Patent ID: 8810150
Filing Date: 2014-08-19
Classification: H05B

Abstract:
1. A lamp drive device comprising: a lamp; a constant current source; a power supply circuit for supplying a direct current voltage to the electrodes of said lamp necessary for sustaining discharge; a trigger voltage generator for applying a trigger voltage to the electrodes of said lamp to start a discharge; and a voltage monitor circuit for measuring the electrode voltage of said lamp; wherein said lamp is lit and discharge is sustained by applying a trigger voltage while supplying a direct current voltage from said power supply circuit to the electrodes of said lamp before the start of discharge; and further comprising: a reference amount-of-change storage unit for storing a threshold value (T) for the amount of change in electrode voltage before the start of discharge and after the start of discharge; an electrode voltage value storage unit for storing a monitor value (A) of the electrode voltage that is measured before the start of discharge; a difference calculation unit for calculating the difference (A−B) between the monitor value (B) of the electrode voltage measured after the start of discharge and the monitor value (A) of the electrode voltage before the start of discharge; and a lighting status determination unit for determining the lighting status by comparing said difference (A−B) and said threshold value (T).