Touch panel system and method
First Claim
1. In an apparatus for locating a selected touch point on a current-conducting impedance surface having at least a pair of boundaries, the improvement comprisingmeans for linearizing current flow to said boundaries,means for causing a linearized electrical current to flow through said selected touch point as the sum of separate currents passing through each of said boundaries, andmeans for translating said separate currents to at least one signal corresponding to the location of said selected touch point relative to said boundaries.
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Abstract
A general method is disclosed for accurately determining the location or position of a source or sink of electric current on the surface of a resistance element or impedance layer. Touch panels are described that detect the presence of a user'"'"'s finger on such surface, and produce output signals corresponding to the position of the finger in one or more axes. A preferred embodiment discloses a touch panel that includes a signal generator and determines the position of the user'"'"'s finger from current flowing through the user'"'"'s body to ground. Another touch panel embodiment determines the position of the user'"'"'s finger from currents caused by ambient electrical noise. A pressure-sensitive touch panel, a transparent touch panel for use with a video display, a touch-panel-controlled audio mixer, and a video game incorporating touch panels are also disclosed.
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Citations
28 Claims
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1. In an apparatus for locating a selected touch point on a current-conducting impedance surface having at least a pair of boundaries, the improvement comprising
means for linearizing current flow to said boundaries, means for causing a linearized electrical current to flow through said selected touch point as the sum of separate currents passing through each of said boundaries, and means for translating said separate currents to at least one signal corresponding to the location of said selected touch point relative to said boundaries.
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6. A method of detecting a selected touch point on a current-conducting impedance surface having at least a pair of spaced boundaries comprising the steps of
causing an electrical current to flow through said selected touch point as the cumulative linearized current passing through those portions of said conductive impedance surface between said selected touch point and each boundary, respectively, and translating the electrical current flow through said portions to a signal corresponding to the location of said selected touch point relative to one of said boundaries.
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7. Apparatus for detecting the position of a selected touch point on a current-conducting surface comprising,
edge termination means defining two or more spaced apart edges of said current-conducting surface, the distance between said two or more spaced edges being predetermined, said edge termination means having terminals for connection to an external circuit, circuit means connected to said terminals of said edge termination means for maintaining said terminals at a predetermined instantaneous electrical potential at any time a linearized electrical current flows through said edges to any point on said surface between said edges, means for detecting a parameter of the linearized electrical currents through said terminals, and means for determining from the values of said detected parameter the location of said selected touch point on said surface at which said current is flowing from said edges, and producing at least one electrical signal corresponding to the said location of said selected touch point relative to at least one of said edges.
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20. In a touch panel system having a resistive surface defined by two opposed pairs of edge terminations on said surface, a line passing through each edge pair being orthogonal to a line passing through the other edge pair, and having means for maintaining the terminals of said edge terminations of said surface at a predetermined instantaneous electrical potential, the method of locating a position on said surface comprising
creating a potential difference between the terminals of said surface and a point touched on said surface by a human finger, placing said finger in proximity to said surface at any selected point such that current flows through said finger and said point to the terminals of said edge termination of said surface, measuring a parameter of said current flowing through said terminals, and converting said current measurements to a utilization signal and applying same to a utilization device.
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21. In a touch panel system having an impedance surface element or layer bounded by at least three edge terminations for said surface, with at least three terminals for connecting external circuitry to said edge terminations, a method of determining the position of a selected touch point on said impedance surface, comprising,
measuring electrical currents flowing through said terminals, and determining from said measurements the location of said selected touch point on said surface and producing an electrical signal corresponding thereto.
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23. A method of determining in two dimensions the location of a source or sink of electrical current on a current-conducting surface, comprising the steps of
establishing at least three electrical connections to said surface, said surface possessing an electrical impedance that (1) is constant as a function of location or (2) is a known function of location, measuring the electrical currents that said source or sink causes to flow through said electrical connections, and determining the location of said source or sink of electrical current from the electrical measurements.
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24. A method of determining the location on an extended current-conducting impedance surface, of a current-conducting pathway between said impedance surface and a point of common electrical potential comprising:
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establishing at least two electrical connections to said impedance surface, said impedance surface possessing an electrical impedance that (1) is constant as a function of location or (2) is a known function of location, establishing potential differences between said electrical connections and said point of common electrical potential, linearizing current flow through said connections, measuring the electrical currents that flow through said electrical connections, and determining the location of said current-conducting pathway from the electrical measurements.
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25. A proportioning system for producing at at least three output terminals at least three signals which are functions of the position of a human finger at a selected touch point on a touch panel surface, comprising an impedance surface bounded by at least three current-conducting edges and at least three terminal means connecting said current-conducting edges to an external circuit, means for maintaining said terminal means at a selected instantaneous potential and means for establishing potential differences between said selected touch point and said terminal means whereby the ratio of current flow through any one of said terminal means to the total current through all of said terminal means is a function of the position of said selected touch point relative to said current-conducting edges.
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26. An apparatus for simultaneously locating a selected touch point on each of at least two separate touchable surfaces, comprising:
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at least two current-conducting impedance surfaces, each of said impedance surfaces being bounded by edge-termination means with at least two terminals for connecting said edge-terminations means to an external circuit, means connected to said terminals for maintaining said terminals at predetermined instantaneous electrical potentials, means for creating an instantaneous difference in net electrical potential between said terminals of a first impedance surface and said terminals of at least one other impedance surface, such that when a current-conducting means is provided between a selected touch point on said first impedance surface and a selected touch point on said other impedance surface, electrical currents are caused to flow through said terminals of both said first impedance surface and said other impedance surface, means for detecting a parameter of the electrical currents through said terminals of both said first impedance surface and said other impedance surface, and means for determining from the values of said detected parameter the locations of said selected touch points on said impedance surfaces, and producing at least two electrical signals corresponding to said locations of said selected touch points.
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27. Apparatus for determining the location in two dimensions of a point through which electrical current flows in a current-conductive impedance surface, comprising
means making at least three spced apart electrical connections to said current conductive impedance surface, means for linearizing current flow through said at least three connections, means for simultaneously measuring the electrical currents flowing through said at least three connections to said point, and ratiometric means for determining the location of said point from said measurements of electrical current.
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28. In a touch panel system having a resistive surface defined by two opposed pairs of edge terminations on said surface, a line passing through each edge pair being orthogonal to a line passing through the other of said opposed pairs of edged terminations, said edge terminations having terminals for connection to external electrical circuitry, improvement in the means for locating a selected touch point on said surface comprising
means for maintaining the terminals of said edge termination at a predetermined instantaneous electrical potential, means for creating a potential difference between the terminals of said surface and a selected touch point on said surface through which electrical current passing through a human finger passes, and means for converting said current measurement to a utilization signal and applying said to a utilization device.
Specification