Patent ID: 6163115
Filing Date: 2000-12-19
Classification: H05B,Y02B

Abstract:
A lighting apparatus for a high-pressure discharge lamp comprising:a power conversion device with a variable output, comprising a semiconductor switch for chopping direct current and having an output side connected to a high-pressure discharge lamp;a high-voltage generation circuit for applying high voltage to the high-pressure discharge lamp on the basis of the output from the power conversion device, to turn on the high-pressure discharge lamp;a target power setting device constituted to be capable of setting a target power value to be supplied from the power conversion device to the high-pressure discharge lamp;power detection means for detecting quantity of electricity correlating with power supplied to the high-pressure discharge lamp;control means for controlling an operation of the semiconductor switch of the power conversion device so as to make the target power value set by the target power setting device approximate to the quantity of electricity detected by the power detection means; anda charging circuit having a capacitor constituted to be charged with a current correlating with the target power value set by the target power setting device,wherein the target power setting device sets the target power value on the basis of a charging voltage of the capacitor in the charging circuit when operations are started, and lowers the target power value in accordance with a duration of operations.