Method of and apparatus for sensing the location, such as coordinates, of designated points on an electrically sensitive touch-screen surface
AssigneeMicrotouch Systems, Inc.
InventorBlair Evans
Life of this patent
Estimating the term…
Abstract
A method and apparatus are disclosed for determining the location of a designated point on an electrically sensitive touch-screen surface while minimizing aberrations introduced by non-uniformity in the field applied to the surface, by attaching a plurality of field-producing discrete point electrodes to widely spaced points on the surface in a predetermined geometric pattern and by measuring the currents drawn from the point electrodes upon the capacitive touching of a designated location on the surface.
Claims36
A capacitive touch-screen sensor apparatus for providing high resolution sensing of a designated point on a touch-screen surface having, in combination:
- a rigid uniformly electrically conductive surface;
- a plurality of discrete point electrodes widely separate from one another on the surface;
- alternating current driver means connected to the point electrodes for driving the electrodes with matched drive signals to produce a regular electric field over the surface;
- first circuit means for separately sensing the respective currents drawn through the point electrodes in response to the capacitive touching of a designated point on the surface and producing in accordance with each sensed current a signal representing the distance from the designated point to the corresponding electrode;
- and
- second circuit means for determining from the distance-representing signals the location of the designated point on the surface.
A method of touch location, comprising providing a touch-sensing surface having a plurality of discrete point electrodes widely spaced apart thereon in a predetermined geometric pattern, driving the electrodes with matched alternating-current voltages to generate a regular electric field over the touch-sensing surface, separately measuring the respective currents through the point electrodes simultaneously upon a capacitive touching of the touch-sensing surface, and determining the location of the capacitive touching from the measured currents.
A method of touch location, comprising providing a touch-sensing surface having a plurality of discrete point electrodes widely spaced apart thereon and defining the boundaries of a regular geometric pattern, driving the electrodes with matched alternating-current drive voltages to produce a regular electric field over the touch-sensing surface, producing in accordance with the respective current flow in each electrode a signal representing the distance from a capacitively touched point on the touch-sensing surface to that electrode, and determining the location of the touched point on the touch-sensing surface from the distance-representing signals.
Capacitive touch-screen sensor apparatus, comprising:
- a electrically conductive touch-sensitive surface;
- a plurality of discrete point electrodes widely space from one another on the surface;
- alternating current driver means connected to the point electrodes for driving the electrodes with matched drive signals to produce a regular electric field over the touch-sensitive surface;
- first circuit means for separately sensing the respective currents drawn through the point electrodes in response to the capacitive touching of a designated point on the touch-sensitive surface;
- and
- second circuit means for determining from the separately sensed currents the location of the designated point on the touch-sensitive surface.
Dependencies are inferred from the claim text.