Lattice touch-sensing system

• US 6,970,160 B2
• Filed: 12/19/2002
• Issued: 11/29/2005
• Est. Priority Date: 12/19/2002
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Badaye, Massoud, Lim, Brian G., Mulligan, Roger C., Wong, Alex K.
• Primary Examiner(s): Shankar, Vijay
• Assistant Examiner(s): DHARIA, PRABODH M
• Application Number:
  US10/324,728
• Publication Number:
  US 20040119701A1
• Time in Patent Office: 1,076 Days
• Field of Search: 345173-179, 345/156, 345/1, 345/2, 345/903, 345/126, 345/169, 345/184, 345/158, 178 1801- 1809, 178 1901- 1903, 178/20.01
• US Class Current: 345/173
• 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: H03K 2217/960755 Constructional details of capacitive touch and proximity switches

Abstract

This invention is directed to a lattice touch-sensing system for detecting a position of a touch on a touch-sensitive surface. The lattice touch-sensing system may include two capacitive sensing layers, separated by an insulating material, where each layer consists of substantially parallel conducting elements, and the conducting elements of the two sensing layers are substantially orthogonal to each other. Each element may comprise a series of diamond shaped patches that are connected together with narrow conductive rectangular strips. Each conducting element of a given sensing layer is electrically connected at one or both ends to a lead line of a corresponding set of lead lines. A control circuit may also be included to provide an excitation signal to both sets of conducting elements through the corresponding sets of lead lines, to receive sensing signals generated by sensor elements when a touch on the surface occurs, and to determine a position of the touch based on the position of the affected bars in each layer.

Claims

1. A device comprising a touch-sensitive screen comprising:

a touching surface;

a first sensor layer including;

a first set of capacitive sensor bars disposed in a first direction, each of the first set of capacitive sensor bars having a first end and a second end, wherein the first end of each of the first set of capacitive sensor bars is connected to one of a first set of lead lines;

a second sensor layer including;

a second set of capacitive sensor bars disposed in a second direction, the second direction being substantially orthogonal to the first direction, each of the second set of capacitive sensor bars having a first end and a second end, wherein the first end of each of the second set of capacitive sensor bars is connected to one of a second set of lead lines; and

a non-conductive layer separating the first sensor layer from the second sensor layer,

wherein the touch-sensitive screen is mounted within the device, the area around the touch-sensitive screen being sized in accordance with a reduced number of lead lines on the second ends of the sensor bars in the first set of capacitive sensor bars.

2. The device of claim 1, wherein the first set of capacitive sensor bars and the second set of capacitive sensor bars are substantially orthogonal.

3. The device of claim 1, wherein each of the second set of capacitive sensor bars is connected at only one end to one of a second set of lead lines.

4. The device of claim 1, wherein the first set of capacitive sensor bars and the second set of capacitive sensor bars are constructed of indium tin oxide.

5. The device of claim 1, wherein a touch to the touching surface is experienced by a first sensor bar in the first set of capacitive sensor bars and a second sensor bar in the second set of capacitive sensor bars, the position of the touch on the touching surface being determined according to a position of the first sensor bar in the second direction and a position of the second sensor bar in the first direction.

6. The device of claim 1 wherein each of the second ends of the first set of sensor bars are connected to the first set of lead lines, and the second ends of the second set of sensor bars are connected to the second set of lead lines.

7. The device of claim 1, wherein each of the second ends of first set of sensor bars are not connected to the first set of lead lines, and the second ends of the second set of sensor bars are not connected to the second set of lead lines.

8. The device of claim 1, wherein the area around the touch-sensitive screen is sized in additional accordance with a lack of lead lines on the second ends of the sensor bars in the second set of sensor bars.

9. The device of claim 1, wherein the first and second set of capacitive sensor bars each comprises

rows of patches of conductive material and depletion areas between the patches of conductive material,

the rows of the first and second sets of sensor bars being configured such that the patches of the first set of sensor bars are disposed within the depletion areas of the second set of sensor bars, and the patches of the second set of sensor bars are disposed with the depletion areas of the first set of sensor bars.

10. The device of claim 9, wherein the patches of conductive material of the first and second sets of sensor bars are configured in a substantially diamond shape.

11. The device of claim 9, wherein, on each set of sensor bars, the patches of conductive material are connected with strips of conductive material.

12. A method for identifying a location of a touch on a touch-sensitive screen, comprising:

receiving a first signal and a second signal, the first signal being associated with a first sensor bar on the touch-sensitive screen, the second signal being associated with a second sensor bar on the touch-sensitive screen, the first and second sensor bars being disposed in two different layers of sensor bars, the sensor bars of the two different layers extending in two different directions, and being connected to lead lines at a first end of the sensor bars;

analyzing the first signal and the second signal to identify the first sensor bar and the second sensor bar, wherein the first sensor bar has a corresponding position, and the second sensor bar has a corresponding position;

analyzing secondary signals on one or more sensor bars neighboring the first sensor bar or the second sensor bar; and

locating the touch through analysis of the position of the first sensor bar and the second sensor bar, and further refinement through analysis of the secondary signals; and

wherein the touch-sensitive screen is mounted within a device, the area around the touch-sensitive screen being sized in accordance with a reduced number of lead lines on the second ends of the sensor bars in the first set of capacitive sensor bars.

13. The method as in claim 12, wherein the sensor bars of the two different layers are further connected at a second end of the sensor bar.

14. The method as in claim 12, wherein the sensor bars of the two different layers are connected at only the first end of the sensor bar.

15. The method of claim 12, further comprising generating a set of coordinates corresponding to the location of the touch and providing the coordinates to a computing device for further processing.

16. The method of claim 12, wherein the two different directions comprise substantially orthogonal directions.

17. The method of claim 12, wherein the first sensor bar is one of a plurality of sensor bars in a first layer of sensor bars, and the second sensor bar is one of another plurality of sensor bars in a second layer of sensor bars, the first and second layers of sensor bars being separated by a dielectric material.

18. The method of claim 17, wherein the first end of each of the sensor bars in the first layer of sensor bars is connected to at least one of a plurality of lead lines, and the first end each of the sensor bars in the second layer of sensor bars is connected to at least one of the plurality of lead lines.

19. The method of claim 17, wherein the first ends of at least two of the sensor bars of the sensor layers are connected to the same lead line and a signal-processing scheme is used to distinguish which of the jointly-connected sensor bars experienced the touch.

20. The method of claim 19, wherein the first ends of at least two of the sensor bars in the other sensor layer are connected to the same lead line and a signal-processing scheme is used to distinguish which of the jointly-connected sensor bars experienced the touch.

21. The method of claim 12, wherein analyzing the first and second signals comprises identifying a first coordinate in a first direction corresponding to the first sensor bar and identifying a second coordinate in a second direction corresponding to the second sensor bar, the first and second directions being about orthogonal in the plane of the touch-sensitive screen.

22. The method of claim 21, wherein analysis of the position of the first sensor bar and the second sensor bar comprises evaluating the location identified by the first coordinate in the first direction and the second coordinate in the second direction.