US3678291A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Solid state relay
Assignee: Sanmina Corp
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Filing: 1970-05-18
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Granted: 1972-07-18
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Expires: 1990-05-18
Abstract
Abstract A solid-state switching device capable of replacing mechanical relays. When the relay is conducting rated load current, a single saturated transistor carries the current with a very low voltage drop. When the load current rises above a pre-determined level, the load-carrying circuit automatically becomes a modified Darlington circuit, which is capable of carrying substantial overloads without being damaged, and with voltage drops within a desirable range. Optionally, means are provided for disabling the load circuit and, in effect, opening the relay, when a certain level of overload current is reached, thereby turning the device into a circuit-breaker.
Inventors
- 👤 Ronald J Coe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 14:58
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/08; H03K17/082; H03K17/0826; H03F; H03F1/00; H03F1/52; H03K17/51; H03K17/78; H03K17/795
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
73 words
A relay device comprising output terminal means, semiconductor means for selectively providing a very low impedance path between said load terminal means and an electrical source, said semiconductor means comprising a current amplifier having at least two stages, means for selectively enabling said current amplifier, and means for selectively disabling at least one stage of said current amplifier in response to the flow of relatively low-level load currents to said load terminal means.
Claim 2
Dependent Claim
73 words
A relay device comprising output terminal means, semiconductor means for selectively providing a very low impedance path between said load terminal means and an electrical source, said semiconductor means comprising a current amplifier having at least two stages, means for selectively enabling said current amplifier, and means for selectively disabling at least one stage of said current amplifier in response to the flow of relatively low-level load currents to said load terminal means.
Claim 3
Dependent Claim
24 words
A relay device as in claim 1 in which said current amplifier forms a substantially saturated semiconductor switch when said one stage is disabled.
Claim 4
Dependent Claim
29 words
A relay device as in claim 1 in which said current amplifier comprises a Darlington amplifier during the flow of relatively high-level load currents to said load terminal means.
Claim 5
Dependent Claim
20 words
A relay device as in claim 1 including a constant current source for supplying bias current to said current amplifier.
Claim 6
Dependent Claim
28 words
A device as in claim 1 including circuit-breaker means for selectively disabling both of said stages in response to the flow of load currents above a pre-determined level.
Claim 7
Dependent Claim
67 words
A switching device comprising output terminal means, a Darlington amplifier circuit for providing a very low impedance path for connecting said output terminal means to an electrical source, means for enabling said amplifier circuit in response to an input signal, and means for selectively disabling one stage of said amplifier circuit when the flow of current to said output terminal means is below a pre-determined minimum value.
Claim 8
Dependent Claim
67 words
A switching device comprising output terminal means, a Darlington amplifier circuit for providing a very low impedance path for connecting said output terminal means to an electrical source, means for enabling said amplifier circuit in response to an input signal, and means for selectively disabling one stage of said amplifier circuit when the flow of current to said output terminal means is below a pre-determined minimum value.
Claim 9
Dependent Claim
45 words
A device as in claim 6 in which said Darlington amplifier circuit includes a driver stage and a second stage, each stage including a transistor, the emitter-collector path of said second-stage transistor being connected between said output terminal means and a terminal for said source.
Claim 10
Dependent Claim
40 words
A device as in claim 7 in which said disabling means comprises unidirectional conduction means connected between the collector leads of said transistors and adapted to conduct only when the load current through said device rises to a pre-determined value.
Claim 11
Dependent Claim
28 words
A device as in claim 6 including circuit-breaker means for selectively disabling both of said stages in response to the flow of load currents above a pre-determined level.
Claim 12
Dependent Claim
25 words
A device as in claim 6 including isolator means at the input of said device for conductively isolating said input from said output terminal means.
Claim 13
Dependent Claim
32 words
A device as in claim 10 in which said isolator means comprises a light-emitting diode positioned to shine light on a photo-diode when said light-emitting diode is energized by an input signal.
References Cited (Backward Citations)
US3126490A
Cited
US2928009A
Cited
US2949543A
Cited
US3210561A
Cited
US3359483A
Cited
US3508162A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-07-18 | 1976-01-17 | 1976-07-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-07-18 | 1980-01-17 | 1980-07-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-07-18 | 1984-01-17 | 1984-07-18 | $7700.00 | Window Closed / Lapsed |