Optics: measuring and testing – Of light reflection
Reexamination Certificate
2000-10-19
2003-10-07
Epps, Georgia (Department: 2873)
Optics: measuring and testing
Of light reflection
C250S227290
Reexamination Certificate
active
06631000
ABSTRACT:
DESCRIPTION
The present invention relates to a device and a procedure for the quality control of in particular finished surfaces. In numerous products, the quality or the visual properties of its surface become an important characteristic for the overall appearance of the product. Thus, in order to achieve a high reproducibility during production, retouching or repair work on objects, quality control measurements are carried out on the products to determine one or several parameters (such as for example: color, gloss, haze, orange peel, etc.).
Particularly with finished surface's, but not limited solely thereto, their visual properties may change depending upon viewing angle, respectively angle of illumination. Such surfaces are called goniochromatic.
Examples of such surfaces are those with effect, metallic or pearl lustre finishes, coated surfaces as well as interference color surfaces, or even synthetic surfaces having inlaid transparent particles and other such similar surfaces.
Finished surfaces having inlaid metal particles may exhibit, for example, FLOP effects so that a change in color dependant upon the viewing angle may be observed. Such effects may be induced, for example, by aluminum particles inlaid in the surface and which then act as mirrors.
In order to offer consumers products featuring new colors, new finishes are developed which are able to exhibit specific qualities.
In many effect finishes, there is a particular viewing angle at which a change in parameters occurs. Should a surface be observed at a slightly lesser angle, a first impression of color may, for instance, be noted, while a second impression of color, which may conceivably differ considerably from the first impression of color, may be noted upon scanning or measuring at a slightly greater angle.
Measuring devices which illuminate a measurement surface at an angle and which measure the reflected light at two fixed angle ranges in order to determine the color of a surface to be examined under these two scanning angles are known from the prior art. Furthermore, goniometric measuring devices are also known in the prior art with which, for example, a surface is illuminated at a fixed angle and a photosensor is trammed across the entire angle range in order to obtain the surface color as a function of the scanning angle.
However, goniometric devices have the disadvantage that in order to determine color function, the sensor must be trammed over the entire angle range during each measurement and a mechanical decalibrating of the device cannot always be excluded.
It is the task of the present invention to provide a device and a procedure of the type as indicated above to enable a quality control of surfaces and finished surfaces in particular.
Another aspect of the task of the present invention is to provide a device which can determine at least one visual property of a surface, including of those surfaces which may also have been given new finishes or other such similar treatments.
SUMMARY OF THE INVENTION
This task is solved in accordance with the present inventive device and method as described herein.
Preferred embodiments of the invention constitute the subject matter of the subclaims.
A device according to the present invention for the quality control of especially finished surfaces comprises an illuminating means having at least one light source. The light radiated from said illuminating means is directed to the measurement surface at a predetermined angle. A plurality of at least three, preferably at least five measuring means are furthermore provided, which each receive at least a portion of the light reflected by the measurement surface. Each measuring means has at least one photosensor which emits at least one electrical measurement signal, whereby said electrical measurement signal is characteristic of the light received by the measuring means.
The inventive device furthermore has at least one control and evaluation means provided with at least one processor and at least one memory means in order to control the measurement sequence, evaluate the measurement results, and derive a parameter from the measurement signals which characterizes the surface. An output means serves to display, respectively forward, the measurement results.
The device according to the present invention has numerous advantages:
Arranging each of the plurality of measuring means in the inventive device at a different angle to the measurement surface enables the evaluation means to derive a parameter which is characteristic of the surface from the measurement signals of the individual measuring means.
Preferably at least one characteristic parameter is determined for the measured surface; this parameter may be its color, gloss, haze, orange peel or distinction of image. It is moreover possible that two or three different parameters can be determined and/or that, for example, at least one parameter each may be determined from respectively two, three or all measuring means.
Especially preferred is determining the color parameter of the measurement surface whereby it is possible that a set of color characteristics are determined in that, for example, each measuring means determines one color characteristic. In a preferred embodiment of the invention, a plurality of retaining means are provided in the device upon each of which a measuring means is disposed. Especially preferred is that the number of retaining means is greater or identical to the number of measuring means so that, for example, ten retaining means are provided whereby measuring means are disposed upon five of these ten retaining means.
A greater number of retaining means relative to the number of measuring means is highly advantageous because this enables changing the position of one measuring means from a first retaining means to a second retaining means upon which no other measuring means has been disposed.
With this type of device, the individual positions of the measuring means can be changed essentially at any time which enables the device to be adapted to changed conditions.
The retaining means serve to hold or support the measuring means, respectively parts thereof, and are preferably realized as conventional retaining means as known in the prior art.
In a preferred embodiment of the present invention, the angle spacing between at least three adjacent retaining means is in each case identical and especially preferred is that essentially all the angle spacings of adjacent retaining means are essentially identical. For example, more than 30 retaining means are disposed across a 180° range of angles in the present embodiment, the spacings between said means in each case amounting to 5°, whereby a greater angle spacing can also be given between a first area of the retaining means and a second area of the retaining means. It is likewise possible that the aggregate of retaining means are distributed across, for example, three angle ranges in that the angle spacings from one to the next are identical, whereby greater angle spacings are found between the individual areas.
This embodiment is particularly advantageous. Positioning the retaining means for instance at a 3° or 5° spacing from one another enables setting the angle at which a measuring means receives a portion of the light reflected from the surface at small increments. Should the retaining means be arranged during the actual manufacturing of the device, a measuring means can be brought from one retaining means onto another retaining means with relatively low expenditure.
In a preferred embodiment of the present invention, at least one measuring means comprises an optical photoconductor means and a spectral means, whereby the optical photoconductor means receives a portion of the light reflected from the measurement surface and conveys same to the spectral means. In this embodiment, the predetermined angle at which the measuring means is directed to the measurement surface corresponds to the angle at which in this case the optical photoconductor means is directed to the measurement surface, while
BYK Gardner GmbH
Epps Georgia
Hanig Richard
LandOfFree
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