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US3566136A
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US
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System for detecting the sense of the direction of the variation in phase of a cyclically varying signal
Assignee: Olympus Corp
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Filing: 1968-11-20
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Granted: 1971-02-23
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Expires: 1988-11-20
Abstract
Abstract System for detecting the sense of the direction in which the variation in the phase of a cyclically varying signal is occurring comprising the steps of detecting a first signal having a phase in advance of that of the cyclically varying signal by one-fourth of the cycle thereof and a second signal having a phase in retard of that of the first-mentioned cyclically varying signal by one-fourth of the cycle thereof, and producing two resultant signals having their phases relatively shifted from each other by one-fourth of the cycle of the first-mentioned cyclically varying signal by producing the vectorial differential respectively between the above-described first signal and the first-mentioned cyclically varying signal and between the same and the above-described second signal. The thus produced two resultant signals are used for detecting the sense of the variation in the phase of the first-mentioned cyclically varying signal. The accuracy is improved regardless of the drifts of the signal responding means used in the system, while the production cost is lowered by reducing the number of the signal responding means required as well as by increasing in latitude of the allowance of the sensitivity of the same.
Inventors
- 👤 Shin-Ichi Kamachi
- 👤 Yuzi Ikuno
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 16:00
CPC Classifications
G; G01; G01P; G01P13/00; G01P13/02; G01P13/04
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
148 words
The method of detecting the sense of the direction in which the variation in the phase of a cyclically varying signal is occurring, wherein the improvement comprises the steps of detecting a first signal having a phase in advance of that of said cyclically varying signal by one-fourth of the cycle thereof and a second signal having a phase which lags that of said cyclically varying signal by one-fourth of the cycle thereof, and producing two resultant signals having their phases shifted by one-fourth of the cycle of said cyclically varying signal relative to each other by producing the vectorial differential of said first signal subtracted by said cyclically varying signal and the vectorial differential of said cyclically varying signal subtracted by said second signal, thereby permitting the sense of the variation in the phase of said cyclically varying signal to be detected by said two resultant signals.
Claim 2
Independent Claim
148 words
The method of detecting the sense of the direction in which the variation in the phase of a cyclically varying signal is occurring, wherein the improvement comprises the steps of detecting a first signal having a phase in advance of that of said cyclically varying signal by one-fourth of the cycle thereof and a second signal having a phase which lags that of said cyclically varying signal by one-fourth of the cycle thereof, and producing two resultant signals having their phases shifted by one-fourth of the cycle of said cyclically varying signal relative to each other by producing the vectorial differential of said first signal subtracted by said cyclically varying signal and the vectorial differential of said cyclically varying signal subtracted by said second signal, thereby permitting the sense of the variation in the phase of said cyclically varying signal to be detected by said two resultant signals.
Claim 3
Dependent Claim
42 words
System according to claim 1, wherein said cyclically varying signal and said first and second signals are electrical sinusoidal wave signals, the phase differences therebetween being pi /2, respectively, so that the phase difference between said two resultant signals is pi /2.
Claim 4
Dependent Claim
140 words
System according to claim 2, wherein said cyclically varying signal is derived from a photoelectric element which receives light from a light source through moire fringes generated by two superposed diffraction gratings and moved across the optical path of the light by the relative movement of said diffraction gratings caused in accordance with the movement of an object the displacement of which is to be detected, said first signal being derived from a photoelectric element located in advance of said first mentioned photoelectric element in the direction of the movement of said moire fringes by one-fourth of the distance between adjacent fringes thereof while said second signal is derived from a further photoelectric element located lagging said first mentioned photoelectric element in the direction of the movement of said moire fringes by one-fourth of the distance between adjacent fringes thereof.
Claim 5
Dependent Claim
203 words
System for detecting the sense of the direction in which the variation in the phase of a cyclically varying signal is taking place, wherein the improvement comprises three signal responding means arranged in said system to receive said cyclically varying signal so that they produce the respective output signals with the phases thereof being shifted by one-fourth of the cycle of said cyclically varying signal from each other, and two differential means connected to said three signal responding means such that a vectorial differential of the first output signal with respect to the second output signal having its phase in advance of said first output signal by one-fourth of the cycle is produced by one of said two differential means while the other of said two differential means produces another vectorial differential of said second output signal with respect to the third output signal having its phase lagging said second output signal by one-fourth of the cycle so that two resultant vectorial differentials are provided having their phases shifted by one-fourth of the cycle from each other, said two resultant vectorial differentials being used for detecting the sense of the direction of the variation in the phase of said first-mentioned cyclically varying signal.
Claim 6
Dependent Claim
203 words
System for detecting the sense of the direction in which the variation in the phase of a cyclically varying signal is taking place, wherein the improvement comprises three signal responding means arranged in said system to receive said cyclically varying signal so that they produce the respective output signals with the phases thereof being shifted by one-fourth of the cycle of said cyclically varying signal from each other, and two differential means connected to said three signal responding means such that a vectorial differential of the first output signal with respect to the second output signal having its phase in advance of said first output signal by one-fourth of the cycle is produced by one of said two differential means while the other of said two differential means produces another vectorial differential of said second output signal with respect to the third output signal having its phase lagging said second output signal by one-fourth of the cycle so that two resultant vectorial differentials are provided having their phases shifted by one-fourth of the cycle from each other, said two resultant vectorial differentials being used for detecting the sense of the direction of the variation in the phase of said first-mentioned cyclically varying signal.
Claim 7
Dependent Claim
67 words
System according to claim 4, wherein said cyclically varying signal is moire fringes and said three-signal responding means are photoelectric elements while said two differential means are differential amplifier, a transistor is interposed between each of the photoelectric elements and the corresponding differential amplifier connected thereto so as to prevent the variation in the input to the respective differential amplifier supplied from each of said photoelectric elements.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-02-22 | 1974-08-24 | 1975-02-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-02-22 | 1978-08-24 | 1979-02-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-02-22 | 1982-08-24 | 1983-02-23 | $7700.00 | Window Closed / Lapsed |