JP5398505B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus that uses an electrophotographic recording system such as a laser printer, a copying machine, or a facsimile.

  2. Description of the Related Art Conventionally, in an image forming apparatus using an electrophotographic method, a toner image on an image carrier is transferred to a belt or a recording medium carried on the belt by a transfer member to which a voltage having a polarity opposite to the charged polarity of the toner is applied. There is a transfer process for electrostatic transfer. As an example of this transfer member, there is a contact transfer member such as a transfer roller which is connected to a high voltage power source and is disposed at a position facing the image carrier via the belt.

  In the image forming apparatus having the above configuration, a portion where the transfer roller and the belt are opposed to each other with a small gap is formed in the vicinity of the contact between the transfer roller and the belt. The portion where the small gap is formed forms an electric field with an unclear boundary, which may be a factor that deteriorates transferability such as scattering of a toner image.

  Based on such a background, a configuration for transferring a toner image with high fidelity and good reproducibility to a belt or a recording medium carried on the belt has been proposed. Specifically, a configuration has been proposed in which a transfer electric field in the transfer portion is stabilized by adjusting a contact surface of the transfer member with respect to the belt using a sheet or film as the transfer member.

JP 2007-156455 A

  However, since the transfer member using the sheet or film rubs against the belt by the movement of the belt, the transfer member and the belt are scraped by repeatedly performing image formation. In addition, toner, paper dust, scraped powder of movable parts accompanying use, etc. easily enter the contact surface side of the belt with the transfer member, and these adhere to the contact surface side of the belt with the transfer member, thereby causing an image. May cause defects.

  An object of the present invention is to suppress image defects caused by deposits adhering to a contact surface side of a belt with a transfer member.

  In order to solve the above problems, the present invention provides an image carrier that carries a toner image, an endless belt that moves in contact with the image carrier, and the image carrier that faces the image carrier across the belt. And a transfer member that transfers a toner image toward the belt. The transfer member contacts the belt without rotating with the belt, and is in contact with the belt. A surface has a sheet member that rubs against the belt when the belt moves, and the sheet member has an opening in a contact surface with the belt.

  According to the present invention, the adhering matter attached to the contact surface side of the belt with the transfer member can be removed by the sheet member having the opening. Thereby, the image defect resulting from the deposit | attachment adhering to the contact surface side with the transfer member of a belt can be suppressed.

Schematic sectional view showing an image forming apparatus Schematic sectional view showing the primary transfer member (A) is a schematic plan view showing the opening shape of the sheet member of Example 1, and (b) is an enlarged view showing the opening shape of the sheet member of Example 1. (A) is a schematic plan view showing the opening shape of the sheet member of Example 2, and (b) is an enlarged view showing the opening shape of the sheet member of Example 2. Table showing the evaluation results of Example 1, Example 2, and Comparative Example

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements 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. Therefore, unless specifically stated otherwise, the scope of the present invention is not intended to be limited thereto.

[Example 1]
Example 1 according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view of the overall configuration of the image forming apparatus. Here, a color printer including a plurality of image forming units (image forming stations) is illustrated as the image forming apparatus.

  The image forming apparatus shown in FIG. 1 includes four image forming stations in which colors of developer images that can be formed are different. Here, the first image forming station is yellow (Y), the second image forming station is magenta (M), the third image forming station is cyan (C), and the fourth image forming station is black (K). It is said. Since the first image forming station to the fourth image forming station have the same configuration except that the color of the developer image that can be formed is different, the first image forming station will be described as an example. In the following description, each component of the yellow (Y) image forming station is denoted by (a). Similarly, the components of each image forming station are denoted by (b) in magenta (M), (c) in cyan (C), and (d) in black (K). Yes.

  In each image forming station, process cartridges 9 (9a, 9b, 9c, 9d) corresponding to the respective colors are detachably mounted. Each process cartridge 9 has substantially the same structure. Each process cartridge 9 has a photosensitive drum 1 (1a, 1b, 1c, 1d) which is an electrophotographic photosensitive member (image carrier), and a process means which acts on each photosensitive drum 1. Here, as process means, charging roller 2 (2a, 2b, 2c, 2d) as charging means, developing unit 8 (8a, 8b, 8c, 8d) as developing means, and cleaning unit 3 (as cleaning means) ( 3a, 3b, 3c, 3d). Each developing unit 8 includes a developing sleeve 4 (4a, 4b, 4c, 4d) and a developer coating blade 7 (7a, 7b, 7c, 7d), and developers (toners) 5 (5a, 5b) having different colors. , 5c, 5d). Each charging roller 2 is connected to a charging bias power source 20 (20a, 20b, 20c, 20d) which is a voltage supply means to the charging roller 2. Similarly, each developing sleeve 4 is also connected to a developing bias power source 21 (21a, 21b, 21c, 21d) that is a voltage supply means to the developing sleeve 4.

  Further, each image forming station is provided with exposure means 11 (11a, 11b, 11c, 11d). Each exposure means 11 is composed of a scanner unit or LED array that scans laser light with a polygon mirror, and a scanning beam 12 (12a, 12b, 12c, 12d) modulated based on an image signal is applied to each photosensitive drum 1. Irradiate.

  The image forming apparatus also includes an intermediate transfer belt 13 that is an endless belt (endless belt). The intermediate transfer belt 13 is disposed so as to contact all four photosensitive drums 1a, 1b, 1c, and 1d. The intermediate transfer belt 13 is supported by three rollers, a secondary transfer counter roller 24 as a stretching member, a driving roller 14, and a tension roller 15, so that an appropriate tension is maintained. By driving the driving roller 14, the intermediate transfer belt 13 moves in the forward direction (in the direction of the arrow in FIG. 1) with respect to the photosensitive drums 1a, 1b, 1c, and 1d at substantially the same speed.

  Further, primary transfer members 10 (10a, 10b, 10c, 10d) are arranged at positions opposed to the respective photosensitive drums 1 (1a, 1b, 1c, 1d) via the intermediate transfer belt 13. Each primary transfer member 10 is connected to a primary transfer power supply 22 (22a, 22b, 22c, 22d) which is a voltage supply means to the primary transfer member 10, and a voltage having a polarity opposite to that of the toner is received from each primary transfer power supply 22. It is to be applied. The intermediate transfer belt 13 moves between the photosensitive drum 1 and the primary transfer member 10. In each primary transfer region where the photosensitive drum 1 and the primary transfer member 10 face each other, the toner image formed on each photosensitive drum 1 is sequentially transferred by the primary transfer member 10 so as to be superimposed on the intermediate transfer belt 13. The

Here, PI having a thickness of 100 μm and a volume resistivity of 10 ¹⁰ Ωcm is used as the intermediate transfer belt 13. Here, PI is used as the intermediate transfer belt 13, but nylon, PET, PEN, PVdF, PEEK, or the like may be used.

  Further, the image forming apparatus performs the secondary transfer in which the secondary transfer counter roller 24 and the secondary transfer roller 25 are opposed to each other via the feeding roller 17 that feeds the recording medium P from the feeding cassette 16 one by one and the belt 13. A registration roller 18 for conveying the recording medium P is provided in the area. Note that the secondary transfer roller 25 is connected to a secondary transfer power source 26. The fixing unit 19 includes a fixing roller and a pressure roller, and fixes the toner image on the recording medium P by applying heat and pressure to the toner image on the recording medium P.

  Next, an image forming operation will be described. When the image forming operation starts, the photosensitive drums 1a to 1d, the intermediate transfer belt 13 and the like start to rotate in the arrow direction at a predetermined process speed. First, at the first image forming station, the photosensitive drum 1a is uniformly charged to the negative polarity by the charging roller 2a by the charging bias power source 20a. Subsequently, an electrostatic latent image according to the image information is formed on the photosensitive drum 1a by the scanning beam 12a irradiated from the exposure unit 11a.

  The toner 5a in the developing unit 8a is charged to a negative polarity by the developer applying blade 7a and applied to the developing sleeve 4a. The developing sleeve 4a is supplied with a bias from a developing bias power source 21a. When the electrostatic latent image formed on the photosensitive drum 1a reaches the developing sleeve 4a, the electrostatic latent image is visualized by negative polarity toner, and the first color (here, yellow) toner image is formed on the photosensitive drum 1a. Is formed.

  The toner image formed on the photosensitive drum 1a is primarily transferred onto the intermediate transfer belt 13 by the action of the primary transfer member 10a. After the primary transfer is completed, the toner remaining on the drum surface is cleaned by the cleaning unit 3a to prepare for the next image formation.

  The second to fourth image forming stations for magenta, cyan, and black are subjected to the same image forming process as the first image forming station for yellow. That is, a toner image of each color is formed on each photosensitive drum, and the toner images of each color are transferred onto the intermediate transfer belt 13 so as to form a multiple image on the intermediate transfer belt 13.

  On the other hand, in accordance with the above-described image forming process, the recording medium P accommodated in the feeding cassette 16 is fed one by one by the feeding roller 17 and conveyed to the registration roller 18. The recording medium P is in contact with a contact portion (formed by the intermediate transfer belt 13 and the secondary transfer roller 25 by the registration roller 18 in synchronization with the multiple image (four color toner image) formed on the intermediate transfer belt 13. (Secondary transfer area). Multiple images (four color toner images) carried on the intermediate transfer belt 13 by the secondary transfer roller 25 to which a voltage having a polarity opposite to that of the toner is applied by the secondary transfer power supply 26 are collectively recorded on the recording medium P. Secondary transferred on top.

  After the secondary transfer is completed, the transfer residual toner remaining on the intermediate transfer belt 13 and the paper dust generated when the recording medium P is conveyed are removed by the belt cleaning unit 27 that is in contact with the intermediate transfer belt 13. , Removed and recovered from the surface. Here, an elastic cleaning blade formed of urethane rubber or the like is used as the belt cleaning means 27.

  The recording medium P after the completion of the secondary transfer is conveyed to the fixing unit 19 where the toner image is fixed. The recording medium P on which the toner image is fixed is discharged out of the image forming apparatus as an image formed product (print, copy).

  Here, the configuration of the primary transfer member will be described in detail with reference to FIG. FIG. 2 is an enlarged cross-sectional view of each primary transfer region. Although the primary transfer area in the first image forming station is illustrated here, the primary transfer areas in the second to fourth image forming stations are configured in the same manner. Hereinafter, the first image forming station will be described as an example.

  In the following description, the short side direction is the moving direction of the intermediate transfer belt, and the long side direction is the direction orthogonal to the moving direction of the intermediate transfer belt.

  As shown in FIG. 2, the primary transfer member 10 a includes a sheet member 32 a and an elastic member 31 a as a pressing member that presses the sheet member 32 a against the intermediate transfer belt 13. The sheet member 32a is sandwiched between the intermediate transfer belt 13 and the elastic member 31a.

  The elastic member 31a is a urethane rubber sponge having a longitudinal width of 230 mm, a lateral width of 5 mm, and a thickness of 5 mm. The hardness of the elastic member 31a is 20 ° with 500 gf of Asker C. The elastic member 31a is electrically insulated. The elastic member 31a used here is urethane rubber, but is not limited thereto, and EPDM, NBR, epichlorohydrin rubber, or the like may be used.

  The elastic member 31a is installed at a position facing the photosensitive drum 1a. The intermediate transfer belt 13 and the sheet member 32a are sandwiched between the elastic member 31a and the photosensitive drum 1a. The elastic member 31a is pressurized with a total pressure of 4.9 N to the photosensitive drum 1a side by a pressure spring (not shown), and stably contacts the sheet member 32a with the intermediate transfer belt 13.

The sheet member 32a is a polyethylene sheet having a longitudinal width of 232 mm, a lateral width of 15 mm, and a thickness of 200 μm. The sheet member 32a has conductivity, and the volume resistivity when applying 100V is 10 ⁴ Ωcm. Here, polyethylene is used as the material of the sheet member 32a, but the material is not limited to this. For example, other materials such as polycarbonate (PC), PVDF, PET, polyimide (PI), vinyl acetate, and polyamide are used. It may be used.

  The sheet member 32a is supported by an upstream portion in the belt moving direction at a position where the sheet member 32a contacts the photosensitive drum 1a via the intermediate transfer belt 13 (transfer nip: contact area B where the drum 1a and the belt 13 in FIG. 2 are in contact). It is supported by a member (not shown). The sheet member 32a receives pressure from the elastic member 31a and is in uniform contact with the back surface of the intermediate transfer belt 13 (the surface on the side in contact with the sheet member 32a). The sheet member 32 a rubs against the belt 13 when the contact surface 32 a 1 contacting the back surface of the intermediate transfer belt 13 moves.

  Further, on the contact surface 32a1 of the sheet member 32a with the intermediate transfer belt 13, the end portion 32a2 on the downstream side in the belt moving direction is located outside the pressing region D where the elastic member 31a presses the sheet member 32a. The end portion 32a2 of the sheet member 32a that protrudes outside the pressing region D of the elastic member 31a is in contact with the back surface of the intermediate transfer belt 13 due to the rigidity of the sheet member 32a.

  The sheet member 32a is connected to the primary transfer power source 22a, and a voltage controlled so that the flowing current becomes a predetermined value during image formation is applied. The current applied to the primary transfer member 10a varies depending on the environment (temperature, humidity) in which the image forming apparatus is used. Further, the sheet member 32 a is in close contact with the back surface of the intermediate transfer belt 13 due to the electrostatic attraction force generated with the application of a voltage for image formation.

  The sheet member 32 a has an opening 100 a on a contact surface 32 a 1 with the intermediate transfer belt 13. Here, the features of the opening 100a of the sheet member 32a will be described with reference to FIG. FIG. 3A is a schematic plan view showing the shape of the sheet member. FIG. 3B is an enlarged view of the opening in the sheet member. Here, the sheet member in the first image forming station is also shown here, but the sheet member in the second to fourth image forming stations is configured similarly.

  As shown in FIG. 3A, the sheet member 32 a has an opening 100 a on the downstream side in the movement direction (arrow A direction) of the intermediate transfer belt 13. The opening 100a has a large number of openings having a predetermined size and shape. Here, each opening 100a is formed of a circle having a radius of 1.8 mm. The openings 100a form a line in which the intervals between the centers of the openings (circles) are arranged at intervals of 6 mm in the longitudinal direction. A plurality of rows (here, two rows) are provided in the belt movement direction with a predetermined interval (a space between the centers of the openings (circles), here, 5.2 mm). . Further, the openings 100a in a plurality of rows are arranged in a staggered manner so that the openings in the rear row are located between the openings in the front row in the belt movement direction.

  As shown in FIG. 3B, the openings 100a in each row in the sheet member 32a have a region J (here, 1.2 mm) where the openings in the front row and the rear rows in the belt movement direction overlap. The opening 100a is provided over the entire length in the longitudinal direction (here, the width in the longitudinal direction is 222 mm), leaving a predetermined length (here, 5 mm) at both ends in the longitudinal direction. Here, the maximum width in the longitudinal direction of the image of the image forming apparatus is 210 mm, and the opening 100 of the sheet member 32 a contacts the back surface of the intermediate transfer belt 13 over the longitudinal width of the image. The opening 100a penetrates perpendicularly to the contact surface between the intermediate transfer belt 13 and the sheet member 32a in the thickness direction of the sheet member 32a. The formation position of the opening 100a is on the downstream side in the belt movement direction from the elastic member 31a. That is, the opening 100a is provided outside the pressing region D where the elastic member 31a presses the sheet member 32a.

  By the action of the opening 100a, the adhered matter adhering to the back surface of the intermediate transfer belt 13 that causes image defects is removed. First, this deposit and the image defect resulting from the deposit will be described. The adhering material is scraped powder by rubbing between the intermediate transfer belt and the transfer member, scraped powder of movable parts in the image forming apparatus, toner, paper powder, and the like. These deposits cause image defects due to local shortage of transfer current at the adhered portion on the back surface of the intermediate transfer belt. In particular, in the configuration in which the intermediate transfer belt and the transfer member rub, the adhering material on the back surface of the intermediate transfer belt repeatedly rubs with the transfer member due to the movement of the intermediate transfer belt, and the transfer member is scraped into a streak shape. There is also. As a result, a non-contact portion is locally generated at a portion where the transfer member is scraped off, and transfer efficiency is lowered, thereby causing a vertical streak-like image defect. Furthermore, these deposits may cause damage to the intermediate transfer belt itself by deforming the intermediate transfer belt into a convex shape at the nip portion. In this case as well, a local non-contact portion is formed at the contact portion between the intermediate transfer belt and the transfer member, and an image defect occurs.

  Next, the operation of the opening 100 provided on the contact surface 32a1 of the sheet member 32a with the intermediate transfer belt 13 as described above will be described in detail. As shown in FIG. 2, the edge (end) 101 a on the downstream side in the belt movement direction of the opening 100 a provided in the sheet member 32 a is counter-directional with respect to the movement direction of the intermediate transfer belt 13 on the back surface of the intermediate transfer belt 13. To touch. The edge 101a on the downstream side of the opening 100a is stably in close contact with the back surface of the intermediate transfer belt 13 by an electrostatic attraction generated by an applied voltage for image formation. The adhering matter adhering to the back surface of the intermediate transfer belt 13 can be scraped off by the edge 101a in close contact with the back surface of the intermediate transfer belt 13.

  The deposit scraped off by the edge 101a on the downstream side of the opening 100a falls into a pocket 102a as a receiving portion provided below the opening 100a and is held in the pocket 102a. As a result, the adhering material once scraped off is prevented from adhering to the back surface of the intermediate transfer belt 13 again. Furthermore, since the opening portion 100a is provided on the downstream side of the region D, the opening portion 100a prevents the primary transfer from being affected.

  With the above-described operation of the opening 100a, even when image formation is repeatedly performed and scraping powder or toner adheres to the back surface of the intermediate transfer belt 13, good transferability can be maintained regardless of the number of sheets used. it can. In this embodiment, the shape of the opening is a circle. However, the present invention is not limited to this, and it goes without saying that the same effect can be achieved in other shapes.

  In order to examine the effect of the image forming apparatus of this example, evaluation was performed using an image forming apparatus having a process speed of 150 mm / sec.

  As a comparative example, an image forming apparatus using a sheet member having the same basic configuration as the above image forming apparatus but having no opening as a transfer member was used.

  As a durability experiment, CLC color laser copier paper (Canon sales, product name) was used for the recording medium P, and the image ratio of each color of C (cyan), M (magenta), Y (yellow), and K (black) was 25%. 50,000 images were printed. The plain paper mode was used as the image forming mode, and the throughput was 18 sheets per minute.

  The evaluation image was sampled at the start of the durability experiment and every 5,000 images formed during the durability experiment. The following were output as evaluation images to be sampled. That is, a solid image (maximum density level image), a halftone image, and a character thin line image are respectively converted into C (cyan), M (magenta), Y (yellow), K (black), R (red), and B (blue). And G (green).

  For the sampled evaluation images, ranking evaluation was performed from the viewpoint of image defects caused by the deposits on the back surface of the intermediate transfer belt 13. As the criteria for ranking, “◯” indicates that no image defect occurred, “Δ” indicates that the image can be confirmed slightly, and “x” indicates that the image can be confirmed. The atmosphere environment in which the experiment was performed is an NN environment having a temperature of 23 ° C. and a humidity of 50%.

  The evaluation results are shown in FIG. In the image forming apparatus of the present embodiment, image defects due to deposits on the back surface of the intermediate transfer belt 13 did not occur up to 80,000 sheets. In addition, it was confirmed that the intermediate transfer belt 13, the sheet member 32, toner, paper powder, and the like are held in the pocket 102 after the durability test. On the other hand, in the image forming apparatus of the comparative example, the image defect due to the adhered matter on the back surface of the intermediate transfer belt 13 did not occur up to 60,000 sheets, but occurred to the extent that it can be slightly confirmed from 70,000 sheets or later. It was confirmed that it deteriorated as the durability experiment progressed.

  As described above, in the image forming apparatus of this embodiment, the opening 100a is provided at a position downstream of the transfer nip portion of the sheet member 32 constituting the transfer member. Thereby, the deposits on the back surface of the intermediate transfer belt 13 can be scraped off. As a result, it is possible to suppress the occurrence of image defects due to deposits on the back surface of the intermediate transfer belt 13. Needless to say, the present embodiment also has the same effect on foreign matters and the like attached to the back surface of the intermediate transfer belt 13 in the manufacturing process of the image forming apparatus.

[Example 2]
A second embodiment according to the present invention will be described with reference to the drawings. The basic configuration and operation of the image forming apparatus of the present embodiment are the same as those of the first embodiment described above. Accordingly, elements having the same functions or configurations as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  The features of the opening 100 of the sheet member 32 in this embodiment will be described with reference to FIG. In this embodiment, the position of the opening 100a of the sheet member 32 is different from the first image forming station to the fourth image forming station, and is not the same.

  FIG. 4A is a schematic plan view showing the shapes of the sheet members 32a, 32b, 32c, and 32d used in this embodiment. The openings 100a, 100b, 100c, and 100d have a large number of openings having a predetermined size and shape. Here, each opening part 100a, 100b, 100c, 100d consists of a circle with a radius of 1.8 mm. FIG. 4B is an enlarged view of the openings 100a, 100b, 100c, and 100d in the sheet members 32a, 32b, 32c, and 32d of each station. The opening 100 of the sheet member 32 of one station has a region J that overlaps with the opening 100 of the sheet member 32 of any other station. Further, by combining the openings 100a, 100b, 100c, and 100d of the four stations, the downstream edge of the opening contacts the back surface of the intermediate transfer belt 13 over the entire width in the longitudinal direction of the image. As a result, the edges of the openings 100a, 100b, 100c, and 100d can scrape deposits on the back surface of the intermediate transfer belt 13 over the entire image width.

  As in this configuration, it is a more advantageous configuration than the first embodiment from the viewpoint of the strength of the sheet member that the opening over the entire image width is divided and formed into a plurality of sheet members 32. Specifically, in this configuration, since the opening per sheet member can be reduced to a quarter of that in the first embodiment, the rigidity of the sheet member is increased compared to the first embodiment, and the image width is reduced. The durability can be further improved while maintaining the effect of removing the deposits over the entire area.

  In order to confirm the effect of this example, the same evaluation as in Example 1 was performed. Evaluation conditions and the like are the same as those in Example 1.

  The evaluation results are shown in FIG. In the image forming apparatus of this example, image defects due to deposits on the back surface of the intermediate transfer belt 13 did not occur up to 100,000 sheets. Further, no deformation such as undulation was observed in the sheet member after the durability test.

  From the above evaluation results, in this example, the number of openings formed in one sheet member can be reduced as compared with Example 1 described above, thereby maintaining the effect of removing the deposits on the back surface of the intermediate transfer belt while maintaining durability. The sex can be further improved.

[Other embodiments]
In the embodiment described above, the opening is disposed on the downstream side of the transfer nip of the sheet member, but the present invention is not limited to this. In the case where the sheet member and the intermediate transfer belt have a contact surface on the upstream side of the transfer nip, the same effect can be exhibited even if an opening is provided on the upstream side of the transfer nip.

  In the above-described embodiments, the case where the belt is an intermediate transfer belt carrying a toner image is shown, but the present invention is not limited to this, and is a case of a transfer belt carrying and transporting a recording medium such as paper. Can exert the same effect.

  In the above-described embodiment, four image forming stations are used. However, the number of used stations is not limited, and may be set as necessary.

  In the above-described embodiment, as a process cartridge that can be attached to and detached from the main body of the image forming apparatus, a process cartridge that integrally includes a photosensitive drum and a charging unit, a developing unit, and a cleaning unit as process units that act on the photosensitive drum. Illustrated. The process cartridge is not limited to this, and may be a cartridge integrally including any one of a charging unit, a developing unit, and a cleaning unit in addition to the photosensitive drum.

  In the above-described embodiments, the printer is exemplified as the image forming apparatus, but the present invention is not limited to this. For example, the image forming apparatus may be another image forming apparatus such as a copying machine or a facsimile machine, or another image forming apparatus such as a multifunction machine combining these functions. By applying the present invention to these image forming apparatuses, Similar effects can be obtained.

1a, 1b, 1c, 1d... Photosensitive drums 10a, 10b, 10c, 10d... Primary transfer member 13... Intermediate transfer belt 31a. 100b, 100c, 100d ... opening 101a ... edge

Claims (4)

An image carrier that carries a toner image, an endless belt that moves in contact with the image carrier, and a toner image transferred from the image carrier to the belt facing the image carrier across the belt. An image forming apparatus having a transfer member,
The transfer member is a member that contacts the belt without rotating together with the belt, and a contact surface that contacts the belt has a sheet member that rubs against the belt when the belt moves,
The image forming apparatus, wherein the sheet member has an opening on a contact surface with the belt.   The transfer member includes a pressing member that presses the sheet member against the belt, and the sheet member includes the opening outside a region where the pressing member presses the sheet member. Item 2. The image forming apparatus according to Item 1.   The image forming apparatus according to claim 1, wherein the sheet member has the opening outside a region where the image carrier contacts the belt.   The said sheet | seat member is provided with the said opening part over the whole region of the direction orthogonal to the moving direction of the said belt in the contact surface with the said belt. The image forming apparatus described in 1.

Images