Optics: measuring and testing – By configuration comparison – With comparison to master – desired shape – or reference voltage
Reexamination Certificate
2000-07-10
2004-09-07
Font, Frank G. (Department: 2877)
Optics: measuring and testing
By configuration comparison
With comparison to master, desired shape, or reference voltage
C356S369000, C356S364000, C382S141000
Reexamination Certificate
active
06788411
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally concerns machine-vision, particularly systems and methods for lighting/illuminating objects in machine-vision systems.
COPYRIGHT NOTICE/PERMISSION
A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever. The following notice applies to the software and data as described below and in the drawings hereto: Copyright © 1998-2000, PPT Vision, Inc., All Rights Reserved.
RELATED APPLICATIONS
This invention is related to:
U.S. Pat. No. 6,603,103, entitled “CIRCUIT FOR MACHINE-VISION SYSTEM”,
U.S. patent application Ser. No. 09/350,050, entitled “MACHINE-VISION SYSTEM AND METHOD FOR RANDOMLY LOCATED PARTS” (now abandoned), filed Jul. 8, 1999,
U.S. patent application Ser. No. 09/350,255, entitled “PARTS MANIPULATION AND INSPECTION SYSTEM AND METHOD” (now abandoned), filed Jul. 8, 1999,
U.S. patent application Ser. No. 09/349,684, entitled “MACHINE-VISION SYSTEMS AND METHODS WITH UP AND DOWN LIGHTS” (now abandoned), filed Jul. 8, 1999,
U.S. patent application Ser. No. 09/349,948, entitled “METHOD AND APPARATUS TO CALCULATE BGA BALL TOPS” (now abandoned), filed Jul. 8, 1999,
U.S. Pat. No. 6,522,777, entitled “COMBINED 3D AND 2D-SCANNING MACHINE-VISION SYSTEM AND METHOD”
U.S. patent application Ser. No. 09/350,037, entitled “MACHINE-VISION SYSTEM AND METHOD HAVING A SINE-WAVE PROJECTION PATTERN” (now abandoned), filed Jul. 8, 1999,
U.S. patent application Ser. No. 09/350,251, entitled “TRAY FLIPPER AND METHOD FOR PARTS INSPECTION” (filed Jul. 8, 1999,
U.S. Pat. No. 6,509,559, entitled “BINARY GRATING AND METHOD FOR GENERATING A MOIRE PATTERN FOR 3D IMAGING”
U.S. Pat. No. 6,486,963, entitled “PRECISION 3D SCANNER BASE AND METHOD FOR MEASURING MANUFACTURED PARTS”
U.S. Pat. No. 6,501,554, entitled “3D SCANNER AND METHOD FOR MEASURING HEIGHTS AND ANGLES OF MANUFACTURED PARTS”
which are all assigned to a common assignee, and which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
There is a widespread need for inspection data for electronic parts in a manufacturing environment. Machine-vision systems have become vital to many complex manufacturing processes, particularly for quality control. For example, during the manufacture of integrated circuits which contain millions of transistors and other electrical components, machine-vision systems visually inspect the circuits at various manufacturing stages for surface blemishes or other defects, rejecting or accepting circuits based on appearance.
Machine-vision systems typically includes an imaging device, such as an electronic camera and an illumination system, which illuminates an object for the camera. The typical illumination system, generally designed to illuminate all sides of an object simultaneously, comprises some form of a circular ring of lights, for example a ring-shaped flashtube, a ring of light-emitting diodes, or a ring of optical fibers. The circular ring of lights usually lies between the camera and object, with the camera looking down through the ring to the object and the lights oriented down and inward to the object.
Conventional illumination systems suffer from at least two major problems. First, they lack a convenient way for varying the angle of illumination, that is, the angle light strikes an object. Conventional illumination systems require technicians to manually adjust orientation of the complete ring of lights or to manually adjust orientation of its individual lights. However, manual adjustments are not only time consuming, but often lead to angular variations which compromise consistency of machine-vision systems. Second, conventional systems lack convenient way of switching from one illumination mode to another, for example, from a particular selected angle of illumination to a multi-directional object illumination, such as “cloudy-day illumination.” Some select-angle illumination modes are better for viewing scratches, while cloudy-day illumination is better for specular or irregular surfaces. This lack of a convenient way of switching illumination modes often leads to use of more than one machine-vision system, and thus forces manufacturers to buy separate systems, to use human inspectors, or to skip inspection for some types of defects. Accordingly, there is a need for better illumination systems for machine-vision systems.
SUMMARY OF THE INVENTION
In the context of a machine-vision system for inspecting a part, this invention includes method and apparatus to provide high-speed changing and/or automatic adjustment of illumination angle, dispersion, intensity, and/or color of illumination in a machine vision system.
One aspect of the present invention provides a machine-vision system having an optical axis. This system includes a light source emitting light having a polarization, a machine-vision imager that obtains an image of an object illuminated by the light, a processor coupled to receive an image from the imager, and operative to generate a quality parameter based on the image, and one or more of the various means as described above for selectively directing the light in a predetermined pattern based on its polarization and based on the quality parameter of the image.
Another aspect of the present invention provides a machine-vision system having an optical axis. This system includes a machine-vision imager located along the optical axis, a controllable light source, a first optical element that selectively directs light in a first predetermined pattern relative to the optical axis based on light characteristics, a second optical element, that directs light in a second predetermined pattern relative to the optical axis, and an electronic controller operatively coupled to the imager and the controllable light source to control the light characteristics and thereby selecting one or more of the first and second predetermined patterns.
Another aspect of the present invention provides an illumination method that includes emitting light, selectively polarizing the light, and selectively directing the light based on its polarization.
In some embodiments, the selectively directing provides two or more different angles of illumination (e.g., alpha and/or beta). In some such embodiments, the angle is a conical angle of a ring illumination.
Yet another aspect of the present invention provides a machine-vision method for inspecting an object. This method includes (a) setting one or more illumination parameters, (b) illuminating the object based on the one or more illumination parameters, (c) obtaining an image of the illuminated object, (d) generating a quality parameter based on an image quality of a predetermined region of interest in the image, and (e) iterating (b), (c), and (d) using a different illumination parameter. In some embodiments of this method, the iterating is based on the quality parameter. In some embodiments, the one or more illumination parameters includes a predetermined azimuth angle of illumination. In some embodiments, the one or more illumination parameters includes a predetermined compass angle of illumination. In some embodiments, the one or more illumination parameters includes a predetermined compass angle of illumination.
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pate
Font Frank G.
PPT Vision, Inc.
Punnoose Roy M.
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