| 摘要 |
PURPOSE:To enhance the reliability of control, by counting the time of lapse after zero-crossing signal is generated, and by detecting lack of the signal for switching in case that the time is over a specified time set by the cycle of an AC power waveform. CONSTITUTION:A time T1 is set on a timer A which is stopped, cleared, and restarted at every time when zero-crossing signal is generated. A value corresponding with the electrical conduction start phase angle of a load is set on a timer B which is synchronized with the generation of the zero-crossing signal to start counting. When the zero-crossing signal is normally generated, then a time on the timer B is over a specified time after the specified time, and an interruption is caused at a microcomputer, and the electrical conduction control of the load is turned ON. When the lack of the zero-cross signal is caused, then the counting value of the timer A is set to be T1, and the timer B is started. When the continuous lack of the zero-crossing signal is caused for a long time, then the electrical conduction is controlled to be interrupted. |
