Touch sensitive devices with composite electrodes

• US 8,405,633 B2
• Filed: 08/22/2012
• Issued: 03/26/2013
• Est. Priority Date: 08/01/2008
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Geaghan, Bernard O.
• Primary Examiner(s): Lao, Lun-Yi
• Assistant Examiner(s): Siddiqui, Saiful A
• Application Number:
  US13/591,327
• Publication Number:
  US 20120313893A1
• Time in Patent Office: 216 Days
• Field of Search: 345156-158, 345/173, 178 1801- 1809, 463 37- 38
• US Class Current: 345/173
• CPC Class Codes: G06F 2203/04112 Electrode mesh in capacitive digitiser: electrode for touch sensing is formed of a mesh of very fine, normally metallic, interconnected lines that are almost invisible to see. This provides a quite large but transparent electrode surface, without need for ITO or similar transparent conductive material
• CPC Class Codes: G06F 3/04164 Connections between sensors and controllers, e.g. routing lines between electrodes and connection pads
• CPC Class Codes: G06F 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes
• CPC Class Codes: Y10T 156/10 Methods of surface bonding and/or assembly therefor
• CPC Class Codes: Y10T 29/49117 Conductor or circuit manufacturing
• CPC Class Codes: Y10T 29/49124 On flat or curved insulated base, e.g., printed circuit, etc.
• CPC Class Codes: Y10T 29/49128 Assembling formed circuit to base
• CPC Class Codes: Y10T 29/49155 Manufacturing circuit on or in base

Abstract

A matrix touch panel having upper and lower electrodes, the upper electrodes being composite electrodes made of a plurality of spaced micro-wires, and allowing, for example, an electric field from lower electrodes to pass between the micro-wires and thereby capacitively couple with a touching object, such as a finger.

Claims

1. A multi-layer touch panel, comprising:

a first layer comprising a transparent touch surface;

an upper electrode array and a lower electrode array defining an electrode matrix having nodes where the upper and lower electrodes cross over, and wherein the upper electrode array is disposed between the first layer and the lower electrode layer, wherein electrodes of the upper and lower electrode arrays comprise a plurality of composite electrodes comprised of a plurality of metal or metal alloy micro-wire conductors having a cross-sectional dimension of less than 10 microns;

a dielectric disposed between the upper electrode array and the lower electrode array;

wherein electrodes of the upper electrode layer are configured to be more pervious to an electric field than electrodes in the lower electrode layer.

2. The multi-layer touch panel of claim 1, wherein configured to be pervious comprises allowing an electric field to pass through spaces in the electrode.

3. The multi-layer touch panel of claim 1, wherein electrodes of the lower electrode layer are substantially isotropic.

4. The multi-layer touch panel of claim 1, wherein the micro-wires have a maximum cross-sectional dimension of less than 9 microns.

5. The multi-layer touch panel of claim 4, wherein the number of micro-wire conductors that comprise at least one of the electrodes of the first electrode layer is between the range of 2 and 10, inclusive.

6. The multi-layer touch panel of claim 1, wherein the micro-wires have a maximum cross-sectional dimension of less than 3 microns.

7. The multi-layer touch panel of claim 1, wherein the micro-wires have a maximum cross-sectional dimension of less than 5 microns.

8. The multi-layer touch panel of claim 1, wherein the micro-wires have a maximum cross-sectional dimension of between 1 and 4 microns.

9. The multi-layer touch panel of claim 1, wherein the micro-wires of the first electrode layer cover two percent or less of the surface area of the upper electrode layer.

10. The multi-layer touch panel of claim 1, wherein the center-to-center spacing of the micro-wire conductors that comprise at least one of the electrodes of the lower electrode array is less than the center-to-center spacing of the micro-wire conductors that comprise at least one of the electrodes of the upper electrode array.

11. The multi-layer touch panel of claim 10, wherein the center-to-center spacing of the micro-wire conductors that comprise the at least one electrode of the lower electrode array is at least four times less than the center-to-center spacing of the micro-wire conductors that comprise the at least one electrode of the upper electrode array.

12. The multi-layer touch panel of claim 1, wherein the micro-wire conductors that comprise the electrodes of the first electrode layer are substantially uniformly spaced on the upper electrode layer.

13. The multi-layer touch panel of claim 1, wherein the center-to-center spacing of the micro-wire conductors that comprise at least one of the electrodes of the first electrode layer is less than 4 mm.

14. The multi-layer touch panel of claim 13, wherein the micro-wire conductors that comprise at least one electrode of the first electrode layer electrode include conductor bridges.

15. The multi-layer touch panel of claim 1, further comprising:

a drive circuit configured to electrically drive at least one of the lower electrodes; and

,

a receive circuit configured to sense signals indicative of capacitance between an electrode in the upper electrode layer and an electrode in the lower electrode layer.

16. The multi-layer touch panel of claim 1, further comprising:

a drive circuit configured to electrically drive at least one of the lower electrodes; and

,

a measurement circuit configured to sense signals indicative of capacitance between an electrode in the lower electrode layer and a ground reference voltage.

17. The multi-layer touch panel of claim 1, further comprising:

a drive circuit configured to electrically drive at least one electrode in upper electrode layer; and

,

a receive circuit configured to sense signals indicative of capacitance between the at least one electrode in the lower electrode layer and a ground reference voltage.

18. A method for identifying locations of touches or near-touches on a touch sensitive apparatus, comprising:

sensing, with an electronic controller, a value indicative of the change of mutual capacitance between an overlapping first electrode and a second electrode disposed in a matrix-type touch sensor, the change in mutual capacitance induced by the presence of an object proximate to the touch sensor, wherein the first and second electrodes are metal or metal alloy electrodes comprised of a plurality of micro-wire conductors having an average cross-sectional dimension of less than 10 microns;

wherein the electrode positioned closer to the touches or near-touches defines an upper electrode, and the other electrode defines a lower electrode, and wherein the upper electrode is more pervious to an electric field than the lower electrode.

19. The method of claim 18, wherein the more pervious comprises a greater tendency to allow coupling of an electric field from a lower electrode through spaces in the upper electrode layer.

20. The method of claim 18, wherein the micro-wire conductors have a maximum cross-sectional dimension of less than 5 microns.

21. The method of claim 18, wherein the center-to-center spacing of the micro-wire conductors that comprise the first electrode is less than 4 mm.

22. The method of claim 18, wherein the number of micro-wire conductors that comprise the composite conductor is between 2 and 10.

23. The method of claim 18, wherein the lower electrode is isotropic.