Patent FR1269723A successfully refreshed from Google Patents.
US3733463A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Temperature control system with a pulse width modulated bridge
Assignee: Individual
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Filing: 1970-12-24
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Granted: 1973-05-15
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Expires: 1990-12-24
Abstract
Abstract A temperature control system is disclosed which includes a modified wheatstone bridge with a resistive-capacitive (RC) circuit in one leg of the bridge. The RC circuit includes a resistor which provides an effective resistance as a function of its absolute resistance and the on-time to off-time ratio of pulses supplied to a switch connected thereacross. A sawtooth voltage is produced across the RC circuit, the voltage being compared with the voltage across a temperature sensor, with heat being applied during each pulse period portion when the sawtooth voltage exceeds the voltage across the temperature sensor.
Inventors
- 👤 G Low
- 👤 R Heyser
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 19:10
CPC Classifications
G; G05; G05D; G05D23/00; G05D23/19; G05D23/20; G05D23/24; G05D23/1906; G05D23/1913
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
205 words
A temperature control system comprising: a wheatstone-like bridge having first and second parallel legs and including a temperature sensitive element, whose resistance varies as a function of temperature, connected in series with a first bridge resistor in said first leg, and a resistorcapacitor circuit connected in series with a second bridge resistor in said second leg; a source of power; heating means for providing heat when connected to said source; means for applying a voltage across said bridge, whereby the voltages across said element circuit are functions of the resistances thereacross, respectively; means coupled to said element and to said circuit for connecting said heating means to said source when the voltage across said circuit is greater than the voltage across said element; and control means coupled to said circuit for controlling the resistance across said circuit to vary in a preselected manner during each of a succession of pulse periods with the capacitor of said circuit controlling the voltage of said circuit to vary in a preselected manner from a first level to a second level during a first portion of each pulse period and from said second level to said first level during the rest of the pulse period following said first portion.
Claim 2
Dependent Claim
205 words
A temperature control system comprising: a wheatstone-like bridge having first and second parallel legs and including a temperature sensitive element, whose resistance varies as a function of temperature, connected in series with a first bridge resistor in said first leg, and a resistorcapacitor circuit connected in series with a second bridge resistor in said second leg; a source of power; heating means for providing heat when connected to said source; means for applying a voltage across said bridge, whereby the voltages across said element circuit are functions of the resistances thereacross, respectively; means coupled to said element and to said circuit for connecting said heating means to said source when the voltage across said circuit is greater than the voltage across said element; and control means coupled to said circuit for controlling the resistance across said circuit to vary in a preselected manner during each of a succession of pulse periods with the capacitor of said circuit controlling the voltage of said circuit to vary in a preselected manner from a first level to a second level during a first portion of each pulse period and from said second level to said first level during the rest of the pulse period following said first portion.
Claim 3
Dependent Claim
68 words
The arrangement as recited in claim 1 wherein said circuit consists of first and second resistors connected in series and said capacitor is connected in parallel across at least one of said resistors and said control means is coupled to said second resistor and includes first means for shorting out said second resistor during said first portion of each pulse period, with said first portion being selectively variable.
Claim 4
Dependent Claim
73 words
The arrangement as recited in claim 2 wherein said control means include second means for providing a succession of equal period pulses, each pulse being of a first level during said first portion of each pulse period and of a second level during the rest of the pulse period, and means for applying said pulses to said first means to short out said second resistor during the first portion of each pulse period.
Claim 5
Dependent Claim
92 words
The arrangement as recited in claim 2 wherein said capacitor is connected in parallel across both said first and second resistors, whereby when said second resistor is shorted out the voltage across said capacitor, representing the voltage across said circuit, rises gradually from said first level to said second level and falls gradually from said second level to said first level during the rest of each pulse period when sAid second resistor is not shorted out, with the voltage across the circuit during each pulse period having the shape of a sawtooth.
Claim 6
Dependent Claim
73 words
The arrangement as recited in claim 4 wherein said control means include second means for providing a succession of equal period pulses, each pulse being of a first level during the first portion of each pulse period and of a second level during the rest of the pulse period, and means for applying said pulses to said first means to short out said second resistor during the first portion of each pulse period.
Claim 7
Dependent Claim
170 words
In a temperature control system of the type comprising a bridge with a temperature sensitive element whose resistance varies as a function of temperature in one leg of said bridge, said system further including means for comparing the voltage across said element with the voltage across another leg of said bridge, an arrangement comprising: a resistor having first and second terminals in said other leg; control means for controlling the resistance across said terminals to vary from the full resistance of said resistor to substantially zero during a selected portion of each of a succession of periods, whereby the effective resistance across said terminals during each period is less than the resistance of said resistor; and a capacitor in said other leg connected in parallel across at least said resistor whereby the voltage across said other leg increases toward a peak value when the resistance across said terminals is the full resistance of said resistor and decreases from said peak value when the resistance across said terminals is substantially zero.
Claim 8
Dependent Claim
170 words
In a temperature control system of the type comprising a bridge with a temperature sensitive element whose resistance varies as a function of temperature in one leg of said bridge, said system further including means for comparing the voltage across said element with the voltage across another leg of said bridge, an arrangement comprising: a resistor having first and second terminals in said other leg; control means for controlling the resistance across said terminals to vary from the full resistance of said resistor to substantially zero during a selected portion of each of a succession of periods, whereby the effective resistance across said terminals during each period is less than the resistance of said resistor; and a capacitor in said other leg connected in parallel across at least said resistor whereby the voltage across said other leg increases toward a peak value when the resistance across said terminals is the full resistance of said resistor and decreases from said peak value when the resistance across said terminals is substantially zero.
Claim 9
Dependent Claim
96 words
The arrangement as recited in claim 6 wherein said control means includes a switch which is connected across said first and second terminals, said switch being switchable to an on state in which said terminals are effectively shorted out and an off state during which the resistance across said terminals is the resistance of said resistor, and source means coupled to said switch means for controlling said switch to be in the on state during a selected portion of each of said periods and in the off state during the rest of each of said periods.
Claim 10
Dependent Claim
62 words
The arrangement as recited in claim 7 wherein said source means is a source of a succession of equal period pulses, each pulse being of a first level which switches said switch to its on state during a variably selected period portion and of a second level which switches said switch to its off state during the rest of the pulse period.
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) | 1976-05-14 | 1976-11-13 | 1977-05-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-05-14 | 1980-11-13 | 1981-05-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-05-14 | 1984-11-13 | 1985-05-15 | $7700.00 | Window Closed / Lapsed |