US3566151A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Temperature control circuits
Assignee: Pilkington Group Ltd
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Filing: 1969-03-10
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Granted: 1971-02-23
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Expires: 1989-03-10
Abstract
Abstract A circuit for controlling the heating current flowing through a load according to a predetermined temperature/time function includes a thyristor circuit which controls the power supplied to the load and a firing circuit for the thyristor circuit. The output from a thermocouple associated with the load is compared with a voltage representing a predetermined temperature/time function to produce a control output which is connected to the firing circuit.
Inventors
- 👤 Frederick W Wilburn
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 12:52
CPC Classifications
G; G05; G05B; G05B19/00; G05B19/02; G05B19/04; G05B19/07; G05B19/075; G05D; G05D23/00; G05D23/19; G05D23/1906; G05D23/1913; G05D23/20; G05D23/22
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
178 words
A control circuit for controlling the heating current flowing through an electrical load according to a predetermined temperature/time function, comprising a thyristor circuit connecting the load to an alternating current supply, a firing circuit connected to the trigger input of the thyristor circuit, a thermocouple associated with the load, a function generator comprising a high stability analogue amplifier which is shunted by a polyester capacitor, and an adjustable voltage supply circuit connected to the input of the analogue amplifier, the setting of which voltage supply circuit determines the rate of change of voltage at the output of the analogue amplifier representing said temperature/time function, a summing amplifier having one input connected to the thermocouple and a second input connected to the output of the analogue amplifier, and an output from the summing amplifier connected to the firing circuit so as to transmit thereto a potential level to control the time during each cycle of the supply current when the thyristor circuit is triggered, thereby controlling the heating current supplied to the load in accordance with said predetermined function.
Claim 2
Dependent Claim
178 words
A control circuit for controlling the heating current flowing through an electrical load according to a predetermined temperature/time function, comprising a thyristor circuit connecting the load to an alternating current supply, a firing circuit connected to the trigger input of the thyristor circuit, a thermocouple associated with the load, a function generator comprising a high stability analogue amplifier which is shunted by a polyester capacitor, and an adjustable voltage supply circuit connected to the input of the analogue amplifier, the setting of which voltage supply circuit determines the rate of change of voltage at the output of the analogue amplifier representing said temperature/time function, a summing amplifier having one input connected to the thermocouple and a second input connected to the output of the analogue amplifier, and an output from the summing amplifier connected to the firing circuit so as to transmit thereto a potential level to control the time during each cycle of the supply current when the thyristor circuit is triggered, thereby controlling the heating current supplied to the load in accordance with said predetermined function.
Claim 3
Dependent Claim
62 words
A circuit according to claim 1, wherein the input to the analogue amplifier is connected to act as a summing amplifier by two parallel resistors in the input, one being connected to said adjustable voltage supply circuit and the other being means for deriving an adjustable voltage representing the temperature at which control of the heating current by the function generator begins.
Claim 4
Dependent Claim
52 words
A circuit according to claim 1, wherein the adjustable voltage supply circuit comprises a potentiometer connected to a DC voltage source through a reversing switch, whereby the polarity of the supply is reversible to provide control of the rise or the fall of the temperature of the load by the function generator.
Claim 5
Dependent Claim
79 words
A circuit according to claim 1, including a voltage limiting diode shunting the analogue amplifier in parallel with said polyester capacitor, one electrode of the diode being connected to the input of the analogue amplifier through a potentiometer which is connected in a resistor chain extending between a fixed potential supply and earth, the setting of the potentiometer determining a voltage, corresponding to the maximum temperature of the load to be achieved, at which the voltage limiting diode conducts.
Claim 6
Dependent Claim
78 words
A circuit according to claim 1, including a second analogue amplifier connected between the function generator output and the second input to the summing amplifier, and a series of parallel-connected shunt circuits shunting the second analogue amplifier and each including a diode and a potentiometer, the potentiometers being settable so that the shunt circuits are switched in successively as the amplifier output varies, thereby adjusting the gain of the amplifier to match the temperature/voltage characteristic of the thermocouple.
Claim 7
Dependent Claim
40 words
A circuit according to claim 1, including a diode connected between the function generator output and a fixed voltage in a sense such that the diode conducts and modifies the function generator output when that output reaches a predetermined voltage.
Claim 8
Dependent Claim
69 words
A circuit according to claim 6, including a plurality of diodes connected to the function generator output, and each returned to a different fixed voltage so that the diodes are switched into conduction in succession as the function generator output passes through predetermined voltages and said output passes through predetermined voltages and said output is made to approximate to a temperature/time curve matching the temperature/voltage characteristic of the thermocouple.
Claim 9
Dependent Claim
57 words
A circuit according to claim 1, wherein the thyristor circuit includes two thyristors connected in parallel-opposing, and in series with the alTernating current supply and the electrical load, the trigger electrodes of both thyristors being connected to the firing circuit so that the thyristors conduct respectively on the positive and negative half-cycles of the alternating current supply.
References Cited (Backward Citations)
US2666889A
Cited
US3157801A
Cited
US3196255A
Cited
US3231719A
Cited
US3315063A
Cited
US3443121A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-02-22 | 1974-08-24 | 1975-02-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-02-22 | 1978-08-24 | 1979-02-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-02-22 | 1982-08-24 | 1983-02-23 | $7700.00 | Window Closed / Lapsed |