MULTIPLE ELECTRODE TOUCH SENSITIVE DEVICE

• US 20100164889A1
• Filed: 12/21/2009
• Published: 07/01/2010
• Est. Priority Date: 12/26/2008
• Status: Active Grant

• Current Assignee: Neodrón Limited (Atlantic IP Services Limited)
• Original Assignee: Atmel Corporation (Microchip Technology Incorporated)
• Inventors: Hristov, Luben, Philipp, Harald
• Granted Patent: US 8,704,779 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• 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 3/04164 Connections between sensors and controllers, e.g. routing lines between electrodes and connection pads
• 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

Abstract

Two different sets of electrodes in a touch sensitive device are formed to produce an electric field gradient from one end of the electrodes to the other end when opposite ends of the electrodes are driven with different voltages. A signal measuring cycle is performed by alternately driving the ends of one set of electrodes, while using the other set of electrodes to receive signals. The roles of the sets of electrodes are then reversed, such that the set that that was driven is now used to receive signals from the other set of electrodes. Reference signals may be obtained by driving both sides of one set of electrodes, and then both sides of the other set of electrodes. The signals obtained are then used to determine the touch position on the touch sensitive device.

Claims

1. A controller comprising:

a driver to provide signals to drive electrodes of a touch sensitive device, wherein the driver provides multiple sets of drive signals to at least four different drive lines to separately couple to both ends of two sets of electrodes having electric field gradients and wherein the sets of electrodes are arranged to exchange signals; and

a receiver to receive multiple sets of exchanged signals from both sets of electrodes responsive to the signals provided by the driver.

2. The controller of claim 1 wherein the multiple sets of drive signals include:

four drive signals to be provided to each end of both sets of electrodes;

a drive signal to be provided to both ends of one set of electrodes; and

a drive signal to be provided to both ends of the other set of electrodes.

3. The controller of claim 2 and further comprising a processor to determine a touch position responsive to the exchanged signals received by the receiver.

4. The controller of claim 3 wherein exchanged signals received as a result of the drive signals being provided to both ends of the sets of electrodes are reference signals.

5. The controller of claim 3 wherein when the four drive signals to be provided to an end of a set of electrodes are each provided while the other end of the set of electrodes is held at a reference voltage.

6. The controller of claim 1 wherein the exchanged signals are obtained from either end of the sets of electrodes.

7. The controller of claim 1 wherein the driver provides drive signals in the form of bursts of pulses.

8. The controller of claim 7 wherein the pulses are provided in six different sets of bursts corresponding to six different measurements.

9. The controller of claim 8 wherein four of the sets of bursts correspond to driving four different corresponding ends of the two sets of electrodes.

10. The controller of claim 9 wherein two of the sets of bursts correspond to driving both ends of each of the two sets of electrodes.

11. The controller of claim 1 wherein the controller is configured to selectively drive both sets of electrodes at the same time to operate in a proximity detection mode.

12. The controller of claim 1 wherein exchanged signals are obtained from sense circuitry coupled to one set of electrodes and sense circuitry coupled to a second set of electrodes.

13. The controller of claim 12 wherein each of the sense circuitry comprises a single sense capacitor corresponding to each set of electrodes.

14. A method comprising:

alternately driving different ends of a first set of electrodes of a touch sensitive device;

measuring signals transferred from the first set of electrodes to a second set of electrodes;

alternatively driving different ends of the second set of electrodes of a touch sensitive device; and

measuring signals transferred from the second set of electrodes to the first set of electrodes.

15. The method of claim 14 and further comprising:

driving both ends of the first set of electrodes;

measuring signals transferred from the first set of electrodes to the second set of electrodes resulting from driving both ends to obtain a first reference signal;

driving both ends of the second set of electrodes; and

measuring signals transferred from the second set of electrodes to the first set of electrodes resulting from driving both ends to obtain a second reference signal.

16. The method of claim 14 and further comprising determining a touch position signal from signals resulting from the measuring of transferred signals.

17. A touch sensitive device comprising:

a plurality of x electrodes having two ends coupled to form an electric field gradient between the ends of the x electrodes when either end is driven; and

a plurality of y electrodes arranged to exchange signals with the x electrodes and having two ends coupled to form an electric field gradient between the ends of the y electrodes when either end is driven.

18. The touch sensitive device of claim 17 wherein the x electrodes and y electrodes are orthogonal to each other.

19. The touch sensitive device of claim 18 wherein the x electrode and y electrodes are formed in separate layers.

20. The touch sensitive device of claim 17 wherein the x electrodes and y electrodes are substantially parallel to each other and are formed in the same layer.

21. The touch sensitive device of claim 17 wherein the electrodes are formed of metal.

22. The touch sensitive device of claim 17 wherein the electrodes are formed of a transparent conductive material.

23. The touch sensitive device of claim 22 wherein the material comprises ITO.

24. The touch sensitive device of claim 22 wherein the x electrodes are coupled by a resistive chain to provide the electric field gradient and the y electrodes are formed of strips of transparent conductive material that are narrower than the x electrodes to provide the electric field gradient.

25. The touch sensitive device of claim 17 and further comprising resistive chains coupled to each of the x electrodes and the y electrodes to provide the gradient.

26. The touch sensitive device of claim 17 wherein the x electrodes and y electrodes are formed in a diamond pattern.

27. The touch sensitive device of claim 26 wherein the diamond pattern comprises split diamond connected by a conductive bar to enhance the gradient.