Discussion on the suitability of small-pitch LED display in the control room
Small-pitch LED screens have appeared as superstars in indoor commercial displays and conference rooms in recent years. Use the posture of a strong player to further capture the application of the control room. Dazzling colors and a seemingly seamless large screen are perfectly applied in the control room, which amazes the first-time observers. Next, let’s examine it from a technical point of view: Are small-pitch LEDs suitable for subdivided application control rooms?
Large-screen usage scenarios in the control room
●The information display in the control room is required to be point-to-point without scaling, and no dead pixels are allowed
The control room is mainly for big data information display, not for general video or image display, so it is necessary to clearly display each pixel. Therefore, in the application process of the control room, if the display screen has dead pixels, it will not be recognized as a professional product.
In the control room, the scale of the number of display screens can be composed of dozens to hundreds of projection boxes. For the application of 10 full HD screens, the number of small-pitch LEDs will be composed of 20 million RGB LEDs, which is a huge number of components. In the theory of system reliability, each component has its own damage probability, and the reliability is poor if the number of components is large. According to this theory, we can predict that the probability of dead lights of small-pitch LED screens is very high. At present, the Chinese government stipulates that the acceptable dead light rate of outdoor LED screens is between 1/10,000 and 3. This one-ten-thousandth cannot be used in the control room at all. If it is assumed that indoor small-pitch LEDs have ten times better reliability, it can only reach one in 100,000. Judging from the number of 20 million LEDs, there is a probability of nearly 200 dead lights in the whole area, which is unbearable in a professional control room. In the DLP projection splicing large-screen industry, the specifications of the DMD components manufactured by Ti are free of dead pixels.
– 7×24 uninterrupted operation of the control room throughout the year
7×24 operation puts a lot of pressure on display devices, so the requirements for device reliability are particularly high. Compared with commercial displays, there is at least a shutdown break every day, which allows the equipment and components to release pressure. Therefore, equipment suitable for commercial use may not be able to withstand the test of 7×24 use.
For example, the narrow-edge LCD display, the original factory recommends that it should not be used for more than 20 hours a day, and the components must be rested to release the pressure and reduce the degradation rate of the screen. However, DLP has been used in control rooms for more than two decades and has passed the rigorous 7×24 test. However, the time for the small-pitch LED screen to be launched and applied in the control room is not long enough, and whether it can withstand the test of the whole year remains to be verified by time.
●The staff in the control room watch the big screen for a long time
The interaction between the staff and the large screen needs to be watched for a long time, so there are special requirements for the display screen. The picture quality must be soft, without glare, and the brightness should not be too bright to protect the health of the eyes.
The seamlessness of the small-pitch LED screen is not magic. In fact, it is full of seams, but the uneven seams cannot be seen when splicing. It is a very small luminous duty ratio (the luminous point only accounts for about 1/10 of the area of the component), in exchange for the seemingly seamless splicing, and its side effect is obvious graininess. It is easy to feel uncomfortable visually, and it is not suitable for close viewing.
The visual effect of the small-pitch LED screen is different from the DLP projection effect, which is obviously glare, and the brightness is not easy. If the LED brightness is lowered, there will be ghosts, dark lines in the first line, low gray color cast, low gray unevenness, gradient dark lines and other bad visual effects. Watching for a long time every day and for a long time, the impact on the human eye remains to be seen.
Control room applications emphasize the amount of information. It is necessary to see all the displayed information at a glance and make quick decisions, so the size of the display screen and the number of image points are the required specifications. Scaling cannot be used to force high-quality information onto a lower-resolution display. However, at present, the number of pixels of the small-pitch LED screen is not consistent with the signal source, and the signal will be scaled.
●With the same pixel resolution, the installation cost of DLP video walls is lower
There is no technical difficulty in achieving the same resolution as DLP for small-pitch LED screens. But we need to examine its commerciality from a cost perspective. The price of a DLP full HD 70″ cabinet is about RMB 80,000-100,000. This year, the price of a P1.9 small-pitch LED screen on the Internet is about RMB 30,000 per square meter. It is estimated that if the same resolution as DLP is to be achieved, the estimated cost will be higher. It costs 220,000 RMB, which is about 2.2-2.7 times. The area requirement is 5.5 times that of DLP. That is to say, in addition to the increase in cost, there must be a larger space for installation, and the increased cost is even greater
Everyone thinks that the price decline of small-pitch LED screens can be expected, is that so
The cost of led screen manufacturer screen can be divided into material and labor costs. The cost of LED monomers and SMTs accounts for the vast majority. From the perspective of LED, according to upstream component manufacturers, there is almost no profit, and it is difficult to reduce prices and continue to spend money on new component development. If the components are further reduced, the yield rate will decrease and the cost will increase. The other is the placement cost, which is a labor cost. When the labor cost is rising, it is almost impossible to have room for price reduction. Therefore, the expected price reduction dividend can only be released from the profits of small-pitch LED screen manufacturers
●Small-pitch LED screens require high maintenance cost
Installation and maintenance costs are another key consideration when choosing different technology products. Many users choose products and ignore their maintenance costs in the future. The funds can only be used in a damaged state, or even abandoned, which is completely out of shape from the original plan
Small-pitch LEDs, according to the current process technology, even large foreign manufacturers are divided into multiple groups of Bins for delivery, and the number is as follow
-Color Bin R =1, G = 5, B=3 (the eyes of the same color bin can still distinguish the difference)
– Luminance Bin R=4, G=4, B=4
– In total, there are 5x3x1x4x4x4= 960 Bins for RGB LEDs
During production, it is necessary to select close Bin groups, and use a point-by-point correction method to even out the LED screen. But in the future, it is very easy to cause blurred screen. The physical reason is: the different display screens lead to different LED working currents, resulting in different attenuation rates. In order to maintain a professional uniform picture, stop correction must be done frequently. In addition, due to the inevitable dead lights, the frequency of maintenance and replacement will not be less. These are maintenance costs. Generally, it is easy for users to obtain construction funds, but it is difficult to list maintenance costs, which is quite troublesome
Small-pitch LED screens are everywhere, but they have special usage scenarios in the control room market segment. From the perspective of component reliability, visual effects, initial installation costs and future maintenance costs, small-pitch LED screens are obviously not so suitable for 7 /24’s control room.
