Image-forming device

Abstract

To provide an image-forming device capable of suppressing smudges on the back of a paper sheet.SOLUTION: An image-forming device includes: image-forming means for forming a toner image; an image carrier for carrying a toner image formed by the image-forming means; a transfer member for transferring a toner image on the image carrier to a recording medium; and a cleaning member for cleaning the surface of the image carrier. An adjustment pattern comprising multiple toner patches provided with an interval in an orthogonal direction orthogonal to a surface movement direction of the image carrier is formed in the image carrier, the adjustment pattern is detected by pattern detection means, and adjustment operation for adjusting the image-forming means is executed on the basis of a detection result of the pattern detection means. At the time of execution of the adjustment operation, the transfer member is separated from the image carrier, and multiple band-like patterns that are long in an orthogonal direction are formed with a predetermined interval when executing the adjustment operation.SELECTED DRAWING: Figure 4

Description

[Technical field]

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

[0002] Conventionally, there is known an image forming apparatus which includes an image creating means for creating a toner image, an image carrier for carrying the toner image created by the image creating 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, and which forms an adjustment pattern on the image carrier consisting of a plurality of toner patches spaced apart in a direction perpendicular to the direction of surface movement of the image carrier, detects the adjustment pattern with a pattern detection means, and performs an adjustment operation to adjust the image creating means based on the detection result of the pattern detection means.

[0003] Patent Document 1 describes an image forming apparatus in which a belt-like pattern that is long in a direction perpendicular to the surface movement direction of an intermediate transfer belt that removes filming from the intermediate transfer belt, which is an image carrier, is passed through a transfer nip by the movement of the intermediate transfer belt, and is finally input to a contact point between the image carrier and the cleaning member. Patent Document 1 describes that the belt-like pattern is formed before the formation of a toner image to be transferred to paper, between sheets of paper, etc., and describes that when the belt-like pattern passes through the transfer nip, a bias of the opposite polarity to the transfer bias used when transferring the toner image to paper is applied to the transfer nip to prevent the belt-like pattern from being transferred to a secondary transfer roller. Summary of the Invention [Problem to be solved by the invention]

[0004] However, there is a risk that it is not possible to simultaneously suppress poor cleaning and effectively remove filming from the image carrier, and there is also a risk of back staining, in which the back surface of the paper is stained. [Means for solving the problem]

[0005] In order to solve the above-mentioned problems, the present invention provides an image forming apparatus comprising an image creating means for creating a toner image, an image carrier for carrying the toner image created by the image creating 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, wherein an adjustment pattern consisting of a plurality of toner patches spaced apart in a direction perpendicular to a surface movement direction of the image carrier is formed on the image carrier, the adjustment pattern is detected by a pattern detection means, and an adjustment operation is performed to adjust the image creating means based on the detection result of the pattern detection means, wherein, when the adjustment operation is performed, the transfer member is separated from the image carrier, and when the adjustment operation is performed, a plurality of band-shaped patterns that are long in the perpendicular direction are formed at predetermined intervals in the surface movement direction. Effect of the Invention

[0006] According to the present invention, it is possible to suppress poor cleaning and effectively remove filming from an image carrier, and also to suppress back staining of paper. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic configuration diagram of a printer according to an embodiment of the present invention. [Diagram 2] 5A and 5B are schematic diagrams for explaining gradation patterns serving as adjustment patterns on an intermediate transfer belt. [Diagram 3] 11A and 11B are diagrams for explaining a cleaning failure when the amount of toner in the scraping pattern is large. [Figure 4] 6 is a schematic diagram showing a part of a gradation pattern and a scraping pattern formed on the intermediate transfer belt when process control is performed. FIG. [Diagram 5] 6A to 6C are diagrams for explaining a case where a scraping pattern according to the present embodiment is input to a cleaning location. [Figure 6] 11A to 11C are diagrams illustrating the scraping patterns under conditions (1) to (3) in the verification experiment. [Figure 7] 6A and 6B are diagrams for explaining changes in image density of the scraping pattern. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The best mode for carrying out the present invention will be described below with reference to the drawings. Note that a person skilled in the art can easily modify and alter the present invention within the scope of the claims to create other embodiments, and these modifications and alterations are included in the scope of the claims. The following description is an example of the best mode for carrying out the present invention, and does not limit the scope of the claims.

[0009] Hereinafter, an embodiment of an electrophotographic printer (hereinafter, referred to as printer 100) will be described as an image forming apparatus to which the present invention is applied. FIG. 1 is a schematic diagram of a printer 100 according to this embodiment. The printer 100 is a tandem type image forming device that forms full color images, and forms color images using toners of the colors yellow (Y), cyan (C), magenta (M), and black (Bk). It is mainly composed of an image forming unit 120, an intermediate transfer unit 160, and a paper feed unit 130. In the following description, the subscripts Y, C, M, and Bk indicate members for yellow, cyan, magenta, and black, respectively.

[0010] The printer 100 has a configuration in which a paper feed section 130 having two paper feed cassettes 131 for storing paper as recording media at its lower portion is provided, and an image creating section 120 and an intermediate transfer section 160 are disposed above the paper feed section 130.

[0011] The imaging section 120 is provided with imaging units 121Y, 121C, 121M, 121Bk as four imaging means each having a drum-shaped photoreceptor 10Y, 10C, 121M, 121Bk. These imaging units 121Y, 121C, 121M, 121Bk are arranged in line in the surface movement direction of the intermediate transfer belt 162 as an image carrier, and are each configured as a process cartridge and are each configured to be detachably attached to the printer 100 as a unit. Each of the imaging units 121Y, 121C, 121M, and 121Bk is provided with a charging device 11, a developing device 12, a photoconductor cleaning device 13, and a lubricant applying device .

[0012] The intermediate transfer section 160 includes an intermediate transfer belt 162 as an image carrier, which is a flexible endless belt wound around a plurality of tension rollers, primary transfer rollers 161Y, C, M, Bk, and a secondary transfer roller 166 as a transfer member. The intermediate transfer belt 162 is disposed above the image forming units 121Y, C, M, Bk, and the photoconductors 10Y, C, M, Bk of the image forming units are in contact with the intermediate transfer belt 162. The intermediate transfer belt 162 moves on its surface in synchronization with the movement of the photoconductors 10Y, C, M, Bk. The primary transfer rollers 161Y, C, M, Bk are disposed along the inner circumferential surface of the intermediate transfer belt 162, and the primary transfer rollers 161Y, C, M, Bk press the surface of the intermediate transfer belt 162 against the surface of the photoconductors 10Y, C, M, Bk.

[0013] The multiple tension rollers around which the intermediate transfer belt 162 is wound include a drive roller 163 on the left side of FIG. 1, an opposing roller 164 that faces the secondary transfer roller on the right side of the figure, a driven roller 165 at the top of the figure, and primary transfer rollers 161Y, C, M, and Bk. Further, a secondary transfer roller 166 serving as a secondary transfer device is disposed around the intermediate transfer belt 162 at a position facing the opposing roller 164 and facing the paper transport path 60. Meanwhile, a belt cleaning device 167 for cleaning the belt surface is disposed at a position facing the drive roller 163.

[0014] Toner bottles 159Y, 159C, 159M, 159Bk corresponding to the imaging units 121Y, 121C, 121M, 121Bk are arranged in a substantially horizontal direction above the intermediate transfer unit 160. Also, an exposure device 140 is arranged below the imaging units 121Y, 121C, 121Bk to irradiate the uniformly charged surfaces of the photoconductors 10Y, 10C, 121M, 121Bk with laser light to form electrostatic latent images.

[0015] The paper feed unit 130 is disposed below the exposure device 140. The paper feed unit 130 is provided with a paper feed cassette 131 that stores paper as a recording medium, and a paper feed roller 132. The paper feed unit 130 feeds paper at a predetermined timing toward a secondary transfer nip portion between the intermediate transfer belt 162 and a secondary transfer roller 166 via a pair of registration rollers 133. In addition, below the exposure device, a waste toner bottle 150 for storing waste toner removed by the photoconductor cleaning device 13 and the belt cleaning device 167 is also arranged.

[0016] A fixing device 30 that fixes the toner image to the paper is disposed downstream of the secondary transfer nip portion in the paper transport direction, and a paper discharge roller and a paper discharge storage section 135 that stores the discharged paper are disposed downstream of the fixing device 30 in the paper transport direction. Between the two paper feed cassettes 131 of the paper feed section 130 and the fixing device 30, a transport path 60 for transporting the paper is formed.

[0017] In this printer 100, the photoconductors 10Y, C, M, and Bk of the imaging units 121Y, C, M, and Bk are uniformly charged by the charging device 11 and exposed to a predetermined pattern by the exposure device 140 to form electrostatic latent images. Then, toner is supplied to the surface of each photoconductor 10Y, C, M, and Bk by the developing device 12, and the electrostatic latent images on the photoconductors are developed. The developed toner images on each photoconductor reach the primary transfer nip, which is the contact point with the intermediate transfer belt 162, and the toner images of each color are primarily transferred onto the intermediate transfer belt 162, superimposed in sequence.

[0018] Residual toner remaining on the surface of the photoconductor without being primarily transferred to the intermediate transfer belt 162 is removed by the photoconductor cleaning device 13. The residual toner removed by the photoconductor cleaning device 13 is transported as waste toner via a transport path to a waste toner bottle 150 for collection. Thereafter, a lubricant is applied to the surface of the photoconductor by a lubricant application device.

[0019] The color toner image on the intermediate transfer belt, onto which the toner images from each photoconductor are superimposed and primarily transferred, is transported to a secondary transfer nip formed by contact with a secondary transfer roller 166. In this secondary transfer nip, the color toner image on the intermediate transfer belt is secondarily transferred onto a sheet of paper that has been transported from one of the paper feed cassettes 131 via a pair of registration rollers 133.

[0020] A secondary transfer bias is applied to an opposing roller 164 that faces the secondary transfer roller 166 via the intermediate transfer belt 162, and the secondary transfer roller 166 is electrically grounded. When the color toner image on the intermediate transfer belt 162 is secondarily transferred to paper, a transfer bias of negative polarity, which is the normal charging polarity of the toner, is applied to the opposing roller 164, and the normally charged toner of negative polarity on the intermediate transfer belt is repulsively transferred to the paper P.

[0021] Residual toner remaining on the intermediate transfer belt 162 without being secondarily transferred to paper is removed by a cleaning blade 167a, which is a cleaning member of a belt cleaning device 167. The toner removed by the cleaning blade 167a is transported as waste toner through a transport path to a waste toner bottle 150 and collected.

[0022] In the printer 100, in order to stabilize image quality against environmental changes and over time, a control called process control is carried out as an adjustment operation at a predetermined timing. FIG. 2 is a schematic diagram for explaining a gradation pattern serving as an adjustment pattern on the intermediate transfer belt. The gradation pattern, which is an adjustment pattern, is made up of a plurality of toner patches, which are arranged in the width direction (also the main scanning direction) of the intermediate transfer belt 162 and the surface movement direction (also the sub-scanning direction) of the intermediate transfer belt 162. Specifically, in the width direction of the intermediate transfer belt 162, three toner patches with the same image density are arranged at a predetermined interval so as to be located at positions facing an optical sensor serving as a pattern detection means (the center in the width direction and both ends). In the surface movement direction of the intermediate transfer belt, toner patches with different image densities are arranged. In the example shown in FIG. 2, gradation patterns of black, cyan, magenta, and yellow are formed from the top.

[0023] The optical sensor unit 40 has optical sensors 40R, 40C, and 40F as a plurality of pattern detection means arranged at predetermined intervals in the belt width direction of the intermediate transfer belt 162. Each optical sensor outputs a signal according to the optical reflectance of the intermediate transfer belt 162 and the toner patches of each gradation pattern PK, PC, PM, and PY on the intermediate transfer belt 162, and detects the amount of toner adhesion. The printer 100 adjusts the image creation conditions such as the development bias based on the detected amount of toner adhesion.

[0024] The optical sensors 40R and 40F, which are arranged to face the width direction end regions of the intermediate transfer belt 162, are arranged outside the paper passing region. As a result, during the formation of a toner image to be transferred to paper, an adjustment pattern is formed outside the paper passing region, and the optical sensors 40R and 40F detect the amount of toner adhesion of the adjustment pattern. Then, based on the amount of toner adhesion detected by the optical sensors 40R and 40F, the developing bias, etc. can be adjusted to adjust the image density, etc.

[0025] The secondary transfer roller 166 is configured to be capable of moving toward and away from the intermediate transfer belt 162, and is separated from the intermediate transfer belt 162 when process control is being performed. This makes it possible to prevent toner from adhering to the secondary transfer roller 166 when the gradation pattern on the intermediate transfer belt 162 passes through the secondary transfer position. This makes it possible to suppress so-called back staining, in which toner adhering to the secondary transfer roller is transferred to the back side of the paper when the toner image on the intermediate transfer belt is secondarily transferred to the paper.

[0026] The base component of the toner, silica or titanium oxide added to the toner, and other so-called external additives of the toner are transferred from the photoreceptor 10 to the intermediate transfer belt 162. The external additives of the toner transferred to the intermediate transfer belt 162 may adhere to the intermediate transfer belt 162, causing filming on the intermediate transfer belt 162. In addition, when the lubricant application device 14 that applies a lubricant to the surface of the photoreceptor 10 is provided, various components contained in the lubricant are also transferred from the photoreceptor 10 to the intermediate transfer belt 162 in addition to the external additives of the toner. The external additives of the toner and the lubricant may interact with each other, causing the filming on the intermediate transfer belt 162 to worsen. Furthermore, at the secondary transfer nip, paper dust may be transferred from the paper P to the intermediate transfer belt 162 and adhere to the intermediate transfer belt 162, causing paper dust filming.

[0027] Such filming on the intermediate transfer belt 162 occurs when filming substances, such as various components contained in toner additives such as silica and lubricants, adhere to the intermediate transfer belt 162 due to external pressure (mainly contact pressure with the photoconductor) on the intermediate transfer belt 162. When filming occurs on the intermediate transfer belt 162, when a full solid image or halftone image is output, toner does not adhere to the areas corresponding to the filming, resulting in abnormal images such as white spots.

[0028] Furthermore, when filming occurs, the glossiness of the belt decreases. Therefore, when filming occurs in the area of ​​the intermediate transfer belt 162 facing the optical sensors 40R, 40C, and 40F, the output signal changes and it becomes impossible to properly detect the amount of adhesion of the gradation pattern on the intermediate transfer belt. In addition, there is also a problem that the output of the optical sensor becomes unstable due to unevenness in the filming state, making it impossible to perform correct image adjustment.

[0029] Furthermore, the cleaning performance of the cleaning blade 167a may be degraded due to filming. In the belt width direction, the position of the cleaning blade 167a corresponding to the arrangement positions of the optical sensors 40R, 40C, and 40F is often input with a gradation pattern with a large amount of adhesion per unit area. Therefore, if filming occurs in the area of ​​the intermediate transfer belt 162 facing the optical sensors 40R, 40C, and 40F, there is a high risk of poor cleaning (slip-through of toner) occurring when the gradation pattern is input to the cleaning blade 167a.

[0030] The filming can be scraped off by toner remaining at the contact point between the cleaning blade 167a and the surface of the intermediate transfer belt 162 (hereinafter referred to as the "cleaning point") and removed from the surface of the intermediate transfer belt 162. Specifically, the filming on the surface of the intermediate transfer belt is scraped off by the unevenness of the surface of the toner remaining at the cleaning point and the pressure applied to the toner from the cleaning blade 167a, etc.

[0031] Therefore, in order to suppress filming on the intermediate transfer belt 162, the printer 100 forms a scraping pattern as a long band-like pattern in the width direction of the intermediate transfer belt on the intermediate transfer belt 162 at a predetermined timing. Then, by inputting this scraping pattern to the cleaning blade 167a, a sufficient amount of toner is allowed to remain at the cleaning location.

[0032] Conventionally, the filming state of the intermediate transfer belt 162 is grasped from the travel distance of the intermediate transfer belt 162, and when the filming state reaches a predetermined state, the scraping pattern is formed, for example, between the sheets. At this time, if the secondary transfer roller is moved toward or away from the intermediate transfer belt when the scraping pattern passes the secondary transfer position, and the toner of the scraping pattern is prevented from adhering to the secondary transfer roller, the paper interval widens and productivity drops. Therefore, conventionally, when the scraping pattern passes the secondary transfer nip, a bias of the opposite polarity to the secondary transfer bias is applied to the opposing roller 164 to prevent the scraping pattern from being transferred to the secondary transfer roller. However, among the toners constituting the scraping pattern, there is a risk that the reversely charged toner, which is charged to the opposite polarity (positive polarity) to the normal charging polarity (negative polarity), may be electrostatically transferred to the secondary transfer roller. In addition, there is a risk that a part of the toner of the scraping pattern may be scraped off by the secondary transfer roller and mechanically adhere to the secondary transfer roller. In particular, as described below, in a device with a high image forming speed, if the amount of toner in the scraping pattern is increased in order to effectively remove filming from the intermediate transfer belt, the amount of toner adhering to the secondary transfer roller increases, which may result in soiling of the back of the paper.

[0033] Furthermore, by increasing the image formation speed to improve productivity, the temperature inside the machine rises and filming on the intermediate transfer belt 162 worsens. As described above, by retaining a sufficient amount of toner at the cleaning location, filming on the surface of the intermediate transfer belt can be effectively removed. This is preferable because filming on the intermediate transfer belt can be suppressed over time even in an apparatus with a high image formation speed. However, if the scraping pattern is made longer in the surface movement direction of the intermediate transfer belt 162 (hereinafter referred to as the belt movement direction) and the amount of toner in the scraping pattern is increased, toner may slip through, causing poor cleaning.

[0034] FIG. 3 is a diagram for explaining a cleaning failure when the amount of toner in the scraping pattern is large. When the scraping pattern is input to a cleaning position, which is a contact point between the cleaning blade 167a and the surface of the intermediate transfer belt 162, the toner T constituting the scraping pattern is blocked by the cleaning blade 167a, as shown in Fig. 3(a). The pressure of the toner T constituting the blocked scraping pattern causes the tip of the cleaning blade 167a to deform in the belt movement direction, forming a wedge-shaped space N between the intermediate transfer belt 162 and the cleaning blade 167a. When the toner T enters the wedge-shaped space N, the toner T is pressed against the intermediate transfer belt 162, and the filming on the intermediate transfer belt 162 is removed by the toner T.

[0035] 3(a), the pressure of the blocked toner on the tip of the cleaning blade 167a gradually increases. As a result, the tip of the cleaning blade 167a further deforms in the belt movement direction, gradually expanding the wedge-shaped space N. In this way, as the wedge-shaped space N expands, more toner enters the wedge-shaped space N, improving the filming removal effect.

[0036] However, if the amount of toner in the scraping pattern is large, the toner continues to be input to the cleaning area from the state shown in Fig. 3(b), and the pressure of the blocked toner on the tip of the cleaning blade 167a increases further. As a result, the tip of the cleaning blade 167a deforms further in the belt movement direction, causing toner to slip through the cleaning area, resulting in poor cleaning (Fig. 3(c)).

[0037] In this embodiment, in order to solve the above-mentioned problem of paper back staining and the problem that suppression of filming and suppression of cleaning defects cannot be achieved at the same time, the following is done. First, in order to solve the above-mentioned problem of paper back staining, a scraping pattern is formed when process control is performed to separate the secondary transfer roller 166, which is a transfer member, from the intermediate transfer belt 162. Also, in order to solve the problem of achieving both suppression of cleaning defects and suppression of filming, a plurality of scraping patterns are formed at predetermined intervals. Below, the characteristic features of this embodiment will be described with reference to the drawings.

[0038] FIG. 4 is a schematic diagram showing a part of the gradation pattern formed on the intermediate transfer belt 162 and the scraping pattern KP when the process control is performed. As shown in FIG. 4, in this embodiment, following the gradation pattern serving as the adjustment pattern, a scraping pattern serving as a belt-shaped pattern consisting of three solid images is formed on the intermediate transfer belt 162 at a predetermined interval.

[0039] As described above, when process control is performed, the secondary transfer roller 166 is separated from the intermediate transfer belt 162 to form a gradation pattern on the intermediate transfer belt. Following this gradation pattern, a scraping pattern KP is formed, and the secondary transfer roller 166 is kept separated from the intermediate transfer belt 162 until the scraping pattern KP passes the secondary transfer position. This prevents the toner of the multiple toner patches of the gradation pattern and the toner of the scraping pattern KP from adhering to the secondary transfer roller 166, thereby preventing back staining of the paper.

[0040] Furthermore, by forming the scraping pattern KP when process control is being executed, the number of times that the apparatus experiences downtime can be reduced, compared to when the operation of forming the scraping pattern KP and the process control are performed at different times.

[0041] Furthermore, by forming the scraping pattern KP when the process control is being executed, in one secondary transfer roller separation operation, the gradation pattern and the scraping pattern KP can pass the secondary transfer position without coming into contact with the secondary transfer roller 166. This makes it possible to reduce the total downtime of the device compared to when the scraping pattern formation operation and the process control are performed at different times.

[0042] 4(b), each scraping pattern KP is a strip-shaped pattern that is long in the width direction (hereinafter simply referred to as the width direction) of the intermediate transfer belt 162. Also, each scraping pattern KP is longer than the maximum paper passing width that the device can transport, and extends in the width direction to the opposing areas of the optical sensors 40R, 40F that are arranged opposite both ends of the intermediate transfer belt 162. This makes it possible to effectively suppress filming in the maximum paper passing width area of ​​the intermediate transfer belt 162 where the toner image to be transferred to the paper is formed, and effectively suppresses the occurrence of abnormal images such as blank areas.

[0043] Further, the scraping pattern KP extends in the width direction up to the opposing areas of the optical sensors 40R, 40F arranged opposite both ends of the intermediate transfer belt 162. Therefore, filming in the opposing portions of the intermediate transfer belt 162 facing the optical sensors 40R, 40F can be effectively suppressed, and the amount of adhesion can be effectively detected.

[0044] If the length W2 of the scraping pattern KP in the belt movement direction is shorter than the length W1 of the toner patch in the belt movement direction, the amount of toner input to the cleaning area at one time is small, and the pressure of the remaining toner applied to the tip of the cleaning blade 167a becomes insufficient. As a result, the wedge-shaped space N shown in Figure 3(b) is not formed, and filming on the intermediate transfer belt surface may not be removed well.

[0045] In this embodiment, by making the length W2 of the scraping pattern KP in the belt movement direction longer than the length W1 of the toner patch in the belt movement direction, the amount of toner in the scraping pattern KP can be made greater than or equal to the amount of toner that deforms the tip of the cleaning blade in the belt movement direction. This forms the wedge-shaped space N, and the toner of the scraping pattern input to the cleaning area can effectively remove filming on the intermediate transfer belt surface.

[0046] In addition, the length W2 of the scraping pattern KP in the belt movement direction is set so that the amount of toner in the scraping pattern is less than the amount of toner that does not cause cleaning defects. In this embodiment, as shown in the verification experiment described later, by setting the length W2 of the scraping pattern KP in the belt movement direction to 80 mm or less, the amount of toner in the scraping pattern KP can be made less than the amount of toner that does not cause cleaning defects.

[0047] If the interval Sp between the scraping patterns KP is too short, when the next scraping pattern KP is input to the cleaning spot, the amount of toner remaining at the cleaning spot (the sum of the amount of toner in the scraping pattern and the amount of remaining toner not removed at the cleaning spot) may be greater than the amount of toner that causes cleaning defects. Therefore, the interval Sp needs to be set to a predetermined value or more. In this embodiment, as shown in the verification experiment described below, by setting the interval Sp between the scraping patterns KP to at least 80 mm or more, it is possible to achieve an interval that does not cause cleaning defects.

[0048] On the other hand, if the interval Sp is too long, the toner constituting the preceding scraping pattern KP may be completely removed from the cleaning location, the wedge-shaped space N may disappear, and the filming removal may be interrupted. As a result, the filming removal may become uneven. Also, if the interval Sp is too long, the distance L1 from the first scraping pattern to the last scraping pattern becomes long. As a result, the process control execution time becomes long, and the downtime of the device becomes long. Therefore, it is preferable to make the interval Sp as short as possible (around 80 mm) within the above-mentioned predetermined value (80 mm) at which no cleaning failure occurs. This makes it possible to suppress the occurrence of cleaning failure, to remove filming from the intermediate transfer belt evenly and well, and to suppress the process control execution time from becoming long.

[0049] FIG. 5 is a diagram for explaining a case where the scraping pattern KP of this embodiment is input to a cleaning location. 5(a) and 5(b), when the scraping pattern KP is input to the cleaning location, the tip of the cleaning blade 167a is deformed in the belt movement direction by the pressure of the blocked toner, as in the conventional method. Then, as in the conventional method, the toner enters the wedge-shaped space N formed by the deformation of the tip of the cleaning blade 167a in the belt movement direction, and the filming on the intermediate transfer belt 162 is effectively removed.

[0050] The length W2 of the scraping pattern in the belt movement direction in this embodiment is shorter than in the past, and the amount of toner in the scraping pattern is smaller than in the past. Therefore, further toner input from the state of FIG. 5(b) is suppressed, and further deformation of the tip of the cleaning blade 167a in the belt movement direction is suppressed. As a result, the deformation of the tip of the cleaning blade 167a can be kept to a level where toner does not slip through, and the occurrence of cleaning defects can be suppressed.

[0051] After the scraping pattern is input, the toner remaining at the cleaning portion is gradually removed from the intermediate transfer belt 162, and the pressure of the toner on the tip of the cleaning blade 167a decreases. As a result, the tip of the cleaning blade gradually returns to its initial shape due to its restoring force, and the wedge-shaped space N gradually decreases, returning to the state shown in FIG. 5(a) as shown in FIG. 5(c).

[0052] Then, the next scraping pattern KP is input to the cleaning spot before the toner forming the previous scraping pattern KP is completely removed from the cleaning spot and the wedge-shaped space N disappears. As a result, the filming removal by toner continues, and the filming on the intermediate transfer belt 162 can be removed evenly.

[0053] In this embodiment, by forming a plurality of scraping patterns KP at a predetermined interval, the amount of toner in each scraping pattern KP is set to a toner amount that does not cause cleaning failure, and depending on the number of scraping patterns KP, the amount of toner input to the cleaning blade 167a can be set to a toner amount that can satisfactorily remove filming from the intermediate transfer belt 162. This makes it possible to achieve both suppression of cleaning failure and satisfactorily remove filming from the intermediate transfer belt 162.

[0054] As described above, in this embodiment, the toner amount of each scraping pattern KP and the interval Sp between the scraping patterns KP are adjusted to prevent cleaning defects. However, for example, depending on the environment in which the device is used or over time, the contact pressure of the cleaning blade 167a against the intermediate transfer belt 162 may change, causing a decrease in cleaning performance and resulting in minor cleaning defects.

[0055] If the scraping pattern KP is formed before the gradation pattern, when the above-mentioned minor cleaning failure occurs, the accuracy of detecting the amount of toner patch adhesion by the optical sensors 40F, 40C, and 40R may be reduced due to the influence of the minor cleaning failure. Specifically, the amount of adhesion of the toner patch may be detected as being greater than the actual amount of adhesion of the toner patch. As a result, the image density after the image density adjustment based on the amount of adhesion of the toner patch may be lighter than the target image density.

[0056] However, in this embodiment, by forming the scraping pattern KP after the gradation pattern, even if a minor cleaning failure occurs, the minor cleaning failure does not affect the detection of the amount of adhesion of the toner patch, and thus the optical sensors 40F, 40C, and 40R can detect the amount of adhesion of the toner patch with high accuracy.

[0057] In this embodiment, the three scraping patterns are formed with toners of different colors, as shown in Fig. 4. This makes it possible to prevent toner consumption from being concentrated in a specific color.

[0058] Also, the scraping pattern on the most downstream side in the surface movement direction of the intermediate transfer belt 162 is M color, the central scraping pattern is C color, and the most upstream scraping pattern is Y color, following the arrangement order of the imaging units 121 shown in FIG. 1. In this way, the image formation time for forming three scraping patterns can be shortened by making the order of the colors of the scraping patterns follow the arrangement order of the imaging units 121 from the downstream side in the surface movement direction of the intermediate transfer belt. Also, three scraping patterns may be formed on the intermediate transfer belt 162 in the order of K, M, and C colors. Even with this configuration, for example, the image formation time for forming three scraping patterns can be shortened compared to the case where the order is K, C, and Y colors, skipping M color. Note that the image formation time is the time from when one of the three imaging units starts a series of image formation processes to when the last one of the three imaging units ends a series of image formation processes. The image forming process is a series of processes from the start of uniform charging of the photoconductor surface by the charging device 11 to the primary transfer of the toner image onto the intermediate transfer belt.

[0059] The verification experiments carried out by the present inventors will be described below. As shown in FIG. 6, verification experiments were carried out under conditions (1) to (3) in which the length of the scraping pattern in the belt movement direction and the number of scraping patterns were different from one another.

[0060] Condition (1) is a condition in which one solid image scraping pattern KP with a length in the belt movement direction of 80 mm is formed, and condition (2) is a condition in which one solid image scraping pattern KP with a length in the belt movement direction of 200 mm is formed. Condition (3) is a condition in which three solid image scraping patterns KP with lengths in the belt movement direction of 70 mm, 60 mm, and 70 mm are formed at intervals of 80 mm. Then, cleaning performance and filming performance were evaluated under conditions (1) to (3), respectively.

[0061] <Cleaning performance evaluation> The cleaning performance was evaluated under the following conditions. Cleaning blade contact pressure: 20N / m -Intermediate transfer belt linear speed: 300mm / s The cleaning performance was evaluated based on the image printed after the scraping pattern KP was formed. When no streaky abnormal image was observed in the printed image, the cleaning performance was evaluated as "○", and when streaky abnormal image was observed in the printed image, the cleaning performance was evaluated as "×".

[0062] <Filming Evaluation> The filming property was evaluated by printing 150,000 sheets of a running chart with an image area ratio of 5%, and then forming a test pattern on the intermediate transfer belt. If no error occurred when the optical sensors 40R, 40C, and 40F detected the amount of adhesion of the test pattern, the filming property was evaluated as "good". On the other hand, if an error occurred when the optical sensors 40R, 40C, and 40F detected the amount of adhesion of the test pattern, the filming property was evaluated as "poor". The scraping pattern KP was formed at the timing when the process control was performed.

[0063] The results of the verification experiment are shown in Table 1 below. [Table 1]

[0064] As shown in Table 1, under condition (1), the cleaning performance was rated as "good", but the filming was rated as "poor". This is thought to be because in the scraping pattern under condition (1), the amount of toner input to the cleaning area at one time is small, so no toner slips through, and the cleaning performance was rated as "good". On the other hand, under condition (1), the filming was rated as "poor".

[0065] As shown in Table 1, under condition (2) where one scraping pattern KP with a length in the belt movement direction of 200 mm or more was formed, the cleaning performance was rated as "x." 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 167a was significantly deformed in the belt movement direction due to the pressure of the toner input to the cleaning area, as shown in Figure 3(c), causing the toner to slip through, resulting in streaky abnormal images.

[0066] On the other hand, the filming evaluation was "good" under condition (2). This is thought to be because a large amount of toner was input to the cleaning blade 167a, so that a predetermined amount or more of toner remained at the cleaning point for a long period of time, and the wedge-shaped space N was maintained for a long period of time. As a result, filming on the intermediate transfer belt 162 was suppressed over time, and the filming evaluation was thought to be "good."

[0067] From conditions (1) and (2), it was found that cleaning failures can be suppressed by setting at least the length of the scraping pattern KP in the moving direction to 80 mm or less. It was also found that filming on the intermediate transfer belt 162 over time can be suppressed by setting at least the length of the scraping pattern KP in the belt moving direction to 200 mm or more.

[0068] As shown in Table 1, under condition (3), the cleaning performance and filming resistance were both evaluated as "good." This is because the length of each scraping pattern KP in the moving direction is 80 mm or less. Therefore, it is believed that the amount of toner input to the cleaning area at one time was kept below the amount of toner that would cause cleaning defects, and the cleaning blade was able to effectively block the toner at the cleaning area.

[0069] Moreover, under condition (3), three scraping patterns are formed with an interval of 80 mm between them. In this way, by making the interval between the scraping patterns at least 80 mm or more, and making it longer than the length of the scraping pattern in the belt movement direction (80 mm or less), it was confirmed that the amount of toner remaining at the cleaning spot when the next scraping pattern is input to the cleaning spot will not exceed the amount of toner that would cause a cleaning defect, and therefore no cleaning defect will occur.

[0070] Furthermore, if the interval between the scraping patterns KP is at least 80 mm, the toner at the cleaning spot is completely removed by the cleaning blade 167a, and the next scraping pattern KP can be input to the cleaning spot before the wedge-shaped space N disappears. This allows the toner filming at the cleaning spot to continue to be scraped off. Moreover, under condition (3), the total length of the three scraping patterns in the belt movement direction is 200 mm, the same as under condition (2). This allows the same amount of toner as under condition (2) to be input to the cleaning spot, and similarly to condition (2), the filming on the intermediate transfer belt 162 can be successfully removed, resulting in a filming evaluation of "good."

[0071] From the above, it was found that by forming multiple scraping patterns, setting the length of each scraping pattern in the belt movement direction to 80 mm or less, setting the spacing between the scraping patterns to 80 mm, and setting the total length of the multiple scraping patterns in the belt movement direction to 200 mm or more, it is possible to effectively suppress cleaning failures and filming on the intermediate transfer belt 162.

[0072] In the above description, each scraping pattern is a monochromatic solid image made of one color of toner, but the amount of adhesion per unit area of ​​each scraping pattern may be made greater than the amount of adhesion of a monochromatic solid image. This allows, for example, the length of the scraping pattern in the belt movement direction to be shorter than 70 mm, resulting in the same amount of toner as when the length of the scraping pattern of the solid image in the belt movement direction is 70 mm. This allows the length of the three scraping patterns in the belt movement direction to be shorter than 360 mm in FIG. 6, thereby shortening the execution time of the process control.

[0073] By appropriately adjusting the charging bias of the charging device 11, the developing bias of the developing device 12, and the exposure amount of the exposure device 140, the adhesion amount per unit area of ​​each scraping pattern can be made greater than the adhesion amount per unit area of ​​a single-color solid image. Also, by forming each writing pattern with toner of two or more colors, the adhesion amount per unit area may be made greater than the adhesion amount per unit area of ​​a single-color solid image composed of toner of one color.

[0074] Furthermore, the speed at which filming progresses varies depending on the internal temperature and the linear speed of the intermediate transfer belt 162. Therefore, the image density of the scraping pattern (the amount of toner adhesion per unit area) may be changed depending on the speed at which filming progresses.

[0075] For example, a temperature sensor is provided as a temperature detection means for detecting the temperature inside the machine, and when the temperature of the temperature sensor is below a threshold value, the image density of each scraping pattern is lightened from the solid image because the filming progresses slowly, thereby reducing the amount of toner adhesion per unit area. This makes it possible to suppress the amount of toner consumption, suppress cleaning failures, and effectively remove filming.

[0076] Furthermore, in an image forming apparatus having a plurality of image forming modes in which the linear speed of the intermediate transfer belt 162 differs from one another, when the image forming mode is the low-speed mode, the linear speed of the intermediate transfer belt 162 is low and the filming progresses at a slow speed. Therefore, when the image forming mode is the low-speed mode, the image density of each scraping pattern is lightened from the solid image to reduce the amount of toner adhesion per unit area. This makes it possible to suppress the amount of toner consumption, suppress cleaning defects, and effectively remove filming.

[0077] By controlling the voltage applied to the charging member of the charging device 11, the charging potential of the photoconductor 10 is changed, and the image density of the scraping pattern is changed. Note that no exposure is performed by the exposure device, and the voltage applied to the charging member is controlled to make the charging potential of the photoconductor lower than the development bias, thereby forming a desired development potential and forming a band-shaped scraping pattern. As shown in FIG. 7, the absolute value of the voltage applied to the charging member is increased, thereby increasing the absolute value of the charging potential of the photoconductor, thereby reducing the image density of the scraping pattern.

[0078] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the spirit of the present invention described in the claims, unless otherwise specifically limited in the above description.

[0079] The above description is merely an example, and each of the following aspects provides unique effects. (Aspect 1) In an image forming apparatus comprising an image creating means such as an image creating unit 121 that creates a toner image, an image carrier such as an intermediate transfer belt 162 that carries the toner image created by the image creating means, a transfer member such as a secondary transfer roller 166 that transfers the toner image on the image carrier to a recording medium such as paper, and a cleaning member such as a cleaning blade 167a that cleans the surface of the image carrier, an adjustment pattern such as a gradation pattern consisting of a plurality of toner patches spaced apart in a direction perpendicular to the surface movement direction of the image carrier is formed on the image carrier, the adjustment pattern is detected by a pattern detection means such as optical sensors 40F, 40C, 40R, and an adjustment operation such as process control that adjusts the image creating means is performed based on the detection result of the pattern detection means, and when the adjustment operation is performed, the transfer member is separated from the image carrier, and a plurality of band-shaped patterns such as scraping patterns KP that are long in the orthogonal direction are formed at predetermined intervals in the surface movement direction during the adjustment operation. In an apparatus in which the linear speed of an image carrier such as the intermediate transfer belt 162 is increased to improve productivity, filming on the image carrier is likely to worsen due to an increase in the temperature inside the apparatus. By increasing the length of a strip-shaped pattern such as the scraping pattern KP in the surface movement direction of the image carrier and increasing the amount of toner in the strip-shaped pattern, the amount of toner input to the cleaning member increases, and the filming removal effect can be improved. This makes it possible to effectively remove filming even in an apparatus in which the linear speed of the image carrier is high. However, if the toner amount of the toner image pattern is increased, a large amount of toner is input to the cleaning member at one time, and the amount of toner blocked by the cleaning member increases. If the amount of toner blocked by the cleaning member increases, the pressure from the blocked toner applied to the cleaning member increases, and toner may slip through the contact portion of the cleaning member with the image carrier, causing a cleaning failure. As a result, there was a risk that it would be impossible to simultaneously suppress cleaning failure and effectively remove filming on the image carrier. In addition, in the above-mentioned Patent Document 1, as described above, when the belt-shaped pattern passes through the transfer nip, a bias of the opposite polarity to the transfer bias when transferring the toner image to the paper is applied to the transfer nip to prevent the belt-shaped pattern from being transferred to the secondary transfer roller, but when the belt-shaped pattern passes through the transfer nip, there is a risk that the toner constituting the belt-shaped pattern, which is charged with a polarity opposite to the normal charging polarity, will adhere to the transfer member. In addition, there is a risk that part of the toner of the belt-shaped pattern will be scraped off by the transfer member and mechanically adhere to the transfer member. In the first aspect, by forming a plurality of belt-shaped patterns at a predetermined interval, the toner amount of the belt-shaped patterns is set to a toner amount that does not cause cleaning defects, and the number of toner image patterns formed by the number of belt-shaped patterns can be set to a toner amount that corresponds to the filming state on the image carrier. In addition, since the plurality of toner image patterns are formed at a predetermined interval in the moving direction of the image carrier, the toner of the toner image patterns blocked by the cleaning member is removed to a certain extent from the surface of the image carrier, and the next toner image pattern can be input to the cleaning member after the toner blocked by the cleaning member has decreased to a certain extent. Therefore, the amount of blocked toner can be prevented from becoming an amount of toner that causes cleaning defects, and both the prevention of cleaning defects and the satisfactory removal of filming on the image carrier can be achieved. In addition, by forming a plurality of belt-shaped patterns during the adjustment operation and separating the transfer member from the image carrier during the adjustment operation, it is possible to prevent the toner of the adjustment patterns and the toner of the belt-shaped patterns from adhering to the transfer member. This makes it possible to suppress the occurrence of back stains on the paper. In addition, it is possible to reduce the number of times the device is downtimed, compared to when the belt-shaped patterns are formed at a timing different from the adjustment operation.

[0080] (Aspect 2) In the first embodiment, the length of the stripe pattern such as the scraping pattern Kp in the surface movement direction is longer than the length of the toner patch in the surface movement direction. By making the length of the band-shaped pattern in the surface movement direction longer than the length of the toner patch in the surface movement direction, an amount of toner that provides a good filming removal effect can be input to the cleaning member compared to when the length of the band-shaped pattern in the surface movement direction is shorter than the length of the toner patch in the surface movement direction.

[0081] (Aspect 3) In aspect 1, imaging means such as a plurality of imaging units 121Y, C, M, Bk, each of which forms a toner image of a different color, are arranged side by side in the direction of surface movement of an image carrier such as an intermediate transfer belt 162, and strip-shaped patterns such as a plurality of scraping patterns KP are formed in different colors. This makes it possible to prevent toner consumption from being concentrated in a specific color, compared to when band-shaped patterns such as a plurality of scraping patterns KP are formed in one color, as described in the embodiment.

[0082] (Aspect 4) In the third aspect, the color order of the stripe patterns such as the multiple scraping patterns KP from the downstream side in the surface movement direction follows the color order of the imaging means such as the multiple imaging units 121Y, C, M, and Bk from the downstream side in the surface movement direction. According to this, as explained in the embodiment, it is possible to shorten the imaging time for imaging strip-shaped patterns such as a plurality of scraping patterns KP.

[0083] (Aspect 5) In any one of the aspects 1 to 4, the image density of the stripe pattern such as the scraping pattern KP is made variable. According to this, as described in the embodiment, the amount of toner in a band-shaped pattern such as a scraping pattern can be adjusted according to the speed at which filming progresses, thereby suppressing filming while reducing toner consumption.

[0084] (Aspect 6) In any one of the first to fifth aspects, the interval Sp between the band-like patterns is longer than the length of the band-like patterns in the surface moving direction. According to this, as described in the embodiment, when a band-shaped pattern such as the next scraping pattern is input to the cleaning location, the amount of toner remaining at the cleaning location can be prevented from exceeding the amount of toner that would cause cleaning failure, thereby preventing the occurrence of cleaning failure.

[0085] (Aspect 7) In any of the aspects 1 to 6, the length in the orthogonal direction of the strip-shaped pattern such as the scraping pattern Kp is equal to or greater than the paper passing area of ​​the image carrier such as the intermediate transfer belt 162 . According to this, as described in the embodiment, it is possible to effectively prevent the occurrence of abnormal images such as blank areas due to filming in an image formed on a recording medium such as paper.

[0086] (Aspect 8) In any of aspects 1 to 7, a pattern detection means such as an optical sensor is arranged at least at both ends in the perpendicular direction of an image carrier such as the intermediate transfer belt 162, and the perpendicular length of a band-shaped pattern such as the scraping pattern KP is equal to or greater than the perpendicular length from the pattern detection means at one end of the perpendicular direction to the pattern detection means at the other end of the perpendicular direction. According to this, as described in the embodiment, it is possible to effectively prevent the occurrence of abnormal images such as blank areas in images formed on recording media such as paper. Also, it is possible to effectively prevent filming in the opposing areas of pattern detection means such as optical sensors 40F, 40R arranged to face each other at both ends of the image carrier, and toner patches can be effectively detected.

[0087] (Aspect 9) In any of the aspects 1 to 8, a stripe pattern such as a plurality of scraping patterns KP is formed following an adjustment pattern such as a gradation pattern. According to this, as described in the embodiment, even if a minor cleaning failure occurs due to the scraping pattern, the gradation pattern is not affected, and the toner patch of the gradation pattern can be detected well by the pattern detection means.

[0088] (Aspect 10) In any of the first to ninth embodiments, the toner adhesion amount per unit area of ​​a band-shaped pattern such as the scraping pattern KP is set to be greater than the adhesion amount per unit area of ​​a single-color solid image composed of toner of one color. According to this, as described in the embodiment, the length of the belt-like pattern in the surface movement direction can be shortened compared to when the belt-like pattern such as the scraping pattern KP is a monochromatic solid image composed of one color of toner, and the amount of toner can be the same as when the belt-like pattern is a monochromatic solid image. As a result, the length from the most downstream belt-like pattern in the surface movement direction to the most upstream belt-like pattern in the surface movement direction can be shortened compared to when multiple belt-like patterns are monochromatic solid images. This makes it possible to shorten the adjustment operation time for process control, etc. [Explanation of symbols]

[0089] 11: Charging device 12: Developing device 40: Optical sensor unit 40C: Optical sensor 40F: Optical sensor 40R: Optical sensor 100: Printer 120: Imaging section 121: Imaging unit 140: Exposure equipment 160: Intermediate transfer unit 162: Intermediate transfer belt 166: Secondary transfer roller 167: Belt cleaning device 167a: Cleaning blade KP: Scraping pattern N: Wedge-shaped space P:Paper [Prior art documents] [Patent documents]

[0090] [Patent Document 1] JP 2023-29257 A

Claims

1. An imaging means for forming a toner image; an image carrier that carries the toner image formed by the imaging unit; a transfer member that transfers the toner image on the image carrier to a recording medium; a cleaning member for cleaning the surface of the image carrier; an image forming apparatus comprising: an adjustment pattern formed on an image carrier, the adjustment pattern being made up of a plurality of toner patches spaced apart in a direction perpendicular to a surface movement direction of the image carrier; a pattern detection means detecting the adjustment pattern; and an adjustment operation for adjusting the image forming means based on a detection result of the pattern detection means, When the adjustment operation is performed, the transfer member is separated from the image carrier, the image forming apparatus forming a plurality of band-shaped patterns that are long in the perpendicular direction at predetermined intervals in the surface movement direction during the adjustment operation;

2. 2. The image forming apparatus according to claim 1, an image forming apparatus, wherein a length of the belt-shaped pattern in the surface movement direction is longer than a length of the toner patch in the surface movement direction;

3. 2. The image forming apparatus according to claim 1, A plurality of image forming means each forming a toner image of a different color are arranged in the surface moving direction, The image forming apparatus according to claim 1, wherein the plurality of belt-like patterns are formed in different colors.

4. 4. The image forming apparatus according to claim 3, 1. An image forming apparatus, comprising: a color sequence of the plurality of belt-like patterns from a downstream side in the surface movement direction, the color sequence of the plurality of image forming means from a downstream side in the surface movement direction.

5. 2. The image forming apparatus according to claim 1, 1. An image forming apparatus, comprising: a belt-like pattern and a belt-like pattern; a belt-like pattern that is spaced from one another by a distance greater than a length of the belt-like pattern in a surface movement direction.

6. 2. The image forming apparatus according to claim 1, An image forming apparatus comprising: an image forming device in which the image density of the belt-like pattern is changeable.

7. 2. The image forming apparatus according to claim 1, 2. An image forming apparatus comprising: a belt-shaped pattern having a length in the perpendicular direction that is equal to or greater than a paper passing area of ​​the image carrier.

8. 2. The image forming apparatus according to claim 1, the pattern detection means are disposed at least on both ends of the image carrier in the perpendicular direction, an image forming apparatus, characterized in that a length of the belt-shaped pattern in the orthogonal direction is equal to or greater than a length in the orthogonal direction from the pattern detection means at one end in the orthogonal direction to the pattern detection means at the other end in the orthogonal direction;

9. 2. The image forming apparatus according to claim 1, The image forming apparatus according to claim 1, wherein the belt-shaped pattern is formed following the adjustment pattern.

10. 2. The image forming apparatus according to claim 1, an image forming apparatus including: a toner adhesion amount per unit area of ​​said belt-like pattern being greater than a toner adhesion amount per unit area of ​​a single-color solid image;

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