Apparatus and method for increasing accuracy of touch sensor

• US 7,148,881 B2
• Filed: 07/23/2002
• Issued: 12/12/2006
• Est. Priority Date: 01/11/2002
• Status: Expired due to Term

• Current Assignee: Wistron Corporation
• Original Assignee: Eturobtouch Technology Incorporated
• Inventors: Kuo, Peggy, Tseng, Vicky, Lee, Carry
• Primary Examiner(s): Liang, Regina
• Application Number:
  US10/200,122
• Publication Number:
  US 20030132920A1
• Time in Patent Office: 1,603 Days
• Field of Search: 345/173, 345/174, 178/18.01, 178/18.03, 178/18.05
• US Class Current: 345/173
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact

Abstract

An apparatus for increasing the sensing accuracy of a touch sensor comprises a transparent or translucent substrate; a conductive film coated on the upper surface of the substrate; a plurality of resistor elements printed in at least one or more than one row, wherein adjacent ends of individual resistor elements are joined at the junctions at or near the four corners by wires, and wherein first gaps are formed between each independent row of resistor elements; a plurality of insulator elements formed discontinuously formed by removing a part of the conductive film near the inner side of the resistor elements on the surface thereof, the removed portions thus forming the insulator elements which are arranged; in at least more than one row, on the inner side of the resistor elements; and a plurality of second gaps formed between each row of the plurality of insulator elements.

Claims

1. An apparatus for increasing the sensing accuracy of a touch sensor comprising:

a transparent or translucent substrate;

a conductive film very thinly coated on the upper surface of the substrate;

a plurality of resistor elements consisting of conductive material, each resistor element being in a linear shape parallel to an edge of said substrate printed in at least one or more than one row and in a discontinuous manner, on the upper surface of the conductive film at the perimeter thereof, wherein adjacent ends of individual resistor elements are joined at the junctions at or near the four corners by wires, and wherein first gaps are formed between each independent row of resistor elements;

a plurality of insulator elements, each insulator element being in linear shape parallel to an edge of said substrate discontinuously formed by removing a part of the conductive film near the inner side of the resistor elements on the surface thereof, the removed portions thus forming the insulator elements which are arranged in at least more than one row, on the inner side of the resistor elements; and

a plurality of second gaps formed between each row of the plurality of insulator elements;

wherein additional resistor elements and insulator elements are provided in a middle row between the inner arranged insulator elements and the outer-arranged resistor elements, the additional insulator elements located at the corners being preferably L-shape, and wherein additional first and second gaps are formed thereby for compensating and correcting the electrical field effect in this area, so as to further correct the equipotential lines in the middle row of additional resistor elements and insulator elements to generally straight lines.

2. An apparatus for increasing the sensing accuracy of a touch sensor as claimed in claim 1, wherein the substrate preferably consists of glass material or flexible plastic material, the conductive film preferably consists of indium tin oxide (ITO) material, and the resistor elements preferably consist of silver pastes or flit.

3. The apparatus of claim 1, wherein in the region of the inner side-arranged insulator elements, the plurality of second gaps further compensate and correct the electrical field generated in this region, and further correct the equipotential lines in these region to be disposed to straight lines.

4. A method for increasing the sensing accuracy of a touch sensor comprising the steps of:

(1) connecting lead wires respectively onto the voltage junctions at the four corners of a plurality of resistor elements each resistor element being in a linear shape parallel to an edge of said substrate;

(2) applying a positive electrode voltage to selected two of the junctions and applying OV voltage to the other two of the junctions;

(3) utilizing the resistive area formed by the discontinuous resistor elements located on the conductive film layer and the first gaps between adjacent resistor elements to reduce the current flowing through each individual resistor element so that a higher impedance value may be obtained on the surface of the conductive film, and to lower the field strength between the junctions of two corners, to thereby preliminarily minimize the degree of curvature of the equipotential lines; and

(4) utilizing the second gaps located between the rows of the plurality of insulator elements as resistive area, each insulator element being in linear shape parallel to an edge of said substrate whereby the blockage of the insulator elements causes the electrical field produced from the two ends of each resistor element to flow toward the second gaps, to thereby further effectively rectify the curvature of the equipotential lines generated from the resistor elements and first gaps, thus finally making the equipotential lines in the x direction and y direction of the electrical field on the conductive film straight or linear;

wherein additional resistor elements and insulator elements are provided in a middle row between the inner arranged insulator elements and the outer-arranged resistor elements, the additional insulator elements located at the corners being preferably L-shape, and wherein additional first and second gaps are formed thereby for compensating and correcting the electrical field effect in this area, so as to further correct the equipotential lines in the middle row of additional resistor elements and insulator elements to generally straight lines.

5. A method for increasing the sensing accuracy of a touch sensor as claimed in claim 4, wherein the equipotential lines S in the x-axis direction and the equipotential lines S1 in the y-axis direction sensed on the conductive film are all disposed to be straight lines, so that when the conductive film is touched within its active area, a very accurate voltage signal in the x-axis and y-axis directions can be obtained.

6. The method of claim 4, wherein in the region of the inner side-arranged insulator elements, the plurality of second gaps further compensate and correct the electrical field generated in this region, and further correct the equipotential lines in these region to be disposed to straight lines.