| 摘要 |
<p>PURPOSE:To contrive a stable and accurate printing operation, by supplying an AC power synchronized with the period of a line data printing operation of a printer, and setting a cutoff point of a power supply at the time of switching to be coincident with or proximate to the zero point of the AC power. CONSTITUTION:When a LED-driving voltage DV is oscillated and outputted from an oscillator 21, a gate control signal GC outputted from a voltage comparator 31 becomes a signal containing logical levels of '1' and '0'. In a driver gate array 13, driver gates corresponding to the logical level '1' are opened synchronously to the signal, and the signal level at an output terminal thereof is brought to the logical level of '1'. By this, only the LEDs in a LED array 14 which correspond to data of logical level '1' in line data are operated to emit light. In a LED printer, a latent image is formed on a photosensitive body on the basis of the emission of light from the LED array 14, resulting in a print image. Based on the opening and closing operations of the driver gate array 13, the switching of the LED array 14 is constantly carried out at a zero level point of the voltage DV, so that noise or a surge voltage is hardly generated during a printing operation.</p> |
