| 摘要 |
PURPOSE:To obtain an RGB luminance switching circuit appliaoble to a broad range in an output condition by switching stepwise a constant current applied to a differnetial amplifier in response to a level of a luminance switching signal. CONSTITUTION:When an R signal is inputted to an input terminal RIN, a transistor (TR)1 is turned off and a TR2 is turned on. A resistance value of a resistor R4 is selected sufficiently larger and a nearly constant current flows to the TR2. Since a TR3 is turned on or off depending whether input voltage of the luminance switching signal is at a high level or a low level, the emitter voltage is changed over depending on the luminance switching signal. The voltage level generated at the resistor R3 is set freely by changing the current amount flowing to the resistor R4 in this way. This applies also to G and B signals applied respectively to input terminals GIN and BIN. |
