As we all know, LED lamp beads are light-emitting diodes. LED lamp beads are widely used in lighting, LED large screen display, traffic lights, decoration, computers, electronic toys and gifts, switches, telephones, advertising, urban glory project and many other production fields.
LED lamp beads as LED electronic display screen production of the highest, the largest consumption of components. The quality of LED electronic display screen plays a leading role in the LED lamp beads, today to introduce why LED lamp beads are the most critical components of LED electronic display screen, how to identify the pros and cons of LED lamp beads?
What impact does LED bead have on LED display screen
The most important component of full-color LED electronic display is LED bead. There are three reasons:
First, LED full color screen in the use of the most key components, per square meter will use thousands to tens of thousands of LED beads;
Second, LED beads determine the main part of the optical display performance of the whole screen, directly affecting the audience's evaluation of the display screen;
Third, LED electronic displays account for the largest share of the total cost, ranging from 30 percent to 70 percent.
How to identify the quality of LED electronic display beads
First, look at the solder joint. The LED beads produced by regular LED bead manufacturers are produced by SMT patch process, solder paste and reflow welding process
Second, look at the quality of FPC. FPC copper and calendered copper two, copper foil copper plate is protruding from the closer inspection can be seen from the welding pad and FPC joint
3. See the cleanliness of the surface of LED lamp beads. If the LED bead produced by SMT process is used, its surface cleanliness is very good, and there are no impurities and stains to be seen.
Four, see the LED chip and production processes, with his eyes is can't tell the difference between the use of aging equipment and testing equipment, if you put a few manufacturer of LED on aging instrument with large current aging 24 hours or longer, to measure a few manufacturer of LED brightness, look at the LED luminous intensity attenuation, minimum damping least that quality is the best.
1 point of view
The Angle of view of LED electronic display is determined by the Angle of view of LED lamp bead. At present, most outdoor electronic display screens use a horizontal viewing Angle of 120°. Vertical Angle of view 50°; The elliptic LED indoor electronic display screen is 120° horizontally and vertically. Due to its particularity, 30° is generally used for electronic display screens on highways. Circular leds for viewing angles are enough, and electronic displays on some tall buildings require a higher level of vertical viewing. Angle of view and brightness are mutually contradictory, large Angle of view will certainly reduce brightness. The choice of perspective depends on the specific purpose.
LED brightness is an important determinant of the brightness of electronic display screen. The higher the LED brightness, the larger the allowance of using current, which is good for saving electricity consumption and maintaining LED stability. 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. Generally, a 120-degree LED should be selected to ensure sufficient viewing Angle of the display screen. For electronic display screens with different distances and different line-of-sight, a balance should be found between brightness, Angle and price.
3 failure rate
Since the full-color electronic display 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 electronic display. Generally speaking, according to industry experience, the failure rate of LED electronic display screen before shipment should not be more than 3/10000 (refers to the failure caused by LED lamp bead itself) within 72 hours after the installation of LED electronic display screen.
4. Antistatic capacity
LED semiconductor devices are sensitive to static electricity and can easily lead to static electricity failure. Therefore, the anti-static ability is very important for the life of the display screen. Generally speaking, LED body electrostatic mode test failure voltage should not be lower than 2000V
The theoretical life of LED lamp bead is 100,000 hours, which is far longer than the working life of other parts of LED electronic display. Therefore, as long as the quality of LED lamp bead is guaranteed, the working current is appropriate, the PCB heat dissipation design is reasonable, and the production process of electronic display is rigorous, LED lamp bead will be one of the most durable parts of the display machine.
LED lamp beads account for 70% of the price of LED electronic display screen. Therefore, LED lamp beads can determine the quality of LED electronic display screen. China is the leading producer of LED lamp beads and the gathering place of LED electronic display screens. The high technical requirements of LED electronic display are the future development trend. The high quality requirements of LED electronic display are not only about the trend of LED electronic display manufacturers, but also about the development of LED electronic display device manufacturers. From LED lamp beads to promote the transformation of China from a leading manufacturer of LED electronic display screens to a leading manufacturer of LED electronic display screens.
6 attenuation characteristic
After working for a long time, LED electronic display screen will appear the phenomenon of brightness decline and inconsistent color of display screen. This phenomenon is mainly caused by the attenuation of LED brightness caused by the attenuation of LED brightness, which will reduce the brightness of the whole screen of the display screen. Red, green, blue LED brightness attenuation amplitude is not consistent will cause LED display color inconsistency, is often said the display spent phenomenon. High quality LED devices can control the brightness attenuation. According to the standard of lighting 20mA at room temperature for 1000 hours, red attenuation should be less than 2% blue and green attenuation should be less than 10%. Therefore, when designing blue and green LED electronic display screen, try not to use 20mA current, and only use 70% to 80% rated current.
In addition to the correlation with the red, green and blue LED's own characteristics, the attenuation characteristics are affected by the use of current, PCB heat dissipation design, and the ambient temperature of the display screen.
The size of LED beads affects the pixel distance, or resolution, of LED electronic display. Type 3535 patch LED is mainly used for P10/P8/P6 indoor display, and type 2121 patch LED is mainly used for P2/P2.5/P3 indoor display. Under the premise of constant point spacing, LED bead size increases, which can increase the display area and reduce the graininess. However, due to the decrease of the black area, the contrast will be reduced. On the contrary, LED size decreases, reducing display area, increasing graininess, increasing black area and increasing contrast.
Full-color electronic display screen is composed of numerous red, green and blue LED pixels assembled into each color LED brightness, wavelength consistency determines the brightness consistency, white balance consistency, chroma consistency of the entire display screen. Generally speaking, display manufacturers require device suppliers to provide 5nm wavelength range and 11.3 brightness range of LED. These indicators can be classified by device suppliers through spectral separators to achieve voltage consistency. Generally speaking, no requirements are required.
Due to the Angle of LED, the full-color LED electronic display screen also has the direction of Angle, that is, the brightness will increase or decrease when viewed from different angles. The consistency of red, green and blue LED angles will seriously affect the consistency of white balance at different angles, directly affecting the fidelity of video color of the display screen. In order to achieve the matching consistency of the brightness change of red, green and blue leds at different angles, it is necessary to carry out strict scientific design in packaging lens design and raw material selection, which depends on the technical level of packaging suppliers. No matter how good the normal white balance is, if the LED Angle consistency is not good, the white balance effect of the whole screen at different angles will be bad.