Patent ID: 6496160
Filing Date: 2002-12-17
Classification: G09G

Abstract:
Apparatus for converting analog stroke display signals representing electron beam generated stroke traces, into raster display information for producing a raster-scan image display, including:a sampling circuit for sampling the analog stroke display signals to produce pixel data representing sub-pixel locations covered by the stroke traces; a frame buffer coupled to the sampling circuit for temporarily storing pixel data; a filter coupled to the frame buffer for calculating brightness of pixels based upon the amount of coverage of the pixels by a stroke trace; and a raster-scan display device coupled to the filter for receiving the pixel data from the filter to produce a raster-scan image; wherein the stroke display signals include an analog X major deflection signal and an analog Y major deflection signal defining respectively the X axis and Y axis end point coordinates of a stroke trace, and wherein said sampling circuit includes an analog-to-digital converter for producing digitized representations of the X and Y major deflection signals, representing sub-pixel locations covered by the stroke trace; wherein the stroke display signals further include signals further include an analog x character deflection signal and an analog y character deflection signal defining respectively the x axis and y axis coordinates of a character stroke trace as a character is being drawn, and wherein the analog-to-digital converter produces digitized samples (digital representations) of x and y character deflection signals, representing sub-pixels locations covered by the character stroke trace; wherein the stroke display signals further include a three-level video signal in which a level 0 indicates that the electron beam is to be moved while off, a level 1 indicates that a stroke trace is to be drawn by the electron beam (at a first brightness level), and a level 2 indicates that a character is to be drawn by the electron beam (at a second brightness level), said sampling circuit further including a sample combiner for adding the digitized samples of the X major and x character deflection signals and adding the digitized samples of Y major and y character deflection signals when the video signal is a level 2, and supplying the sums to the frame buffer, for supplying the digitized samples of the X major and Y major deflection signal to the frame buffer when the video signal is a level 1, and for supplying no digitized samples to the frame buffer when the video signal is a level 0.