Xerox Corporation

Gary R Skillman

David Keneth Ahl

Roger M Swanson

Ross E Schroll

Timothy G Struczewski

James C Fox

Michael Terietzki

Roy Lee

Light emitting diode (LED) bar systems have large surface areas and extensive cabling that carry high frequency clocks and data. As the process speeds increase, the higher clock and data rates become an electromagnetic interference (EMI) problem. As the U.S. federal government restricts EMI emissions, many have turned to shielding techniques. However, a spread spectrum technique now may also reduce peak EMI amplitudes by distributing the EMI energy over a range of frequencies. The pixel data may be clocked into a LED bar system with a varying frequency to spread the energy over the range of the modulation. The same total energy is still emitted from the system, but the peak energy at any particular frequency is reduced.

Method of reducing electromagnetic emissions (EMI) from LED bar systems

A Direct Digital Synthesis pixel clock generator for use in electrophotographic printers. A controller receives a start-of-scan signal and a facet 0 signal. In response, the controller sends a pre-stored frequency control word to a Direct Digital Synthesis Oscillator. The Direct Digital Synthesis Oscillator sends pulses at a frequency that depends on the frequency control word to a Digital Phase Shift Circuit. The controller also applies a sequence of delay profile words to the Digital Phase Shift Circuit. Each delay profile word causes the Digital Phase Shift Circuit to delay a contemporaneous pulse from the Direct Digital Synthesis Oscillator between 0&deg; and 360&deg; degrees, with the actual delay depending upon the delay profile word. The delay profile words are selected such that scan line pixels are &ldquo;adjusted&rdquo; in position. A phase-locked-loop circuit integrates and smoothes the frequency step changes. The output of the phase-locked loop circuit is applied to a synchronizer that synchronizes the pixel clocks with the start-of-scan. Alternatively, the controller applies a sequence of frequency profile words to a Direct Digital Synthesis Oscillator. The Direct Digital Synthesis Oscillator then generates pulses at a rate that depends upon the applied frequency profile word. The frequency profile words are selected such that the pixels are &ldquo;adjusted&rdquo; in position. A phase-locked-loop circuit then integrates and smoothes the output of the Direct Digital Synthesis Oscillator. The resulting pulse frequency is applied to a synchronizing circuit that synchronizes the pixel clocks with the start-of scan-signals.

Direct digital synthesis pixel clock generator

An apparatus for effecting electrical connection between the main machine and a module containing the apparatus for advancing a sheet through the transfer zone and to registration for information developed on the photoreceptor belt. The connector on the main machine is mounted to permit engagement with a complementary connector on the module, but provide for movement when the module is raised slightly to contact the photoreceptor module. The apparatus minimizes which otherwise would inhibit this upward movement and detract from proper operation of the machine and the quality of the copy produced.

Electrical connector for an electrophotographic printing machine

Growing community of inventors

Rochester, NY, United States of America

Gary R Skillman