Patent US5051579A successfully refreshed from Google Patents.
US5051579A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Optical scale encoder with light intensity alarm
Assignee: Canon Inc
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Filing: 1990-06-01
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Granted: 1991-09-24
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Expires: 2010-06-01
Abstract
Abstract An encoder for measuring movement of an optical scale by photoelectrically converting light from the optical scale obtained by applying light from a light source to the optical scale, by means of light receiving element, includes detector for detecting a variation in intensity of the light received by the light receiving element and a comparator for comparing a signal from the detector with a predetermined reference signal. Consequently, a predetermined alarm signal is generated on the basis of the result of comparison obtained from the comparator. A measuring system for detecting a moving condition of an object, includes an optical scale connected to the object; a light source for applying light to the optical scale; a first detector for receiving light from the optical scale and for detecting the moving condition of the object; a second detector for detecting a variation in intensity of the light received by the first detector; and a signal forming device for forming a predetermined alarm signal on the basis of an output signal from the second detector.
Inventors
- 👤 Masaaki Tsukiji
- 👤 Tetsuharu Nishimura
- 👤 Koh Ishizuka
- 👤 Satoshi Ishii
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 21:05
CPC Classifications
G; G01; G01D; G01D5/00; G01D5/26; G01D5/32; G01D5/34; G01D5/36; G01D5/38
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
204 words
A measuring system for detecting the moving condition of an object, comprising: an optical scale connected to said object; illumination means for applying light to said optical scale; light receiving means for receiving light from said optical scale and for producing output signals with different phases in accordance with the movement of the object; alarm signal forming means for detecting a variation in intensity of the light received by said light receiving means and for generating a predetermined alarm signal, wherein said alarm signal forming means includes comparison means for comparing each of the levels of the output signals from said light receiving means with a predetermined reference level and generating means for generating the predetermined alarm signal when at least one of levels of at least one of the output signals is less than the predetermined reference levels; a diffraction grating arranged on said optical scale along a moving direction of the object, wherein said illumination means applies light to said diffraction grating to generate first and second diffracted light, and wherein said light receiving means photoelectrically converts an interference fringe formed by effecting interference between the first diffracted light and the second diffracted light generated by said diffraction grating into electrical signals.
Claim 2
Dependent Claim
204 words
A measuring system for detecting the moving condition of an object, comprising: an optical scale connected to said object; illumination means for applying light to said optical scale; light receiving means for receiving light from said optical scale and for producing output signals with different phases in accordance with the movement of the object; alarm signal forming means for detecting a variation in intensity of the light received by said light receiving means and for generating a predetermined alarm signal, wherein said alarm signal forming means includes comparison means for comparing each of the levels of the output signals from said light receiving means with a predetermined reference level and generating means for generating the predetermined alarm signal when at least one of levels of at least one of the output signals is less than the predetermined reference levels; a diffraction grating arranged on said optical scale along a moving direction of the object, wherein said illumination means applies light to said diffraction grating to generate first and second diffracted light, and wherein said light receiving means photoelectrically converts an interference fringe formed by effecting interference between the first diffracted light and the second diffracted light generated by said diffraction grating into electrical signals.
Claim 3
Dependent Claim
15 words
A measuring system according to claim 1, wherein said optical scale comprises a rotary scale.
Claim 4
Dependent Claim
141 words
A measuring system for detecting the moving condition of an object, comprising: illumination means for applying light to an optical scale connected to the object; light receiving means, including at least three photodetectors, for receiving light reflected from said optical scale, and for producing output signals with different phases in accordance with the movement of the object; and alarm signal forming means for detecting a variation in intensity of the light received by said light receiving means, and for generating a predetermined alarm signal, said alarm signal forming means including (a) comparison means for comparing each of the levels of the output signals of said photodetectors with a predetermined reference level at the same time, and (b) generating means for generating the predetermined alarm signal when the levels of all of the output signals are less than the predetermined reference level.
Claim 5
Dependent Claim
141 words
A measuring system for detecting the moving condition of an object, comprising: illumination means for applying light to an optical scale connected to the object; light receiving means, including at least three photodetectors, for receiving light reflected from said optical scale, and for producing output signals with different phases in accordance with the movement of the object; and alarm signal forming means for detecting a variation in intensity of the light received by said light receiving means, and for generating a predetermined alarm signal, said alarm signal forming means including (a) comparison means for comparing each of the levels of the output signals of said photodetectors with a predetermined reference level at the same time, and (b) generating means for generating the predetermined alarm signal when the levels of all of the output signals are less than the predetermined reference level.
Claim 6
Dependent Claim
38 words
A measuring system according to claim 3, wherein at least one of the output signals from said at least three photodetectors exceeds the predetermined reference level in a normal condition irrespective of the position of said optical scale.
Claim 7
Dependent Claim
15 words
A measuring system according to claim 3, wherein said optical scale comprises a rotary scale.
Claim 8
Dependent Claim
161 words
A measuring system for detecting the moving condition of an object, comprising: an optical scale connected to the object and comprising a diffraction grating arranged on said optical scale along a moving direction of the object; illumination means for applying light to said optical scale; light receiving means, including at least three photodetectors, for receiving light reflected from said optical scale, and for producing output signals with different phases in accordance with the movement of the object; and alarm signal forming means for detecting a variation in intensity of the light received by said light receiving means, and for generating a predetermined alarm signal, said alarm signal forming means including (a) comparison means for comparing each of the levels of the output signals of said photodetectors with a predetermined reference level at the same time, and (b) generating means for generating the predetermined alarm signal when the levels of all of the output signals are less than the predetermined reference level.
Claim 9
Dependent Claim
161 words
A measuring system for detecting the moving condition of an object, comprising: an optical scale connected to the object and comprising a diffraction grating arranged on said optical scale along a moving direction of the object; illumination means for applying light to said optical scale; light receiving means, including at least three photodetectors, for receiving light reflected from said optical scale, and for producing output signals with different phases in accordance with the movement of the object; and alarm signal forming means for detecting a variation in intensity of the light received by said light receiving means, and for generating a predetermined alarm signal, said alarm signal forming means including (a) comparison means for comparing each of the levels of the output signals of said photodetectors with a predetermined reference level at the same time, and (b) generating means for generating the predetermined alarm signal when the levels of all of the output signals are less than the predetermined reference level.
Claim 10
Dependent Claim
38 words
A measuring system according to claim 6, wherein at least one of the output signals from said at least three photodetectors exceeds the predetermined reference level in a normal condition irrespective of the position of said optical scale.
Claim 11
Dependent Claim
57 words
A measuring system according to claim 6, wherein said illumination means applies light to said diffraction grating to generate first and second diffracted light, and wherein said light receiving means photoelectrically converts an interference fringe, formed by affecting interference between the first diffracted light and the second diffracted light generated by said diffraction grating, into electrical signals.
Claim 12
Dependent Claim
30 words
A measuring system according to claim 6, wherein said optical scale comprises a rotary scale, and wherein said diffraction grating is formed along a rotational direction of said rotary scale.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-09-23 | 1995-03-25 | 1995-09-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-09-23 | 1999-03-25 | 1999-09-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-09-23 | 2003-03-25 | 2003-09-24 | $7700.00 | Window Closed / Lapsed |