Patent ID: 8138679

Claim:
A light emitting device having a plurality of lamps and operable to maintain normal operation after the occurrence of a low-voltage error in one or more of the lamps, the device comprising: a control power source circuit coupled to a commercial alternating-current power source and operable to generate a control direct-current voltage; a step-down chopper circuit coupled to the control power source circuit and further comprising a switching element; a lamp current detecting circuit; a control circuit operable to receive the control direct-current voltage from the control power source circuit and to output a control signal to the switching element of the step-down chopper circuit, wherein the control signal drives the switching element and supplies power to the lamps; and a direction inverting circuit comprising a plurality of pairs of switching elements connected in parallel, each pair connected in series between the positive and negative poles of the power supply, the direction inverting circuit further comprising the plurality of lamps, each lamp connected between one pair of switching elements, wherein the direction inverting circuit is operable to control the plurality of switching element pairs and apply a reverse voltage to lamps in which a low-voltage error has been detected, and further operable to apply a forward voltage to lamps in which a normal state has been detected.