| 摘要 |
PURPOSE:To discriminate the frequency of a commercial power source precisely by storing two discrimination results of a discriminating means, comparing those two stored discrimination results with each other, and outputting a coincidence signal and stopping a timer when they are equal to each other. CONSTITUTION:A frequency discrimination device is provided with the discriminating means 1 which discriminates the frequency of the commercial power source, the timer 2 which outputs a discriminating operation start signal to the means 1, a sequential storage means 4 which stores the discrimination result of the means 1 successively, and a comparing means 4 which compares two discrimination results with each other and then outputs the coincidence signal and also stops the timer 2 when they are equal to each other. When the discrimination start signal is outputted by the timer 2, the discrimination results of the discriminating means 1 are stored in memories 3a and 3b of the storage means 3 successively. The comparing means 4 compares the last and current discrimination results stored in the memories 3a and 3b with each other to repeat the operation while replacing the current discrimination value with a temporary decision value when they are not coincident or to output the coincidence signal and stops the timer 2 when they are coincident, thereby finishing the discriminating operation.
|
