Patent ID: 8829798

Claim:
A light amount control apparatus for controlling a light amount of an LED element by current control, comprising: a drive control unit configured to supply a current to the LED element; a light amount detection unit configured to detect the light amount of the LED element; a temperature detection unit configured to detect an ambient temperature of the LED element; a storage unit configured to store a first current amount which has been preset so that the light amount of the LED element reaches a target light amount value at a predetermined reference ambient temperature, and a thermal correction coefficient for correcting the first current amount so that the light amount of the LED element reaches the target light amount value at an ambient temperature different from the predetermined reference ambient temperature; and a calculation unit configured to calculate, when the light amount of the LED element detected by said light amount detection unit reaches the target light amount value, from a second current amount supplied to the LED element by said drive control unit and the thermal correction coefficient corresponding to the ambient temperature of the LED element, an aging correction coefficient for correcting the first current amount to correct a change in light amount due to aging of the LED element at the predetermined reference ambient temperature, and to store the calculated aging correction coefficient in said storage unit.