| US 7,538,313 B2 | ||
| Optical encoder having a no track portion of an optical scale being placed at a position symmetrical to a light non-transparent portion within an irradiation region of incident light | ||
| Toru Oka, Tokyo (Japan); Yoichi Ohmura, Tokyo (Japan); Hajime Nakajima, Tokyo (Japan); Masahiko Sakamoto, Tokyo (Japan); and Toshikazu Kitagaki, Tokyo (Japan) | ||
| Assigned to Mitsubishi Denki Kabushiki Kaisha, Tokyo (Japan) | ||
| Filed on Sep. 13, 2007, as Appl. No. 11/854,635. | ||
| Application 11/854635 is a division of application No. 10/555101, granted, now 7,285,769, previously published as PCT/JP2004/012067, filed on Aug. 23, 2004. | ||
| Claims priority of application No. 2003-391219 (JP), filed on Nov. 20, 2003. | ||
| Prior Publication US 2008/0277569 A1, Nov. 13, 2008 | ||
| Int. Cl. G01D 5/34 (2006.01) | ||
| U.S. Cl. 250—231.13 [250/239] | 1 Claim |
| 1. An optical encoder comprising:
an optical scale having at least one track in which a light transmission portion and a light non-transparent portion are arranged,
where an output pattern obtained by emitting an incident light functions as an optical code;
a light source portion including at least one light source for emitting said incident light; and
a light detecting portion including at least one light detecting element for detecting said output pattern,
wherein a portion of said optical scale which has no track is placed at a position symmetrical to said light non-transparent
portion within an irradiation region of said incident light from said light source with respect to an optical axis of said
light source as a symmetry axis.
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