Mutual hover protection for touch screens

Abstract

The present invention discloses a touch sensor and method for detecting touch in a capacitive touch screen application, wherein the touch sensor is capable of distinguishing between a finger hovering over the touch sensor and a touch from a stylus having a small contact surface area without having to adjust the sensitivity of the touch sensor. The touch sensor includes a first sensing electrode, a transmission electrode, and a second sensing electrode, wherein the second sensing electrode is substantially positioned around the periphery of an internal circuit (i.e., the transmission electrode and the first sensing electrode). Touch is detected by sensing a change in a first capacitance between the transmission electrode and the first sensing electrode and a change in a second capacitance between the transmission electrode and the second sensing electrode. The change in the first capacitance and the change in the second capacitance are compared to determine whether the changes in the capacitances are due to a finger hovering or due to a touch.

Description

[0001] This application is a divisional application of the Chinese invention patent application with application date of September 13, 2016, application number 201610822838.8, and invention name “Mutual hover protection for touch screens”. Technical Field

[0002] The present disclosure relates generally to capacitive touch screen panels, and more particularly to a touch sensor layout for use in a capacitive touch screen. Background Art

[0003] Conventional touch screen sensors are designed to detect user touch, where a finger or stylus is typically used to express the user touch. Many styluses are designed with a small surface area for contacting the touch screen device. For example, a stylus may have a contact surface area of ​​approximately 1 mm in diameter. A stylus with a small contact surface area is more difficult to detect than a stylus with a larger contact surface area. Many conventional touch screen devices compensate for the difficulty of detecting a stylus with a small contact surface area by increasing the sensitivity of the touch sensor (e.g., by reducing the capacitance detection threshold of the touch sensor).

[0004] Unfortunately, as the sensitivity of touch sensors increases, false touch detections also increase. Most commonly, false touch detections occur when a user hovers a finger over a touch sensor but does not actually touch the sensor and does not intend to touch the sensor. In some cases, false touch detections may occur when a finger hovers 1-3 mm above the surface of the touch screen. Because such false touch detections are undesirable, there is a need in the prior art to improve touch sensors that are used in single-layer and multi-layer stacked configurations for capacitive touch screens. Summary of the invention

[0005] The present disclosure provides a capacitive sensing structure, which includes: a first sensing electrode, which is configured to sense a first capacitance and generate a first sensing signal indicating the sensed first capacitance; a transmission electrode, which is substantially positioned around the periphery of the first sensing electrode; a second sensing electrode, which is substantially positioned around the periphery of the transmission electrode, which is configured to sense a second capacitance and generate a second sensing signal indicating the sensed second capacitance; and a controller circuit, which is configured to receive the first sensing signal and the second sensing signal, to compare the change of the sensed first capacitance with the change of the sensed second capacitance, and to generate an output signal indicating a user touch based on the comparison between the change of the sensed first capacitance and the change of the sensed second capacitance.

[0006] In another embodiment, the present disclosure provides a capacitive sensing circuit, which includes a capacitive sensing structure, which includes: a first sensing electrode, which is configured to sense a first capacitance and generate a first sensing signal indicative of the sensed first capacitance; and a transmission electrode; a second sensing electrode, which is substantially positioned around the periphery of the capacitive sensing structure, the second sensing electrode is configured to sense a second capacitance and generate a second sensing signal indicative of the sensed second capacitance; and a controller circuit, which is configured to receive the first sensing signal and the second sensing signal, to compare the change in the sensed first capacitance with the change in the sensed second capacitance, and to generate an output signal indicative of a user touch based on the comparison between the change in the sensed first capacitance and the change in the sensed second capacitance.

[0007] In yet another embodiment, the present disclosure provides a method for detecting touch, the method comprising: applying a force signal to a capacitive sensing structure, the capacitive sensing structure comprising a transmission electrode and a first sensing electrode; sensing a first capacitance via the first sensing electrode; generating a first sensing signal indicative of the sensed first capacitance; sensing a second capacitance via a second sensing electrode, wherein the second sensing electrode is substantially positioned around a periphery of the capacitive sensing structure; generating a second sensing signal indicative of the sensed second capacitance; comparing a change in the sensed first capacitance with a change in the sensed second capacitance; and generating an output signal indicative of a user touch based on a comparison between the change in the sensed first capacitance and the change in the sensed second capacitance.

[0008] The foregoing and other features and advantages of the present disclosure will become more apparent from the following detailed description of embodiments when read in conjunction with the accompanying drawings. The detailed description and drawings are merely illustrative of the present disclosure and do not limit the scope of the invention as defined by the appended claims and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Embodiments are illustrated by way of example in the accompanying drawings, which are not necessarily drawn to scale, in which like numerals indicate similar parts, and in which:

[0010] Figure 1 A conventional touch sensor layout for use in a capacitive touch screen is shown;

[0011] Figure 2 A first example embodiment of a touch sensor layout for use in a capacitive touch screen application according to the present disclosure is shown;

[0012] Figure 3 Shown Figure 2An alternative embodiment of a touch sensor layout shown in a multi-layer stacked configuration;

[0013] Figure 4 A second example embodiment of a touch sensor layout for use in a capacitive touch screen application according to the present disclosure is shown;

[0014] Figure 5A , Figure 5B and Figure 5C Shown Figure 4 A cross-sectional view of a touch sensor shown in FIG.

[0015] Figure 6 An example embodiment of a controller circuit is presented;

[0016] Figure 7 A flow chart is shown which illustrates a method according to the present disclosure;

[0017] Figure 8 A flow chart is shown, which shows a method according to the present disclosure; and

[0018] Fig. 9 An alternative embodiment of a touch sensor is presented having a first sense electrode positioned between a transmit electrode and a second sense electrode. DETAILED DESCRIPTION

[0019] The present disclosure provides a touch sensor and method for detecting a small contact surface area without false touch detection due to a user's finger hovering over the touch sensor. In other words, the disclosed touch sensor and method are capable of distinguishing between a finger hovering over the touch sensor and a touch from a stylus having a small contact surface area without having to adjust the sensitivity of the touch sensor.

[0020] Now refer to Figure 1 , which shows an example embodiment of a conventional touch sensor 100 having a sensing electrode 102 and a transmission electrode 104. In operation, the touch sensor 100 receives a force signal applied to the transmission electrode 104. There is a capacitance between the transmission electrode 104 and the sensing electrode 102. A touch applied to the touch sensor 100 causes a change in capacitance between the transmission electrode 104 and the sensing electrode 102. This change in capacitance is used to detect a user touch.

[0021] For example, in Figure 1, the capacitance between the transmission electrode 104 and the sensing electrode 102 has an initial value when no touch is present. When a stylus having a contact surface area of ​​1 mm (referred to herein as a "1 mm stylus") contacts the touch sensor 100 at a location 106 above the sensing electrode 102, the capacitance between the transmission electrode 104 and the sensing electrode 102 undergoes a capacitance change large enough to identify a touch (e.g., exceeding a certain capacitance change threshold). Similarly, when the 1 mm stylus contacts the touch sensor 100 at a location 108 above the transmission electrode 104, the capacitance between the transmission electrode 104 and the sensing electrode 102 again undergoes a capacitance change large enough to be identified as a touch. Thus, a 1 mm stylus touching almost anywhere on the touch sensor 100 causes a capacitance change large enough to indicate a touch on the touch sensor 100.

[0022] Although conventional touch sensor 100 can detect touches with a 1 mm stylus, sensor 100 also detects touches when a finger hovers approximately 1-3 mm above sensor 100. For example, a finger having an approximate contact surface area of ​​7 mm and hovering approximately 1 mm above touch sensor 100 can trigger a capacitance change similar to that caused by an actual touch with a 1 mm stylus. Figure 1 The embodiment shown in makes it difficult to distinguish between a 1 mm stylus and a finger hovering over touch sensor 100.

[0023] The following description relates to a touch sensor and method for detecting touch that is capable of distinguishing between a finger hovering over the touch sensor and a touch from a stylus having a small contact surface area without having to adjust the sensitivity of the touch sensor. In essence, the disclosed touch sensor incorporates a second sensing electrode that is substantially positioned around the periphery of an existing touch sensor circuit (i.e., a transmission electrode and a first sensing electrode). A first capacitance exists between the first sensing electrode and the transmission electrode, and a second capacitance exists between the second sensing electrode and the transmission electrode. In some embodiments, a change in the first capacitance is compared with a change in the second capacitance. When the difference between the change in the first capacitance and the change in the second capacitance is sufficiently large, the touch sensor indicates that a touch is detected. Otherwise, the touch sensor indicates that no touch is detected. In other embodiments, the first capacitance is compared with the second capacitance. When the difference between the first capacitance and the second capacitance is sufficiently large, the touch sensor indicates that a touch is detected. Otherwise, the touch sensor indicates that no touch is detected.

[0024] Now refer to Figure 2, which shows an example embodiment of a touch sensor 200 for detecting touches in a capacitive touch screen application, wherein the touch sensor 200 is able to distinguish between a finger hovering over the touch sensor 200 and a touch from a stylus having a small contact surface area without having to adjust the sensitivity of the touch sensor 200. The touch sensor 200 includes a first sensing electrode 202, a transmission electrode 204, and a second sensing electrode 206. Figure 2 , first sense electrode 202 includes a plurality of finger structures 208 that intersect with a plurality of finger structures 210 of transmission electrode 204. Second sense electrode 206 is positioned substantially around the perimeter of transmission electrode 204. In this context, “substantially” refers to at least 90% of the perimeter of transmission electrode 204. To accommodate a single-layer touch screen configuration, or a configuration in which the first sense electrode and the second sense electrode are on the same layer, the pattern of second sense electrode 206 includes openings 212 for allowing electrical connection to transmission electrode 204 and / or first sense electrode 202.

[0025] exist Figure 2 The example touch sensor 200 shown in FIG. 1 includes a first set of gaps 203 between each of the interdigitated finger structures 208 and 210. The touch sensor 200 also includes a gap 205 between the transmission electrode 204 and the second sensing electrode 206. Figure 2 In the example embodiment shown in , gap 203 is 0.2 mm, gap 205 is 0.3 mm, the finger structures 208 have a width w1 of 0.3 mm, the finger structures 210 have a width w2 of 0.8 mm, and the second sense electrode 206 has a width w3 of 0.6 mm. It should be understood that these measurements are not intended to be limiting, but are provided as examples.

[0026] In operation, a controller circuit (not shown) applies a force signal to the transmission electrode 204. A first capacitance exists between the transmission electrode 204 and the first sensing electrode 202, and a second capacitance exists between the transmission electrode 204 and the second sensing electrode 206. When there is no touch, the first capacitance and the second capacitance each have an initial steady-state value. When a stylus or finger approaches the touch sensor 200, the first capacitance and the second capacitance are affected by the approaching object. Specifically, when the object approaches the second sensing electrode 206, the second capacitance changes, and when the object approaches the first sensing electrode 202, the first capacitance changes.

[0027] Therefore, the corresponding first and second capacitances (or the changes in the corresponding first and second capacitances) indicate the position of the approaching object relative to the first sensing electrode 202 and the second sensing electrode 206. When the first capacitance (or the change in the first capacitance) is greater than the second capacitance (or the change in the second capacitance), the object is closer to the first sensing electrode 202 than to the second sensing electrode 206. Conversely, when the second capacitance (or the change in the second capacitance) is greater than the first capacitance (or the change in the first capacitance), the object is closer to the second sensing electrode 206 than to the first sensing electrode 202. Therefore, a touch can be determined by considering the corresponding first and second capacitances (or the changes in the corresponding first and second capacitances) in view of the known positions of the first sensing electrode 202 and the second sensing electrode 206 in the touch sensor 200. In addition, a larger object (such as a finger) hovering over the touch sensor 200 can be distinguished from a touch from a stylus having a small contact surface area without having to adjust the sensitivity of the touch sensor 200.

[0028] For example, in Figure 2 , first sense electrodes 202 are positioned toward the center of touch sensor 200, and second sense electrodes 206 are positioned along the perimeter of touch sensor 200. Thus, when the first capacitance (or change in the first capacitance) is substantially greater than the second capacitance (or change in the second capacitance) (e.g., 20% greater), the touch object (i.e., stylus or finger) is positioned closer to the center of touch sensor 200 than to the perimeter of touch sensor 200 (where second sense electrodes 206 are located). When this occurs, the controller circuit indicates that a user touch is detected.

[0029] Conversely, when the second capacitance (or the change in the second capacitance) is greater than the first capacitance (or the change in the first capacitance), the touch object is positioned closer to the periphery of the touch sensor 200 than to the center of the touch sensor 200. When this occurs, the controller circuit indicates that no user touch is detected because the touch object is positioned closer to the periphery of the touch sensor 200 than to the center of the touch sensor 200.

[0030] Similarly, when the first capacitance (or the change in the first capacitance) is similar to the second capacitance (or the change in the second capacitance), the controller circuit indicates that no user touch is detected because the touch object is not substantially positioned closer to the center of the touch sensor 200 than to the perimeter of the touch sensor 200. This last condition typically indicates that a finger is hovering over the touch sensor 200.

[0031] Despite Figure 2The touch sensor 200 shown in is illustrated as a sensor in a single-layer touch screen application, but the touch sensor 200 may also be implemented in a multi-layer stacked configuration. For example, the transmission electrode 204 may include a first layer in a multi-layer stacked configuration, and the first sensing electrode 202 and the second sensing electrode 206 may include a second layer in a multi-layer stacked configuration. Alternatively, the first sensing electrode 202 and the transmission electrode 204 may include a first layer in a multi-layer stacked configuration, and the second sensing electrode 206 may include a second layer in a multi-layer stacked configuration. In such an embodiment, the second sensing electrode 206 may be positioned around the entire perimeter of the transmission electrode 204 and the opening 212 may be omitted. Figure 3 An example of such a configuration is shown in .

[0032] Figure 4 An alternative embodiment of a touch sensor 400 according to the present disclosure is shown, wherein the touch sensor 400 is able to distinguish between a finger hovering over the touch sensor 400 and a touch from a stylus having a small contact surface area without having to adjust the sensitivity of the touch sensor 400. The touch sensor 400 includes a first sense electrode 402, a transmit electrode 404, and a second sense electrode 406. Figure 4 The embodiment shown in is functionally similar to Figure 2 The embodiment shown in FIG. 4 is similar, but a diamond shape is provided. For example, the first sensing electrode 402 is a diamond shape, and the transmission electrode 404 substantially surrounds the periphery of the first sensing electrode 402. The second sensing electrode 406 substantially surrounds the periphery of the transmission electrode 404.

[0033] exist Figure 4 In the embodiment shown in FIG. 4 , the transmission electrode 404 includes an opening area 408 to allow electrical connection to the first sensing electrode 402, and the second sensing electrode 406 includes an opening area 410 to allow electrical connection to the first sensing electrode 402 and to the transmission electrode 404. The first sensing electrode 402 and the transmission electrode 404 are separated by a first gap 412. The transmission electrode 404 and the second sensing electrode 406 are separated by a second gap 414. In a single-layer touch screen application, Figure 4 However, touch sensor 400 may be implemented in a multi-layer stack configuration, in which case one or more of these opening areas 408 and 410 may be eliminated.

[0034] For example, the transmission electrode 404 may include a first layer in a multi-layer stacking configuration, and the first sensing electrode 402 and the second sensing electrode 406 may include a second layer in a multi-layer stacking configuration. In such an embodiment, the transmission electrode 404 may be positioned around the entire perimeter of the first sensing electrode 402 and the opening area 408 may be eliminated. Alternatively, the first sensing electrode 402 and the transmission electrode 404 may include a first layer in a multi-layer stacking configuration, and the second sensing electrode 406 may include a second layer in a multi-layer stacking configuration. In such an embodiment, the second sensing electrode 406 may be positioned around the entire perimeter of the transmission electrode 404 and the opening area 410 may be eliminated.

[0035] Now refer to Figure 5A , Figure 5B and Figure 5C To discuss the operation of touch sensor 400, these figures show the Figure 4 A cross-sectional view of the touch sensor 400 taken along line AA. Figure 5A , line 504 represents the electrical connection between the displayed portions of the transmission electrode 404, and line 506 represents the electrical connection between the displayed portions of the second sensing electrode 406. It should be understood that, as with respect to Figure 5A , Figure 5B and Figure 5C The operation of the touch sensor 400 shown and described is not limited to Figure 4 Rather, the sensor configuration 400 shown in FIG. 1 may also be applied to other sensor configurations designed according to the present disclosure, including Figure 2 Touch sensor 200 shown in FIG.

[0036] In operation, a controller circuit (not shown) applies a force signal 502 to the transmission electrode 404. A first capacitance 508 exists between the transmission electrode 404 and the first sensing electrode 402, and a second capacitance 510 exists between the transmission electrode 404 and the second sensing electrode 406. When there is no touch, the first capacitance 508 and the second capacitance 510 each have an initial steady-state value. When a stylus or finger approaches the touch sensor 400 (see Figure 5B and Figure 5C ), the first capacitance 508 and the second capacitance 510 are affected by the approaching object. Specifically, when the object approaches the second sensing electrode 406, the second capacitance 510 changes, and when the object approaches the first sensing electrode 402, the first capacitance 508 changes. Therefore, the corresponding first capacitance 508 and the second capacitance 510 (or the corresponding changes in the first capacitance 508 and the second capacitance 510) indicate the position of the approaching object relative to the first sensing electrode 402 and the second sensing electrode 406. This information can be used to detect touch.

[0037] When first capacitance 508 (or a change in first capacitance 508) is greater than second capacitance 510 (or a change in second capacitance 510), the object is closer to first sensing electrode 402 than to second sensing electrode 406. Conversely, when second capacitance 510 (or a change in second capacitance 510) is greater than first capacitance 508 (or a change in first capacitance 508), the object is closer to second sensing electrode 406 than to first sensing electrode 402. Thus, a touch can be determined by considering the corresponding first capacitance 508 and second capacitance 510 (or a change in the corresponding first capacitance 508 and second capacitance 510) in view of the known positions of first sensing electrode 402 and second sensing electrode 406 in touch sensor 400. In addition, a larger object (such as a finger) hovering over touch sensor 400 can be distinguished from a touch from a stylus having a small contact surface area without having to adjust the sensitivity of touch sensor 400.

[0038] For example, Figure 5B The embodiment shown in FIG. 4 shows a 1 mm stylus 512 touching the touch sensor 400 at the first sense electrode 402. Due to the size of the stylus 512 and its touch location, the touch of the stylus causes a large change in the first capacitance 508 (in Figure 5B The first capacitor 508′ is shown as a changed first capacitor 508′. Figure 5B As shown in , when the first capacitance 508 (or the change in the first capacitance 508) is substantially greater than the second capacitance 510 (or the change in the second capacitance 510) (e.g., 20% greater), the touch object is positioned closer to the center of the touch sensor 400 than to the periphery of the touch sensor 400 (where the second sensing electrode 406 is located). When this occurs, the controller circuit indicates that a user touch is detected.

[0039] In contrast, when finger 514 is hovering over touch sensor 400 (as in Figure 5C ), the first capacitor 508 (or the change of the first capacitor 508) (in Figure 5C The first capacitor 508′ after the change is shown in FIG. 5 and the second capacitor 510 (or the change of the second capacitor 510) (in FIG. Figure 5C When this occurs, the controller circuit interprets the capacitance change as occurring due to a finger hovering, and thus indicates that no user touch is detected.

[0040] Now refer to Figure 6 , which shows an example embodiment of a controller circuit 600. Figure 6In the embodiment shown in FIG. 6 , the controller circuit 600 includes a circuit 602 for generating a force signal 604. The controller circuit 600 senses a first capacitance 606 at a first sensing electrode and senses a second capacitance 608 at a second sensing electrode. The first capacitance 606 is sensed at a first capacitance-to-voltage converter circuit 610 and generates a first voltage V1 indicating the sensed first capacitance 606, the first capacitance-to-voltage converter circuit including an operational amplifier 612 and a feedback capacitor Cf1. Thus, when the first capacitance 606 changes, for example, the first voltage V1 changes accordingly in response to a user touch. The second capacitance 608 is sensed at a second capacitance-to-voltage converter circuit 614 and generates a second voltage V2 indicating the sensed second capacitance 608, the second capacitance-to-voltage converter circuit including an operational amplifier 616 and a feedback capacitor Cf2. Thus, when the second capacitance 608 changes, for example, the second voltage V2 changes accordingly in response to a user touch. The first voltage V1 and the second voltage V2 (or a change ΔV1 in the first voltage and a change ΔV2 in the second voltage) can be used to detect touch, as discussed in more detail below.

[0041] The first voltage V1 and the second voltage V2 are received at the logic circuit 618. Once started, the touch sensor (including the controller circuit 600) achieves a steady state, whereby the steady-state values ​​of the first capacitor 606 and the second capacitor 608 are detected and represented as the steady-state values ​​of the first voltage V1 and the second voltage V2, respectively. In some embodiments, these steady-state voltage values ​​are stored for comparison with the real-time values ​​of the first voltage V1 and the second voltage V2. For example, the logic circuit 618 can sample the first voltage V1 and the second voltage V2 to determine the change ΔV1 of the first voltage and the change ΔV2 of the second voltage, wherein these changes are determined relative to the steady-state values ​​of the first voltage V1 and the second voltage V2.

[0042] In some embodiments, the change ΔV1 of the first voltage is compared to the change ΔV2 of the second voltage to determine whether a touch occurs. Specifically, the logic circuit 618 compares the change ΔV1 of the first voltage to the change ΔV2 of the second voltage and indicates that a user touch is detected when the change ΔV1 of the first voltage is significantly greater than the change ΔV2 of the second voltage. For example, in some embodiments, the logic circuit 618 may indicate a touch when the change ΔV1 of the first voltage is approximately 20% greater than the change ΔV2 of the second voltage.

[0043] In other words, the logic circuit 618 determines the change ΔV1 of the first voltage relative to the initial value (steady-state value) of the first voltage V1, and determines the change ΔV2 of the second voltage relative to the initial value (steady-state value) of the second voltage V2. The logic circuit 618 then subtracts the change ΔV2 of the second voltage from the change ΔV1 of the first voltage. If the difference is greater than the threshold, the logic circuit 618 indicates a touch; otherwise, the logic circuit indicates no touch. The threshold can be selected to be any value. However, in some embodiments, the threshold is equal to 20% of the change ΔV2 of the second voltage. In this embodiment, the logic circuit 618 indicates a touch when the change ΔV1 of the first voltage is 20% greater than the change ΔV2 of the second voltage.

[0044] In other embodiments, the logic circuit 618 samples the instantaneous first voltage value V1 and the instantaneous second voltage value V2, and then subtracts the second voltage V2 from the first voltage V1. If the difference is greater than a threshold, the logic circuit 618 indicates a touch; otherwise, the logic circuit indicates no touch. The threshold can be selected to be any value. However, in some embodiments, the threshold is equal to 20% of the second voltage V2. In this embodiment, the logic circuit 618 indicates a touch when the first voltage V1 is 20% greater than the second voltage V2.

[0045] The logic circuit 618 generates an output signal 620 indicating whether a touch is detected. The output signal 620 is received at the main controller circuit 650, which is configured to perform operations in response to (or in view of) the output signal 620.

[0046] Figure 7A flow chart 700 is shown, which shows a method according to the above disclosure for using a touch sensor to distinguish between a finger hovering over the touch sensor and a touch from a stylus having a small contact surface area without having to adjust the sensitivity of the touch sensor. At box 701, a force signal is applied to a transmission electrode, thereby causing a first capacitance and a second capacitance at the corresponding first sensing electrode and second sensing electrode. At box 702, the first capacitance is sensed using the first sensing electrode. At box 703, a first sensing signal indicating the sensed first capacitance is generated. At box 704, the second capacitance is sensed using the second sensing electrode. At box 705, a second sensing signal indicating the sensed second capacitance is generated. At box 706, the first sensing signal and the second sensing signal are sampled to determine a change in the first sensing signal relative to a steady-state value of the first sensing signal and a change in the second sensing signal relative to a steady-state value of the second sensing signal. At box 707, the change in the second sensing signal is subtracted from the change in the first sensing signal. Box 708 determines whether the difference between the change in the first sensing signal and the change in the second sensing signal is greater than a threshold value (e.g., 20% of the change in the second sensing signal). If the difference between the change in the first sense signal and the change in the second sense signal is greater than the threshold, then at block 709, a signal is generated indicating that a touch is detected. Otherwise, at block 710, a signal is generated indicating that a touch is not detected.

[0047] Figure 8 A flow chart 800 is shown, which shows a method according to the aforementioned disclosure for using a touch sensor to distinguish between a finger hovering over the touch sensor and a touch from a stylus having a small contact surface area without having to adjust the sensitivity of the touch sensor. At box 801, a force signal is applied to a transmission electrode, thereby causing a first capacitance and a second capacitance at corresponding first sensing electrodes and second sensing electrodes. At box 802, the first capacitance is sensed using the first sensing electrode. At box 803, a first sensing signal indicating the sensed first capacitance is generated. At box 804, the second capacitance is sensed using the second sensing electrode. At box 805, a second sensing signal indicating the sensed second capacitance is generated. At box 806, the first sensing signal and the second sensing signal are sampled to determine instantaneous values ​​of the first sensing signal and the second sensing signal. At box 807, the second sensing signal value is subtracted from the first sensing signal value. Box 808 determines whether the difference between the first sensing signal value and the second sensing signal value is greater than a threshold value (e.g., 20% of the second sensing signal). If the difference is greater than the threshold, then at block 809, a signal is generated indicating that a touch is detected. Otherwise, at block 810, a signal is generated indicating that a touch is not detected.

[0048] It should be understood that other touch sensor designs other than those shown and described herein may be implemented. For example, the touch sensor may be implemented with other sensor patterns other than those having a cross-finger shape or a diamond shape. Such alternative embodiments may also include those in which the first sense electrode is positioned between the transmission electrode and the second sense electrode.

[0049] For example, Fig. 9 An embodiment of a touch sensor 900 is shown having a first sense electrode 902 positioned between a transmission electrode 904 and a second sense electrode 906. Fig. 9 The embodiment shown in further includes a controller circuit 908. As in the embodiments discussed herein, the controller circuit 908 applies a force signal 910 to the transmission electrode 904, thereby generating a first capacitance 912 using the first sense electrode 902 and a second capacitance 914 using the second sense electrode 906. The controller 908 receives a first sense signal 916 from the first sense electrode 902 indicating the first capacitance 912, and receives a second sense signal 918 from the second sense electrode 906 indicating the second capacitance 914. The controller circuit 908 compares the changes in the sense signals 916 and 918 to determine touch detection according to the foregoing disclosure.

[0050] The foregoing description has been provided by way of exemplary and non-limiting examples, and is a complete and informative description of one or more exemplary embodiments of the present invention. However, various modifications and adaptations may become apparent to those skilled in the relevant art in view of the foregoing description when read in conjunction with the accompanying drawings and the appended claims. However, all such and similar modifications to the present teachings will still fall within the scope of the present invention as determined by the appended claims.

[0051] For example, in some embodiments, the first sensing electrode and the transmission electrode can be considered as a single capacitive sensing structure that can operate independently of the second sensing electrode. In such embodiments, the second sensing electrode is positioned substantially around the perimeter of the capacitive sensing structure. In other embodiments, the transmission electrode and the second sensing electrode can be considered as a single capacitive sensing structure that can operate independently of the first sensing electrode. In such embodiments, the first sensing electrode is positioned substantially along the interior of the capacitive sensing structure, and the second sensing electrode is positioned substantially around the perimeter of the transmission electrode.

[0052] The aforementioned sensors and methods may be incorporated into a variety of touch sensor types, including, for example, zero-dimensional sensors, one-dimensional sensors, two-dimensional sensors, and wheel sensors.

Claims

1. A capacitive sensing structure, comprising: a first sensing electrode located in the first layer and configured to sense a first capacitance and generate a first sensing signal indicative of the sensed first capacitance; a transmission electrode located in the first layer and positioned around a periphery of the first sensing electrode; a second sensing electrode located in the first layer and positioned to surround at least 90% of a perimeter of the transmission electrode, the second sensing electrode being configured to sense a second capacitance and generate a second sensing signal indicative of the sensed second capacitance; as well as a controller circuit configured to receive the first sensing signal and the second sensing signal and to: generating a first voltage according to the first sensing signal; generating a second voltage according to the second sensing signal; determining steady-state values ​​of the first voltage and the second voltage; determining the change in the sensed first capacitance by subtracting the first voltage from the steady-state value of the first voltage to produce a first changed voltage; determining the change in the sensed second capacitance by subtracting the second voltage from the steady-state value of the second voltage to produce a second changed voltage; comparing the sensed change in the first capacitance with the sensed change in the second capacitance, and: generating an output signal indicative of a user touch based on a comparison between the change in the sensed first capacitance and the change in the sensed second capacitance; Wherein, comparing the change of the sensed first capacitance with the change of the sensed second capacitance comprises: subtracting the second varied voltage from the first varied voltage to produce a voltage difference; and The voltage difference is compared to a threshold voltage.

2. The capacitive sensing structure according to claim 1, wherein: The threshold voltage is 20% of the second changed voltage. 3 . The capacitive sensing structure of claim 1 , wherein the first sensing electrode is diamond-shaped. The capacitive sensing structure of claim 3 , wherein the transmission electrodes are diamond-shaped. 5 . The capacitive sensing structure of claim 4 , wherein the transmission electrode includes an open area to allow electrical connection to the first sensing electrode. 6 . The capacitive sensing structure of claim 4 , wherein the first sensing electrode and the transmission electrode are separated by a first gap.

7. The capacitive sensing structure of claim 4, wherein the second sensing electrodes are diamond-shaped. 8 . The capacitive sensing structure of claim 7 , wherein the second sensing electrode includes an open area to allow electrical connection to the first sensing electrode and to the transmission electrode.

9. The capacitive sensing structure of claim 7, wherein the transmission electrode and the second sensing electrode are separated by a second gap.

10. A capacitive sensing circuit, comprising: A capacitive sensing structure, the capacitive sensing structure comprising: a first sensing electrode located in the first layer and configured to sense a first capacitance and generate a first sensing signal indicative of the sensed first capacitance; a transmission electrode located in the first layer; and a second sensing electrode located in the first layer and positioned to surround at least 90% of a perimeter of the capacitive sensing structure, the second sensing electrode being configured to sense a second capacitance and generate a second sensing signal indicative of the sensed second capacitance; and a controller circuit configured to receive the first sensing signal and the second sensing signal and to: generating a first voltage according to the first sensing signal; generating a second voltage according to the second sensing signal; determining steady-state values ​​of the first voltage and the second voltage; determining the change in the sensed first capacitance by subtracting the first voltage from the steady-state value of the first voltage to produce a first changed voltage; determining the change in the sensed second capacitance by subtracting the second voltage from the steady-state value of the second voltage to produce a second changed voltage; comparing the sensed change in the first capacitance with the sensed change in the second capacitance, and for generating an output signal indicative of a user touch based on the comparison between the sensed change in the first capacitance and the sensed change in the second capacitance; Wherein, comparing the change of the sensed first capacitance with the change of the sensed second capacitance comprises: subtracting the second varied voltage from the first varied voltage to produce a voltage difference; and The voltage difference is compared to a threshold voltage.

11. The capacitive sensing circuit according to claim 10, wherein: The threshold voltage is 20% of the second changed voltage. 12 . The capacitive sensing circuit of claim 10 , wherein the first sensing electrode is diamond-shaped.

13. The capacitive sensing circuit of claim 12, wherein the transmission electrode is diamond-shaped.

14. The capacitive sensing circuit of claim 13, wherein the transmission electrode includes an open area to allow electrical connection to the first sensing electrode. 15 . The capacitive sensing circuit of claim 13 , wherein the first sensing electrode and the transmission electrode are separated by a first gap.

16. The capacitive sensing circuit of claim 13, wherein the second sensing electrode is diamond-shaped. 17 . The capacitive sensing circuit of claim 16 , wherein the second sensing electrode includes an open area to allow electrical connection to the first sensing electrode and to the transmission electrode.

18. The capacitive sensing circuit of claim 16, wherein the transmission electrode and the second sensing electrode are separated by a second gap.

19. A method for detecting a touch, comprising: applying a force signal to a capacitive sensing structure, the capacitive sensing structure comprising a transmission electrode and a first sensing electrode, the transmission electrode and the first sensing electrode both being located in a same first layer; sensing a first capacitance via the first sensing electrode; generating a first voltage indicative of the sensed first capacitance; sensing a second capacitance via a second sensing electrode located in the first layer, wherein the second sensing electrode is positioned around at least 90% of a perimeter of the capacitive sensing structure; generating a second voltage indicative of the sensed second capacitance; determining steady-state values ​​of the first voltage and the second voltage; determining the change in the sensed first capacitance by subtracting the first voltage from the steady-state value of the first voltage to produce a first changed voltage; and determining the change in the sensed second capacitance by subtracting the second voltage from the steady-state value of the second voltage to produce a second changed voltage; comparing the sensed change in the first capacitance with the sensed change in the second capacitance; and generating an output signal indicative of a user touch based on a comparison between the change in the sensed first capacitance and the change in the sensed second capacitance Wherein, comparing the change of the sensed first capacitance with the change of the sensed second capacitance comprises: subtracting the second varied voltage from the first varied voltage to produce a voltage difference; and The voltage difference is compared to a threshold voltage.

20. The method according to claim 19, wherein: The threshold voltage is 20% of the second changed voltage.

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