TECHNICAL FIELD

The present invention relates to a method pertaining to the transportation and selection of film-carrying frames in a magazine which can be moved horizontally in relation to a stand, and more particularly to a method of the kind defined in the preamble of Claim 1.

The invention also relates to apparatus for transporting and selecting film-carrying frames in accordance with the preamble of Claim 6.

BACKGROUND PRIOR ART

Motorized film examination cabinets provided with horizontal¬ ly movable magazines that contain film frames for vertical transportation between the magazine and an overlying illumi¬ nated surface are known to the art. Conventionally, two film frames are moved up to a position in front of the illuminated surface, one upper and one lower film-frame.

Examples of such known film examination cabinets are de¬ scribed in SE-B-310 074, SE-B-348 057 and SE-B-347 120, for instance (all of which are in the names E. Ohlson and C-E Ohlson) .

The film frames housed in the magazine are mutually spaced, i.e. a space is provided between each frame. This space is necessary in order for mechanical requirements on vertical transportation and straightness of the frames to be reason¬ able. Because the films, which vary in size, are not com- pletely straight, the frames are often provided with horizon¬ tally mounted and vertically movable elastic cords or threads. These threads function to prevent outwardly project-

ing films from vertical transportation of the frames, not least during passage behind a forwardly jutting frame in the magazine.

If the space between the frames is too small, the films will fasten and jam the system. This often leads to irritating disturbances in operation and also interrupts the diagnosis and other working routines. Furthermore, when the frame spacing is inadequate, the frames are liable to contact one another as they move and result in discordant noise which can be experienced as particularly troublesome, especially when several film examination cabinets and radiologists are located on in one and the same room.

Motorized film examination cabinets which function in accordance with the magazine principle enable combinations of frames to be selected quickly in different positions in the magazine, so that these frames can be positioned in front of the illuminated surface. It is also possible to use motorized film examination cabinets which function in accordance with the belt principle, i.e. a principle in which the films are mounted on transparent plastic belts or bands that are reeled onto reels externally of the illuminated surface. The belts either move in a vertical or horizontal direction and can be moved forwards and rearwards, i.e. out and in, so as to enable the belts to be reeled onto the reels, which have the same width as the belts.

The so-called belt machines do not have the aforementioned serious drawbacks. On the contrary, they have the advantage of a higher film storage capacity than machines that operate in accordance with the magazine principle. The number of film frames that can be accommodated in the magazine is dependent on the depth, which is restricted by the space available in practice, not least by the space required to accommodate the legs of the person carrying out the examination.

The number of film frames and therewith the film storage capacity can be increased by minimizing the thickness of the frames and therewith increasing their packing density. However, adequate spacing between the frames is still required to achieve reliable functioning of the arrangement. This capacity could be greatly increased by either reducing or eliminating the spacing between the frames, i.e. to pack the frames together in the form of suspended pocket files.

OBJECTS OF THE INVENTION

With a starting point from the aforedescribed known tech¬ niques, the object of the invention is to provide a method and an arrangement of the aforedescribed kind which will enable the frames to be reliably selected and transported in a magazine, despite the magazine accommodating more film frames than has hitherto been considered possible.

SUMMARY OF THE INVENTION

This object is fulfilled by an inventive method of the aforedescribed kind that has the features set forth in the characterizing clause of Claim 1.

As a result of mutually separating frames in the region between frame-engagement locations in conjunction with frame selection, engagement of frame-carrying elements for vertical movement of the frame to a film-examining position can be effected reliably and with no problems. The remaining frames in the magazine may be packed tightly in the magazine during this frame selection, therewith enabling the capacity of the magazine to be considerably increased.

It has been found in practice that the magazine storage capacity can be increased threefold when practicing the invention, i.e. a magazine which earlier had an effective capacity of twenty-six frames is able to accommodate effect-

ively not fewer than seventy-eight frames when practicing the invention. In this regard, the frames have also been made thinner than the earlier frames to no detriment, since the frame engaging and lifting devices are still able to grip the frames to no disadvantage.

The frames can be separated in different ways. A preferred method of separating the frames in the region between the frame-engagement locations is to move the frames in said region at a greater speed than remaining frames in the magazine, wherewith the magnitude of the spacing between these frames in the selected region will be dependent on the increase in speed.

This increase in speed can be achieved, for instance, by transferring the frame-carrying elements from the gaps between the teeth of a toothed rack connected to the magazine to gaps between the teeth of a toothed wheel which is mounted adjacent said rack and the peripheral speed of which is greater than the speed at which the rack moves.

It will be understood that this greater speed can be achieved reliably with the aid of simple means. The gaps between the respective teeth of the rack and toothed wheel enable the film frames to be accurately positioned and therewith facilitate frame selection, i.e. each tooth gap is given a predetermined number which is marked appropriately by the operator on a selector device belonging to the examination cabinet. The frame corresponding to the number chosen is then moved automatically to the aforesaid frame-engagement position, in which the frame is transferred so that its carrier element will rest in tooth gaps on toothed wheels located adjacent the racks, for engagement of the frame and its vertical movement in the system. The frame concerned will therewith be located in a position above remaining frames and is separated from those frames located adjacent thereto, so as to enable the frame to be gripped in an acceptable manner.

When two frames are lifted to the film viewing position, which is normally the case in examination cabinets of the design concerned, corresponding selection and separation processes are effected for subsequent frames after the first frame has adopted a waiting position at a convenient height above the magazine. The two frames are then moved together to the film-viewing position.

Normally, it is ensured that advancement of the frames will cease when selected frames are located in a position in which their respective carrier element can be engaged by the frame- engaging devices.

As will be understood, this increase in speed in conjunction with a frame separation operation can be achieved in other ways. For instance, the frame-carrying elements can be accommodated in adjacent parts of a groove of a helical worm means whose axis is parallel with the direction of movement of the magazine and which exhibits a part of greater pitch in which the speed of selected frames is increased.

Alternatively, the frame-separating device may include mutually adjacent and mutually parallel conveyor belts located at different levels and provided with teeth and tooth gaps, of which levels the higher level will move faster than the lower level.

The invention also relates to an arrangement for transporting and selecting film-carrying frames of the aforedescribed kind, this arrangement being characterized mainly by the features set forth in the characterizing clause of Claim 6.

Preferred embodiments of this arrangement are defined in dependent Claims.

The invention will now be described in more detail with reference to exemplifying embodiments thereof and also with

reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. l is a schematic perspective view of a film examination cabinet which includes a horizontally movable film-frame magazine and an arrangement constructed in accordance with the present invention.

Fig. 2a is a perspective view of a film-frame separating or parting mechanism forming part of the inventive arrangement.

Fig. 3 is a side view of the frame separating mechanism and shows the mechanism in conjunction with a frame selection operation.

Fig. 4 is a schematic, perspective view of a pivotal device which is movable along a vertical guide means and which functions to engage the carrier elements of a selected frame for vertical movement of the frame to a film-viewing posi¬ tion.

Fig. 5 is a schematic perspective view of an alternative embodiment of an inventive frame separating or parting mechanism in accordance with the invention.

Fig. 6 is a side view of the mechanism shown in Fig. 5 and illustrates the mechanism during an ongoing frame separating operation.

Finally, Fig. 7 is a schematic side view of another embodi¬ ment of the inventive frame separating mechanism.

DESCRIPTION OF PREFERRED EMBODIMENTS

The reference numeral 1 identifies generally an X-ray film examination cabinet which is supported by a metal-beam stand

(not shown) .

The stand also supports a magazine 2 in which a plurality of tightly packed film-carrying frames 3 are housed.

The magazine is carried by a plurality of mutually adjacent carrier rollers 4 which are rotatable about horizontal axles 4a. Horizontal reciprocating movement is obtained with the aid of a toothed wheel 9 which is driven by a shaft 9a and the teeth 9b of which coact with the teeth 10'b of a toothed wheel 10', the teeth 10'b of said wheel 10' engaging a toothed rack 7 mounted in a U-beam 6 attached to the upper side-edge of the magazine 2. The toothed wheel 10' is rotatable on a shaft 10a which also carries a frame-separat- ing device in the form of a toothed wheel 10, as described below.

As the toothed wheel 9 rotates, the magazine 2, carried by the rollers 4, moves reciprocatingly in a horizontal direc- tion in the lower part of the cabinet 1.

According to one embodiment preferred in practice, the magazine accommodates seventy-eight relatively thin film- carrying frames 3.

The film-carrying frames are provided at their upper side- edges with outwardly projecting carrier elements 3a which have downwardly-outwardly directed grooves 3b for engagement with a device 28 (see Fig. 4) functioning to move a selected frame vertically into a film-examining position in front of the illuminated surface la.

In the case of the Fig. 4 embodiment, the engagement device 28 is mounted on a link element 11 which is pivotal about a pivot axle 12. The link element 11 is connected by said pivot axle 12 to a carriage element 13 having two wheels 14 and 15 which are movable along one side of a vertical guide means

16. The link element 11 carries a roller or runner 18 which is rotatable about a shaft 17 and moves along the other side of the vertical guide means 16. The shafts 17 and 19 of respective wheels 18 and 15 are mutually joined by a spring 20.

As will be seen from Fig. 4, the mutually opposing side surfaces of the vertical guide means 16 have different angles of slope at certain places therealong, therewith causing the link element 11 to pivot relative to the carriage element 13 during passage along these parts of the vertical guide means.

The units or assemblies 11, 13 are moved vertically with the aid of cords or lines 21, 22 which pass around guide rollers (not shown) , of which one is driven by a drive motor (not shown) .

The line 22 exiting downwardly from the carriage element 13 is joined to a corresponding frame engagement mechanism located at a lower level and intended for engagement with a further film frame, so as to enable two film frames to be moved to an examining position in front of the illuminated surface la simultaneously, with one frame located beneath the other.

The vertical guide means 16 with its differently angled side surfaces may also be used to vary the distance between said two vertically transported film frames, namely so that the frames will be in end-to-end contact in the film-examining position and therewith avoiding the occurrence of disturbing stray light between the frames.

The carrier elements 3a of the frames 3 accommodated in the magazine 2 rest in the tooth gaps 8c of a toothed rack 8 connected to the upper side of the U-beam 6 attached to the magazine 2. The teeth of the rack 8 are referenced 8b.

In this way, each of the individual frames 3 in the magazine 2 will obtain an accurately defined position which enables the operator to readily perform a frame selection operation so that a desired frame is brought to a correct position for engagement of a frame-engaging device 28 in the groove 3b of the carrier elements 3a of the frame concerned, on each of its sides.

In order to ensure that respective engagement devices 28 will engage reliably with the carrier elements 3a of a desired frame, despite the closeness at which the frames are packed in the magazine 2, the arrangement includes a frame-separat¬ ing device which functions to mutually separate adjacent frames in the region between the carrier-element engagement locations on both side surfaces of the magazine.

In the embodiment illustrated in Figs. 2a and 3, this frame- separating device is comprised of a toothed wheel 10 which is rotatably mounted on the shaft 10a and which coacts with the toothed rack 8. As indicated in the aforegoing, the shaft 10a also carries the toothed wheel 10 ^• in driving engagement with the driving toothed wheel 9a, so that the wheels 9 and 10 will rotate synchronously with one another although at different peripheral speeds. For instance, the peripheral speed of the toothed wheel 10 may be twice that of the toothed wheel 9, which is achieved, e.g., by using a toothed wheel 10 whose diameter is twice that of the toothed wheel 9 and rotating the two wheels at mutually the same speed.

As will be seen from Fig. 3, as the magazine is moved along the rack 8, for instance to the right in the Figure, the carrier elements 3a of the frames 3 received in the tooth gaps 8c of the rack 8 will be transferred to the tooth gaps 10c of the tooth wheel 10. The frames 3 and associated carrier elements 3a that are located in said engagement region will therewith be moved twice as fast as those frames that are located outside said engagement region and not acted

upon by the wheel 10.

This increase in speed of said frames causes the frames to be mutually separated, therewith enabling reliable engagement of the engagement devices 28 provided on the link elements 11.

Thus, as the selection operation proceeds, those frames that are located in the region of the engagement location will be separated and the frame selection and separating process is terminated when a desired frame or frames is/are located centrally above the shaft 10a of the toothed wheel 10, whereafter the carrier element of the frame concerned can be engaged unimpeded.

Subsequent to this engagement and subsequent to lifting the frame 3 concerned to a position in which its bottom edge is free from the top edge of frames 3 located in the magazine, a further frame-selecting and frame-separating operation can be carried out, so as to bring a further selected frame to a position in which it is distanced from remaining frames and therewith allow engagement of further engagement devices 28 and movement of said further frame to a viewing position in front of the illuminated surface la, i.e. in a position such that the X-ray films in both frames can be viewed simulta¬ neously.

In the case of the embodiment illustrated in Figs. 2 and 3, the frames are separated from one another in the engagement region by virtue of an increase in speed achieved with the aid of a toothed wheel whose peripheral speed is greater than that at which the magazine, and therewith the remaining frames, is moved horizontally during the frame-selecting operation.

It is not necessary for the frames to be stationary before the frame carrier-element is engaged by the engagement

devices 28. Thus, engagement of the frames to effect their mutual separation can be ensured without requiring the selected frame to be stationary.

Figs. 5-7 illustrate an alternative frame-separating method and arrangements therefor. In the case of the embodiment illustrated in Figs. 5 and 6, the frame separating arrange¬ ment includes adjacent, generally parallel conveyor belts 25, 26, e.g. rubber belts, provided with teeth 25b, tooth gaps 25c and teeth 26b and tooth gabs 26c respectively.

The conveyor belt 26 can be caused to move faster than the conveyor belt 25, so as to separate selected frames from the remainder of the frames. The belt 26 runs over a wheel 27 and over a further wheel (not shown) , wherein at least eight frames at a time can be moved at the higher speed with the aid of the belt 26. The spacing between the frames 3 will be dependent on the difference in speed of the belts 25, 26. In practice, the belt 26 will preferably move at roughly twice the speed of the belt 25, as in the corresponding case of the earlier embodiment.

Fig. 7 illustrates an embodiment in which the frame-separat¬ ing device has the form of a helical groove 31 provided in an axle 30, i.e. a worm-like device, wherein the carrier elements 3a of the frames 3 are received in the helical groove so that the frames will be tightly packed therealong. The helical axle 30 extends parallel to the direction of magazine movement, said magazine not being shown in Fig. 7. As illustrated in Fig. 7, the helical groove 31 has a region 31• of greater pitch, wherein as the axle 30 rotates those frame carrier elements 3a that are located in said region will be moved at a greater speed than the remainder and therewith separated therefrom.

It will be understood that other means for separating frames located in the region of the frame engagement location are possible within the scope of the invention.