Patent ID: 7245841

Claim:
An electrophotographic apparatus comprising: a plurality of image forming units which: electrify a photosensitive member, form electrostatic images, each being made up of an electrification potential portion and a discharge potential portion, on said photosensitive member by an exposure unit, and develop said electrostatic latent images with toner, to thus form toner images on said photosensitive member; an intermediate transfer belt on which said toner images of different colors formed on said photosensitive member are sequentially transferred in an overlapping manner by said respective image forming units; and an image detector for detecting registration patches formed on said intermediate transfer belt with said color toner images, registration correction control for aligning positions of said color toner images being employed, wherein said image detector comprises: an I/V converter for converting, into a voltage output, a current output as a result of a photoelectric element arranged in a traveling direction of said intermediate transfer belt receiving light reflected from said intermediate transfer belt and light reflected from said toner images formed on said intermediate transfer belt; a peak-hold unit for holding an output voltage into which said light reflected from said intermediate transfer belt has been converted by said I/V converter; and a computation unit for detecting a difference between said output voltage of the said peak-hold unit and an output voltage into which said light reflected from said toner images of respective colors is converted by said IV converter.