CIRCUIT CONFIGURATION FOR INSET-IMAGE KEYING IN A TELEVISION SET HAVING ONLY ONE TUNER

摘要

A circuit configuration for inset-image keying in a television set having only one tuner and a picture tube includes a control device connected to the tuner for switching the tuning frequency of the tuner between a first image signal of a first program for displaying a large image and a second image signal of a second program for displaying a small image to be keyed into the large image. A switchover device is connected to the tuner and the control device. A large-image signal route for the first image signal has a large-image memory device. A small-image signal route for the second image signal has a small-image memory device. The switchover device alternately supplies the first image signal to the large-image signal route or the second image signal to the small-image signal route. A device reads out and keys the small image into the large image on the picture tube. The large-image memory device continuously supplies the large image during periods of time in which the switchover device is switched to the small-image signal route by repeated readout of the most recently stored large image. The periods of time are selected to enable the small image stored in the small-image memory device to be at least partly rewritten by new second image signals for displaying a new small image.