Patent ID: 8760724

Claim:
An image forming apparatus that performs gradation correction, comprising: a pattern type selecting unit that selects a single pattern type to be formed on an image carrier from a plurality of pattern types, for gradation correction control, in the form of rows of area coverage modulation patterns on the image carrier; a pattern forming unit that forms, on the image carrier of the image forming apparatus, the rows of area coverage modulation patterns, the rows of area coverage modulation patterns having patterns of different gradation values in steps by an area coverage modulation method; toner adhering amount detecting circuitry that measures toner adhering amount of each pattern of the rows of area coverage modulation patterns formed on the image carrier; and γ correction signal generation circuitry that generates a γ correction signal based on a detection result of the toner adhering amount detecting circuitry, the γ correction signal generation circuitry outputting the γ correction signal as a same signal for gradation correction in copier section circuitry and for gradation correction in printer section circuitry, wherein the image forming apparatus performs the gradation correction after performing a target toner adhering amount assurance process, the target toner adhering amount assurance process including forming gradation patterns on the image carrier by sequentially switching charging bias and developing bias according to a predetermined timing, the formed gradation patterns are then detected by the toner adhering amount detecting circuitry, and control is performed based on the detected result of the adhering amount by the toner adhering amount detecting circuitry so that a target adhering amount is obtained.