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US 5,671,052 AGranted
Optical encoder
AssigneeOlympus Optical Co., Ltd.
InventorsIsao Kawakubo, Eiji Yamamoto
Life of this patent
Estimating the term…
Abstract
An optical encoder comprising a movable scale moving relatively to a light source, a surface-emitting semiconductor laser light-source for radiating a part of the movable scale, and a photodetector for receiving reflection light by the movable scale or transmission light through the movable scale.
Claims20
An optical encoder comprising:
- a movable scale which is movable relative to a light source,
- a surface-emitting semiconductor laser light-source for radiating light to a part of said movable scale, without any lenses or slits provided between said movable scale and said surface-emitting semiconductor laser light-source, and
- a photodetector for detecting light reflected by said movable scale or light transmitted through said movable scale.
An optical encoder comprising:
- a movable scale movable relative to a light source,
- a surface-emitting semiconductor laser light-source for radiating a part of said movable scale, and
- a photodetector for detecting light reflected by said movable scale or light transmitted through said movable scale,
- wherein said optical encoder satisfies the following relationship:
- p.gtoreq..lambda..multidot.L/a, when L.gtoreq.a.sup.2 /.lambda.,
- where L is the distance between said movable scale and a light beam emitting surface of said surface-emitting semiconductor laser light-source, .lambda. is a wavelength of a light beam, p is a scale pitch, and a is a beam diameter at the radiation window of said light source measured along a pitch direction of said scale.
3 more elements
An optical encoder comprising:
- a movable scale movable relative to a light source,
- a surface emitting semiconductor laser light-source for radiating a part of said movable scale, and
- a photodetector for detecting light reflected by said movable scale or light transmitted through from said movable scale,
- wherein said optical encoder satisfies the following relationship:
- p.gtoreq.a, when L<a.sup.2 /.lambda.,
- where L is a distance between said movable scale and a light beam emitting surface of said surface-emitting semiconductor laser light-source, .lambda. is a wavelength of a light beam, p is a scale pitch, and a is a beam diameter at the radiation window of said light source measured along a pitch direction of said scale.
3 more elements
An optical encoder comprising:
- a movable scale movable relative to a light source,
- a surface emitting semiconductor laser light-source for radiating a part of said movable scale, and
- a photodetector for detecting light reflected by said movable scale or light transmitted through said movable scale,
- wherein said optical encoder satisfies the following relationship:
- p.sub.1 .gtoreq..lambda..multidot.L/a.sub.1, when L.gtoreq.a.sub.1.sup.2 /.lambda.
- p.sub.2 .gtoreq..lambda..multidot.L/a.sub.2, when L.gtoreq.a.sub.2.sup.2 /.lambda.
- p.sub.1 .gtoreq.a.sub.1, when L<a.sub.1.sup.2 /.lambda.
- p.sub.2 .gtoreq.a.sub.2, when L<a.sub.2.sup.2 /.lambda.
- where L is a distance between said movable scale and a light beam emitting surface of said surface-emitting semiconductor laser light-source, .lambda. is a wavelength of light beam, p.sub.1 and p.sub.2 are pitches of said movable scale having different specific direction, and a.sub.1 and a.sub.2 are respective beam diameters at the radiation window of said light source corresponding to the direction of pitches p.sub.1 and p.sub.2.
6 more elements
Dependencies are inferred from the claim text.