Sheet feeding device and image forming apparatus

Abstract

To provide a sheet feeder capable of stably feeding sheets various in size and nonuniform in thickness.SOLUTION: A sheet feeder comprises a loading unit on which sheets are placed, a feed member that is provided above the loading unit and feeds an uppermost one of the sheets placed on the loading unit in a sheet-feed direction, and a rear-end regulating member that is provided movably in the sheet-feed direction and regulates the position of a rear end in the sheet-feed direction of the sheets placed on the loading unit. The rear-end regulating member has a support portion to support an underside of the sheet placed on the loading unit, in which the support portion has a convex shape protruded upward at a central portion in a sheet-width direction orthogonal to the sheet-feed direction and a vertical direction as compared with both ends in the sheet-width direction.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a sheet feeding device that feeds sheets and an image forming apparatus that forms images on sheets. [Background technology]

[0002] Image forming devices such as printers and copiers are equipped with a sheet feeding device that feeds sheets used as recording materials one by one toward an image forming unit. Patent Document 1 describes how sheets of uneven thickness, such as envelopes, can be handled by attaching an attachment equipped with a swing plate that swings about an axis parallel to the sheet feeding direction to the tray of the sheet feeding device. According to this, when the tray is raised with a stack of envelopes loaded on the swing plate and the top envelope comes into contact with the feed roller, the swing plate swings due to the force received from the feed roller via the stack of envelopes, thereby reducing the tilt of the top envelope. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-129044 Summary of the Invention [Problem to be solved by the invention]

[0004] However, with the configuration of the above document, depending on the size of the sheet, the rear end of the sheet (the upstream end of the sheet in the sheet feeding direction) is located at a position away from the swing plate, so the skew near the rear end of the top sheet may not be sufficiently reduced. If the skew of the top sheet is large, the contact state of the feed roller with the top sheet becomes unstable, which may result in feeding problems.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a sheet feeding device that can more stably feed sheets of various sizes and uneven thicknesses. [Means for solving the problem]

[0006] According to one aspect of the present invention, there is provided a sheet feeding device including a stacking section on which sheets are stacked, a feeding member provided above the stacking section and configured to feed the top sheet of the sheets stacked on the stacking section in a sheet feeding direction, and a trailing edge regulating member provided movable in the sheet feeding direction and configured to regulate the position of the trailing edge of the sheets stacked on the stacking section in the sheet feeding direction, the trailing edge regulating member having a support portion for supporting the underside of the sheets stacked on the stacking section, the support portion being configured to regulate the position of the trailing edge of the sheets stacked on the stacking section in a sheet width direction perpendicular to the sheet feeding direction and the up-down direction. of the support The center portion is of the support The sheet feeding device is characterized by having a convex shape that protrudes upward compared to both end portions. [Effects of the Invention]

[0007] According to the present invention, sheets of various sizes and uneven thicknesses can be fed more stably. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram of an image forming apparatus according to a first embodiment. [Figure 2] 1A and 1B are perspective views of an image forming apparatus according to a first embodiment. [Figure 3] 1A and 1B are a top view and a rear view of a feeding cassette according to a first embodiment. [Figure 4] 1A and 1B are an exploded view and a perspective view of a feeding cassette according to a first embodiment; [Figure 5] 3A and 3B are diagrams showing how a stack of envelopes of different sizes is set in the feeding cassette according to the first embodiment. [Figure 6] 5A and 5B are cross-sectional views for explaining a feeding operation according to the first embodiment. [Figure 7] 5A to 5C are schematic diagrams for explaining the operation of the configuration according to the first embodiment. [Figure 8] 10A is a perspective view of a feeding cassette according to a second embodiment, and FIG. 10B is a view showing some of its components. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0010] First Embodiment A first embodiment of the present disclosure will be described with reference to Figures 1 to 7. Figure 1 is a schematic diagram showing the overall configuration of a full-color laser beam printer (hereinafter referred to as printer 201) which is an example of an image forming apparatus equipped with a sheet feeding device.

[0011] The printer 201 includes a printer main body 201A as the main body of the image forming apparatus, an image forming section 201B, a fixing section 220, and a sheet feeding device 230, which are arranged within the printer main body 201A.

[0012] The image forming unit 201B has a tandem intermediate transfer configuration, that is, the image forming unit 201B has four process cartridges (process units, image forming stations) 211 that form toner images of four colors, yellow, magenta, cyan, and black, and an intermediate transfer unit 201C.

[0013] Each process cartridge 211 has a photosensitive drum 212 as an image carrier (electrophotographic photosensitive member), a charger 213 as charging means, a developing unit 214 as developing means, and a cleaning blade 215 as cleaning means. The developing unit 214 has a container that contains a developer including toner, and a developing roller (developer carrier) that carries the developer and rotates to supply the toner to the photosensitive drum 212. In addition, a laser scanner 210 as exposure means is disposed below the four process cartridges 211.

[0014] The intermediate transfer unit 201C includes an intermediate transfer belt 216 as an intermediate transfer body, a drive roller 216a, a tension roller 216b, and four primary transfer rollers 219. The intermediate transfer belt 216 is wound (tensioned) around the drive roller 216a and the tension roller 216b, and is conveyed by the rotation of the drive roller 216a while coming into contact with the photosensitive drums 212 of the process cartridges 211 in order. The four primary transfer rollers 219 are provided in the internal space of the intermediate transfer belt 216, and are positioned so as to face the photosensitive drums 212 with the intermediate transfer belt 216 sandwiched therebetween.

[0015] A secondary transfer roller 217 is disposed opposite the drive roller 216a across the intermediate transfer belt 216 as a transfer means for transferring the toner image formed in the image forming unit 201B onto a sheet S as a recording material (recording medium). A nip between the secondary transfer roller 217 and the intermediate transfer belt 216 forms a secondary transfer unit where the toner image is transferred onto the sheet S.

[0016] Fixing unit 220 is disposed downstream of the secondary transfer unit in the sheet conveying direction. Fixing unit 220 has a pair of rotating bodies, each composed of a roller or a belt, that sandwich and convey sheet S, and a heating means that heats the toner image on sheet S. The heating means may be a halogen lamp that emits radiant heat, a ceramic heater that heats rollers or belts by non-radiant heat, or an induction heating mechanism that heats rollers or belts by electromagnetic induction.

[0017] Further downstream of the fixing unit 220, a pair of discharge rollers 225 is disposed as a discharge means for discharging the sheet S on which an image has been formed from the printer main body 201A. Also, on the upper surface of the printer main body 201A, a discharge tray 223 on which the sheet S on which an image has been formed is stacked is provided.

[0018] The sheet feeding device 230 includes a feeding cassette 233, a feeding roller 1 (pickup roller), a conveying roller 2 (feed roller), and a separation roller 3. The sheet feeding device 230 is configured to feed the sheets S one by one toward the image forming unit 201B. , Shi A variety of sheet materials of different sizes and materials can be used as the sheet S, including paper such as plain paper and cardboard, surface-treated sheet materials such as plastic film, cloth, and coated paper, and sheet materials of special shapes such as index paper. In particular, the sheet feeding device 230 of this embodiment can feed sheets S of non-uniform thickness, such as envelopes.

[0019] The feeding cassette 233 is detachably attached to the printer main body 201A. The feeding cassette 233 is a storage case (storage section) that stores sheets S. The feeding cassette 233 has a lifter tray 8 on which the sheets S are stacked. The lifter tray 8 is configured to be able to move up and down as described below.

[0020] The feed roller 1 is provided above the lifter tray 8. The feed roller 1 functions as a feed member that feeds the top sheet of the sheets S stacked in the feed cassette 233. Note that instead of the feed roller 1, a belt member, for example, may be used as the feed member.

[0021] The conveying roller 2 and the separation roller 3 constitute a separation roller pair as a conveying unit that separates and conveys the sheets S fed by the feed roller 1 one by one. The conveying roller 2 rotates in the sheet feeding direction of the feed roller 1. The separation roller 3 is pressed against the conveying roller 2 and separates the sheets S at a separation section 232, which is a nip between the conveying roller 2 and the separation roller 3. The separation roller 3 may be, for example, a roller member connected via a torque limiter to a shaft member fixed to the frame of the feed cassette 233. The separation roller 3 is an example of a separating member that separates sheets, and may be, for example, a roller member to which a driving force (retard drive) in a direction opposite to the rotation of the conveying roller 2 is input via a torque limiter, or a pad-shaped elastic member (rubber pad). The feed roller 1, conveying roller 2, and separation roller 3 are each a roller whose outer periphery is wrapped with a material with a high friction coefficient, such as rubber.

[0022] A pair of pull-out rollers 239 is disposed downstream of the pair of separation rollers in the sheet conveying direction. A pair of registration rollers 240 is disposed downstream of the pair of pull-out rollers 239 and upstream of the secondary transfer portion.

[0023] (Image formation operation) An outline of the image forming operation by the printer 201 will be described below. First, when an image forming instruction (print job) is input to the printer 201 from an external computer, the control unit of the printer 201 starts the image forming operation.

[0024] When the image forming operation starts, the image forming unit 201B starts driving the photosensitive drum 212 and intermediate transfer belt 216, and the charger 213 uniformly charges the surface of the photosensitive drum 212 to a predetermined polarity and potential. The laser scanner 210 irradiates the photosensitive drum 212 with laser light modulated in accordance with a video signal generated based on image information provided when a print job is input. This exposes the photosensitive drum 212, and an electrostatic latent image corresponding to a component image of each color is formed on the surface of the photosensitive drum 212. The developer 214 develops the electrostatic latent image using a developer containing toner of each color. As a result, a monochromatic toner image of each color is formed on the surface of the photosensitive drum 212.

[0025] The single-color toner images formed on the photosensitive drums 212 in the process cartridges 211 are sequentially transferred (primary transfer) onto the intermediate transfer belt 216 by the primary transfer rollers 219. At this time, the single-color toner images of each color are superimposed on each other on the intermediate transfer belt 216, thereby forming a full-color toner image on the intermediate transfer belt 216. The full-color toner image is carried on the intermediate transfer belt 216 and transported toward a secondary transfer unit.

[0026] In parallel with the toner image formation process described above, the sheet feeding device 230 feeds the sheets S one by one. First, the lifter tray 8 rises, causing the top sheet of the sheets S in the feed cassette 233 to come into contact with the feed roller 1. The feed roller 1 is driven to rotate by a motor (not shown), and sends out the sheet S in the sheet feeding direction by friction. The sheets S sent out by the feed roller 1 are separated into single sheets as they pass through the separation section 232. Specifically, when only one sheet S enters the separation section 232, the separation roller 3 rotates following the sheet S, allowing the sheet S to pass through. On the other hand, when multiple sheets S enter the separation section 232, the separation roller 3 rotates in the direction opposite to the sheet feeding direction while sliding the sheets against each other, preventing sheets S other than the topmost sheet S from passing through the separation section 232.

[0027] The sheet S that has passed through the separation unit 232 is conveyed to a registration roller pair 240 via a pull-out roller pair 239. The registration roller pair 240 corrects any skew of the sheet S, and then conveys the sheet S to the secondary transfer unit in time with the arrival of the toner image carried and conveyed by the intermediate transfer belt 216 at the secondary transfer unit. Then, when the sheet S passes through the secondary transfer unit, a predetermined transfer voltage is applied to the secondary transfer roller 217, so that the toner image is transferred from the intermediate transfer belt 216 to the sheet S.

[0028] The sheet S onto which the toner image has been transferred is transported to the fixing unit 220. The fixing unit 220 heats and pressurizes the toner image on the sheet S while transporting the sheet S, thereby fixing the toner image to the sheet S. After passing through the fixing unit 220, the sheet S is discharged by a pair of discharge rollers 225 and is stacked on a discharge tray 223 as a product.

[0029] (feed cassette) The configuration of the feed cassette 233 will now be described. Figures 2(a) and 2(b) are perspective views of the printer 201 viewed from diagonally above. Figure 2(a) shows a state in which the feed cassette 233 is stored (attached) in the printer main body 201A, and Figure 2(b) shows a state in which the feed cassette 233 is pulled out from the printer main body 201A.

[0030] In the following explanation and drawings, the vertical direction (direction of gravity) when the printer 201 is installed on a horizontal surface is referred to as the up-down direction, and the upward vertical direction is referred to as the z direction. Of the directions perpendicular to the z direction, the direction in which the feed cassette 233 is attached to or detached from the printer main body 201A is referred to as the front-to-back direction of the printer 201, and the direction from front to rear is referred to as the y direction. The direction perpendicular to the z direction and the y direction is referred to as the left-to-right direction of the printer 201, and the direction from left to right is referred to as the x direction. Furthermore, the positional relationship between the feed cassette 233 and its components will be described based on the state in which the feed cassette 233 is attached to the printer main body 201A.

[0031] As shown in Fig. 2(a), the feed cassette 233 is exposed on the front side of the printer main body 201A. A handle 233a (grip) for operating the feed cassette 233 is provided on the front side of the feed cassette 233. By gripping the handle 233a and operating it in the y1 direction, which is approximately parallel to the y axis, the user can pull out the feed cassette 233 from the printer main body 201A as shown in Fig. 2(b), or install the feed cassette 233 into the printer main body 201A as shown in Fig. 2(a).

[0032] Slide rails 9 extending in the front-to-rear direction are arranged on the left and right side surfaces of the feed cassette 233. Although only the slide rail 9 on one side is shown in FIG. 2(b), a similar slide rail 9 is arranged on the other side (see FIG. 3(a)). A guide shape that guides the slide rail 9 is provided in the printer main body 201A, and the slide rail 9, which serves as a guided portion, is guided by the guide shape, thereby restricting the movement direction of the feed cassette 233 to the y1 direction.

[0033] As shown in FIG. 2B, the feeding cassette 233 is provided with a pair of side end regulating members 10 and 11 and a trailing end regulating member 14.

[0034] The configuration of the feed cassette 233 will be further described with reference to Figures 3(a) and 3(b). Figure 3(a) is a top view of the feed cassette 233, and Figure 3(b) is a rear view of the feed cassette 233 as seen from the rear.

[0035] As shown in Fig. 3(a), sheets stored in the feeding cassette 233 are fed in a sheet feeding direction Df that is substantially parallel to the x-axis when viewed from above. Hereinafter, the downstream end of a sheet in the sheet feeding direction Df will be referred to as the "leading edge" of the sheet, and the upstream end of a sheet in the sheet feeding direction Df will be referred to as the "trailing edge" of the sheet. Furthermore, the direction (substantially parallel to the y-axis) that is perpendicular to both the sheet feeding direction Df and the up-down direction (z direction) will be referred to as the sheet width direction Dw, and the end of the sheet in the sheet width direction Dw will be referred to as the "side edge" of the sheet.

[0036] As shown in Figure 3(a), the feeding cassette 233 of this embodiment comprises a cassette body 233A, a lifter tray 8, a lifter arm 17, a pair of side end regulating members 10, 11, a rear end regulating member 14, a slide rail 9, and a separation roller 3.

[0037] The cassette body 233A is a substantially rectangular parallelepiped frame with an open upper side. The lifter tray 8 has a tray body 8A supported so as to be swingable about a swing shaft 233b (boss portion) provided on the cassette body 233A, and a tray attachment 18 (described later) detachably attached to the tray body 8A. The tray body 8A can hold sheets even when the tray attachment 18 is removed. The lifter tray 8 is an example of a lifting member that can rise and fall relative to the bottom 16 of the feed cassette 233, and instead of being configured to swing about the swing shaft 233b, it may be configured to move up and down while maintaining a substantially horizontal attitude.

[0038] The lower surfaces of the sheets stored in the feeding cassette 233 are supported by the lifter tray 8 and the bottom 16 of the cassette body 233A. That is, the lifter tray 8 (lifting member) and the bottom 16 of the cassette body 233A form a stacking portion on which the sheets are stacked in the feeding cassette 233 (storage cabinet).

[0039] The lifter arm 17 is disposed between the tray body 8A of the lifter tray 8 and the bottom 16 of the cassette body 233A, and rotates by a driving force supplied from a motor in the printer body 201A, thereby raising and lowering the lifter tray 8. As shown in FIG. 3(b), a lifter gear 15 (input gear) is disposed on the rear side of the feed cassette 233 for receiving driving force from a driving gear (output gear) in the printer body 201A and transmitting the driving force to the lifter arm 17. The lifter arm 17 rotates integrally with the lifter gear 15 around a common shaft. Note that the mechanism for raising and lowering the lifter tray 8 (lifting member) is not limited to a lifter arm. For example, the lifter tray 8 may be raised and lowered by winding and unwinding a wire suspending the lifter tray 8 using the driving force of a motor.

[0040] As shown in FIG. 3(a), the side edge regulating members 10, 11 (side fences, side guides) are supported on the bottom 16 (bottom plate) of the cassette main body 233A. The side edge regulating members 10, 11 are arranged facing each other in the front-to-rear direction and are configured to be slidable (movable, position adjustable) relative to the cassette main body 233A in the y2 direction, which is approximately parallel to the y axis. The side edge regulating members 10, 11 each have regulating surfaces 24a, 25a (contact surface, second contact surface) that extend approximately perpendicular to the y axis. The side edge regulating members 10, 11 are positioned according to the size of the sheet, so that the regulating surfaces 24a, 25a come into contact with the side edges of the sheet and regulate the position of the side edges of the sheet.

[0041] The side edge regulating members 10 and 11 are configured to move in conjunction with each other, for example, by a rack-and-pinion mechanism. As a result, the side edge regulating members 10 and 11 move while maintaining a symmetrical positional relationship with respect to the conveying center y0 in the sheet width direction Dw. The conveying center y0 is the center position in the sheet width direction Dw of the contact area where the feed roller 1 comes into contact with the sheet on the lifter tray 8. Note that the lifter tray 8 is provided with a notch (recess) in which part of the side edge of the tray main body 8A in the sheet width direction Dw is cut out toward the conveying center y0 to allow movement of the side edge regulating members 10 and 11.

[0042] The trailing edge regulating member 14 (rearing edge fence, rearing edge guide) is supported on the bottom 16 of the cassette body 233A. The trailing edge regulating member 14 is configured to be slidable (movable, position adjustable) relative to the cassette body 233A in the x1 direction, which is approximately parallel to the x-axis. The trailing edge regulating member 14 has a regulating surface 20a (contact surface, first contact surface) that extends approximately perpendicular to the x-axis. The trailing edge regulating member 14 is positioned according to the size of the sheet so that the regulating surface 20a contacts the trailing edge of the sheet and regulates the position of the trailing edge of the sheet. Note that the lifter tray 8 has a notch (recess) cut out toward the downstream side of the sheet feeding direction Df in the center of the upstream end of the tray body 8A in the sheet feeding direction Df to allow movement of the trailing edge regulating member 14.

[0043] The side end regulating members 10, 11 and the trailing end regulating member 14 of this embodiment are formed by attaching attachments (24, 25, 20) to main bodies 10A, 11A, 14A that themselves function as side end regulating members or trailing end regulating members. The side end attachments 24, 25 are attachments that are detachably attached to the main bodies 10A, 11A of the side end regulating members 10, 11, respectively. The trailing end attachment 20 is an attachment that is detachably attached to the main body 14A of the trailing end regulating member 14. The detailed configurations of the main bodies 10A, 11A, 14A and the attachments (24, 25, 20) will be described later.

[0044] The main bodies 10A, 11A, and 14A of the side edge regulating members 10 and 11 and the trailing edge regulating member 14 can regulate the position of a sheet even when the attachments (24, 25, and 20) are removed, respectively. That is, as shown in FIGS. 3A and 4A, the main bodies 10A and 11A of the side edge regulating members 10 and 11 each have regulating surfaces 10b and 11b (sheet contact surfaces) that extend substantially perpendicular to the y-axis. The main body 14A of the trailing edge regulating member 14 also has a regulating surface 14b (sheet contact surface) that extends substantially perpendicular to the x-axis. Therefore, by positioning the main bodies 10A, 11A, and 14A of the side edge regulating members 10 and 11 and the trailing edge regulating member 14 according to the sheet size, the regulating surfaces 10b, 11b, and 14b can regulate the positions of the side edges and trailing edges of the sheet.

[0045] The regulating surfaces 24a, 25a of the side end attachments 24, 25 attached to the main bodies 10A, 11A of the side end regulating members 10, 11 are located inside (closer to the conveying center y0) in the sheet width direction Dw than the regulating surfaces 10b, 11b of the main bodies 10A, 11A. The regulating surface 20a of the rear end attachment 20 attached to the main body 14A of the rear end regulating member 14 is located downstream in the sheet feeding direction Df than the regulating surface 14b of the main body 14A. Therefore, with the attachments (24, 25, 20) attached, sheets that are smaller in size in the sheet width direction Dw or the sheet feeding direction Df can be loaded in the feed cassette 233 compared to the state before the attachments are attached.

[0046] (Envelope attachment) The tray attachment 18, the rear end attachment 20, and the side end attachments 24 and 25 will be described in detail. Fig. 4(a) is an exploded view showing how the tray attachment 18, the rear end attachment 20, and the side end attachments 24 and 25 are attached to the feeding cassette 233. Fig. 4(b) is a perspective view showing the feeding cassette 233 with the attachments attached.

[0047] It is assumed that one of the main use cases of the attachments (18, 20, 24, 25) is to load envelopes onto the feeding cassette 233. However, sheets other than envelopes may be loaded onto the feeding cassette 233 with the attachments (18, 20, 24, 25) attached.

[0048] [Tray attachment] As shown in FIG. 3(a) and FIG. 4(a, b), the tray attachment 18 has an envelope front placement table 18a and a friction sheet 19.

[0049] The envelope front loading tray 18a is an elongated member having a convex shape in which a central portion a1 (see also FIG. 7(c)) in the sheet width direction Dw protrudes upward compared to both end portions a2 in the sheet width direction Dw, and the convex shape continues in the sheet feeding direction Df. The envelope front loading tray 18a is disposed in the central portion of the lifter tray 8 in the sheet width direction Dw. Specifically, as shown in FIG. 3(a), the envelope front loading tray 18a is disposed at a position overlapping with the conveyance center y0 when viewed from above, and preferably the central portion a1 of the envelope front loading tray 18a is disposed on a straight line with the conveyance center y0.

[0050] The friction sheet 19 is disposed downstream of the envelope front support tray 18a in the sheet feeding direction Df. The friction sheet 19 is disposed below the feed roller 1 (see also FIGS. 6A and 6B). The friction sheet 19 is a friction portion that increases the frictional force with the bottom sheet to prevent the stack of sheets placed on the envelope front support tray 18a from shifting during feeding due to the force applied by the feed roller 1. The friction sheet 19 is made of a sheet material that has a higher coefficient of friction with the material (paper) of typical envelopes than the surface of the envelope front support tray 18a. For example, a rubber sheet or a resin sheet with a roughened surface can be used. Alternatively, instead of attaching a sheet material, a portion of the surface of the tray attachment 18 may be roughened to serve as the friction portion. The width of the friction sheet 19 in the sheet width direction Dw can be set larger than the width of the center portion a1 of the envelope front support tray 18a to ensure a sufficient contact area between the friction sheet 19 and the sheets.

[0051] At least one engaging portion 18c that protrudes downward is provided at the bottom of the tray attachment 18. Meanwhile, the tray main body 8A is provided with an engaged portion 8c that engages with the engaging portion 18c at a position corresponding to the engaging portion 18c. In the illustrated embodiment, three engaging portions 18c and three engaged portions 8c are provided, and only one engaging portion 18c is shown in Figure 4(a). Sheet feeding direction received from the sheet during feeding Df In order to prevent the engaging portion 18c from being disengaged from the engaged portion 8c by the force of the engaging portion 18c, for example, the lower end of the engaging portion 18c is Df It is preferable that the shape of the outlet port is bent in a hook shape toward the downstream side.

[0052] 4(a) and 4(b), the user can attach tray attachment 18 to tray main body 8A by gripping tray attachment 18 and moving it from top to bottom, and engaging engaging portion 18c with engaged portion 8c. The user can also remove tray attachment 18 from tray main body 8A by gripping tray attachment 18 attached to tray main body 8A, disengaging engaging portion 18c from engaged portion 8c, and then lifting tray attachment 18 upward.

[0053] [Rear end attachment] As shown in FIG. 3(a) and FIG. 4(a, b), the rear end attachment 20 has a regulating surface 20a, an envelope rear placing table 20d, a claw portion 20b, and an attachment portion 20c.

[0054] The envelope rear loading tray 20d is an elongated member having a convex shape in which a center portion d1 (see also FIG. 7(c)) in the sheet width direction Dw protrudes upward compared to both end portions d2 in the sheet width direction Dw, and the convex shape continues in the sheet feeding direction Df. The envelope rear loading tray 20d extends downstream in the sheet feeding direction Df from the regulating surface 20a of the trailing end regulating member 14. The downstream end of the envelope rear loading tray 20d in the sheet feeding direction Df forms an inclined surface that slopes downward toward the downstream in the sheet feeding direction Df.

[0055] The envelope rear mounting tray 20d is disposed in the center of the lifter tray 8 in the sheet width direction Dw. Specifically, as shown in Fig. 3(a), the envelope rear mounting tray 20d is disposed at a position overlapping the conveyance center y0 when viewed from above, and preferably disposed so that the center d1 of the envelope rear mounting tray 20d is located on the conveyance center y0. In addition, it is preferable to dispose the envelope rear mounting tray 20d and the envelope front mounting tray 18a so that the center line of the envelope rear mounting tray 20d in the sheet width direction Dw coincides with the center line of the envelope front mounting tray 18a in the sheet width direction Dw.

[0056] As described above, the envelope front loading platform 18a of the tray attachment 18 and the envelope rear loading platform 20d of the rear end attachment 20 are both formed with a convex shape with the center portion in the sheet width direction Dw protruding upward. The envelope rear loading platform 20d functions as a support portion (first support portion) that is provided on the rear end regulating member 14 and supports the underside of the sheet. Meanwhile, the envelope front loading platform 18a of the lifter tray 8 functions as a second support portion that supports the underside of the sheet downstream of the first support portion in the sheet feeding direction Df.

[0057] The envelope front loading platform 18a is provided on the tray body 8A of the lifter tray 8 and moves up and down together with the tray body 8A. On the other hand, the envelope rear loading platform 20d is provided as part of the trailing end regulating member 14 supported on the bottom 16 of the feeding cassette 233, and does not move up and down even when the lifter tray 8 moves up and down.

[0058] Here, it is preferable that the protruding height of the first support portion be set to be greater than the protruding height of the second support portion. The protruding height of the first support portion is the vertical distance from the upper surface of a stacking portion capable of supporting sheets on both sides of the first support portion in the sheet width direction to the center of the first support portion in a cross section of the sheet feeding device in a plane (y-z plane) that passes through the first support portion and is perpendicular to the sheet feeding direction. The protruding height of the second support portion is the vertical distance from the upper surface of a stacking portion capable of supporting sheets on both sides of the second support portion in the sheet width direction to the center of the second support portion in a cross section of the sheet feeding device in a plane (y-z plane) that passes through the second support portion and is perpendicular to the sheet feeding direction.

[0059] In this embodiment, the envelope rear mounting table 20d protrudes from the bottom 16 of the feed cassette 233, and the envelope front mounting table 18a protrudes from the tray main body 8A of the lifter tray 8. Therefore, the protruding height (h2 in FIG. 7(c)) of the envelope rear mounting table 20d from the bottom 16 of the feed cassette 233 is set higher than the protruding height (h1 in FIG. 7(c)) of the envelope front mounting table 18a from the tray main body 8A.

[0060] The envelope front loading tray 18a has a trapezoidal cross section in a plane perpendicular to the sheet feeding direction Df, while the envelope rear loading tray 20d has a triangular cross section in a plane perpendicular to the sheet feeding direction Df. However, the envelope front loading tray 18a and the envelope rear loading tray 20d may have any convex shape that supports the center of the underside of the sheet stack in the sheet width direction Dw. For example, the envelope rear loading tray 20d may have a trapezoidal cross section or another convex shape (e.g., semicircular).

[0061] Furthermore, the widths of the center portions a1, d1 of the envelope front loading tray 18a and the envelope rear loading tray 20d in the sheet width direction Dw are both smaller than the width of the sheet with the shortest width in the sheet width direction Dw among the sheets that can be loaded in the feed cassette 233. Specifically, when the side edge regulating members 10, 11 are moved to their innermost positions, the center portions a1, d1 of the envelope front loading tray 18a and the envelope rear loading tray 20d are located inside the regulating surfaces 24a, 25a in the sheet width direction Dw. Furthermore, the widths of the center portions a1, d1 can be set to ½ or less, and more preferably ⅓, of the width of the regulating surfaces 24a, 25a when the side edge regulating members 10, 11 are moved to their innermost positions. If the width of the central portions a1, d1 that come into contact with the underside of the sheet stack is narrow, the space between the central portions a1, d1 and the regulating surfaces 24a, 25a makes it easier to absorb differences in the stack height of the sheet stack caused by uneven sheet thickness, as described below.

[0062] The claw portion 20b is a protrusion (first protrusion) that protrudes from the upper end of the regulating surface 20a toward the downstream side in the sheet feeding direction Df. The claw portion 20b has a function of preventing the uppermost sheet of the sheet stack stacked on the lifter tray 8 from protruding above the upper end of the regulating surface 20a.

[0063] The mounting portion 20c is provided on the rear side of the regulating surface 20a (upstream side of the regulating surface 20a in the sheet feeding direction Df). The mounting portion 20c is composed of a pair of hook-shaped members facing each other in the sheet width direction Dw when viewed from above, and a space for receiving the main body 14A of the trailing end regulating member 14 is formed inside the pair of hook-shaped members.

[0064] 4(a) and 4(b), the user can attach the rear end attachment 20 to the main body 14A by gripping the rear end attachment 20 and moving it from top to bottom, and fitting the main body 14A of the rear end regulating member 14 into the mounting portion 20c. The user can also remove the rear end attachment 20 from the main body 14A by gripping the rear end attachment 20 attached to the main body 14A and lifting it upward.

[0065] [Side end attachment] As shown in FIG. 3(a) and FIG. 4(a, b), each of the side end attachments 24, 25 has a restriction surface 24a, 25a, a claw portion 24b, 25b, and a mounting portion 24c, 25c.

[0066] The claws 24b and 25b are protrusions (second protrusions) that protrude inward in the sheet width direction Dw from the upper ends of the regulating surfaces 24a and 25a. The claws 24b and 25b have a function of preventing the top sheet of the sheet stack stacked on the lifter tray 8 from protruding above the upper ends of the regulating surfaces 24a and 25a.

[0067] The mounting portions 24c and 25c are provided on the rear side of the regulating surfaces 24a and 25a (outside the regulating surfaces 24a and 25a in the sheet width direction Dw). Each of the mounting portions 24c and 25c is composed of a pair of hook-shaped members facing each other in the sheet feeding direction Df when viewed from above, and a space is formed inside the pair of hook-shaped members to receive the main bodies 10A and 11A of the side end regulating members 10 and 11.

[0068] 4(a) and 4(b), the user grasps the side end attachment 24, 25 and moves it downward, fitting the main body 10A, 11A of the side end regulating member 10, 11 into the mounting portion 24c, 25c. This allows the user to mount the side end attachment 24, 25 on the main body 10A, 11A. The user can also grasp the side end attachment 24, 25 mounted on the main body 10A, 11A and lift it upward to remove the side end attachment 24, 25 from the main body 10A, 11A.

[0069] As described above, in this embodiment, by attaching the attachments (18, 20, 24, 25) from above while the feed cassette 233 is pulled out from the printer main body 201A, the feed cassette 233 becomes suitable for loading envelopes. Also, by removing the attachments (18, 20, 24, 25) from above while the feed cassette 233 is pulled out from the printer main body 201A, the feed cassette 233 becomes suitable for loading sheets other than envelopes. In this way, the user can easily change the state of the feed cassette 233 depending on the application without requiring complicated operations or tools, thereby improving usability.

[0070] In addition, in this embodiment, the envelope rear placement table 20d that swingably supports the rear end of the sheet is disposed on the rear end regulating member 14, so that it is possible to accommodate sheets of various sizes. Df 5(b) shows how a long bundle of envelopes P1 is loaded into the feeding cassette 233 to which the attachments (18, 20, 24, 25) are attached. Df 10 shows how a short bundle of envelopes Ps is being loaded into the feeding cassette 233 to which the attachments (18, 20, 24, 25) are attached.

[0071] As shown in Figures 5(a, b), by moving the rear end regulating member 14 according to the length of the envelope stacks Pl, Ps, the envelope rear loading platform 20d moves to a position where it can support the underside of the rear end of the envelope stacks Pl, Ps.

[0072] (Feeding operation) Next, the control of the lifting and lowering of the lifter tray 8 and the feeding operation will be described using Figures 6(a) and 6(b). Figures 6(a) and 6(b) are cross-sectional views of the sheet feeding device 230, cut along a plane perpendicular to the sheet width direction Dw (y direction), with a stack of envelopes P placed on the front envelope placement table 18a of the lifter tray 8 and the rear envelope placement table 20d of the trailing end regulating member 14. Figure 6(a) shows the state before the lifter tray 8 is raised, and Figure 6(b) shows the state after the lifter tray 8 is raised.

[0073] 6(a), when setting a stack of envelopes P in the feed cassette 233, the user places the stack of envelopes P in the feed cassette 233 pulled out from the printer main body 201A, and then moves the side edge regulating members 10 and 11 and the rear edge regulating member 14 to match the size of the envelopes. After that, when the feed cassette 233 is attached to the printer main body 201A, the lifter gear 15 of the feed cassette 233 meshes with the drive gear 234 of the printer main body 201A.

[0074] When the control unit of the printer main body 201A determines that the feed cassette 233 has been installed, it starts the rotation of the motor to rotate the drive gear 234. This rotates the lifter gear 15 that meshes with the drive gear 234, and the lifter arm 17 rotates together with the lifter gear 15. As a result, as shown in FIG. 6(b), the lower surface of the lifter tray 8 is pressed by the lifter arm 17, causing it to swing upward about the swing shaft 233b, and the top envelope comes into contact with the feed roller 1.

[0075] Inside the printer main body 201A, there are provided a biasing member such as a spring that biases the feed roller 1 downward, and a sensor (not shown) that detects when the height of the feed roller 1 has reached a predetermined position where it can feed envelopes. The lifter tray 8 continues to rise from the point where the top envelope contacts the feed roller 1, and when the sensor issues a signal indicating that the height of the feed roller 1 has reached the predetermined position, the control unit stops the rotation of the motor and stops the lifting of the lifter tray 8. This allows the feed roller 1 to be rotated and the feeding operation to begin.

[0076] As the feeding operation is performed, the load amount of envelope stack P decreases, and as the height of the top surface of envelope stack P decreases, a sensor emits a signal indicating that the height of feed roller 1 has fallen below a predetermined position. The control unit then starts rotating the motor, raises lifter tray 8 a predetermined amount, and then stops the motor. As a result, the height of the top surface of envelope stack P is kept approximately constant during the feeding operation, and envelopes are fed in order by feed roller 1, starting with the top envelope.

[0077] (Envelope attachment function) As described above, the feeding cassette 233 of this embodiment is made suitable for stacking sheets of uneven thickness, such as envelopes, by mounting the attachments (18, 20, 24, 25).

[0078] 7(a) shows a stack of envelopes P with flap 23 along one long side placed on a horizontal surface. At this time, because the thickness of each envelope is uneven due to flap 23, stacking heights H1, H2, H3, and H4 at the four corners of the stack of envelopes P also differ, with the height on the side with flap 23 being higher than the height on the side without flap 23 (H1>H2, H3>H4).

[0079] 7(a) is set in the feed cassette 233 with its long side parallel to the sheet feed direction Df and its short side parallel to the sheet width direction Dw (long side feed orientation). If no countermeasures are implemented in the feed cassette 233, uneven contact in the sheet width direction Dw occurs in the contact pressure between the feed roller 1 and the envelope stack P due to unevenness in the height of the envelope stack P caused by the flap 23. This uneven contact of the feed roller 1 leads to feeding problems in which the feed roller 1 is unable to properly feed the top envelope.

[0080] Also, it will be explained that the tilt of the trailing edge of the envelope bundle P may be greater than the tilt of the leading edge of the envelope bundle P due to the pressure of the feeding roller 1 on the envelope bundle P during feeding.

[0081] As shown in Figure 7(b), when the lifter tray 8 rises and the envelope stack P comes into contact with the feed roller 1, the envelope stack P is crushed by the feed roller 1, and the stack heights H1' and H2' of the leading edge of the envelope stack P become lower.

[0082] At this time, the part not receiving the pressing force of the feed roller 1 (the part in the sheet feeding direction from the feed roller 1) Df ​7(a)), the thickness of each envelope remains the same as before the bundle of envelopes P contacted the feed roller 1. Therefore, when the leading end of the bundle of envelopes P is crushed by the feed roller 1 and the stacking height decreases, the bundle of envelopes P spreads out in a roughly fan-like shape with the leading end at the center when viewed in the sheet width direction Dw. As a result, the stacking heights H3' and H4' of the trailing end of the bundle of envelopes P become higher than before the bundle of envelopes P contacted the feed roller 1. That is, compared to the state in FIG. 7(a), H3' > H3 and H4' > H4.

[0083] Here, the stack height at the rear end of the envelope stack P becomes higher on the side of the flap 23 where the thickness of each envelope is greater. As a result, the difference in stack height in the sheet width direction Dw at the rear end of the envelope stack P becomes larger compared to before the envelope stack P contacted the feed roller 1. In other words, H3'-H4'>H3-H4.

[0084] For this reason, when a stack of envelopes P is set, the topmost envelope P1 may become significantly tilted, particularly at its rear end P1b, due to the pressure applied by the feed roller 1 to the stack of envelopes P. This large tilt in the posture of the topmost envelope P1 at the rear end of the stack of envelopes P may cause feeding problems with the feed roller 1.

[0085] Here's a bit more about how poor feeding can occur due to the tilt of the trailing edge of the stack of envelopes P. Let's assume that the feed roller 1 starts feeding the topmost envelope P1 while pressing the leading edge of the stack of envelopes P, as shown in Figure 7(b). At this time, the tilt of the trailing edge P1b of the topmost envelope P1 (the difference in height between both ends in the sheet width direction Dw) decreases from H3'-H4' to H1'-H2' as the trailing edge P1b approaches the feed roller 1. In other words, even when the tilt of the trailing edge of the stack of envelopes P increases due to the pressing force of the feed roller 1, the tilt of the topmost envelope P1 at the point of contact with the feed roller 1 is considered to remain roughly constant.

[0086] However, if the leading edge P1a and trailing edge P1b of the topmost envelope P1 are at different inclinations, the envelope P1 is twisted, and a torsional stress is generated in the envelope P1 that tries to eliminate the difference in inclination between the leading edge P1a and trailing edge P1b. Specifically, when viewed from the downstream side in the sheet feeding direction Df in the state shown in Figure 7(b), a torsional stress is generated in the envelope P1 that tries to rotate the leading edge P1a clockwise. A similar torsional stress is generated in envelopes below the topmost envelope P1 if the leading edge and trailing edge have different inclinations.

[0087] Due to this torsional stress, the pressing force (contact pressure) of the uppermost envelope P1 pressing against the feed roller 1 increases on the same side as the flap 23 in the sheet width direction Dw, and the pressing force (contact pressure) of the uppermost envelope P1 pressing against the feed roller 1 decreases on the opposite side of the flap 23. In other words, when the tilt of the rear end of the envelope stack P becomes large due to the feed roller 1 pressing against the envelope stack P, the torsional stress generated in the envelope stack P disrupts the balance of the contact pressure between the feed roller 1 and the envelope P1.

[0088] 7(c), the leading edge of the envelope stack P is supported by the convex envelope front loading platform 18a. At this time, the difference in stack height (the difference between H1' and H2') at the leading edge of the envelope stack P is absorbed by the spaces on both sides of the envelope front loading platform 18a in the sheet width direction Dw. Specifically, a corner Pnc on the leading edge of the underside of the envelope stack P in the sheet feed direction Df and on the same side as the flap 23 in the sheet width direction Dw is allowed to be positioned below the center a1 of the convex envelope front loading platform 18a. On the other hand, a corner Pnd on the leading edge of the underside of the envelope stack P in the sheet feed direction Df and on the opposite side from the flap 23 in the sheet width direction Dw is allowed to be positioned above the center a1 of the envelope front loading platform 18a. Therefore, even when there is a difference in stack height (difference between H1' and H2') at the leading end of the envelope stack P, the inclination of the leading end P1a of the uppermost envelope P1 can be made closer to horizontal.

[0089] However, even if the inclination of the leading edge P1a of the uppermost envelope P1 is made closer to horizontal by the envelope front loading table 18a, if the inclination of the rear end of the envelope stack P remains large, there is a possibility that feeding problems will occur with the feed roller 1, as described above. To improve this, it is desirable to reduce the inclination of the rear end of the envelope stack P.

[0090] As another method for reducing uneven contact of the feed roller 1 when feeding sheets of uneven thickness, such as envelopes, it is possible to provide a platform that can swing around a swing axis passing through the center of the sheet width direction Dw, instead of the envelope front platform 18a. Even in this case, if the rear end of the envelope stack P remains largely tilted, there is a possibility that the feed roller 1 will not feed properly.

[0091] Therefore, in this embodiment, as shown in FIG. 7(c), the underside of the trailing end of the envelope stack P is supported by the convex envelope rear mounting tray 20d. In this case, the difference in stacking height (H3'-H4') at the trailing end of the envelope stack P is absorbed by the spaces on both sides of the envelope rear mounting tray 20d in the sheet width direction Dw. Specifically, a corner Pne at the trailing end of the envelope stack P in the sheet feed direction Df and on the same side as the flap 23 in the sheet width direction Dw on the underside of the envelope stack P is allowed to be positioned below the center d1 of the convex envelope rear mounting tray 20d. On the other hand, a corner Pnf at the trailing end of the envelope stack P in the sheet feed direction Df and on the opposite side from the flap 23 in the sheet width direction Dw on the underside of the envelope stack P is allowed to be positioned above the center d1 of the envelope rear mounting tray 20d. Therefore, even when there is a difference in stack height (difference between H3' and H4') at the rear end of the envelope stack P, the inclination of the rear end P1b of the uppermost envelope P1 can be made closer to horizontal.

[0092] In this way, in this embodiment, by supporting the underside of the rear end of the envelope stack P by the convex-shaped envelope rear loading platform 20d, the inclination of the rear end P1b of the top envelope P1 can be made closer to horizontal, thereby reducing the occurrence of feeding problems.

[0093] Here, as described above, the protruding height h2 of the rear envelope placement table 20d is set higher than the protruding height h1 of the front envelope placement table 18a (h1 < h2). As described above, this corresponds to the fact that in the state where the envelope bundle P is pressed by the feeding roller 1 (Fig. 7(b)), the difference in stacking height (H3’ - H4’) at the rear end of the envelope bundle P is larger than the difference in stacking height (H1’ - H2’) at the tip of the envelope bundle P. That is, by setting the protruding height h2 of the rear envelope placement table 20d higher than the protruding height h1 of the front envelope placement table 18a, the inclination of the rear end P1b of the uppermost envelope P1 can be made closer to horizontal.

[0094] Also, generally, envelopes are manufactured by folding and gluing from base paper, but the shape of the envelopes, the direction and position of gluing are diverse. And when the envelopes are exposed to, for example, a low humidity or low temperature environment, warping or curling may occur in the envelopes due to differences in the direction and position of this gluing. When such a warped or curled envelope bundle is loaded into the feeding cassette 233 and pressed by the feeding roller 1, the difference in stacking height in the sheet width direction Dw of the envelope bundle may become even larger due to the warping or curling.

[0095] Even in such a state, with the configuration of this embodiment, the inclination of the rear end P1b of the uppermost envelope P1 can be made closer to horizontal by the rear envelope placement table 20d, so the occurrence of feeding defects can be reduced.

[0096] Also, when the envelope bundle P is pressed by the feeding roller 1, the uppermost envelope P1 may sometimes climb over the upper end of the regulating surface 20a of the rear end regulating member 14 or the upper ends of the regulating surfaces 24a, 25a of the side end regulating members 10, 11. In this case, the envelope P1 released from the regulation of the regulating surfaces 20a, 24a, 25a may turn and skew greatly during feeding, and there may be conveyance defects and image misregistration.

[0097] In contrast, in this embodiment, by providing claw portions 20b protruding from the upper end of regulating surface 20a of trailing end regulating member 14, it is possible to prevent trailing end P1b of the uppermost envelope P1 from protruding above regulating surface 20a. Similarly, in this embodiment, by providing claw portions 24b, 25b protruding from the upper ends of regulating surfaces 24a, 25a of side end regulating members 10, 11, it is possible to prevent the side edge of the uppermost envelope P1 from protruding above regulating surfaces 24a, 25a. This reduces the possibility of poor conveyance or image misalignment caused by the uppermost envelope P1 climbing over regulating surfaces 20a, 24a, 25a during feeding.

[0098] (Variation) In the embodiment described above, a configuration has been described in which the convex envelope front tray 18a and the convex envelope rear tray 20d are used in combination. However, as described with reference to FIG. 7(b), when the feed roller 1 presses the envelope stack P, the difference in stack height at the rear end of the envelope stack P becomes larger than the difference in stack height at the leading end of the envelope stack P. Therefore, even if the envelope front tray 18a is omitted and only the envelope rear tray 20d is provided, the occurrence of feeding problems can be reduced.

[0099] <Second embodiment> Next, a feed cassette 333 according to a second embodiment of the present disclosure will be described with reference to FIGS. 8(a) and 8(b). Similar to the feed cassette 233 of the first embodiment, the feed cassette 333 according to this embodiment constitutes part of the sheet feeding device 230 and is a unit that is detachably attached to the printer main body 201A (FIG. 1). FIG. 8(a) is a perspective view of the feed cassette 333 according to this embodiment. FIG. 8(b) is a perspective view illustrating only some of the components of the feed cassette 333.

[0100] The feed cassette 333 according to this embodiment has a different internal configuration from that of the first embodiment. Hereinafter, elements with the same reference numerals as those in the first embodiment have substantially the same configurations and functions as those described in the first embodiment, and differences from the first embodiment will be mainly described.

[0101] As shown in Figures 8(a) and 8(b), the feeding cassette 333 comprises a cassette body 233A, a lifter tray 38, a lifter arm 17, a pair of side end regulating members 34 and 35, a trailing end regulating member 30, a slide rail 9, and a separation roller 3.

[0102] The lifter tray 38 has a shape in which the tray body 8A and the tray attachment 18 in the first embodiment are integrated. Therefore, the lifter tray 38 has a convex envelope front loading platform 38a. The shape and arrangement of the envelope front loading platform 38a can be the same as the envelope front loading platform 18a in the first embodiment.

[0103] The side edge regulating member 34 has a shape in which the main body 11A of the side edge regulating member 11 in the first embodiment is integrated with the side edge attachment 24. The side edge regulating member 35 has a shape in which the main body 10A of the side edge regulating member 10 in the first embodiment is integrated with the side edge attachment 25. The side edge regulating members 34, 35 have claws 34b, 35b that prevent the uppermost sheet from protruding above the regulating surfaces of the side edge regulating members 34, 35.

[0104] The trailing end regulating member 30 has a shape in which the main body 14A of the trailing end regulating member 14 and the trailing end attachment 20 in the first embodiment are integrated. Therefore, the trailing end regulating member 30 has a convex envelope rear loading platform 30d. The shape and arrangement of the envelope rear loading platform 30d can be the same as the envelope rear loading platform 20d in the first embodiment. In addition, the trailing end regulating member 30 has a claw portion 30b that prevents the uppermost sheet from protruding above the regulating surface of the trailing end regulating member 30.

[0105] In this manner, in this embodiment, the envelope front tray 18a and the envelope rear tray 30d, which are suitable for stacking sheets of non-uniform thickness such as envelopes, are not provided as attachments as in the first embodiment, but are instead built into the feed cassette 333 from the beginning. Therefore, when loading envelopes or the like, the same advantages as in the first embodiment can be obtained. Furthermore, when the feed cassette 233 is used solely for the purpose of feeding envelopes or the like, the sheet feeding device can be simplified and costs can be reduced.

[0106] (Other embodiments) The printer 201 described in the above embodiment is an example of an image forming apparatus. As the image forming means, instead of the tandem intermediate transfer type image forming unit 201B described above, a direct transfer type image forming unit that directly transfers a toner image from an image carrier to a sheet may be used. Furthermore, the image forming means is not limited to an electrophotographic type, and an inkjet type image forming unit or an offset printing mechanism may also be used.

[0107] Furthermore, the sheet feeding device is not limited to one provided as a part of the image forming device, but may be one (optional feeder) connected to the image forming device and feeding sheets to the image forming device. Furthermore, the sheet feeding device may be one that feeds sheets for purposes other than image formation (for example, a device that feeds sheets (documents) to be read in an image reading device, or a device that feeds envelopes to inspect their contents). [Explanation of symbols]

[0108] 1...feeding member (feeding roller) / 14...rear end regulating member / 16, 8...loading portion (bottom of feeding cassette, lifter tray) / 20a...contact surface (regulating surface) / 20b...protruding portion (claw portion) / 20d...supporting portion, first supporting portion (rear envelope placing table) / 18a...second supporting portion (front envelope placing table) / 201...image forming apparatus (printer) / 230...sheet feeding device / 233...storage cabinet (feeding cassette) / h2...protruding height of first supporting portion, h1...protruding height of second supporting portion

Claims

1. a loading section on which sheets are loaded; a feeding member provided above the stacking section and configured to feed the top sheet of the sheets stacked on the stacking section in a sheet feeding direction; a trailing edge regulating member that is provided movably in the sheet feeding direction and that regulates the position of the trailing edge of the sheet stacked on the stacking section in the sheet feeding direction; Equipped with the trailing edge regulating member has a support portion that supports a lower surface of the sheet stacked on the stacking portion, the support portion has a convex shape in which a central portion of the support portion in a sheet width direction perpendicular to the sheet feeding direction and the up-down direction protrudes upward compared to both end portions of the support portion in the sheet width direction. A sheet feeding device characterized by:

2. The support portion is a first support portion, a second support portion disposed downstream of the first support portion in the sheet feeding direction and configured to support a lower surface of the sheets stacked on the stacking portion; The second support portion has a convex shape in which a central portion of the second support portion in the seat width direction protrudes upward compared to both end portions of the second support portion in the seat width direction.

2. The sheet feeding device according to claim 1, wherein the sheet feeding device is a sheet feeding device.

3. a protruding height of the first support portion protruding upward from the loading portion is greater than a protruding height of the second support portion protruding upward from the loading portion; 3. The sheet feeding device according to claim 2, wherein the sheet feeding device is a sheet feeding device.

4. It is equipped with a storage compartment for storing seats, the loading section has a bottom of the storage cabinet, and a lifting member that is provided so as to be able to rise and fall relative to the bottom and is disposed at a position that overlaps with the feeding member when viewed from above, the first support portion protrudes upward relative to the bottom portion, The second support portion protrudes upward relative to the lifting member.

4. The sheet feeding device according to claim 2, wherein the sheet feeding device is a sheet feeding device.

5. a center portion of the first support portion in the sheet width direction and a center portion of the second support portion in the sheet width direction are located on a straight line that passes through a center position of the feeding member in the sheet width direction and extends in the sheet feeding direction when viewed from above; 5. The sheet feeding device according to claim 2, wherein the sheet feeding device is a sheet feeding device.

6. a friction portion is provided at a downstream end of the second support portion in the sheet feeding direction, the friction portion being in contact with a lower surface of the sheets stacked on the stacking portion and preventing the sheets stacked on the stacking portion from shifting in position due to a force received from the feeding member; 6. The sheet feeding device according to claim 2, wherein the sheet feeding device is a sheet feeding device.

7. The second support portion is positioned relative to the loading portion so as not to move in the sheet feeding direction.

7. The sheet feeding device according to claim 2, wherein the sheet feeding device is a sheet feeding device.

8. The length of the second support portion in the sheet feeding direction is longer than the length of the first support portion in the sheet feeding direction.

8. The sheet feeding device according to claim 7, wherein the sheet feeding device is a sheet feeding device.

9. the trailing edge regulating member has a contact surface that contacts the trailing edge of the sheet stacked on the stacking section, and a protruding portion that protrudes from an upper end of the contact surface to a downstream side in the sheet feeding direction, 9. The sheet feeding device according to claim 1, wherein the sheet feeding device is a sheet feeding device.

10. The sheet stacking device further includes a pair of side edge regulating members each of which is movable in the sheet width direction and which regulates the position of a side edge of the sheet stacked in the sheet width direction, The abutment surface is a first abutment surface, and the protrusion is a first protrusion, Each of the pair of side end regulating members has a second contact surface that contacts a side end of a sheet stacked on the stacking section, and a second protrusion that protrudes inward in the sheet width direction from an upper end of the second contact surface.

10. The sheet feeding device according to claim 9, wherein the sheet feeding device is a sheet feeding device.

11. the trailing edge regulating member has a main body to which the support portion is detachably attached, The main body portion, with the support portion removed, can regulate the position of the rear end of the sheets stacked on the stacking portion.

11. The sheet feeding device according to claim 1, wherein the sheet feeding device is a sheet feeding device.

12. a sheet feeding device according to any one of claims 1 to 11; an image forming means for forming an image on the sheet fed by the sheet feeding device; An image forming apparatus comprising:

Images