Abstract:
A housing includes a pair of housing walls that face each other with an inner space therebetween. The housing further includes: a first projection that projects from a first housing wall of the pair of housing walls toward a second housing wall of the pair of housing walls and abuts the second housing wall; and a second projection that projects from the second housing wall toward the first housing wall and engages in the first projection thereby preventing separation of the pair of housing walls.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2008-243237, filed on Sep. 22, 2008, the entire contents of which are incorporated herein by reference. 
     FIELD 
     The embodiments discussed herein are related to a housing in an electronic device and an electronic device having a housing in which a board is disposed. 
     BACKGROUND 
     Generally, as a method for joining walls of a housing of an electronic device such as a personal computer, there are known a method using screws and a method using claws protruding from one inner wall of a housing to be engaged in another wall (see, for example, Japanese Laid-open Patent Publications No. 05-315767 and No. 2000-59041). 
     Meanwhile, a housing of an electronic device is required not only to have its walls firmly joined together thereby reliably preventing the separation of the walls, but also to avoid such an inconvenience that a wall of the housing is warped by receiving an external force like a press on the wall by a user. Further, as for a housing of an electronic device expected to reduce the size and weight, such as a notebook personal computer and a mobile telephone, disconnection of walls and deformation of a wall due to an external force need to be prevented efficiently in a limited space. 
     SUMMARY 
     According to an aspect of the invention, a housing includes: a pair of housing walls that face each other with an inner space therebetween; a first projection that projects from a first housing wall of the pair of housing walls toward a second housing wall of the pair of housing walls and abuts the second housing wall; and a second projection that projects from the second housing wall toward the first housing wall and engages in the first projection thereby preventing separation of the pair of housing walls. 
     According to the housing described above, the first projection is formed to project from the first housing wall and abut the second housing wall to support the housing from inside, thereby preventing the second housing wall from warping due to an external force applied to the second housing wall. In addition, the second projection is formed to project from the second housing wall and engage in the first projection, thereby preventing the separation of the pair of housing walls. Further, since the second projection becomes integral with the first projection by engaging in the first projection, the space required to prevent the separation and the warp is made small. In other words, the housing described above makes it possible to efficiently prevent, in a tight space, the housing walls from being separated from each other and the wall being warped due to an external force. 
     The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, as claimed. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is an external view of a personal computer in a state (closed state) where a display unit is closed with respect to a main unit; 
         FIG. 2  is an external view of the personal computer in a state (open state) where the display unit is opened with respect to the main unit; 
         FIG. 3  is an external view of the personal computer in the closed state as illustrated in  FIG. 1 , where the undersurface of the main unit is seen, with the display unit down; 
         FIG. 4  illustrates a state where a dust filter illustrated in  FIG. 3  is detached; 
         FIG. 5  illustrates a state where a panel serving as the lower surface of the main unit illustrated in  FIG. 4  is detached and thus an internal structure of the main unit is exposed; 
         FIG. 6  illustrates a state where the dust filter is placed so as to have its filter main body inserted between a blowing opening of a fan and a heat radiating section; 
         FIG. 7  is an enlarged view of the fan and the heat radiating section in a cooling unit illustrated in  FIG. 5 ; 
         FIG. 8  is an enlarged view of the dust filter; 
         FIG. 9  illustrates a state where the dust filter and the fan are arranged; 
         FIG. 10  illustrates a state where the dust filter and the heat radiating section are arranged; 
         FIG. 11  illustrates a main unit of another embodiment in which the cooling unit in the main unit illustrated in  FIG. 5  is replaced with another type of cooling unit which transfers heat to a heat radiating section by circulating a coolant; 
         FIG. 12  illustrates a state where a dust filter is attached in the cooling unit illustrated in  FIG. 11 ; 
         FIG. 13  illustrates a side of the dust filter illustrated in  FIG. 12 , which comes into contact with a blowing opening; 
         FIG. 14  illustrates a state where a leaf spring of the dust filter is disposed at a position across the first and second pipes; 
         FIG. 15  illustrates a state where three flat cables illustrated in  FIG. 5  are connected to connectors mounted on the back side of the main board; 
         FIG. 16  illustrates cable holding sections from the front side of the main board illustrated in  FIG. 5 ; 
         FIG. 17  illustrates the cable holding sections from a direction different from  FIG. 16  on the front side of the main board illustrated in  FIG. 5 ; 
         FIG. 18  is an enlarged view of a sub-board illustrated in  FIG. 5 ; 
         FIG. 19  illustrates a state where the sub-board detached from the main board is turned over and connectors of the respective boards is seen; 
         FIG. 20  is a side view illustrating how the sub-board connector and the main board connector are connected to each other; 
         FIG. 21  illustrates a state where a TV signal cable illustrated in  FIG. 5  is connected to an antenna module mounted on the back side of the sub-board; 
         FIG. 22  illustrates the antenna module having the TV signal cable connected thereto; 
         FIG. 23  is an enlarged view illustrating a cable holding section together with an output connector temporarily held by the cable holding section; 
         FIG. 24  illustrates the display unit illustrated in  FIG. 2  in a state of being detached from the main unit; 
         FIG. 25  illustrates an upper panel removed from the display unit; 
         FIG. 26  illustrates the display unit having the upper panel removed therefrom; 
         FIG. 27  illustrates a state where locking claws arranged on a lower frame part, a liquid crystal side rib and a short rib are lined up; 
         FIG. 28  is an enlarged view of an inverter circuit board in a housed state; 
         FIG. 29  illustrates a state where a portion, covering an upper side of the inverter circuit board, in a retaining sheet covering the inverter circuit board is opened; 
         FIG. 30  illustrates a state where the inverter circuit board is taken out of a concave section together with the retaining sheet; 
         FIG. 31  illustrates a state where a single-lamp inverter circuit board also illustrated in  FIG. 29  and the like and a double-lamp inverter circuit board are laid out; and 
         FIG. 32  illustrates a state where the double-lamp inverter circuit board is housed in the concave section for housing the single-lamp inverter circuit board. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     With reference to the drawings, description will be given below of a specific embodiment. 
     An embodiment of an electronic device described below is a so-called notebook personal computer and has a structure in which a main unit and a display unit are connected to each other so as to be opened and closed. The main unit includes a keyboard and the like, and processes various kinds of information. The display unit displays images and the like. 
       FIG. 1  is an external view of the personal computer in a state (closed state) where the display unit is closed with respect to the main unit.  FIG. 2  is an external view of the personal computer in a state (open state) where the display unit is opened with respect to the main unit. 
     This personal computer  10  includes a main unit  20  and a display unit  30  as described above. The main unit  20  and the display unit  30  are connected so that the display unit  30  is opened and closed in an arrow A direction with respect to the main unit  20 . 
     The main unit  20  of the personal computer  10  has components such as a hard disk drive and various boards housed in a main-unit housing  21 . Further, the main unit  20  includes, on its upper surface, a keyboard  22  having multiple keys arranged thereon, a track pad  23 , a right-click button  24  and a left-click button  25 . 
     The display unit  30  of the personal computer  10  displays results of information processing executed by the main unit  20 . The display unit  30  has a flat liquid crystal panel  32 , a control circuit for the liquid crystal panel  32  and the like housed in a display housing  31 . 
       FIG. 3  is an external view of the personal computer in the closed state as illustrated in  FIG. 1 , illustrating a state where the undersurface of the main unit is seen, with the display unit down. 
     Note that  FIG. 3  illustrates the rear of the personal computer  10  directed frontward in contrast to  FIGS. 1 and 2 . 
     The personal computer  10  of this embodiment, to be described later, uses a cooling unit for cooling with air various electronic components in the main unit  20 . As illustrated in  FIG. 3 , the main unit  20  includes an inlet  26  on its lower surface. From the inlet  26 , cooling air is taken into the main unit  20 . The cooling unit allows the cooling air to absorb heat produced by the various electronic components so as to cool the various electronic components. As a result, the air thus warmed is discharged to the outside of the main unit  20  from an outlet  27  provided in the rear of the main unit  20 . 
     Moreover, in this embodiment, a dust filter  131  for removing dust from the air used for cooling in the cooling unit is detachably attached to the main-unit housing  21 . 
       FIG. 4  illustrates a state where the dust filter illustrated in  FIG. 3  is detached. 
     As illustrated in  FIG. 4 , the dust filter  131  includes a filter main body  131   a  having multiple ribs arranged in a lattice pattern. This filter main body  131   a  removes dust from the air flowing toward the outlet  27 . 
     The main-unit housing  21  has, in its lower surface, an opening  28  extended parallel to the outlet  27 . The dust filter  131  is inserted into the opening  28 . Meanwhile, the dust filter  131  has a leaf spring  131   b  which biases the filter main body  131   a  in a longitudinal direction indicated by an arrow B. When the dust filter  131  is inserted into the opening  28 , the leaf spring  131   b  presses the filter main body  131   a  against the main-unit housing  21  in the longitudinal direction indicated by the arrow B. The action by the leaf spring  131   b  of pressing the filter main body  131   a  fixes the dust filter  131  to the main-unit housing  21 . Moreover, a user may detach the dust filter  131  from the main-unit housing  21  by pushing the leaf spring  131   b  with his/her finger and pulling the leaf spring  131   b  out from the main-unit housing  21 . 
     In this embodiment, the dust filter  131  may be easily detached from the main-unit housing  21  in this manner. Thus, the dust filter  131  may be cleaned as appropriate to avoid clogging of the dust filter  131  and the like. 
       FIG. 5  illustrates a state where a panel serving as the lower surface of the main unit illustrated in  FIG. 4  is detached and thus an internal structure of the main unit is exposed. 
     Note that, in  FIG. 5 , the display unit  30  and the dust filter  131  are also removed. 
     As illustrated in  FIG. 5 , the main unit  20  has a main board  110 , a sub-board  120  and the like housed therein. The main board  110  is a large-size board having various electronic components mounted thereon, such as a CPU  111  for performing overall control of the personal computer  10  and chipsets  112  for controlling data communication and the like in the CPU  111  and the like. The sub-board  120  is connected to the main board  110  through a connector and has an antenna module to be described later and the like mounted thereon. 
     The CPU  111  and the chipsets  112  mounted on the main board  110  produce heat while executing signal processing. Therefore, those components are preferably constantly cooled during operations of the personal computer  10  in order to avoid malfunction or the like due to the heat thus produced. In this embodiment, for cooling the CPU  111  and the chipsets  112 , a cooling unit  130  to be described below is mounted on the main unit  20 . 
     The cooling unit  130  includes a heat transfer section  132  having a heat absorbing plate  132   a  made of copper. The heat absorbing plate  132   a  comes into contact with the CPU  111  and the two chipsets  112  to absorb heat produced by those components. The heat transfer section  132  also has a heat pipe  132   b  for transferring the heat absorbed by the heat absorbing plate  132   a  to a heat radiating section  133  to be described later. In the cooling unit  130 , the heat transfer section  132  brings the heat produced by the CPU  111  and the two chipsets  112  into the heat radiating section  133 . 
     The heat radiating section  133  has a structure in which metal fins  133   a  are arranged at predetermined intervals in a ventilator through which the air passes. Here, the ventilator defines a ventilation area. The heat transferred to the heat radiating section  133  by the heat transfer section  132  comes to the fins  133   a  included in the heat radiating section  133 . 
     The cooling unit  130  further includes a fan  134  for blowing air in a direction indicated by an arrow C so as to allow the air to flow between the fins  133   a  in the heat radiating section  133 . The air blown by the fan  134  passes between the fins  133   a  so that the heat coming to the fins  133   a  is radiated into the air. The air warmed by the heat radiation is discharged from the outlet  27  illustrated in  FIGS. 3 and 4 . 
     In this event, if some of the air blown over the heat radiating section  133  leaks to the surrounding without passing between the fins  133   a , cooling efficiency of the fins  133   a  is lowered. This lowered cooling efficiency of the fins  133   a  eventually causes a decrease in efficiency of cooling the CPU  111  and the chipsets  112 . 
     Here, in this embodiment, the dust filter  131  illustrated in  FIGS. 3 and 4  is disposed such that the filter main body  131   a  is inserted through the opening  28  illustrated in  FIG. 4  to be placed between the heat radiating section  133  and a blowing opening  134   a . The blowing opening  134   a  is directed toward the heat radiating section  133  so that the air pushed by the fan  134  comes out through the blowing opening  134   a.    
       FIG. 6  illustrates a state where the dust filter is placed so as to have the filter main body inserted between the blowing opening of the fan and the heat radiating section. 
     The filter main body  131   a  of the dust filter  131  removes dust from the air blown toward the heat radiating section  133  by the fan  134 . Thus, clogging between the fins  133   a  in the heat radiating section  133  or the like is avoided. However, the filter main body  131   a  resists the air blown toward the heat radiating section  133 . Therefore, some of the air hitting the filter main body  131   a  tends to veer off the direction heading toward the heat radiating section  133 . Here, in this embodiment, the filter main body  131   a  of the dust filter  131  also serves as a part of a duct wall which surely guides the air from the fan  134  to the spaces between the fins  133   a  included in the heat radiating section  133  while preventing air leaks to the surrounding. Meanwhile, a wall surface or the like of the main-unit housing  21  forms a different portion of the duct wall, which also helps forcibly guide the air that tends to veer toward the heat radiating section  133 . Thus, a decrease in cooling efficiency is prevented. 
     Moreover, this embodiment employs a commercially available fan as the fan  134  included in the cooling unit  130  and commercially available radiating fins as the heat radiating section  133 , so that a cost reduction is achieved. However, this has resulted in the differences in size and position between the blowing opening  134   a  in the fan  134  and the heat radiating section  133 , which will be described below. 
       FIG. 7  is an enlarged view of the fan and the heat radiating section in the cooling unit illustrated in  FIG. 5 . 
     As illustrated in  FIG. 7 , in this embodiment, a width d 1  of the blowing opening  134   a  is smaller than a width d 2  of the heat radiating section  133 . Moreover, the position of the right side surface of the blowing opening  134   a  is shifted from the position of the right side surface of the heat radiating section  133 . Furthermore, the position of the left side surface of the blowing opening  134   a  is also shifted from the position of the left side surface of the heat radiating section  133 . 
     Therefore, in this embodiment, in order to allow the filter main body  131   a  of the dust filter  131  to serve as a part of the duct wall, a shape of the dust filter  131  is designed as described below to guide the air blown out of the blowing opening  134   a  to the spaces between the fins  133   a  included in the heat radiating section  133 . 
       FIG. 8  is an enlarged view of the dust filter. 
       FIG. 8  illustrates the dust filter  131  with a side to contact the blowing opening  134   a  facing upward and a side to contact the heat radiating section  133  facing downward. 
     In this embodiment, the filter main body  131   a  of the dust filter  131  includes two shielding ribs, a shielding rib  131   c  on the fan side and a shielding rib  131   d  on the heat radiating section side, as shielding ribs for preventing the air blown out of the blowing opening  134   a  from leaking laterally. The shielding rib  131   c  protrudes along the side surface of the fan  134  toward the fan  134  from the side of the filter main body  131   a  that comes into contact with the blowing opening  134   a . The shielding rib  131   c  is provided at a position corresponding to the width d 1  of the blowing opening  134   a  illustrated in  FIG. 7 . Moreover, the shielding rib  131   d  protrudes along the side surface of the heat radiating section  133  toward the heat radiating section  133  from the side of the filter main body  131   a  coming into contact with the heat radiating section  133 . The shielding rib  131   d  is provided at a position corresponding to the width d 2  of the heat radiating section  133  illustrated in  FIG. 7 . 
       FIG. 9  illustrates a state where the dust filter and the fan are arranged.  FIG. 10  illustrates a state where the dust filter and the heat radiating section are arranged. 
     As illustrated in  FIG. 9 , the shielding rib  131   c  is provided at a position slightly outside the edge of the blowing opening  134   a . As a result, the filter main body  131   a  of the dust filter  131  is provided with an air inlet of a size and a position corresponding to those of the blowing opening  134   a  of the fan  134  so that the air blown out of the blowing opening  134   a  is taken into the filter main body  131   a  without any leak. 
     Moreover, as illustrated in  FIG. 10 , the shielding rib  131   d  is provided at a position slightly outside the edge of the heat radiating section  133 . Furthermore, a blocking plate  131   e  is provided between the shielding rib  131   c  and the shielding rib  131   d . Thus, as illustrated in  FIG. 10 , the air passing near the shielding rib  131   c  flows in a direction indicated by an arrow D and heads toward the heat radiating section  133  without leaking. In this structure, the filter main body  131   a  of the dust filter  131  is provided with an air outlet of a size and a position corresponding to those of a portion of the heat radiating section  133  onto which the air is blown, so that the air taken into the filter main body  131   a  flows toward the heat radiating section  133 . 
     As described above with reference to  FIGS. 6 to 10 , in the cooling unit  130  of this embodiment, the filter main body  131   a  of the dust filter  131  has the air inlet of the size and the position corresponding to those of the blowing opening  134   a  of the fan  134  and the air outlet of the size and the position corresponding to those of the portion of the heat radiating section  133  onto which the air is blown. Thus, the filter main body  131   a  serves as a part of the wall of the duct which takes in the air blown out of the blowing opening  134   a  without any leak and guides the air to the heat radiating section  133 . As a result, the CPU  111  and the chipsets  112  illustrated in  FIG. 5  are efficiently cooled. 
     Note that, there has been described the cooling unit  130 , illustrated in  FIG. 5 , of the type using the heat pipe  132   b  to transfer the heat to the heat radiating section, as an example of the cooling unit for cooling the CPU  111  and the chipsets  112 . However, the cooling unit for cooling the CPU  111  and the chipsets  112  is not limited to this type of cooling unit but may be of a different type which transfers the heat to the heat radiating section by circulating a coolant. This different type of cooling unit will be described below. Note that this different type of cooling unit will be hereinafter called a second cooling unit. 
       FIG. 11  illustrates a main unit of another embodiment in which the cooling unit in the main unit illustrated in  FIG. 5  is replaced with a second cooling unit which transfers heat to a heat radiating section by circulating a coolant. 
     A main unit  20 ′ of the another embodiment illustrated in  FIG. 11  has a second cooling unit  510  mounted thereon, which transfers heat to a heat radiating section by circulating a coolant, the second cooling unit being of a type different from that of the cooling unit  130  illustrated in  FIG. 5 . 
     The second cooling unit  510  includes one CPU heat absorbing section  511  and two chipset heat absorbing sections  512 , which are metal heat absorbing sections in which the coolant flows. Specifically, the CPU heat absorbing section  511  absorbs heat produced by a CPU  111 , and the chipset heat absorbing sections  512  absorb heat produced by two chipsets  112 , respectively. In the second cooling unit  510 , the above three heat absorbing sections are connected to each other. Inside the connected body, provided are partition walls  513  forming, together with pipes to be described later, a passage indicated by arrows in  FIG. 11  that guides the coolant to flow out of a heat radiating section  515  and back to the heat radiating section  515 . 
     Moreover, the second cooling unit  510  also includes a fan  514  equivalent to the fan  134  illustrated in  FIG. 5  and further includes the heat radiating section  515  having metal fins arranged in a blowing opening through which air from the fan  514  passes. Moreover, the heat radiating section  515  also includes a liquid passage through which the coolant flows, and the fins come into contact with the liquid passage. The air passing between the fins discharges heat of the coolant in the liquid passage. 
     The heat radiating section  515  is connected to the chipset heat absorbing section  512  through a first pipe  516  guiding the coolant from the heat radiating section  515  elsewhere. Moreover, the heat radiating section  515  is connected to the CPU heat absorbing section  511  through a second pipe  517  guiding the coolant to the heat radiating section  515 . 
     Moreover, the second cooling unit  510  includes a pump  518  for circulating the coolant. Thus, in the second cooling unit  510 , a circulating passage is formed, which allows the coolant to flow out of the heat radiating section  515 , through the two chipset heat absorbing sections  512 , the pump  518  and the CPU heat absorbing section  511  in this order, and then to come back to the heat radiating section  515 . 
     Here, among the CPU  111  and the two chipsets  112 , the CPU  111  is a maximum heat-producing element having a maximum heating value. In general, a conventional type of cooling unit, which transfers heat to a heat radiating section by circulating a coolant, often allows the coolant in a lowest temperature state, which has just left the heat radiating section, preferentially to flow to a maximum heat absorbing section which absorbs heat produced by the maximum heat-producing element such as the CPU. Meanwhile, from the viewpoint of heat resistance, many pumps used for circulating such a coolant have an upper limit set for a temperature of the coolant that flows therethrough. When the coolant preferentially flows to the maximum heat absorbing section as described above, the temperature of the coolant is likely to exceed the upper temperature limit in the pump. Thus, many conventional units require a complex passage, in which the coolant, after flowing out of the heat radiating section, goes to the maximum heat absorbing section thereby having the temperature increased, and then comes back to the heat radiating section again for radiating heat, and finally arrives at the pump. 
     In contrast, in the second cooling unit  510  illustrated in  FIG. 11 , the coolant that has just left the heat radiating section  515  preferentially flows to the chipset heat absorbing sections  512  absorbing the heat of the chipsets  112  having a heating value smaller than that of the CPU  111 . In the second cooling unit  510 , the chipset heat absorbing sections  512  serve as minimum heat absorbing sections having a heat absorption amount smaller than that of the CPU heat absorbing section  511  that is a maximum heat absorbing section. Moreover, in the second cooling unit  510 , the coolant that has left the chipset heat absorbing sections  512  as the minimum heat absorbing sections is sent to the CPU heat absorbing section  511  as the maximum heat absorbing section through the pump  518 . 
     In the development of the second cooling unit  510 , the following has been confirmed. Specifically, an increase in the temperature of the coolant due to the heat produced by the chipsets  112  does not exceed the upper temperature limit in the pump  518 . Furthermore, even the coolant having the temperature somewhat increased by the heat produced by the chipsets  112  sufficiently endures a transfer of heat produced by the CPU  111  and absorbed by the CPU heat absorbing section  511 . 
     The second cooling unit  510  cools the CPU  111  and the chipsets  112  with a shortest passage, unlike a conventional complex passage, by circulating the coolant in the above order. Therefore, the second cooling unit  510  is efficiently placed in a limited space within the electronic device and thus cools the electronic device. 
     Meanwhile, in the second cooling unit  510 , both of the two chipset heat absorbing sections  512  as the minimum heat absorbing sections are arranged on the upstream side of the pump  518 . Although the pump  518  generates some heat, the above arrangement of the two chipset heat absorbing sections  512  in the second cooling unit  510  makes it possible to cool both of the two chipsets  112  while avoiding the influence of the heat produced by the pump  518 . Thus, the second cooling unit  510  realizes further efficient cooling. 
     Moreover, in the second cooling unit  510 , the heat of the coolant inside the heat radiating section  515  is radiated by the air from the fan  514 . Thus, compared with, for example, heat radiation by natural convection, further efficient heat radiation is performed. 
     Note that, here, the description has been given of the structure in which all of the heat absorbing sections for the two chipsets are arranged on the upstream side of the pump in the flow of the coolant as an example of the cooling unit of the type which transfers the heat to the heat radiating section by circulating the coolant. However, the cooling unit of the type which transfers the heat to the heat radiating section by circulating the coolant is not limited thereto but at least one of the heat absorbing sections for the chipsets may be arranged on the upstream side of the pump. 
     Here, the second cooling unit  510  also includes a dust filter having a filter main body for removing dust from air flowing toward the heat radiating section  515  from the fan  514  and serving as a part of a duct wall for blowing air from the fan  514  onto the heat radiating section  515  without any leak. 
     Note that  FIG. 11  illustrates a state where the dust filter is removed. 
       FIG. 12  illustrates a state where the dust filter is attached in the second cooling unit illustrated in  FIG. 11 . 
     As illustrated in  FIG. 12 , also in the second cooling unit  510 , there is provided a dust filter  519  having a filter main body  519   a  inserted between a blowing opening  514   a  of the fan  514  and the heat radiating section  515 . 
     Here, in the second cooling unit  510 , a width of the blowing opening  514   a  (see  FIG. 11 ) and a width of the heat radiating section  515  are approximately equal to each other. Moreover, positions, in a width direction, of the blowing opening  514   a  and the heat radiating section  515  approximately agree with each other. 
     Meanwhile, as illustrated in  FIG. 12 , there is a difference between a height h 1  of the blowing opening  514   a  and a height h 2  of the heat radiating section  515 . Furthermore, positions of the blowing opening  514   a  and the heat radiating section  515  are shifted from each other in a height direction. Here, in the second cooling unit  510 , the shape of the filter main body  519   a  of the dust filter  519  is designed as described below to deal with the differences in height and position. 
     In this embodiment, first, in the filter main body  519   a  of the dust filter  519 , a shielding rib  519   b  for preventing the air coming out of the blowing opening  514   a  from leaking in the height direction is provided on the blowing opening  514   a  side having a relatively low height in the filter main body  519   a  of the dust filter  519 . 
       FIG. 13  illustrates a side of the dust filter illustrated in  FIG. 12 , which comes into contact with the blowing opening. 
     As illustrated in  FIG. 13 , the shielding rib  519   b  is a canopy-shaped rib protruding along an upper surface of the fan  514  toward the fan  514  from the side of the filter main body  519   a  coming into contact with the blowing opening  514   a . This shielding rib  519   b  is provided at a position in the filter main body  519   a , the position corresponding to the height h 1  (see  FIG. 12 ) of the blowing opening  514   a.    
     Moreover, in this embodiment, as illustrated in  FIG. 12 , an upper surface  519   c  of the dust filter  519  is provided at a position corresponding to the relatively high height h 2  of the heat radiating section  515 . Furthermore, an edge of the upper surface  519   c  on the heat radiating section  515  side protrudes toward the heat radiating section  515  to be in a canopy shape along an upper surface of the heat radiating section  515 . 
     Furthermore, as indicated by a dotted line in  FIG. 12 , a blocking plate  519   d  is provided to block a space between the shielding rib  519   b  and the upper surface  519   c  on the fan  514  side. Moreover, a passage of the air passing through the filter main body  519   a  extends from the fan  514  side toward the heat radiating section  515  as indicated by a dotted line in  FIG. 12 . Moreover, the shape of a lower surface opposed to the upper surface  519   c  in the dust filter  519  spreads toward a lower surface of the heat radiating section  515  from a lower surface of the blowing opening  514   a . This structure allows formation of an air inlet and an air outlet in the dust filter  519 , a size and a position of the air inlet corresponding to those of the blowing opening  514   a  of the fan  514  and a size and a position of the air outlet corresponding to those of a portion of the heat radiating section  515  onto which the air is blown. Thus, the air coming from the fan  514  heads toward the heat radiating section  515  without leaking. 
     Moreover, as in the case of the dust filter  131  illustrated in  FIG. 4  and the like, the dust filter  519  also has a leaf spring  519   e  provided as illustrated in  FIGS. 12 and 13 , the leaf spring being intended to fix the dust filter  519  with a pressing operation of the filter main body  519   a  against the housing. 
     In order to effectively press the filter main body  519   a  against the housing, the leaf spring  519   e  is preferably disposed as close to the filter main body  519   a  as possible. 
     Incidentally, in the second cooling unit  510  illustrated in  FIGS. 11 to 13 , the first and second pipes  516  and  517  are connected to the heat radiating section  515 . These pipes are arranged just proximal to the heat radiating section  515  along the flow of the air. Thus, if the leaf spring  519   e  of the dust filter  519  is disposed near the filter main body  519   a  as described above, the leaf spring  519   e  interferes with the first and second pipes  516  and  517 . On the other hand, when the pipes are detoured and arranged to dispose the leaf spring  519   e  at the desirable position, the circulation route of the coolant devised as described with reference to  FIG. 11  has to be extended. Such a detour lowers cooling efficiency of the second cooling unit  510 . 
     Therefore, the second cooling unit  510  is configured so that, in attachment of the dust filter  519 , the leaf spring  519   e  of the dust filter  519  is disposed at a position across the first and second pipes  516  and  517  arranged just proximal to the heat radiating section  515 . 
       FIG. 14  illustrates a state where the leaf spring of the dust filter is disposed at a position across the first and second pipes. 
     As illustrated in  FIG. 14 , in the second cooling unit  510 , the leaf spring  519   e  of the dust filter  519  is disposed at a position slightly distant from the filter main body  519   a.  Thus, in attachment of the dust filter  519 , the leaf spring  519   e  is disposed at a position across the first and second pipes  516  and  517  arranged just proximal to the heat radiating section  515 . In the second cooling unit  510 , such arrangement of the leaf spring  519   e  enables the first and second pipes  516  and  517  to be arranged just proximal to the heat radiating section  515 , thereby preventing a decrease in cooling efficiency. 
     Note that the description has been given of the dust filter  519  of a type having the leaf spring disposed to avoid the pipes passing near the heat radiating section as an example of the dust filter including the filter main body and the leaf spring. However, the dust filter having the leaf spring disposed to avoid the components near the heat radiating section is not limited to this example. For instance, the dust filter may be a type having the leaf spring disposed to avoid electronic components and the like near the heat radiating section. 
     This concludes the description of the another embodiment including the second cooling unit  510  with reference to  FIGS. 11 to 14 . Referring back to  FIG. 5  again, an internal structure of the main unit  20  of the personal computer  10  illustrated in  FIG. 5  will be described. 
     In the main unit  20 , various input signals generated using the keyboard  22 , the track pad  23  and the right and left click buttons  24  and  25  illustrated in  FIG. 2  by the user operating the respective parts are sent to the main board  110 . In this embodiment, three flat cables  140  are used to transmit the various input signals to the main board  110 . The three flat cables  140  each have one end connected to a connector mounted on a back side of the main board  110  through a path which is partially along an inner wall of the main-unit housing  21 , the back side of the main board  110  being opposed to the side having the CPU  111  and the cooling unit  130  mounted thereon. 
       FIG. 15  illustrates a state where the three flat cables illustrated in  FIG. 5  are connected to the connectors mounted on the back side of the main board. 
       FIG. 15  illustrates an enlarged view of a portion where the back side of the main board  110  is exposed from the main-unit housing  21  in a state where the keyboard  22  is detached from the main unit  20  illustrated in  FIG. 2 . 
     As illustrated in  FIG. 15 , on the back side of the main board  110 , three flat cable connectors  113  are mounted so as to correspond to the three flat cables  140 , respectively. The flat cables  140  are connected to the flat cable connectors  113 , respectively. 
     Here, in order to connect the flat cables  140  to the flat cable connectors  113 , respectively, in assembly of the main unit  20 , leading ends of the flat cables  140  have to be moved in a direction of connection to the flat cable connectors  113  indicated by arrows E in  FIG. 15 , in other words, in longitudinal directions of the flat cables  140 . 
     Conventionally, above operations are often performed by positioning the flat cables by temporarily fixing the flat cables to the housing or the like with tapes and then connecting the flat cables to the connectors by moving the leading ends of the flat cables in the longitudinal directions. Such a method requires some margins in length between the temporary fixing positions and the leading ends for allowing an operator to perform the operation by moving the leading ends. As a result, the lengths of the connected flat cables turn out to be redundant. Accordingly, there arises a problem that such redundancies hinder the assembly operation of the electronic device after connection of the flat cables and thus workability is lowered. 
     Therefore, in this embodiment, flat cable holding sections  21   a  for holding the flat cables  140  while allowing the flat cables  140  to be movable in the longitudinal directions are provided on the paths before reaching the flat cable connectors  113 , respectively. 
       FIG. 16  illustrates the cable holding sections from the front side of the main board illustrated in  FIG. 5 .  FIG. 17  illustrates the cable holding sections from a direction different from  FIG. 16  on the front side of the main board illustrated in  FIG. 5 . 
     The flat cable holding sections  21   a  are provided for the flat cables  140  respectively. The flat cable holding section  21   a  has a band-shaped structure, which protrudes higher than a thickness of the flat cable  140  from the inner wall of the main-unit housing  21 , is bent in a direction along the inner wall, and extends longer than a width of the flat cable  140  along the inner wall. 
     Each of the flat cables  140  extends toward the main board  110  from the front side of the main board  110  and reaches the back side of the main board  110  by passing under the extended portion of each of the flat cable holding sections  21   a . In this way, the flat cable  140  is connected to each of the flat cable connectors  113  as illustrated in  FIG. 15 . 
     Such a structure enables the flat cables  140  to be held by the flat cable holding sections  21   a  while being movable in the longitudinal directions when the flat cables  140  are to be connected to the flat cable connectors  113 . Thus, margins for moving the leading ends as in the conventional case are not particularly required to be prepared. Accordingly, the flat cables  140  is shortened and thus the workability is improved. 
     Moreover, in this embodiment, the main board  110  is attached to the inner wall of the main-unit housing  21 . The flat cables  140  are connected to the flat cable connectors  113  mounted on the back side of the main board  110 , that is, the inner wall side of the main board  110 . With this structure, in the processing of connecting the flat cables  140 , the main-unit housing  21 , which is in a state of having the main board  110  attached thereto and having the flat cables  140  laid to some extent, needs to be turned over at least once. In this embodiment, during turning over the main-unit housing  21 , the flat cables  140  are held by the above flat cable holding sections  21   a . Thus, the main-unit housing  21  may be turned over while maintaining the positions of the arranged flat cables  140 . In this regard as well, the workability is improved. 
     Moreover, as described above, in this embodiment, each of the flat cable holding sections  21   a  is provided for each of the flat cables  140 . Thus, the positions of the flat cables  140  are surely maintained for each of the flat cables  140  as described above. 
     Note that the description has been given here of the flat cable holding sections  21   a  holding the flat cables as an example of the cable holding sections for holding the cables so that the cables are movable along the arrangement paths as described above. However, such cable holding sections are not limited to the use in holding the flat cables but also may be applied to hold general cables. 
     This concludes the description of the flat cables  140  with reference to  FIGS. 15 to 17 . Referring back to  FIG. 5  again, description of the internal structure of the main unit  20  of the personal computer  10  of this embodiment will be continued. 
     As described above, the main unit  20  has the main board  110  and the sub-board  120  housed therein, the sub-board being connected to the main board  110  through a connector and including an antenna module to be described later and the like mounted thereon. 
     Here, in this embodiment, the sub-board  120  is fixed to the main board  110  and the main-unit housing  21  with screws. Thus, through-holes through which the screws for fixing those described above penetrate are provided in the sub-board  120 . 
       FIG. 18  is an enlarged view of the sub-board illustrated in  FIG. 5 . 
     As illustrated in  FIG. 18 , in the sub-board  120 , provided are: two through-holes (main board through-holes)  121  for screwing the sub-board  120  to the main board  110 ; and four through-holes (housing through-holes)  122  for screwing the sub-board  120  to the main-unit housing  21 . 
     Moreover, in this embodiment, the two main board through-holes  121  are circular holes and the four housing through-holes  122  are elongate holes. 
     This is because the sub-board  120  and the main board  110  are connected to each other through connectors as described below. 
       FIG. 19  illustrates a state where the sub-board detached from the main board is turned over and the connectors of the respective boards is seen.  FIG. 20  is a side view illustrating how the sub-board connector and the main board connector are connected to each other. 
     Note that  FIGS. 19 and 20  illustrate a state where the antenna module to be described later is detached from the sub-board. 
     As illustrated in  FIG. 19 , the sub-board  120  includes a rectangular male connector  123  for connection to the main board  110  on a back side opposed to the side illustrated in  FIG. 18 . Meanwhile, the main board  110  includes on its front side a rectangular female connector  114  to be engaged with the male connector  123 . These two board connectors are connected to each other as illustrated in  FIG. 20  in assembly of the main unit  20 . 
     Here, the male connector  123  is attached to the sub-board  120 , and the female connector  114  is attached to the main board  110  by soldering the connectors to the boards, respectively. Thus, a position on the sub-board  120  to which the male connector  123  is attached, and a position on the main board  110  to which the female connector  114  is attached may be erroneously shifted in a rotational direction from their respective attachment positions in design. 
     When there are such shifts in the rotational direction in the attachment positions of the male connector  123  and the female connector  114 , the sub-board  120  is shifted in a circumferential direction indicated by an arrow F around the male connector  123  as illustrated in  FIG. 18 . As a result, between each of the six through-holes provided in the sub-board  120  and each of screw holes corresponding thereto, there occur positional shifts around the male connector  123  in a direction corresponding to the circumference according to a distance from the center. Among the six through-holes, the two main board through-holes  121  are provided near the male connector  123 , and thus, such positional shifts are small. However, the four housing through-holes  122  provided at positions distant from the male connector  123  may have large positional shifts. 
     Therefore, in this embodiment, in order to cope with such positional shifts, the four housing through-holes  122  are formed to be the elongate holes extending in the direction of a tangent to the circumference passing through the screw attachment positions around the male connector  123 . Thus, even if there are such shifts of the attachment positions of the male connector  123  and the female connector  114 , the sub-board  120  is easily screwed to the main-unit housing  21 . 
     Note that, in consideration of a manufacturing workability, this embodiment provides the description in which the direction of the tangent to the circumference passing through the screw attachment positions is used as an example of a direction having a predetermined relationship with the circumference. Moreover, the housing through-holes  122  are formed as elongate holes linearly extended in the direction of the tangent to the circumference passing through the screw attachment positions. However, the direction having the predetermined relationship with the circumference passing through the screw attachment positions may be a direction along the circumference. Moreover, the housing through-holes  122  may be circular elongate holes along the circumference. 
     Moreover, here, the screws have been described as an example of fastening members for fixing the sub-board  120  to the main board  110  and the main-unit housing  21  as described above. However, the fastening members are not limited to the screws but may be other kinds of fastening members such as press-fit pins. 
     This concludes the description of screwing the sub-board  120  with reference to  FIGS. 18 to 20 . Referring back to  FIG. 5  again, description of the internal structure of the main unit  20  of the personal computer  10  of this embodiment will be continued. 
     In this embodiment, the main unit  20  includes a TV signal connector  150  capable of receiving a TV antenna signal. Moreover, a TV signal cable  160  extending from the TV signal connector  150  to transmit the TV antenna signal is connected to the antenna module to be described later which is mounted on the back side of the sub-board  120 . 
       FIG. 21  illustrates a state where the TV signal cable illustrated in  FIG. 5  is connected to the antenna module mounted on the back side of the sub-board.  FIG. 22  illustrates the antenna module having the TV signal cable connected thereto. 
     An antenna module  170  is a board for converting the TV antenna signal into a signal that may be handled within the personal computer  10  by performing signal processing compliant with predetermined communication standards, the TV antenna signal received by the TV signal connector  150  and transmitted through the TV signal cable  160 . This antenna module  170  is mounted on the back side of the sub-board  120 . Moreover, on the antenna module  170 , a connector (input connector)  171  for inputting a TV signal to the antenna module  170  is mounted. Furthermore, the TV signal cable  160  includes a TV signal output connector  161  at its leading end on the antenna module  170  side, the TV signal output connector  161  being connected to the TV signal input connector  171 . 
     Here,  FIG. 22  illustrates an enlarged view of a portion where the antenna module  170  is exposed from the main-unit housing  21  in a state where the keyboard  22  is detached from the main unit  20  illustrated in  FIG. 2 . As illustrated in  FIG. 22 , the main-unit housing  21  includes an operation opening  21   b  for the operator to access the TV signal input connector  171  of the antenna module  170  in assembly of the main unit  20 . The TV signal output connector  161  of the TV signal cable  160  is connected to the TV signal input connector  171  of the antenna module  170  with an operation through the operation opening  21   b  in the main-unit housing  21 . 
     Here, generally, the above TV signal connector is often attached to the back side of the main unit of the personal computer as in the case of this embodiment illustrated in  FIG. 5 . On the other hand, the antenna module may be disposed at a position near the front side opposed to the back side, as in the case of this embodiment illustrated in  FIG. 5 , as a matter of arrangement convenience inside the main unit. In this case, the output connector of the TV signal cable is connected to the input connector of the antenna module in the following manner. First, as illustrated in  FIG. 5 , the lower surface of the main unit is turned up and the TV signal cable is arranged so as to allow the output connector to come close to the antenna module. Thereafter, the main unit is turned over and the output connector is connected to the input connector with an operation through the operation opening for the access to the antenna module on the upper surface of the main unit. Conventionally, during such an operation, operational inefficiency often occurs in that the TV signal cable has to be rearranged, since the output connector of the TV signal cable retracts into the housing when the main unit is turned over. 
     To avoid such operational inefficiency, in the main unit  20  of this embodiment, the TV signal output connector  161  may be temporarily held when the TV signal cable  160  is arranged as described above. For this purpose, a TV signal cable holding section  21   c  is provided on the lower surface illustrated in  FIGS. 5 and 21  in the main-unit housing  21 . Specifically, the TV signal cable holding section  21   c  holds the TV signal cable  160  so as to allow a part (that is an end or a middle part) of the TV signal cable  160  to reach the operation opening  21   b.    
       FIG. 23  is an enlarged view illustrating the cable holding section together with the output connector temporarily held by the cable holding section. 
     The TV signal cable holding section  21   c  has a slit formed therein, the slit having a width smaller than the size of the TV signal output connector  161 . Once the TV signal cable  160  is arranged as described above, a cable main body  162  is inserted into the slit as illustrated in  FIG. 23 . As mentioned above, the slit in the TV signal cable holding section  21   c  has the width smaller than the size of the TV signal output connector  161 . Therefore, even when the main unit  20  is turned over to connect the TV signal output connector  161  to the TV signal input connector  171  of the antenna module  170 , the TV signal output connector  161  remains being held by the TV signal cable holding section  21   c . Accordingly, it is possible to avoid such an operational inefficiency that the TV signal output connector  161  retracts into the main-unit housing  21  during the operation. In this embodiment, the workability is improved by such an action of the TV signal cable holding section  21   c.    
     Moreover, in this embodiment, the antenna module  170  has the TV signal input connector  171  on the side facing the operation opening  21   b . Thus, the connectors are allowed to be connected through the operation opening  21   b . In this regard as well, the workability is improved. 
     Moreover, in this embodiment, the TV signal cable holding section  21   c  is provided on the arrangement path of the TV signal cable  160  and on the edge of the operation opening  21   b . Thus, the operation of connecting the connectors through the operation opening  21   b  is facilitated. Thus, the workability is further improved. 
     Note that, here, the description has been given of the TV signal cable  160  and the antenna module as examples of the cable and the board, which are connected to each other by engaging the connectors thereof with each other. However, the cable and the board are not limited thereto and a radio communication cable and a radio module, for example, may be used. 
     This concludes the description of the internal structure of the main unit  20  with reference to  FIGS. 5 to 23 . Next, the display unit  30  illustrated in  FIG. 2  will be described. 
       FIG. 24  illustrates the display unit illustrated in  FIG. 2  in a state of being detached from the main unit. 
     As described above, the display unit  30  has the flat liquid crystal panel  32 , the control circuit for the liquid crystal panel and the like housed in the display housing  31 . Moreover, the display housing  31  includes an upper panel  311  and a lower panel  312 . The upper panel  311  is a housing wall forming a frame of an opening through which a display screen of the liquid crystal panel  32  is exposed. The lower panel  312  is a housing wall facing the upper panel  311  with an internal space therebetween. In the internal space, the liquid crystal panel  32  and the like are housed. Electronic components to be housed in the display unit  30 , such as the liquid crystal panel  32 , are fixed to the lower panel  312 . 
       FIG. 25  illustrates the upper panel removed from the display unit.  FIG. 26  illustrates the display unit having the upper panel removed therefrom. 
       FIG. 25  illustrates the upper panel  311  in a reversed state. Moreover,  FIG. 25  illustrates a connection side of the main unit  20  and the display unit  30  positioned frontward. 
       FIG. 26  illustrates the liquid crystal panel  32  fixed to the lower panel  312 , an inverter circuit board  33  for turning on a backlight of the liquid crystal panel  32 , and the like. Moreover, in the lower panel  312 , a concave section  313  for housing the inverter circuit board  33  is provided, the concave section  313  being formed of ribs surrounding its periphery. The inverter circuit board  33  is housed in the concave section  313  in a state of being covered with a retaining sheet  34  for retaining the inverter circuit board  33  in the concave section  313 . Specifically, the retaining sheet  34  is formed of a PET film and details thereof will be described later. 
     In this embodiment, the upper panel  311  is fixed to the lower panel  312  by use of screws or by locking with locking claws provided on an outer edge of the upper panel  311 . 
     Here, a lower frame part  311   a  of the upper panel  311  on the connection side is wider than an upper frame part  311   b  opposed to the connection side or two side frame parts  311   c.  Thus, in the lower frame part  311   a , a space is easily formed between the liquid crystal panel  32  and an inner edge of the lower frame part  311   a.    
     Therefore, in this embodiment, four locking claws  311   d  for preventing the lower frame part  311   a  and the lower panel  312  from separating from each other by fixing the inner edge of the lower frame part  311   a  to the lower panel  312  are arranged near the inner edge so as to align along the edge of the liquid crystal panel  32  in a state where the upper panel  311  is assembled to the lower panel  312 . The four locking claws  311   d  are protrusions protruding toward the lower panel  312  from the lower frame part  311   a . The locking claws  311   d  catch on a rib (liquid crystal side rib)  313   a  on the liquid crystal panel  32  side among the ribs forming the concave section  313  illustrated in  FIG. 26  and a short rib  314  arranged to the right, in  FIG. 26 , of the liquid crystal side rib  313   a  with a wiring space left therebetween. 
       FIG. 27  illustrates a state where the locking claws  311   d  arranged on the lower frame part, the liquid crystal side rib  313   a  and the short rib  314  are lined up. 
     As illustrated in  FIG. 27 , the liquid crystal side rib  313   a  has three locking holes  313   a _ 1  provided therein and the short rib  314  has one locking hole  314   a  provided therein. Among the four locking claws  311   d , the three locking claws  311   d  on the left side in  FIG. 27  catch on the three locking holes  313   a _ 1  in the liquid crystal side rib  313   a , respectively. Moreover, among the four locking claws  311   d , the one locking claws  311   d  on the right side in  FIG. 27  catches on the locking hole  314   a  in the short rib  314 . 
     When the four locking claws  311   d  catch on the three locking holes  313   a _ 1  in the liquid crystal side rib  313   a  and the one locking hole  314   a  in the short rib  314 , respectively, the inner edge of the lower frame part  311   a  is fixed to the lower panel  312 . Thus, the liquid crystal panel  32  and the inner edge of the lower frame part  311   a  are prevented from being spaced apart from each other. 
     Moreover, since the lower frame part  311   a  is wide as described above, the lower frame part  311   a  is easily bent when pressed by the user or the like. 
     Therefore, in this embodiment, the liquid crystal side rib  313   a  and the short rib  314  are formed so as to have their upper edges come into contact with the lower frame part  311   a  of the upper panel  311  in a state where the upper panel  311  is attached to the lower panel  312 . Thus, the liquid crystal side rib  313   a  and the short rib  314  react to the pressure applied to the lower frame part  311   a , thereby preventing the lower frame part  311   a  from bending. 
     Here, in this embodiment, as described above, in the state where the upper panel  311  is attached to the lower panel  312 , the locking claws  311   d , for preventing the liquid crystal panel  32  and the inner edge of the lower frame part  311   a  from being spaced apart from each other, and the ribs  313   a  and  314  for preventing the lower frame part  311   a  from bending are integrated with each other. Thus, in this embodiment, the spacing and bending are efficiently prevented within a limited space. 
     Note that, here, the description has been given of the structure in which the four locking claws  311   d  are provided as protrusions protruding toward the lower panel  312  from the upper panel  311  and the two types of ribs, the liquid crystal side rib  313   a  and the short rib  314 , are provided as the protrusions protruding toward the upper panel  311  from the lower panel  312 . However, the numbers of claws and ribs are not limited thereto. Alternatively, the number of the claws and that of the ribs may be different from each other or different from the example described above, or a single claw and a single rib may be provided. Furthermore, only the number of either the claws or the ribs may be more than one. 
     Moreover, here, the description has been given of the display housing  21  having the opening provided therein, through which the display screen of the liquid crystal panel  32  is exposed. However, spacing and bending prevention by the locking claws and the ribs may be also applied to prevention of spacing and bending between simple housing walls having no such opening provided therein. 
     Next, a structure of housing the inverter circuit board  33  in the lower panel  312  will be described. 
       FIG. 28  is an enlarged view of the inverter circuit board in a housed state. 
     Note that, in  FIG. 28 , the liquid crystal panel  32  is detached from the lower panel  312 . 
     As described above, in the lower panel  312 , the concave section  313  is provided, which is surrounded by multiple ribs including the liquid crystal side rib  313   a.  Moreover, the inverter circuit board  33  is housed in the concave section  313  in the state of being covered with the retaining sheet  34 . 
     Here, in this embodiment, the retaining sheet  34  covering the inverter circuit board  33  retains the inverter circuit board  33  within the concave section  313 . 
       FIG. 29  illustrates a state where a portion, covering an upper side of the inverter circuit board, in the retaining sheet covering the inverter circuit board is opened.  FIG. 30  illustrates a state where the inverter circuit board is taken out of the concave section  313  together with the retaining sheet. 
     The retaining sheet  34  has a bottom portion  341 , a side portion  342  and an upper portion  343 . The bottom portion  341  covers a rear surface of the inverter circuit board  33 , which is opposed to a component mounting surface, and is provided between the rear surface of the inverter circuit board  33  and a bottom of the concave section  313 . The side portion  342  is bent toward the component mounting surface from the bottom portion  341 . The upper portion  343  is bent from the side portion  342  so as to cover the component mounting surface. 
     In housing of the inverter circuit board  33 , a surface of the bottom portion  341  on the bottom side of the concave section  313  is attached to the bottom of the concave section  313  with a double-sided tape. 
     Moreover, three rectangular protrusions  343   a  are provided on an edge of the upper portion  343 . Moreover, two cutouts  313   a _ 2  and one protrusion hole  313   a _ 3  are provided on the liquid crystal side rib  313   a  among the ribs forming the concave section  313 . In housing of the inverter circuit board  33 , the two left and right protrusions  343   a  among the three protrusions  343   a  are fitted into the two cutouts  313   a _ 2  as illustrated in  FIG. 28 . Moreover, in housing of the inverter circuit board  33 , the center protrusion  343   a  among the three protrusions  343   a  is fitted into the one protrusion hole  313   a _ 3  as illustrated in  FIG. 28 . Furthermore, a cushion member  344  for elastically pressing the inverter circuit board  33  is attached to a surface of the upper portion  343  on the inverter circuit board  33  side. 
     When the inverter circuit board  33  is housed in the concave section  313  in the state of being covered with the retaining sheet  34  as illustrated in  FIG. 28 , there occur the following actions: the bottom portion  341  is attached to the bottom of the concave section  313 ; the edge of the upper portion  343  is locked by fitting the three protrusions  343   a  into the cutouts  313   a _ 2  and the protrusion hole  313   a _ 3 ; and the inverter circuit board  33  is pressed by the cushion member  344 . With these actions, the inverter circuit board  33  is retained in the concave section  313 . 
     In this embodiment, a metal radiator plate  35  for diffusing heat produced by the inverter circuit board  33  is attached to the lower panel  312 , and a part of the radiator plate  35  extends into the concave section  313 . Further, the bottom portion  341  of the retaining sheet  34  made of an insulating material of the PET film also has a function of insulating the radiator plate  35  and the inverter circuit board  33  from each other. 
     Here, it is conceivable to allow the retaining sheet  34  to have other functions than the insulating function unlike this embodiment. 
     As a conceivable example, a retaining sheet of a different structure may be formed of a so-called graphite sheet that is a resin material containing graphite and has a good thermal diffusion property to diffuse heat produced by the inverter circuit board. Further, as another conceivable example, a retaining sheet of a different structure may be formed of a so-called radio wave absorbing sheet that is a resin material containing ferrite and has a good radio wave absorbing property to absorb electromagnetic noise generated by the inverter circuit board. Here, in the graphite sheet or the radio wave absorbing sheet, graphite or ferrite contained in the corresponding resin material is conductive. Thus, in order to secure insulation properties in each of the sheets, insulating layers made of an insulating material such as PET are generally formed on both surfaces of each sheet. 
     Incidentally, the liquid crystal panel  32  of this embodiment illustrated in  FIG. 26  is a single-lamp liquid crystal panel using one fluorescent lamp as a backlight. The inverter circuit board  33  is a single-lamp inverter circuit board corresponding to the single-lamp liquid crystal panel. 
     Generally, as the liquid crystal panel used in the notebook personal computer, other than the single-lamp liquid crystal panel, there is a double-lamp liquid crystal panel using two fluorescent lamps. Since the single-lamp liquid crystal panel and the double-lamp liquid crystal panel often have the same external shape or the like, a common housing that allows the both types of liquid crystal panels to be attached thereto is desired in terms of reduction in manufacturing cost, and the like. 
     On the other hand, external dimensions and the like of the inverter circuit board often differ between the single-lamp type and a double-lamp type. Conventionally, the inverter circuit board is often retained in the housing by screwing or the like. Thus, in many cases, screwing positions or the like for retaining the inverter circuit board differ between the single-lamp type and the double-lamp type. Therefore, conventionally, such a difference becomes a factor that hinders realization of the housing that may be commonly used for the single-lamp type and the double-lamp type. 
     Meanwhile, in this embodiment, as a method for retaining the inverter circuit board  33 , the method for covering the inverter circuit board  33  with the retaining sheet  34  is adopted as described above. Thus, a conventional structure such as screw holes for retaining the inverter circuit board, which hinders common use of the housing between the single-lamp type and the double-lamp type, is no longer required in the display housing  31  of the display unit  30 . As a result, in this embodiment, a double-lamp inverter circuit board is housed and retained in the concave section  313  for housing the single-lamp inverter circuit board  33  to be described below. 
       FIG. 31  illustrates a state where the single-lamp inverter circuit board also illustrated in  FIG. 29  and the like and the double-lamp inverter circuit board are laid out.  FIG. 32  illustrates a state where the double-lamp inverter circuit board is housed in the concave section for housing the single-lamp inverter circuit board. 
     As illustrated in  FIG. 31 , a double-lamp inverter circuit board  55  is longer and slightly wider than the single-lamp inverter circuit board  33 , which is adopted in this embodiment, due to differences in sizes and types of mounted components, the number thereof and the like therebetween. 
     Here, as illustrated in  FIG. 29  or the like, in this embodiment, the concave section  313  is formed to be slightly wider than the single-lamp inverter circuit board  33 . In this embodiment, the cushion member  344  attached to the upper portion  343  of the retaining sheet  34  also functions to prevent the single-lamp inverter circuit board  33  from moving within the wide concave section  313 . The width of the concave section  313  is designed with regard to the double-lamp inverter circuit board  55  which may possibly be housed therein. Thus, the concave section  313  has the width that allows the double-lamp inverter circuit board  55  to be just fitted therein as illustrated in  FIG. 32 . 
     For housing and retaining the double-lamp inverter circuit board  55 , the retaining sheet  34  used for housing and retaining the single-lamp inverter circuit board  33  is used as it is as illustrated in  FIG. 32 . 
     Specifically, the bottom portion  341  of the retaining sheet  34  is attached to the bottom of the concave section  313  with a double-sided tape, and the upper portion  343  covers a component mounting surface of the double-lamp inverter circuit board  55 . Moreover, the three protrusions  343   a  are fitted into the two cutouts  313   a _ 2  and the one protrusion hole  313   a _ 3  in the liquid crystal side rib  313   a.  In this event, the cushion member  344  attached to the upper portion  343  elastically presses the double-lamp inverter circuit board  55 . Thus, the double-lamp inverter circuit board  55  is retained in the concave section  313  as in the case of the single-lamp inverter circuit board  33 . 
     As described above, in this embodiment, the display housing  31  having the single-lamp liquid crystal panel  32  and the single-lamp inverter circuit board  33  mounted therein may also be used for the double-lamp liquid crystal panel and the double-lamp inverter circuit board  55 . Thus, unlike the conventional case, it is no longer required to prepare housings for the respective types. As a result, manufacturing cost may be reduced. 
     Note that the notebook personal computer  10  has been described above as an example of the electronic device. However, the electronic device of the present invention is not limited thereto. The electronic device may be other types of personal computers such as a desktop type or a laptop type, or may be a computer more sophisticated than the personal computer. Alternatively, the electronic device is not limited to the computer but may be household electrical appliances or the like. 
     As described above, according to the embodiment, it is possible to obtain a housing where separation of housing walls and a warp of a wall due to an external force is efficiently prevented in a limited space, and also to realize an electronic device mounted with such a housing. 
     All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although the embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.