Patent ID: 8362709

Claim:
A current balance circuit having a protection function, the current balance circuit comprising: a current balance unit configured to maintain current balance of lamp driving power supplied to a lamp unit including a plurality of lamps; and a protection unit configured to detect the lamp driving power supplied to the lamp unit from the current balance unit, cut off the lamp driving power after a preset time period when the lamp unit operates abnormally, and control a voltage level of the lamp driving power to a preset reference voltage level or lower during the preset time period, wherein the current balance unit comprises a plurality of current balancing transformers corresponding to the plurality of lamps on a one-to-one basis and configured to maintain the current balance of the lamp driving power, each of the current balancing transformers comprises: a primary winding configured to receive the lamp driving power and send the received lamp driving power to a corresponding lamp among the plurality of lamps; and a secondary winding electromagnetically coupled with the primary winding and electrically connected to an adjacent current balancing transformer among the plurality of current balancing transformers to form at least one loop and maintain the current balance, and the protection unit comprises: a detection part configured to detect power induced from the secondary windings of the current balancing transformers; a delay transmission part configured to delay a detected voltage from the detection part by the preset time period and send the delayed voltage to an outside circuit; and a regulation part configured to receive the detected voltage from the detection part and regulate the voltage level of the lamp driving power to the preset reference voltage level during the preset time period.