Patent ID: 8797313
Filing Date: 2014-08-05
Classification: H05B,Y02B

Abstract:
1. A driving device for a discharge lamp, comprising: an alternating current supply section configured to supply two electrodes of the discharge lamp with an alternating current, the alternating current comprising a plurality of modulation periods; and a frequency modulation section configured to modulate a frequency of the alternating current in accordance with a predefined modulation pattern, the predefined modulation pattern comprising a plurality of retentive periods within each of the modulation periods, each retentive period having a constant frequency that is different from a frequency of temporally adjacent retentive periods, wherein the frequency modulation section makes a length of at least one of the retentive periods in the modulation period shorter in response to at least two conditions being met: (a) a predetermined condition occurring, and (b) the frequency of the at least one of the retentive periods is equal to or less than a predetermined reference frequency, and the frequency modulation section is configured to modulate the frequency of the alternating current in accordance with the predefined modulation pattern when the at least two conditions are not met.