Patent US3895241A successfully refreshed from Google Patents.
US3895241A
Expired / Lapsed
US
⏱️ 0.0 years remaining
LED coupled switching circuits
Assignee: SILICON POWER CUBE Corp
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Filing: 1974-05-06
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Granted: 1975-07-15
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Expires: 1994-05-06
Abstract
Abstract LED coupled switching circuits are provided with at least two solid state light-emitting source devices which activate corresponding light-responsive switching devices to produce outputs related to the state of excitation of the solid state light sources. At least one of the light-responsive switching devices in the output circuit is connected in Darlington type arrangements with a power transistor.
Inventors
- 👤 David Cooper
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 18:30
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/51; H03K17/78; H03K17/79; H03K17/795; H03K17/7955
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
168 words
A switching circuit comprising, in combination: first and second light-emitting devices having first and second sets of terminals; first and second photoresponsive semiconductor devices optically coupled to said first and second light-emitting devices respectively; said first and sEcond photoresponsive semiconductor devices being operable between conductive and nonconductive conditions in response to light output variations from their said respective first and second light-emitting devices; said first photoresponsive semiconductor device comprising a first phototransistor having emitter and collector electrodes; and a power transistor having emitter, collector and base electrodes; said first phototransistor and said power transistor connected in a Darlington configuration, whereby their said collector electrodes are connected to one another, and whereby the emitter electrode of said first phototransistor is connected to the base of said power transistor; said second photoresponsive semiconductor device having first and second electrodes connected in series with said collector and emitter electrodes of said first phototransistor; said first electrode of said second photoresponsive semiconductor device connected to said base electrode of said power transistor.
Claim 2
Dependent Claim
168 words
A switching circuit comprising, in combination: first and second light-emitting devices having first and second sets of terminals; first and second photoresponsive semiconductor devices optically coupled to said first and second light-emitting devices respectively; said first and sEcond photoresponsive semiconductor devices being operable between conductive and nonconductive conditions in response to light output variations from their said respective first and second light-emitting devices; said first photoresponsive semiconductor device comprising a first phototransistor having emitter and collector electrodes; and a power transistor having emitter, collector and base electrodes; said first phototransistor and said power transistor connected in a Darlington configuration, whereby their said collector electrodes are connected to one another, and whereby the emitter electrode of said first phototransistor is connected to the base of said power transistor; said second photoresponsive semiconductor device having first and second electrodes connected in series with said collector and emitter electrodes of said first phototransistor; said first electrode of said second photoresponsive semiconductor device connected to said base electrode of said power transistor.
Claim 3
Dependent Claim
15 words
The circuit of claim 1 wherein said second photoresponsive semiconductor device is a second phototransistor.
Claim 4
Dependent Claim
14 words
The circuit of claim 1 wherein said second photoresponsive semiconductor device is a thyristor.
Claim 5
Dependent Claim
12 words
The circuit of claim 1 wherein said phototransistor is an NPN transistor.
Claim 6
Dependent Claim
11 words
The circuit of claim 2 wherein said phototransistors are NPN transistors.
Claim 7
Dependent Claim
16 words
The circuit of claim 3 which further includes a diode connected in series with said thyristor.
Claim 8
Dependent Claim
17 words
The circuit of claim 1 which further includes a diode connected in series with said power transistor.
Claim 9
Dependent Claim
21 words
The circuit of claim 6 wherein said thyristor and said diode are connected in closed series relation with said first phototransistor.
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) | 1978-07-14 | 1979-01-13 | 1979-07-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-07-14 | 1983-01-13 | 1983-07-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-07-14 | 1987-01-13 | 1987-07-15 | $7700.00 | Window Closed / Lapsed |