Image forming apparatus

Abstract

The present invention provides an image forming apparatus that can effectively suppress the decrease in the accuracy of detecting the amount of adhesion of the adjustment pattern for the adhesion amount detection means. [Solution] The image forming apparatus is equipped with a pattern changing means that changes the toner image pattern or the frequency of toner image pattern formation so that the amount of toner input to the part of the cleaning member that contacts the non-paper-feeding area of ​​the image carrier during a predetermined period increases according to the remaining amount of lubricant in the lubricant application means. A specified range is set based on the change of the toner image pattern by the pattern changing means (S12), If the adjustment pattern falls within the set specified range (Yes in S13), the formation timing of the adjustment pattern is changed so that it falls outside the specified range (S14). On the other hand, if the adjustment pattern does not fall within the set specified range (No in S13), the adjustment pattern is formed without changing the formation timing (S15).

Description

[Technical Field]

[0001] This invention relates to an image forming apparatus. [Background technology]

[0002] Conventionally, the following image forming apparatus is known. Specifically, the image forming apparatus comprises an imaging means for forming a toner image by attaching toner to a latent image carried by a latent image carrier, an image carrier for carrying the toner image formed by the imaging means, a transfer member for transferring the toner image on the image carrier to a recording medium, and a cleaning member for cleaning the surface of the image carrier. It also comprises an adhesion amount detection means for detecting the amount of toner attached to an adjustment pattern for adjusting the imaging means, which is arranged opposite the surface of the image carrier and formed outside the recording medium paper feeding area of ​​the image carrier in the width direction of the recording medium.

[0003] Patent Document 1 describes an image forming apparatus that, for the purpose of removing filming from the intermediate transfer belt which is an image carrier, forms a scraping pattern, which is a toner image pattern that is input to a cleaning member without being transferred to a recording medium, on the intermediate transfer belt. Furthermore, Patent Document 1 describes that, in order to suppress the decrease in the accuracy of the adhesion amount detection of the optical sensor, which is an adhesion amount detection means due to filming, the amount of input toner in the region of the scraping toner pattern corresponding to the position of the optical sensor is increased compared to the amount of toner in other regions, thereby increasing the amount of toner input to the cleaning member in that region compared to other regions. [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] However, depending on the positional relationship between the position of the image carrier, such as an intermediate transfer belt on which the adjustment pattern is formed, and the position of the image carrier on which the toner image pattern is formed, there was a risk that the accuracy of the toner adhesion amount detection of the adjustment pattern by an adhesion amount detection means, such as an optical sensor, would decrease. [Means for solving the problem]

[0005] To solve the above-mentioned problems, the present invention provides an image forming apparatus comprising: an image forming means for forming a toner image by attaching toner to a latent image carried by a latent image carrier; an image carrier for carrying the toner image formed by the image forming means; a transfer member for transferring the toner image on the image carrier to a recording medium; a cleaning member for cleaning the surface of the image carrier; and an adhesion amount detection means for detecting the amount of toner attached to an adjustment pattern for adjusting the image forming means, which is arranged opposite to the surface of the image carrier and formed in a non-paper-feeding area of ​​the image carrier that is outside the paper-feeding area of ​​the recording medium in the width direction of the recording medium, wherein the image forming means forms a toner image pattern on the image carrier that is input to the cleaning member without being transferred to the recording medium, and the image forming means also applies a lubricant to the surface of the latent image carrier. The invention provides a pattern changing means that has means to change the toner image pattern or the frequency of formation of the toner image pattern so that the amount of toner input to the portion of the cleaning member that contacts the non-paper-feeding area of ​​the image carrier during a predetermined period increases according to the remaining amount of lubricant of the lubricant application means, and a timing adjustment means that adjusts the timing of formation of the adjustment pattern so that if the surface movement distance of the image carrier from the position of the toner image pattern formed on the image carrier to the formation position of the adjustment pattern formed after the toner image pattern is formed on the image carrier falls within a predetermined range, the timing adjustment means changes the predetermined range based on the change of the toner image pattern by the pattern changing means. [Effects of the Invention]

[0006] According to the present invention, the decrease in the accuracy of detecting the amount of adhesion of the adjustment pattern of the adhesion amount detection means can be effectively suppressed. [Brief explanation of the drawing]

[0007] [Figure 1] Overall configuration diagram of the image forming apparatus. [Figure 2] A schematic diagram of the image-forming section of an image forming apparatus. [Figure 3] Schematic diagram of the intermediate transfer belt device. [Figure 4] A block diagram showing an example of the main components of the control system of the image forming apparatus according to this embodiment. [Figure 5] A schematic diagram illustrating the gradation pattern on the intermediate transfer belt. [Figure 6] A schematic diagram showing an example of an image adjustment pattern formed on an intermediate transfer belt when image adjustment is performed in parallel with the printing operation. [Figure 7] A diagram illustrating the formation location of the scraping pattern on the intermediate transfer belt. [Figure 8] A diagram illustrating the areas where minor cleaning defects occur. [Figure 9] This figure illustrates an example of changing the formation position of the adjustment pattern in this embodiment. [Figure 10] A diagram illustrating the case where the solid lubricant has not been depleted. [Figure 11] A diagram illustrating what happens when solid lubricant is depleted. [Figure 12] A diagram illustrating measures to prevent the tip of the cleaning blade from curling. [Figure 13] Flowchart for controlling changes in the scraping pattern due to a decrease in solid lubricant. [Figure 14] This diagram illustrates the distance from the scraping pattern after changing the timing of the formation of the adjustment pattern. [Figure 15] Flowchart showing the timing change for forming the adjustment pattern in this embodiment. [Figure 16] A diagram showing an example of the formation of the adjustment pattern in this embodiment. [Figure 17] A figure showing another example of the formation of the adjustment pattern in this embodiment. [Figure 18] A diagram showing yet another example of the formation of the adjustment pattern in this embodiment. [Figure 19] Flowchart of an example in which the formation of the adjustment pattern is discontinued. [Figure 20]A diagram showing an example of forming an adjustment pattern for canceling the formation (image formation) of an adjustment pattern. [Figure 21] A diagram showing an example of an embodiment in which the color of the scraping pattern is changed. [Figure 22] A diagram showing an example in which the scraping pattern is formed as a plurality of belt-like patterns formed at short intervals. [Figure 23] A diagram for explaining the scraping patterns of conditions (1) to (3) in the verification experiment. [Figure 24] A diagram for explaining the scraping patterns of conditions (4) to (6) in the verification experiment. [Figure 25] A diagram showing an example of forming a scraping pattern composed of a plurality of belt-like patterns.

Best Mode for Carrying Out the Invention

[0008] Hereinafter, the best mode for carrying out the present invention will be described based on the drawings. Those skilled in the art can easily modify and change the present invention within the scope of the claims to form other embodiments, and these modifications and changes are included in the scope of the claims. The following description is an example of the best mode of this invention and does not limit the scope of the claims. In each figure, the same or corresponding parts are denoted by the same reference numerals, and the redundant description will be appropriately simplified or omitted.

[0009] First, referring to FIGS. 1 to 3, the overall configuration and operation of the image forming apparatus 100 will be described. FIG. 1 is an overall configuration diagram of the image forming apparatus 100, FIG. 2 is a schematic configuration diagram of the image forming unit 6 which is an image forming means of the image forming apparatus 100, and FIG. 3 is a schematic configuration diagram of the intermediate transfer belt device 15. As shown in FIG. 1, an intermediate transfer belt device 15 (belt device) is installed at the center of the image forming apparatus 100. Further, image forming units 6Y, 6C, 6M, and 6K corresponding to each color (yellow, cyan, magenta, black) are arranged in parallel so as to face the intermediate transfer belt 8 (image carrier) of the intermediate transfer belt device 15.

[0010] The image-forming unit 6Y, corresponding to the yellow color shown in Figure 2, consists of a photoreceptor 1Y (latent image carrier) and a charging unit 4Y, a developing unit 5Y, a cleaning unit 2Y, a static elimination unit, etc., arranged around the photoreceptor 1Y. The image-forming process (charging, exposure, development, transfer, and cleaning) is performed on the surface of the photoreceptor 1Y, and a yellow image is formed on the photoreceptor 1Y.

[0011] Furthermore, the other three image units, 6C, 6M, and 6K, have almost the same configuration as the yellow-compatible image unit 6Y, except for the color of the toner used, and each forms an image corresponding to its respective toner color. Below, we will omit the explanations of the other three image units, 6C, 6M, and 6K as appropriate, and only explain the yellow-compatible image unit 6Y.

[0012] As shown in Figure 2, the photoreceptor 1Y, which carries the latent image, is driven to rotate counterclockwise by a motor. Then, at the position of the charging section 4Y, the surface of the photoreceptor 1Y is uniformly charged (charging process). Specifically, a charging bias is applied to the charging section 4Y from the charging power supply (see power supply section 62 in Figure 3). Subsequently, the surface of the photoreceptor 1Y reaches the irradiation position of the laser light L emitted from the exposure section 7, and an electrostatic latent image corresponding to yellow is formed by exposure scanning at this position (exposure process). In this way, an exposure potential is formed in the portion of the surface of the photoreceptor 1Y where the electrostatic latent image has been formed.

[0013] Subsequently, the surface of the photoreceptor 1Y reaches a position opposite the developing unit 5Y, where the electrostatic latent image is developed and a yellow toner image is formed (developing step). Next, the surface of the photoreceptor 1Y reaches a position opposite the intermediate transfer belt 8 (intermediate transfer body) and the primary transfer roller 9Y, which act as image carriers, where the toner image on the photoreceptor 1Y is transferred onto the intermediate transfer belt 8 (primary transfer step). At this point, a small amount of untransferred toner remains on the photoreceptor 1Y.

[0014] Next, the surface of the photoreceptor 1Y reaches a position opposite the cleaning unit 2Y, where any untransferred toner remaining on the surface of the photoreceptor 1Y is removed by the cleaning blade 2a (photoreceptor cleaning blade). The removed untransferred toner is collected in the cleaning unit 2Y (cleaning process).

[0015] The cleaning unit 2Y is equipped with a lubricant supply unit 3, which is a means for applying lubricant. The lubricant supply unit 3 applies lubricant to the surface of the photoreceptor 1Y. The lubricant supply unit 3 consists of a lubricant supply roller 3a, a solid lubricant 3b, a compression spring 3c, etc. The lubricant supply unit 3 rotates counterclockwise in Figure 2 and supplies lubricant while sliding against the photoreceptor 1Y. The solid lubricant 3b is in sliding contact with the lubricant supply roller 3a, and the compression spring 3c biases the solid lubricant 3b toward the lubricant supply roller 3a.

[0016] The surface of the photoreceptor 1Y, having passed through the cleaning section 2Y, reaches a position opposite the static elimination section, where the residual potential on the photoreceptor 1 is removed. In this way, the series of imaging processes performed on the photoreceptor 1Y are completed.

[0017] The image formation process described above is carried out in the other image formation units 6C, 6M, and 6K in the same way as in the yellow image formation unit 6Y. Specifically, a laser beam L based on image information is irradiated from the exposure unit 7, which is located above the image formation unit 6, toward the surface of the photoreceptors 1C, 1M, and 1K of each image formation unit 6C, 6M, and 6K. More specifically, the exposure unit 7 emits a laser beam L from a light source and irradiates the photoreceptor onto it via multiple optical elements while scanning the laser beam L with a rotating polygon mirror. After that, the toner images of each color formed on each photoreceptor through the development process are superimposed onto the intermediate transfer belt 8 and primary transferred. In this way, a color image (toner image) is supported (formed) on the surface of the intermediate transfer belt 8.

[0018] As shown in Figure 3, the intermediate transfer belt device 15 consists of an intermediate transfer belt 8 as an image carrier, four primary transfer rollers 9Y, 9C, 9M, and 9K, a drive roller 12A, a secondary transfer opposing roller 80, a tension roller 12B, driven rollers 12C and 12D, a cleaning opposing roller 13, a cleaning blade 10 (cleaning member), a secondary transfer roller 70 (transfer member), an optical sensor unit 40, and the like. The intermediate transfer belt 8 is stretched and supported by multiple roller members 80, 12A to 12D, and 13, and is moved endlessly in the direction of the arrow in Figure 3 by the rotational drive of one roller member (drive roller 12A) by a drive motor 61.

[0019] The four primary transfer rollers 9Y, 9C, 9M, and 9K each have an intermediate transfer belt 8 sandwiched between them and the photoreceptors 1Y, 1C, 1M, and 1K to form a primary transfer nip. A transfer voltage (primary transfer bias) with the opposite polarity to the toner polarity is then applied to the primary transfer rollers 9Y, 9C, 9M, and 9K from the primary transfer power supply of the power supply unit 62.

[0020] The intermediate transfer belt 8 travels in the direction of the arrow, sequentially passing through the primary transfer nips of the primary transfer rollers 9Y, 9C, 9M, and 9K, and the toner images of each color formed on the surface of the photoreceptors 1Y, 1C, 1M, and 1K are superimposed onto the surface of the intermediate transfer belt 8 and primary transferred.

[0021] The intermediate transfer belt 8, on which the toner images of each color have been superimposed and primary transferred, reaches a position opposite the secondary transfer roller 70 (transfer member). At this position, the secondary transfer opposing roller 80 sandwiches the intermediate transfer belt 8 between itself and the secondary transfer roller 70, forming a secondary transfer nip. The four toner images formed on the intermediate transfer belt 8 are then secondary transferred onto the paper P (sheet) that has been transported to the position of this secondary transfer nip. At this time, untransferred toner remains on the intermediate transfer belt 8 that was not transferred to the paper P.

[0022] The intermediate transfer belt 8 reaches the position of the cleaning blade 10 (cleaning member). At this position, any untransferred toner, paper dust, or other adhering materials on the intermediate transfer belt 8 are removed. Thus, the series of transfer processes performed on the intermediate transfer belt 8 are completed.

[0023] As shown in Figure 1, the paper P to be transported to the secondary transfer nip position is transported from the paper feed unit 26 located below the image forming apparatus 100, via the paper feed roller 27 and the pair of registration rollers 28. Specifically, the paper feed unit 26 stores multiple sheets of paper P stacked on top of each other. When the paper feed roller 27 is driven to rotate counterclockwise in Figure 1, the top sheet of paper P is fed towards the space between the rollers of the pair of registration rollers 28.

[0024] The paper P, transported to the registration roller pair 28, temporarily stops at the position of the roller nip of the registration roller pair 28, where the rotational drive has been stopped. In time with the color image on the intermediate transfer belt 8, the registration roller pair 28 is driven to rotate, transporting the paper P toward the secondary transfer nip, and the desired color image is transferred onto the paper P.

[0025] The paper P onto which the color image has been transferred at the secondary transfer nip is transported to the fixing unit 20, where the heat and pressure from the fixing belt and pressure rollers fix the transferred color image onto the paper P. The paper P is then discharged from the device by a pair of discharge rollers. The paper P discharged from the device by the discharge rollers is then sequentially stacked on the stacking unit as output images. Thus, the image forming process in the image forming apparatus 100 is completed.

[0026] Next, Figure 2 will provide a more detailed explanation of the configuration and operation of the developing unit 5Y (developing device) in the image-making unit 6. The developing unit 5Y consists of a developing roller 51Y facing the photoreceptor 1Y, a doctor blade 52Y facing the developing roller 51Y, two transport screws 55Y disposed within the developer container, a density detection sensor 56Y for detecting the toner concentration in the developer, and the like. The developing roller 51Y consists of a magnet fixed inside and a sleeve that rotates around the magnet. The developer container holds a two-component developer consisting of a carrier and toner.

[0027] The sleeve of the developing roller 51Y rotates in the direction of the arrow in Figure 2, and the developer supported on the developing roller 51Y by the magnetic field formed by the magnet moves along the developing roller 51Y as the sleeve rotates. The developer in the developing unit 5Y is adjusted so that the proportion of toner in the developer (toner concentration) is within a predetermined range. Specifically, when the density detection sensor 56Y detects that the toner concentration has fallen below a predetermined range, the control unit 60 (see Figure 3) controls the toner supply unit 63, and new toner is supplied from the toner container to the developing unit 5Y. This adjusts the proportion of toner in the developer (toner concentration) so that it is within a predetermined range.

[0028] The toner supplied to the developer container of the developing unit 5Y is mixed and agitated with the developer by two transport screws 55Y, and circulates between two isolated developer containers (movement in the direction perpendicular to the paper plane in Figure 2). The toner in the developer is attracted to the carrier by triboelectric charging and is supported on the developing roller 51Y together with the carrier by the magnetic force formed on the developing roller 51Y.

[0029] The developer supported on the developing roller 51Y is transported in the direction of the arrow in Figure 2 to the position of the doctor blade 52Y. At this position, the amount of developer on the developing roller 51Y is adjusted to the appropriate level, and then it is transported to the position opposite the photoreceptor 1Y (developing region). Then, the toner is attracted to the latent image formed on the photoreceptor 1Y by the electric field formed in the developing region. After that, the developer remaining on the developing roller 51Y reaches above the developer storage section as the sleeve rotates, and at this position it is detached from the developing roller 51Y. The electric field formed in the development area is created by the potential difference between the exposure potential (image potential) formed on the photoreceptor 1Y and the development bias applied to the development roller 51Y from the development power supply (see power supply unit 62 in Figure 3).

[0030] Next, the intermediate transfer belt device 15 in this embodiment will be described in detail using Figure 3 and other figures. As shown in Figure 3, the intermediate transfer belt device 15, as a belt device, consists of an intermediate transfer belt 8 as an image carrier, four primary transfer rollers 9Y, 9C, 9M, and 9K, a drive roller 12A, a secondary transfer opposing roller 80, a tension roller 12B, driven rollers 12C and 12D, a cleaning opposing roller 13, a cleaning blade 10, a secondary transfer roller 70, and an optical sensor unit 40 consisting of multiple optical sensors.

[0031] As explained earlier, the intermediate transfer belt 8, acting as an image carrier, receives primary transfers of toner images formed on the surfaces of multiple photoreceptors 1Y, 1C, 1M, and 1K, each as an image portion. The intermediate transfer belt 8 is positioned opposite the four photoreceptors 1Y, 1C, 1M, and 1K. The intermediate transfer belt 8 is primarily stretched and supported by six roller members (drive roller 12A, secondary transfer opposing roller 80, tension roller 12B, driven rollers 12C, 12D, and cleaning opposing roller 13).

[0032] The intermediate transfer belt 8 is composed of one or more layers of PVDF (vinyldenine fluoride), ETFE (ethylene-tetrafluoroethylene copolymer), PI (polyimide), PC (polycarbonate), etc., with conductive materials such as carbon black dispersed within it. The intermediate transfer belt 8 has a volume resistivity of 10 6 ~10 13 Ωcm, surface resistivity on the back side of the belt is 10 7 ~10 13 It is adjusted to be in the range of Ωcm. In addition, the intermediate transfer belt 8 is set to have a thickness in the range of 20 to 200 μm. In this embodiment, the thickness of the intermediate transfer belt 8 is about 60 μm, and the volume resistivity is 10 9 It is set to approximately Ωcm.

[0033] A release layer may be coated onto the surface of the intermediate transfer belt 8 as needed. Examples of materials that can be used for coating include fluororesins such as ETFE (ethylene-tetrafluoroethylene copolymer), PTFE (polytetrafluoroethylene), PVDF (vinyldenine fluoride), PEA (perfluoroalkoxy fluororesin), FEP (tetrafluoroethylene-hexafluoropropylene copolymer), and PVF (vinyl fluoride). However, the material is not limited to these.

[0034] The primary transfer rollers 9Y, 9C, 9M, and 9K each face the corresponding photoreceptor 1Y, 1C, 1M, and 1K via the intermediate transfer belt 8. Specifically, the primary transfer roller 9Y for yellow faces the yellow photoreceptor 1Y via the intermediate transfer belt 8. The primary transfer roller 9M for magenta faces the magenta photoreceptor 1M via the intermediate transfer belt 8. The primary transfer roller 9C for cyan faces the cyan photoreceptor 1C via the intermediate transfer belt 8. The primary transfer roller 9K for black faces the black photoreceptor 1K via the intermediate transfer belt 8. The primary transfer rollers 9Y, 9C, 9M, and 9K are elastic rollers each with a conductive sponge layer with an outer diameter of approximately 16 mm formed on a core metal with a diameter of approximately 10 mm. The volume resistivity of the primary transfer rollers 9Y, 9C, 9M, and 9K is 10 6 ~10 12Ω (preferably, 10 7 ~10 9 Ω) and is adjusted to be within this range.

[0035] The driving roller 12A is rotationally driven by a driving motor 61 controlled by the control unit 60, and the intermediate transfer belt 8 travels in a predetermined traveling direction (clockwise direction in FIG. 3).

[0036] The tension roller 12B is in contact with the outer peripheral surface of the intermediate transfer belt 8. The two driven rollers 12C and 12D are in contact with the inner peripheral surface of the intermediate transfer belt 8. A cleaning blade 10 is installed between the secondary transfer opposing roller 80 and the tension roller 12B so as to face the cleaning opposing roller 13 through the intermediate transfer belt 8. This cleaning blade 10 is in sliding contact with the surface of the intermediate transfer belt 8 to clean foreign substances such as untransferred toner and paper dust adhering to the surface of the intermediate transfer belt 8. The foreign substances removed by the cleaning blade 10 are collected inside the intermediate transfer cleaning unit in which the cleaning blade 10 is held.

[0037] The secondary transfer opposing roller 80 is in contact with the secondary transfer roller 70 through the intermediate transfer belt 8. The secondary transfer opposing roller 80 has a volume resistance of 10 7 ~10 8 Ω or so, and an elastic layer 83 (layer thickness is about 5 mm) made of NBR rubber with a hardness (JIS - A hardness) of about 48 to 58 degrees is formed on the outer peripheral surface of a cylindrical core made of stainless steel or the like.

[0038] Furthermore, the secondary transfer opposing roller 80 is electrically connected to the power supply unit 62 (secondary transfer power supply), and a secondary transfer bias of approximately -10kV is applied from this power supply. This secondary transfer bias applied to the secondary transfer opposing roller 80 is for secondary transfer of the toner image carried on the intermediate transfer belt 8 to the paper P being transported to the secondary transfer nip. The secondary transfer bias is a bias (DC voltage) with the same polarity as the toner (negative polarity in this embodiment). As a result, the toner carried on the toner-carrying surface (outer circumference) of the intermediate transfer belt 8 is electrostatically moved from the secondary transfer opposing roller 80 side to the secondary transfer roller 70 side by the secondary transfer electric field.

[0039] The secondary transfer roller 70 contacts the toner-carrying surface (outer circumference) of the intermediate transfer belt 8, forming a secondary transfer nip on which the paper P is transported. The secondary transfer roller 70 has an outer diameter of approximately 15.5 mm. The secondary transfer roller 70 has an elastic layer formed (coated) on a hollow core metal of approximately 9 mm in diameter, made of stainless steel, aluminum, etc., with a hardness (Asker C hardness) of approximately 40 to 50 degrees. The elastic layer of the secondary transfer roller 70 is formed in a solid or foamed sponge form by dispersing conductive fillers such as carbon or incorporating ionic conductive materials in a rubber material such as polyurethane, EPDM, or silicone. The elastic layer has a volume resistance of 10 to suppress the concentration of the transfer current. 6.5 ~10 7.5 It is set to approximately Ω. Furthermore, a release layer made of semiconductive fluororesin or urethane resin may be formed on the surface of the secondary transfer roller 70 to improve the release properties of the roller surface from the toner.

[0040] Figure 4 is a block diagram showing an example of the main components of the control system of the image forming apparatus 100 according to this embodiment. The image forming apparatus 100 includes a control unit 60, which is composed of a computer device such as a microcomputer. The control unit 60 includes a CPU (Central Processing Unit) 60a. It also includes a ROM (Read Only Memory) 60c and a RAM (Random Access Memory) 60b as storage means connected to the CPU 60a via a bus line. The CPU 60a performs various calculations and drive control of various parts by executing a control program, which is a pre-installed computer program. The ROM 60c stores fixed data such as computer programs and control data in advance. The RAM 60b functions as a work area, etc., that stores various data in a rewritable manner.

[0041] ROM 60c stores a conversion table containing information on the conversion of the output value of the optical sensor unit 40 to the amount of toner deposited per unit area. ROM 60c also stores control target values ​​for the image formation conditions of each imaging unit in the image forming apparatus 100 (e.g., charging bias, development bias, exposure amount, primary transfer bias, etc.), as well as the cumulative number of printed sheets for each imaging unit.

[0042] The control unit 60 may be configured using, for example, an IC (integrated circuit) manufactured for control purposes in an image forming apparatus 100, rather than a computer device such as a microcomputer.

[0043] In this image forming apparatus 100, in order to stabilize image quality in response to environmental fluctuations and over time, a control called process control is performed at predetermined timings. Figure 5 is a schematic diagram illustrating the gradation pattern on the intermediate transfer belt.

[0044] The gradation pattern consists of multiple toner patches with different image densities, and these gradation patterns are formed at the positions of the intermediate transfer belt 8 opposite the optical sensor (the center in the width direction and both ends). In the example shown in Figure 4, gradation patterns of black, cyan, magenta, and yellow are formed from top to bottom.

[0045] The optical sensor unit 40 has multiple optical sensors 40R, 40C, and 40F, which serve as adhesion amount detection means, arranged at predetermined intervals in the belt width direction of the intermediate transfer belt 8. Each optical sensor outputs a signal corresponding to the light reflectance of the intermediate transfer belt 8 and the gradation patterns PKPC, PM, and PY on the intermediate transfer belt 8, and detects the amount of toner adhesion. The image forming apparatus 100 adjusts the image formation conditions, such as the development bias Vb, based on the detected amount of toner adhesion.

[0046] The optical sensors 40R and 40F, positioned opposite the widthwise end region of the intermediate transfer belt 8, are located outside the paper feeding region. Therefore, as shown in Figure 6, during toner image formation for transfer to paper, an image adjustment pattern is formed outside the paper feeding region, and the amount of toner deposited on this image adjustment pattern is detected by the optical sensors 40R and 40F. Based on the amount of toner deposited detected by the optical sensors 40R and 40F, the development bias and other factors can be adjusted to control the image density and other settings.

[0047] The toner's base components, as well as silica, titanium dioxide, and other so-called toner additives added to the toner, are transferred from the photoreceptor 1 to the intermediate transfer belt 8. These toner additives transferred to the intermediate transfer belt 8 can adhere to the belt, causing filming on the belt. In addition to the toner additives, various components contained in the lubricant, such as boron nitride and zinc stearate, are also transferred from the photoreceptor 1 to the intermediate transfer belt 8. The toner additives and lubricant then interact with each other, which can worsen the filming on the intermediate transfer belt 8. Furthermore, at the secondary transfer nip, paper dust from the paper P is transferred to the intermediate transfer belt 8 and adheres to the belt, causing paper dust filming.

[0048] This type of filming on the intermediate transfer belt 8 occurs when filming substances, such as silica and other toner additives and various components contained in lubricants, adhere to the intermediate transfer belt 8 due to external pressure on the belt 8 (mainly contact pressure with the photoreceptor 1). When filming occurs on the intermediate transfer belt 8, if a full solid image or halftone image is output, toner will not adhere to the areas corresponding to the filming, resulting in abnormal images such as white areas or so-called white spots.

[0049] Furthermore, when filming occurs, the glossiness of the belt decreases. Therefore, if filming occurs in the region of the intermediate transfer belt 8 facing the optical sensors 40R, 40C, and 40F, the output signal changes, making it impossible to accurately detect the amount of gradation pattern deposited on the intermediate transfer belt. In addition, unevenness in the filming state can lead to unstable output from the optical sensors, resulting in problems with proper image adjustment.

[0050] Furthermore, filming may reduce the cleaning performance of the cleaning blade 10. In the belt width direction, the positions corresponding to the placement of the optical sensors 40R, 40C, and 40F on the cleaning blade 10 are frequently input with gradation patterns that have a large amount of toner deposited per unit area. Therefore, if filming occurs in the area of ​​the intermediate transfer belt 8 facing the optical sensors 40R, 40C, and 40F, the risk of cleaning failure (toner slippage) occurring when a gradation pattern is input to the cleaning blade 10 increases.

[0051] The above-mentioned filming can be scraped off by the toner that remains at the contact points between the cleaning blade 10 and the surface of the intermediate transfer belt 8 (hereinafter referred to as the "cleaning points"), and removed from the surface of the intermediate transfer belt 8. Specifically, the filming on the surface of the intermediate transfer belt is scraped off by the unevenness of the toner surface remaining at the cleaning points and the pressure of the cleaning blade 10 on the toner.

[0052] Therefore, in order to suppress filming of the intermediate transfer belt 8, the image forming apparatus 100 forms a scraping pattern on the intermediate transfer belt 8 at a predetermined timing. Then, by inputting this scraping pattern to the cleaning blade 10, a sufficient amount of toner is ensured to remain in the cleaning area.

[0053] Figure 7 illustrates the formation position of the scraping pattern on the intermediate transfer belt. Figure 7 shows the result of printing three images consecutively using a normal image forming operation. As shown in Figure 7, the formation positions of the scraping pattern are as follows: 1. Position in front of the first sheet of paper on the secondary transfer nip. 2. Position outside the width of the paper being fed through the secondary transfer nip. 3. Position of the non-image-forming region at the trailing edge of the paper that is fed through the secondary transfer nip. 4. Position between pages 5. Position of the final sheet after it has passed through the secondary transfer nip. These are some examples. Regarding point 2 above, this configuration can be adopted when the width of the intermediate transfer belt 8 is wider than the axial length of the secondary transfer roller 70, and the secondary transfer roller 70 does not come into contact with the intermediate transfer belt 8 at the position described in point 2. This is because, in the case where the secondary transfer roller 70 comes into contact with the intermediate transfer belt 8 at the position described in point 2, the scraping pattern at the end formed at the position described in point 2 (hereinafter referred to as the end pattern) is transferred to the secondary transfer roller 70. Furthermore, since only the end of the intermediate transfer belt 8 in the width direction can be removed at the position described in point 2 alone, it is necessary to combine it with the strip-shaped scraping patterns (hereinafter referred to as the strip patterns) that are long in the width direction of the intermediate transfer belt 8 as described in points 1 and 3 to 5 above. The strip patterns described in points 1 and 3 to 5 above may be formed with any of the toners Y, M, C, or K, or two or more of the toners Y, M, C, or K may be layered. Alternatively, multiple strip patterns of different toner colors may be formed at predetermined intervals.

[0054] The end pattern formed at the position described in 2. above may be formed by creating multiple toner patches at predetermined intervals, or it may be a long line in the direction of surface movement of the intermediate transfer belt 8. Furthermore, if the end pattern is composed of multiple toner patches, the colors of the multiple toner patches may be different from each other, or the colors of the multiple toner patches may be the same.

[0055] Regarding item 3 above, the position may also be the non-image-forming region at the leading edge of the paper that is fed through the secondary transfer nip. Regarding items 1, 3 to 5 above, when the strip-shaped pattern on the intermediate transfer belt passes through the secondary transfer nip, a positive polarity bias is applied to the secondary transfer opposing roller 80. By applying a positive polarity bias to the secondary transfer opposing roller 80, the strip-shaped pattern is electrostatically attracted to the intermediate transfer belt 8, preventing the strip-shaped pattern from being transferred to the secondary transfer roller 70 or the paper P.

[0056] The control unit 60 measures the travel distance of the intermediate transfer belt 8 and calculates the required toner input amount to the cleaning blade 10 based on the filming condition on the surface of the intermediate transfer belt 8, based on the measured travel distance of the intermediate transfer belt 8. Specifically, the required toner input amount is calculated by multiplying the travel distance of the intermediate transfer belt 8 by a coefficient. The calculated required toner input amounts are added together to calculate the cumulative value of the required toner input amount, and if the cumulative value of the required toner input amount exceeds a threshold, a scraping pattern is formed. Next, the amount of toner in the formed scraping pattern (amount of toner input to the cleaning blade 10) is subtracted from the above cumulative value. Then, the calculated required toner input amounts are added together, and if the cumulative value of the required toner input amount exceeds a threshold again, a scraping pattern is formed.

[0057] The above coefficient may be a fixed value, or for example, the coefficient may be changed between the color image mode and the monochrome image mode. This is because the filming may deteriorate more in the color image mode than in the monochrome image mode. In the color image mode, the fixing set temperature is higher and the number of operating motors increases compared to the monochrome image mode, so the temperature inside the machine tends to rise. When the temperature inside the machine rises, the amount of stick slip of the cleaning blade 10 increases, and there is a risk that filming will deteriorate. Also, when there is a lubricant application part for applying a lubricant to the surface of the photoreceptor 1, in the color image mode, the amount of lubricant, which is a component of the filming substance adhering to the intermediate transfer belt 8, increases compared to the monochrome mode. Therefore, there is a risk that filming will deteriorate more in the color image mode than in the monochrome image mode.

[0058] Therefore, for example, the coefficient B in the color image mode is set to a value higher than the coefficient A in the monochrome image mode (A < B). Then, when forming an image (when driving the intermediate transfer belt), it is determined whether it is the monochrome image mode or the color image mode. In the monochrome image mode, the required toner input amount is calculated using the coefficient A, and in the color image mode, the required toner input amount is calculated using the coefficient B.

[0059] For example, when the color image mode is used frequently, as described above, the risk of filming deterioration is higher than in the monochrome image mode. However, when the color image mode is used frequently, since the integrated value of the required toner input amount exceeds the threshold value at a short running distance of the intermediate transfer belt 8, the scraping pattern is formed at an early timing. On the other hand, when the monochrome image mode is used frequently, filming is less likely to deteriorate compared to the color image mode. Therefore, when the monochrome image mode is used frequently, the running distance at which the integrated value of the required toner input amount exceeds the threshold value becomes longer, and the scraping pattern is formed at a late timing.

[0060] In this way, by forming the scraping pattern based on the image mode, the scraping pattern can be formed at an appropriate timing, and unnecessary toner consumption and deterioration of filming can be favorably suppressed.

[0061] During the operation of the image forming apparatus 100, the ground soiling toner is continuously supplied from the developing unit 5, and this ground soiling toner may adhere between sheets of paper or outside the paper passing area of the intermediate transfer belt 8. The ground soiling toner adhering between sheets of paper or outside the paper passing area is input to the cleaning blade 10. The filming of the intermediate transfer belt 8 is also scraped off by the ground soiling toner input to the cleaning blade 10. As a result, the amount of filming of the intermediate transfer belt 8 varies according to the amount of ground soiling toner input to the cleaning blade 10.

[0062] Therefore, the coefficient may be changed based on the amount of ground soiling toner input to the cleaning blade 10. In a high-temperature and high-humidity environment, the amount of ground soiling toner increases, and the filming scraped off by this ground soiling toner is more than in a low-temperature and low-humidity environment or a normal-temperature and normal-humidity environment. Therefore, for example, the ground soiling coefficient G1 may be used in a high-temperature and high-humidity environment, the ground soiling coefficient G2 (G1 < G2) in a normal-temperature and normal-humidity environment, and the ground soiling coefficient G3 (G2 < G3) in a low-temperature and low-humidity environment, and the required toner input amount may be calculated. Thereby, in a high-temperature and high-humidity environment where the amount of ground soiling toner is large, the running distance at which the integrated value of the required toner input amount exceeds the threshold value becomes long, and the scraping pattern is formed at a late timing.

[0063] In this way, by forming the scraping pattern based on the amount of ground soiling toner, the scraping pattern can be formed at an appropriate timing, and unnecessary toner consumption and deterioration of filming can be favorably suppressed.

[0064] To effectively remove filming, the amount of toner input to the cleaning area by the scraping pattern should be as large as possible, but too much toner may result in cleaning failure. Therefore, the amount of toner input to the cleaning area by the scraping pattern is set to the minimum level that does not cause cleaning failure. However, under conditions where cleaning failure is likely to occur (e.g., over time, after being left unattended, in a high-temperature, high-humidity environment), minor cleaning failures may occur in the non-paper-feed area of ​​the intermediate transfer belt 8, which is outside the paper-feed area in the belt width direction. This is because in the paper-feed area of ​​the intermediate transfer belt 8, the secondary transfer nip comes into contact with the paper, and some of the filming material on the intermediate transfer belt 8 adheres to the paper. On the other hand, in the non-paper-feed area, the filming material does not adhere to the paper. Therefore, filming is more likely to worsen in the non-paper-feed area than in the paper-feed area. As described above, filming can reduce the cleaning performance of the cleaning blade 10, and minor cleaning failures occur only in the non-paper-feed area, where filming is more likely to worsen than in the paper-feed area.

[0065] Figure 8 illustrates the region in the surface movement direction of the intermediate transfer belt 8 where minor cleaning defects occur. Minor cleaning defects occur after the cleaning blade has passed, starting from the downstream end A of the scraping pattern KP on the intermediate transfer belt 8 in the direction of surface movement of the intermediate transfer belt 8 (see Figure 8(c)).

[0066] As shown in Figure 8(d), in the primary transfer nip, after the primary transfer of the scraping pattern KP, the starting point A of the minor cleaning defect area where cleaning defect toner is attached reaches the primary transfer nip after one rotation of the intermediate transfer belt 8. As shown in Figure 8(e), when this minor cleaning defect area passes the cleaning area of ​​the cleaning blade 10, the cleaning defect toner in the cleaning defect area is removed by the cleaning blade 10. Therefore, as shown in Figure 8(f), at least in the primary transfer nip, after the primary transfer of the scraping pattern KP and the second rotation of the intermediate transfer belt 8, the area of ​​the intermediate transfer belt 8 where no cleaning defect has occurred will pass through the primary transfer nip. In Figure 8, minor cleaning defects occur over one rotation of the intermediate transfer belt 8, but the area in which minor cleaning defects occur varies depending on the configuration of the device. For example, if the circumference of the intermediate transfer belt 8 is long, the area in which minor cleaning defects occur will be considerably shorter than one rotation of the intermediate transfer belt 8.

[0067] Therefore, in this embodiment, if the adjustment pattern is formed in a minor cleaning defect area on the intermediate transfer belt shown in Figure 8, the timing of the adjustment pattern formation is adjusted and the position of the adjustment pattern is changed.

[0068] Figure 9 illustrates an example of changing the formation position of the adjustment pattern in this embodiment. As explained using Figure 8, the area where minor cleaning defects occur is the region where the distance from the scraping pattern formation position is between one and two circumferences of the intermediate transfer belt 8. When the adjustment pattern is formed by intermediate transfer in that region, the control unit 60 changes the formation timing of the adjustment pattern and changes the formation position of the adjustment pattern. Thus, in this embodiment, the control unit 60 functions as a timing adjustment means.

[0069] The distance from the scraping pattern formation position (the position where the pattern is first transferred to the intermediate transfer belt 8) to the adjustment pattern formation position (the position where the pattern is first transferred to the intermediate transfer belt 8) can be determined from the driving time of the intermediate transfer belt 8.

[0070] The adjustment pattern RP1 shown in Figure 9 is formed at a position less than one rotation of the intermediate transfer belt from the position of the scraping pattern KP (it is first transferred to the intermediate transfer belt 8). Therefore, the control unit 60 determines that the adjustment pattern RP1 is formed outside the area where minor cleaning defects occur, and the adjustment pattern RP1 is imaged without changing the timing of image formation.

[0071] On the other hand, the adjustment pattern RP2 is formed (primarily transferred) between the position of the scraping pattern KP1 and the first to second turns of the intermediate transfer belt. This adjustment pattern RP2 is formed (primarily transferred) in the area of ​​the intermediate transfer belt 8 where minor cleaning defects occur. Therefore, the accuracy of the optical sensors 40F and 40R in detecting the amount of toner deposited on the adjustment pattern may decrease due to the influence of poorly cleaned toner that has slipped through the cleaning blade 10.

[0072] Accordingly, the control unit 60 changes the imaging timing so that the adjustment pattern RP2 is at least two turns away from the position where the scraping pattern KP1 is formed (primarily transferred) on the intermediate transfer belt 8. As a result, the adjustment pattern RP2 is not formed (primarily transferred) in the area of ​​the scraping pattern KP1 where minor cleaning defects occur. Consequently, it is possible to prevent positional misalignment control defects due to false detection of the adjustment pattern and image density adjustment defects due to a decrease in the accuracy of detecting the amount of the adjustment pattern attached.

[0073] As described above, the lubricant adhering to the intermediate transfer belt 8 is one factor that worsens the filming on the intermediate transfer belt 8, but it also has the advantage of reducing the coefficient of friction between the surface of the intermediate transfer belt and the cleaning blade 10, thereby suppressing the curling of the tip of the cleaning blade 10. As shown in Figure 10, when there is solid lubricant 3b in the lubricant supply unit 3, the part of the cleaning blade 10 that contacts the paper-feeding area of ​​the intermediate transfer belt 8 receives residual toner, lubricant, and background soiled toner. The part that contacts the non-paper-feeding area receives lubricant and background soiled toner continuously. Therefore, when there is solid lubricant 3b in the lubricant supply unit 3, the curling of the tip of the cleaning blade 10 is well suppressed, and abnormal wear of the tip of the cleaning blade 10 is suppressed.

[0074] Figure 11 illustrates the case when the solid lubricant 3b is depleted. The solid lubricant 3b is biased toward the lubricant supply roller 3a by compression springs 3c at both ends in the longitudinal direction (width direction of the device). However, due to the uneven biasing force between the compression springs 3c, one side in the longitudinal direction (left side in the figure) is depleted faster than the other side (right side in the figure), as shown in Figure 11.

[0075] Therefore, in the non-paper-feeding area on the lubricant-depleted side of the intermediate transfer belt 8, the amount of lubricant adhering to it decreases. Also, the amount of background toner supplied from the developing unit 5 decreases. As a result, the frictional force with the intermediate transfer belt 8 increases on the lubricant-depleted side of the cleaning blade 10, and there is a risk that peeling may occur at the tip of the cleaning blade 10 on the lubricant-depleted side.

[0076] To suppress the peeling of the cleaning blade 10 due to lubricant depletion, a toner image pattern is periodically applied to the lubricant-depleted side of the cleaning blade 10, as shown in Figure 12. This improves the slippage between the cleaning blade 10 and the intermediate transfer belt 8 by the toner that is held back by the cleaning blade 10 on the lubricant-depleted side, thereby suppressing the peeling of the tip of the cleaning blade 10.

[0077] It is unclear whether one end or the other end of the solid lubricant 3b in the longitudinal direction will be depleted first. Therefore, when the solid lubricant 3b is depleted and reaches the end of its lifespan, a toner image pattern will be formed (primary transfer) in the non-paper-feeding areas on both sides of the intermediate transfer belt 8.

[0078] In this embodiment, when the solid lubricant 3b of one of the multiple image-forming units reaches the end of its lifespan, the control unit 60 changes the scraping pattern from a strip-shaped pattern to a combination of a strip-shaped pattern and an edge pattern formed at a position outside the width of the paper passed through the secondary transfer nip (as shown in Figure 7, 2.). This increases the amount of toner input to the non-paper-passing area of ​​the cleaning blade 10 (the area that contacts the non-paper-passing area of ​​the intermediate transfer belt 8) over a predetermined period. As a result, the shortage of background soiling toner can be compensated for, and the curling of the tip of the cleaning blade 10 can be suppressed. Thus, in this embodiment, the control unit 60 functions as a pattern changing means.

[0079] Figure 13 is a flowchart illustrating the control of the change in the scraping pattern as the amount of solid lubricant 3b decreases. The depletion (lifespan) of the solid lubricant 3b is estimated based on the cumulative number of prints since the image-making unit was put into use. The depletion (lifespan) of the solid lubricant 3b varies depending on how the machine is used and environmental factors such as temperature and humidity. Therefore, the average number of prints at which the solid lubricant 3b reaches the end of its lifespan (depletes), which has been determined in advance through experiments, is stored as the lubricant lifespan in the memory means (ROM 60c) of the control unit 60.

[0080] When the cumulative number of printed sheets of any of the multiple image-forming units reaches (lifetime - P sheets) (Yes in S1), the control unit 60 changes the scraping pattern from a strip pattern to a combination of a strip pattern and an edge pattern (S2).

[0081] Next, when the cumulative number of printed sheets of any of the multiple image-forming units reaches the lubricant lifespan (Yes in S3), the control unit 60 increases the amount of toner deposited on the edge pattern and increases the amount of toner input to the non-paper-feeding area of ​​the cleaning blade 10 (S4). If the edge pattern is a solid image, the amount of toner deposited on the edge pattern can be increased as follows: If the edge pattern consists of multiple toner patches, the amount of toner deposited on the edge pattern can be increased by increasing the number of toner patches. If the edge pattern is a line-shaped pattern extending in the direction of surface movement of the intermediate transfer belt 8, the amount of toner deposited on the edge pattern can be increased by extending the length of the edge pattern in the direction of surface movement. In addition, the amount of toner deposited on the edge pattern can also be increased by overlapping two or more toners.

[0082] Next, if the cumulative number of printed pages in the image-making unit exceeds the lifespan + P pages (Yes in S5), the amount of toner adhering to the edge pattern is further increased, and the amount of toner input to the non-paper-feeding area of ​​the cleaning blade 10 is further increased (S6).

[0083] In the above description, the lifespan (depletion) of the solid lubricant 3b is estimated based on the cumulative number of printed pages, but the lifespan (depletion) of the solid lubricant 3b may also be estimated based on the travel distance of the photoreceptor 1 in the image-forming unit. Furthermore, in the above description, the amount of toner input to the non-paper-feeding area of ​​the cleaning blade 10 over a predetermined period is increased by increasing the amount of toner adhering to the edge pattern, but the following may also be used. That is, the amount of toner input to the non-paper-feeding area of ​​the cleaning blade 10 over a predetermined period may be increased by increasing the frequency of formation of the scraping pattern.

[0084] Specifically, when the cumulative number of printed pages reaches the lifespan of the lubricant, the coefficient used to calculate the required toner input amount, as described above, which determines the formation of a scraping pattern, is increased to increase the frequency of scraping pattern formation. When the cumulative number of printed pages in the image-forming unit exceeds the lifespan + P pages, the coefficient used to calculate the required toner input amount is further increased to further increase the frequency of scraping pattern formation. In this way, increasing the frequency of scraping pattern formation also increases the amount of toner input to the non-paper-feeding area of ​​the cleaning blade 10 over a predetermined period, thereby suppressing curling at the leading edge of the non-paper-feeding area of ​​the cleaning blade 10.

[0085] As the amount of solid lubricant 3b decreases, the amount of toner input to the non-paper-feeding area of ​​the cleaning blade 10 over a predetermined period increases. This can lead to a greater amount of toner passing through the cleaning blade 10 in the non-paper-feeding area, potentially worsening cleaning performance. Specifically, as explained using Figure 11, the biasing force between the compression springs 3c is uneven. As a result, the lubricant is depleted only on one side in the longitudinal direction, as shown in Figure 11, while the lubricant remains unchanged on the other side. Therefore, in the non-paper-feeding area on the side where the lubricant is not depleted, filming caused by the lubricant occurs, potentially resulting in poor cleaning performance of the cleaning blade 10. Furthermore, since there is no reduction in background soiling toner in the non-paper-feeding area on the side where the lubricant is not depleted, the amount of toner input to the non-paper-feeding area on the side where the lubricant is not depleted over a predetermined period is greater than that in the non-paper-feeding area on the side where the lubricant is depleted. As a result, cleaning problems may worsen in the non-paper-feeding area on the side of the cleaning blade 10 where the lubricant has not been depleted.

[0086] Furthermore, depending on how the machine is used and environmental factors such as temperature and humidity, the amount of solid lubricant 3b may not decrease as much as estimated based on the cumulative number of printed pages and the distance traveled by the photoreceptor. In this case, cleaning problems will worsen in the non-paper-feeding areas on both sides.

[0087] When the scraping pattern is input, a large amount of toner slips through the cleaning blade 10, worsening the cleaning failure. As a result, the intermediate transfer belt 8 completes one rotation, and a large amount of toner slips through is input to the cleaning blade 10 again. Furthermore, because a large amount of toner is input to the cleaning blade 10, even when the cleaning failure originating point A on the intermediate transfer belt 8, as shown in Figure 8, passes through the cleaning blade 10 again, a large amount of toner is blocked by the cleaning blade 10. Consequently, even after the first transfer of the scraping pattern and the second rotation of the intermediate transfer belt 8, the cleaning failure (toner slippage) continues in the non-paper-passing area of ​​the intermediate transfer belt 8. The period during which the cleaning failure continues tends to be longer when the amount of toner input to the cleaning blade 10 is greater than or equal to the lifespan, but less than the lifespan, compared to when the cumulative number of printed pages is greater than or equal to the lifespan minus P pages and less than the lifespan. Furthermore, the period during which cleaning failures persist tends to be longer when the amount of toner input to the cleaning blade 10 is greater ("lifetime + p pages") than when the number of pages is greater than the lifetime but less than the lifetime + p pages.

[0088] Therefore, in this embodiment, the distance from the scraping pattern formation position to the position where the adjustment pattern is formed is increased in response to the change in the scraping pattern due to the decrease in the solid lubricant 3b.

[0089] Figure 14 illustrates the distance from the scraping pattern after changing the timing of the adjustment pattern formation. The horizontal axis of Figure 14 shows the travel distance of the photoreceptor 1 or the cumulative number of printed sheets in the imaging unit, which is used to estimate the lifespan of the solid lubricant 3b, and the vertical axis shows the distance from the scraping pattern after changing the timing of the adjustment pattern formation. In Figure 14, B is the circumference of the intermediate transfer belt 8, and L1 is twice the circumference of the intermediate transfer belt 8 (L1 = 2B).

[0090] If the cumulative number of printed pages for any of the multiple image-forming units is less than "lifetime - P pages", the scraping pattern is a strip-shaped pattern, and the amount of toner input to the non-paper-feeding area of ​​the cleaning blade 10 is not large. In this case, as explained using Figure 8, the cleaning defect is minor, and the area on the intermediate transfer belt where the cleaning defect occurs is between the scraping pattern formation (primary transfer) position and 1 to 2 turns of the intermediate transfer belt 8, with the primary transfer nip as the starting point. Therefore, if the number of printed pages is less than "lifetime - P pages", as explained using Figure 8, when the adjustment pattern is formed (primary transferred to the intermediate transfer belt 8) between 1 to 2 turns of the intermediate transfer belt 8, the timing of the adjustment pattern formation is changed so that the adjustment pattern is formed (primary transferred) at a position at least L1 (twice the circumference of the intermediate transfer belt 8: 2 turns of the intermediate transfer belt) away from the scraping pattern.

[0091] If the cumulative number of printed pages from any of the multiple image-forming units is greater than or equal to "lifetime - P pages" but less than the lifetime, the scraping pattern is changed to a combination of a strip pattern and an edge pattern. As a result, the amount of toner input to the non-paper-feeding area of ​​the cleaning blade 10 increases. Therefore, cleaning defects in the non-paper-feeding area may worsen compared to when the number of printed pages is less than "lifetime - P pages". In this case, the area on the intermediate transfer belt where cleaning defects occur is between the scraping pattern formation position and the 1st to 3rd turns of the intermediate transfer belt 8, with the primary transfer nip as the starting point. Therefore, when the number of printed pages is greater than or equal to "lifetime - P pages" and equal to the lifetime, if the adjustment pattern is formed between the 1st to 3rd turns of the intermediate transfer belt 8, the timing of the adjustment pattern formation is changed so that the adjustment pattern is formed at a distance of L1 (twice the circumference of the intermediate transfer belt 8: 2 turns of the intermediate transfer belt) + B (1 turn of the intermediate transfer belt) or more from the scraping pattern.

[0092] If the cumulative number of printed pages from any of the multiple image-forming units is greater than or equal to the "lifetime" but less than "lifetime + P pages", the scraping pattern is changed so that the amount of toner input to the non-paper-feeding area of ​​the cleaning blade 10 increases beyond the lifetime. As a result, cleaning defects in the non-paper-feeding area may worsen compared to when the number of printed pages is less than the "lifetime". In this case, the area on the intermediate transfer belt where cleaning defects occur is between the scraping pattern formation position and the 1st to 4th turns of the intermediate transfer belt 8, with the primary transfer nip as the starting point. Therefore, if the number of printed pages is greater than or equal to the "lifetime" but less than "lifetime + p pages", and the adjustment pattern is formed between the 1st to 4th turns of the intermediate transfer belt 8, the timing of the adjustment pattern formation is changed so that the adjustment pattern is formed at a position at least L1+2B (4 turns of the intermediate transfer belt) away from the scraping pattern.

[0093] If the cumulative number of printed pages from any of the multiple image-forming units is equal to or greater than "lifetime + P pages", the scraping pattern is modified so that the amount of toner input to the non-paper-feeding area of ​​the cleaning blade 10 increases compared to when it is less than "lifetime + P pages". Therefore, cleaning defects in the non-paper-feeding area may worsen compared to when it is less than "lifetime + p pages". In this case, the area on the intermediate transfer belt where cleaning defects occur is between the scraping pattern formation position and the 1st to 5th turns of the intermediate transfer belt 8, with the primary transfer nip as the starting point. Accordingly, in the case of "lifetime + p pages", when the adjustment pattern is formed between the 1st to 5th turns of the intermediate transfer belt 8, the timing of the adjustment pattern formation is changed so that the adjustment pattern is formed at a position at least L1+3B (5th turn of the intermediate transfer belt 8) away from the scraping pattern.

[0094] L1, B, and P are values ​​that have been experimentally confirmed in advance to prevent peeling of the tip of the cleaning blade 10 and to be unaffected by adjustment operations, even when the machine is used or environmental conditions such as temperature and humidity vary.

[0095] In this embodiment, B is set to the circumference of the intermediate transfer belt 8, and the distance from the scraping pattern of the adjustment pattern as the depletion of the solid lubricant 3b progresses is set to (L1+B, L1+B2, L+3B), so as to be twice the circumference of the belt. As explained using Figure 8, cleaning failures are resolved when the toner that has slipped through the cleaning blade 10 travels one rotation of the intermediate transfer belt and is input to the cleaning blade 10. Therefore, by setting the circumference of the intermediate transfer belt 8 to twice the circumference, the adjustment pattern can be formed on the intermediate transfer belt 8, where the toner that has slipped through the cleaning blade 10 has been removed and the cleaning failure has been reliably resolved.

[0096] Note that while L1 is set to twice the circumference of the intermediate transfer belt 8 and B to the circumference of the intermediate transfer belt 8, these are merely examples, and the settings should be adjusted as appropriate depending on the configuration of the device. For example, if the circumference of the intermediate transfer belt 8 is long, the area where minor cleaning defects occur may be significantly shorter than one rotation of the intermediate transfer belt 8. In such cases, L1 may be made shorter than twice the circumference of the intermediate transfer belt 8.

[0097] Figure 15 is a flowchart illustrating the timing change for forming the adjustment pattern in this embodiment. When the control unit 60 reaches the timing for forming the adjustment pattern (Yes in S11), it sets a specified range (S12) to determine whether or not to change the timing of the adjustment pattern formation based on the scraping pattern. This specified range is the area where cleaning defects occur on the intermediate transfer belt 8, as described above. If the cumulative number of printed sheets from all image units is less than "lifetime - P sheets", the specified range is a distance from the scraping pattern formation position that exceeds one rotation of the intermediate transfer belt but is 2 rotations or less. If the cumulative number of printed sheets from any of the multiple image units is greater than or equal to "lifetime - P sheets" but less than the lifetime, the specified range is a distance from the scraping pattern formation position that exceeds one rotation of the intermediate transfer belt but is 3 rotations or less. If the cumulative number of printed sheets from any of the multiple image units is greater than or equal to the lifetime and less than lifetime + P sheets, the specified range is a distance from the scraping pattern formation position that exceeds one rotation of the intermediate transfer belt but is 4 rotations or less. Furthermore, if the cumulative number of printed sheets from any of the multiple image-forming units exceeds "lifespan + P sheets," the specified range will be the distance from the scraping pattern formation position that exceeds one rotation of the intermediate transfer belt but does not exceed five rotations.

[0098] Next, if the formation position of the adjustment pattern on the intermediate transfer belt 8 (primary transfer position) falls within the set specified range (Yes in S13), the control unit 60 changes the image formation timing of the adjustment pattern so that the adjustment pattern is formed outside the set specified range (S14). On the other hand, if the formation position of the adjustment pattern on the intermediate transfer belt 8 (primary transfer position) falls outside the set specified range (No in S13), the control unit 60 forms the adjustment pattern without changing the image formation timing of the adjustment pattern (S25).

[0099] Figure 16 shows an example of the formation of the adjustment pattern in this embodiment. The example shown in Figure 16 is the case where the cumulative number of printed sheets from any of the multiple image-forming units is greater than or equal to the "lifetime" and less than "lifetime + P sheets". The specified range is the range where the distance from the scraping pattern formation position (primary transfer position) exceeds one rotation of the intermediate transfer belt but is less than or equal to three rotations. In the example shown in Figure 16, the adjustment pattern RP is formed (primary transfer) at a position less than one rotation of the intermediate transfer belt 8 from the position of the scraping pattern KP. Therefore, in the configuration shown in Figure 16, the adjustment pattern is formed as is without changing (extending) the image formation timing.

[0100] Figure 17 shows another example of the formation of the adjustment pattern in this embodiment. In the example shown in Figure 17, the cumulative number of printed sheets from any of the multiple image-forming units is greater than or equal to the "lifetime number of sheets" and less than "lifetime number of sheets + P sheets". The specified range is the distance from the scraping pattern formation position that exceeds one rotation of the intermediate transfer belt but is less than or equal to three rotations. In the example shown in Figure 17, the adjustment pattern RP is formed in a specified range where cleaning defects occur from the position of the scraping pattern KP to the 1st to 3rd rotations of the intermediate transfer belt. Therefore, for this adjustment pattern, the timing of pattern formation is changed so that the distance from the scraping pattern KP is 3 rotations or more.

[0101] Figure 18 shows yet another example of the formation of the adjustment pattern in this embodiment. In the example shown in Figure 18, the cumulative number of printed sheets from any of the multiple image-forming units is greater than or equal to the "lifetime" and less than "lifetime + P sheets". The specified range is the distance from the scraping pattern formation position that exceeds one rotation of the intermediate transfer belt but is less than or equal to three rotations. In the example shown in Figure 18, the adjustment pattern RP is formed at a position at least three turns away from the scraping pattern KP on the intermediate transfer belt. Therefore, for this adjustment pattern, the distance from the scraping pattern KP is such that the adjustment pattern is formed (primary transfer) on the intermediate transfer belt 8 after the cleaning defects on the intermediate transfer belt 8 have been resolved. Thus, the adjustment pattern is formed as is without changing (extending) the image formation timing.

[0102] In this embodiment, the specified range for determining whether or not to change the timing of adjustment pattern formation is changed based on the amount of toner input to the cleaning blade 10 within a predetermined period determined by the scraping pattern. When the adjustment pattern is formed within the specified range, the timing of the adjustment pattern is changed so that the formation position (primary transfer position) of the adjustment pattern on the intermediate transfer belt 8 is outside the specified range. This prevents the formation (primary transfer) of the adjustment pattern RP in areas on the intermediate transfer belt where cleaning defects occur, and allows the optical sensors 40F and 40R to accurately detect the amount of adjustment pattern RP adhering to the surface.

[0103] As described above, when the adjustment pattern is formed (primary transfer) in the cleaning defect occurrence area (specified range), the image formation timing of the adjustment pattern is changed (extended) so that the adjustment pattern is formed outside the cleaning defect occurrence area. However, when the adjustment pattern is formed (primary transfer) in the cleaning defect occurrence area (specified range), the formation of the adjustment pattern may be stopped.

[0104] Figure 19 is a flowchart of an example in which the formation of the adjustment pattern is discontinued. As shown in Figure 19, when it is time to form the adjustment pattern (Yes in S21), a specified range is set to determine whether or not to stop forming the adjustment pattern based on the scraping pattern (the amount of toner input to the cleaning blade 10 within a predetermined period due to the scraping pattern) (S22).

[0105] This specified range is the same as described above, and is the area where cleaning defects occur on the intermediate transfer belt 8. If the cumulative number of printed sheets for all image units is less than "lifetime - P sheets", the specified range is the distance from the scraping pattern formation position that exceeds one rotation of the intermediate transfer belt but does not exceed two rotations. If the cumulative number of printed sheets for any of the multiple image units is greater than or equal to "lifetime - P sheets" but less than the lifetime, the specified range is the distance from the scraping pattern formation position that exceeds one rotation of the intermediate transfer belt but does not exceed three rotations. If the cumulative number of printed sheets for any of the multiple image units is greater than or equal to the lifetime and less than lifetime + P sheets, the specified range is the distance from the scraping pattern formation position that exceeds one rotation of the intermediate transfer belt but does not exceed four rotations. Furthermore, if the cumulative number of printed sheets for any of the multiple image units is greater than or equal to "lifetime + P sheets", the specified range is the distance from the scraping pattern formation position that exceeds one rotation of the intermediate transfer belt but does not exceed five rotations.

[0106] Next, the control unit 60 stops forming (image-making) the adjustment pattern if the formation position (primary transfer position) of the adjustment pattern on the intermediate transfer belt 8 falls within the set specified range (Yes in S23) (S24). On the other hand, if the formation position of the adjustment pattern on the intermediate transfer belt 8 falls outside the set specified range (No in S23), the control unit 60 forms (image-making) the adjustment pattern (S25).

[0107] Figure 20 shows an example of the formation of an adjustment pattern in an embodiment where the formation (image creation) of the adjustment pattern is discontinued. The example shown in Figure 20 is when the cumulative number of printed sheets from any of the multiple image-forming units is greater than or equal to the "lifetime number of sheets" and less than the "lifetime number of sheets + P sheets". The specified range is the distance from the scraping pattern formation position that exceeds one rotation of the intermediate transfer belt but is less than or equal to three rotations. As shown in Figure 20, the formation position of the adjustment pattern RP1 is such that the distance from the scraping pattern KP1 is less than one rotation of the intermediate transfer belt 8, and it is formed (primary transfer) outside the specified range (cleaning defect occurrence area) of the intermediate transfer belt 8. Therefore, the adjustment pattern RP1 is imaged.

[0108] On the other hand, the formation position of the adjustment pattern RP2 is within a specified range of more than one turn of the intermediate transfer belt but no more than three turns, from the position of the scraping pattern KP1. Therefore, the control unit 60 stops forming the adjustment pattern RP2, and the adjustment pattern RP2 is not formed in the area of ​​the intermediate transfer belt 8 where cleaning defects occur.

[0109] Even with this control system, no adjustment pattern is formed in areas where cleaning defects occur. Therefore, it is possible to prevent positional misalignment control defects due to false detection of adjustment patterns, and image density adjustment defects due to a decrease in the accuracy of detecting the amount of adjustment pattern adhesion.

[0110] Furthermore, when the cumulative number of printed sheets from multiple image-forming units exceeds "lifetime - P sheets", the amount of edge pattern adhesion may be increased compared to when the cumulative number of printed sheets from one of the multiple image-forming units exceeds "lifetime - P sheets".

[0111] Furthermore, as shown in Figure 21, the color used to form the scratch pattern may be changed. For example, when the cumulative value of the required toner input exceeds a threshold and it is time to form the scratch pattern, the color with the lowest toner consumption among Y, C, M, and K is used as the scratch pattern formation color. The toner consumption of each color can be determined, for example, from the image area ratio of each color. In the example shown in Figure 21, at the timing of scratch pattern KP1 formation, the consumption of K color toner was the lowest among Y, C, M, and K, so scratch pattern KP1 is formed using K color toner. At the timing of scratch pattern KP2 formation, the consumption of Y color toner was the lowest among Y, C, M, and K, so scratch pattern KP2 is formed using Y color toner. This makes it possible to suppress the bias of toner consumption towards a specific color compared to the case where only one of Y, C, M, or K is used to form the scratch pattern.

[0112] Figure 22 shows an example where the scraping pattern KP is made up of multiple strip-like patterns formed at short intervals. In the configuration shown in Figure 22, three strip-shaped patterns are formed with toners of different colors. This helps to suppress the uneven consumption of toner in a particular color. Also, in Figure 22, the downstream strip-shaped pattern on the intermediate transfer belt 8 is M color, the middle strip-shaped pattern is C color, and the upstream strip-shaped pattern is Y color, following the arrangement of the image-forming units 6 shown in Figure 1. By making the order of the colors of the strip-shaped patterns follow the arrangement of the image-forming units 6 in this way, the image-forming time for the three strip-shaped patterns can be shortened. Alternatively, the three strip-shaped patterns may be formed on the intermediate transfer belt 8 in the order of K, M, and C colors. Even with this configuration, for example, by using the order K, C, and Y colors, the image-forming time for the three strip-shaped patterns can be shortened compared to skipping the M color. Note that the image-forming time is the time from when one of the three image-forming units starts the series of image-forming processes described above until when the last of the three image-forming units finishes the series of image-forming processes described above.

[0113] The above interval Sp is set so that the next strip pattern is input before the toner forming the preceding strip pattern is completely removed from the cleaning area. Furthermore, the above interval Sp is set so that the amount of toner remaining in the cleaning area is less than or equal to the amount of toner that would cause a cleaning failure. This suppresses cleaning failures and effectively suppresses filming.

[0114] The verification experiments conducted by the inventors are described below. As shown in Figures 23 and 24, verification experiments were conducted under conditions (1) to (6) where the length of the strip-shaped pattern in the surface movement direction and the number of strip-shaped patterns differed from each other.

[0115] Condition (1) is a condition in which one strip-shaped pattern with a length of 32.5 mm in the direction of movement is formed, and condition (2) is a condition in which one strip-shaped pattern with a length of 97.5 mm in the direction of movement is formed. Condition (3) is a condition in which three strip-shaped patterns with a length of 32.5 mm in the direction of movement are formed at intervals of 13 mm, and condition (4) is a condition in which one strip-shaped pattern with a length of 80 mm in the direction of movement is formed. Condition (5) is a condition in which one strip-shaped pattern with a length of 200 mm in the direction of movement is formed. Condition (6) is a condition in which three strip-shaped patterns with lengths of 70 mm, 60 mm, and 70 mm in the direction of movement are formed at intervals of 80 mm. Then, for each of conditions (1) to (6), the cleaning performance and filming performance were evaluated.

[0116] <Evaluation of cleaning ability> The cleaning performance was evaluated under the following conditions. • Cleaning blade contact pressure: 20 N / m • Line speed of the intermediate transfer belt: 300 mm / s Furthermore, the cleaning performance was evaluated based on images printed after the formation of the strip-shaped pattern. If no streaky abnormalities were observed in the printed image, the cleaning performance was evaluated as "○" (good). If streaky abnormalities were observed in the printed image, the cleaning performance was evaluated as "×" (bad).

[0117] <Evaluation of filming capabilities> The filming performance was evaluated by printing 150,000 running charts with an image area ratio of 5%, and then forming a test pattern on the intermediate transfer belt. If no errors occurred when detecting the amount of test pattern adhesion using optical sensors 40R, 40C, and 40F, the filming performance was evaluated as "○". On the other hand, if errors occurred when detecting the amount of test pattern adhesion using optical sensors 40R, 40C, and 40F, the filming performance was evaluated as "×". The amount of toner input was calculated based on the travel distance of the intermediate transfer belt 8, and when the accumulated value of the toner input exceeded a threshold, a strip-shaped pattern was formed.

[0118] The results of the verification experiment are shown in Table 1 below. [Table 1]

[0119] As shown in Table 1, under conditions (1) and (4), the cleaning performance was rated "○", but the filming performance was rated "×". This is likely because, in the strip-shaped patterns of conditions (1) and (4), the amount of toner input to the cleaning area at one time is small, so toner leakage does not occur, resulting in a "○" rating for cleaning performance. On the other hand, under conditions (1) and (4), the filming performance was rated "×".

[0120] As described above, in this embodiment, the amount of toner in the formed strip-shaped pattern (amount of toner input to the cleaning blade 10) is subtracted from the cumulative value of the toner input amount, and when the cumulative value of the toner input amount exceeds a threshold, the strip-shaped pattern is formed. In condition (1), the amount of toner input to the cleaning blade 10 is small, so the subtraction value is small, and the frequency of the strip-shaped pattern formation operation is higher compared to the other conditions (2) to (6). However, because the amount of toner input to the cleaning blade 10 in a single strip-shaped pattern formation operation is small, the scraping of film in a single strip-shaped pattern formation operation is insufficient. As a result, even if the frequency of the strip-shaped pattern formation operation is high, the film on the intermediate transfer belt 8 cannot be removed well, and the film on the intermediate transfer belt 8 deteriorates over time, which is thought to be why the film evaluation was "×".

[0121] As shown in Table 1, in conditions (2) and (5), where a single strip-shaped pattern with a length of 97.5 mm or more in the direction of movement was formed, the cleaning performance was rated as "×". This is thought to be because a large amount of toner was input to the cleaning area at once, and the tip of the cleaning blade 10 could not withstand the pressure of the toner input to the cleaning area, causing the toner to slip through and resulting in streaky abnormal images.

[0122] On the other hand, under conditions (2) and (5), the filming evaluation was "○". Because a large amount of toner is input to the cleaning blade 10, the toner can remain in the cleaning area for a long time. As a result, the filming can be removed by the toner that remains in the cleaning area for a relatively long period of time. Therefore, it is thought that the filming on the intermediate transfer belt 8 was removed more effectively compared to the case where the filming is removed by toner that remains in the cleaning area intermittently, as in condition (1). As a result, it is thought that the filming on the intermediate transfer belt 8 was suppressed over time, and the filming evaluation was "○".

[0123] From conditions (1), (2), (4), and (5), it was found that cleaning defects can be suppressed by setting the length of the strip-shaped pattern in the direction of movement to at least 80 mm or less. Furthermore, it was found that filming of the intermediate transfer belt 8 can be suppressed over time by setting the length of the strip-shaped pattern in the direction of movement to at least 97.5 mm or more.

[0124] As shown in Table 1, under conditions (3) and (6), both cleaning performance and filming performance were rated "○". This is because the length of each strip-shaped pattern in the direction of movement is 80 mm or less. Therefore, it is considered that the amount of toner input to the cleaning area at one time could be kept below the amount of toner that would cause cleaning failure, and the cleaning blade 10 was able to effectively block the toner at the cleaning area.

[0125] Furthermore, in conditions (3) and (6), three strip-shaped patterns are formed at predetermined intervals, and the next strip-shaped pattern is input to the cleaning area before the toner in the cleaning area is completely removed by the cleaning blade 10. This ensures that the scraping of toner filming in the cleaning area continues. Also, in condition (3), the total length of movement of the three strip-shaped patterns is 97.5 mm, the same as in condition (2). As a result, the same amount of toner as in condition (2) is input to the cleaning area. Therefore, it is thought that the filming on the intermediate transfer belt 8 can be removed by the toner that remains in the cleaning area for a sufficiently long time, similar to condition (2), and the filming evaluation was "○".

[0126] Furthermore, in condition (6), the length of each strip pattern in the direction of movement is longer than in condition (3). Therefore, the amount of toner input to the cleaning area at one time is greater than in condition (3). Thus, even if the interval between strip patterns is longer than in condition (3), the next strip pattern can be input to the cleaning area before the toner at the cleaning area is completely removed by the cleaning blade 10. For this reason, in condition (6) as well, the filming on the intermediate transfer belt 8 can be removed by the toner that remains at the cleaning area for a sufficiently long time, and it is thought that the filming evaluation was "○".

[0127] On the other hand, in condition (6), if the spacing between the strip patterns is set to 13 mm, the same as in condition (3), too much toner may accumulate in the cleaning area, potentially causing cleaning failures. Therefore, it is necessary to set the spacing between the strip patterns according to the length of each strip pattern in the direction of movement (the amount of toner in each strip pattern).

[0128] In condition (3), the distance from the first to the last stripe pattern is shorter than in condition (6), resulting in a shorter duration for the stripe pattern formation operation and thus reducing the downtime of the device. On the other hand, in condition (6), a larger total amount of toner is input to the cleaning area in a single stripe pattern formation operation than in condition (3), and the toner remains at the cleaning area for a longer time. Therefore, condition (6) has a higher film removal effect than condition (3).

[0129] Furthermore, when the BN index was measured for conditions (2) and (3), the BN index was approximately 0.2, and for condition (1), it was 0.45. The BN index is an index value indicating the amount of boron nitride, a component of the lubricant, deposited on the intermediate transfer belt 8. The BN index value can be determined using the ATR (Attenuated Total Reflection) infrared absorption spectrum. Specifically, the difference spectrum is taken between the ATR infrared absorption spectrum of the intermediate transfer belt 8 before the verification experiment and the ATR infrared absorption spectrum of the intermediate transfer belt 8 after the verification experiment. The ratio of the peak area derived from boron nitride to the peak area derived from the intermediate transfer belt in this difference spectrum is used as the BN index.

[0130] Figure 25 shows an example where the scraping pattern KP is made into multiple strip-like patterns with short intervals between them. Continuous printing begins after a scraping pattern KP1 is formed, consisting of three strip-shaped patterns KP1(M), KP1(C), and KP1(Y) in M, C, and Y colors. This suppresses cleaning defects and effectively removes filming from the surface of the intermediate transfer belt, allowing continuous printing to begin. Therefore, during continuous printing, streaky abnormal images due to cleaning defects and white spots due to filming are suppressed, resulting in high-quality images. Furthermore, the color order of the three strip-shaped patterns follows the arrangement order from the downstream side in the surface movement direction of the intermediate transfer belt 8 of the imaging unit 6 shown in Figure 1. Therefore, the imaging time for the three strip-shaped patterns can be shortened, and delays in the start of continuous printing can be suppressed. In addition, by forming the three strip-shaped patterns with different colors, it is possible to suppress the uneven consumption of toner in a specific color.

[0131] Furthermore, for scraping pattern KP2, where the scraping pattern is a combination of a strip pattern and an edge pattern, if the cumulative number of printed pages for any one of the multiple image-forming sections is greater than or equal to "lifetime - p pages", the multiple toner patches of the strip pattern KP2-1(K) and the edge pattern KP2-2 can be formed with different colors, M and C, to suppress the concentration of toner on a specific color.

[0132] Although preferred embodiments of the present invention have been described above, the present invention is not limited to these specific embodiments, and various modifications and changes are possible within the scope of the spirit of the present invention as described in the claims, unless otherwise specifically limited in the above description.

[0133] The above is just one example; each of the following embodiments produces its own unique effects. (Aspect 1) The image forming apparatus comprises: an image forming means such as an image forming unit 6 that forms a toner image by attaching toner to a latent image carried by a latent image carrier such as a photoreceptor 1; an image carrier such as an intermediate transfer belt 8 that carries the toner image formed by the image forming means; a transfer member such as a secondary transfer roller 70 that transfers the toner image on the image carrier to a recording medium such as paper; a cleaning member such as a cleaning blade 10 that cleans the surface of the image carrier; and adhesion amount detection means such as optical sensors 40R, 40F that detect the amount of toner attached to an adjustment pattern for adjusting the image forming means, which is positioned opposite the surface of the image carrier and is formed outside the recording medium paper feeding area of ​​the image carrier in the width direction of the recording medium such as the main scanning direction, wherein the image forming means forms a toner image pattern such as a scraping pattern KP on the image carrier that is input to the cleaning member without being transferred to the recording medium. In 100, the image forming means includes a lubricant application means such as a lubricant supply unit 3 for applying lubricant to the surface of the latent image carrier, a pattern changing means such as a control unit 60 that changes the toner image pattern or the frequency of toner image pattern formation so that the amount of toner input to the part of the cleaning member that contacts the non-paper-feeding area of ​​the image carrier during a predetermined period increases according to the remaining amount of lubricant in the lubricant application means, and a timing adjustment means such as a control unit 60 that adjusts the timing of the formation of the adjustment pattern so that it falls outside the specified range if the surface movement distance of the image carrier from the position of the toner image pattern formed on the image carrier to the formation position of the adjustment pattern formed after the toner image pattern is formed on the image carrier falls outside the specified range, and the timing adjustment means changes the specified range based on the changes made by the pattern changing means. When the lubricant, such as the solid lubricant 3b, in the lubricant application means such as the lubricant supply unit 3 is depleted, the amount of lubricant adhering to the image carrier, such as the intermediate transfer belt 8, decreases, and the coefficient of dynamic friction between the surface of the image carrier and the cleaning member, such as the cleaning blade 10, increases. Furthermore, the depletion of the lubricant also reduces the amount of background toner adhering to the image carrier from the image-forming means that is continuously input to the cleaning member. Transfer residue toner is input to the central side of the cleaning member in the width direction that contacts the recording medium feeding area of ​​the image carrier. Because the input transfer residue toner improves the sliding between the image carrier and the cleaning member, there is almost no increase in frictional force due to the decrease in the amount of lubricant adhering to the image carrier on the central side of the cleaning member in the width direction. On the other hand, on the end side of the cleaning member in the width direction that contacts the non-feeding area of ​​the image carrier where almost no transfer residue toner is input, the frictional force increases due to the decrease in the amount of lubricant adhering to the image carrier and the decrease in background toner, which may cause peeling at the tip and abnormal wear at the tip of the cleaning member. Therefore, in Embodiment 1, in response to the decrease in lubricant, the pattern changing means changes the toner image pattern or the frequency of toner image pattern formation so that the amount of toner input to the portion of the cleaning member that contacts the non-paper-feeding area of ​​the image carrier (the widthwise end side of the cleaning member) during a predetermined period increases. By increasing the amount of toner input to the widthwise end side of the cleaning member during a predetermined period, the shortage of background dirt toner can be compensated for. As a result, slippage between the image carrier and the cleaning member can be maintained at the end side of the cleaning member, and peeling at the end side of the cleaning member can be suppressed. However, as explained using Figure 11, the contact force of the lubricant on the coating member, such as the coating brush that applies the lubricant to the latent image carrier, may differ in the width direction, resulting in the lubricant not being consumed uniformly in the width direction, and one side in the width direction may be depleted faster than the other. In this case, the amount of lubricant and background toner decreases in one of the non-paper-feeding areas on both sides of the image carrier in the width direction, but there is no decrease in the amount of lubricant or background toner on the other side. It is not possible to know which side in the width direction will deplete the lubricant faster. Therefore, when the amount of lubricant adhering to the image carrier decreases, the toner image pattern is changed on both sides of the cleaning member to increase the amount of toner input. As a result, since there is no decrease in background toner on the side where the lubricant is not depleted, the amount of toner input becomes excessive, and there is a risk that the cleaning failure will worsen compared to before the toner image pattern was changed by the pattern changing means. Before the toner image pattern was changed, minor cleaning defects may occur under conditions where cleaning defects are likely to occur. Such minor cleaning defects can be resolved, for example, by the image carrier completing one rotation and passing through the cleaning member again. On the other hand, after the toner image pattern was changed, cleaning defects in the non-paper-passing areas of the image carrier will not be resolved unless the image carrier passes through the cleaning member multiple times. If an adjustment pattern is formed in the area in the direction of surface movement on the image carrier where cleaning defects are occurring, the accuracy of the adhesion amount detection by the adhesion amount detection means may decrease due to the toner with cleaning defects. Therefore, in embodiment 1, when the surface displacement distance of the image carrier from the position of the toner image pattern formed on the image carrier by the timing adjustment means to the position of the adjustment pattern RP to be formed on the image carrier falls within a specified range, the formation timing of the adjustment pattern PR is adjusted so that the adjustment pattern is formed outside the specified range. Furthermore, the timing adjustment means changes the specified range based on the toner image pattern changed by the pattern changing means. By defining the above-mentioned specified range as the region where cleaning defects occur in the image carrier, the adjustment pattern will not be formed in the region where cleaning defects occur, and the influence of the toner with cleaning defects on the amount of adhesion of the adjustment pattern when detecting the amount of adhesion can be effectively suppressed. As a result, the amount of adhesion of the adjustment pattern can be detected with high accuracy by the adhesion amount detection means. Furthermore, by changing the specified range based on the changed toner image pattern, even if the cleaning defect worsens and the area where cleaning defects occur becomes longer due to the change in the toner image pattern, the adjustment pattern can be formed outside the area where cleaning defects occur, compared to not changing the specified range based on the changed toner image pattern.

[0134] (Aspect 2) The system comprises an image forming means, such as an image forming unit 6, which forms a toner image by attaching toner to a latent image carried by a latent image carrier such as a photoreceptor 1; an image carrier such as an intermediate transfer belt 8 that carries the toner image formed by the image forming means; a transfer member such as a secondary transfer roller 70 that transfers the toner image on the image carrier to a recording medium such as paper; a cleaning member such as a cleaning blade 10 that cleans the surface of the image carrier; and adhesion amount detection means such as optical sensors 40R, 40F that are positioned opposite the surface of the image carrier and are formed outside the recording medium paper feeding area of ​​the image carrier in the width direction of the recording medium such as the main scanning direction, for detecting the amount of toner attached to an adjustment pattern for adjusting the image forming means, wherein the image forming means forms a toner image pattern such as a scraping pattern KP on the image carrier that is input to the cleaning member without being transferred to the recording medium. In the image forming apparatus 100, the image forming means includes a lubricant application means such as a lubricant supply unit 3 for applying lubricant to the surface of a latent image carrier, a pattern changing means such as a control unit 60 that changes the toner image pattern or the frequency of toner image pattern formation so that the amount of toner input to the part of the cleaning member that contacts the non-paper-feeding area of ​​the image carrier during a predetermined period increases according to the remaining amount of lubricant in the lubricant application means, and an adjustment pattern cancellation means such as a control unit 60 that cancels the formation of the adjustment pattern if the surface movement distance of the image carrier from the position of the toner image pattern formed on the image carrier to the formation position of the adjustment pattern formed after the toner image pattern formation falls within a specified range, and the adjustment pattern cancellation means changes the specified range based on the changes made by the pattern changing means. According to this, similar to embodiment 1, the pattern changing means such as the control unit 60 changes the toner image pattern or the frequency of toner image pattern formation so that the amount of toner input to the part of the cleaning member that comes into contact with the non-paper-feeding area of ​​the image carrier (the widthwise end side of the cleaning member) increases in response to the decrease in lubricant, thereby suppressing the curling of the leading edge on the widthwise end side of the cleaning member. Furthermore, in Embodiment 2, by stopping the adjustment pattern when it enters the specified range, the formation of the adjustment pattern in the area where cleaning defects occur on the image carrier can be suppressed. Therefore, in Embodiment 2 as well, when detecting the amount of adjustment pattern adhesion with the adhesion amount detection means, the influence of toner with cleaning defects can be effectively suppressed. As a result, the adhesion amount detection means can accurately detect the amount of adjustment pattern adhesion. In addition, by changing the specified range based on the changed toner image pattern, compared to not changing the specified range based on the changed toner image pattern, even if cleaning defects worsen and the area where cleaning defects occur becomes longer due to the change in the toner image pattern, it is possible to prevent the formation of the adjustment pattern outside the area where cleaning defects occur.

[0135] (Aspect 3) In embodiment 1 or 2, the specified range is expanded based on a change in the toner image pattern, such as a scraping pattern, by a pattern changing means such as a control unit 60. According to this, as described in the embodiment, changing the toner image pattern, such as the scraping pattern, by the pattern changing means increases the amount of toner input to the area of ​​the cleaning member, such as the cleaning blade 10, that contacts the non-paper-feeding area of ​​the image carrier, such as the intermediate transfer belt 8, during a predetermined period. This worsens the cleaning defects in the non-paper-feeding area of ​​the image carrier, and the area where cleaning defects occur becomes wider than before the toner image pattern was changed. Therefore, by widening the above-specified range, it is possible to suppress the formation of adjustment patterns in the cleaning defect area of ​​the image carrier after the toner image pattern has been changed.

[0136] (Aspect 4) In embodiment 3, the amount of increase in the specified range based on the change of the toner image pattern, such as the scraping pattern, by the pattern changing means such as the control unit 60 is an integer multiple of the circumference of the image carrier such as the intermediate transfer belt 8. According to this, as described in the embodiment, cleaning defects are resolved when the toner that has slipped through the cleaning member, such as the cleaning blade 10, is re-entered into the cleaning member and removed by the image carrier, such as the intermediate transfer belt 8, after it has completed one rotation. Therefore, by setting the increase amount of the specified range to an integer multiple of the circumference of the image carrier, an adjustment pattern can be formed on the image carrier, where the toner that has slipped through the cleaning member has been removed and the cleaning defects have been reliably resolved.

[0137] (Appendix 5) In embodiment 3 or 4, the initial value of the specified range exceeds the circumference of the image carrier, such as the intermediate transfer belt 8, and is less than or equal to twice the circumference. According to this, as described in the embodiment, before the toner image pattern such as the scraping pattern is changed, there is a minor cleaning defect, and the region where such minor cleaning defects occur is from a position a distance from the toner image pattern formation position to a position twice the circumference of the image carrier. Therefore, by setting the initial value of the specified range to exceed the circumference of the image carrier such as the intermediate transfer belt 8, but not exceeding twice the circumference, it is possible to suppress the formation of the adjustment pattern in the cleaning defect region of the image carrier.

[0138] (Aspect 6) In any of embodiments 1 to 5, the remaining amount of lubricant is estimated based on the cumulative number of prints made by the image-making means such as the image-making unit 6, or the distance traveled by the latent image carrier such as the photoreceptor 1. According to this, the amount of lubrication in the lubricant application means, such as the lubricant supply unit 3, decreases as the image-forming means, such as the image-forming unit 6, is driven. Therefore, the remaining amount of lubricant can be estimated from the cumulative number of prints made by the image-forming means, such as the image-forming unit 6, or from the travel distance of the latent image carrier, such as the photoreceptor 1. Furthermore, compared to systems that directly detect the remaining amount of lubricant using sensors, the number of parts can be reduced, thereby lowering the cost of the device.

[0139] (Aspect 7) In any of embodiments 1 to 6, the device includes imaging means such as a plurality of imaging units 6 that each form toner images of different colors, and the color of the toner image pattern is changeable. According to this, as explained using Figure 21, the color of the toner image pattern cannot be changed, and compared to the case where only one of several colors is used to form a toner image pattern such as a scraping pattern, it is possible to suppress the bias in toner consumption towards a specific color.

[0140] (Pattern 8) In any of the embodiments 1 to 7, The device includes image-forming means such as multiple image-forming units 6, each forming toner images of different colors, and the toner image patterns, such as scraping patterns, are composed of toners of multiple colors. According to this, as described in the embodiment, it is possible to suppress the bias in toner consumption towards a specific color compared to the case where the toner image pattern is formed with one color.

[0141] (Aspect 9) In embodiment 8, multiple imaging means, such as imaging units 6, each forming toner images of different colors, are arranged in the direction of surface movement of an image carrier, such as an intermediate transfer belt 8. In a single toner image pattern formation operation, multiple toner image patterns, such as strip-shaped patterns of different colors, are formed at predetermined intervals, and the color order of the multiple toner image patterns from the downstream side in the surface movement direction follows the color order of the multiple imaging means from the downstream side in the surface movement direction. According to this, as described in the embodiment, the imaging time for creating toner image patterns such as multiple strip-shaped patterns can be shortened.

[0142] (Aspect 10) In embodiment 9, the color order of multiple toner image patterns, such as strip-shaped patterns, from the downstream side in the surface movement direction is set to a continuous color order from the downstream side in the surface movement direction of multiple image-forming means. According to this, as described in the embodiment, for example, the image-forming means are arranged in the order of K, M, C, Y colors from the downstream side in the direction of surface movement of the image carrier, and the color order of the multiple scraping patterns is K, C, Y colors, and not a continuous color order skipping the M color, which makes it possible to shorten the image-forming time for forming multiple scraping patterns. [Explanation of Symbols]

[0143] 1: Photoreceptor 3: Lubricant supply unit 3a: Lubricant supply roller 3b: Solid lubricant 3c: Compression spring 4: Charged part 5: Developing Department 6:Image creation section 7: Exposure area 8: Intermediate transfer belt 9: Primary transfer roller 10: Cleaning blade 15: Intermediate transfer belt device 20: Fixing section 26:Paper feed section 40: Optical sensor unit 40C: Optical sensor 40F: Optical sensor 40R: Optical sensor 60: Control Unit 63: Toner Refill Department 70: Secondary transfer roller 100: Image forming apparatus KP: Scraping Pattern P:Paper PR: Adjustment pattern [Prior art documents] [Patent Documents]

[0144] [Patent Document 1] Japanese Patent Publication No. 2023-43109

Claims

1. An imaging means for forming a toner image by attaching toner to the latent image carried by a latent image carrier, An image carrier that holds the toner image formed by the image-forming means, A transfer member for transferring the toner image on the image carrier to a recording medium, A cleaning member for cleaning the surface of the image carrier, The system includes a toner deposition amount detection means that is positioned opposite the surface of the image carrier and is formed in a non-paper-feeding area of ​​the image carrier that is outside the paper-feeding area of ​​the recording medium in the width direction of the recording medium, for adjusting the image-making means, The image forming means is an image forming apparatus that forms a toner image pattern on the image carrier without transferring it to the recording medium, and inputting the toner image pattern to the cleaning member. The image forming means includes a lubricant application means for applying a lubricant to the surface of the latent image carrier, A pattern changing means that changes the toner image pattern or the frequency of formation of the toner image pattern so as to increase the amount of toner input to the portion of the cleaning member that contacts the non-paper-feeding area of ​​the image carrier during a predetermined period, according to the remaining amount of lubricant in the lubricant application means, The system includes a timing adjustment means for adjusting the formation timing of the adjustment pattern so that if the surface displacement distance of the image carrier from the position of the toner image pattern formed on the image carrier to the formation position of the adjustment pattern formed after the toner image pattern is formed falls within a specified range, the timing adjustment means adjusts the formation timing of the adjustment pattern so that it falls outside the specified range. The image forming apparatus is characterized in that the timing adjustment means changes the specified range based on the change of the toner image pattern by the pattern changing means.

2. An imaging means for forming a toner image by attaching toner to the latent image carried by a latent image carrier, An image carrier that holds the toner image formed by the image-forming means, A transfer member for transferring the toner image on the image carrier to a recording medium, A cleaning member for cleaning the surface of the image carrier, The system includes a toner deposition amount detection means that is positioned opposite the surface of the image carrier and is formed in a non-paper-feeding area of ​​the image carrier that is outside the paper-feeding area of ​​the recording medium in the width direction of the recording medium, for adjusting the image-making means, The image forming means is an image forming apparatus that forms a toner image pattern on the image carrier without transferring it to the recording medium, and inputting the toner image pattern to the cleaning member. The image forming means includes a lubricant application means for applying a lubricant to the surface of the latent image carrier, A pattern changing means that changes the toner image pattern so as to increase the amount of toner input into the non-paper-feeding area of ​​the cleaning member, according to the remaining amount of lubricant in the lubricant application means, The system includes an adjustment pattern cancellation means for cancelling the formation of the adjustment pattern if the surface displacement distance of the image carrier from the position of the toner image pattern formed on the image carrier to the formation position of the adjustment pattern to be formed after the toner image pattern is formed on the image carrier falls within a specified range. The image forming apparatus is characterized in that the adjustment pattern cancellation means changes the specified range based on the change of the toner image pattern by the pattern changing means.

3. In the image forming apparatus according to claim 1 or 2, An image forming apparatus characterized by expanding the specified range based on the modification of the toner image pattern by the pattern changing means.

4. In the image forming apparatus according to claim 3, An image forming apparatus characterized in that the amount of increase in the specified range based on the change of the toner image pattern by the pattern changing means is an integer multiple of the circumference of the image carrier.

5. In the image forming apparatus according to claim 3, The image forming apparatus is characterized in that the initial value of the specified range exceeds the circumference of the image carrier and is less than or equal to twice the circumference.

6. In the image forming apparatus according to claim 1 or 2, An image forming apparatus characterized by estimating the remaining amount of lubricant based on the cumulative number of prints made by the image forming means or the distance traveled by the latent image carrier.

7. In the image forming apparatus according to claim 1 or 2, It comprises multiple image-forming means that each form a toner image of a different color, The image forming apparatus is characterized in that the color of the toner image pattern can be changed.

8. In the image forming apparatus according to claim 1 or 2, It comprises multiple image-forming means that each form a toner image of a different color, The image forming apparatus is characterized in that the toner image pattern is composed of multiple colors of toner.

9. In the image forming apparatus according to claim 8, Multiple imaging means, each forming a toner image of a different color, are arranged in the direction of surface movement of the image carrier. In a single toner pattern formation operation, multiple toner pattern designs of different colors are formed at predetermined intervals. An image forming apparatus characterized in that the color order of the multiple toner image patterns from the downstream side in the surface movement direction follows the color order of the multiple imaging means from the downstream side in the surface movement direction.

10. In the image forming apparatus according to claim 9, An image forming apparatus characterized in that the color order of a plurality of toner image patterns from the downstream side in the surface movement direction is a continuous color order from the downstream side in the surface movement direction of a plurality of image forming means.

Images