在傳統(tǒng)照明系統(tǒng)中使HB發(fā)光二極管變暗的挑戰(zhàn)

　　在傳統(tǒng)照明系統(tǒng)中使HB發(fā)光二極管變暗的挑戰(zhàn)

　　在交流線路供電的電路中用二極管代替電阻通常是一個容易造成災(zāi)難的方法，但這正是設(shè)計師們試圖用現(xiàn)代高亮度LED技術(shù)取代白熾燈所面臨的嚴峻挑戰(zhàn)。從崔vled15系列是專為解決傳統(tǒng)LED照明裝置整合的挑戰(zhàn)。

　　近年來，高亮度LED已經(jīng)有了很大的發(fā)展，被許多人認為是最有可能取代白熾燈的技術(shù)。有一些很好的理由接受這種觀點。相比于競爭對手的技術(shù)，如緊湊型熒光燈、高亮度發(fā)光二極管能提供同等或更高的發(fā)光效率，沒有處理復(fù)雜的汞，可以提高他們的性德光效率，具有更長的使用壽命，并有潛力，大大簡化了驅(qū)動的要求，特別是在應(yīng)用中，可調(diào)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.