US-20260126740-A1 - IMAGE FORMING APPARATUS

US20260126740A1US 20260126740 A1US20260126740 A1US 20260126740A1US-20260126740-A1

Abstract

In an image forming apparatus, a developing roller accommodating unit includes a developing roller and has an opening of a length smaller than a length of the developing roller in a direction of a rotation axis of the developing roller. A replenishment operation determination unit determines to perform a replenishment operation if a predetermined condition is satisfied. A pixel number determination unit determines, based on information on a number of pixels in an image to be formed, a number of pixels in both a first area and a second area obtained by dividing an image formation area. The predetermined condition is at least one of that the first number of pixels in the first area is greater than a first threshold and that the second number of pixels in the second area is greater than a second threshold different from the first threshold.

Inventors

Shinsuke Kobayashi
Akimichi Suzuki
Masashi Tanaka
Hikaru Osada
Jun Hara
Akisato Sakaki

Assignees

CANON KABUSHIKI KAISHA

Dates

Publication Date: 20260507
Application Date: 20251029
Priority Date: 20241106

Claims (17)

1 . An image forming apparatus comprising: a developing agent accommodating unit configured to accommodate a developing agent; a developing roller accommodating unit including a developing roller that develops an electrostatic latent image formed on a photosensitive member, and having an opening of a length smaller than a length of the developing roller in a direction of an axis of rotation of the developing roller, the developing roller accommodating unit configured to accommodate the developing agent supplied from the developing agent accommodating unit through the opening; an image formation control unit configured to receive a print job including information on a number of pixels in an image to be formed on a recording material and execute an image formation operation based on the print job; a replenishment operation determination unit configured to determine to perform a replenishment operation in a case where a predetermined condition is satisfied, the replenishment operation being an operation of supplying the developing agent from the developing agent accommodating unit to the developing roller accommodating unit; and a pixel number determination unit configured to determine, based on the information, a number of pixels in both a first area and a second area, each being a part of an image formation area of the recording material and being obtained by dividing the image formation area in the direction of the axis of rotation, wherein in a case where the number of pixels in the first area determined by the pixel number determination unit is taken as a first number of pixels and the number of pixels in the second area determined by the pixel number determination unit is taken as a second number of pixels, the predetermined condition is at least one of that the first number of pixels is greater than a first threshold and that the second number of pixels is greater than a second threshold different from the first threshold.
2 . The image forming apparatus according to claim 1 , wherein each of the first number of pixels and the second number of pixels is an integrated value of numbers of pixels on a plurality of recording materials on which images are formed based on the print job.
3 . The image forming apparatus according to claim 1 , wherein the second area is an area closer to the opening than the first area in the direction of the axis of rotation, and the first threshold is set to a value lower than the second threshold.
4 . The image forming apparatus according to claim 1 , wherein a threshold is set for each of a plurality of areas obtained by dividing the image formation area in the direction of the axis of rotation, the plurality of areas including the first area and the second area, and the replenishment operation determination unit determines to perform the replenishment operation in a case where the number of pixels corresponding to at least one area among the plurality of areas exceeds the threshold set for the area.
5 . The image forming apparatus according to claim 4 , wherein the threshold is set to a lower value as a distance of the corresponding area, among the plurality of areas, from the opening in the direction of the axis of rotation increases.
6 . The image forming apparatus according to claim 4 , wherein a size of each of the plurality of areas is determined according to a size of the opening.
7 . The image forming apparatus according to claim 6 , wherein the threshold corresponding to each of the plurality of areas is set in accordance with a size of the corresponding area.
8 . The image forming apparatus according to claim 1 , wherein the pixel number determination unit determines, based on the information, a number of pixels to be developed by the developing agent in each of the first area and the second area.
9 . The image forming apparatus according to claim 1 , wherein the developing roller accommodating unit has a plurality of openings for supplying the developing agent from the developing agent accommodating unit, and the developing roller accommodating unit is configured such that a length of each of the openings in the direction of the axis rotation is shorter as a number of the openings provided in the developing roller accommodating unit increases.
10 . The image forming apparatus according to claim 1 , further comprising: a rotary that includes the developing roller accommodating unit and to and from which the developing agent accommodating unit can be attached and detached, wherein the replenishment operation includes an operation of rotating the rotary by one rotation.
11 . The image forming apparatus according to claim 10 , wherein the replenishment operation includes an operation of rotating the rotary to assume an orientation in which developing agent that has fallen within the developing agent accommodating unit due to gravity can move into the developing roller accommodating unit through the opening.
12 . The image forming apparatus according to claim 11 , wherein the replenishment operation is an operation of rotating the rotary by one rotation after the rotary has assumed the orientation.
13 . The image forming apparatus according to claim 1 , wherein the developing agent accommodating unit includes a screw member capable of rotating, the screw member being configured to convey the developing agent within the developing agent accommodating unit to replenish the developing roller accommodating unit with the developing agent through the opening, and the replenishment operation is an operation of rotating the screw member or increasing a rotation speed of the screw member.
14 . The image forming apparatus according to claim 1 , wherein the developing roller accommodating unit includes a screw member capable of rotating, the screw member being configured to convey the developing agent, with which the developing agent accommodating unit has been replenished through the opening, within the developing roller accommodating unit for supply to the developing roller accommodating unit, and the replenishment operation is an operation of rotating the screw member or increasing a rotation speed of the screw member.
15 . The image forming apparatus according to claim 14 , wherein each of the first number of pixels and the second number of pixels is an integrated value of numbers of pixels on a plurality of recording materials on which images are formed based on the print job, when the integrated value corresponding to the first area reaches the first threshold, the replenishment operation determination unit determines to increase the rotation speed of the screw member, and when the integrated value then reaches a third threshold greater than the first threshold, the replenishment operation determination unit determines to further increase the rotation speed of the screw member, and when the integrated value corresponding to the second area reaches the second threshold, the replenishment operation determination unit determines to increase the rotation speed of the screw member, and when the integrated value then reaches a fourth threshold greater than the second threshold, the replenishment operation determination unit determines to further increase the rotation speed of the screw member.
16 . The image forming apparatus according to claim 2 , wherein in a case where the replenishment operation is performed, the pixel number determination unit resets the integrated value to 0.
17 . The image forming apparatus according to claim 2 , wherein in a case where execution of the print job is completed, the pixel number determination unit resets the integrated value to 0.

Description

BACKGROUND Field of the Technology The present disclosure relates to an image forming apparatus. Description of the Related Art In an electrophotographic image forming apparatus, to prevent density unevenness from arising in a toner image formed by developing an electrostatic latent image using toner, the toner is supplied uniformly to the entirety of a developing member (a developing roller). Japanese Patent Laid-Open No. 2010-66582 discloses a configuration in which the rotation speed of a toner conveyance member is controlled on the basis of a result of detecting toner density in order to supply toner to a developing member uniformly. SUMMARY However, with this past technique, if a replenishment opening is provided in a partial area in the lengthwise direction of the developing container, an image with blank patches may arise due to insufficient toner being supplied to the developing member. The present disclosure reduces the occurrence of images having blank patches in an image forming apparatus in which a replenishment opening is provided in a partial area in the lengthwise direction of a developing container (a developing roller accommodating unit). According to one aspect of the present disclosure, there is provided an image forming apparatus comprising: a developing agent accommodating unit configured to accommodate a developing agent; a developing roller accommodating unit including a developing roller that develops an electrostatic latent image formed on a photosensitive member, and having an opening of a length smaller than a length of the developing roller in a direction of an axis of rotation of the developing roller, the developing roller accommodating unit configured to accommodate the developing agent supplied from the developing agent accommodating unit through the opening; an image formation control unit configured to receive a print job including information on a number of pixels in an image to be formed on a recording material and execute an image formation operation based on the print job; a replenishment operation determination unit configured to determine to perform a replenishment operation in a case where a predetermined condition is satisfied, the replenishment operation being an operation of supplying the developing agent from the developing agent accommodating unit to the developing roller accommodating unit; and a pixel number determination unit configured to determine, based on the information, a number of pixels in both a first area and a second area, each being a part of an image formation area of the recording material and being obtained by dividing the image formation area in the direction of the axis of rotation, wherein in a case where the number of pixels in the first area determined by the pixel number determination unit is taken as a first number of pixels and the number of pixels in the second area determined by the pixel number determination unit is taken as a second number of pixels, the predetermined condition is at least one of that the first number of pixels is greater than a first threshold and that the second number of pixels is greater than a second threshold different from the first threshold. Features of the present disclosure will become apparent from the following description of embodiments with reference to the attached drawings. The following description of embodiments are described by way of example. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present disclosure, and together with the description, serve to explain the principles of the embodiments. FIG. 1 is a cross-sectional view illustrating an example of the hardware configuration of an image forming apparatus. FIGS. 2A and 2B illustrate an example of a standby orientation and a replenishment orientation of a rotary body. FIG. 3 illustrates an example of the motor configuration of the image forming apparatus. FIG. 4A is a cross-sectional view illustrating an example of the configuration of a toner cartridge and a developing unit. FIG. 4B illustrates an example of the arrangement of a replenishment opening. FIGS. 5A and 5B illustrate examples of toner states within the developing unit. FIG. 6 is a block diagram illustrating an example of the control configuration of the image forming apparatus. FIGS. 7A to 7C illustrate an example of a method for dividing an image area. FIGS. 8A to 8C illustrate an example of the arrangement of replenishment openings (a second embodiment). FIGS. 9A and 9B illustrate an example of a method for dividing an image area (the second embodiment). FIG. 10 is a cross-sectional view illustrating an example of the hardware configuration of an image forming apparatus (a third embodiment). FIG. 11 is a cross-sectional view illustrating an example of the configuration of a developing device (the third embodiment). FIGS. 12A and 12B illustrate examples of toner states