Patent ID: 8380094

Claim:
An image forming apparatus, comprising a toner image carrier that carries a toner image, a toner image detection sensor that detects a reference toner image on the toner image carrier, a temperature sensor that detects a temperature in the apparatus, and a storage section for storing a correlation between each temperature and a drive value for the toner image detection sensor; wherein calibration of the toner image detection sensor is performed by acquiring a corresponding drive value from the storage section based on the temperature measured by the temperature sensor and driving the toner image detection sensor at the corresponding drive value, wherein the toner image detection sensor is an optical sensor that includes a light emitting device and a light receiving device, and wherein, when calibrating the toner image detection sensor, the corresponding drive value is acquired from the storage section based on the temperature measured by the temperature sensor, the light emitting device of the toner image detection sensor is driven at the corresponding drive value, and if a detected light received value of the light receiving device is not within a predetermined appropriate value range, a process of modifying the corresponding drive value by a first range of modification so that the detected light received value approaches the predetermined appropriate value range, then again driving the light emitting device, and if the detected light received value of the light receiving device is not within the predetermined appropriate value range, modifying the modified drive value by a second range of modification that is smaller than the first range of modification so that the detected light received value approaches the predetermined appropriate value range and then again driving the light emitting device, is repeated until the detected light received value falls within the predetermined appropriate value range.