Dual measurement and related systems, methods and devices for high sensitivity capacitive sensing applications

Abstract

Embodiments disclosed herein generally relate to dual measurement techniques for capacitive sensing and related systems and methods. In one embodiment, a capacitive sensing method characterized by water tolerance is performed, and another capacitive sensing method characterized by proximity tolerance is performed. In one embodiment, the method characterized by water tolerance is a driven shield self-capacitive sensing measurement, and the method characterized by proximity tolerance is a grounded shield self-capacitive sensing measurement.

Description

[0001] Priority declaration

[0002] This application claims the benefit of the filing date of U.S. Provisional Patent Application No. 62 / 793,003, filed on January 16, 2019, entitled “DUAL MEASUREMENT OF SELFCAPACITANCE SENSORS TO SUPPORT GLOVED OPERATION AND WATER TOLERANCE WHILE REJECTING UNINTENDED PROXIMITY ACTIVATION,” and claims the benefit of the filing date of co-pending U.S. Patent Application No. 16 / 377,612, filed on April 8, 2019, entitled “DUAL MEASUREMENT FOR HIGH SENSITIVITY CAPACITIVE SENSING APPLICATIONS AND RELATED SYSTEMS, METHODS AND DEVICES,” the disclosures of each of which are hereby incorporated by reference herein in their entirety. Technical Field

[0003] The disclosed embodiments relate generally to capacitance sensing and, more particularly, to measurement techniques and related systems, methods, and apparatus for high-sensitivity capacitance sensing applications. Background Art

[0004] Typical touch interface systems may incorporate touch sensors (such as, but not limited to, capacitive sensors and / or resistive sensors) that respond to objects that are in close proximity to or in physical contact with a touch-sensitive surface of the touch interface system. Such responses may be captured and interpreted to infer information about the contact, including the position of the object relative to the touch interface system.

[0005] Touchpads used with personal computers (including laptop computers and keyboards for tablet computers) typically incorporate touch interface systems or operate in combination with touch interface systems. Displays typically include touch screens that incorporate elements of touch interface systems (typically at least touch sensors) to enable users to interact with graphical user interfaces (GUIs) and / or computer applications. Examples of devices incorporating touch displays include portable media players, televisions, smart phones, tablet computers, personal computers, and wearable devices such as smart watches, to name a few. In addition, control panels for automobiles, household appliances (e.g., ovens, refrigerators, or washing machines), security systems, automated teller machines (ATMs), residential environmental control systems, and industrial equipment can incorporate touch interface systems with displays and housings, including enabling buttons, sliders, wheels, and other touch elements.

[0006] Depending on the end use, the touch interface system is used in environments that vary in exposure (such as but not limited to water, sand and / or crayons), temperature, and noise. For example, for some applications, the touch interface system may be used at temperatures ranging from -40 to 40 degrees Celsius, and therefore the sensitivity of such a touch interface system needs to be set so that touches from both bare and gloved fingers are detected. As another example, for some applications, the touch interface system may be used in areas where people pass by the display but do not intend to use the display, so unintentional proximity detections need to be rejected. In view of the different sensitivity and environmental requirements, successful operation is sometimes challenging to balance. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The objects and advantages of the various embodiments of the present disclosure will be apparent to those skilled in the art through the detailed description in conjunction with the accompanying drawings. The patent or application file contains at least one drawing in color. The Patent Office will provide copies of this patent or patent application publication with color drawings upon request and payment of the necessary fee.

[0008] Figure 1A , Figure 1B and Figure 1C shows examples of electric fields projecting from an isolated sensor, a grounded shield sensor, and a driven shield sensor;

[0009] Figure 2 A process for dual touch measurement sensing according to one or more embodiments of the present disclosure is shown;

[0010] Figure 3 An exemplary touch interface system 300 configured for dual measurement sensing technology according to one or more embodiments of the present disclosure is shown.

[0011] Figure 4A and Figure 4BDual measurement sensing operations, such as touch sensing circuits, are shown according to one or more embodiments of the present disclosure.

[0012] Figure 5A and Figure 5B Dual measurement sensing operations, such as touch sensing circuits, are shown according to one or more embodiments of the present disclosure.

[0013] Figure 6 A diagram corresponding to a dual measurement calibration method according to one or more embodiments of the present disclosure is shown.

[0014] Figure 7 A timing diagram of exemplary dual touch measurement sensing according to one or more embodiments of the present disclosure is shown. DETAILED DESCRIPTION

[0015] In the following detailed description, reference is made to the accompanying drawings which form a part thereof, and in which specific exemplary embodiments in which the present disclosure may be practiced are shown by way of example. These embodiments are described in sufficient detail to enable one of ordinary skill in the art to practice the present disclosure. However, other embodiments may be utilized, and changes in structure, material, and process may be made without departing from the scope of the present disclosure.

[0016] The illustrations presented herein are not intended to be actual views of any particular method, system, device, or structure, but are merely idealized representations for describing embodiments of the present disclosure. The drawings presented herein are not necessarily drawn to scale. For the convenience of the reader, similar structures or components in the various drawings may retain the same or similar numbering; however, the similarity of numbering does not mean that the structures or components must be identical in size, composition, configuration, or any other attribute.

[0017] It is readily understood that the components of the embodiments as described herein as a whole and shown in the accompanying drawings may be arranged and designed in a variety of different configurations. Therefore, the following description of various embodiments is not intended to limit the scope of the present disclosure, but is merely representative of various embodiments. Although various aspects of the embodiments may be presented in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise indicated.

[0018] The following description may include examples to help those skilled in the art practice the embodiments disclosed in the present invention. The use of the terms "exemplary", "by way of example" and "for example" means that the relevant description is illustrative, and although the scope of the present disclosure is intended to cover examples and legal equivalents, the use of such terms is not intended to limit the scope of the embodiments or the present disclosure to the specified components, steps, features or functions, etc.

[0019] Therefore, unless otherwise specified herein, the specific embodiments shown and described are merely examples and should not be construed as the only way to implement the present disclosure. Elements, circuits, and functions may be shown in block diagram form so as not to obscure the present disclosure with unnecessary details. On the contrary, the specific embodiments shown and described are merely exemplary and should not be construed as the only way to implement the present disclosure, unless otherwise specified herein. In addition, the partitioning of logic between block definitions and individual blocks is an example of a specific embodiment. It will be apparent to one of ordinary skill in the art that the present disclosure can be practiced through many other partitioning solutions. In most cases, details about timing considerations, etc. have been omitted, where such details are not required to obtain a complete understanding of the present disclosure and are within the capabilities of one of ordinary skill in the relevant art.

[0020] The information and signals described herein may be represented using any of a variety of different techniques and technologies. For example, data, instructions, commands, information, signals, bits, and symbols that may be referenced throughout the specification may be represented by voltage, current, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof. For clarity of presentation and description, some of the accompanying drawings may show signals as single signals. It will be appreciated by those of ordinary skill in the art that a signal may represent a bus of signals, wherein the bus may have various bit widths, and the present disclosure may be implemented on any number of data signals including a single data signal.

[0021] It should be understood that any reference to an element using names such as "first", "second", etc. herein does not limit the number or order of these elements, unless such limitations are explicitly stated. On the contrary, these names are used herein as a convenient method to distinguish two or more elements or two or more instances of an element. Therefore, the reference to the first element and the second element does not mean that only two elements can be used, or that the first element must be before the second element in some way. Moreover, unless otherwise stated, a group of elements may include one or more elements. Similarly, an element sometimes mentioned in the singular may also include one or more instances of an element.

[0022] As used herein, the term "substantially" in reference to a given parameter, attribute, or condition refers to and includes the degree to which a person of ordinary skill in the art would understand that the given parameter, attribute, or condition is satisfied with a small degree of variance, such as, for example, within acceptable manufacturing tolerances. By way of example, depending on the specific parameter, attribute, or condition that is substantially satisfied, the parameter, attribute, or condition may be satisfied by at least 90%, at least 95%, or even at least 99%.

[0023] The various exemplary logic blocks, modules, and circuits described in conjunction with the embodiments disclosed herein may be implemented or executed with a general purpose processor, a special purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof, designed to perform the functions described herein. A general purpose processor (also referred to herein as a host processor or simply a host) may be a microprocessor, but in an alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration. A general purpose computer including a processor is considered a special purpose computer when the general purpose computer is configured to execute computing instructions (e.g., software code) associated with the embodiments disclosed herein.

[0024] Moreover, it should be noted that embodiments may be described according to processes depicted as flow charts, flow diagrams, structure diagrams, or block diagrams. Although flow charts may describe operational behaviors as sequential processes, many of these behaviors may be performed in another order, in parallel, or substantially simultaneously. In addition, the order of actions may be rearranged. A process may correspond to a method, a thread, a function, a procedure, a subroutine, and / or a subprogram, but is not limited thereto. In addition, the methods disclosed herein may be implemented by hardware, software, or both. If implemented in software, these functions may be stored or transmitted to a computer-readable medium as one or more instructions or codes. Computer-readable media include both computer storage media and communication media, which include any media that facilitate the transfer of a computer program from one location to another.

[0025] As understood for the purposes of the embodiments described in the present disclosure, a capacitive sensor may respond to an object (such as a finger or stylus) contacting a touch-sensitive area of ​​the capacitive sensor or an object approaching a touch-sensitive area of ​​the capacitive sensor. In the present disclosure, "contact" and "touch" are intended to encompass both physical contact of an object with a touch-sensitive area (e.g., but not limited to, an electrode or one or more covering layers covering an electrode or electrode group) and the presence of an object in the vicinity of a touch-sensitive area without physical contact. Actual physical contact with a capacitive sensor is not necessarily required.

[0026] By way of example, when an object contacts a capacitive sensor, a capacitance change may occur within the capacitive sensor at or near the contact location. If its touch meets a certain threshold, the analog acquisition front end may "detect" the touch. "Charge post transfer" is a technique implemented in some touch acquisition front ends for detecting capacitance changes, in which a sensing capacitor is charged in response to a capacitance change (e.g., charges faster or slower), and the charge is transferred to an integration capacitor over multiple charge transfer cycles. The amount of charge associated with such a charge transfer may be converted to a digital signal by an analog-to-digital converter (ADC), and a digital controller may process those digital signals (often referred to as "delta counts" or just "delta") to determine a measurement and whether an object is contacting the sensor.

[0027] Self-capacitance sensors (also referred to herein as "self-cap sensors") are capacitive field sensors that respond to changes in capacitance to ground. Self-capacitance sensors are typically arranged in an array of rows and columns that react independently to touch. As a non-limiting example, a self-capacitance sensor may include a circuit that employs a repetitive charge-and-transfer cycle using a commonly integrated CMOS push-pull drive circuit with a floating terminal.

[0028] Mutual capacitance sensors are capacitive field sensors that detect / respond to changes in capacitance between two electrodes, a drive electrode and a sense electrode. The drive and sense electrode pairs form a capacitor at each intersection of the drive and sense lines. Self-capacitance and mutual capacitance technologies can be used in the same touch interface system and complement each other, for example, self-capacitance can be used to confirm a touch using mutual capacitance detection.

[0029] For a 2D touch-sensitive surface that can be incorporated into a touch-sensitive surface (e.g., a touch pad or display screen) and can facilitate user interaction with an associated home appliance, an exemplary touch sensor can be covered in a 2-dimensional (2D) arrangement. An insulating protective layer (e.g., but not limited to, resin, glass, and / or plastic) can be used to cover the touch sensor and can be referred to herein as a "cover layer." As used herein, a "touch display" is a display (such as a liquid crystal display (LCD), a thin film transistor (TFT) LCD, or a light emitting diode (LED) display) that incorporates a 2D touch sensor.

[0030] Using the example of a touch screen sensor (a matrix sensor approach using a mutual capacitance sensor employing charge transfer technology), the drive electrodes may extend in rows on one side of the substrate, and the sensing electrodes may extend in columns on the other side of the substrate to define a "matrix" array of N×M nodes. Each node corresponds to the intersection between the conductive lines of the drive electrode and the conductive lines of the sensing electrode. The drive electrode drives all nodes in a given row at the same time, and the sensing electrode senses all nodes in a given column. The capacitive coupling of the drive electrode and the sensing electrode at the node position (mutual capacitance), or the coupling of the sensing electrode to ground (self-capacitance) may be measured separately or both in response to a capacitance change indicating a touch event. For example, if a drive signal is applied to the drive electrode of row 2 and the sensing electrode of column 3 is active, the node position is: row 2, column 3. The nodes may be scanned sequentially by different combinations of drive electrodes and sensing electrodes. In one mode, the drive electrodes may be driven sequentially, while all the sensing electrodes are continuously monitored. In another mode, each sensing electrode may be sampled sequentially.

[0031] As non-limiting examples, the touch processor and touch acquisition circuitry may be a microcontroller, digital logic circuit, and / or configurable state machine that may be configured to control drive electrodes and analyze capacitive effects on the touch sensor (e.g., but not limited to, detected from changes in measured channel capacitance and / or absolute channel capacitance). An integrated circuit (IC) package including a microcontroller may provide input and output pins to communicate with a host; and firmware to perform techniques and operations, including those described herein in conjunction with various embodiments. Examples of microcontrollers that may be used with various embodiments of the present disclosure may include peripheral interface microcontrollers, ARM-based microcontrollers, and AVR-8 and 32-bit microcontrollers.

[0032] Self-capacitance sensors are sometimes implemented with a "ground shield" to isolate the touch sensor from electromagnetic interference (EMI) and provide directionality to the touch sensor through field shaping (i.e., preventing backside activation). Structurally, ground shielding involves positioning a ground shield (usually a grounded conductive material) behind or around an electrode to contain the electric field emanating from the electrode.

[0033] Grounded shields are sometimes used in touch sensor applications that require low sensitivity, i.e., need to respond to objects that are close to the surface. More specifically, grounded shields typically reduce sensitivity by containing the transmitted electric field, such as by bringing it close to the dielectric cover layer. In other words, the grounded shield reduces the projection of the electric field, thereby reducing the range of distances (e.g., the distance from the cover layer) at which proximity can be detected. In this article, reducing the projection of the electric field may also be referred to as reducing the "intensity" of the electric field. Containing the electric field enables sensing while reducing unwanted proximity detection, i.e., detection farther away from the touch sensor than an acceptable distance (acceptable is usually defined based on the requirements of a specific application). The grounded shield reduces the projection of the electric field (and reduces the intensity of the electric field), thereby reducing the range of distances at which proximity detection can be experienced.

[0034] However, the ground shield sensor can still detect invalid touches from foreign objects (such as moisture on the touch sensor). By further explanation, it is known that at least two capacitive couplings occur with a self-capacitance sensor that implements a ground shield. The first capacitive coupling is the ground return and is: the electrode to finger to ground (also known as "free space") path that is typically used to detect capacitance changes in self-capacitance measurements. The second capacitive coupling is called the ground return and is: the electrode to finger to ground shield to ground path. Moisture does not produce capacitive coupling to the ground return path, however, it can produce capacitive coupling to the ground return path, and charge can be drawn along the second path, so that moisture is indistinguishable from a finger to the touch processor. In other words, invalid touches can be detected based on moisture on the touch sensor. Therefore, although the ground shield sensor has the advantages of reducing projection and reducing proximity effects (e.g., unwanted proximity detection), it is prone to detecting invalid touches when moisture is on the sensor.

[0035] Self-capacitive sensors are sometimes implemented with a "driven shield" to isolate the touch sensor from electromagnetic interference (EMI), provide directionality to the touch sensor, and / or improve tolerance to foreign objects such as moisture. A typical example of a driven shield is an active shield (i.e., conductive material) incorporated behind or around an active electrode to continuously track (i.e., drive to the same voltage potential) the sensing electrode and driving electrode voltage potentials of all other electrodes or a subset of adjacent electrodes of the sensor. The effect of the driven shield technique is that there is no or insignificant capacitive coupling from the sensor to the moisture to the shield, so moisture is not detected as a touch. In the case of a touch, when moisture is on the sensor, most (if not all) of the available field generated by the sensor is coupled to the finger, thereby increasing the impact on the sensor, thereby improving sensitivity and signal-to-noise ratio (SNR). Note that the electric field around the touch sensor can be further projected, allowing the design of close proximity sensors (i.e., sensors that detect touches of objects that are close to but not physically touching the sensor). However, the increased electric field projection can cause unintended proximity detection, especially in high-sensitivity applications.

[0036] Figure 1A , Figure 1B and Figure 1C The electric field emanating from an exemplary touch sensor is shown. Figure 1A An isolated sensor is shown (i.e., shielding is not implemented), Figure 1B shows a grounded shield sensor, and Figure 1C The driven shield sensor is shown. Figure 1A , Figure 1B and Figure 1C In each of the figures, the electric field and its directionality are shown by the solid arrows coming out of the touch sensor. The electric field strength is shown by the multiple arrows, so the electric field 103 ( Figure 1B ) is weaker than the electric field 101 emitted from the sensor 100 ( Figure 1A ) and the electric field 105 emitted from the sensor 104 ( Figure 1C )Both.

[0037] The inventors of the present disclosure recognized that neither ground shield technology nor driven shield technology alone is suitable for applications requiring high sensitivity, reduced electric field projection, and moisture barrier. The inventors of the present disclosure recognized the need for a touch processor for many applications, including high sensitivity applications requiring proximity detection barrier and moisture barrier.

[0038] Thus, one or more embodiments of the present disclosure relate generally to dual touch measurement sensing techniques, and more specifically to using proximity barrier techniques in combination with moisture barrier techniques to detect touch. In one embodiment, (i) a first measurement is performed using a driven shield self-capacitance measurement (also referred to herein as a "driven shield self-capacitance mode"), or (ii) a shield is grounded and then a self-capacitance measurement is performed (also referred to herein as a "grounded shield self-capacitance mode"); then a second measurement is performed using the other of the driven shield self-capacitance mode or the grounded shield self-capacitance mode. If both measurements detect a touch, then the touch is detected.

[0039] Figure 2A process 200 for dual touch measurement sensing according to one or more embodiments of the present disclosure is shown. In operation 201, a driven shield self-capacitance sensing mode is enabled. The driven shield self-capacitance sensing mode may be associated with self-capacitance sensing techniques that implement driven shielding (including those described herein). In operation 202, a driven shield self-capacitance sensing operation is performed. In operation 203, a sensing result of the driven shield self-capacitance sensing operation is determined. The sensing result may be, for example, a value indicating that a touch is detected or not detected. In the case where the sensing result is detected by the touch, the location of the touch may also be stored. For example, in the case of a touch display, if a touch is detected during operation 202, location information corresponding to the coordinates of the physical location where the touch is detected on the touch display may also be stored. In operation 204, a grounded shield self-capacitance sensing mode is enabled. In one or more embodiments, enabling a grounded shield self-capacitance sensing mode may include grounding the shield of the sensor and enabling the self-capacitance sensing mode. Such a self-capacitance sensing mode may be associated with a self-capacitance sensing technique that does not include the use of a driven shield. In operation 205, a grounded self-capacitance sensing operation is performed. In one or more embodiments, performing a grounded shield self-capacitance sensing operation may include performing a self-capacitance sensing technique. In operation 206, a sensing result of the grounded self-capacitance sensing operation is determined. The sensing result may indicate that a touch is detected or not detected, and if a touch is detected, it may include location information associated with the detected touch. In operation 207, a touch result is determined in response to the first result and the second result. In one embodiment, if the sensing result of the driven shield self-capacitance sensing operation and the sensing result of the grounded shield self-capacitance sensing operation are both detected touches, the touch result is that a touch is detected. In addition, if the sensing result of the driven shield self-capacitance sensing operation or the sensing result of the grounded shield self-capacitance sensing operation is that a touch is not detected, the touch result is not detected. In one embodiment, if the sensing result of the driven shield self-capacitance sensing operation and the sensing result of the grounded shield self-capacitance sensing operation are both detected touches for the same location information, the touch result is detected touch, and if the sensing result of the driven shield self-capacitance sensing operation or the sensing result of the grounded shield self-capacitance sensing operation is that a touch is not detected for the same location information, the touch result is not detected.

[0040] Figure 3An exemplary touch interface system 300 configured for dual measurement sensing technology according to one or more embodiments of the present disclosure is shown. In one or more embodiments, the touch interface system 300 may include a capacitive sensor 301, an acquisition circuit 302, and a touch processor 303. The touch processor 303 may generally be configured to detect a touch at a touch sensor such as the capacitive sensor 301. In one or more embodiments, the touch processor 303 may include a grounded shield self-capacitance sensing module 304 and a driven shield self-capacitance module 305. The touch processor 303 may be configured to detect a touch at the capacitive sensor 301 in response to the results of the grounded shield self-capacitance sensing module 304 and the driven shield self-capacitance module 305 (i.e., detecting a touch).

[0041] The ground shield self-capacitance sensing module 304 may generally be configured to perform one or more ground shield self-capacitance sensing techniques, including those described herein. The driven shield self-capacitance module 305 may generally be configured to perform one or more driven shield self-capacitance sensing techniques, including those described herein. Figure 3 Only the ground shield self-capacitance sensing module 304 and the driven shield self-capacitance module 305 are shown, but it is particularly contemplated that the touch processor 303 can be configured to perform other capacitive sensing technologies. By way of example, the touch processor 303 may include a mutual capacitance sensing module for performing mutual capacitance sensing operations, and the dual measurement sensing technology may be used to confirm the results of the mutual capacitance sensing module - for example, confirming touch detection using mutual capacitance sensing.

[0042] Figure 4A , Figure 4B , Figure 5A and Figure 5B Dual measurement sensing operations, such as touch sensing circuits, are shown according to one or more embodiments of the present disclosure. Figure 4A and Figure 4B Exemplary dual-measurement sensing operations are shown with no active touch and with water on the electrodes of the touch sensor. Figure 5A and Figure 5B An exemplary dual measurement sensing operation of a finger active touch is shown.

[0043] exist Figure 4A and Figure 4BIn the illustrated embodiment, the touch sensing circuit system 400 includes a touch sensor 401 and a touch controller 405 operably coupled to the touch sensor 401. In one or more embodiments, the touch sensor 401 includes a conductive structure 404, a substrate material 402, and a back conductive material 403A and a front conductive material 403B. The substrate material 402 can be, for example, any insulating material, including low-loss substrates such as printed circuit board (PCB) materials (for example, but not limited to FR4, CEM-1, polyamic acid, and polyimide film), acrylic resins such as polyethylene terephthalate (PET) and polycarbonate, and / or glass.

[0044] In one or more embodiments, the conductive structure 404 can be, for example, an electrode formed by a conductive filler on the substrate material 402. The conductive structure 404 can be, for example, copper, carbon, silver ink, Orgacon ( TM ), indium tin oxide (ITO) coated glass and / or a suitable conductive material characterized by a resistivity of substantially 1 kΩ / sq such that the RC time constant can be controlled.

[0045] In one or more embodiments, the back conductive material 403A and the front conductive material 403B can be disposed on opposite sides of the substrate material 402. The back conductive material 403A and / or the front conductive material 403B can extend in parallel planes. In one or more embodiments, there can be additional conductive materials disposed on lateral sides of the substrate material 402. The back conductive material 403A and the front conductive material 403B can be joined or continuous with such additional lateral materials.

[0046] In one or more embodiments, back conductive material 403A can be arranged relative to substrate material 402 and conductive structures 404 to facilitate the directionality of electric fields projecting from conductive structures 404. In one embodiment, back conductive material 403A can be positioned coplanar with a bottom surface of substrate material 402 opposite conductive structures 404 such that electric fields projecting from conductive structures 404 project further in a direction opposite to back conductive material 403A, or in other words, such that back conductive material 403A blocks (or reduces) projection of electric fields from conductive structures 404 in a direction from the surface of touch sensor 401 toward back conductive material 403A.

[0047] In one or more embodiments, the front conductive material 403B can be arranged relative to the substrate material 402 to further provide directionality and / or isolate the touch sensor 401 from other nearby sensors or electronic devices. The front conductive material 403B can define one or more openings (e.g., Figure 4A and Figure 4B, but not labeled), to facilitate projection of the electric field from the conductive structure / electrode 404.

[0048] In one or more embodiments, the touch controller 405 may generally be configured to perform dual measurement techniques according to one or more embodiments of the present disclosure. By way of example, the touch controller 405 may implement Figure 3 The touch processor 303, the ground shielding self-capacitance sensing module 304 and the driven shielding self-capacitance module 305 are shown. Figure 4A , Figure 4B In the example shown, the touch controller 405 is operably coupled to the touch sensor 401 via one or more conductive lines. More specifically, the touch controller 405 is operably coupled to the conductive structure / electrode 404 via the sensing line 407 and is operably coupled to the conductive materials 403A, 403B via the shielding line 406.

[0049] Figure 4A The touch sensing circuit system 400 is shown during a first measurement of a dual measurement sensing operation, wherein moisture 420 is present at the conductive structure / electrode 404 and capacitive coupling 421 exists between the moisture 420 and the conductive materials 403A, 403B. Figure 4A and Figure 4B In the described embodiment, the first measurement is a driven shield self-capacitance measurement, and the second measurement is a grounded self-capacitance measurement, but the embodiments of the present disclosure do not require that the driven shield self-capacitance measurement and the grounded shield self-capacitance measurement be performed in a particular order. Therefore, during the first measurement, the touch controller 405 provides a driven shield signal 409 to the conductive materials 403A, 403B, and causes the conductive materials 403A, 403B to have a driven shield voltage.

[0050] In one embodiment, the touch controller 405 synchronizes (i.e., tracks the voltage potential) the driven shield signal 409 to one or more measurement signals 410 on the conductive structure / electrode 404. The measurement signal 410 indicates the change in capacitance of the touch sensor 401, and is received via the sense line 407 and stored by the touch controller 405. Due to the driven shield signal 409, the capacitive coupling 421 is blocked or at least does not contribute to the self-capacitance measurement, so the touch controller 405 does not detect the touch due to moisture 420 at the conductive structure / electrode 404.

[0051] Note that additional signal lines for tracking voltages associated with nearby sensors in order to provide driven shielding may also be included in touch sensing circuitry 400 ( Figure 5A and Figure 5B ) but are omitted in this discussion for improved clarity.

[0052] Figure 4BThe touch sensing circuit system 400 is shown during a second measurement of a dual measurement sensing operation, wherein moisture 420 is present at the conductive structure / electrode 404, and there is a capacitive coupling 421 between the moisture 420 and the conductive material 403A, 403B. The second measurement is a grounded self-capacitance shield measurement, so the touch controller 405 provides a ground voltage 411 to the conductive material 403A, 403B via the shield line 406, and causes the conductive material 403A, 403B to have a voltage potential equal to the ground potential. The measurement is made in response to a measurement signal 410 received through the sense line 407 and stored by the touch controller 405. Here, for the reasons already explained, the capacitive coupling 421 is detected as a touch by the touch controller 405. Therefore, the result of the grounded shield self-capacitance measurement is that an invalid touch is detected.

[0053] Once touch controller 405 completes both measurements, touch controller 405 determines whether a touch has occurred. In this example, a touch is not detected by the driven shield self-capacitance measurement and a touch is detected by the grounded self-capacitance measurement, so the dual measurement logic of touch controller 405 determines that a touch has not occurred because the results of the two measurements are different, and touch controller 405 does not detect a touch.

[0054] Figure 5A and Figure 5B Touch sensing circuitry 400 is shown during a dual measurement sensing operation with finger 422 contacting touch sensor 401. Note that the touch is detected for both the self capacitance driven shield measurement and the grounded shield self capacitance measurement, so the touch is detected by touch controller 405 and in this case it is a valid touch.

[0055] In an embodiment where the touch controller 405 is implemented as a microcontroller, one or more of the sense line 407 and the shield line 406 may be operably coupled to a general purpose input / output (GPIO) pin or a peripheral input / output (I / O) pin of the microcontroller, and the ground shield self-capacitance sensing module 304 and the driven shield self-capacitance module 305 may be implemented in the firmware of the microcontroller. In one embodiment, the touch controller 405 may include internal circuitry for providing a ground signal to the GPIO pin, and thus such internal circuitry may be used to provide a ground voltage to the conductive materials 403a, 403B.

[0056] One or more embodiments of the present disclosure are generally directed to methods of calibrating a touch processor for dual measurement sensing for low and high sensitivity applications. Driven shield self-capacitance measurements and grounded shield self-capacitance measurements are performed under various conditions, some requiring high sensitivity, some requiring low sensitivity, and both with and without moisture. Since the strength of the capacitive coupling is proportional to the delta count of charge transfer, the delta count can be used to determine a threshold or threshold range for detecting a touch.

[0057] Figure 6 A graph 600 of delta counts for self-capacitance grounded measurements (i.e., grounded self-capacitance measurements) and driven shield self-capacitance measurements is shown. For each of the self-capacitance grounded measurements and driven shield self-capacitance measurements, test measurements were taken using no gloves, light gloves, and heavy gloves in direct physical contact with the front panel layer above the touch sensor. Test measurements were also taken using a bare finger (i.e., no gloves) at 3 mm and 5 mm from the touch sensor. In this example, 3 mm and 5 mm were measured from the outer surface of one or more front panel layers above the touch sensor.

[0058] exist Figure 6 In the example shown, line 603 is selected as the detection threshold for grounded self-capacitance measurement because no gloves, light gloves, and heavy gloves have sufficiently strong capacitive coupling, but at 3 mm and 5 mm, the capacitive coupling is below the threshold defined by line 603. Line 604 is selected as the detection threshold for grounded shield self-capacitance measurement because no gloves, light gloves, and heavy gloves have sufficiently strong capacitive coupling, and at 5 mm, the capacitive coupling is below the threshold defined by line 604. At close to 3 mm, the touch will be detected by driven shield self-capacitance measurement; according to the disclosed embodiment, it will not be detected by grounded shield self-capacitance measurement, and therefore will not be detected by dual measurement.

[0059] In some embodiments of calibrating the touch processor for dual measurements, some self-capacitance measurements may be used for informational purposes or not taken at all. In other embodiments of calibrating the touch processor for dual measurements (e.g., where projection of the electric field is less of a concern), it may be determined whether to use a grounded self-capacitance measurement or a self-capacitance measurement for one of the dual measurements after taking a test measurement.

[0060] Once the thresholds 603 and 604 are selected, they may be stored in a touch processor (e.g., Figure 3 The touch processor 303 is located at the touch processor 303, and is used to detect touch of ground self-capacitance measurement and drive shield self-capacitance measurement respectively.

[0061] Figure 7 A timing diagram of exemplary dual touch measurement sensing according to one or more embodiments of the present disclosure is shown. Figure 7, the voltage levels at the shield line 701, the active sense line 702, the other sense lines 703, and the touch output 704 are shown. The voltage levels of three phases of the dual touch measurement sensing operation are shown: a self-capacitance shield sensing phase 705, a grounded self-capacitance sensing phase 706, and a post-processing phase 707. In this example, changes in the voltage levels at 708 and 709 measured at the active sense line 702 during phases 705 and 706, respectively, indicate contact at the touch sensor. During the self-capacitance shield sensing phase 705, the shield line 701 and the other sense lines 703 are driven with a signal to match the active sense line 702 while the measurements are collected. During the grounded self-capacitance sensing phase 706, the shield line 701 is driven to ground, and the other sense lines 703 are driven to ground or Vdd (at Figure 7 During post-processing stage 707, the measurements (not shown) made during stages 705 and 706 are analyzed to detect a touch, and touch output 704 is driven to a high voltage level 710 to indicate that a touch was detected.

[0062] Many functional descriptions in this specification may be shown, described or labeled as modules, threads, steps or other classifications of programming code (including firmware) to more specifically emphasize their implementation independence. Modules may be implemented at least in part in hardware in one form or another. For example, a module may be implemented as a hardware circuit that includes a customized VLSI circuit or gate array, an existing semiconductor (such as a logic chip), a transistor or other discrete component. Modules may also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices, etc.

[0063] Modules may also be implemented using software or firmware stored on a physical storage device (eg, a computer-readable storage medium), in memory, or a combination thereof for execution by various types of processors.

[0064] The identified module of executable code may, for example, include one or more physical blocks or logical blocks of computer instructions, which may, for example, be organized as threads, objects, procedures, or functions. However, the executable files of the identified modules need not be physically located together, but may include different instructions stored in different locations, which, when logically joined together, comprise the module and achieve the stated purpose of the module.

[0065] In fact, the module of executable code can be a single instruction or many instructions, and can even be distributed on several different code segments, between different programs and on several storage devices or memory devices. Similarly, operating data can be identified and shown in this article within the module, and can be implemented in any suitable form and organized in any suitable type of data structure. Operating data can be collected as a single data set, or can be distributed in different locations, including distribution on different storage devices, and can exist at least partially as electronic signals on a system or network. In the case where a module or part of a module is implemented in software, the software portion is stored on one or more physical devices, which are referred to as computer-readable media in this article.

[0066] In some embodiments, the software part is stored in a non-transient state so that the software part or its representation continues for a period of time at the same physical location. In addition, in some embodiments, the software part is stored on one or more non-transient storage devices, which include hardware elements capable of storing non-transient states and / or signals representing the software part, although other parts of the non-transient storage device may be able to change and / or transmit signals. Examples of non-transient storage devices are flash memory and random access memory (RAM). Another example of non-transient storage device includes a read-only memory (ROM), which can store signals and / or states representing the software part for a period of time. However, the ability to store signals and / or states will not be weakened by transmitting other functions of signals that are identical to or represent stored signals and / or states. For example, a processor can access a ROM to obtain a signal representing a stored signal and / or state in order to execute corresponding software instructions.

[0067] Although moisture barriers and proximity barriers are described in conjunction with one or more embodiments, such descriptions do not imply that 100% moisture barriers and / or 100% proximity barriers are required. In other words, the present disclosure encompasses a range of embodiments resistant to moisture barriers and proximity barriers, including less than 100% moisture barriers and less than 100% proximity barriers, and their legal equivalents.

[0068] Any characterization of something in this disclosure as 'typical', 'conventional' or 'known' does not necessarily mean that the thing is disclosed in the prior art or understood in the prior art for the aspect in question. It also does not necessarily mean that it is well-known, well-understood or commonly used in the relevant art.

[0069] Although the present invention is described herein with respect to certain illustrated embodiments, those of ordinary skill in the art will recognize and appreciate that the present invention is not so limited. Rather, many additions, deletions, and modifications may be made to the illustrated embodiments and the described embodiments without departing from the scope of the present invention as claimed below and its legal equivalents. Furthermore, features from one embodiment may be combined with features of another embodiment while still being included within the scope of the present invention as contemplated by the inventor.

[0070] Additional non-limiting embodiments of the present disclosure include:

[0071] Embodiment 1: A capacitance sensing circuit comprises: a sensor comprising an electrode and a shield for the electrode, the sensor being configured to generate a measurable signal in response to a change in capacitance at or near the sensor; and a touch controller being configured to detect touch in response to a capacitance sensing measurement performed using the measurable signal, wherein the capacitance sensing measurement comprises: a driven shield self-capacitance sensing measurement, the driven shield self-capacitance sensing measurement comprising providing a driven shield signal to at least a portion of a shield of the sensor; and a grounded shield self-capacitance sensing measurement, the grounded shield self-capacitance sensing measurement comprising providing a ground signal to at least a portion of a shield of the sensor and performing a self-capacitance sensing measurement.

[0072] Embodiment 2: A circuit according to any one of Embodiments 1, wherein a first shield for shielding an electrode comprises: a back conductive material; and a front conductive material, wherein the back conductive material and the front conductive material extend in parallel planes.

[0073] Embodiment 3: The circuit of any one of Embodiments 1 and 2, wherein the first shield further comprises a conductive material disposed at lateral sides of the back conductive material and the front conductive material.

[0074] Embodiment 4: The circuit of any one of Embodiments 1 to 3, wherein the first shield is arranged relative to the electrode to facilitate directionality of the electric field projecting from the electrode.

[0075] Embodiment 5: A circuit according to any one of Embodiments 1 to 4, wherein the shield is arranged relative to the electrode so that the electric field protruding from the electrode extends further in a first direction than in a second direction substantially opposite to the first direction.

[0076] Embodiment 6: The circuit of any one of Embodiments 1 to 5, wherein the touch controller is configured to provide a signal indicative of a touch in response to the driven shield self-capacitance sensing measurement and the grounded shield self-capacitance sensing measurement.

[0077] Embodiment 7: A circuit according to any one of embodiments 1 to 6, wherein the touch controller is configured to: provide a drive shield signal to a shield line, the shield line being operably coupled to at least a portion of the shield of the sensor; provide a drive shield signal to a passive sensing line of the sensor; and measure a first measurable signal at an active sensing line of the sensor.

[0078] Embodiment 8: A circuit according to any one of embodiments 1 to 7, wherein after measuring a first measurable signal at an active sensing line, the touch controller is configured to: provide a ground signal to the shield line; provide a ground or supply voltage signal to a passive sensing line of the sensor; and measure a second measurable signal at the active sensing line of the sensor.

[0079] Embodiment 9: A touch processor comprises: a grounded shield self-capacitance sensing module, which is configured to perform self-capacitance sensing measurements after providing a ground signal to the shield of the electrode of the touch sensor; and a driven shield self-capacitance sensing module, which is configured to perform self-capacitance sensing measurements while providing a driven shield to the shield of the electrode of the touch sensor.

[0080] Embodiment 10: A touch processor according to any one of Embodiments 9, wherein: the grounded shielded self-capacitance sensing module is configured to detect a first touch in response to a first measurement being greater than a first threshold; the driven shielded self-capacitance sensing module is configured to detect a second touch in response to a second measurement being greater than a second threshold; and the touch processor is configured to report touches in response to the detected first touch and the detected second touch.

[0081] Embodiment 11: A touch processor according to any one of Embodiments 9 and 10, wherein the first threshold is selected to reduce sensitivity to proximity touch, and the second threshold is selected to reduce sensitivity to moisture touch.

[0082] Embodiment 12: A touch processor according to any one of embodiments 9 to 11, wherein the processor is configured to not report a touch in response to one of the ground shield self-capacitance sensing module and the self-capacitance shield sensing module detecting a touch and the other not detecting a touch.

[0083] Embodiment 13: A dual measurement sensing method, comprising: performing a driven shield self-capacitance sensing operation; determining a first sensing result in response to the driven shield self-capacitance sensing operation performed; performing a grounded shield self-capacitance sensing operation; determining a second sensing result in response to the grounded shield self-capacitance sensing operation performed; and determining a touch result in response to the first sensing result and the second sensing result.

[0084] Embodiment 14: A method according to any one of Embodiments 13, wherein determining a first sensing result includes: receiving a first measurement collected in response to a driven shield self-capacitance sensing operation performed; comparing the first measurement with a first threshold; and determining the first sensing result in response to the first measurement.

[0085] Embodiment 15: A method according to any one of embodiments 13 and 14, wherein determining a second sensing result includes: receiving a second measurement collected in response to a ground shield self-capacitance sensing operation performed; comparing the second measurement with a second threshold; and determining a second sensing result in response to the second measurement.

[0086] Embodiment 16: A method according to any one of Embodiments 13 to 15, wherein determining the touch result includes: detecting the touch in response to a first sensing result and a second sensing result both corresponding to the touch.

[0087] Embodiment 17: A capacitance sensing system comprises: a sensor comprising electrodes and sensing lines; an acquisition circuit operably coupled to the sensing lines; and a touch processor operably coupled to the acquisition circuit and the sensor, the touch processor being configured to detect touch in response to a first capacitance sensing measurement and a second capacitance sensing measurement, wherein one of the first capacitance sensing measurement and the second capacitance sensing measurement is characterized by water resistance and the other of the first capacitance sensing measurement and the second capacitance sensing measurement is characterized by proximity detection resistance.

[0088] Embodiment 18: The system of Embodiment 17, wherein one of the first capacitive sensing measurement and the second capacitive sensing measurement characterized by water tolerance is a driven shield capacitive sensing measurement.

[0089] Embodiment 19: The system of any one of Embodiments 17 and 18, wherein one of the first capacitive sensing measurement and the second capacitive sensing measurement characterized by proximity tolerance is a ground shield capacitive sensing measurement.

[0090] Embodiment 20: A system according to any one of Embodiments 17 to 19, wherein the sensor further comprises a shield arranged to facilitate the directionality of the electric field projecting from the electrode.

Claims

1. A capacitance sensing circuit, comprising: a sensor comprising an electrode and a shield for the electrode, the sensor being configured to generate a measurable signal in response to a change in capacitance at or near the sensor; and A touch controller, wherein the touch controller is configured to: Performing a capacitive sensing measurement using the measurable signal, the capacitive sensing measurement comprising: a driven shield self capacitance sensing measurement, the driven shield self capacitance sensing measurement comprising providing a driven shield signal to at least a portion of the shield of the sensor and performing a self capacitance sensing measurement; and a grounded shield self-capacitance sensing measurement comprising providing a ground signal to at least a portion of the shield of the sensor and performing a self-capacitance sensing measurement; and A touch is detected in response to both: determining that the driven shield self-capacitance sensing measurement exceeds a first threshold; and determining that the ground shield self-capacitance sensing measurement exceeds a second threshold, the first threshold being greater than the second threshold, wherein the first threshold is selected to reject invalid proximity touches at driven-shield self-capacitance sensing measurements above the second threshold; and Wherein the second threshold is selected to detect a valid touch at a ground shield self-capacitance sensing measurement below the first threshold.

2. The circuit of claim 1 , wherein a first shield for said shielding of said electrodes comprises: Back conductive material; and Front conductive material, The back conductive material and the front conductive material extend in parallel planes. 3 . The circuit of claim 2 , wherein the first shield further comprises a conductive material disposed at lateral sides of the back conductive material and the front conductive material.

4. The circuit of claim 1, wherein the shield is arranged relative to the electrode to facilitate directionality of an electric field projecting from the electrode.

5. The circuit of claim 4, wherein the shield is arranged relative to the electrode such that an electric field projecting from the electrode extends further in a first direction than in a second direction substantially opposite to the first direction. 6 . The circuit of claim 1 , wherein the touch controller is configured to provide a signal indicative of a touch in response to the driven shield self-capacitance sensing measurement and the grounded shield self-capacitance sensing measurement.

7. The circuit of claim 1 , wherein the touch controller is configured to: providing the driven shield signal to a shield line operatively coupled to the at least a portion of the shield of the sensor; providing the driven shield signal to a passive sense line of the sensor; as well as A first measurable signal is measured at an active sensing line of the sensor.

8. The circuit of claim 7, wherein after measuring the first measurable signal at the active sense line, the touch controller is configured to: providing a ground signal to the shielding line; providing a ground or supply voltage signal to the passive sensing line of the sensor; and A second measurable signal is measured at the active sensing line of the sensor.

9. A touch processor, comprising: a computer-readable medium having computer-readable instructions stored thereon; as well as A processing core configured to execute the computer-readable instructions, the computer-readable instructions comprising an executable code module, the executable code module comprising: a grounded shield self-capacitance sensing module configured to perform self-capacitance sensing measurements after providing a ground signal to a shield of an electrode of a touch sensor; and a driven shield self-capacitance sensing module configured to perform self-capacitance sensing measurements while providing a driven shield to the shields of the electrodes of the touch sensor; wherein the processing core is configured to report a touch in response to both: determining, by the grounded shield self-capacitance sensing module, that the self-capacitance sensing measurement after providing the ground signal to the shield exceeds a first threshold; and determining, by the driven shield self-capacitance sensing module, that the self-capacitance sensing measurement while providing the driven shield exceeds a second threshold, the second threshold being greater than the first threshold, wherein the first threshold is selected to detect a valid touch at a ground shield self-capacitance sensing measurement below the second threshold; and Wherein the second threshold is selected to reject invalid proximity touches at driven shield self-capacitance sensing measurements above the first threshold.

10. A dual measurement sensing method, comprising: Performing a driven shield self-capacitance sensing operation; determining a first sensing result in response to determining that a first measurement of the performed driven shield self-capacitance sensing operation exceeds a first threshold; performing a ground shield self-capacitance sensing operation; determining a second sensing result in response to determining that a second measurement of the performed ground shield self-capacitance sensing operation exceeds a second threshold, the first threshold being greater than the second threshold; as well as determining a touch result in response to both the first sensing result and the second sensing result, wherein the first threshold is selected to reject invalid proximity touches at the performed driven shield self-capacitance sensing operation above the second threshold; and Wherein the second threshold is selected to detect a valid touch at the performed ground shield self-capacitance sensing operation below the first threshold.

11. The method of claim 10, wherein determining the first sensing result in response to determining that a first measurement of the performed driven shield self-capacitance sensing operation exceeds the first threshold comprises: It is determined independently of the second measurement that the first measurement exceeds the first threshold.

12. A capacitance sensing system, comprising: A sensor comprising electrodes and sensing wires; an acquisition circuit operatively coupled to the sensing line; and a touch processor operably coupled to the acquisition circuit and the sensor, the touch processor configured to detect a touch in response to a first capacitance sensing measurement exceeding a first threshold and a second capacitance sensing measurement exceeding a second threshold, the first capacitance sensing measurement being characterized by water resistance and the second capacitance sensing measurement being characterized by proximity detection resistance, the first threshold being greater than the second threshold, wherein the first threshold is selected to reject invalid proximity touches at a first capacitive sensing measurement characterized by water resistance that is above the second threshold; and Wherein the second threshold is selected to detect a valid touch at a second capacitance sensing measurement characterized by proximity detection resistance that is below the first threshold.

13. The system of claim 12, wherein the first capacitive sensing measurement characterizing water tolerance is a driven shield capacitive sensing measurement.

14. The system of claim 12, wherein the second capacitive sensing measurement characterized as approach tolerance is a ground shield capacitive sensing measurement.

15. The system of claim 12, wherein the sensor further comprises a shield arranged to facilitate directionality of an electric field projecting from the electrode.

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