Electrographic tough sensor having reduced bow of equipotential field line therein

A position touch sensor having resistive electrodes which provides a linear output response over an enhanced proportion of the surface area of said sensor by reducing the bow of equipotential lines along edges of said sensor, which comprises:

• a resistive layer having a selected substantially uniform resistivity throughout said layer, said resistive layer defining perimeter edges;
• a resistance element positioned proximate each of said perimeter edges of said resistive layer for providing orthogonal electrical fields of said resistive layer, each of said resistance elements having opposite ends joined to proximate ends of adjoining resistance elements, each of said resistance elements comprising a plurality of substantially identical discontinuous and overlapping conductive units in electrical contact with said resistive layer, each of said units formed by at lease two parallel legs of a selected length in one direction substantially aligned along said edges, and at least one leg of said selected length in a second direction substantially aligned along said edges, said at least two legs electrically connected to said at least one leg, said at least two legs of one unit interleaved with said at 1east one leg of an adjacent unit, said legs of one unit separated from legs of the other a selected distance, said selected length and selected distance defining a selected resistance value along said resistance element with relationship to said resistivity of said resistive layer;
• a plurality of electrodes positioned on, and electrically connected to, said layer along a preselected symmetrical path proximate each perimeter edge of said layer, said electrodes each being electrically connected to selected positions along said resistance elements and having a selected center-to-center spacing and each electrode having an effective length along said path, said length and spacing of said electrodes, and said positions of connection to said resistance elements selected to produce a selected voltage gradient along said path of said electrodes to compensate for any voltage drop along said resistance element during operation of said sensor when said orthogonal fields are introduced into said resistive layer whereby said bow is reduced;
• and
• means for deriving output signals corresponding to coordinates of a selected point on said resistive layer.

A single sheet resistor type touch sensor which exhibits substantially reduced bow of the electric equipotential lines along edges thereof, which comprises:

• a substantially rectangular substrate having an upper and a lower face;
• a uniform resistive coating applied to a substantial portion of said upper face of said substrate, said resistive coating having a resistivity of between about 10 and about 10,000 ohms per square and defining perimeter edges having corners;
• a resistance element proximate each of said perimeter edges of said coating, said resistance elements having a resistance of about 6.5 to about 6500 ohms per foot, each resistance element joined to ends of adjoining resitance elements proximate said corners of said coating, each of said resistance elements comprising a plurality of substantially identical discontinuous and overlapping conductive units in electrical contact with said resistive coating, each of said units formed by at least two parallel legs of a selected length in on direction substantially aligned along said edges, and at least one leg of said selected length in a second direction substantially aligned along said edges, said at least two legs electrically connected to said at least one leg, said at least two legs of one unit interleaved with said at least one leg of an adjacent unit, said legs of one unit separated from legs of the adjacent unit a selected distance, said selected length and selected distance defining a selected linear resitance value along said resistance element with relationship to said resistivity of said resistive coating;
• circuitry attached to said junctions of said resistance elements to apply voltages to said resistance elements to produce orthogonal electric fields in said resistive coating;
• a plurality of conductive electrodes on, and in electrical contact with, said resistive coating aligned in a single path proximate said perimeter edges, said electrodes having a spacing and an effective length along said path whereby said electrodes produce an effective voltage gradient in said resistive coating which progressively decreases from proximate said corners to centerlines of said path to counteract voltage drop along said resistance elements due to said applied voltages from said circuitry and thereby substantially reduces any bow in equipotential lines produced in said resistive coating by said applied voltages to said resistance elements;
• and
• means for deriving output signals corresponding to coordinates of a selected point on said resistive coating.

A position touch sensor having resistive electrodes which provides a substantially linear output response over the total area of said sensor by substantially reducing the bow of equipotential lines along edges of said sensor, said equipotential lines produced when electric fields are introduced into said sensor, which comprises:

• a resistive layer having a selected substantially uniform resistivity throughout said layer, said resistive layer defining perimeter edges;
• a resistance element positioned proximate each of said perimeter edges of said resistive layer for providing orthogonal electrical fields to said resistive layer, each of said resistance elements having opposite ends joined to proximate ends of adjoining resistance elements, each of said resistance elements comprising a plurality of discontinuous units in electrical contact with said resistive layer, each of said units formd by at least one line of conductive material spaced from a line of conductive material of an adjacent unit to define a separation gap of a selected width and length whereby said width and length of said gap and said resistivity of said resistive layer establish a unit resistance value for said units;
• a plurality of electrodes positioned on, and electrically connected to, said resistive layer along a preselected symmetrical path proximate each perimeter edge of said layer, said electrodes each being electrically connected to selected positions along said resistance elements to introduce orthogonal electric fields in said resistive layer, said electrodes having a selected spacing and each electrode having an effective length along said path, said spacing and effective length of said electrodes selected to produce a selected voltage gradient at each of said electrode to compensate for any cumulative voltage drop along said resistance element perpendicular to current flow through said resistive layer during operation of said sensor when said orthogonal fields are introduced into said resistive layer whereby said bow of said equipotential lines is substantially reduced;
• and
• means for deriving output signals corresponding to coordinates of a selected point on said resistive layer.

A position touch sensor having resistive electrodes which provides a substantially linear output response over the total area of said sensor by substantially reducing the bow of equipotential lines along edges of said sensor, said equipotential lines produced when electric fields are introduced into said sensor, which comprises:

• a resistive layer having a selected substantially uniform resistivity throughout said layer, said resistive layer defining perimeter edges;
• a resistance element positioned proximate each of said perimeter edges of said resistive layer for providing orthogonal electrical fields to said resistive layer, each of said resistance elements having opposite ends joined to proximate ends of adjoining resistance elements, each of said resistance elements comprising a plurality of discontinuous and overlapping conductive units in electrical contact with said resistive layer, each of said units formed by at least two parallel legs of a selected length in one direction substantially aligned along said edges, and at least one leg of said selected length in a second direction substantially aligned along said edges, said at least two legs electrically connected to said at least one leg, said at least two legs of one unit interleaved with said at least one leg of an adjacent unit, said legs of one unit separated from legs of the other unit a selected distance, said selected length and selected distance of said legs defining a selected resistance value along said resistance element with relationship to said resistivity of said resistivity layer;
• a plurality of electrodes positioned on, and electrically connected to, said layer along a preselected symmetrical path proximate each perimeter edge of said resistive layer, said electrodes each being electrically connected to selected positions along said resistance elements to introduce orthogonal fields in said resistive layer, said electrodes having a selected spacing and each electrode having an effective length along said path, said spacing and effective length of said electrodes selected to produce a selected voltage gradient at each of said electrodes to compensate for any cumulative voltage drop along said resistance element perpendicular to current flow through said resistive layer during operation of said sensor when said orthogonal fields are introduced into said resistive layer whereby said bow of said equipotential lines is reduced;
• and
• means for deriving output signals corresponding to coordinates of a selected point on said resistive layer.

A single sheet resistor-type touch sensor which exhibits substantially reduced bow of the electric equipotential lines along edges thereof, said equipotential lines produced when electric fields are introduced into said sensor, which comprises:

• a substantially rectangular substrate having an upper and a lower face;
• a uniform resistive coating applied to a substantial portion of said upper face of said substrate, said resistive coating having a resistivity of between abvout 10 and about 10,000 ohms per square and defining perimeter edges having corners;
• a resistance element proximate each of said perimeter edges of said coating, said resistance elements having a selected resistance in ohms per foot of about 0.65 times said resistivity of said resistive coating, each resistance element joined to ends of adjoining resistance elements proximate said corners of said coating, each of said resistance elements comprising a plurality of discontinuous and overlapping conductive units in electrical contact with said resistive layer, each of said units formed by at least two parallel legs of a selected length in one direction substantially aligned along said edges and at least one leg of said selected length in a second direction substantially aligned along said edges, said at 1east two legs electrically connected to said at least one leg, said at least two legs of one unit interleaved with said at 1east one leg of an adjacent unit, said legs of one unit separated from legs of the adjacent unit a selected distance defining said selected resistance value along said resistance element with relationship to said resistivity of said resistive layer;
• circuitry attached to the junctions of said resistance elements to apply voltages to said resistance elements to produce orthogonal electric fields in said resistive coating;
• a plurality of conductivity electrodes, on, and in electrical contact with said resistive coating, and aligned in a single path proximate said perimeter edges of said coating, said electrodes having a spacing and an effective length along said path whereby said electrodes produce an effective voltage gradient at each of said electrodes which progressively decreases from proximate said corners to centerlines of said path to counteract a cumulative voltage drop along said resistance elements perpendicular to current flow through said resistive coating and thereby substantially reduce any bow in equipotential lines produced in said resistive coating by said applied volltages to said resistance elements;
• and
• means for deriving output signals corresponding to coordinates of a selected point on said resistive coating.