|In the hot summer, LED display should pay attention to heat dissipation|
The biggest problem that LEDs currently encounter is heat dissipation, and outdoor the LED display is the same. The power consumption of LED displays is very large, and a considerable part of the energy is wasted on heat, which causes many problems. Why LED displays can be widely used, my summary is the following:
1. Extensibility: The larger the LCD screen is, the higher the investment in the production line equipment. The increase in the size of the LED display is very easy, just like building blocks. The resolution is also convenient to implement according to user needs.
2, full color: light bulbs, neon lights, etc. are all monochrome, LEDs achieve a combination of RGB three primary colors.
3, high reliability: LED is solid lighting, high reliability, unlike neon tubes, bulbs and the like need vacuum tubes.
4, long life: LED chip theoretical life can reach 100,000 hours, the actual service life is more than 30,000 hours.
5, environmentally friendly: LED itself is energy-saving and pollution-free products.
LED display fever will bring the following problems:
1. Wavelength shift: Wavelength drift will cause problems in color correction. When the LED is at low temperature and high temperature, the wavelength drift is relatively large. According to the experimental data, the wavelength changes by 0.2-0.3 nm for every degree of temperature change.
2, the output brightness is reduced: the temperature change per degree Celsius causes a change in 1% output brightness, of which the red light is most affected. From -40 degrees 180% brightness, to 120 degrees brightness less than 50%, that is, the red light brightness is reduced by nearly two-thirds. Relatively speaking, the brightness of the blue and green lights is not as strong as the temperature, especially the blue light. A problem arises when the temperature rises, and the brightness of the LEDs of different colors is different.
3. Temperature rise leads to shortened LED life: According to a laboratory data in the United States, the junction temperature is raised from 63C to 74C, and the LED lifetime is reduced from 36,000 hours to 16,000 hours.
4. Excessive heat dissipation components result in increased system cost.
5. Waste energy and increase user costs.
So where does the heat come from? From power supply to LED light, to LED drive, to adjustable resistance, the heating part includes LED light, LED drive, LED cable. Let's take 5V power supply as an example:
Power supply voltage: 5V,; LED: LED G/B Vfwd=3.2V, LED R Vfwd=2V
1, LED luminous efficiency is about 20%, LED heating accounts for 50% of total heating
2, the controller and the connection line accounted for about 5% of the total heat
3, the driving pressure drop: 1.8V (G / B) or 3V (R) pressure drop, driving part of the heat accounted for more than 45% of the total heat.
The heating of the LED lamp needs to improve the luminous efficiency of the LED, and the heat generated by the controller and the connecting wire is less, and the improvement space is not large. The heating part of the driving part has a lot of room for improvement, and it is also part of what we expect to improve.