Method of detecting a phase difference of image bearing members and an image forming apparatus using the method

An image forming apparatus, comprising:

• an image transferring member configured to receive and transfer a toner image;
• a plurality of image bearing members configured to bear respective toner images on respective surfaces thereof, and comprising:
• a reference image bearing member configured to carry and transfer a reference toner mark and a reference image pattern onto the image transferring member;
• and
• corresponding image bearing members configured to carry and transfer a corresponding image pattern onto the image transferring member;
• a plurality of detectors configured to detect the reference image pattern and the corresponding image pattern;
• and
• a controller configured to control the reference image bearing member and each corresponding image bearing member to have a positional relation for which a sum of an elapsed time differences between the reference image pattern and the corresponding image pattern is minimum.

An image forming apparatus, comprising:

• means for transferring a toner image;
• means for carrying respective toner images, comprising:
• first means for forming a reference toner mark and a reference image pattern onto the means for transferring;
• and
• second means for forming a corresponding image pattern onto the means for transferring;
• means for detecting the reference image pattern and the corresponding image pattern;
• and
• means for controlling the first and second means for forming to have a positional relation for which a sum of an elapsed time differences between the reference image pattern and the corresponding image pattern is minimum.

An image forming apparatus, comprising:

• an image transferring member configured to receive and transfer a toner image;
• a plurality of image bearing members configured to bear respective toner images on respective surfaces thereof, and comprising:
• a reference image bearing member configured to carry and transfer a reference toner mark and a reference image pattern onto the image transferring member;
• and
• corresponding image bearing members configured to carry and transfer a corresponding image pattern onto the image transferring member;
• a plurality of drive gears configured to drive the plurality of image bearing members;
• a plurality of detectors configured to detect a position of a marking material formed on one of each image bearing member and each drive gear so that a position of each image bearing member is detected;
• and
• a controller configured to control the reference image bearing member and each corresponding image bearing member to have a positional relation for which a sum of an elapsed time differences between the reference image pattern and the corresponding image pattern is minimum.

An image forming apparatus, comprising:

• means for transferring a toner image;
• means for carrying respective toner images, comprising:
• first means for forming a reference toner mark and a reference image pattern onto the means for transferring;
• and
• second means for forming a corresponding image pattern onto the means for transferring;
• means for driving the means for carrying;
• means for detecting a position of a marking material formed on one of the means for carrying and the means for driving so that a position of the means for carrying is detected;
• and
• means for controlling the first and second means for forming to have a positional relation for which a sum of an elapsed time differences between the reference image pattern and the corresponding image pattern is minimum.