| 摘要 |
PURPOSE:To take a picture of the waveform on the oscilloscope under the optimum conditions, by providing a scale illuminance adjusting function in a Braun tube luminance adjusting devie, and maintaining a constant ratio between the luminance of the Braun tube and illuminance of the scale. CONSTITUTION:The luminance of the Braun tube 1 is adjusted by the voltage of a Braun tube luminance adjusting device 2. The illuminance of the scale is adjusted by controlling the current supplied to a lamp 7 from a scale illuminance adjusting device 9 through a constant current source 6, when a switch 5 is at the position on the other side of the illustrated position. When the switch 5 is at the illustrated position, the adjusting voltage of the Braun tube luminance adjusting device 2 is divided by impedances 3 and 4 and applied to the constant current source 6. Thus, the current of the lamp 7 is controlled. In this constitution, the luminance of the Braun tube 1 and the illuminance of the lamp can be controlled by constant relationship at the same time, and the constant contrast can be maintained. |
