Optics: measuring and testing – Sample – specimen – or standard holder or support
Reexamination Certificate
2000-02-25
2002-08-06
Font, Frank G. (Department: 2877)
Optics: measuring and testing
Sample, specimen, or standard holder or support
C356S445000, C356S446000, C250S566000, C235S472010, C235S462320
Reexamination Certificate
active
06429934
ABSTRACT:
BACKGROUND OF THE INVENTION—FIELD OF USE
This invention relates to the optimal and uniform illumination of surfaces, which may be specular or irregular, and to the uniform illumination of machine readable codes, symbologies and the like that may be applied directly to such surfaces or to symbology carrying media that is, in turn, applied to such surfaces. More particularly, this invention relates to optimal and uniform illumination of surfaces, codes, symbologies or the like to facilitate imaging and successful decoding of machine readable codes, symbology or the like.
BACKGROUND OF THE INVENTION—DESCRIPTION OF THE PRIOR ART
It is quite often necessary to determine the existence, location or characteristics of an article through automated means for automated purposes. Robotic handling of parts for processing such as machining or assembly purposes and automated sorting, transportation, manipulation and other handling of parts, components, packages and the like usually requires that some form of machine readable code or symbology be applied to the article. At times it is convenient to apply the symbology to a media such as a pressure sensitive label. Other times it is more desirable and possibly efficient to apply the symbology directly to the article. The symbology may be a conventional bar code, a stacked bar code or other 2-D symbology.
Machine reading of symbology, as by a stationary or hand-held reader or imager, requires proper illumination of the targeted symbology. This may present problems if the media carrying the symbology is applied to an irregular or curved surface. The problems are more pronounced if the symbology is applied directly to the article and the article surface is normally specular and/or the article's surface is irregular.
Imaging and decoding a 1-D or 2-D symbology requires that the ones and zeros of the symbology be discernable for the decoding algorithms, which, in turn, requires that proper contrast between the ones and zeroes be obtained during the imaging process. Particularly when imaging a 2-d symbology, it is not important whether the ones are dark or light with respect to the zeroes; it is only important that the contrast between the two states is sufficient for adequate separation. For example, when the symbology is printed as a black code on a white background or as a white code on a black background, the code will be easily discernable in almost any illumination if the code and the background are both surfaces having a matte reflectivity. The matte surfaces ensure that regardless of the direction from which they are illuminated, the light reflected from them will be smoothly distributed over a wide angular distribution and so will provide adequate illumination into the camera lens. This situation is usually achieved when the symbologies are printed on labels that are affixed to parts or components. However, labels are easily tampered with and often fragile compared to the parts or components to which they are attached. Therefore, it is often advantageous to mark the symbology directly on the parts or components. Unfortunately, parts and components often have specular (mirror like) surfaces which do not distribute the light uniformity over a wide angular distribution but rather redirect the light rays such that the angle of reflection is exactly equal to the angle of incidence. If the illumination comes from a small source (a source having a small angular extent as viewed from the specular surface being illuminated) it is highly likely that the light reflected from the surface will miss the camera lens and so the surface will appear to be “black”. Conversely, if the small light source is positioned such that the angle of reflection directs the light rays from the source directly into the camera lens the light rays may be overwhelmingly bright and so make the surface appear to be “white”. Thus, we have an intolerable situation because the surface may appear to be either “black” or “white” according to very small changes in the exact angular relationship between the specular surface being imaged, the light source, and the camera lens. This situation is especially deleterious when the symbology being imaged is on a surface that is simultaneously specular and curved so that some portions appear to be bright and other portions appear to be dark.
SUMMARY OF THE INVENTION
It is therefore an object of this invention to provide new and novel surface illumination apparatus.
It is another object of this invention to provide new and novel methods of surface illumination.
It is yet another object of this invention to provide new and novel optimal illumination of surfaces which carry machine readable coded information.
It is another object of this invention to provide new and novel optimal illumination of specular and otherwise irregular surfaces upon which there is disposed machine readable coded symbology.
It is yet still another object of this invention to provide new and novel apparatus and methods for hand-held optimal illumination of machine readable coded symbology.
It is yet a further object of this invention to provide new and novel apparatus and methods for hand-held optimal illumination of machine readable, coded symbology applied directly to parts and components.
It is yet still a further object of this invention to provide new and novel apparatus and methods for illumination of machine readable codes of black and white cells, and/or cells of other differing and contrasting colors, which illuminates such cells so as to optimize the contrast between such differing and contrasting colors for optimal separation of the respective differing and contrasting colors when imaging same to facilitate successful decoding thereof.
It is yet still a further object of this invention to provide new and novel apparatus and methods for readily effecting modification of the illumination provided by a symbology imaging device through an attachment to the imaging device which, when attached to the imaging device, re-directs the imaging device's illumination so as to further illuminate and enhance symbology of differing and contrasting colors to be imaged to facilitate imaging and decoding of the symbology and which, when detached from the imaging device or rotated to an alternate position, permits the imaging device's original illumination modes to be employed.
It is yet still a further object of this invention to provide new and novel apparatus and methods for illuminating symbology carried by parts, components and the like to facilitate optimal decoding of the symbology.
It is yet a further object of this invention to provide new and novel hand-held apparatus and methods for applying optimal uniform illumination to symbology directly applied to parts, components and the like to effect decoding of the symbology.
It is yet still a further object of this invention to provide new and novel apparatus and methods for modification of the illumination provided by a symbology imaging device by including, as a component of the imaging device, an illumination directing member selectively positionable between first and second dispositions; wherein the first disposition permits illumination to be projected in a first manner and wherein the second disposition re-directs the illumination to project same in a second manner.
It is yet still a further object of the invention to provide new and novel apparatus and methods for illumination provided by a hand-held symbology imaging device to selectively provide “bright field” illumination or “dark field” illumination from the same illumination source.
Other objects, features and advantages of the inventions in their methods and details of construction and arrangement of parts will be seen from the above, from the following description of the preferred embodiments when considered with the drawings and from the appended claims.
REFERENCES:
patent: 5140141 (1992-08-01), Inagaki et al.
patent: 5469294 (1995-11-01), Wilt et al.
patent: 5641958 (1997-06-01), Rudeen
patent: 5737122 (1998-04-01), Wilt et al.
patent: 606685
Dunn Sheila B.
Merva John J.
Stern Howard
Pollack Morris I.
Punnoose Roy M.
Robotic Vision Systems Inc.
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