| 摘要 |
<p>A counting circuit which counts the number of pulses asynchronously input during a predetermined period of time includes a counter (C') which counts the number of input pulses, a register (D) which stores the pulses emitted from the counter (C') every after a predetermined period, and a control circuit (B') which generates a signal for controlling the operation condition and a signal for controlling the operation period of the counter (C') and the register (D). The counter (C') performs the counting operation ordinarily during the period in which no signal is generated for determining the operation period of the counter (C'), i.e., during the period between a pulse and another pulse which represents the operation period. When the input pulses are fed to the counter (C') so as to be counted during the period in which the pulses are being generated, the control circuit (B') does not clear the value counted by the counter (C') but permits the counter (C') to continue the counting operation. Then, the value counted by the counter (C') is output to the register (D) so as to be latched there in order to prevent miscounting.</p> |
