Patent ID: 9442438
Filing Date: 2016-09-13
CPC Classification: G03G

Claim Text:
1. An image forming apparatus comprising: a fixing device that includes a rotatable fixing member, a pressing member configured to contact an outer surface of the fixing member to form a nip where toner not yet fixed is fixed onto a recording medium passing through the nip, and a heater for heating the fixing member; and a surface information detecting device configured to detect surface information of the fixing member, wherein the surface information detecting device forms alignment of a plurality of optical spots on the outer surface of the fixing member in a direction crossing a rotation direction of the fixing member at an angle not a right angle, detects a reflected light of each optical spot, and detects the surface information of the outer surface of the fixing device based on a plurality of detection results of the reflective lights; the surface information of the fixing member is information related to a scratch level and a scratch position of a streaky scratch; and the scratch position is specified by a differentiating operation differentiating a plurality of detection results in an alignment direction of the optical spots; and the surface information detecting device determines the scratch level based on a detection result of the scratch position and detection results at least two positions at which absolute values of differential values which are results of the differentiating operation of a plurality of detection results concentrate near zero.