Image forming apparatus that performs shading correction to maintain print position accuracy

1 . An image forming apparatus comprising:

an image forming unit configured to form an image on a sheet of a plurality of sheets based on received image data, form an adjustment image in an area of the sheet to be cut, and convey the sheet on a conveyance path;

a reading sensor configured to read the image on the sheet which passes a reading area of the conveyance path;

a reference member that is read by the reading sensor for performing a shading correction for the reading sensor;

a controller configured to:

switch operation of the image forming apparatus between a productivity priority mode and an image quality priority mode;

control a positional relationship between the reading sensor and the reference member to be a first positional relationship in a case where the reading sensor reads the image;

control the positional relationship between the reading sensor and the reference member to be a second positional relationship that is different from the first positional relationship in a case where the reading sensor reads the reference member;

control, in the productivity priority mode, in a case where an execution condition for executing reading of the reference member by the reading sensor is satisfied during a period in which both the image and the adjustment image are formed on the sheet of the plurality of sheets, the positional relationship between the reading sensor and the reference member to be the second positional relationship while continuing conveyance of the plurality of sheets including the sheet on which the image and the adjustment image have been formed to pass the reading area,

wherein the reading sensor and the reference member are arranged such that the positional relationship between the reading sensor and the reference member is switched from the first positional relationship to the second positional relationship by moving either the reference member or the reading sensor while continuing conveyance of the plurality of sheets on which the image and the adjustment image have been formed along a same conveyance path in both the first positional relationship and the second positional relationship; and

adjust, in the image quality priority mode, in the case where the execution condition for executing reading of the reference member by the reading sensor is satisfied during the period in which both the image and the adjustment image are formed on the sheet of the plurality of sheets, a timing for forming the adjustment image on the sheet and control the positional relationship between the reading sensor and the reference member to be the second positional relationship while continuing conveyance of the plurality of sheets to pass the reading area such that the sheet on which the image and the adjustment image have been formed passes the reading area after the shading correction has been performed.

2 . The image forming apparatus according to claim 1 ,

wherein a distance between the reading sensor and the reference member in the second positional relationship is shorter than a distance between the reading sensor and the reference member in the first positional relationship.

3 . The image forming apparatus according to claim 1 ,

wherein the reading sensor is positioned, in the first positional relationship, at a first position, and

wherein the reading sensor is positioned, in the second positional relationship, at a second position closer to the reference member than in the first position.

4 . The image forming apparatus according to claim 1 ,

wherein the reference member is positioned, in the first positional relationship, at a first position, and

wherein the reference member is positioned, in the second positional relationship, at a second position closer to the reading sensor than in the first position.

5 . The image forming apparatus according to claim 1 ,

wherein the shading correction is performed in a case where a condition regarding a number of sheets passing through a reading position is met.

6 . The image forming apparatus according to claim 1 ,

wherein the reading sensor includes a light source, and

wherein the shading correction is performed in a case where a condition regarding a lighting time of the light source is met.

7 . The image forming apparatus according to claim 1 ,

wherein the shading correction is performed in a case where a condition regarding a temperature of the reading sensor is met.

8 . The image forming apparatus according to claim 1 ,

wherein the controller generates an image forming condition to control quality of an image to be formed by the image forming unit based on a result of the adjustment image read by the reading sensor.

9 . The image forming apparatus according to claim 8 ,

wherein the image forming condition comprises a condition to adjust a position of an image to be formed on a sheet.

10 . The image forming apparatus according to claim 8 ,

wherein the adjustment image is formed on four corners of the sheet.

11 . The image forming apparatus according to claim 1 ,

wherein color of the reference member is white.

12 . The image forming apparatus according to claim 1 ,

wherein the image forming unit is further configured to form a test image that is used to control image quality;

wherein the test image is read by the reading sensor; and

wherein the controller is configured to control conveyance of a sheet on which the test image has been formed so that the sheet on which the test image has been formed does not pass through the reading area at a timing when the reading sensor reads the reference member.

13 . The image forming apparatus according to claim 1 ,

wherein the image forming unit is further configured to form a test image that is used to control image quality;

wherein the test image is read by the reading sensor; and

wherein the controller is configured to control forming of the test image by the image forming unit so that the sheet on which the test image has been formed does not pass through the reading area at a timing when the reading sensor reads the reference member.

14 . The image forming apparatus according to claim 1 ,

wherein the reading sensor is a line sensor having a plurality of light receiving elements aligned in a direction orthogonal to a conveyance direction in which the sheet is conveyed.

15 . The image forming apparatus according to claim 1 ,

wherein the reading sensor comprises a plurality of light receiving elements in a direction orthogonal to a conveyance direction in which the sheet is conveyed, and

wherein the controller is configured to:

perform reading of the reference member by moving the reading sensor in the conveyance direction so that the reading sensor and the reference member face each other; or

perform reading of the reference member by moving the reference member in the conveyance direction so that the reading sensor and the reference member face each other.

16 . The image forming apparatus according to claim 1 ,

wherein the controller is configured to control, in a case where the reading of the reference member by the reading sensor is completed in the second positional relationship, the reference member to be in the first positional relationship while continuing conveyance of the plurality of sheets on which the image and the adjustment image have been formed to pass the reading area.

17 . The image forming apparatus according to claim 1 , wherein the adjustment image includes one of an image for detecting geometric characteristics, an image for detecting image density, or an image for detecting color misregistration.

18 . The image forming apparatus according to claim 1 , wherein, in a case where the image forming unit is configured to form images, based on the received image data, on both sides of the sheet, the adjustment image is also formed on both sides of the sheet.

19 . The image forming apparatus according to claim 1 , wherein the reading sensor is configured to not read the adjustment image during the period in which both the image and the adjustment image are formed on the plurality of sheets and the execution condition for executing reading of the reference member by the reading sensor is satisfied.