Patent ID: 8471491

Claim:
A method for operating an AC light-emitting diode (LED), adapted for predicting a driving voltage of the AC LED as the AC LED is driven by a predetermined driving current, comprising: applying a first driving voltage to the AC LED for measuring a first driving current; applying a second driving voltage to the AC LED for measuring a second driving current; and applying an interpolation in accordance with the first driving voltage, the first driving current, the second driving voltage, the second driving current, and the predetermined driving current so as to calculate a third driving voltage, wherein the third driving voltage is the predicted driving voltage of the AC LED when the AC LED is driven by the predetermined driving current, and the interpolation is performed according to an equation as follows: V ⁢ ⁢ rms = Vf ⁢ ⁢ 1 + ( Vf ⁢ ⁢ 2 - Vf ⁢ ⁢ 1 ) × ( I ⁢ ⁢ rms - If ⁢ ⁢ 1 ) If ⁢ ⁢ 2 - If ⁢ ⁢ 1 , in which Vrms is the third driving voltage, Vf 1 is the first driving voltage, Vf 2 is the second driving voltage, Irms is the predetermined driving current, If 1 is the first driving current, and If 2 is the second driving current.