Analysis on the necessity of correction of full-color LED display

From the current market demand analysis, the necessity of on-site proofreading is becoming more and more prominent.

Uniformity proofreading can be summarized as factory proofreading, repair proofreading, service area proofreading and on-site proofreading.

Generally speaking, when the LED display operates to a certain time, all LED light-emitting tubes will have brightness attenuation, and the attenuation curves of the three primary color tubes are not common. Therefore, their brightness will also be lower than that before leaving the factory. However, the difference of photoelectric characteristics of each LED makes the degree of decline of their brightness error. Therefore, when the display screen is used for a period of time, the brightness of the LED will be attenuated to varying degrees, resulting in uneven display between pixels. Then, compared with the screen at the beginning of delivery, the whole picture will have a granular display condition, or the brightness of the whole picture will decrease. The different attenuation curves of the three primary color tubes change the white balance and color temperature.

In practice, due to the attenuation of LED and the change of other factors such as ambient temperature, it is almost inevitable that the function of very excellent display screen becomes worse when leaving the factory. It is impossible to disassemble the installed LED display screen and transport it back to the factory for calibration. In view of these features, it is necessary for the display manufacturer to conduct on-site calibration to ensure that the display function at the factory is always maintained throughout the life cycle of the display. Several on-site proofreading methods:

1. Calibration method according to LED operation time:

This is an early on-site calibration method, which is to calibrate the display screen on the spot according to the tracking and recording the operation time of each LED module. By roughly calculating the working time of each LED, measuring their respective uniform brightness attenuation, estimating different calibration levels, and then sending them to each LED module for corresponding adjustment. This method does not require any manual input. However, this method ignores a very important problem. The LED attenuation frequency estimated by operation time is not suitable for each LED. With the increase of operation time, the fluctuation scale of LED attenuation frequency is becoming larger and larger. The calibration on a uniform basis makes some LEDs close to the calibration level, but makes other LEDs more and more contrary. Because the brightness levels between modules are different, and there is no effective way to adjust these modules with mismatched brightness, a series of problems will occur when adjusting the uniformity between modules at different operation times, and the key is that this method can not complete the calibration between pixels. Therefore, through this kind of proofreading, the whole feeling of the display screen will appear mosaic, which can not well improve the uniformity of the display screen in the later stage.

2. According to the common proofreading method on site:

In order to completely improve the uniformity of the display screen, it is necessary to use special collection equipment to quickly collect the light color information of each pixel of the LED display screen on site, compensate the practical attenuation degree of each led through relevant algorithms, and then complete the real meaning of common proofreading, Even LED modules that do not work together can complete pixel level calibration. Through proofreading, the display screen is restored to the uniform display function just before leaving the factory.