DISCHARGE LAMP LIGHTING DEVICE

摘要

PROBLEM TO BE SOLVED: To average optical output of a discharge lamp even when data are superimposed on illumination light without being restricted by modulation speed or encoding to prevent occurrence of flickering.

SOLUTION: A signal control interface part 5 superimposes data on the optical output of the discharge lamp 3 to transmit the data by modulating the frequency of high-frequency A.C. output of an inverter circuit 2 by a data signal given from the outside. The interface part 5 simultaneously changes the oscillation frequency of an oscillation circuit 41 and an on-duty ratio D of a duty ratio setting circuit 43. Accordingly, since the on-duty ratio D is also changed at the same time even if the switching frequency f is reduced, the high-frequency A.C. output of the inverter circuit 2 is averaged without being apparently changed, and the the optical output of the discharge lamp 3 is kept nearly constant.

COPYRIGHT: (C)2005,JPO&NCIPI