Near field wireless device for distance measurement

Abstract

One example discloses a wireless device comprising: a first near-field device comprising a near-field transmitter or receiver and a controller, the first near-field device configured to be coupled to a near-field antenna having a first conductive surface and a set of feed points; wherein the controller is configured to receive a transmitter output voltage from the set of feed points; wherein the controller is configured to generate a correction signal based on a difference between the transmitter output voltage and a target transmitter output voltage; wherein the correction signal varies in response to a change in a distance between the first surface and a second conductive surface; and wherein the controller is configured to calculate the distance between the first conductive surface and the second conductive surface based on the correction signal.

Description

Technical Field

[0001] This specification relates to systems, methods, apparatus, devices, articles of manufacture, and instructions for use in near-field wireless devices. Background Technology

[0002] This article discusses near-field interactions, such as those between near-field devices on a user's body and other conductive surfaces and / or other wirelessly networked devices (e.g., Internet of Things (IoT) devices), based on near-field electromagnetic induction (NFEMI), where the transmitter and receiver are coupled via both magnetic (H) and electric (E) fields, or near-field electrostatic induction (NFEI), where the transmitter and receiver are coupled via only an electric (H) field. Although RF wireless communication is achieved by propagating RF plane waves through free space, NFEMI and NFEI communication utilize non-propagating quasi-static H and / or E fields.

[0003] H-field antennas (i.e., magnetic antennas) are primarily sensitive to magnetic fields and / or primarily activate the magnetic field when driven by an electric current. Any E-field component from an H-field antenna is greatly reduced (e.g., reduced by -20 dB to -60 dB, with a factor of 0.1 to 0.0008 (10% to 0.08%), depending on the antenna design).

[0004] The small loop antenna is an example H-field antenna and includes a loop antenna whose size is much smaller than the wavelength it uses. The small loop antenna does not resonate at the NFEMI carrier frequency, but instead is tuned to a resonant state via an external reactance. In some example embodiments, the current in the small loop antenna has the same value at all locations within the loop.

[0005] E-field antennas (i.e., electric antennas) are primarily sensitive to electric fields and / or primarily initiate electric fields when driven by voltage. Any H-field component from an E-field antenna is greatly reduced (e.g., reduced by -20 dB to -60 dB, with a factor of 0.1 to 0.0008 (10% to 0.08%), depending on the antenna design).

[0006] The short-loaded dipole antenna is an example E-field antenna and includes a short dipole much smaller than the NFEMI carrier frequency, and in some example embodiments has additional capacitive surfaces at both ends.

[0007] The quasi-static characteristics of these fields are a result of the combination of NFEMI antenna size and its carrier frequency. Most of the near-field energy is stored in the form of magnetic and electric fields, while a small amount of RF energy inevitably propagates in free space. Small antenna geometry minimizes the radiated waves in free space.

[0008] For example, some body-holding or wearable devices, such as game controllers, medical devices, hearing aids, and wireless earbuds, can also employ near-field magnetic induction (NFMI) as a wireless communication method. In NFMI wireless communication, two loosely coupled coils transmit signals. No radio wave radiation occurs. The current flowing in the transmitting coil generates an H-field, which then induces a current in the receiving coil. Wireless communication is thus achieved. A disadvantage is that H-field-based NFMI systems with small antenna coils have a limited range, which may be much smaller than the entire wearable area of ​​the user's body. This type of H-field communication is sensitive to coil orientation.

[0009] Other body-holding or wearable devices employ near-field induction (NFEI) as a wireless communication method. NFEI allows electronics on and near conductive surfaces (e.g., the human body) to exchange information via E-field coupling (e.g., at 21 MHz). NFEI is sometimes also referred to as body-coupled communication (BCC). While E-field-based NFEI signals can have a greater range than H-field-based NFMI signals, the E-field signal strength can vary relative to body posture and is sensitive to body movement. The body may even partially block the capacitive return path, thereby increasing E-field channel loss and making reliable and robust wireless communication impossible.

[0010] In various operating setups, the distance between such wireless and / or wearable near-field devices and various other conductive surfaces or other near-field devices in the environment can be useful. Summary of the Invention

[0011] According to an example embodiment, a wireless device includes: a first near-field device including a near-field transmitter or receiver and a controller, the first near-field device being configured to be coupled to a near-field antenna having a first conductive surface and a set of feed points; wherein the controller is configured to receive a transmitter output voltage from the set of feed points; wherein the controller is configured to generate a correction signal based on the difference between the transmitter output voltage and a target transmitter output voltage; wherein the correction signal varies in response to a change in the distance between the first surface and a second conductive surface; and wherein the controller is configured to calculate the distance between the first conductive surface and the second conductive surface based on the correction signal.

[0012] In another example embodiment, the correction signal increases when the distance between the first surface and the second surface decreases; and the correction signal decreases when the distance between the first surface and the second surface increases.

[0013] In another example embodiment, the controller is configured to adjust the transmitter output voltage based on the correction signal.

[0014] In another example embodiment, the first conductive surface is configured to be coupled to the user's body, and the second conductive surface is embedded in a device not on the user's body.

[0015] In another example embodiment, the second conductive surface is not coupled to any other near-field device.

[0016] In another example embodiment, the controller calculates the distance without transmitting or receiving data to or from any other near-field device coupled to the second conductive surface.

[0017] In another example embodiment, the near-field device hosts a non-propagating quasi-static electrical near-field signal; and the first conductive surface is configured to conduct the non-propagating quasi-static electrical near-field signal.

[0018] In another example embodiment, the near-field device is configured to transmit or receive a near-field inductive (NFEI) signal; and the near-field transmitter or receiver is configured to set the near-field resonant frequency or operating bandwidth of the NFEI signal.

[0019] In another example embodiment, the near-field transceiver is configured to transmit or receive a near-field electromagnetic induction (NFEMI) signal; and the near-field transmitter or receiver is configured to set the near-field resonant frequency or the operating bandwidth of the NFEMI signal.

[0020] In another example embodiment, the first conductive surface is embedded in a user's body, vehicle, game controller, or robot.

[0021] In another example embodiment, the first conductive surface is located on or near an assembly line.

[0022] In another example embodiment, the controller is configured to record a set of distances over a period of time; and the controller is configured to output an authentication signal when the set of distances corresponds to a stored set of distances.

[0023] In another example embodiment, the authentication signal performs at least one of the following: activating the electronic device, granting access to the secure space, indicating that the procedure has been correctly followed, and / or indicating that a quality assurance procedure has been performed.

[0024] In another example embodiment, the controller is configured to generate an acoustic signal having an amplitude and / or frequency modulated according to the distance.

[0025] In another example embodiment, the controller is configured to generate a tactile signal having amplitude, frequency, and / or pattern modulated according to the distance.

[0026] In another example embodiment, the tactile signal is generated in response to the tuning value exceeding a threshold value.

[0027] In another example embodiment, the tuning value includes an adjustable capacitor configured to set the near-field resonant frequency of the first near-field device.

[0028] In another example embodiment, the tuning value includes an adjustable resistor configured to set the transmitter or receiver bandwidth of the first near-field device.

[0029] The foregoing discussion is not intended to represent every example embodiment or every implementation within the scope of the present or future claims. The following figures and detailed descriptions further illustrate various example embodiments.

[0030] A more comprehensive understanding of the various exemplary embodiments can be obtained by considering the following detailed description taken in conjunction with the accompanying drawings. Attached Figure Description

[0031] Figure 1 This is an example of a near-field wireless device.

[0032] Figure 2 This is an example of a near-field antenna in a wireless device.

[0033] Figure 3A This is the first example of a first near-field device on a first surface where the distance from the second surface varies.

[0034] Figure 3B This is a second example of a first near-field device on a first surface where the distance from the second surface varies.

[0035] Figure 4 It is used for Figure 3A The first example is a sample set of transmitter output voltage correction signal values.

[0036] Figure 5A yes Figure 4 Example section of the set of transmitter output voltage correction signal values.

[0037] Figure 5B yes Figure 5A Example section of the set of transmitter output voltage correction signal values.

[0038] Figure 6 yes Figure 1 Example circuit diagram of a near-field wireless device.

[0039] While this disclosure allows for various modifications and alternatives, their particularities have been illustrated by way of example in the drawings and will be described in detail. However, it should be understood that other embodiments beyond the specific embodiments described are also possible. All modifications, equivalents, and alternative embodiments falling within the spirit and scope of the appended claims are also covered. Detailed Implementation

[0040] The present discussion focuses on an example near-field wireless device that measures the change in its internal tuning value when the device is sufficiently close to a conductive medium (e.g., a conductive surface). The following discussion describes near-field wireless devices that utilize near-field coupling mechanisms (electrical and magnetic) to various surfaces (some of which are conductive) to employ the device's internal tuning value.

[0041] The tuning values ​​for the near-field device include a correction signal based on the difference between the transmitter output voltage of the near-field device and the target transmitter output voltage. Although changes to the capacitor bank (C bank) used to stabilize the device's resonant frequency and the resistor bank (R bank) used to stabilize the device's operating bandwidth / quality factor can also be used to calculate the distance, using the correction signal to calculate the distance is much faster.

[0042] The correction signal based on the difference between the transmitter output voltage and the target transmitter output voltage using a near-field device is faster because it only requires one transmitter output voltage measurement at one frequency for the correction signal to adjust the transmitter output voltage back to its target transmitter output voltage value. In contrast, C-group / R-group tuning may require three measurements.

[0043] Changes in tuning values ​​are mapped to various movements (e.g., approaching or moving away) of the near-field wireless device relative to various conductive surfaces and / or relative to each other. Some of these near-field wireless devices may be worn by a user, requiring careful tracking of user movement as the user approaches and moves away from various objects in the environment (e.g., see below for applications of this technique). In some example embodiments, the transmitter output voltage correction signal increment has sufficient granularity and a sufficient update frequency (e.g., at least once every 10-20 ms) to track user movement.

[0044] In hazardous environments where the time between detecting a user's proximity and the user potentially actually coming into contact with a dangerous device may be too short for an R / C group tuner to provide a sufficient warning to the user, using transmitter output voltage measurements to accelerate distance change detection can have many benefits.

[0045] It should be noted that while the example embodiments discussed herein refer to a “user,” in alternative embodiments, the near-field device may be coupled to any conductive surface (e.g., a robot, vehicle, docking system, physical coupling system, location on an assembly line, etc.).

[0046] Figure 1 This is an example of a near-field wireless device 100. The example near-field wireless device 100 includes a near-field antenna 102, a tuning circuit 104, a tuning monitor circuit 106, a controller 108, a haptic device 110, and a transceiver circuit 112. Figure 2 An example of a near-field antenna 102 is presented and discussed. Transceiver circuitry 112 is configured to adjust the transmitter output voltage of device 100 using controller 108. Tuning circuitry 104 is configured to adjust the resonant frequency of device 100 using a group of capacitors (C group) and adjust the bandwidth using a group of resistors (R group) in response to a signal from controller 108. In some examples, the C group and R group are discretely approximately 130 pF and 5000 ohms, respectively, to support the desired resonant frequency (e.g., 10.3 MHz) and bandwidth (e.g., 400 kHz).

[0047] The tuning monitor circuit 106 is configured to monitor the transmitter output voltage, as well as the C group and R group values, which are subsequently transmitted to the controller 108.

[0048] The controller 108 is configured to adjust (e.g., increment / decrement) the transmitter output voltage using transceiver circuitry 112 and to adjust the C-group and R-group values ​​using tuning circuitry 104. The controller 108 is also configured to receive the transmitter output voltage from tuning monitor circuitry 106 and to calculate the distance of the near-field wireless device 100 or a user coupled to the wireless device 100 from the conductive surface.

[0049] In some example embodiments, the distance calculated by controller 108 can be used to drive haptic device 110. In some examples, haptic device 110 is coupled to a user (e.g., physical coupling, audio coupling, electrical coupling, etc.) to provide some type of haptic feedback (e.g., a haptic signal having its amplitude, frequency, and / or pattern) as the user approaches, leaves, or touches various conductive surfaces.

[0050] The five main types of haptic feedback technology (tactile feedback) are force, vibratory haptics, electrohaptics, ultrasound, and thermal feedback. The most well-known example of haptic technology is the device in a mobile phone that generates vibrations, which are classified as vibratory haptic feedback. Vibratory haptic stimulators apply pressure to receptors on human skin. This type of haptic feedback allows users to feel clicks, vibrations, and other tactile inputs that provide a variety of tactile sensations.

[0051] In some example embodiments, haptic feedback can be provided when a user places the near-field device 100 (e.g., wearable) in a "not supported" condition where the performance of the near-field device 100 is degraded (e.g., a near-field device not worn correctly and / or signal loss with other near-field devices). For example, with the NFEMI wearable wristband, an unsupported condition could be when the user is not wearing the wristband containing the near-field device correctly. Another unsupported condition could be when the wristband is placed behind the user.

[0052] In other example embodiments, tactile feedback can be provided to warn a user of being in a hazardous / industrial environment when the user approaches or gets too close to certain dangerous / industrial structures. Therefore, the level of tactile feedback may vary depending on the user's proximity to the conductive interface (e.g., a slight vibration occurs when the user is far from the surface, while a more intense vibration occurs when the user is very close).

[0053] Figure 2 This is a first example of a near-field antenna 200 in wireless device 100. In this example, antenna 200 is a near-field electromagnetic induction (NFEMI) antenna. In some example embodiments, antenna 200 includes a coil (H-field) antenna 205 for a magnetic field and a short-loaded dipole (E-field) antenna 220 for an electric field. H-field antenna 205 includes a ferrite core 210 wound with wire 215. E-field antenna 220 includes two conductive loaded surfaces 225 and 230. Antenna 200 feed points 235, 240 are coupled to various transceiver circuitry systems, such as downstream radio transmitter and receiver integrated circuits (RF-ICs) (not shown here). Antenna 200 can be tuned to resonate at the communication frequency by means of a reactive component integrated in the RF-IC. The bandwidth of antenna 200 can be tuned in a similar manner using the reactive component.

[0054] When the NFEMI antenna 200 approaches a conductive structure (e.g., a structure with one or more conductive surfaces, a body, a person, an object, etc.), the magnetic and electric fields will be substantially confined to the conductive surface and will not radiate significantly in free space. This enhances the security and confidentiality of such body-based network communications.

[0055] In various example embodiments, antenna 200 operates at 50 MHz or below (e.g., 30 MHz) to ensure that the field follows the contour of the conductive surface and to ensure that far-field radiation is greatly reduced.

[0056] Figure 3A This is a first example 300 of a first near-field device 302, which includes a first conductive surface 304 with a varying distance 318 from the second conductive surface 316. The first conductive surface 304 may be part of an NFEMI antenna 200. In example 300, movement is shown as approaching (phase 1) 310 outside the plane of the second conductive surface 316, and departing (phase 2) 314 also outside the plane of the second conductive surface 316. At any given time, the distance 318 between the first conductive surface 304 and the second conductive surface 316 (e.g., a user's finger) is shown.

[0057] In this example 300, the user's left finger (i.e., the second surface 316) approaches the first conductive surface 304 and then moves away from it. This movement sequence is repeated 6 times. Figure 4 An example is shown below. When the user's finger approaches and moves away from the first conductive surface 304, the controller 108 adjusts the transmitter output voltage correction signal and calculates the instantaneous distance 318 from the transmitter output voltage correction signal.

[0058] In some example embodiments, the conductive surfaces 225, 230 of the near-field antenna 200 (see...) Figure 2 One of the conductive surfaces 225 and 230 is positioned to face the user's finger, while the other is oriented towards the environment, thereby creating capacitance between the plate and the environment. This capacitance is altered by the proximity of the conductive surfaces 225 and 230 to various conductive surfaces, structures, and / or objects in the environment (e.g., the second surface 316).

[0059] In some example embodiments, the near-field antenna 200 is positioned to face a user's finger, which is a portion of the second conductive surface 316. Various conductive surfaces, structures, and / or objects (e.g., the second surface 316) in the environment near the near-field antenna 200 may introduce additional losses in the antenna and cause a decrease in the quality factor of the antenna 200.

[0060] In some example embodiments, in order to compensate for these distance 318 variations, the controller 108 adjusts the transmitter amplification of the transceiver circuit 112 based on the transmitter output voltage correction signal, so that the transmitter output voltage is maintained at the target transmitter output voltage.

[0061] For example, when the distance 318 between the first surface 304 and the second surface 316 decreases during the approach (phase 1) 310, the transmitter output voltage correction signal increases, and when the distance 318 between the first surface 304 and the second surface 316 increases during the departure (phase 2) 314, the transmitter output voltage correction signal decreases. See [link to relevant documentation]. Figure 4 .

[0062] In other words, when the distance 318 between the first surface 304 and the second surface 316 begins to decrease, the controller 108 first increases the transmitter output voltage correction signal value to maintain the target transmitter output voltage. Then, when the distance 318 between the first surface 304 and the second surface 316 no longer decreases and remains constant / fixed, the transmitter output voltage correction signal value gradually decreases to maintain the target transmitter output voltage according to a specific setting corresponding to the resistor tuning value. When the distance 318 between the first surface 304 and the second surface 316 begins to increase, the controller 108 further decreases the transmitter output voltage correction signal value to maintain the target transmitter output voltage.

[0063] In an example embodiment of the first near-field device 302 including a controller, the controller may be configured to record a set of distances over a period of time and output an authentication signal when the set of distances corresponds to a stored set of distances. In various example embodiments, the authentication signal may: activate an electronic device, grant access to a secure space, indicate that procedures have been correctly followed, indicate that quality assurance procedures have been performed, etc.

[0064] The controller can also be configured to output a boundary crossing signal (e.g., alarm, tactile, etc.) when the distance 318 is less than a predetermined distance 318. The boundary crossing signal can enable the generation of an acoustic signal and / or a tactile signal having an amplitude and / or frequency modulated according to the distance 318. The controller can also be configured to generate a visual cue modulated according to the distance 318.

[0065] Figure 3B This is a second example 320 of a first near-field device 302 on a first surface 322 at a varying distance 318 from the second surface 324 (e.g., a finger configuration specific to a particular user). In this example 320, operation is generally similar to... Figure 3A The difference in the operation described in the article is that the first surface 322 with the first near-field device 302 approaches (stage 1) 310 and moves away from (stage 2) 314 and the second surface 324.

[0066] Figure 4 It is used for Figure 3A The first example 300 is an example set 400 of the transmitter output voltage correction signal value 402. In this example 400, approach (phase 1) 310 and departure (phase 2) 314 are shown. The x-axis is time 410 in seconds, and the primary y-axis 404 is the setting of the transmitter output voltage correction signal value 402 of the near-field device 100. The secondary y-axis 408 is... Figure 6 The setting of the R group value 406 (i.e., resistor) in the tuning circuit 104.

[0067] The data recorded at 15 seconds included six similar approaches (phase 1) 310 and subsequent departures (phase 2) 314, each lasting approximately 2.5 seconds.

[0068] When approaching the second conductive surface 316 (stage 1), the transmitter output voltage correction signal value 402 increases from setting 83 to setting 98 within approximately 20 ms (i.e., 15 tuning steps) until the first conductive surface 304 makes electrical contact with the second conductive surface 316, which is defined as the start of the contact period 412.

[0069] When the transmitter leaves the second conductive surface 316 during the period of leaving the contact period 414 (stage 2) 314, the transmitter output voltage correction signal value 402 decreases from setting 86 to setting 69 within 50ms.

[0070] In example 400, the transmitter output voltage correction signal value 402 rises sharply at the beginning of the contact period 412 and then falls slowly during the contact period 412. Then, the transmitter output voltage correction signal value 402 falls sharply at the beginning of the exit contact period 414 and then rises slowly during the exit contact period 414.

[0071] Contact is defined herein as including actual electrical contact, but also including examples where the first conductive surface 304 is close to the second conductive surface 316 but not in actual contact, for example, separated by a thin dielectric.

[0072] The faster response time of the transmitter output voltage correction signal value 402 relative to the R group value 406 will now be discussed. For example 400, at the start of contact phase 412, the transmitter output voltage correction signal value 402 increases to setting 98 over approximately 20 ms with 15 tuning steps during the approach phase 310. In contrast, from the start of contact phase 412, the R group value 406 decreases over 8 steps with 560 ms.

[0073] If a 10% change in the tuning parameters is critical for determining contact, a 10% change in the transmitter output voltage correction signal value 402 will be observed in less than 10 ms. A 10% change in the R group value 406 will be observed after more than 100 ms. Therefore, compared to other tuning parameters such as a variable (tunable) resistor, the transmitter voltage tuning is 100 times faster at detecting contact in this embodiment of the tuning algorithm and in this example 400.

[0074] For example 400, after contact period 412 and during departure contact period 414, the transmitter output voltage correction signal value 402 decreases over approximately 80 ms with 21 tuning steps, while the R group value 406 decreases over 700 ms with 8 steps during departure contact period 414.

[0075] If redefining a 10% change in the tuning parameters is critical for determining departure, a 10% change in the transmitter output voltage correction signal value 402 will be observed within approximately 30 ms. A 10% change in the R-group value 406 is insufficient because the R-group value 406 is low when the near-field device 100 is in contact (e.g., 5), so to make it more significant, an increment of the R-group value 406 over two steps is chosen here. This increment will be observed after more than 100 ms. Therefore, the transmitter output voltage correction signal value 402 detects departure much faster than the R-group value 406 in this embodiment of the tuning algorithm and in this example 400.

[0076] Figure 5A yes Figure 4 Example section 500 shows the settings of a set of transmitter output voltage correction signal values ​​402 and R group values ​​406.

[0077] Figure 5B yes Figure 5A Example section 502 shows the settings of a set of transmitter output voltage correction signal values ​​402 and R group values ​​406.

[0078] Figure 6 yes Figure 1 Example circuit diagram 600 of a near-field wireless device. Example circuit 600 includes a coil (H-field) antenna 205, a short-loaded dipole (E-field) antenna 220, a tuning circuit 104 having R groups and C groups, a tuning monitor circuit 106 configured to monitor the transmitter output voltage (VTx), a controller 108, and a transceiver circuit 112 configured to receive a transmitter output voltage correction signal from the controller 108.

[0079] L1 represents the induction of the coil (H-field) antenna 205 and R represents its loss, while Ca represents the capacitance of the short-loaded dipole (E-field) antenna 220 and Ra represents its loss. The two antennas, together with variable capacitors C1 and C2, are resonantly tuned at a communication frequency of, for example, 10.6 MHz. Variable-loaded resistors R1 and R2 are tuned for a desired communication bandwidth of, for example, 400 kHz.

[0080] During the last 20ms of the approach phase 310 to the beginning of the contact period 412, when additional losses are introduced into the system, the system's quality factor degrades, and the tuning resistor settings (R1 and R2) must be adapted to restore the correct bandwidth. The tuning resistor settings must be reduced and then used to correct the bandwidth, but this requires running an iterative tuning algorithm. This algorithm uses a dedicated tuning signal consisting of three frequency modulations, which are applied sequentially to the system and measured by the system. This algorithm transmits control signals for R1 and R2 (…). Figure 6 (The dashed arrow in the middle).

[0081] Because the resistor settings are not adjusted instantaneously, the transmitted voltage VTx will be too low when the overall equivalent parallel resistance of the system (the combination of R1, R2, R, and Ra) is too low. The transmitter voltage settings need to be adjusted to ensure the target transmitter output voltage is maintained.

[0082] The transmitter voltage setting is obtained by measuring VTx, which is the amplitude of the communication signal (e.g., 10.6 MHz in a 400 kHz bandwidth). Because this value is too low, the controller 108 adjusts the setting so that VTx is again at the target output voltage level. This tuning loop only requires one measurement of the existing communication signal.

[0083] Next, the resistor setting is repeatedly adjusted during the contact period 412 to stabilize it at a lower resistance tuning setting, which also allows the transmitter output voltage correction signal 402 to be adjusted and stabilized back to a lower correction setting during the contact period 412.

[0084] pass Figure 4 The measurements illustrate this explanation, showing that the adjustment of the R group value 406 occurs significantly slower than the change in the transmitter output voltage correction signal value 402. Therefore, when the NFEMI device is sufficiently close to the conductive medium, the transmitter output voltage correction signal value 402 is a better parameter for the monitor to detect—in milliseconds.

[0085] Unless a specific order is explicitly stated, the various instructions and / or operational steps discussed in the foregoing figures may be performed in any order. Furthermore, those skilled in the art will recognize that while some example sets of instructions / steps have been discussed, the material in this specification can be combined in various ways to produce other examples, and should be understood within the context provided by this specific embodiment.

[0086] In some example embodiments, these instructions / steps are implemented as functional and software instructions. In other embodiments, the instructions may be implemented using logic gates, application-specific chips, firmware, and other hardware forms.

[0087] When instructions are implemented as a set of executable instructions in a non-transitory computer-readable or computer-usable medium, these instructions are implemented on a computer or machine on which the executable instructions are programmed and controlled. The instructions are loaded to execute on a processor (e.g., one or more CPUs). The processor includes a microprocessor, microcontroller, processor module or subsystem (including one or more microprocessors or microcontrollers), or other control or computing device. A processor may refer to a single component or multiple components. The computer-readable or computer-usable storage medium is considered part of an article (or article of manufacture). An article or article of manufacture may refer to any single component or multiple components manufactured. Non-transitory machine or computer-usable medium as defined herein does not include signals, but such medium is capable of receiving and processing information from signals and / or other transient media.

[0088] It will be readily understood that the components of the embodiments generally described herein and illustrated in the accompanying drawings can be arranged and designed in a wide variety of different configurations. Therefore, the specific implementations of the various embodiments illustrated in the figures are not intended to limit the scope of this disclosure, but merely to illustrate various embodiments. Although various aspects of the embodiments are presented in the drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0089] The invention may be implemented in other specific forms without departing from the spirit or essential characteristics thereof. The described embodiments are to be regarded in all respects as illustrative rather than restrictive. Therefore, the scope of the invention is indicated by the appended claims rather than by the specific embodiments described therein. All changes that appear within the equivalent meaning and scope of the claims are covered by the scope of the claims.

[0090] References to features, advantages, or similar language throughout this specification do not imply that all features and advantages achievable through the invention should be included in or in any single embodiment of the invention. In fact, language relating to features and advantages should be understood to mean that a particular feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the invention. Therefore, all references to features and advantages, as well as similar language throughout this specification, may (but not necessarily) refer to the same embodiment.

[0091] Furthermore, the features, advantages, and characteristics described in this invention can be combined in one or more embodiments in any suitable manner. Those skilled in the art will recognize that, in view of the description herein, this invention can be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages that may not be present in all embodiments of the invention can be identified in certain embodiments.

[0092] Throughout this specification, references to "an embodiment," "embodiment," or similar language mean that a particular feature, structure, or characteristic described in connection with the indicated embodiment is included in at least one embodiment of the invention. Therefore, the phrases "in one embodiment," "in an embodiment," and similar language throughout this specification may (but not necessarily) refer to the same embodiment.

Claims

1. A wireless device, characterized in that, include: A first near-field device includes a near-field transmitter or receiver and a controller, the first near-field device being configured to be coupled to a near-field antenna having a first conductive surface and a set of feed points; The controller is configured to receive the transmitter output voltage from the set of feed points; The controller is configured to generate a correction signal based on the difference between the transmitter output voltage and the target transmitter output voltage; The correction signal changes in response to a change in the distance between the first conductive surface and the second conductive surface; and The controller is configured to calculate the distance between the first conductive surface and the second conductive surface based on the correction signal; The second conductive surface is not coupled to any other near-field device; The controller calculates the distance without transmitting or receiving data to or from any other near-field device coupled to the second conductive surface.

2. The apparatus according to claim 1: Its features are, When the distance between the first conductive surface and the second conductive surface decreases, the correction signal increases; and The correction signal decreases when the distance between the first conductive surface and the second conductive surface increases.

3. The apparatus according to claim 1: Its features are, The controller is configured to adjust the transmitter output voltage based on the correction signal.

4. The apparatus according to claim 1: Its features are, The first conductive surface is configured to be coupled to the user's body, and the second conductive surface is embedded in a device that is not on the user's body.

5. The apparatus according to claim 1: Its features are, The near-field device hosts a non-propagating quasi-static electrical near-field signal; and The first conductive surface is configured to conduct the non-propagating quasi-static electrical near-field signal.

6. The apparatus according to claim 1: Its features are, The near-field device is configured to transmit or receive near-field inductive (NFEI) signals; and The near-field transmitter or receiver is configured to set the near-field resonant frequency or operating bandwidth of the NFEI signal.

7. The apparatus according to claim 1: Its features are, The near-field device is configured to transmit or receive near-field electromagnetic induction (NFEMI) signals; and The near-field transmitter or receiver is configured to set the near-field resonant frequency or operating bandwidth of the NFEMI signal.

8. The apparatus according to claim 1: Its features are, The controller is configured to record a set of distances over a period of time; and The controller is configured to output an authentication signal when the set of distances corresponds to a stored set of distances.

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