Large image display apparatus

Claim 1

A large image display apparatus comprising: a plurality of DC operating discharge lamps each having an anode, a cathode and a light emitting tube; a display board having the plurality of discharge lamps; high frequency generating means having first and second terminals and for generating a high frequency voltage between said first and second terminals; a plurality of rectifying means, each connected between said anode of said respective discharge lamps and said first terminal of said high frequency generating means, for generating a DC voltage including a high frequency ripple voltage component between said first and second terminals, a voltage of said first terminal being higher than that of said second terminal; a plurality of current limiting means, each series connected with said respective rectifying means, for limiting a current flowing through said respective discharge lamps; means for commonly connecting said second terminal with said cathodes of the plurality of discharge lamps; heating means for commonly heating the cathodes of the plurality of discharge lamps; image signal generating means for generating an image signal; and a plurality of switching means comprises a bipolar transistor having a base receiving a control signal dependent on the image signal and an emitter-collector path connected in parallel with said discharge lamp, arranged in parallel between the anode and cathode of said respective discharge lamps, for turning on/off the respective discharge lamps in response to the image signal, terminals of said plurality of switching means which are connected to the respective cathodes being commonly connected to said second terminal of said high frequency generating means.