Abstract:
A wireless communication apparatus, includes: a second circuit board; a wireless communication processing circuit accommodated in the second circuit board; a first signal line that connects a first ground potential portion of the first circuit board with a first antenna feed point of the wireless communication processing circuit, wherein the first signal line and the first ground potential portion are configured to operate as a first antenna; a second signal line that connects the first circuit board with the second circuit board and is configured to convey a baseband signal; and a circuit element that is connected to the second signal line and is configured to block RF signals that are sent and received by the wireless communication processing circuit.

Description:
FIELD 
     The exemplary embodiments described herein relate to wireless communication terminals. 
     BACKGROUND 
     In recent years, wearable devices that are worn on bodies of users have been developed. For example, wristwatch-type wireless communication terminals named as “smart watches” are developed. Usually, the wrist-watch type wireless communication terminals include a radio telephone function, and an antenna which performs transmission and reception of radio signals. A length of the antenna is decided by a wavelength of the signal which is transmitted and received by the antenna. For example, an appropriate length for the antenna which transmits and receives 800 MHz band signals in a cellular communication system is defined by the wavelength of the 800 MHz signal. 
     On the other hand, it is necessary to keep the wearable device such as the wristwatch smaller than conventional mobile phones. As recognized by the inventor, a limitation with small wearable electronic device is the limited space that is used to include components, (e.g., antennas), and therefore, the wearable device is preferred to include a least number of parts. 
     SUMMARY 
     The foregoing paragraphs have been provided by way of general introduction, and are not intended to limit the scope of the following claims. The described embodiments, together with further advantages, will be best understood by reference to the following detailed description taken in conjunction with the accompanying drawings. 
     In one embodiment, there is provided a wireless communication apparatus, including: a second circuit board; a wireless communication processing circuit accommodated in the second circuit board; a first signal line that connects a first ground potential portion of the first circuit board with a first antenna feed point of the wireless communication processing circuit, wherein the first signal line and the first ground potential portion are configured to operate as a first antenna; a second signal line that connects the first circuit board with the second circuit board and is configured to convey a baseband signal; and a circuit element that is connected to the second signal line and is configured to block RF signals that are sent and received by the wireless communication processing section. 
     In another embodiment, the circuit element is an inductor. 
     In another embodiment, the first antenna feed point of the wireless communication processing circuit includes a matching circuit, the matching circuit matches a first impedance of the first signal line with a second impedance of the wireless communication processing circuit. 
     In another embodiment, the first circuit board includes a receiver, a vibration element, a LED and a switch, wherein each mounted on a front surface of the first circuit board, and the first ground potential portion is mounted on a rear surface of the first circuit board. 
     In another embodiment, the wireless communication apparatus further includes: a third circuit board, a third signal line, a fourth signal line, a second circuit element and a second antenna feed point of the wireless communication processing circuit of the second circuit board, wherein the third signal line connects a second ground potential portion of the third circuit board with the second antenna feed point, the third signal line and the second ground potential portion are configured to operate as a second antenna, the fourth signal line connects the second circuit board with the third circuit board and is configured to convey a baseband signal, the second circuit element that is connected to the fourth signal line and blocks RF signals that are sent and received by the wireless communication processing circuit, and the wireless communication apparatus can use either the first antenna or the second antenna. 
     In another embodiment, the second circuit element is an inductor. 
     In another embodiment, the fourth signal line includes a plurality of signal lines. 
     In another embodiment, the wireless communication apparatus further includes: a third circuit board, a fourth signal line, a second circuit element and a low pass filter disposed on the third circuit board, wherein the first ground potential portion of the first circuit board is connected to a second ground potential portion of the third circuit board, the fourth signal line connects the second circuit board with the third circuit board and is configured to convey a baseband signal, the second circuit element that is connected to the fourth signal line and blocks RF signals that are sent and received by the wireless communication processing circuit, and the low pass filter is connected between the first ground potential portion and the second ground potential portion, wherein the filter allows signals with frequencies that are lower than a predetermined frequency to pass through, and blocks the signals with frequencies that are higher than the predetermined frequency. 
     In another embodiment, the wireless communication processing circuit is configured to operate at two predetermined bands. 
     In another embodiment, the second signal line includes a plurality of signal lines. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete appreciation of the disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: 
         FIG. 1  is an exemplary embodiment of a circuit board of a wireless communication terminal; 
         FIG. 2  is an exemplary structure of a wireless communication terminal; 
         FIG. 3  is an exemplary arrangement of circuit boards and batteries; 
         FIG. 4  is an exemplary arrangement of the circuit boards and a resin sheet; 
         FIG. 5  is an exemplary bottom view of one of the circuit boards; 
         FIG. 6  is another exemplary embodiment of the wireless communication terminal; 
         FIG. 7  is another exemplary embodiment of the wireless communication terminal; and 
         FIG. 8  is another exemplary embodiment of the wireless communication terminal. 
     
    
    
     DETAILED DESCRIPTION 
     In the drawings, like reference numerals designate identical or corresponding parts throughout the several views. Further, as used herein, the words “a,” “an” and the like generally carry a meaning of “one or more,” unless stated otherwise. The drawings are generally drawn to scale unless specified otherwise or illustrating schematic structures or flowcharts. 
     Furthermore, the terms “approximately,” “about,” and similar terms generally refer to ranges that include the identified value within a margin of 20%, 10%, or preferably 5%, and any values therebetween. 
     As recognized by the inventor, a wireless communication terminal, such as a wearable device has limited space and so it is preferable to include a least number of components, such as antennas so as to fit in a wearable-size form factor. 
       FIG. 1  is an exemplary embodiment of a circuit board of a wireless communication terminal, which is implemented by several circuit boards and interconnections. The exemplary embodiment of the wireless communication terminal includes three circuit boards  10 ,  20 , and  30  as shown. 
     The circuit components that operate at baseband are arranged at circuit boards  10  and  30 . A wireless communication processing section  24 , which performs a transmission process and a reception process of a radio signal is implemented at the circuit board  20 . 
     Signal lines  21  connect the circuit board  10  to the circuit board  20 , and signal lines  31  connect the circuit board  20  to the circuit board  30 . The signal lines  21  and  31  transmit baseband signals, which are not modulated by a high frequency signal. Moreover, the signal lines  21  and  31  include the multiple signal lines. The signal lines  21  are located at one flexible circuit board, and the signal lines  31  are located in another flexible circuit board. The length of the signal lines  21  and  31  are several millimeters (e.g., about 1 cm). Inductors  12  are implemented in the connection place between each signal line of the signal lines  21 , and circuit board  10 . The inductors  12  block the signals of the band in which the antenna transmits or receives, and only allow the baseband signals to pass through the signal lines  21  and  31 . 
     A signal line  22  connects an antenna feeding point  23  of the wireless communication processing section  24  in the circuit board  20 , to a grounding potential part  11  of the circuit board  10 . The antenna feeding point  23  includes a matching circuit. The length of the signal line  22  is several millimeters (e.g., 1 cm in length). Furthermore, the signal lines  21  are also located on another flexible circuit board. The flexible circuit board which the signal line  21  is located at, and the circuit board which the signal line  22  are located, are separated as far as possible. The grounding potential part  11  of the circuit board  10  covers most of the back surface of the circuit board  10 . 
     The grounding potential part  11  and the signal line  22  of the circuit board  10  operate as an antenna of the wireless communication processing section  24 . For example, the antenna performs a transmission or a reception of an 800 MHz band signal. Therefore, the wireless communication terminal does not need another antenna that is separated from the grounding potential part  11 , or the signal line  22 , and therefore can be much smaller than the wireless communication terminals that require dedicated antennas. 
       FIG. 2  is an exemplary structure of the wireless communication terminal. The wireless communication terminal includes a mobile telephone that can be used for communicating voice. The circuit board  10  includes components, such as a receiver  13 , a vibrator  14 , a light-emitting diode (LED)  15 , and a switch  16 . The receiver  13 , the vibrator  14 , the LED  15  and the switch  16  are arranged on the surface of the circuit board  10 . The receiver  13  outputs a sound from an input voice signal. The vibrator  14  vibrates and the LED is illuminated when the wireless communication terminal receives a drive signal to indicate the data transmission/reception is completed or a calling signal is coming. The switch  16  turns on, or off, a power supply of the wireless communication terminal. The components located at the circuit boards  10  are connected to the circuit board  30  through the signal lines  22  and  31 . 
     High frequency signals are processed at the circuit board  20 . That is, the wireless communication processing section  24  and a short-distance communication process part  25  are implemented at the circuit board  20 . The wireless communication processing section  24  operates at 800 MHz band or a higher frequency band, and communicates wirelessly with base stations. The signal line  22  is connected to the antenna feeding point  23  of the wireless communication processing section  24 . The matching circuit of the antenna feeding point  23  matches an impedance of the signal line  22 , with an impedance of the wireless communication processing section  24 . The short-distance wireless communication process part  25  also communicates wirelessly with the terminal for the access point of wireless Local Area Networks (LANs), or Bluetooth™. The short-distance wireless communication process part  25  communicates thorough a 2 GHz frequency band or a frequency band that operates at a high frequency than the 2 GHz. 
     This antenna  26  is located at the edge part of the circuit board  20 . Since the transmission or the reception is operated at the 2 GHz band or a frequency band higher than that, the antenna  26  can be very small. 
     The circuit board  30  includes a control part  32 , a microphone  33 , a Universal Serial Bus (USB) port  34 , and a Subscriber Identity Module (SIM) card adapter  35 . The control part  32  controls an operation of each part of the wireless communication terminal. The microphone  33  outputs a voice signal. The USB port  34  is a terminal which connects the wireless communication terminal with a cable that is adapted to a specification of the USB. A SIM card that records ID numbers of the radio telephones can be used through the SIM card adapter  35 . A battery  41 , a battery  42 , a battery  43  and a battery  44  are connected to the circuit board  30  through power wires  51  and  52 . The batteries ( 41 ,  42 ,  43  and  44 ) can be lithium ion batteries. 
       FIG. 3  is an exemplary arrangement of the circuit boards ( 10 ,  20  and  30 ) the batteries ( 41 ,  42 ,  43  and  44 ). The circuit boards ( 10 ,  20  and  30 ) and the batteries ( 41 ,  42 ,  43  and  44 ) are substantially equivalent sizes, and are arranged at equal intervals. 
     A thickness of each battery (e.g.,  41 ,  42 ,  43  and  44 ) is several millimeters. The circuit boards ( 10 ,  20  and  30 ) and the batteries ( 41 ,  42 ,  43  and  44 ) are located on a resin sheet  100  that is flexible and includes resin or metal cases. 
       FIG. 4  shows the resin sheet  100  and the circuit boards ( 10 ,  20  and  30 ), respectively. The resin sheet  100  includes three board arrangement parts ( 110 ,  120  and  130 ) and four battery arrangement parts ( 140 ,  150 ,  160  and  170 ). Connection parts are used to connect the arrangement parts. The connection parts ( 111  and  112 ) connect the board arrangement part  110  and the board arrangement part  120 . The connection parts ( 121  and  122 ) connect the board arrangement part  120  and the board arrangement part  130 . The connection parts ( 131  and  132 ) connect the board arrangement part  130  and the battery arrangement part  140 . The connection parts ( 141  and  142 ) connect the battery arrangement part  140  and the battery arrangement part  150 . The connection parts ( 151  and  152 ) connect the battery arrangement part  150  and the battery arrangement part  160 . The connection parts ( 161  and  162 ) connect the battery arrangement part  160  and the battery arrangement part  170 . 
     Furthermore, the circuit board  10  is located at the board arrangement part  110 , the circuit board  20  is located at located at the board arrangement part  120 , and the circuit board  30  is located at located at the board arrangement part  130 . The battery  41  is located at the battery arrangement part  140 , the battery  42  is located at the battery arrangement part  150 , the battery  43  is located at the battery arrangement part  160 , and the battery  44  is located at the battery arrangement part  170 . 
     The resin sheet  100  is made of a flexible raw material. Moreover, the signal lines ( 21 ,  22  and  31 ) and the power wires ( 51  and  52 ) are also implemented on the flexible circuit boards. Therefore, the resin sheet  100  with the circuit board ( 10 ,  20  and  30 ) and the batteries ( 41 ,  42 ,  43  and  44 ) can be folded at the connection parts (e.g.,  111 ,  112 ,  121 ,  122 ,  131 ,  132 ,  141 ,  142 ,  151 ,  152 ,  161  and  162 ). Therefore, the wireless communication terminal can be wound around a wrist of the user as a wristwatch. 
       FIG. 5  is an exemplary bottom view of the circuit board  10 . The grounding potential part  11  of the circuit board  10  is located at the entire of back surface of the circuit board  10 . The receiver  13  and the vibrator  14  are located at a surface side of the circuit board  10 . 
     The signal line  21  is connected to the surface side of the circuit board  10 . Moreover, the signal line  22  is directly connected to the back surface of the circuit board  10  through the grounding potential part  11 . 
       FIG. 6  is another embodiment of the wireless communication terminal. Compared with the previous embodiment shown in  FIG. 1 , the signal line  21  is located closer to the signal lines  22  to operate as the antenna. Furthermore, multiple of the signal line  21  and the single signal lines  22  can be arranged together in one flexible substrate. The connection of the circuit board  10  and the circuit board  20  in  FIG. 6  becomes simpler compared with the connection of the circuit board  10  and the circuit board  20  in  FIG. 1 , because of the closer distance between the signal lines  21  and the signal lines  22 . 
       FIG. 7  is another embodiment of the wireless communication terminal. Compared with the previous embodiment shown in  FIG. 1 , the embodiment shown in  FIG. 7  includes two antenna feeding points. A first antenna includes the grounding potential part  11  and the signal line  22  of the circuit board  10 . A second antenna includes a grounding potential part  37  and a signal line  36  of the circuit board  30 . The wireless communication processing section  24  includes two antenna feeding points. The antenna feeding point  23  is connected to the signal line  22 . 
     Moreover, another antenna feeding point  23   a  of the wireless communication processing section  24  is connected to the signal line  36 . The signal line  36  is connected to the grounding potential part  37  of the circuit board  30 . The grounding potential part  37  is located at the back surface of the circuit board  30 . The signal line  36  is arranged in the position away from signal lines  31 . 
     The signal line  36  and the grounding potential part  37  that is connected to the signal line  36  forms the second antenna. An inductor  38  is located at the connection point of the signal line  31  and the circuit board  30 . This inductor  38  blocks the signal of the frequency band that the second antenna transmits or receives. 
     Because the wireless communication terminal includes two antennas, the wireless communication processing section  24  is equipped to support a diversity reception that selects and receives signals from a favorable antenna among several antennas. 
       FIG. 8  is another embodiment of the wireless communication terminal. Compared with the previous embodiment, the circuit board  30  also includes a wireless communication processing section  24   a . The wireless communication processing section  24  wirelessly communicates with the base station for radio telephones, and operates at two frequency bands, one is 800 MHz band and the other is 1.5 GHz band. A signal line  27  connects an antenna feeding point  23   b  of the wireless communication processing section  24   a , to a ground potential part  28  at the back surface of the circuit board  20 . Furthermore, the signal line  22  connects the grounding potential part  28 , to the grounding potential parts  11  at the back surface of the circuit board  10 . A filter  29  is located at the connection point of the signal line  22  and the grounding potential part  28  of the circuit board  20 . The filter  29  is a low-pass filter which allows the signal below a predetermined frequency band to pass through. For example, the filter  29  allows the signal of the 800 MHz band to pass through, while blocks the signal of the 1.5 GHz band. 
     In addition, inductors  39  are located at connection places of the signal lines  31  and the circuit board  20 . The inductors  39  block the signal of the band which an antenna transmits or receives. 
     In this embodiment, the signal line  27 , the signal line  22 , and the grounding potential part  11  operates as an antenna of the wireless communication processing section  24   a . The antenna of the wireless communication processing section  24   a  performs the transmission or the reception of the signal of a low frequency band (e.g., 800 MHz band). Moreover, the signal line  27  and the grounding potential part  28  of the circuit board  20  form another antenna which performs the transmission or the reception of the signal of a high frequency band (e.g., 1.5 GHz band). 
     Since the filter  29  is connected to the signal line  22  and block the high frequency signal, the signal line  22  and the grounding potential part  11 , which are located before the filter  29 , do not operate at 1.5 GHz band. Thus, the transmission or reception of the signal of two frequency bands can be performed in the embodiment that is disclosed in  FIG. 8 . 
     The disclosed antennas are used to connect the base station for radio telephones, the same structure may be sufficient as the other antenna in the wireless communication terminal. For example, the disclosed embodiment can be used as the antenna for the wireless LANs, and the Bluetooth™. 
     Moreover, as shown in  FIG. 5  the grounding potential part  11  of the circuit board  10  occupies the most of the back surface of the circuit board  10 . However, the size of the antenna in the grounding potential part  11  can be varied according to the frequency band that the wireless communication terminal transmits or receives. For example, the area of the grounding potential part  11  can be smaller than the area of the grounding potential part  11  shown in  FIG. 5 , in order for the wireless communication terminal to transmit or receive the signals at a different frequency band. 
     Furthermore, the structure of circuit board  10 ,  20  and  30  and the arrangement configuration of battery  41 ,  42 ,  43 ,  44  shown in  FIG. 3  can be adjusted for different applications, such as other wearable computing services. 
     Thus, the foregoing discussion discloses and describes merely exemplary embodiments of the present invention. As will be understood by those skilled in the art, the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Accordingly, the disclosure of the present invention is intended to be illustrative, but not limiting of the scope of the invention, as well as other claims. The disclosure, including any readily discernible variants of the teachings herein, define, in part, the scope of the foregoing claim terminology such that no inventive subject matter is dedicated to the public.