| 摘要 |
PURPOSE:To eliminate the blind sector of luminance restricting action by clamping the detected voltage of anode current of a CRT to the voltage corresponding to luminance regulating voltage, and setting this voltage to the driving voltage of an output transistor. CONSTITUTION:Anode current detection voltage VA is generated in the detecting end of a resistance 12 for anode current IM detection of a CRT. Luminance regulating voltage VB of a luminance controlling circuit 3 is supplied from a variable resistance 7 to which power source VCC1 is applied. Voltage VB is supplied to the emitter of a transistor TR5 for luminance restriction, and voltage from the variable resistance 7 is applied to the base of a TR29 that forms voltage VD corresponding to the voltage VB. Voltage VA is clamped to the voltage VD by a clamping diode 17 and applied to the emitter resistance 22 of a TR4 as the driving voltage of the output TR4. Thus, operation characteristics changing from non-restricting operation of regular luminance to restricting operation are not accompanied by the state of no control, and elimination of the blind sector of luminance restricting action becomes possible. Further, temperature compensation of the output TR4 is also possible.
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