Abstract:
In an electronic apparatus such as a portable computer provided with an electronic apparatus frame having a boss portion, a protrusion is formed in a position for the boss portion, the electronic apparatus comprising a boss separator formed having a retaining hole and attached to the protrusion to form the boss portion.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This is a Continuation Application of PCT Application No. PCT/JP99/01762, filed Apr. 2, 1999, which was not published under PCT Article 21(2) in English.  
     
    
     
         [0002]    This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 10-173019, filed Jun. 19, 1998, the entire contents of which are incorporated herein by reference.  
         BACKGROUND OF THE INVENTION  
         [0003]    This invention relates to an electronic apparatus having a frame of a light metal used in a personal computer or the like, a manufacturing method for the electronic apparatus, and a mold device for forming the frame of the electronic apparatus.  
           [0004]    Recently, magnesium alloys have been mainly used as the material of an electronic apparatus frame of a light metal. These alloys are molded by die-casting or thixotropy. In either of these molding methods, which use different equipment mechanisms, an alloy melted at 580° to 750° is injected into a mold of about 100° to 350° and molded.  
           [0005]    [0005]FIG. 6 shows a configuration of a conventional electronic apparatus frame  1 . In molding this electronic apparatus frame  1 , a molten metal is poured through a sprue  2  (this drawing shows the shape of the electronic apparatus frame just molded, and in the description to follow, various parts of a mold device will be described corresponding to the shape of the electronic apparatus frame just molded), and the molten metal is introduced into a desired mold through a runner  3 . The introduced molten metal diffuses throughout a cavity  4  and finally reaches an air vent  5 . Further, a molten metal reservoir  6  is coupled to the air vent  5 . When the molten metal is introduced through the sprue  2 , therefore, air can be discharged to the outside through the air vent  5 . Thereupon, the frame can be formed without containing any voids therein.  
           [0006]    In order to change the shape of the electronic apparatus frame  1  of FIG. 6 just molded into a utilizable shape, moreover, the sprue  2 , runner  3 , air vent  5 , or molten metal reservoir  6  is cut off thereafter to shape the electronic apparatus frame  1 .  
           [0007]    After the molten metal is solidified in the cavity  4 , the solidified frame shape is taken out. In the case where the electronic apparatus frame  1  is provided with pores  7  for heat radiation to the outside or for use as a speaker, for example, the pores  7  are formed by punching at given pitches. Thus, the narrow-pitch pores  7  are formed in the electronic apparatus frame  1  in the aforesaid manner.  
           [0008]    However, punching the cavity shape to form the pores  7  one by one after the frame shape is formed in the cavity  4  requires post-forming, which entails higher cost. Accordingly, there is a demand for a manufacturing method capable of rapidly forming the pores  7  without entailing high cost.  
           [0009]    Hereupon, there may be proposed a manufacturing method in which the molten metal is poured into the cavity  4  that is provided with pins projecting therein, and the frame shape having the pins formed thereon is taken out of the mold device.  
           [0010]    In the case where the pins are arranged at narrow pitches, according to this manufacturing method, however, the fluidity of the molten metal between the pins worsens if the molten metal is a magnesium alloy, for example. In some cases, the molten metal may possibly fail to penetrate into the regions between the pins, thus leaving unfilled portions.  
           [0011]    If the frame used is formed of a magnesium alloy, moreover, burrs are inevitably formed as the frame shape is punched at narrow pitches, since the electronic apparatus frame  1  is thinned. Since the burrs arouse a problem on the external appearance of products, they must be removed in an additional laborious process.  
         BRIEF SUMMARY OF THE INVENTION  
         [0012]    This invention has been contrived in consideration of these circumstances, and its object is to provide an electronic apparatus with a frame having a good external appearance and shape, lowered in cost, and capable of affording rapid formation of pores at narrow pitches, an electronic apparatus manufacturing method, and a mold device.  
           [0013]    According to a preferred embodiment, a mold device of this invention is a mold device comprising pin members provided projecting from an upper mold or a lower mold in order to form a frame having pores arranged at given pitches, the lower mold or the upper mold opposed to the respective projecting end portions of the pin members having a depression such that the pin members can be formed projecting longer than the wall thickness of the frame and that an inflow bypass portion kept at a given space from the respective projecting end portions of the pin members can be provided in positions for the pin members.  
           [0014]    Further, an electronic apparatus manufacturing method of this invention is an electronic apparatus manufacturing method for molding a frame of an electronic apparatus having pores arranged at given pitches, by means of the mold device according to claim 1, comprising a flowing process for causing a molten metal to flow in the inflow bypass portion and diffuse throughout the interior of the mold device, a solidifying process for solidifying the molten metal introduced into the mold device in the flowing process, thereby forming a molded piece, and a working process for forming penetrating pores by machining a raised portion corresponding to the depression of the molded piece formed in the solidifying process and making the raised portion flush with the other portion.  
           [0015]    Furthermore, an electronic apparatus of this invention is an electronic apparatus comprising a frame formed having pores arranged at given pitches, the pores being initially surrounded by a raised portion formed having pore shapes deeper than the wall thickness of the frame, the electronic apparatus having a machined surface around the penetrating pores formed by machining the raised portion so that the raised portion is flush with the other portion of the frame.  
           [0016]    Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.  
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
       [0017]    The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate presently preferred embodiments of the invention, and together with the general description given above and the detailed description of the preferred embodiments given below, serve to explain the principles of the invention.  
         [0018]    [0018]FIG. 1 is a perspective view showing the shape of a prior art electronic apparatus frame;  
         [0019]    [0019]FIG. 2 is a perspective view showing a configuration of a portable computer as an electronic apparatus according to one embodiment of this embodiment;  
         [0020]    [0020]FIG. 3 is a sectional view showing the shape of a mold device of the same embodiment;  
         [0021]    [0021]FIG. 4 is a partial enlarged view of the mold device;  
         [0022]    [0022]FIG. 5 is a perspective view showing the shape of an electronic apparatus frame used for the electronic apparatus;  
         [0023]    [0023]FIG. 6 shows a flowchart for a manufacturing method for the electronic apparatus;  
         [0024]    [0024]FIG. 7 is a perspective view showing the shape of a molded piece; and  
         [0025]    [0025]FIG. 8 is a sectional view illustrating a manufacturing method for the electronic apparatus having the electronic apparatus frame of the same embodiment, in which FIG. 8A is a view showing a state in which a raised portion of the molded piece left uncut, and FIG. 8B is a view showing the molded piece with the raised portion off.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0026]    One embodiment of the present invention will now be described with reference to FIGS.  2  to  8 B.  
         [0027]    [0027]FIG. 2 is an external view showing the shape of a portable computer  10  such as a note-type personal computer. In this drawing, the portable computer  10  comprises a computer body  11  and a display unit  12  that is rockably supported on the computer body  11 . The computer body  11  is provided with a frame  13 , and this frame  13  is design so that a lower frame  14  and an upper frame  15  are suitably joined by means of, for example, screws or the like. However, the lower frame  14  and the upper frame  15  may be joined by means of any other arrangement than this.  
         [0028]    In the description to follow, the frame that is applied to the portable computer  10  or some other electronic apparatus will be described as an electronic apparatus frame  20 .  
         [0029]    The electronic apparatus frame  20  of the light metal personal computer, formed of a magnesium alloy or the like, sometimes may require a large number of pores  21  arranged at short pitches, as shown in FIG. 5, in order to fulfill a function to cool the inside of the personal computer or to serve as a speaker for external sounding. A mold device  30  shown in FIG. 3 is used to provide this electronic apparatus frame  20 .  
         [0030]    The mold device  30  includes an upper mold  31  and a lower mold  32 , which engage each other to form the mold device  30 . The mold device  30  is provided with a sprue  33 , for use as a molten metal inlet, and a runner  34  for guiding a molten metal in introduction into the mold and in uniform diffusion. The molten metal guided by means of the runner  34  is introduced into a cavity  35  of the mold device  30 .  
         [0031]    The molten metal is a molten magnesium alloy. Alternatively, an aluminum alloy may be used for the molten metal, for example.  
         [0032]    In order to form the pores  21  in the aforesaid electronic apparatus frame  20 , the cavity  35  is provided with pin members  36  in those parts which correspond to the pores  21  of the mold device  30 , individually. The pin members  36 , which have a length such that they project a little longer than the wall thickness of the electronic apparatus frame  20 , are provided on the upper mold  31 .  
         [0033]    The lower mold  32 , which faces those parts of the upper mold  31  on which the pin members  36  are provided, is provided with an inflow bypass portion  37  shown in FIG. 4. This inflow bypass portion  37  is located in a depression  38  that is depressed below the other parts of the cavity  35 . The depression  38  has a depth such that the gap between the inflow bypass portion  37  and the respective projecting end portions of the pin members  36  is substantially equal to the width of the other parts of the cavity  35 .  
         [0034]    An air vent  39  is formed in the other end of the cavity  35 . The air vent  39  serves to discharge air in the mold device  30  to the outside of the mold device  30 . The air vent  39  further communicates with a molten metal reservoir  40 . Thus, the molten metal introduced into the mold device  30  can reach the molten metal reservoir  40  without producing voids in the cavity  35 .  
         [0035]    The following is a description of a manufacturing method for manufacturing the electronic apparatus frame  20  by means of the mold device  30  constructed in this manner. FIG. 6 shows a flowchart for the manufacturing method.  
         [0036]    In injection-molding the electronic apparatus frame  20  of a light metal, a pressure of about 250 tons, for example, is applied to a molten magnesium alloy. By the application of this pressure, the molten metal is introduced into the cavity  35  in the mold device  30 . In the mold device  30 , however, the pin members  36  are arranged at pitches (hereinafter referred to as narrow pitches) such that the molten metal cannot be introduced satisfactorily, and the fluidity of the molten magnesium alloy is unfavorable (i.e., if the molten metal comes into contact with the respective inner wall surfaces of the upper mold  31  and the lower mold  32  that are touched by the molten metal, the touched portion is cooled and solidified first, so that the fluidity is unsatisfactory). Accordingly, the fluidity worsens between the individual pin members  36  that are arranged at the narrow pitches. Unfilled portions may be created as this is done, and those portions may form voids, possibly causing malformation.  
         [0037]    In order to prevent the occurrence of the malformation, the molten metal is caused to flow into the inflow bypass portion  37  in the depression  38  of the lower mold  32 , and the molten metal is caused to flow in the region between the inflow bypass portion  37  and the pin members  36  after it is made to flow first in the aforesaid portion (flowing process).  
         [0038]    Thus, as the molten metal flows from one end of the cavity  35  to the other end, a normal molten metal flow such that the molten metal gets into the positions between the individual pin members  36  is produced along with a faster molten metal flow in the inflow bypass portion  37  in which the molten metal easily flows. Accordingly, a molten metal flow is generated such that the molten metal penetrates from the inflow bypass portion  37  into the gaps between the pin members  36  that are located on the upper side. In consequence, most of the molten metal that penetrates into the gaps between the pin members  36  is directed upward from the inflow bypass portion  37 , so that the molten metal can easily get into the positions between the individual pin members  36 .  
         [0039]    Thereafter, the molten metal solidifies in the cavity  35  to form a molded piece  41  shown in FIG. 7 (solidifying process). This molded piece  41  has a raised portion  42  that is provided corresponding to the depression  38 .  
         [0040]    As shown in FIGS. 8A and 8B, moreover, the raised portion  42  is formed having holes  43  that are provided corresponding to the pin members  36  and have a depth greater than the wall thickness of the electronic apparatus frame  20 . Thus, the lower end side of the holes  43  further projects beyond the wall thickness of the electronic apparatus frame  20 .  
         [0041]    Then, the pores  21  can be provided penetrating the electronic apparatus frame  20  by subjecting the raised portion  42 , a to-be-removed portion, to cutting work (or any other machining) by means of, for example, a milling machine so that it is flush with the other part of the molded piece  41  (working process).  
         [0042]    As this cutting work is carried out, a cut surface (machined surface)  44  is formed in the region around the pores  21  from which the raised portion  42  is removed.  
         [0043]    According to the mold device  30  constructed in this manner, the electronic apparatus frame  20 , and the manufacturing method therefor, the mold device  30  is provided with pin members  36 , the depression  38  is formed in the mold device  30  so that the length of projection of the pin members  36  is greater than the wall thickness of electronic apparatus frame  20 , and the region between the depression  38  and the respective projecting end portions of the pin members  36  forms the inflow bypass portion  37 . Accordingly, the molten metal from the inflow bypass portion  37  can be caused to penetrate into the regions between the pin members  36 , thereby preventing creation of unfilled portions.  
         [0044]    Thus, although the pin members  36  are arranged at the narrow pitches, the molten metal can be caused easily to get into the intermediate regions.  
         [0045]    Further, the raised portion  42  is formed on the molded piece  41  by means of the mold device  30 , and the pores  21  are formed in the electronic apparatus frame  20  by removing the raised portion  42  by cutting work or the like. As compared with the case where the narrow-pitch pores  21  are bored by pressing or by means of a drill or the like, therefore, the cost for a working apparatus can be lowered, and the working time can be shortened.  
         [0046]    Furthermore, creation of burrs that are usually formed around the respective openings of the pores  21  when boring or pressing is effected can be restrained, so that the external appearance and shape of the electronic apparatus frame  20  can be improved.  
         [0047]    Since the magnesium alloy is used as the material of the electronic apparatus frame  20 , moreover, there may be provided the electronic apparatus frame  20  that is highly stiff and strong enough despite its reduced thickness.  
         [0048]    Although the one embodiment of the present invention has been described above, the present invention can be modified variously. The following is a description of the modification.  
         [0049]    According to the embodiment described above, the described electronic apparatus frame  20  has the narrow-pitch pores  21 . However, the present invention is not limited to this embodiment and may be also applied to other components and the like.  
         [0050]    Further, all the pores  21  need not be arranged at narrow pitches, and the present invention may be also applied to a configuration that has various pitches such that some of pitches are narrow.  
         [0051]    Furthermore, various modifications may be effected without departing from the spirit of the present invention.  
         [0052]    Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.