| 摘要 |
PURPOSE:To correct correctly the expansion of a reproduced picture by using the product between a detection signal proportional to the driving current flowing to a vertical deflecting coil and a luminance level signal as the negative feedback signal of a negative feedback amplifying circuit to which the driving current is supplied. CONSTITUTION:A part of the driving current supplied to a vertical deflecting coil 3 from an output circuit 2 is inputted to one input terminal of a multiplying circuit 7 through a variable resistance VR, and the luminance level signal is supplied to the other input terminal. The output of the circuit 7 is connected to the negative input terminal of the circuit 2 to become the negative feedback signal. This negative feedback signal has a waveform where the absolute value of the saw tooth wave level is increased in accordance with the increase of the luminance level signal in both of positive and negative areas of a saw tooth wave. Since the absolute value of the driving current level is reduced in accordance with the increase of the luminance level signal, the deflecting force applied to an electron beam is reduced to suppress the expansion in the vertical direction of the reproduced picture when the luminance of the picture is raised. |
