Abstract: A fiber optic system is used in a laser ROS scanning system to generate a start of scan signal. In one embodiment, a single optical fiber is positioned at the beginning of a scan line sweep. The fiber transmits a portion of a scan beam energy to a photodetector located on a local electronics board. The photodiode generates an output signal which is sent as an input to a high speed comparator. A second input to the comparator is a divided down and delayed analog of the photodetector output signal. The comparator compares the two voltage wave forms and generates electrical signals at the precise time the two wave forms intersect or crossover. The comparator output is used to initiate the SOS signal of a gas or laser diode ROS.

Abstract: A method and apparatus is provided for lateral registration of image exposures on photoreceptive belts subject to lateral deviation from linear travel. In one embodiment, a plurality of Raster Output Scanner (ROS) imagers in a digital color printer are positioned so as to form successive images on the surface of the belt. A plurality of split cell photodetectors are positioned beneath the belt, one each associated with each of the ROS imagers. An aperture is formed in the belt in a non-image area, but in alignment with the detectors. Scan lines from each ROS unit are periodically visible through the aperture and illuminate the photodetector. The outputs from each of the photodetector photosites are compared and lateral belt movement errors thereby identified. Appropriate correction signals are generated to maintain the correct lateral registration.

Abstract: The present invention is directed to a precise method of registering plurality of imaging stations, so as to form sequential images on a photoreceptor belt in a single pass. A belt hole is formed in the photoreceptor belt, outside the image area, but within the scan of the imager scan line. The scan line is sequentially swept in a transverse direction across the width of the belt. As the leading edge of the belt hole advances into the sweeping beam, a plurality of beam sweeps will occur while the leading edge is moving through the sweep area. Due to the gaussian illumination of the scanning beam, the exposure at the belt edge gradually increases to a maximum point coinciding with the maximum illumination of the scanning beam. A detector is placed beneath the belt to provide a signal representing the exposure level of each scanning beam which crosses the leading edge of the advancing belt hole. The detectors produce a current output representative of the exposure level.