| 摘要 |
<p>PURPOSE:To reduce overshoot and the width of temperature ripple, by changing the width of on/off timing in response to the leading of temperature for the purpose of minute control, in a controller for fixation temperature of a copying machine. CONSTITUTION:A voltage at a point A is high when temperature is low and it is low when the temperature is high. This voltage signal is inputted to a V/F converter 2 comprising an operational amplifier 6 and an IC1 for a timer IC and the number of pulses nearly proportional to the voltage at the point A is outputted to a point B (No. 3 terminal of the IC1). Thus, when the temperature is low, the frequency of the output of the No. 3 pin of the IC1 is high, the output is inverted at an inverter 7 and inputted to a trigger terminal (No. 2 pin) of an IC2 for timer IC. When a trigger pulse interval T1 is shorter than a time constant depending on a resistor R2 and a capacitor C2, since the output of the No. 3 pin of the IC2 does not go to ''low'', a heater 5 keeps on. Conversely, when the time constant is longer, the output of the IC2 goes to ''low'' and the on-time of the heater 5 depends on the resistor R2 and the capacitor C2.</p> |
