Patent ID: 6380988
Filing Date: 2002-04-30
Classification: G09G,H04N

Abstract:
A focus compensation apparatus for adjusting a focus at the edge of a monitor screen in a monitor system, the focus compensation apparatus comprising:a parabolic signal generation circuit for generating a parabolic signal in synchronization with a horizontal flyback pulse, the waveform of the parabolic signal varying in response to first and second control signals, the parabolic signal generation circuit comprising: a first level adjustor for generating a first signal having a level corresponding to the first control signal, a horizontal parabolic signal generator for generating a horizontal parabolic signal in synchronization with the horizontal flyback pulse, the waveform of the horizontal parabolic signal varying in response to the first signal and the second control signal, the horizontal parabolic signal generator comprising: a first sawtooth generator for receiving the horizontal flyback pulse and generating a first sawtooth signal synchronized with the horizontal flyback pulse, a first multiplier for receiving the first sawtooth signal and squaring a linear section of the first sawtooth signal to generate a squared signal as a first square signal, a second level adjustor for receiving the first signal, adjusting the level of the first signal in response to the second control signal, and generating a level-adjusted first signal as a second signal, and a first parabolic amplitude adjustor for receiving the first square signal, controlling the amplitude of the first square signal to be the level of the second signal, and generating an amplitude-controlled signal as the horizontal parabolic signal, and a parabolic signal synthesizer for synthesizing the first signal and the horizontal parabolic signal and generating a synthesized result as the parabolic signal for controlling the input video signal, such that the gain of the input video signal increases from the center toward the edge of the monitor screen; and a video signal focus compensator for adjusting the gain of an input video signal such that the gain increases from the center of the monitor screen toward the edge of the monitor screen in response to the parabolic signal, and for outputting a gain-adjusted video signal as a focus-compensated video signal.