Electro-optical inspection

• US 5,114,230 A
• Filed: 01/03/1990
• Issued: 05/19/1992
• Est. Priority Date: 09/07/1979
• Status: Expired due to Term

• Current Assignee: Sensor Adaptive Machines, Inc.
• Original Assignee: Diffracto, Ltd. (Lmi Technologies Incorporated)
• Inventors: Pryor, Timothy R.
• Primary Examiner(s): Huppert, Michael S.
• Assistant Examiner(s): Wacyra, Edward M.
• Application Number:
  US07/460,641
• Time in Patent Office: 867 Days
• Field of Search: 209/555, 209/556, 209/558, 209/586, 209/587, 209/588, 250/560, 250/561, 250/562, 250/571, 250/572, 356/23, 356/72, 356/73, 356/375, 356/376, 356/381, 356/383-387, 356/394, 356/237, 356/372
• US Class Current: 356/625
• CPC Class Codes: G01B 11/2433 for measuring outlines by shadow casting

Abstract

A method and apparatus for inspecting workpieces for rapid and accurate determination of dimensions and the like. The equipment is electro-optical in nature and there is no contact between the inspecting elements and the workpiece under inspection. An electro-optical sensor is utilized which includes a light source for illuminating at least one edge of a workpiece, a lens for forming an image of the illuminated edge, and an array of photosensitive elements, such a photodiodes, capable of producing an electrical signal in response to light incident thereon. The light, including the edge image, is impinged upon the array and the electrical signals produced correspond to the portion of the edge, its shape, etc. The signals can be rapidly analyzed to provide a determination of a dimension such as length, squareness, curvature, and the like.

Claims

1. Apparatus for simultaneously determining two dimensions of a workpiece comprising:

an inspection station;

electro-optical sensor means for generating a first set of signals indicative of two dimensions of the workpiece in said inspection station and for generating a second set of signals indicative of a two dimensional position of the workpiece in said inspection station; and

means for analyzing said first and second sets of signals to determine the two dimensions of said workpiece.

2. Apparatus according to claim 1 further comprising physical means for constraining the workpiece in said inspection station.

3. Apparatus according to claim 1 wherein said electro-optical sensor means comprises:

light source means for illuminating the workpiece in said inspection station;

a single lens for forming images of a plurality of illuminated portions of the illuminated workpiece; and

light detector means comprising a plurality of discrete photodetectors capable of generating said first and second sets of signals in response to light incident thereon, each photodetector being positioned to receive from said single lens an image of a respective illuminated portion of the illuminated workpiece.

4. Apparatus according to claim 1 wherein said electro-optical sensor means comprises:

light source means for illuminating the workpiece in said inspection station;

a single lens for forming images of a plurality of illuminated portions of the illuminated workpiece;

light detector means comprising a first set of discrete photodetectors capable of generating said first set of signals in response to light incident thereon and a second set of discrete photodetectors capable of generating said second set of signals in response to light incident thereon, each photodetector being positioned to receive from said single lens an image of a respective illuminated portion of the illuminated workpiece.

5. Apparatus according to claim 1 wherein said electro-optical sensor means comprises means for illuminating the workpiece in said inspection station, a single lens for forming images of a plurality of illuminated portions of the illuminated workpiece, and photodetector means for generating said first and second sets of signals, said photodetector means comprising a plurality of photodetectors positioned to detect from said single lens the images of the illuminated portions of the illuminated workpiece.

6. Apparatus according to claim 5 wherein a plurality of said photodetectors are positioned adjacent to an illuminated side of said workpiece.

7. Apparatus according to claim 1 further comprising means for mounting said electro-optical sensor means in fixed position at said inspection station, said position being such that a workpiece can be moved into and out of said inspection station without repositioning said electro-optical sensor means.

8. A method of simultaneously determining two dimensions of a workpiece comprising:

providing the workpiece in an inspection station;

electro-optically generating a first set of signals indicative of two dimensions of said workpiece in said inspection station and a second set of signals indicative of a two dimensional position of said workpiece in said inspection station; and

analyzing said first and second sets of signals to determine the two dimensions of said workpiece.

9. A method according to claim 8 further comprising physically constraining the workpiece in said inspection station.

10. A method according to claim 8 wherein said electro-optical signal generating step comprises:

illuminating the workpiece in said inspection station;

forming images of a plurality of illuminated portions of the illuminated workpiece with a single lens; and

providing light detector means comprising a plurality of discrete photodetectors capable of generating said first and second sets of signals in response to light incident thereon, each photodetector being positioned to receive from the single lens an image of a respective illuminated portion of the workpiece.

11. A method according to claim 8 wherein said electro-optical signal generating step comprises:

illuminating the workpiece in said inspection station;

forming images of a plurality of illuminated portions of the illuminated workpiece with a single lens;

providing light detector means comprising a first set of discrete photodetectors capable of generating said first set of signals in response to light incident thereon and a second set of discrete photodetectors capable of generating said second set of signals in response to light incident thereon, each photodetector being positioned to receive from the single lens an image of a respective illuminated portion of the workpiece.

12. A method according to claim 8 wherein said electro-optical signal generating step comprises illuminating the workpiece in said inspection station, forming images of a plurality of illuminated portions of the illuminated workpiece with a single lens, and providing photodetector means for generating said first and second sets of signals, said photodetector means comprising a plurality of photodetectors positioned to detect from said single lens the images of the illuminated portions of the illuminated workpiece.

13. A method according to claim 12 wherein a plurality of said photodetectors are positioned adjacent to an illuminated side of said workpiece.

14. A method according to claim 8 wherein the generating step includes mounting of an electro-optical sensor means in fixed position at said inspection station, and moving the workpiece into and out of said inspection station without repositioning said electro-optical sensor means.