| 摘要 |
PURPOSE:To generate a trigger signal for executing exactly an electric conduction control, by providing a circuit for generating the trigger signal which is generated at the head of one period of an AC waveform, and ended in the latter half part of one period of the AC waveform, and also, sufficiently before the end time point of one period. CONSTITUTION:In an AC power control device for heating the glass in order to eliminate a cloud or an ice-drop, etc. adhering to the glass due to a difference between a room temperature and an open air temperature, a trigger circuit for generating a trigger signal which is generated at the head of one period of the AC waveform, and also, sufficiently before the end time point of one period is provided. For instance, a timer 56 generates a pulse of a time constant determined by a resistance 51b and a capacitor 55, but when a signal supplied to an input terminal 57b is changed to '1' level from '0' level, after its time point, a pulse signal supplied to an input terminal 57a becomes ineffective. In this way, a trigger signal for executing an exact electric conduction control can be generated. |
