Sheet feeder cassette

Abstract: A sheet feeder comprises a telescopic structure which has a plurality of stages of sheet supporting bodies and all stages of the sheet supporting bodies are provided with top plates for covering the areas above the sheets, wherein the top plate for, at least, the last-stage sheet supporting body has of the plate member that is attached rotatably to an upper rear end part of the sheet supporting body of a stage previous to the last. The plate member can be pivoted so as to be placed on the top plate of the previous-stage sheet supporting body. The sheet feeder cassette is attached to an image forming apparatus and the top plates and such constitute the supporting body for the sheets which are discharged from the image forming apparatus.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeder cassette for holding of sheets to be supplied to such an image forming apparatus as a printer, a plotter, a photocopier or a telecopier. 2. Description of the Related Art A conventionally-known sheet feeder cassette has a shape of box which stores sheets to be fed. Since this type of sheet feeder cassette has a top plate, an advantage thereof is that the stored sheets are protected from dusts and such which may stick to the surfaces thereof. Since the image forming apparatus forms images on sheets of various sizes, the sheet feeder cassettes are designed so as to store the sheets of various sizes. For example, a sheet feeder cassette, which can store sheets of both A3 size that is comparatively large and A4 size that is comparatively small, is formed in a size that is appropriated to A3 which is the larger size and thus, when the smaller sheets of A4 size are stored, a partition plate or the similar which is provided inside the cassette is moved so as to match the A4 size or a partition plate is installed inside the cassette so that the A4-size sheets can be held. In the sheet feeder cassette described above, since the size of the cassette itself remains in a size which is appropriate for the A3 size even when the A4-size sheets are stored, it occupies a large installation space. Such a problem as above can be solved by a telescopic structure of the sheet feeder cassette. However, if the sheet feeder cassette is of a telescopic structure simply with a plurality of sheet supporting bodies to constitute a plurality of stages, thickness of the sheet supporting bodies becomes the smaller as the stage is closer to the rear end and, as the result, another problem that the quantity of storable sheets becomes the smaller is aroused. EP-A-0 529 803 describes a telescopic paper cassette for an image forming device wherein, however, the individual segments of the telescopic paper cassette do not comprise any top plates. A cover is provided on one of the printer body and the paper cassette for covering an upper surface of a rear portion of the paper cassette when the cassette is mounted into the body with the rear portion projecting rearwardly from a rear end of the printer body. SUMMARY OF THE INVENTION In view of such problems as described above, the present invention is purposed to provide a sheet feeder cassette wherein a telescopic structure can reduce the installation space thereof and wherein reduction in decrease in the quantity of storable sheets can be prevented. According to the present invention, there is provided a sheet feeder cassette a plurality of sheet supporting bodies being connected sequentially so as to form a telescopic structure. Each of said sheet supporting bodies has a top plate for covering an upper surface of sheets stored in said sheet supporting bodies. At least the top plate of the sheet supporting body forming the outermost stage of the telescopic structure is attached to the upper side of a sheet supporting body forming a previous stage of the telescopic structure. Said top plate of said sheet supporting body forming the outermost stage comprises a plate member pivotally attached to an upper rear end part of said sheet supporting body forming the previous stage. Further, said plate member can be pivoted so as to be placed on a top plate of said one sheet supporting body existing in the previous stage. Furthermore, when said sheet supporting bodies existing in the last and previous stages are stored in one sheet supporting body existing in a more previous stage to the previous stage, said plate member is preferably accommodated in a recess formed in a top plate for said one sheet supporting body existing in the more previous stage. Still further, said sheet feeder cassette can be designed so as to be attached to an image forming apparatus, and said top plates support the sheet discharged from the image forming apparatus unitedly. Since the sheet feeder cassette according to the present invention has a telescopic structure with a plurality of sheet supporting bodies to constitute a plurality of stages, an installation space thereof can be reduced by extending or compressing the cassette size so as to match various sizes of the sheets. Additionally, since all stages of the sheet supporting bodies are provided with top plates for covering the areas above the sheets, dusts and such are prevented from sticking to the surface of the stored sheets. Moreover, since the top plate for, at least, the last-stage sheet supporting body has the plate member that is attached pivotally to the upper rear end part of the sheet supporting body of a stage previous to the last, the quantity of the sheets to be stored can be increased by the thickness of the top plate. To describe this more in detail, if a sheet feeder cassette has a telescopic structure simply with a plurality of sheet supporting bodies to constitute a plurality of stages, for instance, and if all stages of the sheet supporting bodies are provided with top plates for covering the areas above the sheets, the second-stage sheet supporting body, for example, must be stored inside the first-stage sheet supporting body and thus the thickness of the second-stage sheet-supporting body is smaller than the first-stage sheet supporting body by at least the thicknesses of the bottom plate and the top plate thereof; the thickness of the storable sheets (that is, the quantity of the sheets) is subject to the thickness of the second-stage sheet supporting body and thus, as the result, the thickness of the storable sheets (that is, the quantity of the sheets) which are spread over the first-and the second-stage sheet supporting bodies is only a remainder of the thickness of the first-stage sheet supporting body lessened by the thicknesses of the bottom plate and the top plate of the second-stage sheet supporting body. On the contrary, in the sheet feeder cassette according to the present invention, the top plate for, at least, the last-stage sheet supporting body has the plate member that is attached pivotally to the upper rear end part of the sheet supporting body of a stage previous to the last, can increase at least the thickness of the storable sheets which are spread over the last-stage and the previous-to-the-last-stage sheet supporting bodies by as much as the thickness of the top plate. Further, the aforenamed plate member can be pivoted so as to be placed on a top plate of the aforenamed previous-stage sheet supporting body, the plate member will not be in the way when the last-stage sheet supporting body is stored inside the previous-stage sheet supporting body. Further, the aforenamed sheet feeder cassette is designed so as to be attached to an image forming apparatus and wherein the aforenamed top plates constitute a supporting body for sheets which are discharged from the image forming apparatus, the image forming apparatus needs not to be provided with another discharged-sheet supporter and, consequently, the image forming apparatus can be made compact. BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings: Fig. 1 is a plan of a printer as an example of the image forming apparatus with adoption of a mode of an embodiment of a sheet feeder cassette related to the present invention; Fig. 2 is a left-side view of the same; Fig. 3 is a right-side view of the same; Fig. 4 is a perspective view of the printer in which a second-stage sheet supporting body of the sheet feeder cassette is drawn out from a first-stage sheet supporting body; Fig. 5 is a perspective view of the printer in which a third-stage sheet supporting body of the sheet feeder cassette is drawn out from the second-stage sheet supporting body; and Fig. 6 is a perspective view of the printer in which a plate member is turned over onto the third-stage sheet supporting body. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described with references to drawings. Fig. 1 is a plan of a printer as an example of the image forming apparatus with adoption of a mode of embodiment of a sheet feeder cassette related to the present invention, Fig. 2 is a left-side view and Fig. 3 is a right-side view. These figures show a printer main body 10 and a sheet feeder cassette 20. As shown in Figs. 1 and 3, the sheet feeder cassette 20 in this mode of embodiment has a telescopic structure comprising three stages of sheet supporting bodies 21, 22 and 23. The first-stage sheet supporting body 21 has a shape of square pipe which comprises a bottom plate 21a, a pair of lateral side plate 21b and a top plate 21c, and has such a structure as to be detachably attached to the printer main body 10. The second-stage sheet supporting body 22 has a shape of square pipe which comprises a bottom plate 22a, a pair of lateral side plate 22b and a top plate 22c, and has such a structure as to emerge from and submerge into the above-described first-stage sheet supporting body 21 in directions of arrows Y1 and Y2. Fig. 4 shows a state in that the second-stage sheet supporting body 22 is drawn out from the first-stage sheet supporting body 21. The virtual lines in Figs. 1 and 3 show a drawn-out state. The third-stage sheet supporting body 23 which is the last-stage sheet supporting body of this mode of embodiment comprises a bottom plate 23a and a rear end wall 23d, and has such a structure as to emerge from and submerge into the above-described second-stage sheet supporting body 22 in directions of arrows Y1 and Y2. Fig. 5 shows a state in that the third-stage sheet supporting body 23 is drawn out from the second-stage sheet supporting body 22. The third-stage sheet supporting body 23 may be but does not have to be provided with lateral side plates. The virtual lines in Figs. 1 and 3 show a drawn-out state. A plate member 23c constitutes the top plate of the last-stage sheet supporting body 23. The plate member 23c is attached pivotally to an upper rear end part 22d of the previous-stage sheet supporting body which is the second-stage sheet supporting body 22 in this mode of embodiment with hinges 22e (see Figs. 3 and 6). After the second- and the third-stage sheet supporting bodies 22 and 23 are drawn out as indicated in virtual lines A in Fig. 3, if the plate member 23c is turned over onto the third-stage sheet supporting body 23 as indicated in virtual lines B, a fore end 23c1 thereof comes into contact with the rear end wall 23d to form a top plate for the third-stage sheet supporting body 23 (Fig. 6). When the third-stage sheet supporting body 23 is stored inside the second-stage sheet supporting body 22, as indicated in virtual lines C in Fig. 3, the plate member 23c is placed on the top plate 22c for the second-stage sheet supporting body 22. Furthermore, when the second-stage sheet supporting body 22 is stored in the first-stage sheet supporting body 21, as indicated in solid lines in Fig. 1, the plate member 23c is accomodated in a recess 21d which is formed in the top plate 21c for the first-stage sheet supporting body 21. Through telescopic operations of the sheet supporting bodies 21, 22 and 23, this sheet feeder cassette 20 holds sheets of various sizes, from postcard-size to longitudinally positioned A2 size. As indicated in virtual lines, longitudinally-positioned A2 size sheets can be stored in a state wherein the second- and the third-stage sheet supporting bodies are drawn out. Supporting plates are provided inside the cassette 20 for preventing stored small-sized sheets, such as A4 size, from shifting. The printer main body 10 picks up sheets placed inside the sheet feeder cassette 20, one sheet each time and, after printing, discharges the sheets onto the sheet feeder cassette 20. That is, the sheet feeder cassette 20 has a structure wherein the top plates 21c, 22c and 23c constitute a supporting part for the sheets discharged from the printer main body 10. In other words, top plates 21c, 22c and 23c support the discharged sheets unitedly. The following operational effects are obtained from the sheet feeder cassette 20 as described above: The telescopic structure which comprises three stages of sheet supporting bodies 21, 22 and 23, the installation space thereof can be reduced by extending or compressing the cassette size so as to match various sizes of the sheets. Additionally, since all stages of the sheet supporting bodies are provided with top plates for covering the areas above the sheets, dusts and such are prevented from sticking to the surface of the stored sheets. Moreover, since the top plate for, at least, the last-stage sheet supporting body 23 has the plate member 23c that is attached pivotally to the upper rear end part 22d of the sheet supporting body 22 of a stage previous to the last, the quantity of the sheets to be stored can be increased by the thickness of the top plate 23c. To describe this more in detail, if the sheet feeder cassette 20 has the telescopic structure simply with a plurality of sheet supporting bodies to constitute a plurality of stages, for instance, and if all stages of the sheet supporting bodies are provided with top plates for covering the areas above the sheets, the third-stage sheet supporting body 23, for example, must be stored inside the second-stage sheet supporting body 22 and thus the thickness of the third-stage sheet-supporting body 23 is smaller than the thickness of the second-stage sheet supporting body 22 by at least the thicknesses of the bottom plate 23a and the top plate 23c thereof; the thickness of the storable sheets (that is, quantity of the sheets) is subject to the thickness of the third-stage sheet supporting body 23 and thus, as the result, the thickness of the storable sheets (that is, quantity of the sheets) which are spread over the first-stage sheet supporting body 21 through the third-stage sheet supporting body 23 is only the remainder of the thickness of the second-stage sheet supporting body 22 lessened by the thicknesses of the bottom plate 23a and the top plate 23c of the third-stage sheet supporting body 23. On the contrary, the sheet feeder cassette in this mode of embodiment, wherein the top plate for, at least, the last-stage sheet supporting body 23 comprises the plate member 23c that is attached pivotally to an upper rear end part 22d of the sheet supporting body 22 of a stage previous to the last, can increase at least the thickness of the storable sheets which are spread over the last-stage and the previous-to-the-last-stage sheet supporting bodies by as much as the thickness of the top plate 23c. Further, since the plate member 23c can be pivoted so as to be placed on the top plate 22c of the previous-stage sheet supporting body 22, the plate member 23c will not be in the way when the last-stage sheet supporting body 23 is stored inside the previous-stage sheet supporting body 22. Further, since the top plates 21c, 22c and 23c of the sheet feeder cassette 20 constitute the supporting body for the sheets which are discharged from the printer main body 10, the printer main body 10 needs not to be provided with another discharged-sheet supporter and, consequently, the printer as a whole can be made compact. Although the mode of one embodiment of the present invention has been described above, the present invention is not restricted to the above embodiment, but there may be many modifications, changes, and alterations without departing from the scope or spirit of the main characteristics of the present invention. For example, although the above embodiment comprises three stages of sheet supporting bodies, two stages or four stages and more are also available. Further, in the aforementioned embodiment, the plate member 23c is attaced pivotally to the second-stage sheet supporting body 22. However, the plate member may be attaced slidably to the second-stage sheet supporting body.

Claims: A sheet feeder cassette (20) comprising a plurality of sheet supporting bodies (21, 22, 23) being connected sequentially so as to form a telescopic structure, characterized in that each of said sheet supporting bodies (21, 22, 23) has a top plate (21c, 22c, 23c) for covering an upper surface of sheets stored in said sheet supporting bodies (21, 22, 23), wherein at least the top plate (23c) of the sheet supporting body (23) forming the outermost stage of the telescopic structure is attached to the upper side of a sheet supporting body (22) forming a previous stage of the telescopic structure, and wherein said top plate (23c) of said sheet supporting body (23) forming the outermost stage comprises a plate member (23c) pivotally attached to an upper rear end part of said sheet supporting body (22) forming the previous stage. The sheet feeder cassette (20) according to claim 1, wherein said plate member (23c) can be pivoted so as to be placed on a top plate (22c) of said one sheet supporting body (22) existing in the previous stage. The sheet feeder cassette (20) according to claim 1 or 2, wherein, when said sheet supporting bodies (22, 23) forming the outermost and the previous stage are stored in a further sheet supporting body (21) forming a still previous stage to the previous stage, said plate member (23c) is accommodated in a recess (21d) formed in a top plate (21c) of said sheet supporting body (21) forming the still previous stage. The sheet feeder cassette (20) according to any one of the preceding claims, wherein said sheet feeder cassette (20) is designed so as to be attached to an image forming apparatus (10), and said top plates (21c, 22c, 23c) support the sheet discharged from the image forming apparatus (10) unitedly.

Inventors: KASHIWABARA KAZUTOSHI, YOKOYAMA KOICHIRO, KASHIWABARA, KAZUTOSHI, YOKOYAMA, KOICHIRO
Applicants: SEIKO EPSON CORP, SEIKO EPSON CORPORATION
Application year: 1998
Main classification: H04N1
IPC codes: B65H31, B41J13, B65H1