发明名称 |
Optical encorder for detection having a moving reference point |
摘要 |
The present invention provides an optical encoder capable of using the recesses and convexes of a movable plate and a fixed plate to accurately generate a Z phase signal in synchronism with an A/B phase signal. Phase type diffraction gratings on the moving and fixed plates including a plurality of tracks with different grating pitches cause parallel coherent beams to interfere with one another, and a light receiving part detects the intensity of light to obtain a plurality of synchronous signals with different periods. On the other hand, the light receiving part detects light spots formed by condensing elements on the movable plate to generates a single pulse per rotation as a reference position. One of the plurality of synchronous signals that has the shortest period is selected as an A/B phase signal that depends on the movement of the movable plate. The conjunction of the reference position signal and the plurality of synchronous signals is determined as a Z phase signal indicating the origin of the movable plate, thereby obtaining a Z phase signal in synchronism with one pulse of the A/B phase signal.
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申请公布号 |
US5981941(A) |
申请公布日期 |
1999.11.09 |
申请号 |
US19970859321 |
申请日期 |
1997.05.20 |
申请人 |
MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD. |
发明人 |
TAKATA, KAZUMASA;NISHII, KANJI;TAKAMOTO, KENJI;ITO, MASAMI;FUKUI, ATSUSHI;KISHI, TOMOHISA |
分类号 |
G01D5/38;(IPC1-7):G01D5/34 |
主分类号 |
G01D5/38 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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