| 摘要 |
PURPOSE:To adjust continuously a luminance of a CRT display by sensing an illumination intensity at the periphery of a CRT with a illumination intensity sensor, and linking an illumination intensity volume and a luminance volume so that the signal in accordance with the illumination intensity can go to be the variable value of the luminance volume. CONSTITUTION:The light received by a photodetecting part 5 with an optical battery as an element is made into digital signal at an A/D converting part 6 as an electric signal and transferred to a data memory part 7. the memory part 7 stipulates a correlating reference value of a CRT peripheral illumination intensity and a CRT luminance set beforehand, and supplied to a D/A converting device 8. The data analog-converted at the converting device 8 are inputted into the base of a transistor 11, and further, the electric current, which flows at an auxiliary luminance volume 3 and a resistance 2 for adjusting the luminance, is controlled. The voltage applied to a grid 9 is changed by the electric current and the luminance of the display surface of a CRT 1 is controlled.
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