Field of the Invention

The present invention relates to a cleaner head for an appliance, and to an appliance comprising such a cleaner head.

Background of the Invention

Appliances for cleaning or treating surfaces may comprise a cleaner head that is in contact with the surface to be cleaned or treated in use. Some appliances utilise liquids, such as water, to clean or treat a surface. Such liquids may be utilised alongside a roller, mop, wipe, or other component for applying a wiping force to the surface.

Summary of the Invention

According to a first aspect of the present invention there is provided a cleaner head for an appliance, the cleaner head comprising: a liquid distribution tank for storing liquid to be distributed to a surface to be cleaned; a roller for contacting the surface to be cleaned; a reservoir having at least one reservoir inlet for receiving liquid from the liquid distribution tank and a reservoir outlet surface comprising at least one reservoir outlet; and a drive component for driving distribution of liquid from the liquid distribution tank to the reservoir, wherein the cleaner head comprises a distribution surface for receiving liquid from the at least one reservoir outlet for distributing the liquid onto the roller, and the distribution surface is substantially parallel to the reservoir outlet surface.

Without a distribution surface, liquid leaving the reservoir via the at least one reservoir outlet is for example deposited onto the roller under pressure and can bounce or splash off or be otherwise ejected from a surface of the roller rather than saturating the roller. This can reduce the efficiency of the cleaner head. Furthermore, liquid ejected from the roller can also escape from the cleaner head and come into contact with the surface to be cleaned, leaving wet spots, or other components of the cleaner head, which may affect safety. However, inclusion of a distribution surface for example means that the liquid exiting the at least one reservoir outlet is deposited onto the distribution surface before flowing onto the roller. This may result in a lower speed of the liquid as the liquid is distributed from the distribution surface onto the roller compared to direct deposition of the liquid from the at least one reservoir outlet onto the roller. This can reduce splashing of liquid from the roller when the liquid is deposited on the roller, allowing the liquid to penetrate and saturate the roller more readily. This may improve the efficiency of the cleaner head and reduce undesirable wet spots on the surface to be cleaned. Arranging the distribution surface substantially parallel to the reservoir outlet surface may be particularly effective at reducing ejection of liquid from the surface of the roller when the liquid is deposited on the roller from the distribution surface compared to other angles between the distribution surface and the reservoir outlet surface. For example, the distribution surface may be parallel to the reservoir outlet surface within manufacturing tolerances, such as within 5 degrees.

The distribution surface may be substantially parallel to the surface to be cleaned when the cleaner head is located on the surface to be cleaned, in use. For example, the distribution surface and the surface to be cleaned may be substantially horizontal, such as within 5 degrees of horizontal. This enables liquid ejection from the roller to be effectively reduced when using the cleaner head to clean horizontal surfaces.

The distribution surface may be below the reservoir outlet surface when the cleaner head is located on the surface to be cleaned, in use. This for example enables the liquid to fall from the reservoir outlet surface onto the distribution surface under gravity, which can reduce the complexity of the cleaner head compared to other arrangements in which the distribution surface is at a different location with respect to the reservoir outlet surface.

The distribution surface need not be directly beneath the reservoir outlet surface when the cleaner head is located on the surface to be cleaned, in use. Instead, the distribution surface may be non-overlapped by the reservoir outlet surface. For example, the reservoir outlet surface may be offset from the distribution surface in a direction parallel to a plane of the distribution surface, such as a horizontal direction. In such cases, the cleaner head may comprise a collection surface overlapped by the reservoir outlet surface when the cleaner head is located on the surface to be cleaned, in use. In other words, the collection surface may be directly beneath the reservoir outlet surface with the cleaner head in use. At least a portion of the collection surface may be angled with respect to the distribution surface. This may aid in urging the liquid deposited on the collection surface from the at least one reservoir outlet towards the distribution surface, for distribution to the roller. The collection surface may be a concave curved surface. This may aid in reducing the speed of the liquid incident on the collection surface, to more gently guide the liquid towards the distribution surface. This may further reduce splashing of the liquid from the surface of the roller when the liquid is deposited from the distribution surface onto the roller.

The distribution surface may be substantially flat. A substantially flat distribution surface, such as flat within manufacturing tolerances, may reduce bouncing of liquid from the distribution surface to a greater extent than otherwise, reducing the risk of liquid being undesirably deposited in unwanted areas within the interior of the cleaner head.

The cleaner head may comprise a mangle located below the distribution surface when the cleaner head is located on the surface to be cleaned, in use. The mangle may be used to scrape dirty liquid and debris from the roller. Locating the mangle below the distribution surface for example means that the dirty liquid and debris scraped by the mangle remains spatially separated from the clean liquid distributed onto the roller by the distribution surface so that the liquid on the roller remains clean before it is brought into contact with the surface to be cleaned.

A distribution structure comprising the distribution surface may abut the mangle. Arranging the distribution structure to abut the mangle for example means that the cleaner head lacks an empty volume between the distribution surface and the mangle into which dirty liquid and debris collected by the mangle may undesirably flow. This may thus further reduce the risk of clean liquid from the at least one reservoir outlet from coming into contact with dirty liquid and debris collected by the mangle.

The distribution surface may be configured to transfer liquid to the roller substantially without transfer of the liquid to the mangle, such as with a negligible amount of liquid from the distribution surface coming into contact with the mangle without first contacting the roller. This may improve efficiency by transferring liquid onto the roller without the liquid contacting the mangle and potentially being scraped away before coming into contact with the surface to be cleaned. In addition, this may mean that the distribution surface and the mangle are not in liquid communication with each other so that dirty liquid and debris from the mangle also is not transferred back to the distribution surface.

A portion of the roller may be located between an edge of the distribution surface and the mangle. This may facilitate straightforward transfer of liquid from the distribution surface onto the roller. The mangle may be at an acute angle with respect to the distribution surface. For example, the mangle may be at an angle of between approximately 30 to 60 degrees with respect to the distribution surface. A mangle with such an angle may be more effective at collecting dirty liquid and debris from the roller.

A distance between the mangle and an edge of the distribution surface facing the roller may be between around 3 millimetres and 4 millimetres. This may further reduce transfer of dirty liquid and debris from the mangle to the distribution surface.

The distribution surface may be elongate along an axis parallel to a rotational axis of the roller. This may facilitate distribution of the liquid from the distribution surface along a length of the roller parallel to the rotational axis of the roller, improving the efficiency with which a surface may be cleaned by the roller.

A distance between an edge of the distribution surface and the roller in a direction parallel to the rotational axis of the roller may be substantially uniform along the axis parallel to the rotational axis of the roller. This may improve the uniformity with which liquid is deposited from the distribution surface onto the roller.

The cleaner head may comprise a plurality of reservoir outlets distributed along the axis parallel to the rotational axis of the roller along a distance of at least 80% of a length of the roller along the axis parallel to the rotational axis of the roller. This may assist the deposition of the liquid from the reservoir outlets, via the deposition surface, onto a substantial length of the roller, such as at least 80% of the roller. This can then enable more efficient deposition of the liquid by the roller on the surface than if a smaller proportion of the length of the roller is wetted by the liquid.

A distance between the distribution surface and the reservoir outlet surface may be between approximately 1.5mm and approximately 1.7mm. This is for example an effective distance to reduce bouncing of the liquid from the surface of the roller when the liquid is deposited from the distribution surface onto the roller.

A depth of the distribution surface, along a short axis of the distribution surface, may be between approximately 4mm and approximately 4.3mm. Such a depth for example allows the liquid to flow laterally onto the roller, which can further reduce ejection of liquid from the surface of the roller when the liquid is deposited from the distribution surface onto the roller compared to other depths.

The cleaner head may comprise a housing comprising a first housing portion and a second housing portion releasably connected to one another, the first housing portion may comprise the liquid distribution tank, the reservoir may be at least partly formed by the second housing portion, and the distribution surface may be defined by a protrusion of the second housing portion. This for example allows the protrusion, and hence the distribution surface, to be formed integrally with the second housing portion. This may improve robustness and simplify fabrication compared to having an additional component to provide the distribution surface.

The cleaner head may comprise a first separating member and a second separating member each separating the distribution surface from the reservoir outlet surface, and the at least one reservoir outlet may be located between the first separating member and the second separating member. The first and second separating members can for example act to guide the flow of the liquid from the at least one reservoir outlet onto the distribution surface. This may reduce flow of the liquid from the sides of the distribution surface and away from the roller, improving efficiency. Furthermore, by reducing flow of the liquid into other locations than the roller, such as regions of the cleaner head including electrical components or regions of the surface to be cleaned, safety of the cleaner head may be improved and/or wet spots on the surface to be cleaned may be reduced.

According to a second aspect of the present invention there is provided an appliance comprising a cleaner head according to the first aspect of the present invention.

The appliance may comprise a main unit, and the cleaner head may be releasably attachable to the main unit. This may enable the functionality of the cleaner head to be selectively provided for the appliance, for example enabling the cleaner head to be swapped for a further cleaner head of different form and/or functionality.

The main unit may comprise a power supply for supplying electrical power to the drive component. This may reduce the need for a separate power supply to be provided in the cleaner head, which may reduce size and/or weight and/or cost of the cleaner head. According to a third aspect of the present invention there is provided an appliance comprising a main unit to which a wet cleaner head is attachable, wherein the main unit comprises: an airflow generator operable during use of the appliance in a first mode in which an airflow is generated and in a second mode in which an airflow is not generated; and a control module configured to: determine whether the wet cleaner head is attached to the main unit; and in response to determining that the wet cleaner head is attached to the main unit, control the airflow generator to operate in the second mode.

An appliance having an airflow generator may be used to perform cleaning utilising an airflow generated thereby, such as vacuum cleaning. Accordingly, in some examples, the appliance may be referred to as a vacuum cleaning appliance. However, the main unit being attachable to a wet cleaner head may allow for the appliance to provide wet cleaning. For example, a wet cleaner head may be for cleaning or treating surfaces using a liquid. For example, the wet cleaner head may comprise a roller or other component configured to contact a surface to be cleaned, and a liquid delivery assembly configured to deliver liquid to the roller or other component. Wet cleaning may be provided via the liquid and/or via motion of the wetted roller or other component against the surface. The wet cleaner head may therefore not utilise the airflow generated by the airflow generator of the main unit in order to provide cleaning. Providing the main unit with a control unit that determines whether the wet cleaner head is attached and, if so, controls the airflow generator to operate in the second mode in which an airflow is not generated (e.g. controls the airflow generator to be off), may therefore help prevent the airflow from being unnecessarily generated. This may, in turn, help the appliance to run more efficiently.

The control module may be further configured to: in response to determining that the wet cleaner head is attached to the main unit, control the main unit to provide power to the wet cleaner head thereby to operate the wet cleaner head. This may help provide for powered wet cleaning to be provided by the wet cleaner head when it is attached to the main unit, but without the airflow generator generating the airflow. This may provide for powerful yet relatively efficient wet cleaning performance. In examples, the wet cleaner head may comprise a drive component (e.g. a liquid pump) for driving distribution of a liquid from a liquid distribution tank to a roller or other component for contacting the surface to be cleaned; and/or a roller drive (e.g. motor) configured to drive rotation of the roller or another component for contacting the surface to be cleaned. The power provided by the main unit to the cleaner head may power one or both of the drive component and the roller drive. The control module may be configured to: determine whether a cleaner head other than the wet cleaner head is attached to the main unit; and in response to determining that a cleaner head other than the wet cleaner head is attached to the main unit, control the airflow generator to operate in the first mode. For example, other cleaner heads may be attachable to the main unit and, unlike the wet cleaner head, may utilise the airflow generated by the airflow generator to perform cleaning. For example, these other cleaner heads may be powered or not powered. Providing that the control unit is configured to determine whether a cleaner head other than a wet cleaner head is attached to the main unit, and if so, control the airflow generator to operate in the first mode in which the airflow is generated may allow that other cleaner heads which do utilise the airflow can be effectively used, whilst still avoiding the unnecessary running of the airflow generator when the wet cleaner head is attached.

The control module may be configured to: in response to determining that a cleaner head other than the wet cleaner head is attached to the main unit, control the main unit to provide power to the cleaner head other than the wet cleaner head so as to operate the cleaner head other than the wet cleaner head. Other cleaner heads may have powered components. For example, such another cleaner head may comprise a roller that has bristles and is driven to rotate by a motor so as to move particles to be cleaned into the airflow. Providing power to cleaner heads other than the wet cleaner head may therefore allow such other cleaner heads to operate, for example in cooperation with the airflow generated by the airflow generator.

The control module may be configured to: determine whether there is any cleaner head attached to the main unit; and in response to determining that there is no cleaner head attached to the main unit, control the airflow generator to operate in the first mode. It may be useful for the airflow generator to generate an airflow when there is no cleaner head attached to the main unit. For example, the main unit itself may be used to perform vacuum cleaning without a cleaning head attached.

The main unit may comprise a terminal for providing power to a cleaner head attached to the main unit in use, and the control module may be configured to: in response to determining there is no cleaner head attached to the main unit, control the main unit so as not to provide power to the terminal. This may help allow for the safe operation of the appliance. For example, the terminal may be exposed to some degree when there is no cleaner head attached to the main unit. Accordingly, not providing power to the terminal when it is detected that no cleaner head is attached to the main unit may help reduce exposure of power to unintended objects. Alternatively, or additionally, not providing power to the terminal when no cleaner head is attached to the main unit may help reduce unintended leakage of electrical energy from the terminal, and hence for more efficient operation of the appliance.

In examples, the control of the airflow generator to operate in the second mode may comprise controlling the main unit to not provide power to the airflow generator and/or the control of the airflow generator to operate in the first mode may comprise controlling the main unit to provide power to the airflow generator. For example, the main unit may comprise a power supply, and the control module may control the power provided by the power supply to the airflow generator. For example, when a wet cleaner head is attached to the main unit, the control module control the power supply to provide no power to the airflow generator so that the airflow generator operates in the second mode and hence does not generate the airflow, whereas when another cleaning head or no cleaning head is attached to the main unit, the control module may control the power supply to provide power to the airflow generator so that the airflow generator operates in the first mode and hence generates the airflow. This may provide a relatively simple and cost-effective means of controlling whether the airflow generator generates the airflow.

The main unit may comprise a terminal for providing power to a cleaner head attached to the main unit in use, and the control module may be configured to: determine whether the wet cleaner head is attached to the main unit based on a current drawn from the terminal in response to a voltage applied to the terminal. In some examples, the control module may be configured to determine which, if any, cleaner head is attached to the main unit based on a current drawn from the terminal in response to a voltage being applied to the terminal by the main unit. This may allow to provide a relatively simple and cost-effective means by which to determine which, if any, attachment is attached to the main unit. For example, the wet cleaner head may draw a first current in response to the applied voltage; another cleaner head may draw a second, different, current in response to the applied voltage; and where there is no cleaner head attached to the main unit, there may be no current drawn in response to the applied voltage.

The control module may be configured to: determine whether the wet cleaner head is attached to the main unit based on a delay with which current is drawn from the terminal in response to the applied voltage. This may allow for a relatively simple and cost- effective means to determine that the wet cleaner head is attached to the main unit, even in the case where the wet cleaner head draws the same or similar magnitude of current as cleaner heads other than the wet cleaner head. In some examples, the control module may be configured to determine which, if any, cleaner head is attached to the main unit based on a delay with which current is drawn from the terminal in response to the voltage being applied to the terminal by the main unit. For example, a wet cleaner head may be configured to delay drawing current from the terminal in response to an applied voltage, a cleaner head other than the wet cleaner head may be configured not to delay drawing current from the terminal in response to the applied voltage. Where no cleaner head is attached to the main unit, no current may be drawn immediately or by the delay. For example, the wet cleaner head may comprise a delay component, such as a delay circuit, configured to delay the draw of current by the wet cleaner head in response to an applied voltage.

The control module may be configured to: determine that the wet cleaner head is attached to the main unit based on current being drawn, from the terminal in response to the applied voltage, in a particular one of a plurality of time periods. This may allow for the wet cleaner head to be reliably detected, for example amongst other cleaner heads or no cleaner head, even when there are slight variations in the delay applied by different wet cleaner heads. This may provide for reliable operation of the appliance. The control module may be configured to determine that a cleaner head other than the wet cleaner head is attached to the main unit based on current being drawn, from the terminal in response to the applied voltage, in a different particular one of the plurality of time periods. The control module may be configured to determine that no cleaner head is attached to the main unit based on no current being drawn, from the terminal in response to the applied voltage, in any of the plurality of time periods. For example, the control module may be configured to monitor the current drawn from the terminal, in response to the applied voltage, in a first time period and in a second, subsequent, time period. Where it is detected that current is drawn in the first time period the control module may determine that a cleaner head other than the wet cleaner head is attached to the main unit. Where it is detected that current is not drawn in the first time period but is drawn in the second time period the control module may determine that the wet cleaner head is attached to the main unit. Where no current is detected as being drawn in either the first time period or the second time period, the control module may determine that no cleaner head is attached to the main unit. In examples, the first time period may have a duration of around 65 to 95 microseconds, and the second time period may have a duration of around 300 to around 350 microseconds. The duration of the second time period may be selected based on the tolerances of the delay component, for example so as to ensure that the delayed current triggered by the application of voltage in the first time period can be detected in the second time period.

Adjacent time periods may be separated from one another by a time gap. This may help improve the reliability with which the cleaner head attached to the main unit can be determined. For example, introducing a time gap may help reduce the likelihood of a current intended to be drawn in one time period being erroneously detected as being drawn in an adjacent time period. As an example, there may be a gap of between around 90 and 110 microseconds between the first time period and the second time period.

The applied voltage may comprise a plurality of voltage pulses, one for each of the plurality of time periods. For example, a first voltage pulse (e.g. lasting for around 90 microseconds) may be applied and the first time period may be a certain time period (e.g. around 65 to 95 microseconds) post commencement of the first voltage pulse (that is, the first time period may start at the start of the first voltage pulse and last for around between 65 and 95 microseconds). If no current draw is detected in the first time period, then a second voltage pulse may be applied (e.g. lasting for around 300 to 350 microseconds). There may be a gap (e.g. 90 to 110 microseconds) in between the pulses where no voltage is applied. The second time period may be a certain time period (e.g. 300 to 350 microseconds) post commencement of the second voltage pulse (that is, the second time period may start at the start of the second voltage pulse and last for around between 300 and 350 microseconds). In examples, if current draw is detected in the second time period then it may be determined that the wet cleaner head is attached to the main unit. In examples, when a current draw is triggered by a voltage pulse of the first time period, but is delayed so as to occur in the second time period, the voltage pulse may nonetheless be again provided in the second time period so that the current draw may occur.

An initial one of the plurality of time periods may have a first duration, and a subsequent time period may have a second duration, the second duration being longer than the first duration. This may help provide that the delayed current draw detected in the second time period can comprise both the current draw triggered by the voltage applied in the initial (e.g. first) time period, and the current draw triggered by the voltage applied in the subsequent (e.g. second) time period. This may, in turn, help ensure that the delayed current draw is detected in the second time period. For example, as mentioned above, an applied voltage may comprise a first voltage pulse of around 90 microseconds, followed by around a 90 to 110 microsecond gap, followed by a second voltage pulse of for between around 300 to 350 microseconds. The first time period may be around 65 to 95 microseconds in duration and may commence when the first voltage pulse commences, the second time period may be between around 300 to 350 microseconds in duration and may commence when the second voltage pulse commences, and there may be a time gap of around 90 to 110 microseconds between the first and second time periods. The delay component of the wet cleaner head may be configured to apply a delay such that current is drawn by the wet cleaner head around, for example, 120 microseconds after application of a voltage. Accordingly, the current draw triggered by the first voltage pulse will occur at around 120 microseconds from the start of the first voltage pulse (and hence not within the first time period), and the current draw triggered by the second voltage pulse will occur at around 120 microseconds from the start of the second voltage pulse (and hence within the second time period). Other values are possible.

The control module is configured to determine whether the wet cleaner head is attached to the main unit in response to a trigger signal indicating that the appliance is to be operated. For example, the control module may be configured to determine which, if any, cleaner head is attached to the main unit in response to the trigger signal indicating that the appliance is to be operated. For example, the trigger signal may comprise a user operating a button or other user interface element to initiate operation of the appliance. The control module may therefore determine which attachment, if any, is attached to the main unit, and perform control as appropriate, on start up or initiation of operation of the device. This may help ensure proper and/or efficient operation of the appliance.

The main unit may comprise a power supply for powering the airflow generator and/or the wet cleaner head. For example, the power supply may be for powering the airflow generator and/or any powered cleaner head attached to the main unit. For example, the power supply may be a battery. Powering the wet cleaner head (or other powered cleaner head) with a power supply of the main unit may reduce the need to provide a separate power supply in the cleaner head itself, which may reduce complexity and cost. The appliance may comprise the wet cleaner head. The wet cleaner head may comprise a delay component configured to delay, by a particular amount, drawing of current by the wet cleaner head from the main unit when a voltage is applied to the wet cleaner head by the main unit. For example, the delay component may be configured so that current is drawn with a delay of around 120 microseconds from the voltage being applied. For example, the delay component may be provided by a delay circuit. Providing the delay by a delay circuit may provide a robust and cost effective way to provide the delay component. The delay circuit may be, for example, an RC (Resistance-Capacitance) based time delay circuit, for example, an RC based time delay circuit comprising a Field Effect T ransistor (FET) transistor such as a Metal Oxide Semiconductor FET (MOSFET). Other delay components such as other delay circuits may be used.

The wet cleaner head may comprise a drive component configured to drive distribution of liquid, and the main unit may be configured to provide power to the drive component when the wet cleaner head is attached to the main unit in use. For example, the drive component (e.g. a liquid pump) may be configured to drive distribution of liquid from a liquid distribution tank to a roller for contacting a surface to be cleaned in use. The wet cleaner head may comprise a roller drive for driving rotation of the roller when the wet cleaner head is attached to the main unit in use. The wet cleaner head comprising the drive component and/or the roller drive may help the wet cleaner head to provide effective wet cleaning.

According to a fourth aspect of the invention, there is provided a cleaner head for an appliance, the cleaner head comprising: a roller for contacting a surface to be cleaned; and a liquid delivery assembly comprising a drive component for driving distribution of liquid to the roller; wherein the drive component is configured to drive the distribution of liquid to the roller in pulses; wherein the drive component is configured to, drive the distribution of liquid for a first duration to generate each pulse; and consecutive pulses are separated by a second duration in which the drive component does not drive the distribution of liquid; and wherein the first duration is between 2% and 9% of the second duration.

Driving the liquid distribution in pulses may help allow for improved control over the delivery of liquid to the roller. For example, the drive component may comprise a pump configured or otherwise controlled to operate in a pulsed or cyclical manner. For example, the pump may be configured to be on (thereby driving the distribution of liquid to the roller) for the first duration and then off (thereby not driving the distribution of liquid to the roller) for the second duration. The pump may be configured or otherwise controlled to repeat this sequence, thereby driving the distribution of liquid to the roller in pulses. As another example, the drive component may comprise a pump and a valve for controlling the passage of liquid from the pump to the roller. For example, the pump may operate continuously, and the valve may be configured or otherwise controlled to open and close in a pulsed or cyclical manner. For example, the valve may be configured to be open (thereby driving the distribution of liquid to the roller) for the first duration and then off (thereby not driving the distribution of liquid to the roller) for the second duration. The valve may be configured or otherwise controlled to repeat this sequence, thereby driving the distribution of liquid to the roller in pulses. In any case, driving the liquid distribution in pulses where the first duration is between 2% and 9% of the second duration may allow for a desired overall liquid delivery rate to be achieved (e.g. averaged over the pulses), but while allowing the pressure at which the liquid is distributed (e.g. during each pulse) to be relatively high. This may be as compared, for example, to driving the liquid distribution continuously. This may, in turn, allow for several benefits. For example, distributing the liquid at relatively high pressure may allow for liquid to be relatively evenly distributed along the roller. For example, the liquid delivery assembly may comprise a reservoir to which liquid is driven by the drive component (e.g. a liquid pump) via a reservoir inlet (e.g. a single inlet), and the reservoir may comprise a plurality of outlets (e.g. eight outlets) via which liquid is delivered to the roller. Driving the liquid at relatively high pressure to the reservoir may allow for the reservoir to fill relatively evenly, and hence for each of the outlets to deliver a similar amount of liquid as one another. This may, in turn, help improve the evenness with which liquid is provided to the roller, which in turn may help improve overall cleaning performance. Further, driving the liquid at relatively high pressure to the reservoir may allow that the pressure is high enough in the reservoir so that liquid is expelled from the outlets. This may provide improved control of the liquid delivery, for example as compared to simply allowing the liquid to drip from the outlets. As another example, driving the liquid at relatively high pressure may allow for clearing of parts of the liquid delivery assembly which might otherwise become clogged up with dirt or other debris. For example, the outlets of the reservoir may be configured to be relatively small (e.g. 1 millimetre in diameter) in order to provide a suitable liquid delivery. Driving the liquid at relatively high pressure may allow for unclogging of such outlets, should that occur during cleaning. The first duration being between 2% and 9% of the second duration may help provide a suitable liquid delivery rate to the roller (e.g. between 25 and 35 millilitres per minute) to provide a desired saturation level of a material of the roller that contacts the surface to be cleaned. For example, the desired saturation level may be between 10% and 30% saturation of the material, e.g. between 25% and 28% saturation of the material. This may, in turn, provide good cleaning performance. In examples where the pulses are provided by controlling the pump to be on for the first duration and off for the second duration, the first duration being between 2% and 9% of the second duration provides that the drive component (e.g. liquid pump) is mostly off (that is, not driving distribution of the liquid), which may help save energy and/or prolong the operating life of the drive component. In examples, the first duration may be around 8% of the second duration or may be around 4% of the second duration. In examples, the first duration may be 0.25 seconds. The second duration may be between 3 seconds and 10 seconds. For example, the second duration may be around 3 seconds or around 6 seconds.

The cleaner head may comprise a roller drive configured to drive rotation of the roller, and the first duration may last for at least one revolution of the roller. For example, the first duration may last for between 2 and 5 revolutions of the roller, for example between around 3.8 and 4.2 revolutions of the roller, for example around 4 revolutions of the roller. Having the first duration last for at least one revolution of the roller may help ensure that liquid is delivered evenly around the entire circumference of the roller. This may in turn help improve the evenness with which a material of the roller that contacts the surface to be cleaned is wetted and/or may help improve the speed with which an even wetting of the material is achieved. The first duration lasting for between 2 and 5 revolutions of the roller, for example between around 3.8 and 4.2 revolutions of the roller, for example around 4 revolutions of the roller, may provide an optimum condition between evenness of liquid distribution, the rate of rotation of the roller, and the duty cycle of the drive component.

The liquid delivery assembly may comprise a reservoir to which liquid is driven by the drive component via a reservoir inlet, and the reservoir may comprise a plurality of outlets via which liquid is delivered to the roller. For example, the plurality of outlets may be arranged along a direction parallel to the rotational axis of the roller. The reservoir and outlets may provide a simple and space efficient means by which to distribute the liquid across the roller, for example across a material of the roller that contacts the surface to be cleaned. The liquid delivery assembly may comprise a distribution surface for distributing liquid onto the roller, the distribution surface extending in a direction parallel to the rotational axis of the roller, the distribution surface being provided with liquid from the outlets of the reservoir. The distribution surface may reduce spitting of liquid from the roller (that is, a material of the roller that contacts the surface to be cleaned) when the liquid is delivered to the material. For example, in some cases, spraying liquid directly onto the material from the outlets may cause the liquid to impact the rotating roller material at relatively high speeds, which may in turn cause some of the liquid to bounce off the material rather than being absorbed by it. However, by providing a distribution surface that is provided with liquid from the outlets and which distributes the liquid onto the material, the liquid can be slowed down before contacting the material. This may in turn reduce spitting and hence improve the consistency with which liquid is absorbed into the material.

The cleaner head may further comprise a liquid distribution tank for storing liquid to be distributed to the roller by the drive component. Providing a liquid distribution tank in the cleaner head may allow the cleaner head to be portable. As another example, this may allow for the liquid to be stored close to the liquid delivery assembly, which may help minimise piping required to provide liquid to the roller.

In examples, the liquid delivery assembly may be configured to deliver liquid to the roller at a rate of between 25 and 35 millilitres per minute, for example at a rate of 30 millilitres per minute. The surface area of a material of the roller that contacts the surface to be cleaned may be between 800 and 900 square centimetres, for example around 820 square centimetres. For example, the radius of the roller at the material may be around 58 mm, and the length of the roller may be around 226 mm. The material may be microfibre having a density of between 46500 and 85250 fibres per square centimetre. These parameters may help provide a desired cleaning performance and/or saturation level of a material of the roller (e.g. between 25% and 28%).

The liquid delivery assembly may be configured to deliver liquid to the material so that the material is between 10% and 30% saturated with liquid, for example between 25% and 28% saturated with liquid The material of the roller being between 10% and 30% saturated with liquid has been found to provide good cleaning performance, with the saturation being between 25% and 28% providing particularly good cleaning performance. Specifically, this has been found to provide particularly useful wetness of the surface to be cleaned. For example, if the saturation is too low, then not enough liquid may be applied to the surface to be cleaned via the roller and hence cleaning performance may be sub-optimal. On the other hand, if the saturation is too high, too much liquid may be applied to the surface to be cleaned via the roller, and the surface may accordingly become unacceptably wet. It has been found that a liquid saturation of the material of the roller between 10% and 30%, and in particular between 25% and 28%, provides a sufficient amount of liquid to the surface to be cleaned via the roller to allow good cleaning performance but without causing the surface to become unacceptably wet. In examples, a liquid saturation of 28% may be particularly preferred. In examples, the liquid may be water.

The cleaner head may comprise a mangle configured to remove liquid and/or debris from the material. The mangle may span the material in a direction parallel to the axis of the roller. The mangle may have a thickness of around 2 millimetres. The mangle may penetrate into the material a distance of between 2 and 3 millimetres, for example 2.5 millimetres. That is, the mangle may extend beyond an outer diameter of the material of the roller in use, by a distance of between 2 and 3 millimetres, for example 2.5 millimetres. The thickness (e.g. the pile thickness) of the material of the roller may be around 5 millimetres. Accordingly, in examples, the mangle may penetrate the material between 40% and 60% of the thickness of the material, for example 50% of the thickness of the material. The mangle may be provided by a strip or bar that contacts the material, for example penetrates into the material, such as into the microfibres of a microfibre material. The mangle may help remove dirty liquid and/or debris from the material, for example which has been generated by the cleaning of the surface or picked up from the surface. For example, the rotation of the roller may urge the material against the mangle and cause excess liquid and/or debris to become separated therefrom. This may be transferred, for example, into a liquid collection tank, which the cleaner head may also comprise. Alternatively or additionally, the mangle, in cooperation with the liquid delivery assembly, may help maintain a desired liquid saturation of the material over a period of time and/or during different uses. For example, the mangle may be configured so as to remove liquid from the material when the saturation goes beyond a desired level (e.g. 28%). For example, this may be achieved by the mangle penetrating into the material a distance of between 2 and 3 millimetres. For example, in cases where the cleaner head is applied to clean a wet surface causing the material to increase above 28% liquid saturation, the mangle may act to remove the excess liquid to reduce the saturation to desired levels (e.g. 28%) again. Similarly, in cases where excess liquid is delivered by the liquid delivery assembly that might otherwise take the liquid saturation of the material beyond desired levels, the mangle may act to remove the excess liquid to maintain the saturation at desired levels (e.g. 28%). Accordingly, the mangle may allow for a relatively simple liquid delivery assembly to be provided (for example one which need not necessarily actively monitor the liquid saturation of the material), but whilst still allowing for liquid saturation of the material in a desired range (e.g. 25% to 28%) to be maintained.

The cleaner head may comprise a roller drive, and the roller drive may be configured to drive rotation of the roller at a rate between 500 and 1200 revolutions per minute, for example between 900 and 1000 revolutions per minute. This may be the steady state operational rotational speed of the roller. Rotating the roller at between 500 and 1200 revolutions per minute, for example between 900 and 1000 revolutions per minute may help provide good cleaning performance. In examples, the roller may have a length of between 225 and 227 millimetres, for example around 226 millimetres. In examples, the roller may have a radius of around 60 millimetres. It will be appreciated that the radius of the roller may vary slightly depending on, for example, whether the material is wet or dry. For example, when the material is wet, the roller may have an overall radius of 58 millimetres, and when the material is dry, the roller may have an overall radius of 62 millimetres, for example.

According to a fifth aspect of the present invention, there is provided an appliance comprising a cleaner head according to the fourth aspect.

The appliance may comprise a main unit, and the cleaner head may be releasably attachable to the main unit. This may enable the functionality of the cleaner head to be selectively provided for the appliance, for example enabling the cleaner head to be swapped for a further cleaner head of different form and/or functionality.

The main unit may comprise a power supply for supplying electrical power to the drive component and/or the roller drive. This may reduce the need for a separate power supply to be provided in the cleaner head, which may reduce size and/or weight and/or cost of the cleaner head.

Optional features of aspects of the present invention may be equally applied to other aspects of the present invention, where appropriate.

Brief Description of the Drawings Figure 1 is a perspective view of a cleaner head;

Figure 2 is an exploded perspective view of the cleaner head of Figure 1 , showing first and second housing portions;

Figure 3 is a perspective view of the first housing portion of Figure 2 in isolation;

Figure 4 is a bottom plan view of the first housing portion of Figure 3;

Figure 5 is an upper plan view of the first housing portion of Figure 3;

Figure 6A is a perspective view illustrating a removable cover of a liquid collection tank of the first housing portion of Figure 3, and Figure 6B is a cross-sectional view of a squeegee of the first housing portion of Figure 3;

Figure 7 is a perspective view of the second housing portion of Figure 2 in isolation;

Figure 8 is a perspective view of the second housing portion of Figure 7 with a wall section removed;

Figure 9 is a right side view of the second housing portion of Figure 7;

Figure 10 is a schematic view of the cleaner head of Figure 1 with an upper wall and a side wall of its housing removed;

Figure 11 is a schematic cross-sectional view taken along a central depth line of the cleaner head of Figure 1 ;

Figure 12 is an enlarged view of the circled region denoted A in Figure 11; and

Figure 13 is a schematic illustration of an appliance comprising the cleaner head of Figure 1.

Detailed Description of the Invention A cleaner head 10 is illustrated in Figures 1 to 2.

The cleaner head 10 comprises a housing 12, a roller 14, and an attachment mechanism 16. The roller 14 is rotatably connected to the housing 12 such that it rotates about a rotational axis R (see Figure 2) that is substantially parallel to a width direction W of the housing 12. The housing 12 comprises a first housing portion 18 and a second housing portion 20 releasably connected to each other.

The first housing portion 18 is illustrated in Figures 3 to 6, and comprises a right side wall 22, a tank assembly 24, a mounting member 26, a catch mechanism 28, and a projection in the form of a guide strip 30. The right side wall 22 is generally elongate in form, and extends generally in a depth direction D of the cleaner head 10. The tank assembly 24 and the mounting member 26 are each fixedly connected to the right side wall 22 (allowing the mounting member 26 to be fixedly connected to the tank assembly 24). The tank assembly 24 and the mounting member 26 extend from the right side wall 22 such that the tank assembly 24 and the mounting member 26 are located within the housing 12 when the cleaner head 10 is assembled. The catch mechanism 28 and the guide strip 30 are generally centrally located along the right side wall 22.

The mounting member 26 is located at a front end 32 of the right side wall 22, with the tank assembly 24 located rearwardly of the mounting member 26. The front end 32 of the right side wall 22 is generally shaped to correspond to the curvature of the roller 14, and has a region of reduced radius such that the roller 14 is partially exposed at the front of the housing 12 when the cleaner head 10 is assembled and the roller 14 contacts the surface to be cleaned.

The tank assembly 24 comprises a liquid distribution tank 34 for storing liquid to be distributed to a surface to be cleaned and a liquid collection tank 36 for collecting liquid from the surface to be cleaned. The liquid collection tank 36 and the liquid distribution tank 34 are fixedly connected to one another. The liquid distribution tank 34 is hollow in form and has a curved rear wall 37, a flat base wall 38, a wheel 40, an inlet 42, and a closure 44. The wheel 40 is disposed in the flat base wall 38. The inlet 42 is covered and closed by the closure 44 in Figures 4 and 5, and has the form of an aperture defined by a neck with an external screw thread that cooperates with an internal screw thread of the closure 44. The inlet 42 is located on the liquid distribution tank 34 such that the inlet 42 is located within an interior volume of the housing 12 when the cleaner head 10 is assembled. The inlet 42 faces in a first direction W along the housing 12 of the cleaner head 10. This first direction is a direction toward a sidewall of the housing 12 when the cleaner head 10 is located on a surface to be cleaned in use.

The closure 44 has the form of a cap that covers the inlet 42, and is removable from the inlet 42 via twisting. The closure 44 comprises a valve member 46 that enables fluidic communication between an interior of the liquid distribution tank 34 and a drive component comprising a pump 84 (see Figure 8).

The liquid distribution tank 34 has an internal volume of around 300ml. The liquid distribution tank 34 extends for substantially the full height direction H of the cleaner head 10, but only extends partially (for a little over 50%) across a width direction W of the housing 12 of the cleaner head 10. The liquid distribution tank 34 is located at a rear end 48 of the right side wall 22, and forms part of a rear surface of the cleaner head 10 when the cleaner head 10 is assembled.

The liquid collection tank 36 comprises a main tank body 50, an upper plate 52, and a removable cover 54 releasably connected to the main tank body 50 via an interference fit. The liquid collection tank 36 further comprises a front wall 56 and a surface contact member in the form of a squeegee 58. The squeegee 58 and removable cover 54 are entirely removable from the main tank body 50. The liquid collection tank 36 is located generally centrally along the right side wall 22, such that the liquid collection tank 36 is located between the liquid distribution tank 34 and the mounting member 26. A bottom surface of the liquid collection tank 36 and a bottom surface of the liquid distribution tank 34 are substantially aligned.

The main tank body 50 is generally cuboidal and hollow in form, and extends across substantially the entirety of the width direction W of the cleaner head 10 when the cleaner head 10 is assembled. An upper region of the main tank body 50 is open such that the hollow interior of the main tank body 50 is accessible via the upper region. The main tank body 50 has an internal volume of around 360ml, giving the liquid collection tank 36 an internal volume 20% greater than the internal volume of the liquid distribution tank 34.

The upper plate 52 is generally solid and planar in form, and is fixedly connected to a rear section of a periphery of the upper region of the main tank body 50 such that the upper plate 52 overlies around 50% of the upper region of the main tank body 50. The removable cover 54 is selectively locatable underneath the upper plate 52 such that the removable cover 54 overlies the upper region of the main tank body 50.

Referring to Figure 6A, the removable cover 54 is generally rectangularly shaped in plan view, and has an outer periphery 60, an inner periphery 62, a sloped surface 64, and a handle in the form of a pull-tab 66, and mounting wings 67. The sloped surface 64 slopes from the outer periphery 60 to the inner periphery 62 such that the inner periphery 62 is located a lower height relative to the outer periphery 60 when the removable cover 54 is located on the main tank body 50. The pull tab 66 is located on a front periphery of the removable cover 54 and is facing outwardly from an upper surface of the cover 54 (in particular, it is upstanding from the sloped surface 64). The inner periphery 62 defines an elongate slot that acts as a combined inlet/outlet 65 of the liquid collection tank 36. The combined inlet/outlet 65 may be located symmetrically about a center line of the liquid collection tank 36. Due to the sloped surface 64, the combined inlet/ outlet 65 is located at a height lower than a height of the main tank body 50. The combined inlet/outlet 65 faces in a second direction H along the housing 12 of the cleaner head 10, where the second direction H is different to the first direction W in which the inlet 42 of the liquid distribution tank 34 faces. As shown in Figure 1 , the second direction H is substantially orthogonal to the first direction W and to the rotational axis R, and is a direction toward an upper surface of the housing 12 when the cleaner head 10 is located on a surface to be cleaned in use. The mounting wings 67 extend from sides of the outer periphery 60 near a front region of the outer periphery 60, and are shaped and dimensioned to be received between the upper plate 52 and the front wall 56 of the liquid collection tank 36. The pull tab 66 is spaced from the combined inlet/outlet 65 by virtue of its location on the sloped surface 64.

The front wall 56 is arcuate in form, and is shaped to generally correspond to the curvature of the roller 14. A lower region of the front wall 56 is shaped and spaced from the main tank body 50 to define a channel within which the squeegee 58 is received. The channel is open at one end to enable the squeegee 58 to slide into and out of the channel.

The squeegee 58 is formed of a resiliently deformable material, and is shaped such that the squeegee 58 is an extension of the front wall 56 when located within the channel. When located within the channel, the squeegee 58 extends from the front wall 56 such that a surface of the squeegee 58 and a surface of the front wall 56 form a continuous surface. As shown in Figure 6B, a rear portion of the squeegee 58 includes an elongate element 581 extending from a top surface of the squeegee 58. The elongate element 581 includes a first elongate recess 582a and a second elongate recess 582b. Referring to Figure 11 , the arcuate front wall 56 ends with a first elongate protrusion 562a. A second elongate protrusion 562b extends from the bottom of the main tank body 50, and is arranged vertically below the first elongate protrusion 562a. To locate the squeegee 58 within the channel, the squeegee 58 is slid relative to the main tank body 50, and the first 562a and second 562b elongate protrusions are received within the first 582a and second 582b elongate recesses respectively. The squeegee 58 extends to a position slightly lower than a lower surface of the main tank body 50 when located within the channel. A vertical gap G (see Figure 3) between the lower surface of the main tank body 50 and the surface to be cleaned is thus formed when the cleaner head is in use. As the roller 14 rotates, the rotational energy from the roller 14 helps to scoop the liquid (from the surface to be cleaned) up along the arcuate front wall 56. The vertical gap G is dimensioned so that it is small enough to prevent dirty liquid from the surface being cleaned to pass beyond the squeegee toward the rear of the cleaner head 10, and large enough to prevent scratching of the surface by the main tank body 50. A height (along the direction H in Figure 1) of this vertical gap G may range from about 0.2mm to 1 ,5mm.

As previously noted, the mounting member 26 is located at the front end 32 of the right side wall 22. The mounting member 26 is releasably connected to the roller 14 and rotatably mounts the roller 14 within the housing 12. The mounting member 26 is shaped and dimensioned to be received within, and engage with, the roller 14. The mounting member 26 is fixedly connected to the right side wall 22, yet comprises a bearing assembly (not shown) to enable rotation of the roller 14 when connected to the mounting member 26. Further details of the mounting member 26 will be apparent to a person skilled in the art, and so will not be described here for sake of brevity.

The catch mechanism 28 is located substantially centrally along the right side wall 22, above the liquid distribution tank 34. The catch mechanism 28 comprises a depressible button 70 and a hook 72 movable in response to movement of the depressible button 70. The hook 72 is releasably engageable with a corresponding latch (not shown) formed on an underside of an upper wall 74 (see Figure 7) of the second housing portion 20. The guide strip 30 is elongate in form and extends in the width direction W to a similar extent as that of the liquid collection tank 36. The guide strip 30 is spaced vertically apart from the upper plate 52, and is shaped and dimensioned to be received within a guide channel 94 of the second housing portion 20. The guide strip 30 has a generally T- shaped cross-sectional shape.

The second housing portion 20 is illustrated in Figures 7 to 12. The second housing portion 20 comprises an upper wall 74, a left side wall 76, control circuitry 78, a drive mechanism in the form of a roller drive 80, a pump compartment 82, a pump 84, a liquid tube 86, an intermediate plate 87, a reservoir 88, a distribution surface 90, a mangle 92, and a guide channel 94. The roller 14 is rotatably connected to the second housing portion 20.

A front end of the upper wall 74 is shaped to correspond to the curvature of the roller 14, and a planar portion of the upper wall 74 comprises a notch 96 shaped and dimensioned to receive the depressible button 70 of the catch mechanism 28.

The left side wall 76 is generally elongate in form, and extends in the depth direction D of the cleaner head 10. The outer surface of the left side wall 76 is the same shape as that of the right side wall 22. The left side wall 76 is hollow in form, and defines a compartment 98 within which the control circuitry 78 is housed. The compartment 98 is sealed from any regions within the housing 12 that contain liquid in use. An inner surface of the left side wall 76 comprises a locating feature in the form of a locating ridge 77 that generally corresponds to a side surface of the liquid collection tank 36.

The control circuitry 78 comprises appropriate control circuitry for driving the roller drive 80 and the pump 84. Further details of how the control circuitry 78 drives the roller drive 80 and the pump 84 will be provided hereafter. The control circuitry 78 also comprises a delay component, specifically a delay circuit, the functionality of which will be discussed hereafter.

The roller drive 80 is located at, and fixedly connected to, a front end 100 of the left side wall 76 at a similar position to which the mounting member 26 is connected to the right side wall 22 of the first housing portion 18. The roller drive 80 comprises an appropriate torque generator, such as a motor, for generating a torque to drive rotation of the roller 14. The roller drive 80 is shaped and dimensioned to fit within an interior of the roller 14, such that the roller drive 80 is located internally of the roller 14 with the roller 14 and the roller drive 80 concentric when the cleaner head 10 is assembled. The roller drive 80 is controlled by the control circuitry 78 to operate at a rate of rotation of around 900- 1000rpm in a steady state. Steady state operational speeds in the region of 500- 1200rpm are also envisaged.

The pump compartment 82 is substantially hollow in form, and is shaped and dimensioned to receive the pump 84 therein. The pump compartment 82 is further shaped and dimensioned to correspond to a projected footprint of the liquid distribution tank 34. The pump compartment 82 is located at a rear end 102 of the left side wall 76, and extends partially in the width direction W of the cleaner head 10. The pump compartment 82 has an aperture (not shown) which enables the pump 84 to connect to the valve member 46 of the closure 44 of the liquid distribution tank 34.

The pump 84 is any appropriate pump for driving liquid from the liquid distribution tank 34 to the reservoir 88, as will be discussed in more detail hereafter. The pump 84 is controlled by the control circuitry 78 to operate in a pulsed or cyclical manner, with the pump 84 controlled to be on for a first duration, to be off for a second duration, and so on. In other words, the pump 84 is on (i.e. drives the distribution of liquid) for the first duration to generate each pulse and consecutive pulses are separated by the second duration in which the drive component does not drive the distribution of liquid. The first duration lasts for at least one revolution of the roller 14. The first duration may be 0.25 seconds and the second duration may be 6 seconds, which equates to the first duration being around 4% of the second duration. With a roller speed of between around 900rpm and 10OOrpm, the first duration of 0.25 seconds equates to the pump 84 being controlled to be on for between around 3.8 and 4.2 revolutions of the roller 14. With a roller speed of between around 500rpm and 1200rpm, the first duration of 0.25 seconds equates to the pump 84 being controlled to be on for between around 2 and 5 revolutions of the roller 14. In other examples, the pump 84 may be controlled to be off for a duration of between around 3 and 10 seconds. In still other examples, the first duration may be between around 2% and 9% of the second duration. In yet still other examples, there may be a valve for controlling the passage of liquid from the pump 84. For example, the pump 84 may operate continuously, and the valve may be configured or otherwise controlled to open and close in a pulsed or cyclical manner. Referring to Figure 10, the liquid tube 86 extends from the pump 84 to the reservoir 88 along the intermediate plate 87. The intermediate plate 87 is fixedly connected to the left side wall 76 at a region between the front 100 and rear 102 ends of the left side wall 76, and is vertically spaced apart from the upper wall 74. An upper surface of the intermediate plate 87 comprises a dividing wall 104 and a lower surface of the intermediate plate 87 comprises the guide channel 94 (see Figure 9). The dividing wall 104 extends across the width of the intermediate plate 87, and, together with the upper wall 74 defines a guide region 106 and a reservoir region 108.

The guide region 106 is a hollow cavity that acts to guide the liquid tube 86 from the pump 84 to the reservoir 88, and to guide electrical looming from the attachment mechanism 16 to the control circuitry 78 within the compartment 98. The liquid tube 86 extends through a gap in the dividing wall 104 to bridge the guide region 106 and the reservoir region 108.

The guide channel 94 extends across the lower surface of the intermediate plate 87 in the width direction W of the cleaner head 10. The guide channel 94 is shaped and dimensioned to receive the guide strip 30 of the first housing portion 18. An end of the guide channel 94 opposite to the left side wall 76 is open such that the guide strip 30 can be slidably received within the guide channel 94.

Referring to Figure 12, the reservoir 88 is at least partly formed by the second housing portion 20 and is defined by the upper surface of the intermediate plate 87 in the reservoir region 108, reservoir side walls 110, and a reservoir cover 91 located between lower surface of the upper wall 74 of the second housing portion 20 and the upper ends of the reservoir walls 110. The reservoir 88 is generally cuboidal in form and is elongate along an axis parallel to a rotational axis of the roller 14. A seal 112 (which may include silicon) is located about a periphery of the reservoir side walls 110, in particular, between the side walls 10, the reservoir cover 91 and the intermediate plate 87. The reservoir side walls 110 are shaped such that the reservoir 88 extends across the width direction W of the cleaner head 10, and has a width in the direction W of around 202mm. The reservoir 88 extends for around 90% of a length of the roller 14 (where the length of the roller 14 extends along the W direction shown in Figure 1), although the reservoir 88 extending for at least 80% of the length of the roller 14 is also envisaged. The reservoir 88 has an interior volume of around 1444mm ³ . An interior volume of up to around 1571 mm ³ is also envisaged. The reservoir 88 has a reservoir inlet 114 and eight reservoir outlets 116, although between 6 to 10 reservoir outlets are also envisaged. The reservoir inlet 114 comprises a circular aperture formed centrally along a rear one of the reservoir side walls 110, in a reservoir inlet surface 115 which is a side surface of the reservoir 88 facing the liquid distribution tank 34. The reservoir inlet 114 is in fluid communication with the liquid tube 86 and receives liquid from the liquid distribution tank 34. The reservoir inlet 114 has a radius in the region of 1.25mm, although radii in the region of 1.00mm to 1.50mm are also envisaged.

The reservoir outlets 116 are spaced substantially evenly along a length of the reservoir 88 along an axis parallel to the rotational axis of the roller 14. Further, they are offset from the reservoir inlet 114 along the axis parallel to the rotational axis of the roller 14. The reservoir outlets 116 comprise generally circular apertures formed in a reservoir outlet surface 117 of the intermediate plate 87 in the reservoir region 108, which is a base surface of the reservoir 88. Each reservoir outlet 116 has a radius of around 1.00mm, and the reservoir outlets 116 are spaced by around 28.00mm along the width direction W of the cleaner head 10. The reservoir outlets 116 cover a length extending to around 90% of a length of the roller 14, although the reservoir outlets 116 covering a length of at least 80% of the length of the roller 14 is also envisaged. The cross-sectional area of the reservoir inlet 114 is larger (e.g. less than 3 times larger) than the cross- sectional area of each reservoir outlet 116. In one example, the reservoir inlet 114 has a radius of around 1.25 times the radius of an individual reservoir outlet 116, whilst the reservoir inlet 114 has a radius of around 0.16 times the combined radius of the reservoir outlets 116. A ratio of a total combined cross-sectional area of the reservoir outlets 116 to a cross-sectional area of the reservoir inlet 114, and a ratio of an interior volume of the reservoir 88 to a total combined cross-sectional area of the reservoir outlets 116 are such that in use, liquid exits the reservoir 88 substantially uniformly from the plurality of reservoir outlets 116. The combined cross-sectional area of the reservoir outlets 116 is around 5 times the cross-sectional area of the reservoir inlet 114. The interior volume of the reservoir 88 is around 1444 times the radius of each individual reservoir outlet 116, and is around 181 times the total combined cross-sectional area of the reservoir outlets 116. Such a configuration of the reservoir 88, in combination with the pulsed delivery cycle of the pump 84 mentioned previously, provides a water flow rate of around 30ml/min in the reservoir 88, alongside a pressure of around 13.5kPa to 14.5kPa in the reservoir 88. Radii of between 0.80mm and 1 ,20mm are also envisaged for the reservoir outlets 116, as is a spacing of around 25.00mm to 30.00mm between each reservoir outlet 116. Thus, a combined cross-sectional area of the reservoir outlets 116 of between around 2.5 and 10 times the cross-sectional area of the reservoir inlet 114, an interior volume of the reservoir 88 of between 150 to 400 times the combined cross-sectional area of the reservoir outlets 116, an interior volume of the reservoir 88 of between 1300 to 2800 times the individual cross-sectional area of each of the reservoir outlets 116, and an interior volume of the reservoir 88 of between 900 to 1900 times the cross-sectional area of reservoir inlet 114 are also envisaged. Variations in size of the reservoir inlet 114 and the reservoir outlets 116 can lead to water flow rates in the reservoir 88 of between 25ml/min and 35ml/min. In other words, liquid is delivered to the pile 122 of the roller 14 at a rate of between 25ml/min and 35ml/min.

The distribution surface 90 is defined by a protrusion 118 of the second housing portion 20, where the protrusion 118 extends from the lower surface of the intermediate plate 87 underneath the reservoir outlets 116. The protrusion 118 forms a distribution structure comprising the distribution surface 90 for distributing liquid onto the pile 122 of the roller 14. The distribution surface 90 is below the reservoir outlet surface 117 (but nonoverlapped by this surface 117) when the cleaner head 10 is located on the surface to be cleaned, in use. The distribution surface 90 is substantially planar in form (in other words, substantially flat), and extends substantially parallel to the planar portion of the upper wall 74 (and substantially parallel to the reservoir outlet surface 117 and the surface to be cleaned when the cleaner head is located on this surface, in use). The distribution surface 90 is thus elongate along an axis parallel to a rotational axis of the roller 14 (R, illustrated in Figure 2, which is parallel to the width direction W of the cleaner head 10), with a substantially uniform distance between the edge of the distribution surface 90 and the roller 14 (indicated in Figure 12 using the reference numeral g). The distance g is taken in a direction perpendicular to the rotational axis of the roller 14 (R, shown in Figure 2) and along the depth direction D of the cleaner head (shown in Figure 1), and is very small in the example of Figure 12. However, it is envisaged that the distance between the edge of the distribution surface 90 and the roller 14 may be larger in other cases.

The distribution surface 90 is located around 1.6mm below each reservoir outlet 116 (indicated as a height h in Figure 12, which is parallel to a height direction H of the cleaner head 10 as shown in Figure 1 and represents a distance between a plane including the reservoir outlet surface 117 and a plane including the distribution surface 90). The distribution surface 90s has a depth d in the depth direction D of the cleaner head (in other words, a depth d along a short axis of the distribution surface 90) of around 4.1 mm. Distances of around 1.5mm to 1.7mm between the distribution surface 90 and the reservoir outlet surface 117(corresponding to heights h as shown in Figure 12), are also envisaged, as are depths d in the region of 4.0mm to 4.3mm. Although not illustrated, dividers are positioned between adjacent ones of the reservoir outlets 116 along the distribution surface 90. The reservoir outlets 116 are positioned between first and second separating members 119a, 119b that separate the distribution surface 90 from the reservoir outlet surface 117. The dividers are the same as the separating members 119a, 119b but positioned between two adjacent reservoir outlets 116 rather than at each end of the reservoir outlet surface 117.

The protrusion 118 also defines a collection surface 123 which is directly beneath the reservoir outlets 116, and is thus overlapped by the reservoir outlet surface 117. The collection surface 123 has a concave curved form, and extends substantially parallel to the planar portion of the upper wall 74. At least a portion of the collection surface 123 is angled with respect to the distribution surface. Liquid deposited on the collection surface 123 by the reservoir outlets 116 is urged by the collection surface 123 towards the distribution surface 90. The distribution surface 90 adjoins the collection surface 123 and is offset from the reservoir outlets 116 horizontally.

The mangle 92 is an elongate protrusion affixed to an underside of the intermediate plate 87, where a part of the mangle 92 is positioned below the distribution surface 90. A thickness TM of the mangle may be around 2mm. The protrusion 118, which in this case forms a distribution structure comprising the distribution surface 90, abuts the mangle 92. The distribution structure transfers liquid to the roller 14 substantially without transfer of the liquid to the mangle 92. The mangle 92 extends forwardly of the distribution surface 90, with a vertical distance v of around 3.4mm between the edge of the distribution surface 90 (facing the roller 14) and the mangle 92. The vertical distance v is in a direction perpendicular to the rotational axis R of the roller 14 and is parallel to a height direction H of the cleaner head 10. Vertical distances v of around between 3.0mm and 4.00mm are also envisaged. As shown in Figure 12, a portion of the roller 14 is located between the edge of the distribution surface 90 and the mangle 92. The mangle 92 projects at an acute angle 0 of approximately 30 to 60 degrees (see Figure 11) with respect to the distribution surface 90 and relative to an axis of rotation of the roller 14 from a plane passing through the rotational axis of the roller 14 and parallel to the surface to be cleaned when the cleaner head 10 is located on the surface to be cleaned in use. The mangle 92 is dimensioned to extend around 2.5mm into the roller 14 (with such extension labelled E in Figure 12), as will be discussed in more detail hereafter. The mangle 92 is thus at an acute angle 0 (in this case of between approximately 30 to 60 degrees) relative to the distribution surface 90. Penetration depths E of between 2mm and 3mm are also envisaged.

The roller 14 comprises a core 120 and a material for contacting a surface to be cleaned where the material is in the form of a pile 122. The core 120 is generally cylindrical (with a cylindrical base surface) and hollow in form. An interior of the core 120 is provided with fixing mechanisms for releasably fixing the roller 14 to the roller drive 80 and the mounting mechanism 26. Details of such fixing mechanisms are not pertinent to the present invention, and so will not be described here for sake of clarity. A diameter of the core 120 is sufficiently large that the roller drive 80 can be received within the core 120. The pile 122 is a microfibre pile with a density of between 46,500 and 85,250 fibres/cm ² . The pile 122 has a thickness T of around 5mm. The roller 14 as a whole has a radius of around 62mm when dry, and around 58mm when wet. The roller 14 has a length of around 226mm, although lengths in the region of 225mm and 227mm are also envisaged. In other words, a surface area of the pile 122 is between 800 and 900 square centimetres.

As previously noted, the cleaner head 10 comprises an attachment mechanism 16. The attachment mechanism 16 comprises a lower portion 124 and an upper portion 126. The lower portion 124 is hingedly mounted to a central region of the upper wall 74 of the second housing portion 20, such that the lower portion 124 can move in a plane defined by the depth D and height H directions of the cleaner head 10. The upper portion 126 is hingedly mounted to the lower portion 124 to enable the upper portion 126 to move relative to the lower portion 124 in a plane defined by the width W and height H directions of the cleaner head 10.

The upper portion 126 comprises a connection formation 128, and looming, which isn’t shown for sake of clarity. The connection formation 128 comprises a catch for releasably connecting to either a wand 204 or a main unit 202 of an appliance 200. Details of the catch are not pertinent to the present invention, and will not be described here for sake of brevity. The connection formation 128 is tubular in form and solid, such that there is no airflow path therethrough. The looming provides an electrical connection between the main unit 202 of the appliance 200 and the cleaner head 10.

The cleaner head is shown in an assembled configuration in Figure 1 and in a disassembled configuration in Figure 2.

To assemble the cleaner head 10, the roller 14 is connected to the roller drive 80, and the first 18 and second 20 housing portions are moved toward one another via a sliding motion along the width direction W of the cleaner head 10. The guide strip 30 is received in the guide channel 94 to guide the relative sliding motion. As a result of the sliding motion, the first 18 and second 20 housing portions are brought together and the hook 72 of the catch mechanism 28 engages the latch of the upper wall 74 of the second housing portion 20 to secure the first 18 and second 20 housing portions in place relative to one another. Thus, the first 18 and second 20 housing portions are slidably connected to one another along an axis parallel to the rotational axis R of the roller 14.

Bringing together the first 18 and second 20 housing portions moves the mounting member 26 into contact with the roller 14, such that the roller 14 is rotatably connected to the housing 12 by each of the mounting member 26 and the roller drive 80. The locating ridge 77 locates the tank assembly 24 relative to the second housing portion 20. In particular, the locating ridge 77 defines a recess for receiving a portion (side wall) of the liquid collection tank 36. The valve member 46 of the closure 44 of the liquid distribution tank 34 is brought into contact with the pump 84 such that a fluidic connection is made between the liquid distribution tank 34 and the pump 84. When the first 18 and second 20 housing portions are assembled together, the roller 14 is located at a first end of the housing 12 and the liquid distribution tank 34 is located at a second end of the housing 12 (the first and second ends being opposite to each other along the depth direction D of the housing 12). The liquid collection tank 36 is located between the liquid distribution tank 34 and the roller 14 in the depth direction D of the housing 12. Further, both the inlet 42 of the liquid distribution tank 34 and the combined inlet/outlet 65 of the liquid collection tank 36 are located within an internal volume of the housing 12. Additionally, the liquid distribution tank 34 and the pump 84 are adjacent to one another across the width of the housing 12. In other words, each of the liquid distribution tank 34 and the pump 84 extends partially across the width of the housing 12. In the assembled configuration, the roller 14 extends along the width of the cleaner head 10 between the right side wall 22 and the left side wall 76 of the respective first 18 and second 20 housing portions, at the front of the cleaner head 10. The reservoir 88 overlies a rear portion of the roller 14. The mangle 92 extends into the pile 122 of the roller 14. The liquid collection tank 36 is located rearwardly of the roller 14, with the front wall 56 spaced slightly from the roller 14 to enable rotation of the roller 14 within the housing 12. The combined inlet/outlet 65 of the liquid collection tank 36 faces toward the upper wall 74 of the cleaner head 10. The mangle 92 is positioned between 3 and 5mm higher (with such a distance labelled m in Figure 11) than the combined inlet/outlet 65 of the liquid collection tank 36. The liquid collection tank 36 extends across the width direction W of the cleaner head 10 to a similar extent to that of the roller 14 between the right side wall 22 and the left side wall 76 of the respective first 18 and second 20 housing portions. The liquid collection tank 36 and the roller 14 may each extend across at least 90% of the width of the housing 12 (i.e. dimension of the housing 12 along the direction W between the opposing side walls 22, 76). The combined inlet/outlet 65 may extend across at least 75% of a width of the liquid collection tank 36.

The liquid distribution tank 34 is located rearwardly of the liquid collection tank 36. The liquid collection tank 36 extends across the width in the direction W (between the opposing side walls 22, 76) of the housing 12 to a greater extent than the liquid distribution tank 34. The pump compartment 82, and hence the pump 84, are located adjacent to the liquid distribution tank 34 across the width W of the cleaner head 10. The attachment mechanism 16 is located centrally on the upper wall 74 such that the attachment mechanism 16 overlies the liquid collection tank 36, and is connected to the upper wall 74 at a point between the roller 14 and the liquid distribution tank 34.

To disassemble the cleaner head 10, a user depresses the depressible button 70 to remove the hook 72 of the catch mechanism 28 from engagement with the latch of the upper wall 74 of the second housing portion 20. At the same time, the user applies a force to separate the first 18 and second 20 housing portions by relative sliding of the first 18 and second 20 housing portions. Sliding motion of the first 18 and second 20 housing portions is constrained by movement of the guide strip 30 along the guide channel 94 to be in a direction parallel to a rotational axis R of the roller 14.

Since the tank assembly 24 is arranged within the first housing portion 18, the tank assembly 24 is releasably connected to the second housing portion 20 when the first 18 and second 20 housing portions are assembled. As the user slides the first 18 and second 20 housing portions away from one another along a connection axis (parallel to the axis of rotation R of the roller 14), the tank assembly 24 is moved along the connection axis and is disconnected from the second housing portion 20. Disconnection of the first 18 and second 20 housing portions breaks the fluidic connection between the liquid distribution tank 34 and the pump 84. Similarly, the connection between the mounting member 26 and the roller 14 is broken, with the mounting member 26 being removed from within an end of the core 120 of the roller 14. The user can continue to separate the first 18 and second 20 housing portions until the guide strip 30 leaves the guide channel 94, and the first 18 and second 20 housing portions are discrete, separated components.

In such a manner, the tank assembly 24, i.e. the liquid distribution tank 34 and the liquid collection tank 36, is removable from the second housing portion 20 by sliding the tank assembly 24 along the width direction W of the cleaner head 10. The tank assembly 24 is then located separately from electronic components of the cleaner head 10, and the liquid collection tank 36 can be emptied, and the liquid distribution tank 34 can be refilled. The removable cover 54 can be removed from the liquid collection tank 36 to aid with emptying.

Similarly, the roller 14 may then be removed from the second housing portion 20 by sliding the roller 14 along its axis of rotation to separate the roller 14 from the roller drive 80. The roller 14 can then be cleaned by a user.

When desired, the user can reassemble the cleaner head 10 in the manner previously described.

T o use the cleaner head 10, the attachment mechanism 16 is used to connect the cleaner head 10 to an appliance 200, as illustrated schematically in Figure 13.

The appliance 200 has a main unit 202, and a wand 204 releasably connected to the main unit 202. The cleaner head 10 can be connected to either of the main unit 202, or to the wand 204, depending on a user’s preference. The main unit 202 houses a power supply in the form of a battery 206, an airflow generator 208, and a control module 210. Power can be provided from the battery 206 to the airflow generator 208, and to the cleaner head 10 via a terminal (not shown) of the main unit 202, under control of the control module 210. Further details of the main unit 202 are not pertinent to the present invention, and will not be discussed here for sake of brevity.

The control module 210 determines whether the cleaner head 10 is attached to the main unit 202 based on a current drawn from the terminal in response to a voltage applied to the terminal. When the cleaner head 10 is attached to the main unit 202, either directly or via the wand 204, and a user actuates the main unit 202 by pressing a button or trigger or the like (i.e. sends a trigger signal indicating that the appliance is to be operated), the control module 210 of the main unit 202 causes a first voltage pulse to be sent to the cleaner head 10 via the terminal. As previously noted, the control circuitry 78 comprises a delay circuit. The delay circuit is configured to delay the draw of current by the cleaner head 10 from the terminal in response to the applied voltage. Specific details of the delay circuit are not important, and will be immediately apparent to a person skilled in the art. For example, an RC delay circuit may be utilised. This delay circuit means that, in response to the first voltage pulse, the control module 210 of the main unit 202 does not detect a current profile of the cleaner head 10 within a first time period of around 65-95ps post commencement of the first voltage pulse. The control module 210 of the main unit 202 then causes a second voltage pulse to be sent to the cleaner head 10 via the terminal. The control module 210 of the cleaner head 10 then detects a current profile within a second time period of say 300-350ps post commencement of the second voltage pulse.

Such a current profile, for example no current detected in the first time window and current detected in the second time window, may be distinctive compared to that provided by other cleaner heads, for example other cleaner heads without a delay circuit where a current profile is detected within the first time period by the control module 210 of the main unit 202. Thus the control module 210 can determine when the cleaner head 10 is attached to the main unit 202 based on the delay with which (or the particular one of a plurality of time periods) current is drawn from the terminal in response to the applied voltage. The control module 210 can also determine that a cleaner head other than cleaner head 10 is attached to the main unit 202 based on current being drawn from the terminal in response to the applied voltage in a different particular one of the plurality of time periods. If no current is drawn from the terminal in response to the applied voltage in any of the plurality of time periods, then it can be determined that no cleaner head is attached to the main unit 202. An initial one of the plurality of time periods may have a first duration and a subsequent time period may have a second duration longer than the first duration. The adjacent time periods may be separated from one another by a time gap. For example, the applied voltage may include a plurality of voltage pulses, one for each of the plurality of time periods, where there may be a time gap in between consecutive pulses.

The control module 210 can then take appropriate action in controlling the main unit 202. The control module 210 can operate the airflow generator 208 in either a first mode (in which power Is provided by the main unit 202 to the airflow generator 208 and an airflow is generated) and a second mode (in which power is not provided to the airflow generator 208 and an airflow is not generated). In particular, when the control module 210 determines that the cleaner head 10 is attached to the main unit 202, the control module 210 can control the operational mode of airflow generator 208 to be in the second mode (off), such that no airflow is provided by the main unit 202, as such airflow is not needed for the cleaner head 10. For other cleaner heads, the operational mode of the airflow generator 208 may instead be controlled to provide an airflow where such airflow is appropriate. When it is determined that there is no cleaner head attached to the main unit 202, the control module also controls the airflow generator to operate in the first mode.

Although the cleaner head 10 is detected here by looking at current profiles, other methods of detection, for example including communication from the cleaner head 10 to the control module via a wired and/or wireless connection, that enable the control module 210 to turn off the airflow generator 208 are also envisaged.

With the cleaner head 10 attached to the main unit 202, power is supplied from the battery 206 of the main unit 202 via looming (not shown) to the cleaner head 10, and in particular to the control circuitry 78, the roller drive 80, and the pump 84. With other cleaner heads attached to the main unit 202, power may also be supplied to these cleaner heads from the battery 206. However, power is not provided to the terminal of the main unit 202 when it is determined that no cleaner head is attached to the main unit 202.

The pump 84 drives distribution of liquid from the liquid distribution tank 34. The pump 84 is controlled by the control circuitry 78 to operate in a pulsed or cyclical manner, as noted previously, with the pump 84 controlled to be on for a first duration of 0.25 seconds, to be off for a second duration of 6 seconds, and so on. In other words, for each pulse, the first duration is around 4% of the second duration. This causes liquid to be moved from the liquid distribution tank 34, through the liquid tube 86, to the reservoir 88. In particular, liquid is driven by the pump 84 via the reservoir inlet 114 to the reservoir 88, and liquid is delivered to the pile 122 of the roller 14 via the reservoir outlets 116. The pressure within the reservoir 88 is such that liquid exits the reservoir 88 through the reservoir outlets 116, and drips onto the distribution surface 90. The configuration of the reservoir 88 and the operation of the pump 84 is such that the liquid flow rate through the reservoir is around 30ml/min. The pump 84, the liquid tube 86, the reservoir 88, and the distribution surface 90 together provide a liquid delivery assembly for delivering liquid to the roller 14 (in particular, the pile 122 of the roller 14).

The liquid pools on the distribution surface 90 and is gradually distributed to the roller 14 by simply falling from the distribution surface 90 onto the pile 122 of the roller 14. The roller 14 is wetted at a rate of around 30ml/min. With the roller 14 wetted by the liquid, the cleaner head 10 can be moved across a surface to be cleaned by the user. The roller drive 80 is controlled to rotate the roller 14 at around 900-1000rpm. As the roller 14 rotates and is moved across the surface to be cleaned, the roller 14 can impart a wiping force to the surface to be cleaned. The squeegee 58 contacts the surface to be cleaned and ensures that no dirty liquid from the surface being cleaned passes toward the rear of the cleaner head 10.

The roller 14 causes displacement of liquid (from the surface to be cleaned) into the combined inlet/outlet 65 of the liquid collection tank 36.

In particular, the rotation of the roller 14 and the curved nature of the front wall 56 of the liquid collection tank ensures that dirty liquid, and debris, passes from the surface being cleaned to the interior volume of the cleaner head 10. The roller 14 directs the dirty liquid and debris toward the squeegee 58 and the rotational energy generated via rotation of the roller 14 pushes the dirty liquid and debris upwards along the front wall 56 into the main tank body 50 of the liquid collection tank 36.

Further, as previously noted, the mangle 92 contacts the roller 14, in particular, it extends into the pile 122 of the roller 14. As the roller 14 rotates, the roller 14 is driven so that the roller 14 impinges the mangle 92 from below. In such a manner the pile 122 contacts the mangle 92, the mangle 92 acts to scrape dirty liquid and debris from the pile 122 of the roller 14. Accordingly, the liquid carried by the roller 14 is displaced into the combined inlet/outlet 65 of the liquid collection tank 36 in use. The speed of the roller 14 at the mangle 92 is around 5 to 7 m/s, which has been found to be particularly good for removal of dirty liquid and debris from the pile 122 of the roller 14. Speeds of between around 3m/s to 8m/s are also envisaged. The positioning and shape of the mangle 92 results in dirty liquid and debris being passed rearwardly toward the liquid collection tank 36.

Such dirty liquid and debris is guided by a curved portion 89 of the intermediate plate 87 (adjacent to the mangle 92) and/or the sloped surface 64 of the removable cover 54 through the combined inlet/outlet 65 into the interior of the main tank body 50 of the liquid collection tank 36. For example, the dirty liquid and debris is guided by the curved portion 89 along a curved path towards the liquid collection tank 36. As shown in Figure 12, the curved portion 89 is concave from the perspective of the surface to be cleaned when the cleaner head 10 is located on the surface to be cleaned in use.

With the configuration of the cleaner head 10 described above, the roller 14 (in particular the pile 122 of the roller 14) is maintained at a saturation level of between 25% and 28% in use. Such a saturation level has been found to be effective at cleaning a surface to be cleaned, without the need to distribute excessive levels of liquid onto the surface. Efficient cleaning may also be achieved with a saturation level of between 10% and 30%.

When desired, for example when there is no remaining liquid in the liquid distribution tank 34, the cleaner head 10 can be removed from the main unit 202 of the appliance 200. The cleaner head 10 can then be disassembled in the manner previously described to enable the liquid collection tank 36 to be emptied, and the liquid distribution tank 34 to be refilled.

In an embodiment of this disclosure, an appliance may be provided with the following clauses.

1. An appliance comprising a main unit to which a wet cleaner head is attachable, wherein the main unit comprises: an airflow generator operable during use of the appliance in a first mode in which an airflow is generated and in a second mode in which an airflow is not generated; and a control module configured to: determine whether the wet cleaner head is attached to the main unit; and in response to determining that the wet cleaner head is attached to the main unit, control the airflow generator to operate in the second mode. 2. An appliance according to clause 1 , wherein the control module is further configured to, in response to determining that the wet cleaner head is attached to the main unit: control the main unit to provide power to the wet cleaner head thereby to operate the wet cleaner head.

3. An appliance according to clause 1 or 2, wherein the control module is configured to: determine whether a cleaner head other than the wet cleaner head is attached to the main unit; and in response to determining that a cleaner head other than the wet cleaner head is attached to the main unit, control the airflow generator to operate in the first mode.

4. An appliance according to clause 3, wherein the control module is configured to: in response to determining that a cleaner head other than the wet cleaner head is attached to the main unit, control the main unit to provide power to the cleaner head other than the wet cleaner head so as to operate the cleaner head other than the wet cleaner head.

5. An appliance according to any one of the preceding clauses, wherein the control module is configured to: determine whether there is any cleaner head attached to the main unit; and in response to determining that there is no cleaner head attached to the main unit, control the airflow generator to operate in the first mode.

6. An appliance according to clause 5, wherein the main unit comprises a terminal for providing power to a cleaner head attached to the main unit in use, and wherein the control module is configured to: in response to determining there is no cleaner head attached to the main unit, control the main unit so as not to provide power to the terminal.

7. An appliance according to any one of the preceding clauses, wherein the control of the airflow generator to operate in the second mode comprises controlling the main unit to not provide power to the airflow generator and/or wherein the control of the airflow generator to operate in the first mode comprises controlling the main unit to provide power to the airflow generator.

8. An appliance according to any one of the preceding clauses, wherein the main unit comprises a terminal for providing power to a cleaner head attached to the main unit in use, and wherein the control module is configured to determine whether the wet cleaner head is attached to the main unit based on a current drawn from the terminal in response to a voltage applied to the terminal.

9. An appliance according to clause 8, wherein the control module is configured to determine whether the wet cleaner head is attached to the main unit based on a delay with which current is drawn from the terminal in response to the applied voltage.

10. An appliance according to clause 9, wherein the control module is configured to determine that the wet cleaner head is attached to the main unit based on current being drawn, from the terminal in response to the applied voltage, in a particular one of a plurality of time periods.

11. An appliance according to clause 10, wherein the control module is configured to determine that a cleaner head other than the wet cleaner head is attached to the main unit based on current being drawn, from the terminal in response to the applied voltage, in a different particular one of the plurality of time periods.

12. An appliance according to clause 10 or 11 , wherein the control module is configured to determine that no cleaner head is attached to the main unit based on no current being drawn, from the terminal in response to the applied voltage, in any of the plurality of time periods.

13. An appliance according to any one of clause 10 to 12, wherein adjacent time periods are separated from one another by a time gap.

14. An appliance according to any one of clause 10 to 13, wherein the applied voltage comprises a plurality of voltage pulses, one for each of the plurality of time periods.

15. An appliance according to clause 14, wherein an initial one of the plurality of time periods has a first duration, and a time period immediately subsequent to the initial time period has a second duration, the second duration being longer than the first duration.

16. An appliance according to any one of the preceding clauses, wherein the control module is configured to determine whether the wet cleaner head is attached to the main unit in response to a trigger signal indicating that the appliance is to be operated. 17. An appliance according to any one of the preceding clauses, wherein the main unit comprises a power supply for powering the airflow generator and/or the wet cleaner head.

18. An appliance according to any one of the preceding clauses, wherein the appliance comprises the wet cleaner head.

19. An appliance according to clause 18, wherein the wet cleaner head comprises a delay component configured to delay, by a particular amount, drawing of current by the wet cleaner head from the main unit when a voltage is applied to the wet cleaner head by the main unit.

20. An appliance according to clause 18 or 19, wherein the wet cleaner head comprises a drive component configured to drive distribution of liquid, and wherein the main unit is configured to provide power to the drive component when the wet cleaner head is attached to the main unit in use.

In another embodiment of this disclosure, a cleaner head for an appliance may be provided with the following clauses.

1. A cleaner head for an appliance, the cleaner head comprising: a roller for contacting a surface to be cleaned; and a liquid delivery assembly comprising a drive component for driving distribution of liquid to the roller; wherein the drive component is configured to drive the distribution of liquid to the roller in pulses; wherein the drive component is configured to drive the distribution of liquid for a first duration to generate each pulse; and consecutive pulses are separated by a second duration in which the drive component does not drive the distribution of liquid; and wherein the first duration is between 2% and 9% of the second duration.

2. A cleaner head according to clause 1 , wherein the first duration is 0.25 seconds.

3. A cleaner head according to clause 1 or 2, wherein the second duration is between 3 seconds and 10 seconds. 4. A cleaner head according to any one of clauses 1 to 3, wherein the cleaner head comprises a roller drive configured to drive rotation of the roller, and wherein the first duration lasts for at least one revolution of the roller.

5. A cleaner head according to clause 4, wherein the first duration lasts for between 2 and 5 revolutions of the roller.

6. A cleaner head according to any one of the preceding clauses, wherein the liquid delivery assembly comprises a reservoir to which liquid is driven by the drive component via a reservoir inlet, wherein the reservoir comprises a plurality of outlets via which liquid is delivered to the roller.

7. A cleaner head according to clause 6, wherein the liquid delivery assembly comprises a distribution surface for distributing liquid onto the roller, the distribution surface extending in a direction parallel to the rotational axis of the roller, the distribution surface being provided with liquid from the outlets of the reservoir.

8. A cleaner head according to any one of the preceding clauses, wherein the cleaner head further comprises a liquid distribution tank for storing liquid to be distributed to the roller by the drive component.

9. A cleaner head according to any one of the preceding claims, wherein the liquid delivery assembly is configured to deliver liquid to the roller at a rate of between 25 and 35 millilitres per minute.

10. A cleaner head according to any one of the preceding clauses, wherein the roller comprises a material for contacting the surface to be cleaned.

11. A cleaner head according to clause 10 wherein the liquid delivery assembly is configured to deliver liquid to the material so that the material is between 10% and 30% saturated with liquid.

12. A cleaner head according to clause 10 or 11 , wherein the surface area of the material is between 800 and 900 square centimetres. 13. A cleaner head according to any one of clauses 10 to 12, wherein the material is microfibre having a density of between 46500 and 85250 fibres per square centimetre.

14. A cleaner head according to any one of clauses 10 to 13, wherein the cleaner head comprises a mangle configured to remove liquid and/or debris from the material.

15. The cleaner head according to clause 14, wherein the mangle penetrates into the material a distance of between 2 and 3 millimetres.

16. A cleaner head according to any one of the preceding clauses, wherein the cleaner head comprises a roller drive, wherein the roller drive is configured to drive rotation of the roller at a rate between 500 and 1200 revolutions per minute.

17. An appliance comprising a cleaner head according to any one of the preceding clauses.

18. An appliance according to clause 17, wherein the appliance comprises a main unit, and the cleaner head is releasably attachable to the main unit.

19. An appliance according to clause 18, wherein the main unit comprises a power supply for supplying electrical power to the drive component.

Whilst particular examples and embodiments have thus far been described, it should be understood that these are illustrative only and that various modifications may be made without departing from the scope of the invention as defined by the claims. For example, the values of various parameters and dimensions described in conjunction with the specific embodiment above may be varied within a reasonable tolerance range that will be apparent to a person skilled in the art without significantly modifying operation of the cleaner head 10.