US3632985A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Thermocouple bridge temperature control
Assignee: BLUE M ELECTRIC Co
•
Filing: 1970-03-09
•
Granted: 1972-01-04
•
Expires: 1990-03-09
Abstract
Abstract A linearly calibrated temperature control suitable for economical commercial manufacture employs a thermocouple as an element of an arm of a Wheatstone bridge of particular resistance relation having a high-gain operational amplifier as the DC unbalance detector. The control temperature is varied by manual variation of resistance of a bridge arm and variations of amplifier offset are compensated at all temperatures by singletemperature scale adjustment. The DC output of the operational amplifier controls a power regulation circuit which responds to unbalance of one polarity.
Inventors
- 👤 Duward J Bare
- 👤 Chester S Penk
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 18:11
CPC Classifications
G; G05; G05D; G05D23/00; G05D23/19; G05D23/20; G05D23/22; G05D23/1902
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
149 words
In a temperature control comprising a temperature-responsive voltage source including a thermocouple, a manually variable source of balancing potential, means for comparing the temperature-responsive source and the balancing source, and means for producing heat transfer at a rate responsive to the magnitude of the difference to establish and maintain manually selected temperatures, the improved construction characterized by: a. the comparing means comprising a high-gain operational amplifier, b. and the source of balancing potential having a control member varying the potential linearly with movement thereof and having a visual indicator essentially linearly Calibrated in temperature, the control member varying the balancing potential over a range greater than the range of balancing potentials corresponding to the calibrated temperature range, so that substantially uniform temperature calibration may be obtained in commercial manufacture, despite variation in inputoutput offset of individual operational amplifiers, by singletemperature positioning of the indicator relative to the control member.
Claim 2
Dependent Claim
149 words
In a temperature control comprising a temperature-responsive voltage source including a thermocouple, a manually variable source of balancing potential, means for comparing the temperature-responsive source and the balancing source, and means for producing heat transfer at a rate responsive to the magnitude of the difference to establish and maintain manually selected temperatures, the improved construction characterized by: a. the comparing means comprising a high-gain operational amplifier, b. and the source of balancing potential having a control member varying the potential linearly with movement thereof and having a visual indicator essentially linearly Calibrated in temperature, the control member varying the balancing potential over a range greater than the range of balancing potentials corresponding to the calibrated temperature range, so that substantially uniform temperature calibration may be obtained in commercial manufacture, despite variation in inputoutput offset of individual operational amplifiers, by singletemperature positioning of the indicator relative to the control member.
Claim 3
Dependent Claim
122 words
The temperature control of claim 1 further characterized by: c. said sources and comparing means comprising a temperature-sensitive resistive Wheatstone bridge having first and second series-connected arms and third and fourth series-connected arms connected in parallel with the first and second arms across a DC energizing source, and having the operational amplifier input connected between the junctions of the respective pairs of arms, d. the first and third arms each being of resistance which is a large multiple of that of the second and fourth, respectively, e. the thermocouple being in one of said arms of lower resistance and in polarity opposing the energizing source, f. and the control member being a variable resistor in one of said arms of lower resistance.
Claim 4
Dependent Claim
21 words
The temperature control of claim 2 further characterized by: g. the control member and the thermocouple being in opposite low-resistance arms.
Claim 5
Dependent Claim
30 words
The temperature control of claim 3 further characterized by: h. at least one parallel combination of a resistor and thermistor in series with the control member for ambient temperature compensation.
Claim 6
Dependent Claim
38 words
The temperature control of claim 1 wherein the source of balancing potential includes at least one parallel combination of a thermistor and a resistor, to compensate for variation in the temperature of the cold junction of the thermocouple.
Claim 7
Dependent Claim
83 words
The temperature control of claim 1 further characterized by: c. the heat-transfer-producing means comprising regulating means coupled to the amplifier output and maintaining a maximum heat transfer rate at substantially all input values of polarity indicative of requirement for greater heat transfer, and decreasing the heat transfer rate with increasing input of the opposite polarity, so that reduction heat transfer commences in start-up only when the preselected temperature is closely approached, whereupon the heat transfer is reduced until the equilibrium temperature is reached.
Claim 8
Dependent Claim
36 words
The temperature control of claim 6 having the output of the amplifier substantially null at null input and connected to the current-control input of a transistor rendered substantially conducting only by input of said opposite polarity.
Claim 9
Dependent Claim
47 words
The temperature control of claim 7 wherein the transistor is connected across a charging capacitor to control the rate of charging thereof, and including means to discharge the capacitor and initiate heat-transfer energization upon reaching a predetermined potential in each half-cycle of an alternating heat-transfer power source.
Claim 10
Dependent Claim
33 words
The temperature control of claim 8 wherein the discharging means comprises a direct voltage supply pulsating in synchronism with the power source and the charging potential for the capacitor comprises filtered direct voltage.
Claim 11
Dependent Claim
29 words
The temperature control of claim 8 having a transformer primary in series with the capacitor and having a rectifier bypassing the transformer primary only for current of charging polarity.
Claim 12
Dependent Claim
56 words
The temperature control of claim 10 wherein said power source is one phase of a three-phase line, and having means for connecting the amplifier output to power-control circuits for the other phases, and a rectifier connected between the amplifier output and the transistor input blocking output current of polarity indicative of need for greater heat transfer.
Claim 13
Dependent Claim
21 words
The temperature control of claim 8 having at least one rectifier blocking reverse current through the charging circuit of the capacitor.
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) | 1975-01-03 | 1975-07-05 | 1976-01-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-03 | 1979-07-05 | 1980-01-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-03 | 1983-07-05 | 1984-01-04 | $7700.00 | Window Closed / Lapsed |