Color image forming apparatus and image forming method

A color image forming apparatus comprising:

• an image forming section which forms an image based on image information on an image carrier provided in the image forming section;
• a detection section which detects a print mark for color misalignment correction formed on the image carrier by the image forming section, and outputs print mark detection information;
• and
• a control section for executing color misalignment correction control based on the print mark detection information outputted from the detection section,
• wherein operations of forming a print mark for color misalignment correction onto an image boundary area of the image carrier, detecting the print mark, and judging whether or not to execute the color misalignment correction based a result of the print mark detection, are assumed to be operations of a correction judgment mode, wherein the image boundary area, is an area on the image carrier between an image area of a page and an image area of the next page, images of both the pages being formed on the image carrier based on the image information,
• wherein, in the correction judgment mode, the control section obtains a trend of a color misalignment amount of the second print mark by statistically processing data of the result of the print mark detection, calculates an execution timing of color misalignment correction and a color misalignment correction amount base on the obtained trend, and executes the color misalignment correction based on the calculated execution timing and the calculated color misalignment correction amount.

An image forming method comprising:

• forming an image based on image information on an image carrier;
• detecting a print mark for color misalignment correction formed on the image carrier, and outputting print mark detection information;
• obtaining, in a correction judgment mode, a trend of a color misalignment amount of the second print mark by statistically processing data of the result of the second print mark detection, and calculating an execution timing of color misalignment correction base on the obtained trend;
• and
• executing a color misalignment correction mode at the calculated execution timing,
• wherein operations of stopping an image forming process to form an image based on the image information onto the image carrier, executing an image forming process to form a first print mark for color misalignment correction onto the image carrier, detecting the first print mark, and executing the color misalignment correction based on a detection result of the first print mark are assumed to be operations of the color misalignment correction mode, and
• operations of forming a second print mark for color misalignment correction onto an image boundary area of the image carrier, detecting the second print mark, and judging whether or not to execute the color misalignment correction mode based a result of the second print mark detection, are assumed to be operations of the correction judgment mode, wherein the image boundary area, is an area on the image carrier between an image area of a page and an image area of the next page, images of both the pages being formed on the image carrier based on the image information.

An image forming method comprising:

• forming an image based on image information on an image carrier;
• detecting a print mark for color misalignment correction formed on the image carrier, and outputting print mark detection information;
• obtaining, in a correction judgment mode, a trend of a color misalignment amount of the second print mark by statistically processing data of the result of the print mark detection, and calculating an execution timing of color misalignment correction and a color misalignment correction amount base on the obtained trend;
• and
• executing the color misalignment correction based on the calculated execution timing and the calculated color misalignment correction amount,
• wherein operations of forming a print mark for color misalignment correction onto an image boundary area of the image carrier, detecting the print mark, and judging whether or not to execute the color misalignment correction based on a result of the print mark detection, are assumed to be operations of the correction judgment mode, wherein the image boundary area, is an area on the image carrier between an image area of a page and an image area of the next page, images of both the pages being formed on the image carrier based on the image information.