US3597590A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electric blanket control
Assignee: Nortel Networks Ltd
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Filing: 1969-02-12
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Granted: 1971-08-03
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Expires: 1989-02-12
Abstract
Abstract An electronic control for an electric blanket or other heated device in which the heating element of the blanket senses the ambient temperature and the other elements of the control are separated from the heating element so that the components of the control are less susceptible to sensing change in ambient temperature near the blanket. The electronic control circuit controls current to the heating element of the blanket by gating an SCR at the zero crossings of the applied voltage so as to prevent radiofrequency interference which would occur if the SCR were switched at other than the zero crossings. Unidirectional current means is connected in a bridge circuit which controls the gating of the SCR so that the temperature coefficients of the components in the two legs of the bridge circuit are balanced enhancing temperature compensation.
Inventors
- 👤 Bobby R Fleming
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 23:41
CPC Classifications
H; H05; H05B; H05B1/00; H05B1/02; H05B1/0227; H05B1/0252; H05B1/0272; G; G05; G05D; G05D23/00; G05D23/19; G05D23/1906; G05D23/1909; G05D23/20; G05D23/24; G05D23/2401; H05B3/00; H05B3/20; H05B3/34
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
200 words
A control circuit for an electrical heating element comprising a. switching means connected in series with the heating element for connection of a source of AC voltage, b. means for biasing said switching means to provide current conduction through the heating element including 1. circuit means for supplying a biasing voltage including means for advancing the phase of the biasing voltage with respect to the phase of the source of AC voltage, 2. a gating switch circuit connected between a point in said circuit means and said switching means, 3. electrical means comprising a bridge including temperaturesetting means in a leg of said bridge for detecting a temperature change of the heating element and connected to said gating switch for actuation thereof in response to the temperature of the heating element, and 4. means connected in circuit with said electrical detecting means for compensating said detecting means for ambient temperature variations said compensating means comprising a pair of diodes located in series in a leg of said detecting bridge on either side of said temperature-setting means and said diodes being temperature-responsive in compensating mode with respect to each other such that variations in temperature do not affect the temperature setting.
Claim 2
Dependent Claim
200 words
A control circuit for an electrical heating element comprising a. switching means connected in series with the heating element for connection of a source of AC voltage, b. means for biasing said switching means to provide current conduction through the heating element including 1. circuit means for supplying a biasing voltage including means for advancing the phase of the biasing voltage with respect to the phase of the source of AC voltage, 2. a gating switch circuit connected between a point in said circuit means and said switching means, 3. electrical means comprising a bridge including temperaturesetting means in a leg of said bridge for detecting a temperature change of the heating element and connected to said gating switch for actuation thereof in response to the temperature of the heating element, and 4. means connected in circuit with said electrical detecting means for compensating said detecting means for ambient temperature variations said compensating means comprising a pair of diodes located in series in a leg of said detecting bridge on either side of said temperature-setting means and said diodes being temperature-responsive in compensating mode with respect to each other such that variations in temperature do not affect the temperature setting.
Claim 3
Dependent Claim
20 words
A control circuit for an electrical heating element according to claim 1 wherein said switching means comprises a silicon-controlled rectifier.
Claim 4
Dependent Claim
16 words
a gating switch circuit connected between a point in said circuit means and said switching means,
Claim 5
Dependent Claim
16 words
a gating switch circuit connected between a point in said circuit means and said switching means,
Claim 6
Dependent Claim
42 words
electrical means comprising a bridge including temperature-setting means in a leg of said bridge for detecting a temperature change of the heating element and connected to said gating switch for actuation thereof in response to the temperature of the heating element, and
Claim 7
Dependent Claim
42 words
electrical means comprising a bridge including temperature-setting means in a leg of said bridge for detecting a temperature change of the heating element and connected to said gating switch for actuation thereof in response to the temperature of the heating element, and
Claim 8
Dependent Claim
14 words
A control circuit according to claim 1 wherein said phase-advancing means includes a capacitor.
Claim 9
Dependent Claim
16 words
A control circuit according to claim 1 wherein said gating switch circuit includes a first transistor.
Claim 10
Dependent Claim
67 words
means connected in circuit with said electrical detecting means for compensating said detecting means for ambient temperature variations said compensating means comprising a pair of diodes located in series in a leg of said detecting bridge on either side of said temperature-setting means and said diodes being temperature-responsive in compensating mode with respect to each other such that variations in temperature do not affect the temperature setting.
Claim 11
Dependent Claim
67 words
means connected in circuit with said electrical detecting means for compensating said detecting means for ambient temperature variations said compensating means comprising a pair of diodes located in series in a leg of said detecting bridge on either side of said temperature-setting means and said diodes being temperature-responsive in compensating mode with respect to each other such that variations in temperature do not affect the temperature setting.
Claim 12
Dependent Claim
21 words
A control circuit according to claim 4 wherein said gating switch circuit includes a second transistor coacting with the first transistor.
Claim 13
Dependent Claim
38 words
A control circuit according to claim 1 including current-limiting means connected in series with the heating element and the source of AC voltage, and a protective diode connected in parallel with the heating element for protecting said load.
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) | 1974-08-02 | 1975-02-01 | 1975-08-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-08-02 | 1979-02-01 | 1979-08-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-08-02 | 1983-02-01 | 1983-08-03 | $7700.00 | Window Closed / Lapsed |