| 摘要 |
PROBLEM TO BE SOLVED: To prevent leakage light emitting noise from occurring in other driving signal via a capacity between wirings arranged around a vacuum fluorescent display tube which is generated by a sudden change in data of digit and segment drive signals. SOLUTION: Pulse response noise S101, which occurs in a digit drive control signal S610 due to a sudden rise of a segment drive control signal by the influence of a simultaneous change of a segment drive high withstand voltage output port 102 via capacitance 608 between wirings around a vacuum fluorescent display tube, is detected by a leakage light emitting noise detecting circuit 103. An output characteristics adjusting signal S103 is generated, which decides an output characteristics of digit and segment drive high withstand voltage output ports from a detected leakage light emitting noise signal S102 by a high withstand voltage output port characteristics adjusting circuit 105 is generated. With the generated output characteristics adjusting signal, it is judged how much larger the generated leakage light emitting noise is than a filament bias voltage, and the leakage light emission is prevented by adjusting each output characteristics of the segment and digit drive signals and relaxing the pulse response noise.
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