Patent ID: 8648847

Claim:
An Light Emitting Diode (LED) driving apparatus that drives an LED module having at least one LED, comprising: a power feed unit that feeds direct current power to the LED module; a driving control unit that performs driving control of the power feed unit; a current detection unit that detects load current flowing in the LED module; and an output control unit that determines whether the LED module is under conducting state or opening state in accordance with a detection result of the current detection unit, and outputs a signal to the driving control unit in accordance with a result of the determination to thus control an output from the power feed unit, wherein, when the LED module is under conducting state, the output control unit outputs a first signal to the driving control unit so that the load current is constant when a voltage is applied to the LED module by the power feed unit, wherein, when the LED module is under opening state, the output control unit outputs a second signal to the driving control unit so that a voltage, which is applied to the LED module by the power feed unit, becomes a predetermined constant-voltage value, wherein the predetermined constant-voltage value is at least a voltage value at which the LED module starts conduction, and at most a voltage value corresponding to an upper limit of the load current when the LED module is under conducting state, wherein the output control unit has a constant-current control unit that performs constant-current control and a constant-voltage control unit that performs constant-voltage control, wherein, when the LED module is under conducting state the constant-current control unit performs the constant-current-control based on a comparison result of a voltage corresponding to the load current detected by the current detection unit and a first reference value that is a reference voltage for generating the first signal, and wherein, when the LED module is under opening state, by using: a voltage corresponding to the load current detected by the current detection unit; a voltage based on an output voltage of the power feed unit; a second reference value that is a voltage for generating the second signal; and an opening state detecting signal from the constant-current control unit, as inputs, the constant-voltage control unit generates a third reference value, based on the second reference value and the opening state detecting signal, and outputs the second signal based on a comparison result of the voltage based on the output voltage of the power feed unit and the third reference value, and thus the constant-voltage control unit performs the constant-voltage control on the output voltage of the power feed unit.