| 摘要 |
PURPOSE:To ensure the reproduction of a picture with high fidelity, by putting a variable resistor for adjusting a drive gain into a coupled part of two transistors that form a cascode amplifier. CONSTITUTION:Switches 16 and 17 are usually closed. The signal R supplied from an input 1 is amplified by a cascode amplifying circuit consisting of transistors TR10 and TR11 and then transmitted to a CRT from an output 7 for the reproduction of pictures. Then a variable resistor 5 is put into the area between the collector of an input side TR10 and the emitter of an output side TR11. At the same time, a distributing resistor 15 is provided between the collector of the TR10 and a constant voltage source. Then the gain is controlled by the resistor 5 to carry out the control of the white balance. Thus the satisfactory reproducibility of the detailed contrast of the parts at the area near the black level is satisfactorily obtained. |
