US3597749A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic heads utilized as a displacement measuring instrument
Assignee: Sony Corp
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Filing: 1969-01-17
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Granted: 1971-08-03
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Expires: 1989-01-17
Abstract
Abstract An apparatus for the magnetic recording of gradient information wherein magnetic indicia are recorded on a magnetic medium which is detected by a pair of magnetic pickup heads. Since the spacing between the magnetic indicia is fixed it is possible to accurately measure distance by counting the number of magnetic indicia which move past the heads. Since there are two heads, the direction of movement of the information may be detected also. In the present invention, the two heads are indexed by supplying a variable phase shift mean in either of two channels and the indexing is accomplished by the phase shifters and the heads do not have to be mechanically moved relative to each other for proper indexing.
Inventors
- 👤 Saburo Uemura
- 👤 Kiyoshi Himuro
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 16:57
CPC Classifications
G; G01; G01D; G01D5/00; G01D5/12; G01D5/243
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
134 words
A displacement measuring instrument comprising a carrier signal generator, a magnetic scale having formed thereon magnetic gratings of fixed wavelength, two magnetic heads disposed in reading relationship with the magnetic scale and spaced apart from each other at a distance of (n+ 1/4) times the recorded wavelength of the magnetic gratings, (n being 0, 1, 2, 3,...), a phase shifter connected between one of the magnetic heads and the carrier signal generator, mixer means for combining the reproduced signals of the two magnetic heads to provide a composite signal, a phase comparator for comparing the composite signal of the mixer means with the carrier signal, and a variable phase shifter located in either of the paths between the phase comparator and the mixer means and between the phase comparator and the carrier signal generator.
Claim 2
Dependent Claim
134 words
A displacement measuring instrument comprising a carrier signal generator, a magnetic scale having formed thereon magnetic gratings of fixed wavelength, two magnetic heads disposed in reading relationship with the magnetic scale and spaced apart from each other at a distance of (n+ 1/4) times the recorded wavelength of the magnetic gratings, (n being 0, 1, 2, 3,...), a phase shifter connected between one of the magnetic heads and the carrier signal generator, mixer means for combining the reproduced signals of the two magnetic heads to provide a composite signal, a phase comparator for comparing the composite signal of the mixer means with the carrier signal, and a variable phase shifter located in either of the paths between the phase comparator and the mixer means and between the phase comparator and the carrier signal generator.
Claim 3
Dependent Claim
138 words
A displacement measuring instrument comprising a magnetic scale with magnetic gratings of fixed wavelength formed thereon, a pair of magnetic heads mounted in reading relationship with said scale and spaced apart a distance of (n+ 1/4) times the recorded wavelength of the magnetic gratings (n being an integer including zero from zero to infinity), a generator supplying a signal to the first magnetic head, a pi /4 phase shifter receiving a signal from said generator and supplying a signal to the second magnetic head, combining means connected to the outputs of said magnetic heads, phase comparing means connected to the output of the combining means and to the output of the generator, and variable phase shifting means connected to one of the inputs to said phase comparing means to adjust the phase of one of said input signals.
Claim 4
Dependent Claim
138 words
A displacement measuring instrument comprising a magnetic scale with magnetic gratings of fixed wavelength formed thereon, a pair of magnetic heads mounted in reading relationship with said scale and spaced apart a distance of (n+ 1/4) times the recorded wavelength of the magnetic gratings (n being an integer including zero from zero to infinity), a generator supplying a signal to the first magnetic head, a pi /4 phase shifter receiving a signal from said generator and supplying a signal to the second magnetic head, combining means connected to the outputs of said magnetic heads, phase comparing means connected to the output of the combining means and to the output of the generator, and variable phase shifting means connected to one of the inputs to said phase comparing means to adjust the phase of one of said input signals.
Claim 5
Dependent Claim
22 words
A displacement measuring instrument according to claim 2 comprising a frequency divider connected between the generator and the pair of magnetic heads.
Claim 6
Dependent Claim
35 words
A displacement measuring instrument according to claim 3 wherein said combining means comprises a mixer, a filter connected to the output of the mixer, and a pulse former connected to the output of the filter.
Claim 7
Dependent Claim
22 words
A displacement measuring instrument according to claim 4 comprising a second pulse former connected between the generator and the phase comparing means.
Claim 8
Dependent Claim
24 words
A displacement measuring instrument according to claim 5 wherein said variable phasE shifting means is connected between said generator and said second pulse former.
Claim 9
Dependent Claim
32 words
A displacement measuring instrument according to claim 5 comprising a second filter connected to the output of the phase comparing means, and an indicator connected to the output of the second filter.
Claim 10
Dependent Claim
23 words
A displacement measuring instrument according to claim 5 wherein said variable phase shifting means is connected between said filter and said pulse former.
Claim 11
Dependent Claim
39 words
A displacement measuring instrument according to claim 8 comprising a motor means with its output shaft connected to said variable phase shifting means, and switch means for connecting the output of the phase comparing means to said motor means.
Claim 12
Independent Claim
62 words
The method of measuring displacement with a pair of magnetic heads and a magnetic scale having formed thereon magnetic gratings comprising applying a signal to said magnetic heads, detecting and combining signals from said magnetic heads, comparing the combined signal from said magnetic heads with the signal applied to the magnetic heads, including phase shifting one of the signals to be compared.
Claim 13
Independent Claim
62 words
The method of measuring displacement with a pair of magnetic heads and a magnetic scale having formed thereon magnetic gratings comprising applying a signal to said magnetic heads, detecting and combining signals from said magnetic heads, comparing the combined signal from said magnetic heads with the signal applied to the magnetic heads, including phase shifting one of the signals to be compared.
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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) | 1974-08-02 | 1975-02-01 | 1975-08-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-08-02 | 1979-02-01 | 1979-08-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-08-02 | 1983-02-01 | 1983-08-03 | $7700.00 | Window Closed / Lapsed |