VIDEO SIGNAL SWITCHING CIRCUIT ESPECIALLY SUITABLE FOR HIGH DEFINITION TELEVISION RECEIVING

摘要

PCT No. PCT/JP88/01085 Sec. 371 Date Aug. 6, 1990 Sec. 102(e) Date Aug. 6, 1990 PCT Filed Oct. 24, 1989 PCT Pub. No. WO90/04904 PCT Pub. Date Mar. 5, 1990.The present invention provides an apparatus which receives and displays a high definition television signal and which is constructed so that noise and/or a deformed picture may not be displayed even when an input signal instead of a high definition television signal is applied or when transmission of such a high definition television signal is interrupted. In the apparatus, on the basis of whether or not a frame signal in an input high definition television signal can be detected, a first signal indicating synchronization lock or a second signal indicating synchronization unlock is generated so that, when the first signal is detected, the output of a signal processing circuit (110) is selected to display the high definition television signal, while when the second signal is detected, the output of a pattern generation circuit (114) is selected to prevent display of noise etc.