Image forming device

Abstract

To provide an image forming apparatus that can certainly close a gap between a retainer and a support frame and can facilitate an operation to remove the retainer.SOLUTION: An image forming apparatus comprises: a support frame 81 on which image carrier units 27 and developing units are removably supported; a retainer 75 that is rotatably supported by the support frame 81 and rotates upward to locate the image carrier units 27 and the developing units on the support frame 81; and a sheet member 101 that closes the gap between the support frame 81 and the retainer 75. The sheet member 101 has an upper end 113 that is supported by the retainer 75 and a lower end 111 that is supported by the support frame 81, and at least one of the upper end 113 and the lower end 111 is removably provided.SELECTED DRAWING: Figure 6A

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus including an image carrier unit and a developing unit. [Background technology]

[0002] In an electrophotographic image forming apparatus, a toner image is formed on an image carrier by developing an electrostatic latent image formed on the image carrier with toner. Patent Document 1 discloses an image forming apparatus in which an image carrier unit having an image carrier and a developing unit that develops the electrostatic latent image with toner are detachably supported on a support frame. This image forming apparatus includes a retainer that positions the image carrier unit and the developing unit on the support frame.

[0003] The image carrier unit and the developing unit are attached and detached through an opening formed in the front plate of the support frame. The lower end of the retainer is rotatably supported by the support frame below the opening. The retainer is rotated upward and fixed to the support frame, and the retainer positions both units relative to the support frame. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2016-14854 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the image forming device described in Patent Document 1, toner scattered from the image carrier unit or the developing unit may pass through the opening and then through the gap between the lower end of the retainer and the support frame, and leak outside the image forming device.

[0006] In response to this, a sheet member may be provided to close the gap between the lower end of the retainer and the support frame. For example, the sheet member is fixed to the retainer above the gap with double-sided tape, and is fixed to the support frame below the gap with double-sided tape. In this case, when removing the retainer, the sheet member must also be removed, which causes problems such as laborious work and waste of materials.

[0007] SUMMARY OF THE PRESENT INVETION The present invention has been made in consideration of the above circumstances, and has an object to provide an image forming apparatus in which the gap between the retainer and the support frame can be reliably closed and the retainer can be easily removed. [Means for solving the problem]

[0008] In order to solve the above problems, the image forming apparatus of the present invention comprises an image carrier unit having an image carrier on which an electrostatic latent image is formed, a developing unit that develops the electrostatic latent image formed on the image carrier with toner, a support frame on which the image carrier unit and the developing unit are removably supported, a retainer that is rotatably supported on the support frame and rotates upward to position the image carrier unit and the developing unit on the support frame, and a sheet member that fills the gap between the support frame and the retainer, wherein the sheet member has an upper end supported by the retainer and a lower end supported by the support frame, and at least one of the upper end and the lower end is removably provided.

[0009] In the image forming apparatus of the present invention, the lower end of the sheet member may be fixed to the support frame, and the upper end may be detachably attached to the retainer.

[0010] In the image forming apparatus of the present invention, an insertion piece may be formed on the upper end of the sheet member, and the retainer may be provided with a holding member having an insertion hole into which the insertion piece can be inserted.

[0011] In the image forming apparatus of the present invention, a magnet piece may be provided on the upper end of the sheet member, and the retainer may be provided with a metal plate piece that is attracted by the magnetic force of the magnet piece. Effect of the Invention

[0012] According to the present invention, since it is not necessary to completely remove the sheet member when replacing the retainer, the retainer can be replaced without generating waste materials and toner leakage can be prevented. [Brief description of the drawings]

[0013] [Figure 1] 1 is a front view showing a schematic internal structure of an image forming apparatus according to an embodiment of the present invention; [Diagram 2] 1 is a front view showing a schematic diagram of an image carrier unit and a developing unit of an image forming apparatus according to an embodiment of the present invention; [Diagram 3] 1 is a perspective view showing an image carrier unit and a developing unit supported by a support frame in an image forming apparatus according to an embodiment of the present invention; [Figure 4] 5 is a front view showing a reflecting mirror adjustment hole of a support frame in the image forming apparatus according to the embodiment of the present invention. FIG. [Figure 5A] 1 is a perspective view showing a retainer rotated to a positioning position in an image forming apparatus according to an embodiment of the present invention; [Figure 5B] 1 is a perspective view showing a retainer rotated to an open position in an image forming apparatus according to an embodiment of the present invention; [Figure 6A] 1 is a side view showing a retainer rotated to a positioning position in an image forming apparatus according to an embodiment of the present invention; [Figure 6B] 1 is a side view showing a retainer rotated to an open state in an image forming apparatus according to an embodiment of the present invention; [Figure 7] 2 is a plan view showing a sheet member in the image forming apparatus according to the embodiment of the present invention; FIG. [Figure 8]1 is a perspective view showing a sheet member in an image forming apparatus according to an embodiment of the present invention; [Figure 9] FIG. 11 is a perspective view showing another example of a sheet member in the image forming apparatus according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An image forming apparatus according to an embodiment of the present invention will now be described with reference to the drawings.

[0015] The image forming apparatus will be described with reference to Fig. 1. Fig. 1 is a front view showing a schematic internal configuration of the image forming apparatus. Fr, Rr, L, and R in each drawing indicate the front, rear, left, and right sides of the image forming apparatus 1, respectively.

[0016] The image forming apparatus 1 includes a sheet feeding section 3, an electrophotographic image forming section 5, a fixing device 7, a discharge device 9, and a discharge tray 11. The image forming apparatus 1 also includes a main transport path 13 for sheets that runs from the sheet feeding section 3 to the discharge device 9 via the image forming section 5 and the fixing device 7, and a reversing path 15 branching off from the main transport path 13.

[0017] The sheet feeding section 3 includes a paper feed cassette 21 in which sheets are stored, and a paper feed unit 23 that feeds the sheets from the paper feed cassette 21 to the main transport path 13 .

[0018] The image forming unit 5 includes an endless intermediate transfer belt 25, four image carrier units 27 and four developing units 29 corresponding to toner of four colors (yellow, magenta, cyan, and black), four primary transfer rollers 31 corresponding to the four image carrier units 27, a secondary transfer roller 33, and an exposure device 35.

[0019] The intermediate transfer belt 25 is wound around a drive roller and a driven roller that are disposed apart in the left-right direction. When the drive roller rotates, the intermediate transfer belt 25 circulates and travels in the counterclockwise direction in FIG.

[0020] The four image carrier units 27 are arranged side by side along the running direction of the intermediate transfer belt 25, facing the lower track of the intermediate transfer belt 25. The four developing units 29 are arranged adjacent to the upstream side of the four image carrier units 27 in the running direction of the intermediate transfer belt 25. The four developing units 29 are connected to toner containers 37 in which toners of corresponding colors are accommodated. The four primary transfer rollers 31 are arranged in the hollow portion of the intermediate transfer belt 25, facing the four image carrier units 27 with the intermediate transfer belt 25 in between. The secondary transfer roller 33 is arranged facing the intermediate transfer belt 25, downstream of the four image carrier units 27 and the four developing units 29 in the running direction of the intermediate transfer belt 25. A transfer nip is formed between the secondary transfer roller 33 and the intermediate transfer belt 25. The image carrier units 27 and the developing units 29 will be described later.

[0021] The exposure device 35 is disposed below the four image carrier units 27 and the four developing units 29, and exposes the four image carrier units 27 to light corresponding to image data.

[0022] The fixing device 7 has a pressure roller and a heating roller, and forms a fixing nip between the two rollers.

[0023] The main transport path 13 is formed from the sheet feeding unit 3, passing through the secondary transfer nip and the fixing nip toward the discharge device 9. A pair of registration rollers 39 is disposed between the sheet feeding unit 3 and the secondary transfer nip on the main transport path 13. The reversing path 15 branches off from the main transport path 13 at a branching point between the fixing nip and the discharge device 9, and merges with the main transport path 13 at a junction between the sheet feeding unit 3 and the pair of registration rollers 39.

[0024] Next, the image forming operation will be briefly described. In the image forming section 5, the image carrier unit 27 forms an electrostatic latent image corresponding to the image data by exposure by the exposure device 35. The development unit 29 develops the electrostatic latent image formed on the image carrier unit 27 into a toner image. The toner image on each image carrier unit 27 is transferred to the intermediate transfer belt 25 by the corresponding primary transfer roller 31.

[0025] Meanwhile, in the sheet feeding section 3, a sheet is transported from a paper feed cassette 21 to the main transport path 13 by the paper feed unit 23. The sheet is transported to the secondary transfer nip at an appropriate timing by a pair of registration rollers 39. In the secondary transfer nip, the toner image formed on the intermediate transfer belt 25 is transferred to the sheet. The sheet is transported along the main transport path 13 to the fixing device 7, and the toner image is fixed to the sheet in the fixing nip of the fixing device 7. The sheet is further transported to the discharge device 9, and is discharged to the discharge tray 11 by the discharge device 9.

[0026] When double-sided printing is performed, the sheet with the toner image fixed on one side thereof is transported from the main transport path 13 to the reversing path 15 at the branching point, and then transported from the reversing path 15 to the main transport path 13 at the junction. The sheet is then transported to the secondary transfer nip at an appropriate timing by a pair of registration rollers 39, where the toner image formed on the intermediate transfer belt 25 is transferred to the other side of the sheet. The sheet is transported along the main transport path 13 to the fixing device 7, where the toner image is fixed to the sheet at the fixing nip. The sheet is further transported to the discharge device 9, and is discharged by the discharge device 9 onto the discharge tray 11.

[0027] Next, the image carrier unit 27 and the developing unit 29 will be described with reference to Figures 2 and 3. Figure 2 is a front view showing the image carrier unit 27 and the developing unit 29 in a schematic manner, and Figure 3 is a perspective view showing the image carrier unit 27 and the developing unit 29 supported by a support 71.

[0028] First, the image carrier unit 27 will be described with reference to Fig. 2. The image carrier unit 27 includes a photoconductor drum 41 as an image carrier, a charging device 43, and a cleaning device 45. The photoconductor drum 41 is rotatable in the clockwise direction in Fig. 2 about a rotation shaft 41a. The charging device 43 and the cleaning device 45 are disposed around the photoconductor drum 41 in that order along the rotation direction.

[0029] The charging device 43 includes a charging roller 49 and a cleaning roller 51. The charging roller 49 rotates in contact with the photoconductor drum 41, and applies a charging bias to the photoconductor drum 41. The cleaning roller 51 rotates in contact with the charging roller 49, and cleans the charging roller 49.

[0030] The cleaning device 45 includes a cleaning roller 53, a cleaning blade 55, and a collection roller 57. The cleaning roller 53 rotates in contact with the photoconductor drum 41, and removes toner remaining on the photoconductor drum 41. The cleaning blade 55 is disposed downstream of the cleaning roller 53 in the rotation direction of the photoconductor drum 41, and comes into contact with the photoconductor drum 41 to scrape off toner remaining on the photoconductor drum 41. The collection roller 57 transports the toner removed by the cleaning roller 53 and the cleaning blade 55 toward a collection port (not shown).

[0031] Next, the developing unit 29 will be described with reference to Fig. 2. The developing unit 29 includes a developing container 61, an agitating and conveying screw 63, a supply and conveying screw 65, and a magnetic roller 67.

[0032] The developing container 61 contains a developer containing a magnetic carrier and a toner. The developing container 61 has an opening 61a facing the photoconductor drum 41. The developing container 61 has a mixing conveying chamber 61b and a supply conveying chamber 61c formed in a lower portion thereof to which toner is replenished from a toner container 37 (see FIG. 1). The mixing conveying screw 63 is rotatably supported in the mixing conveying chamber 61b, and the supply conveying screw 65 is rotatably supported in the supply conveying chamber 61c. The magnetic roller 67 is disposed above the supply conveying screw 65, and a part of the outer circumferential surface is exposed from the opening 61a of the developing container 61.

[0033] As described above, the developing unit 29 is disposed upstream of the image carrier unit 27 in the running direction of the intermediate transfer belt 25, and the magnetic roller 67 exposed from the opening 61a of the developing container 61 faces the photosensitive drum 41 of the image carrier unit 27.

[0034] In the image carrier unit 27, the photoconductor drum 41 is charged to a predetermined potential by the charging device 43. Thereafter, the photoconductor drum 41 is exposed to light by the exposure device 35 (see FIG. 1), and an electrostatic latent image based on image data is formed.

[0035] In the developing unit 29, the toner is charged by circulating and stirring the developer in the stirring and conveying chamber 61b and the supply and conveying chamber 61c by the stirring and conveying screw 63 and the supply and conveying screw 65. The developer containing the charged toner is conveyed to the magnetic roller 67 by the supply and conveying screw 65, and a magnetic brush is formed on the magnetic roller 67.

[0036] The magnetic brush formed on the magnetic roller 67 causes toner to fly from the magnetic roller 67 to the photosensitive drum 41 due to the potential difference between the bias potential applied to the magnetic roller 67 and the potential of the electrostatic latent image on the photosensitive drum 41 at the opening 61a of the developing container 61, and the electrostatic latent image on the photosensitive drum 41 is developed into a toner image.

[0037] The toner image formed on the photoconductor drum 41 is transferred to the intermediate transfer belt 25 by the primary transfer roller 31. Any toner remaining on the photoconductor drum 41 after the toner image has been transferred to the intermediate transfer belt 25 is removed by a cleaning device 45.

[0038] 3, the four image carrier units 27 and the four developing units 29 are supported and positioned by a support 71. The support 71 includes a support frame 73 that supports each unit, and a retainer 75 that positions each unit on the support frame 73.

[0039] The support body 71 will be described with reference to Fig. 3, Fig. 4, Fig. 5A and Fig. 5B, Fig. 6A and Fig. 6B. Fig. 4 is a front view showing a front frame 81 of the support body 71, Fig. 5A and Fig. 5B are perspective views showing the retainer 75, and Fig. 6A and Fig. 6B are side views showing the retainer 75.

[0040] As shown in FIG. 3, the support frame 73 includes a front frame 81 and a rear frame 83 arranged opposite each other in the front-rear direction, and a base 85 provided for each unit between the front and rear frames 81, 83.

[0041] An opening 81a is formed in the front frame 81. The four image carrier units 27 and the four developing units 29 are supported by corresponding pedestals 85 between the front and rear frames 81 and 83. The four image carrier units 27 and the four developing units 29 can be removed from the corresponding pedestals 85 through the opening 81a of the front frame 81. Lock pins (not shown) are provided on the left and right of the opening 81a of the front frame 81. Furthermore, the front frame 81 is provided with horizontal support pieces 81b (see FIGS. 4, 5A, 6A, and 6B) that extend forward from below the opening 81a.

[0042] 4, below the opening 81a of the front frame 81 and above the support piece 81b, a plurality of holes 81c are formed through which adjustment screws 35a for adjusting the angle of the reflecting mirror included in the exposure device 35 (see FIG. 1) are exposed. When adjusting the angle of the reflecting mirror, a tool such as a screwdriver is inserted through the holes 81c to rotate the adjustment screws 35a.

[0043] Next, the retainer 75 will be described. As shown in Fig. 3, the retainer 75 is a plate-like member having dimensions larger than the opening 81a of the front frame 81 of the support frame 73, and as shown in Figs. 5B, 6A, and 6B, the retainer 75 has an outer cover 91 and a positioning plate 93 fixed to the inner surface of the outer cover 91. Hooks (not shown) are formed on the left and right edges of the outer cover 91. The positioning plate 93 is formed with a bearing hole 93a into which one end (front end) of the rotation shaft 41a of the photosensitive drum 41 of each image carrier unit 27 can be fitted. As an example, the outer cover 91 is made of resin, and the positioning plate 93 is made of sheet metal.

[0044] The left and right lower corners of the retainer 75 are supported rotatably about a rotation shaft 75a (see FIGS. 6A and 6B) below the opening 81a of the front frame 81 and above the support piece 81b. As a result, the retainer 75 rotates about the rotation shaft 75a between a positioning position (see FIGS. 5A and 6A) where the image carrier unit 27 is positioned and an open position (see FIGS. 5B and 6B) where the image carrier unit 27 and the developing unit 29 can be removed. When the retainer 75 rotates to the positioning position, as shown in FIG. 6A, the front end of the rotation shaft 41a of the photosensitive drum 41 of the corresponding image carrier unit 27 fits into the bearing hole 93a of the positioning plate 93, and the image carrier unit 27 is positioned in the support frame 73. Similarly, the developing unit 29 is positioned in the support frame 73. Furthermore, the hook of the outer cover 91 engages with the lock pin of the front frame 81, and the retainer 75 is maintained at the position. On the other hand, when the retainer 75 rotates to the open position, the image carrier unit 27 and the developing unit 29 can be removed through the opening 81a. The retainer 75 is supported by the support piece 81b of the front frame 81.

[0045] Incidentally, when the image forming operation is performed as described above, toner may scatter from the image carrier unit 27 or the developing unit 29 and leak out from the gap between each unit and the opening 81a of the front frame 81. The leaked toner may accumulate on the support piece 81b of the front frame 81 or scatter inside the machine.

[0046] For this reason, a sheet member 101 that prevents toner from leaking through gaps is provided on the support 71. The sheet member 101 will be described with reference to Figures 7 and 8. Figure 7 is a plan view showing the sheet member 101, and Figure 8 is a perspective view showing the sheet member 101.

[0047] As shown in FIG. 7, the sheet member 101 is composed of a main body side sheet 103 fixed to the support frame 73 and a fixed side sheet 105 fixed to the retainer 75. The main body side sheet 103 is a generally rectangular shape elongated in the left-right direction with dimensions capable of closing a gap, and has a lower end 111 and an upper end 113 along the left-right direction, and an intermediate portion 115 therebetween. The upper end 113 includes three flap portions 121 formed at intervals in the left-right direction. Each flap portion 121 has a pair of rectangular insertion pieces 123 formed on both side edges in the left-right direction. The upper and lower corners of each insertion piece 123 are formed in an arc shape. As an example, the upper end 113 is formed of a sheet piece made of elastic resin, and the intermediate portion 115 and the lower end 111 are formed of sheet pieces such as flexible synthetic leather or nonwoven fabric, and the upper end 113 and the intermediate portion 115 are connected by adhesion or sewing. The main body side sheet 103 is also simply referred to as a sheet member.

[0048] As shown in Figs. 5A, 6A and 6B, the lower end 111 of the main body side sheet 103 is fixed to the upper surface of the support piece 81b of the front frame 81 of the support frame 73 using double-sided tape or adhesive.

[0049] 7, the fixed-side sheet 105 has a rectangular shape that is long in the left-right direction, and has three holding portions 131 corresponding to the three flap portions 121 of the main body-side sheet 103, and a fixing portion 133 that is fixed to the retainer 75 other than the three holding portions 131. As an example, the fixed-side sheet 105 is formed of a sheet piece made of elastic resin.

[0050] Each holding portion 131 has a pair of left and right rectangular pocket pieces 141. A rectangular slit 143 is formed on the inner sides of the pair of pocket pieces 141 that face each other. A semicircular pressing piece 145 is formed on the inner sides of the pair of pocket pieces 141 that face each other.

[0051] The fixing portion 133 is fixed to the outer surface of the retainer 75 (outer cover 91) using double-sided tape or adhesive. As a result, as shown in Fig. 8, a pair of pockets 151 opening into the slits 143 are formed between the outer cover 91 and the pair of pocket pieces 141. The insertion pieces 123 of each flap portion 121 of the main body side sheet 103 can be inserted into this pocket 151 through the slits 143. In this manner, the pocket 151 formed between the outer cover 91 and the pocket piece 141 is an example of an insertion hole into which the insertion piece 123 of the main body side sheet 103 can be inserted, and the fixing side sheet 105 is an example of a holding member having an insertion hole into which the insertion piece 123 of the main body side sheet 103 can be inserted.

[0052] As shown in Fig. 5A, Fig. 6A, and Fig. 6B, the sheet member having the above-mentioned configuration has a lower end 111 of the main body side sheet 103 fixed to the upper surface of the support piece 81b of the front frame 81, and a fixed part 133 of the fixed side sheet 105 fixed to the outer cover 91 of the retainer 75. The three pairs of insertion pieces 123 of the main body side sheet 103 are inserted into three pairs of pockets 151 between the fixed side sheet 105 and the outer cover 91. After being inserted into the pockets 151, the insertion pieces 123 are pressed against the outer cover 91 by the pressing piece 145. In this way, the lower end 111 of the main body side sheet 103 is fixed to the front frame 81 below the gap, and the upper end 113 (the three flap parts 121) is supported by the retainer 75 above the gap, thereby preventing toner leaking from the gap from scattering.

[0053] Furthermore, since the middle portion 115 of the main body side sheet 103 is not fixed to the retainer 75 or the front frame 81, when the retainer 75 rotates as shown in Figs. 5B and 6B, it bends in response to the rotation.

[0054] On the other hand, by pulling out the pair of insertion pieces 123 from the pair of pockets 151, the upper end 113 of the main body side sheet 103 can be removed from the fixed side sheet 105, i.e., the retainer 75. Therefore, when replacing the retainer 75 or adjusting the angle of the reflecting mirror of the exposure device 35 (see FIG. 1), it is sufficient to pull out the insertion pieces 123 from the pockets 151 and remove the upper end 113 of the main body side sheet 103 from the retainer.

[0055] As described above, according to the present invention, when replacing the retainer 75 or adjusting the angle of the reflecting mirror, it is not necessary to completely remove the sheet member 101. Therefore, it is possible to replace the retainer 75 or adjust the angle of the reflecting mirror without generating waste materials, and toner leakage can be prevented.

[0056] Furthermore, by removably supporting the upper end 113 of the main body side sheet 103 on the retainer 75, the insertion piece 123 can be easily inserted into the pocket 151 and removed from the pocket 151. However, the lower end 111 of the main body side sheet may be removably supported on the front frame 81, and the upper end 113 may be fixed to the retainer 75. Alternatively, both the upper end 113 and the lower end 111 may be removable.

[0057] Also, a pocket may be formed directly in the outer cover 91 of the retainer 75 without providing the fixed side sheet 105. Alternatively, instead of a pocket, a slit into which the insertion piece 123 can be inserted may be formed in the outer cover 91.

[0058] Next, a modified example of the sheet member 101 will be described with reference to Fig. 9. Fig. 9 is a perspective view showing the sheet member 101.

[0059] The sheet member 101 of the modified example is also composed of a main body side sheet 103 fixed to the support frame 73, and a fixed side sheet 105 fixed to the retainer 75. The upper end portion 113 of the main body side sheet 103 is rectangular, and a magnet piece 201 is fixed to the inner surface along the left-right direction. The fixed side sheet 105 is formed of a sheet metal piece that can be attracted by the magnetic force of the magnet piece 201. A groove portion 205 with a rectangular cross section is formed along the left-right direction on the outer surface of the retainer 75 (outer cover 91). The fixed side sheet 105 is fixed to this groove portion 205.

[0060] According to this modification, the magnet piece 201 and the fixed-side sheet 105 are magnetically attracted to each other, so that the upper end portion 113 of the main body side sheet 103 is fixed to the retainer 75. On the other hand, by pulling the magnet piece 201 away from the fixed-side sheet 105 against the magnetic force, the upper end portion 113 of the main body side sheet 103 can be removed from the retainer 75. Note that a metal piece may be fixed to the upper end portion 113 of the main body side sheet 103, and the fixed-side sheet 105 may be formed of a magnet piece.

[0061] In addition to the above examples, methods such as Velcro (registered trademark) or snap fit connection can be used to removably support the upper end 113 (or lower end 111) of the sheet member 101 (main body side sheet 103) on the retainer 75.

[0062] Although the present invention has been described with reference to specific embodiments, the present invention is not limited to the above embodiments, and those skilled in the art may modify the above embodiments without departing from the scope and spirit of the present invention. [Explanation of symbols]

[0063] 1. Image forming device 27 Image carrier unit 29 Development unit 73 Support Frame 75 Retainer 101 Sheet material 105 Solid side sheet (holding member, sheet metal piece) 111 Lower end 113 Upper end 123 Insert 151 Pocket (insertion hole) 201 Magnet piece

Claims

1. an image carrier unit including an image carrier on which an electrostatic latent image is formed; a developing unit that develops the electrostatic latent image formed on the image carrier with toner; a support frame on which the image carrier unit and the developing unit are detachably supported; a retainer that is rotatably supported by the support frame and that positions the image carrier unit and the developing unit relative to the support frame by rotating upward; a sheet member that closes a gap between the support frame and the retainer, An image forming apparatus characterized in that the sheet member has an upper end supported by the retainer and a lower end supported by the support frame, and at least one of the upper end and the lower end is removable.

2. 2. The image forming apparatus according to claim 1, wherein the lower end of the sheet member is fixed to the support frame, and the upper end is detachable from the retainer.

3. An insert piece is formed on the upper end of the sheet member, 3. The image forming apparatus according to claim 2, wherein the retainer is provided with a holding member having an insertion hole into which the insertion piece can be inserted.

4. A magnet piece is provided on the upper end of the sheet member, 3. The image forming apparatus according to claim 2, wherein the retainer is provided with a metal plate piece that is attracted by the magnetic force of the magnet piece.

Images