Capacitive Touch Screen with Noise Suppression

• US 20100044122A1
• Filed: 04/10/2009
• Published: 02/25/2010
• Est. Priority Date: 04/10/2008
• Status: Active Grant

• Current Assignee: Neodrón Limited (Atlantic IP Services Limited), QRG Limited
• Original Assignee: Atmel Corporation (Microchip Technology Incorporated)
• Inventors: Sleeman, Peter, Trend, Matthew, Brunet, Samuel, Philipp, Harald
• Granted Patent: US 9,823,784 B2
• Time in Patent Office: Days
• US Class Current: 178/18.60
• CPC Class Codes: G01B 2210/58 Wireless transmission of information between a sensor or probe and a control or evaluation unit
• CPC Class Codes: G01B 7/003 for measuring position, not involving coordinate determination coordinate measuring G01B7/004
• CPC Class Codes: G01D 5/2405 by varying dielectric
• CPC Class Codes: G06F 1/16 Constructional details or arrangements
• CPC Class Codes: G06F 2203/04111 Cross over in capacitive digitiser, i.e. details of structures for connecting electrodes of the sensing pattern where the connections cross each other, e.g. bridge structures comprising an insulating layer, or vias through substrate
• 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 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/041661 using detection at multiple resolutions, e.g. coarse and fine scanning; using detection within a limited area, e.g. object tracking window
• 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: H03K 17/9622 using a plurality of detectors, e.g. keyboard
• CPC Class Codes: H05K 1/0296 Conductive pattern lay-out details not covered by sub groups H05K1/02 - H05K1/0295 H05K1/11 takes precedence; lay-out adapted to mounted component configuration H05K1/18

Abstract

A capacitive touch sensor wherein the touch sensitive panel has drive electrodes arranged on the lower side of a substrate and sense electrodes arranged on the upper side. The drive electrodes are shaped and dimensioned to substantially entirely cover the touch sensitive area with individual drive electrodes being separated from each other by small gaps, the gaps being so small as to be practically invisible. The near blanket coverage by the drive electrodes also serves to screen out interference from noise sources below the drive electrode layer, such as drive signals for an underlying display, thereby suppressing noise pick-up by the sense electrodes that are positioned above the drive electrodes.

Claims

1. A capacitive touch sensor comprising a touch sensitive panel having a plurality of drive electrodes arranged on one side of a substrate in a first layer and a plurality of sense electrodes arranged on the other side of the substrate in a second layer so that the sense electrodes cross the drive electrodes at a plurality of intersections offset from each other by the thickness of the substrate, wherein the drive electrodes substantially entirely cover the first layer with individual ones of the drive electrodes being separated from neighboring drive electrodes by small gaps.

2. The capacitive touch sensor of claim 1, wherein the drive electrodes have a pitch of comparable dimension to the touch size of the touching object for which the sensor is designed.

3. The capacitive touch sensor of claim 2, wherein the touching object for which the sensor is designed is a finger, and the pitch is around 8 mm or less.

4. The capacitive touch sensor of claim 1, wherein the small gaps are dimensioned to be sufficiently small to be invisible or almost invisible.

5. The capacitive touch sensor of claim 1, wherein the small gaps between drive electrodes are less than around 100 micrometers.

6. The capacitive touch sensor of claim 1, wherein the sense electrodes are narrow in comparison to the size of the touching object.

7. The capacitive touch sensor of claim 2, wherein the sense electrodes have a line width one quarter or less than the pitch of the drive electrodes.

8. The capacitive touch sensor of claim 3, wherein the sense electrodes have a line width one quarter or less than the pitch of the drive electrodes.

9. The capacitive touch sensor of claim 1, wherein the second layer additionally accommodates isolated elements arranged between the sensing electrodes so that the sense electrodes and the isolated elements together substantially entirely cover the second layer with individual ones of the sense electrodes and isolated elements being separated from each other by small gaps.

10. The capacitive touch sensor of claim 1, wherein the first and second layers of electrodes are the only electrode layers provided.

11. The capacitive touch sensor of claim 1, further comprising a display module arranged below the first layer.

12. The capacitive touch sensor of claim 1, wherein each drive and/or sense electrode is made of a continuous sheet of electrically conductive material.

13. The capacitive touch sensor of claim 1, wherein each drive and/or sense electrode is made of a mesh or filigree pattern of interconnected lines of highly conductive material which collectively define each electrode.

14. The capacitive touch sensor of claim 13, wherein the interconnected lines have a sufficiently small width so as to be invisible or almost invisible.

15. The capacitive touch sensor of claim 1, wherein the drive electrodes extend in a first linear direction and the sense electrodes extend in a second linear direction transverse to the first linear direction so that the plurality of intersections form a grid pattern.

16. The capacitive touch sensor of claim 1, wherein the drive electrodes extend arcuately and the sense electrodes extend radially so that the plurality of intersections lie on one or more arcuate paths.

17. A touch sensitive panel for a capacitive touch sensor, the touch sensitive panel having a plurality of drive electrodes arranged in a first layer and a plurality of sense electrodes arranged in a second layer so that the sense electrodes cross the drive electrodes at a plurality of intersections offset from each other, wherein the drive electrodes substantially entirely cover the first layer with individual ones of the drive electrodes being separated from neighboring drive electrodes by small gaps.

18. The panel of claim 17, wherein the first and second layers are disposed on opposite sides of a common substrate offset from each other by the thickness of the substrate.

19. The panel of claim 17, wherein the first and second layers are disposed on respective first and second substrates.

20. A method of manufacturing a touch sensitive panel for a capacitive touch sensor comprising:

providing a substrate having first and second sides;

depositing on the first side of the substrate a first layer of conductive material in a first pattern forming a plurality of drive electrodes, wherein the drive electrodes substantially entirely cover the first layer with individual ones of the drive electrodes being separated from neighboring drive electrodes by small gaps; and

depositing on the second side of the substrate a second layer of conductive material in a second pattern forming a plurality of sense electrodes so that the sense electrodes cross the drive electrodes at a plurality of intersections offset from each other by the thickness of the substrate.