US3660688A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Static switch
Assignee: Delta Venture
•
Filing: 1970-12-07
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Granted: 1972-05-02
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Expires: 1990-12-07
Abstract
Abstract A touch switch circuit is disclosed for connecting a load to a source of AC potential in response to operator contact with a touch probe. A normally nonconducting SCR is in series connection with a load and source of AC potential. Means are present for clamping the gate of the SCR below its normal turn-on level, and for removing the said clamp in response to operator contact with said touch terminal whereby to fire said SCR and activate said load.
Inventors
- 👤 Robert W Evans
- 👤 Stuart P Jackson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 01:05
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/94; H03K17/96; H03K17/962; H03K17/51; H03K17/56; H03K17/72; H03K17/725
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
143 words
A touch switch circuit for connecting a load to a source of AC potential, comprising: a normally nonconducting thyristor in series connection with said load and said source of AC potential; means to provide full wave rectified unipolar drive to said thyristor; a field effect transistor (FET); means to clamp the gate of said thyristor below its normal turnon level, said field effect transistor (FET) conducting with zero bias connected across the gate and caThode of said thyristor; and sensing circuit means including a touch terminal electrically connected to said thyristor to remove said clamp in response to operator contact with said touch terminal whereby to fire said thyristor and activate said load, said sensing circuit means being connected to the gate of said FET to render said FET conductive after contact with said touch terminal is established, whereby to remove said clamp.
Claim 2
Dependent Claim
143 words
A touch switch circuit for connecting a load to a source of AC potential, comprising: a normally nonconducting thyristor in series connection with said load and said source of AC potential; means to provide full wave rectified unipolar drive to said thyristor; a field effect transistor (FET); means to clamp the gate of said thyristor below its normal turnon level, said field effect transistor (FET) conducting with zero bias connected across the gate and caThode of said thyristor; and sensing circuit means including a touch terminal electrically connected to said thyristor to remove said clamp in response to operator contact with said touch terminal whereby to fire said thyristor and activate said load, said sensing circuit means being connected to the gate of said FET to render said FET conductive after contact with said touch terminal is established, whereby to remove said clamp.
Claim 3
Dependent Claim
12 words
Apparatus in accordance with claim 1 wherein said thyristor is an SCR.
Claim 4
Dependent Claim
57 words
Apparatus in accordance with claim 1 wherein said sensing circuit means includes means to rectify 60 Hz voltage picked up by said touch terminal when it is touched, and apply said voltage to a capacitor across said field effect transistor gate, said voltage across said capacitor acting to render said FET nonconductive to remove said SCR clamp.
Claim 5
Dependent Claim
29 words
Apparatus in accordance with claim 3 wherein a diode bridge connected to said source of AC potential provides said unipolar drive for said SCR and said sensing circuit means.
Claim 6
Dependent Claim
42 words
Apparatus in accordance with claim 4 further including transistor means connected across said SCR, adapted for clamping said gate potential at said cathode potential for a period after said FET is rendered nonconductive whereby to provide a start-up delay for said SCR.
Claim 7
Dependent Claim
31 words
Apparatus in accordance with claim 5 further including a series RC network across said load and AC potential source for providing noise suppression to prevent line transients from triggering said SCR.
References Cited (Backward Citations)
US3530312A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-05-02 | 1975-11-01 | 1976-05-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-02 | 1979-11-01 | 1980-05-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-02 | 1983-11-01 | 1984-05-02 | $7700.00 | Window Closed / Lapsed |