Image forming apparatus

An image forming apparatus comprising:

• a light source;
• a laser scanning member configured to scan light emitted from the light source;
• a light detecting portion configured to detect light incident on a predetermined position in a scanning path of the light scanned by the laser scanning member;
• a light source control portion configured to, each time the light detecting portion detects light, cause the light source to emit light corresponding to image data of a line, at a predetermined emission start timing;
• a scanning lens configured to cause the light scanned by the laser scanning member to be scanned at an equal speed on an image carrier;
• a housing in which the laser scanning member, the light detecting portion, and the scanning lens are disposed;
• a temperature gradient detecting portion configured to detect a temperature gradient of the housing;
• a heater configured to heat the image carrier or a sheet before image transferring;
• and
• a correction processing portion configured to correct the emission start timing based on the temperature gradient detected by the temperature gradient detecting portion and a predetermined expression, and change a content of the predetermined expression based on an operation state of the heater at a start of an image formation process.