| 摘要 |
<p>PURPOSE:To enable the entire surface of a liquid-crystal optical shutter to be controlled to a uniform temperature, by providing a temperature-detecting element for detecting the temperature of one of a plurality of heat generating elements, and controlling the other ones of the heat generating elements on the basis of an output from the temperature-detecting element and paper size information. CONSTITUTION:A temperature-controlling circuit 32 outputs a control signal through control of pulse width based on a value detected by a thermistor 25. The control signal S3 is outputted directly to a heater 22 corresponding to B5 size through an inverter circuit 33, and is outputted also to a correcting circuit 31. An output from a counter circuit 28 is inputted through a bus line A to a calculating circuit 30, which calculates the quantity of electric current to be passed to a heater corresponding to a part other than a self-heat-generating part of a liquid-crystal optical shutter so that the temperature of the self-heat-generating part and that of the other part will be equal, based on the number of black dots and size information. The result of the calculation is inputted to the correcting circuit 31, which outputs correction signals S4, S5 based on the inputted value to heaters 23, 24. Each of the heaters is supplied with an electric current from a power source V24 when the corresponding signal is at a high level.</p> |
