Scaled graphic line display on cathode-ray tube with uniform brightness

Claim 2

In a cathode-ray tube display system having digital means for deflection of an electron beam in said tube, said digital deflection means including means for storing a number proportional to the length of a graphic line to be displayed and means for counting a number of fixed-frequency clock pulses equal to said stored number to control said deflection means in displaying a graphic line, an improvement comprised of means for scaling said stored number for a desired graphic display scale by shifting said stored number in said storage means, thereby altering the number of clock pulses counted for the graphic line displayed to alter the scale thereof while maintaining the deflection rate of said beam constant for all range scales, thereby maintaining uniform brightness in the display of graphic lines of all lengths at all scales.

Claim 3

In a cathode-ray tube display system for displaying graphic lines, said system having digital means for deflection of an electron beam in said tube in an X axis direction and digital means for simultaneous deflection of said electron beam in a Y axis direction while displaying a graphic line of a specified length at a specified angle with respect to one of said axes, said x- and y-axis deflection means including a source of clock pulses occurring at a fixed rate and means for counting a number of said clock pulses proportional to the specified length of a graphic line to be displayed in order to produce a running line length count for the graphic line specified, an improvement comprised of means for storing said length of a line to be displayed in binary digital form, and means for scaling said length for a desired graphic display scale before counting clock pulses by shifting said length in said storing means, thus altering the numBer of clock pulses counted to alter the scaled length of the graphic line displayed while maintaining the deflection rate of said beam constant for uniform brightness.

Claim 4

In a cathode-ray tube display system for displaying graphic lines, said system having digital means for deflection of an electron beam in said tube in an X axis direction and digital means for simultaneous deflection of said electron beam in a Y axis direction while displaying a graphic line of a specified length at a specified angle with respect to one of said axes, said x- and y-axis deflection means including a source of clock pulses occurring at a fixed rate and means for counting a number of said clock pulses proportional to the specified length of a graphic line to be displayed in order to produce a running line length count for the graphic line specified, an improvement comprised of means for storing said length of a line to be displayed in binary digital form, and means for scaling said length for a desired graphic display scale before counting clock pulses by shifting said length in said storing means, thus altering the numBer of clock pulses counted to alter the scaled length of the graphic line displayed while maintaining the deflection rate of said beam constant for uniform brightness.

Claim 5

Apparatus as defined in claim 2 wherein said scaling means is comprised of a shift register and said scaling means is comprised of means for applying shift pulses to said shift register, one shift pulse for each binary order of difference in the desired scale over a range scale which requires the maximum number of clock pulses to be counted for a line of maximum length.

Claim 6

Apparatus as defined in claim 3 wherein said counting means is a count-down binary counter connected to receive a scaled length and to receive said clock pulses for counting down said scaled length to zero, thereby counting a number of said clock pulses proportional to the specified length of a graphic line to be displayed.

Claim 7

Apparatus as defined in claim 4 wherein said digital means for deflection of said electron beam of said tube in said X and Y axes is comprised of separate X and Y binary counters and means for producing X and Y trains of pulses effectively at the respective rates R sin theta and R cos theta , where R is the scaled length of the line specified and theta is said specified angle of said line, and wherein said X and Y pulse trains are applied to the least significant binary stages of said X and Y counters respectively, whereby upon accummulating said trains of pulses in said X and Y counters until said counting means counts down to zero in response to clock pulses, at a fixed frequency, the electron beam is deflected said distance R at said angle theta without changing the connections of the pulse trains to the least significant binary stages of said X and Y counters for scaling, thereby maintaining a substantially constant beam deflection rate for lines displayed at any selected scale.