| 摘要 |
PURPOSE:To enable a developed visible image to be improved in reproducibility to inputted image signals by a method wherein a delay means which delays that image signals transfer from an ON-state to an OFF-state is provided. CONSTITUTION:A drive circuit is composed of an input, image signal delay circuit 1 which corrects light pulses in width, a switching circuit 2 which drives a semiconductor light emitting element 4 in pulses, and a variable current source circuit 3 which determines a current which drives the semiconductor light emitting element 4. The waveforms of light signals inputted to or outputted from the delay circuit 1 are shown in figure. At this point, when an input signal changes from a Low level to a High level, an output signal is delayed by a delay time of an invertor. Therefore, an input image signal at a low level is elongated in time by DELTAt through the delay circuit 1 to elongate a semiconductor light emitting element in light pulse ON-time, whereby a light pulse can be compensated in width. At this point, the delay time DELTA t is required to be set to enable a printed developed image to be optimal to input image signals. |
