Capacitive sensing with differential value indication

Abstract

One or more examples relate to a detector. The signal that the detector is configured to sense is a difference value. Such a difference value can be indicative of a difference in self-capacitance indications exhibited at a first internal capacitor and a second internal capacitor. Such a difference value can be proportional to a relationship between a first material and a second material present at a device under test coupled to an electrode of the detector. Such a difference value can be proportional to a vertical height of a surface of a material present at a device under test coupled to an electrode of the detector. The difference in coupling capacitance can be obtained by performing a complementary acquisition process with a symmetric capacitive sensor. When the acquisition processes are performed substantially simultaneously, coupling errors that can be present in the self-capacitance indications are not present in the difference value.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit of U.S. Provisional Patent Application Serial No. 62 / 704,895, filed June 2, 2020, pursuant to 35 USC §119(e), the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] One or more example systems involve capacitive sensing. One or more example systems involve capacitive distance sensing and level sensing. One or more example systems involve acquiring differential values ​​that are indications of the self-capacitive component. Background Technology

[0004] Capacitive sensors are used in a variety of operating environments, such as for capacitive proximity sensing and distance sensing, but are not limited to these. Attached Figure Description

[0005] To facilitate identification of any discussion of a particular element or action, the most important one or more numbers in the reference markings refer to the figure number where the element was first introduced.

[0006] Figure 1A It is a block diagram depicting a capacitive sensing system according to one or more examples.

[0007] Figure 1B It is a block diagram depicting a capacitive sensing system according to one or more examples.

[0008] Figure 1C It is a block diagram depicting a capacitive sensing system according to one or more examples.

[0009] Figure 2 It is a block diagram depicting a detector based on one or more examples.

[0010] Figure 3 It is a flowchart depicting the process of generating difference values ​​based on one or more examples.

[0011] Figure 4 It is a flowchart depicting the acquisition process based on one or more examples.

[0012] Figure 5 It is a block diagram depicting a first drive signal applied to an electrode of a first sensor and a second drive signal applied to an electrode of a second sensor according to one or more examples, wherein the timing of the second drive signal is out of phase with the timing of the first drive signal by 180 degrees (θ-180).

[0013] Figure 6It is a diagram depicting exemplary voltage levels of a first voltage and a second voltage during an exemplary execution of a process performed by the disclosed detector to generate a differential value, according to one or more examples.

[0014] Figure 7 It is a diagram depicting exemplary voltage levels during exemplary execution of a process performed by the disclosed detector to generate differential values, according to one or more examples.

[0015] Figure 8 It is a block diagram depicting a detector portion configured to apply a protective voltage, according to one or more examples, which increases immunity to leakage current at the corresponding electrodes of the sensor.

[0016] Figure 9 A graphical view depicting exemplary voltage levels during a first and second acquisition phase, according to one or more examples.

[0017] Figure 10 This is a block diagram depicting a measurement circuit according to one or more examples. As a non-limiting example, the measurement circuit can be used to implement a first measurement circuit and a second measurement circuit with a single ADC.

[0018] Figure 11 It is a diagram depicting the self-capacitance indication and coupling capacitance indication in exemplary operation according to one or more examples. Detailed Implementation

[0019] In the following detailed description, reference is made to the accompanying drawings, which form part of this disclosure, and specific examples in which this disclosure may be practiced are shown by way of example. These examples are described in sufficient detail to enable those skilled in the art to practice this disclosure. However, other examples enabled herein may be utilized, and structural, material, and process changes may be made without departing from the scope of this disclosure.

[0020] The illustrations presented herein are not intended to be actual views of any particular method, system, device, or structure, but are merely idealized representations used to describe examples of this disclosure. In some cases, for the convenience of the reader, similar structures or components in the various figures may retain the same or similar numbering; however, similarity in numbering does not necessarily mean that the structures or components are identical in size, composition, construction, or any other property.

[0021] The following description may include examples to assist those skilled in the art in practicing the examples disclosed herein. The use of the terms "exemplary," "by example," and "for example" indicates that the related description is illustrative, and while the scope of this disclosure is intended to cover examples and legal equivalents, the use of such terms is not intended to limit the examples or the scope of this disclosure to the specified parts, steps, features, or functions, etc.

[0022] It should be readily understood that the components of the examples described herein and shown in the accompanying drawings can be arranged and designed in a variety of different configurations. Therefore, the following description of various examples is not intended to limit the scope of this disclosure, but rather to represent various examples only. While various aspects of these examples are given in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0023] Furthermore, the specific embodiments shown and described are merely examples and should not be construed as the only way to implement this disclosure unless otherwise indicated herein. Components, circuits, and functions may be illustrated in block diagram form so as not to obscure this disclosure with unnecessary detail. Rather, the specific embodiments shown and described are merely exemplary and should not be construed as the only way to implement this disclosure unless otherwise indicated herein.

[0024] Furthermore, the block definitions and logical partitioning between the blocks are examples of a particular implementation. It will be apparent to those skilled in the art that this disclosure can be practiced with many other partitioning solutions. In most cases, details regarding timing considerations, etc., have been omitted, as such details do not require a full understanding of this disclosure and are within the capabilities of those skilled in the art.

[0025] Those skilled in the art will understand that information and signals can be represented using any of a variety of different techniques and methods. For clarity of presentation and description, some accompanying drawings may show a signal as a single signal. It should be understood by those skilled in the art that a signal may represent a signal bus, wherein the bus may have multiple bit widths, and this disclosure can be implemented on any number of data signals, including a single data signal.

[0026] The various exemplary logic blocks, modules, and circuits described in conjunction with the examples disclosed herein may be implemented or performed using a general-purpose processor, a special-purpose processor, a digital signal processor (DSP), an integrated circuit (IC), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic components, discrete hardware components, or any combination thereof designed to perform the functions described herein, the term "processor" being used to encompass all of the above. A general-purpose processor may be a microprocessor, but alternatively, a processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple 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 it is configured to execute computational instructions (e.g., software code, but not limited thereto) related to the examples of this disclosure.

[0027] Examples can be described based on processes depicted as flowcharts, schematic diagrams, structural diagrams, or block diagrams. While a flowchart may describe actions as a continuous process, many of these actions may be performed in another sequence, in parallel, or substantially simultaneously. Furthermore, the order of actions can be rearranged. Processes in this document may correspond to methods, threads, functions, procedures, subroutines, subroutines, other structures, or combinations thereof. Furthermore, the methods disclosed herein can be implemented in hardware, software, or both. If implemented in software, these functions may be stored or transferred as one or more instructions or code onto a computer-readable medium. Computer-readable media includes both computer storage media and communication media, which includes any medium that facilitates the transfer of a computer program from one location to another.

[0028] Any reference to elements in this document using names such as "first," "second," etc., does not limit the number or order of those elements unless such limitation is explicitly stated. Rather, these names may be used herein as a convenient way to distinguish between two or more elements or instances of elements. Thus, referring to a first element and a second element does not imply that only two elements can be used there, or that the first element must somehow precede the second element. Furthermore, unless otherwise specified, a group of elements may include one or more elements.

[0029] As used herein, the terms “substantially” or “about” refer to, and include, the degree to which a given parameter, property, or condition is satisfied with a relatively small degree of variance (e.g., within acceptable manufacturing or operational tolerances). By way of example, depending on the specific parameter, property, or condition that is substantially satisfied, it may be satisfied at least 90%, at least 95%, or even at least 99%.

[0030] As used herein, any relational terms (such as "above", "on top of", "below", "on", "under", "upper", "lower", "upper" or "lower", but not limited thereto) are used for clarity and convenience in understanding this disclosure and the accompanying drawings, and such relational terms do not imply or depend on any particular preference, orientation or order unless the context clearly indicates otherwise.

[0031] In this description, the term "coupled" and its derivatives may be used to indicate that two elements cooperate or interact with each other. When an element is described as "coupled" to another element, the element may be in direct physical or electrical contact, or an intermediary element or layer may be present. In contrast, when an element is described as "directly coupled" to another element, no intermediary element or layer is present. The term "connection" is used interchangeably with the term "coupled" in this specification and has the same meaning as "coupled," unless otherwise expressly indicated or the context will otherwise indicate to a person skilled in the art. It should be understood that when an element is referred to as "connected" or "coupled" to a first element and a second element, the element is coupled to the first element and the element is coupled to the second element.

[0032] When an element is referred to herein as being “electrically coupled” to another element, one or more of the charge or signal may be transferred between the element and the other element directly or via an intermediary element (if present). It should be understood that when an element is referred to herein as being “electrically connected” or “electrically coupled” to a first element and a second element, one or more of the charge and / or signal may be transferred between the first element and the second element via the element, directly or via an intermediary element (if present).

[0033] Self-capacitance is the capacitance between an electrode and a virtual ground, and this virtual ground may be known or unknown.

[0034] When measuring the self-capacitance of an electrode, this is typically done relative to a signal with a local ground as a reference potential, and this signal serves as an indication of the self-capacitance or the magnitude of any variation therein. The coupling between the electrode and the dummy ground may vary, affecting the electrode's self-capacitance and its indication; such variations may be known or unknown. As a non-limiting example, if the electrode is coupled to a material of interest, there may be electrical coupling between the material of interest and the ground potential or local ground of the capacitance sensor due to environmental factors (e.g., objects contacting the material or the device under test containing the material, but not limited to these), which could affect the electrode's self-capacitance and its indication. Furthermore, electrical noise can degrade the accuracy and resolution of the signal and the values ​​generated to represent the signal. As a non-limiting example, if the signal or its representative value is used to infer information about the material of interest, the presence of noise in the signal / value, as well as variations due to reasons other than material changes, reduces the correlation between the signal and the material of interest and the information inferred about the material of interest from the signal / value. The presence of such effects is referred to herein as "coupling error".

[0035] In applications that utilize self-capacitance indication to infer information about materials of interest, such as level sensing (e.g., the level of a liquid, solution, or mixture in a container, but not limited to this), coupling errors can have undesirable, even catastrophic, effects on the system or process utilizing such information. Furthermore, the inventors of this disclosure have recognized that it is often difficult to compensate for coupling errors during operation without worsening them. Moreover, the magnitude of coupling errors depends on many factors, such as the power topology of the capacitive sensor (e.g., isolated or non-isolated, switched, linear, battery-powered, but not limited to this), changes in coupling due to operational variations in other application loads, and operational variations in material coupling to ground (e.g., such as hand coupling, but not limited to this), and it is difficult to predict and resolve all of these issues in advance.

[0036] In coupling error-sensitive applications, there are sometimes attempts to increase the degree of controlled capacitance coupling between the material and the ground of the capacitive sensor circuit in order to reduce the effect of variations between the material of interest and ground. The inventors of this disclosure recognize that, in practice, fully realizing the benefits of this approach is challenging due to mechanical, electrical, or cost constraints. Sometimes attempts are made to couple the material of interest to ground; however, the inventors of this disclosure recognize that this implies other constraints, such as electrical insulation, introducing foreign metallic bodies (conductors used for the grounding path) into the potentially corroding material, and regulatory constraints, such as health concerns in food and beverage applications.

[0037] The inventors of this disclosure recognize that, as a non-limiting example, a solution that can naturally reduce coupling errors without some or all of the drawbacks discussed above would be desirable.

[0038] The inventors of this disclosure recognized that, in the case of changes in the self-capacitance of the electrodes, these changes may be caused by changes in the material of interest, which may be caused by changes in the potential between the material of interest / circuit of the capacitive sensor and ground, and the components of the change may be separate due to both the change in the material of interest and the change in the potential between the material of interest / circuit of the capacitive sensor and ground. The inventors of this disclosure recognized the desire to observe or capture the component of the self-capacitance change caused by the change in the material of interest, which is independent of the change in the potential between the material of interest / circuit of the capacitive sensor and ground.

[0039] As used in this article, “coupling capacitance” refers to the component of an electrode’s self-capacitance that is capacitively coupled to the local reference potential of the electrode.

[0040] Figure 1A This is a block diagram depicting a capacitance sensing system 100 according to one or more examples. The capacitance sensing system 100 is generally configured to generate a differential value 106 proportional to a property 112 of a material 110 present at a device under test (DUT 114). The property 112 of the material 110 can vary, and the differential value 106 can reflect the variation in property 112. In one or more examples, the property 112 of the material 110 may be based at least in part on a relationship 116 between a first material 140a and a second material 140b in the material 110. The relationship 116 between the first material 140a and the second material 140b in the material 110 can vary, and the property 112 of the material 110 can reflect the variation in relationship 116. In this way, property 112 is an indication of the relationship 116 between the first material 140a and the second material 140b.

[0041] In one or more examples, the values ​​of property 112, relation 116, and the measurements of the first material 140a, second material 140b, or DUT 114 that are proportional to them may be based at least in part on the corresponding coupling capacitance (C) of the electrodes 108 of detector 102. S The detector 102 is generally configured to generate a differential value 106, which is an indication of the corresponding coupling capacitance of the electrode 108, including when coupled to the DUT 114. The detector 102 may generate signals at a first internal capacitor and a second internal capacitor 104, respectively, which are self-capacitance indications 124 of the electrode 108 of the detector 102. As discussed herein, the detector 102 can generate the differential value 106 by calculating the difference between the self-capacitance indications 124.

[0042] Detector 102 generates a signal and value for self-capacitance indication 124 by performing a specific process susceptible to coupling errors. Self-capacitance indication 124 includes a coupling capacitance indication. Self-capacitance indication 124 may additionally include a coupling error indication. As discussed above, the presence of a coupling error indication may affect the correspondence between self-capacitance indication 124 and the coupling capacitance of electrode 108. By taking the difference between the corresponding self-capacitance indications 124 of electrode 108, detector 102 generates a value indicating the coupling capacitance of electrode 108, namely, a difference value 106. More specifically, detector 102 is configured to generate self-capacitance indication 124 such that coupling error indications present in the corresponding self-capacitance indication 124 can be individually canceled out. The coupling capacitance indication present in the corresponding self-capacitance indication 124 is retained in the difference value 106.

[0043] Figure 1B This is a block diagram depicting a capacitive sensing system 100. Electrode 108 has coupling capacitance C associated with corresponding electrodes 118a and 118b in electrode 108, respectively. S1 and C S2 This is at least one component of its corresponding self-capacitance. Coupling capacitance C S1 and C S2 They are basically the same. The differential value of 106 is the coupling capacitance C. S1 and C S2 This indicates, and therefore is an indication of, the corresponding coupling capacitance of electrodes 118a and 118b in electrode 108. Coupling capacitance C S1 and C S2 This can also be characterized as a component of the self-capacitance of the corresponding electrodes 118a and 118b in electrode 108 associated with the coupling between the corresponding electrodes 118a and 118b in electrode 108 and the reference potential 122. Furthermore, changes in the coupling between the corresponding electrodes 118a and 118b and the reference potential 122 are reflected in the coupling capacitance C. S1 and C S2 The changes and the magnitude of the difference value 106.

[0044] In one or more examples, various inferences can be reliably made at least in part based on the difference value 106. Non-limiting examples of inferences include the corresponding amount or level of material 140a or 140b or the utilization of DUT 114 (e.g., utilized capacity, remaining capacity, but not limited thereto).

[0045] Figure 1C This is a diagram depicting a capacitive sensing system 100. A first sensor 130 and a second sensor 132 are arranged adjacent to a volume 136 (e.g., defined by the DUT 114 of FIG1). The respective lengths of the corresponding electrodes 118a and 118b of the first sensor 130 and the second sensor 132 extend continuously along a first vertical direction (e.g., as shown in the figure). Figure 1C (The depicted direction extends along the Y direction, but is not limited thereto). The first vertical direction may extend substantially parallel to the boundary plane of the vertical orientation of volume 136. Volume 136 represents the volume of space occupied by material 110 (reference numeral "110" refers to the entire contents of volume 136). Material 110 includes a first material 140a (e.g., a liquid, but not limited thereto) and a second material 140b (e.g., air, but not limited thereto), which are different from each other. In various examples, material 110 may have a heterogeneous or homogeneous state. As a non-limiting example of a heterogeneous state, a non-zero amount of the first material 140a and the second material 140b may be present in material 110 (e.g., DUT 114 has some liquid but is not full, and the rest of the volume has air, but is not limited thereto). As a non-limiting example of a homogeneous state, one or the other of the first material 140a or the second material 140b is present (e.g., DUT114″ is filled with the first material 140a or the second material 140b, but is not limited thereto).

[0046] The coupling capacitance of electrodes 118a and 118b can vary proportionally to a change in property 112, which is the dielectric property of material 110. Non-limiting examples of dielectric properties include dielectric geometry (e.g., the thickness or width of material 110, but not limited to) and dielectric material properties (i.e., characterization of energy absorption from an electric field). The dielectric property of material 110 can be based at least in part on the corresponding dielectric properties of the first material 140a and the second material 140b, and therefore at least in part on the ratio of the corresponding amounts of the first material 140a and the second material 140b present in volume 136. The ratio of the corresponding amounts of the first material 140a and the second material 140b can vary. The dielectric property of material 110 can vary in response to a change in the ratio of the corresponding amounts of the first material 140a and the second material 140b present in volume 136. In one or more examples, the corresponding coupling capacitance of electrodes 118a and 118b can be related to relation 116 (…). Figure 1A The relationship 116 is an indication of the ratio of corresponding amounts of the first material 140a and the second material 140b. The ratio of corresponding amounts of the first material 140a and the second material 140b can be an indication of the level or vertical height of the first material 140a or the second material 140b. The vertical height of the surface 120 of the first material 140a can vary (e.g., rise or fall, but is not limited thereto). As a non-limiting example, various amounts of the first material 140a can be added or removed from the volume 136, and similar amounts (by volume) of the second material 140b can be removed or added. In one or more examples, the surface 120 can be substantially flat or blocky, substantially parallel or angled to the surface on which the volume 136 is disposed.

[0047] Coupling capacitance (C) of electrodes 118a and 118b s1 C s2 C s1 =C s2 The value of ) can vary proportionally with the change in the vertical height of the surface 120 of the first material 140a. Specific, non-limiting examples depicting the change in the vertical height 138 of the surface 120 (which can also be characterized as the "horizontal plane" of the first material 140a) are the first vertical height 126, the second vertical height 128, and the third vertical height 134. Figure 1C Different values ​​of the coupling capacitance, C, for electrodes 118a and 118b at the first vertical height 126, the second vertical height 128, and the third vertical height 134 are depicted respectively. Svaluel C svalue2 and C Svalue3 .

[0048] Figure 2 This is a block diagram depicting a detector 200 according to one or more examples. Detector 200 is generally configured to generate a differential value 220, which is the coupling capacitance C of the corresponding electrodes 228 and 230 of the first sensor 208 and the second sensor 210. s1 and C s2 The amplitude indication, where C s1 =C s2 Detector 200 is Figure 1A A non-restrictive example of detector 102.

[0049] In one or more examples, the first sensor 208 and the second sensor 210 are symmetrical. As used herein, when a capacitive sensor (such as the first sensor 208 and the second sensor 210) is described as "symmetrical," it means that the capacitive sensor responds to substantially the same degree of change in the coupling capacitance of the respective electrodes 228 and 230. As a non-limiting example, symmetrical capacitive sensors exhibit substantially the same degree of capacitive coupling with the material and experience substantially the same degree of change in capacitive coupling in response to changes in the dielectric properties of the material that affect the dielectric constant K of the material. As a non-limiting example, non-limiting examples of changes in dielectric properties due to pressure or temperature include changes in dielectric geometry (e.g., changes in thickness or width, but not limited to) or changes in dielectric material properties (i.e., changes in the characterization of energy absorption from an electric field). In one or more examples, to increase the symmetry between the first sensor 208 and the second sensor 210, the areas A1 and A2 (A1 = A2) of the respective electrodes 228 and 230, the capacitance of the internal capacitor (C i1 =C i2One or more of the reference voltage level and the ground level are essentially the same.

[0050] Figure 2 The circuit depicted for the first external capacitor 214 and the second external capacitor 216 is used to represent the corresponding coupling capacitance C of electrodes 228 and 230. s1 and C s2 The equivalent circuit, where these electrodes are the corresponding plates of the first external capacitor 214 and the second external capacitor 216. It is worth noting that in one or more examples, the self-capacitance and the coupling capacitance C... s1 and C s2 The actual value may be known or unknown because the indication of the self-capacitance and coupling capacitance of the corresponding electrodes 228 and 230 of the first external capacitor 214 and the second external capacitor 216 is utilized, as discussed herein.

[0051] In the case of each of the first external capacitor 214 and the second external capacitor 216, a material or liquid (not depicted) serves as the dielectric of the respective first external capacitor 214 and second external capacitor 216, and electrodes 228 and 230 are insulating electrodes arranged near a portion of the wall defining the holding area of ​​the DUT (e.g., a basin, chamber, hollow portion, cavity, or space in which material exists or will exist, but not limited thereto), serving as the respective plates of the first external capacitor 214 and the second external capacitor 216. It is not required that electrodes 228 or 230 be in physical contact with the wall of the DUT or the material present in the DUT, or with another material in physical contact with the DUT or the material present therein.

[0052] While examples may appear to refer to rigid-walled or fixed-volume DUTs, this is not necessary, and rigid-walled, flexible, fixed, and non-fixed-volume DUTs (e.g., bags, chambers, but not limited thereto, for dispensing liquids via pumps) are particularly considered and do not exceed the scope of this disclosure.

[0053] In one or more examples, a first sensor 208 is configured to generate a first voltage V1 of the self-capacitance of an indicator electrode 228, and a second sensor 210 is configured to generate a second voltage V2 of the second self-capacitance of an indicator electrode 230. In one or more examples, voltages V1 and V2 are generated by performing different but complementary acquisition processes, respectively, via a first acquisition circuit 222 of the first sensor 208 and a second acquisition circuit 224 of the second sensor 210. The first acquisition circuit 222 and the second acquisition circuit 224 each include a plurality of switches controlled to perform either the first acquisition process or the second acquisition process (as applicable), and will be referenced later. Figure 4 Let's have a discussion.

[0054] At least in part, in response to the first acquisition circuit 222 performing a first acquisition process and the second acquisition circuit 224 performing a second acquisition process, voltages V1 and V2 are generated at the first internal capacitor 212 of the first acquisition circuit 222 and the second internal capacitor 218 of the second acquisition circuit 224, respectively. These voltages represent voltage levels indicating the self-capacitance of the first external capacitor 214 and the second external capacitor 216, respectively. These self-capacitances may (but do not necessarily) include coupling errors.

[0055] In one or more examples, an increase or decrease in the voltage level of the first voltage V1 should reflect a corresponding proportional increase or decrease in the self-capacitance indication, while a decrease or increase in the voltage level of the second voltage V2 should reflect a corresponding proportional increase or decrease in the second self-capacitance indication.

[0056] Measurement circuit 226 includes a first analog-to-digital converter (ADC) 202 of a first sensor 208, a second ADC 204 of a second sensor 210, and a processor 206. The first ADC 202 and the second ADC 204 are arranged to generate a first value R1 and a second value R2, respectively, corresponding to the respective voltage levels of voltages V1 and V2. Therefore, the first value R1 and the second value R2 indicate self-capacitance, and the first voltage V1 and the second voltage V2 also indicate self-capacitance. In one or more examples, a first internal capacitor 212 and a second internal capacitor 218 may be arranged and sized such that the respective voltage levels of voltages V1 and V2 are within the operating range of the first ADC 202 and the second ADC 204. The processor 206 is generally configured to calculate the difference between the first and second values ​​(i.e., R1-R2) and generate a value reflecting the difference between the first value R1 and the second value R2 and indicating the coupling capacitance C. s1 C s2 The difference value is 220.

[0057] In a given execution of the measurement, either the first sensor 208 or the second sensor 210 can be used according to the first acquisition process (e.g., Figure 4 The first acquisition process 424, but not limited thereto) or the second acquisition process (e.g., Figure 4 The second acquisition process 426, but not limited thereto, is used for operation. In one or more examples, the first sensor 208 and the second sensor 210 may be operated using their respective switches S1, S2, S3, and S4. As used herein, when a switch or connection via a switch is described as “on”, it means that current flows through the switch or connection, and when a switch is described as “off”, it means that current does not flow through the switch or connection.

[0058] Figure 3 It is a flowchart depicting a process 300 for generating differential values ​​as an indication of coupling capacitance, based on one or more examples.

[0059] At operation 302, process 300 obtains a differential value of the difference in self-capacitance indications of the indicating electrodes. The self-capacitance indication can be expressed at a first internal capacitor and a second internal capacitor. In one or more examples, the self-capacitance indication can optionally be obtained by performing a first acquisition process and a second acquisition process, which are different from each other.

[0060] At operation 304, process 300 optionally responds at least partially to a differential value to infer the vertical height of the surface of the material present at the device under test coupled to the electrode. In one or more examples, process 300 optionally infers a relationship between a first material and a second material present at the device under test, and optionally responds at least partially to a differential value to infer the vertical height of the surface of one of the first material and the second material.

[0061] Figure 4 It is a flowchart depicting a differential acquisition process 400 for acquiring differential values ​​of an indicative coupling capacitance, according to one or more examples.

[0062] The differential acquisition process 400 includes a first acquisition process 424 and a second acquisition process 426. The first acquisition process 424 and the second acquisition process 426 are non-limiting examples of the first acquisition process and the second acquisition process of process 300.

[0063] In one or more examples, detector 200 (or more generally, differential acquisition process 400) may be configured to operate either the first sensor 208 or the second sensor 210 according to a first acquisition process 424 or a second acquisition process 426 for a given execution of differential acquisition process 400. Figure 4 In the particular non-limiting example depicted, the first sensor 208 performs the first acquisition process 424 and the second sensor 210 performs the second acquisition process 426.

[0064] In one or more examples, the first acquisition process 424 and the second acquisition process 426 are performed substantially simultaneously. The following operations are performed substantially simultaneously: operations 404 / 412, 406 / 414, 408 / 416, and 410 / 418. As discussed below, this ensures that the sensors performing the first acquisition process 424 and the second acquisition process 426 are affected in the same but opposite ways, as discussed below.

[0065] At operation 402, differential acquisition process 400 initiates measurement. In one or more examples, differential acquisition process 400 initializes a first sensor (e.g., first sensor 208, but not limited thereto) to perform measurement according to first acquisition process 424, and initializes a second sensor (e.g., second sensor 210, but not limited thereto) to perform measurement according to second acquisition process 426.

[0066] At operation 404, the first acquisition process 424 charges the first internal capacitor to the reference voltage Vref. In the case of the first sensor 208, the connection via switches S1, S3 and S4 is disconnected, and the connection between Vref and the first internal capacitor 212 is connected via switch S2, while the connection between the first internal capacitor 212 and the first external capacitor 214 and ground is disconnected via switch S2.

[0067] At operation 406, the first acquisition process 424 discharges the first external capacitor (i.e., discharges the self-capacitance of the electrode represented by the first external capacitor). In the case of the first sensor 208, the connection via switches S1 and S3 is broken, the connection between the first external capacitor 214 and ground is connected via switch S4, the connection between VREF and the first internal capacitor 212 is connected via switch S2, and the connection between the first internal capacitor 212 and both the first external capacitor 214 and ground is broken via switch S2. In the case of the first sensor 208, operations 404 and 406 can be performed simultaneously.

[0068] At operation 408, the first acquisition process 424 couples the first internal capacitor and the first external capacitor. With the first sensor 208, the connection via switches S1, S3, and S4 is broken, the connection between the first internal capacitor 212 and the first external capacitor 214 is connected via switch S2, and the connection between the first internal capacitor 212 and both Vref and ground is broken via switch S2. This arrangement initiates charge sharing from the first internal capacitor 212 to the first external capacitor 214.

[0069] It is worth noting that, at least in part, in response to operations 404, 406, and 408, the voltage level of the first voltage V1 is the reference voltage Vref, the first coupling capacitance Cs1 of the first external capacitor 214, and the first internal capacitance C of the first internal capacitor 212. i1 The function.

[0070] At operation 410, the first acquisition process 424 measures the first voltage V1 present on the first internal capacitor to obtain a first value. The first value represents the voltage level of the first voltage V1. In the case of the first sensor 208, the connection between the first ADC 202 and the first internal capacitor 212 is turned on via switch S1, the connection between the first internal capacitor 212 and the first external capacitor 214 is turned on via switch S2, the connection between the first internal capacitor 212 and Vref and ground is turned off via switch S2, and the corresponding connections of switches S3 and S4 are turned off. The first voltage V1 is measured via the first ADC 202 to obtain the first value R1.

[0071] Moving to the second acquisition process 426, at operation 412, the second acquisition process 426 discharges the second internal capacitor. In the case of the second sensor 210, the connection via switches S1, S3 and S4 is broken, and the connection between ground and the second internal capacitor 218 is made on via switch S2, while the connection between the second internal capacitor 218 and the second external capacitor 216 and Vref is broken on both via switch S2.

[0072] At operation 414, the second acquisition process 426 charges the second external capacitor to the reference voltage Vref. (That is, it charges the self-capacitance of the electrode represented by the second external capacitor to the reference voltage Vref). In the case of the second sensor 210, the connection via switches S1 and S4 is disconnected, the connection between the second external capacitor 216 and Vref is connected via switch S3, the connection between ground and the second internal capacitor 218 is connected via switch S2, and the connection between the second internal capacitor 218 and both the second external capacitor 216 and ground is disconnected via switch S2.

[0073] At operation 416, the second acquisition process 426 couples the second internal capacitor and the second external capacitor. With the second sensor 210, the connection via switches S1, S3, and S4 is broken, the connection between the second internal capacitor 218 and the second external capacitor 216 is connected via switch S2, and the connection between the second internal capacitor 218 and both Vref and ground is broken via switch S2. This arrangement initiates charge sharing from the second external capacitor 216 to the second internal capacitor 218.

[0074] It is worth noting that, at least in part in response to the execution of operations 412, 414, and 416, the voltage level of the second voltage V2 is the reference voltage Vref and the second coupling capacitance C of the second external capacitor 216. s2 The second internal capacitor C of the second internal capacitor 218 i2 The function.

[0075] At operation 418, the second acquisition process 426 measures the second voltage V2 present on the second internal capacitor to obtain a second value. The second value represents the voltage level of the second voltage V2. In the case of the second sensor 210, the connection between the second ADC 204 and the second internal capacitor 218 is turned on via switch S1, the connection between the second internal capacitor 218 and the second external capacitor 216 is turned on via switch S2, the connection between the second internal capacitor 218 and Vref and ground is turned off via switch S2, and the corresponding connections of switches S3 and S4 are turned off. The second voltage V2 is measured via the second ADC 204 to obtain the second value R2.

[0076] At optional operation 420, differential acquisition process 400 may optionally utilize first sensor 208 to perform another execution of second acquisition process 426 and utilize second sensor 210 to perform another execution of first acquisition process 424. The first value and the second value obtained by first sensor 208 performing first acquisition process 424 and second acquisition process 426 can be combined to obtain a first value R1, and the values ​​obtained by second sensor 210 performing first acquisition process 424 and second acquisition process 426 can be combined to obtain a second value R2.

[0077] Figure 6 (As will be described further below) depicts the voltage generated during the differential acquisition process 400 without optional operation 420, and Figure 7 (As will be described further below) depicts the voltage generated during the differential acquisition process 400 with optional operation 420.

[0078] At operation 422, differential acquisition process 400 calculates the difference between the first value R1 and the second value R2 to obtain the differential value indicating the coupling capacitance. The obtained difference indicates the first coupling capacitance C. S1 Second coupling capacitor C S2 The difference in self-capacitance indicates the distance from the material.

[0079] It is worth noting that since the first acquisition process 424 and the second acquisition process 426 described below are executed substantially simultaneously, they are affected by the same noise and coupling errors. Because the first sensor and the second sensor (e.g., first sensor 208 and second sensor 210, but not limited thereto) are symmetrical, they are affected by the same noise and environmental coupling errors to the same extent; that is, there are coupling errors of substantially the same magnitude. During the execution of the first acquisition process 424 and the second acquisition process 426, the net changes in voltage and charge flow direction experienced at the first sensor and the second sensor are of opposite polarity; therefore, the signals are affected by noise and environmental coupling errors in opposite ways, i.e., the corresponding coupling errors have opposite signs. Complementary (e.g., substantially the same magnitude but substantially opposite signs) coupling errors exist in voltages V1 and V2, and are captured by values ​​R1 and R2. When R2 is subtracted from R1, the coupling errors are canceled out, and a value proportional to the distance is obtained where the coupling error is nonexistent or irrelevant.

[0080] Figure 5 This is a block diagram depicting a first drive signal 502 applied to electrode 228 of the first sensor 208 and a second drive signal 504 applied to electrode 230 of the second sensor 210, wherein the timing of the second drive signal 504 is out of phase with the timing of the first drive signal 502 by 180 degrees (θ-180). The first drive signal 502 is a non-limiting example of a drive signal applied to electrode 228 during the execution of the first acquisition process 424, and the second drive signal 504 is a non-limiting example of a drive signal applied to electrode 230 during the execution of the second acquisition process 426. In one or more examples, the first drive signal 502 and the second drive signal 504 are applied synchronously.

[0081] In optional operation 420, where the first sensor 208 performs the second acquisition process 426 and the second sensor 210 performs the first acquisition process 424, the phases of the corresponding drive signals used to generate these measurement signals can remain the same or can vary, as long as the corresponding timings are 180 degrees out of phase.

[0082] Figure 6 These are graphs depicting exemplary voltage levels of the first voltage V1 and the second voltage V2, respectively, in the first graph 602 and the second graph 604, during an exemplary execution of the differential acquisition process 400 performed by the detector 200.

[0083] At time t0, the first internal capacitor 212 of the first sensor 208 is charged to Vdd (reference voltage Vref), as shown by the dashed line in the first curve 602, and the second internal capacitor 218 of the second sensor 210 is discharged to Vss (ground or system ground), as shown by the dashed line in the second curve 604. During the duration from t0 to t1, the first external capacitor 214 is discharged to Vss, as shown by the solid line in the first curve 602, and the second external capacitor 216 is charged to Vdd, as shown by the solid line in the second curve 604.

[0084] At time t1, the first internal capacitor 212 and the first external capacitor 214 are coupled, and from t1 to time t2, there is charge sharing from the first internal capacitor 212 to the first external capacitor 214. This charge sharing reduces the first voltage V1 at time t2 to the level indicating the first coupling capacitance C. S1 The voltage level is shown in curve 606, where the solid line in the first curve 602 represents the voltage across the first external capacitor 214. Also at time t1, the second internal capacitor 218 and the second external capacitor 216 are coupled, and from t1 to time t2, there is a charge sharing from the second external capacitor 216 to the second internal capacitor 218. This charge sharing at time t2 increases the second voltage V2 to the level indicating the second coupling capacitance C. S2 The voltage level is shown in curve 608, where the solid line of the second curve 604 shows the voltage across the second external capacitor 216.

[0085] In the case of the first sensor 208, curve 606 thus represents the outflow of charge from the first internal capacitor 212 to the first external capacitor 214, and a net negative change in the voltage level of the first voltage V1 from time t1 to time t0. In the case of the second sensor 210, curve 608 represents the inflow of charge from the second external capacitor 216 to the second internal capacitor 218, and a net positive change in the voltage level of the second voltage V2 from time t1 to time t0.

[0086] Figure 7 This is a graph depicting exemplary voltage levels during exemplary execution of a differential acquisition process 400 (including optional operation 420) performed by detector 200.

[0087] Figure 7The voltage levels at the first sensor 208 and the second sensor 210 are depicted during two acquisition phases (acquisition phase 1 and acquisition phase 2). During acquisition phase 1, the first sensor 208 performs a first acquisition process 424, as depicted in the upper graph, and the second sensor 210 performs a second acquisition process 426, as depicted in the lower graph. During acquisition phase 2, the first sensor 208 performs the second acquisition process 426, as depicted in the upper graph, and the second sensor 210 performs the first acquisition process 424, as depicted in the lower graph.

[0088] Curves 702a and 702b represent the voltage levels exhibited by voltage V1 (on the internal capacitor) during acquisition phase 1 and acquisition phase 2, respectively. Curves 704a and 704b represent the voltage levels exhibited by the voltage on the external capacitor during acquisition phase 1 and acquisition phase 2, respectively.

[0089] The third curves 706a and 706b represent the voltage levels exhibited by voltage V2 during acquisition phase 1 and acquisition phase 2, respectively. The fourth curves 708a and 708b represent the voltage levels exhibited by the external capacitor during acquisition phase 1 and acquisition phase 2, respectively. During time t21 of acquisition phase 1, the voltage level obtained by the first sensor 208 is... Figure 7 The first value VA1(t21) is represented and obtained by the second sensor 210. Figure 7 The second value VB2(t21) is represented. During time t22 of phase 2, it is obtained by the first sensor 208. Figure 7 The third value VB1(t22) is represented and obtained by the second sensor 210. Figure 7 The fourth value represented is VA2(t22).

[0090] A first value VA1(t21) is obtained at time t21, and from time t11 to time t21, the first voltage V1 exhibits an overall decreasing voltage level from VDD to VSS. A second value VB1(t22) is obtained at time t22, and from time t12 to time t22, the first voltage V1 exhibits an overall increasing voltage level from VSS to VDD. When VA1(t21) and VB1(t22) are combined, at least some of the noise effect on the first sensor 208 is canceled out.

[0091] Similarly, a third value VB2(t21) is obtained at time t21, and from time t11 to time t21, the first voltage V1 exhibits an overall increasing voltage level from VSS to VDD. A fourth value VA2(t22) is obtained at time t22, and from time t12 to time t22, the second voltage V2 exhibits an overall decreasing voltage level from VDD to VSS. When VB2(t21) and VA2(t22) are combined, at least some of the noise effect on the second sensor 210 is canceled out.

[0092] The difference value obtained by responding at least partially to the two-phase measurements performed by each sensor can be expressed as: Difference value = VA1(t11) - VB2(t11) + VA2(t22) - VB1(t22). Alternatively or additionally, in one or more examples, the difference value can be calculated for individual phase measurements, and then the two-phase measurement results can be calculated using the individual phase measurement results, the difference value being expressed as: value obtained from the first phase = VA1(t11) - VB2(t11), and value obtained from the second phase = VA2(t22) - VB1(t22), and difference value = VA1(t11) - VB2(t11) + VA2(t22) - VB1(t22).

[0093] Figure 8 This is a block diagram depicting a detector section 800 configured to apply a protective voltage (i.e., referred to as drive shielding) that increases, but is not limited to, immunity to leakage current at the respective electrodes of the first and second sensors (e.g., electrode 228 of the first sensor 208 and electrode 230 of the second sensor 210).

[0094] A first protection line 814 is disposed on a first support structure portion 806 (e.g., a portion of a printed circuit board (PCB), but not limited thereto), located in a path surrounding the electrode 810 disposed on the first support structure portion 806. Similarly, a second protection line 824 is disposed on a second support structure portion 808 (which may be the same as or different from the first support structure portion 806), located in a path surrounding the electrode 812. A first drive protection electrode 820 coupled to the first protection line 814 is provided for receiving a first protection voltage 816 generated by the first protection circuit 802, and a second drive protection electrode 822 coupled to the second protection line 824 is provided for receiving a second protection voltage 818 generated by the second protection circuit 804.

[0095] In one or more examples, the corresponding waveforms of the first protection voltage 816 and the second protection voltage 818 can track the waveforms of the voltages at the first external capacitor 214 and the second external capacitor 216. However, a 1:1 correspondence of waveforms is not required as long as the total net change in voltage level exhibited by the first protection voltage 816 and the second protection voltage 818 is the same as the total net change in voltage level exhibited by the voltages across the first external capacitor 214 and the second external capacitor 216 during the duration of interest. In one or more examples, the first protection circuit 802 and the second protection circuit 804 may be configured with information about the net voltage change and timing to generate the first protection voltage 816 and the second protection voltage 818, respectively, which exhibit voltage levels suitable for protection.

[0096] Figure 9 Exemplary voltage levels during the first and second acquisition phases of an exemplary differential acquisition process 400, including optional operation 420, are depicted. Figure 8 A graphical view of the protection voltage.

[0097] First schematic view 910 depicts the voltage levels exhibited at electrode 810 and first protection voltage 816 during the first and second acquisition phases of the exemplary differential acquisition process 400. Second schematic view 912 depicts the voltage levels exhibited by second protection voltage 818 and electrode 812 during the first and second acquisition phases of the exemplary differential acquisition process 400.

[0098] The first acquisition phase is from time t01 to t21, and the second acquisition phase is from time t02 to t22. Figure 9 Not depicted in the middle Figure 6 and Figure 7 The labels depicted in the figure are used to mark the times t11 and t12 when charge sharing begins between the internal and external capacitors, in order to avoid unnecessarily obscuring the figures and their descriptions.

[0099] In the first schematic view 910, the first curve 902a represents the voltage level exhibited by the first protection voltage 816 during the first acquisition phase, and the first curve 902b represents the voltage level exhibited by the first protection voltage 816 during the second acquisition phase. The second curve 904a represents the voltage level exhibited by the electrode 810 during the first acquisition phase, and the second curve 904b represents the voltage level exhibited by the electrode 810 during the second acquisition phase.

[0100] In the second schematic view 912, the third curve 906a represents the voltage level of the second protection voltage 818 during the first acquisition phase, and the third curve 906b represents the voltage level of the second protection voltage 818 during the second acquisition phase. The fourth curve 908a represents the voltage level exhibited by the electrode 812 during the first acquisition phase, and the fourth curve 908b represents the voltage level exhibited by the electrode 812 during the second acquisition phase.

[0101] From time t01 to time t21, the net change in voltage level exhibited by electrode 810 and first protection voltage 816, depicted by second curve 904a and first curve 902a, and the polarity of this change are the same, i.e., a net change from VSS to VDD. From time t02 to immediately following time t22, the net change in voltage level exhibited by electrode 810 and first protection voltage 816, depicted by second curve 904b and first curve 902b, and the polarity of this change are the same, i.e., a net change from VDD to VSS. From time t01 to time t21, the net change in voltage level exhibited by electrode 812 and first protection voltage 818, depicted by fourth curve 908a and third curve 906a, and the polarity of this change are the same, i.e., a net change from VDD to VSS. From time t02 to immediately following time t22, the net change in voltage level exhibited by electrode 812 and the second protection voltage 818, as depicted by the fourth curve 908b and the third curve 906b, and the polarity of this change are the same, namely, the net change from VSS to VDD.

[0102] It is worth noting that immediately following t22, the second curve 904b drops to VSS, and the fourth curve rises to VDD. This could reflect the discharge of the first external capacitor or the charging of the second external capacitor, optionally as part of an optional new execution of operation 412 or operation 404 of the second acquisition process 426 or the first acquisition process 424, respectively. This could optionally reflect the drive of electrode 810 to VSS or electrode 812 to VDD, so the net change in voltage level is the same as that of the protection voltages 816 and 818.

[0103] The presence of the first protection voltage 816 and the second protection voltage 818 (which exhibits a voltage level that tracks the net change in voltage level exhibited by electrodes 810 and 812 and the polarity of such change) protects electrodes 810 and 812 from leakage current.

[0104] Figure 10This is a block diagram depicting a measurement circuit 1000. As a non-limiting example, this measurement circuit can be used to implement a first measurement circuit 226 and a second measurement circuit 226 using a single ADC 1004. The measurement circuit 1000 includes a first sample-and-hold circuit 1006 and a second sample-and-hold circuit 1008, which are respectively configured to sample the voltage of a continuously varying analog signal and hold its value at a constant level for a specified duration. In one or more examples, the respective inputs of the first sample-and-hold circuit 1006 and the second sample-and-hold circuit 1008 may be coupled via a first terminal 1010 and a second terminal 1012 to the sensing lines of different sensors, such as the first sensing line 236 of the first sensor 208 and the second sensing line 238 of the second sensor 210, but are not limited thereto. In one or more examples, the first sample-and-hold circuit 1006 and the second sample-and-hold circuit 1008 are configured to perform corresponding voltage sampling in response to a timing signal 1016. In one or more examples, the first sample-and-hold circuit 1006 and the second sample-and-hold circuit 1008 utilize the same timing signal 1016 (or two well-synchronized timing signals) so that the first sample-and-hold circuit and the second sample-and-hold circuit can be controlled to perform their respective voltage sampling substantially simultaneously.

[0105] Measurement circuit 1000 includes a multiplexer 1014 arranged to selectively provide one of the outputs of a first sample-and-hold circuit 1006 and a second sample-and-hold circuit 1008 to the input of ADC 1004. ADC 1004 is configured to digitize the corresponding voltage levels provided by multiplexer 1014 and store these values ​​in buffer 1002. The digitized values ​​stored in buffer 1002 can be retrieved and combined by a processor (e.g., processor 206, but not limited thereto) to obtain differential values ​​indicating coupling capacitance. Although ADC 1004 measures the voltages provided to multiplexer 1014 by the corresponding inputs at different times, the voltages exhibit voltage levels of substantially simultaneously sampled voltages and therefore include complementary coupling errors, as discussed herein.

[0106] Figure 11 It is a diagram including a first schematic view 1102 and a second schematic view 1104, which depict the use of self-capacitance indication (e.g., during several events) during which self-capacitance indication is used. Figure 1A The self-capacitance indicator 124, but not limited to this) and the differential value (e.g., Figure 1A The difference value is 106 or Figure 2The vertical height value is indicated by a difference of 220 (but not limited to this). By comparing the corresponding values ​​depicted in views 1102 and 1104 during the events (one finger, two fingers, palm touching the DUT wall; fingers touching water present at the DUT; and the grounding wire inserted into the water), it can be seen that the vertical height value indicated in view 1102 changes considerably in response to the events, including when the grounding wire is inserted into the water, which results in a large change compared to the value indicated without an event. In the second illustrated view 1104, the vertical height value indicated does not show substantial change for most events, and a modest change is observed when the grounding wire is inserted into the water compared to the first illustrated view 1102.

[0107] Therefore, the first schematic view 1102 depicts the self-capacitance indication values ​​affected by touching the DUT wall with one finger, two fingers, and the palm; touching water present at the DUT with a finger; and the grounding wire being inserted into the water, respectively. This results in coupling errors in the values. The presence of coupling errors leads to large fluctuations in the values. As can be seen in the second schematic view 1104, the differential value provides a reduction in the self-capacitance indication.

[0108] In this description, any characterization of something as "typical," "conventional," "known," etc., does not necessarily mean that the object is disclosed in the prior art or that the aspects discussed are known in the prior art. Nor does such characterization necessarily mean that it is well-known, fully understood, or routinely used in the relevant field. It only means that the inventors of this disclosure know or understand it.

[0109] As used in this disclosure, the term "combination" referring to multiple elements can include any combination of all elements or any combination of various different sub-combinations of certain elements. For example, the phrase "A, B, C, D or combinations thereof" can refer to any one of A, B, C, or D; a combination of each of A, B, C, and D; and any sub-combination of A, B, C, or D, such as A, B, and C; A, B, and D; A, C, and D; B, C, and D; A and B; A and C; A and D; B and C; B and D; or C and D.

[0110] The terms used in this disclosure, and especially in the appended claims (e.g., the body of the appended claims, etc.), are generally intended to be “open-ended” terms (e.g., the term “including” should be interpreted as “including but not limited to”, the term “having” should be interpreted as “at least having”, the term “includes” should be interpreted as “including but not limited to”, etc.). As used herein, the term “each” means some or all. As used herein, the term “every” means all.

[0111] Furthermore, if a specific number of introduced claim statements are anticipated, such an intent will be explicitly stated in the claims, and without such statements, no such intent exists. For example, as an aid to understanding, the appended claims may contain the use of the introductory phrases “at least one” and “one or more” to introduce claim statements. However, the use of such phrases should not be construed as implying that a claim statement introduced by the indefinite article “a” or “an” limits any particular claim containing such an introduced claim statement to an example containing only one such statement, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and / or “an” can be interpreted as referring to “at least one” or “one or more”, but is not limited thereto); the same applies to the use of definite articles to introduce claim statements. As used herein, the term “each” means some or all, and the terms “each and each” mean all.

[0112] Furthermore, even when a specific number of the introduced claims are explicitly stated, those skilled in the art will recognize that such statements should be interpreted as intended to represent at least the number stated (e.g., the unmodified statement "two statements" means, without other modifying elements, at least two statements, or two or more statements, but not limited thereto). Moreover, in instances where conventions such as "at least one of A, B, and C, but not limited thereto" or "one or more of A, B, and C, but not limited thereto" are used, such constructions are generally intended to include, but are not limited to, a single A, a single B, a single C, A and B together, A and C together, B and C together, or A, B, and C together.

[0113] Furthermore, any separate word or phrase presenting two or more alternative terms in the specification, claims, or drawings should be understood to include the possibility of including one term, any one term, or both terms. For example, the phrase "A or B" should be understood to include the possibility of including "A" or "B" or "A and B".

[0114] Various examples of non-limiting examples of this disclosure include:

[0115] Example 1: An apparatus comprising: a detector, wherein the detector is configured to sense a signal that is a differential value indicating a difference in self-capacitance at a first internal capacitor and a second internal capacitor, wherein the differential value is proportional to the vertical height of the surface of a material present at a device under test coupled to an electrode of the detector.

[0116] Example 2: The apparatus according to Example 1 includes: a first sensor configured to generate a first voltage indicating a first self-capacitance of a corresponding electrode; and a second sensor configured to generate a second voltage indicating a second self-capacitance of a corresponding electrode.

[0117] Example 3: The apparatus according to any one of Examples 1 and 2, wherein: the first sensor is configured to change the voltage level of the first voltage in at least a partial response to a change in the first self-capacitance; and the second sensor is configured to change the voltage level of the second voltage in at least a partial response to a change in the second self-capacitance.

[0118] Example 4: The apparatus according to any one of Examples 1 to 3, wherein the first sensor and the second sensor are configured to provide a substantially symmetrical response to capacitive coupling with a material present at the device under test.

[0119] Example 5: The apparatus according to any one of Examples 1 to 4, wherein the first sensor and the second sensor are configured to provide a substantially symmetrical response to changes in the coupling between the material present at the device under test and the first sensor and the second sensor.

[0120] Example 6: The apparatus according to any one of Examples 1 to 5, wherein the first sensor and the second sensor are configured to provide a substantially symmetrical response comprising: a response to a change in coupling between the material present at the device under test and the first sensor and the second sensor, at least in part, a response to a change in the dielectric properties of the material.

[0121] Example 7: The apparatus according to any one of Examples 1 to 6, wherein: the first sensor includes: a first acquisition circuit configured to generate the first voltage at the first internal capacitor; and a first measurement circuit configured to generate a first value indicating a voltage level represented by the first voltage; and the second sensor includes: a second acquisition circuit configured to generate the second voltage at the second internal capacitor; and a second measurement circuit configured to generate a second value indicating a voltage level represented by the second voltage.

[0122] Example 8: The apparatus according to any one of Examples 1 to 7, wherein: the first measuring circuit includes a first analog-to-digital converter arranged to measure the first voltage generated at the first internal capacitor; and the second measuring circuit includes a second analog-to-digital converter arranged to measure the second voltage generated at the second internal capacitor.

[0123] Example 9: An apparatus according to any one of Examples 1 to 8, the apparatus comprising: a sample-and-hold circuit; an analog-to-digital converter; and a processor configured to control the sample-and-hold circuit and the analog-to-digital converter to alternately measure the first voltage generated at the first internal capacitor and the second voltage generated at the second internal capacitor.

[0124] Example 10: An apparatus according to any one of Examples 1 to 9, the apparatus comprising: a first wire arranged around a corresponding electrode of the first sensor; a second wire arranged around a corresponding electrode of the second sensor; a first drive protection electrode electrically coupled to the first wire and configured to receive a first protection voltage; and a second drive protection electrode electrically coupled to the second wire and configured to receive a second protection voltage.

[0125] Example 11: A method comprising: obtaining a difference value of a self-capacitance indication of an indicator electrode, the self-capacitance indication being manifested at a first internal capacitor and a second internal capacitor; and inferring, at least in part, the vertical height of a surface of material present at a device under test coupled to the electrode in response to the difference value.

[0126] Example 12: According to the method of Example 11, the method includes: performing a first acquisition process to obtain a first self-capacitance indication of a first electrode in the electrode; and performing a second acquisition process to obtain a second self-capacitance indication of a second electrode in the electrode.

[0127] Example 13: The method according to any one of Examples 11 and 12, wherein performing the first acquisition process includes: charging a first internal capacitor to a reference voltage; discharging a first external capacitor associated with the first electrode in the electrode; coupling the first internal capacitor and the first external capacitor; and measuring the voltage exhibited by the first internal capacitor.

[0128] Example 14: The method according to any one of Examples 11 to 13, wherein performing the second acquisition process includes: discharging a second internal capacitor; charging a second external capacitor to a reference voltage, the second external capacitor being associated with the second electrode in the electrode; coupling the second internal capacitor and the second external capacitor; and measuring the voltage exhibited by the second internal capacitor.

[0129] Example 15: The method according to any one of Examples 11 to 14, wherein performing the first acquisition process and the second acquisition process includes: performing the first acquisition process using a first sensor and performing the second acquisition process using a second sensor; and performing the second acquisition process using the first sensor and performing the first acquisition process using the second sensor.

[0130] Example 16: The method according to any one of Examples 11 to 15, wherein the first acquisition process and the second acquisition process are executed substantially simultaneously.

[0131] Example 17: The method according to any one of Examples 11 to 16, wherein the first self-capacitance indicator and the second self-capacitance indicator are generated substantially simultaneously.

[0132] Example 18: An apparatus comprising: a detector, wherein the detector is configured to sense a signal that is a differential value, the differential value being an indication of a coupling capacitance exhibited by two corresponding electrodes, wherein the indication of the coupling capacitance is proportional to a relationship between a first material and a second material present at the device under test coupled to the two corresponding electrodes of the detector.

[0133] Example 19: An apparatus comprising: a detector, wherein the detector is configured to sense a signal that is a change in the self-capacitance of an electrode, the change in the self-capacitance of the electrode including only the change in self-capacitance due to a change in capacitive coupling between the electrode and the material of interest.

[0134] Example 20: An apparatus comprising: a detector, wherein the detector is configured to sense a signal that is a change in the self-capacitance of an electrode, the change in the self-capacitance of the electrode including only the change in self-capacitance due to a change in the dielectric properties of the material of interest.

[0135] Without departing from the scope of this disclosure, the features of the various examples described herein are not mutually exclusive and can exist in various combinations and arrangements, even if such combinations or arrangements are not explicitly described herein. In fact, variations, modifications, and other specific implementations of the content described herein will be recognized by those skilled in the art without departing from the scope of this disclosure. Therefore, the invention should not be limited solely to the foregoing exemplary description, but should be limited only to the appended claims and their legal equivalents.

Claims

1. A device for sensing material level, the device comprising: A detector, wherein the detector is configured to sense a signal that is a differential value indicating a difference in self-capacitance at a first internal capacitor and a second internal capacitor, wherein the differential value is proportional to the vertical height of the surface of the material present at the device under test at the electrodes coupled to the detector. The detector includes a first sensor and a second sensor configured to provide a substantially symmetrical response to a change in capacitive coupling with respect to the material present at the device under test, the change in capacitive coupling being at least partially responsive to the dielectric properties of the material.

2. The apparatus according to claim 1, wherein: The first sensor is configured to generate a first voltage indicating a first self-capacitance of the corresponding electrode; and The second sensor is configured to generate a second voltage that indicates the second self-capacitance of the corresponding electrode.

3. The apparatus according to claim 2, wherein: The first sensor is configured to change the voltage level of the first voltage in at least a partial response to a change in the first self-capacitance; and The second sensor is configured to change the voltage level of the second voltage in at least a portion of response to a change in the second self-capacitance.

4. The apparatus of claim 2, wherein the first sensor and the second sensor are configured to provide a substantially symmetrical response to changes in the coupling between the material present at the device under test and the first sensor and the second sensor.

5. The apparatus according to claim 2, wherein: The first sensor includes: A first acquisition circuit, configured to generate the first voltage at the first internal capacitor; and A first measuring circuit is configured to generate a first value, the first value indicating the voltage level represented by the first voltage, and The second sensor includes: A second acquisition circuit, configured to generate the second voltage at the second internal capacitor; and A second measurement circuit is configured to generate a second value, which indicates the voltage level represented by the second voltage.

6. The apparatus according to claim 5, wherein: The first measurement circuit includes a first analog-to-digital converter arranged to measure the first voltage generated at the first internal capacitor; and The second measurement circuit includes a second analog-to-digital converter arranged to measure the second voltage generated at the second internal capacitor.

7. The apparatus according to claim 2, wherein the apparatus comprises: Sample and hold circuit; Analog-to-digital converter; and A processor configured to control the sample-and-hold circuit and the analog-to-digital converter to alternately measure the first voltage generated at the first internal capacitor and the second voltage generated at the second internal capacitor.

8. The apparatus according to claim 2, wherein the apparatus comprises: A first wire is arranged around the corresponding electrode of the first sensor; A second wire is arranged around the corresponding electrode of the second sensor; and A first driving protection electrode is electrically coupled to the first wire and configured to receive a first protection voltage. and The second drive protection electrode is electrically coupled to the second wire and is configured to receive a second protection voltage.

9. A method for level sensing, the method comprising: The difference value of the self-capacitance indication of the indicator electrode is obtained, and the self-capacitance indication is expressed at the first internal capacitor and the second internal capacitor. as well as The vertical height of the surface of the material present at the device under test coupled to the electrode is inferred, at least in part, in response to the difference value. Obtaining the differential value includes performing a first acquisition process to obtain a first self-capacitance indication of a first electrode in the electrodes, and performing a second acquisition process to obtain a second self-capacitance indication of a second electrode in the electrodes, the first acquisition process and the second acquisition process being performed substantially simultaneously to provide a substantially symmetrical response to capacitive coupling with the material.

10. The method according to claim 9, wherein performing the first acquisition process comprises: Charge the first internal capacitor to the reference voltage; Discharge a first external capacitor, which is associated with the first electrode in the electrodes; Couple the first internal capacitor and the first external capacitor; as well as The voltage exhibited by the first internal capacitor is measured.

11. The method of claim 9, wherein performing the second acquisition process comprises: Discharge the second internal capacitor; A second external capacitor is charged to a reference voltage, the second external capacitor being associated with the second electrode in the electrodes; Couple the second internal capacitor and the second external capacitor; as well as The voltage exhibited by the second internal capacitor is measured.

12. The method according to claim 9, wherein performing the first acquisition process and the second acquisition process comprises: The first acquisition process is performed using a first sensor, and the second acquisition process is performed using a second sensor. as well as The second acquisition process is performed using the first sensor, and the first acquisition process is performed using the second sensor.

13. The method of claim 9, wherein the first self-capacitance indicator and the second self-capacitance indicator are generated substantially simultaneously.

14. An apparatus for sensing material level, the apparatus comprising: A detector, wherein the detector is configured to sense a differential value, the differential value being an indication of coupling capacitance exhibited by two corresponding electrodes, wherein the indication of coupling capacitance is proportional to a relationship between a first material and a second material present at the device under test coupled to the two corresponding electrodes of the detector. The difference value indicates the difference in self-capacitance indicated at the first internal capacitor and the second internal capacitor associated with the two corresponding electrodes.

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