SHEET FEED APPARATUS AND CARTRIDGE THEREFOR

Abstract: A top-sheet feeding apparatus having an automatically elevating stack support tray (100) to keep the top sheet of the stack (5) in operative contact with sheet feed means (10). An upwardly projecting member (2) is present on the tray. The stack of sheets is provided in a cartridge (3) which simplifies the change over of throughput material and reduces the risk of damage and contamination both during handling and storage. The cartridge (3) comprises a generally enclosed rectangular container (4) holding the stack of sheets (5). The container has three openings as follows: (i) in its top face (6b) a cut out portion (9) exposing a portion of the top sheet to permit engagement by the sheet feed means (10), (ii) in a side face (6c) a slot (11) through which sheets can be fed out from the top of the stack, and (iii) in bottom face (6a) an aperture (7) slightly larger than the projecting member (2). The cartridge (3) also comprises a vertically movable plate (8) for supporting the stack (5). The plate (8) is disposed within the container (4) adjacent the bottom face (6a) and extends over the aperture (7) therein such that the block (2) of the elevating tray (100) bears against the underside of plate (8) to raise the plate and the stack, thus maintaining the top sheet of the stack in operative contact with the sheet feed means (10).

Description: This invention relates to a sheet feed apparatus, particularly but not exclusively for use in a xerographic or like copier, comprising a support tray for a stack of sheets to be fed, and means for feeding the top sheet of the stack, wherein the tray is elevated automatically to maintain the top sheet of the stack in operative contact with the sheet feed means. Sheet feeders with automatically elevating support trays are well known and are used particularly in high performance commercial copiers where high capacity trays are required. For example, in the Xerox 9700 and 1050 machines the main copy sheet supply tray in both cases is of this automatic elevator type. The operator places a loose stack of sheets on the tray by hand. Then when an appropriate signal is given, e.g. by pressing a control button or closing a cover door, the tray is raised automatically until the top sheet of the stack is brought into operative contact with the feed mechanism. As the sheets are fed from the top of the stack into the processing portion of the copier during use, the height of the stack reduces and as it does so, the tray is elevated automatically to keep the top sheet of the stack in contact with the feed mechanism. To replace or change the stack of copy sheets at any time the support tray is automatically lowered to a base position in response to an appropriate signal, for example when the cover door is opened or when the operator presses an appropriate control button. In some circumstances it may be desirable to change the stack of copy sheets quite frequently. For example, particularly in a "copy centre" environment, there will be a need to run a whole variety of different throughput materials such as various weights and colours of paper, card stock, pre-punched paper, envelopes, labels, transparencies for overhead projectors, drawing film, and customised pre-printed materials like letter headed paper. Each time a different throughput material is used the stack has to be physically handled by the operator first as it is inserted into the machine and subsequently as it is removed to make way for a stack of different material. During handling and also during storage the loose stacks of different sheets are vulnerable to contamination and damage which are detrimental to copy quality, high performance machines especially being sensitive to the surface characteristics of the copy sheets, their moisture content, and also to any debris present on the surface of the sheets. US-A-4 504 053 discloses a sheet feed apparatus of a different type, comprising a fixed base table rather than an elevating support tray. A sheet containing bin is located on the base table. A lift is located at the centre of the base table and is arranged to rise through an opening therein. The bin, which has a completely open top face, also has an opening in its bottom face through which the lift moves to engage a pallet supporting a stack of sheets within the bin thus raising the stack to a top-sheet feeding apparatus, the bin being locked automatically to the base table when the lift is operational. Yet another type of sheet feed apparatus, which also does not have an elevating support tray, is disclosed in FR-A-2 019 154. In that apparatus, a stack of sheets is supported on a receiving plate which, during operation of the apparatus, remains stationary. The sheet feed means comprises a roller supported on a rocking arm so that, as sheets are fed from the stack, the roller can move downwards to remain in operative engagement with the top of the stack. According to the present invention, a sheet feed apparatus having the features specified in the opening paragraph is characterised in that at least one upwardly projecting member is present on the tray in fixed relation therewith, and in that the stack of sheets is provided on the tray in a cartridge having in its bottom face adjacent the support tray an opening permitting entry of said projecting member, the cartridge containing vertically movable plate for supporting the stack of sheets and extending over the opening in the bottom face thereby in operation the projecting member on the elevating tray bears against the underside of the plate so that the plate and the stack of sheets supported thereon are raised to bring the top sheet of the stack into operative contact with the feed means. Preferably the shape of the opening in the bottom face of the cartridge is complementary to the shape of the projecting member, thereby providing a locating feature for the cartridge on the tray. In one embodiment the cartridge comprises a generally enclosed rectangular container for holding the stack of sheets, the container having a first opening in the top face for exposing a portion of the top sheet to permit the sheet feed means to engage said top sheet, and a second opening in a side face and extending to the top edge of said side face, through which second opening sheets can be fed from the top of the stack. In operation, the top sheet of the stack is brought into contact with the top face of the container thereby raising the container until the top sheet of the stack is brought into operative contact with the sheet feed means. The use of this cartridge to hold the stack of sheets not only simplifies change over of throughput material, but also means that the individual sheets are less likely to be damaged or contaminated because the operator does not actually touch the stack when it is being loaded into and out of the sheet feed apparatus. The cartridge also provides a convenient means of storing either full or part-used stacks of sheets, its generally enclosed construction helping to protect the contents from the environment without the need for a separate protective storage box. In apparatus in accordance with the invention, the at least one upwardly projecting member may be removably mounted on the supporting tray. The apparatus may, for example, include means for attaching the projecting member(s) to the upper side of the support tray, to removably mount the projecting member in fixed relationship with the support tray. In that way, a conventional sheet feed apparatus having an automatically elevating stack support tray can be converted quickly and easily to operate with a cartridge instead of a loose stack of sheets. An embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which:- Figure 1 is a schematic sectional view of a known sheet feed apparatus of the automatic elevator type, Figure 2 is a schematic perspective view of a sheet feed apparatus employing a cartridge for holding the sheets to be fed in accordance with the invention, and Figures 3a to 3c are schematic sectional views of the sheet feed apparatus in Figure 1 at various stages during operation. For comparative purposes there is shown schematically in Fig. 1 a known sheet feed apparatus of the type used in the main paper supply tray of commercially available xerographic machines such as the Xerox 9700 and 1050. The apparatus comprises a horizontal support tray 100 on which is located a loose stack of sheets 5 to be fed. The sheets may be retained by lateral guide members not shown in the Figure. The support tray 100 is driven and controlled in such a manner that it rises automatically to keep the top sheet of the stack in operative contact with a top-sheet feed roll 10 so that when the roll 10 is driven in the direction of arrow A the top sheet is fed from the stack in the direction of arrow B into the copier. Figure 2 shows how the known apparatus is converted to operate with a cartridge in accordance with the invention. For this purpose an adaptor 20 is provided which comprises a flat rectangular platform 1 having an upwardly projecting rectangular block 2 at its centre. The adaptor 20 is attached to the elevating paper tray 100, for example, by means of complementary magnetic strips 1a, 1b; 100a, 100b disposed on the underside of the platform 1 and the upper side of the tray 100 respectively. If, however, the tray 100 itself is made of a material which is itself magnetic, e.g. steel, the magnetic strips thereon can be dispensed with. Needless to say there are many different ways of fixing the adaptor 20 to the tray 100, for example by screwing, riveting or glueing. The advantage of the adaptor is that it enables an existing apparatus having a conventional flat elevating support tray 100 to be converted quickly and easily by the operator without the need for a retrofit by a skilled engineer. Also, the adaptor can easily be removed or replaced by the operator for different applications. Alternatively, however the projecting member may be designed into the original apparatus in which case the projecting member may be provided as an integral part of the elevating paper tray. Above the block 2 is present a cartridge 3 holding the stack of sheets 5 to be fed. The cartridge 3 comprises a generally enclosed rectangular container 4 made, for example, of paper board or plastics material. In Figure 2 the walls of the container 4 are shown to be transparent so the contents can readily been seen. In the bottom face 6a of the container 4 at the centre is a rectangular aperture 7 slightly larger than the block 2. Inside the container 4, adjacent the bottom face 6a is a rigid, rectangular plate 8 covering the aperture 7. The plate which may be made of, for example, paper board is loose and, being slightly smaller than the container 4, is slidable vertically therein. The stack of sheets 5 to be fed is disposed on the plate 8. The lateral dimensions of the container are such that the stack of sheets fits loosely therein and the depth of the container 4 is chosen to accommodate the desired number of sheets, typically 500 or 1000. The top face 6b of the container 4 has a concave cutaway portion 9 at the front edge, exposing the top sheet of the stack. The top-sheet feed roll 10 can thus bear against the top sheet and as the feed roll 10 is rotatably driven the top sheet is fed out through an elongate aperture 11 at the top edge of the front face 6c of the container 4, the aperture 11 extending substantially the full width of the front face 6c. The manner in which the apparatus operates with a cartridge as described above will now be described with references to Figures 3a to 3c. In order to insert or change a cartridge 3 the support tray 100 is lowered automatically (as in the known apparatus) to a base position well below the level of the feed roll 10 as shown in Figure 3a. The operator then takes the cartridge 3 filled, or partially filled, with the stack of sheets 5 to be fed, and locates the aperture 7 in the bottom face 6a of the container 4 over the projecting block 2 so that the block 2 bears against the underside of the plate 8 inside the container 4. The tray 100 is then raised automatically (again as in the known apparatus) until the top-sheet feed roll 10 engages the top sheet of the stack 5 through the aperture 9 in the top face 6b of the cartridge container 4, see Figure 3b. As the feed roll 10 is driven in the direction of arrow A the top sheet is fed from the stack out through the elongate aperture 11 in the front face 6c of the container 4 in the direction of arrow B into the copier. Figure 3c shows the situation when about half of the sheets have already been fed from the stack and the tray 100 has been raised automatically to compensate so as to keep the top sheet in contact with the feed roll 10. The tray will continue rising automatically until the last sheet in the stack has been fed, whereupon it may be lowered automatically back to the base position for the operator to reload a fresh cartridge. It will be evident from the foregoing that the height of the block 2 must be approximately the same as (or greater than) the depth of the container 4 in order to ensure that the bottom sheets of the stack will be pushed up as far as the feed roll 10. Before the entire stackof sheets has been used up the tray 100 may be lowered at the operator's instigation, e.g. by pushing a control button or opening a cover door in known manner. Thus a cartridge can be removed before it is empty and changed for a different cartridge containing different sheet material, e.g. different coloured paper. Of course the newly inserted cartridge may contain a part-used stack of sheets in which case Figure 3c represents the situation immediately after the cartridge has been inserted and the tray 100 has been raised automatically until the top sheet of the part-used stack engages the feed roll 10. As before the tray 100 will continue to rise automatically thereafter to keep the top sheet in operative contact with the feed roll 10 until all the sheets have been fed or until the operator wishes to change the cartridge again. It will be evident to a person skilled in the art that various modifications may be made within the scope of the present invention. For example, the aperture in the top face of the container may be rectangular rather than concave, and may extend the full width of the cartridge. Also, the projecting member may comprise, instead of a relatively large central block, an array of, for example five pillars, four being located at the corners of a rectangle and one at the centre thereof. In this case, the opening in the bottom face of the container may remain as a single rectangular aperture, but large enough to accommodate all the pillars, or alternatively there may be five individual apertures complementing the five pillars.

Claims: A sheet feed apparatus comprising a support tray (100) for a stack of sheets to be fed, and means (10) for feeding the top sheet of the stack, wherein said tray is elevated automatically to maintain the top sheet of the stack in operative contact with the sheet feed means, characterised in that at least one upwardly projecting member (2) is present on the tray in fixed relationship therewith, and in that the stack of sheets (5) is provided in a cartridge (3) having in its bottom face (6a) adjacent the support tray an opening (7) permitting entry of said projecting member, the cartridge containing a vertically movable plate (8) for supporting the stack of sheets and extending over the opening in the bottom face whereby in operation the projecting member on the elevating tray bears against the underside of the plate so that the plate and the stack of sheets supported thereon are raised to bring the top sheet of the stack into operative contact with the feed means. A sheet feed apparatus as claimed in claim 1, wherein the shape of the opening in the bottom face of the cartridge is complementary to the shape of the projecting member, thereby providing locating means for the cartridge. A sheet feed apparatus as claimed in claim 1 or claim 2, wherein the cartridge comprises a generally enclosed rectangular container for holding the stack of sheets, the container having a first opening (9) in the top face (6b) for exposing a portion of the top sheet to permit the sheet feed means to engage said top sheet, and a second opening (11) in a side face (6c) and extending to the top edge of said side face, through which second opening sheets can be fed from the top of the stack, whereby in operation the top sheet of the stack is brought into contact with the top face of the container thereby raising the container until the top sheet of the stack is brought into operative contact with the sheet feed means. A sheet feed apparatus as claimed in any one of the preceding claims, in which the at least one upwardly projecting member is removably mounted on the support tray. A sheet feed apparatus as claimed in any one of the preceding claims, including means (1a, 100a; 1b, 100b) for attaching said projecting member(s) to the upper side of the support tray, to removably mount the projecting member in fixed relationship with the support tray.

Inventors: PENSON, CHRISTOPHER JOHN
Applicants: XEROX CORPORATION
Application year: 1987
Main classification: G03G15
IPC codes: B65H1, G03G15