Abstract:
A near field communication (NFC) system and an associated apparatus are provided. The NFC system includes a display device, a host computer, at least one RF module coupled to the host computer, a plurality of antennas coupled to the at least one RF module, and a NFC device. The antennas are disposed behind the display device. The NFC device is for communicating with the host computer via one of the antennas. The NFC system can upgrade communication quality and achieve multi-tasking efficiency.

Description:
BACKGROUND OF INVENTION 
     1. Field of the Invention 
     The present invention relates to near field communication (NFC), and more particularly to a NFC system having a plurality of antennas and an associated apparatus. 
     2. Description of the Prior Art 
     Near field communication (NFC) technology is designed for short distance wireless communication and now is widely applied to our daily life. For example, the contact-less radio frequency identification (RFID) card has been applied to the public transportation tickets and the credit card transactions. The NFC technology performs data transmission through inductive coupling. Take a passive (i.e. powerless in itself) RFID card or RFID tag as example: there are coil antennas inside the RFID card and the card reader; the card reader generates an alternating magnetic field by its coil antenna, and the coil antenna of the RFID card inductively couples the alternating magnetic field to generate the electric power required for operation of the circuit within the RFID card. The communication between the RFID card and the card reader is performed by using carriers of high frequency (HF, such as 13.56 MHz) or low frequency (LF, such as 125 KHz) in the spectrum. The RFID card can backscatter its data to the card reader. The card reader can transmits data to the RFID card so as to write the data into the RFID card. In addition to the card reader and the passive RFID card, the near field communication can also be performed by two transceivers. After one transceiver transmits data, the other transceiver makes a reply in a predefined format. For example, two cell phones can transmit data to each other by means of the NFC technology. 
     In prior arts, an application is developed by using the NFC technology to enable the wireless communication between a computer and a RFID card or cell phone. The coil antenna used for the near field communication is wound around a display panel. When a user moves the RFID card or cell phone close to the display panel wound with the coil antenna, the RFID card or cell phone can be inductively coupled to a RF module connected to the coil antenna, so as to transmit data to the RF module, which then transmits the data to the computer so as to display the data on the display panel.  FIG. 1  and  FIG. 2  show a vertical view and a lateral view of an example of this application. When two cell phones  15 , 16  (or RFID cards) approach a touch sensitive display panel  11 , a RF module  13  is inductively coupled to the cell phone  15 , 16  by an alternating magnetic field (shown as the magnetic power lines) generated by an antenna  12 . The user can operate the touch sensitive display panel  11  to instruct a host computer  14  to transmit the data of the cell phone  15  to the cell phone  16 . Therefore, after the RF module  13  and the cell phone  15  finish handshaking, the cell phone  15  transmits its data to the host computer  14  via the RF module  13 ; after the RF module  13  and the cell phone  16  finish handshaking, the host computer  14  sends the data to the cell phone  16  via the RF module  13 . 
     However, in the above application, the antenna  12  is wound around the touch sensitive display panel  11 . Thus, when the touch sensitive display panel  11  and the wound antenna  12  become larger, the area of the coil antennas within the cell phones  15 , 16  (or RFID cards) become smaller in comparison with the area of the antenna  12 , and thus the number of the magnetic power lines which can be captured by the cell phones  15 , 16  is relatively decreased such that the magnetic field intensity is weakened. In order to enable the cell phone  15 , 16  to capture enough magnetic field intensity required for communication, the RF module  13  and the antenna  12  must supply more power such as increasing the current passing through the antenna  12  or the number of coils of the antenna  12  so as to generate higher magnetic field intensity. However, this would cause the interference between the electronic components in the touch sensitive display panel  11  and the near field communication, and thus the quality degradation of both display and wireless communication. On the other hand, since the area of the antennas in the cell phones  15 , 16  becomes relatively smaller against the area of the antenna, the coupling coefficient becomes smaller consequently. This would also degrade the communication quality. 
     Moreover, in the above application, if multiple cell phones or RFID cards are to communicate with each other via the host computer  14  simultaneously, multitasking efficiency is hard to achieve since the host computer  14  can communicate with the cell phones or RFID cards via only one antenna  12 . 
     SUMMARY OF INVENTION 
     It is therefore one objective of the present invention to provide a NFC system to upgrade near field communication quality. 
     Another objective of the present invention is to provide a NFC system having multiple antennas, so as to achieve multi-tasking efficiency unavailable in prior arts. 
     Another objective of the present invention is to provide an apparatus which can integrate multiple NFC antennas behind a display panel without influencing display quality. 
     A NFC system provided by the present invention comprises: a display device; a host computer coupled to the display device; at least one radio frequency (RF) module coupled to the host computer; a plurality of antennas disposed behind the display device, wherein the plurality of antennas are coupled to the at least one RF module; and a first NFC device, for communicating with the host computer via a first antenna of the antennas. 
     An apparatus integrating NFC antennas is provided. The display device, coupled to a host computer, comprises: a display panel; and a plurality of circular antennas disposed behind the display panel, wherein the plurality of circular antennas are coupled to at least one radio frequency (RF) module coupled to the host computer. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  and  FIG. 2  respectively show a vertical view and a lateral view of a practical application of NFC technology. 
         FIG. 3  and  FIG. 4  respectively show a vertical view and a lateral view of a NFC system according to an embodiment of the present invention. 
         FIG. 5  and  FIG. 6  are diagrams respectively showing two different embodiments of the data transmission between the first and second NFC devices of  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 3  and  FIG. 4  respectively show a vertical view and a lateral view of a NFC system  30  according to an embodiment of the present invention. The NFC system  30  comprises a touch sensitive display  31  (including a display panel), a plurality of circular antennas  321 ˜ 326 , a plurality of RF modules  331 ˜ 336 , a host computer  34 , a first NFC device  35  and a second NFC device  36 . In  FIG. 3  and  FIG. 4 , the first NFC device  35  and the second NFC device  36  are shown as cell phones, while the first NFC device  35  and the second NFC device  36  can also be other portable electronic devices with NFC capability such as RFID cards, digital cameras, personal digital assistants (PDA), MP3 players, etc. The first NFC device  35  and the second NFC device  36  can be active or passive devices. The active device such as a cell phone has its own power source, while the passive device such as a RFID card does not have. Besides, the number of circular antennas is not limited to six as shown in  FIG. 3 . The circular antennas  321 ˜ 326  can be coil antennas. The touch sensitive display  31  of the NFC system  30  is just an embodiment of the present invention, and other types of display panels, such as LCD panel, plasma panel and OLED panel, can also be applied to the NFC system of the present invention. 
     The circular antennas  321 ˜ 326  are disposed behind the touch sensitive display  31  (or behind the display panel of the touch sensitive display  31 ) in an array form. Each of the circular antennas  321 ˜ 326  is coupled to a corresponding RF module, that is, the circular antenna  321  is coupled to the RF module  331 , the circular antenna  322  is coupled to the RF module  332  . . . and the circular antenna  326  is coupled to the RF module  336 . The magnetic field range formed by the circular antennas  321 ˜ 326  covers the touch sensitive display  31 , such that the first NFC device  35  and the second NFC device  36  can couple to one of the circular antennas  321 ˜ 326  when they approach any position on the surface of the touch display panel  31 . The RF modules  331 ˜ 336  and the host computer  34  are all coupled to a bus  37 . For example, the RF modules  331 ˜ 336  can be coupled to a transmission interface (e.g. USB, RS232) of the host computer  34  or a bus connected to the host computer  34  (e.g. I 2 C, RS485). In one embodiment, each of the RF modules  331 ˜ 336  has a corresponding identification code for communicating with the host computer  34  and other RF modules. In another embodiment, the number of circular antennas is not equal to that of RF modules. That is, multiple circular antennas may share one RF module, e.g. every three circular antennas share one RF module. Additionally, the RF modules  331 ˜ 336  can be integrated within the host computer  34 . 
     When the first NFC device  35  approach the surface of the touch sensitive display  31 , the first NFC device  35  is inductively coupled to one of the circular antennas  321 ˜ 326 . For example, as shown in  FIG. 3 , the first NFC device  35  is inductively coupled to the circular antenna  321 . Next, the first NFC device  35  transmits a first data stored in itself to the host computer  34  via the circular antenna  321  and the RF module  331  coupled to the circular antenna  321 , and then the host computer  34  displays the first data on the touch sensitive display  31 . Besides, if the touch sensitive display  31  displays a second data stored in the host computer  34  and a user touches the touch sensitive display  31  to instruct the host computer  34  to transmit the second data to the first NFC device  35 , then the host computer  34  transmits the second data to the first NFC device  35  via the RF module  331  and the circular antenna  321 . The first data and the second data can be pictures or various kinds of files. In another embodiment, the user can also use a mouse or keyboard (not shown) to instruct the host computer  34  to perform data communication between the first NFC device  35  and the host computer  34 . 
     As shown in  FIG. 3 , the second NFC device  36  is inductively coupled to the circular antenna  326 . When the user operates the touch sensitive display  31  to instruct the host computer  34  to transmit the first data to the second NFC device  36 , the first data stored in the NFC device  35  is transmitted to the second NFC device  36  successively via the circular antenna  321 , the RF module  331 , the host computer  34 , the RF module  336  and the circular antenna  326 , as shown in  FIG. 5 . 
     In another embodiment, the RF modules  331 ˜ 336  are mutually coupled, and therefore the RF modules  331 ˜ 336  can transmit data with each other. When the user operates the touch sensitive display  31  to instruct the host computer  34  to transmit the first data to the second NFC device  36 , the host computer  34  instructs the RF module  331  to directly transmit the first data to the RF module  336  without passing the host computer. Thus, the first data stored in the NFC device  35  is transmitted to the second NFC device  36  successively via the circular antenna  321 , the RF module  331 , the RF module  336  and the circular antenna  326  as shown in  FIG. 6 , wherein the solid arrows represent the transmission path of the first data, while the dotted arrows represent the instructions that the host computer  34  issues to the RF modules  331  and  336 . 
     In  FIG. 3  and  FIG. 4 , by means of setting multiple circular antennas behind the display in the array form, the area of each circular antenna can be reduced, so as to increase the coupling coefficient between the circular antenna and the NFC device and thus upgrade communication quality. Furthermore, the circular antenna with a smaller area can avoid the problem of the prior arts that the communication can only be enabled by increasing the current or the number of coils to upgrade the magnetic field intensity. Thus, the circular antenna with a smaller area can also lower the interference between the circular antenna and the display panel. Besides, when more than two NFC devices are to communicate with each other, the NFC system  30  can enable its multiple circular antennas to perform data transceiving simultaneously, so as to achieve multitasking effect and thus upgrade communication efficiency. 
     While the present invention has been shown and described with reference to the preferred embodiments thereof and in terms of the illustrative drawings, it should not be considered as limited thereby. Various possible modifications and alterations could be conceived of by persons skilled without departing from the scope and the spirit of the present invention.