Touchscreen having multiple parallel connections to each electrode in a series resistor chain on the periphery of the touch area

• US 6,593,916 B1
• Filed: 11/03/2000
• Issued: 07/15/2003
• Est. Priority Date: 11/03/2000
• Status: Expired due to Term

• Current Assignee: Elo Touch Solutions, Inc.
• Original Assignee: Elo Touchsystems Incorporated (Elo Touch Solutions, Inc.)
• Inventors: Aroyan, James L.
• Primary Examiner(s): Shalwala, Bipin
• Assistant Examiner(s): Dharia, Prabodh M.
• Application Number:
  US09/705,383
• Time in Patent Office: 984 Days
• Field of Search: 345/156, 345/173, 345/176, 345/177, 345/178, 345/174, 345/180, 178/18-1-, 178/19-1-, 178/20-1-
• US Class Current: 345/173
• CPC Class Codes: G06F 2203/04113 Peripheral electrode pattern in resistive digitisers, i.e. electrodes at the periphery of the resistive sheet are shaped in patterns enhancing linearity of induced field
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact

Abstract

A resistive or capacitive position touchscreen includes a glass substrate having a uniform resistive coating and series resistive chains of overlapping discrete electrodes adjacent to the peripheral edges of the substrate. Gaps in an otherwise insulating linear discontinuity running parallel to each chain form resistive current paths across the touch area. There are at least two gaps for each electrode so that multiple current paths connect to each electrode. Each gap produces a local ripple in the voltage field which decays away with distance from the gap. Since the ripple decay length is determined by the distance between current paths, the magnitude of the ripple near the electrodes is reduced exponentially by a factor corresponding to the number of gaps per electrode.

Claims

1. A position touchscreen comprising

a substrate having a resistive surface bounded by four peripheral edges which terminate at four corners, said resistive surface having a touch area interior to said edges,

a series resistor chain proximate each of said peripheral edges for creating electric fields across said touch area, each resistor chain comprising a plurality of conductive electrodes arranged in series with resistive regions of said surface therebetween, each electrode having an inside portion facing said touch area, the inside portions of adjacent electrodes being separated by junctions, and

a linear array of insulating regions in said resistive surface adjacent to each resistor chain between said resistor chain and said touch area, said linear array of insulating regions acting as electrical insulators, each said insulating regions being separated by gaps where said resistive surface is intact,

wherein a plurality of gaps are positioned between a majority of each of said inside portions and said touch area thereby forming a plurality of conductive paths per said majority of inside portions across said touch area.

2. A position touchscreen as in claim 1 wherein none of said gaps are positioned between the junctions and the touch area.

3. A position touchscreen as in claim 1 wherein some of said gaps are positioned between the junctions and the touch area.

4. A position touchscreen as in claim 1 wherein each said insulating region runs parallel to said adjacent series resistor chain.

5. A position touchscreen as in claim 1 wherein said array of insulating regions is a line where said resistive surface has been removed, said line being parallel to said adjacent series resistor chain.

6. A position sensor as in claim 1 wherein at least some of said electrodes are Z-shaped electrodes, each Z-shaped electrode having an outside portion connected to said inside portion, at least some of said inside portions being parallel to respective said outside portions of adjacent electrodes.

7. A position sensor as in claim 6 wherein said electrodes further comprise a central bar electrode in each series chain, each said bar electrode being overlapped by outer portions of adjacent Z-shaped electrodes.

8. A position sensor as in claim 7 wherein said electrodes further comprise a right angle electrode at each corner, each said right angle connector overlapping an inner portion of one of said Z-shaped electrodes in each of two series chains, said right angle electrodes providing voltage inputs to each series chain.