US3751635A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Temperature control circuit
Assignee: Individual
•
Filing: 1972-02-22
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Granted: 1973-08-07
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Expires: 1992-02-22
Abstract
Abstract The invention relates to a temperature control circuit for a device, such as an oven, a cooker or a washing machine, including a triac which is controlled by a temperature sensor connected in a bridge circuit, a second bridge circuit and an amplifier stage being provided by means of which three-stage control is obtained and the triac is always controlled during the passages through zero of the supply voltage. When the temperature is too high no power is supplied to a heating element, when the temperature is too low the full power is supplied, and near the desired temperature one half of the power is supplied.
Inventors
- 👤 W Niehaus
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 21:13
CPC Classifications
G; G05; G05F; G05F1/00; G05F1/10; G05F1/12; G05F1/40; G05F1/44; G05F1/45; G05F1/452; G05D; G05D23/00; G05D23/19; G05D23/1906; G05D23/1912; G05D23/20; G05D23/24; H; H02; H02M; H02M1/00; H02M1/08; H02M1/083
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
293 words
A temperature control circuit for providing three-point temperature regulation of a device which includes a heating element comprising, a pair of input terminals adapted to be connected to a source of AC supply voltage, bidirectional controlled switching means connecting said heating element to said input terminals to control the flow of current from said terminals to said heating element, a zero crossing voltage detection circuit connected to the input terminals, a transistor unbalance detector, a measuring bridge circuit including a temperature sensor in one arm and the base-emitter circuit of said transistor unbalance detector, a firing Circuit controlled by the output collector circuit of the unbalance detector of the bridge circuit and including means for applying a trigger signal to a control electrode of said bidirectional switching means, a supply circuit including a diode and a capacitor for coupling energy from the input terminals to the bridge circuit and the firing circuit, said zero crossing detection circuit being operative, when the temperature of the device is too low, in conjunction with the output collector circuit of the unbalance detector to signal the firing circuit to deliver a trigger signal to fire the switching means in the zero value region of the AC supply voltage, means including the firing circuit for discharging an appreciable portion of the capacitor charge at the time the trigger signal is generated, said bridge and firing circuits being arranged so as not to supply a trigger signal when the temperature of the device is above the desired set temperature, and said bridge and firing circuits and said capacitor being operative with the zero detection circuit in the proximity of the set temperature of the device to trigger the switching means during alternate half cycles of the AC supply voltage.
Claim 2
Dependent Claim
293 words
A temperature control circuit for providing three-point temperature regulation of a device which includes a heating element comprising, a pair of input terminals adapted to be connected to a source of AC supply voltage, bidirectional controlled switching means connecting said heating element to said input terminals to control the flow of current from said terminals to said heating element, a zero crossing voltage detection circuit connected to the input terminals, a transistor unbalance detector, a measuring bridge circuit including a temperature sensor in one arm and the base-emitter circuit of said transistor unbalance detector, a firing Circuit controlled by the output collector circuit of the unbalance detector of the bridge circuit and including means for applying a trigger signal to a control electrode of said bidirectional switching means, a supply circuit including a diode and a capacitor for coupling energy from the input terminals to the bridge circuit and the firing circuit, said zero crossing detection circuit being operative, when the temperature of the device is too low, in conjunction with the output collector circuit of the unbalance detector to signal the firing circuit to deliver a trigger signal to fire the switching means in the zero value region of the AC supply voltage, means including the firing circuit for discharging an appreciable portion of the capacitor charge at the time the trigger signal is generated, said bridge and firing circuits being arranged so as not to supply a trigger signal when the temperature of the device is above the desired set temperature, and said bridge and firing circuits and said capacitor being operative with the zero detection circuit in the proximity of the set temperature of the device to trigger the switching means during alternate half cycles of the AC supply voltage.
Claim 3
Dependent Claim
230 words
A temperature control circuit as claimed in claim 1 wherein said zero crossing detection circuit comprises a second bridge circuit have a second transistor unbalance detector the emitter of which is connected to the junction point of two diodes connected in series opposition which each form an arm of the second bridge circuit, means connecting the base of the transistor to the junction point of two resistors which may be in the form of diodes and each form another bridge arm, the collector of the said transistor being arranged to pass current outside the zero value region of the alternating voltage, the temperature control circuit further including a common lead to which are connected one input terminal for the alternating voltage supply, a supply point of the bridge circuit comprising the zero detection circuit, a supply point of the measuring second bridge circuit, one terminal of the capacitor and one main electrode of the switching means, and wherein the firing circuit includes a transistor the emitter of which is connected to the other terminal of the capacitor, the collector of which is connected via a resistor to the control electrode of the switching means and the base of which is connected to the collector of the measuring bridge unbalance detector, and means connecting the collector of the second transistor unbalance detector to the base of the measuring bridge unbalance detector.
Claim 4
Dependent Claim
66 words
A temperature control circuit as claimed in claim 2, wherein the other bridge supply point of the zero crossing detection circuit is connected via the series combination of two resistors to the other input terminal of the alternating voltage supply, the supply circuit diode being connected between the junction point of said two series-connected resistors and the other bridge supply point of the measuring bridge circuit.
Claim 5
Dependent Claim
42 words
A temperature control circuit as claimed in claim 1 wherein said diode is connected between one of said input terminals and one input terminal of the measuring bridge and the capacitor is connected across the input terminals of the measuring bridge circuit.
Claim 6
Dependent Claim
60 words
A temperature control circuit as claimed in claim 4 wherein the base-emitter circuit of the transistor unbalance detector is connected across the output terminals of the measuring bridge circuit and said firing circuit includes a transistor with its base connected to the collector of the transistor unbalance detector and its collector connected to the control electrode of the switching means.
Claim 7
Dependent Claim
109 words
A temperature control circuit as claimed in claim 1 wherein said zero crossing detection circuit comprises a second bridge circuit with input terminals connected to the AC supply terminals and first and second diodes connected in series opposition between the bridge input terminals to form first and second arms Of the second bridge and first and second impedance elements serially connected between the bridge input terminals to form third and fourth arms of the second bridge, and a second transistor unbalance detector with its base-emitter circuit connected to the output terminals of the second bridge circuit and its collector connected to the base of the first transistor unbalance detector.
Claim 8
Dependent Claim
62 words
A temperature control circuit as claimed in claim 6 wherein said supply circuit includes two resistors connected in series between one of said supply terminals and one input terminal of the second bridge circuit, said supply circuit further comprising means connecting the supply diode between the junction of said two series connected resistors and an input terminal of the measuring bridge circuit.
Claim 9
Dependent Claim
57 words
A temperature control circuit as claimed in claim 1 wherein said firing circuit comprises a transistor with its base connected to the collector of the transistor unbalance detector and its emitter-collector circuit connected to provide a discharge path for the capacitor into the control electrode of said switching means, and said switching means comprises a semiconductor triac.
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) | 1976-08-06 | 1977-02-05 | 1977-08-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-06 | 1981-02-05 | 1981-08-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-06 | 1985-02-05 | 1985-08-07 | $7700.00 | Window Closed / Lapsed |