| 摘要 |
PURPOSE:To perform a multilevel printing by regulating the power of light with time by utilizing a pulse width modulating system. CONSTITUTION:A triangular wave and a DC voltage are inputted to the positive and negative input terminals of a comparator 8, respectively. A square wave is outputted from the comparator 8 and the pulse width of an output is changed by the voltage of the negative input terminal. Therefore, a period during which an LED is turned on is changed. A printing power for a prescribed period is represented by the product of the light quantity of the LED and the time for which the LED is turned on and changed by the pulse width because the light quantity of the LED is constant. Since voltage is controlled, a control can be relatively simply performed with an excellent accuracy and, when the frequency of the triangular wave is high, the number of pulses during a prescribed time (a printing time) is high, a multilevel printing being facilitated. |
