US Patent 7777421 Light emitting device

An object of the invention is to suppress the amount of heat generated by a light emitting diode and prevent the light emitting diode from being overheated without reducing the amount of emitted light even when the light emitting diode is a high-power light emitting diode. A light emitting device is configured so that one or more light emitting diodes (11) are lighted by a lighting circuit (12). A DC power is converted into a pulse power by a switching regulator (13) of this lighting circuit (12) and the voltage of a pulse power converted by this switching regulator is lowered by an output control portion (14). The pulse width of a pulse power lowered in voltage by this output control portion is adjusted by a pulse width adjusting oscillation means (16), and the current of a pulse power adjusted in pulse width by this pulse width adjusting oscillation means is limited by a limiting resistor (17). The light emitting device is configured so that a pulse power limited in current by this limiting resistor is outputted to a light emitting diode.