Cursor positioning method and apparatus

A control system for use with a screen having a movable graphic element comprising:

• a keyboard;
• means for generating a planar field of first signals which extend generally vertically from said keyboard;
• means for detecting an echo of said first signals from an object moving in said planar field of first signals;
• means responsive to said detecting means for providing a second signal corresponding to a change in the position of said object in said field of first signals;
• and
• means responsive to said second signal for changing the position of said graphic element on said screen from a first position to a second position as a function of said change in position of said object in said field of first signals.

A control system for use with a screen having a movable graphic element comprising:

• a keyboard;
• means for generating a field of signals which extend from said keyboard;
• means for detecting an echo of said signals from an object moving in said field;
• means responsive to said detecting means for changing the position of said graphic element on said screen from a first position to a second position as a function of said change in position of said object in said field, said change in position of said graphic element on said screen being independent of the starting point of said change in position of said object in said field.

A control system for use with a display screen having a movable graphic element comprising:

• a keyboard;
• a plurality of spaced transducers for generating a field of signals which extends generally vertically from the rear of said keyboard;
• means coupled to each of said transducers for providing therefrom a plurality of pulses at a predetermined pulse rate and with a predetermined interval therebetween, each of said pulses comprising a predetermined pulse width and a predetermined frequency;
• means for dithering said predetermined interval between said pulses to permit signal processing software to discriminate against an undesired, around-the-timebase echo reflected from an object struck by said pulses;
• and
• means responsive to reflections of said signals from an object moving in said field for changing the position of said graphic element on said display screen from a first position to a second position as a function of the direction and speed of movement of said object in said field.

A control system for use with a display screen having a movable graphic element comprising:

• a keyboard;
• means for generating a field of acoustic pulses having a predetermined pulse width and a predetermined frequency with a predetermined interval between said pulses which extends generally vertically from the rear of said keyboard;
• means responsive to reflections of said acoustic pulses from a first object moving in said field for changing the position of said graphic element on said display screen from a first position to a second position as a function of the direction and speed of movement of said object in said field;
• and
• means for dithering said predetermined interval between said pulses to permit signal processing software to discriminate against an undesired, around-the-timebase echo reflected from a second object in said field.