| 摘要 |
PURPOSE:To light an incandescent lamp to compensate a luminous flux shortage at the time of starting a discharge lamp, and minimize the change of the luminous flux in which the output luminous fluxes of the discharge lamp and the incandescent lamp are added. CONSTITUTION:A power source circuit la rectifies a commercial AC power source AC and outputs a DC voltage raised in voltage. A lighting circuit 1b reduces the output voltage of the power source circuit 1a and supplies it to a discharge lamp La. A power source control circuit 3a keeps the output voltage of the power source circuit 1a nearly constant. As the output luminous flux of the discharge lamp La is increased, the power source control circuit 3a extends the on-period of a switching element Q1. A signal the ON/OFF of which is reversed from a control signal for controlling the switching element Q1 is inputted to a light control circuit 2, and the light control circuit 2 lights an incandescent lamp Lb on the basis of this signal. Thus, according to an increase in output light quantity of the discharge lamp La, the output light quantity of the incandescent lamp Lb is reduced. |
