Impacts Of LED Lamp Beads On LED Display Screen
1. Viewing angle
The viewing angle of LED display screen is determined by the viewing angle of LED lamp bead.At present, most outdoor LED screen use elliptical LED with horizontal view of 100° and vertical view of 50°.Both horizontal and vertical viewing angle are 120° is for indoor LED display.Circular LED with viewing angle of 30° is generally enough for the outdoor advertising led display screen on the highway.Some LED screens on tall buildings require more strict viewing angles.Viewing angle and brightness are mutually contradictory, large angle of view will inevitably reduce brightness.The choice of viewing angle needs to be decided according to the specific use.
LED brightness is an important determinant of LED display brightness.The higher the LED brightness, the greater the use of current margin, which is good for saving power consumption and keeping the LED stable. Leds have different angle values.So under the condition that the chip brightness has been set,the smaller the angle, the brighter the LED, but the smaller the viewing angle of the display screen.In general, a 100-degree LED should be selected to ensure adequate viewing angle of LED display screen.A balanced point should be found in brightness, angle and price for LED display screen with different pixel pitch and viewing distance.
3. Failure rate
Since a full color LED display consists of tens or even hundreds of thousands of red, green, and blue Leds, the failure of an LED of any color can affect the overall visual effect of the display.Generally speaking, according to industry experience, the failure rate of LED display screen should not be higher than 3/10000 (referring to the failure caused by LED lamp beads themselves) from the beginning of assembly to 72 hours before shipment.
4. Resistance to static electricity
LED is a semiconductor device, which is sensitive to static electricity and easily leads to static failure. Therefore, anti-static ability is crucial to the life of LED display screen.In general, the human body static mode test failure voltage of LED should not be lower than 2000V.
5. Service life
The theoretical life of LED device is 100,000 hours, much longer than the working life of other parts of LED display.Therefore, as long as the quality of LED devices is guaranteed, the working current is appropriate, the PCB heat dissipation design is reasonable, the display screen production process is rigorous, LED devices will be one of the most durable components in the LED display screen.
LED devices account for 70% of the price of LED screen, so LED devices can determine the quality of LED display.China is a leading country in the production of LED devices, but also the gathering place of LED display screen manufacturing.The high technical requirement of LED display screen is the development trend in the future.The high quality requirement for LED display is not only related to the trend of LED display supplier, but also related to the development of LED display device manufacturers.
6. Attenuation characteristic
After long work,LED display screen will appear brightness decline and display color inconsistency phenomenon, which is mainly caused by the brightness attenuation of LED device.The attenuation of LED brightness will reduce the brightness of the whole LED screen.The inconsistent brightness attenuation of red, green and blue leds will cause the inconsistent color of LED display.High quality LED devices can well control the brightness attenuation. According to the standard of lighting 20mA at room temperature for 1000 hours, the attenuation of red LED should be less than 2%, and the attenuation of blue and green should be less than 10%.Therefore, the blue and green LED should not use 20mA current as far as possible, and it is better to use only 70%-80% of the rated current.
In addition to related to the characteristics of red, green and blue leds themselves, the attenuation characteristics are affected by the use of current, PCB heat dissipation design, and the operating environment temperature of display screen.
7. LED device size
The size of LED device affects the pixel pitch of LED display screen, that is, the resolution.The 5mm oval lamp bead is mainly used for outdoor LED screens above P16, the 3mm oval lamp bead is mainly used for outdoor display screens of P12.5, P12 and P10, the 3528 type patch LED is mainly used for indoor LED screens of P6 and P8, and the 2020 type patch LED is mainly used for indoor LED display screens such as P2 and P3.Under the premise of constant pixel pitch, the size of LED device increases, which can increase the display area and reduce the sense of particles.However, as the black area is reduced, the contrast will be reduced.On the contrary, the LED size decreases, reduces the display area, increases the grain sense, increases the black area, and increases the contrast.
Full color LED display is composed of countless red, green and blue LED pixels together. The consistency of brightness and wavelength of each color LED determines the consistency of brightness, white balance and chromaticity of the whole display screen.Generally speaking, LED screen manufacturers require device suppliers to provide leds in the wavelength range of 5nm and brightness range of 1:1.3, which can be achieved by device suppliers through a color splitter.Voltage consistency is generally not required.
Because the LED is angled, the full-color LED display also has angular directionality, that is, when viewed from different angles, its brightness will increase or decrease.Thus, the angle consistency of the red, green and blue leds will seriously affect the consistency of the white balance at different angles, directly affecting the fidelity of the video color of LED video wall.To achieve the consistency of the luminance changes of red, green and blue leds at different angles, it is necessary to carry out strict scientific design in the design of the packaging lens and the selection of raw materials, which depends on the technical level of the packaging supplier.If the angle consistency of the LED is not good, the white balance effect of the whole display screen at different angles will be bad.The angle consistency characteristics of LED lamp beads can be measured by LED angle comprehensive tester, which is particularly important for middle and high-end LED display screens.