| 摘要 |
PURPOSE:To control the number of rotation of a motor by making a switch element conductive or non-conductive in all of a half cycle of AC and changing a proportion of conduction or non-conduction in <=10 continuous half cycles to adjust the conduction rate. CONSTITUTION:A computer 20 discriminates the set stage of motor speed; and if speed 0 (0% conduction rate) is set, a turning-off signal is outputted after input to a terminal CLK, and a switch element 3 is made non-conductive during a half cycle. If speed 5 (full speed of 100% conduction rate) is set when a switch 23 is made, a turning-on signal is outputted after input to the terminal CLK, and the element 3 is made conductive during this half cycle. If setting is not changed, speed '0' or 5 is kept. If speed '1' is set, a turn-on counter is counted up by +1 and the turning-on signal is outputted in case of the first time, but the turning-off signal is outputted if turning-on is already set once, and if it is decided whether the number of times of turning-off is 4 (<=10 set optionally) or not, and a turn-off counter is counted up by +1 if it is not 4; but if contents of the turn-off counter are 4, turn-on and turn-off counters are cleared together, and the conduction rate is kept at the set value to control the motor rotative speed. The noise is reduced because a waveform has not a quick rise, and the load adjustment width is extended.
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