Patent US3747010A successfully refreshed from Google Patents.
US3747010A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Power supply for oscillator circuit of contactless proximity indicator
Assignee: Individual
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Filing: 1972-09-21
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Granted: 1973-07-17
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Expires: 1992-09-21
Abstract
Abstract A contactless proximity sensor includes an oscillator which generates an output damped by the presence of a metal part whose approach is to be detected. The operating voltage for the oscillator is developed across a Zener diode which is connected in series with a high-ohmic resistance across a supply source, the resistance being shunted by an electronic switch shortcircuiting same under the control of a trigger amplifier upon a critical reduction in the amplitude of the oscillator output. Closure of the electronic switch does not materially affect the operation of the oscillator but actuates a current-responsive indicator, such as a relay, in its two-wire energizing circuit.
Inventors
- 👤 R Buck
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 16:42
CPC Classifications
G; G01; G01V; G01V3/00; G01V3/08; G01V3/10; G01V3/101; G01V3/102; H; H03; H03K; H03K17/00; H03K17/94; H03K17/945; H03K17/95; H03K17/951; H03K17/952; H03K17/9537; H03K17/9542; H03K17/9547
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
205 words
A contactless proximity sensor comprising: an oscillator having a tank circuit and two power-input terminals for generating oscillations of a predetermined amplitude in an output circuit in the absence of an extraneous metallic element, said oscillations varying in amplitude with the distance of such an extraneous element from said tank circuit; a Zener diode connected across said terminals, said Zener diode being part of a coupling network further including a high-ohmic resistor in series therewith and an electronic switch in parallel with said resistor; trigger means coupled to said output circuit for sensing the amplitude of said oscillations, said trigger means being connected to said switch for reversing same in response to a predetermined change in said amplitude, thereby effectively short-circuiting said resistor; a supply circuit connecting said coupling network across a source of operating current for said oscillator, the voltage drop across said Zener diode in both a normal and a reversed condition of said switch being sufficient to maintain said oscillator operative; and indicator means in said supply circuit responsive to changes in the condition of said switch to signal a predetermined minimum departure of said amplitude from its normal level representing an approach of said metallic element to within a specified distance.
Claim 2
Dependent Claim
205 words
A contactless proximity sensor comprising: an oscillator having a tank circuit and two power-input terminals for generating oscillations of a predetermined amplitude in an output circuit in the absence of an extraneous metallic element, said oscillations varying in amplitude with the distance of such an extraneous element from said tank circuit; a Zener diode connected across said terminals, said Zener diode being part of a coupling network further including a high-ohmic resistor in series therewith and an electronic switch in parallel with said resistor; trigger means coupled to said output circuit for sensing the amplitude of said oscillations, said trigger means being connected to said switch for reversing same in response to a predetermined change in said amplitude, thereby effectively short-circuiting said resistor; a supply circuit connecting said coupling network across a source of operating current for said oscillator, the voltage drop across said Zener diode in both a normal and a reversed condition of said switch being sufficient to maintain said oscillator operative; and indicator means in said supply circuit responsive to changes in the condition of said switch to signal a predetermined minimum departure of said amplitude from its normal level representing an approach of said metallic element to within a specified distance.
Claim 3
Dependent Claim
32 words
A proximity sensor as defined in claim 1 wherein said supply circuit comprises a two-wire line connected across an alternating-current supply and a rectifier bridge between said line and said coupling network.
Claim 4
Dependent Claim
16 words
A proximity sensor as defined in claim 1 wherein said trigger means comprises a snap-action amplifier.
Claim 5
Dependent Claim
39 words
A proximity sensor as defined in claim 3 wherein said amplifier comprises an output transistor with a base, an emitter and a collector, said emitter and collector being connected across said coupling network in series with a biasing resistance.
Claim 6
Dependent Claim
26 words
A proximity sensor as defined in claim 4 wherein said switch is a normally nonconductive thyristor having an anode gate circuit connected across said biasing resistance.
Claim 7
Dependent Claim
18 words
A proximity sensor as defined in claim 5 wherein said thyristor has its gate connected to said collector.
Claim 8
Dependent Claim
26 words
A proximity sensor as defined in claim 4 wherein said amplifier further includes rectifying means for said oscillations connected to the base of said output transistor.
Claim 9
Dependent Claim
34 words
A proximity sensor as defined in claim 7 wherein said rectifying means comprises an input transistor with a rectifying base circuit and with an emitter impedance connected to the base of said output transistor.
Claim 10
Dependent Claim
16 words
A proximity sensor as defined in claim 8 wherein said emitter impedance comprises a resistance/capacitance network.
Claim 11
Dependent Claim
21 words
A proximity sensor as defined in claim 8 wherein said rectifying base circuit includes a further transistor connected as a diode.
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) | 1976-07-16 | 1977-01-15 | 1977-07-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-16 | 1981-01-15 | 1981-07-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-16 | 1985-01-15 | 1985-07-17 | $7700.00 | Window Closed / Lapsed |