Patent ID: 8154577

Claim:
A light level controlling apparatus, comprising: a light source configured to irradiate a light beam; a rotatable deflector configured to rotate to scan the light beam irradiated by the light source to an image writing area in a main scanning direction to form an image on the image writing area; a detector provided outside the image writing area and configured to output a synchronization detection signal indicating a time when the light beam scanned by the rotatable deflector enters the image writing area; a storage unit configured to store light level correction data, the light level correction data including: an initial light level correction value indicating an initial light level of the light beam to be irradiated by the light source when the light beam enters the image writing area after the synchronization detection signal is output; and light level change information indicating a change in a light level correction value for a specific main scanning position with respect to the initial light level correction value, the light level correction value for the specific main scanning position indicating a light level of the light beam to be irradiated by the light source when the light beam scans at the specific main scanning position of the image writing area; and a light level controller configured to cause the light source to irradiate the light beam having the light level determined based on the light level correction value for the specific main scanning position; wherein the light level change information of the light level correction data includes: inclination amount data indicating a degree of change in the light level correction value with respect to the initial light level correction value or a preceding light level correction value, the preceding light level correction value indicating a light level of the light beam to be irradiated onto a preceding main scanning position of the image writing area that precedes the specific main scanning position; and inclination direction data indicating a direction of change in the light level correction value with respect to the initial light level correction value or the preceding light level correction value.