Patent US3924253A successfully refreshed from Google Patents.
Patent US3814957A successfully refreshed from Google Patents.
US3814957A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Precision temperature controller
Assignee: Beckman Coulter Inc
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Filing: 1973-02-22
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Granted: 1974-06-04
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Expires: 1993-02-22
Abstract
Abstract A precision temperature controller utilizing a temperature sensitive resistive element in thermal relationship to an object to be heated, the element being connected in a bridge circuit to derive an error signal proportional to deviation from a desired temperature, the error signal being summed with a sawtooth voltage, the output so obtained being compared with a reference voltage in an operational amplifier to derive a pulsed output having a pulse width proportional to the error signal, the pulse width being used to control the time duration of energization of a heating element in proximity to the resistive element.
Inventors
- 👤 A Way
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 19:17
CPC Classifications
G; G05; G05D; G05D23/00; G05D23/19; G05D23/20; G05D23/24; G05D23/1906; G05D23/1913
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
138 words
In a direct current power control system, the combination comprising: a dirEct current energized power device; switching means for selectively coupling said device to a power source; means for sensing the power consumed by said device; reference means for establishing a predetermined power level; means electrically coupled to said reference means and said sensing means for producing an error signal proportional to the variation in said sensing means from the predetermined power level; means for generating a sawtooth wave signal; means for summing said sawtooth wave signal and said error signal; means coupled to the summed signal for producing a train of pulses, said pulses having a pulse width proportional to said error signal; means coupling the train of pulses to said switching means for energizing said switching means for a time period proportional to the pulse width.
Claim 2
Dependent Claim
138 words
In a direct current power control system, the combination comprising: a dirEct current energized power device; switching means for selectively coupling said device to a power source; means for sensing the power consumed by said device; reference means for establishing a predetermined power level; means electrically coupled to said reference means and said sensing means for producing an error signal proportional to the variation in said sensing means from the predetermined power level; means for generating a sawtooth wave signal; means for summing said sawtooth wave signal and said error signal; means coupled to the summed signal for producing a train of pulses, said pulses having a pulse width proportional to said error signal; means coupling the train of pulses to said switching means for energizing said switching means for a time period proportional to the pulse width.
Claim 3
Dependent Claim
29 words
The combination according to claim 1 wherein said switching means is a transistor; and said sensing means and said reference means are resistive devices connected in a bridge circuit.
Claim 4
Dependent Claim
55 words
The combination according to claim 1 wherein said means for producing a train of pulses is a differential amplifier having one input thereof coupled to receive said summed signal. and the other input thereof is coupled to a reference signal preset at a level to produce no pulses in the absence of an error signal.
Claim 5
Dependent Claim
28 words
The combination according to claim 3 wherein said power device and said switching means comprise a heating element connected in series with the collector-to-emitter portion of a transistor.
Claim 6
Dependent Claim
50 words
The combination according to claim 4 wherein said sensing means is a variable resistive device in intimate thermal relation with said heating element, said reference means is a resistive device, and said sensing means and said reference means are electrically connected in a bridge circuit to produce said error signal.
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) | 1977-06-03 | 1977-12-03 | 1978-06-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-03 | 1981-12-03 | 1982-06-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-03 | 1985-12-03 | 1986-06-04 | $7700.00 | Window Closed / Lapsed |