US3629649A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Threshold detector for incident radiation
Assignee: STMicroelectronics SRL
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Filing: 1969-11-24
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Granted: 1971-12-21
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Expires: 1989-11-24
Abstract
Abstract A resistance bridge, having one diagonal connected across a source of direct current, includes in its other diagonal a photodiode in series with the base/emitter circuits of two transistors of opposite conductivity types. One of these transistors controls a further two-transistor stage for operating a relay when the photodiode is illuminated; an armature of that relay exerts a latching or toggle effect by modifying the bias of two of the transistors to vary the sensitivity of the detector in a sense tending to maintain the relay in either its operated or its unoperated state.
Inventors
- 👤 Giorgio Del Zotto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 21:13
CPC Classifications
B; B60; B60Q; B60Q1/00; B60Q1/02; B60Q1/04; B60Q1/14; B60Q1/1415; B60Q1/1423; H; H03; H03K; H03K17/00; H03K17/51; H03K17/78; H03K17/795; B60Q2300/00; B60Q2300/30; B60Q2300/31; B60Q2300/314
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
187 words
A circuit arrangement for detecting incident radiation, comprising a source of direct current; a resistance bridge having an input diagonal connected across said source and further having an output diagonal with a minor fraction of the source voltage developed thereacross; a first and a second transistor of opposite conductivity types each with a base, an emitter and a collector, said transistors having their base/emitter circuits connected in bucking relationship in said output diagonal between a first terminal feeding the base of said first transistor and a second terminal tied to the emitter of said second transistor; a radiation-sensitive resistance element connected between the base of said first transistor and said first terminal; a resistor common to said base/emitter circuits connected in series with the emitter/collector circuit of said first transistor across said input diagonal; amplifier means having an input circuit connected across said source in series with the collector of said second transistor; and a load circuit including relay means connected to the output of said amplifier means for alternate energization and deenergization in response to variations in the level of radiation incident upon said resistance element.
Claim 2
Dependent Claim
187 words
A circuit arrangement for detecting incident radiation, comprising a source of direct current; a resistance bridge having an input diagonal connected across said source and further having an output diagonal with a minor fraction of the source voltage developed thereacross; a first and a second transistor of opposite conductivity types each with a base, an emitter and a collector, said transistors having their base/emitter circuits connected in bucking relationship in said output diagonal between a first terminal feeding the base of said first transistor and a second terminal tied to the emitter of said second transistor; a radiation-sensitive resistance element connected between the base of said first transistor and said first terminal; a resistor common to said base/emitter circuits connected in series with the emitter/collector circuit of said first transistor across said input diagonal; amplifier means having an input circuit connected across said source in series with the collector of said second transistor; and a load circuit including relay means connected to the output of said amplifier means for alternate energization and deenergization in response to variations in the level of radiation incident upon said resistance element.
Claim 3
Dependent Claim
62 words
A circuit arrangement as defined in claim 1 wherein said resistance element is a photodiode, further comprising an impedance element of substantially the same thermal coefficient of resistance as said photodiode connected in an arm of said bridge as part of a temperature-compensating circuit extending from said first terminal to the junction of said base/emitter circuits by way of said common resistor.
Claim 4
Dependent Claim
16 words
A circuit arrangement as defined in claim 2 wherein said compensating element is a germanium diode.
Claim 5
Dependent Claim
43 words
A circuit arrangement as defined in claim 1, further comprising biasing means for said amplifier means and switch means controlled by said relay means for modifying said biasing means in a sense tending to maintain the state of energization of said relay means.
Claim 6
Dependent Claim
60 words
A circuit arrangement as defined in claim 4 wherein said amplifier means comprises a third and a fourth transistor connected in cascade and provided each with a base, an emitter and a collector, said input circuit including the base and emitter of said third transistor, said biasing means including a feedback resistance in the base/emitter circuit of said fourth transistor.
Claim 7
Dependent Claim
35 words
A circuit arrangement as defined in claim 5 wherein said feedback resistance is connectable by said switch means in series with at least part of an arm of said bridge extending to said second terminal.
Claim 8
Dependent Claim
21 words
A circuit arrangement as defined in claim 5, further comprising a capacitance bridged across the base/collector circuit of said third transistor.
Claim 9
Dependent Claim
24 words
A circuit arrangement as defined in claim 5 wherein said third and fourth transistors are of the same conductivity type as said first transistor.
Claim 10
Dependent Claim
29 words
A circuit arrangement as defined in claim 1 wherein the emitter of said first transistor is connected to the base of said second transistor and to said cOmmon resistor.
Claim 11
Dependent Claim
40 words
A circuit arrangement as defined in claim 1 wherein said resistance element is sensitive to luminous radiation, said load circuit includes a lamp connected for energization by said relay means upon the reduction of ambient light below a predetermined threshold.
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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) | 1974-12-20 | 1975-06-21 | 1975-12-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-12-20 | 1979-06-21 | 1979-12-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-12-20 | 1983-06-21 | 1983-12-21 | $7700.00 | Window Closed / Lapsed |