Exposure apparatus, image forming apparatus and heat adjustment method

An image forming apparatus comprising:

• a plurality of image carriers;
• a plurality of light emitting elements that are arranged corresponding to the plurality of image carriers respectively in a line for exposing the image carriers;
• a substrate that the plurality of light emitting elements are arranged thereon;
• a plurality of temperature measuring units that measure temperatures of the substrate along the arrangement direction of the plurality of light emitting elements;
• a plurality of heating units that heat the substrate along the arrangement direction of the plurality of light emitting elements;
• an exposure position detecting unit that detects exposure positions on the image carriers exposed by the plurality of light emitting elements;
• and
• a controller that controls heating values of the plurality of heating units respectively on the basis of the temperatures of the substrate measured by the plurality of temperature measuring units respectively and the exposure positions detected by the exposure position detecting unit,
• wherein
• the controller has a memory that stores a relationship between the temperatures of the substrate and a position change amount of the light emitting elements, and
• the controller controls the heating value of each of the plurality of heating units by use of the relationship stored in the memory.

A heat adjustment method comprising:

• measuring temperatures of a substrate on which a plurality of light emitting elements are arranged in a line, at a plurality of measuring points corresponding to the plurality of light emitting elements;
• heating the substrate by respectively controlling the amount of heating at a plurality of heating points corresponding to the plurality of light emitting elements so that a temperature difference between the temperatures measured at the plurality of measuring points becomes smaller;
• and
• controlling heating values at the plurality of heating points respectively on the basis of the temperatures of the substrate measured at the plurality of measuring points respectively, wherein
• a relationship between the temperatures of the substrate and a position change amount of the light emitting elements is stored, and
• the heating value at the plurality of heating points is controlled by use of the relationship.