| 摘要 |
<p>PURPOSE: To print a half tone image excellent in gradation properties by supplying digital image data containing gradation data at every pixel to convert the same to analogue data and subjecting the analogue data to shift transfer before applying predetermined drive potential to LED elements. CONSTITUTION: The image data outputted to a head controller 14 is converted to analogue data of the corresponding gradation by a D/A converter 16 and the analogue data is amplified to a predetermined level by an operational amplifier 17 to be outputted to an analogue shift register 18. Herein, a clear signal (CLR) is outputted to turn the corresponding analogue switch 21b ON and the charge remaining in condensers 21a is removed. This processing is executed in all of initializing circuits 20. Thereafter, a shift signal (SH) is outputted and the image data is transmitted to a shift gate 19 and charge is accumulated in the condensers 21a. A strobe signal (STR 1) is outputted not only to drive MOSFET 23 but also to allow LED elements 24 to emit light according to the charge quantity of the corresponding condensers 21a.</p> |
