| 摘要 |
PURPOSE:To realize the good control of temperature in a time proportion controlling system, by controlling a zero cross switch for every period with the timing signal using a period of a main AC current power supply for its period and a holding circuit. CONSTITUTION:The output voltage of a bridge circuit 2 including a thermistor 1 is supplied to the inverse input of the 2nd amplifier 5 via an amplifier 3 and compared with the output of a sawtooth wave voltage generator 6 having the in- phase input. Then a transistor TR9 is driven by the output of comparison. The output (c) of the TR9 is read into a D type F.F.21 by the signal (b) of a timing terminal, and the output (d) is held for the next timing, i.e., for a period of a waveform (a) of a main AC power supply 13. Thus a zero cross switch 11 is completely turned on or off. Accordingly, the output side of the switch 11 is completely held in the state (e) of ON or OFF for every period of the power supply 13 and by the zero cross operation. Thus a heater 12 can be heated and controlled for every period. |
