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United States Patent  [ii] Patent Number: 5,745,176
Lebens  Date of Patent: Apr. 28, 1998
 MACHINE-VISION ILLUMINATION SYSTEM AND METHOD FOR DELINEATING A LIGHTED VOLUME FROM AN UNLIGHTED VOLUME
 Inventor: Gary A. Lebens, Chaska, Minn.
 Assignee: PPT Vision, Inc., Eden Prairie, Minn.
 Appl. No.: 532,213
 Filed: Oct. 12,1995
 Int. CI.6 H04N 7/18; H04N 9/47;
 U.S. CI 348/370; 348/131; 348/132;
359/739; 362/244; 362/248; 235/462
 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
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Primary Examiner—Thai Tran
Assistant Examiner—Ngoc-Yen Vu
Attorney, Agent, or Firm—Schwegman, Lundberg,
Woessner & Kluth P.A.
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