Since the LED is angled, the full color LED display also has angular orientation, that is, the brightness is increased or decreased when viewed at different angles. In this way, the angular 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 display video color. To achieve the consistency of brightness change of red, green and blue LEDs at different angles, it is necessary to strictly carry out scientific design on package lens design and raw material selection, depending on the technical level of the package supplier. In the normal direction white balance is good, if the angle of the led is not consistent, the white balance effect of the whole screen at different angles will be bad. The angle consistency characteristic of the led lamp bead can be measured by the led angle comprehensive tester, which is especially important for the middle and high-end display. The most critical component of the full color display is the led lamp bead. All led lamp bead is the most expensive and largest component in LED display, which plays a leading role in the quality of LED display.
Let's take a look at the LED lamp bead as the most critical component of the led display. How to identify the pros and cons of the led lamp bead?
First, led is the key component used in the full-color screen machine, using thousands to tens of thousands of leds per square meter;
Second, LED is the main body that determines the performance of the entire screen optical display, directly affecting the audience's evaluation of the display;
Third, led accounts for the largest proportion of the overall cost of the display, ranging from 30% to 70%.
How to identify the pros and cons of LED display beadFirst, look at the solder joints. The LED lamp strip produced by the regular led lamp manufacturer is made by SMT chip process, which is produced by solder paste and reflow soldering process.
Second, look at the quality of FPC. FPC is divided into copper and rolled copper. The copper foil of the copper plate is convex. If you look closely, you can see it from the connection between the pad and the FPC.
Third, look at the cleanliness of the surface of the led light. If the LED strip produced by the SMT process has a very clean surface, no impurities or stains can be seen.
Fourth, look at the chip and production process of led lights, with the eyes can not see the difference, to use aging equipment and testing equipment, if you put several manufacturers of LED on the aging instrument with high current aging for 24 hours or longer Time, you then measure the led brightness of several manufacturers, see that the LED luminous intensity attenuation is the smallest, the attenuation is the best.
What are the effects of led lamp beads on led display?
1. PerspectiveThe viewing angle of the led display is determined by the viewing angle of the led lamp bead. At present, most of the outdoor display screens use a horizontal viewing angle of 100°; a vertical viewing angle of 50°; an elliptical led, and an indoor display screen with a horizontal and vertical orientation of 120°; The display on the highway is generally 30° due to its particularity; a circular led with a viewing angle is sufficient. Some high-rise buildings require a higher vertical viewing angle. The angle of view and the brightness are contradictory, and a large angle of view necessarily reduces the brightness. The choice of perspective needs to be determined based on the specific application.
2, brightnessLed brightness is an important determinant of display brightness. The higher the brightness of the led, the larger the margin of the current used, which is beneficial for saving power and keeping the LED stable. Led has different angle values. When the brightness of the chip is fixed, the smaller the angle, the brighter the led, but the smaller the viewing angle of the display. Generally, a 100 degree LED should be selected to ensure a sufficient viewing angle of the display. For displays with different dot pitches and different line of sight, a balance should be found in brightness, angle and price.
3, failure rateSince the full-color display is composed of tens of thousands or even hundreds of thousands of red, green and blue LEDs, the failure of any color led will affect the overall visual effect of the display. In general, according to industry experience, the failure rate before the assembly of the led display starts to aging for 72 hours before shipment should be no more than three ten thousandths (refer to the failure caused by the LED lamp itself).
4, antistatic abilityLed is a semiconductor device that is sensitive to static electricity and is highly susceptible to electrostatic failure. Therefore, antistatic capability is critical to the life of the display. In general, the human body static mode test failure voltage of led should not be lower than 2000V.
5, lifeThe theoretical life of the led device is 100,000 hours, which is much larger than the working life of other components of the LED display. Therefore, as long as the quality of the LED device is guaranteed, the working current is suitable, the PCB heat dissipation design is reasonable, and the display production process is rigorous, the LED device will be the display screen. One of the most durable parts in the machine. Led devices account for 70% of the price of led display, so that led devices can determine the quality of led display quality. China is a big country in the production of LED devices, and it is also a gathering place for LED display. The high-tech requirements of led display is the future development trend. The high-quality requirements of led display are not only related to the trend of LED display manufacturers, but also the development of led display device manufacturers. From the LED device check, promote China's transformation from a large LED display manufacturing country to a led display manufacturing power.
6, attenuation characteristicsAfter the LED display is working for a long time, the brightness will drop and the color of the display will be inconsistent, mainly due to the brightness decay of the LED device. The attenuation of the led brightness will cause the brightness of the entire screen of the display to decrease. The inconsistency of the red, green, and blue LED brightness attenuation levels will cause the color of the LED display to be inconsistent, which is what we often say about the display screen. High-quality LED devices provide excellent control of the brightness attenuation. According to 1000 hours normal temperature to illuminate 20mA standard, the red attenuation should be less than 2%, the blue and green attenuation should be less than 10%, so blue and green led should not use 20mA current in the display design, preferably only 70% to 80% % rated current. In addition to the characteristics of the red, green, and blue LEDs, the attenuation characteristics are affected by the current, the heat dissipation design of the PCB, and the ambient temperature of the display.
7, sizeThe size of the led device affects the pixel point distance of the led display, ie the resolution. The 5mm elliptical lamp is mainly used for outdoor display above P16, the 3mm elliptical lamp is mainly used for outdoor display of P12.5, P12 and P10, and the 3528 type patch is mainly used for indoor display of P6 and P8. 2020 type patch LED is mainly used for indoor display such as P2 and P3. Under the premise of constant dot pitch, the size of the LED device is increased, which can increase the display area and reduce the graininess. However, since the black area is reduced, the contrast is reduced. On the contrary, the LED size is reduced, the display area is reduced, and the graininess is increased. The black area increases and the contrast is increased.
8, consistencyThe full-color display is composed of countless red, green and blue LEDs. The brightness and wavelength consistency of each color led to the brightness consistency, white balance consistency and uniformity of the entire display. Sex. In general, display manufacturers require device vendors to provide a 5 nm wavelength range and a 1:1.3 brightness range for the LEDs, which can be graded by the device supplier through a spectroscopic color separation machine. The consistency of the voltage is generally not required.
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