Patent ID: 9244415
Filing Date: 2016-01-26
CPC Classification: G03G

Claim Text:
1. An image forming apparatus comprising: an image carrier; an image forming unit configured to form a patch image including a plurality of patterns on the image carrier; a light emitting unit; a plurality of light receiving units adjacently arranged so as to receive light reflected from the patch image when light is irradiated by the light emitting unit onto the patch image which moves with movement of the image carrier, and each including one or more light receiving elements; and an output unit configured to output an output signal that depends on a difference between a received light quantity of a first light receiving unit and a received light quantity of a second light receiving unit that are respectively odd-numbered and even-numbered in an arrangement order of the light receiving units, wherein the plurality of light receiving units is configured to receive light reflected from the plurality of patterns, the output unit is further configured to output the output signal indicating a first value when the plurality of light receiving units receives light from a first number of patterns among the plurality of patterns, and to output the output signal indicating a second value greater than the first value when the plurality of light receiving units receives light from a second number of patterns, which is greater than the first number of patterns, among the plurality of patterns, the patch image includes one or more lines, the light emitting unit and the plurality of light receiving units are arranged such that the received light quantity of the first light receiving unit and the received light quantity of the second light receiving unit, of light irradiated by the light emitting unit and reflected by the patch image, vary with movement of the image carrier, and respectively differ, and wherein the plurality of light receiving units is arranged at different positions in a movement direction of the image carrier.