Patent ID: 8004215
Filing Date: 2011-08-23
Classification: G02F,H05B

Abstract:
1. A lamp abnormality detecting device that detects an abnormality occurred in any of a plurality of lamps which are feedback-controlled by a current, the lamp abnormality detecting device comprising: a current detection portion that detects currents flowing through the respective lamps; a maximum current extraction portion that extracts a current having a maximum value among the currents detected in the respective lamps by the current detection portion; a minimum current extraction portion that extracts a current having a minimum value among the currents detected in the respective lamps by the current detection portion; a differential circuit that calculates a differential value representing a difference between the value of the current extracted by the maximum current extraction portion and the value of the current extracted by the minimum current extraction portion and outputs the differential value; and a comparison circuit that compares the differential value outputted from the differential circuit with a threshold value which serves as a reference for whether an abnormality has occurred in the plurality of lamps, and outputs a result of the comparison.