What are the benefits of cooling and cooling for LED displays?
Whether it is an indoor LED screen or an outdoor LED full screen, the heat generated in the process will lead to a rise in the temperature of the LED display. Normally, indoor LED displays can naturally dissipate heat due to low brightness. However, the outdoor LED advertising screen, due to its high brightness and heat, needs to be cooled by air conditioning or axial fan. Since the LED display belongs to the electronic products, the temperature rise will affect the light failure of the LED display lights, the work efficiency of the driving IC and the life of the LED display.
Led display is very promising because of its advantages such as energy saving, environmental protection and long life. But temperature is important for led displays, and the temperature affects the led display: the life span of led displays, the light effect, color, etc. So the right temperature is critical to the led display.
The impact of temperature on led displays is as follows:
A high temperature can lead to the complete destruction of led display
(1) the working temperature of the led screen will exceed the bearing temperature of the chip, which will reduce the luminous efficiency of the led display, resulting in obvious light failure and damage.
(2) led display in a transparent epoxy resin encapsulation, more if the junction temperature more than solid phase transition temperature is 125 ℃ (usually), the packaging materials will surge to rubber shape and thermal expansion coefficient, resulting in led display open and failure.
Higher temperature will shorten the life of led display
The life of the led screen is reflected in its light decay, which is the length of time, and the brightness becomes lower and lower until the end is extinguished. It is usually defined that the light flux of an led display is reduced by 30 years.
There are several reasons for the light failure of led displays:
(1) the flaws of the led display chip inside the material at a higher temperature when rapid proliferation, reproduction, and invasion light-emitting area, forming a lot of the radiative recombination centers, severely reduce the luminous efficiency of led display. In addition, under the condition of high temperature, micro defects within the material and the fast expansion of impurity from the interface and panels will also introduce the light emitting area, to form the deep level, will also accelerate the droop of led display device.
(2) when high temperature, the transparent epoxy resin will be modified and yellowed, which will affect the light transmission performance. The higher the working temperature will be, the faster the process will be carried out. This is another major reason for the light failure of led displays.
(3) phosphors of phosphors are also a major factor in the decline of led display, because the attenuation of phosphor powder in high temperature is very serious.
Therefore, the high temperature is the main source of led display's light failure, shortening the life of led display screen.
The light and decline of led displays are different in different brands. Usually, led display manufacturers will give a set of standard light - failure curves. Led display is not reinstable, led display has no unrecoverable optical flux before fading, which is called the "initial flux" of led display.
3. Rising temperature will reduce the luminous efficiency of led display
The reasons for the effect of temperature on led display are as follows:
(1) when the temperature rises, the concentration of the electron and the hole will increase, the forbidden band width will decrease, and the electron mobility will decrease.
(2) temperature rise, the radiation compound chance of the electron and hole in the potential well is reduced, resulting in non-radiation composite (generating heat), thus reducing the internal quantum efficiency of led display.
(3) temperature lead to blue chip peaks shift towards long wave, make the emission wavelength of chips and excitation wavelength of phosphor do not match, can cause the white light led display external light extraction efficiency lower.
(4) as the temperature rises, the quantum efficiency of phosphor powder decreases, and the external light extraction efficiency of led display is reduced.
(5) the performance of silica gel is greatly affected by ambient temperature. As the temperature rises, the thermal stress inside the silica gel increases, causing the refractive index of silica gel to decrease, thus affecting the light effect of led display.
4. Influence of temperature on the luminous wavelength (light color) of led display
The luminous wavelength of led display can be divided into peak wavelength and main wavelength. The peak wavelength is the maximum wavelength of light, and the dominant wavelength can be determined by X and Y color coordinate, reflecting the color perceived by the human eye. Obviously, the change in the wavelength of led display led by the temperature of the led display will directly cause the human eye's different feelings towards the light-emitting color of the led display. For an led display device, the band width of the material in the luminescent area directly determines the wavelength or color of the device. As the temperature increases, the band width of the material will decrease, leading to the longer wavelength of the device and the red shift of the color.
5. Excessive temperature will limit the maximum injection current of led display
The above points are the introduction of the influence of temperature on led display. The above introduction shows that the influence of temperature rise on led display screen is very large. So proper, proper temperature is very important for led display.
LED display when the choose and buy, should pay attention to choose LED display chip brands, packaging manufacturers, drive IC, switching power supply brand, brand is good or bad will affect the LED display itself product quality, and high degree of brand products, its itself produces less heat, also can better control the temperature of the LED display, so as to prolong the service life of the LED display.