Image forming apparatus with controllable velocity ratio between image and developer bearing members

• US 10,018,951 B2
• Filed: 03/29/2017
• Issued: 07/10/2018
• Est. Priority Date: 03/31/2016
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Saito, Tohru, Uchiyama, Akihiko, Nakahara, Hisashi, Shindo, Go
• Primary Examiner(s): Brase, Sandra
• Application Number:
  US15/472,572
• Publication Number:
  US 20170285546A1
• Time in Patent Office: 468 Days
• CPC Class Codes: G03G 15/0806 on a donor element, e.g. belt, roller complete developer unit G03G15/0896
• CPC Class Codes: G03G 15/5008 Driving control for rotary photosensitive medium, e.g. speed control, stop position control
• CPC Class Codes: G03G 15/5062 by measuring the characteristics of an image on the copy material
• CPC Class Codes: G03G 15/5087 for receiving image data
• CPC Class Codes: G03G 15/55 Self-diagnostics; Malfunction or lifetime display
• CPC Class Codes: G03G 2221/1657 transmitting mechanical drive power

Abstract

A control portion has a conversion portion that converts image data to be used for forming a recorded image by using either a first conversion condition which has been set such as to obtain a first gradation characteristic in the image to be formed on the recording material when a first image forming operation is executed or a second conversion condition which has been set such as to obtain a second gradation characteristic, which is different from the first gradation characteristic, in the image when a second image forming operation is executed, a peripheral velocity ratio between an image bearing member and a developer bearing member being larger during the second image forming operation than during the first image forming operation, and enables the first image forming operation or the second image forming operation to be performed on the basis of converted image data.

Claims

1. An image forming apparatus comprising:

an image bearing member on which an electrostatic image is formed;

a developer bearing member that develops the electrostatic image, which has been formed on the image bearing member, with a developer; and

a control portion that controls the image bearing member and the developer bearing member so as to enable execution of a first image forming operation by which a recorded image is formed by rotating the image bearing member and the developer bearing member at a first peripheral velocity ratio and a second image forming operation by which a recorded image is formed by rotating the image bearing member and the developer bearing member at a second peripheral velocity ratio which is greater than the first peripheral velocity ratio, where the peripheral velocity ratio is defined as a ratio of a peripheral velocity of the developer bearing member to a peripheral velocity of the image bearing member, wherein

the control portion;

has a conversion portion that converts image data, which are used for forming the recorded image, by using either a first conversion condition which has been set so as to obtain a first gradation characteristic in the recorded image when the first image forming operation is executed or a second conversion condition which has been set so as to obtain a second gradation characteristic, which is different from the first gradation characteristic, in the recorded image when the second image forming operation is executed, and

enables the first image forming operation or the second image forming operation to be performed on the basis of image data converted by the conversion portion.

2. The image forming apparatus according to claim 1, wherein the second gradation characteristic is a gradation characteristic which is the same as the first gradation characteristic in a first density region in the recorded image and is a gradation characteristic such that a density increase rate gradually increases in a second density region where density is higher than in the first density region.

3. The image forming apparatus according to claim 1, wherein in the first gradation characteristic, a density increase rate is constant over the entire density range in the recorded image.

4. The image forming apparatus according to claim 1, wherein

the control portion executes the first image forming operation when only dot data with a density less than a predetermined threshold are included in the image data to be converted in the conversion portion;

and

the conversion portion converts the image data by using the first conversion condition during the first image forming operation.

5. The image forming apparatus according to claim 4, wherein

the control portion executes the second image forming operation when dot data with a density of at least the predetermined threshold are included in the image data to be converted in the conversion portion;

and

the conversion portion converts the image data by using the second conversion condition during the second image forming operation.

6. The image forming apparatus according to claim 5, wherein

the execution of either of the first image forming operation and the second image forming operation is designatable.

7. The image forming apparatus according to claim 6, wherein

the control portion executes the first image forming operation when only dot data with a density less than the predetermined threshold are included in the image data, even when the execution of the second image forming operation is designated.

8. The image forming apparatus according to claim 1, wherein

the conversion portion converts the image data by gamma correction.

9. The image forming apparatus according to claim 1, wherein a laid-on level of the developer per unit area of the recording material in the recorded image in the second image forming operation is greater than the laid-on level in the first image forming operation.

10. The image forming apparatus according to claim 1, wherein a peripheral velocity of the image bearing member in the second image forming operation is lower than the peripheral velocity of the image bearing member in the first image forming operation.

11. The image forming apparatus according to claim 1, wherein the second peripheral velocity ratio is set such that a laid-on level of the developer per unit area of the recording material in the recorded image at the second peripheral velocity ratio is larger than that at the first peripheral velocity ratio.

12. The image forming apparatus according to claim 1, further comprising

an exposure portion for exposing a surface of the image bearing member to form an electrostatic image on the surface;

a transfer portion for transferring a developer image borne by the image bearing member to the recording material; and

a fixing portion for fixing the developer image to the recording material.

13. An image forming apparatus comprising:

an image bearing member on which an electrostatic image is formed;

a developer bearing member that develops the electrostatic image, which has been formed on the image bearing member, with a developer; and

a control portion that controls the image bearing member and the developer bearing member so as to enable execution of a first image forming operation by which a recorded image is formed by rotating the image bearing member and the developer bearing member at a first peripheral velocity ratio and a second image forming operation by which a recorded image is formed by rotating the image bearing member and the developer bearing member at a second peripheral velocity ratio which is greater than the first peripheral velocity ratio, where the peripheral velocity ratio is defined as a ratio of a peripheral velocity of the developer bearing member to a peripheral velocity of the image bearing member, wherein

the control portion;

has a conversion portion that converts image data, which are used for forming the recorded image, by using either a first conversion condition for outputting the recorded image in a first color reproduction range when the first image forming operation is executed or a second conversion condition for outputting the recorded image in a second color reproduction range, which is wider than the first color reproduction range, when the second image forming operation is executed, and

enables the first image forming operation or the second image forming operation to be performed on the basis of image data converted by the conversion portion.

14. The image forming apparatus according to claim 13, wherein

the conversion of the image data performed by the conversion portion is a color matching conversion for matching tinges between an image displayed by an image display device that displays an image on the basis of image data before the conversion, and an image formed on a recording material on the basis of image data after the conversion.

15. The image forming apparatus according to claim 13, wherein a laid-on level of the developer per unit area of the recording material in the recorded image in the second image forming operation is greater than the laid-on level in the first image forming operation.

16. The image forming apparatus according to claim 13, wherein a peripheral velocity of the image bearing member in the second image forming operation is lower than the peripheral velocity of the image bearing member in the first image forming operation.

17. The image forming apparatus according to claim 13, wherein the second peripheral velocity ratio is set such that a laid-on level of the developer per unit area of the recording material in the recorded image at the second peripheral velocity ratio is larger than that at the first peripheral velocity ratio.

18. The image forming apparatus according to claim 13, further comprising

an exposure portion for exposing a surface of the image bearing member to form an electrostatic image on the surface;

a transfer portion for transferring a developer image borne by the image bearing member to the recording material; and

a fixing portion for fixing the developer image to the recording material.