Patent ID: 6345099
Filing Date: 2002-02-05
Classification: H04N

Abstract:
An apparatus for modifying a graphics data signal to produce a video signal of poor quality if recorded by a VHS-type recorder but which can still be accurately displayed on a computer monitor, comprising:a vertical picture contractor, having an input coupled to the graphics data signal, for contracting the graphics data signal in vertical size to produce a contracted signal; an attenuator, coupled to an output of the vertical picture contractor, for attenuating the amplitude of the contacted signal; a horizontal timing generator for selecting locations for pulse bars to be inserted into the contracted signal such that the pulse bars will not interfere with a display of the graphics data signal on a computer monitor; a pulse bar generator, coupled to the horizontal timing generator, for generating horizontal pulse bars at a location determined by the horizontal timing generator and an amplitude greater than a maximum picture amplitude of the attenuated signal sufficient to distort the graphics data signal if viewed on a non-computer monitor device; and an adder, coupled to the output of the attenuator and the output of the pulse bar generator, for adding the horizontal pulse bars to the attenuated signal to create said video signal of poor quality.