What is a colorimeter?

What is a colorimeter?

The colorimeter is widely used in the color management field of plastics, printing, paint, ink, textile, printing and dyeing garments, etc.

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According to the Lab, Lch principle of CIE color space, the measurement shows the color difference △E and △Lab value of the sample and the sample to be tested. . 

Suitable for internal and external color evaluation and data management. The colorimeter was born to detect the difference in color and color to bring more convenience to industrial production to reduce the loss caused by chromatic aberration. The requirements for the color of people’s items in modern life are getting higher and higher, and the simple color difference may break the image of a brand in the hearts of consumers, which has a great impact on its reputation. The development and use of colorimeter is an inevitable trend.
The color difference is simply a color difference. The reason is that in the case where the multi-color light is a light source, the monochromatic light does not cause chromatic aberration. The wavelength of visible light is between 400 and 700 nm, and the colors reflected by light of different wavelengths are different. The purpose of using the colorimeter is to find out these chromatic aberrations in time and find out the cause of the chromatic aberration, to avoid more serious color problems, and to check the color quality of the products.
In fact, we know that the factors that affect the color of the product include brightness, hue and saturation. We can easily control the color change as long as the three factors are controlled. The role of the colorimeter is to quantify the difference in color perception. That is, it is represented by numbers in the form of differences in the three color attributes of brightness, hue, and chroma. The brightness (L*) indicates that the black and white of the color is the difference between the shades, and the hue (H*) indicates that the difference in hue is reddish or bluish, and the chroma (C*) indicates the difference in the vividness of the color.
The evaluation of chromatic aberration is very important in industry and commerce, mainly used in color matching in production and color quality control of products. Modern color difference assessment is based on the standard color difference formula recommended by the International Lighting Association (CIE) and is calculated using a colorimeter and computer measurement, using exact numbers. Commonly used as CIE 1976L*a*b* and CIE 1976L*u*v* color difference formula.
Another kind of chromatic aberration is produced by different materials, different textures and different shapes. Even if the same batch and the same formula are used, the dyed products may have different colors, mainly because the color is light on the object. Reflected products with different shapes and textures. When the light is shining on it, the reflected light path must be different. The color information that is fed back to the brain after the naked eye is captured will change.
Chromatic aberration, the interpretation of “Ci Hai” refers to the difference between the two colors, that is, the difference in hue, saturation and brightness. The most reasonable and scientific way to control color changes in these three areas using a colorimeter.

Principle of colorimeter

The colorimeter is a precision optical measuring instrument that accurately measures the color difference by the principle of optical/electrical conversion. Generally, the color data of the object is measured at five angles (15°, 45°, 110°), and the collected target is collected. The sample data and the sample data are analyzed and compared to obtain the measurement results.
In the field of optics, the color can be scalar by Lab color, the L axis is the brightness axis, 0 is black, 100 is white; the a axis is red and green axis, positive value is red, negative is green, 0 is neutral; b axis For the yellow-blue axis, the positive value is yellow, the negative value is blue, and 0 is neutral. These scales can be used to indicate the color difference between the sample and the standard. Usually, Δa, Δb, and ΔL are used as identifiers. ΔE is defined as the total color difference of the sample, but it cannot indicate the deviation direction of the sample color difference, ΔE value. The larger, the larger the color difference. The colorimeter can measure the color difference ΔE and Δa, Δb, ΔL values of the sample and the standard according to the Lab and Lch principles of the CIE chromaticity space.
ΔE is usually calculated as follows:

  • ΔE*=[(ΔL*)+(Δa*)+(Δb*)]1/2

Sometimes some companies will require a total color difference of less than 2, and some will also require a Lab value. If ΔE ≤ 2.0, it is recommended that Δa, Δb, ΔL are all ≤ 1.5, and the visual ΔE is 1.5 when the visual discrimination is discernible. Since Δa, Δb, and ΔL are generally not fixed, in the case where the requirements are too strict, the total color difference ΔE and the color difference Δc (regardless of the influence of brightness) are often required. In this case, the following formula can be calculated:

  • ΔE*=[(ΔL*)+(Δa*)+(Δb*)]1/2 Δc*=[(Δa*)+(Δb*)]1/2

Classification of colorimeter

According to the shape of the appearance, the colorimeter can be divided into:
1. Hand-held colorimeter – can directly read color difference data, generally can not connect to the computer, without software. Easy to use, cheap, but less accurate. It is widely used in the general field of color management.
2. Portable colorimeter – also known as portable spectrophotometer, can directly read the data, but also connected to the computer, with software. Small in size, easy to carry, high precision and moderate price.
3. Desktop colorimeter – also known as desktop spectrophotometric color matching instrument, generally no reading display, even when using computer color measurement, color matching software, with high-precision color measurement and color matching function, large size, stable performance, price comparison high. colorimeter product features:

  • Obtain national measurement certification;
  • Professional design standards, powerful functional configuration;
  • Improve the accuracy of each measurement by using the black and white calibration function;
  • Cost-effective for similar products; 3.5 Chinese and English switching operations;
  • Ergonomic design; 3.7 can set the L*a*b value by manual input;
  • Can achieve yellowness test; 3.9 mass data storage
  • Can be multi-point test averaging; 3.11PC computer data management;
  • Suitable for internal color evaluation and data management;
  • Display accuracy 0.01; 3.14 repeat accuracy standard deviation 0.06.

Main features of the colorimeter

  • 1. Automatically compare the color difference between the sample and the tested product, output CIE_Lab three sets of data and colorimetric data of △E, △L, △a, △b after colorimetric, and provide a reference scheme for color matching.
  • 2, with sample and single measurement mode to meet the needs of different places measurement, simple operation, accurate measurement.
  • 3. The instrument is portable. There are two power supply modes, battery and external power supply, which are convenient and practical.
  • 4. Installed with the USB expansion interface, you can connect to the computer display.

Illumination/light-receiving system: 8/d (8° illumination/diffuse light) with specular reflected light (SCI).

Display mode

  • Chromaticity values: L*a*b, L*c*h, ΔE*ab, XYZ, relative RGB values;
  • Color difference: Δ( L*a*b), Δ(L*C*H); whiteness value: Hunter whiteness, Ganz whiteness;
  • Yellowness value: YI.

Measuring range: L*: 1~100.
Measurement conditions: CIE 10° standard observer.
                 CIE D65 light source.
Repeatability: Standard deviation ∆E*ab0.6 or less (measurement condition: measuring white calibration plate 30 times).
Storage: 100 sets of standard samples, 100 sets of test samples for each set of standard samples, about 0.5 seconds.
Measuring light source: Led combined light source.
Interface language selection: Chinese, English.
Power: 4 AAA1.5V alkaline or NiMH batteries, dedicated adapter DC5V.
Interface: USB 2.0, printer.
Operating temperature and humidity: 0 ° C ~ 40 ° C, relative humidity below 80% (35 ° C), no condensation.
Weight: 550g.
Size: 77*86*210mm.

How to use the colorimeter

  • 1. Place the whiteboard, press the power to turn on the key, the boot animation appears, and the automatic black and white board calibration is in progress.
  • 2. The automatic calibration is completed and the standard measurement measurement is entered.
  • 3. Press the test button on the right side of the instrument to read the absolute value of the standard L*a*b*.
  • 4. Press the enter key to press the test port to the measured part of the positive sample. Press the test button and wait for the sound of “di” to remove the lens. The color difference between the sample and the standard is displayed: dL *, da*, db*, etc.
  • 5. According to the working principle described above, the color difference and the color cast direction between the two are judged by dL, da, and db.
  • 6. Repeat steps 3 and 4 to repeatedly check the color difference between the other tested items and the third point standard sample.
  • 8. If you want to re-sample, return to the standard measurement interface and press the button to read the data.
  • 9. After the test, turn off the power. Store the instrument in protective bags and boxes.

Correlation analysis method of colorimeter

Automatically compares the color difference between the template and the tested product, and outputs three sets of color data of L, a, b and colorimetric data of ΔE, ΔL, Δa, and Δb after colorimetry.

  • △E total color difference,
  • △L+ means white, △L- means black
  • △a+ means reddish, △a- means greenish
  • △b+ means yellowish, △b- means bluish

Desktop colorimeter

Briefly describe the color and chromatic aberration of the measured object (paper, etc.), measure the ISO brightness (blue light whiteness R457), and the fluorescent whitening of the fluorescent whitening material, and measure the CIE whiteness (the Gantz whiteness W10 and the color cast value TW10) , measuring ceramic whiteness, measuring building materials and non-metallic mineral whiteness, measuring Hunter system Lab and Lab whiteness, measuring yellowness, measuring sample opacity, transparency, light scattering coefficient and light absorption coefficient, measuring ink absorption value.

How to use a desktop colorimeter

  1. Measure the color and chromatic aberration of the object reflection.
  2. Measure the ISO brightness (blue light whiteness R457) and the fluorescent whitening of the fluorescent whitening material.
  3. Measurement of CIE whiteness (Ganz whiteness W10 and color cast value TW10).
  4. Measure the whiteness of the ceramic.
  5. Measure the whiteness of building materials and non-metallic mineral products.
  6. Measure the Hunter System Lab and Hunter Whiteness.
  7. Measure yellowness.
  8. Measure the opacity, transparency, light scattering coefficient and light absorption coefficient of the sample.
  9. Measure the ink absorption value.

Executive standards

Standards for colorimeter:

  • GB 7973: Diffuse reflectance factor (d/o) for pulp, paper and board.
  • GB 7974: Whiteness determination of paper and board (d/o).
  • GB 7975: Paper and board color determination (d/o).
  • ISO 2470: Method for the determination of blue diffuse reflectance of paper and board (ISO whiteness).
  • GB 3979: Measurement method of object color.
  • GB 8940.2: Determination of pulp whiteness.
  • GB 2913: Plastic whiteness test method.
  • GB 1840: Method for determination of industrial potato starch.
  • GB 13025: General test method for salt industry, determination of whiteness.
  • Textile industry standard: Determination of whiteness of chemical fiber.
  • GB T/5950: Method for measuring whiteness of building materials and non-metallic mineral products.
  • GB 8425: Instrumental evaluation method for textile whiteness.
  • GB 9338: Method for determining the whiteness of fluorescent whitening agents.
  • GB 9984.1: Determination of whiteness of industrial sodium tripolyphosphate.
  • GB 13176.1: Determination of whiteness of washing powder.
  • GB/T 13835.7: Test method for whiteness of rabbit hair fiber.
  • GB 4739: Method for determining the color of ceramic pigments for daily use.
  • GB 6689: Determination of dye color difference, instrument method.
  • GB 8424: Method for determination of color and chromatic aberration of textiles.
  • GB 11186.1: Method for measuring the color of coating film.
  • GB 11942: Color measurement method for color building materials.
  • GB 13531.2: Determination of cosmetic color tristimulus values and color difference ΔE*.
  • GB 1543: Determination of opacity of paper.
  • ISO 2471: Paper and board opacity assay.
  • GB 10339: Determination of light scattering coefficient and light absorption coefficient of paper and pulp.
  • GB 12911: Paper and board ink absorption test.
  • GB 2409: Test method for plastic yellow index.

Main technical characteristics

Analog D65 illuminator illumination. The CIE 1964 complementary color system and the CIE 1976 (L*a*b*) color space color difference formula were used.
Observe the geometry using d/o illumination. The diffusing ball has a diameter of 150mm and a test hole diameter of 25mm. It is equipped with a light absorber to eliminate the influence of the specular reflected light of the sample.
Indication accuracy: chromaticity coordinates 0.0001, the remaining 0.01.
Stability of measured values: After preheating, within 30 min, ≤ 0.1.

  • Repeatability: Rx, Ry and Rz s ≤ 0.10
  • Color coordinates s ≤ 0.0010
  • R457 value s≤0.10

Specimen size: The test plane is not less than Φ30mm and the thickness is not more than 40mm.
Power supply: AC 220V ± 10%, 50Hz, 0.4A.
Communication Interface: RS-232.
Working environment: temperature 5 ~ 35 ° C, relative humidity does not exceed 85%.
Dimensions and weight: 364 × 264 × 400 (mm), 17kg.

Source: China Colorimeter Manufacturer – www.spectrumgfa.com
www.spectrumgfa.com is one of the leading china Colorimeter & Spectrophotometer Manufacturer, with professional factory. We focus on the colorimeters, spectrophotoemters, haze meters, gloss meters and spectral analysis instruments research and development, manufacturing, sales and service since the company been established. Our products is widely used on Painting,textile,plastic industry,food,building material and other products. 
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