Paper feeder and image forming apparatus

Abstract

To provide a paper feeder capable of appropriately pulling a paper feeding cassette to a feeder position, and an image forming apparatus.SOLUTION: A paper feeding cassette comprises: a rectangular bottom part for placing a sheet; a cassette wall part erected along the outer periphery of the bottom part; a first positioning part and a second positioning part that are provided at the cassette wall part on a side of being inserted into a paper feeder body part, each for positioning the paper feeding cassette to a paper feeder; and a protrusion part engaging with an engagement part possessed by a puling-in unit. The first positioning part, the second positioning part and the engagement part are provided on one side deviating from the center in a width direction orthogonal to a paper feeding cassette insertion direction in a plan view obtained by viewing the paper feeding cassette from above. The engagement part is provided between the first positioning part and the second positioning part in the width direction in the plan view obtained by viewing the paper feeding cassette from above.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a paper feeding device and an image forming apparatus. [Background technology]

[0002] 2. Description of the Related Art Paper feeders and image forming apparatuses have been disclosed in the past.

[0003] Furthermore, Patent Document 1 discloses an apparatus provided with a unit restricting means for restricting rotation of the sheet feed cassette at a position where the unit retracting mechanism starts the retracting operation and the sheet feed cassette receives a load.

[0004] In addition, Patent Document 2 discloses a sheet storage means and an image forming apparatus that can ensure a return force when the sheet storage means is pulled out without increasing the retraction force, and that can reduce the operating force required when attaching and pulling out the sheet storage means to the device main body. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-141513 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-124699 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the device described in the above patent document, if the load of the paper feed cassette being pulled into the device is large, the paper feed cassette is pulled in at an angle, and the device is not configured to properly pull the paper feed cassette to the specified device position.

[0007] In view of the above, an object of the present disclosure is to provide a paper feed device and an image forming device that can appropriately retract a paper feed cassette to the device position. [Means for solving the problem]

[0008] In one aspect of the present disclosure, a paper feed device includes a paper feed device main body, a paper feed cassette that can be inserted into and pulled out of the paper feed device main body, and a retraction unit that retracts the paper feed cassette into the paper feed device main body, wherein the paper feed cassette has a rectangular bottom for placing sheets, a cassette wall that stands along the outer periphery of the bottom, a first positioning portion and a second positioning portion that are provided on the cassette wall on the side that is inserted into the paper feed device main body for positioning the paper feed cassette in the paper feed device, and a protrusion that engages with an engaging portion of the retraction unit, wherein the first positioning portion, the second positioning portion, and the engaging portion are provided to one side of the center in a width direction perpendicular to the paper feed cassette insertion direction when the paper feed cassette is viewed in a plan view from above, and the engaging portion is provided between the first positioning portion and the second positioning portion in the width direction when the paper feed cassette is viewed in a plan view from above.

[0009] Another aspect of the present disclosure is characterized by including the above-described paper feeding device and an image forming section that forms an image on a sheet sent out from the paper feeding device. [Effects of the Invention]

[0010] As described above, according to the present disclosure, it is possible to provide a paper feed device and an image forming apparatus that can appropriately retract a paper feed cassette to the device position. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing the internal structure of an image forming apparatus according to the present disclosure as viewed from the front side. [Figure 2] FIG. 2 is a perspective view showing a paper feeder according to the present disclosure. [Figure 3] 3 is a plan view of a paper feed cassette provided in the paper feed device shown in FIG. 2, seen from above. [Figure 4] 4 is a side view of the paper feed cassette provided in the paper feed device shown in FIG. 2, seen from the right side. [Figure 5] 5 is a perspective view showing the internal structure of a paper feeder main body provided in the paper feeder shown in FIG. [Figure 6] FIG. 6 is a perspective view showing a first positioning target portion formed on the paper feeding device main body. [Figure 7] FIG. 7 is a plan view showing the internal structure of a lead-in unit included in a paper feeder main body according to the present disclosure. [Figure 8] FIG. 8 is a plan view showing the internal structure of a lead-in unit included in a paper feeder main body according to the present disclosure. [Figure 9] FIG. 9 is a conceptual diagram of a plan view of the paper feed cassette as seen from above. [Figure 10] FIG. 10 is a conceptual diagram of a plan view of the paper feed cassette as seen from above. [Figure 11] FIG. 11 is a conceptual diagram of a rear view of the paper feed cassette as seen from the rear. [Figure 12] FIG. 12 is a partial enlarged view of an area A of the paper feed cassette shown in FIG. [Figure 13] 13 is a diagram schematically showing the height difference of the rail portion of the paper feed cassette shown in FIG. [Figure 14] FIG. 14 is a graph showing the relationship between the retraction force of the retraction unit and the force required to retract the paper feed cassette to the installation position in the paper feed device according to the present disclosure. [Figure 15] FIG. 15 is a diagram schematically illustrating the principle of generation of a force that pulls a paper feed cassette provided in a paper feed device according to the present disclosure to the installation position. DETAILED DESCRIPTION OF THE INVENTION

[0012] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. Note that the embodiments described below do not unduly limit the content of the present disclosure described in the claims, and not all of the configurations described in the embodiments are necessarily essential as means for solving the problems of the present disclosure.

[0013] (Image forming device) An image forming apparatus 100 according to the present disclosure will be described with reference to FIG. 1. FIG. 1 is a schematic diagram showing the internal structure of the image forming apparatus 100 according to the present disclosure as viewed from the front side. In the image forming apparatus 100, the left side of the horizontal direction when viewed from the front side is defined as the left direction, and the right side is defined as the right direction. In addition, in the depth direction when viewed from the front side, the front side (near side) of the image forming apparatus 100 is defined as the front direction, and the back side (deep side) is defined as the rear direction. In addition, in the image forming apparatus 100, the bottom side is defined as the downward direction, and the opposite side is defined as the upward direction.

[0014] As shown in FIG. 1, the image forming apparatus 100 includes a main body 110, an image reading device 200, a paper feeding device 400, and a manual feeding unit 510.

[0015] An image reading device 200 is provided on the upper part of the main body 110. The image reading device 200 is a device that reads an image of an original G. The image reading device 200 has an original placement table 221 formed of a transparent material on which the original G is placed. Above the original placement table 221, an original pressing cover 218 is provided which is attached via a hinge or the like so as to be able to open and close freely. A original supply tray 220 is provided on the upper surface of the original pressing cover 218, and an automatic document feeder (ADF: Auto Document Feeder) (not shown) is provided inside the original supply tray 220. The ADF automatically supplies the originals G placed on the original supply tray 220 to an image reading position 222 one by one.

[0016] The image reading device 200 incorporates an image reading unit 226 that reads an image from an original G. The image reading unit 226 includes a light source, multiple mirrors, an imaging lens, and a line sensor, all of which are not shown. The image reading device 200 exposes the original G to light emitted from the light source, and guides the light reflected from the original G to the imaging lens via multiple mirrors. The imaging lens then forms an image of the reflected light on a light-receiving element of the line sensor. The line sensor detects the luminance or chromaticity of the reflected light that forms an image on the light-receiving element, and generates image data based on the original G. The line sensor may be, for example, a charge-coupled device (CCD) or a contact image sensor (CIS).

[0017] A paper feeder 400 including a paper feed cassette 410 and a sheet supply unit 420 is provided at the bottom of the main body 110 .

[0018] The paper feed cassette 410 stores sheets P to be supplied to the main body 110. In the image forming apparatus 100 according to the present disclosure, the paper feed cassette 410 is configured to store 500 sheets P. The sheets P stored in the paper feed cassette 410 are supplied to the main body 110 by the sheet supply unit 420.

[0019] The sheet supply unit 420 has a pick-up roller 421, a supply roller 422, and a separation roller 423. The pick-up roller 421 is driven to rotate to pull out sheets P stored in the paper feed cassette 410 from above and send them toward the supply roller 422 and the separation roller 423. The separation roller 423 is disposed in a position facing the supply roller 422. When supplying sheets P to the main body 110, the separation roller 423 is maintained in a state of pressing against the supply roller 422. Then, as the separation roller 423 is driven to rotate, the sheets P are separated and conveyed one by one between the supply roller 422 and the separation roller. Note that the pick-up roller 421 may not be provided, and the supply roller 422 may also serve as the pick-up roller 421. In such a configuration, the supply roller 422 is driven to rotate to pull out sheets P from the paper feed cassette 410.

[0020] 1 shows only one paper feed cassette 410 and one sheet supply unit 420 for ease of explanation, but image forming apparatus 100 according to the present disclosure has a configuration in which three paper feed cassettes 410 are arranged in multiple stages in the vertical direction, and each paper feed cassette 410 is provided with a sheet supply unit 420. The detailed configuration of paper feed device 400 will be described later.

[0021] Furthermore, a manual feed unit 510 having a sheet storage section is provided on the lower right side of the main body 110. The manual feed unit 510 supplies sheets P that cannot be set in the paper feed cassette 410 of the paper feed device 400 to the image forming apparatus 100.

[0022] The sheets P stored in the sheet cassette 410 of the sheet feeding device 400 and the sheets P stored in the sheet storage section of the manual feeding unit 510 are sent to the sheet transport path W1 of the main body 110 via the transport roller 12a.

[0023] The main body 110 includes an image forming section 102 and a sheet transport system 103 .

[0024] The image forming section 102 includes an exposure unit 1, a development unit 2, a photosensitive drum 3 that acts as an electrostatic latent image carrier, a cleaning section 4, a charging device 5, a primary transfer device 6, a fixing unit 7, and a secondary transfer device 10. The image forming section 102 forms an image on a sheet P transported from a paper feed cassette 410 or the like, and discharges the sheet onto a discharge tray 14. Examples of image data for forming an image on the sheet P include image data read from an original G by an image reading section 226, or image data transmitted from an external computer or the like.

[0025] On the other hand, the sheet transport system 103 has a sheet transport path W1. In the sheet transport path W1, there are arranged, from the transport roller 12a toward the discharge tray 14, the registration roller 13, the transfer roller 10a provided in the secondary transfer device 10, the fixing roller 71 and the pressure roller 72 provided in the fixing unit 7, and the discharge roller 31. The direction from the transport roller 12a toward the discharge tray 14 is referred to as the sheet transport direction.

[0026] When forming an image in the image forming apparatus 100, in the image forming section 102, the charging device 5 uniformly charges the surface of the photosensitive drum 3. Furthermore, the exposure unit 1 exposes the charged surface of the photosensitive drum 3 to laser light based on image data. This forms an electrostatic latent image on the photosensitive drum 3. The exposure unit 1 can be configured as a laser scanning unit equipped with a laser emission unit, a reflection mirror, and the like (not shown).

[0027] The electrostatic latent image formed on the photosensitive drum 3 is developed by the developing unit 2 and visualized as a toner image. That is, the developing unit 2 includes a developer tank (not shown) that contains toner and a developing roller that functions as a developer carrier. The developing unit 2 supplies toner to the surface of the photosensitive drum 3, and visualizes the electrostatic latent image formed on the surface of the photosensitive drum 3 with the toner. A toner concentration detection sensor (not shown) that detects the toner concentration is provided inside the developing tank. When the toner concentration detected by this toner concentration detection sensor falls below a predetermined value, toner is replenished to the developing tank from a toner replenishing device (not shown).

[0028] The toner image on the photosensitive drum 3 is transferred in the primary transfer device 6 onto an intermediate transfer belt 6c that is stretched between a drive roller 6a and a driven roller 6b and rotates in a rotation direction E. The toner image on the intermediate transfer belt 6c is then transported to the secondary transfer device 10.

[0029] Meanwhile, sheet P supplied from sheet feeding device 400 or manual feed unit 510 is conveyed through sheet conveyance path W1, via conveyance rollers 12a, to registration rollers 13. Next, sheet P is conveyed by registration rollers 13 to transfer rollers 10a at a timing when sheet P and the toner image on photosensitive drum 3 are aligned. Then, the toner on photosensitive drum 3 is transferred onto sheet P by transfer roller 10a. Thereafter, sheet P passes through fixing roller 71 and pressure roller 72 in fixing unit 7, and is discharged to discharge tray 14 via discharge rollers 31.

[0030] The fixing unit 7 includes a fixing roller 71 and a pressure roller 72, and is disposed downstream of the image forming section 102 in the sheet conveying direction. The fixing roller 71 is set to a predetermined fixing temperature (for example, 160°C), and when the sheet P passes through the nip area (fixing nip portion) between the fixing roller 71 and the pressure roller 72, the toner image transferred to the sheet P is melted, mixed, and pressed against the sheet P. In this way, the toner image is thermally fixed to the sheet P.

[0031] When an image is to be formed on the back side of the sheet P in addition to the front side, the sheet P is conveyed in the opposite direction from the discharge rollers 31 through the reverse sheet conveying path W2. In the reverse sheet conveying path W2, the sheet P passes through each of the reverse conveying rollers 12b provided at two locations spaced a predetermined distance apart, and is guided again to the registration rollers 13 in a state where the sheet P is turned over. Then, a toner image is formed and fixed on the back side of the sheet P in the same manner as on the front side. The sheet P is then discharged to the discharge tray 14.

[0032] After development and image transfer, toner remains on the surface of the photosensitive drum 36. Therefore, the image forming apparatus 100 is provided with a cleaning unit 4 having a cleaning blade or the like that comes into contact with the surface of the photosensitive drum 36, and is configured to remove the toner remaining on the surface of the photosensitive drum 36 by this cleaning unit 4.

[0033] Furthermore, main body 110 having the above-described configuration is equipped with a control unit including a CPU, memory, etc. (not shown). The control unit is configured to transmit control signals to each part of image forming apparatus 100 in response to input operations on the operation panel, etc., and cause image forming apparatus 100 to perform various operations.

[0034] Note that image forming apparatus 100 is configured to include sheet feeding device 400 and manual feeding unit 510. However, image forming apparatus 100 may be configured to include an external sheet feeding device, and to feed sheets P to sheet conveying path W1 from this external sheet feeding device.

[0035] (Paper feeder) 2 to 5, the configuration of sheet feeding device 400 according to the present disclosure will be described. As sheet feeding device 400 according to the present disclosure, a sheet feeding device built into the lower part of image forming apparatus 100 will be described as an example, but the present disclosure is not limited to this. For example, sheet feeding device 400 may be provided separately from image forming apparatus 100.

[0036] Fig. 2 is a perspective view showing a sheet feeding device 400 according to the present disclosure. Fig. 3 is a plan view of a sheet feeding cassette 410 provided in the sheet feeding device 400 shown in Fig. 2, seen from above. Fig. 4 is a side view of a sheet feeding cassette 410 provided in the sheet feeding device 400 shown in Fig. 2, seen from the right side. Fig. 5 is a perspective view showing the internal structure of a sheet feeding device main body 401 provided in the sheet feeding device 400 shown in Fig. 2.

[0037] FIG. 2 is a perspective view of the sheet feeding device 400 as viewed from the front side. In the horizontal direction as viewed from the front side, the left side is defined as the left direction, and the right side is defined as the right direction. In addition, in the depth direction as viewed from the front side, the front side (near side) of the sheet feeding device 400 is defined as the front direction, and the rear side (deep side) is defined as the rear direction. In addition, in the sheet feeding device 400, the bottom side is defined as the downward direction, and the opposite side is defined as the upward direction. Note that FIG. 2 shows a state in which the sheet feeding cassette 410 is pulled out from the sheet feeding device main body 401. In addition, in FIG. 5, the left and right side walls of the sheet feeding device 400 are omitted for convenience in order to make the internal structure of the sheet feeding device main body 401 easier to understand.

[0038] 2, the sheet feeding device 400 has a substantially rectangular parallelepiped shape and includes a sheet feeding device main body 401 and a sheet feeding cassette 410. Three sheet feeding cassettes 410 may be provided. Each of the three sheet feeding cassettes 410 is provided so as to be insertable into and removable from the sheet feeding device main body 401 in a front-to-rear direction (first direction). Note that, in the front-to-rear direction, the direction in which the sheet feeding cassette 410 is inserted into the sheet feeding device main body 401 is referred to as the insertion direction, and the direction in which the sheet feeding cassette 410 is removed from the sheet feeding device main body 401 is referred to as the removal direction of the sheet feeding cassette 410.

[0039] (Paper cassette) 2 and 3, the sheet feed cassette 410 has a rectangular bottom 410a and cassette walls extending upward from the bottom 410a along the outer periphery of the bottom 410a. The cassette walls include a first cassette wall 410b, a second cassette wall 410c, a third cassette wall 410d (second side wall), and a fourth cassette wall 410e (first side wall). The first cassette wall 410b and the second cassette wall 410c are the cassette walls on the side that is inserted into the sheet feeder main body 401.

[0040] The first cassette wall 410b is connected to the front edge of the bottom 410a, the second cassette wall 410c is connected to the rear edge of the bottom 410a, the third cassette wall 410d is connected to the left edge of the bottom 410a, and the fourth cassette wall 410e is connected to the right edge of the bottom 410a, and the bottom 410a, the first cassette wall 410b, the second cassette wall 410c, the third cassette wall 410d, and the fourth cassette wall 410e form a rectangular parallelepiped container with an open top.

[0041] A plurality of sheets P are placed at predetermined positions in a sheet storage area surrounded by the bottom 410a, the first cassette wall 410b, the second cassette wall 410c, the third cassette wall 410d, and the fourth cassette wall 410e. For ease of explanation, the sheets P are omitted from FIG. 3.

[0042] The sheet storage area is provided with a first guide clip 411a and a second guide clip 411b for aligning multiple sheets P in a predetermined position. Each of the first guide clip 411a and the second guide clip 411b has a partition plate that stands upright from the bottom 410a. The partition plate of the first guide clip 411a is movable in the left-right direction and is moved to abut against the left side of the sheet P. The partition plate of the second guide clip 411b is movable in the front-rear direction (first direction) and is moved to abut against the front side of the sheet P. In this way, the partition plates of the first guide clip 411a and the second guide clip 411b allow multiple sheets P to be placed in an aligned state in a predetermined position in the sheet storage area.

[0043] In an embodiment of the present disclosure, as will be described later, when the sheet feed cassette 410 is inserted into the sheet feed device main body 401, the sheet supply unit 420 is provided at a position corresponding to the right side of the sheet feed cassette 410 of the sheet feed device main body 401. Therefore, when the sheet feed cassette 410 is viewed from above, the sheets P are placed to the right of the center position in the left-right direction of the sheet feed cassette 410. Therefore, at the bottom 410a of the sheet feed cassette 410, the center of gravity of the sheet feed cassette 410 is located to the right of the center position in the left-right direction.

[0044] As shown in FIGS. 2 to 4, a pair of rails 412 that abut against the sheet feeding device main body 401 is provided on the outer surfaces of both left and right sides of the sheet feeding cassette 410, i.e., the third cassette wall 410d and the fourth cassette wall 410e. The rail 412 provided on the third cassette wall 410d is a flange member that protrudes leftward from the third cassette wall 410d and extends in the front-to-rear direction. The rail 412 provided on the fourth cassette wall 410e is a flange member that protrudes rightward from the fourth cassette wall 410e and extends in the front-to-rear direction. As shown in FIG. 4, the rail 412 provided on the fourth cassette wall 410e has a protrusion 415 at a substantially central position of the rail 412 that engages with an engagement portion 505 of the retraction unit 500 (described later).

[0045] 4, for example, sheet feed cassette rollers 416 are provided at the rear positions of each of the pair of rail portions 412. The sheet feed cassette rollers 416 are cylindrical rotating members that come into contact with the guide frame 403 to facilitate the insertion and removal of the sheet feed cassette 410. The sheet feed cassette rollers 416 can assist the movement of the sheet feed cassette 410 in the front-to-rear direction. Details of the rail portions 412 will be described later.

[0046] 3, the first cassette wall 410b of the sheet feed cassette 410 has a first flange 410b1 that protrudes leftward from the joining position with the third cassette wall 410d, and a second flange 410b2 that protrudes rightward from the joining position with the fourth cassette wall 410e. The second flange 410b2 is provided with a first positioning portion 413 on the cassette wall (first cassette wall 410b) on the side that is inserted into the sheet feed device main body 410.

[0047] Further, the second cassette wall 410c has a second positioning portion 414 on the cassette wall (second cassette wall 410c) on the side inserted into the sheet feeding device main body 410. The first positioning portion 413 and the second positioning portion 414 are provided to face the sheet feeding device main body 410. The cassette wall on the side inserted into the sheet feeding device main body 410 is, in other words, a wall provided along the width direction X perpendicular to the sheet feeding cassette insertion direction Y.

[0048] As will be described later, sheet feeding device main body 401 is provided with first positioning receiving portion 406 that engages with first positioning portion 413 and second positioning receiving portion 407 that engages with second positioning portion 414. When sheet feeding cassette 410 is inserted into sheet feeding device main body 401, sheet feeding cassette 410 can be positioned within sheet feeding device main body 401 by engaging first positioning portion 413 with first positioning receiving portion 406 and engaging second positioning portion 414 with second positioning receiving portion 407.

[0049] The first positioning portion 413 and the second positioning portion 414 may be convex or hole-shaped as shown in Fig. 3. When the first positioning portion 413 and the second positioning portion 414 are convex, the first positioned portion 406 and the second positioned portion 407 are hole-shaped, and when the first positioning portion 413 and the second positioning portion 414 are hole-shaped, the first positioned portion 406 and the second positioned portion 407 are convex. The convex shape or the size or depth of the hole of the first positioning portion 413 and the second positioning portion 414 may be the same as shown in Fig. 3 or may be different. The hole may be circular or rectangular in shape when viewed from the front.

[0050] Furthermore, after the retraction unit 500 starts retraction, the positions of the first positioning portion 413, the second positioning portion 414 and the engaging portion 505, and the lengths or depths of the first positioning portion 413 and the second positioning portion 414 and the first positioning portion 406 and the second positioning portion 407 may be adjusted so that the first positioning portion 413 or the second positioning portion 414 engages with the first positioning portion 406 with which the first positioning portion 413 engages or the second positioning portion 407 with which the second positioning portion 414 engages.

[0051] 3, the engaging portion 505 of the retraction unit that engages with the first positioning portion 413, the second positioning portion 414, and the protrusion 415 is provided on one side of the center Ox of the paper feed cassette in the width direction X (the left-right direction in FIG. 3) that is perpendicular to the insertion direction of the paper feed cassette 410 in a plan view of the paper feed cassette 410 seen from above. The engaging portion 505 will be described later.

[0052] The engagement portion 505 that engages with the protrusion 415 is provided between the first positioning portion 413 and the second positioning portion 414 in the width direction X in a plan view of the sheet feed cassette 410 seen from above. That is, in the width direction X in FIG. 3, the first positioning portion 413, the engagement portion 505, and the second positioning portion 414 are provided in this order from the right.

[0053] In this way, the paper feed cassette can be appropriately retracted to the device position. After explaining retraction unit 500 (described later), the positional relationship between first positioning portion 413, second positioning portion 414, engaging portion 505, and the operating area in which engaging portion 505 operates will be described in detail.

[0054] Also, as shown in FIG. 3, it is preferable that the first positioning portion 413 and the second positioning portion 414 are provided at the same position or different positions from each other in the width direction X of the paper feed cassette 410. That the first positioning portion 413 and the second positioning portion 414 are at the same position from each other in the width direction X means that, in FIG. 3, the first positioning portion 413 and the second positioning portion 414 are arranged in a straight line. Also, that the first positioning portion 413 and the second positioning portion 414 are at different positions from each other in the width direction X means that, as shown in FIG. 3, the first positioning portion 413 and the second positioning portion 414 are not arranged in a straight line.

[0055] Also, as shown in FIG. 3, it is preferable that the interval X1 between the first positioning portion 413 and the second positioning portion 414 in the width direction X of the paper feed cassette 410 is smaller than the interval Y1 between the first positioning portion 413 and the second positioning portion 414 in the insertion direction Y of the paper feed cassette 410. That is, X1 < Y1. The reference for the interval between the first positioning portion 413 and the second positioning portion 414 is the center of the axis and the center of the length if it is a protrusion, and the center of the hole and the center of the depth if it is a hole.

[0056] As shown in FIG. 4, it is preferable that the first positioning portion 413 and the second positioning portion 414 are provided at the same height position or different height positions from each other in the height direction Z (vertical direction in FIG. 4) of the paper feed cassette 410. That the first positioning portion 413 and the second positioning portion 414 are at the same height position from each other in the height direction Z means that, in FIG. 4, the first positioning portion 413 and the second positioning portion 414 are arranged in a straight line. Also, that the first positioning portion 413 and the second positioning portion 414 are at different height positions from each other in the height direction Z means that, as shown in FIG. 4, the first positioning portion 413 and the second positioning portion 414 are not arranged in a straight line.

[0057] 2 to 4, a handle 417 is provided to protrude forward from approximately the center of first cassette wall 410b of sheet cassette 410. A user can grasp handle 417 to insert sheet cassette 410 into sheet feeder main body 401 or pull sheet feeder cassette 410 out of sheet feeder main body 401.

[0058] (Paper feeder main body) 2 and 5, sheet feeding device main body 401 has a generally rectangular parallelepiped shape with openings on the top and front. When sheet feeding device 400 is provided separately from image forming apparatus 100, the top surface may be closed by an upper wall.

[0059] Sheet feeder main body 401 includes rectangular sheet feeder bottom 401a, and rear wall 401b, left wall 401c, and right wall 401d that extend upward from sheet feeder bottom 401a along the outer periphery of sheet feeder bottom 401a. Rear wall 401b is connected to the rear edge of sheet feeder bottom 401a, left wall 401c is connected to the left edge of sheet feeder bottom 401a, and right wall 401d is connected to the right edge of sheet feeder bottom 401a, and sheet feeder bottom 401a, rear wall 401b, left wall 401c, and right wall 401d form a substantially rectangular parallelepiped housing that is open on the top and front. The paper feed cassette 410 can be inserted into the paper feed device main body 401 or pulled out from the paper feed device main body 401 through the opening on the front surface.

[0060] 2, sheet supply unit 420 is provided on right side wall 401d of sheet feeder main body 401. Therefore, as described above, the sheet storage area in sheet feed cassette 410 where sheets P are placed is located to the right of the center of sheet feed cassette 410.

[0061] As shown in Fig. 5, the first positioning target portion 406 is formed on the right frame side of the frame 402 that forms an opening in the front of the sheet feeding device main body 401. In addition, the second positioning target portion 407 is formed on the rear wall 401b. In this disclosure, the sheet feeding device 400 is provided with three sheet feeding cassettes 410. Therefore, the first positioning target portion 406 and the second positioning target portion 407 are formed at positions corresponding to each sheet feeding cassette 410. Note that in Fig. 5, the first positioning target portion 406 and the second positioning target portion 407 are shown as holes.

[0062] When first positioning target portion 406 is a hole, as shown in Fig. 6, an inner surface of first positioning target portion 406 may have uneven portions 406a formed thereon, each consisting of a plurality of uneven portions. Fig. 6 is a perspective view showing first positioning target portion 406 when it is a hole formed in sheet feeding device main body 401. As shown in Fig. 6, first positioning target portion 406 may have uneven portions 406a formed on parts of the left and right side walls of the inner periphery of first positioning target portion 406.

[0063] In this way, the first positioned portion 406 has the uneven portion 406a on its inner periphery, which reduces the contact area between the first positioned portion 406 and the first positioning portion 413. This reduces the load when the first positioning portion 413 is inserted into the first positioned portion 406.

[0064] In addition, when the second positioned portion 407 is a hole, although not shown, an uneven portion may be formed on the inner surface of the second positioned portion 407, similar to the first positioned portion 406. This makes it possible to reduce the contact area between the second positioned portion 407 and the second positioning portion 414, and to reduce the load when the second positioning portion 414 is inserted into the second positioned portion 407.

[0065] 5, a pair of guide frames 403 are provided on the inside of the left side wall 401c and the right side wall 401d of the sheet feeder main body 401, extending in the front-rear direction (first direction) and capable of guiding the sheet feed cassette 410 inserted into the sheet feeder main body 401 to an installation position. The installation position is a predetermined position when the sheet feed cassette 410 is installed in the sheet feeder main body 401. When the sheet feed cassette 410 is in the installation position, the sheets P stored in the sheet feed cassette 410 are at a predetermined sheet feed position.

[0066] The pair of guide frames 403 are rod members extending in the front-rear direction and arranged so as to span between the left and right frame sides of the frame body 402 and the rear wall portion 401b. As shown in Fig. 5, the guide frame 403 has a U-shaped cross section, and a sliding surface 403a on which the sheet feed cassette rollers 416 move is formed below. The sliding surface 403a supports the sheet feed cassette 410 from below and allows the sheet feed cassette 410 to move in the front-rear direction.

[0067] Furthermore, a retraction unit 500 (retraction device) is provided on the upper surface 403b of the right guide frame 403 of the pair of guide frames 403. In the present disclosure, the retraction unit 500 is configured to be provided on the sheet feeding device main body 401 via the guide frame 403, but this configuration is not limited to this. For example, the retraction unit 500 may be configured to be directly provided on the inside of the right side wall 401d of the sheet feeding device main body 401.

[0068] The retraction unit 500 engages with the sheet feed cassette 410 inserted into the sheet feed device main body 401 and applies a force to pull it rearward, i.e., toward the insertion direction. This allows the retraction unit 500 to retract the sheet feed cassette 410 to the installation position. This reduces the burden on the user when pushing the sheet feed cassette 410 into the sheet feed device main body 401 when inserting the sheet feed cassette 410 into the sheet feed device main body 401. The retraction unit 500 will be described in detail below.

[0069] Furthermore, rollers 405 (support members) are provided at the front ends (ends in the direction in which the paper feed cassette 410 is pulled out) of the sliding surfaces 403a of the pair of guide frames 403, respectively. The rollers 405 are rotating bodies that rotate so that the paper feed cassette 410 can move relatively in the front-to-rear direction with respect to the guide frames 403. The rollers 405 rotate around an axis that extends in the horizontal direction perpendicular to the front-to-rear direction. Therefore, the rail portions 412 come into contact with the rollers 405, thereby assisting the movement of the paper feed cassette 410 in the front-to-rear direction. Therefore, the rollers 405 make it easy to insert and pull out the paper feed cassette 410.

[0070] Although the sheet feeder main body 401 is configured such that the rollers 405 are provided at the front end of the guide frame 403, the location of the rollers 405 is not limited to this. For example, the rollers 405 may be rotatably provided on a member separate from the guide frame 403 at a position adjacent to the front end of the guide frame 403 in the front-rear direction.

[0071] As shown in FIG. 2 , a switching lever 409 is provided below the sheet supply unit 420, above the rear of the right-side guide frame 403. The switching lever 409 is a member for switching between a pressed state in which the separation roller 423 is pressed against the supply roller 422 and a released state in which this pressed state is released. The switching lever 409 is provided so as to be swingable horizontally. That is, when the sheet cassette 410 is inserted into the sheet feeder main body 401 and the sheet cassette 410 abuts against the switching lever 409, the switching lever 409 moves rearward from its initial position. In this way, when the switching lever 409 moves rearward, the separation roller 423 presses the supply roller 422. On the other hand, when the sheet cassette 410 is pulled out of the sheet feeder main body 401 and separated from the swinging member 424, the swinging member 424 moves forward and returns to its initial position. In this manner, when the swinging member 424 returns to the initial position, the pressure state of the separation roller 423 against the supply roller 422 is released.

[0072] 2, a size detection switch 408 that detects the size of the sheet P is provided on the rear wall 401b of the sheet feeding device main body 401. The size detection switch 408 has a plurality of detection portions that protrude forward from the rear wall 401b. The size detection switch 408 can detect the size of the sheet P when the sheet P abuts against these detection portions.

[0073] (Retraction unit) Next, the retraction unit 500 will be described with reference to Figures 7 and 8. Figures 7 and 8 are plan views showing the internal structure of the retraction unit 500 provided in the sheet feeding device main body 401 according to the present disclosure. Figure 7 shows a state in which the engagement portion 505 of the retraction unit 500 is positioned at the rearmost side, and Figure 8 shows a state in which the engagement portion 505 of the retraction unit 500 is positioned at the frontmost side. The operating range in which the engagement portion operates is a range in which the engagement portion shown in Figure 7 operates to the engagement portion shown in Figure 8, and will be described in detail later.

[0074] 7 and 8, retraction unit 500 is configured to include damper section 501, spring 502, and housing 503 that houses damper section 501 and spring 502. Damper section 501 is configured so that a piston (not shown) reciprocates in the front-to-rear direction within a case filled with fluid (e.g., oil). Damper section 501 is equipped with rod 504 that extends in the front-to-rear direction and protrudes from the front end of the case. Rod 504 extends in the front-to-rear direction, and when the end on the case side is defined as the base end and the end opposite the base end is defined as the tip, engagement section 505 is provided at the tip, and the base end is joined to the piston.

[0075] Spring 502 is, for example, a coil spring, and its rear end is fixed inside housing 503 and its front end is connected to the tip of rod 504. The tip of rod 504 is configured to move forward and backward in the front-to-rear direction relative to the case of damper section 501. Therefore, spring 502 fixed to the tip of rod 504 expands and contracts in response to the forward and backward movement of rod 504.

[0076] The engaging portion 505 includes a first contact portion 505a that contacts the protrusion 415 of the paper feed cassette 410 when the paper feed cassette 410 is inserted into the paper feed device main body 401, and a second contact portion 505b that contacts the protrusion 415 of the paper feed cassette 410 when the paper feed cassette 410 is pulled out from inside the paper feed device main body 401. The first contact portion 505a and the second contact portion 505b are provided to protrude from the left side of the housing 503.

[0077] Engagement portion 505 further includes first guide shaft 505c and second guide shaft 505d that engage with guide grooves 506 formed on the upper and lower surfaces of housing 503. First guide shaft 505c is provided on the front side of engagement portion 505, and second guide shaft 505d is provided on the rear side of engagement portion 505. First guide shaft 505c and second guide shaft 505d are configured to move along guide groove 506. Therefore, the movement of engagement portion 505 is regulated by guide groove 506.

[0078] Guide groove 506 is an approximately L-shaped slit that extends along the left side of housing 503 from approximately the middle position of housing 503 toward the front and bends toward the right near the front end of housing 503.

[0079] 7 and 8, when engaging portion 505 moves from the rear side to the front side, engaging portion 505 moves along the left side of housing 503. Then, first guide shaft 505c moves along guide groove 506 near the front end of housing 503 toward the right side of housing 503, and pulls second abutment portion 505b into housing 503. Then, first guide shaft 505c is locked at the end of guide groove 506.

[0080] As a result, the second contact portion 505b of the engaging portion 505 is accommodated in the housing 503 at the front end portion of the housing 503, and the engagement between the protrusion 415 of the paper feed cassette 410 and the engaging portion 505 is released.

[0081] Specifically, when paper feed cassette 410 is pulled out from inside paper feed device main body 401 to the outside, protrusion 415 of paper feed cassette 410 abuts and engages with second abutment portion 505b. Then, the force applied by the user to pull out paper feed cassette 410 moves engagement portion 505, which is engaged with protrusion 415, forward. At this time, the tip of rod 504 moves forward, and spring 502 expands forward.

[0082] When engagement portion 505 moves close to the tip of retraction unit 500, second contact portion 505b is housed in housing 503 as described above, and the engagement between protrusion 415 and second contact portion 505b is released. As a result, sheet feed cassette 410 moves forward away from retraction unit 500, and sheet feed cassette 410 is pulled out from inside sheet feed device main body 401 to the outside.

[0083] On the other hand, when inserting the paper feed cassette 410 into the paper feed device main body 401, the second abutment portion 505b of the retraction unit 500 is housed in the housing 503, and therefore the protrusion 415 of the paper feed cassette 410 abuts and engages with the first abutment portion 505a without being obstructed by the second abutment portion 505b. When the user exerts force to push the paper feed cassette 410, the protrusion 415 presses the first abutment portion 505a rearward, and this force releases the lock of the first guide shaft 505c.

[0084] When the first guide shaft 505c is released from the lock, the restoring force of the stretched spring 502 moves the engaging portion 505 from the front side to the rear side, i.e., in the insertion direction. As the engaging portion 505 moves, the second contact portion 505b presses the protrusion 415 in the insertion direction. The pressing force from the second contact portion 505b pushes the protrusion 415 in the insertion direction, and as a result, the sheet feed cassette 410 is drawn into the sheet feed device main body 401. In this way, the sheet feed cassette 410 is drawn into the sheet feed device main body 401 mainly by the restoring force of the spring 502.

[0085] Therefore, when the user pushes the sheet feed cassette 410 into the position where the protrusion 415 abuts the first abutment portion 505a, the sheet feed cassette 410 is then pulled into the sheet feed device main body 401 by the pull-in unit 500. This reduces the burden on the user when inserting the sheet feed cassette 410 into the sheet feed device main body 401.

[0086] When inserting the sheet feed cassette 410 into the sheet feeder main body 401, various loads exert forces in a direction that hinders movement of the sheet feed cassette 410. For example, such loads include the above-mentioned switching lever 409 or size detection switch 408. Furthermore, such loads include a coupling mechanism that couples with a lift-up shaft in a lift-up mechanism that raises and lowers the sheets P stored in the sheet feed cassette 410 to a predetermined height of the sheet feed opening.

[0087] As described above, the retraction unit 500 is configured to retract the sheet feed cassette 410 to the installation position by utilizing the restoring force of the spring 502. Therefore, the magnitude of the force with which the retraction unit 500 retracts the sheet feed cassette 410 decreases as the sheet feed cassette 410 approaches the installation position.

[0088] Therefore, in order to reliably move the paper feed cassette 410 to the installation position using the retraction unit 500, it is necessary to consider the magnitude of the force with which the retraction unit 500 retracts the paper feed cassette 410 and the effect of the load generated when the paper feed cassette 410 moves.

[0089] (Positional relationship between the first positioning portion, the second positioning portion, the engaging portion, and the operating area in which the engaging portion operates) FIG. 9 is a conceptual diagram of a plan view of the paper feed cassette as seen from above. To illustrate the positional relationship between the first positioning portion 413, the second positioning portion 414, the engagement portion 505 of the retraction unit 500, and the operating area in which the engagement portion 505 operates, FIG. 9 mainly shows these elements and illustrates them schematically. For convenience, the protrusion 415 that engages with the engagement portion 505 is omitted. Also, in FIG. 9, the engagement portion when the engagement portion 505 of the retraction unit 500 is positioned at the rearmost position is indicated by a solid line, and the engagement portion when the engagement portion 505 of the retraction unit 500 is positioned at the frontmost position is indicated by a dotted line. In other words, the engagement portion indicated by the solid line corresponds to the state shown in FIG. 7, and the engagement portion indicated by the dotted line corresponds to the state shown in FIG. 8. The operating area 505Y is the area in which the engagement portion shown in FIG. 7 operates to the engagement portion shown in FIG. 8. The operating region 505Y extends from the end face of the rear first contact portion 505a when positioned at the rearmost position to the end face of the front second contact portion 505b when positioned at the frontmost position.

[0090] As described above, as shown in Fig. 9, the first positioning portion 413, the second positioning portion 414, and the engaging portion 505 are provided on one side of the center Ox of the sheet feed cassette 410 in the width direction X (the left-right direction in Fig. 9) in a plan view of the sheet feed cassette 410 seen from above. In Fig. 9, the first positioning portion 413, the second positioning portion 414, and the engaging portion 505 are provided on the right side of the center Ox of the sheet feed cassette 410 in the width direction X.

[0091] 9, the first positioning portion 413, the second positioning portion 414, and the engaging portion 505 may be provided on the left side of the center Ox of the sheet feed cassette 410 in the width direction X. When the sheet P is shifted to the right side, it is preferable that the first positioning portion 413, the second positioning portion 414, and the engaging portion 505 are provided on the right side, as shown in FIG.

[0092] 9, the engaging portion 505 is provided between the first positioning portion 413 and the second positioning portion 414 in the width direction X in a plan view of the sheet feed cassette 410 seen from above. Further embodiments will be described below.

[0093] As shown in FIG. 9, the engaging portion 505 is preferably disposed within a rectangular region S having the first positioning portion 413 and the second positioning portion 414 as diagonal corners in a plan view. As shown in FIG. 9, the rectangular region S is formed by a corner formed by the distal end surface of the second positioning portion 414 and the left side surface (the side surface opposite the engaging portion) and a corner formed by the proximal end surface of the first positioning portion 413 and the right side surface (the side surface opposite the engaging portion), forming a rectangular shape with these corners as diagonal corners. In FIG. 9, the first positioning portion 413 and the second positioning portion 414 are shown as convex, but if the first positioning portion 413 and the second positioning portion 414 are holes, as shown in FIG. 10, the rectangular region S is formed by a corner formed by the proximal end surface of the hole of the second positioning portion 414 and the left side wall surface (the wall surface opposite the engaging portion) and a corner formed by the distal end surface of the first positioning portion 413 and the right side wall surface (the wall surface opposite the engaging portion), forming a rectangular shape with these corners as diagonal corners.

[0094] 9, the operating area 505Y in which the engaging portion 505 operates is preferably provided in front of the center Oy of the insertion direction of the sheet feed cassette 410 in a plan view of the sheet feed cassette 410 from above. This allows the sheet feed cassette to be pulled into the device position more stably and appropriately than if the operating area 505Y were provided behind the center Oy of the insertion direction of the sheet feed cassette 410.

[0095] 9, the first positioning portion 413, the second positioning portion 414, and the engaging portion 505 are preferably provided at a position where a straight line K connecting the first positioning portion 413 and the second positioning portion 414 intersects with an operating region 505Y (thick line in FIG. 9) in which the engaging portion 505 operates, in a plan view of the paper feed cassette 410 seen from above. In this way, the paper feed cassette can be more stably and appropriately pulled into the device position.

[0096] FIG. 11 is an image diagram of a rear view of the paper feed cassette as seen from the rear, and is a diagram in the height direction. It is also a rear view of FIG. 4. Similarly to FIG. 9, FIG. 11 is a schematic diagram. As shown in FIG. 11, the engagement portion 505 is preferably disposed within a rectangular area M, with the first positioning portion 413 and the second positioning portion 414 as diagonal corners, when viewed from the rear. As shown in FIG. 11, the rectangular area M is formed by a corner formed by the upper surface and left surface (the side opposite the engagement portion) of the second positioning portion 414, and a corner formed by the lower surface and right surface (the side opposite the engagement portion) of the first positioning portion 413, and has a rectangular shape with these corners as diagonal corners. In Figure 11, the first positioning portion 413 and the second positioning portion 414 are shown as convex, but if the first positioning portion 413 and the second positioning portion 414 are holes, the rectangular area M is composed of a corner formed by the upper wall surface and left wall surface (side wall surface opposite the engagement portion) of the second positioning portion 414, and a corner formed by the lower wall surface and right wall surface (side wall surface opposite the engagement portion) of the first positioning portion 413, and is a rectangle with these corners as diagonal corners.

[0097] 11, the engaging portion 505 may be disposed so as to be located diagonally from a straight line L connecting the first positioning portion 413 and the second positioning portion 414 in rear view. This allows the paper feed cassette to be more stably and appropriately pulled into the device position. The straight line L may be a diagonal between the first positioning portion 413 and the second positioning portion 414, and the first positioning portion 413 and the second positioning portion 414 may be at different heights, or the first positioning portion 413 and the second positioning portion 414 may be at the same height rather than being at a diagonal between them. The straight line L passes through the center of the engaging portion 505.

[0098] (Rail section) The configuration of the rail portion 412 provided on the fourth cassette wall portion 410e of the paper feed cassette 410 included in the paper feed device 400 according to this embodiment will be described with reference to FIGS.

[0099] Fig. 12 is a partially enlarged view of region A of sheet cassette 410 shown in Fig. 4. Fig. 13 is a diagram schematically showing the height difference of rail portion 412 of sheet cassette 410 shown in Fig. 12. Fig. 14 is a graph showing the relationship between the retraction force of retraction unit 500 and the force required to retract sheet cassette 410 to the installation position in sheet feeder 400 according to the embodiment. Fig. 15 is a diagram schematically showing the principle of generation of the force that retracts sheet feed cassette 410 provided in sheet feeder 400 according to the embodiment to the installation position.

[0100] For ease of explanation, first cassette wall 410b and handle 417 are omitted from Fig. 12. In Fig. 13, the horizontal axis represents the horizontal distance (mm) starting from the front end of rail 412, and the vertical axis represents the vertical distance (mm) from bottom 410a of sheet cassette 410 to contact surface 412a of rail 412.

[0101] In FIG. 14, the solid line indicates the change in the retraction force (first force) of the retraction unit 500 of the sheet feeder 400, and the dashed line indicates the change in the force (second force) required to retract the sheet feeder cassette 410 to the installation position. The horizontal axis of FIG. 14 indicates the distance between the sheet feeder cassette 410 and the installation position of the sheet feeder cassette 410 in the sheet feeder 400. In other words, the position of the second cassette wall 410c when the sheet feeder cassette 410 is in the installation position is set to 0 mm. The horizontal axis indicates the distance between the second cassette wall 410c and the installation position. The vertical axis indicates the magnitude of the first force and the second force. In FIG. 14, the change in the first force and the second force is shown when the distance between the second cassette wall 410c and the installation position ranges from 0 mm to 50 mm. In addition, the graph showing the change in the second force in FIG. 14 is for a state in which 500 A3 size sheets P are stored in the sheet cassette 410 (storage The measurements were taken using the largest possible paper size and the largest number of sheets.

[0102] In the present disclosure, when the paper feed cassette 410 is inserted into the paper feed device main body 401 and the rear end of the paper feed cassette 410 is pushed to a position 50 mm forward (in the direction of withdrawal) from the installation position, the engagement portion 505 of the retraction unit 500 engages with the protrusion 415 of the paper feed cassette 410, and the retraction unit 500 begins to retract the paper feed cassette 410.

[0103] 12 and 12B, rail portion 412 has a contact surface 412a that contacts rollers 405 provided on guide frame 403. This contact surface 412a includes a first inclined portion 412a1, a second inclined portion 412a2, and a reference horizontal portion 412a3. First inclined portion 412a1 and second inclined portion 412a2 are provided within a region (first range) where contact surface 412a of rail portion 412 contacts rollers 405 while retracting unit 500 retracts sheet feed cassette 410 in the insertion direction.

[0104] The first inclined portion 412a1 is an inclined surface that is inclined downward in the front-rear direction toward the insertion direction of the sheet feed cassette 410.

[0105] In the present disclosure, as shown in FIG. 13 , the first inclined portion 412a1 is provided on the rail portion 412 so as to be inclined 3.5 mm lower than the reference height from the front end to a position 10 mm away from the rear end. The reference height is the height of the rail portion 412 when the paper feed cassette 410 is in the installation position, in other words, the height of the reference horizontal portion 412a3. The paper feed cassette 410 is in the installation position when the first positioning portion 413 is inserted into the first positioning receiving portion 406 and the second positioning portion 414 is inserted into the second positioning receiving portion 407, the paper feed cassette 410 is aligned within the paper feeder main body 401, and the paper feed cassette 410 is ready to feed paper. The height of the front end of the rail portion 412 coincides with this reference height. In addition, in the sheet feeding device 400 according to the embodiment, the height difference of the first inclined portion 412a1 is set to 3.5 mm, but this is not limited to this. For example, it can be set appropriately between 1.5 mm and 4.5 mm.

[0106] The second inclined portion 412a2 is an inclined surface that slopes back to the reference height between a position 10 mm rearward from the front end of the rail portion 412 and a position 22 mm further away (a position 32 mm rearward from the front end) in the front-rear direction. In other words, the second inclined portion 412a2 is connected to the end of the first inclined portion 412a1 on the insertion direction side, and slopes upward in the insertion direction.

[0107] The second inclined portion 412a2 is an inclination that compensates for the difference in height between the first inclined portion 412a1 and the reference horizontal portion 412a3 (reference height) in order to provide the first inclined portion 412a1 in the rail portion 412. However, if the lowest position of the first inclined portion 412a1 is the reference height, the second inclined portion 412a2 can be omitted.

[0108] Thus, contact surface 412a of rail portion 412 includes first inclined portion 412a1, second inclined portion 412a2, and reference horizontal portion 412a3. When roller 405 of guide frame 403 contacts first inclined portion 412a1 of rail portion 412, a force that retracts paper feed cassette 410 can be generated by the weight of paper feed cassette 410, as shown in FIG.

[0109] That is, when the first inclined portion 412a1 of the rail portion 412 comes into contact with the roller 405, the following are generated at the contact position: a load (vertical, downward force F1) exerted by the sheet feed cassette 410, a force (front-rear, insertion direction force F2) that pulls the sheet feed cassette 410 toward the installation position, and a force (force F3) that moves the sheet feed cassette 410 toward the insertion direction due to the contact of the first inclined portion 412a1 with the roller 405. At this time, force F3 corresponds to the resultant force of forces F1 and F2.

[0110] Therefore, at the position where the first inclined portion 412a1 of the rail portion 412 and the roller 405 of the guide frame 403 come into contact with each other, a force F2 can be generated that draws the sheet feed cassette 410 toward the mounting position.

[0111] Incidentally, in sheet feeding device 400, when sheet feeding cassette 410 is in the installation position, the front end of rail portion 412 is aligned with the front end of guide frame 403. As described above, first inclined portion 412a1 is provided in a range that is 10 mm rearward from the front end of rail portion 412.

[0112] Therefore, in the range where the distance between paper feed cassette 410 and the installation position is 10 mm or less, first inclined portion 412a1 comes into contact with rollers 405 of guide frame 403. Therefore, in the range where the first force is smaller than the second force, the pulling force generated by first inclined portion 412a1 can be utilized.

[0113] Therefore, as shown in FIG. 14, in the paper feeding device 400 according to the embodiment, even when the distance between the paper feeding cassette 410 and the mounting position is within a range of 10 mm or less, the force (first force) to retract the paper feeding cassette 410 can be prevented from becoming smaller than the force (second force) required to move the paper feeding cassette 410 to the mounting position.

[0114] When paper feed cassette 410 is pulled out from paper feed device main body 401, first inclined portion 412a1 of rail portion 412 moves from bottom to top while abutting roller 405, generating a force that inhibits the force acting in the pulling direction. However, when the distance between the installation position and paper feed cassette 410 is within a range of 10 mm, the tensile force of spring 502 of retraction unit 500 is small. Therefore, when paper feed cassette 410 is pulled out from paper feed device main body 401, the force acting in the pulling direction can be suppressed from increasing when the distance between the installation position and paper feed cassette 410 is within a range of 10 mm.

[0115] In addition, it is preferable that the starting point of the second inclined portion 412a2 in the rail portion 412, i.e., the junction point between the reference horizontal portion 412a3 and the second inclined portion 412a2, and the starting point of the first inclined portion 412a1, i.e., the junction point between the second inclined portion 412a2 and the first inclined portion 412a1, be within the range where the paper feed cassette 410 abuts against the roller 405 while receiving the first force from the retraction unit 500, and at a position where no influence from other loads occurs.

[0116] Furthermore, the rail portion 412, whose contact surface 412a includes the first inclined portion 412a1 and the second inclined portion 412a2, is configured to be provided on the fourth cassette wall portion 410e, which is closer to the center of gravity of the sheet feed cassette 410 in the left-right direction when sheets P are placed thereon, out of the third cassette wall portion 410d and the fourth cassette wall portion 410e extending in the front-rear direction. Furthermore, the pull-in unit 500 is configured to be provided on the right guide frame 403, which is provided with a roller 405 that contacts the rail portion 412 provided on the fourth cassette wall portion 410e.

[0117] In this way, rail portion 412 including abutment surface 412a is provided on fourth cassette wall portion 410e on the side closer to the center of gravity of sheet feed cassette 410 in the left-right direction. Also, pull-in unit 500 is provided on right guide frame 403, which is provided with rollers 405 that abut against rail portion 412. Therefore, when sheet feed cassette 410 is inserted into sheet feeder main body 401, sheet feed cassette 410 can be guided smoothly into sheet feeder main body 401 without getting stuck.

[0118] As described above, the paper feed device and image forming apparatus according to the present disclosure can appropriately retract the paper feed cassette to the device position.

[0119] Although the embodiments and examples of the present disclosure have been described in detail above, it will be readily apparent to those skilled in the art that many modifications are possible without substantially departing from the novel features and effects of the present disclosure. Therefore, all such modifications are intended to be included within the scope of the present disclosure.

[0120] For example, a term that is described at least once in the specification or drawings together with a different term having a broader or equivalent meaning can be replaced with that different term anywhere in the specification or drawings. Furthermore, the configurations and operations of the paper feed device and image forming device are not limited to those described in the embodiments and examples of the present disclosure, and various modifications are possible. [Explanation of symbols]

[0121] 100 Image forming device 102 Image forming unit 400 Paper feeder 401 Paper feeder main body 401a Paper feeder bottom 401b Rear wall 401c Left side wall 401d Right side wall 403 Guide Frame 405 Coro 406 First positioning part 406a Uneven part 407 Second positioning part 408 Size detection switch 409 Lever 410 Paper cassette 410a bottom 410b First cassette wall 410c Second cassette wall 410d Third cassette wall 410e Fourth cassette wall 411a 1st guide clip 411b 2nd guide clip 412 Rail section 412a Contact surface 412a1 1st slope part 412a2 2nd slope part 412a3 Reference horizontal part 413 First positioning part 414 Second positioning part 415 Protrusion 420 Sheet supply unit 500 Retraction Unit 501 Damper section 502 Spring 503 Case 504 Rod 505 Engagement part 505a 1st contact part 505b 2nd contact part 505c First guide shaft 505d Second guide shaft 505Y (Engagement part) operating area 506 Guide groove K: A straight line connecting the first positioning part and the second positioning part (in plan view) L (in rear view) A straight line connecting the first positioning part and the second positioning part M (in rear view) A rectangular area with the first positioning portion and the second positioning portion as diagonal corners Ox (Paper cassette) center in width direction Oy (Paper cassette) center in insertion direction P-sheet S (in plan view) A rectangular area with the first positioning part and the second positioning part as diagonal corners W1 sheet transport path W2 Reversing sheet transport path X (width direction of the paper cassette) X1: Distance between the first positioning part and the second positioning part in the width direction (when viewed from above) Y (Paper cassette) insertion direction Y1: Distance between the first and second positioning parts in the insertion direction (in plan view) Z (Paper cassette) height direction

Claims

1. A paper feeder including a paper feeder main body, a paper feed cassette that can be inserted into and pulled out of the paper feeder main body, and a pull-in unit that pulls the paper feed cassette into the paper feeder main body, The paper feed cassette is a rectangular bottom portion for placing a sheet; a cassette wall portion erected along the outer periphery of the bottom portion; a first positioning portion and a second positioning portion provided on the cassette wall portion on the side where the cassette is inserted into the paper feed device main body, for positioning the paper feed cassette in the paper feed device; a protrusion that engages with an engagement portion of the retraction unit; Equipped with the first positioning portion, the second positioning portion, and the protrusion are provided on one side of the center in a width direction perpendicular to an insertion direction of the sheet feed cassette in a plan view of the sheet feed cassette seen from above, the protrusion is provided between the first positioning portion and the second positioning portion in the width direction in a plan view of the sheet feed cassette seen from above, the paper feeder main body includes a first positioned portion that fits into the first positioning portion and a second positioned portion that fits into the second positioning portion; In the pair of the first positioning portion and the first positioned portion, and the pair of the second positioning portion and the second positioned portion, one is a convex portion and the other is a hole, the engaging portion engages with the protrusion when the sheet feed cassette is inserted or pulled out, and moves forward in a pulling-out direction and backward in an inserting direction; A paper feeding device characterized in that the operating area in which the engagement portion operates is located forward of the center in the insertion direction when viewed from above in a plan view of the paper feeding cassette when the paper feeding cassette is inserted and capable of feeding paper stored in the paper feeding cassette.

2. 2. The paper feeding device according to claim 1, wherein the first positioning portion and the second positioning portion are provided at different positions in the width direction of the paper feeding cassette.

3. 3. The paper feed device according to claim 1, wherein the protrusion is provided within a rectangular area having the first positioning portion and the second positioning portion as diagonal corners in a plan view of the paper feed cassette from above.

4. The paper feeding device according to any one of claims 1 to 3, characterized in that the first positioning portion and the second positioning portion are provided at the same height position or at different height positions in the height direction of the paper feeding cassette.

5. A paper feeding device described in any one of claims 1 to 4, characterized in that, when viewed in a plan view from the rear of the paper feeding cassette, the protrusion portion is arranged within a rectangular area with the first positioning portion and the second positioning portion as diagonal corners.

6. A paper feeding device described in any one of claims 1 to 5, characterized in that the protrusion portion is arranged on a straight line connecting the first positioning portion and the second positioning portion when viewed in a plan view from the rear of the paper feeding cassette.

7. 7. The paper feed device according to claim 1, wherein the protrusion is provided forward of the center in the insertion direction in a plan view of the paper feed cassette seen from above.

8. A paper feeding device as described in any one of claims 1 to 7, characterized in that, in a plan view of the paper feed cassette from above when the paper feed cassette is inserted and capable of feeding paper stored in the paper feed cassette, the engagement portion is located at a position where a straight line connecting the first positioning portion and the second positioning portion intersects with the operating area in which the engagement portion operates.

9. A paper feeding device described in any one of claims 1 to 8, characterized in that the distance between the first positioning portion and the second positioning portion in the width direction of the paper feeding cassette is smaller than the distance between the first positioning portion and the second positioning portion in the insertion direction of the paper feeding cassette.

10. The protrusion is provided on the outer side of the cassette wall in one width direction perpendicular to the paper feed cassette insertion direction, 10. The paper feed device according to claim 1, wherein the pull-in unit is disposed in the one direction relative to the paper feed cassette when the paper feed cassette is inserted.

11. 11. The paper feeding device according to claim 1, wherein the first positioning portion and the second positioning portion have different sizes or depths of the convex shapes or holes.

12. a paper feeder according to any one of claims 1 to 11; an image forming unit that forms an image on the sheet sent from the paper feeding device; An image forming apparatus comprising:

Images