Several main parameters that affect LED display performance

Time:2018-11-29 Views:726

Derensel technical guidance believes that the main parameters affecting the performance of LED display screen in the market are as follows 11 main aspects

The power consumption of the 1.

LED is a very energy-saving luminous device.The power consumption of LED devices determines the power consumption of full-color LED display screen.Take P20 full-color outdoor display screen as an example. When video is playing, the average power consumption is about 250W per square meter.For some 24-hour advertisers, due to the large area and long playing time, power consumption is an indicator of their concern.Higher brightness leds can be used to create displays that use lower current.Generally speaking, the nominal brightness of red, green and blue leds will be increased by 20% each, and the power consumption of the display screen will be reduced by 15% if the brightness of the display screen remains unchanged.

Life of 2.

The theoretical life of LED devices is 100,000 hours, which is much longer than the working life of other parts of LED full-color 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 the display screen is rigorous, LED devices will be one of the most durable parts of the whole display machine.

3. Attenuation characteristics

After working for a long time, LED full-color display screen will show the phenomenon of brightness decline and inconsistent display color, which is mainly caused by the brightness attenuation of LED devices.The attenuation of LED brightness will cause the brightness of the whole screen to decrease.Inconsistent brightness attenuation of red, green and blue leds will lead to inconsistent color of LED display screen, which is often referred to as the phenomenon of spent display screen.High quality LED devices can well control the brightness attenuation range.According to the standard of lighting 20mA at room temperature of 1000 hours, the red attenuation should be less than 2%, and the blue and green attenuation should be less than 10%. Therefore, the blue and green LED screen design should try not to use 20mA current, and it is best to use only 70% to 80% of the rated current.

In addition to the red, green and blue LED characteristics, attenuation characteristics are related to the use of current, PCB heat dissipation design, the use of environmental temperature display screen, etc., all have an impact on attenuation.

Perspective of 4.

The perspective of full-color LED display depends on the perspective of LED devices.At present is chosen mostly outdoor displays horizontal Angle 110 °, vertical Angle of view of 50 ° 546 elliptical LED, indoor display is chosen level is 140 ° from vertical SMD leds.Display on the highway 30 ° Angle is generally selected due to its particularity of round LED is enough.Some tall buildings have screens that require a higher vertical view.The Angle of view and brightness are contradictory to each other.The choice of perspective needs to be determined according to the specific purpose.

5. Brightness

Brightness is the basic index of LED full-color display screen.In the industry, it is generally believed that outdoor display screen should not be less than 5000nits and indoor display screen should not be less than 800nits.The brightness of the whole screen depends on the superposition of the brightness values of red, green and blue leds composed of each pixel point. The brightness values of red, green and blue leds are approximately proported in a ratio of 3:6:1.Based on the factory nominal value of device current, different current values of red, green and blue are set to achieve the above ratio.For example, if 1R1G1B ratio is used for outdoor P20 full-color display screen, the brightness of each pixel point is 3000mcd if the green tube is 1800mcd, the red tube 900mcd and the blue tube 300mcd, and the maximum brightness of the whole screen is 2500 points per square meter * 3000mcd=7500nits.Finally, the brightness required by the specification can be achieved by adjusting the current value.Brightness is not the higher the better, just the right.

6. Consistency

(1) brightness consistency

The brightness consistency of LED full-color display depends on the brightness consistency of LED light emitting chip and packaging consistency.It is generally required that the maximum and minimum brightness ratio of each color of LED devices should not be higher than 1.3, and then according to the scientific PCB lamp insertion method, the brightness difference between adjacent two leds of the same color should be less than 10%.

(2) color consistency

The color of LED devices that make up LED full-color display screen depends on the wavelength of LED. If the wavelength range is too wide, the color difference will be large, which will affect the consistency of chromaticity of the display screen.Generally speaking, the wavelength range of red, green and blue colors should be within 5nm.

(3) Angle consistency

LED full-color display screen is composed of LED devices with angles. The inconsistency of LED device angles will seriously affect the brightness and chromaticity consistency of different angles of the display screen.The consistency of red, green and blue brightness curves of LED devices (especially elliptic lamps) with the change of Angle of view also seriously affects the consistency of brightness and chromaticity of different angles of the display screen.Of all the full-color screen parameters, this parameter is the most difficult to achieve.The difference of high-grade LED full-color display mainly lies in this.

Size 7.

The size of LED device affects the pixel distance of LED full-color display screen, that is, the resolution.The 5mm oval lamp is mainly used for outdoor display screens above P16, the 3mm oval lamp is mainly used for outdoor display screens of P14, P12.5, P12 and P10, the 3528 patch LED is mainly used for indoor display screens of P5, P6,P7.62, P8 and P10, and the 5050 patch LED is mainly used for outdoor display screens of P8,P10, P13.3, P16 and P26.6.Under the premise of constant point spacing, LED pixel size increases, which can increase the display area and reduce the particle sense. However, as the black area decreases, the contrast will be reduced.On the contrary, LED pixel size decreases, reducing display area, increasing particle sense, increasing black area and increasing contrast.

Wavelength 8.

LED full-color display is composed of red, green and blue leds, each color is measured by wavelength.The color of the display is closely related to this wavelength.The average wavelength of red, green and blue leds determines the dynamic color range of LED full-color display.Generally speaking, the wavelength of red LED is about 625nm, green 525nm and blue 470nm.High quality LED full color display should have a wide color range.

9. Failure rate

An important indicator of LED full-color display screen is the blind spot rate of LED, which completely depends on the quality of LED components (excluding the influence of virtual welding, leakage welding and poor contact in the production process of display screen).LED devices should be sampled and tested before leaving the factory, including room temperature lighting, high temperature and humidity, cold and heat shock and other series of tests, to ensure the stability, consistency and continuity of the product.In general, high-quality LED devices used in full-color displays should have a loss rate of less than one in 10,000 for 1,000 hours.

10. The refresh rate

Refresh rate is an important indicator of the display screen and a parameter that represents the stability of a display screen. The higher refresh rate is, the more stable the display screen will be.Generally, the refresh rate of the display screen reaches 300HZ, and the scanning line will not appear when shooting with a general camera.If a professional camera is required to shoot without scanning lines, the refresh rate is required to be more than 600HZ, and now many control systems can achieve more than 1000HZ.

11. Control system

Control system is also an important content affecting LED display. As long as the above 9 items are determined by the inherent properties of LED, the control system can choose by itself, so as to make LED display more stable, refresh rate higher and display effect better.At present, the industry do LED control synchronization system is the main ling star rain, carlet, asynchronous system is mainly research, xi xun.