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EP-4741940-A1 - IMAGE FORMING APPARATUS

EP4741940A1EP 4741940 A1EP4741940 A1EP 4741940A1EP-4741940-A1

Abstract

An image forming apparatus (100) includes an image carrying member (1a-1d), a charging device (1a-2d), an exposure device (5), a developing device (3a-3d), an intermediate transfer belt (8), a cleaning brush (23), an image density sensor (50), and a control portion (90). The control portion (90) executes calibration including: a first adjustment process of changing an image forming condition based on a result of detection of a first reference image (Y1, Y') formed on the intermediate transfer belt; a first bare-surface-measurement process of detecting, after execution of the first adjustment process, a first-reference-image (Y1, Y1') formation area; and a second adjustment process of changing, after execution of the first bare-surface-measurement process, the image forming condition based on a result of detection of a second reference image (Y2, Y2') formed on the first-reference-image (Y1, Y1') formation area. In a case where an output value of the image density sensor (50) in the first bare-surface-measurement process is equal to or less than a threshold value, the second adjustment process is executed.

Inventors

  • Kikuchi, Einosuke
  • Matayoshi, Akira

Assignees

  • KYOCERA Document Solutions Inc.

Dates

Publication Date
20260513
Application Date
20251110

Claims (7)

  1. An image forming apparatus (100), comprising: an image carrying member (1a-1d) that includes a photosensitive layer formed on a surface thereof; a charging device (2a-2d) that charges the surface of the image carrying member (1a-1d); an exposure device (5) that exposes, to light, the surface of the image carrying member (1a-1d) having been charged by the charging device (2a-2d), thereby forming an electrostatic latent image with attenuated charge; a developing device (3a-3d) that includes a developer carrying member (31) carrying a developer including toner, and that develops the electrostatic latent image having been formed on the image carrying member (1a-1d) into a toner image; an intermediate transfer belt (8) to which the toner image having been formed on the image carrying member (1a-1d) is primarily transferred; a cleaning brush (23) that removes toner remaining on the intermediate transfer belt (8); an image density sensor (50) that detects density of the toner image having been primarily transferred onto the intermediate transfer belt (8); and a control portion (90) that executes calibration to correct image density based on density of a reference image having been detected by the image density sensor (50), characterized in that the calibration includes: a first adjustment process of detecting density of a first reference image (Y1, Y1') formed on the intermediate transfer belt (8) and adjusting an image forming condition based on a detection result; a first bare-surface-measurement process of detecting a first-reference-image (Y1, Y1') formation area using the image density sensor (50) when the intermediate transfer belt (8) has rotated once or more after execution of the first adjustment process; and a second adjustment process of detecting, when the intermediate transfer belt (8) has rotated once after execution of the first bare-surface-measurement process, density of a second reference image (Y2, Y2') formed on the first-reference-image (Y1, Y1') formation area, and changing, based on a detection result, an image forming condition that is different from the image forming condition adjusted in the first adjustment process, and in a case where a fluctuation range of an output waveform of the image density sensor (50) in the first bare-surface-measurement process is equal to or less than a threshold value, the control portion (90) determines that a surface condition of the intermediate transfer belt (8) is normal, and executes the second adjustment process.
  2. The image forming apparatus (100) according to claim 1, wherein in a case where the fluctuation range of the output waveform of the image density sensor (50) in the first bare-surface-measurement process exceeds the threshold value, the control portion (90) executes a second bare-surface-measurement process of detecting the first-reference-image (Y1, Y1') formation area using the image density sensor (50) after causing the intermediate transfer belt (8) to rotate once more, and in a case where a fluctuation range of an output waveform of the image density sensor (50) in the second bare-surface-measurement process is equal to or less than the threshold value, the control portion (90) executes the second adjustment process.
  3. The image forming apparatus (100) according to claim 2, further comprising a notification portion (71) capable of issuing notifications regarding conditions of various portions of the image forming apparatus (100) including the cleaning brush (23), wherein in a case where the fluctuation range of the output waveform of the image density sensor (50) in the second bare-surface-measurement process is equal to or less than the threshold value, the control portion (90), using the notification portion (71), issues a notification regarding deteriorated performance of the cleaning brush (23).
  4. The image forming apparatus (100) according to claim 2, wherein in a case where the fluctuation range of the output waveform of the image density sensor (50) in the second bare-surface-measurement process exceeds the threshold value, the control portion (90) does not execute the second adjustment process and stops the calibration.
  5. The image forming apparatus (100) according to claim 4, further comprising a notification portion (71) capable of issuing notifications regarding conditions of various portions of the image forming apparatus (100) including the intermediate transfer belt (8), wherein in a case where the fluctuation range of the output waveform of the image density sensor (50) in the second bare-surface-measurement process exceeds the threshold value, the control portion (90), using the notification portion (71), issues a notification prompting replacement of the intermediate transfer belt (8).
  6. The image forming apparatus (100) according to claim 1, wherein the first adjustment process is a process in which density of a solid image formed as the first reference image (Y1, Y1') on the intermediate transfer belt (8) is detected, and a development voltage applied to the developer carrying member is adjusted based on a detection result, and the control portion (90) executes the first bare-surface-measurement process when the intermediate transfer belt (8) has rotated twice after execution of the first adjustment process.
  7. The image forming apparatus (100) according to claim 1, wherein the second adjustment process is a process in which density of the second reference image (Y2, Y2') formed on the intermediate transfer belt (8) is detected, and at least one of a light amount of the exposure device (5) and a gradation input value is adjusted based on a detection result.

Description

BACKGROUND The present disclosure relates to an image forming apparatus employing an intermediate transfer method in which a cleaning brush is used to remove residual toner from the surface of an intermediate transfer belt. Conventionally, there has been known an intermediate transfer type image forming apparatus including an intermediate transfer belt that is endless-shaped and driven to rotate in a predetermined direction and a plurality of image forming portions arranged along the intermediate transfer belt. In such an image forming apparatus, toner images of respective colors are primarily transferred by the image forming portions onto the intermediate transfer belt so as to be sequentially superimposed on each other, and then the toner images are secondarily transferred onto a recording medium. In the intermediate transfer type image forming apparatus, in a case where the intermediate transfer belt has an elastic layer, a cleaning device is used which includes, arranged in its housing, a cleaning brush that mechanically and electrically collects toner remaining on the surface of the intermediate transfer belt, a collection roller that collects toner from the cleaning brush, a scraper that scrapes off toner from the surface of the collection roller, and a conveyance spiral that conveys toner scraped off from the surface of the collection roller into a waste toner collection container. On the other hand, in the intermediate transfer type image forming apparatus, a calibration operation is executed to adjust image density or color shift by detecting the density of a reference image (patch image) transferred onto the intermediate transfer belt. At that time, if a defect such as a scratch or contamination has occurred on the intermediate transfer belt, it may prevent the calibration operation from accurately adjusting image density or color shift. SUMMARY An object of the present disclosure is to provide an image forming apparatus capable of accurately executing the second stage of two-stage calibration performed using reference images formed at the same position on the intermediate transfer belt. According to one aspect of the present disclosure, an image forming apparatus includes an image carrying member, a charging device, an exposure device, a developing device, an intermediate transfer belt, a cleaning brush, an image density sensor, and a control portion. The image carrying member includes a photosensitive layer formed on a surface thereof. The charging device charges the surface of the image carrying member. The exposure device exposes, to light, the surface of the image carrying member having been charged by the charging device, thereby forming an electrostatic latent image with attenuated charge. The developing device includes a developer carrying member carrying a developer including toner, and develops the electrostatic latent image having been formed on the image carrying member into a toner image. The intermediate transfer belt, having an endless shape, rotates in contact with the image carrying member, thereby having the toner image primarily transferred thereto. The cleaning brush removes toner remaining on the intermediate transfer belt. The image density sensor detects density of the toner image having been primarily transferred onto the intermediate transfer belt. The control portion executes calibration to correct image density based on density of a reference image having been detected by an image density sensor. The calibration includes: a first adjustment process of detecting density of a first reference image formed on the intermediate transfer belt and adjusting an image forming condition based on a detection result; a first bare-surface-measurement process of detecting a first-reference-image formation area using an image density sensor when the intermediate transfer belt has rotated once or more after execution of the first adjustment process; and a second adjustment process of detecting, when the intermediate transfer belt has rotated once after execution of the first bare-surface-measurement process, density of a second reference image formed on the first-reference-image formation area, and changing, based on a detection result, an image forming condition that is different from the image forming condition adjusted in the first adjustment process. In a case where a fluctuation range of an output waveform of the image density sensor in the first bare-surface-measurement process is equal to or less than a threshold value, the control portion determines that a surface condition of the intermediate transfer belt is normal, and executes the second adjustment process. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing an inner configuration of an image forming apparatus 100 according to one embodiment of the present disclosure.FIG. 2 is a side sectional view showing a configuration around an intermediate transfer unit 30 incorporated in the image forming apparatus 100.