At present, there are still some technical problems to be solved in the development and promotion of LED home lighting, mainly the temperature compensation, luminous uniformity, light decay, glare, stroboscopic effect and thermal management of high-power LEDs (including heat dissipation design and temperature control, thermal analysis and Thermal simulation), white LED arrangement and light distribution. Below we mainly talk about the temperature compensation and glare of high-power LEDs.
Temperature compensation for high power LEDs
As mentioned above, high-power LED lights generally use a constant current driver. But this is not the best design. Because the output current of the constant current driver does not change with temperature. When the ambient temperature of the LED is high: at the safe operating point temperature, the forward current will exceed the safe zone, which will greatly reduce or even damage the life of the LED; the solution is to reduce the forward current value of the LED. Effectively prevent the LED temperature from rising continuously, instead of maintaining the forward current constant, this technical problem has not yet received sufficient attention in China.
An effective solution is to add temperature compensation to the LED driver. The principle is that the LED driver detects the ambient temperature of the LED through a negative temperature coefficient thermistor (NTCR). As long as the safe operating point temperature is exceeded, the output current is automatically reduced to ensure that the LED operates in a safe zone; when the temperature is reduced to safety In the area, the output current of the LEn actuator automatically returns to normal. Temperature compensation technology is important to prevent LED from overheating and damage it.
Glare
Glare is caused by excessive brightness or excessive brightness change, which makes people feel irritated and uncomfortable. Because each white LED chip has a high brightness, the light-emitting area is small, similar to a point source, and it does not emit a complete, continuous visible spectrum like sunlight. Therefore, it is easy to produce glare. Although the glare can be avoided by using a frosted astigmatism lampshade, the illuminance of the perceived light is significantly reduced. The dimming technology can better solve the above problem, that is, adjusting the brightness level of the LED lighting (or backlight) by monitoring the brightness of the external environment. To achieve anti-glare purposes.
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