Method and apparatus to minimize burn lines on a display

A method for displaying a video signal, comprising:

• receiving a video signal representing an image having a first aspect ratio, with said image having a top and bottom edge;
• generating an edge modification signal;
• and
• displaying said image on a display having a second aspect ratio with said top and bottom edge modified in accordance with said edge modification signal, wherein said displaying comprises:
• retrieving said image from said video signal;
• sending said image to an electron gun for a cathode ray tube display system;
• sending said edge modification signal to a shading grid for said cathode ray tube display system;
• displaying said retrieved image on a fluorescent screen of said cathode ray tube display system by sending a stream of electrons representing portions of said image from said electron gun to said fluorescent screen through said shading grid, and with said shading grid modifying said stream of electrons using said edge modification signal to reduce brightness levels at said top and bottom edge of said retrieved image.

A method to generate an edge modification signal, comprising:

• receiving a waveform signal comprising a horizontal parabola signal and a vertical parabola signal;
• filtering said waveform signal to isolate said vertical parabola signal;
• and
• modifying said vertical parabola signal by multiplying said vertical parabola signal with itself at least twice to form said edge modification signal.

An apparatus to display a video signal, comprising:

• a video receiver to receive a video signal representing an image having a first aspect ratio, with said image having a top and bottom edge;
• an edge modification signal generator to generate an edge modification signal;
• and
• a cathode ray tube display system having a second aspect ratio, said cathode ray tube display system comprising at least one electron gun, a shading grid and a fluorescent screen, with said electron gun sending a quantity of electrons representing said top and bottom edge portions of said image to said fluorescent screen through said shading grid, and with said shading grid decreasing said quantity of electrons using said edge modification signal.

An edge modification signal generator, comprising:

• a dynamic waveform generator to generate a dynamic focus waveform signal comprising a horizontal parabola signal and a vertical parabola signal;
• a filter to filter said waveform signal and isolate said vertical parabola signal;
• a first multiplier to multiply said vertical parabola signal with itself;
• and
• a second multiplier to multiply said multiplied vertical parabola signal with itself to form said edge modification signal.

An apparatus to display a video signal, comprising:

• a video receiver to receive and decode a video signal representing an image having a first aspect ratio, with said image having a top and bottom edge;
• a cathode ray tube display system having a second aspect ratio to display said image using a vertical sweep cycle, said vertical sweep cycle having a beginning point and an end point representing said top and bottom edge of said image, respectively;
• and
• a video processing circuit to receive said decoded video signal and produce a flat gain response in the center of said vertical sweep cycle, with said gain decreasing towards said beginning point and said end point of said vertical sweep cycle.