| 摘要 |
The power supply rectifies the output of the secondary coil of the commercial AC power transformer, followed by rectifying a half wave of the second secondary coil of the same ac power transformer before feeding one-half cycle of the commercial AC current to the heater of the fluorescent display tube. The power supply uses a rectifying circuit for generating the double voltage for the second secondary coil, the double voltage being mixed in the direction in which it becomes lower than the stable voltage of the microcomputer. The display erase potential VP is thus generated. As a result, luminance can be held constant in respective display positions without causing the voltage of the display tube to vary throughout the one-off operations of the heating power source.
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