In today's rapidly developing society, the application of outdoor LED screens is becoming increasingly widespread. However, inconsistent quality leads to frequent accidents. So, how do we judge the quality of outdoor LED screens?
In LED displays, the most crucial component is the LED chip. The quality of the chips directly affects the overall quality of the LED display. LED chips are the most numerous key components used in a full-color screen, with thousands to tens of thousands used per square meter. The chips are also the main determinant of the overall optical display performance, directly influencing the viewer's evaluation of the display. Chips also account for the largest proportion of the overall cost of the display, ranging from 30% to 70%. Their importance is immediately apparent.
In the LED display field, brightness is one of the most important indicators. With high brightness requirements, heat dissipation becomes a major issue. Heat dissipation has been a long-standing problem in the LED field, whether for lighting or displays. Major manufacturers have launched their own heat dissipation solutions, declaring that the heat dissipation effect of their products has become a key performance indicator. Another reason is that with the development of small-pitch LEDs, the junction temperature problem remains difficult to solve.
So, how do we distinguish the quality of LED display chips?
First: Check the brightness, which is what people usually refer to as the LED's brightness in lumens (LM). LM is the unit for measuring the brightness of an LED.
Second: Check the uniformity and consistency of the light emission. High-quality LEDs emit light evenly and with consistent color. Poor-quality LEDs will have uneven brightness, with some LEDs being brighter than others, and the color will be inconsistent and messy, with obvious dark areas.
Third: Check the chip and its size. The chip is a decisive factor in the quality of the LED. Generally, the larger the chip, the stronger the stability, the higher the brightness, and the better the heat dissipation.
Fourth: Check the adhesive and phosphor. Good products usually use imported adhesive. A well-sealed LED will not deform when pressed by hand. Cheap adhesive will deform or even crack when pressed.
Fifth: Check the bracket. Generally, the bracket is made of silver-plated red copper. The advantage of silver-plated red copper brackets is that they dissipate heat quickly, better heat dissipate heat for the LED, and have low resistance. Some vendors in the market use ceramic brackets instead of silver-plated copper brackets because ceramic brackets have excellent thermal conductivity.
Sixth: Examine the packaging process. High-quality LED chips have uniform color and good colloid consistency. This relies heavily on good machinery and equipment. Good production equipment is a crucial factor; it ensures the stability and consistency of the product at each stage, guaranteeing a high yield rate.
However, the most important factor is the LED chip itself. The chip directly determines the color rendering index, brightness, and resistance to light decay.
At high junction temperatures, light decay is severe. The substrate is the first point of contact with heat, and its thermal conductivity directly determines the junction temperature. Currently, some major manufacturers have begun using new ceramic substrate materials.
Ceramic substrates currently offer the best heat dissipation on the market, surpassing aluminum, silicon, and sapphire substrates in both thermal conductivity and stability. Currently, there are two main types of ceramic substrates: aluminum nitride and aluminum oxide. Aluminum nitride has a thermal conductivity of 170 W/(m·K) to 230 W/(m·K), which is more than twice that of aluminum oxide substrates. With this high thermal conductivity, LED chips do not generate junction temperature at all, thus eliminating heat dissipation issues.