Thermal design of LED display
High temperature can cause electronic components failure probability increase rapidly, thus resulting in a decline in the reliability of the LED display. In order to control the temperature of the LED display the internal electronic components, in the LED display working environment conditions, the allowable temperature shall not exceed the stipulated, the need for thermal design of LED display. LED display thermal design, how to low cost and high quality, is discussed in this paper.
A related knowledge, heat dissipation design
Heat transfer of the two basic rules: heat from high to low temperature zone; High temperature heat is equal to the area to absorb heat at low temperature.
Heat transfer there are three basic ways: heat conduction, convection and radiation.
Thermal conductivity, gas heat conduction is the result of the irregular movement of gas molecules colliding. Thermal conductivity of the metal conductor is mainly completed by free electron movement. The thermal conductivity of conductive solid is achieved by the vibration of the lattice structure. The heat conduction mechanism of liquid depend mainly on the effect of elastic wave.
Convection: refers to the fluid when the relative displacement between the parts caused by the heat transfer process. Convection occurs only in the fluid, and with the phenomenon of thermal conductivity. When the fluid flows through a surface heat exchange process, what has happened is called the convective heat transfer. From all parts of the cold and hot fluid density different convection caused by natural convection. If the fluid movement caused by external forces (such as fan), is called forced convection.
Radiation: objects in the form of electromagnetic wave transmission ability of process called thermal radiation. Radiant energy transfer in the vacuum energy, and a form of energy conversion, that is transformed into radiant energy, and radiation thermal energy is transformed into heat energy.
Choosing the cooling way, should consider the following factors: the heat flux LED display, power density, total power consumption volume, surface area, volume, work environment conditions (temperature, humidity, air pressure, dust, etc.), etc.
According to mechanism of heat transfer, have natural cooling, forced air cooling and liquid cooling directly; Evaporative cooling; Thermoelectric refrigeration; Heat pipe heat transfer and thermal radiation.
Natural cooling forced air cooling liquid cooling direct evaporative cooling
Heat capacity W/cm? (temperature of 40 ) 0.040.30.61.1
Easy is difficult difficult
High school low weight or volume
Low noise or vibration no discretion
No high and low power consumption is low
In the low cost high
Easy maintainability is easier to more difficult problems
You can see from the table above, the natural cooling of the cooling effect is relatively small, evaporative cooling of the cooling effect is larger. The body sweat to cool, with is evaporative cooling of the cooling method.
Second, the LED display design method of heat dissipation
From the practical application shows that the LED display internal fever, fever more electronic components are: LED, driving IC, switching power supply. Therefore, need to thermal design of LED display, between the heat source and the external environment to provide a low thermal resistance pathway, ensure heat transfer out.
Object temperature below 1800 , meaningful thermal radiation wavelength lies between 0.38 ~ 100 microns, and most of the energy in the infrared band 0.76 ~ 20 microns, within the visible spectrum, thermal radiation energy proportion is not big. Therefore, all sorts of color LED display can internal coating. The sun was shining in the LED display outside, need to Shanghai juji into light, avoid the visible absorption.
Considering from the usage of LED display, rental screen, indoor fixed installation screen use natural cooling cooling method, fixed installation screen is multi-purpose outdoor method of forced air cooling heat dissipation.
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