Capacitive touch sensor apparatus and system having branching electrodes and electrode array therefor

Abstract

A capacitive touch sensor includes a plurality of electrodes on a substrate and the position of a finger touching the sensor, which is determined by monitoring changes in output signal caused by capacitance changes due to the presence of a finger above or near the electrodes. The present invention provides a capacitive touch sensor device comprising a substrate and a plurality of touch sensor electrodes disposed on the substrate. Each of the electrodes includes a separate main electrode strip and one or more individual electrode strip branches extending from the main electrode strip.

Description

[Technical Field] [Comparison of relevant applications] This application claims priority to U.S. Provisional Application No. 62 / 609,851, filed on December 22, 2017, which is incorporated herein by reference in its entirety. This invention relates to capacitive touch sensing technology, and in particular to a capacitive touch sensor comprising at least a plurality of electrodes. [Previous Technology] Capacitive touch sensors (e.g., for touchscreens) typically comprise a two-dimensional, cross-shaped array of substantially transparent conductive electrodes disposed on a substrate layer. Each electrode typically extends from one edge of the screen to the opposite side and is usually made of indium tin oxide (ITO). The electrodes can be in the form of strips. Each strip can be a simple straight, narrow track or a track formed integrally by a series of interconnected pads (e.g., diamond-shaped pads) in a given axial direction. A protective top layer of glass or plastic typically covers the substrate layer and the conductive strips. Electronic signals with a frequency range (e.g., from 500 kHz to 30 MHz) can be input to electrodes (commonly or individually), while the effect of electrode impedance on the signal is monitored. When a human finger (or another component with some conductive material) applies pressure to one or more electrodes, it causes a change in capacitance, which is detectable and measurable. Therefore, by monitoring the output from each electrode, the location of the touch on the sensor can be determined. For two-dimensional sensing, two sets of overlapping electrodes in the vertical direction can be monitored, thereby determining the touch location on a two-dimensional plane. Traditional capacitive touch sensors can be configured using self-capacitance or mutual capacitance. The capacitance of a single electrode to ground is often referred to as its self-capacitance. In a self-capacitance touch sensor, the capacitance of each electrode relative to ground is detected individually. By sensing which electrodes have increased self-capacitance, the location of the finger touch can be determined. In mutual capacitance touch sensors, the mutual capacitance between vertical electrode pairs is detected. For example, in a grid of vertical and horizontal (X and Y) electrodes, the mutual capacitance between vertical X and Y electrode pairs is monitored. In a typical two-dimensional electrode grid, each X electrode is positioned to have an area very close to each Y electrode (thus generating mutual capacitance between each XY electrode pair). By sensing which X electrode is coupled to which Y electrode, the location of one or more finger touches can be determined in two dimensions. Typical interconnected diamond-patterned touchscreens exhibit rapid changes in self-capacitance and mutual capacitance in some areas and minimal capacitance changes in others when a finger glides across the electrodes. This "unevenness" makes it difficult and / or unreliable to resolve finger position with precision finer than the spacing between two parallel electrodes. However, making the electrode pattern finer may not improve overall functionality, as this reduces desired capacitance changes while increasing unwanted fixed capacitances, such as cross-capacitance and interference capacitance between multiple electrode traces around the sensor area. Reducing the size and spacing of the electrodes can also significantly increase the number of sensing channels required for a given sensor area and may reduce sensing speed due to the increased number of electrodes to drive and sense. [Summary of the Invention] Therefore, according to one aspect of the present invention, a capacitive touch sensor device includes: a substrate; a plurality of touch sensor electrodes disposed on the substrate, wherein each electrode includes: a separate main electrode strip; and one or more individual electrode strip branches extending from the main electrode strip. According to another aspect of the present invention, a capacitive touch sensor system includes: a touch sensor controller; and a capacitive touch sensor device operatively coupled to the controller, the capacitive touch sensor device including: a substrate; a plurality of touch sensor electrodes disposed on the substrate, wherein each electrode includes: a separate main electrode strip; and one or more individual electrode strip branches extending from the main electrode strip. According to another aspect of the invention, an electrode array for a capacitive touch sensor includes: a plurality of touch sensor electrodes, wherein each electrode includes: a further first-order electrode branch; and one or more individual higher-order electrode branches, the one or more individual higher-order electrode branches including one or more second-order electrode branches extending from the first-order electrode branch. In some embodiments, each of the one or more electrode strip branches includes a further first-order branch portion extending from the individual main electrode strip. In some embodiments, for each electrode, the individual first-order branch portion is substantially orthogonal to the individual main electrode strip. In some embodiments, each of the one or more electrode strip branches further includes one or more second-order branch portions extending from the first-order branch portion. In some embodiments, each of the one or more electrode strip branches further includes one or more tertiary branch portions extending from at least one of the one or more second-order electrode branch portions. In some embodiments, for each electrode, the individual one or more electrode strip branches of the electrode intersect with one or more electrode strip branches of at least another of the plurality of electrodes. In some embodiments, the plurality of touch sensor electrodes includes first and second sets of electrodes, the main electrode strips of the first set of electrodes being substantially parallel to each other, and the main electrode strips of the second set of electrodes being substantially parallel to each other and substantially orthogonal to the main electrode strips of the first set of electrodes. In some embodiments, for each of the first group of electrodes, the individual main electrode strip and the individual one or more electrode strip branches define a first pattern, and for each of the second group of electrodes, the individual main electrode strip and the individual one or more electrode strip branches define a second pattern. In some embodiments, the electrode strip branches of the plurality of electrodes do not intersect each other. In some embodiments, each electrode includes a plurality of interconnect pads. In some embodiments, the pads have variable sizes. In some embodiments, for each electrode, the size of each of the pads of the electrode is a function of one of the positions of the pad relative to the main electrode strip of the electrode. In some embodiments, the pads of the electrode strip branches are smaller than the pads of the main electrode strip. In some embodiments, the number of pads of the plurality of electrodes is at least four times the number of electrode crosses. Those skilled in the art will gain a better understanding of other forms and features of the invention after reading the detailed description of specific embodiments in this specification. [Simplified Explanation of the Diagram] The invention will be better understood below with reference to the accompanying drawings, in which: Figure 1 is a top view of an exemplary capacitive touch sensor panel; Figure 2 is a block diagram of a controller according to some embodiments; Figure 3 is a layout diagram of an exemplary electrode array for a capacitive touch sensor; Figure 4 is a layout diagram of an exemplary touch sensor electrode including a branch pattern according to some embodiments; Figure 5 is a layout diagram of an exemplary touch sensor electrode including another branch pattern according to some embodiments; Figure 6 shows three vertical ("X") electrodes, each in the form of the electrode of Figure 4; Figure 7 shows three horizontal ("Y") electrodes, each in the form of the electrode of Figure 5; Figure 8 is a top view of a touch sensor device 800 according to some embodiments, the touch sensor device 800 including a substrate and X and Y electrodes of Figures 6 and 7 combined on the substrate; Figure 9 shows a top view of the touch sensor device 800 of Figure 8; Figure 10 shows a top view of a modified version of the touch sensor device; Figure 11 shows a layout diagram of another exemplary electrode according to some embodiments; Figure 12 shows a layout diagram of another exemplary electrode according to some embodiments; Figure 13 shows a top view of a touch sensor device according to some embodiments, including the electrode forms shown in Figures 11 and 12; Figure 14 shows a view of a "cell" of the exemplary touch sensor device of Figure 13; Figure 15 shows a partial top view of another exemplary touch sensor device according to some embodiments; Figure 16 shows a partial top view of another exemplary touch sensor device according to some embodiments; Figure 17 shows a block diagram of an exemplary self-capacitance controller according to some embodiments; and Figure 18 shows a layout of an exemplary touch sensor electrode array according to some embodiments.

Implementation Method

Claims

1. A capacitive touch sensor device, comprising: a substrate; a plurality of touch sensor electrodes disposed on the substrate, wherein each touch sensor electrode includes a plurality of interconnected pads arranged as: a separate main electrode strip; and one or more individual electrode strip branches extending from the main electrode strip; wherein the plurality of touch sensor electrodes includes a first set of electrodes and a second set of electrodes and the first set of electrodes interleaved with the second set of electrodes, and, for each touch sensor electrode, the one or more individual electrode strip branches interleaved with at least another of the one or more individual electrode strip branches, such that the total number of the plurality of pads is at least eight times the total number of interleavings formed by the plurality of touch sensor electrodes.

2. The capacitive touch sensor device as claimed in claim 1, wherein each of the one or more electrode strip branches includes a further first-order branch portion extending from the individual main electrode strip.

3. The capacitive touch sensor device as claimed in claim 2, wherein for each of the touch sensor electrodes, the individual first-order branch portion is substantially orthogonal to the individual main electrode strip.

4. The capacitive touch sensor device as claimed in claim 3, wherein each of the one or more electrode strip branches further comprises one or more second-order branch portions extending from the first-order branch portion and substantially orthogonal to the individual first-order branch portion, and the individual first-order branch portion of the first group of electrodes and the one or more second-order branch portions do not intersect with the second group of electrodes, and the individual first-order branch portion of the second group of electrodes and the one or more second-order branch portions do not intersect with the first group of electrodes.

5. The capacitive touch sensor device as claimed in claim 4, wherein for each of the one or more electrode strip branches, the individual second-order branch portion is parallel to and laterally offset from the corresponding main electrode strip.

6. The capacitive touch sensor device as claimed in claim 2, wherein each of the one or more electrode strip branches further includes one or more second-order branch portions extending from the individual first-order branch portion.

7. The capacitive touch sensor device as claimed in claim 6, wherein each of the one or more electrode strip branches further includes one or more tertiary branch portions extending from at least one of the one or more second-order branch portions.

8. The capacitive touch sensor device as claimed in claim 1, wherein the main electrode strips of the first set of electrodes are substantially parallel to each other, and the main electrode strips of the second set of electrodes are substantially parallel to each other and substantially orthogonal to the main electrode strips of the first set of electrodes.

9. The capacitive touch sensor device as described in claim 8, wherein: For each of the first group of electrodes, the individual main electrode strip and the individual one or more electrode strip branches define a first pattern, and for each of the second group of electrodes, the individual main electrode strip and the individual one or more electrode strip branches define a second pattern.

10. The capacitive touch sensor device as claimed in claim 1, wherein the interlaced electrode strip branches do not cross each other.

11. The capacitive touch sensor device as claimed in claim 1, wherein the pads have variable dimensions.

12. The capacitive touch sensor device as claimed in claim 11, wherein for each of the touch sensor electrodes, the size of each of the pads of the touch sensor electrode is a function of one of the positions of the pad relative to the main electrode strip of the touch sensor electrode.

13. The capacitive touch sensor device as claimed in claim 12, wherein the pads of the electrode strip branches are smaller than the pads of the main electrode strip.

14. A capacitive touch sensor system comprising: a touch sensor controller; a capacitive touch sensor device operatively coupled to the controller, the capacitive touch sensor device comprising: a substrate; a plurality of touch sensor electrodes disposed on the substrate, wherein each touch sensor electrode comprises a plurality of interconnected pads arranged as: a separate main electrode strip; and one or more individual electrode strip branches extending from the main electrode strip, wherein the plurality of touch sensor electrodes comprises a first set of electrodes and a second set of electrodes and the first set of electrodes interleaved with the second set of electrodes, and, for each touch sensor electrode, the one or more individual electrode strip branches interleaved with at least another of the one or more individual electrode strip branches, such that the total number of the plurality of pads is at least eight times the total number of interleavings formed by the plurality of touch sensor electrodes.

15. The capacitive touch sensor system as claimed in claim 14, wherein each of the one or more electrode strip branches includes a further first-order branch portion extending from the individual main electrode strip.

16. The capacitive touch sensor system as claimed in claim 15, wherein for each of the touch sensor electrodes, the individual first-order branch portion is substantially orthogonal to the individual main electrode strip.

17. The capacitive touch sensor system as claimed in claim 16, wherein each of the one or more electrode strip branches further comprises one or more second-order branch portions extending from the first-order branch portion and substantially orthogonal to the individual first-order branch portion, and the individual first-order branch portion of the first group of electrodes and the one or more second-order branch portions do not intersect with the second group of electrodes, and the individual first-order branch portion of the second group of electrodes and the one or more second-order branch portions do not intersect with the first group of electrodes.

18. The capacitive touch sensor system as described in claim 17, wherein for each of the one or more electrode strip branches, the individual second-order branch portion is parallel to and laterally offset from the corresponding main electrode strip.

19. The capacitive touch sensor device as claimed in claim 15, wherein each of the one or more electrode strip branches further includes one or more second-order branch portions extending from the individual first-order branch portion.

20. The capacitive touch sensor device as claimed in claim 14, wherein the main electrode strips of the first set of electrodes are substantially parallel to each other, and the main electrode strips of the second set of electrodes are substantially parallel to each other and substantially orthogonal to the main electrode strips of the first set of electrodes.

21. An electrode array for a capacitive touch sensor, comprising: a plurality of touch sensor electrodes, wherein each touch sensor electrode includes a plurality of interconnected pads arranged as: a separate main electrode strip; and one or more individual electrode strip branches, each including: a separate first-order electrode branch extending from the main electrode strip; and one or more individual higher-order electrode branches, the one or more individual higher-order electrode branches including one or more second-order electrode branches extending from the first-order electrode branches, wherein the plurality of touch sensor electrodes includes a first set of electrodes and a second set of electrodes and the first set of electrodes is interleaved with the second set of electrodes, and, for each touch sensor electrode, the one or more individual electrode strip branches are interleaved with at least another one of the one or more individual electrode strip branches, such that the total number of the plurality of pads is at least eight times the total number of interleavings formed by the plurality of touch sensor electrodes.

22. The electrode array of the capacitive touch sensor as claimed in claim 21, wherein each of the individual first-order electrode branches extends substantially orthogonally from the corresponding main electrode strip, and each of the individual second-order electrode branches is substantially orthogonal to the corresponding first-order electrode branch, and the individual first-order branch portion of the first group of electrodes and the one or more second-order branch portions do not intersect with the second group of electrodes, and the individual first-order branch portion of the second group of electrodes and the one or more second-order branch portions do not intersect with the first group of electrodes.

23. The electrode array of the capacitive touch sensor as described in claim 22, wherein for each of the one or more electrode strip branches, the individual second-order branch portion is parallel to and laterally offset from the corresponding main electrode strip.

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