Patent US3675484A successfully refreshed from Google Patents.
US3675484A
Expired / Lapsed
US
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Apparatus for temperature measurement
Assignee: Battelle Development Corp
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Filing: 1970-06-05
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Granted: 1972-07-11
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Expires: 1990-06-05
Abstract
Abstract An improved apparatus for temperature measurement which minimizes sensing element self-heating error and instrument ambient heating error when used as an oceanographic thermometer includes a frequency-selective network having a thermistor as a temperature sensing element thereof. The network is connected in the feedback loop of an AC amplifier whose output voltage is stabilized by an automatic gain control circuit at a predetermined, low value. In one embodiment, the output voltage is connected to the apparatus output terminal through an isolation circuit, and the AGC circuit comprises a second thermistor in shunt with the output voltage. In a second, improved embodiment, the output voltage is amplified by a second amplification stage and applied to a level detector circuit and to an isolation circuit from which the apparatus output is taken. The level detector in turn controls the impedance of a field effect transistor in shunt with the output voltage. The requirements for a successful oceanographic thermometer design are discussed and related in detail to the embodiments noted, and the performance of working models of each embodiment with regard to these requirements is set forth.
Inventors
- 👤 Arthur M Pederson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 15:54
CPC Classifications
G; G01; G01K; G01K1/00; G01K1/02; G01K1/024; G01K7/00; G01K7/16; G01K7/22; G01K7/24; G01K7/245
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
276 words
An apparatus for the measurement of temperature comprising: a. a frequency-selective network which comprises a parallel branch and a series branch, said series branch including a resistance and a capacitance in series, and said parallel branch including a second resistance and a second capacitance in parallel, one of said resistances comprising a temperaturedependent resistor, b. a source of supply voltage, c. an AC amplifier having input, output, supply and reference terminals, said source of supply voltage being connected across said supply and said reference terminals, said parallel branch being connected from said input terminal to said reference terminal, and said series branch being connected from said output terminal to said input terminal, said AC amplifier having a gain sufficient to insure oscillation thereof in combination with said frequency-selective network to produce an output voltage on said output terminal whose frequency is determined by the temperature of said temperature-dependent resistor, said AC amplifier further including an input circuit connected between said input and said reference terminals, the impedance of said input circuit being high so that the input impedance of said AC amplifier is relatively high when compared with the impedance of said parallel branch of said frequencyselective network and an output circuit connected between said output and said reference terminals thereof for prOviding a relatively low output impedance with respect to the impedance of said series branch of said frequency-selective network, and d. means connected between said output and said reference terminals for stabilizing said output voltage on said output terminal at a predetermined low level being just sufficient to maintain the overall loop gain of said frequency-selective network and said AC amplifier greater than unity.
Claim 2
Independent Claim
276 words
An apparatus for the measurement of temperature comprising: a. a frequency-selective network which comprises a parallel branch and a series branch, said series branch including a resistance and a capacitance in series, and said parallel branch including a second resistance and a second capacitance in parallel, one of said resistances comprising a temperaturedependent resistor, b. a source of supply voltage, c. an AC amplifier having input, output, supply and reference terminals, said source of supply voltage being connected across said supply and said reference terminals, said parallel branch being connected from said input terminal to said reference terminal, and said series branch being connected from said output terminal to said input terminal, said AC amplifier having a gain sufficient to insure oscillation thereof in combination with said frequency-selective network to produce an output voltage on said output terminal whose frequency is determined by the temperature of said temperature-dependent resistor, said AC amplifier further including an input circuit connected between said input and said reference terminals, the impedance of said input circuit being high so that the input impedance of said AC amplifier is relatively high when compared with the impedance of said parallel branch of said frequencyselective network and an output circuit connected between said output and said reference terminals thereof for prOviding a relatively low output impedance with respect to the impedance of said series branch of said frequency-selective network, and d. means connected between said output and said reference terminals for stabilizing said output voltage on said output terminal at a predetermined low level being just sufficient to maintain the overall loop gain of said frequency-selective network and said AC amplifier greater than unity.
Claim 3
Dependent Claim
45 words
An apparatus for the measurement of temperature as recited in claim 1, wherein said input circuit includes a field-effect transistor so that the input impedance of said AC amplifier is relatively high when compared with the impedance of said parallel branch of said frequency-selective network.
Claim 4
Dependent Claim
82 words
An apparatus for the measurement of temperature, as recited in claim 1, wherein said output circuit comprises a transistor connected in an emitter-follower configuration, said transistor having an input, and a voltage divider network in circuit therewith, said voltage divider network comprising two series-connected resistors which are connected from the emitter of said transistor to said amplifier''s reference terminal, the common junction of said resistors functioning as said amplifier''s output terminal, and means coupling said amplifier''s input terminal to said transistor input.
Claim 5
Dependent Claim
71 words
An apparatus for the measurement of temperature, as recited in claim 3, wherein: a. said AC amplifier further includes an amplification stage having an input and an output, said input being coupled to said amplifier''s input terminal and said output being coupled to the input of said transistor, and b. said stabilizing means comprises a second temperature dependent resistor which is coupled between said transistor input and said amplifier''s reference terminal.
Claim 6
Dependent Claim
155 words
An apparatus for the measurement of temperature, as recited in claim 3, wherein: a. said AC amplifier further includes an amplification stage having an input and an output, said input being coupled to said amplifier''s input terminal and said output being coupled to the input of said transistor, and b. said stabilizing means comprises: i. a level detecting means having said output voltage on said amplifier''s output terminal coupled thereto, said level detecting means including a source of a standard voltage, and means comparing said output voltage with said standard voltage to produce a control signal whose magnitude and sense are determined by their difference, ii. a controllable variable impedance which is coupled between said transistor input and said amplifier''s reference terminal, said controllable variable impedance including a control terminal, and iii. means coupling said control signal to said control terminal, whereby said output voltage is regulated at a value determined by said standard voltage.
Claim 7
Dependent Claim
69 words
An apparatus for the measurement of temperature, as recited in claim 5, and further including a second AC amplifier, said second amplifier also including input, output, supply and reference terminals, said source of supply voltage being connected across its supply and reference terminals, said second amplifier''s input terminal being connected to said first amplifier''s output terminal, and said second amplifier''s output terminal being coupled to said level detecting means.
Claim 8
Dependent Claim
117 words
An apparatus for the measurement of temperature, as recited in claim 1, wherein said output circuit further includes a first transistor connected in an emitter-follower configuration, and further comprising a second transistor in circuit with said first transistor, each transistor having a base, a collector, and an emitter, the emitter of said first transistor being said amplifier''s output terminal, the base of said second transistor being tied to the collector of said first transistor, the collector of said second transistor being tied to the emitter of said first transistor, and the emitter of said second transistor being tied to said amplifieR''s supply terminal, and means coupling said amplifier''s input terminal to the base of said first transistor.
Claim 9
Dependent Claim
158 words
An apparatus for the measurement of temperature, as recited in claim 7, wherein: a. said AC amplifier further includes an amplification stage having an input and an output, said input being coupled to said amplifier''s input terminal, and said output being coupled to the base of said first transistor, and b. said stabilizing means comprises: i. a level detecting means having said output voltage on said amplifier''s output terminal coupled thereto, said level detecting means including a source of standard voltage, and means comparing said output voltage with said standard voltage to produce a control signal whose magnitude and sense are determined by their difference, ii. a controllable variable impedance which is coupled between the base of said first transistor and said amplifier''s reference terminal, said controllable variable impedance including a control terminal, and iii. means coupling said control signal to said control terminal, whereby said output voltage is regulated at a value determined by said standard voltage.
Claim 10
Dependent Claim
34 words
An apparatus for the measurement of temperature, as recited in claim 8, wherein said controllable variable impedance comprises a field-effect transistor having a gate terminal, said control signal being coupled to said gate terminal.
Claim 11
Dependent Claim
70 words
An apparatus for the measurement of temperature, as recited in claim 8, and further including a second AC amplifier, said second amplifier also including input, output, supply and reference terminals, said source of supply voltage being connected across its supply and reference terminals, said second amplifier''s input terminal being connected to said first amplifier''s output terminal and said second second amplifier''s output terminal being coupled to said level detecting means.
Claim 12
Dependent Claim
75 words
An apparatus for the measurement of temperature, as recited in claim 10, and further comprising an isolation means having an input terminal which is connected to said second amplifier''s output terminal and having a circuit output terminal, said isolation means including a field-effect transistor interposed between said input terminal and said circuit output terminal thereof which blocks impedance changes occurring at said circuit output terminal from occurring at said output terminal of said second amplifier.
Claim 13
Dependent Claim
66 words
An apparatus for the measurement of temperature, as recited in claim 1, further comprising an isolation means having said output voltage on said amplifier''s output terminal connected thereto, said isolation means including a circuit output terminal, and means coupling said amplifier''s output terminal to said circuit output terminal which blocks changes in impedance appearing at said circuit output terminal from appearing at said amplifier''s output terminal.
Claim 14
Dependent Claim
26 words
An apparatus for the measurement of temperature, as recited in claim 1, wherein said temperature-dependent resistor is located in said series branch of said frequency-selective network.
Claim 15
Dependent Claim
26 words
An apparatus for the measurement of temperature, as recited in claim 1 wherein said temperature-dependent resistor is located in said parallel branch of said frequency-selective network.
Claim 16
Dependent Claim
95 words
An oceanographic thermometer for providing in-situ measurements of the temperature of sea water, comprising an apparatus as recited in claim 1, and further comprising: a. a waterproof, pressure-proof housing, b. means supporting said temperature-dependent resistor from said housing and in fluid contact with the sea water, c. means maintaining the remaining portion of said frequency-selective network, said AC amplifier, and said stabilizing means within said housing, and d. underwater connector means providing for connection of said amplifier''s output, supply and reference terminals to an external monitoring means and to said source of supply voltage, respectively.
Claim 17
Dependent Claim
30 words
An oceanographic tHermometer as recited in claim 15, further including a voltage regulating means interposed between said underwater connector means and said supply and reference terminals of said AC amplifier.
Claim 18
Dependent Claim
53 words
An oceanographic thermometer as recited in claim 15 wherein said means supporting said temperature-dependent resistor includes an underwater female receptacle disposed on said housing, a probe structure having said temperature-dependent resistor disposed therein, and an underwater male connector attached to said probe structure which is adapted for water-tight engagement with said female receptacle.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-07-11 | 1976-01-10 | 1976-07-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-07-11 | 1980-01-10 | 1980-07-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-07-11 | 1984-01-10 | 1984-07-11 | $7700.00 | Window Closed / Lapsed |