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The application and advantages of Full color LED cabinet calibration

The application and advantages of Full color LED cabinet calibration


Led display cabinet correction can significantly improve the display quality of stitching display after, and relatively in-situ correction efficiency is higher, not limited by time and place, the cost is low. Therefore, the housing correction technology will become an integral part of led display manufacturing, has a good application prospect.

Due to the characteristic of LED tube, attenuation and the discreteness of circuit components, the LED display brightness and chromaticity inconsistent phenomenon, seriously affect the quality of display. In order to overcome the led display brightness and chromaticity heterogeneity problem, point by point correction technology arises at the historic moment, and is developing rapidly, it can significantly improve the uniformity of led display, to improve the display quality.

According to different applications, the point correction technology and can be divided into two kinds: one kind is the production line by box correction (housing correction); Another kind is the scene of the big correction (in-situ correction). In-situ correction technology can choose a good place to watch for correction, ensure the led display screen in the field application environment to achieve satisfactory display effect, but the complex scene environment and long-distance technical support is limited field calibration problems. Especially some foreign orders on-site calibration cost and difficulty is larger.

In order to ensure that the factory the uniformity of the LED screen, reduce the cost for technical support, housing correction technology will reflect their own unique value. Housing correction can significantly improve the display quality of stitching display after, and relatively in-situ correction efficiency is higher, not limited by time and place, the cost is low. Therefore, the housing correction technology will become an integral part of led display manufacturing, has a good application prospect.

A, led display cabinet calibration profile
Housing correction is one of the production line correction, which require led display manufacturers in the production line to increase the link. Under normal circumstances, the housing correction is arranged in the factory before the last link, mainly used to eliminate the box of brightness and chromaticity difference between internal and enclosure, to improve the uniformity of led display after joining together.

In addition to increasing correction link in production, manufacturers generally need to follow up on the screen body factory correction effect. Commonly used approach has the following three types: one is pieced together all the enclosure, to observe the effect showed, but joining together have a larger workload, it's not convenient to implement; 2 it is drawn at random for Mosaic part enclosure, to observe the effect correction; Three is to use of measurement calibration system records of all housing correction effect simulation evaluation. Increase the housing correction and simulation evaluation/sampling link LED production lines.

Housing correction shall be carried out in a dark room, which requires a plane array imaging device and each one colorimeter is used to measure the luminance and chrominance information of each box. In order to ensure that all the calibration process of box body is under the influence of the external environment condition, to meet its goal of luminance and chrominance uniformity, dark room completely sealed, and the temperature and humidity as a constant value, in the process of calibration, and calibration of the instrument must be fixed enclosure, box must be placed above the base, avoid the influence of the ground reflection.

Similar with the correction, in each case, the process of correction of the including data collection, data analysis, target setting, coefficient of correction coefficient calculation and upload, also need to control system.

Second, the key technology and difficulty
Housing correction is an effective way to improve the quality of led display image, its key technology is mainly manifested in the following two aspects: one is the box body internal uniformity between pixels, 2 it is bright color degree of consistency between the box body.

1. The box body internal uniformity between the pixel
Chamber between the pixels of similar uniformity correction and in-situ correction, are more mature, including light degree of uniformity correction and bright dark lines fixed:

(1) light degree of uniformity correction by measuring equipment to measure the LED luminance and chrominance information of each LED bulb in the box, its measuring methods involving photometry and colorimetry and digital image processing related knowledge; After given by light chrominance information according to the standard and the corresponding correction to calculate the corresponding correction coefficient and sent to the corresponding body receiving card; Cabinet lighting, display control system will be in accordance with the correction factor to adjust the LED current, make the casing all the LED brightness and chroma to achieve consistently.
Brightness correction is adjust the brightness of the fluctuation change LED to the same level, in the process of adjusting the brightness to the appropriate to reduce most of the maximum brightness of LED. Color correction is based on the principle of the RGB color matching, by changing the RGB trichromatic color coordinate to solve the problem of color deviation, for before and after the correction of color gamut contrast figure, big triangle for correction before display color gamut, RGB trichromatic color coordinates discrete distribution; Small triangle is adjusted display color gamut, RGB three colored coordinate consistency is better.

(2) due to mechanical machining accuracy and precision of assembly process, because of the limitation of splicing lamp plate spacing is slight inconsistent phenomenon, after the human visual system after low pass filtering process, the display will appear bright line or dark lines. Small spacing screen because of the existing mechanical technology limited, general requirements for the revised bright dark lines can significantly improve housing uniformity.

2. Light degree of consistency between different boxes
Housing correction and in-situ correction has a remarkable differences, timing is not joining together in school is enclosure, timing the lack of the surrounding area as a reference in school, and after the correction need to ensure that case any stitching and there is no bright color degrees of difference. And, more importantly, as a band-pass filter, the human eye vision system to the brightness of the gentle gradient differences or the details of the minimal angular resolution is not sensitive, and for contains the edge of the steps in the low frequency signal is very sensitive. Application in the field of led display which embodied in the human eye can only distinguish between 4-5% above the brightness of the led pixel difference, can easily identify case bright degree difference of 1%. That is to say, the consistency of the human eye to chamber pixel requirements is low, higher requirements and consistency between the box body. Therefore, the body is the light degree of consistency between housing correction characteristic of the key technologies.

The bright color degrees between the body not consistent mainly embodied in two aspects:

(1)The average bright color degrees of difference, between the box body when splicing box will appear obvious boundary, this can be achieved by adjusting color gamut and set the right target to achieve; When necessary, need to be equipped with higher precision colorimeter for auxiliary measure.

(2) Housing distribution appears as gradient on the gradient distribution of bright color degrees, this is due to the housing phenomenon caused by the measurement data is gradient distribution. Because the visual system for low frequency that is smooth, gradual brightness difference is not sensitive to this problem in a single housing correction were hard to find. Stitching together of the time but the enclosure, joining together the brightness of the larger jump occurs, forming obvious stitching line. This requires correction system is able to detect and to solve the problem of the gradient distribution of the measured data.

For further information, you can email at victory@dakco.cn , or go back to www.led-displays-china.com.



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