LED application of complementary five factors determine the display quality of

LED (light emitting diode) on the importance of the display is like a car engine, air conditioning compressor. Select a good performance of the LED is a basic condition for the completion of a high-performance LED display. However, even with the same dishes, the same spices, the same stove, different levels of chefs may also cook a variety of dishes. Therefore, the ability to make good use of LED is to test the touchstone display manufacturers. It is generally believed that the following five key performance indicators are closely related to the quality parameters of LED, such as brightness and angle of view, uniformity and definition, pixel out of control rate, life, energy consumption and energy efficiency.

Brightness and visual angle

The brightness of the display mainly depends on the LED intensity and LED density

Display angle should solve the problem of luminous flux waste

The brightness of the display mainly depends on the luminous intensity and LED density of LED. New technology emerge in an endless stream of LED in recent years, substrate epitaxy, chip and package etc., especially indium tin oxide (ITO) current spreading layer technology and process stable and mature, so that the intensity of LED has been greatly improved. At present, the international first-class brand of low-power LED in the horizontal perspective of 110 degrees, the vertical angle of view of the case of 50 degrees, the luminous intensity of the green tube has been as high as 4000mcd, red tube up to 1500mcd, blue tube up to 1000mcd. When the pixel spacing is 20mm, the display brightness can reach 10000nit or more. The display can work in any environment. On the visual angle of the display screen, there is a phenomenon worthy of our consideration: LED display especially outdoor display, people's point of view is from below, and to the existing LED display form of products, a luminous flux of half disappeared in the vast sky. In today's energy shortage, do we have a more reasonable solution? Worth pondering.

Uniformity and clarity

The difference of.LED performance parameters is the main reason for the uniformity

The main reason for restricting the improvement of LED display resolution is uniformity, not physical pixel spacing

With the development of LED display technology, uniformity has become the most important indicator to measure the quality of display screen. It is often said that LED shows "a little bright, brilliant", is a serious contrast between the pixel and the module of an image metaphor. Professional point of view is the dust effect and mosaic phenomenon".

The causes of uneven phenomenon are not consistent LED performance parameters; lack of display in the production, installation of precision assembly; other electronic components of the electrical parameters consistent enough; module, PCB design is not standardized.

Among them, "LED inconsistent performance parameters" is the main reason. The inconsistency of these performance parameters mainly includes: the inconsistency of the light intensity, the optical axis is not consistent, the color coordinates are inconsistent, the intensity distribution curve of each primary color is inconsistent, and the attenuation characteristics are inconsistent. How to solve the inconsistency of the performance parameters of LED, the current industry there are two ways: one is through further subdivision of LED specifications, improve the consistency of the LED performance; two is through the subsequent correction method to improve the uniformity of display. The subsequent correction is also from the early module calibration, module calibration, the development of today's point by point correction. The correction technique is developed from the light intensity correction to the light intensity and color coordinate correction.

However, we do not think it is a universal correction. The optical axis is not consistent, inconsistent, the distribution curves of light intensity attenuation characteristics of inconsistent and poor accuracy as well as the design of the assembly is not standardized, not through the subsequent correction to eliminate, or even the subsequent correction will make the optical axis, attenuation, the assembly accuracy is not consistent even worse.

Therefore, through the practice of our conclusion is: the follow-up correction is only the treatment table, and LED parameter subdivision is the root cause, is the mainstream of the LED display industry in the future.

In terms of the relationship between the uniformity and clarity of the display, the industry often has an understanding of the error, that is, the resolution to replace clarity. In fact, the clarity of the display screen is the subjective perception of the screen resolution, uniformity (signal to noise ratio), brightness, contrast and other factors. Only reduce the pixel pitch improve the resolution, while ignoring the uniformity is beyond all doubt to improve clarity. Imagine a serious "dust effect" and "mosaic phenomenon" of the display, even if it is a small physical distance between pixels, the resolution is too high, it is impossible to get a good image definition.

Therefore, in a sense, the main reason for the improvement of the current definition of LED display screen is uniformity and not physical pixel spacing".

Display pixels out of control

The main cause of the screen pixel out of control is the failure of the LED

Electrostatic discharge is the biggest cause of failure

Cause the screen pixels out of control for many reasons, one of the main reasons is that LED failure".

The main cause of LED failure can be divided into two aspects: first, the poor quality of LED itself; the two is improper use. Based on the analysis, we conclude the relationship between the LED failure mode and the two main factors.

We talked about a lot of LED failures that are usually not found in the LED routine test. In addition, by electrostatic discharge current (caused by the junction temperature is too high), external strength of improper use, a lot of LED failure is in high temperature, low temperature, fast temperature changes or other adverse weather conditions, due to differences in LED chip, epoxy resin, bracket, wire, solid crystal glue, PPA cup body materials such as thermal expansion coefficient,