Fine-pitch LED screens are mainly used in commercial fields, such as corporate meeting rooms, chairman's offices, online video conferencing, and information display needs in schools and educational institutions. Their high brightness, seamless design, lightweight and flexible nature, and small installation footprint are all attractive features. However, several irreconcilable contradictions still exist in current fine-pitch LED displays. If these contradictions are not properly resolved, they will significantly affect the user experience of LED displays. The following examples illustrate this:
1. Reduced Brightness and Grayscale Loss:
One of the most significant differences between indoor and outdoor display applications is the variation in ambient light. When LED displays are used outdoors, the intensity of sunlight during the day is very high, so outdoor LED displays need to be very bright! In fact, to achieve good display results outdoors, the brightness of the LED display needs to reach 4000 cd/m² (luminous brightness per unit area). Indoors, the brightness of a full-color LED display needs to be around 800 cd/m² (candelas per square meter) to ensure normal operation. However, studies have shown that a brightness between 120 cd/m² and 150 cd/m² provides a good compromise between health and visual effects. Furthermore, unlike passive light sources, LEDs are self-luminous display technology, and the human eye is more sensitive to direct light sources, thus requiring lower brightness for comfortable viewing.
Therefore, when LED displays are used indoors, their brightness needs to be appropriately reduced to meet the needs of indoor display. However, when the display brightness is reduced to 500 cd/m² or even 600 cd/m² and below, the image begins to show noticeable grayscale loss. With further reduction in brightness, the grayscale loss becomes even more severe (generally, the higher the grayscale level, the richer the colors displayed on the screen, and the more delicate and vibrant the image. Grayscale is a determining factor in the number of colors displayed. For the LED display industry, high grayscale screens provide a more realistic color aesthetic). When the brightness is reduced to below 200 cd/m², most displays experience significant grayscale loss, and the image quality becomes almost "unbearable," with a large amount of detail missing. 2. Improved Picture Quality and Increased Pixel Defects:
The image on an LED display screen is composed of countless small LED light beads. Therefore, the fineness of the picture quality is determined by the pixel pitch (or density) of the light beads. The more LED light beads per unit area, the higher the definition of the LED screen, and the richer the display of image details. Based on this, current LED displays are developing towards smaller pixel pitch and mini-LED display technologies.
However, due to technical limitations, LED displays are prone to pixel defects. Generally, the standard for dead pixels in outdoor LED displays is one to three per ten thousand. However, for small-pitch LEDs, a defect rate of three per ten thousand is almost unacceptable for daily use. Taking a P2.5 small-pitch LED display as an example, it has 160,000 light beads per square meter; if the pitch is further reduced to 1 millimeter, there will be 1 million light beads per square meter. At this point, if the standard is "no more than 3 defective pixels," the number of defective pixels in a small-pitch LED display would be countless; and a large number of screen defects would lead to a very unpleasant viewing experience.
3. Close-Range Viewing and Severe Heat Generation:
As an indoor display device, especially for products positioned as display platforms for small and medium-sized conference rooms, viewers usually watch and use the screen at close range. Taking a typical conference display scenario as an example, the conference host and participants are approximately 1.5-5 meters away from the screen.
However, the luminous efficiency of LED displays is very low. Studies have shown that in the energy conversion process of LED screens, the luminous efficiency of LEDs is only 100 lm/W, and their electro-optical conversion efficiency is only about 20-30%. That is, only about 20-30% of the input electrical energy is converted into light energy, while the remaining 70-80% of the energy is consumed in the form of heat radiation. In contrast, the incandescent lamps commonly used in the past could convert almost all the input electrical energy into light energy radiation. Therefore, LED displays generate a significant amount of heat. LED screens that generate excessive heat over extended periods can raise the overall ambient temperature (even with air conditioning and other cooling systems, the heat radiated from the screen during prolonged operation can still cause discomfort). For meeting participants, during a meeting lasting one to two hours or even longer, those sitting near the severely overheating screen will experience an uncomfortable, almost scorching sensation. Even those sitting further away will find it difficult to maintain a positive attitude after enduring prolonged exposure to the stifling heat, even if they don't end up sweating profusely like ants on a hot plate.
