WIRELESS WEARABLE DEVICE

TECHNICAL FIELD

This application pertains to the technical field of wireless communication, and in particular, to a wireless wearable device.

BACKGROUND

Recent decades have witnessed prosperity of wireless communication technology. An increasing requirement on convenient “anytime and anywhere” accesses to the Internet and WLANs leads to a rapid development of electronic devices that are wireless and portable, such as mobile phones, tablets and handheld game consoles. Miniaturization of wireless devices is a trend in both research and business, which aims at merging the wireless communication into each application scenario in people's daily life. A prospect is that the wireless devices are light, so as to provide high-quality wireless accesses without putting a significant burden on users. Such objective demands wireless devices that are increasingly compact, and thereby raises great challenges on downscaling integrated circuits, batteries, and antennas. In addition, other objects, desirable features and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background.

SUMMARY

In one embodiment, a wireless wearable device is provided, including a housing, a printed circuit board, PCB, and an antenna module connected to the PCB. The PCB is located inside the housing. The antenna module is configured to transmit and receive a wireless signal. The antenna module includes a first electrode; and a part of a body of a user and the first electrode together serve as an antenna for the wireless signal.

In one embodiment, at least a portion of the first electrode is located at a surface of the housing, and the portion of the first electrode keeps in contact with a skin of the part of the body when the part of the body and the first electrode together serving as an antenna for the wireless signal.

In one embodiment, the first electrode is not in contact with the part of the body when the part of the body and the first electrode together serving as an antenna for the wireless signal.

In one embodiment, at least a portion of the first electrode is attached to an inner side of the housing.

In one embodiment, the portion of the first electrode is separated from an inner side of a part of the housing by a first distance.

In one embodiment, a dielectric material is located between the portion of the first electrode and the inner side of the part of the housing.

In one embodiment, the housing is made of an insulating material.

In one embodiment, the insulating material is an elastic material.

In one embodiment, the part of the housing is made of a conductive material, and the PCB is configured to detect a change in capacitance between the part of the housing and the first electrode to determine an operation performed by a user on the housing.

In one embodiment, the antenna module is configured to transmit and receive the wireless signal under a same communication protocol when the wireless device communicates wirelessly with another device.

In one embodiment, a total length of the first electrode is less than a quarter of a wavelength corresponding to the communication protocol.

In one embodiment, the total length of the first electrode is equal to an eighth of the wavelength corresponding to the communication protocol.

In one embodiment, the communication protocol comprises one or more of Bluetooth®, wireless fidelity, GPS, or Cellular.

In one embodiment, the communication protocol includes one of the Bluetooth® or the wireless fidelity, a total length of the first electrode ranges from 5 mm to 25 mm.

In one embodiment, the antenna module is further configured to transmit and receive another wireless signal, and the part of the body and the first electrode together serve as an antenna for the other wireless signal. A frequency of the wireless signal is different from a frequency of the other wireless signal. A distance between the part of the body and the first electrode when the antenna module transmitting and receiving the wireless signal is different from the distance between the part of the body and the first electrode when the antenna module transmitting and receiving the other wireless signal.

In one embodiment, the antenna module is further configured to transmit and receive another wireless signal, and another part of the body and the first electrode together serve as an antenna for the other wireless signal. A frequency of the wireless signal is different from a frequency of the other wireless signal.

In one embodiment, the first electrode includes a feeding part and a flat part. The flat part is connected to an RF circuit of the PCB via the feeding part.

In one embodiment, the flat part is a stripe of an L-shape.

In one embodiment, a width of the stripe is 3 mm, and a length of a long edge of the L-shape is 15 mm.

In one embodiment, the feeding part is connected to the RF circuit through soldering, flexible print circuits, conductive printing, metal-plate connection, or wiring.

In one embodiment, the wireless wearable device is a wireless earbud.

In one embodiment, the housing of the wireless earbud comprises a side shell pluggable into the ear of the user. At least a portion of the first electrode is: located at a surface of the side shell, attached to an inner side of the side shell, or separated from an inner side of the side shell by the first distance.

In one embodiment, the part of the body comprises at least one of: a tragus, an antitragus, an antihelix, or crus of helix of an ear of the user.

In one embodiment, the wireless wearable device is one of a virtual reality apparatus, an augmented reality apparatus, electronic clothing, a necklace, a wristband, a ring, glasses, a wearable gaming console, or a gaming controller, which is capable to perform wireless communication.

The wireless wearable device is provided according to an embodiment of the present disclosure, including the housing, the PCB located inside the housing, and the antenna module connected to the PCB. The antenna module is configured to transmit and receive the wireless signal, and includes the first electrode. A part of a body of a user and the first electrode together serve as an antenna for the wireless signal. Hence, a total length of the first electrode can be reduced to a level smaller than a quarter of a wavelength applied in wireless communication, leading to a smaller size of the whole device. The wireless wearable device does not need an intentional touch or grip performed by the user due to a constant contact in wearing. Thereby, a state of the antenna is stable, improving quality of the transmitted and received signals.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and:

FIG. 1a to 1c are schematic structural diagrams of a wireless wearable device according to an embodiment of the present disclosure;

FIG. 2 is structural diagrams of an earbud according to an embodiment of the present disclosure;

FIG. 3 is a diagram of a three-dimensional model of an earbud when worn by a user according to an embodiment of the present disclosure;

FIG. 4 is another diagram of a three-dimensional model of an earbud when worn by a user according to an embodiment of the present disclosure;

FIGS. 5a and 5b are Smith chart and a graph of a return loss of an antenna of an earbud according to an embodiment of the present disclosure;

FIG. 6 is a graph of an antenna efficiency of an antenna of an earbud according to an embodiment of the present disclosure;

FIGS. 7a and 7b are graphs of radiation patterns of an antenna of an earbud according to an embodiment of the present disclosure;

FIG. 8 is a schematic structure of a flat part of a first electrode according to an embodiment of the present disclosure;

FIGS. 9a and 9b are Smith chart and a graph of a return loss of an antenna of an earbud according to another embodiment of the present disclosure;

FIG. 10 is a graph of an antenna efficiency of an antenna of an earbud according to another embodiment of the present disclosure;

FIG. 11 is a schematic diagram of a performance test on an earbud according to an embodiment of the present disclosure;

FIG. 12 are photos of an earbud worn by users in a performance test according to an embodiment of the present disclosure; and

FIG. 13 are photos of application scenarios in which a gaming controller serves as a wireless wearable device according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background of the invention or the following detailed description.

To make the object, technical solutions and advantages of the present application clearer, hereinafter technical solutions in some embodiments of the present disclosure are described in conjunction with the drawings in some embodiments of the present disclosure. Apparently, the described embodiments are only some rather than all of the embodiments of the present disclosure. Any other embodiments obtained based on the embodiments of the present disclosure by those skilled in the art without any creative effort fall within the scope of protection of the present disclosure.

A size of an antenna is generally limited by a frequency band applied in a corresponding protocol of the wireless communication. More specifically, a length of a conventional antenna should be at least a quarter of a corresponding wavelength in order to achieve a good quality of transmitted or received signals. Even if popular wireless devices have already applied super-high-frequency (SHF) band in communication, e.g. Bluetooth® and Wi-fi, such limitation still greatly hinders miniaturization of conventional wireless wearable devices. In traditional very-high-frequency (VHF) band of radio waves, proposed was a concept that applying the human body as the antenna or as a part of the antenna, so as to reduce a size of a handheld radio receiver. Nevertheless, frequencies of the VHF band (˜100 MHz) is quite lower than those of a common SHF band (˜GHz), therefore a size of the antenna is much larger than that of the popular wireless devices by several orders of magnitude, and another problem lies in that the wireless signals of high frequencies is degraded more greatly by the human body. Moreover, the radio receiver requires an intentional grip in handholding. Since a gripping position may change due to various postures of a user or various habits of different users, the quality of transmitted or received signals is not stable.

Reference is made to FIGS. 1a to 1c, which are a schematic structural diagram of a wireless wearable device according to an embodiment of the present disclosure. As shown in FIG. 1, a wireless wearable device includes a housing, a printed circuit board (PCB), and an antenna module. The PCB is located inside the housing. The antenna module is connected to the PCB, and is configured to transmit and receive a wireless signal. The antenna module includes a first electrode. A part of a body of a user and the first electrode together serve as an antenna for the wireless signal.

In one embodiment, at least a portion of the first electrode is located at a surface of the housing, and such portion keeps in contact with a skin of the part of the body when the part of the body of the user and the first electrode together serving as an antenna for the wireless signal, as shown in FIG. 1a. It is noted that besides the first electrode, another part of the housing may further be in contact with the part of the body at such time.

In another embodiment, the first electrode is not in contact with the part of the body when the part of the body of the user and the first electrode together serving as an antenna for the wireless signal. In such case, the first electrode may be still located a surface of the housing, but at a portion not touching the part of the body. Alternatively, the first electrode may be located within the housing. For example, the first electrode may be attached to an inner side of the housing, as shown in FIG. 1b. For another example, the first electrode may be separated from the inner side of a part of the housing by a first distance, as shown in FIG. 1c. Although the housing touches the skin in FIGS. 1b and 1c, it is appreciated that the housing may be separated from the skin by a gap in some embodiments.

In the above embodiments, the housing of the wireless wearable device may implement various functions. A main function is to provide protection over circuits, inner sensors or other elements that may be located inside. Another function may be providing an interface for the user to control the wireless wearable device. For example, a button or a touch sensor may be provided on the housing to implement starting, shutdown, standby, or other modes of the wireless wearable device, when the user touches or presses a corresponding region on the housing. It is appreciated that such function may be implemented alternatively via a mechanical switch, or even not provided in a case that the wearable device is controlled wirelessly or by an inner sensor (such as a capacitive sensor, a strain sensor, a gravity sensor, or a temperature sensor).

The PCB inside the housing is configured to receive, process, and transmit signals via a peripheral element connected to the PCB. The peripheral element may be configured to collect information inside or outside the wireless wearable device, or generate information under control of the PCB. For example, the peripheral element may include the antenna module, a sensor, a speaker, a motor, a microphone, a light emitting diode, a display, a battery, or the like. It is appreciated that a processor may be attached on the PCB to implement the relevant function.

The antenna module is configured to transmit and receive the wireless signal, so as to achieve wireless communication with one or more external devices. The external devices include, but are not limited to, a mobile phone, a laptop, a desktop, a tablet, a router, or a base station. An external device depends on an application environment in practice. It is appreciated that the wireless communication is based on a communication protocol, such as Bluetooth®, wireless fidelity (Wi-fi), global positioning system (GPS), or Cellular.

The first electrode of the antenna module would form an antenna for the wireless signal in conjunction with the human body. In some embodiments of the present disclosure, the human body does not constitute the whole antenna, to avoid high impedance on high-frequency signals. Instead, the human body acts as a part of the antenna to compensate the first electrode with a reduced length. Thereby, a length of the first electrode located in the wireless wearable device can be significantly reduced, a size of the whole device is smaller, and wearing experience is improved.

In some embodiments, the first electrode, or the housing close to the first electrode, may always keep in contact with the skin of the user during usage, namely, during the wireless wearable device being worn by the user. Accordingly, unless intentional operation of taking off the device, it is quite improbable that the quality of signal changes due to detachment of the device from the human body. Since a stable condition of the antenna is ensured, the quality of the wireless signals transmitted or received by the antenna module is guaranteed.

It should be noted that the human body may serve as a part of the antenna for one of the communication protocols, i.e. a first protocol, supported by the wireless wearable device. For the first protocol, the antenna module transmits and receives the wireless signal via both the first electrode and the human body. For another protocol, i.e. a second protocol, supported by the wireless wearable device, the first electrode itself may constitute the antenna, and the antenna module may transmit and receive the wireless signal via the first electrode only. When communicating under the second protocol, the first electrode may not be disposed close the human body, and therefore may operate alone as the antenna for the wireless signal. It is appreciated that a wavelength for the first protocol is usually greater than that for the second protocol, because a length of the antenna is shorter for the second protocol. For example, the wireless wearable device according to an embodiment of the present disclosure may apply Wi-fi of both 2.4 GHz and 5 GHz when the first electrode and the part of the body serving as the antenna, i.e. when worn by the user, and may merely apply Wi-fi of 5 GHz when the first electrode alone serving as the antenna, i.e. when it is detached from the skin of the user. The switching between the first protocol and the second protocol may be controlled by a circuit on the PCB.

Additionally or alternatively, the human body may serve as a part of the antenna for both a first protocol and a second protocol. Similar to the above case, the first protocol and the second protocol apply wireless signals of different frequencies. A distance between the part of the body may be equal to a first value when the antenna module transmitting or receiving the first protocol, and may be equal to a second value when the antenna module transmitting or receiving the first protocol. In one embodiment, the first value may be smaller than the second value, and correspondingly the wireless signal under the first protocol has a longer wavelength than the wireless signal under the second protocol. In such case, wireless communication may be switched from the first protocol to the second protocol when the antenna module moves away from the part of the body by a certain distance. That is, the wireless wearable device may still be capable to communicate through the first electrode and the human body even when a position of the wireless wearable device changes.

Additionally or alternatively, different parts of the human body may serves as the antenna for wireless signals of different frequencies together with the first electrode. For example, the wireless wearable device when worn by the user is in such a position that a distance between the first electrode and a first part of the body is equal to a first value, and a distance between the first electrode and a second part of the body is equal to a second value. Thereby, the first electrode and the first part of the body may serve as an antenna for a wireless signal of a first frequency, while the first electrode and the second part of the body may serve as an antenna for a wireless signal of a second frequency. In such case, the wearable wireless device is capable to achieve communication under two different frequencies (or two protocols) even when staying at a same position. It is noted that the antenna module may transmit or receive the wireless signals of the first frequency and the second frequency at the same time or at different times, which is not limited herein.

It should be noted that unless otherwise defined, hereinafter the term “antenna” refers to a combination of the first electrode and the human body, and the term “antenna module” refers to a peripheral element of the wireless wearable device that is connected to the PCB and includes the first electrode.

The wireless wearable device herein may be implemented as various daily gadgets or accessories. Generally, the wireless wearable devices refer to those wireless electronic devices that are close to and/or on the surface of the skin during usage (or when “worn” by a user). For example, the wireless wearable device may be an earbud, a necklace, a ring, a wristband, glasses, a wearable gaming console, or a gaming controller (such as a gamepad or a joystick communicated wirelessly with a gaming console). It is noted that the wireless device herein is not limited to the aforementioned forms, as long as the associated gadget or accessory is capable to keep in contact with a skin of a user during usage. Namely, the part of the body skin may keep in contact with a portion at a surface of the housing during usage, or at least stay close to a surface of the housing during usage, and thereby the first electrode at the surface or disposed at an inner side of the surface is capable to serve as an antenna together with the human body. For example, a skin of an ear always keeps in contact with the housing around an earplug, in a case that the wireless wearable device is embodied as an earbud. Similarly, a skin of the neck always keeps in contact with the housing at a lower surface, in a case that the wireless wearable device is embodied as a necklace. A skin of a wrist always keeps in contact with the housing at an inner surface, in a case that the wireless wearable device is embodied as a wristband. A skin of a finger always keeps in contact with the housing at an inner surface, in a case that the wireless wearable device is embodied as a ring. A skin of two sides of the nose always keeps in contact with the housing at nodes pads, or a skin above the two ears always keeps in contact with the housing at temple tips, in a case that the wireless wearable device is embodied as glasses. A skin of a palm always keeps in contact with the housing at a lower part, in a case that the wireless wearable device is a gamepad.

For clear and concise illustration, following description is mainly focused on embodiments of an earbud. It is appreciated that embodiments of other suitable gadgets or accessories may be acquired from the earbud through analogy. Therefore, features described in following embodiments may also apply to other suitable gadgets or accessories, even if details merely concern earbuds in the description.

Reference is made to FIG. 2, which are structural diagrams of an earbud according to an embodiment of the present disclosure. The left subfigure shows an overall three-dimensional view of the earbud, in which the PCB and the first electrode of the antenna module is emphasized by using deeper shades. It is noted that the housing is not completely shown in FIG. 2, for better illustrating a position of the PCB and the first electrode. As discussed above, the housing may be configured to expose the first electrode at a surface of the housing, or may be configured to enclose the first electrode. Although FIG. 2 shows a specific physical configuration for the PCB and the first electrode, it is appreciated that the present disclosure is not limited thereto. The PCB and the first electrode may be implemented in other shapes and dimensions, as long as they can achieve transmission and receiving of signals in wireless communication.

In one embodiment, a total length of the first electrode is less than a quarter of a wavelength corresponding to the communication protocol. For example, the communication protocol may be Wi-fi of 2.4 GHz, of which a wavelength is 125 mm, and thereby the total length of the first electrode is less than ¼×125=31.25 mm. For another example, the communication may be GPS of 1.228 GHz, of which a wavelength is 244.3 mm, and thereby the total length of the first electrode is less than ¼×244.3=61.075 mm. Those skilled in the art can appreciate that a length required for an antenna corresponding to a wavelength should be at least a quarter of the wavelength in conventional technology. In this embodiment, a difference between such limitation and the total length of the first electrode is compensated by a part of the human body (namely, an ear for the earbud) which serves as the antenna together with the first electrode. Generally speaking, the farther the first electrode is from the part of the body, the less total length the part of the body can compensate. The first electrode is mainly configured to ensure a good quality of the signals when coupling the signals into the RF circuit of the PCB.

In one embodiment, the first electrode as shown in FIG. 2 may be configured to keep in contact with the part of the body when serving as a part of the antenna. In such case, a portion of the first electrode is located at a surface of the housing to implement such contact, while another portion of the first electrode is located inside the housing to connect the PCB. It is appreciated that in a case that the first electrode is located at a surface of the housing and the housing is made of a conductive material such as metal, the housing may further serves as a part of the antenna besides the first electrode and the human body. In such case, a total length of the first electrode may be further reduced to a smaller scale.

In another embodiment, the first electrode as shown in FIG. 2 may not touch the part of the body when serving as a part of the antenna. A portion of the first electrode may still be disposed at a part of the surface of the housing, except that such part of the surface does not touch the skin of the user when the wireless wearable device is worn by the user. Alternatively, the whole first electrode may be located inside the housing, namely, the first electrode is enclosed in the housing. In the latter case, a distance between the portion of the first electrode and the part of the body may be regarded as including three parts: a first distance between the portion of the first electrode to an inner surface of the housing, a thickness of the housing, and a second distance between an outer surface of the housing and the human body. One or both of the first distance and the second distance may be equal to zero. For example, the first distance may be zero in case of the first electrode being attached to the inner surface of the housing, and the second distance may be zero in case of the part of the body keeping in contact with the outer surface of the housing.

In one embodiment, there is a dielectric layer located between the portion of the first electrode and the part of the housing. A part of the housing may be made of a conductive material, and a distance between the part of the housing and the portion of first electrode serves as the aforementioned first distance. In such case, the PCB may be further configured to detect a change in capacitance between the part of the housing and the first electrode, so as to determine an operation performed by the user on the housing. For example, the operation may be a touch on the part of the housing, or may be a squeeze or a stretch on a region in which the part of the housing is located.

In one embodiment, the total length of the first electrode is equal to an eighth of the wavelength corresponding to the communication protocol. For example, the communication protocol may be Wi-fi of 2.4 GHz, of which a wavelength is 125 mm, and thereby the total length of the first electrode is equal to ⅛×125=15.625 mm. For another example, the communication may be GPS of 1.228 GHz, of which a wavelength is 244.3 mm, and thereby the total length of the first electrode is equal to ⅛×244.3=30.5375 mm. Generally, the eighth of the wavelength is approximately a balance point between a quality of signals and a size of the first electrode. It is appreciated that in embodiments of the present disclosure, the total length of the first electrode may not be accurately equal to the eighth of the wavelength, and any value less than the quarter of the wavelength may be appropriate as long as the quality of signals and the size of the first electrode meet an application requirement.

Reference is further made to FIG. 2, where signals are fed from the RF circuit (not shown) of the PCB to the first electrode for transmission, or fed from the first electrode to the PCB for receiving. The first electrode is generally made of metal or other conductive materials, such as brass, copper, aluminum, stainless steel, or phosphor bronze. In one embodiment, the first electrode includes a feeding part and a flat part. The feeding part serves a bridge between the flat part and the PCB both signally and physically. That is, the flat part is connected and coupled to the PCB via the feeding part.

The feeding part is directly connected and coupled to the RF circuit of the PCB. As shown in FIG. 2, the feeding part may be a metal band includes two segments that are perpendicular to each other. It is noted that the feeding part may be implemented in other forms according to a specific structure of the wireless wearable device. For example, the feeding part may be an integral metal band or a metal plate. In one embodiment, the feeding part is connected to the RF circuit through conventional techniques, such as FPC (flexible print circuits), conductive printing (e.g. laser direct structuring), metal-plate connection, or wiring. The present disclosure is not limited thereto, as long as the formed feeding part can transmit signals well between the flat part and the RF circuit.

Generally, the flat part is a main component of the first electrode. The flat part may be in direct contact with the part of the body, or may be a portion closest to the part of the body in the antenna module. The flat part may be a metal plate with a certain thickness. As shown in FIG. 2, the flat part may be a rectangular plate which is perpendicular to a connected segment of the feeding part. In one embodiment, such connected segment may be implemented as a contact spring or a pogo-pin. It is noted that the flat part may be implemented in other forms according to a specific structure of the wireless wearable device. For example, a shape of the flat part in a plane perpendicular to the thickness may be circular or trapezoid. In one embodiment, the shape may be a loop or a spiral according to a practical requirement. In another embodiment, the flat part may be curved to accommodate with a limited space within the housing.

The total length of the first electrode is determined by dimensions of the first electrode, and more specifically, by dimensions along which electromagnetic waves propagate in the first electrode. In one embodiment, the feeding part includes a band or a wire extending from the RF circuit to the flat part, and the flat part includes a plate with a certain shape and a certain thickness. In such case, the total length of the first electrode is equal to a sum of a length of the feeding part, a thickness of the flat part, and a half of a peripheral of the shape of the flat part. As an example, dimensions of the first electrode are marked in FIG. 2 according to an embodiment of the present disclosure. The first electrode is for wireless communication under one or both of the Bluetooth® and Wi-fi, of which a frequency is around 2.44 GHz and a wavelength is approximately 123 mm. The two segments of the feeding part are 2 mm and 1 mm, respectively, in length. The feeding part is 0.5 mm in thickness, 2 mm in width, and 6.5 mm in length. Hence, the length of the feeding part is equal to 2+1=3 mm, a half of the peripheral of the rectangular is equal to 6.5+2=8.5 mm, and the total length of the first electrode is equal to 3+0.5+8.5=12 mm, which is less than an eighth of the wavelength. It is appreciated that such dimensions are merely one embodiment of the present disclosure, and the dimensions and the shape concerning the first electrode can be tuned according to a practical requirement. For example, the total length of the first electrode may be controlled between 5 mm to 15 mm for the same wavelength when it is configured to keep in contact the human body during usage. For another example, the total length of the first electrode may be controlled between 10 mm to 25 mm for the same wavelength when it is configured to be separated from the human body by 0.05 mm to 3 mm during usage, so as to implement the antenna in conjunction with the human body.

Hereinafter described are some details of performances of an earbud on a basis of FIG. 2. Reference is first made to FIG. 3, which is a diagram of a three-dimensional model of a user wearing an earbud according to an embodiment of the present disclosure. It is assumed that the earbud is worn on a right ear of a user. An earbud on a left ear can be easily deduced from such case. An overall human head is simulated to evaluate performances of the earbud.

Reference is then made to FIG. 4, which are detailed diagrams of an earbud worn by a user according to an embodiment of the present disclosure. As shown in FIG. 4, the housing of the earbud includes a cylinder-like structure containing the PCB, which is located on an outer side of an earplug. In FIG. 4, a part of the first electrode is located at a position where a side surface of the cylinder structure contacts with the external ear. For better illustration, the portion in which the first electrode is located is enlarged. In the enlarged view, it can be seen that the flat part of the first electrode is in contact with the antitragus of the right ear, as indicated by a dotted circle. Thereby, at least the first electrode and the right ear would form an antenna for the earbud.

It is noted that FIG. 4 merely shows one embodiment of the present disclosure. In another embodiment, the housing of the earbud may be of an irregular shape that fits the concha of the human ears. Further, the first electrode may contact with the concha at another position, and the first electrode still keeps in contact with the concha during usage. Alternatively, the first electrode may be located in another part of the side surface while not being in contact with the ear, or the first electrode may be located inside the housing as illustrated in FIGS. 1b or 1c.

An earbud with a small size when worn by a user is generally fixed to the ear through the earplug, or through a support wing fixed on a cylinder portion containing a speaker. Thereby, it may be more preferable that one or more positions near the entrance of the external acoustic meatus serve as the antenna for the wireless signal together with the first electrode. In one embodiment, the part of the body may refer to at least one of a tragus, an antitragus, an antihelix, and crus of helix of an ear of the user, when the earbud is worn by the user.

Hereinafter FIGS. 5a to 7b are illustrated to describe performance of ear buds adopting a structure according to technical solutions of the present disclosure, where the first electrode is located at a surface of the housing and keeps in contact with a skin of the ear during usage.

Reference is further made to FIGS. 5a and 5b, which are Smith chart and a graph of a return loss of an antenna of an earbud according to an embodiment of the present disclosure. Both the Smith chart and the graph of the return loss is obtained on a basis of the structure as shown in FIG. 2 and the model established as shown in FIG. 3. As an example, the target bandwidth in FIG. 5b corresponds to wireless communication under protocols of the Bluetooth® or 2.4 GHz Wi-fi. A matched impedance for the antenna is set to be 50 ohm.

As shown in FIGS. 5a and 5b, two frequencies within the target bandwidth are particularly marked, namely, point 1 representing a frequency of 2.4 GHz and point 2 representing a frequency of 2.48 GHz. From FIG. 5a, impedance of point 1 and point 2 can be obtained, which are (36.71+3.68i)ohm and (36.15+5.92i)ohm, respectively. Both points 1 and 2 are located near the center of the Smith chart, indicating a rather low reflection coefficient. As shown in FIG. 5b, the return losses of points 1 and 2 are −15.98 dB and −15.17 dB, respectively, and the curve within the target band is smooth. Therefore, the earbud with the first electrode as shown in FIGS. 2 and 3 provides signals with high quality between the PCB and the antenna for the target bandwidth.

Reference is further made to FIG. 6, which is a graph of an antenna efficiency of an antenna of an earbud according to an embodiment of the present disclosure. The graph of the antenna loss is obtained on a basis of the structure as shown in FIG. 2 and the model established as shown in FIG. 3. FIG. 6 shows that the antenna efficiency is approximately −9 dB within the target bandwidth, and a profile of the curve in the target bandwidth is quite smooth. The antenna efficiency herein is defined as a ratio of the power delivered to the antenna relative to the power radiated from the antenna. Such result indicates that the first electrode keeping in contact with the human body does exhibit radiation characteristics of a standard antenna, and a very high portion of power present at an input of the antenna is radiated away from the human body for all signals within the target bandwidth. It is appreciated that such result further indicates a good performance of low power consumption. Thereby, a size of a battery required in the earbud can be reduced, which further contributes to the miniaturization of the whole device.

Reference is further made to FIGS. 7a and 7b, which are graphs of radiation patterns of an antenna of an earbud according to an embodiment of the present disclosure. The radiation patterns in FIGS. 7a and 7b are both depicted for vertical planes, where FIG. 7a concerns a plane parallel to a line connecting the two ears, and FIG. 7b concerns a plane perpendicular to the line connecting the two ears. A general radiation pattern for a whole sphere may be coarsely deduced from FIGS. 7a and 7b. It can be seen from FIGS. 7a and 7b that the radiation is nearly uniform in all directions, except for a direction pointing to the head. The reason lies in that there are various tissues and organs (even bones) along such direction besides the skin and the cartilage, thereby hindering propagation of electromagnetic signals. It is appreciated that such direction would not significantly influence the performances of the earbud. In practice, the signals in such direction may be collected by a paired earbud worn on the other ear, if necessary.

Hereinafter an earbud adopting another structure according to technical solutions of the present disclosure is taken as an example, in order to illustrate performances under different application scenarios. The first electrode is located inside the housing at a position close to a skin of the ear during usage, and is separated from the ear by a part of the housing.

Reference is made to FIG. 8, which is a schematic structure of a flat part of a first electrode according to an embodiment of the present disclosure. The flat part is a stripe of an L-shape, and an end of a short edge of the L-shape is connected to the PCB via the feeding part of the first electrode. In this embodiment, a dimension of the feeding part may be small enough with respect to the flat part, and therefore can be neglected. A dimension and a thickness of the first electrode may be tuned based on a practical requirement, for example, a frequency of the wireless signal, a thickness and a material of the housing, and a distance between a skin of the ear and the first electrode.

In this embodiment, a frequency of the wireless signal transmitted and received by the antenna module may be set around 2.44 GHz. Namely, the earbud adopts, for example, Bluetooth® or wireless fidelity in wireless communication. As an example, a width of the stripe is set to be 3 mm, a length of the long edge of the L-shape is set to be 15 mm, and a distance between a skin of the ear and the first electrode ranges from 0.05 mm to 3 mm.

Reference is made to FIG. 9a and FIG. 9b, which are Smith chart and a graph of a return loss of an antenna of an earbud in a free-space condition and when worn by a user in such case. The same indicators in FIGS. 9a and 9b correspond to the antenna operating under the same condition. Specifically, the hollow, grey-filled, and black-filled squares present the antenna operating under 2.4 GHz, 2.44 GHz, and 2.48 GHz, respectively, when being arranged in free space; the hollow, grey-filled, and black-filled triangles present the antenna operating under 2.4 GHz, 2.44 GHz, and 2.48 GHz, respectively, when the first electrode is separated from the skin of the ear by 0.05 mm; and the hollow, grey-filled, and black-filled circles present the antenna operating under 2.4 GHz, 2.44 GHz, and 2.48 GHz, respectively, when the first electrode is separated from the skin of the ear by 3 mm. Similar to FIGS. 5a and 5b, resonance frequencies of the antenna can be read from the graph of the return loss. In the free-space condition, the antenna merely includes the antenna module of the earbud, and the resonance frequency is around 2.65 GHz. When worn by the user, the antenna is formed by the antenna module and at least a part of the ear, and the resonance frequency of the antenna module is reduced from around to 2.44 GHz due to the vicinity of the skin. It is noted that such resonance frequency is achieved while a dimension of the first electrode is kept close to an eighth of the wavelength of the wireless signal. Even when the distance between the skin of the ear and the first electrode is increased from 0.05 mm to 3 mm, the return loss only rises a bit, while the resonance frequency is subject to little change.

Reference is further made to FIG. 10, which is a graph of an antenna efficiency of an antenna of an earbud in the above case. FIG. 10 shows that the antenna efficiency is a bit higher than −9 dB within the target bandwidth, and a profile of the curve in the target bandwidth is quite smooth. Similar to FIG. 6, such result indicates that the first electrode and the human body exhibits radiation characteristics of a standard antenna, and a very high portion of power present at an input of the antenna is radiated away from the human body for all signals within the target bandwidth. Namely, the antenna module is this example also has a good performance of low power consumption.

The earbud the above case is subject to practical performance tests as follows. Six users labeled from A to F are required to wear the earbud and walks away from the mobile phone that communicates with the earbud, as shown in FIG. 11. The mobile phone is put in a bag to simulate a daily application environment. A distance between each user and the mobile phone is recorded as a “missing distance”, when the communication between the earbud and the mobile phone fails. In the earbud, the first electrode is attached to an inner side of a part of the housing, and a thickness of the part of the housing is around 0.05 mm. In order to simulate various application scenarios, the six users wear the earbud in different manners, as shown in FIG. 12. For user A, the part of the housing touches the ear at a lower part of the antihelix. For user B, the part of the housing touches the ear at a higher part of the antihelix. For user C, the part of the housing touches the ear at the antitragus. For user D, the part of the housing touches the ear both the lower part and the higher part of the antihelix. For users E and F, the part of the housing does not touch the ear, but is separated from the antihelix by a gap. A width of the gap is almost even and around 2 mm for user E, and is uneven and ranges from 1 mm to 3 mm for user F.

The above tests are carried out both indoor (i.e. provided with dense physical blockage) and outdoor (i.e. provided scarce physical blockage). Further, the display side of the mobile phone faces the users in some tests, while the back-cover side of the mobile phone faces the users in other tests, such that an attitude of the antenna of the mobile phone is also taken into consideration.

An earbud of a conventional antenna is taken as a reference in the tests. The referential earbud (labeled as “O”) is provided with a structure identical to the above-mentioned earbud (labeled as “N”), except that the antenna is of a traditional “λ/4” design, in which the antenna is located at a top shell of the earbud O prevent interference of the human body as much as possible. The result of the tests is as shown in Table I.

From Table I, it can be seen that the earbud N in the aforementioned embodiment is advantageous over the referential earbud O in all tested application environments. In the outdoor tests, the missing distance is improved by an average of approximately 8 m (calculated over all the six users), no matter it is the display side or the back-cover side of the mobile phone that faces the users. In the indoor tests, the missing distance is improved by an average of 12 m when the display side faces the users, and by an average of 12.6 m when the back-cover side faces the users.

TABLE I

Missing distances (in meters) of earbuds

Indoor tests
Outdoor tests

Back-cover

Back-cover

Display side
side
Display side
side

User
N
O
N
O
N
O
N
O

A
23.8
13.2
24.5
12.5
43.2
41.4
60.0
47.4

B
34.2
13.5
34.5
14.5
57.6
38.4
59.4
50.4

C
24.9
22.7
22.2
17.7
36.0
21.6
39.6
31.2

D
24.0
12.9
24.7
13.3
43.2
36.0
53.4
55.8

E
29.5
13.4
30.6
13.5
31.8
28.8
46.2
39.0

F
24.7
13.0
24.9
14.5
27.0
24.0
39.6
28.8

Average
26.8
14.8
26.9
14.3
39.8
31.7
49.7
42.1

The above description concerning FIGS. 3 to 12 is related to performances of the earbud. Since a main principle of the first electrode which serves as the antenna together with a part of the human body is identical, similar technical effects are capable to be obtained in a case that the wireless wearable device is embodied in a form other than the earbud. As an example, FIG. 13 shows application scenarios in which the wireless wearable device is a wireless gaming controller. In such cases, the first electrode may be located on a surface, or at an inner side, of the lower part (as indicated by any dotted circle in FIG. 13) of the housing, and the lower part of the housing keeps in contact with a palm of the user during usage.

In a case the first electrode is located at the surface of the housing, the wireless wearable device according to an embodiment of the present disclosure is further advantageous in selection of housing materials. Generally, a conventional wireless wearable device encloses an antenna within the housing to avoid damages due to an external force. Even though a design of metal housing is increasing popular in the consumer electronics, the housing enclosing the antenna could not be made of metal, in order to prevent the electromagnetic shielding effect from degrading the wireless signals. On the contrary, that would not be a limitation for the wireless wearable device according to an embodiment of the present disclosure. Since the antenna is constituted by at least the first electrode and the human body, the whole antenna is not enclosed by the housing. Hence, a metal housing would not shield a signal transmitted or received by the RF circuit of the inner PCB. Further, the first electrode is still well protected from possible bending or striking, because it is in contact with the skin of the user and therefore is not directly exposed to an external force.

In one embodiment, the housing is made of metal, and housing is connected to the first electrode or serves as the first electrode. The first electrode may be fabricated separately from the housing, even if both are made of metal. In such case, the first electrode and the housing may be made of different materials. The connection between the first electrode and the housing may be implemented through wiring (for example, the feeding part is connected to the housing via an inner wire), or simply through physical contact (for example, the flat part directly contacts the housing). Alternatively, the housing and the first electrode may be fabricated simultaneously or integrated with a same material. The housing itself may be a metal both contacting the skin of the user and coupled to the RF circuit of the inner PCB. In such case, the housing serves as the first electrode.

It is appreciated that the first electrode and the metal housing may not be connected to each other in some embodiments. In such case, an insulating material or a dielectric material may be provided around the first electrode for isolation from the housing.

In one embodiment, the metal housing may serve as a control means of the wireless wearable device. As an example, a second electrode is provided within the metal housing. A capacitance between the second electrode and the housing may be detected by, for example, a circuit on the PCB. The user may perform an operation such as a touch or a tap on the housing in a region corresponding to the second electrode. In such case, the detected capacitance would change, and thereby the operation of the user can be detected.

It is appreciated that the metal is not the only choice for fabricating the housing. The candidates may include other conductive materials, and even insulating materials. The metal material of the housing in the aforementioned embodiments may be replaced with another conductive material where appropriate. An advantage of using the metal or other conductive materials would reduce a risk of electrostatic damages, but the insulating materials are also feasible when applying a conventional electrostatic protection technique. Moreover, the housing can be made by using a combination of one or more of the above materials.

In some embodiments, the housing is made of an insulating material. In case of being located at a surface of the housing, the first electrode may be embedded in the insulating material. The embedding may be implemented by exposing a part of the first electrode via a window at the surface of the housing, or fixedly attaching the first electrode to the surface of the housing. The present disclosure is not limited thereto, as long as the first electrode is kept in contact with the skin during usage.

In one embodiment, the insulating material may be an elastic material, especially in a region of the housing near the first electrode. The elastic material may fit better to a shape of the skin of the human body, since such shape may vary for different users or different postures. Thereby, a better contact between the first electrode and the part of the body can be achieved in a case that the first electrode is located at a surface of the housing. Also, a distance between the first electrode and the part of the body can be minimized as much as possible in a case that the first electrode is enclosed in the housing.

In practice, the PCB may include a circuit to detect a state of contact between the wireless wearable device and the part of the body. For example, an electric length of the antenna is reduced when the wireless wearable device is detached from the part of the body, because it merely includes the first electrode and a resonance frequency thereof is abruptly increased. Thereby, amplitude of signals within a previous wireless band would be significantly reduced after the detachment. Accordingly, the detachment can be detected through the amplitude of signals. It is appreciated that another parameter is similarly applicable in such detection, as long as it may change due to the detachment. For example, a temperature, a resistance, or a capacitance concerning the first electrode may be applied.

The detachment may be detected to implement various functions. For example, in a case the first electrode is located at the surface of the housing, a function of the first electrode may further be expanded according to an embodiment of the present disclosure. In one embodiment, the wireless wearable device further includes a battery located in the housing, and the battery is charged via the first electrode in a case that the wireless wearable device is not worn by the user. For example, a charger for the wireless wearable device includes a charging contact, and the first electrode is disposed in contact with the charging contact when the wireless wearable device is not worn by the user. Once the aforementioned detachment is detected, the circuit on the PCB may switch from an “antenna mode” to a “charging mode”, and an electrical connection between the first electrode and the battery may be activated, so that the first electrode is configured to charge the battery in such case.

The aforementioned mode switching may be implemented in a manner other than detachment detection. For example, the charging mode may be activated when detecting the wireless device is connected to a charging cable, is placed into a charging box, or is put near a wireless charging apparatus. Such detection may be implemented through conventional technologies, such as magnetic induction, which are not described in detail herein. It is noted that these manners of mode switching are suitable for the aforementioned case concerning the first protocol and the second protocol, where the detachment is configured as a condition for switching a wireless band applied in communication between the wireless wearable device and an external device.

The first electrode may conform with the charging function in various manners. In one embodiment, the first electrode may include two separate pieces. In the antenna mode, the two pieces may be connected with each other, and/or both connected to the RF circuit. In the charging mode, the two pieces may be disconnected from each other, and connected to positive and negative terminals, respectively, of the battery. As an alternative solution, the first electrode may include one piece. In the charging mode, the piece is connected to one of the positive or negative terminal of the battery, and the other terminal of battery is charged via an electrode different from the first electrode.

Some solutions may be further adopted to improve protection the exposed first electrode. Since the first electrode is in direct contact with the skin in the wireless wearable device according to an embodiment of the present disclosure, it may be subject to secretion of the skin during usage, such as sweat. Anti-erosion means in conventional technology may be applied to the first electrode, or further to the metal housing. In one embodiment, the first electrode may be coated with a layer of gold or alumite at least in a region contacting the skin. It is appreciated that the coating may cover the whole first electrode, depending on a practical requirement.

It should be noted that, the relationship terms such as “first”, “second” and the like are only used herein to distinguish one entity or operation from another, rather than to necessitate or imply that an actual relationship or order exists between the entities or operations. Furthermore, the terms such as “include”, “comprise” or any other variants thereof means to be non-exclusive. Therefore, a process, a method, an article or a device including a series of elements include not only the disclosed elements but also other elements that are not clearly enumerated, or further include inherent elements of the process, the method, the article or the device. Unless expressively limited, the statement “including a . . . ” does not exclude the case that other similar elements may exist in the process, the method, the article or the device other than enumerated elements.

The embodiments of the present disclosure are described in a progressive manner, and each embodiment places emphasis on the difference from other embodiments. Therefore, one embodiment can refer to other embodiments for the same or similar parts.

According to the description of the disclosed embodiments, those skilled in the art can implement or use the present disclosure. Various modifications made to these embodiments may be obvious to those skilled in the art, and the general principle defined herein may be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure is not limited to the embodiments described herein but confirms to a widest scope in accordance with principles and novel features disclosed in the present disclosure.

While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended claims and their legal equivalents.

WIRELESS WEARABLE DEVICE

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