A special full-color LED display option

Full-color LED display is the most critical components of LED device. There are three reasons: First, LED full-color machine is used in the largest number of key devices per square meter will be used only a few thousand to tens of thousands of LED; second, LED screen is the decision of the entire optical properties of the main display, a direct impact on the The audience for the evaluation of the screen; in the third, LED display in the share of the overall cost the most, from the 30-70 percent range.

LED full-color LED display is the most critical device, which is equivalent to the computer CPU. LED has already decided on the choice of more than 50% of the entire display quality. If you choose not good LED, other parts of the screen no matter how well it can not make up for deficiencies in quality of the display.

Full-color LED display LED special quality and parameters can be attributed to the following five elements:

1, the failure rate

As the full-color display by the tens of thousands or even hundreds of thousands of groups red, green and blue LED in three components of the pixels, any color LED failure will affect the overall visual display. In general, according to industry experience in the LED display began to assemble the aging ship within 72 hours prior to the failure rate should be not more than three ten thousandths (LED refers to the device itself causes of failure).

2, anti-static capacity

LED is a semiconductor device, sensitive to static electricity, caused by static electricity vulnerable to failure, the ability of anti-static display of life is crucial. In general, LED model of the human body static electricity voltage test failure should not be lower than the 2000V.

3, attenuation characteristics

Red, green and blue LED with the working hours have increased the brightness of the attenuation characteristics. LED chip advantages and disadvantages, auxiliary materials, packaging technology and quality level of the LED determines the rate of decay. In general, 1000 hours, 20 mA at room temperature after the pilot light, the red LED attenuation should be less than 10% of the blue, green LED attenuation should be less than 15%. Red, green, blue attenuation of the consistency of full-color LED display great influence on the future of the white balance which in turn will affect the display screen fidelity.

4, brightness

Brightness LED screen brightness is an important factor in the decision. The higher the LED brightness, the greater the margin of current use, saving power and maintain the stability of the LED is good. LED different point of view the value of chips in the brightness has been set, the smaller the angle, LED light is more, but the screen is smaller the angle. In general should choose 100-degree LED display in order to ensure sufficient perspective. Different spacing and different points of-the-horizon display, should be light, the price point of view and find a balance.

5, consistency

Full-color screen is made of red, green and blue LED composed of form themselves into the number of pixels, each color LED brightness and wavelength of consistency determines the brightness of the display consistency, consistency of white balance, color Consistency. In general, the display device manufacturers require suppliers to provide the wavelength range of 5nm and the ratio of the brightness of the scope of the LED, these indicators can be adopted by the device supplier color grading machine to achieve. The voltage does not require uniformity in general.

As the LED is the point of view, the full-color LED display with the same direction point of view, that is, in a different viewing angle, the brightness will increase or decrease the. In this way, red, green and blue LED color the perspective of three will seriously affect the consistency of different angles, white balance, with a direct impact on the video display of color fidelity. To be red, green and blue LED in three different angles of the match when the brightness changes in the consistency needed in the lens package design, choice of raw materials in strict scientific design, depending on the supplier of packaging technology. White balance to the direction of the law no matter how good display, LED if the point of consistency is not good, the whole screen different point of view of the effect of white balance will be the worst. LED device point of view of the characteristics of consistency point of view can be integrated LED tester measured, for the medium and high-end display is particularly important.

Second, full-color LED display exclusive use:

High-quality LED also need a good method to use and the environment, boils down to the use of the eight main points are as follows:

1, anti-static

Display assembly plant should have a good anti-static measures. Special anti-static, anti-static floors, iron anti-static, anti-static pad to Taiwan, the Central Anti-static, anti-static clothing, humidity control, ground equipment (cut foot machine, in particular) are the basic requirements, and use electrostatic detection instrument on a regular basis .

2, wave soldering temperature and time off

To strictly control the wave front of the welding temperature furnace and over time, the recommendations are as follows: pre-heating temperature of 100 ℃ ± 5 ℃, the highest no more than 120 ℃, and warm-up for a smooth rise in temperature, welding temperature of 245 ℃ ± 5 ℃, welding Time does not recommend more than 3 seconds, after the furnace should not have the impact or vibration LED, until the resumption of state at room temperature. Wave soldering machine temperature parameters on a regular basis to detect, which is decided by the characteristics of the LED, or overheating of the fluctuations in temperature will cause direct damage to the LED or LED quality problems, especially for the small size of 3mm, such as circular and oval-shaped LED.

3, the value of the current design

The nominal LED current is 20mA, the largest of its general recommendations for the current use of no more than 80% of the nominal value, especially for the small screen pitch point, because of poor conditions of heat, but also reduce the current value.

In the light of experience, as the red, green and blue LED rate of decay of the inconsistency, the targeted reduction in the blue and green LED's current value, in order to maintain the use of display screen for a long time after the white balance of consistency.

4, mixed light

With a color different from the profile LED brightness need to mix lights, or in accordance with the law of discrete design of the lamp plug inserted map lights, to ensure that the entire screen brightness of each color consistency. This process if something goes wrong, there will be partial screen brightness inconsistencies, a direct impact on the LED display shows the results.

5, control lights verticality

For in-line LED, when the furnace should have been enough to guarantee LED technology perpendicular to the PCB board. Any deviation will affect the set up has been good LED brightness consistency, appear inconsistent brightness of color.

6, thermal design

LED work will be fever, high temperature will affect the LED's speed and stability of the attenuation, the cooling of the PCB board design, the box will affect the design of ventilation cooling LED.

7, control of Xuhan

LED display in the event of non-LED light, often more than 50% probability of various types caused by Xu Han, such as the LED Xu Han-pin, IC Xu Han-pin, the pin row Xu Han mother, and so on. These issues need to improve the process strictly to improve and enhance the quality of testing to resolve. The factory vibration test also may be a good test.

8, driver circuit design

Display module on the driver IC drives the circuit board arrangement will also affect the brightness of the LED. As the driver IC output current in the on-board PCB transmission distance too far, will make the path transmission too much pressure drop and affect the normal voltage LED lead to lower its brightness. We often find that around the modules of the LED display brightness lower than in the middle is for this reason. Therefore, to ensure that the brightness of the display consistency, it is necessary to design a good drive circuit map.

These are the choices from the point of introduction and use of a special full-color LED display relevant knowledge, full-color LED display is a system integration products, and manufacturers need to package LED display applications in close collaboration with manufacturers to strengthen technological exchanges. China has now become the world's manufacturing center of LED displays, LED display manufacturers is to move closer to power. So far, China's full-color LED use of the standard package has been significantly improved, a lot of indicators have been close to the level of Japanese manufacturers, has gone beyond the individual indicators, which will greatly promote the cause of China's LED display.


Reference link: http://www.17led.com/LEDdisplay/2008-06/105.html