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US-12619175-B2 - Image forming apparatus that can perform a first image quality improvement mode in which the frequency of an alternating-current voltage in a development voltage and a primary transfer current flowing between an image carrying member and a primary transfer member are simultaneously changed

US12619175B2US 12619175 B2US12619175 B2US 12619175B2US-12619175-B2

Abstract

An image forming apparatus includes an image carrying member, a charging device, a charging voltage power supply, an exposure device, a development device, a development voltage power supply, an intermediate transfer member, a primary transfer member, a secondary transfer member, a transfer voltage power supply and a control unit. The development device includes a developer carrying member which carries a developer containing a toner. The development voltage power supply applies, to the developer carrying member, a development voltage in which an alternating-current voltage is superimposed on a direct-current voltage. The transfer voltage power supply applies a transfer voltage to the primary transfer member and the secondary transfer member. The control unit performs a first image quality improvement mode in which the frequency of the alternating-current voltage of the development voltage and a primary transfer current flowing between the image carrying member and the primary transfer member are simultaneously changed.

Inventors

  • Takahisa Nakaue
  • Ryosuke Kimura

Assignees

  • KYOCERA DOCUMENT SOLUTIONS INC.

Dates

Publication Date
20260505
Application Date
20240702
Priority Date
20230705

Claims (6)

  1. 1 . An image forming apparatus comprising: an image carrying member in which a photosensitive layer is formed on a surface; a charging device that charges the surface of the image carrying member; an exposure device that exposes the surface of the image carrying member charged by the charging device to form an electrostatic latent image in which charging is attenuated; a development device that includes a developer carrying member which carries a developer containing a toner, and supplies, to the image carrying member, the toner contained in the developer carried by the developer carrying member to develop the electrostatic latent image into a toner image; an intermediate transfer member on which the toner image formed on the image carrying member is sequentially primarily transferred; a primary transfer member that is pressed against the image carrying member through the intermediate transfer member; a secondary transfer member that secondarily transfers, on a recording medium, the toner image primarily transferred on the intermediate transfer member; a charging voltage power supply that applies a charging voltage to the charging device; a development voltage power supply that applies to the developer carrying member a development voltage in which an alternating-current voltage is superimposed on a direct-current voltage; a transfer voltage power supply that applies, to the primary transfer member and the secondary transfer member, a transfer voltage of a polarity opposite to the toner image; and a control unit that controls the charging voltage power supply, the development voltage power supply and the transfer voltage power supply; and an input unit that selects and sets, through operation by a user, one of a plurality of modes including the first image quality improvement mode in which a frequency of the alternating-current voltage of the development voltage and a primary transfer current flowing between the image carrying member and the primary transfer member are simultaneously changed, wherein the control unit performs the first image quality improvement mode when the first image quality improvement mode is set through operation of the input unit by the user, the user can, through operation of the input unit, select and input one of a plurality of differently set setting values of the frequency of the alternating-current voltage and the primary transfer current, and the control unit simultaneously changes the frequency of the alternating-current voltage and the primary transfer current based on the setting value input from the input unit by the user.
  2. 2 . The image forming apparatus according to claim 1 , further comprising: a humidity detection device that detects an absolute humidity around the development device, wherein the setting value is set such that the frequency of the alternating-current voltage is increased stepwise as the absolute humidity is increased.
  3. 3 . The image forming apparatus according to claim 2 , wherein the setting value is set such that a range of change of the frequency of the alternating-current voltage is smaller when a cumulative driving distance of the image carrying member is less than a predetermined distance than when the cumulative driving distance is equal to or greater than the predetermined distance.
  4. 4 . An image forming apparatus comprising: an image carrying member in which a photosensitive layer is formed on a surface; a charging device that charges the surface of the image carrying member; an exposure device that exposes the surface of the image carrying member charged by the charging device to form an electrostatic latent image in which charging is attenuated; a development device that includes a developer carrying member which carries a developer containing a toner, and supplies, to the image carrying member, the toner contained in the developer carried by the developer carrying member to develop the electrostatic latent image into a toner image; an intermediate transfer member on which the toner image formed on the image carrying member is sequentially primarily transferred; a primary transfer member that is pressed against the image carrying member through the intermediate transfer member; a secondary transfer member that secondarily transfers, on a recording medium, the toner image primarily transferred on the intermediate transfer member; a charging voltage power supply that applies a charging voltage to the charging device; a development voltage power supply that applies, to the developer carrying member, a development voltage in which an alternating-current voltage is superimposed on a direct-current voltage; a transfer voltage power supply that applies, to the primary transfer member and the secondary transfer member, a transfer voltage of a polarity opposite to the toner image; and a control unit that controls the charging voltage power supply, the development voltage power supply and the transfer voltage power supply; and an input unit that selects and sets, through operation by a user, one of a plurality of modes including the first image quality improvement mode in which a frequency of the alternating-current voltage of the development voltage and a primary transfer current flowing between the image carrying member and the primary transfer member are simultaneously changed, wherein the control unit performs the first image quality improvement mode when the first image quality improvement mode is set through operation of the input unit by the user, after the first image quality improvement mode was performed, the user can, through operation of the input unit, select and set a second image quality improvement mode in which the charging voltage is changed, and when the second image quality improvement mode is set through operation of the input unit by the user, the control unit performs the second image quality improvement mode after the first image quality improvement mode was performed.
  5. 5 . The image forming apparatus according to claim 4 , wherein, in the second image quality improvement mode, the user can select and input one of a plurality of differently set setting values of the charging voltage through operation of the input unit, and the control unit changes the charging voltage based on the setting values input from the input unit by the user.
  6. 6 . An image forming apparatus comprising: an image carrying member in which a photosensitive layer is formed on a surface; a charging device that charges the surface of the image carrying member; an exposure device that exposes the surface of the image carrying member charged by the charging device to form an electrostatic latent image in which charging is attenuated; a development device that includes a developer carrying member which carries a developer containing a toner and supplies, to the image carrying member, the toner contained in the developer carried by the developer carrying member to develop the electrostatic latent image into a toner image; an intermediate transfer member on which the toner image formed on the image carrying member is sequentially primarily transferred; a primary transfer member that is pressed against the image carrying member through the intermediate transfer member; a secondary transfer member that secondarily transfers, on a recording medium, the toner image primarily transferred on the intermediate transfer member; a charging voltage power supply that applies a charging voltage to the charging device; a development voltage power supply that applies to the developer carrying member a development voltage in which an alternating-current voltage is superimposed on a direct-current voltage; a transfer voltage power supply that applies, to the primary transfer member and the secondary transfer member, a transfer voltage of a polarity opposite to the toner image; and a control unit that controls the charging voltage power supply, the development voltage power supply and the transfer voltage power supply, an image density detection unit that detects a density of the toner image formed on the intermediate transfer member, wherein the control unit can perform a ghost detection mode in which the image density detection unit detects a density of a detection image formed on the intermediate transfer member to detect whether a drum ghost occurs, and based on a result of the ghost detection mode, the control unit performs a first image quality improvement mode in which a frequency of the alternating-current voltage of the development voltage and a primary transfer current flowing between the image carrying member and the primary transfer member are simultaneously changed, the detection image is a half image that is formed after one revolution of the image carrying member from formation of a solid image and includes a part which is a range of formation of the solid image, and the control unit determines the frequency of the alternating-current voltage and the primary transfer current based on a density difference ΔID between the part which is the range of formation of the solid image in the half image and a part therearound.

Description

INCORPORATION BY REFERENCE This application is based upon and claims the benefit of priority from the corresponding Japanese Patent Applications Nos. 2023-110647, filed on Jul. 5, 2023 and 2023-142113, filed on Sep. 1, 2023, the entire contents of which are incorporated herein by reference. BACKGROUND The present disclosure relates to image forming apparatuses, such as a copying machine, a printer, a facsimile and a multifunctional peripheral thereof, which include an image carrying member, and particularly relates to an image forming apparatus of an intermediate transfer system which transfers, on an intermediate transfer belt, a toner image formed on the image carrying member such as a photosensitive drum. Conventionally, an image forming apparatus of an intermediate transfer system is known which includes a seamless intermediate transfer belt that is turned in a predetermined direction and a plurality of image formation units that are provided along the intermediate transfer belt, and in which toner images of individual colors are sequentially superimposed by the image formation units on the intermediate transfer belt to be primarily transferred thereon, and thereafter the toner images are secondarily transferred by a secondary transfer roller on a recording medium such as a sheet. In the image forming apparatus of the intermediate transfer system, a primary transfer current flows into a photosensitive drum, and thus the surface potential of the photosensitive drum is changed. Specifically, the amount of primary transfer current flowing into a part (image part) where a toner is present is reduced, and thus the amount of primary transfer current flowing into a part (white part) where no toner is present is increased. In other words, the so-called drum ghost (historical development) is problematic in which the surface potential is changed depending on whether a toner is present to cause inconsistencies in density. SUMMARY An image forming apparatus according to a first aspect of the present disclosure includes an image carrying member, a charging device, a charging voltage power supply, an exposure device, a development device, a development voltage power supply, an intermediate transfer member, a primary transfer member, a secondary transfer member, a transfer voltage power supply and a control unit. In the image carrying member, a photosensitive layer is formed on a surface. The charging device charges the surface of the image carrying member. The exposure device exposes the surface of the image carrying member charged by the charging device to form an electrostatic latent image in which charging is attenuated. The development device includes a developer carrying member which carries a developer containing a toner, and supplies, to the image carrying member, the toner contained in the developer carried by the developer carrying member to develop the electrostatic latent image into a toner image. On the intermediate transfer member, the toner image formed on the image carrying member is sequentially primarily transferred. The primary transfer member is pressed against the image carrying member through the intermediate transfer member. The secondary transfer member secondarily transfers, on a recording medium, the toner image primarily transferred on the intermediate transfer member. The charging voltage power supply applies a charging voltage to the charging device. The development voltage power supply applies, to the developer carrying member, a development voltage in which an alternating-current voltage is superimposed on a direct-current voltage. The transfer voltage power supply applies, to the primary transfer member and the secondary transfer member, a transfer voltage of a polarity opposite to the toner image. The control unit controls the charging voltage power supply, the development voltage power supply and the transfer voltage power supply. The control unit performs a first image quality improvement mode in which the frequency of the alternating-current voltage of the development voltage and a primary transfer current flowing between the image carrying member and the primary transfer member are simultaneously changed. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration view of a color printer according to an embodiment of the present disclosure; FIG. 2 is an enlarged view of an area around an image formation unit shown in FIG. 1; FIG. 3 is a block diagram showing an example of a control path used in the color printer; FIG. 4 is a flowchart showing an example of control when a drum ghost is removed in a GS mode in the color printer in the first embodiment of the present disclosure; FIG. 5 is a plan view of the liquid crystal display unit of the color printer in the first embodiment and is a diagram showing a state where the GS mode is selected; FIG. 6 is a plan view of the liquid crystal display unit of the color printer in the first embodiment and is a diagram showing a state