PIXEL CLOCK PHASE LOCK LOOP FOR A LASER SCANNER

• Main Author: NACMAN, ARON
• Format: Patent
• Language: English
• Published: 03.03.1993
• Edition: 5
• Subjects: ELECTRIC COMMUNICATION TECHNIQUE; ELECTRICITY; PICTORIAL COMMUNICATION, e.g. TELEVISION

A pixel clock phase lock loop for a laser scanner having a rotating multi-faceted polygon receives start-of scan and end-of-scan pulses for each of a plurality of scan lines. A voltage-controlled oscillator outputs a desired frequency of the pixel clock. A desired number of pixels in each scan line is counted, and a pulse is output at the last pixel in the scan line. The end-of-scan pulse and the last pixel pulse are compared, and an output is provided of phase error, the phase error being equal to the difference between the end-of-scan pulse and the last pixel pulse. The phase error for a facet of the polygon is utilized when the facet scans an imaging beam on a next subsequent polygon revolution. The phase error is converted to a voltage, and the phase error voltage is added to a center frequency voltage to generate a composite voltage for controlling the voltage-controlled oscillator.