Video inspection system employing multiple spectrum LED illumination

• US 5,365,084 A
• Filed: 12/14/1992
• Issued: 11/15/1994
• Est. Priority Date: 02/20/1991
• Status: Expired due to Term

• Current Assignee: Pressco Technology Inc.
• Original Assignee: Pressco Technology Inc.
• Inventors: Cochran, Don W., Triner, James E.
• Primary Examiner(s): Nelms, David C.
• Assistant Examiner(s): Lee, John R.
• Application Number:
  US07/990,009
• Time in Patent Office: 701 Days
• Field of Search: 250/560, 250/561, 250/562, 250/571, 250/572, 250/226, 250/234, 250/235, 250/236, 356/376, 356/379, 356/380, 356/386, 356/387, 356/430, 356/431, 356/434, 356/435, 358/101, 358/106
• US Class Current: 250/559.02
• CPC Class Codes: G01N 2021/8835 Adjustable illumination, e.g. software adjustable screen
• CPC Class Codes: G01N 2021/8845 Multiple wavelengths of illumination or detection
• CPC Class Codes: G01N 2021/8887 based on image processing techniques
• CPC Class Codes: G01N 21/8806 Specially adapted optical and illumination features
• CPC Class Codes: G01N 21/8901 Optical details; Scanning details per se G02B
• CPC Class Codes: G01N 21/8903 using a multiple detector array
• CPC Class Codes: G01N 2201/0621 Supply
• CPC Class Codes: H04N 7/181 for receiving images from a plurality of remote sources
• CPC Class Codes: H04N 7/188 Capturing isolated or intermittent images triggered by the occurrence of a predetermined event, e.g. an object reaching a predetermined position signal generation from motion picture films H04N5/253

Abstract

An engineered lighting system for high speed video inspection includes an array of light emitting diodes including light emitting diodes for use in time delay integration (TDI) inspection of web materials. The light emitting diodes of the array are selectively controllable to accomplish sequential illumination and carefully controllable imaging of a specified section of a continuously moving specimen or specimens. LEDs with different wavelength light output, or multi-wavelength light LEDs are utilized for rapid and reliable inspection of surfaces with varying color or contour or detect characteristics. The system also includes an array of optional backlighting elements to aid in illumination of semi-opaque specimens to accomplish inspection thereof.

Claims

1. An engineered video inspection illumination system comprising:

a first array of light emitting diodes adapted to provide illumination of a plurality of selected wavelength quanta;

first securing means adapted to secure the first array so as to illuminate an associated specimen disposed in an illumination region of the first array;

means for selectively supplying current to the first array so as to generate inspection light therefrom having a selected light constituent of first and second wavelengths; and

video receptor means adapted for receiving the inspection light after exposure thereof to the associated specimen.

2. The engineered video inspection illumination system of claim 1 wherein the video reception means includes isolation means for segregating the first and second wavelength quanta of the inspection light into first and second images, respectively.

3. The engineered video inspection illumination system of claim 2 wherein the video receptor means includes first and second video sensors, and wherein the isolation means includes:

a first filter, adapted to filter a first selected wavelength, disposed to intercept the inspection light prior to exposure to the first video sensor; and

a second filter, adapted to filter a selected wavelength, different than the first selected wavelength, disposed to intercept the inspection light prior to exposure of the second video sensor.

4. The engineered video inspection illumination system of claim 2 wherein the video receptor means includes first and second spatially separated video sensors, and wherein the isolation means includes a prism disposed to intercept the inspection light prior to exposure of the first and second spatially separated video sensors.

5. The engineered video inspection illumination system of claim 2 wherein the video receptor means includes first and second spatially separated video sensors, and wherein the isolation means includes a diffraction grating disposed to intercept the inspection light prior to exposure of the first and second spatially separated video sensors.

6. The engineered video inspection illumination system of claim 2 wherein the light emitting diodes of the first array are composed of visible light generating devices.

7. The engineered video inspection illumination system of claim 1 wherein the first array includes:

a first plurality of diodes, each of which provide light at a first wavelength quanta; and

a second plurality of diodes which provide light at a second wavelength quanta.

32. The engineered video inspection system of claim 1 wherein the first array of light emitting diodes includes means for providing one of the plurality of selected wavelength quanta in the visible spectrum and another of the plurality of selected wavelength in the invisible spectrum.

33. The engineered video inspection system of claim 32 wherein the selected wavelength quanta in the invisible spectrum is infrared.

34. The engineered video inspection system of claim 32 wherein the selected wavelength quanta in the invisible spectrum is ultraviolet.

35. The engineered video inspection system of claim 32 further comprising video receptor means adapted to receiving the inspection light after exposure thereof to the associated specimen, the video receptor means including isolation means for segregating the first and second wavelength quanta of the inspection light into first and second images, respectively.

36. The engineered video inspection system of claim 1 wherein the first array of light emitting diodes includes means for providing the plurality of selected wavelength quanta in the invisible spectrum.

37. The engineered video inspection system of claim 36 wherein the selected wavelength quanta in the invisible spectrum is infrared.

38. The engineered video inspection system of claim 36 wherein the selected wavelength quanta in the invisible spectrum is ultraviolet.

39. The engineered video inspection system of claim 36 further comprising video receptor means adapted to receiving the inspection light after exposure thereof to the associated specimen, the video receptor means including isolation means for segregating the first and second wavelength quanta of the inspection light into first and second images, respectively.

8. An engineered video inspection illumination system comprising:

a first array of light emitting diodes adapted to provide illumination of a plurality of selected wavelength quanta, wherein the first array includes a plurality of multi-spectrum diodes;

first securing means adapted to secure the first array so as to illuminate an associated specimen disposed in an illumination region of the first array; and

means for selectively supplying current to the first array so as to generate inspection light therefrom having a selected light constituent of first and second wavelengths.

9. An engineered video inspection system comprising:

a first array of light emitting diodes adapted to provide illumination of a plurality of selected wavelength quanta;

first securing means adapted to secure the first array so as to illuminate an associated specimen disposed in an illumination region of the first array;

means for selectively supplying current to the first array so as to generate inspection light therefrom having a selected light constituent of first and second wavelengths;

means for receiving a displacement signal representative of a linear displacement of the associated specimen relative to the first array over a selected scan period; and

controller means for selectively supplying a current pulse to the light emitting diodes during the scan period in accordance with the displacement signal such that each of a plurality of generally linear sections of the associated specimen is illuminated a plurality of times by the light emitting diodes.

10. The engineered video inspection illumination system of claim 9 further comprising:

video receptor means adapted for receiving the inspection light after exposure thereof to the associated specimen.

11. The engineered video inspection illumination system of claim 10 wherein the video receptor means includes isolation means for segregating the first and second wavelength quanta of the inspection light into first and second images, respectively.

12. The engineered video inspection illumination system of claim 11 wherein the video receptor means includes first and second video sensors, and wherein the isolation means includes:

a first filter, adapted to filter at least a first selected wavelength, disposed to intercept the inspection light prior to exposure to the first video sensor; and

a second filter, adapted to filter at least a selected wavelength, different than the first selected wavelength, disposed to intercept the inspection light prior to exposure of the second video sensor.

13. The engineered video inspection system of claim 12 wherein the light emitting diodes of the first array are composed of visible light generating devices.

14. The engineered video inspection illumination system of claim 11 wherein the video receptor means includes first and second spatially separated video sensors, and wherein the isolation means includes a prism disposed to intercept the inspection light prior to exposure of the first and second spatially separated video sensors.

15. The engineered video inspection illumination system of claim 11 wherein the video receptor means includes first and second spatially separated video sensors, and wherein the isolation means includes a diffraction grating disposed to intercept the inspection light prior to exposure of the first and second spatially separated video sensors.

16. The engineered video inspection illumination system of claim 9 wherein the first array includes:

a first plurality of diodes, each of which provide light at a first wavelength subset; and

a second plurality of diodes which provide light at a second wavelength subset.

17. The engineered video inspection illumination system of claim 9 wherein the first array includes a plurality of multi-spectra diodes.

18. A method of multiple wavelength video inspection specimen illumination comprising the steps of:

selectively providing a current pulse to first array of light emitting diodes adapted to provide illumination of a plurality of selected wavelength quanta, the step including selectively supplying current to the first array so as to generate inspection light therefrom having a selected light constituent of first and second wavelengths;

illuminating an associated specimen disposed in an illumination region of the first array with light of the first array;

receiving a displacement signal representative of a linear displacement of an associated specimen relative to the array; and

selectively providing the current pulse so as to provide the current pulse in accordance with the displacement signal.

19. The method of multiple wavelength video inspection of claim 18 further comprising the step of selectively providing the current pulse so as to provide the illumination with a specified spectral content.

20. The method of multiple wavelength video inspection of claim 19 further comprising the step of selectively providing the current pulse so as to provide the illumination with a specified duration.

21. The method of claim 20 wherein the step of selectively providing includes the step of selectively supplying the current to the first array so as to generate inspection light composed of visible light.

22. An engineered video inspection illumination system comprising:

a first array of light emitting diodes adapted to provide illumination of at least one selected wavelength range;

a second light source, formed from at least one conventional lamp, adapted to provide illumination of a plurality secondary wavelengths;

first securing means adapted to secure the first array and the second light source so as to illuminate an associated specimen disposed in an illumination region of the first array;

means for selectively supplying current to the first array so as to generate inspection light therefrom having a selected light constituent of first and second wavelengths; and

video receptor means adapted for receiving the inspection light after exposure thereof to the associated specimen.

23. The engineered video inspection illumination system of claim 22 wherein the video receptor means includes isolation means for segregating the first and second wavelength of the inspection light into a first image and at least a second wavelength of the plurality of secondary wavelengths into a second image.

24. The engineered video inspection illumination system of claim 23 wherein the video receptor means includes first and second video sensors, and wherein the isolation means includes:

a first filter, adapted to filter a first selected wavelength, disposed to intercept the inspection light prior to exposure to the first video sensor; and

a second filter, adapted to filter the second selected wavelength, different than the first selected wavelength, disposed to intercept the inspection light prior to exposure of the second video sensor.

25. The engineered video inspection illumination system of claim 24 wherein the light emitting diodes of the first array are composed of visible light generating devices.

26. An engineered video inspection illumination system comprising:

a first array of light emitting diodes adapted to provide illumination of at least one selected wavelength range;

first securing means adapted to secure the first array so as to illuminate an associated specimen disposed in an illumination region of the first array;

means for selectively supplying current to the first array so as to generate inspection light therefrom having a selected light constituent of at least a first wavelengths;

video receptor means adapted for receiving the inspection light after exposure thereof to the associated specimen;

means for securing the video receptor means so as to be non-orthogonal to a direction of travel of the associated specimen relative thereto; and

the video receptor means including a perspective control lens having its field of view directed to the illumination region.

27. The engineered video inspection system of claim 26 wherein:

the first array of light emitting diodes includes means for providing illumination of at least a second selected wavelength range;

the means for selectively supplying current to the first array includes means for selectively supplying current thereto so as to generate inspection light therefrom having a selected light constituent of the second wavelength range.

28. The engineered video inspection illumination system of claim 27 wherein the video receptor means includes isolation means for segregating light of the first and second wavelength range into first and second images, respectively.

29. The engineered video inspection illumination system of claim 28 wherein the video receptor means includes first and second video sensors, and wherein the isolation means includes:

a first filter, adapted to filter a first selected wavelength, disposed to intercept the inspection light prior to exposure to the first video sensor; and

a second filter, adapted to filter a selected wavelength, different than the first selected wavelength, disposed to intercept the inspection light prior to exposure of the second video sensor.

30. The engineered video inspection illumination system of claim 29 further comprising:

means for receiving a displacement signal representative of a linear displacement of the associated specimen relative to the first array over a selected scan period; and

controller means for selectively supplying a current pulse to the light emitting diodes during the scan period in accordance with the displacement signal such that each of a plurality of generally linear sections of the associated specimen is illuminated a plurality of times by the light emitting diodes.

31. The engineered video inspection system of claim 30 wherein the light emitting diodes of the first array are composed of visible light generating devices.