Microprocessor Power Control in Multiple-Laser Printheads
Original Publication Date: 1989-Mar-01
Included in the Prior Art Database: 2005-Jan-27
This article illustrates a technique to control the power setting of laser diodes in a multiple-laser printhead. The power control includes the ability to set the individual "bias" points of each laser, and match the individual full-scale power settings to each other and an external reference. Previous power control hardware for some laser printhead products have used a maximum of one laser diode (if used at all). The laser diode full-scale magnitude of the input current is determined by an external reference generated in the printer. Some printers also use "grey scale". Operating the laser diode at predetermined intermediate power levels between "off" and full scale is known as "grey scale". Grey scale changes laser driver hardware from a binary "ON" and "OFF" mechanism to a very high speed digital-to-analog converter.