| 摘要 |
PURPOSE:To increase a detection speed, to reduce erroneous detection, and to improve detection precision by outputting a rotational direction signal from one of the 1st and 2nd rotational direction detecting means which detects a direction of rotation earlier. CONSTITUTION:Notches of a flywheel are detected optically by phototransistors 71 and 72, and the 1st and 2nd rotational direction detecting circuits 101 and 102 generate high-level outputs. Those high-level outputs are processed by a switching circuit 103, provided with an NOR gate 47 and an AND gate 48, NOR gates 49 and 50 forming an FF, an AND gate 42 and an OR gate 43, AND gates 44 and 45 controlled by the output of the FF, an OR gate 46, etc., to select and output the output of the circuits 101 or 102 which has detected it eariler. Therefore, the speed of this rotational direction detection is made faster than that of discrimination which uses both the detection outputs of the circuits 101 and 102. Further, a period wherein an error detection signal due to a noise, etc., is outputted is shortened to reduce erroneous detection, thereby improving detection precision. |
