A discharge-lamp lighting device is provided which decreases arc jumps,
suppresses the fluctuation in brightness of the lamp, and prolongs a life
of the lamp, by positively accelerating growth of spots even when an
inexpensive, small and highly efficient lamp is used. A discharge-lamp
controlling portion (101) sets frequencies of drive-controlling signals (A
and B) for drive-controlling a commutator (109) within a predetermined
frequency range so that spots formed by arc discharge on electrodes
composing a high-pressure discharge lamp grow through a cycle of
oxidation-reduction of a metal composing the electrodes, and superimposes
a triangular wave signal generated on the basis of the drive-controlling
signals onto a current-controlling signal (F) over an entire period of the
drive-controlling signals so as to make a peak value of the triangular
wave constant, thereby adjusting the waveform of current flowing in the
high-pressure discharge lamp.
