Machine-vision illumination system and method for delineating a lighted ...

[54] MACHINE-VISION ILLUMINATION SYSTEM AND METHOD FOR DELINEATING A LIGHTED VOLUME FROM AN UNLIGHTED VOLUME

[75] Inventor: Gary A. Lebens, Chaska, Minn.
[73] Assignee: PPT Vision, Inc., Eden Prairie, Minn.

[21] Appl. No.: 532,213
[22] Filed: Oct. 12,1995

[51] Int. CI.6 H04N 7/18; H04N 9/47;

H04N 5/222

[52] U.S. CI 348/370; 348/131; 348/132;

359/739; 362/244; 362/248; 235/462

[58] Field of Search 359/738, 739;

362/234, 235, 236, 244, 248; 348/86. 87, 370, 371, 125,126, 127, 128, 131, 132; 235/454, 462; H04N 5/222, 7/18, 9/47

[56] References Cited

U.S. PATENT DOCUMENTS

3,663,752 5/1972 Froschle 178/7.2

4,743,773 5/1988 Katanaetal 250/566

4,882,498 11/1989 Cochran et al 250/571

4,972,093 11/1990 Cochran et al 250/572

5,010,412 4/1991 Gairiss 358/240

5,051,825 9/1991 Cochran et al 358/106

5,072,127 12/1991 Cochran et al 250/572

5,172,005 12/1992 Cochran et al 250/57

5,354,977 10/1994 Roustaei 235/472

5,468,950 11/1995 Hanson 235/472

5,604,550 2/1997 White 396/429

OTHER PUBLICATIONS

Hewlett Packard OptoElectronics Designer's Catalog, Technical Data entitled "High power AllnGaP Amber and Reddish-Orange Lamps," pp. 3-24 through 3-29, 1993. Edmund Scientific Company 1993 Annual Reference Catalog, "Cylinder Lenses (CYL)"; catalog pp.47.

Primary Examiner—Thai Tran

Assistant Examiner—Ngoc-Yen Vu

Attorney, Agent, or Firm—Schwegman, Lundberg,

Woessner & Kluth P.A.

[57] ABSTRACT

The present invention takes advantage of the efficiency of high-brightness red, infra-red, or other color LEDs arranged in a single row, the properties inherent to a focusing element such as a cylindrical lens, as well as the advantages of having a straight-edged diaphragm and a light-absorbing enclosure to produce an illumination source for machinevision systems. The illumination source exhibits multidirectional properties on one side of an imaginary plane defined by the positions of the row of LEDs, the straightedged diaphragm, and the focusing element, and imnimize light cast on the other side of the plane. The present invention provides a compact light line generator which has no shadowing or secondary lines. The present invention also provides a method for measuring the height of a raised surface. The present invention provides a method and apparatus which provide an illumination source for illuminating an object in a machine-vision system, and includes a light source emitting light from a plurality of points, the points being on a straight line, a focusing element, the focusing element focusing light from the light source in one dimension to a focal line, wherein the focusing element is separated from the straight line by a distance sufficient to focus rays from the plurality of points into the focal line, and wherein there is a light path from the straight line to: the focusing element and then to the focal line, and a first diaphragm located in the light path and defining a sharp edge in the rays. This embodiment provides a light which has a sharply defined virtual surface which separates lighted areas from areas not lit, and within the lighted areas, provides light from multiple directions to reduce shadowing.

24 Claims, 8 Drawing Sheets