Sheet stacking device and image forming system

Abstract

To provide a sheet loading device capable of suitably detecting the location of a sheet regulating member by means of detection means.SOLUTION: The sheet loading device includes a lifting table 4, which is a sheet loading portion that loads, raises, and lowers a sheet, and a pair of side fences 25a, 25b, which is configured to be movable in a sheet width direction and serves as a pair of sheet regulating members that regulates the location of a sheet located on the lifting table 4 in a width direction. The sheet loading device also includes a distance measuring sensor 50 that is arranged between the pair of side fences 25a, 25b and serves as detection means for detecting the location of the side fences in a width direction. The distance-measuring sensor 50 is located above the feeding position where the uppermost sheet of the bundle of sheets on the elevating table 4 is located when the sheets loaded on the lifting table 4 are fed.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a sheet stacking device and an image forming system. [Background technology]

[0002] Conventionally, a sheet stacking device has been known that includes a sheet stacking section that stacks sheets and moves up and down, a pair of sheet regulating members that are configured to be movable in the sheet width direction and regulate the widthwise position of the sheets stacked on the sheet stacking section, and a detection means that is positioned between the pair of sheet regulating members and detects the widthwise position of the sheet regulating members.

[0003] Patent Document 1 describes a sheet stacking device in which a distance measuring sensor is disposed as a detection means at the center of the width of the bottom of the sheet stacking device. The distance measuring sensor is configured to irradiate measurement light toward a fence base below the sheet stacking portion of a side fence, which is a sheet regulating member provided to penetrate the sheet stacking portion, and detect the measurement light reflected from the fence base. Summary of the Invention [Problem to be solved by the invention]

[0004] However, there is a risk that dust, dirt, and other debris may accumulate on the bottom of the sheet stacking device over time. The debris that accumulates on the optical axis of the measurement light between the detection unit and the sheet regulating member may block the measurement light, hindering detection of the position of the sheet regulating member, which may result in the detection unit being unable to detect the position of the sheet regulating member or making an erroneous detection. [Means for solving the problem]

[0005] In order to solve the above-mentioned problems, the present invention provides a sheet stacking device including a sheet stacking section that stacks sheets and moves up and down, a pair of sheet regulating members that are configured to be movable in the sheet width direction and that regulate the widthwise position of the sheets stacked on the sheet stacking section, a feeding means that feeds the sheets stacked on the sheet stacking section, and a detection means that is disposed between the pair of sheet regulating members and that detects the widthwise position of the sheet regulating members, wherein when feeding the sheets stacked on the sheet stacking section, the detection means is positioned above a feeding position where the topmost sheet of a sheet stack stacked on the sheet stacking section is located. The detection means is fixed to a stay arranged at the center of the width direction of the device and above the feeding position, and a trailing edge regulating member that regulates the position of the trailing edge of the sheets stacked in the sheet feeding direction of the sheets stacked in the sheet stacking section is attached to the stay so as to be slidable in the sheet feeding direction, and the stay is attached to a frame that is rotatably attached to the device main body. It is characterized by the following. [Effects of the Invention]

[0006] According to the present invention, the position of the sheet regulating member can be detected reliably by the detecting means. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is an explanatory diagram of an entire image forming system according to an embodiment; [Figure 2] FIG. 2 is a schematic diagram illustrating the configuration of a paper feed tray of the paper feed device. [Figure 3] 10A and 10B are explanatory diagrams illustrating an example of the movement of the guide frame and the end fence when a sheet is set. [Figure 4] FIG. [Figure 5] 10A and 10B are diagrams for explaining detection of the widthwise position of a side fence by a distance measurement sensor. [Figure 6] FIG. 10 is a diagram showing an example in which a sheet of the maximum width that can be stacked is set. [Figure 7] FIG. 10 is a diagram showing an example in which a sheet of the minimum width that can be stacked is set. [Figure 8] FIG. 10 is a control flow diagram for determining positional deviation of a side fence. [Figure 9] FIG. 10 is a diagram illustrating an example of a state in which the side fences do not regulate the width direction position of the sheet stack. DETAILED DESCRIPTION OF THE INVENTION

[0008] An embodiment in which the present invention is applied to a sheet feeding device, which is a sheet stacking device equipped with a feeding unit in an image forming system, will be described. Fig. 1 is an explanatory diagram of the entire image forming system according to the embodiment. The image forming system 200 includes a sheet feeding device 210, a pretreatment liquid application device 220, an inkjet printer 230, a drying device 240, and a sheet discharge device 250.

[0009] The paper feeder 210 supplies a sheet 8 serving as a recording medium such as cut paper to a pretreatment liquid application device 220 disposed downstream of a conveyance path for the sheet 8. The pretreatment liquid application device 220 applies a pretreatment liquid to the sheet 8, which prevents bleeding and show-through of inkjet ink used for printing. The pretreatment liquid application device 220 is equipped with a reversing path, and is configured such that, in the case of double-sided printing, after applying the pretreatment liquid to the front side of the sheet 8, the sheet 8 can be reversed and the pretreatment liquid can be applied to the back side as well.

[0010] The inkjet printer 230 forms a desired image by ejecting ink droplets onto the front side of the sheet 8 to which the pretreatment liquid has been applied in the pretreatment liquid application device 220. The drying device 240 includes a dryer and dries the image on the front side of the sheet 8 formed by the inkjet printer 230. When printing on both sides of the sheet 8, the sheet 8 is inverted along a path that returns from the drying device 240 to the inkjet printer 230. Then, the inkjet printer 230 ejects ink droplets onto the front side (the back side before inversion) of the inverted sheet 8 to form a desired image, and the drying device 240 dries the image on the front side (the back side before inversion) of the sheet 8. The sheet 8 is then discharged to the paper discharge device 250.

[0011] Figure 2 is a schematic diagram of the sheet feed tray 100 of the sheet feeder 210. Figure 2(a) is a front view, and sheets are fed from right to left in the figure. Figure 2(b) is a right side view. The left-right direction in Figure 2(b) is the front-rear direction of the device and the width direction of the sheets. The sheet feed tray 100 is box-shaped and includes a bottom 6, a left side panel 10 located downstream in the feeding direction, a front side panel 30 located at the front of the device, a rear side panel 31 located at the rear of the device, and the left side panel 10. The sheet feed tray 100 is box-shaped and open at the top and right sides. The sheet feed tray includes a lift-up table 4 that serves as a sheet stacking unit and is movable up and down by a motor 22. Position sensors 20 and 21 are also provided at positions above and below the lift-up range of the lift-up table 4. When the lift-up table 4 rises, the position sensor 20 detects the top surface of the lift-up table 4, causing the lift-up table 4 to stop at a predetermined position. Similarly, when the lift-up table 4 descends, the position sensor 21 detects the bottom surface of the lift-up table 4, causing the lift-up table 4 to stop at a predetermined position.

[0012] On both sides of the lift table 4 in the sheet width direction (front-to-back direction of the device), side fences 25a, 25b are provided as sheet regulating members, and the position of the pair of side fences 25a, 25b is moved to match the set sheet 8. The pair of side fences 25a, 25b are linked by a connecting portion 26 and are structured to move in different directions in the sheet width direction. Each of the pair of side fences 25a, 25b regulates the position of the edge of the sheet 8 in the width direction.

[0013] The sheet feed tray 100 also has a fixing mechanism 40 that serves as fixing means for fixing the side fences so that they cannot move in the width direction. The fixing mechanism 40 includes a slide plate 41 attached to the side fence 25b on the right side (rear side of the device) in FIG. 2(b) and a fixing plate 42 fixed to the rear panel 31. The slide plate 41 is fixed to the fixing plate 42, so that the side fences 25a, 25b are fixed so that they cannot move in the width direction.

[0014] An end fence 5, which is a rear end regulating member that regulates the position of the rear end of the sheet and is positionable, is disposed at a position corresponding to the rear end of the sheet 8. The end fence 5 regulates the position of the rear end of the sheet 8 when the leading edge of the sheet is in contact with a left side plate 10 on the downstream side in the feeding direction. The end fence 5 is held by a guide rail 16, which is a stay disposed above the paper feed tray, so as to be movable in the longitudinal direction (feeding direction).

[0015] The guide rails 16 are attached to a frame-shaped guide frame 15 that fits along the edge of the box-shaped paper feed tray 100. Specifically, the guide rails 16 are attached to the widthwise center of an upstream support section that extends in the sheet width direction at the upstream end of the guide frame 15 in the feeding direction. The guide frame 15 is fixed to the rear side plate 31 via a plurality of rotatable hinges 17. The end fence 5, which moves in the feeding direction guided by the guide rails 16, is designed to be fixed at any position in the longitudinal direction of the guide rails 16. The end fence 5 can be fixed at any position to accommodate a variety of paper sizes. In addition, a rotatable hinge 18 is provided at a portion of the end fence 5.

[0016] The guide rail 16 is also provided with a distance measurement sensor 50 as a detection means for detecting the widthwise position of the side fence. In this embodiment, an infrared distance measurement sensor that emits infrared light is used as the distance measurement sensor 50. The emitted light may be visible light or ultraviolet light. The distance measurement sensor 50 may also be one that uses radio waves such as millimeter waves or one that uses ultrasonic waves. Based on the position of the side fence detected by the distance measurement sensor 50, the sheet width of the sheet set in the paper feed tray 100 is detected.

[0017] The lift table 4 rises, and when the position sensor 20 detects that the top sheet of the sheet stack on the lift table 4 has reached the feeding position, the lift table 4 stops rising. Multiple pickup belts 3 are arranged in a position facing the downstream part of the lift table 4 in the feeding direction. The pickup belts 3 have multiple suction holes, and a suction fan causes the top sheet at the feeding position to stick to the pickup belts 3. Therefore, when sheets are stacked on the lift table 4, the pickup belts 3 feed the sheets one by one. The pickup belts 3, the suction fan, and the drive device for the pickup belts 3 make up the feeding means.

[0018] FIG. 3 is an explanatory diagram of an example of the movement of the guide frame 15 and end fence 5 when setting a sheet. The lift-up table 4 is lowered by the motor 22 and stopped when the position is detected by the position sensor 21. The paper feed tray 100 is pulled out of the paper feeder 210, and the guide frame 15 is lifted around the rotating hinges 17. At this time, the guide rails 16 fixed to the guide frame 15 are also lifted. The end fence 5 connected to the guide rails 16 is moved vertically by the rotating hinges 18 and retracted, so that it does not get in the way when setting the sheet 8 on the lift-up table 4. Furthermore, the rotating hinges 17 are designed so that torque is applied only in the direction that causes the guide frame 15 to fall, so the guide frame 15 will not fall even if you let go of it when setting a sheet on the lift-up table 4.

[0019] The angle of the guide frame 15 changes as the side fence 25 is moved to match the width of the set sheet 8 and the guide frame 15 is lowered around the rotating hinge 17. The end fence 5 is designed so that its own weight is always applied vertically around the rotating hinge 18. Therefore, when the guide frame 15 is pressed down, the end fence 5 returns to its designated position. Then, the end fence 5 and side fence 25 are moved to their designated positions to match the length and width of the set sheet.

[0020] Figure 4 is a schematic diagram of the fixing mechanism 40, where Figure 4(a) shows the case where a sheet of the maximum width size that can be loaded into the paper feed tray 100 is set, and Figure 4(b) shows the case where a sheet of the minimum width size that can be loaded into the paper feed tray 100 is set.

[0021] The fixing mechanism 40 includes a slide plate 41 as a second member attached to the rear side fence 25b of the device, and a fixing plate 42 as a first member fixed to the rear side plate 31. Slide plate 41 is made of sheet metal and is fixed to the upper part of side fence 25b with screws 45. Two elongated holes 43 extending in the width direction are provided at a predetermined interval in the sheet feeding direction. As shown in Figures 4(a) and 4(b), elongated holes 43 are longer than the widthwise movement range of the side fence from the widthwise restriction position for sheets of the maximum width size to the widthwise restriction position for sheets of the minimum width size.

[0022] The fixed plate 42 is made of sheet metal and is fixed to the rear plate 31 with screws 46. The fixed plate 42 and the slide plate 41 are positioned such that the rear side of the slide plate 41, which is the right side in the figure, rests on the fixed plate 42. Near the front side of the fixed plate 42, which is the left side in the figure, two screw holes are provided at a predetermined interval in the sheet feeding direction, into which screws 48 serving as fastening members are screwed. Each screw 48 passes through an elongated hole 43 in the slide plate 41 and is screwed into a screw hole in the fixed plate 42.

[0023] Loosening the screws 48 allows the side fences to move in the width direction. When the side fences are slid in the width direction, the slide plate 41 moves in the width direction relative to the fixed plate 42. Then, after the side fences are brought into contact with the widthwise ends of the stacked sheets and their position in the width direction is restricted, the screws 48 are tightened to fix the slide plate 41 to the fixed plate 42, thereby fixing the side fences so that they cannot move in the width direction. In this embodiment, the pair of side fences are configured to move in conjunction with each other via the connecting portion 26, so that fixing one of the pair of side fences also fixes the other side fence so that it cannot move.

[0024] The end of the slide plate 41 on the side fence side is bent downward by 90 degrees, and this bent surface serves as a detectable portion 47 for the distance measuring sensor 50 to detect the position of the side fence. The slide plate 41 is made of sheet metal and is constructed from a material that reflects infrared light well, so providing the detectable portion on the slide plate allows the distance measuring sensor 50 to detect the position of the side fence well.

[0025] FIG. 5 is a diagram for explaining how the distance measurement sensor 50 detects the position of the side fence in the width direction. The pair of side fences 25a, 25b move the same distance in different widthwise directions via the connecting portion 26. Therefore, the side fence 25a on the left side in the drawing (front side of the device) and the side fence 25b on the right side in the drawing (rear side of the device) always have the same distance L from the center O1 of the paper feed tray 100 in the widthwise direction.

[0026] The distance measurement sensor 50 is attached to the right side of the guide rail 16 (as a stay) in the figure, and is positioned b [mm] to the right of the widthwise center O1 in the figure. Therefore, if the distance to the side fence 25b measured by the distance measurement sensor 50 is a [mm], then L = a + b. The distance b [mm] from the widthwise center O1 to the distance measurement sensor 50 is always constant, and the distance b [mm] from the widthwise center O1 to the distance measurement sensor 50 is measured in advance and stored in the device's nonvolatile memory. The side fence position L relative to the widthwise center O1 is calculated using the distance a [mm] measured by the distance measurement sensor 50 and the distance b [mm] from the widthwise center O1 to the distance measurement sensor 50 stored in the nonvolatile memory. The sheet width (2L) of the sheet set in the paper feed tray 100 is calculated from the side fence position L thus calculated.

[0027] In this embodiment, the distance measuring sensor 50 is fixed to the guide rail 16 located at the center in the width direction above the paper feed tray 100. This makes it possible to shorten the distance to the side fence compared to when the distance measuring sensor 50 is provided at one end of the paper feed tray 100 in the width direction, and it is possible to accurately detect the distance to the side fence even when using an inexpensive distance measuring sensor with a short measurement range.

[0028] Furthermore, in this embodiment, the pair of side fences 25a, 25b are configured to move by the same amount in different directions in the width direction via the connecting portion 26. As a result, as described with reference to FIG. 5, the sheet width 2L=2(a+b) set in the sheet feed tray 100 can be detected by measuring the distance to one of the side fences with the distance measuring sensor 50. This allows the measurement range of the distance measuring sensor to be shorter than in the case of detecting the sheet width by measuring the distance between the side fences with the distance measuring sensor, as described in Patent Document 1. Therefore, the sheet width can be detected using an inexpensive sensor with a short measurement range.

[0029] FIG. 6 is a diagram showing an example in which a sheet of the maximum width that can be stacked is set. Figure 6(a) shows the state where the maximum number of sheets that can be loaded in the paper feed tray 100 is set on the lift-up table 4, and Figure 6(b) shows the state when there are only a few sheets left loaded on the lift-up table 4. When loading a stack of sheets of the maximum width into the paper feed tray 100, the lift-up table 4 is lowered to a position where the position sensor 21 detects the lift-up table 4. The screws 48 of the fixing mechanism 40 shown in FIG. 4 are loosened, and the side fences 25a and 25b are moved to the widthwise ends. After the stack of sheets is loaded into the paper feed tray 100, the side fences are slid widthwise until they abut against the widthwise ends of the stack of sheets loaded on the lift-up table 4. Once the side fences 25a and 25b abut against the widthwise ends of the sheets and the widthwise position of the sheets is regulated, the screws 48 are tightened to fix the side fences. At this time, the slide plate 41 is fastened to the fixed plate 42 in the state shown in FIG. 4( a). The end fence 5 is moved in the feeding direction until it abuts against the rear end of the sheets, thereby regulating the position of the rear end of the sheets.

[0030] Furthermore, the distance to the detection target portion 47 of the slide plate 41 is measured by the distance measuring sensor 50, and based on the measured distance, it is detected that the width of the sheets stacked on the lift table 4 is the maximum width.

[0031] The lifting table 4 is controlled to rise based on the detection result of the position sensor 20. Specifically, when the position sensor 20 does not detect the top surface of the sheet stack stacked on the lifting table 4, the lifting table 4 starts to rise, and when the position sensor 20 detects the top surface of the sheet stack stacked on the lifting table 4, the lifting table 4 stops to rise.

[0032] The feeding position at which the position sensor 20 detects the top surface of the sheet stack is the height position at which the top sheet of the sheet stack is lifted by the suction force of the suction fan and sticks to the pickup belt 3 shown in Fig. 2. Then, the top sheet that has stuck to the pickup belt 3 by the suction force of the suction fan is conveyed to the guide plate 7 by the pickup belt 3.

[0033] FIG. 7 is a diagram showing an example in which a sheet of the minimum width that can be stacked is set. Figure 7(a) shows the state where the maximum number of sheets that can be loaded into the paper feed tray 100 is set on the lift-up table 4, and Figure 7(b) shows the state when there are only a few sheets left loaded on the lift-up table 4. When setting a stack of sheets of the minimum width in the sheet feed tray 100, the lift-up table 4 is also lowered to a position where the position sensor 21 detects the lift-up table 4, and the stack of sheets of the minimum width is set on the lift-up table. After the stack of sheets of the minimum width has been set, the screws 48 are loosened to move the sliding side fences in the width direction so that the side fences abut against the widthwise ends of the stack of sheets stacked on the lift-up table 4, thereby restricting the widthwise position of the sheets. The screws 48 are then tightened to fix the side fences. At this time, the slide plate 41 is fastened to the fixed plate 42 in the state shown in FIG. 4(b). The end fence 5 is also moved in the feeding direction so that the end fence 5 abuts against the rear end of the sheets, thereby restricting the position of the rear end of the sheets.

[0034] Furthermore, the distance to the detection target portion 47 of the slide plate 41 is measured by the distance measuring sensor 50, and based on the measured distance, it is detected that the width of the sheets stacked on the lift table 4 is the minimum width.

[0035] The lifting table 4 is controlled to rise based on the detection result of the position sensor 20. Specifically, when the position sensor 20 does not detect the top surface of the sheet stack stacked on the lifting table 4, the lifting table 4 starts to rise, and when the position sensor 20 detects the top surface of the sheet stack stacked on the lifting table 4, the lifting table 4 stops to rise.

[0036] If the distance measuring sensor 50 is placed at the bottom 6 of the paper feed tray 100, it must be placed in a position that avoids the connecting portion 26 located at the bottom 6, which may restrict the placement position of the distance measuring sensor 50. Also, over time, dust, dirt, and other debris from the sheets set on the lift table accumulates on the bottom 6 of the paper feed tray. If such debris accumulates on the optical axis of the distance measuring sensor 50, the debris may block the light from the distance measuring sensor 50, making it impossible to measure the distance to the side fence.

[0037] In order to avoid distance measurement failure due to such accumulated dust, it is also conceivable to provide a mounting base on which the distance measurement sensor 50 is mounted on the bottom 6, and to place the distance measurement sensor 50 at a position one step higher than the bottom 6. However, in such a configuration, it becomes necessary to move the lowest position of the lift-up table 4 upward so that the lift-up table 4 does not hit the distance measurement sensor 50. As a result, there is a risk that the maximum number of sheets that can be loaded on the lift-up table 4 will decrease.

[0038] On the other hand, in this embodiment, the distance measuring sensor 50 is fixed to the guide rail 16 arranged above the sheet feed tray 100. This allows the distance measuring sensor 50 to be positioned above the feeding position, which is the highest position in the height direction that the sheets stacked on the lift-up table 4 can be at. As a result, the distance measuring sensor 50 can always be positioned above the sheets stacked on the lift-up table 4. Therefore, as shown in FIGS. 6 and 7 , the distance measuring sensor 50 does not interfere with the sheets stacked on the lift-up table 4 under any circumstances. Furthermore, the distance to the side fence 25b can be measured above the sheets stacked on the lift-up table 4, and the light of the distance measuring sensor 50 is not blocked by the sheets stacked on the lift-up table 4, allowing the distance to the side fence 25b to be measured accurately.

[0039] Furthermore, a pickup belt 3 is disposed downstream in the feeding direction above the feeding position, and a predetermined space is provided upstream of the pickup belt 3 above the feeding position. Therefore, the distance measuring sensor 50 can be disposed in this predetermined space, and the size of the paper feed tray 100 does not increase in the vertical direction.

[0040] Furthermore, unlike the bottom 6, the top surface of the sheet stack stacked on the lift-up table 4 is free from paper dust and other debris attached to the sheet stack. Therefore, debris is less likely to accumulate on the top surface of the sheet stack than on the bottom 6. Even if debris does adhere to the top surface of the sheet stack, when the top sheet of the sheet stack is fed, the debris attached to the top surface of the sheet stack is transported along with the top sheet being fed. Therefore, unlike the bottom 6, debris rarely accumulates on the top surface of the sheet stack. Therefore, the light from the distance measuring sensor 50 is not blocked by accumulated debris, and the distance to the side fence can be measured properly.

[0041] FIG. 8 is a control flow diagram for determining whether the side fence is out of position. When the paper feed tray 100 is pushed into the device body and attached to the device body (YES in S1), the distance sensor 50 measures the distance a to the side fence 25b and calculates the sheet width 2L=2(a+b) (S2). Next, the calculated sheet width is compared with the sheet width designated by the operator through an operation panel provided in the image forming system 200 shown in FIG. 1 or a PC connected to the image forming system 200.

[0042] 9, after setting the sheet stack, the operator may forget to abut the side fences 25a, 25b against the widthwise ends of the sheets when attaching the sheet feed tray 100 to the apparatus body. In this case, the error between the sheet width specified by the operator and the sheet width calculated based on the distance to the side fence measured by the distance measuring sensor 50 is equal to or greater than the threshold value (No in S3).

[0043] If the error is equal to or greater than the threshold and the side fences are not regulating the widthwise position of the sheets stacked on the lift-up table 4, and feeding begins, the sheets may shift widthwise. As a result, there is a risk of print position misalignment occurring, where the position of the image printed on the sheet deviates from the specified position. There is also a risk of transport failure, causing the printing operation to stop.

[0044] Therefore, when the error is greater than or equal to the threshold value (No in S3), size mismatch information indicating that the sheet width calculated using the distance measurement sensor 50 is different from the specified sheet width is displayed on a display unit such as the operation panel or PC monitor to notify the operator (S5).

[0045] When the size mismatch information is notified to the operator, the operator realizes that the side fences are not restricting the sheets in the width direction, and pulls out the paper feed tray 100 again. Then, the side fences are moved in the width direction until they abut against the widthwise edges of the sheets stacked on the lift-up table 4, and the side fences restrict the widthwise position. This makes it possible to prevent transport problems and misalignment of the printing position.

[0046] It is also preferable to notify the user of the size mismatch and prohibit printing so that feeding does not occur when the side fences are not restricting the sheet widthwise. This makes it possible to more reliably prevent transport problems and misalignment of the printing position.

[0047] On the other hand, when the error between the sheet width specified by the operator and the sheet width calculated based on the distance to the side fence measured by the distance measuring sensor 50 is less than the threshold value (Yes in S3), the side fence regulates the widthwise position of the sheets loaded on the lift table. Therefore, in this case, the system is set to feeding standby (S4) and is in a feeding enabled state.

[0048] The above description is merely an example, and each of the following aspects provides unique effects. (Aspect 1) In a sheet loading device such as a paper feeder 210 that includes a sheet loading section such as a lift table 4 that loads sheets and moves up and down, sheet regulating members such as a pair of side fences 25a, 25b that are configured to be movable in the sheet width direction and regulate the widthwise position of the sheets loaded in the sheet loading section, a feeding means (in this embodiment, composed of a pickup belt 3, a suction fan, and a drive device for the pickup belt 3) that feeds the sheets loaded in the sheet loading section, and a detection means such as a distance sensor 50 that is arranged between the pair of sheet regulating members and detects the widthwise position of the sheet regulating members, the detection means is located above the feeding position at which the topmost sheet of the sheet stack loaded in the sheet loading section is located when feeding the sheets loaded in the sheet loading section. According to this, by positioning the detection device above the feeding position, the detection device can detect the position of the sheet regulating member more effectively than when the detection device is located on the bottom surface. That is, unlike the bottom surface of the sheet stack, dust and other debris attached to the sheet stack do not fall onto the top surface of the sheet stack. Therefore, dust is less likely to accumulate on the top surface of the sheet stack than on the bottom surface. Even if dust does adhere to the top surface of the sheet stack, when the top sheet of the sheet stack is fed, the dust attached to the top surface of the sheet stack is transported along with the top sheet being fed. Therefore, unlike the bottom surface of the sheet stack, dust is rarely accumulated on the top surface of the sheet stack. Therefore, dust is not obstructed by dust from detecting the sheet regulating member. As a result, the detection device can detect the position of the sheet regulating member more effectively than when the detection device is located on the bottom surface.

[0049] (Aspect 2) In aspect 1, a detection means such as a distance measuring sensor 50 is fixed to a stay such as a guide rail 16 located in the widthwise center of the device and above the sheets loaded on a sheet loading section such as a lift table 4. This allows the distance measuring sensor 50 or other detection means to be disposed between the pair of sheet regulating members and above the sheets stacked on the sheet stacking section.

[0050] (Aspect 3) In aspect 2, a rear end regulating member such as an end fence 5 that regulates the position of the rear end in the sheet feeding direction of sheets loaded on a sheet stacking section such as a lifting table 4 is attached to a stay such as a guide rail 16 so as to be slidable in the sheet feeding direction, and the stay is attached to a frame such as a guide frame 15 that is rotatably attached to the device main body. According to this, as described in the embodiment, by rotating a frame such as the guide frame 15, the trailing edge regulating member such as the end fence 5 can be retracted from the center position in the width direction together with a stay such as the guide rail 16. As a result, when setting a sheet on a sheet stacking section such as the lift-up table 4, the trailing edge regulating member does not get in the way, and the ease of setting the sheet can be improved.

[0051] (Aspect 4) In any of aspects 1 to 3, one of the pair of sheet regulating members such as side fences 25a, 25b is configured to move in the width direction in conjunction with the movement of the other sheet regulating member by the same amount in the width direction in the opposite direction to the one sheet regulating member, and a detection means such as a distance measuring sensor 50 detects the position of one of the pair of sheet regulating members. According to this, as described in the embodiment, when one sheet regulating member moves in the width direction, the other sheet regulating member moves in the opposite direction to the one sheet regulating member by the same amount in the width direction, so that by detecting the position of one sheet regulating member, the position of the other sheet regulating member can also be determined. As a result, the distance from one sheet regulating member to the other sheet regulating member can be calculated from the position of one sheet regulating member, and the sheet width of the sheets stacked on a sheet stacking section such as the lift-up table 4 can be calculated.

[0052] (Aspect 5) In any of the first to fourth aspects, the detection means is a distance measurement sensor such as the distance measurement sensor 50. This makes it possible to grasp the widthwise position of the sheet restricting member, such as a side fence, based on the distance measured by a distance measuring sensor such as the distance measuring sensor 50 from the detection means to the sheet restricting member.

[0053] (Aspect 6) In any of aspects 1 to 5, a fixing means such as a fixing mechanism 40 is provided to fix a sheet regulating member such as a side fence so that it cannot move in the width direction, and the fixing means is provided with a detectable portion 47 that can be detected by a detection means such as a distance measuring sensor 50. According to this, by providing a fixing means, it is possible to fix a sheet regulating member such as a side fence at a position that regulates the width direction of sheets loaded on a sheet stacking section such as the lift-up table 4. By detecting the detectable portion 47 of the fixing means, it is possible to detect the position of the side fence.

[0054] (Aspect 7) In aspect 6, a fixing means such as the fixing mechanism 40 has a first member such as a fixing plate 42 fixed to the side of the device, a second member such as a slide plate 41 made of sheet metal fixed to the upper surface of a sheet regulating member such as a side fence and attached so as to be slidable in the width direction relative to the first member, and a fastening member such as a screw 48 that fastens the second member to the first member, and has a detectable portion 47 on the second member. According to this, by fastening a second member such as the slide plate 41 to a first member such as the fixed plate 42 with a fastening member such as a screw 48, it is possible to fix a sheet restricting member such as a side fence so that it cannot move in the width direction. In addition, by loosening the screw, it is possible to move the first member relative to the second member, and to move the sheet restricting member in the width direction. Furthermore, by providing a detected portion on the second member attached to the sheet regulating member, a detecting means such as the distance measuring sensor 50 can detect the detected portion, thereby detecting the position of the sheet regulating member.

[0055] (Aspect 8) In any of aspects 1 to 7, if the error between the sheet width calculated based on the position of a sheet regulating member such as a side fence detected by a detection means such as a distance measurement sensor 50 and the sheet width input by the operator is greater than or equal to a threshold value, the operator is notified. As described in the embodiment, this prevents sheets stacked on a sheet stacking unit such as a lift table from being fed without being restricted in the width direction by a sheet restricting member such as a side fence, thereby preventing sheets from being conveyed with deviation in the width direction, and suppressing misalignment of the printing position and conveyance problems.

[0056] (Aspect 9) The image forming system includes the sheet stacking device according to any one of the first to eighth aspects, and an image forming apparatus that forms an image on a sheet fed by a feeding means. According to this, the sheets stacked on the sheet stacking section can be sent to the image forming device, and an image can be formed on the sheets. [Explanation of symbols]

[0057] 3: Pickup belt 4: Lift table 5: End fence 6: Bottom 7: Guide plate 8: Sheet 10: Side plate downstream in the feeding direction 15: Guide frame 16: Guide rail 17: Rotating hinge 18: Rotating hinge 20: Position sensor 21: Position sensor 22: Motor 25a: Side fence 25b: Side fence 26:Connection part 30: Front side plate 31: Rear side plate 40:Fixing mechanism 41: Slide plate 42: Fixed plate 43: Slot 45: Screw 46: Screw 47: Detected part 48: Screw 50: Distance sensor 100: Paper tray 200: Image forming system 210: Paper feeder 220: Pretreatment liquid application device 230: Inkjet printer 240:Drying equipment 250: Paper ejection device L: Distance from the center of the width to the side fence O1: Width center a: Measurement distance of the distance sensor b: Distance from the center of the width to the distance sensor [Prior art documents] [Patent documents]

[0058] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-058889

Claims

1. a sheet stacking section that stacks sheets and moves up and down; a pair of sheet regulating members configured to be movable in a sheet width direction and regulating the position of the sheets stacked in the sheet stacking section in the width direction; a feeding means for feeding the sheets stacked in the sheet stacking section; a detection means disposed between the pair of sheet regulating members and configured to detect the position of the sheet regulating members in the width direction, the detecting means is located above a feeding position where the top sheet of the sheet stack placed on the sheet stacking section is located when the sheets placed on the sheet stacking section are fed, the detection means is fixed to a stay disposed at the center of the device in the width direction and above the feeding position, a rear end regulating member that regulates the position of the rear end of the sheets stacked in the sheet feeding direction of the sheets stacked in the sheet stacking section is attached to the stay so as to be slidable in the sheet feeding direction; The sheet stacking device is characterized in that the stay is attached to a frame that is rotatably attached to the device body.

2. 2. The sheet stacking device according to claim 1, The pair of sheet regulating members are configured so that, when one of the sheet regulating members moves in the width direction, the other sheet regulating member moves in the opposite direction to the one sheet regulating member by the same amount in the width direction, The sheet stacking device according to claim 1, wherein the detecting means detects the position of one of a pair of sheet regulating members.

3. 3. The sheet stacking device according to claim 1, 4. A sheet stacking device according to claim 1, wherein the detecting means is a distance measuring sensor.

4. 4. The sheet stacking device according to claim 1, a fixing means for fixing the sheet regulating member so that it cannot move in the width direction; A sheet stacking device characterized in that the fixing means is provided with a detected portion that is detected by the detecting means.

5. 5. The sheet stacking device according to claim 4, the fixing means includes a first member fixed to a side surface of the device, a second member fixed to an upper surface of the sheet regulating member and attached so as to be slidable in the width direction relative to the first member, and a fastening member that fastens the second member to the first member; The sheet stacking device has the detected portion on the second member.

6. 6. The sheet stacking device according to claim 1, A sheet stacking device characterized in that, when an error between a sheet width calculated based on the position of the sheet regulating member detected by the detection means and a sheet width input by an operator is equal to or greater than a threshold value, an operator is notified.

7. 7. An image forming system comprising: the sheet stacking device according to claim 1; and an image forming apparatus that forms an image on the sheet fed by the feeding means.

Images