| 摘要 |
PURPOSE:To display brightness and contrast of a data signal in an appropriate state by detecting a cathode current during the period only when the data signal is switched to R, G and B data signals, and controlling automatically the current of R, G and B data signals. CONSTITUTION:An image chrominance component from an input terminal (a) is inputted to an image circuit 1 and a color circuit 2. The former and the latter input an image signal (b) and color difference signals (c), (d) and (e) to a data input switching circuit 3, respectively. Since the switching circuit 3 is provided with change-over switches both on a TV side and a data side; signals (b), (c), (d) and (e) are directly inputted in case of the TV side, and data signals (f), (g) and (h) of R, G and B are carried out by being applied with luminance control and contrast control, in case of the data side and outputted. These two kinds of control are executed when a matrix circuit 4 detects the cathode current of a cathode-ray tube circuit 5, and the current is added to the data input switching circuit through a switching circuit 8 as a control current. |
