| 摘要 |
PURPOSE:To detect abnormality in a counterpart signal, by counting the number of encoder signal pulses in specific number of polarity detection signal pulses. CONSTITUTION:When polarity detection signals 6, 7, 8 are 'H', number of pulses in an encoder signal 5 is counted in counter circuits 12, 13, 14 through AND gates 9, 10, 11. Counts latched in latch circuits 15, 16, 17 are compared with a lower limit count signal 25 in comparator circuits 18, 20, 22 while compared with an upper limit count signal 24 in comparator circuits 19, 21, 23. If the count is lower than the lower limit or higher than the upper limit for at least one phase polarity detection signal, an 'H' level abnormality signal is fed from OR gate 26, 27, or 28 to an OR gate 29 and an abnormality signal 30 is produced from the OR gate 29. |
