| 摘要 |
PURPOSE:To shorten a detecting time and detect with good accuracy the revolution speed in a wide range by counting the output of a pulse generator by the first counter simultaneously with the output of the pulse generator and by counting by the second counter the output of the oscillator having sufficiently high frequency during the following pulse generating period after the lapse of a fixed time. CONSTITUTION:With the input of a START signal an FF12 actuates a counter 16 with the rising of a pulse generator 11 and starts the counting of the output of the high frequency oscillator 15 having sufficiently high frequency. Simultane ously it starts the counting of the output ENP of the pulse generator with actuating a counter 17 by the output of the counter 16 and continues the counting until the fixed measuring time being decided by the capacity of the counter 16. With the lapse of the time T a counter18 is actuated via FF13, 14, OR gate 12 and inverter 20 by the rise of the output of the counter 16 and the counting of the output of the high frequency oscillator 15 is started and the counting is stopped by the fall of the following output. An arithmetic circuit 22 calculates the revolution speed from the count values of counters 17, 18 and T. |
