US3564205A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Temperature control circuits
Assignee: Robertshaw Controls Co
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Filing: 1969-11-20
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Granted: 1971-02-16
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Expires: 1989-11-20
Abstract
Abstract Temperature control circuits including a bridge network having an output controlling a programmable unijunction transistor, a load controlling the heat supplied to an area, an SCR in series with the load and controlled by the programmable unijunction transistor in accordance with temperature sensed by a thermistor in the bridge network, and a unidirectionally conductive limiter diode connected with the bridge network to permit control operation on only the initial portion of positive half cycles of a supply voltage. Modifications of the temperature control circuits include means for increasing temperature differentials to require discrete temperature changes to energize and deenergize the load.
Inventors
- 👤 Hugh J Tyler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 22:36
CPC Classifications
G; G05; G05D; G05D23/00; G05D23/19; G05D23/20; G05D23/24; G05D23/1906; G05D23/1909
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
246 words
A temperature control circuit comprising: supply means adapted to receive an AC supply voltage; load means connected with said supply means and adapted to control the temperature in a space; switch means and controlling the energization of said load means; a bridge network including input means connected with said supply terminal means to receive the supply voltage, output means, three resistive legs connected with said input means and said output means, and a fourth leg having temperature variable resistance means disposed in said space and connected with said input means and said output means such that output signals are provided at said output means corresponding to the temperature in said space; detection means connected with output means to receive said output signal and assume a conductive or nonconductive state in accordance therewith, said detection means having an output connected with said switch means to control the operation thereof such that said means is conductive when said detection means is conductive to energize said load means; and limiter means connected with said input means and said output means of said bridge network across one of said resistive legs, said limiter means being unidirectionally conductive and having a predetermined breakdown voltage whereby said limiter means is triggered during the initial portion of positive half cycles of the supply voltage to permit control of said switch means independent of amplitude variations of the supply voltage and said limiter means is nonconductive during negative half cycles of the supply voltage.
Claim 2
Dependent Claim
246 words
A temperature control circuit comprising: supply means adapted to receive an AC supply voltage; load means connected with said supply means and adapted to control the temperature in a space; switch means and controlling the energization of said load means; a bridge network including input means connected with said supply terminal means to receive the supply voltage, output means, three resistive legs connected with said input means and said output means, and a fourth leg having temperature variable resistance means disposed in said space and connected with said input means and said output means such that output signals are provided at said output means corresponding to the temperature in said space; detection means connected with output means to receive said output signal and assume a conductive or nonconductive state in accordance therewith, said detection means having an output connected with said switch means to control the operation thereof such that said means is conductive when said detection means is conductive to energize said load means; and limiter means connected with said input means and said output means of said bridge network across one of said resistive legs, said limiter means being unidirectionally conductive and having a predetermined breakdown voltage whereby said limiter means is triggered during the initial portion of positive half cycles of the supply voltage to permit control of said switch means independent of amplitude variations of the supply voltage and said limiter means is nonconductive during negative half cycles of the supply voltage.
Claim 3
Dependent Claim
42 words
The invention as recited in claim 1 wherein storage means is connected with said limiter means to change the output signals at said output means independent of said temperature variable resistance means to increase the temperature differential of said temperature control circuit.
Claim 4
Dependent Claim
31 words
The invention as recited in claim 2 wherein said limiter means includes a unidirectionally conducting breakdown diode, and said storage means includes a capacitor connected in series with said breakdown diode.
Claim 5
Dependent Claim
28 words
The invention as recited in claim 3 wherein said capacitor is connected with said output means to increase the voltage of the output signals at said output means.
Claim 6
Dependent Claim
54 words
The invention as recited in claim 3 wherein said storage means includes shunt switch means shunting a portion of said one resistive leg and connected with said capacitor whereby said shunt switch means is conductive in response to voltage on said capacitor to decrease the voltage of the output signals at said output means.
Claim 7
Dependent Claim
15 words
The invention as recited in claim 5 wherein said shunt switch means is a transistor.
Claim 8
Dependent Claim
133 words
The invention as recited in claim 1 wherein said input means includes a first input terminal and a second input terminal, said output means includes a first output terminal and a second output terminal, said one resistive leg is connected between said first input terminal and said first output terminal, a second of said resistive legs is connected between said first input terminal and said second output terminal, a third of said resistive legs is connected between said second input terminal and said second output terminal, said fourth leg is connected between said second input terminal and said first output terminal, and said detection means is connected with said second output terminal to receive reference signals and with said first output terminal to receive output signals corresponding to the temperature in said space.
Claim 9
Dependent Claim
17 words
The invention as recited in claim 7 wherein said limiter means includes a unidirectionally conducting breakdown diode.
Claim 10
Dependent Claim
46 words
The invention as recited in claim 8 wherein a capacitor is connected in series with said breakdown diode through a second diode having an anode connected with the cathode of said breakdown diode and a cathode connected with a first side of said first input Terminal.
Claim 11
Dependent Claim
140 words
The invention as recited in claim 9 wherein said cathode of said breakdown diode is connected with said first input terminal through a first resistor, said first side of said capacitor is connected with said second output terminal through a second resistor, said detection means includes a semiconductor switch having a first electrode connected with said first output terminal and a third electrode connected with said second output terminal and a third electrode connected with said switch means, said semiconductor switch being conductive during positive half cycles of the supply voltage when the voltage of the output signals at said first input terminal is greater than the voltage of the reference signals at said second output terminal whereby said capacitor is charged with said semiconductive switch is nonconductive to add voltage to the reference signals at said second output terminal.
Claim 12
Dependent Claim
78 words
The invention as recited in claim 10 wherein said semiconductor switch is a programmable unijunction transistor having an anode connected with said first output terminal, a gate connected with said second input terminal and a cathode, and said switch means is a silicon controlled rectifier having an anode connected with said second output terminal and said load means, a cathode connected with said first input terminal, and a gate connected with said cathode of said programmable unijunction transistor.
Claim 13
Dependent Claim
29 words
The invention as recited in claim 11 wherein said fourth leg of said bridge includes variable resistance means for setting the desired temperature to be maintained in said space.
Claim 14
Dependent Claim
174 words
The invention as recited in claim 9 wherein said cathode of said breakdown diode is connected with said first input terminal through a first resistor, said first side of said first capacitor is connected with the base of a transistor, the emitter-collector path of said transistor being connected across a portion of said one resistive leg of said bridge and said detection means includes semiconductor switch having a first electrode connected with said first output terminal, a second electrode connected with said second output terminal and a third electrode connected with said switch means, said semiconductor switch being conductive during positive half cycles of the supply voltage when the voltage of the output signals at said first input terminal is greater than the voltage of the reference signals at said second output terminal whereby said capacitor is charged when said semiconductor switch is nonconductive to bias said transistor into a conductive state to shunt said portion of said one resistive leg to decrease the voltage of the output signals at said first input terminal.
Claim 15
Dependent Claim
48 words
The invention as recited in claim 13 wherein said emitter-collector path of said transistor is connected across said portion of said one resistive leg through a second variable resistor and a third resistor is connected with said first side of said capacitor and the base of said transistor.
Claim 16
Dependent Claim
78 words
The invention as recited in claim 14 wherein said semiconductor switch is a programmable unijunction transistor having an anode connected with said first output terminal, a gate connected with said second input terminal and a cathode, and said switch means is a silicon controlled rectifier having an anode connected with said second input terminal and said load means, a cathode connected with said first input terminal, and a gate connected with said cathode of said programmable unijunction transistor.
Claim 17
Dependent Claim
29 words
The invention as recited in claim 15 wherein said fourth leg of said bridge includes variable resistance means for setting the desired temperature to be maintained in said space.
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) | 1974-02-15 | 1974-08-17 | 1975-02-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-02-15 | 1978-08-17 | 1979-02-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-02-15 | 1982-08-17 | 1983-02-16 | $7700.00 | Window Closed / Lapsed |