Abstract: A control system for an optical sheet sensor device, including at least one light emitter and at least one light detector associated therewith for sensing a sheet in a sheet travel path for automatically controlling the sheet sensor device in order to provide an intensity of light from the light emitter to compensate for varying background reflectance and background-to-light emitter distance. The control provided for determining a light emitter current level corresponding to an operating condition where a sheet is known to be absent from the sheet travel path and where there is a close, reflective background to the light emitter. A light emitter current operating level corresponding to a reduced level with respect to the above determined current level is stored. A current startup error level at a preset amount off-set from the stored current level is determined.

Abstract: A power supply adapted for use with a corona charger. The power supply includes a first DC power source providing an electrical potential above a predetermined reference potential, and a second DC power source providing an electrical potential below such predetermined reference potential. A main circuit having an output adapted to be connected to a corona charger, includes a switching circuit for selectively turning the first and second DC power sources on and off in a manner so as to provide a an electrical potential having an AC waveform output for the main circuit.

Abstract: A brake for a sprocket-optical encoder assembly associated with an electrophotographic copier consists of a metal disc positioned in a magnetic field, mounted on a common shaft with the sprocket driving an optical encoder. The teeth of the sprocket are engaged in perforations in the photoconductor film belt of the copier, and the sprocket and the shaft, together with the disc and encoder are, therefore, driven by movement of the film. As the disc is caused to rotate in the magnetic field, eddy currents are generated therein which resist the rotation. Such resistance acts as a brake on the sprocket, causing the trailing edge of its teeth to maintain contact with the trailing edge of the perforations, thereby avoiding back and forth movement of the teeth within the perforations and consequential destructive impacts with the edges thereof.

Abstract: An optical encoder monitors linear CCD elements as an edge of a perforation or other optical indicia passes along the elements. A line printhead is actauted at least one in response to each new element being activated. The device is particularly useful in a color nonimpact printer in which multiple images are superimposed by line printing, preferably at printheads at a plurality of locations, to create multicolor images.