Paper feed device and image forming device

Abstract

To provide a paper feed device capable of feeding a large number of paper bundles of any size at once.SOLUTION: A paper feed device 1 feeds a paper sheet 2 from the topmost sheet of a paper bundle 3 laminated in order. The paper feed device 1 includes: a bottom plate part 201 that supports a lower surface of the paper bundle 3; and an elastic member SP that is directly or indirectly disposed on the bottom plate part 201 and energizes the bottom plate part 201 upward. The elastic member SP is provided with supporting force varying means 60 and 130 capable of adjusting a moment force applied on a first position of the elastic member SP.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a paper feeder and an image forming apparatus. [Background technology]

[0002] Envelopes have flaps and folds, and are of uneven thickness. Therefore, when many envelopes are stacked, the flap side sinks downward, and the top surface of the stack of paper becomes slanted. A paper feeder described in Patent Document 1 is known as a device that makes it possible to feed paper such as envelopes of uneven thickness. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 5-4731 Summary of the Invention [Problem to be solved by the invention]

[0004] The paper feeder described in Patent Document 1 is capable of feeding envelopes and other paper of a standard size. However, when feeding envelopes and other paper of an arbitrary size other than the standard size, the weight of the envelope on the paper feed tray varies depending on the uneven thickness of the envelope, causing the bottom plate of the paper feed tray to tilt. Therefore, the paper feeder described in Patent Document 1 has a problem in that it cannot feed paper of an arbitrary size because it cannot level the topmost paper of the paper stack to be fed.

[0005] In addition, businesses that mainly print envelopes want to print a large number of envelopes continuously to produce output with high productivity. However, with a general paper feeder unit (PFU), the envelope feed tray can only feed up to 100 envelopes at a time, and the paper feed operation must be repeated every time 100 envelopes are printed, resulting in low productivity.

[0006] SUMMARY OF THE PRESENT INVETION The present invention has been made in consideration of the above problems, and an object of the present invention is to provide a paper feeder and an image forming apparatus capable of feeding a stack of multiple sheets of any size at once. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention has the following configuration. (1) A paper feeding device that feeds paper in sequence, starting from the topmost sheet of a stack of paper, comprising: a bottom plate portion that supports the underside of the stack of paper; and an elastic member that is arranged directly or indirectly on the bottom plate portion and biases the bottom plate portion upward, the elastic member comprising a support force variable means that can adjust the moment force applied to a first position of the elastic member.

[0008] (2) The paper feeder according to claim 1, wherein the supporting force varying means is a spring disposed below a paper stacking section on which the paper is stacked.

[0009] (3) The paper feeding device according to claim 2, wherein the spring is installed at an end of a lever-shaped support portion, and the angle of the spring is changed by the supporting force varying means, thereby making it possible to adjust the moment.

[0010] (4) The sheet feeding device according to claim 2, wherein the spring force is adjustable by changing the tension angle of the spring.

[0011] (5) The paper feeding device according to claim 2, wherein the supporting force varying means is supported by a block disposed below the paper stacking section.

[0012] (6) The paper feeder according to claim 5, wherein a plurality of blocks having different heights are prepared, and the blocks having different heights can be selectively set in accordance with the state of the paper stack.

[0013] (7) The paper feeding device according to claim 5, wherein the spring force of the elastic member and the height of the block are changeable in accordance with the state of the paper.

[0014] (8) The paper feeding device according to claim 1, wherein the paper is an envelope.

[0015] (9) The paper feeder according to claim 5, wherein the spring and the block are configured as a single unit, and the unit is fixed to a base by magnetic force.

[0016] (10) The paper feeding device according to claim 8, wherein the supporting force varying means adjusts the moment force applied to the first position of the elastic member so that the uppermost envelope is positioned horizontally.

[0017] (11) An image forming apparatus comprising: the paper feeder according to any one of claims 1 to 10; and an image forming section that forms an image on the paper fed from the paper feeder. Effect of the Invention

[0018] According to the present invention, it is possible to provide a paper feeder and an image forming apparatus capable of feeding a stack of multiple sheets of any size at once. [Brief description of the drawings]

[0019] [Figure 1] 1 is a perspective view showing a schematic view of a paper feeder according to an embodiment of the present invention; [Diagram 2] 2 is a side view (a cross-sectional view taken along line II-II in FIG. 1) that illustrates a schematic diagram of the paper feeder according to the embodiment of the present invention; [Diagram 3] 10A and 10B are plan views each showing a schematic example of a state in which a rectangular Japanese envelope is supported by a paper support table set used in a paper feeder according to an embodiment of the present invention. [Figure 4] FIG. 2 is a perspective view showing a schematic diagram of a paper support table set used in the paper feeder according to the embodiment of the present invention. [Diagram 5] FIG. 2 is a side view showing a schematic diagram of a paper support table set used in the paper feeder according to the embodiment of the present invention. [Figure 6] 13 is a perspective view of a main part showing an installation state of a supporting force varying means provided on a second supporting portion of the paper support table. FIG. [Figure 7] FIG. 4 is an explanatory diagram showing the principle of a supporting force varying means. [Figure 8] 13 is a plan view showing an installation state of a supporting force varying means provided on the auxiliary paper support base. FIG. [Figure 9] 13 is a side view showing an installation state of a supporting force varying means provided on the auxiliary paper support base. FIG. [Figure 10A] FIG. 2 is a rear view diagram illustrating a square Japanese envelope as an example of paper. [Figure 10B] FIG. 2 is a rear view showing a typical Western-style envelope with a kamasu outer lining as an example of paper. [Figure 10C] FIG. 13 is a rear view diagram illustrating a Japanese envelope with a right side outer pasted as an example of paper. [Figure 11A] 11 is an explanatory diagram showing a state of envelopes stacked in a paper feed tray of a comparative example. FIG. [Figure 11B] This is an explanatory diagram showing the state when a long No. 3 Japanese envelope and a square No. 2 Japanese envelope are stacked in a customization kit provided in the paper feed tray of the present invention. [Figure 11C] This is an explanatory diagram showing the state when the height of a long No. 3 Japanese envelope and a square No. 2 Japanese envelope stacked in a customization kit provided in the paper feed tray of the present invention is lowered. [Figure 12A] 11 is a plan view showing an example of how a rectangular Japanese envelope is supported by the paper support table set; FIG. [Figure 12B] 11 is a side view showing an example of how a rectangular Japanese envelope is supported by the paper support table set; FIG. [Figure 12C] 13 is a side view showing a schematic diagram of a state in which the height of rectangular Japanese envelopes stacked on the paper support table set has been lowered. FIG. [Figure 13A] 1 is a plan view showing a schematic example of how a paper support base supports a Western-style envelope with a flap. [Figure 13B] 13 is a side view showing a schematic example of the state in which a Western-style envelope with a flap is supported by the paper support base. FIG. [Figure 14A] 11 is a plan view showing a schematic example of how a corner-pasted long Japanese envelope is supported by the paper support base. FIG. [Figure 14B] 11 is a side view showing a schematic example of a state in which a long Japanese envelope with a corner pasted is supported by the paper support base. FIG. [Figure 15] 1 is a side view illustrating a schematic diagram of an image forming apparatus according to an embodiment of the present invention; [Figure 16] FIG. 13 is a side view showing a modified example of a paper feeder according to an embodiment of the present invention, illustrating an installation state of a supporting force variable means provided on an auxiliary paper support stand. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Next, an embodiment of the present invention will be described in detail with reference to the drawings as appropriate. In the reference drawings, "front and back" refers to the feeding direction of the paper 2 (the downstream side is the front and the upstream side is the rear), and "left and right" refers to the width direction of the paper 2 (the direction perpendicular to the feeding direction and the up and down direction). Fig. 1 is a perspective view showing a sheet feeding device 1 according to an embodiment of the present invention. Fig. 2 is a side view showing a sheet feeding device 1 according to an embodiment of the present invention (a cross-sectional view taken along line II-II in Fig. 1).

[0021] <Paper Feeding Device> As shown in Fig. 1 or 2, a paper feeder 1 according to an embodiment of the present invention is an air separation type device that blows air onto the topmost (upper) paper 2 of a stack of paper 3 stacked in the vertical direction, thereby floating and separating the paper 2, and conveys the separated paper 2 to supply it to the outside. The paper feeder 1 basically includes a bottom plate 201 shown in Fig. 2, an elastic member SP shown in Fig. 4, a front wall 202, a lift plate 203, a position regulating section 204, a pair of left and right floating sections 205, 205, a front floating section 206, and supporting force varying means 60, 130 shown in Fig. 3. The paper feeder 1 also includes sensors 221, 222, and a control section 223.

[0022] ≪Bottom plate part≫ The bottom plate portion 201 is a member that supports the bottom surface of the stack of sheets 3 accommodated in the sheet feed tray. The bottom plate portion 201 extends horizontally (in the front-rear and left-right directions) and constitutes the floor surface of the sheet feeder 1.

[0023] ≪Front wall section≫ The front wall portion 202 extends upward from the front end portion of the bottom plate portion 201. The front wall portion 202 is a position regulating portion that regulates the position of the front end portion of the paper 2 provided on the lifting plate portion 203 (i.e., the forward movement of the paper 2).

[0024] <Lifting plate section> The lifting plate 203 is a plate-shaped metal member provided on the upper side of the bottom plate 201, extending horizontally, and configured to be movable up and down. The lifting plate 203 is formed with holes, notches, etc. for allowing the position regulating portion 204 and the floating portion 205 to move.

[0025] ≪Position regulation section≫ Position regulating unit 204 is provided above bottom plate unit 201 so as to protrude upward from lift-up plate unit 203, and regulates the position of the rear end of paper 2 provided on lift-up plate unit 203 (i.e., rearward movement of paper 2). Position regulating unit 204 is configured to be manually movable in the front-rear direction relative to bottom plate unit 201, and can accommodate paper 2 of any size.

[0026] <Left and right floating parts> The floating part 205 is provided above the bottom plate part 201 so as to protrude upward from the lifting plate part 203, and is a fan that blows air from the side onto the uppermost sheet of paper 2 among the sheets of paper 2 provided on the lifting plate part 203, thereby lifting the sheet of paper 2. The floating part 205 is configured to be manually movable in the left-right direction relative to the bottom plate part 201, and can accommodate sheets of paper 2 of any size. In the pair of floating parts 205, the housing part that houses the fans also functions as a position regulating part that regulates the position of the width direction end of the sheet of paper 2 provided on the lifting plate part 203 (i.e., the movement of the sheet of paper 2 in the width direction).

[0027] <Front floating part> The floating unit 206 is a fan that blows air from the front onto the uppermost sheet 2 of the sheets 2 arranged on the lift plate unit 203, thereby floating the sheet 2.

[0028] ≪Feeding section≫ The feeding section 210 is provided above the front wall section 202, and transports the paper 2 floated by the floating section 206 while adsorbing it with air, and feeds it to the outside (front) of the paper feeder 1. The feeding section 210 includes a drive roller 211, a driven roller 212, a suction belt 213 which is an endless belt having a plurality of holes and which is wound around the drive roller 211 and the driven roller 212, and a suction section 214 which is provided on the inner periphery of the suction belt 213.

[0029] Sensor The sensor 221 is provided on the lifting plate section 203, detects the presence or absence of the paper 2 provided above the sensor 221, and outputs the detection result to the control section 223. The sensor 222 is provided on the upper part of the front wall section 202, detects the presence or absence of the paper 2 at the same height as the sensor 222, and outputs the detection result to the control section 223.

[0030] <Control Unit> The control unit 223 is composed of a CPU (Central Processing Unit), a ROM (Read-Only Memory), a RAM (Random Access Memory), an input / output circuit, and the like. When the sensor 221 detects the paper 2, the control unit 223 controls a mechanism (motor, etc.) not shown to raise the lift plate unit 203. Here, when the sensor 222 detects the paper 2, the control unit 223 stops the mechanism not shown to set the lift plate unit 203 (i.e., the uppermost paper 2) to a desired height. Here, the gap C between the uppermost paper 2 and the feed unit 210 (the lower surface of the suction belt 213) is set to a predetermined value. In this state, the floating units 205 and 206 are configured to be able to blow air onto the uppermost paper 2. Also, the suction belt 213 is located a predetermined height above the uppermost paper 2.

[0031] Next, the control unit 223 floats the topmost sheet 2 by controlling the floating units 205 and 206. The control unit 223 also controls the suction unit 214 to suck the floated sheet 2 and cause it to adhere to the suction belt 213 (suction by air), and also controls the motor for rotating the drive roller 211, etc., to transport the sheet 2 adsorbed to the suction belt 213 and supply it to the outside of the sheet feeding device 1.

[0032] Fig. 3 is a plan view showing an example of a state in which a rectangular Japanese envelope 2A is supported by the paper support table set 4 used in the paper feeder 1 according to the embodiment of the present invention. Fig. 4 is a perspective view showing the paper support table set 4 used in the paper feeder 1 according to the embodiment of the present invention.

[0033] <Paper support set> 3 or 4, the paper support table set 4 is provided on the lift plate section 203 when paper 2 having partially different thicknesses, such as envelopes, is supplied by the paper feeder 1, and is used to support a paper stack 3 which is a stack of multiple papers 2. The paper support table set 4 includes a paper support table 5 located in the center, and a pair of auxiliary paper support tables 6, 6 located on the left and right of the paper support table 5.

[0034] As shown in FIG. 3, the paper support table set 4 is provided with a first support area SA1, a second support area SA2, a third support area SA3, and a fourth support area SA4. The first support areas SA1, SA1 are areas that support the stack of paper-sheets 3 by the support portions 120, 120 of the left and right auxiliary paper support bases 6, 6. The first support areas SA1, SA1 are used when supporting wide envelopes such as a square No. 2 Japanese envelope 2A or a Western No. 3 Western envelope 2B (see FIG. 13A). The second support area SA2 is a region that supports the stack of paper sheets 3 by the second support portion 50 and the raising portion 70 of the paper support base 5. The third support area SA3 is a region that supports the stack of paper sheets 3 by the third support portion 80 of the paper support base 5. The fourth support area SA4 is a region that supports the stack of paper sheets 3 by the connecting portion 30 of the paper support base 5. The second support area SA2, the third support area SA3 and the fourth support area SA4 can support the front and rear end portions of envelopes of any size.

[0035] ≪Paper support stand≫ 3 or 4, the paper support stand 5 includes a pair of bases 10, 10, a position regulating portion 20, and a connecting portion 30. The paper support stand 5 also includes, for each base 10, a first supporting portion 40, a second supporting portion 50, a supporting force varying means 60, a raising portion 70, and a pair of front and rear third supporting portions 80, 80.

[0036] ≪Base≫ The base 10 is a long plate-shaped metal member extending in the feeding direction of the paper 2, i.e., the front-rear direction. The base 10 can be fixed to the lift plate section 203 by magnetic force. The pair of bases 10, 10 are provided parallel to each other with a predetermined gap in the width direction. In this embodiment, the pair of bases 10, 10 are two opposing sides of a metal member having a rectangular frame shape. That is, the front ends of the pair of bases 10, 10 are connected together by a front edge portion 11 extending in the left-right direction, and the rear ends of the pair of bases 10, 10 are connected together by a rear edge portion 12 extending in the width direction.

[0037] ≪Position regulation section≫ The position regulating portion 20 is a resin member that connects the front ends of the pair of bases 10, 10 to each other and regulates the position of the front end of the paper stack 3, which is a stack of multiple papers 2 supported by the paper support base 5. The position regulating portion 20 integrally includes a wall-shaped bottom wall portion 21 provided at the bottom, a front wall portion 22 extending upward from the front end of the bottom wall portion 21, and an extension wall portion 23 extending upward from a widthwise intermediate portion at the upper end of the front wall portion 22. The rear end of the bottom wall portion 21 is fixed to the front ends and the front edge portion 11 of the pair of bases 10, 10. As shown in FIG. 5, the rear surfaces of the front wall portion 22 and the extension wall portion 23 have an arc shape centered on the rotation axes A1, A2 in a side view.

[0038] The position regulating portion 20 also includes a plurality of ribs 24 extending rearward from the rear surfaces of the front wall portion 22 and the extending wall portion 23. The ribs 24 extend in the up-down direction, and are disposed at equal intervals in the width direction. As shown in Fig. 5, the tip portions (rear end surfaces) of the ribs 24 have an arc shape centered on the rotation axes A1, A2 in a side view.

[0039] ≪Connection part≫ The connecting portion 30 is a resin member that connects the rear ends of the pair of bases 10, 10 to each other. The connecting portion 30 integrally includes a bottom wall portion 31 and a rear wall portion 32 that extends upward from the rear end of the bottom wall portion 31. The front end of the bottom wall portion 31 is detachably fixed to the rear ends and rear edge portion 12 of the pair of bases 10, 10 by magnets MG3 (see FIG. 5) or screws (not shown). A handle portion 33 is formed on the upper portion of the rear wall portion 32. The handle portion 33 has a hole that penetrates the rear wall portion 32 in the front-rear direction and is configured to be gripped by a user.

[0040] The connecting part 30 has a lower protrusion extending downward from the bottom wall part 31. The lower protrusion is fitted into a groove part extending in the front-rear direction in the widthwise center part of the lifting plate part 203, thereby restricting the movement of the connecting part 30 in the widthwise direction and positioning the paper support table 5 in the widthwise direction.

[0041] <First Support> The first support part 40 is a resin member integrally including a bottom wall part 41 and a pair of side walls 42, 42 extending upward from both widthwise ends of the bottom wall part 41. The bottom wall part 41 is formed to have substantially the same width dimension as the base part 10, and is attached to the longitudinal middle part of the base part 10. The first support part 40 supports, on the upper surface of the side wall part 42, a part of the stack of paper-sheets 3 where thin parts 2X of the paper-sheets 2 (see Figs. 10A to 10C) are overlapped.

[0042] FIG. 5 is a side view that shows a schematic diagram of the paper support table set 4 used in the paper feeder 1 according to the embodiment of the present invention. 5, the side wall 42 is integrally provided with a lower portion 42a that is wide in the front-rear direction, an inclined portion 42b that extends upward from the upper end of the lower portion 42a and narrows rearward as it goes upward, and an upper portion 42c that extends upward from the inclined portion 42b and is narrower in the front-rear direction than the lower portion 42a. The inclined portion 42b is a portion for avoiding interference with an intermediate portion 52 of the second support portion 50 described later (see FIGS. 3 and 4), and the upper portion 42c is a portion to which a raised portion 70 described later is attached.

[0043] <<Second Support Part>> 3 or 4, the second support portion 50 is a main portion that supports the weight of the paper stack 3 when supporting the paper stack 3 stored in the paper feed tray from below. The second support portion 50 extends in the front-to-rear direction and is a resin member that is integrally provided with, from the rear, a base end portion 51, an intermediate portion 52, and a tip end portion 53 and has an inverted concave shape in vertical cross section.

[0044] The base end 51 is housed between the pair of side walls 42, 42, and is rotatably supported about a rotation axis A1 with respect to the pair of side walls 42, 42. When the paper stack 3 is not supported, the base end 51 is inclined upward toward the front in a side view. The intermediate portion 52 is inclined upward as it approaches the front in a side view when the paper-sheet stack 3 is not supported. Also, the intermediate portion 52 is inclined toward the inside in the width direction as it approaches the front in a plan view.

[0045] The tip portion 53 extends in a substantially horizontal direction in a side view when the paper-bundle 3 is in an unsupported state. The second support portion 50 supports a portion of the paper-bundle 3 where the thick portion 2Y (see Figs. 10A to 10C) of the paper-bundle 3 is overlapped on the upper surface of the tip portion 53. In addition, the first support portion 40 and / or the second support portion 50 is provided with a support block 54 that restricts the rotation of the second support portion 50 such that the tip portion 53 moves upward from the horizontal when the paper-bundle 3 is in an unsupported state.

[0046] The tip portion 53 includes a sensor holding portion 53a which is a recess capable of holding a sensor 221 (see FIG. 2), a through hole portion 53b formed in the bottom surface of the sensor holding portion 53a, and a paper stacking portion 53c which supports the placed paper stack 3 from below. The sensor 221 is detachable from each of the lift plate portion 203 and the sensor holding portion 53a of the tip portion 53 (see FIG. 2). The sensor 221 housed and held in the sensor holding portion 53a is connected to the control portion 223 by a wiring passing through the through hole portion 53b (see FIG. 2). The paper stacking portion 53c is formed horizontally on the upper surface of the tip portion 53.

[0047] FIG. 6 is a perspective view of the essential parts showing the installation state of the supporting force varying means 60 provided on the second supporting portion 50 of the paper support table 5. As shown in FIG. As shown in FIG. 6, the support block 54 is a member having a rotation restricting portion 54a that restricts the rotation of the second support portion 50. The support block 54 is made of a member having a concave shape in a vertical cross section, into which the tip portion 53 of the second support portion 50 is fitted so as to be rotatable within a preset range. The support block 54 is formed with the rotation restricting portion 54a and a rotation shaft installation hole 54b through which the rotation shaft A1 is inserted. As shown in FIG. 4, the left and right side surfaces of the support block 54 are installed between the left and right side wall portions 42, 42 of the first support portion 40, which are formed in an inverted concave shape. Above the support block 54, a raising portion 70 is arranged at the upper end portion of the side wall portions 42, 42. The support block 54 is placed on the base portion 10.

[0048] <Support force variable means> The supporting force variable means 60 is a moment force variable means capable of adjusting the moment force applied to a first position of the elastic member SP which urges the bottom plate portion 201 (see FIG. 2) of the paper feeder 1 in an upward direction. The supporting force variable means 60 is disposed at the base ends 51, 51 of the second support portions 50, 50 of the paper support table 5. The supporting force variable means 60 is made up of a spring SP1 disposed below the paper stacking portion 53c on which the papers 2 are stacked. The supporting force variable means 60 is supported by a block 64 (see FIGS. 6 and 7) disposed below the paper stacking portion 53c.

[0049] As shown in Fig. 3 or 4, the supporting force varying means 60 adjusts the height of the tip 53 of the second supporting portion 50 so that the topmost sheet 2 of the paper-sheet stack 3 is within a predetermined range R (see Fig. 12B) in the vertical direction. That is, the topmost sheet 2 has a height difference between different positions on its surface that is equal to or less than the predetermined range R, and is in a substantially horizontal position. On the other hand, the bottommost sheet 2 is supported by the first supporting portion 40 (raising portion 70) and the second supporting portion 50, which are at different heights, and therefore has a height difference between different positions on its surface that exceeds the predetermined range R, and is in an inclined position.

[0050] FIG. 7 is an explanatory diagram showing the principle of the supporting force varying means 60. As shown in FIG. As shown in Figs. 6 and 7, in this embodiment, the supporting force varying means 60 is configured to include a supporting shaft 61, a pair of links 62, a connecting shaft 63, a block 64, and an elastic member SP (spring SP1).

[0051] The support shaft 61 is a member for supporting one end of the elastic member SP (spring SP1). The support shaft 61 is made of a rod-shaped member that is installed on the base end 51 of the second support part 50 that has an inverted concave shape in vertical cross section.

[0052] The link 62 is composed of a pair of long plate-shaped link members whose upper end is rotatably connected to both ends of the support shaft 61 and whose lower end is rotatably connected to both ends of the connecting shaft 63. Therefore, the upper end of the link 62 is arranged to be swingable around the support shaft 61, and by swinging, the lower end changes the position of the connecting shaft 63 that supports the lower end of the spring SP1, thereby changing the direction in which the spring SP1 acts. By swinging the link 62 in the front-rear direction, the direction in which the spring SP1 acts can be changed, and accordingly, the spring force F of the second support part 50 can be adjusted.

[0053] The connecting shaft 63 is a connecting member to which the lower end of the spring SP1 is hooked. The connecting shaft 63 is made of a rod-shaped member with a pair of links 62, 62 connected to both left and right ends. The connecting shaft 63 swings in the front-rear direction about the support shaft 61, thereby changing the tension angles θ1, θ2 of the spring SP1 with respect to the rotation axis A1.

[0054] As shown in FIG. 7, the block 64 is a sliding member that is connected to the connecting shaft 63 and moves a distance L in the front-rear direction with the swinging of the connecting shaft 63 and the link 62. The block 64 has a connecting groove 64a with which the connecting shaft 63 is engaged so as to be movable up and down, and a handle portion 64b that is gripped when the block 64 is moved in the front-rear direction. The block 64 is slid in the front-rear direction to move the connecting shaft 63 forward and backward, thereby changing the tension angles θ1, θ2 of the spring SP1, thereby varying the spring force F of the spring SP1. The block 64 has a plurality of blocks 64 with different heights H. In other words, a plurality of blocks 64 with different heights H are prepared, and the blocks 64 with different heights H are selectively set to change according to the state of the paper stack 3. The paper stack 3 can be placed on the upper surface of the handle portion 64b. The lower end of the handle portion 64b is slidably engaged with a block sliding groove 101 (see Figures 3 and 6) extending in the front-to-rear direction on the base 10, and is arranged so that when the link 62 swings, it moves in the front-to-rear direction while being guided by the block sliding groove 101.

[0055] <Elastic material> As shown in FIG. 6, the elastic member SP is a biasing member that indirectly or directly biases the bottom plate portion 201 (see FIG. 2) upward. The elastic member SP is directly or indirectly disposed on the bottom plate portion 201. The elastic member SP is composed of a spring SP1 hooked between the support shaft 61 and the connecting shaft 63, and a spring SP2 (see FIG. 9) described later. The elastic member SP is composed of a member that elastically biases the second support portion 50 upward. The spring force F of the elastic member SP and the block 64 are changed depending on the paper 2. In other words, it is preferable to change the spring force F of the elastic member SP by swinging the link 62 and the connecting shaft 63 to match the height of the paper stack 3.

[0056] <Spring> As shown in Fig. 7, the spring SP1 is installed at the end of the lever-shaped second support part 50, and the moment is adjusted by changing the tension angles θ1, θ2 of the spring SP1 with the support force varying means 60 (moving one of the axes on which the spring SP1 is hung). The spring SP1 is a tension coil spring that provides springiness to the second support part 50. As described above, the spring force F of the spring SP1 can be adjusted by changing the tension angles θ1, θ2.

[0057] <Unit> 6, the unit U1 is a unit formed by combining at least a spring SP1 and a block 64. The unit U1 is detachably fixed to the base 10 by the magnetic force of a magnet MG1. Therefore, the unit U1 can be replaced with one having a spring SP1 with an appropriate spring force F and a block 64 formed to an appropriate height.

[0058] FIG. 14B is a side view showing a schematic example of a state in which a corner-pasted long Japanese envelope is supported by the paper support base. 14B is a value that is preset based on the thickness of the target paper 2, the vertical dimension of the path to which the paper 2 is supplied, etc. In the paper support base 5, the biasing force of the support force varying means 60, the distance between the side wall portion 42 of the first support portion 40 and the tip portion 53 of the second support portion 50, etc. are appropriately set so that the uppermost paper 2 is within the predetermined range R (see FIGS. 3 and 4).

[0059] Fig. 10A is a rear view diagram of a square Japanese envelope 2A as an example of the paper 2. Fig. 10B is a rear view diagram of a Western envelope 2B with a kamasu outer lining as an example of the paper 2. Fig. 10C is a rear view diagram of a Japanese envelope 2C with a right side outer lining as an example of the paper 2.

[0060] As shown in FIG. 3 or FIGS. 10A to 10C, the support force varying means 60 adjusts the height of the tip 53 of the second support portion 50 so that the difference in height between the thin portion 2X and the thick portion 2Y of the topmost paper 2 in the paper stack 3 is smaller than the difference in height between the thin portion 2X and the thick portion 2Y of the bottommost paper 2 in the paper stack 3.

[0061] <Raised section> 4, the raised portion 70 is a resin member that is detachably attached to the upper ends of the pair of side wall portions 42, 42 of the first support portion 40. The raised portion 70 integrally includes an upper wall portion 71, a front wall portion 72 extending downward from a front end portion of the upper wall portion 71, and a rear wall portion 73 extending downward from a rear end portion of the upper wall portion 71. The raised portion 70 is fitted to the side wall portions 42, 42 so as to be immovable in the front-rear direction.

[0062] <Third Support> As shown in Fig. 3 or 4, the third support part 80 is a resin member integrally including a bottom wall part 81 and a pair of side walls 82, 82 extending upward from both widthwise ends of the bottom wall part 81. The bottom wall part 81 is formed to have substantially the same width dimension as the base part 10, and is detachably attached to the longitudinal rear part of the base part 10 by a magnet MG4 (see Fig. 5). The third support part 80 is provided behind the first support part 40, and supports a part of the stack of paper-sheets 3 where the thin parts 2X of the paper-sheets 2 are overlapped on the upper surface of the side wall part 82 (see Fig. 3 and Figs. 10A to 10C).

[0063] ≪Auxiliary paper support stand≫ Auxiliary paper support stand 6 is provided on the outer side of paper support stand 5 in the width direction, and includes a base portion 110, a support portion 120, and a supporting force varying means .

[0064] ≪Base≫ The base 110 is a resin member integrally including a bottom wall 111 in the shape of a long plate extending in the front-rear direction, a pair of side walls 112, 112 extending upward from both widthwise ends at a front-rear intermediate portion of the bottom wall 111, and a handle portion 113 extending upward at the rear of the bottom wall 111. Magnets MG2, MG2 are attached to the lower surface of the bottom wall 111 for detachably fixing the lift plate 203 (see FIG. 2) by magnetic force.

[0065] ≪Support part≫ Fig. 8 is a plan view showing the installation state of the supporting force variable means 130 provided on the auxiliary paper support stand 6. Fig. 9 is a side view showing the installation state of the supporting force variable means 130 provided on the auxiliary paper support stand 6. 4, 5, 8 and 9, the support portion 120 extends in the front-rear direction and integrally includes, from the rear, a base portion 121 and a tip portion 122. The rear end portion of the base portion 121 is housed between the pair of side walls 112, 112 and is supported rotatably around a rotation axis A2 relative to the pair of side walls 112, 112.

[0066] As shown in FIG. 4, when the stack of paper 3 (see FIG. 1) is not supported, the base 121 is inclined upward as it moves forward in a side view, similar to the base end 51 and intermediate portion 52 of the second support portion 50.

[0067] The tip 122 extends in a substantially horizontal direction in a side view, similar to the tip 53 of the second support section 50, when the stack of paper-sheets 3 is not supported. The support section 120 has a paper stacking section 53c on the upper surface of the tip 122, which supports from below the portion of the stack of paper-sheets 3 where the thick portion 2Y of the paper-sheets 2 is stacked (see Fig. 3 and Figs. 10A to 10C). In addition, the base section 110 and / or the support section 120 is provided with a rotation restriction section that restricts the rotation of the support section 120 such that the tip 122 moves upward from the horizontal when the stack of paper-sheets 3 (see Fig. 1) is not supported. The paper stacking section 122c is formed horizontally on the upper surface of the tip 122.

[0068] <Support force variable means> As shown in Figs. 4, 5, 8 and 9, the supporting force variable means 130 is a moment force variable means capable of adjusting the moment force acting on the first position of the elastic member SP which urges the bottom plate portion 201 (see Fig. 2) of the paper feeder 1 upward, similar to the supporting force variable means 60 described above. The supporting force variable means 130 also adjusts the height of the tip portion 122 of the supporting portion 120 so that the uppermost paper 2 of the paper stack 3 is within a predetermined range R (see Fig. 12B) in the vertical direction. The supporting force variable means 130 is a biasing portion which elastically urges the paper stacking portion 122a of the supporting portion 120 upward, and is disposed, for example, at the base portion 121 of the supporting portion 120 of the auxiliary paper support bases 6, 6. The supporting force variable means 130 is composed of a spring SP2 disposed below the paper stacking portion 122a on which the paper 2 is stacked. The supporting force varying means 130 is supported by a block 134 disposed below the paper stacking section 122a.

[0069] As shown in FIGS. 8 and 9, in this embodiment, the supporting force varying means 130 includes a supporting shaft 131, a pair of links 132, a connecting shaft 133, a block 134, and an elastic member SP (spring SP2).

[0070] The support shaft 131 is a member for supporting the upper end of the elastic member SP (spring SP2). The support shaft 131 is made of a rod-shaped member that is installed on the base 121 of the support part 120 that has an inverted concave shape in a vertical cross section.

[0071] Link 132 is composed of a pair of long plate-shaped link members whose upper end is rotatably connected to both ends of support shaft 131 and whose lower end is rotatably connected to both ends of connecting shaft 133. Thus, link 132 is a member whose upper end is arranged to be swingable around support shaft 131, and whose lower end changes the position of connecting shaft 133 supporting the lower end of spring SP2 by swinging, thereby making it possible to change the direction in which spring SP2 acts. Link 132 makes it possible to change the direction in which spring SP2 acts, and thereby makes it possible to adjust the spring force F of support part 120.

[0072] The connecting shaft 133 is a connecting member to which the lower end of the spring SP2 is hooked. The connecting shaft 133 is made of a rod-shaped member with a pair of links 132, 132 connected to both left and right ends. The connecting shaft 133 swings in the front-rear direction around the support shaft 131, thereby changing the angle of the pulling force of the spring SP2 with respect to the rotation axis A2.

[0073] As shown in Figs. 8 and 9, the block 134 is a sliding member that is connected to the connecting shaft 133 and moves in the front-rear direction with the swinging of the connecting shaft 133 and the link 132, similar to the block 64 (see Fig. 7). The block 134 has a connecting groove (not shown) with which the connecting shaft 133 is engaged so as to be movable up and down, and a handle portion 113 that is grasped when the block 64 is moved in the front-rear direction and on which the paper-sheet stack 3 can be placed. The block 134 can be slid in the front-rear direction to move the connecting shaft 133 back and forth, thereby changing the pulling angle of the spring SP2, thereby varying the spring force of the spring SP2. The block 134 has a plurality of blocks with different heights. In other words, a plurality of blocks with different heights are prepared, and the blocks 134 with different heights are selectively set to change according to the state of the paper-sheet stack 3.

[0074] <Elastic material> 8 and 9, as described above, the elastic member SP is composed of the spring SP2 hooked between the support shaft 131 and the connecting shaft 133, and the above-mentioned spring SP1 (see FIG. 7). The elastic member SP of the supporting force varying means 130 is composed of a biasing member that elastically biases the support part 120 upward. The spring force F of the elastic member SP and the block 134 are changed depending on the paper 2. In other words, it is preferable to change the spring force F of the elastic member SP by swinging the link 132 and the connecting shaft 133 to match the height of the paper stack 3.

[0075] Spring SP2 is installed at the end of lever-shaped support part 120, and the moment is adjusted by changing the angle of spring SP2 using support force varying means 130 (moving one of the axes on which spring SP2 is hung). Spring SP2 is a tension coil spring that provides springiness to support part 120. As described above, spring SP2, like spring SP1 (see FIG. 7), makes it possible to adjust the spring force F by changing the tension angle.

[0076] <Unit> Like the above-described unit U1, the unit U2 is a unit formed by combining at least a spring SP2 and a block 134. The unit U2 is detachably fixed to the base 10 by the magnetic force of a magnet MG2. Therefore, the unit U1 can be replaced with one having a spring SP1 having an appropriate spring force F and a block 64 formed to an appropriate height.

[0077] In this way, by having the support force variable means 60, 130, the paper feeding device 1 can absorb imbalances in the thickness of the envelope and stabilize the posture of the paper feeding surface, thereby allowing envelopes of any size to be fed.

[0078] <Relationship between the position and height of the support part> 4 or 5, in the unsupported state of the paper stack 3, the upper surface of the upper wall portion 71 of the raised portion 70 fitted onto the side wall portion 42 of the first support portion 40, the upper surface of the tip portion 53 of the second support portion 50, the upper surface of the side wall portion 82 of the third support portion 80, the upper surface of the tip portion 122 of the support portion 120, and the upper edge portion of the extended wall portion 43 are set to the same height. In addition, the tip portion 53 of the second support portion 50 and the tip portion 122 of the support portion 120 are located at the same position in the front-rear direction and are arranged in the width direction. The distance between the tip portions 53 of the pair of second support portions 50 is narrower than the distance between the inner side wall portions 42, 42 of the pair of first support portions 40 and the distance between the inner side wall portions 82, 82 of the pair of third support portions 80. In other words, the distance between the pair of first support portions 40 and the distance between the pair of third support portions 80 are set to a dimension that allows the position restriction portion 204 to be disposed.

[0079] <Paper> 10A to 10C, the paper 2 may have a thick portion 2Y and a thin portion 2X, and the type of the paper 2 is not particularly limited. The paper 2 may be, for example, an envelope such as a Japanese envelope 2A or 2C or a Western envelope 2B. Below, as examples of paper 2, a square No. 2 Japanese envelope 2A, a Western-style No. 3 Western envelope 2B, and a long No. 3 Japanese envelope 3C with the right side pasted on the outside will be explained as examples.

[0080] FIG. 11A is an explanatory diagram showing a state of envelopes stacked in a paper feed tray of a comparative example. 11A, in the case of a comparative example of a paper feed tray in which a stack of paper sheets 3 such as envelopes is supported by lift plate section 203 without using elastic member SP and blocks 64, 134, when a large number of envelopes are stacked, the top surface of thick section 2Y where there is an overlap becomes higher, and the top surface of thin section 2X where there is a flap becomes lower. As a result, the envelope at the top of stack of paper sheets 3 is positioned at an angle, and cannot be air fed.

[0081] Fig. 11B is an explanatory diagram showing a state when a long No. 3 envelope and a square No. 2 envelope are stacked on a customization kit provided in a paper feed tray of the present invention. Fig. 11C is an explanatory diagram showing a state when a long No. 3 envelope and a square No. 2 envelope stacked on a customization kit provided in a paper feed tray of the present invention are lowered.

[0082] 11B and 11C, the sheets 2 (envelopes) are stacked on the lift plate section 203 of the sheet feeder 1 to form a stack of sheets 3. The envelopes (Japanese envelopes 2A, 2C, Western envelopes 2B) stacked on the lift plate section 203 are arranged so that the topmost sheet 2 (envelope) is horizontally arranged to stabilize the air feeding of the topmost stack of envelopes by the elastic member SP and the blocks 64, 134. Even if the top surface of the thick portion 2Y side of the stack of sheets 3 becomes higher due to the overlapping margin of the envelopes, the elastic member SP and the blocks 64, 134 absorb the load of the higher thick portion 2Y and support the lower thin portion 2X with the blocks 64, 134, so that the topmost envelope can be horizontal.

[0083] 11B, the paper stack 3 of paper 2 stored in the paper feed tray can be stacked high on the lift plate section 203, so that the number of sheets of paper 2 that can be stored in the paper feed tray can be significantly increased. As a result, the number of times and the time required to put the paper 2 into the paper feed tray can be reduced, improving productivity. As a specific example, it has been verified that the upper limit of paper feed capacity of the paper feed tray, which is 200 sheets, can be extended to 300 sheets by providing the elastic member SP and blocks 64, 134 in the paper feed tray. The blocks 64 and 134 may be any blocks capable of directly or indirectly supporting the lower surface of the stack of paper-sheets 3, and the shapes and materials thereof are not particularly limited.

[0084] <Square Japanese envelope> As shown in FIG. 10A, a square Japanese envelope 2A, which is an example of paper 2, has a thick bottom portion 2Y where a closure is formed by an overlap in a direction perpendicular to the width direction, and the other portions are thin portions 2X.

[0085] <Western envelope with Kamasu outer lining> As shown in FIG. 10B, a Western-style envelope 2B with a flax outer lining, which is an example of paper 2, has thicker regions 2Y on both the left and right sides where the closure is formed by the overlap in the width direction, and thinner regions 2X in the other areas.

[0086] <Rectangular Japanese envelope with side-pasting> 10C, in the direction perpendicular to the width direction, a long Japanese envelope 2C with a sealed edge, which is an example of paper 2, has a thick bottom portion 2Y where a closed portion is formed by an overlap, and a thin portion 2X other than the bottom. Also, in the width direction, one end of the long Japanese envelope 2C with a sealed edge, which is a closed portion formed by an overlap, is a thick portion 2Y, and the other portions are a thin portion 2X.

[0087] <Support method for Japanese envelopes (square)> Fig. 12A is a plan view showing an example of how a rectangular Japanese envelope 2A is supported by the paper support stand set 4. Fig. 12B is a side view showing an example of how a rectangular Japanese envelope 2A is supported by the paper support stand set 4. 12A or 12B, a stack of paper-sheets 3 containing rectangular Japanese envelopes 2A is supported by a paper-sheet support table set 4, and positioned by a first support portion 40, and a position regulating portion 204 and floating portions 205, 205 whose positions are adjusted according to the size of the Japanese envelope 2A. As shown in Fig. 12A, the stack of paper-sheets 3 of Japanese envelopes 2A is placed on and supported by first support areas SA1, SA1 of the left and right auxiliary paper-sheet support tables 6, 6, and a second support area SA2 and a third support area SA3 of the paper-sheet support table 5.

[0088] 12A or 12B, in a stack of paper-sheets 3 in which rectangular Japanese envelopes 2A are stacked, the overlapping portion of the thin section 2X is placed on and supported by an upper wall section 71 of a raising section 70 provided on a first support section 40 and by side walls 82, 82 of a third support section 80. In addition, in a stack of paper-sheets 3 in which rectangular Japanese envelopes 2A are stacked, the overlapping portion of the thick section 2Y is placed on and supported by a leading end 53 of a second support section 50 and a leading end 122 of a support section 120, which are biased by a supporting force varying means 60, 130.

[0089] Here, the weight of the thick portion 2Y causes the second support portion 50 to rotate about the rotation axis A1 such that the tip portion 53 lowers while resisting the spring force F (see Figs. 11B and 11C) of the support force variable means 60. Also, the weight of the thick portion 2Y causes the support portion 120 to rotate about the rotation axis A2 such that the tip portion 122 lowers while resisting the spring force F (see Figs. 11B and 11C) of the support force variable means 130. In this state, the (upper surfaces of) the tip portions 53, 122 support the portion of the paper-bundle 3 where the thick portion 2Y is overlapped, in a posture inclined downward toward the front in a side view.

[0090] In this state, the thick portion 2Y of the Japanese envelope 2A at the bottom of the paper-bundle 3 is lower than the thin portion 2X. Also, the thick portion 2Y of the Japanese envelope 2A at the top of the paper-bundle 3 is at approximately the same height as the thin portion 2X. That is, in the top Japanese envelope 2A, the thin portion 2X and the thick portion 2Y are positioned within a predetermined range R (approximately horizontal) in the vertical direction (see FIG. 12B). That is, in a state supported by the paper support table set 4, the difference in height between the thin portion 2X and the thick portion 2Y of the Japanese envelope 2A at the top of the paper-bundle 3 is smaller than the difference in height between the thin portion 2X and the thick portion 2Y of the Japanese envelope 2A at the bottom of the paper-bundle 3. Also, the gap C between the top Japanese envelope 2A of the paper-bundle 3 and the feeding section 210 is set to a predetermined value.

[0091] FIG. 12C is a side view that shows a schematic diagram of a state in which the top surface of a rectangular Japanese envelope 2A stacked on paper support table set 4 has become lowered. 12C, when the Japanese envelope 2A at the top of the paper-bundle 3 is fed externally and the paper-bundle 3 becomes thinner, the control unit 223 (see FIG. 1) raises the lifting plate unit 203. Also, as the paper-bundle 3 becomes lighter, the second support unit 50 (see FIG. 10A) rotates about the rotation axis A1 so that the leading end 53 rises. Similarly, as the paper-bundle 3 becomes lighter, the support unit 120 rotates about the rotation axis A2 so that the leading end 122 rises. At this time, the front end of the Japanese envelope 2A slides against the rib 44. As a result, the gap C between the top Japanese envelope 2A of the paper-bundle 3 and the feed unit 210 is maintained at a predetermined value.

[0092] In addition, when the number of stacked sheets of the paper-sheet stack 3 is small, the left and right raising parts 70 may be removed. In this case, the part of the paper-sheet stack 3 where the thin part 2X is stacked is placed on and supported by the side walls 42, 42 of the first support part 40.

[0093] When all of the Japanese envelopes 2A of the paper stack 3 have been supplied to the outside, the control unit 223 can stop the lifting of the lifting plate unit 203 by the sensor 222 detecting the extending wall unit 43.

[0094] <Support method for Western envelopes (Western style, camas outer pasting)> Fig. 13A is a plan view showing an example of how a Western-style envelope 2B with a flap on the outside is supported by the paper support base 5. Fig. 13B is a side view showing an example of how a Western-style envelope 2B with a flap on the outside is supported by the paper support base 5. Next, the method of supporting a Western envelope 2B (see FIG. 13A) with a kamasu outer pasting will be described, focusing on the differences from the case of supporting a square Japanese envelope 2A. In the drawings referred to in the following description, the floating parts 205, 206 and the feed part 210 are omitted as appropriate. As shown in FIG. 13A, the stack of Western envelopes 2B is placed and supported on the first support areas SA1, SA1 of the left and right auxiliary paper support bases 6, 6 and the second support area SA2 of the paper support base 5.

[0095] 13A and 13B, paper stack 3 on which kamasu-applied Western-style envelopes 2B are stacked is supported by paper support stand 5 and positioned by position regulating unit 20, as well as position regulating unit 204 and floating units 205, 205 whose positions are adjusted according to the size of the Western-style envelopes 2B. In kamasu-applied Western-style envelopes 2B, thicker portions 2Y at both ends in the width direction are located between the pair of left and right support units 120 and the pair of left and right tip portions 53, 53, so they have little effect on the posture of the uppermost Western-style envelope 2B.

[0096] <Support method for Japanese envelopes (long, corner-pasted)> Next, a method for supporting a long Japanese envelope 2C of the edge-pasted type will be described. As shown in FIG. 14A, a stack 3 of Japanese envelopes 2C is placed and supported on the second support area SA2 and the third support area SA3 of the paper support base 5. As shown in FIG. 14A and FIG. 14B, a stack 3 of Japanese envelopes 2C of the edge-pasted type is supported by the paper support base 5 and positioned by the position regulation unit 20, and the position regulation unit 204 and the floating units 205, 205 whose positions are adjusted according to the size of the Japanese envelope 2C. In addition, the raising unit 70 and the third support unit 80 on the side corresponding to the thick part 2Y at one end in the width direction of the Japanese envelope 2C are removed from the paper support base 5. With this configuration, the paper support base 5 can accommodate not only the difference in thickness of the Japanese envelope 2C in the feeding direction but also the thickness of the Japanese envelope 2C in the width direction, and can make the posture of the top Japanese envelope 2C approximately horizontal.

[0097] In this way, the paper support stand set 4 shown in Fig. 3 has a pair of left and right first support areas SA1, second support area SA2, third support area SA3, and fourth support area SA4, and can place and support a stack of envelopes 3 of any size, from the largest No. 0 square envelope to the smallest Western-style No. 2 envelope. As a specific example, it can accommodate envelopes with dimensions of 330 mm in the front direction and 487 mm in the longitudinal direction or less. In this case, if the envelopes can be accommodated in the kit either horizontally or vertically, they may be accommodated in either orientation.

[0098] Image forming device FIG. 15 is a side view diagrammatically illustrating an image forming apparatus 301 according to an embodiment of the present invention. The above-described paper feeder 1 is suitably used as a device for feeding paper 2 to an image forming apparatus 301. Examples of such an image forming apparatus 301 include a copying machine, a printer, a facsimile machine, a printing machine, and a multifunction machine. The following describes an example in which the image forming apparatus 301 equipped with the paper feeder 1 is applied to a copying machine.

[0099] As shown in FIG. 15, an image forming apparatus 301 according to the embodiment of the present invention includes an image forming apparatus main body 310, an image reading device 320, an automatic document feeder 330, and a paper feeder 1.

[0100] The image forming apparatus main body 310 includes, for example, a storage section 311, a supply section 312, an image forming section 313, and a discharge section 314. The storage section 311 stores a stack of paper sheets 3 each including a plurality of stacked sheets 2. The supply section 312 removes the paper sheets 2 stored in the storage section 311 from the storage section 311 and transports them to the image forming section 313.

[0101] Image forming section 313 is a section that forms an image on paper 2 transported from supply section 312 of paper feeder 1 based on an image signal transmitted from image reading device 320. For example, an electrophotographic system, an inkjet system, or the like can be adopted as the image forming method in image forming section 313. As an example, when image forming section 313 is of an electrophotographic system, image forming section 313 includes a toner image forming unit, an intermediate transfer belt, a fixing section, and the like, and forms a toner image on one main surface of paper 2. When image forming section 313 is of an inkjet system, image forming section 313 includes an inkjet head, and forms an ink image on one main surface of paper 2.

[0102] The ejection section 314 ejects the paper 2 on which the image has been formed in the image forming section 313 to the outside of the image forming apparatus main body 310.

[0103] The image reading device 320 optically reads an image from a document conveyed from the automatic document feeder 330 , processes the read image signal, and transmits it to the image forming unit 313 .

[0104] The automatic document feeder 330 includes a document table, and conveys the document placed on the document table to the image reading device 320 .

[0105] The paper feeder 1 is connected to the image forming apparatus main body 310 and supplies the paper 2 to the image forming apparatus main body 310. In this embodiment, the image forming apparatus 301 includes a plurality of paper feeders 1, and each paper feeder 1 separates and supplies the paper 2 one sheet at a time to a supply section 312 of the image forming apparatus main body 310.

[0106] The paper 2 supported by the paper support table set 4 or the paper support table 5 is supplied to the supply unit 312 with the thick portion 2Y at the front. Supplying the paper 2 with the thick portion 2Y at the front is suitable for conveyance by rollers in the supply unit 312, detection by a sensor, and the like.

[0107] As shown in Figures 3, 11B, 11C, 12B, 12C, 13B and 14B, the present invention provides a paper feeding device 1 that feeds paper 2 from the topmost paper sheet 3 of a stack of paper sheets, and includes a bottom plate portion 201 that supports the bottom surface of the paper stack 3, and an elastic member SP that is arranged directly or indirectly on the bottom plate portion 201 and urges the bottom plate portion 201 upward, and the elastic member SP includes a support force variable means 60, 130 that can adjust the moment force applied to a first position of the elastic member SP. According to this configuration, the sheet feeder 1 can adjust the moment force applied to the elastic member SP that urges the bottom plate portion 201 upward with the support force variable means 60, 130, so that even if the sheet stacks 3 are of different sizes or a large quantity of sheets 3, the spring force F can be adjusted so that the topmost sheet 2 is horizontal. Even if the sheets 2 on the sheet feed tray are of uneven thickness, the sheet feeder 1 can adjust the sheet feed tray up and down to prevent the sheet stack from tilting. Therefore, even if the sheets 2 are of any size, the change in weight imbalance due to the thickness of the envelope can be flexibly absorbed and the attitude of the sheet feed surface can be kept horizontal, so that the sheet feeder 1 can always feed the sheets in a stable state. As a result, the sheet feeder 1 can handle many different types of sheets 2 even with a single attachment.

[0108] As shown in FIGS. 5, 6, 9 and 13B, the supporting force varying means 60, 130 are springs SP1, SP2 installed below the paper stacking portions 53c, 122a on which the paper sheets 2 are stacked. According to this configuration, the supporting force varying means 60, 130 can adjust the supporting force of the paper stacking portion 53c, 122a on which the paper 2 is stacked by the springs SP1, SP2.

[0109] Also, as shown in Figures 5, 6, 7 or 9, the springs SP1, SP2 are installed at the ends of a lever-shaped support portion 120 (second support portion 50), and the moment is adjusted by changing the tension angles θ1, θ2 of the springs SP1, SP2 using the support force varying means 60, 130. According to this configuration, the springs SP1, SP2 can adjust the moment of the support part 120 (second support part 50) by making the tension angles θ1, θ2 of the springs SP1, SP2 adjustable by the support force varying means 60, 130. Therefore, the support part 120 (second support part 50) can support the paper stack 3 of paper 2 of any size with an appropriate support force.

[0110] As shown in FIG. 5, FIG. 6, FIG. 9, or FIG. 7, the spring force F of the springs SP1, SP2 can be adjusted by changing the tension angles θ1, θ2. According to this configuration, the springs SP1, SP2 make it possible to adjust the spring force F by changing the pulling angles θ1, θ2, so that the supporting force can be adjusted even for paper stacks 3 that have different sizes and thicknesses in parts and therefore different weights in parts, and therefore paper stacks 3 of any size can be supported in an optimal state.

[0111] As shown in FIG. 6, FIG. 7 or FIG. 9, the supporting force varying means 60, 130 is supported by blocks 64, 134 disposed below the paper stacking portions 53c, 122a. According to this configuration, the supporting force variable means 60, 130 is supported by blocks 64, 134 installed below the paper stacking section 53c, 122a, so that the supporting force can be adjusted appropriately according to the weight of the paper stack 3.

[0112] 11A and 11B, a plurality of blocks 64, 134 with different heights H are prepared, and the blocks 64, 134 with different heights H can be selectively set according to the state of the stack of paper-sheets 3. According to this configuration, a plurality of blocks 64, 134 having different heights H are prepared, and by selecting and replacing the block 64, 134 according to the state of the stack of paper 3, paper 2 of any size, even paper 2 having partially different thicknesses, can be appropriately supported.

[0113] Furthermore, the spring force F of the elastic member SP and the height H of the blocks 64, 134 shown in FIGS. 11A and 11B can be changed in accordance with the state of the paper 2. According to this configuration, the spring force F of the elastic member SP and the height H of the blocks 64, 134 can be changed according to the state of the paper 2, so that any type of paper 2 can always be supported in a stable state.

[0114] As shown in FIG. 12A, FIG. 13A, or FIG. 14A, the paper 2 is an envelope (Japanese envelopes 2A, 2C, Western envelope 2B). According to this configuration, paper support base 5 can easily support any size envelope, even if the envelope has partially different thicknesses.

[0115] As shown in FIG. 5, FIG. 6 or FIG. 9, the springs SP1, SP2 and the blocks 64, 134 are configured as one unit U1, U2, and the units U1, U2 are fixed to the base 10 by magnetic force. According to this configuration, the units U1, U2 are fixed to the base 10 by magnetic force, so that the springs SP1, SP2 and the blocks 64, 134 can be attached to and detached from the base 10 with a single touch. Therefore, when the size of the paper 2 or the like changes, the springs SP1, SP2 and the blocks 64, 134 can be easily replaced with springs SP1, SP2 and blocks 64, 134 suited to the paper 2 for supporting the paper 2.

[0116] Also, as shown in Figures 11B, 11C, 12B, 12B, 13B or 14B, the support force variable means 60, 130 adjusts the moment force applied to the first position of the elastic member SP so that the top envelope (Japanese envelope 2A, 2C, Western envelope 2B) is positioned horizontally. According to this configuration, the support force varying means 60, 130 adjusts the moment force applied to the first position of the elastic member SP so that the envelope is positioned horizontally, thereby enabling the envelope to be fed at all times, even if the size or type of envelope changes.

[0117] As shown in FIG. 15, an image forming apparatus 301 according to an embodiment of the present invention includes a paper feeder 1 and an image forming section 313 that forms an image on a paper 2 supplied from the paper feeder 1. According to this configuration, the image forming device 301 supports the topmost sheet of paper 2, which is the target of image formation, in a suitable posture even if the sheet of paper 2 is of any size, so that the sheet of paper 2 can be fed in a suitable manner and an image can be formed on the sheet of paper 2 in a suitable manner.

[0118] [Variations] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and can be modified as appropriate without departing from the gist of the present invention. Note that the same reference numerals are used to designate components that have already been described, and the description thereof will be omitted. FIG. 16 is a diagram showing a modified example of the paper feeder 1 according to the embodiment of the present invention, and is a side view showing an installation state of the supporting force variable means 130A provided on the auxiliary paper support stand 6.

[0119] The block 134 of the supporting force varying means 130 shown in FIG. 9 and described in the above embodiment may be configured to slide in a groove, similar to the block 64 shown in FIGS. 16, the block 134A of the supporting force varying means 130A has the block 134A and a connecting portion 134Aa formed integrally with the block 134A slidably disposed in a block sliding groove 114 extending in the front-rear direction on the bottom wall portion 111. A long hole 134Ab with which the connecting shaft 133 engages is formed in the front end portion of the connecting portion 134Aa.

[0120] According to this configuration, when the handle portion 113 of the block 134A is operated in the front-rear direction, the connecting portion 134Aa moves integrally with the block 134A in the front-rear direction, causing the link 132 to swing in the front-rear direction. By swinging the link 132, the pulling angle of the spring SP2 can be adjusted, and therefore the moment of the support portion 120 can be adjusted. Therefore, by operating the handle portion 113 in the front-rear direction, the support portion 120 can be adjusted so that it can support a paper stack 3 of paper 2 of any size with a suitable supporting force. [Explanation of symbols]

[0121] 1 Paper feeder 2 Paper 2A Japanese envelope (envelope) 2B Western envelope (envelope) 2C Japanese envelope (envelope) 3 Paper stack 10 base 50 Second support part (support part) 53c,122a Paper stacking section 60,130,130A Support force variable means 64,134,134A Block 120 Support part 201 Bottom plate part 301 Image forming device 313 Image forming section F Spring force H Height SP Elastic material SP1, SP2 springs U1, U2 Unit θ1,θ2 Pull angle (angle)

Claims

1. A paper feeder that feeds a stack of paper sheets in order from the topmost sheet, A bottom plate portion that supports a lower surface of the paper stack; an elastic member disposed directly or indirectly on the bottom plate portion and biasing the bottom plate portion upward; The elastic member includes a supporting force varying means capable of adjusting a moment force applied to the first position of the elastic member. Paper feeding device.

2. The supporting force varying means is a spring installed below a paper stacking section on which the paper is stacked. The paper feeder according to claim 1 .

3. The spring is installed at an end of a lever-shaped support portion, and the angle of the spring is changed by the supporting force varying means, thereby making it possible to adjust the moment.

3. The paper feeder according to claim 2.

4. The spring force can be adjusted by changing the tension angle. The paper feeder according to claim 2 .

5. The supporting force varying means is supported by a block installed below the paper stacking section. The paper feeder according to claim 2 .

6. A plurality of blocks having different heights are prepared, and the blocks having different heights can be selectively set in accordance with the state of the paper stack.

6. The paper feeder according to claim 5.

7. The spring force of the elastic member and the height of the block can be changed according to the state of the paper.

6. The paper feeder according to claim 5.

8. The paper is an envelope. The paper feeder according to claim 1 .

9. the spring and the block are configured as one unit; The unit is fixed to the base by magnetic force.

6. The paper feeder according to claim 5.

10. The supporting force varying means is The moment force acting on the first position of the elastic member is adjusted so that the top envelope is horizontally positioned. The paper feeder according to claim 8.

11. A paper feeder according to any one of claims 1 to 10, an image forming unit that forms an image on the paper fed from the paper feed device; Equipped with Image forming device.

Images