Method and device for displaying a back-screen and characters by using an on-screen signal to avoid the need for dedicated back-screen circuitry

A device for displaying a back-screen in a video signal processing system, said device comprising:

• chrominance signal processing means for processing a composite video signal and generating a determination signal and synchronizing signals corresponding to the composite video signal;
• means for controlling the back-screen on a visual display by generating one of an on-screen signal and an extended on-screen signal and transmitting a generated signal representative of one of said on-screen signal and said extended on-screen signal via a single transmission line in dependence upon said determination signal and said synchronizing signals;
• and
• means, directly connected to said controlling means via said single transmission line, for driving a cathode ray tube in response to said generated signal to enable an alternative display of on-screen characters on said visual display if said generated signal is representative of said on-screen signal and said back-screen on said visual display if said generated signal is representative of said extended on-screen signal.

A method for displaying a back-screen in a video signal processing system comprising the steps of:

• generating a determination signal, synchronizing signals and primary color signals in dependence upon reception of a video signal;
• alternatively generating an on-screen signal in a microcomputer for enabling a display of on-screen characters on a visual display, and an extended on-screen signal in said microcomputer for enabling a display of said back-screen on said visual display in dependence upon said determination signal and said synchronizing signals;
• driving, in a cathode ray tube driver, a cathode ray tube for displaying said on-screen characters on said visual display in accordance with said on-screen signal and said primary color signals, and for displaying said back-screen on said visual display in accordance with said extended on-screen signal, said cathode ray tube driver being directly connected to said microcomputer via a single transmission line, and said single transmission line transferring one of said on-screen signal and said extended on-screen signal directly from said microcomputer to said cathode ray tube driver;
• and
• blocking said extended on-screen signal when said video signal is received, to disable said back-screen from being displayed on said visual display.

A device for displaying a back-screen in a video signal processing system, comprising:

• chrominance processor means coupled to receive composite video signals, for processing said composite video signals to generate a plurality of color signals, synchronizing signals and a control signal, said control signal being indicative of whether said composite video signals have been received by said chrominance processor means;
• controller means, responsive to said synchronizing signals and said control signal, for generating control signals representative to one of on-screen signals and extended on-screen signals, said on-screen signals representing on-screen characters for enabling a display of said on-screen characters on a visual display when said control signal indicates that said composite video signals have been received by said chrominance processor means, and said extended on-screen signals representing the back-screen for enabling a display of said back-screen on said visual display when said control signal indicates that said composite video signals have not been received by said chrominance processor means;
• and
• driver means, directly connected to said controller means to receive said control signals, for driving one of said on-screen signals and said extended on-screen signals to enable a display of said one of said on-screen characters and said back-screen on said visual display in accordance with a selected color from said plurality of color signals.