TECHNICAL FIELD

The disclosure relates to a printed wiring board for use in an electronic device.

BACKGROUND

Electronic devices may be provided with magnet actuators in order to generate, e.g., sound waves.

As disclosed in GB2532436, the magnet actuator may comprise magnets which either attract or repulse each other. Initially, the magnets are arranged in force equilibrium, but in order to generate sound waves the attractive or repulsive force between the magnets is changed by means of an electric current passing through a coil located between the magnets, the current causing at least one of the magnets to move such that the distance between the magnets decreases or increases.

The coil of GB2532436 may be glued to the top of one of the magnets, or wound around the side of a magnet, and may be electrically coupled to an audio signal input by means of a wire. When used for electronic devices, the components of the magnet actuator have to be so small that it is difficult to manufacture as well as assemble the components, in particular the coil. Furthermore, the coil generates undesired heat which is mainly conducted directly to the magnet, which could become demagnetised should the temperature become too high.

SUMMARY

It is an object to provide an improved printed wiring board. The foregoing and other objects are achieved by the features of the independent claims. Further implementation forms are apparent from the dependent claims, the description, and the figures.

According to a first aspect, there is provided a printed wiring board (also called printed circuit board) for use in an electronic device, the printed wiring board comprising integrated circuits and a voice coil, the voice coil being formed integrally with the printed wiring board.

Such a solution allows the printed wiring board and voice coil to be configured as one integral component, as opposed to two separate discrete components, which integral component is easily mounted in an electronic device. Furthermore, by integrating the voice coil with the printed wiring board, the heat generated by the coil will have less impact on adjacent components such as magnets since the material of the printed wired board distributes heat approximately 10 times better than air. Additionally, there is no need for additional support means for assembling the voice coil.

In a possible implementation form of the first aspect, at least one of the integrated circuits is an audio amplifier connected to the voice coil, facilitating a component which is easily mounted in an electronic device and which is reliable since there is no need to accommodate possible movement between the voice coil and the audio amplifier.

In a further possible implementation form of the first aspect, at least one of the integrated circuits is a main processor for the electronic device, facilitating a component which is easily mounted in an electronic device.

In a further possible implementation form of the first aspect, the printed wiring board further comprises a fixed magnet attached to the printed wiring board such that the fixed magnet is superimposed over the voice coil layers, allowing a plurality of actuating components to be interconnected which facilitates simple and efficient mounting of the actuating components within, e.g., an electronic device.

In a further possible implementation form of the first aspect, the printed wiring board comprises at least one printed wiring board layer, and the voice coil is arranged in at least a first voice coil layer and a second voice coil layer, a voice coil interconnecting section extending between the first voice coil layer and the second voice coil layer, allowing an increased amount of voice coil to be used.

In a further possible implementation form of the first aspect, coil windings of a voice coil layer are arranged in a spiral-shaped pattern, the coil windings of a first voice coil layer or a second voice coil layer extending in a direction from an outer periphery of the spiral-shaped pattern towards a center of the spiral-shaped pattern, and the coil windings of a second voice coil layer or a first voice coil layer extending in a direction from a center of the spiral-shaped pattern towards an outer periphery of the spiral-shaped pattern, and wherein the voice coil interconnecting section extends between the first voice coil layer and the second voice coil layer adjacent a center of the spiral-shaped pattern or adjacent an outer periphery of the spiral-shaped pattern, allowing a spatially efficient distribution of voice coil layers. In a further possible implementation form of the first aspect, the printed wiring board comprises at least two printed wiring board layers, each printed wiring board layer comprising a first voice coil layer or a second voice coil layer, wherein each first voice coil layer or second voice coil layer is connected to at least one second voice coil layer or first voice coil layer by means of a voice coil interconnecting section adjacent the center of the spiral-shaped pattern, and wherein each second voice coil layer or first voice coil layer is connected to at least one first voice coil layer or second voice coil layer by means of a voice coil interconnecting section adjacent the outer periphery of the spiral-shaped pattern, allowing a stable yet spatially efficient increase in the number of voice coil layers.

In a further possible implementation form of the first aspect, the printed wiring board layers alternate such that every other printed wiring board layer comprises a first voice coil layer and every other printed wiring board layer comprises a second voice coil layer, facilitating an as simple, layered voice coil structure as possible.

In a further possible implementation form of the first aspect, the printed wiring board layer comprises a throughput for receiving the voice coil interconnecting section extending between the first voice coil layer section and the second voice coil layer, facilitating a discrete yet secure transition between voice coil layers.

According to a second aspect, there is provided an electronic device comprising a movable surface and a device chassis, interconnected by means of a resilient element, a printed wiring board according to the above arranged between the movable surface and the device chassis, the printed wiring board being attached to the device chassis, the printed wiring board being the main printed wiring board of the electronic device, and a moveable magnet attached to the movable surface, the printed wiring board and the moveable magnet being adapted for moving the movable surface relative to the device chassis. Such a solution facilitates an electronic device which comprises fewer discrete parts and which is cheap and reliable.

In a possible implementation form of the second aspect, movement of the movable surface generates vibrations within the electronic device, which may be used as haptic means or for generating sound waves.

In a further possible implementation form of the second aspect, a fixed magnet of the printed wiring board and the moveable magnet are arranged so that a magnetic field, generated by the fixed magnet and the moveable magnet, causes an attractive force between the fixed magnet and the moveable magnet, maintaining the fixed magnet and the moveable magnet in a force equilibrium state, and wherein manipulating electrical current in a voice coil of the printed wiring board causes a change in the attractive force thereby causing a displacement between the fixed magnet and the moveable magnet, allowing a simple yet reliable construction.

In a further possible implementation form of the second aspect, the printed wiring board is arranged such that the fixed magnet and the moveable magnet are located on opposite sides of the printed wiring board, and an air gap is provided between the moveable magnet and the printed wiring board, facilitating a compact actuating arrangement.

In a further possible implementation form of the second aspect, a first air gap is provided between the moveable magnet and the printed wiring board when the attractive force is of a first magnitude, and a second air gap, smaller than the first air gap, is provided between the moveable magnet and the printed wiring board when the attractive force is of a second magnitude, allowing generation of vibrations.

In a further possible implementation form of the second aspect, the electronic device further comprises a first housing and a second housing, the fixed magnet being at least partially located within the first housing, and the moveable magnet being at least partially located within the second housing, the first housing and the second housing limiting the magnetic field to a space within at least one of the first housing and the second housing, preventing the magnetic field from interfering with other components.

This and other aspects will be apparent from and the embodiment(s) described below.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following detailed portion of the present disclosure, the aspects, embodiments, and implementations will be explained in more detail with reference to the example embodiments shown in the drawings, in which:

Fig. 1 shows a schematic, cross-sectional side view of a printed wiring board and an electronic device in accordance with one embodiment of the present invention;

Fig. 2 shows a partial, cross-sectional side view of a printed wiring board and an electronic device in accordance with one embodiment of the present invention; Fig. 3 shows a partial, cross-sectional perspective view of the printed wiring board and the electronic device shown in Fig. 1.

Fig. 4 shows a partial, cross-sectional perspective view of the printed wiring board and electronic device shown in Fig. 2;

Fig. 5 shows a partial, schematic side view of a printed wiring board in accordance with one embodiment of the present invention.

DETAILED DESCRIPTION

Figs. 2, 3, and 4 show a printed wiring board 1 in accordance with embodiments of the present disclosure. The printed wiring board (PWB) 1 is preferably used in an electronic device 10 such as a smart phone or a tablet, however, it may be used in any suitable type of electronic device. The printed wiring board 1 could also be called printed circuit board (PCB) 1 .

As shown in Fig. 2, the printed wiring board comprises at least one printed wiring board layer 1 a, 1 b, functioning as a carrier for other components as well as insulation.

The printed wiring board comprises at least one integrated circuit 2 and a voice coil 3. One of the integrated circuits 2 may be an audio amplifier connected to the voice coil 3, and one integrated circuit 2 may be the main processor for the electronic device. Hence, the printed wiring board may be a main PWB or PCB of the electronic device.

The voice coil 3 is preferably made of copper and formed integrally with the printed wiring board layer(s) 1 a, 1 b, as shown more clearly in Figs. 3 and 4. By integrally is meant that the voice coil is part of the printed wiring board as a result of the voice coil being printed onto a printed wiring board layer 1 a, 1 b. The voice coil 3 is not a separate, discrete component such as a voice coil film stacked on top of a printed wired board layer 1 a, 1 b, but a fixed part of the printed wiring board 1.

The voice coil 3 is preferably arranged in at least a first voice coil layer 3a and a second voice coil layer 3b. The first voice coil layer 3a and the second voice coil layer 3b are arranged such that they are superimposed over each other and extend in a plane which is parallel with a main plane of the printed wiring board. The main plane of the printed wiring board 1 extends in parallel with the main plane of an electronic device 10 which the printed wiring board 1 is mounted into, and may, e.g., extend in parallel with a display of such an electronic device 10. A voice coil interconnecting section 3c extends between the first voice coil layer 3a and the second voice coil layer 3b in a direction perpendicular to the first voice coil layer 3a and the second voice coil layer 3b. See Fig. 5 for a schematic illustration of how the printed wired board layers 1 a, 1 b and the voice coil layers 3a, 3b are arranged.

Each voice coil layer 3a, 3b comprises a plurality of coil windings 4 are arranged in a spiral- shaped pattern, the voice coil 3 extending in a direction from an outer periphery of the spiral- shaped pattern towards a center of the spiral-shaped pattern, or extending in an opposite direction, from a center of the spiral-shaped pattern towards an outer periphery of the spiral- shaped pattern. Figs. 4 and 5 indicate such a spiral-shaped pattern. The pattern is preferably essentially circular, but may also be rectangular, elliptical or any other suitable shape. The coil windings 4 extend in a plane perpendicular to the direction of the attractive force F caused by the magnetic field.

The coil windings 4 of one voice coil layer, i.e. the first voice coil layer 3a or the second voice coil layer 3b, extend in a direction from an outer periphery of the spiral-shaped pattern towards a center of the spiral-shaped pattern. Similarly, the coil windings 4 of another voice coil layer, i.e. the second voice coil layer 3b or the first voice coil layer 3a, extend in a direction from a center of the spiral-shaped pattern towards an outer periphery of the spiral- shaped pattern. In other words, the coil windings 4 of the first voice coil layer 3a and the coil windings 4 of the second voice coil layer 3b extend in opposite directions. The voice coil interconnecting section 3c extends between the first voice coil layer 3a and the second voice coil layer 3b adjacent either the center of the spiral-shaped pattern or adjacent the outer periphery of the spiral-shaped pattern, as shown in Fig. 5.

In one embodiment, the printed wiring board 1 comprises at least two printed wiring board layers 1 a, 1 b, each printed wiring board layer 1 a, 1 b comprising a first voice coil layer 3a or a second voice coil layer 3b. Each first voice coil layer 3a, or second voice coil layer 3b, is connected to at least one second voice coil layer 3b, or first voice coil layer 3a by means of a voice coil interconnecting section 3c adjacent the center of the spiral-shaped pattern.

Correspondingly, each second voice coil layer 3b, or first voice coil layer 3a, is connected to at least one first voice coil layer 3a, or second voice coil layer 3b, by means of a voice coil interconnecting section 3c adjacent the outer periphery of the spiral-shaped pattern. The printed wiring board layers 1 a, 1 b alternate such that every other printed wiring board layer 1 a comprises a first voice coil layer 3a and every other printed wiring board layer 1 b comprises a second voice coil layer 3b.

The direction of the electric current in the voice coil 3 is preferably the same, either clockwise or anti-clockwise, in both first voice coil layer(s) 3a and second voice coil layer(s) 3b in order to generate a common magnetic displacement force.

The printed wiring board layers 1 a, 1 b preferably comprise a throughput 5 for receiving the voice coil interconnecting section 3c extending between the first voice coil layer section 3a and the second voice coil layer 3b.

The printed wiring board 1 further comprises a fixed magnet 6 attached to the printed wiring board 1 such that the fixed magnet 6 is superimposed over the voice coil layers 3a, 3b.

The printed wiring board 1 further comprises an electric source 7, the voice coil 3 being electrically connected to the electric source 7 as shown schematically in Fig. 5, the electrical source transferring electrical current to the voice coil 3.

The electronic device 10, shown schematically in Fig. 1 , comprises a movable surface 9, such as a display, and a device chassis 1 1 , interconnected by means of a resilient element 12 such as an elastic adhesive. The movable surface/display 9 may be made of glass and/or be elastic.

The printed wiring board 1 is arranged between the movable surface 9 and the device chassis 1 1 , and is also attached to the device chassis 1 1. A moveable magnet 8 is attached to the movable surface 9. The printed wiring board 1 and the moveable magnet 8 are adapted for moving the movable surface 9 relative to the printed wiring board 1 , and hence the device chassis 1 1 , in response to manipulation of electrical current in the voice coil 3 of the printed wiring board 1 .

The fixed magnet 6 of the printed wiring board 1 and the moveable magnet 8 are arranged so that a magnetic field, generated by the fixed magnet 6 and the moveable magnet 8, causes an attractive force F between the fixed magnet 6 and the moveable magnet 8, maintaining the fixed magnet 6 and the moveable magnet 8 in a force equilibrium state. Manipulating electrical current in the voice coil 3 of the printed wiring board 1 causes a change in the attractive force F thereby causing a continuous displacement between the fixed magnet 6 and the moveable magnet 8. Subsequently, this displacement causes the movable surface 9 of the electronic device to move in relation to the device chassis 1 1 . The movement of the movable surface 9 generates vibrations within the electronic device 10, the vibrations being used for generating sound waves or as a haptic means providing tactile feedback to the user.

The printed wiring board 1 is arranged such that the fixed magnet 6 and the moveable magnet 8 are located on opposite sides of the printed wiring board 1 , and an air gap 13 is provided between the moveable magnet 8 and the printed wiring board 1 .

A first air gap 13a is provided between the moveable magnet 8 and the printed wiring board 1 when the attractive force F is of a first magnitude, and a second air gap 13b, smaller than the first air gap 13a, is provided between the moveable magnet 8 and the printed wiring board 1 when the attractive force F is of a second magnitude. Hence, the moveable magnet 8 oscillates between two end positions, the one end position being defined by the height of the first air gap 13a. The other end position is at a point where the height of the air gap 13b is smaller than the height of the first air gap 13a.

The electronic device 10 may further comprise a first housing 14a and a second housing 14b, the fixed magnet 6 being at least partially located within the first housing 14a, and the moveable magnet 8 being at least partially located within the second housing 14b. The first housing 14a and the second housing 14b limit the magnetic field to a space within at least one of the first housing 14a and the second housing 14b. This prevents the magnetic field from interfering with other objects such as the other components of the electronic device. The first housing 14a and the second housing 14b are at least partly made of a magnetic material.

The first housing 14a and the second housing 14b may both be configured such that they have an open end and a closed base connected by at least one surrounding wall, e.g. being shaped as a cylinder having one sealed off end and one open end. The open end of the first housing 14a is connected to, or arranged directly in abutment with, the printed wiring board 1 . The open end of the second housing 14b is directed towards the printed wiring board 1 and the first housing 14a.

The first housing 14a is essentially shaped to accommodate the fixed magnet 6. The second housing 14b is essentially shaped to accommodate the moveable magnet 8.

The various aspects and implementations has been described in conjunction with various embodiments herein. However, other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed subject-matter, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article“a” or“an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage.

The reference signs used in the claims shall not be construed as limiting the scope.