| 摘要 |
PURPOSE:To obtain a simple and inexpensive construction by arranging information to be recorded on a rotor in a characteristic manner as to detect the direction of rotation simply by providing only one reading means. CONSTITUTION:A short pulse based on a reflection section 7a of a rotary disc 7 in a pulse generator 13 and a long pulse based on a reflection section 7b are detected optically 2 to obtain an output signal (d). This output signal (d) is inputted into a START and STOP terminals of a timer 12 through a long pulse detector 8 and a short pulse detector 9 of a rotation direction discriminator 14. On the other hand, the output of the short pulse detector is inputted into a RESET terminal through a delay circuit 10. The timer circuit 12 determine the time difference between the long pulse and the short pulse and compare it with time information as judging reference 11 with an built-in comparator circuit. Thus, the direction of the rotation is judged utilizing the fact that the time difference T1 when the rotary disc 7 rotates counterclockwise is longer than that T2 when the disc 7 rotates clockwise. |
