Patent ID: 7889221

Claim:
An optical scanning apparatus that forms a latent image by scanning a laser beam emitted from a light source on an image bearing member, the apparatus comprising: first and second laser beam detectors configured to detect the laser beam; and a calculator configured to calculate a slope of a scanning line on the image bearing member on the basis of a result of detection obtained by the first and second laser beam detectors, wherein the first laser beam detector detects the laser beam in a scanning area in front of an area in which the latent image is formed on the image bearing member and the second laser beam detector detects the laser beam in a scanning area behind the area in which the latent image is formed on the image bearing member, wherein the slope θ of the scanning line on the image bearing member is calculated by the calculator as follows: tanθ=( T 1− T 2)/( T−T 1+ T 2) where T is a time from when the laser beam is incident on the first laser-beam detector to when the laser beam is incident on the second laser-beam detector, T 1 is a time during which an output signal is output from the first laser-beam detector, and T 2 is a time during which an output signal is output from the second laser-beam detector.