METHOD FOR CONTROLLING DENSITY OF LASER BEAM PRINTER

摘要

PURPOSE:To preform the control of density of a laser beam printer without using a movable part by varying the pulse width of the analog signal which drives directly a laser diode. CONSTITUTION:The picture data on an address designated by an address decod er 23 is read out of a dynamic memory 24 synchronously with the pixel clock of 2MHz and applied to AND gates 25a-25h respectively as the output of 8 bits (256 gradations). These gates 25a-25h are controlled by a data selector 29 and the pulse of the analog signal is modulated by opening/closing said gates. Here the pluses having seven different widths are outputted in parallel from a shift register 28 and sent to the selector 29. The selector 29 selects the optional one of those seven different pulses according to the states of data inputs A-C and send it to gates 25a-25h respectively.