Low electromagnetic emissions and improved signal quality video drive architecture for laser printers

A video drive circuit for transferring image information in an electrophotographic image forming device, the image information related to an image to be formed on a medium, the circuit comprising:

• a raster image processor for receiving a high-frequency data signal containing the image information and having a high frequency, the raster image processor further for forming an integer number of low-frequency data signals based upon the high-frequency data signal, each low-frequency data signal having a low frequency which is substantially less than the high frequency;
• a parallel interface cable connected to the raster image processor for transferring the low-frequency data signals, the parallel interface cable having at least as many conductors as there are low-frequency data signals, each low-frequency data signal being transferred across a corresponding conductor of the parallel interface cable;
• and
• a laser printhead comprising:
• a printhead control circuit connected to the parallel interface cable for receiving the low-frequency data signals from the parallel interface cable, and for combining the low-frequency data signals to form at least one reconstructed high-frequency data signal therefrom, the reconstructed high-frequency data signal having substantially the same high frequency and containing the same image information as the high-frequency data signal received by the raster image processor, the low frequency being a quotient of the high frequency divided by an integer value representing the integer number of low-frequency data signals;
• a high-frequency interface connected to the printhead control circuit for transferring the reconstructed high-frequency data signal;
• an analog laser diode driver for receiving the reconstructed high-frequency data signal and for driving a laser diode based thereon;
• and
• the laser diode connected to the analog laser diode driver, the laser diode for forming an image on the print medium based on the image information contained within the reconstructed high-frequency data signal.

A laser printer for forming images on a print medium, the laser printer having desired low levels of electromagnetic emissions, the laser printer comprising:

• a raster image processor for receiving a high-frequency image information signal containing the image information and having a high frequency, the raster image processor further for forming a plurality of low-frequency video signals based on the high-frequency image information signal that jointly carry image information relating to an image to be formed on the print medium, each low-frequency video signal having a low-frequency which is substantially less than the high frequency;
• a low-frequency interface connected to the raster image processor for transferring the low-frequency video signals;
• a printhead control circuit connected to the low-frequency interface for receiving the low-frequency video signals generated by the raster image processor, and for combining the low-frequency video signals to form at least one reconstructed high-frequency video signal that has substantially the same high frequency and carries the same image information as the high-frequency image information signal received by the raster image processor;
• a high-frequency interface connected to the printhead control circuit for transferring the reconstructed high-frequency video signal;
• and
• a laser device connected to the high-frequency interface, the laser device causing a toner material to transfer an image to the print medium based on the image information contained within the reconstructed high-frequency video signal.

A method for processing image information in a printer while producing electromagnetic interference below a desired level, the method comprising:

• generating a first high-frequency image information signal containing the image information and having a high frequency;
• forming a plurality of low-frequency image information signals based upon the first high-frequency image information signal, each low-frequency image information signal having a low frequency which is substantially less than the high frequency;
• transferring to a destination the low-frequency image information signals while producing electromagnetic interference below the desired level;
• receiving the low-frequency image information signals at the destination;
• combining the low-frequency image information signals to form at least one reconstructed high-frequency image information signal therefrom, the reconstructed high-frequency image information signal having substantially the same high frequency and containing the same image information as contained in the first high-frequency image information signal;
• transferring the reconstructed high-frequency image information signal to an image formation device while producing electromagnetic interference below the desired level;
• and
• forming an image on a print medium based on the image information contained within the reconstructed high-frequency image information signal.