| US 7,589,314 B2 | ||
| Optical encoder applying substantially parallel light beams and three periodic optical elements | ||
| Toru Oka, Tokyo (Japan); and Yoichi Ohmura, Tokyo (Japan) | ||
| Assigned to Mitsubishi Denki Kabushiki Kaisha, Tokyo (Japan) | ||
| Appl. No. 11/571,617 PCT Filed Jun. 17, 2005, PCT No. PCT/JP2005/011151 § 371(c)(1), (2), (4) Date Jan. 04, 2007, PCT Pub. No. WO2006/006342, PCT Pub. Date Jan. 19, 2006. |
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| Claims priority of application No. 2004-204552 (JP), filed on Jul. 12, 2004. | ||
| Prior Publication US 2008/0048104 A1, Feb. 28, 2008 | ||
| Int. Cl. G01D 5/34 (2006.01) | ||
| U.S. Cl. 250—231.13 [359/440; 359/441; 359/442] | 16 Claims |
| 1. An optical encoder for measuring a relative movement of a first scale plate and a second scale plate, comprising
a light source,
a lens which converts light from the light source into substantially parallel light beams,
a first scale plate provided with an optical element array which cyclically converges or diffuses the light beams outgoing
from the light source through the lens, in a predetermined direction, and generates a cyclic light quantity distribution,
a second scale plate which cyclically makes spatial modulation on the light beams from the first scale plate,
a third scale plate having slits which allow the light beams from the second scale plate to pass therethrough, and
a light-receiving element which receives the light beams from the third scale plate.
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