| 摘要 |
PURPOSE: A drum disc and a method for sensing a rotational direction are provided to sense a rotational direction of a drum by sensing a groove at a long interval and a groove at a short interval by photocoupler when the drum is rotated because four grooves are formed in the drum disc. CONSTITUTION: A drum disc comprises a drum(5), a plurality of grooves(1,2), and a photocoupler. The plurality of grooves is formed to be symmetrical to the outer circumference of the drum. Intervals between grooves are long or short. The photocoupler senses a rotational direction of the drum by being connected to the drum. The drum is rotated by a motor. The rotational direction is decided based on the interval of signals input when the drum is rotated.
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