Image forming apparatus to correct timing of image formation

A method for an image forming apparatus having a plurality of image bearing members, an intermediate transfer member, and a plurality of image forming units respectively corresponding to the plurality of image bearing members and each configured to form an image on the corresponding image bearing member and to transfer the image formed on the corresponding image bearing member to the intermediate transfer member, the method comprising:

• conveying a recording material;
• transferring, via a transfer unit, the image formed on the intermediate transfer member to the conveyed recording material;
• detecting image patterns for positional deviation detection respectively formed on the intermediate transfer member by the plurality of image forming units;
• and
• performing control by switching between a first mode, which determines, with a first image forming unit among the plurality of image forming units used as a reference, timing of image formation performed by a second image forming unit different from the first image forming unit, and a second mode, which determines timing of image formation performed by the second image forming unit with the second image forming unit used as a reference,
• wherein, based on timings at which, in the first mode, the image pattern formed on the intermediate transfer member by the first image forming unit and the image pattern formed on the intermediate transfer member by the second image forming unit are respectively detected, performing control, in the second mode, includes correcting timing of image formation performed by the second image forming unit or correcting timing at which the recording material is conveyed to the transfer unit.

A non-transitory computer-readable storage medium storing a program to cause an image forming apparatus to perform a method, wherein the image forming apparatus includes a plurality of image bearing members, an intermediate transfer member, and a plurality of image forming units respectively corresponding to the plurality of image bearing members and each configured to form an image on the corresponding image bearing member and to transfer the image formed on the corresponding image bearing member to the intermediate transfer member, the method comprising:

• conveying a recording material;
• transferring, via a transfer unit, the image formed on the intermediate transfer member to the conveyed recording material;
• detecting image patterns for positional deviation detection respectively formed on the intermediate transfer member by the plurality of image forming units;
• and
• performing control by switching between a first mode, which determines, with a first image forming unit among the plurality of image forming units used as a reference, timing of image formation performed by a second image forming unit different from the first image forming unit, and a second mode, which determines timing of image formation performed by the second image forming unit with the second image forming unit used as a reference,
• wherein, based on timings at which, in the first mode, the image pattern formed on the intermediate transfer member by the first image forming unit and the image pattern formed on the intermediate transfer member by the second image forming unit are respectively detected, performing control, in the second mode, includes correcting timing of image formation performed by the second image forming unit or correcting timing at which the recording material is conveyed to the transfer unit.