Abstract:
An antenna unit and a computing system utilizing the antenna unit are disclosed. The antenna is compact and can be fabricated at low cost and with high accuracy. The antenna unit comprises an antenna and a connection cable. The antenna unit is constructed by forming the antenna and the connection cable integrally on a preferably flexible insulating film using preferably the FPC (Flexible Printed Circuit) technique. The computing system comprises a body having its main operational circuits and a hinged cover having a display. The flexible printed antenna is formed integrally with its module of electric components using the FPC technique and is made to span the body and the cover. The antenna itself and the connection cable can be freely bent or folded, resulting in higher freedom in their positioning within the computer system body and cover.

Description:
BACKGROUND OF INVENTION  
         [0001]    The present invention relates to an antenna unit comprising an antenna and a connection cable, and a computer system having such a unit, particularly to an antenna unit in which an FPC (Flexible Printed Circuit) technology can be suitably used and a computer system having such a unit.  
           [0002]    Some conventional computers, for example, notebook PCS (Personal Computers), have a built-in antenna for connection to a network or a peripheral equipment through a wireless LAN or a Bluetooth technique.  
           [0003]    [0003]FIG. 10 shows a configuration of an example of such a conventional antenna. In an example shown in FIG. 10, an inverted “F” antenna  101  has a radio wave resonator  102 , a ground  103 , and a connection conductor  104  for connecting the radio wave resonator  102  and the ground  103 . An antenna unit is constructed by connecting a signal line  106   a  of a coaxial cable  106  to a feeding point  105  of the radio wave resonator  102 , and a shield line  106   b  of the coaxial cable  106  to the ground  103 . In addition, a connector  107  is provided. Usually, the inverted “F” antenna  110  is made of several mm thick nickel silver in view of corrosion resistance. Standards IEEE 802.11b (2.45 GHz) and IEEE 802.11a (5.25 GHz) are applied to the wireless LAN, and the frequency of the Bluetooth specification is substantially same as the 2.45 GHz frequency of the IEEE 802.11b specification.  
           [0004]    In a communication apparatus as represented by a notebook PC for its requirement to be small and light weight, the apparatus needs to be as compact as possible to minimize the space where the antenna unit is usually mounted. However, in the above described conventional antenna unit, the antenna  101  should have a certain thickness because it is fabricated by stamping from nickel silver, and, the coaxial cable  106  is desired to be as thick as possible to eliminate its signal attenuation, and so a problem arises that an antenna unit cannot be made compact.  
           [0005]    In addition, because the frequencies used are as high as several GHz, when the signal line  106   a  of the coaxial cable  106  is connected to the feeding point  105 , for example, by soldering, a problem arises that the positional accuracy for connection should be held high. Thus, even if the position of connection for the signal line  106   a  to the feeding point  105  is offset from the target position by, for example, 0.1 mm, a resonant frequency is offset by about 10 MHZ.  
         SUMMARY OF INVENTION  
         [0006]    The present invention is directed to an antenna unit with a radio wave resonator and a connection cable. The antenna unit according to the present invention is integrally formed with the radio wave resonator and the connection cable on a preferably flexible insulating film utilizing preferably FPC techniques.  
           [0007]    In the present invention, by forming the radio wave resonator and the connection cable on the flexible insulating film preferably by etching, a thin, flat and flexible antenna unit can be obtained Therefore, when the antenna unit is mounted on an LCD panel which has little free space, it requires little space for mounting because of its flatness, and can be positioned in any location if it is flexible. Further, the radio wave resonator and the connection cable can be formed at one time with high accuracy because the radio wave resonator and the connection cable can be formed by etching which is known as a process to be simple and highly accurate.  
           [0008]    In a specific preferred example of the present invention, the connection cable comprises a signal line connected at least to a feeding point of a radio wave resonator, or a signal line connected to the feeding point of said radio wave resonator and two ground circuits provided on both sides of the signal line, and a shield material is provided between said signal line and two ground circuits on one or both of the upper and lower main surfaces of the signal line and the two ground circuits on both sides of the signal line, the shield material being a metal plated, metal powder deposited, or metal foil applied with or without unwoven or woven fabric. Specifically, when the ground circuits and the shield material are provided, a capability for preventing impact of an unnecessary electric wave, the same as for a conventional coaxial cable, can be imparted to a connection cable for the thin and flat antenna unit.  
           [0009]    In another specific preferred example of the present invention, the material used for the insulating film is PET (Polyethylene Telephthalate) or PEN (Polyethylene Naphthalate), or LCP (Liquid Crystal Polymer) and the insulating film of PET or PEN is 5-75 mm thick. In any case, both PET and PEN can attain further compactness of the antenna unit inexpensively because they are materials with high dielectric constant and they are inexpensive. In a further specific preferred example, a pair of radio wave resonator and connection cable are formed on the insulating film and the pair of the radio wave resonator and the connection cable are notched to make them bifurcated, the electric component of the radio wave resonator is integrally formed on the insulating film, and the radio wave resonator is of a structure supporting a plurality of frequencies. In any case, the antenna unit can be fully exploited. 
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0010]    Some of the purposes of the invention having been stated, others will appear as the description proceeds, when taken in connection with the accompanying drawings, in which:  
         [0011]    [0011]FIG. 1 is a view illustrating a configuration of an antenna unit according to the present invention;  
         [0012]    [0012]FIG. 2 is an enlarged view showing the antenna portion of the antenna unit shown in FIG. 1;  
         [0013]    FIGS.  3 ( a ) and ( b ) is a view illustrating a metal plated unwoven fabric used in a circuit requiring a shield as a preferred and example of the invention;  
         [0014]    FIGS.  4 ( a ) and ( b ) are views illustrating a front and back surface in the case where the unwoven fabric shown in FIGS.  3 ( a ) and ( b ) is applied to the antenna unit shown in FIG. 1;  
         [0015]    FIGS.  5 ( a )-( e ) are views successively illustrating respective layers from the front side to the back side in the antenna unit to which the unwoven fabric is applied;  
         [0016]    FIGS.  6 ( a )-( c ) are views illustrating a method connecting for the antenna unit  1  according to the present invention to the connector;  
         [0017]    [0017]FIG. 7 is a view illustrating an example of the antenna unit according to the present invention and electric functioned components of the antenna formed integrally;  
         [0018]    FIGS.  8 ( a )-( h ) are views illustrating an example of an arrangement of the antenna unit according to the present invention mounted on a notebook PC;  
         [0019]    [0019]FIG. 9 is a block diagram illustrating an example of an antenna unit according to the present invention having two antennas used as a diversity antenna; and  
         [0020]    [0020]FIG. 10 is a view illustrating an example of an example of a conventional antenna used as a diversity antenna. 
     
    
     DETAILED DESCRIPTION  
       [0021]    While the present invention will be described more fully hereinafter with reference to the accompanying drawings, in which a preferred embodiment of the present invention is shown, it is to be understood at the outset of the description which follows that persons of skill in the appropriate arts may modify the invention here described while still achieving the favorable results of this invention. Accordingly, the description which follows is to be understood as being a broad, teaching disclosure directed to persons of skill in the appropriate arts, and not as limiting upon the present invention.  
         [0022]    Referring now more particularly to the accompanying drawings, FIG. 1 is a view illustrating a configuration of an example of an antenna unit according to the present invention. In the example shown in FIG. 1 an antenna unit  1  is constructed using a FPC (Flexible Printed Circuit) technique. The antenna unit  1  is made of a flexible insulating film  2 , antennas  3  integrally formed on this insulating film  2 , and connection cables  4  connected to the antennas  3 . Because this example shows the antenna unit  1  having two integral antennas  3 , in one FPC having two antennas  3  and the connection cables  4  integrated thereon, a notch  5  is provided between two antennas  3  to make them bifurcated.  
         [0023]    As shown in FIG. 2, in an enlarged partial view, the antenna  3  takes a shape of inverted “F”, and is used to send and receive a wave of, for example, 2.45 GHz or 5.25 GHz used in IEEE 802.11b or IEEE 802.11a, standards for wireless LAN. The inverted “F” antenna  3  has a ground  11  and a radio wave resonator  12  formed on the insulating film  2 . The radio wave resonator  12  is dimensioned to have a length of λ/4 or λ/2 n  (where n=1, 2, 3, . . . ) when λ is the wavelength of a frequency targeted for sending and receiving, for example, 2.45 GHz. The radio wave resonator  12  has a feeding point  13 , the feeding point  13  being connected to an end of a signal line  14  formed on the insulating film  2 .  
         [0024]    The connection cable  4  is made by extensions  21  and  22  of the ground  11  and the radio wave resonator  12  of the antenna  3  on both sides of an extension  24  of the signal line  14  on the insulating film  2 . At an opposite end of the connection cable  4  to the antenna  3  side are provided terminals  31 ,  34  and  32  connected to the extension  21  of the ground  11 , the extension  24  of the signal line  14 , and the extension  22  of the radio wave resonator  12 .  
         [0025]    In the antenna unit  1  shown in FIG. 1, PET (Polyethylene Telephthalate) or a PEN (Polyethylene Naphthalate) or LCP is a preferable material to use for forming the insulating film  2 , particularly the most preferable being PEN. Both PET and PEN and LCP have a high dielectric constant compared with polyimide or the like which is used usually as the insulating film  2  in such antenna applications, and have thermal resistance sufficient for practical use at a temperature of about 200° C., they are favorable. In addition, when the insulating film  2  is formed of PET or PEN or LCP, the thin and flat antenna unit  1  according to the present invention cannot exhibit its effect if the thickness of insulating film  2  exceeds 5-75 μms and cannot be of high accuracy because of an edge factor if it is less than 5 μms.  
         [0026]    In the antenna unit  1  shown in FIG. 1, usually, the ground  11 , the radio wave resonator  12  and the signal line  14  of the antenna  3 , as well as the respective extensions  21 ,  22  and  24  of the ground  11 , the radio wave resonator  12  and the signal line  14  in the connection cable  4  can be formed on the insulating film  2  with high accuracy and simply by forming a conductive layer over either one of two main surfaces of the insulating film  2 , depositing a resist layer in a predetermined pattern on the conductive layer, and then performing a conventionally known chemical etching process.  
         [0027]    In the antenna unit  1  shown in FIG. 1, as a conductor for the ground  11 , the radio wave resonator  12  and the signal line  14  of the antenna  3  formed on the insulating film  2  and for their extensions  21 ,  22  and  24  in the connection cable  4  a rolled copper or a copper-plated foil is preferably used. Ni, Tin, Ag, Pb/Sn or Au (including each plating) may also be used. In addition, it is preferred to carry out an antirust treatment such as ENTEK (Trademark of SPRAYLAT Company) as a surface treatment of the antenna  3  and other circuits. In addition, it is also preferred to carry out a FLASH (gold) plating on the surface or terminal of the antenna  3  and other circuits.  
         [0028]    Moreover, in the antenna unit  1  above described, the antenna  3  has a single radio wave resonator  12 , and is configured to be able to send and receive only a single frequency, but it is possible to fabricate an antenna supporting a plurality of frequency zones as one antenna  3  by providing a plurality of radio wave resonators  12  of the antenna  3  corresponding to the frequencies. While in examples shown in FIGS. 1 and 2, the radio wave resonator  12  of the antenna  3  is formed on the insulating film, its both surfaces may be exposed as in a conventional antenna shown in FIG. 10. In addition, while an inverted “F” antenna is described as an example, antennas in various shapes such as a square-shaped slot antenna or an I-shaped rod antenna may be used to implement the present invention.  
         [0029]    Now, a preferred example of the antenna unit according to the present invention will be described. In an example it is constructed by applying a metal plated unwoven or woven fabric to one or both surfaces of the portions of the antenna unit  1  other than the functional parts of antenna  3  to prevent an unnecessary electromagnetic wave. Other than the metal plated unwoven or woven fabric, Kevlar (trade name) or a stainless steel mesh may be used. FIGS.  3 ( a ) and ( b ), respectively, show an example of unwoven fabric provided on the front and back surfaces of in the end opposite to the end provided with the antenna  3  and the ground  11  in the connection cable  4  on the insulating film  2 .  
         [0030]    In the examples shown in FIGS.  3 ( a ) and ( b ), both the metal plated unwoven fabric  41  on the back surface (FIG. 3( a )) and the metal plated unwoven fabric  42  on the front surface (FIG. 3( b )) are formed on the antenna unit  1  through the insulating film along the central portions in a longitudinal direction of the antenna unit  1  shown in FIG. 1. Each of the unwoven fabrics  41  and  42  has a notch  43  corresponding to the notch  5  of the antenna unit  1  of FIG. 1. In addition, each of the unwoven fabrics  41  and  42  has a plurality of blind holes  44  on its main surface. Each of the unwoven fabrics  41  and  42  is constructed by pouring and curing a conductive adhesive into the blind holes  44  in the extension  21  of the ground  11  connected to the ground in the connection cable  4  and the extension  22  of the radio wave resonator  12 .  
         [0031]    The blind holes  44  is provided in advance so as not to contact the extension  24  of the signal line  14 . Therefore the extension  24  of the signal line  14  in the connection cable  4  electrically shielded from the extension  21  of the ground  11  and the extension  22  of the radio wave resonator  12  on its both sides, and the unwoven fabrics  41  and  42  on the front and back surfaces. Thus, the connection cable  4  has the same functions as a conventional coaxial cable. FIGS.  4 ( a ) and ( b ) respectively show an example having unwoven fabrics  41  and  42  shown in FIGS.  3 ( a ) and ( b ) applied to the antenna unit  1  shown in FIG. 1, FIG. 4( a ) showing the front surface and FIG. 4( b ) showing the back surface. The pattern of the antenna  3  can be also seen in the back surface in FIG. 4( b ), because the insulating film  2  and its underlying insulating protective layer are substantially transparent.  
         [0032]    FIGS.  5 ( a )-( e ) successively show respective layers from the backside to the front side in the antenna unit having the unwoven fabrics applied thereto. The examples shown in FIGS.  5 ( a )-( e ) mainly show parts of the antenna  3 , FIG. 5( a ) showing the metal plated unwoven fabric  41 , FIG. 5( b ) showing the insulating protective layer  45 , FIG. 5( c ) showing the antenna unit  1  formed with the antenna  4  on the insulating film  2  and the conductive pattern in the connection cable  4 , FIG. 5 (d) showing the insulating protective layer  45 , and FIG. 5( e ) showing the metal plated unwoven fabric  42 . The antenna unit  1  can be obtained by laminating those layers shown in FIGS.  5 ( a )-( e ) through the blind holes  44  provided in the unwoven fabrics  41  and  42  by the conductive adhesive.  
         [0033]    FIGS.  6 ( a )-( c ) respectively show an example of a connection method for the antenna unit  1  and the connector. In the examples shown in FIGS.  6 ( a )-( c ), the connector  51  provided in a notebook PC or the like is made up of a connector body  52  having electrodes  61 ,  62  and  64 , a front cover  53  having a slot  65  and a protective cover  54  covering the electrodes  61 ,  62  and  64 . As shown in FIGS.  6 ( a )-( c ), the antenna unit  1  is connected to the connector  51  by inserting the terminals  21 ,  22  and  24  provided on the insulating film  2  at one end of the connection cable  4  directly through the slot  65  and electronically connecting the terminals  21 ,  22  and  24  respectively to the electrodes  61 ,  62  or  64 .  
         [0034]    [0034]FIG. 7 shows an example of the antenna unit according to the present invention formed integrally with various electrical components of the antenna. In the example shown in FIG. 7, in addition to antenna  1 , connectors  72 ,  73  and  74  are provided at locations which are integrally related by an LED interface (including a cable)  71 . Various electrical components could also be integrally provided in addition to the LED interface  71 , such as an inverter cable (including the cable), a keyboard light (including the cable) and a Bluetooth module (including the cable), as well as a filter chip, an IC and the like. In addition to connectors  72 ,  73  and  74  as previously discussed, a single edge type connector that directly fits in a terminal, for instance, or a card edge type connector, for example, may also be used.  
         [0035]    Since the antenna unit  1  according to the present invention is formed integrally with the module of electric components, using the FPC technique as described above, the antenna itself and the connection cable can be freely bent or folded, resulting in higher freedom in their positioning. FIGS.  8 ( a )-( h ) respectively show an example of an arrangement in which the antenna unit according to the present invention is mounted on a notebook PC. In the examples shown in FIGS.  8 ( a )-( h ), the notebook PC  81  comprises a body  82  with an operational section, a cover  84  with a display  83  and covering the body  82  in its closed position and a hinge member  85  interconnecting the body  82  and the cover  84  so that the cover  84  may slide between its closed position and its open position. Moreover, in the examples shown in FIGS.  8 ( a )-( h ), the body  82  and the cover  84  are shown in a perspective view so that the positions of the antenna unit  1  and the module  86  can be seen.  
         [0036]    In an example shown in FIG. 8( a ), two antenna units  1  are provided in the upper portions on both sides of the cover  84 , and the module  86  is provided on the body  82 . In an example shown in FIG. 8( b ), two antenna units  1  are provided in the lower end on both sides of the cover  84 , and the module  86  is provided on the body  82 . In an example shown in FIG. 8( c ), one antenna unit  1  is provided near the center of the cover  84 , and the module  86  is provided on the body  82 . In an example shown in FIG. 8( d ), one antenna unit  1  and the module  86  are provided on the body  82 . In an example shown in FIG. 8( e ), both two antenna units  1  and the module  86  are provided on the body  82 . In an example shown in FIG. 8( f ), one of two antenna units  1  is provided on an upper portion of the cover  84 , the other is provided on the body  82 , and the module  86  is provided on the body  82 . In an example shown in FIG. 8( g ), one antenna unit  1  is provided on a whole side of the cover  84 , and the module  86  is provided on the body  82 . In an example shown in FIG. 8( h ), one antenna unit  1  is provided on the periphery of the cover  84 , and module  86  is provided on the body  82 . As described above, the antenna unit  1  according to the present invention has high freedom for its positioning.  
         [0037]    While, in the examples shown in FIGS.  8 ( a )-( h ), the examples show the antenna unit  1  according to the present invention mounted on the notebook PC  81  to support the wireless LAN or Bluetooth, it is needless to say that use of the antenna unit  1  according to the present invention is not limited to the notebook PC  81 . For example, it can be applied to other equipment which may make communication such as a portable telephone, a home electronic appliance and an automobile.  
         [0038]    Now, an example of the antenna unit according to the present invention actually mounted on a transceiver will be described. FIG. 9 is a block diagram illustrating an example of the antenna unit  1  having two antennas used as a diversity antenna. In the example shown in FIG. 9, electric equipment with a PC card  91  comprises inverted “F” antennas  3   a  and  3   b  of the same structure as the inverted “F” antenna shown in FIGS. 1 and 2. These inverted “F” antennas  3   a  and  3   b  are positioned in different locations in the electric equipment on which they are mounted. The inverted “F” antennas  3   a  and  3   b  are connected to the PC card  91  through connection cables  4   a  and  4   b . In the connection cables  4   a  and  4   b , extensions  24   a  and  24   b  of the signal lines  14   a  and  14   b  are connected to a diversity controller  92  in the PC card  91 , and extensions  21   a  and  21   b , and  22   a  and  22   b  of respective grounds  11   a  and  11   b , and radio wave resonators  12   a  and  12   b  are connected to a ground  93  of the PC card  91 .  
         [0039]    The diversity controller  92  regularly detects which of two inverted “F” antennas  3   a  and  3   b  is better in sensitivity for reception and transmission, selects the inverted “F” antenna detected as to have a better from sensitivity for reception and transmission as an inverted “F” antenna to be used, and sends and receives the selected inverted “F” antenna and RF signals. First and second RF signal processors  94   a  and  94   b  are provided on the PC card  91  as corresponding to the frequencies of RF signals in first and second inverted “F” antennas respectively. A switch  95  connects the diversity controller  92  to the one corresponding presently used RF signal frequency of first and second RF signal processors  94   a  and  94   b . Each of the first and second RF processors  94   a  and  94   b  has a signal processor  96  and an amplifier  97 . The signal processor  96  convents an RF signal received as an electric wave in the inverted “F” antennas  3   a  and  3   b  to a predetermined signal, and generates an RF signal to be sent as an electric wave in the inverted “F” antennas  3   a  and  3   b . The amplifier  97  amplifies an RF signal to be outputted by the signal processor  96  and supplies the amplified RF signal to the switch  95 , amplifies an RF signal sent from the switch  95  and supplies the amplified RF signal to the signal processor  96 .  
         [0040]    In the drawings and specifications there has been set forth a preferred embodiment of the invention and, although specific terms are used, the description thus given uses terminology in a generic and descriptive sense only and not for purposes of limitation.