US3889053A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Contactless test system
Assignee: Westinghouse Electric Corp
•
Filing: 1973-10-30
•
Granted: 1975-06-10
•
Expires: 1993-10-30
Abstract
Abstract A system for checking the operational status of individual members of a class of electric circuits is disclosed. The operational status of the circuit being inspected is determined by comparing the temperature patterns of the circuit being inspected with the temperature pattern of a similar circuit known to be free of operational defects. An operational circuit of the class to be inspected is coated with a cholesteric liquid crystal to convert the temperature patterns of the surface of the circuit to color pattern. A black and white TV camera is focused on the circuit. The video signal generated by the TV camera is sampled and the samples are digitized to generate a series of digital numbers which are stored in a memory. The circuit to be inspected is similarly coated with the liquid crystal, the TV camera is focused on the circuit to be inspected and the video signal generated by the TV camera is sampled and digitized to generate a second series of numbers which are also stored in a memory. Corresponding members of the first and second series of numbers are then compared by a digital computer to determine areas of the circuit in which intensity of the temperature patterns are abnormal. Any normal temperature patterns are analyzed to determine if the abnormality is significant. A signal is generated indicating that the circuit is defective if a significant abnormality is found.
Inventors
- 👤 Raymond A Lloyd
- 👤 William L Hrybyk
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 07:53
CPC Classifications
G; G01; G01R; G01R31/00; G01R31/28; G01R31/302; G01R31/308; G01N; G01N21/00; G01N21/17; G01N21/25
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
157 words
A method for inspecting a member of a class of related device to determine its operational status, comprising the steps of: a. coating the surface of a reference member with a first heat sensitive layer to convert heat patterns to light patterns; b. scanning the surface of said first heat sensitive layer with a light sensitive device to generate a reference signal indicative of the temperature distribution of the surface of said reference member; c. coating the surface of the member to be inspected with a second heat sensitive layer to convert heat patterns to light patterns; d. scanning the surface of said second heat sensitive layer with a light sensitive detector to generate a test signal indicative of the temperature distribution of the surface of said member; e. comparing said reference and test signals to identify difference therebetween; f. statistically analyzing said difference to determine if said member to be inspected is operating within prescribed limits.
Claim 2
Independent Claim
157 words
A method for inspecting a member of a class of related device to determine its operational status, comprising the steps of: a. coating the surface of a reference member with a first heat sensitive layer to convert heat patterns to light patterns; b. scanning the surface of said first heat sensitive layer with a light sensitive device to generate a reference signal indicative of the temperature distribution of the surface of said reference member; c. coating the surface of the member to be inspected with a second heat sensitive layer to convert heat patterns to light patterns; d. scanning the surface of said second heat sensitive layer with a light sensitive detector to generate a test signal indicative of the temperature distribution of the surface of said member; e. comparing said reference and test signals to identify difference therebetween; f. statistically analyzing said difference to determine if said member to be inspected is operating within prescribed limits.
Claim 3
Dependent Claim
22 words
The method defined by claim 1 wherein said first and second heat sensitive layers are thin layers of a cholesteric liquid crystal.
Claim 4
Dependent Claim
29 words
The method defined by claim 2 wherein said reference signal and said test signal are generated by focusing a TV camera on said first and second heat sensitive layers.
Claim 5
Dependent Claim
26 words
The method defined by claim 3 wherein said reference and test signals are similarly sampled and digitized to generate first and second arrays of digited members.
Claim 6
Dependent Claim
30 words
The method defined by claim 4 wherein corresponding elements of said first and second arrays of digital numbers are compared to generate a third array, equal to the difference therebetween.
Claim 7
Dependent Claim
131 words
Apparatus for inspecting a member of a class of related devices comprising: a. means for generating a visible display of the temperature gradient across a reference member of said class of related devices; b. means for scanning said visible display to generate reference data; c. means for generating a visible display of the temperature gradient across the member of said class of related devices to be inspected; d. means for scanning the visible display of the temperature gradient across said member of said related devices to generate test data; e. means for comparing said reference and test data to generate comparison data related to the difference between said reference and test data; and f. means for statistically analyzing said comparison data to determine the operational status by the member being inspected.
Claim 8
Dependent Claim
131 words
Apparatus for inspecting a member of a class of related devices comprising: a. means for generating a visible display of the temperature gradient across a reference member of said class of related devices; b. means for scanning said visible display to generate reference data; c. means for generating a visible display of the temperature gradient across the member of said class of related devices to be inspected; d. means for scanning the visible display of the temperature gradient across said member of said related devices to generate test data; e. means for comparing said reference and test data to generate comparison data related to the difference between said reference and test data; and f. means for statistically analyzing said comparison data to determine the operational status by the member being inspected.
Claim 9
Dependent Claim
43 words
The apparatus defined by claim 6 wherein said means for generating the visible display of the temperature gradients across said reference member and the member to be inspected includes a thin layer of cholesteric liquid crystal disposed on the surface of said meMbers.
Claim 10
Dependent Claim
31 words
The apparatus defined by claim 7 wherein said reference and test data are generated by sampling and digitizing the video output signal of a TV camera focused on said liquid crystal.
Claim 11
Dependent Claim
19 words
The apparatus defined by claim 8 wherein said means for statistically analyzing said comparison data includes a digital computer.
References Cited (Backward Citations)
US2895049A
Cited
US3049588A
Cited
US3533399A
Cited
US3283148A
Cited
US3718757A
Cited
US3798366A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-06-09 | 1978-12-09 | 1979-06-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-06-09 | 1982-12-09 | 1983-06-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-06-09 | 1986-12-09 | 1987-06-10 | $7700.00 | Window Closed / Lapsed |