Abstract:
In an electronic device, a speaker attaching section  17  which is vertically open with respect to a circuit board  10  and into which a speaker  16  is press-fitted is integrally formed on a contact sheet  13  arranged on the circuit board  10  provided inside an upper case  8 . Therefore, the speaker  16  can be easily attached in a manner that sound therefrom does not leak, simply by the speaker  16  being press-fitted into the speaker attaching section  17  of the contact sheet  13 . Accordingly, in the present invention, the structure of the speaker section  6  is simple and the number of its components is small, whereby the thickness of the speaker section  6  can be reduced. In addition, sound generated by the speaker can be favorably and reliably emitted from the speaker attaching section  17  to the outside of the upper case  8 , without chattering noise being generated.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2010-261018, filed Nov. 24, 2010, the entire contents of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an electronic device including a speaker, such as an electronic dictionary, a mobile phone, or a personal digital assistant (PDA). 
     2. Description of the Related Art 
     As a mounting structure for a speaker in a mobile phone, a structure is known in which a speaker unit is provided on a circuit board inside a device case, a contact sheet having a plurality of contact sections is provided on the circuit board, a key sheet having a plurality of key tops is provided on the contact sheet and each key top of the key sheet is exposed from the surface of the device case, as described in Japanese Patent Application Laid-Open (Kokai) Publication No. 2005-236894. 
     In amounting structure for a speaker such as this, a sound emitting hole is provided in a key top of the key sheet in an area corresponding to the speaker unit, as well as in a contact section of the contact sheet in the area corresponding to the speaker unit, in order to emit sound generated in the speaker unit from the device case. 
     However, there is a problem in this conventional mounting structure for a speaker in that the thickness from the front surface of the key top to the undersurface of the speaker unit is large and therefore the thinning of the device cannot be achieved. 
     In addition, there is another problem in this conventional mounting structure for a speaker in that sound generated in the speaker unit cannot be satisfactorily emitted outside from the device case. 
     Although a mounting structure has been developed in which the contact sheet between the speaker unit and the key sheet is arranged underneath the speaker unit, and the speaker unit is placed closer to the key tops of the key sheet, there is a problem in that sound generated in the speaker unit is not emitted from only the sound emitting hole in the key top because it leaks to the surrounding area of the speaker unit. 
     As described above, in the conventional mounting structure for a speaker, a structure has been adopted in which a speaker unit is provided on a circuit board. Accordingly, the contact sheet is required to be provided on or underneath the speaker unit, and therefore the overall thickness cannot be made sufficiently thin. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an electronic device having a mounting structure for a speaker which is simple and by which the thinning of the device can be achieved and sound generated by the speaker can be satisfactorily emitted outside the device case. 
     In order to achieve the above-described object, in accordance with one aspect of the present invention, there is provided an electronic device comprising: a case in which an opening section is provided in a predetermined area; a circuit board arranged inside the case; a speaker electrically connected to the circuit board; and a contact sheet arranged on the circuit board, in which a speaker attaching section, which is vertically open with respect to the circuit board and into which the speaker is press-fitted, is integrally formed in an area corresponding to the opening section in the case. 
     In the present invention, the speaker can be easily attached by simply being fitted in the speaker attaching section provided on the contact sheet arranged on the circuit board inside the case. Accordingly, the structure is simple and the number of its components is small, whereby the thickness of the device can be reduced. In addition, sound generated by the speaker can be favorably emitted outside the case without chattering noise being generated. 
     The above and further objects and novel features of the present invention will more fully appear from the following detailed description when the same is read in conjunction with the accompanying drawings. It is to be expressly understood, however, that the drawings are for the purpose of illustration only and are not intended as a definition of the limits of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an outer appearance view of an electronic dictionary to which the present invention has been applied; 
         FIG. 2  is an enlarged planar view showing a speaker section of the electronic dictionary shown in  FIG. 1 ; 
         FIG. 3  is an enlarged cross-sectional view of the speaker section taken along line A-A in  FIG. 2 ; 
         FIG. 4A  is a planar view showing an upper substrate of a circuit board of the electronic dictionary; 
         FIG. 4B  is a planar view showing a lower substrate of the circuit board of the electronic dictionary; 
         FIG. 5  is a planar view showing a contact sheet of the electronic dictionary; 
         FIG. 6  is a rear view of the circuit board to which the contact sheet has been attached, when viewed from below; 
         FIG. 7  is an enlarged cross-sectional view taken along line B-B in  FIG. 6 ; 
         FIG. 8  is an enlarged planar view of a speaker shown in FIG.  6 ; 
         FIG. 9  is an enlarged rear view of the main section of a speaker attaching section on the contact sheet into which the speaker shown in  FIG. 8  is attached; 
         FIG. 10  is an enlarged planar view of the speaker section in an upper case of the electronic dictionary; 
         FIG. 11  is an enlarged perspective view of the speaker section on the contact sheet; 
         FIG. 12  is an enlarged rear view of a key top shown in  FIG. 2 ; 
         FIG. 13  is an enlarged perspective view of a speaker installing section in a lower case; 
         FIG. 14  is an enlarged cross-sectional view showing a state where the speaker is inserted into the speaker attaching section on the contact sheet; and 
         FIG. 15  is an enlarged cross-sectional view showing a state where the speaker has been fitted in the speaker attaching section. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     An embodiment in which the present invention has been applied to an electronic dictionary will hereinafter be described with reference to  FIG. 1  to  FIG. 15 . 
     As shown in  FIG. 1 , an electronic dictionary  100  is structured such that a first case  1  and a second case  2  are openably and closably connected by a hinge section  3 . 
     The first case  1  includes a key input section  4 , a touch input section  5 , and a speaker section  6 , and the second case  2  includes a display section  7 . The display section  7  is constituted by a flat display panel such as a liquid crystal display panel or an electroluminescent (EL) display panel, and electro-optically displays various information required for a dictionary function. 
     The key input section  4  includes various keys required for the dictionary function, such as character keys  4   a , function keys  4   b , and a cursor key  4   c . In this instance, an enter key  4   d  is provided in the center of the cursor key  4   c , and two auxiliary keys  4   e  are provided around the outer periphery of the cursor key  4   c.    
     The touch input section  5  is a display panel layered on the undersurface of a transparent touch panel. The speaker section  6  is used to put out information displayed in the display section  7  by sound, which has a switch function described hereafter. 
     The first case  1  includes an upper case  8  and a lower case  9  as shown in  FIG. 3 , and a circuit board  10  is arranged over substantially the entire area inside the upper case  8  and the lower case  9 . The circuit board  10  has a two-layer structure in which an upper substrate  10   a  and a lower substrate  10   b  are layered, as shown in  FIG. 3  and  FIG. 4 . On the top surface of the upper substrate  10   a , a plurality of fixed contacts  11   a  are provided respectively corresponding to the keys  4   a  to  4   e  of the key input section  4  excluding the cursor key  4   c , as shown in  FIG. 4A . 
     Also, on the top surface of the lower substrate  10   b , fixed contacts  11   b  corresponding to the cursor key  4   c  is provided corresponding to contact insertion holes  10   c  in the upper substrate  10   a  of  FIG. 4A , as shown in  FIG. 4B . As shown in  FIG. 6 , various electronic components  12  required for the dictionary function are mounted on the undersurface of the circuit board  10 , or in other words, the undersurface of the lower substrate  10   b.    
     In addition, a contact sheet  13  made of an elastic material, such as rubber or elastomer, is arranged on the top surface of the circuit board  10 , or in other words, on the top surface of the upper substrate  10   a , as shown in  FIG. 3 . On the contact sheet  13 , a plurality of contact sections  14  are integrally provided respectively corresponding to the keys  4   a  to  4   e  of the key input section  4 , as shown in  FIG. 5 . The upper case  8  is provided with key insertion holes  8   a  into which the keys  4   a  to  4   e  are respectively inserted, as shown in  FIG. 10 . 
     As shown in  FIG. 5  to  FIG. 7 , a gripping section  15  that grips the outer peripheral edge of the circuit board  10  is provided on the outer peripheral edge of the contact sheet  13 . The gripping section  15  is formed into a groove shape that extends from the top surface of the circuit board  10  to the side surface and further to the undersurface along the outer peripheral edge thereof, as shown in  FIG. 7 . As a result, the gripping section  15  is structured such that the contact sheet  13  is attached to the circuit board  10  by the contact sheet  13  being placed on the circuit board  10  and the outer peripheral edge of the circuit board  10  being fitted in the gripping section  15 , as shown in  FIG. 6  and  FIG. 7 . 
     The speaker section  6  includes the circuit board  10  arranged inside the first case  1 , a disk-shaped speaker electrically connected to the circuit board  10  by a lead wire  16   a , the contact sheet  13  on which a speaker attaching section  17  where the speaker  16  is attached is integrally formed, and the key top  18  arranged on the speaker attaching section  17  of the contact sheet  13 , as shown in  FIG. 2  and  FIG. 3 . 
     As shown in  FIG. 3 ,  FIG. 4 , and  FIG. 6 , an insertion hole  19  into which the speaker attaching section  17  of the contact sheet  13  is inserted is provided in the circuit board  10 . The speaker attaching section  17  includes a cylindrical section  20  that projects lower than the circuit board  10  from the undersurface of the contact sheet  13  through the insertion hole  19  in the circuit board  10 , and a stopper section  21  that projects inward to form a brim-like shape from the upper portion of the cylindrical section  20 , as shown in  FIG. 3 . 
     The cylindrical section  20  of the speaker attaching section  17  is a circular cylinder section whose top and bottom are open as shown in  FIG. 3 ,  FIG. 9 , and  FIG. 14 , and formed having an inner diameter that is slightly smaller than the outer diameter of the speaker  16 , and a height that is almost the same as the thickness of the speaker  16 . Accordingly, the speaker  16  is fitted in this cylindrical section  20  by being pressed from below. 
     That is, the cylindrical section  20  is structured such that, when the speaker  16  is fitted therein, the speaker  16  is attached without a gap being formed that causes sound from the speaker  16  to leak, as shown in  FIG. 3  and  FIG. 15 . In addition, the stopper section  21  is structured such that, when the speaker  16  is fitted in the cylindrical section  20  by being pressed from below, the stopper section  21  comes in contact with the upper surface of the outer periphery of the speaker  16 , and thereby restricts the upper limit position of the speaker  16  and fixes the speaker  16  inside the cylindrical section  20 . 
     As shown in  FIG. 8 , an engaging projection  22  for positioning is provided on the outer periphery of the speaker  16 . In addition, as shown in  FIG. 9 , an engaging groove section  23  for positioning, with which the engaging projection  22  of the speaker  16  engages, is provided in the cylindrical section  20  of the speaker attaching section  17 . As a result, when the speaker  16  is fitted in the cylindrical section  20  by being pressed from below, the engaging projection  22  of the speaker  16  engages with the engaging groove section  23  of the cylindrical section  20 , whereby the rotation position of the speaker  16  in the planar direction is restricted. 
     Moreover, as shown in  FIG. 3  and  FIG. 11 , a skirt section  24  that is elastically deformable and extends higher than the contact sheet  13  is integrally formed on the inner periphery of the stopper section  21  in the speaker attaching section  17 , and surrounds the upper periphery of the speaker  16 . The upper portion of the skirt section  24  is open, and the key top  18  is arranged on the peripheral edge of this open upper portion. As a result of this structure, the skirt section  24  holds the key top  18  so as to elastically press the key top  18  upwards, and surrounds the upper periphery of the speaker  16  such that sound from the speaker  16  does not leak to the surrounding area. 
     Furthermore, as shown in  FIG. 3 ,  FIG. 5 , and  FIG. 11 , a plurality of contact sections  25  are provided on the contact sheet  13  along the outer periphery of the speaker attaching section  17 . These contact sections  25  are respectively provided in the 12 o&#39;clock, 3 o&#39;clock, 6 o&#39;clock, and 9 o&#39;clock positions in the outer periphery of the speaker attaching section  17 . 
     Each contact section  25  includes a dome-shaped protruding section  25   a  formed slightly higher than the skirt section  24  of the speaker attaching section  17 , a movable contact  25   b  provided inside the protruding section  25   a , and a fixed contact  25   c  provided on the upper substrate  10   a  of the circuit board  10  to come in contact with the movable contact  25   b , as shown in  FIG. 3 . 
     Accordingly, the plurality of contact sections  25  each form a key switch. For example, the contact section  25  at the 12 o&#39;clock position is a key switch for switching the mode of the electronic dictionary  100  to a history mode, the contact section  25  at the 3 o&#39; clock position is a key switch for setting a display layout, the contact section  25  at the 6 o&#39;clock position is a key switch for setting a jump mode, and the contact section  25  at the 9 o&#39;clock position is a key switch for selectively specifying text size. 
     The key top  18  is formed into a disk shape of a size covering the plurality of contact sections  25  arrayed in a ring shape, and arranged on the upper portion of the speaker attaching section  17 , as shown in  FIG. 3 . This key top  18  is arranged within a circular hole  8   b  provided in the upper case  8  as shown in  FIG. 10 , and is exposed from the upper side of the upper case  8  as shown in  FIG. 2 . 
     Also, the key top  18  is bonded to the outer peripheral edge of the upper portion of the skirt section  24  of the speaker attaching section  17  and the top surface of each contact point  25  by adhesive glue  26 , as shown in  FIG. 11  and  FIG. 12 . In the center portion of this key top  18  corresponding to the speaker attaching section  17 , a plurality of sound emitting holes  18   a  are provided as shown in  FIG. 2  and  FIG. 3 . As a result, a closed space is formed between the key top  18  and the speaker  16  by the skirt section  24  of the speaker attaching section  17 , whereby sound from the speaker  16  is prevented from leaking from an area other than the sound emitting holes  18   a , as shown in  FIG. 3  and  FIG. 15 . 
     As shown in  FIG. 3 , an acoustic space  28  is formed below the speaker  16  by an acoustic wall section  27  provided in the lower case  9  of the first case  1 . Specifically, the acoustic wall section  27  is constituted by a semi-circular arc-shaped wall section  27   a  that is provided upright on the bottom section of the lower case  9  and is in close contact with the lower outer periphery of the speaker attaching section  17 , and a plurality of supporting columns  27   b  that are each provided upright on the bottom section of the lower case  9  and is in contact with the lower end surface of the speaker attaching section  17 , as shown in  FIG. 13 . As a result, the acoustic wall section  27  is structured to form the acoustic space  28  that resonates sound emitted downwards from the speaker  16  within the overall lower case  9 . 
     In addition, as shown in  FIG. 2 , two auxiliary key sections  30  and  31  are provided in areas on the outer periphery of the key top  18 , such as an area between the 1 o&#39; clock position and the 2 o&#39; clock position, and an area between the 4 o&#39; clock position and the 5 o&#39;clock position. These two auxiliary key sections  30  and  31  are structured such that two contact sections  32  and  33  provided on the contact sheet  13  are inserted into two semi-circular holes  8   c  of  FIG. 10  provided in the upper case  8  from below and exposed from the upper side, as shown in  FIG. 5  and  FIG. 11 . 
     The contact sections  32  and  33  of the two auxiliary key sections  30  and  31  are structured by a movable contact (not shown) being provided in each of two projecting portions on the contact sheet  13 . When the contact section  32  and  33  are pressed and elastically deformed, the movable contacts comes in contact with fixed contacts  32   a  and  33   a  provided on the lower substrate  10   b  shown in  FIG. 4B , and a switch operation is performed thereby. 
     Next, the mounting of the speaker  16  into the speaker section  6  in the first case  1  will be described. 
     First, the contact sheet  13  is attached to the top surface of the circuit board  10  such that the contact sections  14  of the contact sheet  13  correspond to the respective fixed contacts  11   a  provided on the circuit board  10 . 
     At this time, the speaker attaching section  17  of the contact sheet  13  is inserted into the insertion hole  19  in the circuit board  10  and projects lower than the circuit board  10 . In this state, the outer peripheral edge of the circuit board  10  is fitted in the gripping section  15  provided on the outer peripheral edge of the contact sheet  13 , whereby the contact sheet  13  is attached to the circuit board  10 . 
     Next, the circuit board  10  to which the contact sheet  13  has been attached is placed in the upper case  8  of the first case  1 . At this time, the assembler grasps the gripping section  15  of the contact sheet  13  positioned on the periphery of the circuit board  10 , so that he can mount the circuit board  10  to the upper case  8  without touching it. Therefore, the circuit board  10  is not affected by static electricity or the like, and the quality thereof can be maintained. 
     In the mounting of the circuit board  10  to the upper case  8 , the upper portions of the contact sections  14  of the contact sheet  13  is inserted into the respective key insertion holes  8   a  provided in the uppercase  8 . In addition, the skirt section  24  of the speaker attaching section  17  and the plurality of contact sections  25  positioned around the outer periphery of the skirt section  24  are inserted into the circular hole  8   b  provided in the upper case  8 . 
     Then, the key top  18  is attached to the upper portion of the skirt section  24  and the plurality of contact sections  25  positioned around the outer periphery of the skirt section  24  that have been inserted into the circular hole  8   b  of the upper case  8 . At this time, the adhesive glue  26  is applied to the upper outer peripheral edge of the skirt section  24  and each top surface of the plurality of contact sections  25 , by which the key top  18  is bonded, as shown in  FIG. 11  and  FIG. 12 . 
     Next, the speaker  16  is inserted into the speaker attaching section  17  from below as shown in  FIG. 14 , such that the engaging projection  22  provided on the outer periphery of the speaker  16  corresponds to and engages with the engaging groove section  23  provided in the cylindrical section  20  of the speaker attaching section  17 , as shown in  FIG. 8  and  FIG. 9 . 
     In this state, the speaker  16  is press-fitted into the cylindrical section  20  from below, and the top surface of the outer peripheral portion of the speaker  16  comes in contact with the stopper section  21 . As a result, the speaker  16  is fitted in the cylindrical section  20  of the speaker attaching section  17  without a gap being formed, as shown in  FIG. 15 . 
     Next, the speaker  16  is electrically connected to the circuit board  10  by the lead wire  16   a , as shown in  FIG. 6 . At this time, because the speaker  16  has been fixed to the speaker attaching section  17 , the lead wire  16   a  is not required to be fixed to the circuit board  10  by a fixing member, such as tape. As a result, the operation for connecting the speaker  16  and the circuit board  10  by the lead wire  16   a  is simplified, whereby the connection workability is improved. 
     Then, the lower case  9  is attached to the bottom of the upper case  8  such that the acoustic wall section  27  provided in the lower case  9  corresponds to the lower end surface of the cylindrical section  20  of the speaker attaching section  17 , as shown in  FIG. 3 . As a result, the acoustic space  28  that widely occupies the interior of the lower case  9  is formed below the speaker  16  by the acoustic wall section  27 . 
     Next, effects of this mounting structure for the speaker  16  will be described. 
     When the speaker  16  produces sound, this sound produced from the top surface side of the speaker  16  is emitted outside of the upper case  8  from the plurality of sound emitting holes  18   a  provided in the key top  18 . At this time, because the speaker  16  has been press-fitted into the cylindrical section  20 , the sound from the speaker  16  does not leak to the surrounding area, and chattering noise is not generated. 
     In addition, because the upper periphery of the speaker  16  is closed by the skirt section  24 , the sound from the top surface side of the speaker  16  can be favorably and reliably emitted outside of the upper case  8  from the sound emitting holes  18   a  of the key top  18 . 
     On the other hand, sound emitted from the bottom surface side of the speaker  16  is resonated in the acoustic space  28 . 
     In the key operation of the key top  18 , it is only required that any one of the areas corresponding to the 12 o&#39;clock, 3 o&#39;clock, 6 o&#39;clock, and 9 o&#39;clock positions of the key top  18  is pressed. When it is pressed, one of the plurality of contact sections  25  is depressed and elastically deformed, and the movable contact  25   b  of the contact section  25  comes in contact with the fixed contact  25   c  on the circuit board  10 , whereby an ON operation is performed. 
     At this time, the skirt section  24  also elastically deforms, along with the elastic deformation of the contact section  25 . Therefore, the key stroke of the plurality of contact sections  25  can be sufficiently secured by the skirt section  24 , whereby the key operability is enhanced. 
     In the above-described embodiment, an instance is described in which the skirt section  24  is formed on the inner periphery of the stopper section  21  in the speaker attaching section  17  of the contact sheet  13 . However, the skirt section  24  is not necessarily required to be formed on the inner periphery of the stopper section  21 , and it may be formed in the upper portion of the cylindrical section  20  in the speaker attaching section  17 . 
     Additionally, in the above-described embodiment, the mounting structure for the speaker  16  according to the present invention has been applied to an electronic dictionary. However, the mounting structure is not necessarily required to be applied to an electronic dictionary, and may be widely applied to various electronic devices, such as mobile phones and personal digital assistants (PDA). 
     While the present invention has been described with reference to the preferred embodiments, it is intended that the invention be not limited by any of the details of the description therein but includes all the embodiments which fall within the scope of the appended claims.