Electrophotographic belt and electrophotographic image forming apparatus

Abstract

To provide a belt for electrophotography that is continuously excellent in toner cleaning performance and excellent in sensing characteristics.SOLUTION: A belt for electrophotography has an endless shape, and a plurality of grooves extending in a circumferential direction of the belt for electrophotography are provided in an outer surface of the belt for electrophotography. The outer surface comprises a first area in which the number of the grooves is n at least in a direction orthogonal to the circumferential direction of the belt for electrophotography, and a second area in which the number of the grooves is larger than n at least in the direction orthogonal to the circumferential direction of the belt for electrophotography. The grooves present in the second area include first grooves whose width is gradually reduced toward a first circumferential direction of the belt for electrophotography, and second grooves adjacent to the first groove and whose width is gradually reduced toward a second circumferential direction opposite to the first circumferential direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to electrophotographic belts, such as transport transfer belts and intermediate transfer belts, used in electrophotographic image forming apparatuses such as copying machines and printers, and to electrophotographic image forming apparatuses. [Background technology]

[0002] In electrophotographic image forming apparatuses, for example, an electrophotographic belt is used as an intermediate transfer belt that temporarily holds a toner image. Residual toner on the electrophotographic belt is cleaned using a cleaning blade made of an elastic material such as urethane rubber. In response to the recent demand for even higher image quality in electrophotographic image forming apparatuses, there has been a demand for electrophotographic belts that exhibit stable cleaning properties.

[0003] Patent Document 1 discloses a technology for suppressing wear between the belt and a cleaning blade and stably removing residual toner over a long period of time by providing a plurality of fine grooves extending in the circumferential direction on the outer surface of an electrophotographic belt. The belt is configured with a first region having n grooves in a direction perpendicular to the circumferential direction of the belt, and a second region having more than n grooves. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-191568 Summary of the Invention [Problem to be solved by the invention]

[0005] According to the inventors' investigations, the following was confirmed regarding the electrophotographic belt disclosed in Patent Document 1: Wear of the cleaning blade at the contact portion with the electrophotographic belt can be effectively suppressed, and as a result, residual toner is reliably removed from the outer surface, which is the toner image bearing surface, even after long-term use. However, during the investigations, it was found that, as shown in Figure 4, the amount of specularly reflected light from the second region may decrease significantly as the number of grooves in the direction perpendicular to the circumferential direction increases.

[0006] In an electrophotographic image forming apparatus capable of forming color images, the following control may be performed to achieve high color reproducibility. That is, a color misregistration correcting toner image (hereinafter simply referred to as a "correcting toner image") may be formed on an intermediate transfer belt, the correcting toner image may be detected by an optical sensor, and control for correcting color misregistration may be performed based on the detection result. The optical sensor detects the correcting toner image using the difference (contrast) between the amount of light reflected from an area where the correcting toner image is not formed and the amount of light reflected from an area where the correcting toner image is formed. Therefore, in the electrophotographic belt according to the invention described in Patent Document 1, if the amount of specularly reflected light from the second region decreases, the contrast in the second region decreases compared to the contrast in the first region. This may result in an inaccurate detection of the correcting toner image in the second region. One aspect of the present disclosure is to provide an electrophotographic belt having two regions (first region and second region) with different numbers of grooves in the circumferential direction, and capable of ensuring a sufficient amount of specularly reflected light from the second region with a larger number of grooves. Another aspect of the present disclosure is to provide an electrophotographic image forming apparatus capable of stably forming high-quality electrophotographic images. [Means for solving the problem]

[0007] According to one aspect of the present disclosure, An electrophotographic belt having an endless shape, a plurality of grooves extending in the circumferential direction of the electrophotographic belt are provided on the outer surface of the electrophotographic belt; The outer surface comprises at least a first region in which the number of grooves in a direction perpendicular to the circumferential direction of the electrophotographic belt is n; a second region in which the number of the grooves in a direction perpendicular to the circumferential direction of the electrophotographic belt is greater than n, The groove in the second region is a first groove whose width gradually decreases in a first circumferential direction of the electrophotographic belt; and a second groove adjacent to the first groove, the width of which gradually decreases in a second circumferential direction opposite to the first circumferential direction (n represents an integer of 1 or greater). According to another aspect of the present disclosure, there is provided an electrophotographic image forming apparatus including an endless intermediate transfer belt and a cleaning member in contact with the outer peripheral surface of the intermediate transfer belt, wherein the intermediate transfer belt is the electrophotographic belt described above. [Effects of the Invention]

[0008] According to one aspect of the present disclosure, an electrophotographic belt can be obtained that has two regions (first region and second region) with different numbers of grooves in a direction perpendicular to the circumferential direction, and that can ensure a sufficient amount of specularly reflected light from the second region, which has a greater number of grooves than the first region. According to another aspect of the present disclosure, an electrophotographic image forming apparatus can be obtained that can stably form high-quality electrophotographic images. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2(a) is a schematic diagram showing the configuration of the surface of an electrophotographic belt based on the present disclosure, and FIG. 2(b) is a partially enlarged view illustrating the state of grooves in a second region. [Figure 2] 1 is a schematic diagram showing a cross section of a first region of an electrophotographic belt according to the present disclosure, taken in a direction perpendicular to the circumferential direction. [Figure 3]FIG. 3 is a schematic view showing a cross section in a direction perpendicular to the circumferential direction in a second region of the electrophotographic belt according to the present disclosure. [Figure 4] FIG. 10 is an explanatory diagram of the specular reflection sensor output relative to the number of grooves per unit length in a direction perpendicular to the circumferential direction. [Figure 5] FIG. 10 is an explanatory diagram of the state of light reflection from the surface of a belt having grooves. [Figure 6] 1 is a schematic diagram showing an example of the configuration of an electrophotographic image forming apparatus of an intermediate transfer type. [Figure 7] FIG. 2 is a schematic diagram showing an example of the configuration of a concentration detection sensor. [Figure 8] FIG. 4 is a schematic diagram showing an example of a difference output from a concentration detection sensor. [Figure 9] FIG. 1(a) is an explanatory diagram of stretch blow molding used in manufacturing an electrophotographic belt, FIG. 1(b) is an explanatory diagram of an imprint processing device used to form grooves, and FIG. 1(c) is a cross-sectional view in a direction perpendicular to the circumferential direction of one embodiment of an electrophotographic belt. [Figure 10] FIG. 2 is a schematic diagram showing an example of a cross-sectional shape of a protrusion of a cylindrical mold. [Figure 11] FIG. 4 is an explanatory diagram of a groove shape in a second region in the first embodiment. [Figure 12] FIG. 10 is an explanatory diagram of the results of a sensing evaluation of the belt of Example 1. [Figure 13] FIG. 10 is an explanatory diagram of the groove shape in the second region of Comparative Example 1. [Figure 14] FIG. 10 is an explanatory diagram of the sensing evaluation results of the belt of Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0010] The electrophotographic belt having an endless shape according to the present disclosure has, on its outer surface, a plurality of grooves extending in the circumferential direction of the electrophotographic belt. The outer surface has a first region having n grooves in a direction perpendicular to the circumferential direction of the electrophotographic belt, and a second region having more than n grooves in a direction perpendicular to the circumferential direction of the electrophotographic belt. In this configuration, the amount of specularly reflected light from the second region having a relatively larger number of grooves is smaller than the amount of specularly reflected light from the first region. FIG. 5 is an enlarged cross-sectional view of an electrophotographic belt 500 having grooves extending in the circumferential direction on its outer surface, in a direction perpendicular to the circumferential direction. Of the light irradiated onto the outer peripheral surface of the electrophotographic belt 500, light (λ1) incident on a land portion 503 adjacent to a groove 501 is specularly reflected, but light (λ2) incident on the bottom of the groove 501 is reflected by, for example, the side surface of the groove 501, resulting in a reduced amount of specularly reflected light. As a result, it is believed that the amount of specularly reflected light from the second region, which has a relatively large number of grooves, is less than the amount of specularly reflected light from the first region.

[0011] Therefore, the inventors of the present invention have conducted research to reduce the difference between the amount of specularly reflected light in the second region and the amount of specularly reflected light in the first region. As a result, the grooves in the second region are a first groove whose width gradually decreases in a first circumferential direction of the belt; a second groove adjacent to the first groove and gradually decreasing in width in a second circumferential direction opposite to the first circumferential direction; It has been found that it is effective to adjust the widths of adjacent grooves in the second region so as to include the above. That is, the amount of specularly reflected light from each region also depends on the width of each groove, and the amount of specularly reflected light decreases as the groove width increases. Therefore, the first groove in the second region is shaped so that its width gradually decreases in one circumferential direction of the belt (hereinafter also referred to as the "circumferential direction A2"). Furthermore, the width of at least one second groove of two grooves adjacent to the first groove is shaped so that its width gradually decreases in the direction opposite to the circumferential direction A2 (hereinafter also referred to as the "circumferential direction A1"). More preferably, the degree of decrease in the amount of specularly reflected light of the first groove in the circumferential direction A2 and the degree of decrease in the amount of specular reflected light of the second groove in the circumferential direction A1 are complementary. This makes it possible to minimize the decrease in the amount of specularly reflected light in the second region due to the relatively larger number of grooves compared to the first region.

[0012] An electrophotographic belt according to one embodiment of the present disclosure will be described in detail below, although the present disclosure is not limited to the following embodiment. FIG. 1(a) is a schematic explanatory diagram of the outer peripheral surface of an electrophotographic belt (hereinafter, may be simply referred to as a "belt") 5 according to one embodiment of the present disclosure, and FIG. 1(b) is a partial enlarged view of region X in FIG. 1(a).

[0013] <Electrophotographic belt> The belt 5 has an endless shape, and the outer surface of the belt 5 is provided with a plurality of grooves 200 extending in the circumferential direction of the electrophotographic belt. An example of an electrophotographic belt having an endless shape is an intermediate transfer belt. The outer surface of the belt 5 has a first region 300 having n grooves in a direction perpendicular to the circumferential direction, and a second region 301 having more than n grooves in a direction perpendicular to the circumferential direction. Here, n is an integer of 1 or greater, and the number is not particularly limited as long as the cleaning member can stably clean the outer surface. As an example, in the first region, the number of grooves per mm of width perpendicular to the circumferential direction of the electrophotographic belt is preferably 8 to 500. Specifically, for example, when the total width of the electrophotographic belt in the direction perpendicular to the circumferential direction is 244 mm, the number of grooves n in the first region is preferably 1,952 to 122,000. Furthermore, when the total width is 360 mm, the number of grooves n is preferably 2,880 to 180,000. By setting the number of grooves in the first region within the above range, the area of ​​the cleaning member (not shown) that comes into contact with the portion where the grooves 200 are not provided is reduced, thereby reducing the frictional force generated between the cleaning member and the electrophotographic belt 5. In addition, it is possible to prevent a decrease in the amount of specularly reflected light from the second region due to an excessive number of grooves in the second region.

[0014] The first region 300 includes a groove 200-1. The width of the groove 200-1 is preferably constant. However, "constant" here means that unavoidable dimensional variations in forming the groove are "constant." On the other hand, the second region 301 includes a first groove 200-2 whose width gradually decreases in a first circumferential direction A1 of the belt, and a second groove 200-3 adjacent to the first groove 200-2 whose width gradually decreases in a second circumferential direction A2 opposite the circumferential direction A1. The first grooves 200-2 and the second grooves 200-3 are alternately arranged in a direction perpendicular to the circumferential direction of the belt. In the second region, which has a greater number of grooves than the first region 300, the widths of adjacent grooves are varied to be complementary to each other in one circumferential direction, for example, the first circumferential direction A1. This more reliably prevents a decrease in the amount of specularly reflected light in the second region due to an increased number of grooves. There is no particular limitation on the degree of gradual reduction in the width of each of the grooves 200-2 and 200-3 in the second region 301. However, in order to stably maintain good cleaning performance in the second region, it is preferable that the width of each groove decreases at a constant rate from one end of the second region to the other end in the belt circumferential direction.

[0015] The number of grooves in the second region is preferably 2n-10 or more and 2n+10 or less. By setting the number of grooves in the second region to 2n-10 or more, it is possible to stably change the position of the contact portion of the cleaning member at the boundary between the first region and the second region. Furthermore, by setting the number of grooves in the second region to 2n+10 or less, it is possible to more stably perform secondary transfer of toner even if the toner is primarily transferred onto the grooves.

[0016] 2 shows a cross section of the first region in a direction perpendicular to the circumferential direction of the belt 101. W1 represents the width of the groove, H1 represents the depth of the groove, and P1 represents the interval between the grooves. FIG. 3 shows a cross-sectional view of the belt 101 in the second region in a direction perpendicular to the circumferential direction. In the second region, first grooves 200-2, whose width gradually decreases in a first circumferential direction A1 of the belt 101, and second grooves 200-3, adjacent to the first grooves 200-2 and whose width gradually decreases in a second circumferential direction A2 opposite the circumferential direction A1, are alternately arranged. Therefore, depending on the observation position, narrow grooves and wide grooves may alternate in some locations. W2a and W2b represent the width of each groove, H2a and H2b represent the depth of each groove, and P2a and P2b represent the spacing between each groove. Also, d represents the center-to-center distance between adjacent grooves.

[0017] The spacing between adjacent grooves (P1, P2a, P2b, d) is not particularly limited as long as it is within the range of the number of grooves described above, but it is preferable that the spacing be approximately equal from the perspective of toner cleaning. For example, if the length of the belt in the direction perpendicular to the circumferential direction is 244 mm, P1 is preferably 2 μm to 122 μm. By setting P1 to 122 μm or less, 2,000 grooves can be formed in the first region, resulting in better cleaning. Furthermore, by setting P1 to 2.0 μm or more, it is possible to prevent the number of grooves formed in the second region from increasing too much.

[0018] The groove widths (W1, W2a, W2b) are preferably 0.10 μm to 3.00 μm, and more preferably 0.20 μm to 2.00 μm. By making the groove width 0.10 μm or more, it is possible to more reliably prevent the grooves from disappearing due to wear on the outer surface accompanying use of the electrophotographic belt. Furthermore, by making the groove width 3.00 μm or less, it is possible to effectively prevent a decrease in the secondary transferability of the toner when the toner is primarily transferred onto the grooves.

[0019] The groove depths (H1, H2a, H2b) are preferably 0.10 μm or more and less than 5.00 μm, and more preferably 0.20 μm or more and less than 2.00 μm. Groove depths of 0.10 μm or more can more reliably prevent the grooves from disappearing due to wear on the outer surface during use of the electrophotographic belt. Furthermore, groove depths of 5.00 μm or less can reduce vignetting of light reflected from the groove bottom due to the groove walls, further contributing to suppressing a decrease in the amount of specularly reflected light caused by the grooves. Furthermore, for the grooves 200-2 and 200-3 in the second region, it is preferable that the groove depths gradually decrease as the groove widths gradually decrease. The shallower the groove depth, the less vignetting of light reflected from the groove bottom due to the groove walls can be suppressed, thereby suppressing a decrease in the amount of specularly reflected light. Therefore, by configuring the depth of the grooves 200-2 and 200-3 to become shallower as the groove width gradually decreases, it is possible to better suppress the decrease in the amount of specularly reflected light in the second region caused by an increase in the number of grooves.

[0020] The extension direction of the grooves 200 in the belt according to the present disclosure is preferably non-parallel to the circumferential direction of the belt. Specifically, the narrow angle θ (see FIG. 1(c)) that the groove 200-1 in the first region makes with respect to a straight line A1-A2 parallel to the circumferential direction is preferably not 0° (θ ≠ 0°) and is greater than −3° and less than +3°. θ being 0° means that the groove 200-1 extends parallel to the circumferential direction. When θ is not 0°, the contact position of the cleaning member with the outer circumferential surface of the electrophotographic belt is not fixed, which can prevent only a specific portion from wearing out. Furthermore, assuming that θ is not 0°, setting θ to greater than −3° and less than +3° can prevent excessive friction between the cleaning member and the electrophotographic belt. In other words, the preferred ranges of θ are −3°<θ<0° and 0°<θ<+3°.

[0021] One embodiment of the electrophotographic belt is, for example, as shown in FIG. 9(c) which shows a cross section of the first region in a direction perpendicular to the circumferential direction of the belt, It can have a base layer 909 having an endless shape and a surface layer 907 provided on its outer peripheral surface, with a groove 200-1 formed on the surface of the surface layer opposite to the surface facing the base layer. Furthermore, an elastic layer (not shown) may be provided between the base layer 909 and the surface layer 907 . The base layer can be formed by a known method using a known thermoplastic resin or a known thermosetting resin. Specific examples of the molding method using a thermoplastic resin include the following: A method in which a resin composition is pelletized and molded by a known molding method such as continuous melt extrusion molding, injection molding, stretch blow molding, or inflation molding to obtain an electrophotographic belt in an endless belt shape.

[0022] The surface layer can be formed by using a known method such as dip coating, spray coating, flow coating, shower coating, roll coating, spin coating, or ring coating. The grooves can be formed by known methods such as cutting, etching, imprinting, etc. From the viewpoints of reproducibility of the grooves and processing costs, imprinting is preferred.

[0023] Then, the groove 200 in the second region, as shown in FIG. 1(b), a groove 200-2 whose width gradually decreases in the first circumferential direction A1; a groove 200-3 whose width gradually decreases in the second circumferential direction A2; A method for manufacturing an electrophotographic belt including the above will be described below by taking an example in which an imprinting process is used. The electrophotographic belt according to the present disclosure is not limited to those manufactured by this method.

[0024] The imprinting method according to the present disclosure includes a step of pressing a mold having protrusions corresponding to the shape of the grooves to be formed against a surface to be processed. Specifically, for example, as shown in FIG. 9(b), a cured film of a curable resin composition is formed on the outer peripheral surface of an endless-shaped substrate. Next, the substrate 901 with the cured film is held on the outer peripheral surface of a cylindrical holding mold 900. On the other hand, a cylindrical mold is prepared, in which convex portions corresponding to the width, depth, and pitch of the grooves 200-1 to be formed in the first region are spirally formed on the outer peripheral surface around the entire circumference at an inclination of a predetermined angle with respect to the circumferential direction so as to correspond to the narrow angle θ. Here, the shape of the convex portions is, for example, trapezoidal in cross section in a direction perpendicular to the direction in which the convex portions extend at the predetermined angle in the circumferential direction of the cylindrical mold, as shown in Fig. 10 .

[0025] Next, a cylindrical mold 905 is placed relative to the holding mold 900 holding the substrate 901 having the cured film so that the rotation axes of the holding mold 900 and the cylindrical mold 905 are parallel and so that the tip of the convex portion of the cylindrical mold 905 comes into contact with the outer surface of the cured film. Then, while both the holding mold and the cylindrical mold 905 are rotated at a predetermined speed, the cylindrical mold 905 is pressed against the holding mold while the pressure is gradually increased at a predetermined rate. Once the pressure reaches a predetermined value, that pressure is maintained, and once the initial contact position of the cured film on the holding mold with the mold has made one rotation, the pressing force of the mold against the holding mold is gradually reduced at a predetermined rate, and the cylindrical mold 905 is released. In this way, the convex shape on the surface of the cylindrical mold 905 is transferred to the cured film. Because the convex portion of the cylindrical mold 905 is formed spirally in the circumferential direction, the start and end points of the transferred grooves do not coincide. Furthermore, because mold release begins when the holding mold has completed one rotation, the end points of the circumferential grooves in the cured film are located downstream in the rotation direction from the start points of the grooves. As a result, a first region with n grooves in the direction perpendicular to the circumferential direction and a second region with more than n grooves in the direction perpendicular to the circumferential direction are formed on the surface of the cured film.

[0026] The thickness of the electrophotographic belt is preferably 10 μm or more and 500 μm or less, particularly preferably 30 μm or more and 150 μm or less. The electrophotographic belt of the present disclosure may be used as a belt, or may be wound around or covered on a drum or roll used as an electrophotographic member.

[0027] <Electrophotographic image forming apparatus> FIG. 6 shows an example of an image forming apparatus incorporating an electrophotographic belt according to the present disclosure as an intermediate transfer member, configured as an electrophotographic apparatus. This image forming apparatus forms color images on a recording medium S, such as paper, supplied from a paper feed cassette 20 using four color toners, represented by C, M, Y, and K, respectively. Image forming stations for each color are arranged side by side in a substantially horizontal direction. These image forming stations are equipped with photosensitive drums 1c, 1m, 1y, and 1k, respectively. The subscripts "c," "m," "y," and "k" are added to reference numerals to indicate which color image forming station the reference numeral belongs to: "cyan," "magenta," "yellow," or "black." This image forming apparatus is equipped with a laser scanner 3, a laser optical unit, which emits laser beams 3c, 3m, 3y, and 3k corresponding to image signals for each color toward the photosensitive drums 1c, 1m, 1y, and 1k, respectively.

[0028] Since all the image forming stations have the same structure, the image forming station for K (black) will be described here. Surrounding the photosensitive drum 1k are a conductive roller 2k, which is a contact charging device, a developing unit 4k, a conductive roller 8k, which is a primary transfer roller, and a toner recovery blade 14k, which is used to clean the photosensitive drum 1k. The developing unit 4k is provided with a developing roller 41k, which is a developer carrier that develops the latent image on the photosensitive drum 1k, a developing container 42k that holds toner supplied to the developing roller 41k, and a developing blade 43k that regulates the amount of toner on the developing roller 41k and applies an electric charge.

[0029] The electrophotographic belt 5 is configured as an endless belt and is provided commonly to the image forming stations for each color. It is stretched over a secondary transfer opposing roller 92, a tension roller 6, and a drive roller 7, and is rotated in the direction of the arrow in the figure by the drive roller 7. The electrophotographic belt 5 comes into contact with the surfaces of the photosensitive drums 1y, 1m, 1c, and 1k in succession in the section between the tension roller 6 and the drive roller 7, and is pressed against the photosensitive drums 1y, 1m, 1c, and 1k by primary transfer rollers 8y, 8m, 8c, and 8k, respectively. As a result, the toner images formed on the surfaces of the photosensitive drums 1y, 1m, 1c, and 1k are transferred to the surface of the electrophotographic belt 5, which serves as an intermediate transfer member.

[0030] A secondary transfer roller 9 is provided opposite the counter roller 92, and the electrophotographic belt 5 is pressed against the counter roller 92 by the secondary transfer roller 9. A secondary transfer voltage is applied to the secondary transfer roller 9 from a power source via a current detection circuit 10. The secondary transfer roller 9 and the counter roller 92 form a secondary transfer unit. The recording medium S passes through a nip between the electrophotographic belt 5 and the secondary transfer roller 9 at the position of the counter roller 92 via a feed roller 12 and a transport roller 13, whereby the toner image held on the outer peripheral surface of the electrophotographic belt 5 is transferred. In this way, an image is formed on the surface of the recording medium S. The recording medium S, onto which the toner image has been transferred, passes through a fixing device 15 consisting of a roller pair of a heating roller 151 and a pressure roller 152, whereby the image is fixed, and the recording medium S is discharged onto a paper output tray 21.

[0031] A cleaning blade 11 is provided at the position of the tension roller 6 to come into contact with the outer peripheral surface of the electrophotographic belt 5. Toner that has not been transferred to the recording medium S and remains on the outer peripheral surface of the electrophotographic belt 5 is scraped off and removed by the cleaning blade 11. The cleaning blade 11 is a member that extends in a direction substantially perpendicular to the direction in which the electrophotographic belt 5 moves. The cleaning blade 11 is not particularly limited as long as it is suitable for toner cleaning. Examples include urethane rubber, acrylic rubber, nitrile rubber, and EPDM rubber, and from the viewpoint of toner cleaning, urethane rubber is preferred.

[0032] The color of printed matter in an electrophotographic image forming apparatus changes depending on conditions such as the environment in which it is used. For this reason, it is necessary to measure density appropriately and provide feedback to the control mechanism within the main body. The toner image for density correction is transferred to the surface of the electrophotographic belt 5, and then transported to the position of the drive roller 7 as the electrophotographic belt 5 rotates. The toner density is detected by a density detection sensor 160, which is located on the opposite side of the electrophotographic belt 5 from the drive roller 7.

[0033] 7 is a schematic diagram of the density detection sensor 160. The density detection sensor 160 is composed of a light-emitting element 161, a diffuse reflection light-receiving element 162, and a specular reflection light-receiving element 163. The light-emitting element 161 emits infrared light, which is reflected by the surface of the toner image T. The diffuse reflection light-receiving element 162 is positioned so that it can receive light reflected in directions other than the specular reflection direction relative to the position of the toner image T, and detects the diffuse reflection light at the position of the toner image T. The specular reflection light-receiving element 163 is positioned so that it can receive light reflected in the specular reflection direction relative to the toner image T, and detects the specular reflection light at the position of the toner image T. The detected voltage values ​​are called the diffuse reflection output and the specular reflection output, respectively.

[0034] FIG. 8(a) is a schematic diagram illustrating specular reflection output fluctuation 401, diffuse reflection output fluctuation 402, and sensor output fluctuation 403 calculated from these fluctuations relative to toner concentration. When the toner amount (toner concentration) is low, the specular reflection output increases because a large amount of reflection from the smooth, mirror-like surface of the electrophotographic belt 5 is detected. As the toner amount (toner concentration) increases, the specular reflection output decreases. When the number of toner layers exceeds one, the specular reflection component from the surface of the electrophotographic belt 5 almost disappears. However, the specular reflection output includes both specular reflection and diffuse reflection components. Therefore, the specular reflection output does not monotonically decrease in high-density regions. On the other hand, the diffuse reflection output monotonically increases with the toner amount, but the amount of change (increase) is smaller than the amount of change (decrease) in the specular reflection output. By subtracting the diffuse reflection component, which is obtained based on the diffuse reflection output, from the specular reflection output, the sensor output fluctuation 403 (hereinafter also referred to as sensor output) correlated with the toner concentration can be obtained.

[0035] FIG. 8(b) is a schematic diagram illustrating the base output at multiple locations on the surface of the electrophotographic belt 5 and the patch output at those locations. The base output refers to the sensor output when there is no toner, and the patch output refers to the sensor output when there is toner. As shown in FIG. 8(b), the base output 404 varies depending on the position on the electrophotographic belt 5. Specifically, the specular reflection output changes due to local differences in reflectivity and surface shape depending on the position on the surface of the electrophotographic belt 5, resulting in fluctuations in the base output 404, which is the sensor output 403. Each patch output 405 detects a toner image formed with the same half-tone density, but like the base output 404, it fluctuates depending on the position on the surface of the electrophotographic belt 5. In other words, even if the toner density is the same, the patch output 405 fluctuates depending on the fluctuations in the condition of the base (belt surface). Therefore, if image density control is performed based on the patch output 405 itself, which does not accurately reflect the toner density, the accuracy of the image density control will be reduced. In order to avoid such a decrease in accuracy as much as possible, it is preferable that the specular reflection output, which is the main output of the base, is as uniform as possible regardless of the position on the surface of the electrophotographic belt 5 . [Example]

[0036] The present disclosure will be specifically described below with reference to Examples and Comparative Examples, but the present disclosure is not limited to the configurations embodied in the Examples. The characteristic values ​​and performance of the electrophotographic belts produced in the Examples and Comparative Examples were evaluated according to the following [Evaluation 1] to [Evaluation 5].

[0037] [Evaluation 1] Evaluation of the number of grooves on the surface of the electrophotographic belt and the length of the second region in the circumferential direction The state of the grooves on the surface of the electrophotographic belt was observed over the entire belt surface at 10x magnification using a digital microscope (product name: VHX-500, manufactured by Keyence Corporation), and the presence and number of first and second regions, as well as the length of the second region, were confirmed. Next, the number of grooves in the direction perpendicular to the circumferential direction in the first and second regions was counted. Regarding the location for counting the number of grooves, if the length of the region was 100 mm or less, a single point in the center of the region was counted. If the length of the region exceeded 100 mm, a measurement was taken at one point every 100 mm, and the arithmetic mean value was calculated.

[0038] [Evaluation 2] Evaluation of the groove shape on the surface of the electrophotographic belt The surface of the electrophotographic belt was observed at 50x magnification using a scanning white light interference microscope (product name: Vert Scan, manufactured by Ryoka Systems Co., Ltd.) to confirm the width and depth of the grooves. The groove shape was measured at the midpoint in the direction perpendicular to the circumferential direction of the belt (width direction) in the first and second regions, and at three points 100 mm from the midpoint on both ends. In the circumferential direction, evaluation was performed at five points every 1 / 5 of the circumferential length of each of the first and second regions.

[0039] Because the observation field of view when using a 50x lens is narrow at 94.1 μm x 70.6 μm, the image stitching function was used to acquire images from multiple fields of view, and the cross-sectional shape profile was used to measure the shapes of 10 or more grooves per measurement point, with the arithmetic mean of these values ​​being used as a representative value for evaluation. In the first area, all grooves within the observation field of view were evaluated. In the second area, odd-numbered grooves and even-numbered grooves counting from the left edge of the observation field of view were classified as groove A and groove B for evaluation.

[0040] [Evaluation 3] Sensing evaluation (calculation of the rate of change in specular reflection output) An electrophotographic image forming apparatus shown in Figure 6 was used, and an electrophotographic belt was installed as an intermediate transfer member. The specular reflection output per revolution of the electrophotographic belt was measured in 1 mm increments, and the deviation rate was evaluated using the arithmetic mean value Vave, maximum value Vmax, minimum value Vmin, and the following formula (1). The density detection sensor was positioned ±100 mm from the center of the electrophotographic belt in the width direction. Furthermore, since the specular reflection output varies depending on the conditions of the grooves provided on the surface of the electrophotographic belt, this evaluation was performed by adjusting the light output so that the specular reflection output in the first region was 3.0 V. Runout rate = (Vmax - Vmin) / Vave Equation (1)

[0041] [Evaluation 4] Evaluation of toner cleaning performance Using the electrophotographic image forming apparatus shown in FIG. 6, an electrophotographic belt was attached as an intermediate transfer member, and blade cleaning was carried out while printing an image, to evaluate the toner cleaning performance. This evaluation was carried out under an environment of a temperature of 15°C and a relative humidity of 10%, using OCE Extra (basis weight 80 g / m) as the recording medium S. 2 ) JIS A4 size paper was used, and the paper was passed through with two sheets intermittently printed until toner cleaning failure occurred, with the upper limit set at 200,000 sheets. The toner was then evaluated by whether or not it slipped through the cleaning blade.

[0042] Specifically, first, with the secondary transfer voltage turned off (0 V), laser beams 3y and 3m were irradiated onto photosensitive drums 1y and 1m to record a red image (Y toner and M toner) over the entire A4 size surface. After that, the secondary transfer voltage was set to an appropriate value, and three blank sheets were passed continuously. Since no secondary transfer voltage is applied, the Y toner and M toner transferred from the photosensitive drums 1y and 1m to the entire surface of the electrophotographic belt 5 is hardly transferred to the recording medium S at the secondary transfer portion and rushes into the cleaning blade 11. If the toner is removed from the electrophotographic belt, the three sheets that pass thereafter will be output as completely blank, but if the toner is not removed, the transfer residual toner that has slipped through the cleaning blade 11 will be transferred to the recording medium S at the secondary transfer portion. In other words, it will be transferred onto the blank paper and output on the recording medium S as a toner cleaning failure image.

[0043] The above evaluation was carried out at the times when 50,000 sheets had been passed, 100,000 sheets had been passed, 150,000 sheets had been passed, and 200,000 sheets had been passed. Based on the evaluation results, the electrophotographic belts were ranked according to the following criteria. When it was visually confirmed that streaks parallel to the conveyance direction of the recording medium S had appeared on the white background of the recording medium S, it was determined that a toner cleaning failure had occurred. Rank A: No toner cleaning failures occurred during the 200,000 sheet paper feed process. Rank B: Toner cleaning failure occurred during the 200,000 sheet paper feed process. Rank C: Toner cleaning failure occurred during the 150,000 sheet paper feed process. Rank D: Toner cleaning failure occurred during the process of passing 100,000 sheets. Rank E: A toner cleaning failure occurred during the process of passing 50,000 sheets.

[0044] [Evaluation 5] Evaluation of halftone image performance Using the electrophotographic image forming apparatus shown in Fig. 6, an electrophotographic belt was attached as an intermediate transfer member to output a halftone red image (Y toner and M toner). From the evaluation results, the electrophotographic belts were ranked according to the following criteria. Rank A: No visible streaks of uneven density Rank B: Slight streaks of uneven density are visible Rank C: Streaky uneven density is visible

[0045] Example 1 [Base layer manufacturing] First, a thermoplastic resin composition was prepared by melt-kneading the following base layer materials in a mass ratio of PEN / PEEA / CB = 84 / 15 / 1 using a twin-screw extruder (trade name: TEX30α, manufactured by The Japan Steel Works, Ltd.). The melt-kneading temperature was adjusted to a range of 260°C to 280°C, and the melt-kneading time was approximately 3 to 5 minutes. The obtained thermoplastic resin composition was pelletized and dried at a temperature of 140°C for 6 hours. Next, the dried pelletized thermoplastic resin composition was placed in an injection molding machine (trade name: SE180D, manufactured by Sumitomo Heavy Industries, Ltd.). The cylinder temperature was set to 295°C, and the pellets were injection-molded into a mold temperature-controlled at 30°C to produce a preform. The obtained preform had a test tube shape with an outer diameter of 50 mm, an inner diameter of 46 mm, and a length of 100 mm. ·Base material PEN: Polyethylene naphthalate (product name: TN-8050SC, manufactured by Teijin Chemicals Ltd.) PEEA: Polyetheresteramide (trade name: Pelestat NC6321, manufactured by Sanyo Chemical Industries, Ltd.) CB: Carbon black (product name: MA-100, manufactured by Mitsubishi Chemical Corporation)

[0046] Next, the preform is biaxially stretched using a biaxial stretching apparatus (stretch blow molding machine) shown in Fig. 9(a). Before biaxial stretching, the preform 104 is placed in a heating device 107 equipped with a non-contact heater (not shown) for heating the outer and inner walls of the preform 104, and heated with the heater until the outer surface temperature of the preform reaches 150°C. Next, the heated preform 104 was placed in a blow mold 108 with the mold temperature maintained at 30°C, and stretched in the axial direction using a stretching rod 109. At the same time, air adjusted to a temperature of 23°C was introduced into the preform from a blow air injection section 110 to stretch the preform 104 in the radial direction. In this way, a bottle-shaped molded product 112 was obtained. Next, the body of the obtained bottle-shaped molded product 112 was cut to obtain a seamless base layer of an electrophotographic belt, which had a thickness of 70.2 μm, a circumferential length of 712.2 mm, and a width of 244.0 mm.

[0047] [Coating fluid blending] The following surface layer materials were weighed in a ratio of AN / PTFE / GF / SL / IRG = 66 / 20 / 1.0 / 12 / 1.0 (mass ratio calculated on solid content). The materials except for SL were roughly dispersed in a solution, which was then subjected to a high-pressure emulsifying disperser (trade name: Nanovaita, manufactured by Yoshida Kikai Kogyo Co., Ltd.) until the 50% average particle size of PTFE reached 200 nm. The SL was further stirred, and the PTFE dispersion solution was added dropwise to obtain a coating solution for forming the surface layer. The PTFE particle size in the coating solution was measured using a concentrated particle size analyzer (trade name: FPAR-1000, manufactured by Otsuka Electronics Co., Ltd.) based on dynamic light scattering (DLS) technology (ISO-DIS22412).

[0048] [Table 1]

[0049] [Surface layer formation] The base layer obtained by blow molding was fitted onto the outer periphery of a cylindrical mold (circumference 712 mm), the edges were sealed, and the mold was then immersed in a container filled with the coating liquid (curable composition). The curable composition was then pulled up so that the relative speed between the liquid surface and the base layer was constant, forming a coating film made of the coating liquid on the surface of the base layer. The desired film thickness can be obtained by adjusting the pulling speed (the relative speed between the liquid surface and the base layer of the curable composition) and the solvent ratio of the curable composition. In this example, the pulling speed was set to 10 to 50 mm / sec, and the surface layer thickness was adjusted to 3 μm.

[0050] In this example, the coating direction refers to the direction opposite to the direction in which the base layer is pulled up. In other words, the location where the base layer is first pulled up from the coating liquid is the most upstream. The base layer coated with the coating liquid was removed from the cylindrical mold and dried for 1 minute in an exhausted environment at a temperature of 23°C. The drying temperature and drying time were adjusted appropriately depending on the type of solvent, solvent ratio, and film thickness. Thereafter, a UV irradiator (product name: UE06 / 81-3, manufactured by Eye Graphics Co., Ltd.) was used to dry the base layer with an accumulated light dose of 600 mJ / cm. 2 The coating film was irradiated with ultraviolet light until the coating film hardened. The thickness of the surface layer was measured by destructive testing, in which an electrophotographic belt separately produced under the same conditions was cut and the cross section was observed with an electron microscope (product name: XL30-SFEG, manufactured by FEI). The destructive testing results showed that the thickness of the surface layer was 3.0 μm.

[0051] [Groove formation] Using the imprint processing device shown in FIG. 9(b), grooves were formed in the cured film of the base layer 60 that held the cured film of the coating film. The imprint processing device is composed of a cylindrical mold 905 for providing grooves and a cylindrical belt holding mold 900, and the cylindrical mold 905 can apply pressure while maintaining its axis parallel to the cylindrical belt holding mold 900. At this time, the cylindrical mold 905 and the cylindrical belt holding mold 900 rotate synchronously without slippage.

[0052] The cylindrical mold 905 was made of electroless nickel-plated carbon steel and had a diameter of 50 mm and a length of 250 mm. The surface of the cylindrical mold 905 had protrusions corresponding to the shape of the grooves, and the protrusion pattern was formed in a spiral shape with an angle of 0.1° relative to the circumferential direction of the cylindrical mold 905. The cross-sectional shape of the protrusions corresponding to the grooves formed on the cylindrical mold 905 used in this example, in a direction perpendicular to the circumferential direction, was trapezoidal as shown in FIG. 10, with the respective dimensions of H = 3.5 μm, Wb = 2.0 μm, Wt = 0.2 μm, and P = 20 μm. A cartridge heater was embedded in the cylindrical mold 905 to enable heating.

[0053] A base layer with a coating film formed thereon was fitted onto the outer periphery of the cylindrical belt holder mold 900 (circumferential length 712 mm). This was rotated together with the cylindrical mold 905 at a peripheral speed of 1 mm / sec (the rotation directions were opposite for both), and while maintaining their axial centerlines parallel to each other, the cylindrical mold 905 heated to 130°C was brought into contact with the cylindrical belt holder mold 900, and the pressure was increased to 8.0 kN at a rate of 1.0 kN / s. The cylindrical belt holder mold 900 and the cylindrical mold 905 continued to rotate while the pressure on the cylindrical mold 905 was increased. Thereafter, the cylindrical belt holder mold 900 and the cylindrical mold 905 were rotated while the pressure was maintained at 8.0 kN.

[0054] Then, when the position of the cylindrical belt holding mold 900 that first came into contact with the cylindrical mold 905 had rotated one revolution, the pressure on the cylindrical mold 905 was reduced at a rate of 1.0 kN / s, and the cylindrical mold 905 was released. As a result, the convex pattern of the cylindrical mold 905 was transferred to the surface of the electrophotographic belt, forming grooves. Because the convex pattern of the cylindrical mold 905 was spiral, the start and end of the grooves did not connect after one revolution, and a second region having more grooves than the first region was formed. The groove pattern of the electrophotographic belt obtained through the above steps was one each of a first region and a second region, with 12,200 grooves in the first region and 24,401 grooves in the second region, and the circumferential length of the second region was 7.8 mm. The width and depth of the groove in the first region were as follows: W1=0.6μm H1=0.6μm P1=20μm

[0055] In this example, observation was carried out in three fields per measurement point, and 14 grooves were evaluated. 11(a) and 11(b) show groove A (corresponding to groove 200-3 in FIG. 1) and groove B (corresponding to groove 200-2 in FIG. 1) in the belt circumferential direction in the second region, along with their respective average groove widths (W2a, W2b) and average groove depths (H2a, H2b). Note that in FIGS. 11(a) and 11(b), the origin (0 mm) of the circumferential distance on the horizontal axis is the position furthest in the A2 direction in the second region shown in FIG. 1. The groove spacing was as follows: P2a=20μm P2b=20 μm d=10μm

[0056] As shown in Fig. 11(a), groove B (corresponding to groove 200-2 in Fig. 1) has a groove width that gradually decreases in the belt circumferential direction A1, and as shown in Fig. 11(b), groove B has a groove depth that gradually decreases in the belt circumferential direction A1. The above-described changes in the groove width and groove depth of the groove B are due to the following two points. The cross-sectional shape of the protrusion of the cylindrical mold 905 in the direction perpendicular to the circumferential direction is made approximately trapezoidal as shown in FIG. 10, and Groove B is a groove formed in the process of increasing the pressure at a predetermined rate when the cylindrical mold 905 is rotated in the direction A2 to transfer the pattern of the convex portions of the cylindrical mold 905 to the cured film. On the other hand, groove A (corresponding to groove 200-3 in FIG. 1) has a groove width that gradually decreases in the belt circumferential direction A2 as shown in FIG. 11(a), and a groove depth that gradually decreases in the belt circumferential direction A2 as shown in FIG. 11(b). The above-described changes in the width and depth of the groove A are due to the following two points. The cross-sectional shape of the protrusion of the cylindrical mold 905 in the direction perpendicular to the circumferential direction is made approximately trapezoidal as shown in FIG. 10; Groove A is a groove formed by reducing the pressure at a predetermined rate during the process of forming the second region by rotating and moving the cylindrical mold 905 in the direction of A2 to transfer the pattern of the convex portions of the cylindrical mold 905 to the cured film.

[0057] When the electrophotographic belt was mounted on the electrophotographic image forming apparatus shown in FIG. 6 and the specular reflection output was evaluated, the waveform shown in FIG. 12 was obtained. Fig. 12(a) is a chart showing the specular reflection output in the entire circumferential direction of the electrophotographic belt. Fig. 12(b) is an enlarged chart showing the vicinity of the second region extracted from the chart shown in Fig. 12(a). As is clear from Figs. 12(a) and 12(b), the specular reflection light output of the electrophotographic belt according to this example was equivalent in the first region and the second region, and the deviation rate calculated using the above formula (1) was 3%.

[0058] The toner cleaning performance was also evaluated, and no toner cleaning failure occurred during the process of passing 200,000 sheets, so the electrophotographic belt was judged to be rank A. The electrophotographic belt was mounted on an electrophotographic image forming apparatus shown in Fig. 6, and halftone image performance was evaluated. No streak-like density unevenness due to the groove pattern on the surface of the electrophotographic belt was observed, and the electrophotographic belt was determined to be rank A.

[0059] (Comparative Example 1) When forming a groove using an imprint processing device, With the cylindrical mold 905 and the cylindrical belt holding mold 900 stationary, the cylindrical mold 905 is pressed against the cylindrical belt holding mold 900 up to 8.0 kN, While maintaining the pressure at 8.0 kN, the cylindrical belt holding mold 900 and the cylindrical mold 905 are rotated. When the portion where the cylindrical belt holding mold 900 started to come into contact with the cylindrical mold 905 exceeded one circumference of the cylindrical belt holding mold 900, the cylindrical belt holding mold 900 and the cylindrical mold 905 were stopped. Then, with the cylindrical mold 905 and the cylindrical belt holding mold 900 stationary, the pressure of the cylindrical mold 905 was reduced to 0 kN relative to the cylindrical belt holding mold 900. An electrophotographic belt was produced in the same manner as in Example 1 except for the above.

[0060] For the produced electrophotographic belt, Figures 13(a) and (b) show the grooves A and B, and their respective average groove widths (W2a, W2b) and average groove depths (H2a, H2b) in the circumferential direction of the belt in the second region. As shown in Figures 13(a) and (b), the groove width and groove depth in the circumferential direction of adjacent grooves in the second region in a direction perpendicular to the circumferential direction (corresponding to grooves 200-2 and 200-3 according to the present disclosure) were constant.

[0061] The produced electrophotographic belt was mounted on the electrophotographic image forming apparatus shown in Fig. 6, and the specular reflection output in the circumferential direction was observed. The results are shown in Fig. 14(a). Fig. 14(b) is an enlarged chart of the vicinity of the second region extracted from the chart shown in Fig. 14(a). As shown in Figs. 14(a) and (b), the specular reflection light output from the second region was significantly reduced compared to the specular reflection light output from the first region, and the deviation rate calculated using the above formula (1) was 52%. The toner cleaning performance was evaluated in the same manner as in Example 1. No toner cleaning failure occurred in the process of passing 200,000 sheets, and the electrophotographic belt was determined to be rank A. The halftone image performance was also evaluated in the same manner as in Example 1. No streak-like density unevenness due to the groove pattern on the surface of the electrophotographic belt was observed, and the electrophotographic belt was determined to be rank A.

[0062] (Examples 2 and 3) An electrophotographic belt was produced in the same manner as in Example 1, except that the intervals (P) of the convex patterns of the groove-providing cylindrical die 905 were set to 100 μm and 3.0 μm, respectively, and subjected to evaluation.

[0063] Examples 4 to 6 Electrophotographic belts were produced in the same manner as in Example 1, except that in the process of continuously forming the convex pattern of the groove-imparting cylindrical die 905 in a spiral shape, the angles formed by the convex pattern of the groove-imparting cylindrical die with the circumferential direction were set to 0.01°, 0.9°, and 3.0°, respectively. The electrophotographic belts produced in this manner were subjected to evaluation.

[0064] Example 7 After pressing the groove-imparting cylindrical die 905 against the cylindrical belt holding mold 900 for half its circumference, the groove-imparting cylindrical die 905 was released and then slid vertically by 10 μm, and the cylindrical belt holding mold 900 was further rotated in the reverse direction by a circumferential length of 8 mm. In this state, the groove-imparting cylindrical die 905 was pressed against the cylindrical belt holding mold 900 for another half its circumference, and then the groove-imparting cylindrical die 905 was released. An electrophotographic belt was produced in the same manner as in Example 1, except for the above-mentioned operations. As a result, second regions were provided in two locations in the circumferential direction of the electrophotographic belt. The electrophotographic belt produced in this manner was subjected to evaluation.

[0065] Example 8 Two regions with different patterns were provided on the surface of a cylindrical mold 905 having a diameter of 232.4 mm (circumferential length 730 mm) and a length of 250 mm. In the first region occupying a range of 704 mm in the circumferential direction of the cylindrical mold 905, a convex shape is formed with an angle of 0.1° relative to the circumferential direction and H=3.5 μm, Wb=2.0 μm, Wt=0.2 μm, and P=20 μm. In the second region other than the first region, a convex shape is formed so that the angle formed with respect to the circumferential direction is 0.1°, and H=3.5 μm, Wb=2.0 μm, Wt=0.3 μm, and P=15 μm. In this example, the cylindrical mold 905 was used to process an electrophotographic belt.

[0066] In this example, the second region of the cylindrical mold 905 is brought into contact with the cylindrical belt holding mold 900, and pressure is applied up to 8.0 kN at a rate of 1.0 kN / s. At the same time that the force reaches 8.0 kN, the phase of the cylindrical mold 905 is adjusted so that the first region of the cylindrical mold 905 comes into contact with the cylindrical belt holding mold 900 . Thereafter, while maintaining the pressure at 8.0 kN, the cylindrical belt holding die 900 and the groove-providing cylindrical die 905 are rotated, When the part of the cylindrical belt holding mold 900 where it starts to come into contact with the cylindrical groove-providing mold 905 has traveled one revolution of the cylindrical belt holding mold 900, the second region of the cylindrical mold 905 comes into contact with the cylindrical belt holding mold 900. Thereafter, the load on the cylindrical mold 905 was reduced at a rate of 1.0 kN / s, and the groove-imparting cylindrical mold 905 was released. The electrophotographic belt thus produced was subjected to evaluation.

[0067] (Comparative Examples 2 to 8) An electrophotographic belt was produced in the same manner as in Examples 2 to 8, except that when forming grooves using the imprint processing device, the cylindrical mold 905 was pressurized and depressurized while the cylindrical mold 905 and the cylindrical belt holding mold 900 were kept stationary, as in Comparative Example 1. The produced electrophotographic belt was then subjected to evaluation. The evaluation results of the electrophotographic belts of Examples 1 to 8 are shown in Table 2. The evaluation results of the electrophotographic belts of Comparative Examples 1 to 8 are shown in Table 3.

[0068] [Table 2]

[0069] [Table 3]

[0070] As shown in Table 2, in Examples 1 to 8, the grooves 200 in the second region were configured with grooves 200-2 whose width gradually decreased in the first circumferential direction A1 and grooves 200-3 whose width gradually decreased in the second circumferential direction A2, as shown in FIG. 1(b). Therefore, the change in specular reflection light output between the first region and the second region was small. Therefore, the deviation rate calculated using the above formula (1) was small, and the sensing characteristics were excellent. On the other hand, as shown in Table 3, in Comparative Examples 1 to 8, the width of the grooves constituting the second region was constant, so the specular reflection light output changed significantly between the first region and the second region, and the deviation rate calculated using the formula (1) increased, resulting in poor sensing characteristics. [Explanation of symbols]

[0071] 1 Photosensitive drum 2 Conductive roller 3. Laser scanner 4 Developer 5 Electrophotographic belt 6 Tension roller 7 Drive Roller 8 Primary transfer roller 9 Secondary transfer roller 10 Current detection circuit 11 Cleaning blade 12 Feeding roller 13 Conveyor roller 14 Toner collection blade 15 Fixing unit 20 Paper cassette 21 Paper output tray 41 Developing roller 42 Developer container 43 Developing blade 60 base layer 92 Secondary transfer opposing roller 104 Preform 107 Heating device 108 Blow mold 109 Stretching rod 110 Blow air injection part 112 Blow Bottle 151 Heating roller 152 pressure roller 160 Concentration detection sensor 161 Light-emitting element 162 Regular reflection photodetector 163 Diffuse reflection photodetector 200 grooves 201 First Groove 202 Second Groove 300 1st area 301 Second area 302 Belt circumferential direction 900 Cylindrical Belt Retention Type 901 Base 905 Cylindrical mold S Recording Media T Toner image

Claims

1. An electrophotographic belt having an endless shape, a plurality of grooves extending in the circumferential direction of the electrophotographic belt are provided on the outer surface of the electrophotographic belt; The outer surface comprises at least a first region in which the number of the grooves in a direction perpendicular to the circumferential direction of the electrophotographic belt is n; a second region in which the number of the grooves in a direction perpendicular to the circumferential direction of the electrophotographic belt is greater than n, The grooves present in the second region are a first groove whose width gradually decreases in a first circumferential direction of the electrophotographic belt; and a second groove adjacent to the first groove, the width of which gradually decreases in a second circumferential direction opposite to the first circumferential direction (n represents an integer of 1 or more).

2. 2. The electrophotographic belt according to claim 1, wherein the number of grooves per 1 mm width in the direction perpendicular to the circumferential direction of the electrophotographic belt in the first region is 8 to 500.

3. 3. The electrophotographic belt according to claim 1, wherein the number of the grooves in the second region is 2n-10 or more and 2n+10 or less.

4. As the width of the first groove gradually decreases, the depth of the first groove gradually decreases; 4. The electrophotographic belt according to claim 1, wherein the depth of said second grooves gradually decreases as the width of said second grooves gradually decreases.

5. 5. The electrophotographic belt according to claim 1, wherein when the grooves in the first region form an angle θ with a line parallel to the circumferential direction, θ≠0°.

6. The electrophotographic belt according to claim 5, wherein the angle θ is greater than −3° and less than +3°.

7. 7. The electrophotographic belt according to claim 1, wherein the width of the grooves in the first region and the second region is within a range of 0.10 μm to 3.00 μm.

8. 8. The electrophotographic belt according to claim 1, wherein the width of the groove in the first region is constant.

9. 9. The electrophotographic belt according to claim 1, wherein the electrophotographic belt has a base layer having an endless shape and a surface layer on an outer circumferential surface of the base layer, and the grooves are provided on the outer periphery of the surface layer.

10. An electrophotographic image forming apparatus comprising an endless intermediate transfer belt and a cleaning member in contact with an outer peripheral surface of the intermediate transfer belt, 10. An electrophotographic image forming apparatus, wherein the intermediate transfer belt is the electrophotographic belt according to any one of claims 1 to 9.

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