| US 7,612,331 B2 | ||
| Code disk with a plurality of tracks having different patterns | ||
| Masahiko Sakamoto, Tokyo (Japan); Koichi Sugimoto, Tokyo (Japan); Katsutoshi Kamakura, Tokyo (Japan); Masahiro Otani, Tokyo (Japan); Yasushi Kawashima, Tokyo (Japan); Isamu Higashioka, Tokyo (Japan); Masaru Imaizumi, Tokyo (Japan); and Osamu Murakami, Tokyo (Japan) | ||
| Assigned to Mitsubishi Denki Kabushiki Kaisha, Chiyoda-Ku, Tokyo (Japan) | ||
| Filed on Feb. 15, 2007, as Appl. No. 11/706,349. | ||
| Application 11/706349 is a division of application No. 10/334222, filed on Dec. 31, 2002, granted, now 7,193,962. | ||
| Claims priority of application No. 2002-11194 (JP), filed on Jan. 21, 2002; and application No. 2002-318158 (JP), filed on Oct. 31, 2002. | ||
| Prior Publication US 2007/0147222 A1, Jun. 28, 2007 | ||
| Int. Cl. G11B 7/24 (2006.01) | ||
| U.S. Cl. 250—237G [356/617; 250/231.18] | 24 Claims |
| 1. A code disk for an encoder formed with a transparent substrate comprising:
a plurality of tracks provided on the transparent substrate, each surface of the plurality of tracks having a mutually different
pattern, at least one pattern being formed of grooves which vary in pitch through the whole periphery of the code disk such
that the grooves have at least three different pitches, and intensity of a signal transmitted through the pattern having the
at least three different pitches varies according to positional displacement of the code disk, so that an absolute position
of the code disk is detected.
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