Color image forming apparatus

Patent metadata

Field	Value
Publication number	US-9310705-B2
Application number	US-201313945466-A
Country	US
Kind code	B2
Filing date	Jul 18, 2013
Priority date	Aug 2, 2012
Publication date	Apr 12, 2016
Grant date	Apr 12, 2016

Abstract

A color image forming apparatus includes an image forming unit configured to form misregistration detection patterns, a transfer member on which the misregistration detection patterns are transferred, a plurality of detection units configured to detect the misregistration detection patterns transferred onto the transfer member, a calculation unit which calculates misregistration values from detection results detected by the plurality of detection units, and a control unit which controls an image forming condition by the image forming unit based on the misregistration values. The image forming unit forms first and second marks at different positions in a direction perpendicular to a moving direction of the transfer member as the misregistration detection patterns, and the calculation unit calculates the misregistration values based on detection results of the first and second marks.

First claim

What is claimed is:

1. A color image forming apparatus, which comprises a plurality of image forming units, corresponding to respective colors, for forming images on an intermediate transfer member or a conveyed printing material, in a tandem system, comprising:
a control unit configured to control the plurality of image forming units to form misregistration detection patterns on the intermediate transfer member, the printing material, or a conveyance member which conveys the printing material;
a first detection unit and a second detection unit configured to detect the formed misregistration detection patterns, said first detection unit and said second detection unit being arranged to be juxtaposed in a direction perpendicular to a moving direction of the intermediate transfer member or in a direction perpendicular to a conveyance direction of the printing material;
a calculation unit configured to calculate misregistration values from detection results of the misregistration detection patterns by said first detection unit and said second detection unit; and
a correction unit configured to correct image forming conditions by the plurality of image forming units using the calculated misregistration values,
wherein the misregistration detection patterns include:
a linear first reference mark and a first detection mark to be detected by said first detection unit; and
a linear second reference mark and a second detection mark to be detected by said second detection unit,
the linear first reference mark and the linear second reference mark make substantially 90° as an angle with the moving direction of the intermediate transfer member or the conveyance direction of the printing material,
an angle the second detection mark makes with the moving direction of the intermediate transfer member or the conveyance direction of the printing material is smaller than the angle made by the linear first reference mark,
an angle the first detection mark makes with the moving direction of the intermediate transfer member or the conveyance direction of the printing material is smaller than the angle made by the linear second reference mark,
the linear first reference mark and the second detection mark are arranged so that a detection timing of the linear first reference mark by said first detection unit and a detection timing of the second detection mark by said second detection unit are concurrent timings when no misregistration occurs on the intermediate transfer member, the printing material, or the conveyance member, and
the linear second reference mark and the first detection mark are arranged so that a detection timing of the first detection mark by said first detection unit and a detection timing of the linear second reference mark by said second detection unit are concurrent timings when no misregistration occurs on the intermediate transfer member, the printing material, or the conveyance member.

2. The apparatus according to claim 1 , wherein letting θ1 be the angle the first detection mark makes with the moving direction of the intermediate transfer member or the conveyance direction of the printing material, and
letting θ2 be the angle the second detection mark makes with the moving direction of the intermediate transfer member or the conveyance direction of the printing material,
when said calculation unit calculates a difference between the detection timings of the linear first reference mark and the second detection mark, said calculation unit multiplies the difference by cot(90°-θ2) as a coefficient, and
when said calculation unit calculates a difference between the detection timings of the linear second reference mark and the first detection mark, said calculation unit multiplies the difference by cot(90°-θ1) as a coefficient.

3. The apparatus according to claim 1 , wherein said calculation unit calculates a tilt misregistration value as a tilt with respect to the moving direction of the intermediate transfer member or the conveyance direction of the printing material based on a difference between a detection timing of the linear first reference mark by said first detection unit and a detection timing of the second detection mark by said second detection unit and a difference between a detection timing of the first detection mark by said first detection unit and a detection timing of the linear second reference mark by said second detection unit, and
the misregistration values are corrected according to the tilt misregistration value.

4. The apparatus according to claim 3 , wherein when the angle the first detection mark makes with the moving direction of the intermediate transfer member or the conveyance direction of the printing material and the angle the second detection mark makes with the moving direction of the intermediate transfer member or the conveyance direction of the printing material have the same sign, said calculation unit corrects the total magnification displacement value of the misregistration values according to the tilt misregistration value.

5. The apparatus according to claim 3 , wherein when the angle the first detection mark makes with the moving direction of the intermediate transfer member or the conveyance direction of the printing material and the angle the second detection mark makes with the moving direction of the intermediate transfer member or the conveyance direction of the printing material have different signs, said calculation unit corrects the write start position misregistration value of the misregistration values according to the tilt misregistration value.

6. The apparatus according to claim 1 , wherein the angle the first detection mark makes with the moving direction of the intermediate transfer member or the conveyance direction of the printing material is 45°, and
the angle the second detection mark makes with the moving direction of the intermediate transfer member or the conveyance direction of the printing material is 45°.

7. The apparatus according to claim 1 , wherein the misregistration values include a write start position misregistration value indicating a misregistration value of a write start position and a total magnification displacement value indicating a misregistration value of an output magnification in the direction perpendicular to the moving direction of the intermediate transfer member or the direction perpendicular to the conveyance direction of the printing material,
said calculation unit calculates the write start position misregistration value from an average value of a difference between detection timings of the linear first reference mark and the second detection mark and a difference between detection timings of the linear second reference mark and the first detection mark, and
said calculation unit calculates the total magnification displacement value from a difference between the difference between detection timings of the linear first reference mark and the second detection mark and the difference between the detection timings of the linear second reference mark and the first detection mark.

8. A color image forming apparatus, which comprises a plurality of image forming units, corresponding to respective colors, for forming images on an intermediate transfer member or a conveyed printing material, in a tandem system, comprising:
a control unit configured to control the plurality of image forming units to form misregistration detection patterns on the intermediate transfer member, the printing material, or a conveyance member which conveys the printing material;
a first detection unit and a second detection unit configured to detect the misregistration detection patterns formed on the intermediate transfer member, the printing material, or the conveyance member which conveys

Assignees

• Canon Kk

Inventors

• Nakashima Satoshi

Classifications

• H04N1/506 Primary

  Reproducing the colour component signals picture-sequentially, e.g. with reproducing heads spaced apart from one another in the subscanning direction · CPC title

• H04N1/00037

  Detecting, i.e. determining the occurrence of a predetermined state (H04N1/00031 takes precedence) · CPC title

• G03G15/0131 Primary

  for transferring a pattern to a second base · CPC title

• H04N1/00023

  Colour systems · CPC title

• G03G2215/0158

  Colour registration · CPC title