Multiplexed video signal interface signal, system and method
AssigneeNational Semiconductor Corporation
InventorsAndrew Morrish, Peyman Hojabri
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Abstract
A multiplexed video signal interface in accordance with the present invention provides a multiplexed component video signal in which, in addition to the component video signals with OSD data and user-controllable contrast and video gain, includes control signal components for image brightness and CRT bias along with the ability to individually control such control signal components. This advantageously minimizes the complexity of the necessary signal interfaces and allows for greater integration of circuit functions, thereby significantly reducing circuit complexity, size and costs.
Claims10
An apparatus including a signal multiplexor for multiplexing video image, on-screen-display (OSD) and display control signals, comprising:
- a first control circuit that upon receiving a reference signal, a contrast control signal and a clamped video signal provides a first controlled signal with a contrast-controlled video component;
- a first signal combining circuit, coupled to said first control circuit, that in response to a first combining control signal receives and selectively combines an OSD signal and said first controlled signal to thereby provide a first combination signal with said contrast-controlled video component and an OSD component;
- a second control circuit, coupled to said first signal combining circuit, that upon receiving said first combination signal, said reference signal and a gain control signal provides a second controlled signal with a contrast-controlled and gain-controlled video component and a gain controlled OSD component;
- a third control circuit that upon receiving and combining a brightness control signal and a bias control signal and receiving said gain control signal provides a third controlled signal with a gain-controlled brightness control component and a bias control component;
- and
- a second signal combining circuit, coupled to said second control circuit and said third control circuit, that in response to a second combining control signal receives and selectively combines said second and third controlled signals to thereby provide a multiplexed signal with said contrast-controlled and gain-controlled video component, said gain-controlled OSD component, said gain-controlled brightness control component and said bias control component.
A method of multiplexing video image, on-screen-display (OSD) and display control signals, comprising the steps of:
- receiving a reference signal, a contrast control signal and a clamped video signal and in response thereto generating a first controlled signal with a contrast-controlled video component;
- receiving a fat combining control signal and in response thereto receiving and selectively combining an OSD signal and said first controlled signal and thereby generating a first combination signal with said contrast-controlled video component and an OSD component;
- receiving said first combination signal, said reference signal and a gain control signal and in response thereto generating a second controlled signal with a contrast-controlled and gain-controlled video component and a gain-controlled OSD component;
- receiving and combining a brightness control signal and a bias control signal and receiving said gain control signal and in response thereto generating a third controlled signal with a gain-controlled brightness control component and a bias control component;
- and
- receiving a second combining control signal and in response thereto receiving and selectively combining said second and third controlled signals and thereby generating a multiplexed signal with said contrast-controlled and gain-controlled video component, said gain-controlled OSD component, said gain-controlled brightness control component and said bias control component.
Dependencies are inferred from the claim text.