Printing apparatus

A printing apparatus comprising:

• a belt conveying mechanism having a belt by means of which recording paper is conveyed at a certain speed;
• a plurality of electrostatic recording units arranged in a direction in which said recording paper is conveyed by means of said belt, for forming latent images in conformity to image data onto rotating photosensitive drums, to develop them with toner prior to the transfer for each color onto the recording paper lying on said belt;
• photosensitive drums each having a rotation identifying section indicating rotational positions;
• a plurality of drum position sensors for detecting rotational positions of said plurality of photosensitive drums;
• and
• a drum phase correction unit for correcting to set rotational phases of said photosensitive drums to predetermined phases in such a manner that rotational positions of said photosensitive drums have a specific relationship with reference to the rotational positions detected by said plurality of drum position sensors, as expressed in the following formula on the assumption of an interval L between the drums and a drum diameter D:
• (L mod 2.pi.D)/(D2).