Image forming apparatus

Abstract

To provide an image forming apparatus that can effectively prevent occurrence of cleaning failure and color shift caused by unevenness of a contact pressure of a cleaning blade to execute stable image formation.SOLUTION: A scraper with different contact pressures in a longitudinal direction against an intermediate transfer belt is provided downstream of a cleaning blade.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus such as a copier, a printer, a facsimile, or a multifunction machine having a plurality of these functions. [Background technology]

[0002] As image forming devices become faster, the mainstream full-color image forming device is a configuration in which multiple image forming units are arranged in parallel corresponding to the belt member, and the image creation process for each color is performed in parallel. For example, in electrophotographic image forming devices, there is a full-color tandem system using an intermediate transfer belt.

[0003] The full-color tandem method is an image forming method that obtains a full-color image by multiple image forming units arranged side by side. Specifically, toner images of different colors formed by each image forming unit are superimposed on an intermediate transfer belt and are primarily transferred, and the toner images on the intermediate transfer belt are then collectively secondary transferred to a recording material. The toner images transferred to the recording material are then fixed by a fixing device. This type of full-color image forming apparatus is equipped with a cleaning device that removes residual toner remaining on the intermediate transfer belt after secondary transfer.

[0004] A cleaning blade made of an elastic material such as rubber bonded to a supporting metal plate is widely used as the cleaning device. In particular, the counter type, in which the cleaning blade is brought into contact with the intermediate transfer belt in the driving direction, is generally adopted because of its high cleaning performance.

[0005] On the other hand, when the recording material comes into contact with the intermediate transfer belt during the secondary transfer, paper dust and fillers may be transferred from the recording material to the intermediate transfer belt. It is known that such paper dust and fillers tend to aggregate at the edge of the cleaning blade, causing cleaning defects.

[0006] Therefore, Patent Document 1 discloses a configuration in which a scraper member is provided downstream of the cleaning blade in the moving direction of the intermediate transfer belt, and the toner that has slipped through the cleaning blade is collected by the scraper. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2002-278319 A Summary of the Invention [Problem to be solved by the invention]

[0008] However, in the configuration of Patent Document 1, since both the cleaning blade and the scraper come into contact with the intermediate transfer belt, the transport load on the intermediate transfer belt increases, and there is a possibility that "color shift" will occur, which deteriorates the registration of a color image.

[0009] The present invention has been made in consideration of these problems, and aims to provide an image forming apparatus that can perform stable image formation by suppressing both poor cleaning and color shift caused by aggregation of paper powder and fillers. [Means for solving the problem]

[0010] The image forming apparatus according to the present invention includes a plurality of image carriers, an intermediate transfer belt onto which toner images are transferred from the plurality of image carriers, and a cleaning member that comes into contact with a surface of the intermediate transfer belt to clean the intermediate transfer belt, the cleaning member including a leaning member having an elastic blade that comes into contact with the surface of the intermediate transfer belt along a width direction that is substantially perpendicular to a moving direction of the intermediate transfer belt, and a first regulating portion that regulates a free length of the elastic blade at a base end side opposite to a free end of the elastic blade in a direction intersecting the width direction of the cleaning member, and a scraper that is disposed downstream of the cleaning member in the moving direction of the intermediate transfer belt and comes into contact with the intermediate transfer belt. In an image forming apparatus having a scraper member, the scraper member comprises a contact member that contacts the intermediate transfer belt and a second regulating portion that regulates the free length of the contact member at a base end side opposite the free end of the contact member in a direction intersecting the width direction of the scraper member, the free length of a first region in the center of the width direction of the cleaning member is longer than the free length of a second region on the end side of the width direction of the cleaning member, and the scraper member is configured so that the contact pressure of a region corresponding to the first region in the width direction of the scraper member is higher than the contact pressure of a region corresponding to the second region.

[0011] Another image forming apparatus according to the present invention includes a plurality of image carriers, an intermediate transfer belt onto which toner images are transferred from the plurality of image carriers, a cleaning member having a contact portion that contacts a surface of the intermediate transfer belt and cleans the intermediate transfer belt, and a scraper member that is disposed downstream of the cleaning member in a moving direction of the intermediate transfer belt and contacts the intermediate transfer belt, the contact portion of the cleaning member being a first contact portion that contacts the intermediate transfer belt in a first region of the intermediate transfer belt. The scraper member is characterized in that it comprises a contact portion and a second contact portion that contacts a second region of the intermediate transfer belt outer than the first region and adjacent to the first region in a width direction approximately perpendicular to the movement direction of the intermediate transfer belt, and is configured so that the surface hardness of the second contact portion is higher than the surface hardness of the first contact portion, and the scraper member is configured so that the contact pressure of a predetermined region including the boundary between the first region and the second region in the width direction of the scraper member is higher than the contact pressure of an inner region that is inner than the predetermined region.

[0012] Another image forming apparatus according to the present invention includes a plurality of image carriers, an intermediate transfer belt onto which a toner image is transferred from the plurality of image carriers, and a cleaning member that comes into contact with a surface of the intermediate transfer belt to clean the intermediate transfer belt, the cleaning member including an elastic blade that comes into contact with the surface of the intermediate transfer belt along a width direction that is substantially perpendicular to a moving direction of the intermediate transfer belt, and a first regulating portion that regulates a free length of the elastic blade at a base end side on the opposite side to a free end of the elastic blade in a direction intersecting the width direction of the cleaning member. and a scraper member disposed downstream of the cleaning member in a moving direction of the intermediate transfer belt and in contact with the intermediate transfer belt, the scraper member including a contact member in contact with the intermediate transfer belt and a second regulating portion regulating a free length of the contact member at a base end side opposite to a free end of the contact member in a direction intersecting the width direction of the scraper member, the cleaning member having a contact pressure at a center part in the width direction higher than a contact pressure at an end part in the width direction, The contact member is characterized in that a free length of a central portion in the width direction of the contact member is configured to be shorter than a free length of an end portion of the contact member in the width direction. Effect of the Invention

[0013] According to the present invention, it is possible to effectively prevent poor cleaning and color shift caused by the aggregation of paper powder and fillers, and to perform stable image formation. [Brief description of the drawings]

[0014] [Figure 1] 1 is a schematic diagram of an image forming apparatus according to an embodiment of the present invention; [Diagram 2] FIG. 11 is an explanatory diagram of the longitudinal distribution of the contact pressure of the intermediate transfer member cleaning blade 102 that has been subjected to edge hardening treatment. [Diagram 3] 11 is an explanatory diagram of the longitudinal distribution of the contact pressure of the intermediate transfer member cleaning blade 102 having an increased end free length. FIG. [Figure 4]10 is an explanatory diagram of the longitudinal distribution of the contact pressure of the intermediate transfer member cleaning blade 102 in a deflected state. FIG. [Diagram 5] 1A is a schematic diagram of a scraper 116 in the first embodiment, and FIG. 1B is an explanatory diagram of contact pressure distribution. [Figure 6] 11A is a schematic diagram of a scraper 116 in the second embodiment, and FIG. 11B is an explanatory diagram of contact pressure distribution. [Figure 7] 11A is a schematic diagram of a scraper 116 in the third embodiment, and FIG. 11B is an explanatory diagram of contact pressure distribution. [Figure 8] 13A is a schematic diagram of a scraper 116 in the fourth embodiment, and FIG. 13B is an explanatory diagram of contact pressure distribution. [Figure 9] 13A is a schematic diagram of a scraper 116 in the fifth embodiment, and FIG. 13B is an explanatory diagram of contact pressure distribution. [Figure 10] 13A is a schematic diagram of a scraper 116 in the sixth embodiment, and FIG. 13B is an explanatory diagram of contact pressure distribution. [Figure 11] 13A is a schematic diagram of a scraper 116 in the sixth embodiment, and FIG. 13B is an explanatory diagram of contact pressure distribution. [Figure 12] 1A and 1B are diagrams illustrating the occurrence of cleaning defects and color misregistration. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In this embodiment, only the main parts related to the formation / transfer of a toner image will be described, but the present invention can be embodied in various applications such as printers, various printing machines, copiers, FAX machines, and multifunction machines by adding necessary devices, equipment, and housing structures.

[0016] <Description of Image Forming Apparatus> Fig. 1 is an explanatory diagram of the configuration of an image forming apparatus. As shown in Fig. 1, image forming apparatus 100 is a tandem type intermediate transfer type full-color printer in which image forming units 109Y, 109M, 109C, and 109Bk for yellow, magenta, cyan, and black are arranged along intermediate transfer belt (ITB) 101.

[0017] In image forming unit 109Y, a yellow toner image is formed on a photosensitive drum serving as an image carrier, and this yellow toner image is transferred to intermediate transfer belt 101 serving as another image carrier. In image forming unit 109M, a magenta toner image is formed in a similar procedure to that of image forming unit 109Y, and is transferred and superimposed on the yellow toner image on intermediate transfer belt 101. In image forming units 109C and 109Bk, a cyan toner image and a black toner image are formed in a similar procedure to that of image forming unit 109Y, and are transferred and superimposed in order onto intermediate transfer belt 101.

[0018] The four-color toner images carried on the intermediate transfer belt 101 are transported to a secondary transfer section T2 and are collectively (secondarily) transferred onto a recording material P. The recording material P onto which the four-color toner images have been (secondarily) transferred is separated from the intermediate transfer belt 101 by curvature and sent to a fixing device 112. The fixing device 112 heats and presses the recording material P with a fixing roller 112a and a pressure roller 112b to melt the toner and fix the image onto the surface. Thereafter, the recording material P is discharged outside the apparatus body.

[0019] The image forming units 109Y, 109M, 109C, and 109Bk are substantially identical in configuration, except that the colors of toner used in the respective developing devices are different: yellow, magenta, cyan, and black. In the following, the toner image forming process of the black image forming unit 109Bk will be described, and duplicated descriptions of the other image forming units 109Y, 109M, and 109C will be omitted. Also, the symbols Y, M, C, and Bk representing the toner colors yellow, magenta, cyan, and black will be omitted as appropriate.

[0020] The image forming unit 109Bk includes a photosensitive drum 103, a charging roller 104, an exposure device 105, a developing device 106, a primary transfer roller 107, and a photosensitive drum cleaning blade 108 arranged around the photosensitive drum 103.

[0021] The photosensitive drum 103 has a photosensitive layer with a negative charging polarity formed on the surface of an aluminum tube, and is driven by a motor (not shown) in the direction of the arrow at a process speed of 0.3 m / s.

[0022] A negative DC voltage is applied to the charging roller 104, which negatively charges the surface of the photosensitive drum 103. The exposure device 105 writes an electrostatic image of an image on the surface of the photosensitive drum 103 by scanning a laser beam that is ON-OFF modulated based on scanning line image data obtained by developing a black separated color image, using a rotating mirror.

[0023] The developing device 106 frictionally charges a two-component developer containing a negatively charged non-magnetic toner and a magnetic carrier using an agitating member. The developer is transported by a transport member and carried on a developing sleeve. The developer carried on the developing sleeve has its thickness regulated by a regulating blade, and is then transported to a portion facing the photosensitive drum 103. The developing sleeve is held at a predetermined distance from the photosensitive drum 103. By applying an oscillating voltage, which is an AC voltage superimposed on a negative DC voltage, to the developing sleeve, the negatively charged toner is transferred to the exposed portion of the photosensitive drum 103, which has become relatively positive, and the electrostatic image is reversed and developed.

[0024] The toner used in this embodiment may be a known toner in which a coloring material, a charge control material, etc., is added to a binder resin. The toner may preferably have a volume average particle size of 5 μm or more and 15 μm or less. In this embodiment, toner with a volume average particle size of 6 μm is used for all colors of yellow, magenta, cyan, and black.

[0025] The primary transfer roller 107 forms a primary transfer portion T1 between the photosensitive drum 103 and the intermediate transfer belt 101. By applying a positive DC voltage to the primary transfer roller 107, the toner image carried on the photosensitive drum 103 is primarily transferred to the intermediate transfer belt 101.

[0026] The photoconductor cleaning blade 108 comes into contact with the photoconductor drum 103 so as to face the driving direction of the photoconductor drum 103, and collects the untransferred toner remaining on the photoconductor drum 103. The photoconductor cleaning blade 108 is composed of a plate-shaped elastic member and a supporting metal plate, and the elastic member is made of, for example, urethane rubber with a hardness of 77° (JIS-A) and a thickness of 2 mm.

[0027] The secondary transfer roller 111 comes into contact with the outer surface of the intermediate transfer belt 101 at a position downstream of the image forming unit 109Bk in the movement direction of the intermediate transfer belt 101 and upstream of the intermediate transfer body cleaning blade 102. The secondary transfer roller 111 comes into contact with the intermediate transfer belt 101, the inner surface of which is supported by an opposing roller (drive roller) 110, to form a secondary transfer portion T2. ​​By applying a positive DC voltage to the secondary transfer roller 111, the full-color toner image carried on the intermediate transfer belt 101 is secondarily transferred to the recording material P.

[0028] The intermediate transfer member cleaning blade 102 as a cleaning member abuts against the intermediate transfer belt 101 in the moving direction thereof, facing the tension roller 115, and collects the untransferred toner remaining on the intermediate transfer belt 101. The intermediate transfer member cleaning blade 102 is composed of a plate-shaped elastic member as an elastic blade that abuts against the surface of the intermediate transfer belt 101 along the width direction that is approximately perpendicular to the moving direction of the surface of the intermediate transfer belt 101, and a supporting sheet metal. As the elastic member, for example, urethane rubber having a hardness of 77° (JIS-A) and a thickness of 2 mm is used.

[0029] Furthermore, the supporting metal plate, which serves as a restricting portion for restricting the free length of the elastic member, restricts the free length of the elastic member on the base end side opposite to the free end of the elastic member.

[0030] The scraper 116 as a scraper member is provided downstream of the intermediate transfer member cleaning blade 102 in the moving direction (rotation direction) of the intermediate transfer belt 101 and upstream of the image forming unit 109Y so as to face the moving direction of the intermediate transfer belt 101. The scraper 116 contacts the intermediate transfer belt 101 to collect the transfer residual toner remaining on the intermediate transfer belt 101. The scraper 116 is composed of a plate-shaped inelastic member 116a as a contact member and a support member 116b. Metal or resin is used as the plate-shaped inelastic member 116a. The support member 116b is a regulating portion that regulates the free length of the inelastic member 116a in a direction intersecting with the width direction of the inelastic member 116a. The support member 116b regulates the free length of the inelastic member 116a at the base end side opposite to the free end of the inelastic member 116a.

[0031] In this embodiment, the scraper 116 is brought into contact with the intermediate transfer belt 101 opposite the tension roller 115, but the opposing member may be a separate member, or the scraper 116 may be brought into contact with the intermediate transfer belt 101 at a position where there is no opposing member.

[0032] The intermediate transfer belt 101 is a belt member that is driven to be transported in the direction of the arrow R, and is tensioned by a drive roller 110 that is a drive member, tension rollers 113 and 114 that are tension members, and a tension roller 115 that applies a predetermined tension to the intermediate transfer belt 101. The drive roller 110 also functions as a secondary transfer inner roller disposed in the secondary transfer portion T2. ​​However, the number of rollers that tension the intermediate transfer belt 101 is not limited to the configuration in FIG. 1.

[0033] <Explanation of cleaning failure> At the secondary transfer portion T2, when the recording material P comes into contact with the intermediate transfer belt 101, paper powder and fillers may be transferred from the recording material P to the intermediate transfer belt 101. These paper powder and fillers tend to aggregate at the edge of the intermediate transfer member cleaning blade 102, and depending on the type of recording material, the aggregates may push up the intermediate transfer member cleaning blade 102, causing poor cleaning.

[0034] In addition, the contact pressure of the intermediate transfer body cleaning blade 102 against the intermediate transfer belt 101 is uneven in the longitudinal direction as shown in FIG. 2. The ends of the intermediate transfer body cleaning blade 102 are subjected to hardening treatment 102b to prevent the blade from rolling over from the ends. That is, the surface hardness of both longitudinal ends of the intermediate transfer body cleaning blade 102 is higher than the surface hardness of the longitudinal center of the intermediate transfer body cleaning blade 102. Therefore, the contact pressure of the intermediate transfer body cleaning blade 102 against the intermediate transfer belt 101 is lower in the longitudinal center of the intermediate transfer body cleaning blade 102 than at the ends. In this case, the portion where the contact pressure is lowest is the boundary region between the hardened width and the non-hardened width.

[0035] Similarly, to prevent the blade from turning over, the supporting metal plate of the intermediate transfer member cleaning blade 102 may be configured to have a cutout. That is, as shown in Fig. 3, the free length of the intermediate transfer member cleaning blade 102 at the longitudinal ends may be longer than that at the longitudinal center. Even in such a case, the contact pressure differs in the longitudinal direction (sometimes called contact unevenness).

[0036] Also, as shown in FIG. 4, the contact pressure of the intermediate transfer member cleaning blade 102 at the center portion may become lower than that at the longitudinal ends due to bending of the supporting metal plate.

[0037] This contact unevenness results in a difference in the amount of toner that passes through the intermediate transfer member cleaning blade.More toner passes through in areas with low contact pressure, and less toner passes through in areas with high contact pressure.

[0038] Here, any toner that has slipped past the intermediate transfer member cleaning blade 102 due to the aggregation of paper powder or filler is collected by the scraper 116, so that the toner that has slipped past the intermediate transfer member cleaning blade 102 does not soil the image.

[0039] <Explanation of color shift> However, when both the intermediate transfer body cleaning blade 102 and the scraper 116 come into contact with the intermediate transfer belt 101, the driving load on the intermediate transfer belt 101 increases, and this may cause a "color shift" that deteriorates the registration of a color image.

[0040] Meanwhile, as described above, in the portion corresponding to the region where the contact pressure is high in the longitudinal direction of the intermediate transfer member cleaning blade 102, cleaning defects in the intermediate transfer member cleaning blade 102 due to aggregation of paper powder and filler are unlikely to occur. Therefore, in the portion corresponding to the region where the contact pressure is high in the longitudinal direction of the intermediate transfer member cleaning blade 102, it is possible to set the contact pressure of the scraper 116 against the intermediate transfer belt 101 low. By providing such a portion with low contact pressure, the total pressure over the entire longitudinal area of ​​the scraper 116 can be reduced, thereby suppressing the occurrence of color misregistration.

[0041] As described above, by using a scraper with a low contact pressure set in the area corresponding to the area where the contact pressure is high in the longitudinal direction of the intermediate transfer member cleaning blade 102, it is possible to suppress both poor cleaning and color shift caused by the aggregation of paper powder and filler. In the following, in the examples, a specific configuration for setting the scraper contact pressure partially low will be described.

[0042] [Example 1] 2, the end of the intermediate transfer member cleaning blade 102 is subjected to a hardening treatment 102b to prevent the blade from rolling over from the end. That is, the intermediate transfer member cleaning blade 102 has a first contact portion (non-hardened treated portion) that contacts the center portion (first region) of the intermediate transfer belt 101 in the width direction. The intermediate transfer member cleaning blade 102 also has a second contact portion (hardened treated portion) that contacts the end portion (second region) of the intermediate transfer belt 101 in the width direction.

[0043] The first contact portion (non-hardening processing portion) and the second contact portion (hardening processing portion) are arranged adjacent to each other in the width direction approximately perpendicular to the moving direction of the intermediate transfer belt 101, and the surface hardness of the second contact portion is higher than that of the first contact portion.

[0044] Fig. 5(a) is a schematic diagram of the scraper 116 in this embodiment, and Fig. 5(b) is an explanatory diagram of the contact pressure distribution of the scraper 116. The scraper 116 in this embodiment includes a non-elastic member 116a configured such that a free end thereof contacts the intermediate transfer belt 101, and a support member 116b that supports the non-elastic member 116a.

[0045] As shown in FIG. 5(a), the scraper 116 in this embodiment has a longitudinal distribution in the free length (length from the adhesive part with the support member 116b to the free end) of the non-elastic member 116a depending on the shape of the support member 116b. As shown in FIG. 5(b), the support member 116b is shaped so that the free length of a portion (predetermined area) corresponding to the boundary area (boundary part) between the intermediate transfer cleaning blade 102a and the edge hardening processing part 102b is shortened. This allows the contact pressure of the non-elastic member 116a in the portion corresponding to the boundary area of ​​the intermediate transfer cleaning blade 102 using the edge hardening processing to be set higher than the contact pressure of the non-elastic member 116a in the other portion. That is, in the width direction of the scraper 116, the contact pressure of a predetermined area corresponding to the boundary area between the intermediate transfer cleaning blade 102a and the edge hardening processing part 102b is higher than the contact pressure of the inner area that is located inside the boundary area. Further, the contact pressure of the scraper 116 in a predetermined region corresponding to the boundary region between the intermediate transfer cleaning blade 102a and the end hardening processing portion 102b in the width direction is higher than the contact pressure of an outer region located further outward.

[0046] [Example 2] The intermediate transfer member cleaning blade 102 in this embodiment has the same configuration as that in the first embodiment. That is, a hardening treatment 102b is applied to prevent the blade from turning over. FIG. 6(a) is a schematic diagram of the scraper 116 in this embodiment, and FIG. 6(b) is an explanatory diagram of the contact pressure distribution of the scraper 116. As shown in FIG. 6(a), the scraper 116 in this embodiment has a longitudinal distribution in thickness. As shown in FIG. 6(b), the thickness of the scraper 116 is thicker in a portion corresponding to the boundary region of the end effect processing portion of the intermediate transfer cleaning blade 102. This allows the contact pressure of the scraper 116 in the portion corresponding to the boundary region of the intermediate transfer cleaning blade 102 using the end effect processing to be set higher than the contact pressure of the scraper 116 in the other portion.

[0047] [Example 3] The intermediate transfer member cleaning blade 102 in this embodiment has the same configuration as that in the first embodiment. That is, a hardening treatment 102b is applied to prevent the blade from turning over. FIG. 7(a) is a schematic diagram of the scraper 116 in this embodiment, and FIG. 7(b) is an explanatory diagram of the contact pressure distribution of the scraper 116. As shown in FIG. 6(a), a longitudinal distribution is provided in the contact area of ​​the scraper 116 in this embodiment. As shown in FIG. 7(b), the scraper 116 is contacted only in the portion corresponding to the boundary area of ​​the end effect processing portion of the intermediate transfer cleaning blade 102. This results in a configuration having a scraper for preventing slipping only in the portion corresponding to the boundary area of ​​the intermediate transfer cleaning blade 102 using the end effect processing, and the total longitudinal pressure that causes color shifts can be reduced.

[0048] [Example 4] In this embodiment, the intermediate transfer cleaning blade 102 has a first free length in a first region on the central side in the longitudinal direction of the intermediate transfer cleaning blade 102 due to the shape of the supporting metal plate that supports the intermediate transfer cleaning blade 102. Also, the free length of a second region on an end side in the longitudinal direction of the intermediate transfer cleaning blade 102 is a second length that is longer than the first length.

[0049] FIG. 8(a) is a schematic diagram of the scraper 116 in this embodiment, and FIG. 8(b) is an explanatory diagram of the contact pressure distribution of the scraper 116. As shown in FIG. 8(a), the scraper 116 in this embodiment has a longitudinal distribution in the free length (length from the bonding part with the support member 116b to the free end) of the inelastic member 116a due to the shape of the support member 116b. As shown in FIG. 8(b), the support member 116b is shaped so that the free length of the scraper 116 in the portion corresponding to the free length increase region of the end of the intermediate transfer cleaning blade 102 is shortened. That is, the free length of the first region on the end side of the scraper 116 in the longitudinal direction is a first length, and the free length of the second region on the center side of the scraper 116 in the longitudinal direction is a second length shorter than the first length. This allows the contact pressure of the scraper 116 in the portion corresponding to the boundary region of the intermediate transfer cleaning blade 102 using the edge effect treatment to be set higher than the contact pressure of the scraper 116 in the other portion.

[0050] [Example 5] The intermediate transfer member cleaning blade 102 of this embodiment has a different free length, as in the fourth embodiment. FIG. 9(a) is a schematic diagram of the scraper 116 in this embodiment, and FIG. 9(b) is an explanatory diagram of the contact pressure distribution of the scraper 116. As shown in FIG. 9(a), the scraper 116 in this embodiment has a longitudinal distribution in thickness. As shown in FIG. 9(b), the thickness of the scraper 116 is thicker in a portion corresponding to the end free length increase region of the intermediate transfer cleaning blade 102. This allows the contact pressure of the scraper 116 in the portion corresponding to the end free length increase region of the intermediate transfer cleaning blade 102 using the end effect processing to be set higher than the contact pressure of the scraper 116 in the other portions.

[0051] [Example 6] 4, the free length of the intermediate transfer member cleaning blade 102 in this embodiment is constant in the longitudinal direction of the intermediate transfer member cleaning blade 102. In this embodiment, the contact pressure of the central portion of the intermediate transfer member cleaning blade 102 is lower than that of the longitudinal ends due to bending of the supporting metal plate. Therefore, in this embodiment, the free length of the scraper 116 is configured to differ in the longitudinal direction of the scraper 116 as shown in FIG.

[0052] FIG. 10(a) is a schematic diagram of the scraper 116 in this embodiment, and FIG. 10(b) is an explanatory diagram of the contact pressure distribution of the non-elastic member 116a. As shown in FIG. 10(a), the scraper 116 in this embodiment has a longitudinal distribution in the free length (the length from the adhesive part with the support member 116b to the free end) of the non-elastic member 116a due to the shape of the support member 116b. As shown in FIG. 10(b), the support member 116b is shaped so that the free length of the non-elastic member 116a in the portion corresponding to the bending region of the end of the intermediate transfer cleaning blade 102 is shortened. This allows the contact pressure of the non-elastic member 116a in the portion corresponding to the bending region of the intermediate transfer cleaning blade 102 to be set higher than the contact pressure of the non-elastic member 116a in the other portions.

[0053] [Example 7] In the present embodiment, the free length of the intermediate transfer member cleaning blade 102 is constant in the longitudinal direction of the intermediate transfer member cleaning blade 102, as in the sixth embodiment. FIG. 11(a) is a schematic diagram of the scraper 116 in this embodiment, and FIG. 11(b) is an explanatory diagram of the contact pressure distribution of the scraper 116. As shown in FIG. 11(a), the scraper 116 in this embodiment has a longitudinal distribution in thickness. As shown in FIG. 11(b), the thickness of the scraper 116 is thicker in the portion corresponding to the bending region of the intermediate transfer cleaning blade 102. This allows the contact pressure of the scraper 116 in the portion corresponding to the bending region of the intermediate transfer cleaning blade 102 to be set higher than the contact pressure of the scraper 116 in the other portions.

[0054] <Explanation of cleaning failure and color misalignment occurrence> The scrapers 116 having the configurations of Examples 1, 2, 3, 4, 5, and 6 were mounted on the image forming apparatus 100, and a continuous paper feed test was carried out to confirm the effects of the present invention. In addition, the continuous paper feed test was also carried out with a configuration without a scraper as Comparative Example 1, a configuration using a scraper with a low contact pressure set over the entire lengthwise area as Comparative Example 2, and a configuration using a scraper with a high contact pressure set over the entire lengthwise area as Comparative Example 3.

[0055] FIG. 6 shows the occurrence of cleaning failures and color shifts in the continuous paper feed test. As shown in FIG. 6, neither cleaning failures nor color shifts occurred in the configurations of Example 1, Example 2, Example 3, Example 4, Example 5, and Example 6. In the configuration of Comparative Example 1, no color shifts occurred, but cleaning failures occurred in the areas where the contact pressure of the intermediate transfer cleaning blade 102 was low, and minor cleaning failures occurred in the areas where the contact pressure was high. In the configuration of Comparative Example 2, no color shifts occurred, but minor cleaning failures occurred in the areas where the contact pressure of the intermediate transfer cleaning blade 102 was low, and no cleaning failures occurred in the areas where the contact pressure was high. In addition, in the configuration of Comparative Example 3, no cleaning failures occurred, but color shifts occurred.

[0056] From the above results, it was confirmed that by using a scraper 106 with a high contact pressure set corresponding to the areas of the intermediate transfer cleaning blade 102 with low contact pressure, both poor cleaning and color shift due to aggregation of paper powder and fillers can be suppressed. [Explanation of symbols]

[0057] 100 Image forming device 101 Intermediate transfer belt 102 Intermediate transfer member cleaning blade 102a Unhardened portion of intermediate transfer member cleaning blade 102b Hardened portion of intermediate transfer member cleaning blade 103 Photosensitive drum 104 Charging roller 105 Exposure equipment 106 Developing device 107 Primary transfer roller 108 Photoconductor cleaning blade 109Y, 109M, 109C, 109Bk Image forming unit 110 Drive roller 111 Secondary transfer roller 112 Fixing device 113, 114 Tension roller 115 tension roller, 116 Scraper 116a Scraper non-elastic member 116b Scraper support member

Claims

1. A plurality of image carriers; an intermediate transfer belt onto which toner images are transferred from the plurality of image carriers; a cleaning member that comes into contact with a surface of the intermediate transfer belt to clean the intermediate transfer belt, the cleaning member comprising: an elastic blade that comes into contact with the surface of the intermediate transfer belt along a width direction that is substantially perpendicular to a moving direction of the intermediate transfer belt; and a first regulating portion that regulates a free length of the elastic blade at a base end side on the opposite side to a free end of the elastic blade in a direction that intersects with the width direction of the cleaning member; an image forming apparatus including a scraper member disposed downstream of the cleaning member in a moving direction of the intermediate transfer belt and in contact with the intermediate transfer belt, the scraper member including a contact member that contacts the intermediate transfer belt and a second regulating portion that regulates a free length of the contact member on a base end side on a side opposite to a free end of the contact member in a direction intersecting with the width direction of the scraper member, a free length of a first region at a center in the width direction of the cleaning member is longer than a free length of a second region at an end side in the width direction of the cleaning member, An image forming apparatus characterized in that the scraper member is configured so that, in the width direction of the scraper member, the contact pressure of an area corresponding to the first area is higher than the contact pressure of an area corresponding to the second area.

2. 2. The image forming apparatus according to claim 1, wherein a free length of the region of the contact member corresponding to the first region is shorter than a free length of the region of the contact member corresponding to the second region.

3. A plurality of image carriers; an intermediate transfer belt onto which toner images are transferred from the plurality of image carriers; a cleaning member that includes a contact portion that contacts a surface of the intermediate transfer belt and cleans the intermediate transfer belt; a scraper member disposed downstream of the cleaning member in a moving direction of the intermediate transfer belt and in contact with the intermediate transfer belt, the contact portion of the cleaning member includes a first contact portion that contacts the intermediate transfer belt in a first region of the intermediate transfer belt, and a second contact portion that contacts a second region of the intermediate transfer belt that is adjacent to the first region and outside the first region in a width direction substantially perpendicular to a moving direction of the intermediate transfer belt, and is configured such that a surface hardness of the second contact portion is higher than a surface hardness of the first contact portion; An image forming apparatus characterized in that the scraper member is configured so that the contact pressure of a specified area, including the boundary between the first area and the second area, in the width direction of the scraper member is higher than the contact pressure of an inner area that is more inward than the specified area.

4. 4. The image forming apparatus according to claim 3, wherein the scraper member is configured such that the contact pressure of an outer region, which is outside the specified region in the width direction of the scraper member, is lower than the contact pressure of the specified region.

5. 2. The image forming apparatus according to claim 1, wherein the scraper member is configured such that, in the width direction of the scraper member, the contact pressure of an inner region that is inside the specified region is lower than the contact pressure of an outer region that is outside the specified region.

6. A plurality of image carriers; an intermediate transfer belt onto which toner images are transferred from the plurality of image carriers; a cleaning member that comes into contact with a surface of the intermediate transfer belt to clean the intermediate transfer belt, the cleaning member comprising: an elastic blade that comes into contact with the surface of the intermediate transfer belt along a width direction that is substantially perpendicular to a moving direction of the intermediate transfer belt; and a first regulating portion that regulates a free length of the elastic blade at a base end side on the opposite side to a free end of the elastic blade in a direction that intersects with the width direction of the cleaning member; an image forming apparatus including a scraper member disposed downstream of the cleaning member in a moving direction of the intermediate transfer belt and in contact with the intermediate transfer belt, the scraper member including a contact member that contacts the intermediate transfer belt and a second regulating portion that regulates a free length of the contact member on a base end side on a side opposite to a free end of the contact member in a direction intersecting with the width direction of the scraper member, the cleaning member has a contact pressure at a center portion in the width direction that is higher than a contact pressure at an end portion in the width direction; 13. An image forming apparatus, comprising: a contact member having a central portion having a free length in the width direction that is shorter than a free length of an end portion of the contact member in the width direction.

Images