| 摘要 |
PURPOSE:To prevent the occurrence of count error, by a method wherein a rotary angle between a specified number of pulses of slits detected by light is measured based on an output of a shaft encoder, and it is decided whether or not a normal number of them exists. CONSTITUTION:Only a specified number n of slits 2 is formed in a disc 1, which is driven for rotation by a motor 5. A shaft encoder 6, which generates N pulses, being enoughly move than the slit number n, at each one complete turn, is mounted to the rotary shaft of the motor 5, and the signal thereof is inputted to a counter 11. Meanwhile, a photo transistor 4 detects light, emitted from a luminous diode 3, through the slits 2, and supplies it to a counter 7. The counter 7 is subtraction-counted each time the slit detecting signal from the transistor 4 is inputted. A rotary angle between n pieces of the slits in the disc so inspected is measured, and the value is processed by a processor. This permits the measurement of the number of the slits in the disc without the occurrence of a count error. |
