US3943375A
Expired / Lapsed
US
⏱️ 0.0 years remaining
On-off switch with time delay
Assignee: GTE Sylvania Inc
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Filing: 1974-12-23
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Granted: 1976-03-09
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Expires: 1994-12-23
Abstract
Abstract An on-off switch having a time delayed "off" position provided by a series-connected PTC thermistor.
Inventors
- 👤 David V. Williamson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 03:36
CPC Classifications
H; H01; H01H; H01H43/00; H01H43/30; H01H43/308
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
146 words
A switch for an electrical circuit, said switch comprising: a common terminal adapted for connection to said circuit; selective switching means connected to said common terminal; at least first and second position contacts for selective engagement by said switching means, said first position contact being adapted for connecting to said circuit whereby upon engagement by said switching means a closed-circuit on condition can be provided; and a positive-temperature-coefficient thermistor connected between said second and first position contacts whereby, upon connection of said switch in said circuit and engagement of said second position contact by said switching means, said thermistor is series connected with said switch in said circuit; said thermistor being selected to delay deenergization of said circuit for a predetermined period of time upon actuation of said switching means from said first to said second position contact whereby a time delayed off function is provided.
Claim 2
Dependent Claim
146 words
A switch for an electrical circuit, said switch comprising: a common terminal adapted for connection to said circuit; selective switching means connected to said common terminal; at least first and second position contacts for selective engagement by said switching means, said first position contact being adapted for connecting to said circuit whereby upon engagement by said switching means a closed-circuit on condition can be provided; and a positive-temperature-coefficient thermistor connected between said second and first position contacts whereby, upon connection of said switch in said circuit and engagement of said second position contact by said switching means, said thermistor is series connected with said switch in said circuit; said thermistor being selected to delay deenergization of said circuit for a predetermined period of time upon actuation of said switching means from said first to said second position contact whereby a time delayed off function is provided.
Claim 3
Dependent Claim
40 words
The switch of claim 1 further including a third position contact for selective engagement by said switching means, said third position contact being an open circuit contact whereby upon engagement by said switching means on off condition can be provided.
Claim 4
Dependent Claim
25 words
The combination of claim 2 wherein said switch comprises a single-pole double-throw wall switch with an off position and is adapted for residential lighting circuits.
Claim 5
Dependent Claim
24 words
The switch of claim 1 wherein said delay time is substantially predetermined by selection of the zero-power resistance and switching temperature of said thermistor.
Claim 6
Dependent Claim
36 words
The switch of claim 4 wherein said thermistor is encapsulated in an insulating material, the mass of which is selected to extend the heat-up time of said thermistor, when energized, to thereby extend said delay time.
Claim 7
Dependent Claim
15 words
The switch of claim 1 wherein the switching temperature of said thermistor is approximately 60°C.
Claim 8
Dependent Claim
32 words
The switch of claim 6 wherein the zero power resistance of said thermistor at 25°C is about 27 ohms, and said thermistor has a voltage rating of up to 132 volts AC.
Claim 9
Dependent Claim
17 words
The switch of claim 7 wherein said thermistor is of a disc-type configuration and is epoxy coated.
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) | 1979-03-09 | 1979-09-08 | 1980-03-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-03-09 | 1983-09-08 | 1984-03-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-03-09 | 1987-09-08 | 1988-03-09 | $7700.00 | Window Closed / Lapsed |