Method for operating AC light-emitting diode
View Patent ↗A method for operating an AC LED is disclosed. The method operates with an assumption that a linear relationship exists between the voltage and current of the AC LED operating at an active region. Hence, a first driving voltage and a second driving voltage are applied to the AC LED for respectively measuring a first driving current and a second driving current, and an interpolation is used for obtaining a third driving voltage. The third driving voltage is the predicted driving voltage for the AC LED. The method is capable of determining the actual driving voltage precisely and rapidly before the follow-up tests for other AC LEDs may proceed.
1. 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.
2. The method for operating the AC LED according to claim 1 , wherein the first driving voltage, the second driving voltage, and the third driving voltage are AC voltage signals and the first driving voltage and the second driving voltage are set to upper and lower specification limits of the AC LED.
3. The method for operating the AC LED according to claim 1 , wherein the first driving current and the second driving current are AC current signals and the first driving current and the second driving current passing through the AC LED are of non-sinusoidal waveforms.
4. The method for operating the AC LED according to claim 1 , further comprising applying the third driving voltage to the AC LED.
5. A method for operating an AC 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;
calculating a slope of voltage/current characteristic curve in accordance with the first driving voltage, the first driving current, the second driving voltage, and the second driving current; and
calculating a third driving voltage in accordance with the slope, the first driving voltage, the first driving current, and the predetermined driving current, wherein the third driving voltage is the predicted driving voltage as the AC LED is driven by the predetermined driving current, and the third driving voltage is calculated according to an equation as follows:
Vrms
=
Vf
1
+
(
Vf
2
-
Vf
1
)
×
(
Irms
-
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, and Irms is the predetermined driving current while If 1 is the first driving current, If 2 is the second driving current, and (If 2 -If 1 ) /(Vf 2 -Vf 1 ) is the slope.
6. The method for operating the AC LED according to claim 5 , wherein the first driving voltage, the second driving voltage, and the third driving voltage are AC voltage signals and the first driving voltage and the second driving voltage are upper and lower specification limits of the AC LED.
7. The method for operating the AC LED according to claim 5 , wherein the first driving current and the second driving current are AC current signals and the first driving current and the second driving current passing through the AC LED are of non-sinusoidal waveforms.
8. The method for operating the AC LED according to claim 5 , further comprising applying the third driving voltage to the AC LED.