US3872398A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Proximity sensor with adjustable hysteresis
Assignee: Olivetti SpA
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Filing: 1973-09-25
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Granted: 1975-03-18
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Expires: 1993-09-25
Abstract
Abstract A proximity sensor for use e.g., as a position transducer or a strobe, for metal parts. The sensor utilizes the change in the equivalent parallel resistance of an oscillator circuit as the metal part is relatively moved toward and away from the oscillatory circuit. Ready adjustment of the sensitivity of the sensor is provided by the use of adjustable resistors connected to the oscillatory circuit.
Inventors
- 👤 Alfredo Fausone
- 👤 Luigi Piglione
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 18:21
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/94; H03K17/945; H03K17/95; H03K17/952; H03K17/9537; H03K17/9542; H03K17/9547
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
295 words
A proximity sensor responsive to the relative change in location of a metal element comprising: an oscillator circuit including an inductance for inductive coupling with the metal element, a transistor amplifier and a direct current voltage source for furnishing operating voltages to the elements of the transistor, the collector of said transistor being connected to one terminal of said voltage source through said inductance, a capacitor connected across said inductance, a first resistor voltage divider connected across said source and having an intermediate point connected to the emitter of said transistor to determine the emitter resistance of said transistor, a second resistor voltage divider connected across said voltage source, the base of said transistor being regeneratively coupled to said inductance and being connected to an intermediate point of said second voltage divider, said oscillator being operable to furnish an oscillating voltage output responsive to change in location of the metal element, a demodulating stage connected to said oscillator to supply an output voltage of amplitude determined by the oscillating voltage output of the oscillator circuit, an output stage, each of said demodulating and output stages including a transistor, a first diode connected between the base of the demodulating transistor and the collector of the oscillator transistor, the base of the output transistor being connected to the collector of the demodulating transistor, a pair of output terminals respectively connected to the collector and emitter of the output transistor, and a regenerative feedback connection between the collector of the output transistor and the base of the demodulating transistor, and, means for adjusting the sensitivity of said oscillator circuit to relative change in location of the metal element comprising at least one variable resistance element in said first voltage divider which establishes emitter resistance of said oscillator transistor.
Claim 2
Dependent Claim
295 words
A proximity sensor responsive to the relative change in location of a metal element comprising: an oscillator circuit including an inductance for inductive coupling with the metal element, a transistor amplifier and a direct current voltage source for furnishing operating voltages to the elements of the transistor, the collector of said transistor being connected to one terminal of said voltage source through said inductance, a capacitor connected across said inductance, a first resistor voltage divider connected across said source and having an intermediate point connected to the emitter of said transistor to determine the emitter resistance of said transistor, a second resistor voltage divider connected across said voltage source, the base of said transistor being regeneratively coupled to said inductance and being connected to an intermediate point of said second voltage divider, said oscillator being operable to furnish an oscillating voltage output responsive to change in location of the metal element, a demodulating stage connected to said oscillator to supply an output voltage of amplitude determined by the oscillating voltage output of the oscillator circuit, an output stage, each of said demodulating and output stages including a transistor, a first diode connected between the base of the demodulating transistor and the collector of the oscillator transistor, the base of the output transistor being connected to the collector of the demodulating transistor, a pair of output terminals respectively connected to the collector and emitter of the output transistor, and a regenerative feedback connection between the collector of the output transistor and the base of the demodulating transistor, and, means for adjusting the sensitivity of said oscillator circuit to relative change in location of the metal element comprising at least one variable resistance element in said first voltage divider which establishes emitter resistance of said oscillator transistor.
Claim 3
Dependent Claim
79 words
The apparatus of claim 1 in which said first resistor voltage divider includes first, second and third resistors serially connected across said voltage source, the junction between the first and second resistors being connected to the emitter of the oscillator transistor, and a second diode connected between the collector of the output transistor and the junction between said second and third resistors, said second diode being poled to block conduction when the oscillator circuit is furnishing an oscillating voltage.
References Cited (Backward Citations)
US3469204A
Cited
US3747012A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-03-17 | 1978-09-16 | 1979-03-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-17 | 1982-09-16 | 1983-03-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-17 | 1986-09-16 | 1987-03-18 | $7700.00 | Window Closed / Lapsed |