| 摘要 |
A lighting control signal generating circuit 10 controls the output pulse of a drive signal circuit 11 by the output signal. The output pulses of the drive signal circuit 11 include a first and a second pulse drive signal 11a, 11b, each of which has a phase inverted to each other. These first and second pulse drive signals 11a, 11b are controlled the repetition frequency by the output signal of said light control signal generating circuit 10. Further, the drive signal circuit 11 generates a third pulse drive signal 11c which is so controlled as to be turned ON and OFF in accordance with the output signal of the light control signal generating circuit 10. The first and second pulse drive signal 11a, 11b supplied by the drive signal circuit 11 control the first and the second switching device S1, S2 by turning them ON and OFF alternately. A pulse transformer 12 is provided with a primary coil L1 and a secondary coil L2. The direction of the current flowing in the primary coil L1 is switched and a boosted pulse voltage is generated in the secondary coil L2. A flicker preventing circuit 14 is connected with the primary coil L1 of the pulse transformer 12 in parallel. This flicker preventing circuit 14 is composed of a series connection circuit of a third switching device S3 and an element R having a resistance component. The third switching device S3 is turned ON and OFF in accordance with the third drive signal 11c supplied by the drive signal circuit 10. An outer electrode fluorescent lamp is connected with the secondary coil L2 of the pulse transformer 12.
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