Abstract:
It is an object of the present invention to provide a cabinet capable of containing various devices and securely attaching/detaching an additional device thereto/therefrom, and to provide an additional device. In order to achieve the object, a cabinet according to the present invention includes: a conductive cylinder having an aperture into which the additional device is fitted by insertion and containing an electronic device, the aperture having a folded edge, the additional device operating in parallel with the electronic device; and a reinforcing member supported with a portion of an inner wall of the cylinder and disposed on a boundary between two areas inside the cylinder where the electronic device and the additional device are disposed respectively, the portion of the inner wall being more inside than the folded portion of the aperture.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2003-421992, filed on Dec. 19, 2003, the entire contents of which are incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a cabinet configured to contain a desired device and to have, on a side portion thereof, an additional device which operates in association with or in parallel with the desired device, and it relates to the additional device.  
         [0004]     2. Description of the Related Art  
         [0005]     In recent years, various operators employ cabinets in compliance with the EIA standard or the JIS standard to accommodate many devices such as routers and servers of a data communication network which are given maintenance and expansion when necessary, the cabinet containing these devices together in the same site or office premise (may be a single rack).  
         [0006]      FIG. 10 ( a ) and  FIG. 10 ( b ) show a structural example (1) of a conventional cabinet.  
         [0007]      FIG. 11  shows a structural example (2) of the conventional cabinet.  
         [0008]     As shown in  FIG. 10 ( a ),  FIG. 10 ( b ), and  FIG. 11 , the conventional cabinet is composed of the following elements: 
    (1) A cylinder  52  made of metal (aluminum or the like) having: two apertures with one edge folded with a margin of a prescribed width (assumed here to be small to such an extent as not to close the aperture) at a right angle in a direction of the axis of the cylinder; attached thereto a printed board  51  with components constituting a desired device (a router or the like) mounted in a hollow portion thereof; and a cross section thereof in a rectangular shape;     (2) A front cover  53 : connected to an electronic circuit (including later-described receptacles  51 R- 1 ,  51 R- 2 ) on the printed board  51 ; having attached thereto electronic components used for connection of the electronic circuit to a man-machine interface and to an exterior; fitted (or fastened) to the aperture of the aforesaid cylinder  52  with no folded edge; having in advance a slit or the like corresponding to a ventilation path to the exterior in advance and preventable of radiation of electro magnetic interference generated in the electronic circuit to the exterior;     (3) A decorative frame  56  having a cross section in a substantially U shape and covering the aforesaid cylinder  52  and both of cabinets  55 - 1 ,  55 - 2  (assumed here that a width w thereof is half (=W/2) a width W (&lt;19 inch) of the aforesaid aperture, and a thickness t thereof is equal to a thickness T of this aperture) containing later-described two power supply units  54 - 1 ,  54 - 2  (the power supply unit  54 - 2  is omitted in  FIG. 10 ( a ) and  FIG. 10 ( b ) in order to clearly show the inside of the cylinder  52 ) adjacent to the aperture, the cabinets  55 - 1 ,  55 - 2  being made of metal in a rectangular parallelepiped shape to contain part of the power supply units  54 - 1 ,  54 - 2  respectively.    
 
         [0012]     The aforesaid cabinet  55 - 1  is formed in the following manner:  
         [0013]     (1) A bending margin that is equal in size and shape to the aforesaid bending margin is reserved in an aperture at the one aperture of the cylinder  52 , and the bending margin is bent at a right angle in a direction so as to narrow this aperture.  
         [0014]     (2) A bottom of the cabinet  55 - 1  is formed as a detachable metal plate  55 B- 1 .  
         [0015]     (3) Two air vents  57 - 11 ,  57 - 12  and two decorative screws  58 - 11 ,  58 - 12  rotatable from an exterior are attached to predetermined positions of the plate  55 B- 1 , and fans  59 - 11 ,  59 - 12  are mounted inside the air vents  57 - 11 ,  57 - 12 .  
         [0016]     (4) Screw holes formed in the bending margins of the apertures of the cabinet  55 - 1  and the cylinder  52 , for a predetermined number of screws to screw-fix the cabinet  55 - 1  and the cylinder  52  to each other.  
         [0017]     Further, the power supply unit  54 - 1  is constituted of the following elements: 
    (1) a printed board  61  fixed to the aforesaid plate  55 B- 1  at one end and having at the other end thereof a plug  60 P- 1  fitted to the receptacle  51 R- 1 ; and     (2) a power supply circuit  62 - 1  formed on the printed board  61 - 1  to supply power to the circuit disposed on the printed board  51  via the aforesaid plug  60 P- 1  and receptacle  51 R- 1  and to drive the fans  59 - 11 ,  59 - 12 .    
 
         [0020]     Since the structures of the power supply units  54 - 2  and the cabinet  55 - 2  are the same as those of the power supply unit  54 - 1  and the cabinet  55 - 1  respectively, explanation and illustration thereof will be omitted here, and the same reference numerals and symbols with a suffix number ‘2’ instead of ‘ 1 ’ will be used to designate corresponding portions.  
         [0021]     A device including the cabinet as configured above is assembled in the following procedure.  
         [0022]     (1) The printed board  51  whose assembly has been finished is mounted in the hollow portion of the cylinder  52 .  
         [0023]     (2) The front cover  53  is attached to the other aperture of the cylinder  52 .  
         [0024]     (3) The decorative screws  58 - 11 ,  58 - 12 ,  58 - 21 ,  58 - 22  are screwed off from the power supply units  54 - 1 ,  54 - 2  whose assembly has been finished, and the plates  55 B- 1 ,  55 B- 2  are detached from the bottoms of the cabinets  55 - 1 ,  55 - 2 . It is assumed that even during this process, power supply routes to the fans  59 - 11 ,  59 - 12  are kept via lead wires connected to the power supply circuits  62 - 1 ,  62 - 2  respectively.  
         [0025]     (4) Screws used for screw-fixing the apertures of the cabinets  55 - 1 ,  55 - 2  to the one aperture of the cylinder  52  from the bottom (holes formed by the aforesaid detachment of the plates  55 B- 1 ,  55 B- 2 ) side of the cabinets  55 - 1 ,  55 - 2 .  
         [0026]     (5) The bottoms of the cabinets  55 - 1 ,  55 - 2  are closed with the plates  55 B- 1 ,  55 B- 2  through performing the above procedure in reverse ( 3 ).  
         [0027]     (6) The decorative frame  56  is placed to cover an external wall except bottom faces of the cabinets  55 - 1 ,  55 - 2  and the cylinder  52 .  
         [0028]     A prior art to enhance or maintain high stiffness of a cabinet similarly to the present invention is disclosed in, for example, Japanese Unexamined Patent Application Publication No. 2001-148578.  
         [0029]     In the above-described conventional example, in order to prevent radiation of electronic magnetic interference generated in the electronic circuit disposed on the printed board  51  to the exterior of the cabinet, it is necessary to electrically tightly connect the cylinder  52  to the cabinets  55 - 1 ,  55 - 2  by the aforesaid screw-fixing or to similarly maintain stable and close electrical connection between the cylinder  52  and the cabinets  55 - 1 ,  55 - 2  via conductive springs  71  or the like as shown by ( 1 ) in  FIG. 12 .  
         [0030]     Further, the springs  71  give a strong pressure to the apertures of the cylinder  52  and the cabinets  55 - 1 ,  55 - 2 . Generally, however, the cylinder  52  and the cabinets  55 - 1 ,  55 - 2  are preferably thin and made of light-weight metal so that the cylinder  52  is required to have a reinforcing member  72  at least near the aperture in order to prevent it from deforming against the pressure as shown by ( 2 ) in  FIG. 12 .  
         [0031]     However, the bending margin of the aperture of the cylinder  52  reduces the volume of an available space in the hollow portion of the cylinder  52  in which desired components including the aforesaid printed board  51  are disposed. In addition, even without such a bending margin, the available space is narrowed by the aforesaid reinforcing member  72  and the springs  71 , which possibly prevents desired high density assembly and downsizing of the cylinder.  
         [0032]     Moreover, in the conventional example, the cylinder  52  and the cabinets  55 - 1 ,  55 - 2  are electrically closely coupled in order to suppress radiation of the electro magnetic interference in a high-frequency band ranging from several mega hertz to several gigahertz generated in the electronic circuit on the printed board  51  and of the electro magnetic interference in a bandwidth of several hundred kilohertz or less generated in the power supply circuits  62 - 1 ,  62 - 2  during the process of voltage conversion by switching.  
         [0033]     Therefore, for example, with the power supply unit  54 - 2  detached for replacement or not mounted, the power supply and forced air cooling relies on the power supply unit  54 - 1 , so that an expensive shield has to be provided in order to prevent the radiation of the electro magnetic interference in a high-frequency band.  
         [0034]     Moreover, in the conventional example, the heat release efficiency of the electronic circuit lowers if either of the power supply units  54 - 1 ,  54 - 2  is not mounted or either of the fans incorporated therein is in fault. Therefore, it is required to set the performance or the rotation speed of the fans  59 - 11 ,  59 - 12 ,  59 - 21 ,  59 - 22  with a sufficient margin so as to maintain the operational temperature of the electronic circuit while the power is continuously supplied to the electronic circuit.  
         [0035]     Generally, when power supply units to be plugged into the cabinets of individual devices do not incorporate fans, the larger the number of devices contained in the rack and the thinner the thickness of the cabinets in which the bodies of the devices are mounted, with higher assembly density many power supply units and fans are mounted. Besides, it is difficult to make air exhaustion or suction in the same direction by the fans.  
         [0036]     In such a case, it is likely that the size of the cabinets of the devices contained in the same rack increases since the rack needs to have complex ventilation paths for the purpose of compensating or adapting to the exhaustion and suction in various directions.  
       SUMMARY OF THE INVENTION  
       [0037]     It is an object of the present invention to provide a cabinet that can contain various devices and to which a desired additional device closely related to the contained devices is detachably, securely attached, without great increase in manufacturing cost or any structural complication, and to provide the additional device.  
         [0038]     It is another object of the present invention to reduce the weight and size of a device and a system to which the present invention is applied and realize high density assembly thereof as well as to make the device and system be adaptable to various system configurations, without increasing manufacturing cost and restrictions on thermal design, and complexing the structure.  
         [0039]     It is still another object of the present invention to stably and securely attach/detach the additional device to/from the cylinder of the cabinet even if the thickness or hardness of the cylinder is small because the cabinet of the additional device can have a resisting force against bending force physically acting on or around the aperture of the cylinder.  
         [0040]     It is yet another object of the present invention to make a desired device contained in the cabinet of the present invention adaptable to not only various shapes and dimension of additional devices but also the system configurations and conditions thereof and to prevent abrupt or great decrease in efficiency of forced air cooling of an electronic device contained in the cylinder.  
         [0041]     It is yet another object of the present invention to maintain high efficiency of the aforesaid forced air cooling without setting performance of a fan provided in each of the additional devices to an unnecessarily high level, or consuming large power for driving the fans.  
         [0042]     It is yet another object of the present invention to improve efficiency and availability of the cabinet and additional device with regard to the maintenance and operation thereof and to enhance total reliability thereof.  
         [0043]     It is yet another object of the present invention to increase, compared with conventional examples, upper limit values of the volumes of an electronic device contained in a cylinder and of an additional device attached to the aperture of the cylinder, or to decrease the size of the cabinet of the present invention and change the shape thereof freely.  
         [0044]     It is yet another object of the present invention to suppress or reduce electro magnetic interference caused by an electronic device even while an additional device is not inserted into the aperture of the cylinder.  
         [0045]     It is yet another object of the present invention to closely fit, with a strong pressure, the cabinet of an additional device into the aperture of a cabinet containing an electronic device with low cost and without structural complication, compared with a case where stiffness of the aperture of the cabinet containing the electronic device is not reinforced with having a folded edge.  
         [0046]     It is yet another object of the present invention to make it possible to not only replace power sources according to difference or increase/decrease in load of electronic devices but also standardize the structure of the power sources and electronic devices.  
         [0047]     It is yet another object of the present invention to perform air exhaustion or suction in the same direction or in an integrated manner with easiness during a process of forced air cooling of an electronic device.  
         [0048]     The present invention is applied as follows.  
         [0049]     A first cabinet according to the present invention has a conductive cylinder containing an electronic device. The cylinder has an aperture with a folded edge. Further, an additional device operating in parallel with the aforesaid electronic device is fitted into this aperture. A reinforcing member is supported with a portion of an inner wall of the cylinder and disposed on a boundary between two areas in the cylinder where the electronic device and the additional device are placed, respectively. The portion of the inner wall is more inside than a folded edge of the aperture.  
         [0050]     Therefore, folding the edge of the aperture of the cylinder can increase the stiffness of the aperture, and the provision of the reinforcing member also heightens the physical strength of the inner wall of the cylinder including the vicinity of the folded portion of the aperture, even though the aperture is given pressure in an outward direction from the cabinet of the inserted additional device. Consequently, It is possible to stably and securely attach/detach the additional device to/from the cylinder even if the thickness or hardness of the cylinder is small because the cabinet of the additional device can have a resisting force against bending force physically acting on or around the aperture of the cylinder.  
         [0051]     A second cabinet according to the present invention includes a conductive cylinder containing an electronic device. The cylinder has an aperture with a folded edge. Further, a plurality of additional devices operating in parallel with the aforesaid electronic device are fitted into the aperture with a folded edge. A reinforcing member is supported with a portion of an inner wall of this cylinder, and disposed on a boundary between two areas in the cylinder where the electronic device and all of the plurality of additional devices are placed, respectively. The portion of the inner wall is more inside than the folded edge of the aperture.  
         [0052]     Therefore, folding the edge of the aperture of the cylinder can increase the stiffness of the aperture, and the provision of the reinforcing member also heightens the physical strength of the inner wall of the cylinder including the vicinity of the folded portion of the aperture, even though the aperture is given pressure in an outward direction from the cabinet of the inserted additional devices. Consequently, It is possible to stably and securely attach/detach the additional devices to/from the cylinder even if the thickness or hardness of the cylinder is small because the cabinet of the additional device can have a resisting force against bending force physically acting on or around the aperture of the cylinder.  
         [0053]     A third cabinet according to the present invention includes a partitioning member which partitions the aforesaid aperture into areas into which the additional devices are fitted and is a bypass path for forced air cooling in these areas. Each of the plurality of additional devices has a fan used for the forced air cooling of the electronic device.  
         [0054]     In other words, the partitioning member helps normally operating fans, of the fans provided in the aforesaid plural devices, distribute load of the forced air cooling even though the aperture of the cylinder is divided into a plurality of apertures in conformity with the shapes and dimensions of the devices inserted into the aperture. This makes it possible to allow a desired device contained in the cabinet of the present invention to be adaptable to not only various shapes and dimensions of additional devices but also the system configurations and conditions thereof and to prevent abrupt or great decrease in efficiency of forced air cooling of an electronic device contained in the cylinder.  
         [0055]     A fourth cabinet according to the present invention includes a control unit which increases/decreases rotation speed of the fans provided in the plurality of additional devices, according to the number of the fans or operational conditions of the fans, to maintain efficiency of the forced air cooling within a prescribed range. In other words, fans provided in additionally devices actually mounted on the cabinet and normally operating can compensate all or part of loads of the forced air cooling if some of the plurality of additional devices are not actually mounted on the cabinet or they are mounted but the fans therein do not normally operate. Consequently, it is possible to maintain high efficiency of the aforesaid forced air cooling without setting performance of a fan provided in each of the additional devices to an unnecessarily high level, or consuming large power for driving the fans.  
         [0056]     In a fifth cabinet according to the present invention, the cylinder includes a covering member having an edge that is all or part of the edge of the aforesaid aperture, and used for opening/closing the above-mentioned two areas, and detachably supporting the reinforcing member. Therefore, with the aforesaid covering member detached, it is more facilitated to attach/detach, adjust, inspect and so on the electronic device and additional devices than with no provision of such a covering member. Consequently, it is able to improve the efficiency and availability of the cabinet of the invention with regard to maintenance and operation and to enhance total reliability thereof.  
         [0057]     In a sixth cabinet according to the present invention, the reinforcing member adjacent to the covering member has a specific edge which is shaped to be in parallel with the covering member. The covering member has a member to pinch the specific edge. Therefore, without any large member attached inside the cylinder it is able to give to the aperture stiffness and physical strength enough to securely, stably have the additional device attached thereto with low cost. Consequently, it is possible to increase, compared with conventional examples, upper limit values of the volumes of the electronic device contained in the cylinder and of the additional device attached to the aperture of the cylinder, or to decrease the size of the cabinet of the present invention and change the shape thereof freely.  
         [0058]     In a seventh cabinet according to the present invention, the reinforcing member has an opening for heat release from the electronic device to the aforesaid aperture and for suppression of radiation of electro magnetic interference generated in the electronic device to the aperture. The reinforcing member acts as a shielding member to suppress the radiation of the electro magnetic interference generated in the electronic device without obstructing heat release from the electronic device. This makes it possible to suppress or reduce the electro magnetic interference by the electronic device even while the additional device is not inserted into the aperture of the cylinder.  
         [0059]     A first additional device according to the present invention includes a first conductive cabinet containing an electronic device. The first conductive cabinet is provided with a second conductive cabinet having a first aperture to be fitted by inserting into an aperture with a folded edge. The second conductive cabinet further contains a circuit that operates in parallel with the electronic device. The first aperture of the conductive cabinet containing the circuit has a shape and dimension and made of materials to be fitted into the aforesaid aperture of the conductive cabinet with the folded edge containing the electronic device. Consequently, given a strong pressure, the above-mentioned aperture insertion is tightly made with low cost, without structural complication, compared with a case where stiffness of the aperture of the cabinet containing the electronic device is not reinforced with having a folded edge.  
         [0060]     A second additional device according to the present invention has a circuit to supply power to the electronic device. In this case the power source to supply power to the electronic device is contained as an additional device in another cabinet that is to be fitted into the aperture of the first cabinet containing the electronic device. This makes it possible to replace the power source according to difference or increase/decrease in load among the electronic devices as well as to standardize the structure of the power source and electronic device, compared with a case where such a power source is integrally incorporated in the electronic device.  
         [0061]     A third additional device according to the present invention uses a fan for forced air cooling of the electronic device via the first aperture. In other words the additional device contained in another cabinet fitted into the aperture of the cabinet containing the electronic device includes the fan used for the forced air cooling of the electronic device in addition to the circuit for supplying power to the electronic device. This realizes reduction in the types and number of the additional devices to be contained in another cabinet, and also realizes exhaustion or suction in the same direction, or integration of the exhaustion and suction during the process of the aforesaid forced air cooling the directions.  
         [0062]     In a fourth additional device according to the present invention, the second conductive cabinet of the above-described third additional device has a second aperture to serve as a bypass path for ventilation in the process of the forced air cooling which is provided between the additional device and another additional device disposed adjacent to the additional device. When another additional device is disposed adjacent to the additional device according to the present invention, and one of the fans provided in these additional devices is in fault or in halt, the other fan in normal operation can compensate all or part of loads of the forced air cooling via the second aperture. This enables a desired device contained in the cabinet of the invention to be adaptable to not only various shapes and dimensions of the additional devices but also various system configurations and operational conditions thereof. Also, this results in preventing abrupt or great decrease in efficiency of the aforesaid forced air cooling.  
         [0063]     A fifth additional device according to the present invention additionally includes a control unit which increases/decreases the rotation speed of fans according to operational conditions of the fans provided in a specific additional device of the present invention and in another additional device that is fitted into the aperture of the first cabinet, to maintain efficiency of the forced air cooling within a prescribed range. Accordingly, the fans provided in actually mounted additional devices and normally operating are able to compensate all or part of loads of the forced air cooling if some of the additional devices are not mounted or the fans in the mounted devices do not normally operate. Consequently, it is possible to maintain high efficiency of the forced air cooling without setting the performance of the fans to an unnecessarily high level, or consuming large power for driving these fans.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0064]     The nature, principle, and utility of the invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings in which like parts are designated by identical reference numbers, in which:  
         [0065]      FIG. 1  is an assembly view of first to third embodiments of the present invention;  
         [0066]      FIG. 2  is a cross sectional view of an essential part of the first to third embodiments of the present invention;  
         [0067]      FIG. 3 ( a ) and  FIG. 3 ( b ) show the detailed inner structure of the first to third embodiments of the present invention;  
         [0068]      FIG. 4 ( a ) and  FIG. 4 ( b ) show the process of opening/closing a cabinet according to the first to third embodiments of the present invention;  
         [0069]      FIG. 5 ( a ) and  FIG. 5 ( b ) show the process of mounting a power supply unit in the first to third embodiments of the present invention;  
         [0070]      FIG. 6 ( a ) and  FIG. 6 ( b ) are charts to explain the operation of the first and second embodiments of the present invention  
         [0071]      FIG. 7  is a diagram showing the detailed structure of the third embodiment of the present invention;  
         [0072]      FIG. 8  is a flowchart of the operation of the third embodiment of the present invention;  
         [0073]      FIG. 9  is a table to explain the operation of the third embodiment of the present invention;  
         [0074]      FIG. 10 ( a ) and  FIG. 10 ( b ) show a structural example (1) of a conventional cabinet;  
         [0075]      FIG. 11  shows a structural example (2) of the conventional cabinet; and  
         [0076]      FIG. 12  shows a problem of the conventional example.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0077]     Hereinafter, embodiments of the present invention will be explained in detail based on the drawings.  
         [0078]      FIG. 1  is an assembly view of a first to a third embodiment of the present invention.  
         [0079]      FIG. 2  is a cross sectional view of an essential part of the first to third embodiments of the present invention.  
         [0080]      FIG. 3 ( a ) and  FIG. 3 ( b ) are views showing the state in which a top cover is detached from a cabinet according to the first to third embodiments of the present invention.  
         [0081]      FIG. 4 ( a ) and  FIG. 4 ( b ) are views showing the process of opening/closing the cabinet according to the first to third embodiments of the present invention.  
         [0082]      FIG. 5 ( a ) and  FIG. 5 ( b ) are views showing the process of mounting a power supply unit in the first to third embodiments of the present invention.  
         [0083]     As shown in  FIG. 1  to  FIG. 5 ( b ), the cabinet according to the first to third embodiments of the present invention is composed of a base  11 , a front cover  12 , and a top cover  13 , and the basic structures of the base  11 , front cover  12 , and top cover  13  are as follows.  
         [0084]     The base  11  is composed of the following elements: 
        a bottom plate  111  BP being a rectangular metal plate having screw holes used for fixing the aforesaid printed board  51 , and two rectangular cutout portions  11 N-R,  11 N-L, in one of shorter sides thereof, arranged symmetrical with respect to the center of the shorter side, and the metal plate being used for grounding an electronic circuit disposed on the printed board  51 ;     a pair of side frames  11 SF-R,  11 SF-L being metal plates in a substantially U shape and joined to two longer sides of the aforesaid bottom plate  111  BP respectively;     partitioning members  11 P-R,  11 P-C,  11 P-L being made of metal or metal pieces in a rectangular parallelepiped shape having later-described first slits in lattice, and having the same length to set an interval between themselves and the printed board  51  to a predetermined value, and protrudingly provided in parallel with the longer sides of the bottom plate  11 BP with their ends on three protruding portions, which are other than the aforesaid cutout portions  11 N-R,  11 N-L, on the aforesaid shorter side of the bottom plate  11 BP; and     a reinforcing frame  11 ST: joined to the bottom plate  11 BP (( 1 ) in  FIG. 2 ) with its one end; being a molded metal plate in a substantially L shape (( 2 ) in  FIG. 2 ) including all of one ends and a predetermined length of top portions of the partitioning plates  11 P-R,  11 P-C,  11 P-L; fixed to the partitioning members  11 P-R,  11 P-C,  11 P-L by screwing or the like; and having later-described second slits in lattice.        
 
         [0089]     Note that it will be hereinafter assumed that later-described connectors  11 J-R,  11 J-L are disposed on the printed board  51  in addition to the aforesaid circuit.  
         [0090]     The front cover  12  has the following structure.  
         [0091]     (1) It is formed as a molded conductive member with a shape and dimension to suppress radiation of electro magnetic interference caused by components on the printed board  51  used for man machine interface via the front cover  12 .  
         [0092]     (2) It has a groove fitted to one shorter side of the bottom plate  11 BP and to edges of the side frames  11 SF-R,  11 SF-L, more specifically, edges continuing from or close to this shorter side, and it also has a later-described suction port.  
         [0093]     The top cover  13  is formed by machining a metal plate as follows.  
         [0094]     (1) A pair of sidewalls  13 SW-R,  13 SW-L are formed, which are fixable to the side frames  11 SF-R,  11 SF-L by screws and slidable along external walls of the side frames  11 SF-R,  11 SF-L.  
         [0095]     (2) Bent portions  13 B-R,  13 B-L are formed that are abuttable on and screw-fixable to one ends of the partitioning members  11 P-R,  11 P-L, and coupled to the aforesaid sidewalls  13 SW-R,  13 SW-L respectively.  
         [0096]     (3) Cutout portions  13 N-R,  13 N-L and a bent portion  13 B-C are formed, positioning at the boundary between the cutout portions  13 N-R,  13 N-L, the cutout portions being abuttable on and screw-fixable to one end of the partitioning member  11 P-C and formed by extending the aforesaid cutout portions  11 N-R,  11 N-L toward a top portion of the top cover  13 .  
         [0097]     (4) An edge  13 E is formed that has a cross section in a substantially U shape and is fittable to the front cover  12  together with the bottom plate  11 BP and the side frames  11 SF-R,  11 SF-L.  
         [0098]     Further, detachable power supply units  14 -R,  14 -L are mounted in the aforesaid pair of cutout portions  11 N-R,  13 N-R and pair of cutout potions  11 N-L,  13 N-L, and the power supply units  14 -R,  14 -L are composed of the following elements. Note that what are common to the power supply units  14 -R,  14 -L are hereinafter denoted by reference numerals of corresponding elements with a suffix ‘b’ that can represent both the suffixes R and L.  
         [0099]     (1) A power supply cover  14 C-b: formed of a metal plate which is bent in a U shape and whose edge is molded in a shape to be fitted into the cutout portions  11 N-b,  13 N-b; used for grounding a later-described power supply circuit; and having a fan  14 F-b, a radiation fin  14 R-b, a breaker  14 CB-b, and so on attached to a top portion thereof.  
         [0100]     (2) a printed board  14 PCB-b: fixed to the power supply cover  14 C-b; and on which disposed are a power supply circuit including the aforesaid radiation fin  14 R-b and the breaker  14 CB-b, a control circuit for driving the aforesaid fan  14 F-b, and a connector  14 P-b used for connection to physical lines necessary for power supply to the circuit disposed on the printed board  51  and for association with this circuit (both are achieved via the aforesaid connector  11 J-b).  
         [0101]     Note that an exhaust port formed in the top portion of the power supply cover  14 C-b and used for exhaust via the fan  14 F-b is constituted as a set of slits that satisfy the same conditions as those of later-described first slits, or covered with a net-shaped member having such slits that are formed in advance.  
       First Embodiment  
       [0102]      FIG. 6 ( a ) and  FIG. 6 ( b ) are charts to explain the operation of the first and second embodiments of the present invention.  
         [0103]     Hereinafter, the first embodiment of the present invention will be explained with reference to  FIG. 1  to  FIG. 6 ( b ). Edges of the bottom plate  11 BP and the top cover  13  in which the cutout portions  11 N-b,  13 N-b are formed respectively are folded with predetermined margins as shown in (a) and (b) in  FIG. 2 . Hereinafter, these edges will be referred to as folded portions.  
         [0104]     Further, as shown in  FIG. 2 , a support metal fitting  13 P is attached to an inner wall of the top cover  13  which is distant from the folded portion with a predetermined length. The support metal fitting  13 P is a metal piece with a shape and dimension to insert the reinforcing frame  11 ST thereto and support the edge.  
         [0105]     The power supply cover  14 C-b is formed in a shape and dimension and of a material so as to ensure elasticity and stiffness to attach/detach the power supply unit  14 - b  from/to the edge thereof (hereinafter, referred to as an inserted portion) which is inserted into a space between the aforesaid folded portions of the bottom plate  111  BP and the top cover  13 .  
         [0106]     An assembly process of the cabinet according to this embodiment is as follows:  
         [0107]     (1) As shown in  FIG. 3 ( a ) and  FIG. 3 ( b ), the printed board  51  (a desired electronic circuit whose basic operation check has been finished is incorporated thereon) is mounted on the bottom plate  11 BP, and the front cover  12  is fitted to the bottom plate  11 BP by insertion.  
         [0108]     (2) The inner wall of the top cover  13  slides along the external walls of the side frames  11 SF-R,  11 SF-L and the top portion of the reinforcing frame  11 ST (the partitioning members  11 P-R,  11 P-C,  11 P-L) as shown in  FIG. 4 ( a ) and  FIG. 4 ( b ). The top cover  13  (which corresponds to the specific edge of the reinforcing member described in a sixth cabinet according to the present invention and the cabin in claim  7 ) is fitted with the front cover  12  as shown in  FIG. 5 ( a ) and  FIG. 5 ( b ), and the top cover  13  has the support metal fitting  13 P on its inner wall to pinch the edge of the reinforcing frame  11 ST between the inner wall and the support metal fitting  13   p  shown in ( 3 ) in  FIG. 2 .  
         [0109]     (3) The top cover  13  (including the aforesaid bent portions  13 B-R,  13 B-C,  13 B-L) is screw-fixed to the side frames  11 SF-R,  11 SF-L and the partitioning members  11 P-R,  11 P-C,  11 P-L.  
         [0110]     (4) The printed board  14 PCB-b is inserted into an aperture as the cutout portion  11 N-b or  13 N-b between the partitioning members  11 P-R,  11 P-C (or  11 P-C,  11 P-L), thereby fitting the aforesaid connector  14 P-b with the connector  11 J-b (mounted on the printed board  51 ) and inserting a portion of the power supply cover  14 C-b into a space between the aforesaid folded portions of the bottom plate  111  BP and the top cover  13  (( 4 ) in  FIG. 2 ).  
         [0111]     In the cabinet thus assembled, the folded portions of the bottom plate  11 BP and the top cover  13  is given a pressure in an outward direction of the cabinet by the inserted portion of the power supply covers  14 C-b (( 5 ) in  FIG. 2 ). However, the folded portions are folded in a the above-described manner so that when they can have strength large enough to resist a physically acting bending force thereon due to the inserted power supply cover  14 C-b, even when the bottom plate  11 BP and the top cover  13  are made of thin metal plates.  
         [0112]     Further, in the vicinity of the folded portion of the top cover  13 , a portion of the reinforcing frame  11 ST is inserted into an area sandwiched by the inner wall of the top cover  13  and the support metal fitting  13 P. The reinforcing frame  11 ST is fixed to the bottom plate  11 BP, the top portions of the partitioning plates  11 P-R,  11 P-C,  11 P-L attached to the bottom plate  11 BP, so that it is possible to prevent or sufficiently reduce the bending due to the aforesaid pressure with high reliability even when the bottom plate  11 BP and the top cover  13  are made of thin metal plates.  
         [0113]     Further, the partitioning members  11 P-R,  11 P-C,  11 P-L includes the first slits with a pitch having such a shape and dimension as to suppress radiation of: electro magnetic interference to the power supply unit  14 - b , the electromagnetic magnetic interference (hereinafter, referred to as high-frequency electromagnetic interference) generated in the electronic circuit disposed on the printed board  51  and having a higher frequency band that is higher than that of electro magnetic interference (hereinafter, referred to as low-frequency electro magnetic interference) generated in the power supply circuit provided in the power supply unit  14 - b ; and contrariwise, the low-frequency electro magnetic interference to the printed board  51  ( FIG. 6 ( a )).  
         [0114]     The reinforcing frame  11 ST has second slits with such a shape and dimension and at a pitch as to satisfy both of the following conditions.  
         [0115]     (1) To suppress the radiation of both of the high-frequency electro magnetic interference to the power supply unit  14   b  and of the low-frequency electro magnetic interference to the printed board  51  ( FIG. 6 ( a )).  
         [0116]     (2) Not to obstruct the airflow through ventilation paths (from the suction port formed in the front cover  12  to the fans  14 F-R,  14 F-L) for the aforesaid forced air cooling of the electronic circuit, and the degree of obstruction being allowably low.  
         [0117]     The inserted portion of the power supply cover  14 C-b is in physically and electrically close contact with the folded portions of the top cover  13  since the physical strength of the folded portions of the top cover  13  is secured by the folding as described above and a resisting force against the bending of the top cover  13  is ensured by engaging the support metal fitting  13 P with the edge of the reinforcing frame  11 ST.  
         [0118]     Therefore, it is possible to reliably suppress the radiation of the low-frequency electro magnetic interference generated in the power supply cover  14 C-b to the exterior from spaces which are surrounded by the bottom plate  11 BP, the reinforcing frame  11 ST, the partitioning members  11 P-R,  11 P-C ( 11 P-C,  11 P-L), and in which the power supply units  14 - b  are to be mounted, respectively.  
         [0119]     Thus, this embodiment realizes enhancement in the mechanical strength and the stable efficiency of the forced air cooling as well as the shielding of the internally generated electro magnetic interference without greatly narrowing the inner space, even though the bottom plate  11 BP, the reinforcing frame  11 ST, the top cover  13 , and the power supply covers  14 C-b are formed of thin metal plates.  
         [0120]     Therefore, an electronic device to which this embodiment is applied is able to reduce its size and weight with low cost without any deterioration in performance, and it also can have considerably higher density assembly than that in conventional examples with relaxation of restrictions on thermal design.  
       Second Embodiment  
       [0121]     Hereinafter, the second embodiment of the present invention will be explained with reference to  FIG. 1  to  FIG. 6 ( b ).  
         [0122]     The characteristics of the second embodiment are the shape, dimension, and pitch of the first slits formed in the partitioning member  11 P-C.  
         [0123]     The partitioning member  11 P-C has first slits having a shape and dimension, and with a pitch to suppress, as described above, the radiation of high-frequency electro magnetic interference to the power supply unit  14 - b  and of low-frequency electro magnetic interference to the printed board  51 , and in addition, to form bypass paths coupled to each other with a desired degree of tightness between two ventilation paths from the suction port formed in the front cover  12  to the fans  14 F-R,  14 F-L.  
         [0124]     Incidentally, the first slits in the partitioning members  11 P-R,  11 P-L may be similarly formed with such shape and dimension and at such a pitch as described above.  
         [0125]     In this embodiment, paths for bi-directional ventilation are also formed between the first and second ventilation paths formed respectively by the fans  14 F-R,  14 F-L provided in the respective two power supply units  14 -R,  14 -L. For example, in any of the following conditions, these ventilation paths are substantially integrated by the fan  14 F-L in the power supply unit  14 -L via the first slits formed in the partitioning member  11 -C, as shown in  FIG. 6 ( b ).  
         [0126]     (1) Between the power supply units  14 -R,  14 -L, to operate based on the active redundancy system, only the power supply unit  14 -L is mounted and is in normal operation.  
         [0127]     (2) Between the power supply units  14 -R,  14 -L to operate based on active redundancy the fan  14 F-R mounted in the power supply unit  14 -R is in fault (stopped), and only the power supply unit  14 -L is mounted, and in normal operation.  
         [0128]     Consequently, according to this embodiment, a fan provided in the power supply unit is able to stably continue forced air cooling with desired efficiency even while the operation relies only on a single power supply unit (including a period when the power supply unit  14 -R or  14 -L is given maintenance or replaced).  
       Third Embodiment  
       [0129]      FIG. 7  is a diagram showing the detailed structure of the third embodiment of the present invention.  
         [0130]     In the drawing, an office power source is connected to an input of a power supply circuit  14 PS-b provided in the power supply unit  14 - b  (disposed on the printed board  14 PCB-b) via a not-shown terminal board (assumed here to be disposed on the power supply cover  14 C-b), and an output of the power supply circuit  14 PS-b is connected to the following terminals provided in the fan  14 F-b and to a corresponding pin of the connector  14 P-b.  
         [0131]     (1) A terminal used for supplying power (power for fan driving) to the fan  14 F-b.  
         [0132]     (2) A terminal used for supplying a control signal indicating one of two different rotation speeds to be set for the fan  14 F-b (assumed here for simplicity to indicate that the rotation speed is to be set higher when its logical value is ‘1’ and indicate that the rotation speed is to be set low when its logical value is ‘0’).  
         [0133]     (3) A terminal used for supplying a warning signal indicating whether the fan  14 F-b is in normal operation.  
         [0134]     (4) A terminal used for applying a predetermined voltage (hereinafter, a signal indicating one of two different states, namely, whether such a voltage is applied or not, is referred to as a mount signal) to an exterior of the fan  14 F-b (power supply unit  14 - b ) only when the fan  14 F-b (power supply unit  14 - b ) is mounted.  
         [0135]     On the printed board  51  disposed are the aforesaid electronic circuit to which power is supplied in parallel by the power supply units  14 -R,  14 -L via the aforesaid connectors  11 J-R,  11 J-L, and a control unit  51 CNT supplied with power along with the electronic circuit and exchanging the aforesaid control signal, warning signal, and mount signal with the fans  14 F-R,  14 F-L via the connectors  11 J-R,  11 J-L.  
         [0136]     Note that, hereinafter, the control signal, the warning signal, and the mount signal supplied via a connector  14 P-R and the connector  11 J-R will be referred to as a control signal R, a warning signal R, and a mount signal R respectively, and the control signal, the warning signal, and the mount signal supplied via a connector  14 P-L and the connector  11 J-L will be referred to as a control signal L, a warning signal L, and a mount signal L respectively.  
         [0137]      FIG. 8  is a flowchart of the operation of the third embodiment of the present invention.  
         [0138]      FIG. 9  is a table to explain the operation of the third embodiment of the present invention.  
         [0139]     Hereinafter, the operation of this embodiment will be explained with reference to  FIG. 7  to  FIG. 9  as well as to  FIG. 1  and  FIG. 2 .  
         [0140]     The control unit  51 CNT monitors the aforesaid warning signal R, mount signal R, warning signal L, and mount signal L at a predetermined frequency and judges whether or not power is normally supplied by each of the power supply units  14 -R,  14 -L. The control unit  51 CNT further performs the following operations according to the results of such monitoring and judgment.  
         [0000]     (1) Determination of the System Configuration of the Power Supply Units  
         [0141]     To judge whether or not voltages of the mount signal R, and the mount signal L are equal to the aforesaid predetermined voltage (( 1 ) in  FIG. 8 ): 
        If the results of the judgments are YES, to determine that the power supply units  14 -R,  14 -L are operating based on active redundancy (hereinafter, referred to as duplex operation) (( 2 ) in  FIG. 8 ); and     If, on the other hand, one of the judgment results is NO, to discriminate the corresponding power supply unit (hereinafter, referred to as an unmounted power supply unit), and to determine that the electronic circuit operates with one of the power supply units  14 -R,  14 -L not mounted (hereinafter, referred to as single system operation) (( 3 ) in  FIG. 8 ). 
 
 (2) Judgment on Whether or Not the Power Supply Units are in Normal Operation 
       
 
         [0144]     To determine whether the power supply units  14 -R,  14 -L are normally supplying power (hereinafter, referred to as normal power supply units) based on the difference between the voltages of power supply lines connected to outputs, and proper values of the voltages (( 4 ) and ( 5 ) in  FIG. 8 ).  
         [0145]     (3) Judgment on whether or not the fans are in normal operation: 
        To judge whether or not each of the fans  14 F-R,  14 F-L is in normal operation, based on the logical values of the warning signal R and the warning signal L; and     To discriminate the fan(s) with a negative judgment result (hereinafter, referred to as faulty fans) from the fans  14 F-R,  14 F-L (( 6 ) and ( 7 ) in  FIG. 8 ).        
 
         [0148]     (4) In the single system operation, to set the logical value of the control signal to ‘1’ (indicating that the rotation speed is set high), the control signal being to be given only to either of the fans  14 F-R,  14 F-L which is provided in the one determined as normal and is not the faulty fan.  
         [0149]     (5) In the duplex operation, to determine in what state the power supply units  14 -R,  14 -L are at this moment (hereinafter, referred to as a current state) from the following states (( 9 ) in  FIG. 8 ): 
        A first state in which both of the power supply units  14 -R,  14 -L are normal and neither of the fans  14 F-R,  14 F-L respectively provided therein are the faulty fans (( 3 ) in  FIG. 9 );     A second state in which one of the power supply units  14 -R,  14 -L is not normal and neither of the fans  14 F-R,  14 F-L respectively provided therein are the faulty fans (( 4 ) and ( 5 ) in  FIG. 9 );     A third state in which one of the fans  14 F-R,  14 F-L is the faulty fan ((6) and (7) in  FIG. 9 ).        
 
         [0153]     (6) To supply or stop power to each of the fans  14 F-R,  14 F-L according to the determined current state, and to set the logical value of the control signal (( 10 ) in  FIG. 8 ): 
        If the current state is the first state, to supply power to both of the fans  14 F-R,  14 F-L in parallel and to set the logical value of the control signal to ‘0’ (indicating that the rotation speed is set low) and give the set signal to the fans  14 F-R,  14 F-L;     If the current state is the second state, to supply power to both of the fans  14 F-R,  14 F-L by the normal power supply unit, and to set the logical value of the control signal to ‘0’ (indicating that the rotation speed is set low) and give the set signal to the fans  14 F-R,  14 F-L; and     If the current state is the third state, to supply power only to one of the fans  14 F-R,  14 F-L, being not the faulty fan (hereinafter, referred to as a normal fan) and to set the logical value of the control signal to ‘1’ (indicating that the rotation speed is set high) and to give the set signal to this normal fan.        
 
         [0157]     That is, one of the fans  14 F-R,  14 F-L in normal operation is continuously given power by the normal power supply unit(s) (both or one of the fans  14 F-R,  14 F-L), and is set to have a high operation speed only while the other fan is in fault in the duplex operation or during the single system operation. Thus, according to this embodiment, increasing the rotation speed of the normal fan can compensate a decrease in the efficiency of the forced air cooling due to the faulty fan.  
         [0158]     Moreover, compared with the above-described second embodiment, according to this embodiment it is possible to maintain high efficiency of the forced air cooling of the electronic circuit disposed on the printed board  51 , or relax restrictions on the thermal design and component arrangement of the electronic circuit. It is also possible to enhance total reliability of the electronic circuit without excessive increase in power consumption or the provision of a large fan.  
         [0159]     Note that in this embodiment, the control unit  51 CNT is mounted on the printed board  51  together with the aforesaid electronic circuit. However, the present invention is not limited to such structure, and, for example, the control unit  51 CNT may be disposed on a printed board different from the printed board  51  and supported by the reinforcing frame  11 ST or the like, or two control units are separately disposed on the printed board  14 PCB-R,  14 PCB-L provided in the power supply units  14 -R,  14 R-L respectively.  
         [0160]     Further, in each of the above-described embodiments, the fans  14 F-R,  14 F-L are provided in the power supply units  14 -R,  14 -L respectively. However, the present invention is not limited thereto. For example, the power supply units  14 -R,  14 -L may be structured without the respective fans  14 F-R,  14 F-L, and different fans are attached onto the bottom plate  111  BP instead together with any one of the partitioning members  11 P-R,  11 P-C,  11 P-L which may not have the aforesaid first slits formed therein.  
         [0161]     Further, in each of the above-described embodiments, the reinforcing frame  11 ST is inserted between the inner wall of the top cover  13  and the support metal fitting  13 P, so as to secure the strength of the top cover  13  and electrically connect the reinforcing frame  11 ST, at low impedance, to the top cover  13  which is necessary for shielding the high-frequency electro magnetic interference.  
         [0162]     However, the present invention is not limited to the above structure and, for example, it may be structured that in place of the support metal fitting  13 P, a conductive pin with the largest diameter at its top portion is protrudingly provided on the inner wall of the top cover  13 , and the reinforcing frame  11 ST may have a notch to be engaged with the side wall and the top portion of this pin.  
         [0163]     Further, in each of the above-described embodiments, the partitioning member  11 P-C may not include the first slits if, for example, the electronic circuit only operates in the aforesaid duplex operation, or the first slots may be large enough to allow the low-frequency electro magnetic interference to propagate to/from the power supply units  14 -R,  14 -L via the partitioning member  11 P-C.  
         [0164]     Further, in each of the above-described embodiments, in place of or in addition to the first slits formed in the partitioning member  11 P-C, for example, slits similar to the first slits may be formed in corresponding side faces of the power supply units  14 -R,  14 -L.  
         [0165]     Moreover, the present invention is not limited to the case where the power supply units  14 -R,  14 -L operate based on active redundancy in principle, and is similarly applicable to a case where the number of power supply units mounted similarly to the power supply units  14 -R,  14 -L is one, or to a case where a plurality of power supply units are provided and operate based on a system other than the active redundancy system (for example, standby redundancy or N+1 stand-by system).  
         [0166]     Further, in each of the above-described embodiments, the top cover  13  is tightly fixed onto the base  11  by screwing. However, the present invention is not limited to such structure, and for example, the top cover  13  and the base  11  may be constituted as an integrated cylinder as long as the printed board  51  can be contained in a predetermined location of an inner portion (a hollow portion) thereof.  
         [0167]     Moreover, in each of the above-described embodiments, the power supply units  14 -R,  14 -L are mounted at a center portion of one face of the box-shaped cabinet with a predetermined interval. However, the present invention is not limited to such structure, and such power supply units are mounted at any one of the corners of the aforesaid box-shaped cabinet.  
         [0168]     Further, in each of the above-described embodiments, the present invention is applied to the cabinet in a rectangular parallelepiped shape containing the printed board  51 . However, the present invention is not limited thereto, and applicable to a cabinet in any shape and dimension.  
         [0169]     The invention is not limited to the above embodiments and various modifications may be made without departing from the spirit and scope of the invention. Any improvement may be made in part or all of the components.