Apparatus of generating control signals for controlling an operation of an electrophotographic copying machine

An apparatus of generating control signals for controling an operation of an electrophotographic copying machine of the type wherein said control signals are generated in timed relationship with rotation of a photosensitive drum disposed in said copying machine, the improvement comprising a disk having through-holes therein and driven in association with said photosensitive drum, a light emitting device, a photosensitive device spaced apart from said light emitting device to sense binary coded light signals formed by said light emitting device and said through-holes of said disk and a decoder connected to said photosensitive device, said disk having a strobe section for strobe through-holes and a plurality of code sections for code through-holes associated with said strobe through-holes, said strobe section and said code sections being formed in outer and inner radial portions, respectively, of said disk, and the arrangement being such that as said disk rotates said strobe and code through-holes are, in operation, brought into registration with the path of light from said light emitting device to said photosensitive device to permit light to pass through said through-holes.