在传统照明系统中使HB发光二极管变暗的挑战

　　在传统照明系统中使HB发光二极管变暗的挑战

　　在交流线路供电的电路中用二极管代替电阻通常是一个容易造成灾难的方法，但这正是设计师们试图用现代高亮度LED技术取代白炽灯所面临的严峻挑战。从崔vled15系列是专为解决传统LED照明装置整合的挑战。

　　近年来，高亮度LED已经有了很大的发展，被许多人认为是最有可能取代白炽灯的技术。有一些很好的理由接受这种观点。相比于竞争对手的技术，如紧凑型荧光灯、高亮度发光二极管能提供同等或更高的发光效率，没有处理复杂的汞，可以提高他们的性德光效率，具有更长的使用寿命，并有潜力，大大简化了驱动的要求，特别是在应用中，可调光的光源是必需的。

　　The compatibility problem

　　One of the more significant factors supporting the incumbency of incandescent lighting， however， is an inherent incompatibility between LED technology and most currently installed dimming controls.

　　The operational concept of the basic phase control dimmer circuit as shown in Figure 1 is quite simple; R1 and R2 compose a variable resistance of known minimum value， which causes the voltage waveform across C1 to lag behind the source voltage waveform to a varying degree， as determined by the RC time constant thus formed. When the voltage across diac Q1 exceeds the device’s breakover voltage as a result of this phase shift， the device enters its conduction mode， allowing C1 to discharge through TRIAC Q2’s gate terminal， thus triggering it into conduction. When the current through Q1 and Q2 falls below their respective holding currents， the devices commutate， returning to their high-impedance states， until the process begins anew， which typically happens once per every half-cycle of an AC waveform. Through this process， the circuit of Figure 1 permits truncation of the leading edge of each half-cycle of the AC waveform， resulting in a reduction of the RMS voltage applied to the load to a degree that corresponds to the setting of R2.