Multiple-level printhead using embedded high speed serial data and control link with on-board exposure clock generation

Abstract

A product and process for an LED printhead used in electrophotographic printing that generates an exposure clock on the printhead for the LEDs. The present invention provides a high-speed interface that transmits print data that has been modified, or corrected, using the corresponding unique printhead brightness data as the base reference source data to the printhead boards. The corrected print data is then applied to the LED drivers that expose each LED simultaneously and uniquely. A non-linear clock is applied to the LED drivers as the reference clock to create the unique LED on time circuit. An Exposure RAM stores the data as parallel 8-bit data. A LATCH code received at an ASIC converts the Exposure RAM data into a serial bit stream. The preferred embodiment employs a 60 MHz clock, however, it should be readily apparent that numerous other clocking speeds can be employed. From this a linear or non-linear clock stream is created allowing 256 unique (linear or non-linear) exposure on times to the printhead driver circuitry. This is accomplished with a non-linear clock stream which allows a unique period for each clock period which then allows each increment of exposure time to be unique.