Sheet feeding device and image forming system

Abstract

To provide a sheet feeding device capable of improving convenience in replenishing a sheet placement part with a sheet.SOLUTION: A sheet feeding device includes a control unit 90. The control unit 90 arranges a lift plate 34 at a sheet feeding position during sheet feeding, and arranges the lift plate 34 at a standby position below the sheet feeding position during standby. Further, when a sheet presence / absence detection unit 80 does not detect a sheet in a state where the lift plate 34 is arranged at the sheet feeding position after a sheet feeding is completed, the control unit 90 sets the standby position to the lowest value. Further, when the sheet presence / absence detection unit 80 detects a sheet and a remaining amount detection unit 70 detects a fact that a remaining amount of sheets is equal to or less than a predetermined amount, the control unit 90 sets the standby position to a height between the sheet feeding position and the lowest value. Further, when the sheet presence / absence detection unit detects a sheet and the remaining amount detection unit 70 detects a fact that the remaining amount of sheets exceeds the predetermined amount, the control unit 90 sets the standby position to the lowest value.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a sheet feeding device that inserts a cover, an interleaf, etc. between a plurality of sheets on which images are formed by an image forming device such as a copying machine, a facsimile, or a printer, and to an image forming system using the same.

[0002] A conventional sheet feeding device has a sheet stacking section for stacking sheets, a lift plate arranged on the sheet stacking section, a lift mechanism for raising and lowering the lift plate, and a sheet feeding section arranged above and facing the lift plate for feeding the sheets lifted by the lift plate. The sheet feeding section has a paper feed roller, and as a first method, detects the presence or absence of a sheet on the lift plate when the lift plate rises and the sheet comes into contact with the paper feed roller. Also, as a second method, there is a method of installing a sensor on the lift plate to detect the presence or absence of a sheet. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-50144 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional sheet feeding device, in the first method, the presence or absence of a sheet cannot be detected until the lift plate comes into contact with the paper feed roller, so the presence or absence of a sheet cannot be detected before the user operates the job start button, and it is not possible to determine whether the job is ready to start. In addition, when the lift plate comes into contact with the paper feed roller, there is a problem that it is not convenient for the user to replenish sheets in the sheet stacking section.

[0005] In the second method, when the lift plate is lowered and there is a sheet remaining between the paper roller and the lift plate, the sheet between the paper feed roller and the lift plate does not lower with the lift plate. This increases the distance between the sensor and the sheet, and an expensive sensor with a long detection distance is required to detect the presence or absence of a sheet. This causes a problem of high manufacturing costs for the sheet feeding device.

[0006] In order to achieve the above object, the present invention aims to provide a sheet feeding device that can improve convenience when refilling a sheet stacking section with sheets and reduce manufacturing costs, and an image forming system including the same. [Means for solving the problem]

[0007] In order to achieve the above object, a sheet supplying device of a first configuration of the present invention includes a sheet stacking section, a lift plate, a lift mechanism, a sheet feeding section, a sheet presence / absence detection section, a remaining amount detection section, and a control section. The sheet stacking section stacks sheets. The lift plate is disposed on the sheet stacking section and supported so as to be movable up and down. The lift mechanism raises and lowers the lift plate. The sheet feeding section is disposed above and facing the lift plate, and abuts against and feeds the sheets lifted by the lift plate. The sheet presence / absence detection section is provided on the lift plate and detects whether or not sheets are stacked on the lift plate. The remaining amount detection section detects the remaining amount of the stacked sheets based on the height of the lift plate. The control section controls the lifting and lowering of the lift plate. The control section places the lift plate in a paper feed position when feeding sheets, and places the lift plate in a standby position below the paper feed position when on standby. Furthermore, when the sheet presence / absence detection unit does not detect a sheet with the lift plate disposed at the sheet feed position after the sheet feeding is completed, the control unit sets the standby position to the lowest value. Furthermore, when the sheet presence / absence detection unit detects a sheet and the remaining amount detection unit detects that the remaining amount of sheets is equal to or less than a predetermined amount, the control unit sets the standby position to a height between the sheet feed position and the lowest value. Furthermore, when the sheet presence / absence detection unit detects a sheet and the remaining amount detection unit detects that the remaining amount of sheets exceeds the predetermined amount, the control unit sets the standby position to the lowest value. Effect of the Invention

[0008] According to the first configuration of the present invention, it is possible to provide a sheet feeding device that can improve the convenience when refilling a sheet stacking section with sheets and can reduce manufacturing costs. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing an internal configuration of an image forming system according to an embodiment of the present invention. [Diagram 2] FIG. 1 is a perspective view showing a sheet stacking portion of a sheet feeding device according to an embodiment of the present invention; [Diagram 3] FIG. 1 is a perspective view showing a sheet stacking portion of a sheet feeding device according to an embodiment of the present invention; [Figure 4] FIG. 1 is a cross-sectional view showing the vicinity of a sheet stacking portion of a sheet feeding device according to an embodiment of the present invention, viewed from a sheet width direction. [Diagram 5] FIG. 1 is a cross-sectional view showing the vicinity of a sheet stacking portion of a sheet feeding device according to an embodiment of the present invention, viewed from a sheet width direction. [Figure 6] FIG. 1 is a partial enlarged view showing the vicinity of a sheet feeding portion of a sheet feeding device according to an embodiment of the present invention; [Figure 7] FIG. 1 is a partial enlarged view showing the vicinity of a sheet feeding portion of a sheet feeding device according to an embodiment of the present invention; [Figure 8] FIG. 1 is a cross-sectional view showing the vicinity of a sheet stacking portion of a sheet feeding device according to an embodiment of the present invention, viewed from a sheet width direction. [Figure 9] FIG. 1 is a cross-sectional view showing the vicinity of a sheet stacking portion of a sheet feeding device according to an embodiment of the present invention, viewed from a sheet width direction. [Figure 10] FIG. 1 is a cross-sectional view showing the vicinity of a sheet stacking portion of a sheet feeding device according to an embodiment of the present invention, viewed from a sheet width direction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a sheet feeding device and an image forming system using the same of the present invention will be described with reference to the drawings.

[0011] <1. Image forming system configuration> 1 is a schematic diagram showing the internal configuration of an image forming system 100. The image forming system 100 is composed of an image forming apparatus 1, a sheet feeding apparatus 2, and a paper post-processing apparatus 3. Note that, in this embodiment, an image forming system 100 will be described in which an inkjet recording printer is used as the image forming apparatus, but other image forming apparatuses (for example, a laser printer, a copier, a facsimile machine, etc.) can also be used.

[0012] The direction in which the output sheet P1 output from the image forming apparatus 1 and the insertion sheet P2 inserted from the sheet feeding apparatus 2 are transported toward the paper post-processing apparatus 3 is referred to as the sheet transport direction. Furthermore, the paper post-processing apparatus 3 is defined as the downstream side in the sheet transport direction, and the paper storage unit 4 of the image forming apparatus 1 that stores the output sheet P1 and the sheet stacking unit 10 of the sheet feeding apparatus 2 on which the insertion sheet P2 is stacked are defined as the upstream side in the sheet transport direction.

[0013] A sheet feeding device 2 is connected downstream of the image forming device 1. A paper post-processing device 3 is connected downstream of the sheet feeding device 2.

[0014] <1-1. Configuration of Image Forming Apparatus> The image forming device 1 includes a paper storage section 4 provided at the bottom of the image forming device 1, a paper transport path 6 arranged to the side of the paper storage section 4 and extending downstream in the sheet transport direction, a paper feeding section 5 provided between the paper transport path 6 and the paper storage section 4, an image recording section 7 arranged opposite the paper transport path 6 in the height direction, and an inversion transport section 8 branching off from the paper transport path 6 and extending above the image recording section 7.

[0015] The paper storage section 4 is provided with a plurality of (three in this example) detachable paper feed cassettes 4a in which a stack of output sheets P1 is stacked. The paper feed section 5 feeds the output sheets P1 stored in the paper storage section 4 to a paper transport path 6 by a pair of feed rollers 5a provided downstream in the paper feed direction of each paper feed cassette 4a.

[0016] An endless conveyor belt 6a is provided below the image recording unit 7, and is wound around multiple rollers including a drive roller. The conveyor belt 6a is provided with a large number of ventilation holes (not shown) for suctioning air. The output sheet P1 sent out from the paper feed unit 5 passes below the image recording unit 7 while being attracted to and held by the conveyor belt 6a by a paper suction unit provided inside the conveyor belt 6a.

[0017] The image recording unit 7 includes a plurality of inkjet heads that eject ink toward an output sheet P1 that is attracted to and held by a conveyor belt 6a and conveyed. Ink of four colors (cyan, magenta, yellow, and black) stored in ink tanks (not shown) is supplied to each inkjet head for each color of the inkjet head.

[0018] When recording on both sides of the output sheet P1, the reversing conveying section 8 reverses the output sheet P1 by switching (switching back) the conveying direction of the output sheet P1 after recording on one side is completed, and then conveys the output sheet P1 again with the side on which no image is recorded facing upward to the image recording section 7. The output sheets P1 on which a predetermined image has been recorded by the image recording section 7 are discharged one by one from a pair of discharge rollers 9.

[0019] <1-2. Configuration of the Sheet Feeding Device> The sheet feeding device 2 carries in the output sheets P1 discharged from the image forming device 1 one by one, and inserts insertion sheets P2, such as a cover sheet and a backing sheet (cover sheet) used in bookbinding and an insert sheet (insert sheet) for identification, between the multiple output sheets P1 carried in at a predetermined timing. Then, the output sheets P1 and the insertion sheets P2 are transported to the paper post-processing device 3.

[0020] The sheet feeding device 2 includes a sheet stacking section 10. Insertion sheets P2 are stacked on the sheet stacking section 10. Below the sheet stacking section 10, there are provided a paper inlet 12 for receiving the output sheet P1 discharged from the image forming device 1, and an intermediate transport path 11 for transporting the output sheet P1 from the paper inlet 12 to the paper post-processing device 3. The intermediate transport path 11 is provided with an intermediate transport roller 15. The intermediate transport roller 15 transports the received output sheet P1 downstream.

[0021] An insertion conveying path 16 is provided above the relay conveying path 11. An upstream end opening 19 of the insertion conveying path 16 is adjacent to the sheet stacking unit 10 in the sheet conveying direction. A downstream end of the insertion conveying path 16 is a junction 13 that joins the relay conveying path 11. The insertion conveying path 16 is a path that communicates the sheet stacking unit 10 and the relay conveying path 11. A sheet feeding section 14 is provided above the upstream end opening 19 of the relay conveying path 11. The sheet feeding section 14 has a feed roller 51 that is provided adjacent to the upstream end opening 19 of the insertion conveying path 16 in the sheet conveying direction. The sheet feeding section 14 feeds the insertion sheet P2 from the sheet stacking unit 10 to the insertion conveying path 16 by the feed roller 51. A conveying roller pair 17 is provided at a midpoint of the insertion conveying path 16 in the sheet conveying direction. The insertion sheet P2 fed to the insertion conveyance path 16 is conveyed to the junction 13 by the conveyance roller pair 17, inserted into the relay conveyance path 11, and conveyed to the paper post-processing device 3.

[0022] <1-3. Configuration of paper post-processing device> The paper post-processing device 3 performs predetermined post-processing such as punch hole formation processing and binding processing on a sheet stack including multiple output sheets P1 output from the image forming device 1 and an insertion sheet P2 placed between the multiple output sheets P1.

[0023] The paper post-processing device 3 is provided with a paper entrance 21 that receives the output sheets P1 and the insert sheets P2 transported from the sheet feeding device 2. Inside the paper post-processing device 3, there are provided a punch hole forming device 22 that performs a punch hole forming process on the output sheets P1 and the insert sheets P2 transported from the paper entrance 21, an end binding unit 23 that stacks the transported output sheets P1 and the insert sheets P2 to form a sheet bundle, aligns the ends of the sheet bundle and staples them, and a saddle stitching and center folding unit 25 that staples the center of the sheet bundle and then folds it around the stapled part to form a booklet. On the side of the paper post-processing device 3, there are provided a main tray 24a that can be raised and lowered to a position suitable for discharging the sheet bundle, and a sub-tray 24b fixed to the upper part of the paper post-processing device 3.

[0024] The punch hole forming device 22 is disposed above the paper post-processing device 3. The output sheet P1 and the insertion sheet P2 that have passed through the relay transport path 11 of the sheet feeding device 2 are fed from a paper entrance 21 provided at the upper right of the paper post-processing device 3, and pass through the punch hole forming device 22. If the output sheet P1 and the insertion sheet P2 are not stapled and the sub-tray 24b is selected as the discharge destination, the output sheet P1 and the insertion sheet P2 are discharged directly to the sub-tray 24b. If the staple process is performed, the output sheet P1 and the insertion sheet P2 are transported to the end stitching unit 23 or the saddle stitching and center folding unit 25 disposed below the punch hole forming device 22.

[0025] The edge binding unit 23 is composed of a stapler and a processing tray (neither of which are shown). The output sheets P1 and the insertion sheets P2 are stacked on the processing tray to form a bundle of sheets. The bundle of sheets is transferred to a stapler provided at the end of the processing tray with the leading edge of the bundle aligned, and the end is stapled, and then the bundle is discharged along the processing tray to the main tray 24a.

[0026] The saddle stitching and center folding unit 25 for saddle stitching and center folding, which is disposed below the end stitching unit 23, is composed of a saddle stitching stapler, a center folding device, and a paper guide (none of which are shown), etc. The saddle stitching stapler staples the center of the sheet stack loaded in the paper guide. The sheet stack stapled by the saddle stitching stapler is folded into a booklet around the stapled portion by the center folding device, and then discharged to the booklet tray 26.

[0027] The sheet stacking unit 10 provided in the sheet feeding device 2 may be a single unit, or a configuration in which multiple sheet stacking units 10 are provided as shown in Fig. 1 may be adopted. When a configuration in which multiple sheet stacking units 10 are provided is adopted, different types of insertion sheets can be loaded on each sheet stacking unit 10 to create a booklet that uses different insertion sheets for the front cover, back cover, etc.

[0028] <2. Detailed Configuration of Sheet Feeding Device> Next, the sheet feeding device 2 of the present invention will be described in detail with reference to FIGS.

[0029] 2 and 3 are perspective views showing one sheet stacking unit 10, with the lift plate 34 omitted in FIG. 3. FIGS. 4 and 5 are cross-sectional views showing the vicinity of the sheet feeding unit 14 from the sheet width direction, with FIG. 4 showing the lift plate 34 lowered to its lowest position and FIG. 5 showing the lift plate 34 raised to the sheet feeding position. The sheet feeding device 2 includes the sheet stacking unit 10, the lift plate 34, a lift mechanism 35, the sheet feeding unit 14, a remaining amount detection unit 70, a sheet presence / absence detection unit 80, and a control unit 90.

[0030] <2-1. Sheet stacking section configuration> The sheet stacking section 10 has a vertical wall portion 33 located downstream in the sheet conveying direction, a bottom surface 30 inclined upward from the vertical wall portion 33 toward the upstream side in the sheet conveying direction, and a pair of side surfaces 31 opposed to each other across the bottom surface 30 in the sheet width direction (direction perpendicular to the sheet conveying direction). The pair of side surfaces 31 are provided with shaft protrusions 32 protruding to face each other in the sheet width direction. An upstream end opening 19 of the insertion conveying path 16 is provided at an upper portion of the vertical wall portion 33.

[0031] <2-2. Lift plate configuration> The lift plate 34 is disposed on the sheet stacking section 10 and supported so as to be movable up and down. Specifically, the lift plate 34 is disposed on the bottom surface 30 of the sheet stacking section 10 and is surrounded by the vertical wall portion 33 and a pair of side surfaces 31. The insertion sheet P2 in the sheet stacking section 10 is stacked on the lift plate 34. The lift plate 34 is adjacent to the vertical wall portion 33 of the sheet stacking section 10 in the sheet transport direction. The upstream end of the lift plate 34 in the sheet transport direction is rotatably supported by the shaft protrusion 32. This allows the lift plate 34 to rotate around the shaft protrusion 32. When the lift plate 34 rotates around the shaft protrusion 32, the downstream end of the lift plate 34 in the sheet transport direction moves up and down in the height direction (the up and down direction shown in FIG. 4).

[0032] <2-3. Lift mechanism configuration> The lift mechanism 35 raises and lowers the downstream end of the lift plate 34, and is provided between the bottom surface 30 of the sheet stacking unit 10 and the lift plate 34. The lift mechanism 35 has a drive unit 36 ​​and a plurality of (here, two) operating pieces 38. The drive unit 36 ​​has a drive source (not shown) such as a motor that generates power, and a drive shaft 37 rotatably connected to the drive source. The drive shaft 37 is located below the lift plate 34 and extends in the sheet width direction so as to span between the pair of side surfaces 31. The drive shaft 37 is located downstream of the shaft protrusion 32 in the sheet conveying direction. The operating piece 38 is a rectangular plate-like body that is elongated in the sheet conveying direction. The upstream end of the operating piece 38 is fixed to the drive shaft 37. The operating pieces 38 are arranged at intervals in the sheet width direction. The operating pieces 38 rotate about the drive shaft 37 as the drive shaft 37 rotates. This causes the downstream end of the operating piece 38 to swing in the lifting direction (the up-down direction in FIG. 4).

[0033] As described above, since the drive shaft 37 is disposed below the lift plate 34, the operating piece 38 fixed to the drive shaft 37 is also located below the lift plate 34. Here, as shown in FIG. 5, when the drive shaft 37 rotates counterclockwise (in the direction of the arrow in the figure) by the power of the drive source, the downstream end of the operating piece 38 rises in response to the rotation. Then, the downstream end of the operating piece 38 comes into contact with the rear surface of the lift plate 34, and the downstream end of the lift plate 34 is lifted. In this way, the lift mechanism 35 can raise and lower the downstream end of the lift plate 34 by swinging the operating piece 38 using the power of the drive source.

[0034] <2-4. Configuration of remaining amount detection unit> The remaining amount detection unit 70 detects the remaining amount of the insertion sheets P2 stacked on the sheet stacking unit 10 based on the height of the lift plate 34. The remaining amount detection unit 70 includes a detection piece 39, a link mechanism 42, and a remaining amount detection sensor 48.

[0035] The detection piece 39 is provided on the drive shaft 37 so as to be adjacent to the operating piece 38 in the sheet width direction. The detection piece 39 is a small piece that is elongated in the sheet conveying direction. A through hole 40 that penetrates in the sheet width direction is formed at a base end 39a (the upstream end in the sheet conveying direction) of the detection piece 39. The drive shaft 37 is inserted into this through hole 40, so that the detection piece 39 is supported by the drive shaft 37 so as to be rotatable around the drive shaft 37. When the detection piece 39 rotates around the drive shaft 37, the downstream end of the detection piece 39 swings in the lifting and lowering direction. The downstream end of the detection piece 39 descends until it contacts the bottom surface 30 of the sheet stacking unit 10 due to its own weight. A rectangular plate-shaped light-shielding portion 41 that extends toward the downstream side in the sheet conveying direction is formed at the downstream end of the detection piece 39.

[0036] The detection piece 39 and the drive shaft 37 are connected via a link mechanism 42. The link mechanism 42 has an engagement piece 43 that protrudes radially from the drive shaft 37, and an engagement hole 44 formed in the base end 39a of the detection piece 39, into which the engagement piece 43 is inserted. The engagement hole 44 is a concave hole recessed in the direction in which the engagement piece 43 protrudes. An engagement surface 45 that faces the outer circumferential surface of the engagement piece 43 in the circumferential direction of the drive shaft is formed on an upper surface of the inner circumferential surface of the engagement hole 44.

[0037] As shown in FIG. 4, when the operating piece 38 is at a relatively low position and the lift plate 34 is at the lowest position, the rotation angle of the drive shaft 37 is relatively small, and a gap 46 (play) is generated between the engagement piece 43 and the engagement surface 45. When the drive shaft 37 rotates counterclockwise from this state, the engagement piece 43 also rotates around the drive shaft 37, and the gap 46 between the outer circumferential surface of the drive shaft 37 and the engagement surface 45 becomes smaller. When the drive shaft 37 rotates further from this state, the engagement piece 43 comes into contact with the engagement surface 45. Then, as shown in FIG. 5, the rotation of the drive shaft 37 is transmitted to the detection piece 39 via the engagement surface 45, and the detection piece 39 rotates around the drive shaft 37. In this way, the detection piece 39 rotates to follow the operation piece 38, with the timing shifted from the rotation of the operation piece 38.

[0038] When the drive shaft 37 rotates in the clockwise direction in the figure, the detection piece 39 descends by its own weight so as to follow the swing of the operating piece 38. Then, when the drive shaft 37 continues to rotate in the illustrated direction after the detection piece 39 descends until it contacts the bottom surface 30, a gap 46 is again generated between the outer circumferential surface of the engagement piece 43 and the engagement surface 45.

[0039] The remaining amount detection sensor 48 is provided on the bottom surface 30 of the sheet stacking unit 10 so as to be adjacent to the detection piece 39 in the sheet conveying direction. The remaining amount detection sensor 48 has a light emitting unit 49 and a light receiving unit 50 that face each other in the sheet width direction. The light receiving unit 50 receives light emitted from the light emitting unit 49.

[0040] The light-shielding portion 41 of the detection piece 39 is inserted between the light-emitting portion 49 and the light-receiving portion 50 of the remaining amount detection sensor 48 when there is a gap 46 between the engagement piece 43 and the engagement surface 45. In other words, when the rotation angle of the drive shaft 37 is relatively small and the rotation of the drive shaft 37 is not transmitted to the detection piece 39, the light-shielding portion 41 of the detection piece 39 is at the same height as the light-emitting portion 49 of the remaining amount detection sensor 48. Therefore, the light emitted from the light-emitting portion 49 is blocked by the light-shielding portion 41, and the light-receiving portion 50 cannot receive the light emitted from the light-emitting portion 49. At this time, the remaining amount detection sensor 48 is in the off state.

[0041] From this state, when the drive shaft 37 rotates as described above and the light blocking portion 41 rises to a position higher than the light emitting portion 49 (see FIG. 5), the light receiving portion 50 receives the light emitted from the light emitting portion 49. In this way, the remaining amount detection sensor 48 detects that the detection piece 39 has risen to a position higher than the light emitting portion 49, and thereby can detect the rise of the downstream end of the operating piece 38, i.e., that the lift plate 34 has risen above a predetermined height. At this time, the remaining amount detection sensor 48 turns on.

[0042] <2-5. Structure of sheet presence detection unit> The sheet presence / absence detection unit 80 is provided at the downstream end of the lift plate 34 and detects whether or not a sheet is stacked on the lift plate 34. Specifically, the sheet presence / absence detection unit 80 has a reflective paper detection sensor 81. The paper detection sensor 81 is a reflective optical sensor that detects light reflected from the underside of the insertion sheet P2. The paper detection sensor 81 has a light-emitting unit (not shown) and a light-receiving unit (not shown). The light-receiving unit receives light that is emitted from the light-emitting unit to the underside of the insertion sheet P2 and reflected.

[0043] When the paper detection sensor 81 detects light emitted to and reflected from the bottom surface of the insertion sheet P2 (paper detection sensor 81 is on), it can determine that the insertion sheet P2 is stacked on the lift plate 34. When the paper detection sensor 81 cannot detect light emitted to and reflected from the bottom surface of the insertion sheet P2 (paper detection sensor 81 is off), it can determine that the insertion sheet P2 is not stacked on the lift plate 34.

[0044] The sheet presence / absence detection unit 80 is provided on the lift plate 34 and rises and falls together with the lift plate 34. The paper detection sensor 81 is capable of detecting the insertion sheet P2 within a predetermined detection distance. The detection distance of the paper detection sensor 81 is shorter than the distance between the paper feed position and the lowest position and longer than the distance between the paper feed position and the standby position. The sheet presence / absence detection unit 80 may be disposed in a location other than the downstream end of the lift plate 34.

[0045] Furthermore, the sheet presence / absence detection unit 80 may be configured, for example, with an actuator (not shown) and a paper detection sensor 81. The actuator comes into contact with and swings over the insertion sheet P2 stacked on the lift plate 34. The paper detection sensor 81 detects that the swinging actuator blocks the light path.

[0046] At this time, the paper detection sensor 81 detects that the actuator has blocked the light path (paper detection sensor 81 is in the OFF state), thereby determining that the insertion sheet P2 is stacked on the lift plate 34. Also, the paper detection sensor 81 detects that the actuator has not blocked the light path (paper detection sensor 81 is in the ON state), thereby determining that the insertion sheet P2 is not stacked on the lift plate 34.

[0047] <2-6. Structure of the sheet feeding section> The sheet feeding section 14 has an apparatus body 20 disposed above the lift plate 34, a paper feed roller 51 provided on the apparatus body 20, and a light blocking piece 52 protruding in the sheet width direction from the apparatus body 20. The apparatus body 20 is provided so as to be movable up and down in the illustrated vertical direction. The paper feed roller 51 is adjacent to the upstream end opening 19 of the insertion conveying path 16 in the sheet conveying direction.

[0048] A lifting / lowering sensor 54 is provided at a position facing the device body 20 in the sheet width direction. The lifting / lowering sensor 54 has a light-emitting section 56 and a light-receiving section (not shown) facing each other in the sheet width direction. The light-receiving section of the lifting / lowering sensor 54 receives light emitted from the light-emitting section 56. The lifting / lowering sensor 54 and the light-shielding piece 52 constitute an upper surface detection mechanism 53. The upper surface detection mechanism 53 is capable of detecting that the insertion sheet P2 comes into contact with the paper feed roller 51 and that the device body 20 is at a position higher than a predetermined height.

[0049] 4, when the feed roller 51 and the upper surface of the insertion sheet P2 are not in contact with each other, the light-shielding piece 52 is inserted between the light-emitting part 56 and the light-receiving part of the lifting / lowering sensor 54. As a result, the light-shielding piece 52 blocks the light emitted from the light-emitting part 56 of the lifting / lowering sensor 54.

[0050] 6 and 7 are partial enlarged views showing the vicinity of the sheet feeding unit 14, and Fig. 6 shows a state in which the light receiving unit of the lifting / lowering sensor 54 receives light emitted from the light emitting unit 56. Fig. 7 shows a state in which the light blocking piece 52 blocks the light emitted from the light emitting unit 56 of the lifting / lowering sensor 54.

[0051] As shown in FIG. 6, when the upper surface of the insertion sheet P2 is in contact with the feed roller 51, the feed roller 51 rotates in the sheet conveying direction (counterclockwise direction in the figure), so that one insertion sheet P2 in contact with the feed roller 51 is fed toward the upstream end opening 19 of the relay conveying path 11. When one insertion sheet P2 is fed, the insertion sheet P2 stacked below the fed insertion sheet P2 comes into contact with the feed roller 51. In this way, while the feed roller 51 continues to rotate, the insertion sheets P2 on the sheet stacking unit 10 are fed one by one in order from the top. Therefore, the feed roller 51 can feed the insertion sheets P2 located on the upper surfaces of the multiple insertion sheets P2 one by one in succession to the insertion conveying path 16. At this time, the lift sensor 54 is turned on.

[0052] From the state shown in Fig. 6, the insertion sheets P2 in the sheet stacking section 10 are fed one by one to the insertion transport path 16, and when the remaining amount of the insertion sheets P2 decreases, the position of the upper surface of the insertion sheets P2 in the sheet stacking section 10 drops. Then, the force pressing the paper feed roller 51 weakens, and the device body 20 descends. When the device body 20 descends and the light blocking piece 52 is again inserted between the light emitting section 56 and the light receiving section of the lifting / lowering sensor 54 as shown in Fig. 7, the light emitted from the light emitting section 56 is blocked by the light blocking piece 52. At this time, the lifting / lowering sensor 54 is turned off.

[0053] <2-8. Configuration of the control unit> The control unit 90 is connected to the drive source, the paper detection sensor 81, the remaining amount detection sensor 48, and the lift sensor 54. The control unit 90 controls the drive of the drive source based on the detection results of the paper detection sensor 81, the remaining amount detection sensor 48, and the lift sensor 54, thereby raising and lowering the lift plate 34.

[0054] In the image forming system 100, when a print instruction is input by a user, the sheet feeding device 2 inserts an insertion sheet P2 between a plurality of output sheets P1 conveyed from the image forming apparatus 1 at a predetermined timing.

[0055] In a standby state before a print command is input, the lift plate 34 is separated from the sheet feeding section 14 and descends to a standby position where the remaining amount detection sensor 48 is in an OFF state. At this time, the device body 20 descends and the lift sensor 54 is in an OFF state.

[0056] When a print command is input, the control unit 90 raises the lift plate 34, and when the lift sensor 54 turns on, stops the lift of the lift plate 34. At this time, if the remaining amount of the insertion sheet P2 is less than a predetermined amount, the remaining amount detection sensor 48 turns on (see FIG. 5).

[0057] FIG. 8 is a cross-sectional view of the sheet stacking unit 10 in the sheet width direction, showing a state in which the remaining amount of the insertion sheet P2 is greater than a predetermined amount. The control unit 90 raises the lift plate 34 until the upper surface of the insertion sheet P2 comes into contact with the feed roller 51 and the lift sensor 54 is turned on. When the remaining amount of the insertion sheet P2 is greater than a predetermined amount, the lift plate 34 only rises to a position lower than a predetermined height. At this time, a small gap 46 is formed between the outer peripheral surface of the engagement piece 43 and the engagement surface 45, and the rotation of the drive shaft 37 is not transmitted to the detection piece 39. Therefore, the light-shielding portion 41 of the detection piece 39 is not raised and is inserted between the light-emitting portion 49 and the light-receiving portion 50 of the remaining amount detection sensor 48. As a result, the remaining amount detection sensor 48 is in an off state.

[0058] When the feed roller 51 rotates in the sheet transport direction from this state to feed the insertion sheets P2 one by one, the upper surface of the insertion sheets P2 drops. Therefore, the control unit 90 lifts the lift plate 34. At this time, the control unit 90 controls the drive source to rotate the drive shaft 37, so that the gap 46 between the outer periphery of the engagement piece 43 and the engagement surface 45 becomes smaller.

[0059] When the drive shaft 37 further rotates and the outer peripheral surface of the engagement piece 43 comes into contact with the engagement surface 45, eliminating the gap 46, the rotation of the drive shaft 37 is transmitted to the detection piece 39. When the drive shaft 37 further rotates from this state, the detection piece 39 gradually rotates. When the remaining amount of the insertion sheet P2 becomes less than a predetermined amount, the light-shielding portion 41 of the detection piece 39 becomes higher than the light-emitting portion 49 of the remaining amount detection sensor 48, and the remaining amount detection sensor 48 turns on.

[0060] The control unit 90 can determine that the remaining amount of the sheet stacking unit 10 is equal to or less than a predetermined amount based on the detection result of the remaining amount detection sensor 48. That is, when the lift sensor 54 is on and the remaining amount detection sensor 48 is off, the control unit 90 determines that the remaining amount of the insertion sheet P2 is greater than the predetermined amount. Also, when the lift sensor 54 is on and the remaining amount detection sensor 48 is on, the control unit 90 determines that the remaining amount of the insertion sheet P2 is less than the predetermined amount.

[0061] 9 and 10 are cross-sectional views of the sheet stacking unit 10 in the sheet width direction, showing a standby state after a print job is completed. In the image forming system 100, when a print job is completed, the control unit 90 lowers the lift plate 34 to a standby position and waits for the input of the next print job. At this time, with the lift plate 34 placed at the paper feed position, the control unit 90 determines whether or not the insertion sheet P2 is stacked on the lift plate 34, and determines whether or not the remaining amount of the insertion sheet P2 stacked on the lift plate 34 exceeds a predetermined amount, and controls the standby position of the lift plate 34 based on the determination result.

[0062] When the paper detection sensor 81 is in an OFF state, the control unit 90 determines that the insertion sheets P2 are not stacked on the lift plate 34, sets the standby position of the lift plate 34 to the lowest value, and lowers the lift plate 34 (see FIG. 10). This improves the convenience for the user when refilling the sheet stacking unit 10 with the insertion sheets P2.

[0063] On the other hand, when the paper detection sensor 81 is in the ON state, it is further determined whether or not the remaining amount of the insertion sheets P2 stacked on the lift plate 34 exceeds a predetermined amount. Specifically, when the lift sensor 54 is in the ON state and the remaining amount detection sensor 48 is in the OFF state, it is determined that the remaining amount of the insertion sheets P2 is greater than the predetermined amount, and when the lift sensor 54 is in the ON state and the remaining amount detection sensor 48 is in the ON state, it is determined that the remaining amount of the insertion sheets P2 is less than the predetermined amount.

[0064] When it is determined that the remaining amount of the insertion sheet P2 is less than a predetermined amount, the control unit 90 stops the lift plate 34 at a position higher than the lowest value (see FIG. 9). That is, the control unit 90 sets the standby position to a height between the paper feed position and the lowest value. Specifically, the control unit 90 stops the descent of the lift plate 34 when the remaining amount detection sensor 48 changes from an on state to an off state. By having the lift plate 34 standby at a high position, the time until paper feed starts when the next print job is input can be shortened.

[0065] On the other hand, if it is determined that the remaining amount of the insertion sheet P2 is greater than the predetermined amount, the standby position of the lift plate 34 is set to the lowest value, and the lift plate 34 is lowered.

[0066] By determining whether or not an insertion sheet P2 is loaded on the lift plate 34 when the printing job is completed and the lift plate 34 is positioned in the paper feed position, the control unit 90 can determine that an insertion sheet P2 is loaded on the lift plate 34, for example, when printing is completed with the insertion sheet P2 straddling the upstream end opening 19 of the insertion conveying path 16 and the lift plate 34.

[0067] At this time, the detection distance of the paper detection sensor 81 is shorter than the distance between the paper feed position and the lowest position, and longer than the distance between the paper feed position and the standby position. Therefore, by having the lift plate 34 standby at a high position, it is possible to easily detect a sheet straddling the upstream end opening 19 of the insertion transport path 16 and the lift plate 34. In addition, by using the paper detection sensor 81 with a short detection distance, it is possible to suppress an increase in costs. Furthermore, when the next print job is input, it is possible to shorten the time until feeding of the insertion sheet P2 straddling the upstream end opening 19 of the insertion transport path 16 and the lift plate 34 starts.

[0068] Note that while waiting for the input of a print job, if the paper detection sensor 81 is turned off, for example, because the insertion sheet P2 is removed, the control unit 90 sets the standby position of the lift plate 34 to the lowest value and lowers the lift plate 34. This improves the convenience for the user when refilling the sheet stacking unit 10 with the insertion sheet P2.

[0069] In addition, when the control unit 90 receives a notification that the power is off or that a jam has occurred, even if the paper detection sensor 81 is on, it sets the standby position of the lift plate 34 to the lowest value and lowers the lift plate 34.

[0070] Thereafter, when the control unit 90 receives a notification that the power is ON or a notification that the jam processing is completed, it determines whether or not the insertion sheet P2 is stacked on the lift plate 34. When the paper detection sensor 81 is in the OFF state, it makes the lift plate 34 wait at the lowest value.

[0071] On the other hand, when the paper detection sensor 81 is in an ON state, the lift plate 34 is raised until the lift sensor 54 is in an ON state. At this time, the control unit 90 determines the remaining amount of the sheet stacking unit 10 based on the detection result of the remaining amount detection sensor 48, and controls the standby position of the lift plate 34.

[0072] Specifically, when the remaining amount detection sensor 48 is in an OFF state, it is determined that the remaining amount of the insertion sheet P2 is greater than a predetermined amount, and when the remaining amount detection sensor 48 is in an ON state, it is determined that the remaining amount of the insertion sheet P2 is less than the predetermined amount. At this time, the standby position of the lift plate 34 when it is determined that the remaining amount of the insertion sheet P2 is less than the predetermined amount is set higher than the standby position of the lift plate 34 when it is determined that the remaining amount of the insertion sheet P2 is greater than the predetermined amount. This makes it possible to shorten the time until paper feeding starts when the next print job is input, even if the remaining amount of the insertion sheet P2 is less than the predetermined amount.

[0073] According to this embodiment, the control unit 90 controls the standby position of the lift plate before the paper feeding operation based on the detection result of the sheet presence / absence detection unit 80 including the paper detection sensor 81. As a result, when an insertion sheet (sheet) P2 is loaded on the lift plate 34, the lift plate 34 can be made to wait at a position that can shorten the time until the start of paper feeding when the next print job is input. Also, when an insertion sheet (sheet) is not loaded on the lift plate 34, the lift plate 34 can be made to wait at a position that is convenient for the user to replenish paper.

[0074] In addition, the control unit 90 controls the standby position based on the detection results of the sheet presence / absence detection unit 80 and the detection results of the remaining amount detection unit 70 including the remaining amount detection sensor 48, thereby making it possible to cause the lift plate 34 to wait at a position that can shorten the time until paper feeding begins when the next printing job is input according to the remaining amount of insertion sheets P2.

[0075] Furthermore, when the sheet presence / absence detection unit 80 detects that no insertion sheets P2 are stacked on the lift plate 34 upon receiving a notification that the power is ON or that jam processing is completed, the control unit 90 sets the standby position to the lowest value, and when the sheet presence / absence detection unit 80 detects that no insertion sheets P2 are stacked on the lift plate 34, the control unit 90 controls the standby position based on the detection result of the remaining amount detection unit 70. This makes it possible to make the lift plate 34 standby at a position that can shorten the time until paper feeding starts when the next print job is input after the power is ON or jam processing is completed.

[0076] Furthermore, when the sheet presence / absence detection unit 80 detects that the insertion sheets P2 are stacked on the lift plate 34, the control unit 90 sets the standby position higher than when the sheet presence / absence detection unit 80 detects that the insertion sheets P2 are not stacked on the lift plate 34. This makes it possible to shorten the time until paper feeding starts when the next print job is input.

[0077] In addition, when the sheet presence / absence detection unit 80 detects that no insertion sheet P2 is loaded on the lift plate 34, when a power-off notification is received, or when a jam has occurred, the control unit 90 sets the standby position to the lowest value, thereby improving convenience for the user when refilling the sheet stacking unit 10 with insertion sheets P2.

[0078] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention. [Industrial Applicability]

[0079] The present invention can be used in a sheet feeding device that inserts an insertion sheet at a predetermined timing between a plurality of output sheets output from an image forming apparatus. [Explanation of symbols]

[0080] 1. Image forming device 2 Sheet Feeder 3 Paper post-processing device 10 Sheet loading area 14 Sheet feeding section 34 Lift Board 35 Lift mechanism 36 Drive unit 37 Drive shaft 38 Actuation piece 39 Detection piece 39a Proximal end 42 Link mechanism 43 Engagement piece 44 Engagement hole 45 Engagement surface 46 Gap (play) 48 Detection Sensor 70 Remaining amount detection unit 80 Sheet presence detection unit 90 Control section 100 Image forming system P1 Output Sheet P2 Insert Sheet

Claims

1. a sheet stacking section for stacking sheets; a lift plate disposed in the sheet stacking section and supported so as to be capable of being raised and lowered; A lift mechanism for raising and lowering the lift plate; a sheet feeding section disposed above and facing the lift plate and contacting and feeding the sheet lifted by the lift plate; a sheet presence / absence detection unit provided on the lift plate and configured to detect whether the sheet is loaded on the lift plate; a remaining amount detection unit that detects a remaining amount of the stacked sheets based on a height of the lift plate; A control unit for controlling the elevation and lowering of the lift plate; Equipped with The control unit is the lift plate is disposed at a sheet feeding position when the sheet is fed, and at a standby position when the sheet is on standby, the lift plate is disposed at a standby position below the sheet feeding position; after the sheet feeding is completed, when the sheet presence / absence detection unit detects no sheet with the lift plate disposed at the sheet feeding position, the standby position is set to a lowest value; when the sheet presence / absence detection unit detects the presence of the sheet and the remaining amount detection unit detects that the remaining amount of the sheet is equal to or less than a predetermined amount, the standby position is set to a height between the sheet feed position and a lowest value; when the sheet presence / absence detection unit detects the presence of the sheet and the remaining amount detection unit detects that the remaining amount of the sheet exceeds a predetermined amount, the standby position is set to a lowest value; the sheet presence / absence detection unit includes a reflective paper detection sensor that detects light reflected from a lower surface of the sheet, The paper detection sensor is capable of detecting the sheet at a predetermined detection distance or less, 2. A sheet feeding device according to claim 1, wherein the detection distance is shorter than a distance between the sheet feeding position and a lowermost position and longer than a distance between the sheet feeding position and the standby position.

2. The control unit, upon receiving a notification that the power is ON or a notification that jam processing has been completed, sets the standby position to a lowest value when the sheet is not detected by the sheet presence / absence detection unit, sets the standby position to a height between the paper feed position and the lowest value when the sheet is detected by the sheet presence / absence detection unit and the remaining amount detection unit detects that the remaining amount of the sheet is equal to or less than a predetermined amount, and sets the standby position to the lowest value when the sheet is detected by the sheet presence / absence detection unit and the remaining amount detection unit detects that the remaining amount of the sheet exceeds a predetermined amount.

3. The sheet supplying device of claim 1 or claim 2, characterized in that the control unit sets the standby position to a lowest value when the sheet is not detected by the sheet presence / absence detection unit after the sheet is detected by the sheet presence / absence detection unit and the lift plate is lowered to the standby position.

4. 4. The sheet supplying device according to claim 1, wherein the control unit sets the standby position to the lowest value when a power-off notification or a jam occurrence notification is received.

5. an image forming device for forming an image on a sheet; a sheet post-processing device that performs a predetermined post-processing on a sheet stack output from the image forming device; a sheet feeding device according to any one of claims 1 to 4, which is connected to the sheet post-processing device and functions as an inserter for inserting a sheet into the sheet stack; An image forming system comprising:

Images