US3867641A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ac load actuation circuit
Assignee: 3M Co
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Filing: 1974-02-13
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Granted: 1975-02-18
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Expires: 1994-02-13
Abstract
Abstract A photon coupler including a phototransistor and an LED are connected to a thyristor load switching element for triggering the thyristor to switch a load into connection with an AC source in response to actuation of the LED by a low level DC control signal from a logic circuit. A capacitor is connected in the circuit to provide a triggering current through the phototransistor which leads the load voltage in phase to thereby provide a maximum level triggering current near the zero voltage crossing point for the load, thus providing maximum available power to the load while minimizing RF interference and power dissipation. A zener diode is connected to the phototransistor and to the capacitor for limiting the level of the voltage across the phototransistor due to current flow from the capacitor when power is first applied to the load actuation circuit thereby to protect the phototransistor and also thereby to enable triggering of the SCR only in response to the gating of the phototransistor due to the actuation of the LED.
Inventors
- 👤 John E Collins
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 03:30
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/13; H03K17/136; H03K17/51; H03K17/78; H03K17/79; Y; Y10; Y10S; Y10S323/00; Y10S323/902
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
203 words
An AC load actuation circuit comprising a thyristor load switching element for switching a load into connection with an AC source and a photon coupler for triggering the thyristor load switching element, wherein the improvement comprises in combination; said photon coupler comprising a light emitting element and a photosensitive triggering element which is connected to the gate of said thyristor load switching element for triggering the thyristor in response to the light emitting element being actuated by a control signal; a capacitor connected in the load actuation circuit for providing a triggering current through the photosensitive element to the thyristor gate which leads the load voltage in phase to thereby provide a maximum level triggering current near the zero voltage crossing point for the load; and a zener diode connected to the photosensitive element and to the capacitor for limiting the level of the voltage across the photosensitive triggering element due to current flow from the capacitor when power is first applied to the load actuation circuit thereby to protect the photosensitive triggering element and also thereby to enable triggering of the thyristor only in response to the gating of the photosensitive triggering element due to the actuation of the light emitting element.
Claim 2
Dependent Claim
203 words
An AC load actuation circuit comprising a thyristor load switching element for switching a load into connection with an AC source and a photon coupler for triggering the thyristor load switching element, wherein the improvement comprises in combination; said photon coupler comprising a light emitting element and a photosensitive triggering element which is connected to the gate of said thyristor load switching element for triggering the thyristor in response to the light emitting element being actuated by a control signal; a capacitor connected in the load actuation circuit for providing a triggering current through the photosensitive element to the thyristor gate which leads the load voltage in phase to thereby provide a maximum level triggering current near the zero voltage crossing point for the load; and a zener diode connected to the photosensitive element and to the capacitor for limiting the level of the voltage across the photosensitive triggering element due to current flow from the capacitor when power is first applied to the load actuation circuit thereby to protect the photosensitive triggering element and also thereby to enable triggering of the thyristor only in response to the gating of the photosensitive triggering element due to the actuation of the light emitting element.
Claim 3
Dependent Claim
18 words
An AC load actuation circuit according to claim 1, wherein the thyristor load switching element comprises an SCR.
Claim 4
Dependent Claim
17 words
An AC load actuation circuit according to claim 1, wherein the light emitting element comprises an LED.
Claim 5
Dependent Claim
17 words
An AC load actuation circuit according to claim 1, wherein the photosensitive triggering element comprises a phototransistor.
Claim 6
Dependent Claim
17 words
An AC load actuation circuit according to claim 4, wherein the light emitting element comprises an LED.
Claim 7
Dependent Claim
56 words
An AC load actuation circuit according to claim 4, further comprising a second capacitor connected between the emitter and the base of the phototransistor for inhibiting triggering of the thyristor when power is first applied to the load actuation circuit by preventing amplification of displacement current flowing from the collector to the base of the phototransistor.
Claim 8
Dependent Claim
35 words
An AC load actuation circuit according to claim 1, further comprising a logic circuit connected to the light emitting means for providing a DC signal as the control signal for actuating the light emitting means.
Claim 9
Dependent Claim
186 words
An AC load actuation circuIt comprising an SCR load switching element for switching a load into connection with an AC source and a photon coupler for triggering the SCR load switching element, wherein the improvement comprises in combination; said photon coupler comprising an LED and a phototransistor which is connected to the gate of said SCR load switching element for triggering the SCR in response to the LED being actuated by a control signal; a capacitor connected in the load actuation circuit for providing a triggering current through the phototransistor to the SCR gate which leads the load voltage in phase to thereby provide a maximum level triggering current near the zero voltage crossing point for the load; and a zener diode connected to the phototransistor and to the capacitor for limiting the level of the voltage across the phototransistor due to current flow from the capacitor when power is first applied to the load actuation circuit to thereby protect the phototransistor and to thereby enable triggering of the SCR only in response to the gating of the phototransistor due to the actuation of the LED.
Claim 10
Dependent Claim
186 words
An AC load actuation circuIt comprising an SCR load switching element for switching a load into connection with an AC source and a photon coupler for triggering the SCR load switching element, wherein the improvement comprises in combination; said photon coupler comprising an LED and a phototransistor which is connected to the gate of said SCR load switching element for triggering the SCR in response to the LED being actuated by a control signal; a capacitor connected in the load actuation circuit for providing a triggering current through the phototransistor to the SCR gate which leads the load voltage in phase to thereby provide a maximum level triggering current near the zero voltage crossing point for the load; and a zener diode connected to the phototransistor and to the capacitor for limiting the level of the voltage across the phototransistor due to current flow from the capacitor when power is first applied to the load actuation circuit to thereby protect the phototransistor and to thereby enable triggering of the SCR only in response to the gating of the phototransistor due to the actuation of the LED.
Claim 11
Dependent Claim
55 words
An AC load actuation circuit to claim 8, further comprising a second capacitor connected between the emitter and the base of the phototransistor for inhibiting triggering of the SCR when power is first applied to the load actuation circuit by preventing amplification of displacement current flowing from the collector to the base of the phototransistor.
Claim 12
Dependent Claim
31 words
An AC load actuation circuit according to claim 8, further comprising a logic circuit connected to the LED for providing a DC signal as the control signal for actuating the LED.
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) | 1978-02-17 | 1978-08-19 | 1979-02-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-02-17 | 1982-08-19 | 1983-02-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-02-17 | 1986-08-19 | 1987-02-18 | $7700.00 | Window Closed / Lapsed |