| 摘要 |
<p>PROBLEM TO BE SOLVED: To eliminate a mechanism or a circuit for generating a PG (phase) signal from a drum motor by constituting means for generating/detecting a specified PG signal of a pair of light emitting element and a light receiving element disposed at such positions as a light passes through through holes made in the outer circumferential part of a drum. SOLUTION: Through holes 4, 5 are made through the outer circumferential part of upper and lower drums 2, 3 in the direction of rotary shaft at such positions as the through holes 4, 5 act as one trough hole when the upper drum 2 turns. Since the through holes 4, 5 are aligned once as the upper drum 2 revolves once, light emitted from a light emitting element 6 enters a light receiving element 7. Since light is outputted from the light receiving element 7 as one signal per revolution, it can be used as a PG signal for controlling the phase of rotation. Consequently, a drum motor requires only a simple FG pattern as the magnetization pattern.</p> |
