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US 2007/0181791 A1Published application
Optical encoder
AssigneeCanon Kabushiki Kaisha
InventorsAkio Atsuta, Masahiko Igaki
Life of this patent
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Abstract
In an optical encoder, a plurality of light sources is controlled on and off so as to use light rays to irradiate an optical grating of a scale from a plurality of different directions. The light rays are received by a plurality of photoreceptor elements. Operations are performed using signals output from the photoreceptor elements. Accordingly, the relative position between the photoreceptor elements and the scale is detected precisely.
Claims5
An optical encoder comprising:
- a scale having an optical grating;
- a plurality of photoreceptor elements that are movable relatively with respect to the scale and that are disposed in relation to a pitch of the optical grating;
- a light source having a plurality of light emitting portions which irradiates the photoreceptor elements through the scale from at least two different directions;
- and
- a controller which changes the light emitting powers between the light emitting portions;
- wherein the controller obtains relative-position information of the scale and the photoreceptor elements based on the light emitting powers and on the plurality of signals obtained respectively in accordance with the changes of light emitting powers of the light emitting portions.
3 more elements
Dependencies are inferred from the claim text.