Don't you know what effect the LED light bead has on the LED display?

Jun 1, 2022, 9:01:27 AM

As the heart of LED display screen, lamp beads have a variety of types, each of which has its own unique characteristics. It is tens of thousands of them together with other hardware such as control board that become LED display screen. Today, let\'s follow Xiaobian to learn about the impact of LED light beads on LED display screens!

Led display
1. Perspective

The viewing angle of LED display screen depends on the viewing angle of LED lamp beads. At present, most outdoor display screens use horizontal viewing angle of 100 °; Vertical viewing angle 50 °; Oval LED, indoor display screen is 120 ° horizontally and vertically; Patch LED for. Because of its particularity, the display screen on expressway is generally 30 °; The circular LED of the viewing angle is enough. The display screen on some high-rise buildings has high requirements for vertical viewing angle. Angle of view and brightness contradict each other. Large angle of view will inevitably reduce brightness. The choice of perspective needs to be determined according to the specific purpose.

LED brightness

2. Brightness

LED brightness is an important determinant of display brightness. The higher the brightness of the LED, the greater the margin of the current used, which is good for saving power consumption and maintaining the stability of the LED. LEDs have different angle values. When the chip brightness is set, the smaller the angle, the brighter the LED, but the smaller the viewing angle of the display screen. Generally, 100 degree led shall be selected to ensure sufficient viewing angle of the display screen. For display screens with different point spacing and different viewing distances, a balance should be found in brightness, angle and price.

3. Inefficiency

As the full-color display screen is composed of tens of thousands or even hundreds of thousands of pixels composed of red, green and blue LEDs, the failure of any color LED will affect the overall visual effect of the display screen. Generally speaking, according to industry experience, the failure rate of LED display screen shall not be higher than 3 / 10000 72 hours before shipment. (refers to the failure caused by the LED bulb itself)

4. Antistatic ability

LED is a semiconductor device, which is sensitive to static electricity and easily leads to static electricity failure. Therefore, the anti-static ability is very important to the service life of the display screen. Generally speaking, the human body electrostatic mode test failure voltage of LED shall not be lower than 2000V.

LED devices

5. Life span

The theoretical life of LED devices is 100000 hours, which is much longer than the working life of other components of LED display screen. Therefore, as long as the quality of LED devices is guaranteed, the working current is appropriate, the PCB heat dissipation design is reasonable, and the production process of display screen is rigorous, LED devices will be one of the most durable components in the whole display screen.

LED devices account for 70% of the price of LED display screen, so LED devices can determine the quality of LED display screen. China is not only a large producer of LED devices, but also a gathering place for LED display screen manufacturing. The high-tech requirements of LED display screen are the development trend in the future. The high-quality requirements of LED display screen are not only about the trend of LED display screen manufacturers, but also involve the development of LED display device manufacturers. From the perspective of LED devices, China will promote the transformation from a large LED display manufacturing country to a powerful LED display manufacturing country.

6. Attenuation characteristics

After long-time operation of LED display screen, the brightness will decrease and the color of the display screen will be inconsistent, which is mainly caused by the brightness attenuation of LED devices. The attenuation of LED brightness will reduce the brightness of the whole display screen. The inconsistent brightness attenuation amplitude of red, green and blue LED will cause the inconsistent color of LED display screen, which is the phenomenon we often say that the display screen is spent. High quality LED devices can well control the brightness attenuation. According to the standard of 20mA lighting at normal temperature for 1000 hours, the red attenuation should be less than 2%, and the blue and green attenuation should be less than 10%. Therefore, 20mA current should not be used for the design of blue and green LEDs in the display screen, and it is best to use only 70% to 80% of the rated current.

In addition to the characteristics of red, green and blue LEDs, the attenuation characteristics are affected by the use current, PCB heat dissipation design, and the ambient temperature of the display screen.

7. Dimensions

The size of LED devices affects the pixel distance of LED display screen, that is, the resolution. 5mm oval lamp is mainly used for outdoor display above p16, 3mm oval lamp is mainly used for outdoor display of p12.5, p12 and P10, 3528 patch LED is mainly used for indoor display of P6 and P8, and 2020 patch LED is mainly used for indoor display such as P2 and P3. On the premise of constant point spacing, the LED device size increases, which can increase the display area and reduce the sense of granularity. However, the contrast will be reduced due to the reduction of the black area; On the contrary, the LED size is reduced, the display area is reduced, the graininess is increased, the black area is increased, and the contrast is increased.

The full-color display screen

8. Consistency

The full-color display screen is composed of numerous red, green and blue LED pixels. The brightness and wavelength consistency of each color LED determines the brightness consistency, white balance consistency and chromaticity consistency of the whole display screen. Generally speaking, the display screen manufacturer requires the device supplier to provide LEDs with a wavelength range of 5nm and a brightness range of 1:1.3. These indicators can be achieved by the device supplier through the light and color separation machine. Voltage consistency is generally not required. As the LED has an angle, the full-color LED display also has angle directionality, that is, when viewed from different angles, its brightness will increase or decrease. In this way, the angle consistency of red, green and blue LEDs will seriously affect the consistency of white balance at different angles, and directly affect the fidelity of video color on the display screen. In order to achieve the matching consistency of the brightness changes of red, green and blue LEDs at different angles, it is necessary to strictly carry out scientific design in the packaging lens design and raw material selection, which depends on the technical level of the packaging supplier. For a display screen with good white balance in the normal direction, if the angle consistency of the LED is not good, the white balance effect of the whole screen at different angles will be poor. The angle consistency characteristics of LED lamp beads can be measured by LED angle comprehensive tester, which is particularly important for medium and high-grade display screens.

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