Capacitive touch panel with height determination function

• US 10,126,883 B2
• Filed: 07/03/2012
• Issued: 11/13/2018
• Est. Priority Date: 07/03/2012
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Coulson, Michael Paul, Brown, Christopher James, Slamkul, Dauren
• Primary Examiner(s): Mengistu, Amare
• Assistant Examiner(s): Nadkarni, Sarvesh J
• Application Number:
  US13/541,423
• Publication Number:
  US 20140009428A1
• Time in Patent Office: 2,324 Days
• Field of Search: 345173-178
• CPC Class Codes: G06F 2203/04101 2.5D-digitiser, i.e. digitiser detecting the X/Y position of the input means, finger or stylus, also when it does not touch, but is proximate to the digitiser's interaction surface and also measures the distance of the input means within a short range in the Z direction, possibly with a separate measurement setup
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes
• 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: G06F 3/0448 Details of the electrode shape, e.g. for enhancing the detection of touches, for generating specific electric field shapes, for enhancing display quality

Abstract

A capacitive touch sensor includes a sensor substrate and an array of electrode elements formed over the sensor substrate. Each electrode element of the array includes at least one of a first electrode group comprising at least two drive electrodes and at least one sense electrode, or a second electrode group comprising at least two sense electrodes and at least one drive electrode. The respective electrodes of the first or second electrode group are arranged to form multiple capacitances over different coupling distances. A controller is operatively coupled to the array of electrode elements, the controller configured to determine a distance of an object relative to the surface of the touch sensor based on variations in the multiple capacitances.

Claims

1. A capacitive touch sensor, comprising:

a sensor substrate;

an array of electrode elements formed over the sensor substrate, each electrode element of the array including at least one of

a first electrode group comprising at least two drive electrodes and at least one sense electrode, or

a second electrode group comprising at least two sense electrodes and at least one drive electrode,

wherein the respective electrodes of the first or second electrode group are arranged to form multiple capacitances over different coupling distances, so that the field lines from the respective electrodes spread with different density at different heights with respect to the sensing plane; and

a controller operatively coupled to the array of electrode elements, the controller configured to measure a distance of an object relative to and perpendicular from a plane defined by the surface of the touch sensor based on independent measurement of the extent to which a drive signal, applied to at least one of the drive electrodes, is received by at least one of the sense electrodes, via at least two of the multiple capacitances of different coupling distances.

2. The touch sensor according to claim 1, wherein the electrode elements of the array comprise the second electrode group, and within the second electrode group a first sense electrode of the at least two sense electrodes is separated from the at least one drive electrode by a shorter distance, in a plane of the sensor substrate, than a second sense electrode of the at least two sense electrodes.

3. The touch sensor according to claim 2, wherein the first and second sense electrodes are arranged symmetrically.

4. The touch sensor according to claim 2, wherein the second sense electrode is patterned into interconnected diamonds, and the first sense electrode is split into a first part and a second part, the first and second parts arranged on respective sides of the second sense electrode such that the first sense electrode is closer to the at least one drive electrode than the second sense electrode.

5. The touch sensor according to claim 4, wherein the first part and the second part are electrically connected to each other.

6. The touch sensor according to claim 2, wherein the first sense electrode forms a first mutual coupling capacitance with the at least one drive electrode and the second sense electrode forms a second mutual coupling capacitance with the at least one drive electrode.

7. The touch sensor according claim 2, wherein a majority of the first sense electrode is separated from a first drive electrode of the respective electrode element by a shorter distance, in a plane of the sensor substrate, than the second sense electrode of the respective electrode element, and a majority of the second sense electrode is separated from a second drive electrode of an adjacent electrode element by a shorter distance, in a plane of the sensor substrate, than the first sense electrode.

8. The touch sensor according to claim 1, wherein the controller is configured to calculate a distance of an object relative to a planar surface of the touch panel based on a ratio of the changes in the drive to sense capacitances, said distance measured perpendicularly to the planar surface of the touch panel.

9. The touch sensor according to claim 1, wherein the electrode elements of the array comprise the first electrode group, and within the first electrode group a first drive electrode of the at least two drive electrodes is separated from the at least one sense electrode by a shorter distance, in a plane of the sensor substrate, than a second drive electrode of the at least two drive electrodes.

10. The touch sensor according to claim 9, wherein the at least two drive electrodes are arranged symmetrically.

11. The touch sensor according to claim 9, wherein the second drive electrode is patterned into interconnected diamonds, and the first drive electrode is split into a first part and a second part, the first part arranged on each side of the second drive electrode such that the first part is closer to the at least one sense electrode than the second drive electrode.

12. The touch sensor according to claim 9, wherein the first drive electrode forms a first mutual coupling capacitance with the at least one sense electrode and the second drive electrode forms a second mutual coupling capacitance with the at least one sense electrode.

13. The touch sensor according to claim 1, wherein the first or second electrode group comprises at least two drive electrodes arranged as drive electrode pairs and at least two sense electrodes arranged as sense electrode pairs, and

wherein one drive electrode of the drive electrode pair is split into first and second drive electrode parts and one sense electrode of the sense electrode pair is split into first and second sense electrode parts, and

the first drive electrode part is positioned adjacent to the first sense electrode part in a plane of the sensor substrate, and the first drive electrode part and the first sense electrode part are arranged between the second drive electrode part and the second sense electrode part.

14. The touch sensor according to claim 1, wherein the drive electrodes are interdigitated with the sense electrodes.

15. The touch sensor according to claim 1, wherein the controller is configured to access a look-up table corresponding to each electrode element in order to determine a position and distance of an object relative to the touch panel.

16. The touch sensor according to claim 1, wherein the first or second electrode group comprises three or more sense electrodes.

17. A capacitive touch panel system, comprising

a liquid crystal display;

and

the touch sensor according to claim 1 mounted to the liquid crystal display.

18. The touch panel system according to claim 17, wherein the controller is configured to:

provide a time varying voltage stimulus to the drive electrodes; and

measure a charge that flows from the sense electrodes in response to the time varying voltage stimulus.

19. The touch panel system according to claim 18, wherein the controller is further configured to determine a position and height of an object above the touch sensor based on the measured charge.

20. The touch panel system according to claim 18, wherein the controller is configured to:

perform a first measurement phase wherein a charge is measured that flows from each sense electrode in response to the first drive electrode being provided with a changing electric potential while the second drive electrode is held at a constant electric potential;

perform a second measurement phase wherein a charge is measured that flows from each sense electrode in response to the second drive electrode being provided with a changing electric potential while the first drive electrode is held at a constant electric potential; and

determine a position and distance of an object from the touch panel based on the measured charge obtained in the first and second measurement phases.

21. The touch panel system according to claim 18, wherein the controller is configured to:

perform a first measurement phase wherein a charge is measured that flows from each sense electrode in response to a positive voltage change provided to both the first drive electrode and the second drive electrode;

perform a second measurement phase wherein a charge is measured that flows from each sense electrode in response to a positive voltage change provided to the first drive electrode, while a negative voltage change is provided to the second drive electrode; and

determine a position and distance of an object from the touch panel based on the measured charge obtained in the first and second measurement phases.

22. The touch panel system according to claim 18, wherein the controller is configured to:

perform a first measurement phase wherein a charge is measured that flows from the first sense electrode and from the second sense electrode in response to a voltage stimulus applied to the first drive electrode while the second drive electrode is held at a constant electric potential;

perform a second measurement phase wherein a charge is measured that flows from the first sense electrode and the second sense electrode in response to a voltage stimulus applied to the second drive electrode while the first drive electrode is held at a constant electric potential;

determine a position and distance of an object from the touch panel based on the measured charge of the first and second sense electrodes obtained in the first and second measurement phases.

23. The touch panel system according to claim 18, wherein the controller is configured to:

perform a first measurement phase wherein a charge is measured that flows from the first sense electrode and from the second sense electrode in response to a positive change in electric potential applied to the first drive electrode and a negative change in electric potential is applied to the second drive electrode;

determine a position and distance of an object from the touch panel based on the measured charge of the first and second sense electrodes.

24. The touch panel system according to claim 18, wherein the controller is configured to:

determine a first capacitance between the drive electrode and a first sense electrode of the three sense electrodes;

determine a second capacitance between the drive electrode and a second sense electrode of the three sense electrodes;

determine a third capacitance between the drive electrode and a third sense electrode of the three sense electrodes;

determine the ratio of the change in the second capacitance to the change in the first capacitance;

determine the ratio of the change in the third capacitance to the change in the first capacitance;

compare the ratios to data stored in a lookup table; and

determine a position and distance of an object from the touch panel based on the comparison.

25. The touch panel system according to claim 18, wherein the controller is configured to determine a position and distance of an object from the touch panel based on a ratio of measured capacitance between the drive and sense electrodes.

26. The touch panel system according to claim 18, wherein the controller is configured to determine a position and distance of an object from the touch panel based on a difference in measured capacitance between the drive and sense electrodes.

27. The touch panel system according to claim 26, wherein the controller is further configured to apply a weight factor to at least one measured capacitance prior to determining the difference in capacitance.

28. The touch panel system according to claim 18, wherein the controller is configured to:

perform a first measurement phase wherein a charge is measured that flows from the first sense electrode and from the second sense electrode in response to a voltage stimulus applied to the first drive electrode while the second drive electrode is held at a constant electric potential;

perform a second measurement phase wherein a charge is measured that flows from the first sense electrode and the second sense electrode in response to a voltage stimulus applied to the second drive electrode while the first drive electrode is held at a constant electric potential;

determine a position and distance of an object from the touch panel based on a weighted summation of the measured charge of the first and second sense electrodes obtained in the first and second measurement phases.

29. The touch sensor according to claim 1, wherein the controller configured to measure the distance of the object relative to and perpendicular from the plane defined by the surface of the touch sensor based on independent and simultaneous measurement of the extent to which a drive signal, applied to at least one of the drive electrodes, is received by at least one of the sense electrodes, via at least two of the multiple capacitances of different coupling distances.