Patent ID: 6087776
Filing Date: 2000-07-11
Classification: H05B,Y02B,Y10S

Abstract:
A discharge lamp circuit, comprising:lighting control means for controlling the lighting of a discharge lamp,abnormal condition detect means for detecting an abnormal condition occurring in at least one of the discharge lamp and the discharge lamp lighting circuit, anda protection circuit for receiving a signal from the abnormal condition detect means, said protection circuit being operative to stop the supply of power to the discharge lamp, wherein:(a) said protection circuit comprises first protection means and second protection means and said first protection means and said second protection means are separate and distinct;(b) said first protection means being operative, when a permanent abnormal condition is detected in said discharge lamp or in said discharge lamp lighting circuit by said abnormal condition detect means, to cut off the power supply to the discharge lamp and hold said power supply cutoff condition;(c) said second protection means being operative, when a transient abnormal condition is detected in one of said discharge lamp and said discharge lamp lighting circuit by said abnormal condition detect means, first to cut off the power supply to said discharge lamp and, thereafter, when said transient abnormal condition is no longer detected, to remove said power supply cutoff condition to thereby resume the power supply to said discharge lamp; and(d) while the power supply to said discharge lamp is being cut off by said second protection means, the cut-off of the supply of power to said discharge lamp and the holding of said power supply cutoff condition by said first protection means are prohibited.