| 摘要 |
PURPOSE:To effectively prevent a spot from being generated, by supplying a voltage-divided negative voltage on the grid of a CRT from a negative power source, and performing charge/discharge corresponding to the ON/OFF of a power source switch. CONSTITUTION:When the power source switch is turned ON, the negative power source charges a capacitor 18. Also the negative voltage voltage-divided by a variable resistor 16 is impressed on the grid G1 via a resistor 15. And the change of the luminance adjusting variable resistor 16 smoothes the change of luminance. Next, when the power source switch is turned OFF, all of the negative power source 26, the low voltage power source 28, the high voltage power source, and the cathode power source go to zero potentials. And the discharge circuit of a closed loop consisting of a grounding 16 and a resistor 12, a diode 34, a transistor 36, a capacitor 18, and the ground is operated. As a result, the potential of the G1 is kept at a negative potential, and the generation of the spot at the CRT10 can be prevented.
|
