Patent ID: 8902271

Claim:
An image forming apparatus comprising: an image forming unit including a photosensitive member, a rotatable polygon mirror, and a light source configured to irradiate the polygon mirror with light, the image forming unit being configured to irradiate the photosensitive member with the light reflected by the polygon mirror so as to form a latent image on the photosensitive member and to perform image formation based on the latent image; a determination unit configured to determine whether or not the polygon mirror has converged at a number of rotations that allows the image formation to be performed, wherein the image forming unit starts the image formation based on the determination unit determining that the polygon mirror has converged at the number of rotations that allows the image formation to be performed, and wherein the determination unit is capable of detecting a first timing and a second timing and determines that the polygon mirror has converged at the number of rotations that allows the image formation to be performed based on an earlier one of the first timing and the second timing, the first timing corresponding to a timing at which a preset first period of time has elapsed after a number of rotations of the polygon mirror has reached a first number of rotations, the second timing corresponding to a timing at which a preset second period of time has elapsed while the number of rotations of the polygon mirror stays within a range that is from a second number of rotations to a third number of rotations inclusive, the second period of time being shorter than the first period of time.