Eight effects of LED lamp beads on LED display
1, the Angle of view
The view of LED display depends on the view of LED lamp bead. To date, most outdoor display screen choose horizontal Angle 100 °; 50 ° and vertical perspective; Elliptical LED, indoor display, choose level is 120 ° from vertical; The patch LED. Display on the highway 30 ° is generally selected due to its particularity; A round LED with a view is enough. Screens in some tall buildings require a higher vertical view. Angle of view and brightness are contradictory, large Angle of view will inevitably reduce the brightness. The choice of perspective needs to be determined according to the specific purpose.
LED brightness is an important determinant of display brightness. The higher the brightness of LED, the greater the residual amount of current used, which is good for saving power consumption and keeping LED stable. LED has different Angle values. When the brightness of the chip is set, the smaller the Angle is, the brighter the LED is, but the smaller the Angle of the screen is. A 100-degree LED should be selected to ensure a sufficient view of the display. Display screens with different spacing and different viewing distances should find a balance between brightness, Angle and price.
Because the full-color display consists of tens of thousands or even hundreds of thousands of pixel points composed of red, green and blue leds, the failure of any color LED will affect the overall visual effect of the display. Generally speaking, according to industry experience, the failure rate should be no more than 3 parts per million before the LED display starts to be assembled into 72 hours of aging and delivery.
4. Anti-static ability
As a semiconductor device, LED is sensitive to static electricity and can easily lead to electrostatic failure. Therefore, anti-static ability is crucial to the life of the display screen. Generally speaking, the test failure voltage of LED in human electrostatic mode should not be lower than 2000V.
Theoretical service life of the LED devices for 100000 hours, far more than the working life of the LED display other parts, so the right LED device quality guarantee, the working current, reasonable PCB thermal design, display production process is rigorous, LED display screen machine device will be in one of the most durable components.
LED devices account for 70% of the price of LED displays, so LED devices can determine the quality of LED displays. China is not only a large producer of LED devices, but also a gathering place for LED display production. The high technology requirement of LED display is the future development trend. The high quality requirement of LED display is not only about the trend of LED display manufacturers, but also related to the development of LED display device manufacturers. From the control of LED devices, China has promoted the transformation from a leading manufacturer of LED displays to a leading manufacturer of LED displays.
6. Attenuation characteristics
After working for a long time, the LED display will be reduced in brightness and the color of the display will be inconsistent, mainly due to the brightness attenuation of the LED device. The attenuation of LED brightness will reduce the brightness of the whole screen. The inconsistent brightness attenuation range of red, green and blue leds will lead to the inconsistent color of LED display screens, which is what we often say the display screen is spent. High quality LED devices can control the brightness attenuation well. By 1000 hours at room temperature light 20 ma standards, attenuation should be less than 2%, red, blue, green attenuation should be less than 10%, in blue, green LED display screen design as far as possible not to use when 20 ma current, had better use only 70% to 80% of the rated current.
In addition to the characteristics of red, green and blue leds themselves, the attenuation is affected by current, PCB panel cooling design, display environment temperature and so on.
The size of LED device affects the pixel distance of LED display, i.e. resolution. More than 5 mm elliptic lamp is mainly used for P16 outdoor display, 3 mm elliptic lamp is mainly used for outdoor P12.5, P12, P10 display, type 3528 SMD leds is mainly used for indoor display, P6, P8 type 2020 SMD LED is mainly used for P2, P3 etc indoor display. Under the premise of constant point spacing, the size of LED device increases, which can increase the display area and reduce the sense of particles. On the contrary, LED size decreases, reducing display area, increasing particle sense, increasing black area and increasing contrast.
Full-color display screen is made up of thousands of red, green and blue leds Mosaic composed of pixels, each color LED brightness, the wavelength determines the whole screen brightness consistency, the consistency of the white balance consistency, color uniformity. In general, the manufacturer of display device vendor for 5 nm wavelength range and 1:1. The 3 LED brightness range, these indicators can be made of classification through the testing machine can achieve device supplier. Voltage consistency is generally not required.
Because LED has Angle, full-color LED display also has Angle direction, 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. To be red, green, blue three kinds of LED brightness changes when matching consistency in different angles, encapsulated lens design, choice of raw materials is needed in the strict scientific design, this depends on the technical level packaging suppliers. If the Angle of LED is not consistent well, the white balance effect of different angles of the whole screen will be bad. The Angle consistency of LED lamp bead can be measured by LED Angle comprehensive test instrument, especially important for medium and high grade display screen.