Patent ID: 7773899

Claim:
A method of converting a diffuse reflection output into an amount of toner transfer, comprising: detecting optically a plurality of gradation patterns of toner formed continuously on a surface of a detection target with different amounts of toner transferred by detecting both regular reflection light and diffuse reflection light simultaneously from the detection target; obtaining a regular reflection output increment and a diffuse reflection output increment from a difference of output values for each between an ON time of a light source for the detecting and an OFF time of the light source; multiplying the diffuse reflection output increment by a minimum value of a ratio between the regular reflection output increment and the diffuse reflection output increment; subtracting a result of the multiplying from the regular reflection output increment; converting a ratio between a result of the subtracting and the regular reflection output increment from the surface of the detection target into a normalized value; multiplying the normalized value by the diffuse reflection output increment; obtaining a diffuse reflection output conversion value by subtracting a result of the multiplying the normalized value from the diffuse reflection output increment; and acquiring a first-order linear relation between the diffuse reflection output conversion value and the amount of toner transfer, the amount of toner transfer being within a range in which detection of the amount of toner transfer by the regular reflection light is possible.