DE10037811A1 - Coating inspection device e.g. for motor vehicle, refrigerator, illuminates object and object is observed through spectacles with filter - Google Patents

Abstract

An illumination source (2) irradiates light on object such as car (1) and the object and a reference sample (5) are observed directly and through spectacles provided with a spectral filter (4).

Description

State of the art

Color matching systems with variable spectral distribution - or with several different types of light for the detection of metamerism effects in the coloring industry (automotive painting, textile coloring, color printing, etc.) set to a color refinish of different spectral reflection check their color consistency when changing the light type. Usually this control with daylight (standard light type D65) and incandescent light (standard light type A) carried out.

Criticism of the state of the art

The technology used is through the use of special fluorescent lamps or filtered xenon lamps for realizing natural daylight and incandescent pen to realize the standard illuminant A and is therefore only a color sample smaller cabin available. In some plants it is also added the matching under "energy saving lamps" enables. In this color matching cabins, however, are only to be examined on smaller specimens, typically up to 20 cm × 20 cm respect, think highly of. Compact objects, such as B. refrigerators, automobiles or others can because of their too large dimensions in these color matching booths, no one is examined the. In practice, this means that you have two (to three) complete large systems would need e.g. B. one each for color matching in daylight and one in glow lamp light (or an additional one for gas discharge lamp light) or one elaborate luminaire construction of the system with several different formwork lamp groups should be provided. This in turn makes it very difficult always create the same lighting conditions with regard to the light directions.

Invention task

The task of the invention is to find an optimal device with which the same me tamer effects become recognizable, as under a change in the type of light, e.g. B. by day light on incandescent light, but for any size field of view.  

Solution of the invention task

The representation of different types of light is used to solve the task of the invention needed.

According to the invention, however, the conversion does not take place at the light source or between between the light source and the illuminated object, but between the illuminated test object and eye of the examiner.

Physical explanation of the invention

The idea of the invention can be realized by a filter corresponding spectral Transmission properties that act as a filter or filter wall between the examiner's eye and the object to be checked is installed.

A suitably arranged or provided with a filter is particularly advantageous ne glasses or corresponding eye adhesive cups.

In picture 1 a visual object is e.g. B. a car body 1 (any other test objects te are possible) from the lighting system 2 illuminated. The light type of lighting 2 in the example is simulated daylight. But other lighting types z. B. natural daylight, incandescent, fluorescent, etc. can be used.

The test object 1 , the body, is compared in the selected example with a reference panel 5 . Of course, the test object and references can also have any other geometries, provided that the reference represents a section of the surface from the test object with respect to the evaluated area.

Test object 1 and reference 5 are viewed by a tester 3 who looks through the filter 4 . This filter can be installed as a disk either fixed or movable, held in the hand or designed as glasses or glasses attachment, etc. The examiner now evaluates the color differences present under the different conditions - with and without filter 4 .

The decisive factor is the spectral transmittance with which the specified spectral distribution of the lighting is converted into another desired type of light. For example, the spectral transmittance of the filter shown in Figure 2 shows the conversion of daylight D to incandescent light A.

In practice, the curve of the filter's spectral transmittance ( Figure 2) only has to roughly follow these specifications, because no absolute values are required for the visual assessment of the meta, only statements about a change in color differences.

The effect of metamerism is particularly important in order to recognize the change in a color difference between an original part or test object, in the example the body 1 , and a re-coloring, in the example the color table 5 , with different light colors. Therefore, a reference sample 5 can be attached or held on the surface of the body 1 to be tested, which has the same spectral reflection properties as the original color. The metamerism can then be judged from the change in the color difference of the adjacent body surface.

Filter selection

The filter to be used, e.g. B. the color assessment of a surface illuminated with daylight D for incandescent light A should allow a spectral profile of the permeability

exhibit. It can be used to check whether a Sample pair that is the same color in daylight D, unequal under incandescent light A. looks big. In practice, it then comes down to using this D / A Conversation filter can check whether there is a color difference under daylight D. limit ΔE when viewed through the conversion filter D / A becomes larger or remains the same.  

Color of reference and sample to be tested under daylight

Reference R

Sample P

Color difference under daylight

Color of reference and sample to be tested under incandescent light (converted incandescent light)

Reference R

Sample P

Color difference under incandescent light

If metamerism is present, the color difference under incandescent light ΔE _A becomes greater than the color difference ΔE _D already present under daylight _D :

Denote in these formulas:

• - X, Y, Z the standard color values of the reference R or sample P to be assessed for Ta plain D or incandescent light A
• - S (λ) _{D is} the spectral radiation distribution of illuminant D
• - τ (λ) _{D / A is} the spectral transmittance of the conversion filter, which makes the samples illuminated with daylight D appear in the color as if they were with incandescent light A lighting.
• - R (λ) the spectral reflection of reference R and that in terms of metamerism Sample P. to be assessed
• - x (λ), y (λ), z (λ) the standard spectral value functions according to DIN 5033

Claims (4)

1.Device for testing a test object that is illuminated with a predetermined type of light or illuminated for metamerism effects, characterized in that a conversion filter is arranged between the test object and the examiner's eye, which spectrally changes the spectral distribution of the light entering the examiner's eye from the test object as if the test object was illuminated with a different type of light, under which metamerism effects can be recognized. 2. Device according to claim 1, characterized in that the conversion filter is designed as glasses or glasses attachment. 3. Device according to claim 1, characterized in that the conversion filter is designed as an eye adhesive shell. 4. The device according to claim 1 to 3, characterized in that the spectral distribution of the illuminating light given by the formula S (λ) _{1 given} in another light by the formula S (λ) ₂ = τ (λ) S (λ) _{1 is} converted, in which the formula component τ (λ) represents the spectral transmission of the conversion filter.