JPS6427363A - Drive method - Google Patents

Abstract

PURPOSE:To contrive to make a simple drive circuit usable and to improve the reliability by providing a photoconductive medium coupling a common electrode and an electrode array and using a scanning clock whose frequency is changed continuously in response to the change in the scanning speed so as to apply the optical scanning to the photoconductive medium. CONSTITUTION:The scanning clock is generated, while its frequency is varied continuously in response to the change in the scanning speed on a face to be scanned (photoconductive medium 13), and the optical scanning is applied by using the scanning clock. The phase of a position control clock and that of a clock CLA are compared to control the oscillating frequency of a voltage controlled oscillator 33. The scanning area is sectioned in advance into K-set of blocks and Mi, ni are set to each block so that the change in the frequency fk of the scanning clock caused in the voltage controlled oscillator 33 is well approximated to the change in the scanning speed. Thus, the frequency of the scanning clock is increased at the end of an electrode array 11 where the scanning speed is large and the frequency of the scanning clock is decreased at the center of the array 11 where the scanning speed is small so as to ensure the equi-speed of the scanning beam.