Patent ID: 7528859

Claim:
An electrophotographic image forming apparatus, comprising: an electrophotographic photosensitive drum that is rotatably disposed and includes a light emitting element matrix layer including multiple light emitting pixel portions, and a photoconductive layer in which a latent image is formed by light emission of the light emitting pixel portions; a charging device, which charges the electrophotographic photosensitive drum in a charging position; a developing device, which develops the latent image with a developer in a developing position; a rotary portion, which rotates with the electrophotographic photosensitive drum and has multiple phase detecting patterns of the electrophotographic photosensitive drum, an angle formed between adjacent phase detecting patterns of the multiple phase detecting patterns with respect to a rotation center of the rotary portion being equal to or less than an angle formed between the charging position and the developing position with respect to a rotation center of the electrophotographic photosensitive drum; and a control portion that controls light emission of the multiple light emitting pixel portions and changes an interval between a timing for light emission of a first light emitting pixel portion among the multiple light emitting pixel portions and a timing for light emission of a second light emitting pixel portion which is positioned at a downstream side of the first light emitting pixel portion in a rotation direction of the electrophotographic photosensitive drum during a formation of the latent image so as to correspond to a single transfer material, based on a detection result of the multiple phase detecting patterns.