US3878439A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Light controlled circuit
Assignee: Sycon Corp
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Filing: 1973-03-29
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Granted: 1975-04-15
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Expires: 1993-03-29
Abstract
Abstract The circuit includes a phototransistor, a Schmitt trigger operable in response to a changing condition of the phototransistor, an amplifying and timing subcircuit coupled to the Schmitt trigger, a uni-junction transistor acting as a threshold detector and a relay or other utilization circuit coupled to the amplifier and threshold detector circuits. The circuit may be set so that the timing subcircuit starts operation when the phototransistor changes from an illuminated condition to a non-illuminated condition, or vice versa. In another form the circuit does not contain a timing subcircuit but instead responds to a change in the phototransistor from an illuminated state to a non-illuminated state.
Inventors
- 👤 David F Crozier
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 07:08
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/30; H03K17/51; H03K17/78; H03K17/795; H03K17/7955
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
166 words
A circuit comprising: a. a branch including a load resistor and light-sensitive means for generating output signals corresponding to the light input condition of said light sensitive means, b. a Schmitt trigger circuit coupled to the output of said light-sensitive means, said trigger circuit including first and second switching means coupled to one another, said first switching means being coupled to said load resistor and changing condition whenever said light-sensitive means changes condition, said second switching means changing condition in response to a change in condition of said first switching means, said trigger circuit being directly coupled to said branch, c. a third switching means coupled to said second switching means which changes condition in response to a change in condition of said second switching means, and d. a utilization circuit coupled to said third switching means which is actuated in response to a predetermined change in the condition of said third switching means, said utilization circuit remaining acutated until said light-sensitive means next changes condition.
Claim 2
Dependent Claim
166 words
A circuit comprising: a. a branch including a load resistor and light-sensitive means for generating output signals corresponding to the light input condition of said light sensitive means, b. a Schmitt trigger circuit coupled to the output of said light-sensitive means, said trigger circuit including first and second switching means coupled to one another, said first switching means being coupled to said load resistor and changing condition whenever said light-sensitive means changes condition, said second switching means changing condition in response to a change in condition of said first switching means, said trigger circuit being directly coupled to said branch, c. a third switching means coupled to said second switching means which changes condition in response to a change in condition of said second switching means, and d. a utilization circuit coupled to said third switching means which is actuated in response to a predetermined change in the condition of said third switching means, said utilization circuit remaining acutated until said light-sensitive means next changes condition.
Claim 3
Dependent Claim
105 words
The circuit according to claim 1 wherein all of said switching means are solid state devices, wherein said utilization circuit is a coil and is in series with said third switching means, wherein there is additionally provided a timing subcircuit coupled to said second and third switching means which commences a timing operation as soon as said second switching means becomes non-conductive and further wherein there is a voltage-threshold-detection subcircuit coupled to said third switching means for preventing appreciable conduction through the latter until at least a predetermined minimal voltage appears on a selected electrode of said third means, said conduction thereupon energizing said coil.
References Cited (Backward Citations)
US3113250A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-04-14 | 1978-10-14 | 1979-04-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-14 | 1982-10-14 | 1983-04-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-14 | 1986-10-14 | 1987-04-15 | $7700.00 | Window Closed / Lapsed |