Patent ID: 8358257

Claim:
An operating system of a light emitting device comprising: a light emitting diode package comprising: a light emitting diode chip; and a heat sink thermally connected to the light emitting diode chip, the heat sink comprising a metal; and a driving unit to drive the light emitting diode package at frequency equal to or higher than 100 Hz, the driving unit performing a duty operation, wherein the frequency is configured to decrease an operational temperature of the light emitting diode chip, and wherein the driving unit is configured to estimate a junction temperature of the light emitting diode chip within 10% of an error range, and wherein the junction temperature T of the light emitting diode chips is estimated by a formula, T=T a +(R LED package +R external heat sin k )×W×duty, where T a is ambient temperature, R is thermal resistance, and W is heat discharge of the light emitting diode chips.