Optics: measuring and testing – Inspection of flaws or impurities
Utility Patent
1998-11-20
2001-01-02
Rosenberger, Richard A. (Department: 2877)
Optics: measuring and testing
Inspection of flaws or impurities
C131S905000
Utility Patent
active
06169600
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a system and method of optically inspecting cylindrical surfaces and more particularly, to a system and method of inspecting cigarettes at high speeds during their manufacture.
BACKGROUND OF THE INVENTION
It is highly desirable to be able to inspect the entire cylindrical surface of cylindrical objects, such as cigarettes during the manufacturing process. Any one of a wide variety of defects may occur in such objects and it is desirable to have an automated system for detecting those defects so that defective objects can be rejected or so that any mal-functioning of the machinery producing those objects can be promptly identified and corrected. In the case of cigarettes, for example, the cylindrical surface may be defective due to a piece of tobacco stem piercing the paper, an imperfection in the way the filter has been joined to the remainder of the cigarette rod, an imperfectly formed side seal which leaves some of the tobacco visible, a discoloration of the cigarette wrapper, due to staining and imperfect ink application, etc.
Although inspection of this kind may take place at any stage in the production of cigarettes, it is most advantageous to perform such inspections after processing of the individual cigarettes is substantially complete. At this point in their fabrication, the individual cigarettes are most easily moved through the cigarette making machinery transverse to their length (side by side).
However, with the cigarettes moving transverse to their length it is much more difficult to image the entire surface of the cigarette. For example, the cylindrical nature of the surface makes uniform illumination of the surface and elimination of shadows difficult. Thus, it may be necessary to inspect the surface piecemeal. However, it is highly desirable to keep the number of inspections to a minimum in order to minimize the need for undue multiplication of complex and expensive inspection system components given the extreme high speed at which cigarettes are moved during the fabrication process.
Additionally, any successful inspection system for products such as cigarettes must be extremely fast in order to keep pace with the high speeds at which such products are typically made. For example, it is now common for a single cigarette making machine to make cigarettes at rates approaching twenty thousand parts per minute. Furthermore, a cigarette inspection system must also be able to inspect cigarettes for relatively small or subtle defects (for example, a hole as small as about 0.5 millimeters in diameter or a minor discoloration of the cigarette wrapper).
Accordingly, it is a principle object of the disclosed invention to provide a cigarette inspection system and method which includes at least one illumination system, which accentuates defects in cigarettes being inspected. It is also an object of the disclosed invention to provide a cigarette inspection system which is capable of inspecting cylindrical surfaces, such as the entire circumference of a cigarette, at very high speeds with a high degree of accuracy. Furthermore, it is an object of the present invention to provide a cigarette inspection system which substantially eliminates the possibility of false defect identification due to airborne contaminants, such as tobacco dust and the like
SUMMARY OF THE INVENTION
These and other objects of the invention are satisfied by providing an inspection system for optically inspecting substantially the entire circumference of a cylindrical surface, which includes a first moveable support for supporting and transporting a cylindrical object, such as a cigarette, so that a first side of a cylindrical surface of the cylindrical object is presented to a first visual inspection apparatus. The inspection system further includes a first illumination source for illuminating the first side of the cylindrical surface when the first side of the cylindrical surface is presented to the first visual inspection apparatus. The first illumination source is configured to direct light onto the cylindrical surface along a longitudinal axis of the cylindrical surface at a low, acute angle with respect to the longitudinal axis.
The inspection system also includes a second moveable support configured to receive the cylindrical object being inspected from the first moveable support and for supporting and transporting the cylindrical object such that a second side of the cylindrical object is presented to a second visual inspection apparatus. The second side of the cylindrical object includes at least all portions of the cylindrical surface of the object which are not inspected in the first side.
Also included in the system is a second illumination source for illuminating the second side of the cylindrical surface when the second side of the surface is presented to the second visual inspection apparatus. The second illumination source, like the first illumination source, is configured to direct light onto the cylindrical surface along the cylindrical axis of the cylindrical object at a low, acute angle with respect to the longitudinal axis.
The first and second visual inspection apparatuses included in the cigarette inspection system each include first and second image capture devices, respectfully. The first and second image capture devices capture first and second images of the cylindrical object. The first image corresponds generally to the first side of the cylindrical object. The second image corresponds generally to the second side of the cylindrical surface.
The disclosed invention further includes a method of inspecting substantially an entire circumference of a cylindrical surface of a cylindrical object. The method begins with supporting the cylindrical object being inspected along its longitudinal axis and transporting the object so that a first side of the cylindrical surface is presented to a first visual inspection apparatus. The first side of the cylindrical surface is then illuminated with an illumination source configured to direct light upon the first side of the cylindrical surface in a longitudinal direction along an illumination axis, which is oriented at a low, acute angle with respect to said longitudinal axis. Once the cylindrical object is illuminated, a first image of the cylindrical object, which corresponds to the first side of the cylindrical surface is captured by a first image capture device. The first image is then analyzed using an image processor to identify defects in the first side of the cylindrical surface.
The cylindrical object is then transported so that a second side of the cylindrical surface of the cylindrical object is presented to a second visual inspection system. The second side of the cylindrical surface includes at least all portions of the cylindrical surface which are not included or imaged in the first side.
The second side of the cylindrical surface is then illuminated with an illumination source which, like the first illumination source, is configured to direct light upon the second side of the cylindrical surface along the illumination axis. A second image of the cylindrical object is then captured with a second image capture device. The second image corresponds to the second side of the cylindrical surface.
Finally, the second image is analyzed using the image processor to identify defects in the second side of the cylindrical surface.
Further features and advantages of the invention will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments.
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Acuity Imaging, LLC
Bourque & Associates P.A.
Rosenberger Richard A.
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