Patent Publication Number: US-2023147548-A1

Title: Electronic apparatus

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to an electronic apparatus which includes a keyboard device. 
     Description of the Related Art 
     As a configuration of the electronic apparatus such as a laptop PC and so forth, there exists the configuration which includes a chassis which has a keyboard device on its upper surface and a cooling module which cools a heating element such as a CPU (Central Processing Unit) and so forth in the chassis (see, for example, Japanese Patent No. 6846547). 
     SUMMARY OF THE INVENTION 
     Since demand for thinning of the chassis is great in the electronic apparatus such as the one which is described above, it is difficult to secure a space for installation of a large-sized cooling module. For this reason, in the electronic apparatus of the above-mentioned type, there is concern that heat in the chassis will readily transfer to the keyboard device which is installed on the upper surface of the chassis and the heat will make a user uncomfortable. Particularly, as observed in the keyboard device in Japanese Patent No. 6846547, the configuration that each keycap is surrounded by a frame is small in the number of escape routes of heat which is transferred to the keyboard device from within the chassis and the above-described thermal problem readily occurs. 
     The present invention has been made in consideration of the problem of the above-described prior art and aims to provide an electronic apparatus which makes it possible to suppress temperature rising of a keyboard device which is installed on the upper surface side of the chassis. 
     The electronic apparatus according to the first aspect of the present invention includes a keyboard device which is installed on the upper surface side of the chassis and has a plurality of keycaps and a frame which is installed on the upper surface side of the chassis and isolates the respective keycaps of the keyboard device from one another, in which each of at least some of the plurality of keycaps has an upper plate which forms an operation surface, and side walls on four sides which are provided so as to hang down from a peripheral edge part of the upper plate and face the frame respectively and in at least the side wall on one side of the side walls on the four sides, a flow path formation part which widens a clearance between that side wall and the frame and thereby forms an air flow path is provided. 
     The electronic apparatus according to the second aspect of the present invention includes a chassis, a keyboard device which is installed on the upper surface side of the chassis and has a plurality of keycaps and a frame which is installed on the upper surface side of the chassis and isolates the respective keycaps of the keyboard device from one another, in which each of at least some of the plurality of keycaps has an upper plate which forms an operation surface, and side walls on four sides which are provided so as to hang down from a peripheral edge part of the upper plate and face the frame respectively and in at least the side wall on one side of the side walls on the four sides, a hole part or a recessed part is provided. 
     The electronic apparatus according to the third aspect of the present invention includes a chassis, a keyboard device which is installed on the upper surface side of the chassis and has a plurality of keycaps and a frame which is installed on the upper surface side of the chassis and isolates the respective keycaps of the keyboard device from one another, in which each of at least some of the plurality of keycaps has an upper plate which forms an operation surface, and side walls on four sides which are provided so as to hang down from a peripheral edge part of the upper plate and face the frame respectively and on at least the side wall on one side of the side walls on the four sides, an inclined plane which gradually inclines in a direction of separating from the frame toward a lower end of that side wall is provided. 
     According to one aspect of the present invention, it becomes possible to suppress the temperature rising of the keyboard device which is installed on the upper surface side of the chassis. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic plan view illustrating one example of a state that an electronic apparatus according to one embodiment of the present invention is viewed from above. 
         FIG.  2    is an essential-part-enlarged side-face sectional diagram schematically illustrating one example of an internal structure of a chassis. 
         FIG.  3    is a perspective view illustrating one example of a state in which that part of a keyboard device is enlarged. 
         FIG.  4 A  is a perspective view illustrating one example of a state in which a keycap is viewed diagonally from above. 
         FIG.  4 B  is a perspective view illustrating one example of a state in which the keycap which is illustrated in  FIG.  4 A  is viewed diagonally from below. 
         FIG.  5    is a partially sectional side view illustrating one example of a relation between a keycap which has a flow path formation part and a frame. 
         FIG.  6    is a partially sectional side view illustrating one example of a relation between an existing keycap which has no flow path formation part and a frame. 
         FIG.  7    is a graph illustrating one example of a result of an experiment that an air suction amount of one fan device which is configured so that the keycap which has the flow path formation part is compared with an air suction amount of another fan device which is configured so that the keycap has no flow path formation part. 
         FIG.  8    is a perspective view illustrating one example of a state in which a keycap which has a flow path formation part pertaining to the first modified example is viewed diagonally from above. 
         FIG.  9    is a perspective view illustrating one example of a state in which a keycap which has a flow path formation part pertaining to the second modified example is viewed diagonally from above. 
         FIG.  10 A  is a side view illustrating one example of a keycap which has a flow path formation part pertaining to the third modified example. 
         FIG.  10 B  is a side-face sectional diagram illustrating one example of the keycap which is illustrated in  FIG.  10 A . 
         FIG.  11    is a perspective view illustrating one example of a state in which a keycap which has a flow path formation part pertaining to the fourth modified example is viewed diagonally from above. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the following, an electronic apparatus according to the present invention will be described in detail by giving a preferable embodiment, with reference to the appended drawings. 
       FIG.  1    is a schematic plan view illustrating one example of a state that an electronic apparatus  10  according to one embodiment is viewed from above. As illustrated in  FIG.  1   , the electronic apparatus  10  includes a chassis  14  in which a keyboard device  12  is loaded and a display chassis  18  in which a display  16  is loaded. The electronic apparatus  10  is a clamshell-shape laptop PC that the chassis  14  and the display chassis  18  are coupled together via a hinge  20  to be rotationally movable relatively.  FIG.  1    illustrates a state in which the display chassis  18  is opened from the chassis  14  to bring the electronic apparatus  10  into a usage form. The electronic apparatus  10  may be an electronic apparatus of a shape other than the clamshell-shape. 
     The display chassis  18  is a thin flattened box body. The display  16  is loaded on the display chassis  18 . The display  16  is made of, for example, organic EL (electroluminescence), liquid crystal and so forth. 
     In the following, the chassis  14  and respective elements which are loaded on the chassis  14  will be described by calling the front side “front”, the back side “rear”, a width direction “left-right” and a height direction (a thickness direction of the chassis  14 ) “top-bottom”, with a posture of operating the keyboard device  12  which is illustrated in  FIG.  1    being set as a reference. 
     The chassis  14  is a thin flattened box body. The chassis  14  has a cover member  21  which forms an upper surface  14   a  and side faces on the periphery and a plate-shaped cover member  22  which forms a lower surface  14   b  (also, see  FIG.  2   ). The cover members  21  and  22  are mutually superimposed in a thickness direction and are coupled together to be detachable. An opening  21   a  into which the keyboard device  12  is inserted from below is formed in the upper-side cover member  21  (also, see  FIG.  2   ). The cover member  21  may be also configured to have a shallow bath-tab shape recessed part in place of the opening  21   a  and to place the keyboard device  12  into the recessed part from above. 
     The keyboard device  12  and a touch pad  24  are installed on the upper surface  14   a  of the chassis  14 . The keyboard device  12  occupies the most part of the upper surface  14   a . A rear end part of the chassis  14  is coupled with the display chassis  18  by using the hinge  20 . 
       FIG.  2    is an essential part enlarged side-face sectional diagram schematically illustrating one example of an inner structure of the chassis  14 . As illustrated in  FIG.  1    and  FIG.  2   , a substrate  26  and a cooling module  28  are housed in the chassis  14 . Further, various kinds of electronic components and mechanical components and so forth of a battery device and so forth are installed in the chassis  14 . 
     The substrate  26  is a mother board of the electronic apparatus  10 . The substrate  26  is a printed board that a CPU (Central Processing Unit)  30  is implemented. Further, various kinds of electronic components such as a GPU (Graphics Processing Unit), a communication module, a memory, connection terminals and so forth are implemented on the substrate  26 . The substrate  26  is arranged under the keyboard device  12 . The substrate  26  is screwed to a rear surface of the keyboard device  12  and an inner surface of the cover member  21  and is thereby fixed to the chassis  14 . An upper surface of the substrate  26  serves as an attachment surface for the cover member  21  and a lower surface of the substrate  26  serves as a mounting surface of the CPU  30  and so forth. 
     The CPU  30  is a processing device which executes arithmetic operations which relate to main control and processing of the electronic apparatus  10 . The CPU  30  is the largest heating element in the devices which are loaded on the electronic apparatus  10 . 
     The cooling module  28  absorbs, transports and discharges heat that mainly the CPU  30  generates to the outside of the chassis  14 . It is also possible for the cooling module  28  to discharge heat which is generated from heating elements other than the CPU  30 , such as, for example, a GPU  31  and so forth. The most part of the cooling module  28  is arranged under the substrate  26 . The cooling module  28  is screwed to a lower surface of the substrate  26 , a rear surface of the keyboard device  12 , an inner surface of the cover member  21  and so forth and thereby is fixed to the chassis  14 . 
     The cooling module  28  includes fan devices  32  and  33 , cooling fins  34  and  35  and a heat pipe  36 . 
     The cooling module  28  in one embodiment is used for cooling the CPU  30  and the GPU  31  and therefore one pair of the fan devices  32  and  33  and one pair of the cooling fins  34  and  35  are loaded on the cooling module  28 . The cooling module  28  may be also configured to load one fan device and one cooling fin thereon respectively depending on a target to be cooled, an ability which is required for cooling and so forth. The basic configurations of the fan devices  32  and  33  are basically the same as each other or similar to each other except for a point that the sizes and the shapes of the fan devices  32  and  33  are slightly different from each other. Accordingly, in the following, the fan device  32  and the cooling fin  34  will be representatively described and description of the fan device  33  and the cooling fin  35  will be omitted. 
     The fan devices  32  and  33  are arranged in the vicinities of left and right rear corner parts of the chassis  14  respectively (see  FIG.  1   ). As illustrated in  FIG.  2   , the fan device  32  ( 33 ) includes a fan chassis  40 , a rotation unit  41  and an impeller  42 . The fan device  32  ( 33 ) is a centrifugal fan that the rotation unit  41  is rotated by a motor and thereby the impeller  42 , which is provided on the outer peripheral side of the rotation unit  41 , rotates. 
     The fan chassis  40  is a flattened box body which houses the rotation unit  41  and the impeller  42 . The fan chassis  40  has a lower plate  40 A, an upper plate  40 B and a side plate  40 C. The respective plates  40 A to  40 C are, for example, metal plates. 
     The lower plate  40 A is an almost bullet-shape thin plate that one side of a rectangle plate is formed into a circular shape. The lower plate  40 A forms a lower surface  32   a  of the fan device  32  ( 33 ). A lower suction port  44  is formed in the lower plate  40 A. The lower suction port  44  is a through hole of, for example, a circular shape, a donut shape or a shape that a plurality of ellipses is arrayed in a circumferential direction. 
     The upper plate  40 B is a thin plate which has an external shape which is the same as the external shape of the lower plate  40 A. The upper plate  40 B forms an upper surface  32   b  of the fan device  32  ( 33 ). An upper suction port  45  is formed in the upper plate  40 B. The upper suction port  45  may have a shape which is the same as or similar to the shape of the lower suction port  44 . The suction ports  44  and  45  are openings which are used to take external air into the fan chassis  40  with the aid of rotation of the impeller  42 . 
     The side plate  40 C is a curved plate which covers a side part of a space in the fan chassis  40  which is formed between the lower plate  40 A and the upper plate  40 B. In one embodiment, the side plate  40 C is configured integrally with the upper plate  40 B. 
     An opening is formed in a rearward-facing side face of the fan chassis  40  owing to no installation of the side plate  40 C or owing to formation of a hole in the side plate  40 C. This opening serves as an exhaust port  46  of the fan device  32 . The exhaust port  46  is arranged to face the cooling fin  34 . 
     Front faces of the cooling fins  34  and  35  are arranged directly behind the fan devices  32  and  33  respectively and face the exhaust port  46 . Rear surfaces of the cooling fins  34  and  35  face a chassis exhaust port  14   c  which opens to a rear-side surface of the chassis  14 . The cooling fin  34  ( 35 ) has a structure that a plurality of plate-shaped metal fins is arrayed at equal intervals in a left-right direction on the surface of a base plate. Each fin stands upright in a top-bottom direction and extends in a front-rear direction. A clearance that air which is sent from the fan device  32  ( 33 ) passes is formed between the adjacent fins. The cooling fin  34  ( 35 ) is thermally connected with the CPU  30  via a heat pipe  36 . 
     The heat pipe  36  is a pipe-shaped heat transport device. The heat pipe  36  is used alone or in a set of two or more pipes. The heat pipe  36  is the one that a metal pipe is smashed thin and flat into an oval shape in section and a working fluid is encapsulated into an internal closed space and may be a well-known heat pipe. In the heat pipe  36 , for example, a heat absorption part which is located at one end is thermally connected with the CPU  30  and a heat radiation part which is located at the other end is connected with the cooling fin  34  ( 35 ). 
     In the cooling module  28  which is configured in this way, the heat which is generated from the CPU  30  and so forth and is transported through the heat pipe  36  is transferred to the cooling fin  34  ( 35 ). The heat which is transferred to the cooling fin  34  ( 35 ) is exhausted to the outside of the chassis  14  passing through the chassis exhaust port  14   c  with the aid of air which blows through the exhaust ports  46  in the fan device  32  ( 33 ). In  FIGS.  1 ,  47  and  48    denote plate-shape heat transport devices which diffuse heat which is generated from the CPU  30  and so forth such as, for example, metal plates or vapor chambers. 
       FIG.  3    is a perspective diagram illustrating one example of a state that part of the keyboard device  12  is enlarged. As illustrated in  FIG.  2    and  FIG.  3   , the keyboard device  12  includes a plurality of key switches  50 , a laminated plate  52  and a frame  54 . 
     Each key switch  50  has a keycap  56  which is supported by a guide mechanism  50   a  and a rubber dome  50   b  to be movable upward/downward. The guide mechanism  50   a  is a scissors mechanism which couples together a lower surface of the keycap  56  and an upper surface of the laminated plate  52 . The rubber dome  50   b  is a doom-shape member which is made of a flexible elastic material such as, for example, silicone rubber and so forth. The rubber dome  50   b  is arranged at the center of the guide mechanism  50   a  and is interposed between the keycaps  56  and the laminated plate  52 . 
     Each keycap  56  is molded with, for example, a resin and is formed into an almost rectangular shape in a planer view. Each keycap  56  has an upper plate  56   a  and side walls  56   b  to  56   e  which are located on the four sides (see  FIG.  4 A  and  FIG.  4 B ). 
     The upper plate  56   a  forms an operation surface of each key switch  50 . The side walls  56   b  to  56   e  are disposed to hang down from a peripheral edge of the upper plate  56   a . The side wall  56   b  forms a front side-surface of each keycap  56 . The side wall  56   c  forms a rear side-surface of each keycap  56 . The side wall  56   d  forms a left side-surface of each keycap  56 . The side wall  56   e  forms a right side-surface of each keycap  56 . 
     The laminated plate  52  has a base plate  57 , a membrane sheet  58  which is laminated on an upper surface of the base plate  57  and a light guide plate  59  which is laminated on a lower surface of the base plate  57 . The base plate  57  is a metal plate that cut and raised portions and hole portions are formed on/in various places. The membrane sheet  58  is a switch sheet which has a three-layered structure that a contact is closed, for example, in a case of being pressed. In the membrane sheet  58 , the contact is closed by the rubber dome  50   b  which is compressed in a case where any one of the keycaps  56  is pressed down. The light guide plate  59  is a transparent resin plate which is adapted to guide light that a light source which is attached to a lower surface of the light guide plate  59  emits in the left-right direction, to reflect the light from a light reflection surface and to irradiate each keycap  56  with the reflected light from the rear surface of each keycap  56 . Installation of the light guide plate  59  may be omitted and, in this case, a waterproof sheet may be laminated on a lower surface of the base plate  57 . 
     The frame  54  is a meshed plate which is made of resin, metal and so forth. The frame  54  is fixed to an upper surface of the laminated plate  52  by screwing and so forth. The frame  54  may be molded integrally with the cover member  21 . The frame  54  is adapted to arrange around respective keycaps  56  and to isolate the respective keycaps  56  from one another. 
     The frame  54  has a plurality of key placement holes  54   a  into which the respective keycaps  56  are inserted to be movable upward/downward. Each key placement hole  54   a  is a rectangular space which is surrounded by vertical frames  54   b  which extend in the front-rear direction and horizontal frames  54   c  which extend in the left-right direction in each mesh of the frame  54 . 
     As illustrated in  FIG.  2   , the chassis  14  includes one set of lower communication holes  60  which is adapted to flow air A into the chassis  14  from a lower surface  14   b  of the chassis  14 . 
     Each lower communication hole  60  is a through hole which is formed in a cover member  22  which forms the lower surface  14  of the chassis  14 . One set of lower communication holes  60  has a configuration that, for example, a plurality of slit-shaped hole portions is arranged in parallel. One set of lower communication holes  160  is disposed at a position that one set of lower communication holes  160  overlaps with the lower suction port  44  in the fan device  32  ( 33 ) in the planar view and faces the lower suction port  44 . 
     As illustrated in  FIG.  2   , the chassis  14  includes an upper communication hole  62  which is adapted to flow the air A into the chassis  14  from above. 
     The upper communication hole  62  is a through hole which penetrates through the keyboard device  12  in the top-bottom direction. A clearance between the adjacent keycaps  56  and  56 , a notched recessed portion  54   d  and a hole portion  12   a  communicate with one another in order from above toward below and thereby the upper communication hole  62  is formed. The notched recessed portion  54   d  is a portion which forms a flow path of the air A by notching a lower-surface side of the frame  54 . The hole portion  12   a  is a through hole which is formed in the laminated plate  52 . 
     The upper communication hole  62  communicates with the upper suction port  45  in the fan device  32  ( 33 ). In one embodiment, the upper communication hole  62  is disposed at a position where the upper communication hole  62  overlaps with the upper suction port  45  in the fan device  32  ( 33 ) in the planar view and faces the upper suction port  45 . In a case of configuring to place a cover member  21  under the keyboard device  12 , it is preferable for the upper communication hole  62  to include also a hole portion which is formed in the cover member  21  which is placed under the keyboard device  12 . 
     Accordingly, as illustrated in  FIG.  2   , the fan devices  32  ( 33 ) sucks the air A which is present on the lower side of the chassis  14  from the set of lower communication holes  60  in the cover member  22  through the lower suction port  44 . At the same time, the fan device  32  ( 33 ) sucks the air A which is present on the upper side of the chassis  14  from the upper communication hole  62  through the upper suction port  45 . In a case where the fan device  32  ( 33 ) discharges the air A which is sucked through each of the suction ports  44  and  45  to the outside of the chassis  14  through the exhaust port  46 , the fan device  32  ( 33 ) cools the cooling fin  34  ( 35 ). Thereby, it becomes possible for the fan device  32  ( 33 ) to take in the air sufficiently from the upper and lower surfaces of the chassis  14  and therefore it becomes possible to obtain high cooling efficiency. 
     In  FIGS.  2 ,  63     a  and  63   b  denote sealing materials which are made of sponge and so forth. The sealing material  63   a  forms a cutoff wall around the lower suction port  44  in the fan device  32 . The sealing material  63   b  forms a cutoff wall around the upper suction port  45  in the fan device  32 . The sealing materials  63   a  and  63   b  avoid intrusion of water into the substrate  26  and so forth in the chassis  14  in a case where a liquid such as a beverage and so forth is spilled on the keyboard device  12 . 
     Incidentally, it is desired to make a clearance between each of the side walls  56   b  to  56   d  of each keycap  56  and the frame  54  narrower to the greatest possible extent. The reason therefor lies in avoidance of intrusion of foreign materials into the chassis  14  through each clearance by improving the quality of the outer appearance of the keyboard device  12 . Also, in the electronic apparatus  10  according to one embodiment, a clearance C between each keycap  56  and the frame  54  is extremely narrow (see  FIG.  2    and  FIG.  3   ) and is set to, for example, about 0.4 mm. As a result, it is feared that the suction amount of the air which is sucked through the upper communication hole  62  would be limited because the clearance C acts as a bottleneck and therefore it would become impossible for the fan device  32  ( 33 ) to suck a sufficient amount of the air A. 
     Accordingly, in the electronic apparatus according to one embodiment, the clearance C is widened and a flow path formation part  64  which forms an air flow path in the widened clearance C is provided in each keycap  56 .  FIG.  4 A  is a perspective view illustrating one example of a state that the keycap  56  is viewed diagonally from above.  FIG.  4 B  is a perspective view illustrating one example of a state that the keycap  56  is viewed diagonally from below. 
     As illustrated in  FIG.  4 A  and  FIG.  4 B , the flow path formation part  64  has one pair of hole portions  64   a  and  64   a  which is formed in the rear-side side wall  56   c  of each keycap  56 . The hole portion  64   a  is a notch-shape hole which is formed by notching the side wall  56   c  into an almost trapezoidal shape upwards from a lower end surface of the side wall  56   c . The hole portion  64   a  may be also called a notch-shape recessed portion, in place of the notch-shape hole portion. The hole portion  64   a  may have an arch shape, a rectangular shape and so forth. The hole portion  64   a  may be not a notch-shape hole but a through hole which penetrates through the side wall  56   c . The hole portion  64   a  may be either formed when molding each keycap  56  or formed by machining after molding of each keycap  56 . 
     One pair of the hole portions  64   a  is formed in the side wall  56   c  in a state of being arranged side by side along a longitudinal direction (the left-right direction) of the side wall  56   c . Three or more hole portions  64   a  may be formed in the side wall  56   c . A protection wall  64   b  which is formed by hanging down part of the side wall  56   c  is provided between the mutually adjacent hole portions  64   a  and  64   a . The protection wall  64   b  is a wall member for preventing each keycap  56  from being erroneously removed in a case where a nail or the like of a user is caught in the hole portion  64   a . In the flow path formation part  64  which is illustrated in  FIG.  4 A  and  FIG.  4 B , the side wall  56   c  which includes the protection wall  64   b  is formed into an almost M-shape. Accordingly, the protection wall  64   b  is formed to be widened at the root (an upper part) and therefore has high strength and rigidity. 
     In  FIG.  4 B,  65    denotes a plurality of projections for supporting the guide mechanism  50   a  which is formed on the lower surface of the upper plate  56   a . The respective projections  65  are arranged along the front and rear side walls  56   b  and  56   c  respectively. It is preferable to dispose each projection  65  at a position which is closer to the side walls  56   b  and  56   c  to the extent possible in order to secure a stable elevating operation of the guide mechanism  50   a . In this respect, the hole portions  64   a  which configure the flow path formation part  64  do not project to the center side of each keycap  56  and therefore do not interfere with the projections  65 . 
     As illustrated in  FIG.  3   , in one embodiment, the flow path formation part  64  is installed only in the rearward facing side wall  56   c  in the side walls  56   b  to  56   e  on the four sides of each keycap  56 . The flow path formation part  64  may be formed in some of or all the other side walls  56   b ,  56   d  and  56   e , in addition to or in place of the side wall  56   c.    
     However, as illustrated in  FIG.  3   , the flow path formation parts  64  are exposed to the outside of the keyboard device  12 . In one embodiment, in particular, the keyboard device  12  has a configuration that the keycaps  56  project upward from the upper surface of the frame  54  and therefore the flow path formation parts  64  are conspicuous in outer appearance. For this reason, there are such advantages that in a case where the flow path formation part  64  is formed on the rearward facing side wall  56   c , it becomes more difficult for the flow path formation part  64  to come into sight of the user than in a case where the flow path formation parts  64  are formed on the forward facing and laterally facing side walls  56   b ,  56   d  and  56   e , light leakage from the light guide plate  59  becomes more inconspicuous and it becomes possible to suppress a reduction in outer appearance quality. 
       FIG.  5    is a partially sectional side view illustrating one example of a relation between each keycap  56  which has the flow path formation part  64  and the frame  54 .  FIG.  6    is a partially sectional side view illustrating one example of a relation between an existing keycap  66  which has no flow path formation part  64  and the frame  54 . 
     In the keycap  56  in one embodiment which is illustrated in  FIG.  5   , the clearance C between the side wall  56   c  and the frame  54  is enlarged to a wider clearance C 1  owing to formation of the hole portion  64   a  in the flow path formation part  64 . The clearance C 1  is, for example, 0.9 mm. On the other hand, since in the existing keycap  66  in  FIG.  6   , the flow path formation part  64  is not provided in the side wall  56   c , a clearance C 2  between the side wall  56   c  and the frame  54  is drastically smaller than the clearance C 1 . The clearance C 2  is, for example, 0.4 mm which is the same as the size of the clearance C. 
     Accordingly, in the electronic apparatus  10  according to one embodiment, the clearance C between each keycap  56  and the frame  54  is widened to the clearance C 1  owing to formation of the flow path formation part  64  and thereby a wider air flow path is formed. 
     Here, an effect of increasing the air suction amount of the fan device  32  owing to presence of the flow path formation part  64  will be described. 
       FIG.  7    is a graph illustrating one example of a result of an experiment that the air suction amounts of the fan devices  32  which are configured by using the keycap  56  which has the flow path formation part  64  and the existing keycap  66  which has no flow path formation part  64  are compared with each other. In  FIG.  7   , the horizontal axis indicates a noise (dBA) and the vertical axis indicates an air flow rate (cfm) of the fan device  32 . In addition, a solid-line graph (1) indicates a result of the experiment which is obtained from the keycap  56  which has the flow path formation part  64  in  FIG.  5    in one embodiment of the present invention. A broken-line graph (2) indicates a result of the experiment which is obtained from the existing keycap  66  which has no flow path formation part  64  which is illustrated in  FIG.  6   . 
     Here, in general, the electronic device such as the laptop PC controls the maximum number of revolutions of the fan device  32  within a noise allowable range and controls the number of revolutions of the fan device  32  such that, for example, the noise level does not exceed 50 (dBA). Accordingly, it becomes possible for the cooling module  28  to obtain a higher cooling performance as the air volume (cfm) of the fan device  32  which is obtained at the noise level of 50 dBA is more increased. 
     As illustrated in  FIG.  7   , it is found that the graph (1) which indicates the result of the experiment which is obtained by using the keycap  56  in one embodiment of the present invention is large in the air volume (cfm) at the noise levels (dBA) in all ranges in comparison with the graph (2) which indicates the result of the experiment which is obtained by using the existing keycap  66 . Specifically, the air volume of the fan device  32  in the graph (1) is increased by about 6% in all noise values in comparison with the air volume in the graph (2). That is, it is found that in the electronic apparatus  10  according to one embodiment of the present invention, the air volume of the fan device  32  is increased and the cooling performance of the cooling module  28  is improved by forming the flow path formation part  64  in each keycap  56 . 
       FIG.  8    is a perspective diagram illustrating one example of a state that the keycap  56  which has a flow path formation part  68  pertaining to the first modified example is viewed diagonally from above. The flow path formation part  68  which is illustrated in  FIG.  8    is different from the flow path formation part  64  which is illustrated in  FIG.  4 A  in the point that the flow path formation part  68  has one hole portion  64   a  which extends over almost the full width of the side wall  56   c  and the protection wall  64   b  is not provided at the center. It becomes possible for the flow path formation part  68  to make the air flow path larger than the air flow path which is obtained by the flow path formation part  64  by the amount that there exists no protection wall  64   b  and to more increase the air suction amount of the fan device  32 . 
       FIG.  9    is a perspective view illustrating one example of a state that the keycap  56  which has a flow path formation part  69  pertaining to the second modified example is viewed diagonally from above. The flow path formation part  69  which is illustrated in  FIG.  9    is different from the flow path formation part  64  which is illustrated in  FIG.  4 A  in the point that the flow path formation part  69  has a plurality of slits  69   a  which is narrower than the hole portion  64   a  in the flow path formation part  64  in  FIG.  4 A . Respective slits  69   a  are hole portions or recessed portions which are formed in the side wall  56   c  in a state of being arrayed side by side along the longitudinal direction. The protection wall  64   b  is provided also between the mutually adjacent slits  69   a . Although the flow path formation part  69  becomes smaller than the flow path formation  64  in air flow path, the flow path formation part  69  is higher than the flow path formation part  64  in the effect of avoiding the intrusion of the nails, the foreign matters and so forth because the protection walls  64   b  are arrayed in a lattice shape. 
       FIG.  10 A  is a side view illustrating one example of the keycap  56  which has a flow path formation part  70  pertaining to the third modified example.  FIG.  10 B  is a side face sectional diagram illustrating one example of the keycap  56  which is illustrated in  FIG.  10 A . The flow path formation part  70  which is illustrated in  FIG.  10 A  and FIG.  10 B has an inclined plane  70   a  which is provided on the surface of the side wall  56   c . The inclined plane  70   a  gradually inclines in a direction (forwardly) away from the frame  54  toward a lower end of the side wall  56   c . Although the flow path formation part  70  becomes smaller than the flow path formation  64  in the air flow path, the flow path formation part  70  is greatly higher than the flow path formation part  64  in the effect of avoiding the intrusion of the nails, the foreign matters and so forth because the inclined plane  70   a  itself functions in the same manner as the protection wall  64   b.    
       FIG.  11    is a perspective view illustrating one example of a state that the keycap  56  which has a flow path formation part  71  pertaining to the fourth modified example is viewed diagonally from above. The flow path formation part  71  which is illustrated in  FIG.  11    has a grooved portion  71   a  which is formed in the surface of the side wall  56   c . The grooved portion  71   a  is a groove-shape recessed portion which is formed along the top-bottom direction of the side wall  56   c . The protection wall  64   b  is also provided between the mutually adjacent grooved portions  71   a . Although the flow path formation part  71  becomes smaller than the flow path formation part  64  in the air flow path, the flow path formation part  71  is greatly higher than the flow path formation part  64  in the effect of avoiding the intrusion of the nails, the foreign matters and so forth because also the grooved portion  71   a  itself functions in the same manner as the protection wall  64   b . The flow path formation part  71  may be also configured to widen one grooved portion  71   a  across almost the full width of the side wall  56   c.    
     As described above, in the electronic apparatus  10  according to one embodiment of the present invention, the clearance C between each keycap  56  and the frame  54  is enlarged by installation of the flow path formation part ( 64 ,  69  to  71 ) in each keycap  56  and thereby the air flow path is secured. 
     Accordingly, in the electronic apparatus  10 , the flow rate of the air A which flows from the upper communication hole  62  which penetrates through the keyboard device  12  to the upper suction port  45  is increased. Therefore, in the electronic apparatus  10 , the air volumes of the fan devices  32  and  33  are increased and the cooling performance of the cooling module  28  is improved. As a result, it becomes possible for the electronic apparatus  10  to reduce the amount of heat which is generated from the CPU  30  and so forth and is transmitted to the keyboard device  12  and to suppress temperature rising of the keyboard device  12 . In this case, the flow path formation part  64  and so forth may be provided in the keycap  56  which is located at the position that the keycap  56  overlaps with at least the fan devices  32  and  33  in the top-bottom direction (see  FIG.  2   ). 
     Incidentally, it becomes also possible for the electronic apparatus  10  to discharge the heat which is transmitted from the CPU  30  and so forth to the keyboard device  12  upward through the flow path formation part  64  and so forth by installation of the flow path formation part ( 64 ,  69  to  71 ) in each keycap  56 . That is, as illustrated in  FIG.  2   , in the electronic apparatus  10 , the heat H which is transmitted from the CPU  30  and so forth to the keyboard device  12  is smoothly discharged upward through the clearance C (C 1 ) which is enlarged by installation of the flow path formation part  64  and so forth in each cap  56 . In  FIG.  2   , each solid line arrow H schematically indicates the flow of the heat 
     Accordingly, the upper communication hole  62  which penetrates through the keyboard device  12  is not essential in the electronic apparatus  10 . That is, even in a case where the electronic apparatus  10  is configured to have no upper through hole  62 , it is possible for the electronic apparatus  10  to effectively discharge the heat through the clearance C (C 1 ) which is enlarged by installation of the flow path formation part  64  and so forth in each keycap  56  and thereby to suppress the temperature rising of the keyboard device  12 . In this case, it is desirable that the flow path formation part  64  and so forth be installed in as many keycaps  56  as possible, preferably, in all the keycaps  56 . 
     Incidentally, it goes without saying that the present invention is not limited to the above-described embodiment and the modified examples and it is possible to freely alter the configuration of the electronic apparatus  10  within the range not deviating from the gist of the present invention.