Patent ID: 7649544

Claim:
A photoconductive belt coupled by rollers to a motor for rotation of the belt in an electrophotographic system; a charging station for charging a portion of the photoconductive belt to a relatively high, substantially uniform potential; an image data buffer for receiving a parallel image data stream; an raster output scanner (ROS) driver having a phase lock loop (PLL) circuit and a parallel to serial converter, the PLL circuit, generates a sub-pixel clock signal from a reference clock signal that corresponds to a video data clock signal, the sub-pixel clock signal having a period that is 1/N of a period of the reference clock signal, where N is a number of bits in a data byte of the parallel video data stream, and the parallel to serial converter converts the parallel image data stream to a serial image data bit stream in synchronization with the sub-pixel clock signal; an ROS light source modulated by the serial image data bit stream to generate a light directed to the charged portion of the photoconductive belt to form a latent image on the photoconductive belt corresponding to the parallel image data stream used to generate the serial data bit stream; the ROS driver further comprising: an override circuit coupled between the parallel to serial converter and the ROS light source, the override circuit providing a constant output signal to the ROS light source in response to an override signal; a development station for developing a toner image corresponding to the latent image formed on the photoconductive belt; a transfer station for transferring the developed toner image from the photoconductive belt onto a media sheet; and a fusing station for permanently affixing the transferred toner image to the media sheet.