| 摘要 |
PURPOSE:To prohibit unwanted time limiting action free from inadvertent touch on a time setting switch by having the memory contents reset so as to invalidate a time limiting control signal when the set memory time is varied. CONSTITUTION:When a control switch 54 is operated after a set time is memorized through a time setting switch, an FF 49 making up a memory device inverts to be set. The Q output of the FF 49 opens an AND gate 48 to validate a time limiting signal from a comparator 47. Therefore, if inadvertent operation of the time setting switch happens to change the set time, the FF 49 is reset to invalidate the time limiting signal thereby prohibiting any unwanted time limiting action. |
