The CIE-Lab-System is a colour space, which was specified by the International Commission on Illumination CIE (Commission Internationale d'Eclairage) in the year 1976. It was further derived from the CIE colour system and is based on the CIE “master” space which was introduced in the year 1931. CIELab system is today the most common colour system. On the basis of this equipment independent 3D-colour model, colour differences can be identified numerically. The model is impartial and complies nearly the human perceptiveness, by adapting the geometrical distance between two colours in the colour space with the human perception.
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Especially graphic works with scanner, printer and monitor require an accuracy for colours in an international significant colour profile space, which assure a cor-rect appropriateness of colours. The consistent colour space furthermore provides a larger variety of hues, more than i.e. RGB and CMYK. The measured distance is not corresponding to the sensed colour difference of test persons, therefore the CIE model was revised several times and out of this CIELab was deflected. Independent of the used equipment, the colour code of the CMYK- and RGB-mode can be exchanged in CIELab colour values and can also be used in graphical software. This model is suitable especially for surface colours, while CIE-Luv is in use for the evaluation of light sources at monitors and scanners. How is CIELab configured? The measured spectral curves will be reduces on three coordinates. The axes of the coordinates are positioned rectangular on each other: L* ,the light intensity, from 0 = absolute black to 100 = absolute white. a* describes the red - green axis. Negative values are green, the positives are red. b* describes the yellow - blue axis. Negative values are blue, the positives are yellow. Therewith the colour can be accurately described in the colour space. The calculation is effected under consideration of a standard light and an ordinary observer, that is, the colour values are calculated under defined physical conditions. On the layer a* / b* , it achieves the chromatic circle. At the edges are the polychromatic colours and in the centre achromatic grey is located. |
| Functionality Continuous, controlled LED illumination and identification of the product colour in the colour space after CIELab. The evaluation results in the visible light sector from 400 - 700 nm. The distance between sensor system and product has to be kept obligatory absolute non-varying. The colour evaluation, that ist the output of the measurement results, occures in 4 channels: L*, a*, b* and dE*. |
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Configuration
| Housing: Size HxWxD Enclosure Color |
aluminum pressure housing 230 x 280 x 110 mm IP65 / NEMA 4 RAL 5024 |
Connections |
100-240V AC 0/4 - 20 mA RS 232 or RS 485 fibre optic cable LED-illumination with 9 LEDs |
| User interface Operating Monitoring |
6 soft keys in integrated keypad 2 x 24 characters in illuminated display |
| Ambient conditions Environment temperature Product temperature |
-20°C - +85°C >0°C - +130°C |
Measurement Design
The sensor system is located max. 150mm over the to be detected product surface. The product surface is aproximatively smooth and planar. The products (matals, textiles, food, plastics) are moving on a conveyor belt under the sensor system. Fine powder products are planed by a scraper. For the attainment of top-quality measurement results the environment has to be dust-free. Wit the option “compressed-air“ the measurement can be kept free of dust.
Applications
The range of feasible applications is very large. The material of the product is not relevant, but the surface has to be aproximatively smooth and planar.
Imaginable applications:
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HK7-Versions
HK7-1: basic configuration
HK7-2: basic configuration + automatical white balance
HK7-3: basic configuration + measurement of degree of white index + triple sensorsystem
HK7-4: basic configuration + measurement of degree of white index + triple sensorsystem + automatical white balance
Advantages
In difference to spectrophotometers from the competition, the HK7 is not operating with Xenon-Flashlight. The controlled LED illumination is responsible for an improved stability of the measurement.
Measure geometry |
45/90 |
Standard lights |
D65, A, C, |
Standard observer |
2° (1931), 10° (1964) |
Colour space |
CIE L*a*b*, dE* |
Spectral range |
400nm – 700nm |
Spectral resolution |
1,3nm |
Reproduzierbarkeit |
dE=0,1 |
Gauge head dimensions |
80 x 80 x 80mm |
System size |
230 x 280 x 110mm |
Indication |
Relative values, absolute values or reflectance spectrum in PC |
Calibration |
With implemented white standard |
PC-interfaces |
serial RS232 / RS485 |
Power supply |
85 – 270 VAC |
Protection class |
IP65 |
Market Launch
The check out of the spectrophotometer takes place in several pilot schemes.
Inclusion in catalogue/price list and start of acquisition: May 2010.
Pilot Schemes
Pilot phase HK7-spectrophotometer: Application Syntetic Sausage casing
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