Image forming apparatus

Abstract

To regulate the leading edge of long sheets being discharged without getting caught in the cassette unit.SOLUTION: An image forming apparatus S according to the present invention comprises: a main body S1; a cassette unit 40 attached to the main body and capable of storing sheets P; an image forming part 30 which forms an image on a sheet fed from the cassette unit; a discharge part 70 which discharges the sheet on which the image has been formed by the image forming part in a discharge direction DD; and a discharge tray 5 which stacks the sheets discharged by the discharge part. The cassette unit is constituted so as to protrude from the main body in the discharge direction and extend for storing a sheet longer than the main body in the discharge direction. A cover part 100 covering the upper part of the projecting part of the cassette unit is arranged. A stopper 103 is provided on the cover part to regulate the position of the leading end of the sheet stacked on the discharge tray and protruding from the discharge tray.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to an image forming apparatus having a regulating unit that regulates the position of the leading end of a discharged sheet.

Background Art

[0002] Conventionally, there has been an image forming apparatus that forms an image on a long sheet longer than a cassette for storing the sheet. In order to handle a long sheet longer than the cassette for storing the sheet, Patent Document 1 discloses an image forming apparatus in which the cassette is configured to be extendable, and a part of the extended cassette can be installed protruding from the main body of the image forming apparatus. Patent Document 2 discloses a cassette configured such that the sheet to be discharged can be stacked on the cover of the cassette, and an opening that is not covered by the cover when the cassette is extended can be covered by a movable part such as a frame or a bellows sheet.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the image forming apparatus described in Patent Document 1, since an opening is formed on the upper surface of the extended cassette, the tip of the long sheet to be discharged may get caught in the opening, resulting in loading defects or jams. In the cassette described in Patent Document 2, since the long sheet is discharged onto the frame that covers the opening when the cassette is extended, it is possible to prevent the tip of the long sheet from getting caught in the opening. However, it is not known how far the tip of the discharged long sheet will go, and there is a risk of it falling from above the cassette. For this reason, in the prior art, there is a problem that the discharged long sheet protrudes from the cassette and the loading performance deteriorates.

Means for Solving the Problems

[0005] An image forming apparatus according to an embodiment of the present invention includes: a main body, a feeding cassette mounted on the main body and capable of storing sheets, an image forming unit that forms an image on the sheet fed from the feeding cassette, a discharging unit that discharges the sheet on which the image has been formed by the image forming unit in the discharging direction, a stacking unit that stacks the sheet discharged by the discharging unit, and is characterized in that the feeding cassette is configured to be extendable by protruding from the main body in the discharging direction in order to store a sheet longer than the length of the main body in the discharging direction, above the portion of the feeding cassette that protrudes from the main body, a cover portion that covers the portion is disposed, and a regulating portion is provided on the cover portion to regulate the position of the tip of the sheet that is stacked on the stacking portion and protrudes from the stacking portion.

Advantages of the Invention

[0006] According to the present invention, the position of the tip of the sheet can be regulated by the regulating portion provided on the feeding cassette without the long sheet to be discharged being caught by the feeding cassette.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Modes for Carrying Out the Invention

[0008] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in the following embodiments should be appropriately changed according to the configuration of the apparatus to which the present invention is applied and various conditions, and are not intended to limit the scope of the present invention only thereto.

[0009] The overall configuration of the image forming apparatus S will be described with reference to FIGS. 1 to 5. FIG. 1 is a cross-sectional view of the image forming apparatus S. FIG. 2 is a perspective view of the cassette unit 40. FIG. 3 is a perspective view of the cassette unit 40 with only the front cassette tub 43 pulled forward. FIG. 4 is a cross-sectional view of the image forming apparatus S with the cassette unit 40 of FIG. 3 to which the cover portion 100 is attached. FIG. 5 is a perspective view of the image forming apparatus S of FIG. 4.

[0010] The image forming apparatus S is an electrophotographic tandem type laser beam printer that forms a color image on a recording medium using four colors of toner: yellow, magenta, cyan, and black. The recording medium is a recording material on which an image is formed by an electrophotographic image forming apparatus, and examples thereof include paper, OHP sheets, cloth, and the like. Hereinafter, the recording medium is referred to as sheet P. The image forming apparatus S includes a cassette unit 40 (feeding cassette), an image forming unit 30, a discharging unit 70, and a discharge tray 5. The cassette unit 40 can store a plurality of sheets P and is detachably attached to the main body S1 of the image forming apparatus S. The image forming unit 30 forms an image on the sheet P fed from the cassette unit 40. The discharging unit 70 is provided with a discharging roller 7 that discharges the sheet P on which an image has been formed by the image forming unit 30 to the outside of the main body S1 of the image forming apparatus S. The discharge tray 5 is a stacking unit that stacks the sheets P discharged by the discharging roller 7.

[0011] The image forming unit 30 includes drum-type electrophotographic photoreceptors (hereinafter referred to as photosensitive drums) 10Y, 10M, 10C, and 10K that respectively correspond to yellow, magenta, cyan, and black. Note that the subscripts Y, M, C, and K of the reference numerals indicate yellow, magenta, cyan, and black, respectively. In the following description, for example, the subscripts Y, M, C, and K of the same configuration such as the photosensitive drums 10Y, 10M, 10C, and 10K may be omitted, and for simplicity, the configuration and operation may be described by representing them with the photosensitive drum 10. The photosensitive drum 10 is rotatably supported by the image forming apparatus S and is rotated in the direction indicated by the arrow in FIG. 1 by a driving means (not shown). Around the photosensitive drum 10, a charging roller 11, a developing roller 12, a primary transfer roller 14, and a cleaning blade 13 as process means are arranged along the rotation direction thereof.

[0012] The photosensitive drum 10 is configured by providing a photoconductive layer such as OPC (organic photoconductor) on the outer peripheral surface of an aluminum cylinder. The charging roller 11 is composed of a core metal and a conductive elastic member surrounding the core metal. The charging roller 11 is arranged in contact with the surface of the photosensitive drum 10 and rotates passively, and a charging bias is applied by a power source (not shown). The charging rollers 11Y, 11M, 11C, and 11K uniformly charge the surfaces of the photosensitive drums 10Y, 10M, 10C, and 10K.

[0013] The exposure unit 2 houses a rotating polygon mirror 21, first imaging optical elements 22 (22YM, 22CK), mirrors 23 (23Y, 23M, 23C, 23K), 24 (24M, 24C), and second imaging optical elements 25 (25Y, 25M, 25C, 25K). The exposure unit 2 has a semiconductor laser (not shown) which is a laser light source. The rotating polygon mirror 21 deflects and scans the laser lights LY, LM, LC, and LK emitted from a semiconductor laser (not shown). The laser lights LY, LM, LC, and LK deflected and scanned by the rotating polygon mirror 21 are respectively guided to and imaged on the surfaces of the photosensitive drums 10Y, 10M, 10C, and 10K by the first imaging optical elements 22, mirrors 23, 24, and second imaging optical elements 25. The exposure unit 2 irradiates the surfaces of the photosensitive drums 10Y, 10M, 10C, and 10K uniformly charged by the charging rollers 11Y, 11M, 11C, and 11K with the laser lights LY, LM, LC, and LK based on the image information of each color to form an electrostatic latent image. The developing rollers 12Y, 12M, 12C, and 12K develop the electrostatic latent image formed on the surfaces of the photosensitive drums 10Y, 10M, 10C, and 10K by attaching toners of different colors (yellow, magenta, cyan, black) to form a toner image.

[0014] The intermediate transfer belt 15 (intermediate transfer member) is a belt formed in an endless shape so as to form a loop, and is stretched over three tension rollers parallel to each other. By the rotation of these tension rollers, the intermediate transfer belt 15 is rotated so that its surface moves (runs) in the direction indicated by the arrow. Also, inside the loop of the intermediate transfer belt 15, primary transfer rollers 14 (14Y, 14M, 14C, 14K) are arranged. The primary transfer roller 14 presses the intermediate transfer belt 15 against the surface of the photosensitive drum 10 to form a primary transfer nip portion N1 (N1Y, N1M, N1C, N1K) between the photosensitive drum 10 and the intermediate transfer belt 15. A primary transfer bias is applied to the primary transfer roller 14 by a power source (not shown). The primary transfer rollers 14Y, 14M, 14C, 14K primarily transfer the toner images of each color on the surface of the photosensitive drums 10Y, 10M, 10C, 10K onto the surface of the intermediate transfer belt 15. The cleaning blades 13Y, 13M, 13C, 13K remove the toner (primary transfer residual toner) remaining on the surfaces of the photosensitive drums 10Y, 10M, 10C, 10K.

[0015] On the downstream side of the primary transfer nip portion N1 in the rotation direction of the intermediate transfer belt 15, a secondary transfer roller 16 is arranged. The secondary transfer roller 16 forms a secondary transfer nip portion N2 between itself and the intermediate transfer belt 15. A secondary transfer bias is applied to the secondary transfer roller 16 by a power source (not shown).

[0016] With respect to the conveyance direction CD of the sheet P (the direction indicated by the dashed arrow in FIG. 1), on the downstream side of the secondary transfer nip portion N2, a fixing device 50 for heating and pressing the sheet P to fix the toner on the sheet P is provided. On the downstream side of the fixing device 50, a discharge portion 70 and a discharge tray 5 which is a stacking portion provided on the upper surface portion of the cover 4 are provided.

[0017] The cassette unit 40 can store a plurality of sheets P fed to the secondary transfer nip portion N2. As shown in FIGS. 2 and 3, the cassette unit 40 for storing the sheet P includes a rear cassette tub 41, an intermediate cassette tub 42, and a front cassette tub 43. The rear cassette tub 41, the intermediate cassette tub 42, and the front cassette tub 43 are arranged so as to overlap vertically. When storing the long sheet P longer than the length of the discharge direction DD of the main body S1 of the image forming apparatus S in the cassette unit 40, the cassette unit 40 is configured to be extendable by protruding from the main body S1 in the discharge direction DD. By sliding the rear cassette tub 41, the intermediate cassette tub 42, and the front cassette tub 43 in the front-rear direction, the storage size of the cassette unit 40 can be extended.

[0018] FIG. 3 shows a state in which only the front cassette tub 43 is extended forward. The middle plate 44 is attached to the rear cassette tub 41 so as to rotate about the rotation center axis 44a. Further, the middle plate 44 is biased upward by an elastic member such as a spring (not shown) and presses the sheet P stored in the cassette unit 40 against the feed roller 3 (FIG. 1). The side regulating members 45 and 46 are attached to the rear cassette tub 41 so as to be movable in the left-right direction. The side regulating members 45 and 46 are configured to be moved in the left-right direction by the user to align the side edges of the stored sheet P and align the width of the sheet P. The rear end regulating portion 47 is attached to the front cassette tub 43 so as to be slidable in the front-rear direction according to the length of the sheet stored in the cassette unit 40. The rear end regulating portion 47 is configured to be moved in the front-rear direction by the user to align the rear end of the stored sheet P and align the positions in the conveyance direction CD of the sheet P.

[0019] When the cassette unit 40 with only the front cassette barrel 43 shown in FIG. 3 extended forward is attached to the image forming apparatus S, as shown in FIGS. 4 and 5, the front cassette barrel 43 protrudes forward of the image forming apparatus S. A cover portion 100 is disposed above the cassette unit 40 so that the tip of the long sheet P to be discharged enters the protruding portion of the cassette unit 40 and no loading failure or jam occurs. The cover portion 100 includes a front dust cover 101 and a rear dust cover 102. In the present embodiment, the cover portion 100 is composed of two parts, but the cover portion 100 may be composed of one part or three or more parts. The cover portion 100 preferably has a plurality of cover parts, and the plurality of cover parts are configured to be telescopic in a nested manner. The cover portion 100 is disposed so as to cover the upper part of the cassette unit 40 protruding from the main body S1 of the image forming apparatus S. In the cover portion 100 shown in FIGS. 4 and 5, the rear dust cover 102 is disposed vertically above the front dust cover 101. The front dust cover 101 and the rear dust cover 102 are disposed on the cassette unit 40 so as to be relatively slidable in the front-rear direction.

[0020] The stopper 103 is provided on the upper surface of the front dust cover 101 to prevent the tip of the long sheet P to be discharged from protruding forward more than expected. The stopper 103 is a regulating part that regulates the position of the tip of the long sheet P loaded on the discharge tray 5 and protruding from the discharge tray 5. The stopper 103 is movable following the movement of the front dust cover 101 when the front dust cover 101 slides. As shown in FIG. 3, the stopper 103 is disposed on the front cassette barrel 43 at a position corresponding to the maximum size of the sheet P that can be stored in the cassette unit 40 with only the front cassette barrel 43 pulled out forward. A notch 102a is provided in the rear dust cover 102 so that the stopper 103 does not interfere with the rear dust cover 102 even when the rear dust cover 102 is disposed vertically overlapping on the front dust cover 101. The length of the front dust cover 101 is longer in the front-rear direction than the length of the rear dust cover 102 so that the inside of the cassette unit 40 is not exposed from the notch 102a of the rear dust cover 102 when the front dust cover 101 slides.

[0021] Above the cover part 100, a guide part 104 is provided to guide the tip of the long sheet P loaded on the discharge tray 5 and protruding from the discharge tray 5 to the upper surface of the cover part 100. The guide part 104 has an inclined surface part 104a (inclined part) that guides the tip of the long sheet P so that the tip of the long sheet P to be discharged is smoothly guided onto the cover part 100. The guide part 104 may be provided on the rear dust cover 102, or may be detachably attached to the main body S1 of the image forming apparatus S.

[0022] Here, let the maximum length of the long sheet P that can be stored in the cassette unit 40 shown in FIG. 4 be L1. Let the length in the discharge direction DD of the loadable portion of the discharge tray 5 including the cover 4 on the image forming apparatus S be L2. Let the height from the front end portion of the image forming apparatus S of the loadable portion of the discharge tray 5 including the cover 4 on the image forming apparatus S to the guide portion 104 be H. Let the length of the inclined surface portion 104a of the guide portion 104 be D1. Let the length from the guide portion 104 to the stopper 103 be D2. Let the length obtained by adding H, D1, and D2 be L3. L3 represents the distance from the front end portion of the cover 4 to the stopper 103 along the surfaces of the front surface of the image forming apparatus S, the guide portion 104, the front dust cover 101, and the rear dust cover 102, and is referred to as the creepage length in this specification. In the present embodiment, the stopper 103 is arranged on the front dust cover 101 so as to satisfy the following conditions. L2 > L3 L2 + L3 > L1 Note that the stopper 103 may be fixed on the front dust cover 101 within a range that satisfies the above conditions, or may be provided on the front dust cover 101 so as to be slidable in the front-rear direction.

[0023] By satisfying the condition of L2 > L3, more than half of the discharged long sheet P is on the discharge tray 5 including the cover 4 (hereinafter, simply referred to as the discharge tray 5). Therefore, even if the long sheet P protrudes from the discharge tray 5, it is possible to prevent the long sheet P from falling from the discharge tray 5.

[0024] By satisfying the condition of L2 + L3 > L1, the discharge operation of the long sheet P is not hindered in a state where the leading end of the discharged long sheet P hits the stopper 103. Since the stopper 103 prevents the leading end of the discharged long sheet P from protruding too much, it is possible to prevent a decrease in the loading performance of the long sheet P.

[0025] Next, the image forming operation by the above-described image forming apparatus S will be described. The photosensitive drum 10 is rotated in the direction indicated by the arrow in FIG. 4. The charging roller 11 has a charging bias applied thereto, contacts the photosensitive drum 10 and rotates, uniformly charging the surface of the photosensitive drum 10 to a predetermined potential. The exposure unit 2 emits a laser beam L according to the video signal which is image information, exposes the surface of the uniformly charged photosensitive drum 1, and forms an electrostatic latent image. The electrostatic latent image on the surface of the photosensitive drum 10 is developed by attaching toner at a position (contact position) facing the developing roller 12. As a result, toner images of different colors (yellow, magenta, cyan, black) are formed on the surface of the photosensitive drum 10 respectively.

[0026] Due to the action of the primary transfer bias applied to the primary transfer roller 14, the toner image on the photosensitive drum 10 is transferred onto the intermediate transfer belt 15 at the primary transfer nip portion N1. The toner images on each photosensitive drum 10 are formed at a timing such that they overlap each other when transferred onto the intermediate transfer belt 15. As a result, a toner image in which the four-color toner images of yellow, magenta, cyan, and black overlap is formed on the intermediate transfer belt 15. Note that the toner remaining on the photosensitive drum 10 after passing through the primary transfer nip portion N1 is scraped off by the cleaning blade 13 of the cleaner unit (not shown).

[0027] The toner image on the intermediate transfer belt 15 is conveyed to the secondary transfer nip portion N2 by the rotation of the intermediate transfer belt 15. On the other hand, the sheet P is fed by the feed roller 3 and conveyed toward the secondary transfer nip portion N2 in synchronization with the toner image on the intermediate transfer belt 15. The toner image on the intermediate transfer belt 15 is transferred onto the sheet P at the secondary transfer nip portion N2 due to the action of the secondary transfer bias applied to the secondary transfer roller 16.

[0028] The sheet P onto which the toner image has been transferred is conveyed to the fixing device 50. The fixing device 50 heats and presses the sheet P to fix (melt and adhere) the toner image onto the sheet P. As a result, a full-color image is formed on the sheet P. The toner remaining on the surface of the intermediate transfer belt 15 after passing through the secondary transfer nip portion N2 is scraped off by a belt cleaner (not shown).

[0029] The sheet P that has passed through the fixing device 50 is discharged outside the main body S1 of the image forming apparatus S by the discharge roller 7 and is stacked on the discharge tray 5 which is a stacking portion provided on the upper surface portion of the cover 4. The leading end of the long sheet P protrudes from the discharge tray 5 and is stacked while being guided by the guide portion 104 onto the cover portion 100 disposed on the portion protruding to the front side of the image forming apparatus S of the cassette unit 40, and is regulated by the stopper 103 and stops.

[0030] As described above, since the cover portion 100 is disposed on the portion of the front cassette barrel 43 protruding to the front side of the image forming apparatus S, the leading end of the long sheet P of length L1 discharged does not enter into the cassette unit 40. Therefore, it is possible to prevent poor stacking and jamming of the long sheet P. Further, the guide portion 104 can smoothly guide the leading end of the long sheet P onto the cover portion 100.

[0031] The stopper 103 is disposed on the front dust cover 101 under the conditions of L2 > L3 and L2 + L3 > L1. Since the condition of L2 > L3 is satisfied, more than half of the discharged long sheet P is on the discharge tray 5. Therefore, even if the long sheet P protrudes from the discharge tray 5, it can be prevented from falling from the discharge tray 5. Since the condition of L2 + L3 > L1 is satisfied, it is possible to prevent the leading end of the discharged long sheet P from protruding too much and the stacking performance from deteriorating without hindering the discharge operation in a state where the leading end of the discharged long sheet P hits the stopper 103.

[0032] Therefore, even if the tip of the long sheet P protrudes from the discharge tray 5, it will not get caught on the cassette unit 40, and it is possible to prevent the tip of the discharged long sheet P from protruding too much, reducing the stacking performance, or falling from the discharge tray 5. Since the tip of the long sheet P can be kept at a predetermined position, it is possible to improve the reliability without degrading the stacking performance of the long sheet P.

[0033] Hereinafter, with reference to the accompanying drawings, the case where the cassette unit 40 is further extended will be described. FIG. 6 is a perspective view showing the cassette unit 40 in a state where the intermediate cassette barrel 42 and the front cassette barrel 43 are pulled out forward. FIG. 7 is a cross-sectional view of the image forming apparatus S equipped with the cassette unit 40 of FIG. 6 to which the cover portion 100 is attached. FIG. 8 is a perspective view of the image forming apparatus S of FIG. 7.

[0034] When the cassette unit 40 in a state where the intermediate cassette barrel 42 and the front cassette barrel 43 shown in FIG. 6 are extended forward is attached to the image forming apparatus S, as shown in FIGS. 7 and 8, the intermediate cassette barrel 42 and the front cassette barrel 43 protrude forward of the image forming apparatus S. A cover portion 100 is disposed above the cassette unit 40 so that the tip of the discharged long sheet P does not enter the protruding portion of the cassette unit 40 and cause stacking defects or jams. The cover portion 100 includes a front dust cover 101 and a rear dust cover 102. The front dust cover 101 is slid forward with respect to the rear dust cover 102 and is disposed above the front cassette barrel 43. The rear dust cover 102 is disposed above the intermediate cassette barrel 42. In this way, according to the length of the long sheet P, the front dust cover 101 can be slid back and forth with respect to the rear dust cover 102, and the portion of the cassette unit 40 protruding forward of the image forming apparatus S can be covered by the cover portion 100.

[0035] When the length of the cassette unit 40 is extended according to the length of the long sheet P, the front dust cover 101 can be slid relative to the rear dust cover 102, and the cover portion 100 can surely cover the upper part of the protruding portion of the cassette unit 40. Since the rear dust cover 102 is provided above the front dust cover 101, even when the front dust cover 101 is slid, the tip of the long sheet P discharged is guided onto the front dust cover 101 without being caught.

[0036] As shown in FIG. 6, the stopper 103 is disposed on the front cassette barrel 43 at a position corresponding to the maximum size of the sheet P that can be stored in the cassette unit 40 with the intermediate cassette barrel 42 and the front cassette barrel 43 pulled out forward. The position of the stopper 103 is variable, and for example, it can slide in the front-rear direction according to the slide position of the rear end regulating portion 47 provided in the cassette unit 40.

[0037] On the front side of the cover 4 of the image forming apparatus S, an extension tray 6 (discharge extension tray) capable of extending the loading range of the discharge tray 5 forward is provided so as to be slidable in the front-rear direction. FIG. 5 shows a closed state in which the extension tray 6 is retracted into the main body S1 of the image forming apparatus S. FIG. 8 shows a state in which the extension tray 6 is pulled out to the front side of the image forming apparatus S. Here, since the length D13 of the guide portion 104 in the discharge direction DD is longer than the length L12 of the extension tray 6 in the discharge direction DD, the tip of the long sheet P protruding from the extension tray 6 is guided by the inclined surface portion 104a of the guide portion 104.

[0038] Here, let the maximum length of the long sheet P that can be stored in the cassette unit 40 shown in FIG. 7 be L11. Let the length in the discharge direction DD of the loadable portion of the discharge tray 5 including the cover 4 on the image forming apparatus S be L2. Let the height from the front end portion of the image forming apparatus S of the loadable portion of the discharge tray 5 including the cover 4 on the image forming apparatus S to the guide portion 104 be H. Let the length of the inclined surface portion 104a of the guide portion 104 be D1. Let the length from the guide portion 104 to the stopper 103 be D12. Let the length obtained by adding H, D1, and D12 be L23.

[0039] Even if the length L11 of the long sheet P satisfies the condition of L2 + L23 > L11, when L2 < L23, even if the position of the tip of the long sheet P is regulated by the stopper 103, the length of the portion of the long sheet P on the discharge tray 5 becomes half or less of L11. Therefore, the discharged long sheet P may fall from the discharge tray 5.

[0040] Therefore, when L2 < L23, the extension tray 6 is pulled out forward. Let the length in the discharge direction DD of the extension tray 6 be L12. Let the height from the front end portion (tip portion) of the extension tray 6 to the point A of the inclined surface portion 104a of the guide portion 104 that intersects vertically be H1. Let the length from the point A of the inclined surface portion 104a of the guide portion 104 to the end point B of the inclined surface portion 104a in the discharge direction DD be D11. Let the length obtained by adding H1, D11, and D12 be L13. L13 represents the distance from the front end portion (tip portion) of the extension tray 6 to the stopper 103 along the surface of the front surface of the image forming apparatus S, the guide portion 104, the front dust cover 101, and the rear dust cover 102, and is referred to as the surface length in this specification. In the present embodiment, the stopper 103 is arranged on the front dust cover 101 so as to satisfy the following conditions. L2 + L12 > L13 L2 + L12 + L13 > L11

[0041] By satisfying the condition of L2 + L12 > L13, more than half of the discharged long sheet P is on the discharge tray 5 and the extension tray 6. Therefore, even if the long sheet P protrudes from the extension tray 6, it is possible to prevent the long sheet P from falling from the discharge tray 5.

[0042] By satisfying the condition of L2 + L12 + L13 > L11, the discharge operation of the long sheet P is not hindered when the tip of the discharged long sheet P hits the stopper 103. Since the stopper 103 prevents the tip of the discharged long sheet P from protruding too much, it is possible to prevent a decrease in the stacking performance of the long sheet P.

[0043] As described above, the rear dust cover 102 and the front dust cover 101 are respectively arranged on the intermediate cassette barrel 42 and the front cassette barrel 43 that protrude to the front side of the image forming apparatus S. Thereby, the tip of the long sheet P having a length of L11 discharged does not enter the cassette unit 40. Therefore, it is possible to prevent poor stacking and jamming of the long sheet P. Further, the guide portion 104 can smoothly guide the tip of the long sheet P onto the front dust cover 101 and the rear dust cover 102.

[0044] When the extension tray 6 is pulled out to the front side, the stopper 103 is arranged on the front dust cover 101 under the following conditions with the conditions of L2 + L12 > L13 and L2 + L12 + L13 > L11. Since the condition of L2 + L12 > L13 is satisfied, more than half of the discharged long sheet P is on the discharge tray 5 and the extension tray 6. Therefore, even if the long sheet P protrudes from the extension tray 6, it is possible to prevent it from falling from the discharge tray 5. Since the condition of L2 + L12 + L13 > L11 is satisfied, it is possible to prevent the tip of the discharged long sheet P from protruding too much and the stacking performance from deteriorating without hindering the discharge operation when the tip of the discharged long sheet P hits the stopper 103.

[0045] Therefore, even if the tip of the long sheet P protrudes from the extension tray 6, it can be prevented from getting caught by the cassette unit 40, and the tip of the discharged long sheet P from protruding too far and reducing the loading performance or falling from the discharge tray 5. Since the tip of the long sheet P can be kept at a predetermined position, it is possible to improve the reliability without degrading the loading performance of the long sheet P.

[0046] In this embodiment, the position of the rear end of the long sheet P is regulated by a rear end regulating portion 47 slidably provided in the cassette unit 40. However, instead of the rear end regulating portion 47, a rear end regulating portion fixed to the front cassette barrel 43 may be used. By sliding the intermediate cassette barrel 42 and / or the front cassette barrel 43, the position of the rear end regulating portion fixed to the front cassette barrel 43 may be adjusted. In that case, by changing the amount of forward and backward sliding of the front dust cover 101 with respect to the rear dust cover 102, the cover portion 100 may cover the upper part of the portion of the cassette unit 40 protruding forward of the main body S1 according to the length of the long sheet P. Also, since the position of the stopper 103 moves according to the sliding amount of the front dust cover 101, it will be at a position corresponding to the length of the long sheet P.

[0047] Also, in this embodiment, the length D13 of the guide portion 104 in the discharge direction DD is set to be longer than the length L12 of the extension tray 6. However, the guide portion 104 may be provided so as to be movable in the front-rear direction, or a mechanism may be provided in which a part of the guide portion 104 slides and can be extended. The guide portion 104 only needs to be configured so that the long sheet P protruding from the extension tray 6 can be guided by the inclined surface portion 104a of the guide portion 104.

[0048] According to this embodiment, even when the cassette unit 40 extended for discharging the long sheet P protrudes from the main body S1 and discharges the sheet P, the cover portion 100 covers the upper surface of the cassette unit 40, so the tip of the sheet P will not be caught. Further, since the stopper 103 provided on the cover portion 100 can hold the tip of the long sheet at a predetermined position, it is possible to improve the reliability without deteriorating the loading performance. According to this embodiment, the position of the tip of the sheet P can be regulated by the stopper 103 provided on the cassette unit 40 without the long discharged sheet P being caught by the cassette unit 40.

Explanation of Reference Numerals

[0049] 5 ··· Discharge tray 30 ··· Image forming unit 40 ··· Cassette unit 70 ··· Discharge portion 100 ··· Cover portion 103 ··· Stopper DD ··· Discharge direction P ··· Sheet S ··· Image forming apparatus S1 ··· Main body

Claims

1. A main body, A feeding cassette attached to the main body and capable of storing a sheet, An image forming unit that forms an image on the sheet fed from the feeding cassette, A discharging unit that discharges the sheet on which the image has been formed by the image forming unit in the discharging direction, A stacking unit that stacks the sheet discharged by the discharging unit, and comprising, The feeding cassette is configured to be extendable by protruding from the main body in the discharging direction in order to store a sheet longer than the length of the main body in the discharging direction, Above the portion of the feeding cassette protruding from the main body, a cover portion covering the portion is arranged, An image forming apparatus, characterized in that a regulating portion for regulating the position of the leading end of the sheet stacked on the stacking portion and protruding from the stacking portion is provided on the cover portion.

2. The image forming apparatus according to claim 1, characterized in that a guide portion for guiding the leading end of the sheet stacked on the stacking portion and protruding from the stacking portion to the cover portion is provided on the cover portion.

3. Assuming that the length of the sheet in the discharging direction is L1, the length of the stacking portion in the discharging direction is L2, and the surface length along the sheet from the leading end portion of the stacking portion to the regulating portion provided on the cover portion is L3, L2 + L3 > L1, L2 > L3 The image forming apparatus according to claim 1, characterized in that the conditions are satisfied.

4. The stacking unit is provided with an extension tray that can be extended in the discharging direction, Let the length of the sheet in the discharge direction be L11, the length of the loading portion in the discharge direction be L2, the surface length from the tip of the loading portion to the restricting portion provided on the cover portion be L3, the length of the extension tray in the discharge direction be L12, and the surface length from the tip of the extension tray to the restricting portion provided on the cover portion be L13. When the conditions L2 + L3 > L11 and L2 < L3 are satisfied, by extending the extension tray the conditions L2 + L12 + L13 > L11 and L2 + L12 > L13 are satisfied, and the image forming apparatus according to claim 1 is characterized in that.

5. The cover portion of the image forming apparatus according to claim 1 is characterized in that it is extendable.

6. The cover portion of the image forming apparatus according to claim 1 is characterized in that it is composed of a plurality of parts.

7. The cover portion of the image forming apparatus according to claim 1 is characterized in that a plurality of cover parts are configured in a nested manner and are stretchable.

8. The restricting portion of the image forming apparatus according to claim 1 is characterized in that it is fixed to the cover portion.

9. The restricting portion of the image forming apparatus according to claim 1 is characterized in that it is provided on the cover portion so as to be slidable.

Images