US4841245A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Displacement sensor having multiplexed dual tank circuits
Assignee: Measurement Specialties Inc
•
Filing: 1987-01-29
•
Granted: 1989-06-20
•
Expires: 2007-01-29
Abstract
Abstract Non-contacting sensor apparatus having two tank circuits from which an indication of the position of the moving part of the sensor is developed by measuring the relative resonance frequencies of the two tank circuits. As the moving part of the sensor changes position, the relative resonance frequencies of the two tank circuits change. The outputs of the two tank circuits are multiplexed and drive a pulse generator which develops a first series of pulses having a repetition rate which corresponds to the resonance frequency of one of the tank circuits and a second series of pulses having a repetition rate which corresponds to the resonance frequency of the other tank circuit. The relative times required to count the same number of pulses of each series of pulses provides an indication of the position of the moving part of the sensor.
Inventors
- 👤 David Fiori, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 03:19
CPC Classifications
G; G01; G01D; G01D5/00; G01D5/12; G01D5/243
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
312 words
Sensor apparatus comprising: a sensor having first and second tank circuits and a movable metal member; means for moving said movable metal member, relative to a portion of each of said first and second tank circuits, in accordance with changes in a parameter being monitored, to change the relative resonant frequencies of said first and second tank circuits; and circuit means, responsive to changes in the relative resonant frequencies of said first and second tank circuits, for developing indications of changes in said parameter being monitored, said circuit means including; (a) a pulse generator for producing a first series of pulses having a repetition rate related to the resonant frequency of said first tank circuit and a second series of pulses having a repetition rate related to the resonant frequency of said second tank circuit; (b) a counter, responsive to said first and said second series of pulses, for counting a prescribed number of pulses of said first series and a prescribed number of pulses of said second series and for developing a first counter output pulse having a duration related to the time required to count said first series prescribed number of pulses and a second counter output pulse having a duration related to the time required to count said second series prescribed number of pulses; (c) tank circuit switching means, responsive to said counter output pulses, for connecting said first tank circuit to said pulse generator for the duration of said first counter output pulse and for connecting said second tank circuit to said pulse generator for the duration of said second counter output pulse; and (d) means, responsive to said counter output pulses, for developing an output indication of the relative time durations required for counting said prescribed number of pulses of said first series of pulses and said prescribed number of pulses of said second series of pulses.
Claim 2
Dependent Claim
312 words
Sensor apparatus comprising: a sensor having first and second tank circuits and a movable metal member; means for moving said movable metal member, relative to a portion of each of said first and second tank circuits, in accordance with changes in a parameter being monitored, to change the relative resonant frequencies of said first and second tank circuits; and circuit means, responsive to changes in the relative resonant frequencies of said first and second tank circuits, for developing indications of changes in said parameter being monitored, said circuit means including; (a) a pulse generator for producing a first series of pulses having a repetition rate related to the resonant frequency of said first tank circuit and a second series of pulses having a repetition rate related to the resonant frequency of said second tank circuit; (b) a counter, responsive to said first and said second series of pulses, for counting a prescribed number of pulses of said first series and a prescribed number of pulses of said second series and for developing a first counter output pulse having a duration related to the time required to count said first series prescribed number of pulses and a second counter output pulse having a duration related to the time required to count said second series prescribed number of pulses; (c) tank circuit switching means, responsive to said counter output pulses, for connecting said first tank circuit to said pulse generator for the duration of said first counter output pulse and for connecting said second tank circuit to said pulse generator for the duration of said second counter output pulse; and (d) means, responsive to said counter output pulses, for developing an output indication of the relative time durations required for counting said prescribed number of pulses of said first series of pulses and said prescribed number of pulses of said second series of pulses.
Claim 3
Dependent Claim
52 words
Sensor apparatus according to claim 1, wherein said first and second tank circuits have a single capacitor which is connected to said pulse generator and is switched by said tank circuit switching means between first and second inductance coils to form, in time alternating sequence, said first and said second tank circuits.
Claim 4
Dependent Claim
51 words
Sensor apparatus according to claim 1, wherein said first and said second tank circuits have a single inductance coil which is connected to said pulse generator and is switched by said switching means between first and second capacitors to form, in timed alternating sequence, said first and said second tank circuits.
Claim 5
Dependent Claim
39 words
Sensor apparatus according to claim 1, wherein said first and said second tank circuits each have an inductance coil and capacitor and said first and said second tank circuits are connected, in timed alternating sequence, to said pulse generator.
Claim 6
Dependent Claim
47 words
Sensor apparatus according to claim 1, wherein said indicating means include integrating means, responsive to said counter output signal, for developing an integration signal comprised of a rising portion developed from said first counter output pulse and a decaying portion developed from said second counter output pulse.
Claim 7
Dependent Claim
119 words
Sensor apparatus according to claim 5, wherein: (a) said indicating means further include (i) first switching means for selectively connecting said counter to said integrating means, (ii) a capacitor, and (iii) second switching means for selectively connecting said integrating means to said capacitor; and (b) said circuit means further include timing means for supplying (i) a first control signal to said first switching means to disconnect said counter from said integrating means and interrupt development of said integration signal, and (ii) a second control signal to said second switching means to connect said integrating means to said capacitor to transfer the level of said integration signal to said capacitor during selected interruptions of the development of said integration signal.
Claim 8
Dependent Claim
24 words
Sensor apparatus according to claim 6, wherein the development of said integration signal is interrupted at the mid-point of said rising and decaying portions.
Claim 9
Dependent Claim
237 words
Sensor apparatus according to claim 1, wherein: (a) said counter includes means for supplying an inverted version of said counter output signal; (b) said indicating means include (i) a first integration circuit responsive to said counter output signal for developing a first integration signal composed of a rising portion developed from said first counter output pulse and a decaying portion from said second counter output pulse, (ii) a second integration circuit, responsive to said inverted version of said counter output signal, for developing a second integration signal comprised of a decaying portion from an inverted version of said first counter output pulse and a rising portion from an inverted version of said second counter output pulse, (iii) first switching means for selectively connecting said counter to said first and second integration circuits, (iv) a capacitor, and (v) second switching means for selectively connecting said first and said second integration circuits to said capacitor; and (c) said circuit means further include timing means for supplying (i) a first control signal to said first switching means to disconnect said counter from said first and said second integration circuits and interrupt development of said integration signals, and (ii) a second control signal to said second switching means to connect said first and said second integration circuits to said capacitor to transfer the levels of said integration circuits to said capacitor during selected interruptions of the development of said integration signals.
Claim 10
Dependent Claim
24 words
Sensor apparatus according to claim 8, wherein the development of said integration signals is interrupted at the mid-points of said rising and decaying portions.
Claim 11
Dependent Claim
56 words
Sensor apparatus according to claim 1, wherein said tank circuit switching means are responsive to said first and second counter output pulses and include control means for delaying connecting said first and second tank circuits to said pulse generator for fixed periods of time following the terminations of said first and said second counter output pulses.
Claim 12
Dependent Claim
26 words
Sensor apparatus according to claim 1, wherein said fixed periods of time following said terminations of said first and said second counter output pulses are different.
References Cited (Backward Citations)
US3891918A
Cited
US3851242A
Cited
US3967064A
Cited
US4013911A
Cited
US4008457A
Cited
US4063206A
Cited
US4156221A
Cited
US4053849A
Cited
US4134065A
Cited
US4170311A
Cited
US4282485A
Cited
US4349746A
Cited
US4503922A
Cited
US4663589A
Cited
US4667158A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-06-19 | 1992-12-19 | 1993-06-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-06-19 | 1996-12-19 | 1997-06-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-06-19 | 2000-12-19 | 2001-06-20 | $7700.00 | Window Closed / Lapsed |