Performance Analysis of Special SMD Devices for Outdoor Full Color SMD Display

LED display screens occupy the mainstream market for large-size indoor and outdoor displays with its high brightness, weather resistance and large size, while CRT, liquid crystal display (LCD) and plasma display (PDP) are small and medium-sized, indoors and near. The viewing market is dominated by the viewing market.

LED displays have gained a lot of applications in advertising, stage, public information display, sports transportation facilities and other fields of use. The LED display screen is divided into indoor, outdoor and semi-outdoor LED display according to the use environment; it is divided into monochrome screen, two-color screen and full-color screen according to the display color; according to the selected device, it is divided into digital dot matrix screen, in-line LED screen and SMD type SMD screen.

This article describes the emerging outdoor full-color SMD display and its dedicated SMD device performance.

First, the main advantages of outdoor full color SMD display

As we all know, outdoor LED displays all use in-line elliptical red, green and blue LED devices a year or two ago, and in the past two years, outdoor full-color SMD displays with pixel spacing of 8mm to 16mm are being It has gradually emerged and is widely used.

In the past, because the brightness of the patch SMD was low, and the waterproof, moisture-proof, and anti-ultraviolet functions did not meet the requirements of outdoor harsh environments, the outdoor full-color display is the world of in-line LED devices. Full-color SMD SMD displays can only be used in large numbers indoors. With the advancement of LED chip technology and LED packaging technology, SMD's brightness and protection level can meet the needs of outdoor applications, and full-color SMD display has more full-color in-line LED display is difficult to achieve. Advantages, so get a faster application.

The advantages of outdoor full-color SMD display compared to outdoor in-line elliptical LED display are as follows:

1. Wide viewing angle

The outdoor full-color SMD display not only has a wide viewing angle of 110 degrees in the horizontal direction but also a wide viewing angle of 110 degrees in the vertical direction, which is particularly advantageous in some applications.

2, good light distribution

Red, green, and blue elliptical LEDs are consistently difficult to match at three different brightness levels, while full-color SMDs are three-in-one because of the design structure. Red, green, and blue chips are all in the chip. Among the bracket cups, the matching consistency of the three brightnesses of red, green and blue at different angles is highly uniform, so that the brightness of the outdoor full-color SMD display at any angle is very good. Better color vividness.

Figure 1 and Figure 2 below show the outdoor full-color SMD light distribution curve and the outdoor full-color elliptical LED light distribution curve. It can be seen from the comparison that the light distribution consistency of SMD has obvious advantages over elliptical LED.

Figure 1. Outdoor full color SMD horizontal direction light distribution curve

Figure 2. Outdoor elliptical LED horizontal light distribution curve

3, good mixing

Because the design structure is three-in-one, the three chips are very close together, and the light is mixed in the same bracket cup instead of three discrete elliptical LEDs, so the red, green and blue mixed light effect is better than the straight elliptical LED. Screen, especially suitable for close-up viewing.

4, high contrast

Due to the three-in-one design structure, the full-color SMD is small in size, so the light-emitting area is small, and the black area is large, which improves the contrast of the LED display.

5, automated production

The SMD SMD can be automated with a fully automatic placement machine for high productivity. The circuit design of the full-color SMD display module can realize the combination of the light board and the driving board, which reduces the cost, improves the reliability and improves the production efficiency.

Automated patch production can also improve the vertical accuracy of SMD on the circuit board, and overcome the vertical accuracy problem of the in-line elliptical LED on the circuit board, thus ensuring better optical effects.

Second, the main parameters of outdoor full color patch SMD

1, brightness

At present, the brightness of outdoor full-color SMD SMD has been able to meet the brightness requirements of outdoor full-color SMD display with a dot pitch of 8mm to 16mm. The green brightness can reach 1200mcd to 1600mcd, and the whole screen brightness can be higher than 5000nits.

In order to ensure the consistency of the brightness of the whole screen, the brightness range of each color should be below 1:1.3, and the average brightness ratio of red, green and blue colors is about 3:6:1.

2, wavelength

The wavelength ranges of red, green and blue should not be wider than 5 nm, and the wavelength distribution of each color should be normally distributed.

3, attenuation

Outdoor full-color SMD SMD uses relatively high current due to brightness. Because it is used outdoors, in order to achieve minimum attenuation, it has higher requirements on chip size, heat dissipation design, waterproof and UV resistance. At the same time, the red, green and blue colors have a uniform brightness attenuation, which ensures that the SMD display not only has a small decrease in brightness after a long period of operation, but also maintains good brightness and color consistency. The high-quality outdoor full-color SMD SMD can guarantee that the red, green and blue attenuation is less than 5% after 3000 hours of operation, and the red, green and blue attenuation dispersion is less than +10%.

4, angle

The angle of the outdoor full-color SMD type generally requires that the horizontal direction and the vertical direction are both greater than 110 degrees.

5, waterproof and moisture-proof

The waterproof and moisture-proof performance of the outdoor full-color SMD SMD is a very important key parameter. The choice of SMD scaffold material and structural design determine the waterproof and moisture resistance. The new PPA materials, the use of silica gel materials and the design of new structures can solve the problem of waterproof and moisture. Waterproof and moisture-proof problems are not well solved, and problems such as failure, darkness, and rapid decay may occur. The high-quality outdoor full-color SMD SMD has a waterproof and dustproof rating of IP67 and a moisture-proof rating of Lever3.

6, UV protection

Due to outdoor use, the full-color SMD SMD bracket material and potting material are required to withstand UV rays. Non-UV-resistant SMD will appear yellowing of PPA and turbidity of the potting material, resulting in brightness decay and failure. The high-quality outdoor full-color SMD SMD should not be more than 5% after 10,000 hours of outdoor work.

7, failure rate

It is easy to fail under a number of factors. The quality of the outdoor full-color SMD SMD should be less than 50,000 (50ppm) in 3000 hours.

8, thickness

Outdoor full-color SMD SMD display takes into account the waterproof factor of the circuit board, and needs to be filled with waterproof glue below the SMD thickness. Therefore, the full-color SMD SMD needs a certain height, and the current mainstream thickness on the market is 2.5mm.

Third, the development trend of outdoor full color patch SMD display

In terms of brightness and cost, the traditional outdoor full-color in-line elliptical LED display has an irreplaceable advantage in pixel pitch of 20 mm and above. With the improvement of LED chip brightness and LED packaging technology, the gap between the price of outdoor full-color SMD and the elliptical LED has been reduced to 10% to 20%. The outdoor full-color SMD display has a wide viewing angle. With the advantages of good light distribution, good light mixing, high contrast and easy automation, its market share is expected to grow from less than 10% now to the same as outdoor full color in-line elliptical LED display.