Optics: measuring and testing – Inspection of flaws or impurities – Transparent or translucent material
Reexamination Certificate
1998-10-02
2001-04-03
Font, Frank G. (Department: 2877)
Optics: measuring and testing
Inspection of flaws or impurities
Transparent or translucent material
C356S240100, C356S237600
Reexamination Certificate
active
06211952
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and associated apparatus for inspecting glass containers for checks and, more specifically, it relates to inspection of glass containers for horizontal checks, vertical checks and diagonal checks.
2. Description of the Prior Art
During the molding of glass containers, such as bottles, for example, checks can be formed in the process. Checks are generally considered to be cracks or other structural weaknesses which may, in some instances, be caused by inadvertent rapid cooling. Other checks may result from folds in the glass that are not hot enough to flow together inside the mold. Checks may also occur during the annealing process which generally takes place immediately after molding. Generally, when checks occur, they tend to occur repeatedly in the same location and orientation on the containers. Also, mold conditions may change even in a minor way and result in new checks appearing.
Checks can cause breakage of glass bottles during storage, filling, shipment, further storage and use. Also, cracks, chips and sharp edges which can result from checks can cause injury to persons handling the bottles or pouring the contents or drinking therefrom.
It has been known to provide check detectors that rely on optical means to identify checks. As checks are abrupt changes in direction in the surface of the glass, they can be detected as bright glints of light from the facets of their irregular surfaces. One of the problems with existing optical systems is that threads, mold seams, takeout rings and sealing surfaces also have corners which can easily be confused for checks.
One known form of check detector is marketed under the trade designation “Powers Check Detector” by Emhart Powers of Elmira, N.Y. It employs the concept of using very localized lighting and detector field of view in order to avoid problems created by threads, mold seams, takeout rings and sealing surfaces. A problem presented by this approach is that the check must first be identified by human visual inspection and then a narrow beam of light and narrow field of view detector positioned so as to reflect light from the check into the detector when the bottle is rotated in the field of view. This type of detection device generally consists of a lens with a single detector such as a silicon photodiode at the focus. Precise positioning of the light source and detector are required so as to avoid receipt of glints from other features of the bottle during rotation. This tends to be a time-consuming process and must be repeated for each check found in the containers. As a result, the container molding system and related equipment is out of service while the operator sets up the detectors. As new checks develop, they will not be detected by the machine until the operator notices them and sets up another light source-detector pair. This not only requires human intervention, but substantially reduces the reliability of the molding operation.
It has also been known to employ machines which purport to inspect the entire container and detect checks with “smart” optics. Such machines have been made available commercially under the trade designation AFCD by Precision Co., Ltd. of Japan. These systems employ computer programs to examine the entire surface of the finish and attempt to distinguish threads and other intentionally provided configurations from undesired checks. A plurality of lights and detectors provide a number of combinations of light-detector pairs. The computer is said to recognize the combinations of glints that are characteristics of threads and other intentionally placed shapes and differentiate them from check glints. Relative rotation is established between a rotating container which may be a bottle under the inspection head or rotation of the inspection head with respect to a stationary bottle.
In spite of the foregoing known systems, there remains a very real and substantial need for a method and associated apparatus which will rapidly and effectively monitor glass container finishes for checks having various orientations.
SUMMARY OF THE INVENTION
The present invention has met the above-described need by providing a method of inspecting glass containers for checks in a rapid, reliable manner and associated apparatus.
In one embodiment, horizontal and certain diagonal checks are inspected for and in another embodiment, vertical and other diagonal checks are inspected for.
The method in one embodiment includes introducing the container into an inspection region, illuminating the exterior of the container around the circumference of the container finish, detecting light reflected in the interior of the container finish and comparing the detected light with a reference standard. On the basis of this comparison, a determination is made as to whether checks exist.
The apparatus includes light source means for delivering a beam of light to reflector means which causes the light beam to impinge on the exterior of the container finish and detector means which receives light reflected from the interior of the container finish and converts it into a corresponding electrical signal which is introduced into a microprocessor for comparison with standard data for the container to determine if the container should be rejected due to the presence of undesired checks. Reject means may be activated by the microprocessor to remove a rejected container.
The light source preferably is a pulsed light source which depending on the embodiment, causes the light to impinge on the container finish from different directions. A preferred approach with respect to horizontal and associated diagonal checks is to have the light impinge generally radially. In the embodiment which monitors vertical and associated diagonal checks, it is preferred to have the light impinge on the container finish generally tangentially. In both embodiments, there will generally be only a circumferential portion of the container finish inspected by the inspection means with a plurality of inspection means being employed to inspect the entire circumference.
In another embodiment, the container may be rotated and only one horizontal detector and one vertical detector employed to inspect the container finish.
In general, the pulsed light will impinge on reflector means and the reflected light will be further reflected so as to deliver it to the detector means which converts the received light into a related electrical signal which is delivered to a microprocessor for purposes of effecting the desired comparison.
It is an object of the present invention to provide a method and apparatus for inspecting glass containers for checks without requiring prior knowledge of the existence of or location of checks.
It is a further object of the invention to provide such a method and apparatus wherein features such as container threads, lugs, mold lines, sealing surfaces and takeout rings, as well as other intentionally provided irregularities in the container finish are excluded from the comparison mechanically, optically, or electrically.
It is a further object of the present invention to provide a plurality of inspection units which cooperate to inspect the full 360 degree circumference of the container, which may be a bottle.
It is a further object of the present invention to provide such a system which will operate at rapid speeds and will automatically determine the presence of one or more checks without requiring human intervention.
It is a further object of the present invention to provide such a system which will automatically reject and physically remove containers having checks which exceed a predetermined threshold.
It is a further object of the present invention to provide such a system wherein horizontal and vertical detectors may be employed to inspect portions of a stationary container which is then rotated so that another portion of the container finish can be inspected.
These and other objects of the invention will be more fully understood from the following descript
Dimmick Mary L.
Dimmick, Sr. Henry M.
Weiland Joseph G.
Agarwal Brij K.
AGR International, Inc.
Dimmick Mary L.
Eckert Seamans Cherin & Mellott , LLC
Font Frank G.
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