Patent US3786354A successfully refreshed from Google Patents.
US3786354A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electromagnetic tachometer
Assignee: SPX Technologies Inc
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Filing: 1972-01-24
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Granted: 1974-01-15
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Expires: 1992-01-24
Abstract
Abstract A tachometer system in which a carrier signal is transmitted to a speed sensing and transmission-line-length compensating device. Bursts of the carrier signal are relayed by the device to a detector and comparator circuit where a signal is recovered indicating the rate at which objects pass the speed sensing device. A method of compensating for differences in transmission line length in different systems by tuning the speed sensing device to a resonant frequency greater than the frequency of the carrier signal. Increased transmission line length causes the resonant frequency of the line including the device to approach the frequency of the carrier signal and improve the gain of the transmission line.
Inventors
- 👤 R Lasky
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 21:29
CPC Classifications
G; G01; G01P; G01P3/00; G01P3/42; G01P3/44; G01P3/48; G01P3/481; G01P3/4802; G01P3/484
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
257 words
Apparatus for measuring the rotational speed of a rotating object comprising an oscillator for producing a carrier signal of known frequency, a transmitter circuit coupled to said oscillator, a receiver circuit spaced from said transmitter circuit by an air gap, a disc rotatably coupled to said rotating object and having circumferentially spaced means on its outer periphery extending into said air gap, said disc rotating in said air gap such that said spaced means alternately permit and inhibit transmission of said carrier signal across said air gap in bursts at a rate proportional to the speed of rotation of said disc, circuit means coupled to said receiving circuit for converting the bursts of carrier signal of greater and lesser strength to a signal having a repetition rate proportional to the rate of rotation of said disc, transmission lines of unknown combined length extending between said oscillator and said transmitter circuit and between said receiver circuit and said converting circuit means, at least one of said transmitter and receiver circuits being tuned to a resonant frequency such that the center resonant frequency of transmission lines of minimum combined length including said transmitter and receiver circuits is greater than the frequency of said carrier signal so that an increase in combined length of transmission lines causes the center resonant frequency of the transmission lines including transmitter and receiver circuits to approach the frequency of said carrier signal, whereby the tuning of said circuit compensates for the adverse effects on signal strength of the unknown combined length of transmission lines.
Claim 2
Dependent Claim
257 words
Apparatus for measuring the rotational speed of a rotating object comprising an oscillator for producing a carrier signal of known frequency, a transmitter circuit coupled to said oscillator, a receiver circuit spaced from said transmitter circuit by an air gap, a disc rotatably coupled to said rotating object and having circumferentially spaced means on its outer periphery extending into said air gap, said disc rotating in said air gap such that said spaced means alternately permit and inhibit transmission of said carrier signal across said air gap in bursts at a rate proportional to the speed of rotation of said disc, circuit means coupled to said receiving circuit for converting the bursts of carrier signal of greater and lesser strength to a signal having a repetition rate proportional to the rate of rotation of said disc, transmission lines of unknown combined length extending between said oscillator and said transmitter circuit and between said receiver circuit and said converting circuit means, at least one of said transmitter and receiver circuits being tuned to a resonant frequency such that the center resonant frequency of transmission lines of minimum combined length including said transmitter and receiver circuits is greater than the frequency of said carrier signal so that an increase in combined length of transmission lines causes the center resonant frequency of the transmission lines including transmitter and receiver circuits to approach the frequency of said carrier signal, whereby the tuning of said circuit compensates for the adverse effects on signal strength of the unknown combined length of transmission lines.
Claim 3
Dependent Claim
16 words
Apparatus as claimed in claim 1, wherein said minimum length transmission lines are of zero length.
Claim 4
Dependent Claim
42 words
Apparatus as claimed in claim 2 wherein said transmitter circuit is tuned to a resonant frequency greater than the frequency of said carrier signal and said receiver circuit is tuned to a resonant frequency no greater than that of said transmitter circuit.
Claim 5
Dependent Claim
19 words
Apparatus as claimed in claim 2 wherein said transmitter circuit and said receiver circuit are tuned to different frequencies.
Claim 6
Dependent Claim
21 words
Apparatus as claimed in claim 2 wherein said transmitter circuit and said receiver circuit are each tuned to the same frequency.
Claim 7
Dependent Claim
185 words
In a method of determining the speed of objects by transmitting a carrier signal in periodic bursts across an air gap from a transmitter circuit to a receiver circuit at a repetition rate proportional to the speed of said objects passing through said air gap, said carrier signal being conducted to said transmitter circuit and from said receiver circuit by transmission lines of unknown combined length, the improvement which comprises compensating for the effect on the strength of said carrier signal of the unknown combined length of transmission lines by tuning at least one of said transmitter and receiver circuits to a resonant frequency such that the resonant frequency of transmission lines of minimum combined length including said transmitter and receiver circuits is greater than the frequency of said carrier signal so that an increase in combined length of transmission lines causes the resonant frequency of the transmission lines including transmitter and receiver circuits to approach the frequency of said carrier signal, whereby the tuning of said circuit substantially compensates for the adverse effects on signal strength of the unknown combined length of transmission lines.
Claim 8
Dependent Claim
185 words
In a method of determining the speed of objects by transmitting a carrier signal in periodic bursts across an air gap from a transmitter circuit to a receiver circuit at a repetition rate proportional to the speed of said objects passing through said air gap, said carrier signal being conducted to said transmitter circuit and from said receiver circuit by transmission lines of unknown combined length, the improvement which comprises compensating for the effect on the strength of said carrier signal of the unknown combined length of transmission lines by tuning at least one of said transmitter and receiver circuits to a resonant frequency such that the resonant frequency of transmission lines of minimum combined length including said transmitter and receiver circuits is greater than the frequency of said carrier signal so that an increase in combined length of transmission lines causes the resonant frequency of the transmission lines including transmitter and receiver circuits to approach the frequency of said carrier signal, whereby the tuning of said circuit substantially compensates for the adverse effects on signal strength of the unknown combined length of transmission lines.
Claim 9
Dependent Claim
43 words
The improvement as claimed in claim 6 wherein said transmitter circuit is tuned to a resonant frequency greater than the frequency of said carrier signal and said receiver circuit is tuned to a resonant frequency no greater than that of said transmitter circuit.
Claim 10
Dependent Claim
185 words
A tachometer system in which a carrier signal is transmitted in periodic bursts across an air gap at a rate proportional to the speed of objecTs passing through said air gap, including an oscillator for generating said carrier signal, a speed sensing and transmission line length compensating device defining said air gap, circuit means for utilizing said periodic bursts of carrier signal to determine the speed of said objects, and transmission lines of unknown combined length for conducting said carrier signal between said oscillator, said device and said circuit means, said device comprising a transmitter circuit and a receiver circuit separated by said air gap to permit magnetic coupling therebetween, means for supporting said circuits to define said air gap, said air gap being dimensioned to permit the passage of said objects through the air gap so that coupling between said transmitter and receiver circuits is alternately permitted and prevented, at a rate proportional to the rate of passage of said objects, at least one of said transmitter and receiver circuits being tuned to a resonant frequency greater than the frequency of said carrier signal.
Claim 11
Dependent Claim
185 words
A tachometer system in which a carrier signal is transmitted in periodic bursts across an air gap at a rate proportional to the speed of objecTs passing through said air gap, including an oscillator for generating said carrier signal, a speed sensing and transmission line length compensating device defining said air gap, circuit means for utilizing said periodic bursts of carrier signal to determine the speed of said objects, and transmission lines of unknown combined length for conducting said carrier signal between said oscillator, said device and said circuit means, said device comprising a transmitter circuit and a receiver circuit separated by said air gap to permit magnetic coupling therebetween, means for supporting said circuits to define said air gap, said air gap being dimensioned to permit the passage of said objects through the air gap so that coupling between said transmitter and receiver circuits is alternately permitted and prevented, at a rate proportional to the rate of passage of said objects, at least one of said transmitter and receiver circuits being tuned to a resonant frequency greater than the frequency of said carrier signal.
Claim 12
Dependent Claim
45 words
A system as claimed in claim 8 wherein said transmitter circuit means is tuned to a resonant frequency greater than the frequency of said carrier signal and said receiver circuit is tuned to a resonant frequency no greater than that of said transmitter circuit means.
Claim 13
Dependent Claim
22 words
A system as claimed in claim 9 wherein said receiver circuit is tuned to the same resonant frequency as said transmitter circuit.
Claim 14
Dependent Claim
24 words
A system as claimed in claim 9 wherein each of said transmitter and receiver circuits includes a coil and a capacitor in parallel therewith.
Claim 15
Dependent Claim
37 words
A system as claimed in claim 8 wherein said support means includes a U-shaped enclosure, said transmitter and receiver circuits being located in the respective legs of said enclosure with the space therebetween defining said air gap.
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) | 1977-01-14 | 1977-07-16 | 1978-01-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-14 | 1981-07-16 | 1982-01-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-14 | 1985-07-16 | 1986-01-15 | $7700.00 | Window Closed / Lapsed |