LAMP MALFUNCTION DETECTING DEVICE AND INVERTER EQUIPPED WITH THE SAME, BACK LIGHTING DEVICE AND DISPLAY DEVICE

摘要

This invention is directed to a lamp malfunction detecting device to detect a lamp malfunction. A maximum and minimum extracting circuit (151) outputs an electric current with the maximum value and the one with the minimum value from electric currents supplied from respective lamp driving circuits (140) as the maximum value of an electric current (Imax) and the minimum value of an electric current (Imin), respectively. A subtracting circuit (152) calculates a difference between the maximum value of the electric current (Imax) and the minimum value of the electric current (Imin) and outputs a difference voltage (?V) after the amplification of the difference. A comparison circuit (153) compares the difference voltage (?V) with a predetermined threshold voltage and outputs the compared result as a control signal (S). If the control signal (S) indicates that the difference voltage (?V) is larger than the predetermined threshold voltage, a control circuit (130) makes the lamp driving circuit stop its operation.