| 摘要 |
PURPOSE:To eliminate uneasy to see state of sound multiplex broadcast mode display at the receiving mode of a video signal and to output the sound multiplex broadcast as it is by providing a receiving image mode discriminating means to control a sound multiplex mode display means. CONSTITUTION:The sound multiplex discriminating signal is inputted to a voltage comparator 8. The level of outputs of two comparators 8a, 8b is changed in response to each mode of the discriminating signal. In case of the duplicate broadcast, a transistor (TR) 9a of a display control circuit 9 is turned on, a character signal is transmitted to an on-screen control circuit 10 and displayed on a CRT screen. In case of the stereo mode, a TR9b is turned on and the stereo display is attained on the CRT. An output of a mode discriminating circuit 11a goes to low level in a receiving image mode discriminator 11 at the TV mode, the TR11b is turned off and the operation is reversed entirely in case of the video and RGB modes. Thus, the circuit 9 is operative only at the TV mode and inoperative at the video and the RGB modes. |
