Patent Publication Number: US-7583227-B2

Title: Electronic device with built-in antenna

Description:
TECHNICAL FIELD 
     The present invention relates to an electronic device with a built-in antenna that has an antenna substrate and a waveguide substrate in a housing. 
     BACKGROUND ART 
     Conventional electronic devices with a built-in antenna have an antenna unit in a housing. For example, such an electronic device with a built-in antenna is a main device of a radio communication system used in a restaurant. For example, the antenna unit in the housing is composed of an antenna substrate on which an antenna pattern is formed. Such an antenna is disclosed in Japanese Patent Laid-Open No. 2001-345621. 
     A variety of electronic devices with a built-in antenna have already been put into practical use. Among these, an electronic device incorporates an antenna unit having an antenna substrate and a waveguide substrate. In this case, the antenna substrate and the waveguide substrate have to be in a predetermined positional relationship and make a predetermined angle with each other. Therefore, typically, the antenna substrate and the waveguide substrate are fixed to each other with a metal plate bracket. 
     As described above, in the conventional electronic device with a built-in antenna, the antenna substrate and the waveguide substrate are fixed to each other with a metal plate bracket. Therefore, the metal plate bracket has an effect on the coverage of the antenna and thus the performance of the antenna. 
     DISCLOSURE OF THE INVENTION 
     The present invention has been devised in view of such circumstances. An object of the present invention is to provide an electronic device with a built-in antenna the performance of which is improved because an antenna substrate and a waveguide substrate are fixed to each other without using a metal plate bracket. 
     An electronic device with a built-in antenna according to the present invention comprises: a housing; and an antenna substrate and a waveguide substrate both incorporated in the housing, in which one of the antenna substrate and the waveguide substrate is fixed to an attachment part in the housing, the other substrate is disposed adjacent to the one substrate and in a standing position on the attachment part, the one substrate has an insert on an edge thereof, the other substrate has a slit formed therein along the edge of the one substrate, and the insert is inserted into the slit. 
     Another aspect of the present invention is an antenna unit. The antenna unit comprises: an antenna substrate; and a waveguide substrate coupled to the antenna substrate, in which one of the antenna substrate and the waveguide substrate is fixed to an attachment part in a housing, the other substrate is disposed adjacent to the one substrate and in a standing position on the attachment part, the one substrate has an insert on an edge thereof, the other substrate has a slit formed therein along the edge of the one substrate, and the insert is inserted into the slit. Any device can be provided with the antenna unit. 
     According to another aspect of the present invention, there is provided a device with a built-in antenna comprising: a housing; and a first substrate and a second substrate both incorporated in the housing, in which the first substrate is fixed to an attachment part in the housing, the second substrate is disposed adjacent to the first substrate and in a standing position on the attachment part, the first substrate has an insert on an edge thereof, the second substrate has a slit formed therein along the edge of the first substrate, and the insert is inserted into the slit. The first substrate and the second substrate maybe a waveguide substrate and an antenna substrate but are not limited thereto. 
     As can be seen from the following description, the present invention has various other aspects. Thus, the disclosure of the present invention herein is intended to illustrate only some aspects of the present invention but not to limit the scope of the present invention described and claimed herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram showing an electronic device with a built-in antenna according to an embodiment of the present invention; 
         FIG. 2  is a perspective view of a waveguide substrate and an antenna substrate coupled to each other; 
         FIG. 3  is a perspective view of the waveguide substrate and the antenna substrate separated from each other; 
         FIG. 4  is a diagram showing the waveguide substrate; 
         FIG. 5  is a diagram showing the antenna substrate; 
         FIG. 6  is a front view of the electronic device with a built-in antenna; and 
         FIG. 7  is a rear view of the electronic device with a built-in antenna. 
     
    
    
     DESCRIPTION OF SYMBOLS 
     
         
           1  electronic device with built-in antenna 
           3  main unit case 
           7  antenna unit 
           9  attachment part 
           11  waveguide substrate 
           13  antenna substrate 
           33  insert 
           35  engaging hook 
           37  slit 
           55  holding groove 
       
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     In the following, the present invention will be described in detail. However, it is to be noted that the following detailed description and the accompanying drawings are not intended to limit the scope of the present invention. Instead, the scope of the present invention is defined by the accompanying claims. 
     An electronic device with a built-in antenna according to the present invention comprises: a housing; and an antenna substrate and a waveguide substrate both incorporated in the housing, in which one of the antenna substrate and the waveguide substrate is fixed to an attachment part in the housing, the other substrate is disposed adjacent to the one substrate and in a standing position on the attachment part, the one substrate has an insert on an edge thereof, the other substrate has a slit formed therein along the edge of the one substrate, and the insert is inserted into the slit. 
     In this arrangement, one of the substrates is fixed to the attachment part, and the other substrate is disposed in a standing position on the attachment part. In addition, the insert on the one substrate is inserted into the slit in the other substrate. Thus, the one substrate restricts the movement of the other substrate. Therefore, the substrates can be integrally assembled to the housing without using a metal plate bracket to couple the substrates to each other. 
     In addition, the housing may have holding grooves extending in a direction away from the attachment part, and opposite edges of the other substrate may be inserted in the holding grooves. In this arrangement, the edges of the other substrate can be held by the holding grooves, so that the other substrate can be prevented from shaking. Furthermore, the holding grooves can suitably serve as guide grooves during assembly. 
     In addition, the insert on the one substrate may have an engaging hook for engaging with the slit in the other substrate. In this arrangement, the insert on the one substrate is hard to be disengaged from the slit in the other substrate, and thus the substrates are appropriately fixed to the attachment part. 
     In addition, the one substrate may have a first protrusion that is aligned with the insert and protrudes from the edge, the other substrate may have a second slit aligned with the slit and a second protrusion extending from the edge of the second slit to the inside of the second slit, and the second protrusion on the other substrate may be disposed at such a position that the second protrusion restricts the movement of the first protrusion on the one substrate in such a direction that the engaging hook is disengaged. In this arrangement, the substrates are temporarily fixed to each other before the substrates are attached to the housing. Therefore, the substrates can be easily assembled to the housing. 
     The one substrate may be the waveguide substrate, and the other substrate may be the antenna substrate. This arrangement will be described below as an embodiment of the present invention. Alternatively, the one substrate may be the antenna substrate, and the other substrate may be the waveguide substrate. 
     As described above, according to the present invention, one of the antenna substrate and the waveguide substrate has an insert, the other has a slit, and these elements are used to couple the substrates to each other. Any metal-plate coupling bracket is not needed. Thus, the antenna performance is improved. 
     In the following, an electronic device with a built-in antenna (referred to simply as electronic device hereinafter) according to an embodiment of the present invention will be described with reference to the drawings. In the following description, the appearance of the electronic device will be first mentioned with reference to  FIGS. 6 and 7 , and then an antenna unit incorporated in the electronic device will be mentioned with reference to  FIGS. 1 to 5 . 
       FIGS. 6 and 7  show the appearance of the electronic device according to this embodiment.  FIGS. 6 and 7  are perspective views of the electronic device seen from the front and the rear, respectively. In this embodiment, the electronic device is a main device of a radio communication system used in a restaurant or the like. An electronic device  1  has a main unit case  3  serving as a housing. An external antenna  5  protrudes upward from the main unit case  3 . In addition to the external antenna  5 , another antenna unit is housed in the main unit case  3 . 
       FIG. 1  is a perspective view of the inside of the main unit case  3  seen from the rear of the main unit case  3 . The main unit case  3  is made of resin and formed by molding. 
     A built-in antenna unit  7  is fixed to an attachment part  9  in the main unit case  3 . The attachment part  9  is constituted by the bottom surface of a laterally or horizontally elongated hollow formed in the middle and in the upper space of the main unit case  3 . 
     The antenna unit  7  is composed of a waveguide substrate  11  (waveguide) and an antenna substrate  13 . Two screws  15  pass through the waveguide substrate  11  and are fitted into bosses  17  on the attachment part  9 . In this way, the waveguide substrate  11  is fixed to the attachment part  9 . The antenna substrate  13 , which is coupled to the waveguide substrate  11 , abuts against the waveguide substrate  11  in a standing position on the attachment part  9 . More specifically, the attachment part  9  is constituted by a substantially vertical wall. The waveguide substrate  11  is fixed to and along the wall, so that the waveguide substrate  11  is substantially in parallel with the wall. The antenna substrate  13  stands on the wall of the attachment part  9  substantially vertically. As a result, the antenna substrate  13  is substantially in parallel with the horizontal plane. 
       FIGS. 2 to 5  show the antenna unit  7 .  FIGS. 2 and 3  show the antenna unit  7  coupled to each other and separated from each other, respectively.  FIG. 4  shows the waveguide substrate  11 , and  FIG. 5  shows the antenna substrate  13 . 
     As shown in these drawings, the waveguide substrate  11  and the antenna substrate  13  have an elongated rectangular shape. Both the substrates are made of epoxy or glass, for example. The substrates may be made of different materials. Furthermore, according to this embodiment, the substrates make a right angle with each other. 
     The waveguide substrate  11  has a waveguide pattern  21  formed on one side thereof. As shown, the waveguide pattern  21  includes a plurality of bends and extends in a zigzag manner with respect to the longitudinal direction. Screw holes  23  are formed spaced apart from the waveguide pattern  21 . On the other hand, the antenna substrate  13  has a linear antenna pattern  25 . The antenna pattern  25  is bent at one end thereof, and a connector  27  is attached to the tip of the bent end. The connector  27  is connected to a substrate in the main unit case  3  (not shown). 
     The waveguide substrate  11  is in contact with the antenna substrate  13  at an edge  31 . Two inserts  33  are formed on the edge  31 . The inserts  33  are protrusions extending outward from the edge  31  along the substrate surface. The two inserts  33  are spaced apart from each other in the longitudinal direction. More specifically, the two inserts  33  are formed near the opposite ends of the waveguide substrate  11 , respectively. 
     Each insert  33  has an engaging hook  35 . The engaging hook  35  is a part of the insert  33  protruding therefrom along the edge  31 . The engaging hook  35  is substantially in parallel with the edge  31 . The two engaging hooks  35  protrude in the same direction from the respective inserts  33 . 
     The antenna substrate  13  has one slit  37  for each of the inserts  33  on the waveguide substrate  11  described above. Two slits  37  are formed at positions corresponding to those of the inserts  33 . The inserts  33  are inserted into the slits  37 . In this way, the antenna substrate  13  is coupled to the waveguide substrate  11 . 
     In addition, the engaging hooks  35  of the inserts  33  are engaged with the slits  37  in the antenna substrate  13 . More specifically, when the inserts  33  are inserted into the slits  37 , the waveguide substrate  11  is slid with respect to the antenna substrate  13 . This makes the engaging hooks  35  engage with the ends of the slits  37  in the antenna substrate  13 . 
     In addition, the waveguide substrate  11  has a protrusion  41  (a first protrusion) that is aligned with the inserts  33  and protrudes outwardly from the edge  31 . The protrusion  41  is formed midway between the two inserts  33  and substantially at the middle of the substrate. 
     On the other hand, the antenna substrate  13  has another slit  43  (a second slit with a protrusion or an auxiliary slit with a protrusion) at the position corresponding to the projection on the waveguide substrate  11 . A protrusion  45  (a second protrusion) extends from the edge of the slit  43  toward the inside of the slit  43 . 
     The protrusion  45  on the antenna substrate  13  is disposed to restrict or limit the movement of the waveguide substrate  11  in such a direction that the engaging hooks  35  are disengaged from the antenna substrate  13  as described below. 
     If the waveguide substrate  11  is slid with respect to the antenna substrate  13  in the removal direction that is opposite to the sliding direction at the time of assembly, the engaging hooks  35  are removed from the antenna substrate  13 . To prevent the removal, the protrusion  45  on the antenna substrate  13  is located forward of the protrusion  41  on the waveguide substrate  11  along the removal direction described above. As a result, if the waveguide substrate  11  is to slide in the removal direction (in such a direction that the hooks are removed from the antenna substrate), the protrusion  41  on the waveguide substrate  11  comes into contact with the protrusion  45  on the antenna substrate  13  and is prevented from moving further. This feature is advantageous during assembly as described later. During assembly, the protrusions can be used to temporarily secure the substrates to each other. 
     In the arrangement described above, after the substrates are coupled to each other, the protrusions  41  and  45  may be in contact with each other or slightly spaced apart from each other. 
     Now, a structure for supporting the antenna substrate  13  will be described. With reference to  FIG. 1 , two supporting columns  51  are formed on the attachment part  9  in the main unit case  3 . The two supporting columns  51  are formed at the positions corresponding to opposite edges  53  of the antenna substrate  13 . Each supporting column  51  has a holding groove  55 . The holding grooves  55  extend in a direction away from the attachment part  9 . The edges  53  of the antenna substrate  13  are inserted into the holding grooves  55 . In this way, the antenna substrate  13  is supported by the holding grooves  55  at the opposite sides thereof. 
     In addition, the waveguide substrate  11  has a clearance hole  61  substantially at the center thereof. A protrusion on the main unit case  3  is received in the clearance hole  61 . In addition, the waveguide substrate  11  has clearance recesses  65  and  67  in an edge  63  opposite to the edge  31 . Protrusions on the main unit case  3  are received also in the clearance recesses  65  and  67 . 
     In addition, angled protrusions (or corner protrusions)  71  are formed on the attachment part  9  in the main unit case  3 . The angled protrusions  71  are formed at the position corresponding to corners  73  of the waveguide substrate  11 . The angled protrusions  71  are used when attaching the waveguide substrate  11  to the attachment part  9 . During attachment, the waveguide substrate  11  is disposed in such a manner that the corners  73  are located inside the angled protrusions  71 . 
     In addition, two slit-like notches  83  are formed in a lower edge  81  of the antenna substrate  13 . Ribs  85  on the attachment part  9  in the main unit case  3  are fitted into the notches  83 . 
     In addition, two ribs  93  are formed on a wall  91  in the main unit case  3 . The wall  91  extends along the backside of the antenna substrate  13 . The ribs  93  extend along the wall  91  in a direction away from the attachment part  9 . The ribs  93  are in contact with the backside of the antenna substrate  13  and support the antenna substrate  13 . 
     An arrangement of the electronic device according to this embodiment has been described particularly with regard to the antenna unit  7  and the attachment structure therefor. In the following, a method of assembly of the electronic device according to this embodiment will be described. 
     First, the waveguide substrate  11  and the antenna substrate  13  are coupled to each other. In this step, the waveguide substrate  11  and the antenna substrate  13  are disposed at right angles to each other. The inserts  33  on the waveguide substrate  11  are inserted into the slits  37  in the antenna substrate  13 . The waveguide substrate  11  is inserted until the edge  31  of the waveguide substrate  11  comes into contact with the antenna substrate  13 . When the inserts  33  are inserted into the slits  37 , the protrusion  41  on the waveguide substrate  11  is inserted into the slit  43  in the antenna substrate  13  at the same time. 
     Then, the waveguide substrate  11  and the antenna substrate  13  are slid with respect to each other, thereby sliding the inserts  33  in the slits  37 . This makes the engaging hooks  35  catch the ends of the slits  37  and engage with the antenna substrate  13 . 
     In the sliding step described above, the protrusion  41  on the waveguide substrate  11  moves within the slit  43  in the antenna substrate  13  and comes into contact with the protrusion  45  in the slit  43 . The protrusion  41  moves over the protrusion  45  and reaches to the other side thereof. When the protrusion  41  moves over the protrusion  45 , the waveguide substrate  11  is slightly bent and elastically deformed. This enables the protrusion  41  to move through the clearance beside the protrusion  45  and past the protrusion  45  within the slit  43 . 
     The waveguide substrate  11  and the antenna substrate  13  are coupled to each other as described above. Then, the substrates  11  and  13  coupled to each other are assembled to the main unit case  3 . 
     In the assembly step, the opposite edges  53  of the antenna substrate  13  are inserted into the holding grooves  55  on the supporting columns  51  in the main unit case  3 . The antenna substrate  13  and the waveguide substrate  11  are guided by the holding grooves  55  toward the attachment part  9 . 
     When the edges  53  of the antenna substrate  13  are inserted to an appropriate position in the holding grooves  55 , the waveguide substrate  11  reaches the attachment part  9 . At this time, the corners  75  of the waveguide substrate  11  are disposed inside the angled protrusions  71  on the main unit case  3 . The screw holes  23  in the waveguide substrate  11  are aligned with the bosses  17  on the main unit case  3 . In addition, the clearance hole  61  and the clearance recesses  65  and  67  in the waveguide substrate  11  receive the corresponding protrusions on the main unit case  3 . In addition, the ribs  85  on the main unit case  3  are fitted into the notches  83  in the edge  81  of the antenna substrate  13 . In addition, the ribs  93  on the main unit case  3  abut against the backside of the antenna substrate  13 . 
     Then, the waveguide substrate  11  is fixed to the attachment part  9  with the screws  15 . Thus, the antenna unit  7  composed of the waveguide substrate  11  and the antenna substrate  13  is assembled to the main unit case  3 . Once assembled, the movement of the antenna substrate  13  is restricted by the waveguide substrate  11  and the main unit case  3 . Specifically, the inserts  33  on the waveguide substrate  11 , which are inserted in the slits  37  in the antenna substrate  13 , prevent the antenna substrate  13  from moving away from the attachment part  9 . In addition, the engaging hooks  35  of the inserts  33 , which engage with the antenna substrate  13 , restrict the movement of the antenna substrate  13  in the lateral or horizontal direction in the plane of the attachment part  9  (specifically, in the height direction of the main unit case  3 ). Furthermore, the holding grooves  55  of the main unit case  3  hold the edges  53  of the antenna substrate  13 , thereby restricting the movement of the antenna substrate  13  in the lateral or horizontal direction in the plane of the attachment part  9  (specifically, in the width direction of the main unit case  3 ). In this way, the antenna substrate  13  is also fixed to the main unit case  3  along with the waveguide substrate  11 . 
     The antenna substrate  13  may be completely prevented from movement. Alternatively, the antenna substrate  13  may move to such an extent that the movement has no effect on the antenna performance. According to this embodiment, the latter state is also regarded as the “fixed state”. 
     The electronic device with a built-in antenna according to this embodiment has been described. According to this embodiment, the waveguide substrate  11  is fixed to the attachment part  9 , and the antenna substrate  13  is disposed to protrude from the attachment part. The inserts  33  on the waveguide substrate  11  are inserted into the slits  37  in the antenna substrate  13 . Thus, the movement of the antenna substrate  13  is restricted by the waveguide substrate  11 . Thus, the substrates  11  and  13  can be integrally assembled to the housing without using a metal plate bracket to couple the substrates  11  and  13  to each other. 
     In addition, according to this embodiment, the housing has the holding grooves  55  extending in a direction away from the attachment part  9 , and the edges of the antenna substrate  13  are inserted in the holding grooves  55 . Thus, the antenna substrate  13  is held by the holding grooves  55 , so that the antenna substrate  13  is prevented from shaking. In addition, the holding grooves  55  serve also as guide grooves for guiding the antenna substrate  13  during assembly, so that the assembly is facilitated. 
     In addition, according to this embodiment, the inserts  33  on the waveguide substrate  11  have the engaging hooks  35 . Thus, the antenna substrate  13  is hard to be disengaged from the waveguide substrate  11 , and the substrates are appropriately fixed to the attachment part. 
     In addition, according to this embodiment, the antenna substrate  13  has the protrusion  45  at such a position that the protrusion  45  prevents the movement of the protrusion  41  on the waveguide substrate  11  in such a direction that the engaging hooks  35  are disengaged from the antenna substrate  13 . Thus, the substrates  11  and  13  can be temporarily fixed to each other before the substrates are attached to the housing. Therefore, the substrates  11  and  13  can be easily assembled to the housing. 
     The waveguide substrate  11  and the antenna substrate  13  according to this embodiment correspond to one substrate and the other substrate according to the present invention, respectively. However, the antenna substrate may correspond to one substrate, and the waveguide substrate may correspond to the other substrate. In this case, the antenna substrate has inserts, and the waveguide substrate has slits. And, the antenna substrate is fixed to the housing. 
     A currently possible preferred embodiment of the present invention has been described above. However, it is to be understood that various modifications can be made to this embodiment, and all such modifications are included in the true scope and spirit of the present invention defined in the accompanying claims. 
     INDUSTRIAL APPLICABILITY 
     As described above, the electronic device with a built -in antenna according to the present invention has an advantage that the substrates can be integrally assembled to the housing without using a metal plate bracket, so that the antenna performance is improved, and is useful as a radio communication device or the like.