# US 4,398,825 A · Optical scanner for ball inspection

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- Number: US 4,398,825 A
- Document ID: US4398825A
- Status: Granted
- Kind: A
- Application number: 06/234,776
- Filed: 1981-02-17
- Granted: 1983-08-16
- Earliest claimed: 1981-02-17
- Assignees: General Motors Corporation
- Inventors: Robert W. Lewis
- Web page: https://patentgrep.com/patent/US4398825A

## CPC

- G01N 21/951: {Balls}
- G01N 21/55: Specular reflectivity
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

To inspect a ball while it is spinning, a semicircular array of balanced light sources illuminate the ball, each source being directional to illuminate a restricted zone. An array of light detectors adjacent the sources are arranged for each to detect specularly reflected light from the ball originating from a limited number of light sources and a detector channel for each detector analyzes changes in received light to detect ball surface defects. No lenses are required and the sources and detectors are formed to allow compact packaging near the ball surface.

## Claims

### Claim 1

An optical scanner for optically inspecting the surface of balls comprising;
means for spinning a ball to be inspected, a semicircular array of substantially equal intensity light sources for illuminating the ball surface, each light source being directional to illuminate a restricted zone of the ball,
a semicircular array of light detectors adjacent the array of sources, each detector being positioned to sense the light specularly reflected from several discrete surface areas proximate the detector and originating from several light sources adjacent the detector, whereby substantially no light from remote zones of the ball reaches the said detector, and
a plurality of electronic detector channels, one for each light detector, for analyzing changes in received light to determine the presence of a ball surface defect.

### Claim 2

An optical scanner for optically inspecting the surface of balls comprising;
means for spinning a ball to be inspected,
a semicircular array of substantially equal intensity light sources for illuminating the ball surface comprising a plurality of optical fibers each having an input end and an output end, the input ends being close together and the output ends being separated for emitting light at spaced points, a lamp, a noncoherent fiber optic light guide having one end illuminated by the lamp and the other end arranged to evenly illuminate the input ends of the optical fibers, each light source being directional to illuminate a restricted zone of the ball,
a semicircular array of light detectors adjacent the array of sources, each detector being positioned to sense the light specularly reflected from several discrete surface areas proximate the detector and originating from several light sources adjacent the detector, whereby substantially no light from remote zones of the ball reaches the said detector, and
a plurality of electronic detector channels, one for each light detector, for analyzing changes in received light to determine the presence of a ball surface defect.

### Claim 3

An optical scanner for optically inspecting the surface of balls comprising;
means for spinning a ball to be inspected,
a semicircular array of substantially equal intensity directional light sources for illuminating the ball surface, each light source comprising an illuminated optical fiber for emitting light from an end thereof and an aperture positioned between the said end and the ball to limit illumination to a restricted zone of the ball,
a semicircular array of light detectors adjacent the array of sources, each detector being positioned to sense the light specularly reflected from several discrete surface areas proximate the detector and originating from several light sources adjacent the detector, whereby substantially no light from remote zones of the ball reaches the said detector, and
a plurality of electronic detector channels, one for each light detector, for analyzing changes in received light to determine the presence of a ball surface defect.

### Claim 4

An optical scanner for optically inspecting the surface of balls comprising;
means for spinning a ball to be inspected,
a semicircular array of substantially equal intensity light sources for illuminating a strip across the ball surface, each light source being directional to illuminate a restricted zone of the ball,
a semicircular array of light detectors adjacent the array of sources, each detector being positioned to sense the light specularly reflected from several discrete surface areas proximate the detector and originating from several light sources adjacent the detector, whereby substantially no light from remote zones of the ball reaches the said detector, each detector having an entrance aperture to define the size and shape of the said several discrete surface areas, the discrete surface areas in aggregate forming a substantially continuous band within the illuminated strip across the ball surface, and
a plurality of electronic detector channels, one for each light detector, for analyzing changes in received light to determine the presence of a ball surface defect.