How to identify the quality level of LED display

With the widespread use of LED displays in various fields, more and more people are becoming familiar with and using LED displays. How to judge the quality of the display screens and choose the cost-effective products that suits them, which requires us to master Based on the basic technical indicators of the LED display, it mainly identifies its quality level from the aspects of the function and performance of the display.

First of all, from the function of the display screen, the basic function of the display device is to display our various texts, pictures, videos and other materials to more people to watch. The most important point is the real display of the material. We need our display to have a high degree of reducibility, and how to improve its reductiveness is mainly accomplished by the following technical indicators.

How to identify the quality level of LED display

1, brightness

The brightness of the brightness gives a very intuitive feeling, you can distinguish the height at a glance, do not think that the higher the brightness of the display, the better, mainly according to your use environment and viewing distance, the indoor display is generally 1000nit is more suitable, the outdoor display is higher than 6000nit, and the semi-outdoor is more suitable between 2500 and 5000nit. The brightness of the small-pitch display is lower, in the range of 100 to 300nit, in short to satisfy the audience. Under the premise of seeing the image under the environment, watching the eyes for a long time does not cause a stinging sensation.

2, color temperature

When we see that the image color is inconsistent or different from the material on the display, our picture is seriously distorted, which is related to the color temperature of the white balance of the display. If the human eye directly views the display, its white balance The color temperature value is suitable between 6500 and 8000K, and if it is the display screen used by the TV station, the actual color temperature of the screen should be adjusted to about 5500K, so that the picture on the display screen is true after being recorded by the camera.

3, perspective

For display devices, the larger the angle of view, the better, so the range that can be viewed is greater. The viewing angle of the display screen is divided into a horizontal viewing angle and a vertical viewing angle. At present, the indoor full-color screen horizontal viewing angle can be greater than 140 degrees, the vertical viewing angle is greater than 100 degrees, and the outdoor full color screen horizontal viewing angle is greater than 100 degrees, and the vertical viewing angle is greater than 90 degrees. On the basis of clear and complete viewing of images in the range of viewing angles, the phenomenon of color cast can not occur in different viewing angles. This is mainly related to the arrangement of RGB chip packages of LED lights. Currently, there are two types of fonts in the market: vertical and vertical. The way, the effect is compared as shown below:

4, gray

When the image on the display is poorly layered and the pixel is lost compared with the material, the gray level of the screen is low, and the content of the material cannot be completely and clearly presented. Its professional test method is that the gray bar test can visually see the level of gray level. At present, the industry can achieve 16BIT gray level, and then it will reach 18BIT. The following picture shows the gray bar test chart:

5, the refresh rate

When the human eye directly views the display screen, it feels flickering. When there are many horizontal dark lines when shooting with the camera or camera, the refresh rate of this screen is low. Under the condition that the human eye does not affect the direct viewing of the human eye, the refresh rate of the display screen cannot be lower than 300 Hz. To meet the requirements of camera equipment such as cameras and cameras, the refresh rate of the display screen needs to be above 2000 Hz. The following figure shows the high and low refresh rate. Comparison of effects:

6, contrast

When we look at the screen of the display, we feel that the picture is a bit white, and the gray feeling is like a layer of tulle attached to the surface, the picture is not transparent, which means that the contrast of this screen is low, and the contrast value can not be low. At 1000:1, it is mainly related to the LED lamp package and the module mask design. The contrast of the LED lamp of the black bracket is significantly higher than that of the white bracket. The following figure shows the effect comparison:

7, uniformity

Whether the display screen is clean, no pitting, mosaic phenomenon, which is mainly related to the brightness and color consistency of the LED light, we can watch the brightness and color uniformity of the screen in RGB monochrome and white state. The following picture shows the comparison of test and image effects:

After we understand the function of the display, a display with excellent display needs good performance to be regarded as a high-quality display. We mainly identify the performance by the following aspects.

(1), pixel out of control point (warranty period)

Pixel out of control points are divided into points and constant bright points. The figure below shows the industry as the standard level:

With the birth of small-pitch screens, its industry standard can no longer be applied to small pitches, its standard should be higher, and its runaway rate should be controlled below 1X10-5.

(2), protection level and safety

The degree of protection is mainly waterproof and dustproof. The higher the IP value, the higher the protection level. The following figure is the industry standard:

The safety is mainly reflected in the leakage current, the value of the ground leakage current is ≤3.5mA under the condition of X1.1 times of U; the second is the electric strength, and there is no insulation breakdown under the test condition of 1,500V, 1min.

(3), energy consumption and energy efficiency

In order to reduce the power consumption of the display, improve the energy efficiency, thereby reducing the temperature of the display, extending its service life, the temperature drops by 10 ° C, the product life is doubled, mainly in the following aspects:

A, low Vf value LED

B, low Vds value constant current drive IC

C, low impedance PCB design

D, module working voltage 4.2V 3.8V

E, switching power supply PFC ≥ 0.95 conversion efficiency ( ≥ 0.85)

(4), reliability

Even if its display is excellent, if its reliability is not high and the unstable failure rate is high, the quality of this display is also very low. In order to improve its reliability, it is mainly considered from the following aspects:

A. Material selection: Material analysis

B, thermal design: heat dissipation, heat distribution

C, redundancy: switching power supply, controller, PCB line

D, material tolerance: the remaining 20%

E, reliability simulation verification test: life, certification

Through the above detailed study of the function and performance of the product, when we look at a display screen again, we know where to identify the quality level, so as to achieve the purpose of choosing a cost-effective product that suits you.