| 摘要 |
PURPOSE:To change the number and width of white and black image elements in a subscribed printing area to print out a half tone image by attaching a circuit which changes the pulse frequency of a pulse signal according to the half tone level of the image and outputs the pulse frequency. CONSTITUTION:A white/black discriminating signal, a 24-times clock and a black level discriminating signal (BLn) with 6 levels are inputted in a pulse width modulating circuit 2 and the pulse width in the black division of the white/black discriminating signal is modulated with an optional half tone level and then the modulated pulse width is inputted in a laser diode driving circuit 1. In case of the pulse width modulation in the black division, each pulse width out of (2)BL1-(7)BL6 is modulated 2,3,4,6,8, and 24 times of the clock pulse width in the black division of (1) white/black discriminating signal (B/W) so that (2)BL1 is the most whitish and (7)BL6 is completely black in the whole division like B/W. |
