Patent Publication Number: US-7907093-B2

Title: Electronic device and method for manufacturing same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2007-151743, filed on Jun. 7, 2007; the entire contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to an electronic device and a method for manufacturing the same. 
     2. Background Art 
     An electronic device such as a mobile phone and a PDA (personal digital assistant) needs to include various types of antennas for voice communication as well as wireless LAN, television, radio, electronic payment, GPS, IC tag, and other communications. 
     In the case of an electronic device provided with such various types of antennas, the structure of connecting the antenna pattern on the casing outer surface to an on-board feed unit through a contact probe or a feed pin occupies a large installation space. This prevents the downsizing of the electronic device. 
     JP-A 2001-111321 (Kokai) discloses a feeding structure in which an antenna is placed inside the casing of a communication terminal apparatus and part of the antenna is directly in contact with an on-board feed unit. 
     SUMMARY OF THE INVENTION 
     According to an aspect of the invention, there is provided an electronic device comprising: a first molded body having a first frame, the first molded body being provided with a conductive pattern on its outer surface; a second molded body having a second frame, the second molded body being joined to the first molded body; a wiring sheet made of an insulative sheet provided with an interconnection pattern; a circuit board having a feed point; and a feed line having a first end extended to a mating surface of the first frame opposed to the second frame and a second end connected to the conductive pattern, the interconnection pattern having a first end connected to the one end of the feed line, and the interconnection pattern having a second end connected to the feed point. 
     According to another aspect of the invention, there is provided a method for manufacturing an electronic device, the electronic device including: a first molded body having a first frame, the first molded body being provided with a conductive pattern on its outer surface; a second molded body having a second frame, the second molded body being joined to the first molded body; a wiring sheet made of an insulative sheet provided with an interconnection pattern; a circuit board having a feed point; and a feed line having a first end extended to a mating surface of the first frame opposed to the second frame and a second end connected to the conductive pattern, the interconnection pattern having a first end connected to the one end of the feed line, the interconnection pattern having a second end connected to the feed point, the circuit board being bonded to the first molded body or the second molded body, and the wiring sheet having a first end sandwiched between the first and second frame, the second molded body being provided with a positioning rib, and the wiring sheet being provided with a notch engaged with the positioning rib, the method including: engaging the notch with the positioning rib; bonding the circuit board to the first or second molded body; and fixing the wiring sheet so that the wiring sheet is sandwiched between the first and second molded body. 
     According to another aspect of the invention, there is provided a method for manufacturing an electronic device, the electronic device including: a first molded body having a first frame, the first molded body being provided with a conductive pattern on its outer surface; a second molded body having a second frame, the second molded body being joined to the first molded body; a wiring sheet made of an insulative sheet provided with an interconnection pattern; a circuit board having a feed point; and a feed line having a first end extended to a mating surface of the first frame opposed to the second frame and a second end connected to the conductive pattern, the interconnection pattern having a first end connected to the one end of the feed line, and the interconnection pattern having a second end connected to the feed point, the second molded body is provided with a positioning rib, and the wiring sheet is provided with a notch engaged with the positioning rib, the method including: engaging the notch with the positioning rib; and fixing a second end of the wiring sheet and the circuit board so that a second end of the wiring sheet and the circuit board are sandwiched between the first and second pressing rib and that a first end of the wiring sheet is sandwiched between the first and second molded body. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A to 1D  are schematic views showing the configuration of an electronic device according to an embodiment of the invention; 
         FIGS. 2A and 2B  are schematic partial cross-sectional views of the electronic device of  FIG. 1 ; 
         FIG. 3  is a flow chart showing a process for manufacturing the electronic device of  FIG. 1 ; 
         FIGS. 4A and 4B  are schematic partial cross-sectional views of a variation of the mating surface; 
         FIGS. 5A to 5D  are views showing the configuration of the antenna; and 
         FIGS. 6A and 6B  are schematic partial cross-sectional views showing a variation of this embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Embodiments of the invention will now be described with reference to the drawings. 
       FIG. 1  includes schematic views showing the configuration of an electronic device according to an embodiment of the invention. The electronic device of  FIG. 1  is illustratively a mobile phone or a PDA, and includes a folding or sliding structure.  FIG. 1A  shows a first molded body  10 ,  FIG. 1B  shows a circuit board  30 ,  FIG. 1C  shows a wiring sheet  40 , and  FIG. 1D  shows a second molded body  20 . 
     In this embodiment, one end of the wiring sheet  40  is sandwiched between the first molded body  10  and the second molded body  20 . The other end of the wiring sheet  40  and a feed point  32  of the circuit board, in electrical contact with each other, are sandwiched between the pressing ribs constituting the first and second molded body  10 ,  20 . The first and second molded body  10 ,  20  include resin, for example. In  FIG. 5C , while the wiring sheet  40  has an opening  41  having a closed periphery, the wiring sheet  40  can alternatively be U-shaped, for example. 
     The first and second molded body  10 ,  20  are securely joined together to constitute one of the casings of a folding or sliding electronic device. This casing is to include a liquid crystal display, for example, and the other casing is to include a keyboard, a secondary battery, and a circuit board. 
       FIG. 2  shows cross-sectional views of the casing, where  FIG. 2A  is a partial schematic cross-sectional view taken along the dot-dashed line AA of  FIG. 1C , and  FIG. 2B  is a partial enlarged schematic cross-sectional view in the portion P of  FIG. 2A  for illustrating the mating surfaces of the first and second molded body. In the following, the structure of this embodiment is described in more detail with reference to  FIGS. 1 and 2 . As shown in  FIGS. 1A and 2 , a conductive pattern  12  such as an antenna is formed by printing, painting, or plating on the outer surface  11  of the first molded body  10  illustratively made of resin. In  FIG. 1 , two conductive patterns  12   a  and  12   b  serving as antennas are formed. 
     The first molded body  10  has a first frame  10   a , which presses the wiring sheet  40  from above at a feed line  14  on the surface  10   b  of the frame  10   a . Furthermore, the first molded body  10  has a pressing rib  10   d  inside, which presses the circuit board  30  from above. 
     The second molded body  20  has a second frame  20   a , which presses the wiring sheet  40  from below at the surface  20   b  of the frame  20   a . Furthermore, the second molded body  20  has a pressing rib  20   d  inside, which presses the wiring sheet  40  and the circuit board  30  having the feed point  32  from below. 
     Furthermore, the feed line  14  extends from its one end located on the surface  10   b  of the frame  10   a  through a stepped surface  10   c  and the outer surface of the frame  10   a  to the other end connected to the conductive pattern  12 . 
     As shown in  FIG. 1B , the circuit board  30  is provided with a feed point  32  connected to the on-board circuit component. The feed point  32  is connected to the conductive pattern  12  through an interconnection pattern  44  of the wiring sheet  40  and the feed line  14 . 
     Next, a method for manufacturing an electronic device of this embodiment is described with reference to a flow chart shown in  FIG. 3 . First, an interconnection pattern  44  is formed on the surface of an insulative sheet by printing, painting, or plating to serve as a wiring sheet (S 100 ). Subsequently, as shown in  FIG. 1C , the wiring sheet  40  provided with a notch  42  is aligned with a positioning rib  20   e  provided inside a second molded body  20  and is placed on the second molded body  20  (S 102 ). 
     Subsequently, alignment is performed so that a feed point  32  provided on a circuit board  30  is connected to the other end of the interconnection pattern  44  provided on the wiring sheet  40 , and the circuit board  30  is placed on the second molded body  20  via the wiring sheet  40  (S 104 ). 
     Furthermore, the first and second molded body  10 ,  20  are aligned so as to sandwich the wiring sheet  40  and the circuit board  30  (S 106 ), and fixed together (S 108 ). Here, the first frame  10   a  includes a projected surface  10   b  and a surface  10   c  stepped therefrom. The second frame  20   a  includes a depressed surface  20   b  and a surface  20   c  stepped therefrom. The surface  10   b  is opposed to the surface  20   b , and the surface  10   c  is opposed to the surface  20   c , each serving as a mating surface. The feed line  14  extending on the surface  10   b  makes electrical contact with the interconnection pattern  44 . 
     Next, a variation of the mating surface is described.  FIG. 4  is a schematic partial cross-sectional view of the variation of the mating surface.  FIG. 4A  shows the case where the frame  10   a  of the first molded body  10  provided with a conductive pattern  12  and a feed line  14  has a depressed surface  10   b . The frame  20   a  of the second molded body  20  also has a mating surface opposed thereto.  FIG. 4B  shows the case where the surface  10   b  and the surface  20   b  constituting the mating surfaces are flat. In this case, although the side surface of the wiring sheet  40  is exposed outside, the structure can be simplified. 
     The other end of the interconnection pattern  44  and the feed point  32  of the circuit board  30  are vertically sandwiched between the pressing ribs  10   d  and  20   d  to make electrical connection. Here, if the wiring sheet  40  is provided with an opening  41  as shown in  FIG. 1C , multiple feed points  32  can be provided on the periphery of the circuit board  30 . In the case where multiple feed points  32  are provided, positional precision can be favorably maintained by using a positioning rib  10   e  and a notch  42  as described above. It is noted that the circuit board  30  may be fixed by bonding, for example, without being sandwiched between pressing ribs  10   d  and  20   d , and the feed point  32  may be electrically connected to the other end of the interconnection pattern  44 . 
     According to this embodiment, a conductive pattern  12  such as an antenna provided on the outer surface  11  of the casing is connected to the circuit board  30  through the feed line  14  and the wiring sheet  40  provided on the surface of the molded body. Consequently, space for connection can be reduced as compared with connections based on a contact probe or a feed pin. 
     Here, a description is given of the antenna.  FIG. 5  shows the configuration of the antenna.  FIG. 5A  shows a dipole antenna. The antenna pattern  12  has a length of approximately a half wavelength (λg/2) and is excited at its middle portion by a feeder unit  50 . 
       FIG. 5B  shows a monopole antenna. The antenna pattern  12  has a length of approximately a quarter wavelength (λg/4). It can be treated similarly to a half-wavelength antenna by considering a mirror image with respect to a ground plane  52  as represented by the dashed line. 
       FIG. 5C  shows a folded dipole antenna, allowing high radiation efficiency based on high impedance. 
       FIG. 5D  shows an inverted-F antenna having a plate-like element  12   a , which has a perimeter length of approximately a half wavelength. In this case, because the antenna excites the casing and passes a current therethrough, the effective size of the antenna can be increased. 
     In the case where a plurality of antennas selected from many antennas including those illustrated in  FIG. 5  are placed on the outer surface  11  as shown in  FIG. 1A , multi-band operation is facilitated by this embodiment, in which the connection space is easily reduced. More specifically, transmitting and receiving operations can be extended to the mobile phone triple band including GSM (Global System for Mobile communications), DCS (Digital Cellular System), and PCS (Personal Communications Service), as well as wireless LAN, FM and AM broadcasting, GPS (global positioning system), terrestrial digital broadcasting called One Seg, and electronic payment such as Felica™ and SUICA™. 
       FIG. 6  is a schematic view showing a variation of this embodiment, where  FIG. 6A  is a schematic perspective view of a wiring sheet  40 , and  FIG. 6B  is a partial schematic cross-sectional view of the electronic device taken along the dot-dashed line AA. The wiring sheet  40  of this variation has an interconnection pattern  45  that is made of a thin metal plate bent at 90 degrees. The interconnection pattern  45  is laminated between resin or other insulative sheets. The end bent at 90 degrees is sandwiched between the first and second frames  10   a ,  20   a  and connected to the feed line  14  at the portion W represented by the dashed line in  FIG. 6B . This variation can also provide an electronic device having the same advantageous effect as the embodiment of  FIG. 1 . 
     The embodiments of the invention have been described with reference to the drawings. However, the invention is not limited to these embodiments. The shape, size, material, and arrangement of the molded body, circuit board, and wiring sheet constituting the electronic device, and the method for manufacturing the same, can be variously modified by those skilled in the art without departing from the spirit of the invention, and such modifications are also encompassed within the scope of the invention.