Patent US3665302A successfully refreshed from Google Patents.
US3665302A
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US
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Methods and apparatus for determining the condition of food
Assignee: NAT RES DEV
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Filing: 1970-02-19
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Granted: 1972-05-23
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Expires: 1990-02-19
Abstract
Abstract A method and an apparatus are described for testing the condition of foods, particularly fish. It has been found that the dielectric properties of some foods vary with time and consequently that the electrical quality factor and phase angle of a food sample are indicative of the amount of spoilage of the food. A probe comprising two pairs of electrodes is described for use in measuring the phase angle of a sample. The construction of the probe and the apparatus coupled thereto prevents interfacial polarization where one pair of electrodes contact the sample, and hence one important source of error is overcome. The phase angle is found by passing a current through the sample and measuring the relative phase of the current and of a potential sensed between the electrodes of the said pair.
Inventors
- 👤 Alexander Lees
- 👤 John Charles Shenston Richards
- 👤 Alfred Charles Jason
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 09:16
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/02; G01N33/00; G01N33/02; G01N33/12
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
126 words
Apparatus for determining the condition of a sample of a specified food, including first and second pairs of electrodes adapted to make contact with a sample of food, means for passing a current between the first pair of electrodes, sensing means for sensing the potential between the electrodes of the second pair without drawing sufficient current to cause substantial interfacial polarization between the electrodes of the second pair and the sample, and means for deriving, from the current and the potential, signals representative of an attribute of the sample which depends on at least one of the said dielectric properties of the food, including measuring means for measuring the phase angle phi of the sample by determining the phase angle between the current and the potential.
Claim 2
Dependent Claim
126 words
Apparatus for determining the condition of a sample of a specified food, including first and second pairs of electrodes adapted to make contact with a sample of food, means for passing a current between the first pair of electrodes, sensing means for sensing the potential between the electrodes of the second pair without drawing sufficient current to cause substantial interfacial polarization between the electrodes of the second pair and the sample, and means for deriving, from the current and the potential, signals representative of an attribute of the sample which depends on at least one of the said dielectric properties of the food, including measuring means for measuring the phase angle phi of the sample by determining the phase angle between the current and the potential.
Claim 3
Dependent Claim
86 words
Apparatus according to claim 1 wherein the measuring means includes means for deriving a voltage in phase with the current, delay means for changing the phase angle of the voltage by 90* to provide a gate control signal, and a gate circuit coupled to the delay means and the sensing means to be opened wherever the gate control signal has a predetermined polarity, to allow a signal in phase with the potential between the electrodes of the second pair to pass to integrating and indicating means.
Claim 4
Dependent Claim
50 words
Apparatus according to claim 2 wherein the means for sensing the potential between the second pair of electrodes includes two high-impedance input voltage-follower circuits and a differential amplifier, the electrodes of the second pair being coupled to the inputs of the differential amplifiers by way of the voltage-follower circuits respectively.
Claim 5
Dependent Claim
44 words
Apparatus according to claim 1 wherein the means for measuring the phase angle includes means for deriving a voltage in phase with the current and phase-comparison means for comparing the relative phases of the potential between the second pair of electrodes and the voltage.
Claim 6
Dependent Claim
91 words
Apparatus according to claim 4 wherein the sensing means and the measuring means include first and second circuits for forming square-wave signals having a fixed phase relationship with the said potential and the said voltage, respectively, and wherein a switched current source is coupled to the first and second circuits to provide a constant output current for integrating and indicating means during intervals between the occurrence of the leading or trailing edges of one square-wave signal and that of the following leading or trailing edge, respectively, of the other square-wave signal.
Claim 7
Dependent Claim
68 words
Apparatus according to claim 5 wherein the first said circuit includes a first high-impedance differential amplifier with input terminals coupled to the electrodes of the first pair, and the second said circuit includes a second high-impedance differential amplifier with input terminals coupled across a resistor in series with the electrodes of the first pair of electrodes and the means for passing current between the first pair of electrodes.
Claim 8
Dependent Claim
95 words
Apparatus for determining the condition of a sample of a specified food, including first and second pairs of electrodes adapted to make contact with a sample of food, means for passing a current between the first pair of electrodes, sensing means for sensing the potential between the electrodes of the second pair without drawing sufficient current to cause substantial interfacial polarization between the electrodes of the second pair and the sample, and means for deriving, from the current and the potential, a signal which is representative of the electrical quality factor Q of the sample.
Claim 9
Dependent Claim
95 words
Apparatus for determining the condition of a sample of a specified food, including first and second pairs of electrodes adapted to make contact with a sample of food, means for passing a current between the first pair of electrodes, sensing means for sensing the potential between the electrodes of the second pair without drawing sufficient current to cause substantial interfacial polarization between the electrodes of the second pair and the sample, and means for deriving, from the current and the potential, a signal which is representative of the electrical quality factor Q of the sample.
Claim 10
Dependent Claim
94 words
Apparatus for use in evaluating a material including first and second pairs of electrodes adapted to make contact with a sample of the material, means for passing a current between the first pair of electrodes, sensing means for sensing the potential between the second pair of electrodes without drawing a substantial current, and means for deriving from the current and potential a signal which is representative of a product CR where C is an equivalent capacitance and R is an equivalent resistance which when connected in parallel represent the electrical behavior of the sample.
Claim 11
Dependent Claim
94 words
Apparatus for use in evaluating a material including first and second pairs of electrodes adapted to make contact with a sample of the material, means for passing a current between the first pair of electrodes, sensing means for sensing the potential between the second pair of electrodes without drawing a substantial current, and means for deriving from the current and potential a signal which is representative of a product CR where C is an equivalent capacitance and R is an equivalent resistance which when connected in parallel represent the electrical behavior of the sample.
Claim 12
Dependent Claim
69 words
Apparatus according to claim 7 wherein all the electrodes have one surface in a common plane, and in that plane one electrode of the first pair forms a loop containing the other electrodes, one electrode of the second pair forms a loop containing the other electrodes of the two pairs, and the other electrode of the second pair forms a loop containing the other electrode of the first pair.
Claim 13
Dependent Claim
40 words
Apparatus according to claim 7 wherein all the electrodes have one surface in a common plane, and in that plane each electrode of the first pair forms a loop containing a different one of the electrodes of the second pair.
Claim 14
Dependent Claim
25 words
Apparatus according to claim 7 wherein the electrodes of the first pair are of graphite while those of the second pair are of stainless steel.
Claim 15
Independent Claim
117 words
A method for determining the condition of a sample of a specified food, comprising the steps of contacting: first and second pairs of electrodes with a sample of food, passing a current between the first pair of electrodes, sensing the potential between the electrodes of the second pair without drawing sufficient current to cause substantial interfacial polarization between the electrodes of the second pair and the sample, and deriving, from the current and the potential, signals representative of an attribute of the sample which depends on at aleast one of the said dielectric properties of the food, including measuring the phase angle phi of the sample by determining the phase angle between the current and the potential.
Claim 16
Independent Claim
117 words
A method for determining the condition of a sample of a specified food, comprising the steps of contacting: first and second pairs of electrodes with a sample of food, passing a current between the first pair of electrodes, sensing the potential between the electrodes of the second pair without drawing sufficient current to cause substantial interfacial polarization between the electrodes of the second pair and the sample, and deriving, from the current and the potential, signals representative of an attribute of the sample which depends on at aleast one of the said dielectric properties of the food, including measuring the phase angle phi of the sample by determining the phase angle between the current and the potential.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-05-23 | 1975-11-22 | 1976-05-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-23 | 1979-11-22 | 1980-05-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-23 | 1983-11-22 | 1984-05-23 | $7700.00 | Window Closed / Lapsed |