CONTACTLESS INFRARED DIAGNOSTIC TEST SYSTEM

• US 3,868,508 A
• Filed: 10/30/1973
• Issued: 02/25/1975
• Est. Priority Date: 10/30/1973
• Status: Expired due to Term

• Current Assignee: Raymond A. Lloyd
• Original Assignee: Raymond A. Lloyd
• Inventors: Lloyd, Raymond A.
• Primary Examiner(s): Borchelt, Archie R.
• Application Number:
  US05/411,110
• Time in Patent Office: 483 Days
• Field of Search: 250/252,330,333,334,338
• US Class Current: 250/330
• CPC Class Codes: G01R 31/2806 Apparatus therefor, e.g. test stations, drivers, analysers, conveyors G01R31/2805, G01R31/281, G01R31/2818 take precedence
• CPC Class Codes: G01R 31/308 using non-ionising electromagnetic radiation, e.g. optical radiation investigating or analysing materials by the use of optical means G01N21/00; image analysis G06T7/00
• CPC Class Codes: G01R 31/309 of printed or hybrid circuits or circuit substrates

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 infrared radiation patterns of the circuit being inspected with the infrared patterns radiated by a similar circuit known to be free of operational defects. An infrared TV camera is focused on a circuit known to be free of defects. The TV signal is sampled and the samples are digitized to generate a series of digital numbers which are stored in a memory. The TV camera is then focused on the circuit to be inspected and the TV signal 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 board in which the intensity of the infrared radiation is abnormal. Any abnormal infrared radiation is analyzed to determine if the abnormality is significant. A signal is generated indicating that the circuit is defective if a significant abnormality is found.

Claims

1. A method for inspecting a member of a class of related device to determine its operational status, comprising the steps of:

a. scanning the infrared pattern generated by a reference member of said class of related devices with an infrared detector to generate a reference signal indicative of the infrared radiation emitted by said reference member;

b. scanning the infrared pattern generated by the member to be inspected with an infrared detector to generate a test signal indicative of the infrared radiation emitted by said member;

c. comparing said reference and test signals to identify difference Therebetween;

d. statistically analyzing said difference to determine if said member to be inspected in operating within prescribed limits.

2. The method defined by claim 1 wherein the infrared pattern generated by said reference member is scanned by focusing an infrared TV camera on said reference member to generate said reference signal.

3. The method defined by claim 2 wherein the infrared pattern generated by said member to be inspected is scanned by focusing an infrared TV camera on said member to generate said test signal.

4. 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 numbers.

5. The method defined by claim 4 wherein corresponding elements of said first and second arrays of ditital numbers are compared to generate a third array, equal to the difference therebetween.

6. Apparatus for inspecting a member of a class of related devices comprising:

a. means for examining a reference member of said class of related devices to generate reference data by detecting a parameter having a predictable relationship to the operation of members of said class of related devices;

b. means for examining the member of said class of related devices to be inspected to generate test data by detecting said parameter;

c. means for comparing said reference and test data to generate comparison data related to the difference between said reference and test data; and

d. means for statistically analyzing said comparison data to determine the operational status by the member being inspected.

7. The apparatus defined by claim 6 wherein said means for examining said reference member and the member to be inspected includes a TV camera.

8. The apparatus defined by claim 7 wherein said reference and test data are generated by sampling and digitizing the video output signal by said TV camera.

9. The apparatus defined by claim 8 wherein said means for statistically analyzing said comparison data includes a digital computer.