| 摘要 |
A system for sensing the position of an object such as a rotating member has a plurality of photocouplers coupled with the interposition of a rotary disc having slits and rotating with the object. The system further has a position signal generating circuit for receiving signals produced by the photocouplers and producing a series of component position signals differing in phase successively by a predetermined phase difference, a counting circuit having an up/down count for determining the position of the object by counting occurrences of a predetermined change recurring periodically in the component position signals, and a direction determining circuit for producing an up/down signal for controlling the counting mode of the up/down counter. Each time the predetermined change occurs in any one of the component position signal, the direction determining circuit determines the order in which the change occurs in two successive component position signals.
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