Abstract:
A function expansion device is attached to a portable electronic device such as a notebook-type personal computer so as to provide a function to use various kinds of information storage media. A bay housing is detachably attached to a bottom surface of the notebook-type personal computer. The bay housing has a bay into which a drive unit is inserted. The drive unit can be selected from among a floppy disk drive, a CD-ROM drive, a magneto-optical disk drive, a high-capacity floppy disk drive, a digital video disk and a hard disk drive. Each of the drive units has an identical outer configuration so that each of the drive units can be alternatively attached to the bay housing. Various types of drive units can be connected to the notebook-type personal computer by merely changing the drive unit accommodated in the bay housing.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention generally relates to a function expansion device and, more particularly, to a function expansion device for the electronic device installed in the bottom of a portable electronic device.  
           [0003]    The function expansion device (so-called function station) for a portable electronic device (for example, a notebook-type personal computer) which expands the function of the portable electronic device is provided as an attachment of the electronic device which is a portable device. The function expansion device for such a portable electronic device is provided with an information storage medium therein, and has a function which not provided in the portable electronic device. The function expansion device for a portable electronic device is used for expanding the function of a portable electronic device. The function expansion device also serves to reduce a thickness of the portable electronic device by limiting a function of the portable electronic device. Accordingly, the function expansion device becomes necessary for a portable electronic device.  
           [0004]    In recent years, besides a conventional floppy disk and CD-ROM, a magneto-optical disk (MO), high-density recording floppy disk (LS-120) and a digital video disk (DVD), etc. are developed, and the information storage medium is diversified. Accordingly, it is preferable that the function expansion device for a portable electronic device be constructed to correspond to the diversification of the information storage medium in recent years. Moreover, it is preferable that the function expansion device for a portable electronic device be as small as possible so that it can be carried easily. Further, it is preferable that the function expansion device for a portable electronic device has good extendibility of its function.  
           [0005]    2. Description of the Related Art  
           [0006]    [0006]FIG. 1 shows a conventional function expansion device  10  for a notebook-type personal computer  20  as a portable electronic device. The function expansion device  10  is attached to a bottom side of the notebook-type personal computer  20 . A connector  11  of the function expansion device  10  is connected to a connector  21  of the notebook-type personal computer  20 . The function expansion device  10  has a floppy disk drive  12  and a CD-ROM drive  13 . Insertion openings for the floppy disk and the CD-ROM are provided on a front side of the function expansion device  10 .  
           [0007]    In order to expand the function of the notebook-type personal computer  20 , the function expansion device  10  is attached to the notebook-type personal computer  20 , and a floppy disk cartridge  30  or a CD-ROM  31  is loaded to the respective floppy disk drive  12  or the CD-ROM drive  13 .  
           [0008]    Since the conventional function expansion device  10  has only the floppy disk drive  12  and the CD-ROM drive  13 , an information storage medium which can be used with the function expansion device  10  is limited to a floppy disk and a CD-ROM. Accordingly, the function expansion device  10  cannot use other information storage media available on the market, such as a magneto-optical disk (MO), a high capacity floppy disk (LS-120) or a digital video disk (DVD). That is, the function expansion device  10  is limited in its extendibility, and is inconvenient in use.  
           [0009]    Additionally, the conventional function expansion device  10  is not made to be a portable unit, and, the size of the function expansion device  10  is almost the same as that of the notebook-type personal computer  20 . Thus, it is inconvenient for carrying the notebook-type personal computer with the function expansion device  10  attached thereto.  
         SUMMARY OF THE INVENTION  
         [0010]    It is a general object of the present invention to provide an improved and useful function expansion device for a portable electronic device in which above-mentioned problems are eliminated.  
           [0011]    A more specific object of the present invention is to provide a function expansion device adapted to be attached to a portable electronic device which function expansion device provides a function to use various kinds of information storage media.  
           [0012]    Another object of the present invention is to provide a function expansion device having a size smaller than that of a conventional function expansion device.  
           [0013]    In order to achieve the above-mentioned objects, there is provided according to one aspect of the present invention a function expansion device for expanding a function of a portable electronic device by being detachably attached to the portable electronic device, the function expansion device comprising:  
           [0014]    a unit accommodating part which removably accommodates a functional unit, and  
           [0015]    wherein the functional unit provides a function to be added to said portable device.  
           [0016]    According to the above-mentioned invention, the functional unit can be easily removed from the function expansion device and replaced by a different functional unit which provides a different function to the portable electronic device. That is, one of a plurality of functional units can be selectively accommodated in the unit accommodating part so that different functions can be provided to the portable electronic device. Thus, various functions can be provided to the electronic device with a simple structure and operation.  
           [0017]    In one embodiment of the present invention, the function expansion device includes a bay housing detachably attached to a bottom surface of a notebook-type personal computer as the portable electronic device. The bay housing includes a bay into which a drive unit is inserted. The drive unit can be selected from among a hard disk drive, a floppy disk drive, a CD-ROM drive, a magneto-optical disk drive, a high-capacity floppy disk drive and a digital video disk drive. Each of the drive units has an identical outer configuration so that each of the drive units can be alternatively attached to the bay housing. Accordingly, even if the bay housing has a single bay, various drive units can be connected to the notebook-type personal computer by merely changing the drive units accommodated in the bay housing.  
           [0018]    The function expansion device according to the present invention may further comprise a battery accommodating part which accommodates a battery pack for providing an electric power to at least one of the portable electronic device and the functional unit accommodated in the unit accommodating part.  
           [0019]    The function expansion device according to the above-mentioned invention may further comprise a charging circuit charging the battery pack accommodated in the battery accommodating part.  
           [0020]    Accordingly, the function expansion device can be used as a charger for charging the battery pack which provides an electric power to the portable electronic device.  
           [0021]    Additionally, in the function expansion device according to the present invention, the battery accommodating part may have a configuration the same as that of a battery accommodating part of the portable electronic device so that a battery pack used for the portable electronic device is used as the battery pack to be accommodated in the battery accommodating part of the function expansion device.  
           [0022]    Accordingly, the battery pack accommodated in the function expansion device can be commonly to the battery pack provided in the portable electronic device. Thus, there is no need to prepare a battery pack exclusive for the function expansion device.  
           [0023]    Additionally, in the function expansion device according to the present invention, the functional unit may be an adapter which converts a commercially available voltage into a voltage used by the portable electronic device.  
           [0024]    Accordingly, the function expansion device can be used as a power supply adapter for supplying a DC voltage to the portable electronic device by converting a commercially available AC voltage into the DC voltage suitable for the potable electronic device.  
           [0025]    In the above-mentioned invention, the adapter may include a charging circuit for charging a battery pack provided in the function expansion device.  
           [0026]    Accordingly, the function expansion device can be used as a charger for the battery pack.  
           [0027]    Further, the function expansion device according to the present invention may further comprise a cooling unit for cooling an interior of the function expansion device.  
           [0028]    Accordingly, a drive unit which generates a considerable amount of heat can be attached to the function expansion device.  
           [0029]    Additionally, the function expansion device according to the present invention may further comprise a member which adjusts an angle of the portable electronic device when the function expansion device is mounted to the portable electronic device, the angle being formed between a bottom surface of the function expansion device and a surface on which the portable electronic device is placed.  
           [0030]    Accordingly, the portable electronic device to which the function expansion device according to the present invention is mounted can be operated at an angle according to user&#39;s preference.  
           [0031]    Additionally, in the function expansion device according to the present, an outer configuration of the function expansion device is determined so that an operation related to the portable electronic device is facilitated by the outer configuration of the function expansion device.  
           [0032]    Additionally, there is provided according to another aspect of the present invention an electronic device system comprising:  
           [0033]    an electronic device;  
           [0034]    a plurality of functional units each of which provides a function to be added to the electronic device; and  
           [0035]    a function expansion device detachably attached to the electronic device, the function expansion device including a unit accommodating part which accommodates one of the functional units.  
           [0036]    Additionally, there is provided according to another aspect of the present invention a functional unit providing a function to be added to an electronic device via an attachment which is detachably mounted to the electronic device, the functional unit being detachably attached to the attachment.  
           [0037]    The functional unit according to the present invention may further comprise a converter which converts a commercially available voltage into a voltage suitable for driving the electronic device.  
           [0038]    Additionally, the functional unit may further comprise a charging circuit for charging a battery pack provided in the attachment so that the battery pack is charged by using the commercially available voltage.  
           [0039]    Other objects, features and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAIWINGS  
       [0040]    [0040]FIG. 1 is a perspective view of a conventional function expansion device adapted to be attached to a notebook-type personal computer;  
         [0041]    [0041]FIG. 2 is a perspective view of a notebook-type personal computer and a function expansion device according to a first embodiment of the present invention;  
         [0042]    [0042]FIG. 3 is an illustration for explaining an electrical connection between the function expansion device and the notebook-type personal computer shown in FIG. 2;  
         [0043]    [0043]FIG. 4 is a perspective view of a bay housing shown in FIG. 2;  
         [0044]    [0044]FIG. 5 is a perspective view of the bay housing shown in FIG. 2, viewed from a bottom side.  
         [0045]    [0045]FIG. 6 is a side view of the bay housing shown in FIG. 2;  
         [0046]    [0046]FIG. 7 is an exploded perspective view of the bay housing shown in FIG. 2;  
         [0047]    [0047]FIG. 8A is a perspective view of a battery pack shown in FIG. 2, viewed from a bottom side;  
         [0048]    [0048]FIG. 8B is a perspective view of the battery pack shown in FIG. 2, viewed from a top side;  
         [0049]    [0049]FIG. 9A is a perspective view of a floppy disk drive shown in FIG. 2, viewed from a bottom side;  
         [0050]    [0050]FIG. 9B is a perspective view of a floppy disk drive of the floppy disk drive, viewed from a top side;  
         [0051]    [0051]FIG. 10 is a perspective view of a rear side of a notebook-type personal computer shown in FIG. 2;  
         [0052]    [0052]FIG. 11 is a plan view of a bottom surface of the notebook-type personal computer shown in FIG. 2;  
         [0053]    [0053]FIG. 12 is a perspective view of the notebook-type personal computer used in an expansion mode  1 ;  
         [0054]    [0054]FIG. 13 is a perspective view of a CD-ROM drive shown in FIG. 2;  
         [0055]    [0055]FIG. 14 is a perspective view of the notebook-type personal computer used in an expansion mode  2 ;  
         [0056]    [0056]FIG. 15 is a perspective view of the notebook-type personal computer used in an expansion mode  3 ;  
         [0057]    [0057]FIG. 16 is a perspective view of the notebook-type personal computer used in an expansion mode  4 ;  
         [0058]    [0058]FIG. 17 is a perspective view of the notebook-type personal computer used in an expansion mode  5 ;  
         [0059]    [0059]FIG. 18 is a perspective view of the notebook-type personal computer used in an expansion mode  6 ;  
         [0060]    [0060]FIG. 19 is a perspective view of a part of a bay housing for explaining an operation for attaching a battery pack to the bay housing;  
         [0061]    [0061]FIG. 20 is a perspective view of the notebook-type personal computer for explaining an operation for attaching the bay housing to the notebook-type personal computer;  
         [0062]    [0062]FIG. 21 is side view of the notebook-type personal computer and the function expansion device mounted on the notebook-type personal computer;  
         [0063]    [0063]FIG. 22 is a perspective view of a part of the bay housing for explaining a removing operation of the floppy disk drive;  
         [0064]    [0064]FIG. 23 is diagram for explaining a discriminating circuit;  
         [0065]    [0065]FIG. 24 is an illustration of the notebook-type personal computer with the function expansion device mounted to the notebook-type personal computer;  
         [0066]    [0066]FIG. 25 is a perspective view of the notebook-type personal computer for explaining an operation for attaching the bay housing provided with a battery pack; and  
         [0067]    [0067]FIG. 26 is an illustration for explaining an electrical connection between the function expansion device provided with the battery pack and the notebook-type personal computer shown in FIG. 2. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0068]    A description will now be given, with reference to FIG. 2, of a function expansion device according to a first embodiment of the present invention. FIG. 2 is a perspective view of a notebook-type personal computer system  50  including a notebook-type personal computer  40  and the function expansion device  60  according to the first embodiment of the present invention. In FIG. 2, directions indicated by arrows X 1  and X 2  correspond to a direction of a width of the notebook-type personal computer  40 ; directions indicated by arrows Y 1  and Y 2  correspond to a direction of a depth of the notebook-type personal computer  40 ; directions indicated by arrows Z 1  and Z 2  correspond to a direction of a height or thickness of the notebook-type personal computer  40 . Hereinafter, the directions indicated by arrows X 1 , X 2 , Y 1 , Y 2 , Z 1  and Z 2  are referred to as directions X 1 , X 2 , Y 1 , Y 2 , Z 1  and Z 2 , respectively.  
         [0069]    The function expansion device  60  comprises a bay housing  70 , a floppy disk drive  110 , a CD-ROM drive  130 , a magneto-optical disk drive  140 , a high capacity floppy disc drive  150 , a digital video disk drive  160 , a hard disk drive  170 , an AC/DC adapter  180  and a battery pack  190 .  
         [0070]    A battery pack  190  is attached to the housing bay  70 . Additionally, the housing bay  70  is provided with a portion to which one of the floppy disk drive  110 , the CD-ROM drive  130 , the magneto-optical disk drive  140 , the high-capacity floppy disk drive  150 , the digital video disk device  160 , a hard disk drive  170  and the AC/DC adapter  180  is attached. Thus, there are eight functions which can be provided by selecting one of the above-mentioned drives or units. Thus, extendibility of the function expansion device  60  can provide much wider extendibility than the conventional function expansion device. The function expansion device  60  is attached to the bottom side of the notebook-type personal computer  40 . Additionally, the function expansion device  60  can serves as a charger of the battery pack  190  and also serves as a supporting legs of the notebook-type personal computer  40 .  
         [0071]    When the function expansion device  60  for a notebook-type personal computer is attached to the notebook-type personal computer  40 , the function expansion device  60  and the notebook-type personal computer  40  are electrically connected to each other as shown in FIG. 3 so that the function of the notebook-type personal computer  40  is expanded.  
         [0072]    A description will now be given of each unit constituting the function expanding device  60 .  
         [0073]    (1) The Bay housing  70 :  
         [0074]    The bay housing  70  has approximately a rectangular plate shape. A width A 2  of the housing bay  70  is substantially equal to a width A 1  of the notebook-type personal computer  40 . A depth B 1  of the housing bay  70  is substantially one half of a depth B 2  of the notebook-type personal computer  40 . A thickness C 1  of the bay housing  70  is substantially equal to a thickness of the notebook-type personal computer  40 . Accordingly, the overall size of the bay housing  70  is approximately on half of the overall size of the notebook-type personal computer  40 , and is easily carried. The bay housing  70  is smaller than the conventional function expansion device since the bay housing has a single bay into which the floppy disk drive  110  is inserted. It should be noted that the directions X 1  and X 2  correspond to the longitudinal direction of function expansion device  60 .  
         [0075]    As shown in FIGS. 4, 5,  6  and  7 , the bay housing  70  has a construction in which a lower-half body  71  and an upper-half body  72  are assembled. A bay  73  which is a space for accommodating a drive unit is formed in a half part on the side of the direction X 2 . A battery pack accommodating part  74  and an expansion connector  75  are provided in a half part on the side of the direction X 1 . Additionally, the bay housing  70  has fixed claws  78  and  79  along a Y 1  side of a top surface the  70   a  on the respective sides of the directions X 1  and X 2 . Further, the bay housing  70  has movable claws  78  and  79  along a Y 2  side of a top surface the  70   a  on the respective sides of the directions X 1  and X 2 .  
         [0076]    The bay  73  is a flat space formed between the lower-half body  71  and the upper-half body  72 , and has a contour corresponding to an outer configuration of the floppy disk drive  110 . The bay  73  has an opening  73   a  through which the floppy disk drive  110  is inserted. A notch window  82  is formed on the lower-half body  71  on the side of the opening  73   a . The notch window  82  is provided so as to facilitate an operation for removing the floppy disk drive  110  from the by  73 . A connector  83  is provided in the inner part of the bay  73 .  
         [0077]    A locking mechanism  84  is provided in a part along the Y 2  side of the bay  73  as shown in FIG. 6. The locking mechanism  84  includes a locking claw  85  and an unlocking knob  86  that are integrally formed with each other to form a locking member. The locking member is mounted on the lower-half body  71 . The locking member is urged by a spring  87  in the direction Y 2  so that the locking claw  85  protrudes into the bay  73 . The locking claw can be moved rearward by operating the unlocking knob  86  to slide in the direction Y 1  so that a unit such as the floppy disk drive  110  accommodated in the bay  73  is unlocked and is movable in the direction of removal. As shown in FIG. 7, the movable claws  80  and  81  are fixed to opposite ends of a rod  88  that is supported by the lower-half body  71  at the opposite ends. The movable claws  80  and  81  are urged by a spring  89  in a direction indicated by an arrow D 1 . An arm  91  extends from the rod  88  in a direction perpendicular to the longitudinal direction of the rod  88 . An unlocking knob  92  is provided on an end of the arm  91  so that the unlocking knob  92  is exposed through an opening formed on a bottom surface of  70   b  of the bay housing  70 . The movable claws  80  and  81  and the rod  88  are rotated in a direction indicated by an arrow D 2  against the spring  89  against an urging force of the spring  89  so that the bay housing  70  is unlocked with respect to the notebook-type personal computer  40 . A locking mechanism  93  is provided in relation to the unlocking knob  92 . The unlocking knob  92  is prevented from being operated, that is, the unlocking knob is locked by sliding an operational knob  94  (shown in FIG. 5) exposed from the bottom surface  70   b  of the bay housing  70  in the direction Y 2 . The locking knob  92  is unlocked, that is, the locking knob can be in an operable state by sliding the operational knob  94  in the direction Y 1 .  
         [0078]    The battery pack accommodating part  74  shown in FIG. 4 has a configuration corresponding to the configuration of the battery pack  190  shown in FIGS. 8A and 8B. The battery pack accommodating part  74  is formed in the upper-half body  72 . A terminal  95  and a locking mechanism  96  is provided in relation to the battery pack accommodating part  74 . The locking mechanism  96  includes locking claws  97  and  98  and operational knob  99 . The battery pack  190  has an outer configuration the same as that of the battery pack  47  of the notebook-type personal computer  40 .  
         [0079]    Additionally, a cooling fan  100  is mounted on a back surface of the upper-half body  72 . In relation to the cooling fan  100 , a ventilation opening  102  is formed on the lower-half body  71  so that air outlet from an opening  101  of the cooling fan  100  is discharged from the bay housing  70  in a diagonal direction.  
         [0080]    Tilting legs  76  and  77  are pivotably mounted on the lower-half body  71  as shown in FIG. 5. The tilting legs  76  and  77  are normally folded to sit on the bottom surface  70   b  of the housing bay  70 . Additionally, a charging circuit  103  for charging the battery pack  190  attached to the bay housing  190  is provided in the bay housing  70 .  
         [0081]    Additionally, the bay housing  70  has a slanting surface  70   b  slanting in the direction Z 1  in a part of the bottom surface  70   b  on near the Y 1  side as shown in FIG. 6 so that the housing bay can serve as a base of the notebook-type personal computer  40 . The housing bay  70  is attached on the bottom surface of the notebook-type personal computer  40  in a position near the rear side of the notebook-type personal computer  40 .  
         [0082]    (2) The Floppy Disk Drive  110 :  
         [0083]    As shown in FIG. 2, each of the drive units  110 ,  130 ,  140 ,  150 ,  160  and  170  and the AC/DC adapter  180  has substantially the same outer configuration that is a flat shape so that each of the drive units can be inserted into the bay  73  of the bay housing  70 . The drive units  110 ,  130 ,  140 ,  150 ,  160  and  170  and the AC/DC adapter  180  have connectors  111 ,  131 ,  141 ,  151 ,  161 ,  171  and  181 , respectively, at the same position on their end on the side of the direction X 1 .  
         [0084]    As shown in FIG. 2 and FIGS. 9A and 9B, the floppy disk drive  110  has a flat shape corresponding to bay  73  so that the floppy disc drive  110  can be inserted into the bay  73 . Additionally, the floppy disk drive  110  has the connector  111  on the end in the direction X 1  (the direction of insertion). A turntable  113  (refer to FIG. 2) and a magnetic head  114  (refer to FIG. 2) are provided inside a main body  112  of the floppy disk drive  110 . A floppy disk insertion opening  116  is formed on the main body  112  on an end in the direction X 2 . The main body  112  has a depression  117  for locking on a side surface  112   a  in the direction Y 1  and a depression  118  on a side surface  120   b  in the direction Y 2 . The depression  118  is provided with a connector  119 . Additionally, the main body  112  has a finger engaging part  120  which is exposed through the notch window  82  in a state in which the floppy disk drive  110  is positioned inside the bay housing  70 . The connector  119  can be electrically connected to the notebook-type personal computer  40  via a connector  41   g  (shown in FIG. 10) provided on a rear surface of the notebook-type personal computer  40  and a cable. As also shown in FIG. 12, a floppy disk cartridge  115  is inserted into the floppy drive unit  110  through the insertion opening  116  in the direction X 1 .  
         [0085]    (3) The CD-ROM Drive  130 :  
         [0086]    As shown in FIG. 2, FIG. 13 and FIG. 14, the CD-ROM drive  130  is different from the floppy disk drive  110  in that the CD-ROM drive  130  is not provided with the depression  118  and the connector  119 . Instead, the CD-ROM drive  130  has a connector  131  positioned on an end in the direction X 1  (the direction of insertion), and also has a drawer mechanism  132 . The drawer mechanism  132  includes a turntable  133  and an optical head  134 . A CD-ROM  135  is placed on the turntable  133 .  
         [0087]    (4) The Magneto-optical Disk Drive  140 :  
         [0088]    As shown in FIG. 2 and FIG. 15, the magneto-optical disk drive  140  has the same outer configuration as the CD-ROM drive  130 , and has the connector  141  on an end in the direction X 1  (the direction of insertion). A turntable  142  and an optical head unit  143  are provided inside the magneto-optical disk drive  140 . A magneto-optical disk cartridge  144  is inserted into the magneto-optical disk drive  140  through an insertion opening  145  in the direction X 1  as shown in FIG. 15.  
         [0089]    (5) The High-capacity Floppy Disk Drive  150 :  
         [0090]    As shown in FIG. 2 and FIG. 16, the high-capacity floppy disk drive  150  has the same outer configuration as the CD-ROM drive  130 , and has the connector  151  on an end in the direction X 1  (the direction of insertion). A turntable  152  and a magnetic head unit  153  are provided inside the high-capacity floppy disk drive  150 . A high-capacity floppy disk cartridge  155  is inserted into the high-capacity floppy disk drive  150  through an insertion opening  154  in the direction X 1  as shown in FIG. 16.  
         [0091]    (6) The Digital Video Disk Drive  160 :  
         [0092]    As shown in FIG. 2 and FIG. 17, the digital video disk drive  160  has the same outer configuration as the CD-ROM drive  130 , and has the connector  161  on an end in the direction X 1  (the direction of insertion). The digital disk drive  160  has a drawer  162  which can be drawn in the direction X 2  as shown in FIG. 17. A turntable  163  and an optical head unit  1164  are provided on the drawer  162 . A digital vide disk  165  is placed on the turntable  163 .  
         [0093]    (7) The Hard Disk Drive  170 :  
         [0094]    As shown in FIG. 2 and FIG. 18, the hard disk drive  170  has the same outer configuration as the CD-ROM drive  130 , and has the connector  171  on an end in the direction X 1  (the direction of insertion). A hard disk  171  and a magnetic head unit  173  are provided inside the hard disk drive  170 .  
         [0095]    (8) The AC/DC Adapter  180 :  
         [0096]    As shown in FIG. 2, the AC/DC adapter  180  has the same outer configuration as the CD-ROM drive  130 , and has the connector  181  on an end in the direction X 1  (the direction of insertion). An AC/DC converter  182  is provided inside the AC/DC adapter  180 . A power supply cord  183  extends from an end in the direction X 2 . It should be noted that a bay having the same structure as the bay  73  of the bay housing  70  may be provided on the notebook-type personal computer  40  so as to use the AC/DC adapter  180  as a power supply adapter for the notebook-type personal computer  40  by inserting the AC/DC adapter  180  into the bay provided on the notebook-type personal computer  40 .  
         [0097]    (9) The Battery Pack  190 :  
         [0098]    As shown in FIG. 2 and FIGS. 8A and 8B, the battery pack  190  has substantially a rectangular plate shape. The battery pack  190  has a notched part  191  so that an orientation of the battery pack  190  can be easily recognized. A terminal  192  and claw parts  193  and  194  are provided on a side surface in the direction Y 1 . Additionally, claw parts  195 ,  196  and  197  are provided in a side surface in the direction Y 2 . The battery pack  190  has the same configuration as the battery pack  47  built in the notebook-type personal computer  40 .  
         [0099]    A description will now be given of the notebook-type personal computer  40 .  
         [0100]    As shown in FIG. 2, 10 and  11 , the notebook-type personal computer  40  comprises a main body  41  and a liquid crystal display part  42  which is rotatable with respect to the main body  41 . The main-body  41  has a top surface  41   a , a bottom surface  41   b , a front surface  41   c  in the direction Y 2 , a rear surface  41   d  in the Y 1  direction, a side surface  41   e  in the X 2  direction and a side surface  41   f  in the direction X 1 . The top surface  41   a  of the main body  41  is provided with a keyboard part  43 . As shown in FIG. 10, the rear surface  41   d  of the main body  41  are provided with engaging recessed parts  44   a  and  44   b  near ends in the directions X 1  and X 2 , respectively. As shown in FIG. 11, the bottom surface  44   b  of the main body  41  is provided with a connector  45  and engaging recessed parts  46   a  and  46   b . The engaging recessed parts  44   a  and  44   b  are arranged in positions corresponding to the above-mentioned claw parts  80  and  81  of the bay housing  70 . The connector  45  is arranged in a position corresponding to the connector  95  of the bay housing  70 . The engaging recessed parts  46   a  and  46   b  are arranged in positions corresponding to the claw parts  78  and  79  of the bay housing  70 . The connector  45  is covered by a door  45   a  which can be opened by being pressed.  
         [0101]    The battery pack  47  and a hard disk drive  48  are built in the main body  41  near the Y 2  end on the bottom surface  41   b.    
         [0102]    A description will now be given of the modes of using the bay housing  70 .  
         [0103]    The bay housing  70  can be used in one of the following seven modes.  
         [0104]    Each of FIGS. 12 and 14- 18  show a state of the notebook-type personal computer  40  to which the function expansion device  60  is attached. The function expansion device  60  can be constructed by attaching the battery pack  180  to the battery pack accommodating part  74  of the bay housing  70  and inserting into the bay  73  of the bay housing  70  one of the floppy disk drive  110 , the CD-ROM drive  130 , the magneto-optical disk drive  140 , the high-capacity floppy disk drive  150 , the digital video disk drive  160  and the hard disk drive  170  which is selected by a user. The thus-constructed function expansion device  60  is mounted to a part of the bottom surface  41   b  which part is near the rear side of the notebook-type personal computer  40  by being engaged with the notebook-type personal computer  40  at four positions. The opening  73   a  of the bay  73  of the bay housing  70  is located on the side of the side surface  41   e  of the notebook-type personal computer  40 .  
         [0105]    The function expansion device  60  is constructed in one of the following modes.  
         [0106]    (1) Expansion Mode  1  (Refer to FIG. 12):  
         [0107]    [0107]FIG. 12 shows the expansion mode  1 . The battery pack  190  is attached to the battery pack accommodating part  74 , and the floppy disk drive  110  is inserted into the bay  73  through the opening  73   a  until the entire floppy disk drive  110  is accommodated in the bay  73  as shown in FIG. 2. In this state, the connector  111  of the floppy disk drive  110  is connected to the connector  83  of the notebook-type personal computer  40 , and the locking depression  117  engages the locking claw  85  of the bay housing  70 . Additionally, the insertion opening  116  of the floppy disk drive  110  is positioned on the end in the direction X 2 .  
         [0108]    The battery pack  190  is initially inserted in a diagonal direction into the battery pack accommodating part  74  as indicated by an arrow A in FIG. 19. Then, the battery pack  190  is rotated as shown by an arrow B so as to be accommodated in the battery pack accommodating part  74 . In this state, the terminals  192  of the battery pack  190  is connected to the connector  95  of the pay housing  70 , and the claw parts  193  and  194  of the battery pack  190  are engaged with the locking claws  97  and  98  of the bay housing  70 , respectively.  
         [0109]    The thus-constructed function expansion device  60  is engaged with the bottom surface  41   b  of the notebook-type personal computer  40  in a slanted state as indicated by an arrow C in FIG. 20 so that the claw parts  78  and  79  are fit in the engaging recessed parts  46   a  and  46   b , respectively. Thereafter, the bay housing  70  is rotated toward the notebook-type personal computer  40  as indicated by an arrow D in FIG. 20. In the process of the rotating operation, the claw parts  80  and  81  are temporarily rotated as shown by double dashed chain lines in FIG. 21 against a spring force of the spring  89 , and finally engage with the respective engaging recessed parts  4   a  and  44   b  by being returned to their original positions by the spring force of the spring  89 . The connector  95  presses and opens the door  45   a  and is connected to the connector  45 . Thereafter, the operational knob  94  is slide in the direction Y 2  so as to lock the operational knob  92 .  
         [0110]    The thus-constructed function expansion device  60  is mounted on the notebook-type personal computer  40  as shown in FIG. 21. In the mounted state, the claw parts  78  and  79  are engages with the respective engaging recessed parts  46   a  and  46   b  on the Ys side. Additionally, the claw parts  80  and  81  are engaged with the respective engaging recessed parts  44   a  and  44   b.    
         [0111]    The floppy disk cartridge  115  is inserted into the floppy disk drive  110  through the insertion opening  116  in the direction X 1  as shown in FIG. 12.  
         [0112]    The notebook-type personal computer  40  and the function expansion device  60  mounted to the notebook-type personal computer  40  are electrically connected as shown in FIG. 3 so that data can be exchanged between the notebook-type personal computer  40  and the floppy disc drive  110 . The battery pack  190  supplies a power to both the floppy disk drive  110  and the notebook-type personal computer  40 .  
         [0113]    It should be noted that the bay housing  70  may be mounted to the notebook-type personal computer  40  first, and then the floppy disk drive  110  is inserted into the bay  73 .  
         [0114]    (2) Expansion Mode  2  (Refer to FIG. 14)  
         [0115]    [0115]FIG. 14 shows the expansion mode  2 . In FIG. 14, the CD-ROM drive  130  is attached to the bay  73  of the bay housing  70 . In this state, the CD-ROM drive  130  is locked by the locking claw  85 , and the connector  131  of the CD-ROM drive  130  is connected to the connector  83  of the bay housing  70 . The CD-ROM  135  is attached to the CD-ROM drive  130  in the bay  73 . The notebook-type personal computer  40  and the function expansion device  60  mounted to the notebook-type personal computer  40  are electrically connected as shown in FIG. 3 so that data can be exchanged between the notebook-type personal computer  40  and the CD-ROM drive  130 .  
         [0116]    (3) Expansion Mode  3  (Refer to FIG. 15) FIG. 14 shows the expansion mode  3 . In FIG. 15, the magneto-optical disk drive  140  is attached to the bay  73  of the bay housing  70 . In this state, the magneto-optical disk drive  140  is locked by the locking claw  85 , and the connector  141  of the magneto-optical disk drive  140  is connected to the connector  83  of the bay housing  70 . The magneto-optical disk cartridge  145  is attached to the magneto-optical disk drive  140  in the bay  73 . The notebook-type personal computer  40  and the function expansion device  60  mounted to the notebook-type personal computer  40  are electrically connected as shown in FIG. 3 so that data can be exchanged between the notebook-type personal computer  40  and the magneto-optical disk drive  140 .  
         [0117]    (4) Expansion Mode  4  (Refer to FIG. 16)  
         [0118]    [0118]FIG. 16 shows the expansion mode  4 . In FIG. 16, the high-capacity floppy disk drive  150  is attached to the bay  73  of the bay housing  70 . In this state, the high-capacity floppy disk drive  150  is locked by the locking claw  85 , and the connector  151  of the high-capacity floppy disk drive  150  is connected to the connector  83  of the bay housing  70 . The high-capacity floppy disk cartridge  155  is attached to the high-capacity floppy disk drive  150  in the bay  73 . The notebook-type personal computer  40  and the function expansion device  60  mounted to the notebook-type personal computer  40  are electrically connected as shown in FIG. 3 so that data can be exchanged between the notebook-type personal computer  40  and the high-capacity floppy disk drive  150 .  
         [0119]    (5) Expansion Mode  5  (Refer to FIG. 17)  
         [0120]    [0120]FIG. 17 shows the expansion mode  5 . In FIG. 17, the digital video disk drive  160  is attached to the bay  73  of the bay housing  70 . In this state, the digital video disk drive  160  is locked by the locking claw  85 , and the connector  161  of the digital video disk  160  is connected to the connector  83  of the bay housing  70 . The digital video disk  165  is attached to the digital video disk drive  160  in the bay  73 . The notebook-type personal computer  40  and the function expansion device  60  mounted to the notebook-type personal computer  40  are electrically connected as shown in FIG. 3 so that data can be exchanged between the notebook-type personal computer  40  and the digital video disk drive  160 .  
         [0121]    (6) Expansion Mode  6  (Refer to FIG. 18)  
         [0122]    [0122]FIG. 18 shows the expansion mode  6 . In FIG. 18, the hard disk drive  170  is attached to the bay  73  of the bay housing  70 . In this state, the hard disk drive  170  is locked by the locking claw  85 , and the connector  171  of the hard disk drive  170  is connected to the connector  83  of the bay housing  70 . The notebook-type personal computer  40  and the function expansion device  60  mounted to the notebook-type personal computer  40  are electrically connected as shown in FIG. 3 so that data can be exchanged between the notebook-type personal computer  40  and the hard disk drive  170 .  
         [0123]    It should be noted that the mode of expansion can be changed by changing one of the drive units, for example, the floppy disk drive  110  attached to the bay  73  to another one of the drive units, for example, the CD-ROM  130  in a state in which the bay housing  70  is mounted to the notebook-type personal computer  40 .  
         [0124]    In order to remove the floppy disk from the bay housing  70 , the unlocking knob  86  is slid in the direction Y 1  so as to unlock the locking mechanism  84 . Thereafter, the floppy disk drive  110  can be easily removed from the bay  73  by strongly pressing a finger onto the finger engaging part  120  exposed through the notch window  82  and pulling the floppy disk drive  110  in a direction indicated by an arrow A shown in FIG. 22 the CD-ROM drive  130 , for example, can be attached to the bay  73  by simply inserting it into the bay  73 . Accordingly, the operation for changing the mode of expansion is easy.  
         [0125]    A discriminating unit  210  shown in FIG. 23 discriminates one of the floppy disk drive  110 , the CD-ROM drive  130 , the magneto-optical disk drive  140 , the high-capacity floppy disk drive  150 , the digital video disk drive  160 , the hard disk drive  170  and the AC/DC adapter  180  which one is attached to the bay housing  70 . The discriminating unit  210  has three ID lines ID 1 , ID 2  and ID 3  so that one of the lines connected to the ground differs from drive to drive which is attached to the bay housing  70 . That is, each of the eight types of the drive units can be discriminated based on a combination of a high signal “ 1 ” and a low signal “ 0 ” of the three ID lines Id 1 , ID 2  and ID 3 . More specifically, for example, when the floppy disk drive  110  is attached to the bay housing  70 , the signal level of the ID lines becomes “ 001 ” whereas the signal level becomes “ 000 ” when the CD-ROM drive  130  is attached to the bay housing  70 .  
         [0126]    It should be noted that since the operational knob  92  is locked by the operational knob  94 , the bay housing  70  cannot be unintentionally removed from the notebook-type personal computer  40 . The bay housing  70  can only be removed from the notebook-type personal computer  40  by sliding the operational knob  94  in the direction Y 1  so as to unlock the operational knob  92  and disengaging the claw parts  80  and  81  from the respective engaging recessed parts  44   a  and  44   b  by pressing the operational knob  92 .  
         [0127]    A description will now be given of a state of the notebook-type personal computer  40  placed on a table with a mode of expansion.  
         [0128]    The notebook-type personal computer  40  can be placed on a surface  220  of a table in a tilted state as shown in FIGS. 21 and 24. In the state shown in FIGS. 21 and 24, the tilting legs  76  and  77  are raised so that the notebook-type personal computer  40  is supported by the tilting legs  76  and  77 , the slanting surface  70   b   1  and a part  41   b   1  of the bottom surface  41   b  of the main body  41  of the notebook-type personal computer  40 . In this state, the keyboard part  43  of the notebook-type personal computer  40  is slightly slanted so as to facilitate a key operation. That is, the bay housing  70  can serve as a stand for the notebook-type personal computer  40  when the tilting legs  76  and  77  are raised.  
         [0129]    The bay housing  70  is separated from the surface  220  of the table so that a space  221  is formed between the bottom surface  70   b  of the bay housing  70  and the surface  220  of the table. Additionally, as shown in FIG. 24, when the cooling fan  100  is operated, air is outlet through the ventilation opening  102  in a diagonal direction as indicated by an arrow A. Accordingly, the space  221  is efficiently ventilated. Thus, heat under the bottom surface  70   b  of the bay housing  70  is efficiently released, and the function expansion device  60  (the bay housing  70 ) can be efficiently cooled. If the cooling fan  100  is a type which draws air through ventilation opening  102 , the air in the space  221  is also efficiently exchanged, and, thereby the function expansion device  60  can be efficiently cooled. It should be noted that if the cooling fan  100  is not provided and only the ventilation opening  102  is formed, a heat if released from the bottom surface  70   b  of the bay housing  70  by natural cooling.  
         [0130]    It is also be noted that the bay housing  70  may be used without raising the tilting legs  76  and  77  and the entire bottom surface  70   b  is made contact with the surface  220  of the table so that the bay housing  70  is used as a stand for supporting the notebook-type personal computer  40 . In the above-mentioned structure of the bay housing, since the tilting legs  76  and  77  are raised only when it is necessary, the entire thickness (height) of the function expansion device  60  can be smaller than when the entire bottom surface  70   b  of the bay housing  70  is inclined with respect to the notebook-type personal computer  40 .  
         [0131]    A description will now be given, with reference to FIGS. 25 and 26, of accommodation of the AC/DC adapter  180 .  
         [0132]    As shown in FIG. 25, the AC/DC adapter  180  is carried together with the bay housing  70  in a state in which the AC/DC adapter  180  is accommodated in the bay  73  of the bay housing  70 . Accordingly, a good portability can be provided as compared to a case in which the AC/DC adapter  180  is carried separately from the bay housing  70 .  
         [0133]    The bay housing  70  in which the AC/DC adapter  180  is accommodated is mounted to the notebook-type personal computer  40  as shown in FIG. 23. Accordingly, the notebook-type personal computer  40  can be operated by a commercially available power source.  
         [0134]    Additionally, as shown in FIG. 26, an AC voltage of the commercially available power source is converted into a DC voltage by the charging circuit  103  so as to charge the battery pack  190  accommodated in the battery pack accommodating part  74 . It should noted that the battery pack  190  can be charged in a state in which the bay housing  70  is separated from the notebook-type personal computer  40 . Accordingly, the bay housing  70  can serve as a charger by accommodating the AC/DC adapter  180 . Additionally, the battery pack  47  of the notebook-type personal computer  40  can be charged by using the AC/DC adapter  180 .  
         [0135]    Since the battery pack  190  is identical to the battery pack  47  of the notebook-type personal computer  40 , the battery pack  190  can be used as the battery pack  47  of the notebook-type personal computer  40  after a power of the battery pack  47  has been completely consumed by removing the battery pack  47  from the notebook-type personal computer  40  and attaching the battery pack  190  to the notebook-type personal computer  40 .  
         [0136]    Additionally, the charge circuit  103  may be provided in the AC/DC adapter  180 . In such a case, the battery pack  47  of the notebook-type personal computer  40  can be charged without providing a charging circuit in the main body of the notebook-type personal computer  40 .  
         [0137]    It should be noted that the bay housing  70  may be connected to the notebook-type personal computer by a cable. Additionally, the charging circuit  103  may be provided outside the bay housing  70  so that a housing of the charging circuit  103  may be provided under the bay housing  70 . In such a case, the housing of the charging circuit  103 , the bay housing  70  (the function expansion device  60 ) and the notebook-type personal computer  40  are mounted one on another in that order.  
         [0138]    The present invention is not limited to the specifically disclosed embodiments, and variations and modification may be made without departing from the scope of the present invention.  
         [0139]    The present application is based on Japanese priority application No. 10-260602 filed on Sep. 14, 1998, the entire contents of which are hereby incorporated by reference.