Abstract:
An information processing device has a pair of projections joined to a display unit and angularly movable about an axis which is disposed in a position vertically spaced a predetermined distance from a display panel of the display unit, and a pair of supports. The projections are angularly movably supported by the supports such that the axis is positioned within the main unit.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an information processing device having a display unit which is foldable with respect to a main unit. 
     DESCRIPTION OF THE RELATED ART 
     In recent years, many portable information processing devices called note-type personal computers or mobile computers are available as products. Such an information processing device has a main unit and a display unit which can be opened and closed with respect to the main unit by hinges. 
     FIG. 28 is a perspective view of a computer as a conventional information processing device with a display unit opened with respect to a main unit, and FIG. 29 is a side elevational view of the computer. 
     The computer, denoted by  500 , comprises a main unit  510  and a display unit  520  openably and closably attached thereto by a hinge  530 . The hinge  530  comprises a projection  531  mounted on a substantially central portion of the main unit  510  and a recess  532  defined in a substantially central portion of the display unit  520  and fitted over the projection  531 . 
     FIG. 30 is a perspective view of another computer as a conventional information processing device with a display unit opened with respect to a main unit, and FIG. 31 is a side elevational view of the computer. 
     The computer, denoted by  600 , comprises a main unit  610  and a display unit  620  openably and closably attached thereto by a pair of hinges  630 . A battery pack  640  is detachably disposed between the hinges  630 . 
     When the conventional computers  500 ,  600  are used on a desktop, the user moves its line of sight between keyboards  511 ,  611  on the main units  510 ,  610  and display panels  521 ,  621  of the display units  520 ,  620  as shown in FIGS. 29 and 31. It is assumed that the main units  510 ,  610  and the display units  520 ,  620  have the same width a, the display panels  521 ,  621  have the same width b, the keyboards  511 ,  611  have the same width c, and regions of the display units  520 ,  620  beneath the display panels  521 ,  610  where boards can be housed have the same distance d. It is also assumed that a central axis  630   a  of the hinges  630  is spaced from a lower end  621   a  of the display panel  621  by a distance d 2 . 
     It can be understood that minimum angles α 1 , α 2  through which the user&#39;s line of sight moves, i.e., angles formed at the viewpoint E between upper ends  511   a ,  611   a  of the keyboards  511 ,  611  and lower ends  521   a ,  621   a  of the display panels  521 ,  621 , and maximum angles β 1 , β 2  through which the user&#39;s line of sight moves, i.e., angles formed at the viewpoint E between lower ends  511   b,    611   b  of the keyboards  511 ,  611  and upper ends  521   b,    621   b  of the display panels  521 ,  621  are greatly affected by the relative positional relationship between the central axes  530   a ,  630   a  of the hinges  530 ,  630 . 
     The central axes  530   a ,  630   a  of the hinges  530 ,  630  are disposed outwardly and upwardly of the main units  510 ,  610  on and parallel to extensions of the display panels  521 ,  621 . The display panels  521 ,  621  are spaced from the central axes  530   a ,  630   a  by the distance d across the regions where the board or the like can be housed. Therefore, both the minimum angles α 1 , α 2  through which the user&#39;s line of sight moves and the maximum angles β 1 , β 2  through which the user&#39;s line of sight moves are large. When the user uses the computer over a long period of time, the user tends to suffer from a growing fatigue and the efficiency with which to work with the computers is liable to decrease. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an information processing device which eliminates the above drawbacks, can easily be used, and can be operated with increased efficiency. 
     According to the present invention, the above object can be achieved by an information processing device having a main unit for executing a predetermined information processing operation and a display unit openable and closable with respect to the main unit, characterized by a pair of projections joined to the display unit and angularly movable about an axis which is disposed in a position vertically spaced a predetermined distance from a display panel of the display unit, and a pair of supports, the projections being angularly movably supported by the supports such that the axis is positioned within the main unit. 
     With the above arrangement, since the display unit has a rear portion that is offset from the supports by the length of the projections, a front surface of the rear portion of the display unit is turned along a rear portion of the main unit. Therefore, if the display unit is unfolded to an angle for use, then the rear portion of the display unit is turned over behind the main unit, reducing the distance between the central axis of an opening and closing mechanism and the lower end of the display panel and hence reducing minimum and maximum angles through which the line of sight of the user moves. Consequently, the user is less liable to fatigue from using the information processing device over a long period of time, and the efficiency with which to work with the information processing device increases. 
     The above and other objects, features, and advantages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings which illustrate a preferred embodiment of the present invention by way of example. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a portable computer having a display unit that is openable and closable with respect to a main unit, as an embodiment of an information processing device according to the present invention; 
     FIG. 2 is a plan view of the computer shown in FIG. 1 with the display unit opened substantially 180 degrees with respect to the main unit; 
     FIG. 3 is a plan view of the computer shown in FIG. 1 with the display unit closed with respect to the main unit as viewed from the display unit side; 
     FIG. 4 is a plan view of the computer shown in FIG. 3 as viewed from the main unit side; 
     FIG. 5 is a front elevational view of the computer shown in FIG. 3; 
     FIG. 6 is a rear elevational view of the computer shown in FIG. 3; 
     FIG. 7 is a right side elevational view of the computer shown in FIG. 3; 
     FIG. 8 is a left side elevational view of the computer shown in FIG. 3; 
     FIGS. 9A and 9B are side elevational and plan views showing details of a hinge (first opening and closing mechanism) of the computer shown in FIG. 1; 
     FIGS. 10A and 10B are side elevational and plan views showing details of a hinge (second opening and closing mechanism) of the computer shown in FIG. 1; 
     FIG. 11 is a first partly sectional side elevational view showing the manner in which the display unit is opened with respect to the main unit while the computer with the battery pack mounted therein as shown in FIG. 1 is placed on a desktop; 
     FIG. 12 is a second partly sectional side elevational view showing the manner in which the display unit is opened with respect to the main unit while the computer with the battery pack mounted therein as shown in FIG. 1 is placed on the desktop; 
     FIG. 13 is a third partly sectional side elevational view showing the manner in which the display unit is opened with respect to the main unit while the computer with the battery pack mounted therein as shown in FIG. 1 is placed on the desktop; 
     FIG. 14 is a fourth partly sectional side elevational view showing the manner in which the display unit is opened with respect to the main unit while the computer with the battery pack mounted therein as shown in FIG. 1 is placed on the desktop; 
     FIG. 15 is a side elevational view of the computer shown in FIG. 1 with the display unit opened with respect to the main unit; 
     FIG. 16 is a perspective view showing a computer as a conventional information processing device with a display unit opened with respect to a main unit; 
     FIG. 17 is a side elevational view of the computer shown in FIG. 16; 
     FIG. 18 is a perspective view illustrative of problems of the computer shown in FIG. 16; 
     FIG. 19 is a perspective view illustrative of problems of the computer shown in FIG. 16; 
     FIG. 20 is a view showing an internal structure of the display unit at the time a nonmetal casing covering the front surface of the display unit is detached: 
     FIGS. 21A,  21 B, and  21 C are a view of an antenna module shown in FIG.  1  and surrounding areas as seen from the outside of the display unit, a view thereof as seen from the inside of the display unit, and a cross-sectional view taken along line A—A of FIG.  21 A: 
     FIGS. 22A,  22 B, and  22 C are a plan view of a battery pack of the computer shown in FIG. 1, a side elevational view of the battery pack, and a right side elevational view of the battery pack; 
     FIG. 23 is a perspective view of the battery pack of the computer shown in FIG. 1; 
     FIG. 24 is a plan view of the computer shown in FIG. 1 before the battery pack is inserted therein; 
     FIG. 25 is a plan view of the computer shown in FIG. 1 after the battery pack is inserted therein; 
     FIG. 26 is a side elevational view of the computer shown in FIG. 1 before the battery pack is inserted therein; 
     FIG. 27 is a side elevational view of the computer shown in FIG. 1 after the battery pack is inserted therein; 
     FIG. 28 is a perspective view of a computer as a conventional information processing device with a display unit opened with respect to a main unit; 
     FIG. 29 is a side elevational view of the computer shown in FIG. 28; 
     FIG. 30 is a perspective view of another computer as a conventional information processing device with a display unit opened with respect to a main unit; and 
     FIG. 31 is a side elevational view of the computer shown in FIG.  30 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A preferred embodiment of the present invention will hereinafter be described in detail with reference to the drawings. 
     Since the embodiment which will be described below is a preferred embodiment of the present invention, it is limited by various details that are technically preferable. However, the present invention is not limited to those details unless otherwise specified in the description that follows. 
     FIG. 1 is a perspective view of a portable computer having a display unit that is openable and closable with respect to a main unit, as an embodiment of an information processing device according to the present invention. FIG. 2 is a plan view of the computer shown in FIG. 1 with the display unit opened substantially 180 degrees with respect to the main unit, and FIGS. 3 through 8 are a plan view of the computer with the display unit closed with respect to the main unit, as view from the display unit side, a plan view as viewed from the main unit side, a front elevational view, a rear elevational view, a right side elevational view, and a left side elevational view. 
     The computer, denoted by  100 , comprises a main unit  2  and a display unit  3  which are openable and closable (foldable and unfoldable) in the directions indicated by the arrows R by a hinge  1 A (first opening and closing mechanism) and a hinge  1 B (second opening and closing mechanism), described in detail later, that are enclosed in areas A, B. The computer  100  also has a battery storage region  2   a  disposed between the hinges  1 A,  1 B in which a battery pack, described in detail later, can removably be stored. Confronting surfaces of the main unit  2  and the display unit  3  are referred to as upper and front surfaces, respectively, and opposite surfaces of the main unit  2  and the display unit  3  as lower and rear surfaces, respectively. 
     As shown in FIGS. 1 and 2, the main unit  2  has a keyboard  11 , a pointing device  12 , etc. on the upper surface thereof, and covered with a nonmetal casing  2 A made of plastics or the like. As shown in FIG. 4, the lower surface of the main unit  2  has an air inlet hole  21  of a cooling fan that is disposed in the main unit  2 , a pair of legs  22 , and slidable removal levers  23  for removing the battery pack from the battery storage region  2   a , and is covered with a metal casing  2 B made of magnesium alloy, aluminum alloy, or the like. 
     As shown in FIGS. 1 and 2, the front surface of the display unit  3  has a liquid crystal display (LCD)  31  or the like, and is covered with a nonmetal casing  3 A made of plastics or the like. As shown in FIG. 3, the rear surface of the display unit  3  is covered with a metal casing  3 B made of magnesium alloy, aluminum alloy, or the like except an antenna cover  41  which covers an antenna, described in detail later. A pair of protectors  42  is disposed on the rear surface of the display unit  3  near the hinges  1 A,  1 B, the protectors  42  slightly projecting from the rear surface of the display unit  3  for protecting the end of the display unit  3  against damage due to frictional engagement with the surface of the desktop. 
     As shown in FIGS. 1 and 5, a pair of speakers  51  is disposed on a front side of the main unit  2 , and an antenna cover  61  covering an antenna and a slide lever  62  for releasing a tooth  32  projecting from the front surface of the display unit  3  from a hole  13  defined in the upper surface of the main unit  2  are disposed on a front side of the display unit  3 . 
     As shown in FIG. 6, battery connectors  71 ,  72  for electrically and mechanically connecting the battery pack are disposed in the battery storage region  2   a  in a rear side of the main unit  2 . 
     As shown in FIGS. 1 and 7, the main unit  2  has on its right side a headphone terminal  81 , a jog dial  82 , a PC card slot  83  for accommodating a PC (Personal Computer) card according to the PCMCIA (Personal Computer Memory Card International Association) standards, a 4-pin IEEE (Institute of Electrical and Electronics Engineers) 1394 terminal  84 , and a modem terminal  85  for a modular jack. 
     The jog dial  82  has a side surface partly projecting from the right side of the main unit  2  and an upper surface partly projecting from the upper surface of the main unit  2  so as to lie flush with the keys of the keyboard  11 . 
     The jog dial  82  is a user interface that can easily be operated to perform system settings and various functions of various software applications with ease by rotating and pressing the dial. As shown in FIGS. 1 and 2, the jog dial  82  has a flat disk-shaped control knob  82   a  which can be rotated in the direction indicated by the arrow a or b to execute certain processing and which can also be pressed in the direction indicated by the arrow c to execute certain processing. 
     As shown in FIGS. 1 and 8, the main unit  2  has on its left side a memory stick slot  91  for a memory stick serving as a memory card, an USB (Universal Serial Bus) terminal  92 , an external display connector  93 , an air discharge hole  94 , and an external power supply connector  95 . 
     A transparent plate  14  is fitted in a portion of the upper surface of the main unit  2  which is aligned with the memory stick slot  91  for allowing the user to confirm the label of a memory stick, which has been inserted into the memory stick slot  91 , from above the upper surface of the main unit  2  through the transparent plate  14 . 
     FIGS. 9A and 9B are left side elevational and plan views, respectively, showing details of the hinge (first opening and closing mechanism)  1 A with the nonmetal casing  2 A removed from the main unit  2  and the nonmetal casing  3 B removed from the display unit  3 . 
     The hinge  1 A comprises a projection  101  fixed by a screw to a side end of the metal casing  3 B of the display unit  3  so as to project substantially perpendicularly to the display panel of the LCD  31  of the display unit  3 , and a support  102  fixed by a screw to a side end of the main unit  2 . The projection  101  having a tip end portion is rotatably supported by the support  102 . 
     The projection  101 , which is substantially L-shaped, is made of a material of large mechanical strength, e.g., stainless steel (SUS) that is an iron-based material, in order to keep the display unit  3  strong when it is opened and closed. The projection  101  has an end fixed by a screw to a side end of the display unit  3  and an opposite end rotatably supported on the support  102 . 
     The support  102  comprises a strength holder  103  which holds a mechanical strength and a joint  104  to which the projection  101  is joined. The strength holder  103  , which is substantially L-shaped, is made of, a material of large mechanical strength, e.g., stainless steel (SUS) that is an iron-based material, in order to keep the display unit  2  strong when it is opened and closed and also to ensure opening and closing actions of the display unit  2 . The joint  104  comprises a shaft  104   a  supported by the strength holder  103 , and a stopper  104   b  and a washer spring  104   c  that are fitted over the shaft  104   a.  The opposite end of the projection  101  is fitted over the shaft  104   a,  and integrally joined thereto by the stopper  104   b  and the washer spring  104   c.    
     FIGS. 10A and 10B are plan and right side elevational views, respectively, showing details of the hinge  1 B (second opening and closing mechanism) with the nonmetal casing  2 A removed from the main unit  2  and the nonmetal casing  3 B removed from the display unit  3 . 
     The hinge  1 B comprises a projection  111  fixed by a screw to the other side end of the display unit  3  so as to project substantially perpendicularly to the display panel of the LCD  31  of the display unit  3 , and a support  112  fixed by a screw to the other side end of the main unit  2 . The projection  111  having a tip end portion is rotatably supported by the support  112 . 
     The projection  111  and the support  112  are substantially identical in structure to the projection  101  and the support  102  of the hinge  1 A, but differ therefrom in that the support  112  has a joint  114  that is centrally hollow for passage of wires, etc. 
     The hinges  1 A,  1 B allow the projections  101 ,  111  to rotate in the direction indicated by the arrow R in FIG. 1 with respect to the supports  102 ,  112 . Since the display unit  3  may be provided with only the projections  101 ,  111 , a space within a lower portion of the display unit  3 , i.e., a space below the LCD  31 , can effectively be utilized. 
     FIGS. 11 through 14 are partly sectional side elevational views showing the manner in which the display unit  3  is opened with respect to the main unit  2  while the computer  100  with the battery pack mounted therein is placed on a desktop. 
     As shown in FIG. 11, when the computer  101  is placed on a desktop, for example, the rear portion of the computer  100  is raised higher than the front portion thereof by the legs  22 , i.e., the computer  100  is tilted toward the user. The legs  22  have rubber sheets  22   a , for example, applied to their bottoms, holding the computer  100  stable against slipping on the desktop. 
     As shown in FIG. 12, the slide lever  62  is slid to slide the tooth  32  projecting from the front surface of the display unit  3  out of locking engagement with the hole  13  defined in the upper surface of the main unit  2 , and the display unit  3  is unfolded from the main unit  2 . At this time, since the rear portion of the display unit  3  is offset from the supports  102 ,  112  by the length of the projections  101 ,  111 , the rear portion of the display unit  3  is turned along the rear portion of the main unit  2 . As the rear portion of the main unit  2  is lifted off the surface of the desktop by the legs  22 , even when the display unit  3  is opened more than 90 degrees from the main unit  2 , the rear portion of the display unit  3  is not held in abutment against the surface of the desktop, allowing the display unit  3  to be unfolded smoothly. 
     As shown in FIG. 13, the display unit  3  is unfolded from the main unit  2  to an angular position in which the user can easily view the LCD  31  of the display unit  3 . FIG. 15 is a side elevational view corresponding to the views of the conventional computers  500 ,  600  shown in FIGS. 29 and 31. In FIG. 15, the main unit  2  and the display unit  3  have the width a, the LCD  31  has the width b, the keyboard has the width c, and a region of the display unit  3  beneath the LCD  31  where a board can be housed has the distance d. Since the display unit  3  is arranged so as to be perpendicular to the projections  101 ,  111  that project radially from the central axes  1   a,    1   b  of the hinges  1 A,  1 B disposed in the main unit  2 , the rear portion of the display unit  3  is turned behind the main unit  2 , bringing the LCD  31  closer to the keyboard  11 . Stated otherwise, the distance do between the central axes  1   a ,  1   b  of the hinges  1 A,  1 B of the computer  100  and the lower end  31   a  of the LCD  31  becomes smaller than the distance d of the region of the display unit  3  beneath the LCD  31  where a board can be housed. 
     Therefore, an minimum angle α 0  through which the user&#39;s line of sight to the computer  100  moves, i.e., angles formed at the viewpoint E between the upper end  11   a  of the keyboard  11  and the lower end  31   a  of the LCD  31 , and a maximum angle β 0  through which the user&#39;s line of sight to the computer  100  moves, i.e., an angle formed at the viewpoint E between the lower end  11   b  of the keyboard  11  and the upper end  31   b  of the LCD  31  are smaller than the minimum angles α 1 , α 2  through which the user&#39;s line of sight moves and the maximum angles β 1 , β 2  through which the user&#39;s line of sight moves with respect to the conventional computers  500 ,  600 . Therefore, since the user&#39;s eyes need to move a shorter distance, the user is less liable to fatigue from use over a long period of time, and the efficiency with which to work with the computer increases. 
     As shown in FIG. 14, as the display unit  3  is further unfolded from the main unit  2 , the display unit  3  and the main unit  2  can be held substantially horizontally. At this time, inasmuch as the protectors  42  slightly projecting from the rear portion of the display unit  3  protect the rear portion of the display unit  3 , the rear portion of the display unit  3  is prevented from being scratched from frictional engagement with the surface of the desktop. 
     The computer  100  of the above construction further offers the following advantages: 
     FIG. 16 is a perspective view showing a computer as a conventional information processing device with a display unit opened with respect to a main unit, and FIG. 17 is a side elevational view of the computer. The computer, denoted by  400 , has a display unit  420  openably and closably attached to a main unit  410  by a pair of hinges  430 . A battery pack  440  is removably disposed between the hinges  430 . 
     The computer  400  is spaced from the surface of a desktop by a leg  411  mounted on the lower surface of a front portion of the main unit  410 , and a leg  441  mounted on the lower surface of the battery pack  440 . Air for cooling electronic parts in the computer is introduced from an air inlet hole, not shown, defined in the lower surface of the main unit  410 . 
     When the conventional computer  400  is displayed for sale with the display unit  420  opened with respect to the main unit  410 , the battery pack  440  is usually removed for theft prevention. However, since the lower end of the display unit  420  is opened and closed along the outer circumference of the hinges  430 , as shown in FIG. 18, a hole  440   a  from which the battery pack  440  is removed is left between the main unit  410  and the display unit  420 , making the computer  400  unsightly in appearance. 
     With the computer  100  according to the present embodiment, however, as shown in FIG. 13, the battery storage region  2   a  from which the battery pack has been removed is concealed by an extension  2 AA of the nonmetal casing  2 A made of plastics or the like which covers the upper surface of the main unit  2 . Therefore, no hole is left for view, making the computer  100  sightly in appearance. 
     When the battery pack  440  is removed from the computer  400  and the computer  400  is used with an AC power supply, as shown in FIG. 19, the computer  400  is supported by the leg  411  on the lower surface of the front portion of the main unit  410  and the lower surface of the rear portion of the main unit  410 . Therefore, the air inlet hole defined in the lower surface of the main unit  410  is partly closed by the surface of the desktop, making it impossible to sufficiently cool the electronic parts in the computer  400 . 
     With the computer  100  according to the present embodiment, however, as shown in FIG. 13, when the battery pack is removed from the computer  100  and the computer  100  is used with an AC power supply, the air inlet hole  21  defined in the lower surface remains spaced from the surface of the desktop by the legs  22  on the main unit  2 . As the air inlet hole  21  is not closed, electronic parts in the computer  100  can sufficiently be cooled. 
     With the conventional computer  400 , as shown in FIG. 19, since the main unit  410  is tilted downwardly toward the display unit  420 , the computer  400  tends to turn over toward the unfolded display unit  420 . Therefore, the display unit  420  cannot be opened and closed smoothly. 
     With the computer  100  according to the present embodiment, however, as shown in FIG. 13, the legs  22  support the computer  100  even when no battery pack is mounted in the computer  100 . Therefore, the main unit  2  is stably held on the surface of the desktop, and the display unit  3  can be opened and closed when the battery pack is not mounted in the same manner as when the battery pack is mounted in place. 
     FIG. 20 is a view showing an internal structure of the display unit  3  at the time the nonmetal casing  3 A covering the front surface of the display unit  3  is detached. 
     A light source circuit (inverter circuit)  33  for the LCD  31  is disposed beneath the LCD  31 . A driver circuit  34  for the LCD  31  is disposed on a left side of the LCD  31 . An antenna module  35  is disposed upwardly of the LCD  31 . A transmission/reception module  36  is disposed on a right side of the LCD  31 . 
     As described above, only the projections  101 ,  111  of the hinges  1 A,  1 B need to be provided on the display unit  3  side. Therefore, a space within a lower portion of the display unit  3 , i.e., a space below the LCD  31 , can effectively be utilized. Heretofore, a light source circuit (inverter circuit) has been disposed on the right side of the LCD. In the present embodiment, the light source circuit (inverter circuit)  33  for the LCD  31  is disposed beneath the LCD  31 , the transmission/reception module  36  is disposed on the right side of the LCD  31 , and the antenna module  35  is disposed upwardly of the LCD  31  in the vicinity of the transmission/reception module  36  preferably from a sensitivity viewpoint for compatibility with Bluetooth. 
     Bluetooth (hereinafter referred to as BT) refers to close-range wireless communication technology whose standardization was started in May 1998 by five Japanese, European, and U.S. companies. According to the BT process, a maximum data transmission rate is 1 Mbits/second (effectively, 721 kbits/second), and a maximum transmission range is 10 m. 79 channels having a bandwidth of 1 MHz are established in a 2.4 GHz ISM (Industrial Scientific) band that can be used by users without licenses, and radio waves are transmitted according to a frequency-hopping spread spectrum process where channels are switched 1600 times per second. 
     BT-compatible devices are divided into master units for determining a frequency hopping pattern and slave units to communicate with master units. A master unit can communicate with seven slave units at one time. A subnet that is composed of a maximum of 8 master and slave units is called a piconet. Slaves of a piconet can simultaneously become slave units of two or more piconets. 
     FIGS. 21A,  21 B, and  21 C are a view of the antenna module  35  and surrounding areas as seen from the rear side of the display unit  3 , a view thereof as seen from the front side of the display unit  3 , and a cross-sectional view taken along line A—A of FIG.  21 A. 
     The antenna module  35  comprises a BT antenna  35   a  for BT communications and a connector  35   b  for connection to the transmission/reception module  36 , the BT antenna  35   a  and the connector  35   b  being installed on a board  35   c.    
     The antenna module  35  is incorporated in the display unit  3  for portability and aesthetic reasons. The rear side of the display unit  3  is covered with the metal casing  3 B. If the BT antenna  35   a  were fully covered with the metal casing  3 B, it would impair the transmission and reception of radio waves. Therefore, the antenna module  35  is disposed such that the BT antenna  35   a  is positioned above the display unit  3  and slightly projects upwardly from an upper end UP of the metal casing  3 B, and the antenna module  35  including the projection of the BT antenna  35   a  is covered with an antenna cover  61  which comprises a nonmetal member made of plastics or the like. The antenna module  35  may be disposed such that the BT antenna  35   a  projects as a whole upwardly from the upper end of the metal casing  3 B. The BT antenna  35   a  thus projecting upwardly provides improved radio wave transmission/reception characteristics on the left and right sides of the display unit. 
     The metal casing  3 B has a recess  37  wherein the antenna module  35  is disposed for increased sensitivity of the BT antenna  35   a . The recess  37  is defined such that the distance d 1  between a left end of the recess  37  shown in FIG. 21A and a high-sensitivity side of the BT antenna  35   a , i.e., an end of the BT antenna  35   a  opposite to a feeder port  35   aa  thereof, is greater than the distance d 2  between a right end of the recess  37  shown in FIG.  21 A and the feeder port  35   aa  of the BT antenna  35   a . The recess  37  is covered with an antenna cover  41  which comprises a nonmetal member made of plastics or the like. 
     The BT antenna  35   a  on the board  35   c  in the antenna module  35  is directed outwardly of the display unit  3 , as shown in FIG.  21 C. However, the BT antenna  35   a  on the board  35   c  may be directed inwardly of the display unit  3 . 
     As shown in FIG. 20, the transmission/reception module  36  comprises an RF processor  36   a  connected to the connector  35   b  which is electrically connected to the feeder port  35   aa  of the antenna module  35 , and a baseband processor  36   b  connected to a microcomputer in the main unit  2 , the RF processor  36   a  and the baseband processor  36   b  being mounted on a board  36   c.    
     Transmission data to be transmitted via BT communications is generated by the microcomputer and transferred to the baseband processor  36   b.  The baseband processor  36   b  converts the transmission data from the microcomputer into packets for BT communications. At this time, the baseband processor  36   b  adds code detecting and correcting codes and various communication data to the converted data. The data generated by the baseband processor  36   b  is transferred to the RF processor  36   a,  which converts the data into analog data for transmission. 
     The RF processor  36   a  modulates the transferred digital data, and transmits on a radio wave carrier in the 2.4 GHz band from the BT antenna  35   a . The radio wave carrier has a frequency selected for a different slot (one lump of date) by a frequency hopping process. 
     A signal received by the BT antenna  35   a  is demodulated and converted into digital data by the RF processor  36   a.  Thereafter, the data is checked for errors by the baseband processor  36   b.  Then, the data is transferred to the microcomputer, which performs corresponding processing on the data. 
     FIGS. 22A,  22 B, and  22 C are a plan view of the battery pack, a side elevational view of the battery pack, and a right side elevational view of the battery pack. The battery pack, denoted by  200 , comprises a lithium-ion secondary cell housed in a case  201 . Since the space is provided in front of the air inlet hole  21  defined in the lower surface of the main unit  2 , as described above, the battery storage region  2   a  in the main unit  2  is of a size that can be at least twice the size of the conventional battery storage region. Therefore, the case  201  can be of a size which is at least twice the size of the conventional case, and is molded of plastics, for example. The case  201  can thus hold a plurality of cells at least twice as many as the cells in the conventional case, e.g. two arrays of cells as compared with one array of cells in the conventional case. 
     The battery pack  200  is inserted by being guided between the hinges  1 A,  1 B, and is mechanically and electrically connected to the main unit  2 . The battery pack  200  and the main unit  2  have a guide mechanism and a connection mechanism which allow the battery pack  200  to be detachably placed in the main unit  2 . 
     Specifically, as shown in FIGS. 22A to  22 C and  23 , the case  201  has a pair of attachments  202 , an electric connection terminal  203 , and a pair of grooves  204  on its outer surfaces. The attachments  202  project from a surface of the case  201  for abutment against the main unit  2 . The electric connection terminal  203  projects from the surface of the case  201  for abutment against the main unit  2  and is positioned between the attachments  202 . The grooves  204  are defined in left and right ends of the case  201  and extend in a horizontal direction N. 
     As shown in FIG. 23, battery connectors  71 ,  72  in the form of recesses, which correspond respectively to the attachments  202  and the electric connection terminal  203 , are defined in a rear end portion of the battery storage region  2   a  in the main unit  2 . A pair of projections  73  for insertion into the respective grooves  204  is defined in the battery storage region  2   a  at the opposite sides of the rear end portion thereof, substantially in the upper surface of the legs  22 . 
     As shown in FIGS. 24 and 26, the battery pack  200  is moved toward the battery storage region  2   a  while an abutment surface of the battery pack  200  is being oriented toward the battery storage region  2   a , and the projections  73  of the main unit  2  are inserted respectively into the grooves  204  in the battery pack  200 . The battery pack  200  can thus be displaced horizontally in the battery storage region  2   a  along the projections  73 . 
     As shown in FIGS. 25 and 27, the attachments  202  and the electric connection terminal  203  of the battery pack  200  are fitted into the battery connectors  71 ,  72  of the main unit  2 . The battery pack  200  is now reliably electrically and mechanically removably fixed in position. 
     Since the battery pack  200  can be guided by the grooves  204  and the projections  73 , the electric connection terminal  203  of the battery pack  200  is prevented from being damaged under stresses exerted when the electric connection terminal  203  is connected to and disconnected from the battery connector  72 . With the battery pack  200  mounted in the main unit  2 , a drive power supply is supplied from the battery pack  200  via the electric connection terminal  203  and the battery connector  72  to the main unit  2 . 
     The guide mechanism described above comprises the grooves  204  defined in the opposite ends of the battery pack  200  and the projections  73  disposed on the surfaces of the main unit  2  which face the opposite ends of the battery pack  200 . However, the grooves  204  and the projections  73  may positionally be switched around. Specifically, grooves similar to the grooves  204  may be defined in the surfaces of the main unit  2  which face the opposite ends of the battery pack  200 , and projections similar to the projections  73  may be disposed on the opposite ends of the battery pack  200 . 
     In the above embodiment, recesses are defined in the metal casing. However, the metal casing may be replaced with a nonmetal casing with an electromagnetic shield layer deposited on its inner surface. Such an electromagnetic shield layer may be deposited by an electrically conductive coating process, a metal plating process, a metal evaporating process, or a metal foil spreading process. While the above embodiment has been directed to a portable personal computer, the present invention is also applicable to any of various other types of information processing devices, e.g., portable information terminals and information processing devices such as portable telephone sets, radio units, etc. 
     Although a certain preferred embodiment of the present invention have been shown and described in detail, it should be understood that various changes and modifications may be made therein without departing from the scope of the appended claims.