Abstract:
A card-mounting rack for electronic part-mounting cards is disclosed by which a housing of a rack or the like produced in accordance with standard specifications can be used to mount a plurality of large cards in high density therein to achieve overall densification and miniaturization of a system such as a computer system. Cooling fans are provided on a front and rear faces of a housing of a rack. A mother board is horizontally placed at the center of the inside of the housing. A plurality of cards are mounted perpendicularly on top and bottom faces of the mother board using gondolas and driving mechanisms having a function for moving the cards upwardly or downwardly through a plurality of connector provided on the top and bottom faces of the motherboard. Further, spacers for stabilizing the cards are inserted on rear faces of the cards.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a card-mounting rack for electronic part-mounting cards for mounting parts of the card type such as electronic circuit boards for construction of a computer system or the like in high density into a housing. 
   2. Description of the Related Art 
   Conventionally, when a plurality of parts of the card type (a part of the type mentioned is hereinafter referred to merely as card) such as electronic circuit boards on which electronic parts are mounted are accommodated into the inside of a housing of a standardized rack such as a 19-inch rack or the like to construct a system such as a computer system, such a conventional method as disclosed in Japanese Patent Laid-Open No. 10-178289 and U.S. Pat. No. 5,868,585 is used. According to the method, a mother board is mounted in the inside of a housing such that it extends in parallel to the side faces of the housing but perpendicularly to the bottom face of the housing. Further, a plurality of cards are mounted only on one face or side of the mother board such that they extend in parallel to the bottom face of the housing. In such a mounting method as just described, the cards are connected to the mother board only in a limited one direction. Therefore, the length of a cable necessary for connection between the cards increases as the number of cards to be mounted onto one mother board increases. Such increase of the length of a connection cable between cards as just described makes a cause of signal delay, noise increase and so forth. As a result, it becomes a factor that the performance of the entire system is degraded. 
   In order to suppress such degradation of the system performance arising from increase of the length of a connection cable between cards as just described, the following method may be used. In particular, in order to reduce the length of a connection cable between cards, a mother board is placed at the center of a housing such that it extends in parallel to the side faces of the housing but perpendicularly to the bottom face of the housing and a plurality of cards are mounted on both faces of the mother board provided at the center of the housing such that they extend in parallel to the bottom face of the housing. However, according to such a mounting method as just described, the size of cards is limited by the width of the housing, and a card having a size generally used for the 19-inch standard rack cannot be mounted. 
   Also another method may be used wherein, in order to prevent occurrence of such a limitation to the size of the cards as just described, a mother board is placed at the center of a housing such that it extends perpendicularly to the side faces and the bottom face of the housing and a plurality of cards are mounted on both faces of the mother board provided at the center of the housing such that they extend in parallel to the bottom face of the housing. 
   However, in such mounting methods as described above, an air flow for cooling generated in the inside of the housing of a rack or the like by sucking air from the front face of the housing and exhausting air to the rear face of the housing is intercepted by the mother board provided at the center of the housing. This gives rise to a problem that the cooling system does not sufficiently function. A method wherein air is sucked from a lower portion of a housing and exhausted from an upper portion of the housing may be used as alternate measures without using the general cooling system of the front face air sucking and rear face air exhausting type described above. However, in the cooling system of the bottom face air sucking and top face air exhausting type, it is necessary to assure a space for the location of cooling fans above and below cards to be mounted. Therefore, when a system such as a computer system is constructed, the height of a housing of a rack or the like becomes greater than that of a housing of a standard rack or the like and the mounting density of electronic parts other than a mother board and cards to be mounted in the housing decreases. As a result, a problem occurs that improvement of the performance of the entire system by high-density mounting and miniaturization is obstructed. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide a card-mounting rack for electronic part-mounting cards wherein a housing of a rack or the like produced in accordance with standard specifications can be used to mount a plurality of large cards in high density therein to achieve overall densification and miniaturization of a system such as a computer system. 
   In order to attain the object described above, according to the present invention, there is provided a card-mounting rack for electronic part-mounting cards for mounting a plurality of cards each having an electronic part and a connector mounted thereon, comprising a mother board disposed horizontally, a plurality of platforms, a driving mechanism provided for each of the platforms for moving the platform upwardly or downwardly toward the mother board, a card guide provided for each of the platforms for guiding one of the cards for movement in a horizontal direction to send the card onto the platform, and a mother board side connector provided on a bottom face or a top face of the mother board for each of the cards, the connector of any of the cards being connected to one of the mother board side connectors when, after the card is sent onto the corresponding platform under the guidance of the corresponding card guide, the platform is moved upwardly or downwardly toward the mother board by the corresponding driving mechanism. 
   The mother board side connectors may be provided on the top face and the bottom face of the motherboard, and a plurality of units each formed from one of the platforms, one of the driving mechanisms and one of the card guides may be provided symmetrically in upward and downward directions on the upper and lower sides of the mother board. 
   The driving mechanism may include a gondola for retaining a card on the corresponding platform and a guide rail for guiding the gondola upon upward or downward movement of the platform. 
   The driving mechanism may include a ball screw held in meshing engagement with a threaded hole provided on the corresponding platform, a first bevel gear fixed to the ball screw, a second bevel gear held in meshing engagement with the first bevel gear, and a rotating tool for rotating the second bevel gear to rotate the first bevel gear thereby to rotate the ball screw to move the platform upwardly and downwardly. 
   Preferably, the gondola is formed from a material which intercepts magnetism and electromagnetic waves. 
   Preferably, fans for generating air flows to cool the cards are provided. 
   With the card mounting rack, cards are mounted on one or both of the top and bottom faces of the mother board horizontally placed in the inside of the rack such that they extend in parallel to the side faces of the rack but perpendicularly to the mother board placed horizontally in the inside of the rack. Consequently, the card mounting rack according to the present invention can mount a plurality of large size cards without a limitation to the width of the rack. Therefore, the length of a connection cable between the cards can be reduced, and degradation of a system performance arising from increase of the connection cable between the cards can be suppressed. Further, heat generated from the mother board and the cards in the rack can be radiated efficiently by a cooling system of the front face air sucking and rear face air exhausting type implemented by the cooling fans provided on the front and rear faces of the rack. Therefore, the cooling system may not be provided on upper and lower portions of the rack, and a high-density mounting mechanism free from a dead space can be achieved. Further, it is possible to operate the driving mechanism from both of the front and rear faces of the rack to mount and dismount a card. Therefore, a card exchanging operation can be performed efficiently. Furthermore, if a material having an electromagnetic wave intercepting property is used as the material for forming the gondolas, then occurrence of a problem that electromagnetic wave which is generated from the cards upon driving of the cards leaks to the outside can be prevented. 
   The above and other objects, features and advantages of the present invention will become apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings in which like parts or elements are denoted by like reference symbols. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a card-mounting rack for electronic part-mounting cards according to an embodiment of the present invention; 
       FIG. 2  is a perspective view showing part of the card-mounting rack for electronic part-mounting cards other than panels on the front and rear faces and cooling fans; 
       FIG. 3  is a schematic sectional view of the card-mounting rack for electronic part-mounting cards; 
       FIG. 4  is a schematic sectional view of the card-mounting rack for electronic part-mounting cards taken along a plane different from that used for the sectional view of  FIG. 3 ; and 
       FIG. 5  is a sectional view illustrating operation of the card-mounting rack for electronic part-mounting cards. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to  FIG. 1 , there is shown a card mounting rack according to an embodiment of the present invention. The card mounting rack includes cooling fans  14   a  and  14   b  provided on inner faces of a front face panel  19  and a rear face panel  20  of a housing  11   a  of a rack  11 , respectively. The cooling fans  14   a  provided on the front face panel  19  of the rack  11  suck air from the outside of the housing  11   a . The cooling fans  14   b  provided on the rear face panel  20  of the housing  11   a  exhaust air having absorbed heat generated upon driving of system components such as a mother board  12 , cards  13  and so forth mounted in the inside of the housing  11   a  to the outside of the housing  11   a.    
   Referring now to  FIG. 2 , the mother board  12  is horizontally placed at the vertically central position in the inside of the housing  11   a . A plurality of cards  13  are mounted on upper and lower faces of the mother board  12  through a plurality of connectors  18  provided on the upper and lower faces of the mother board  12 . The cards  13  are placed in respective gondolas  15  provided on both of the upper and lower faces or sides of the mother board  12  for moving the cards  13  in upward and downward directions to mount them onto the mother board  12 . Driving mechanisms  17  for moving the respective gondolas  15  in upward and downward directions to move the cards  13  in upward and downward directions to insert or remove the cards  13  onto or from the mother board  12  are provided on the upper side of the gondolas  15  provided on the upper side of the mother board  12  and on the lower side of the gondolas  15  provided on the lower side of the mother board  12 . Spacers  16  for fixing the cards  13  to protect them from an influence of vibration and so forth are mounted individually between the driving mechanisms  17  and the cards  13 . 
   In the embodiment, a pair of gondola  15  and a pair of driving mechanisms  17  for individually moving the gondolas  15  in upward and downward directions are provided on each of the upper and lower sides of the mother board  12 . Each set of a gondola  15  and a corresponding driving mechanism  17  is hereinafter referred to as unit. However, the units have a structure substantially same as each other and are disposed vertically symmetrically with each other. Thus, the structure of the units is described below taking the units provided on the lower side of the mother board  12  as an example. 
   Referring now to  FIG. 3 , each of the gondolas  15  shown includes card rails  32  provided as a card guide on upper and lower portions thereof for guiding a card  13  for movement in a horizontal direction from the front face or the rear face of the rack not shown in  FIG. 3  to place and retain the card  13  into and in the inside of the gondola  15  perpendicularly to the mother board  12 . Guide rails  21  are provided such that they extend vertically from the upper portion to the lower portion of the gondola  15  for holding the side portions of the gondola  15  for sliding motion and serve as a gondola guide for guiding upward or downward movement of the gondola  15  at four corners of the gondola  15 . 
   Further, a card side connector  18   a  is provided at the upper end, on the mother board  12  side, of the card  13  on which an LSI  33  is mounted. A guide edge panel  31  is provided in the proximity of the card side connector  18   a . Further, the guide edge panel  31  and the lower end of the card  13  are fitted in the card rail  32  provided on the upper portion of the gondola  15  and the card rail  32  provided on the lower portion of the gondola  15 , respectively, so that the card  13  is moved in a horizontal direction from the front face or the rear face side of the rack not shown under the guidance of the card rails  32  until it is guided to a correct position in the gondola  15 . The card  13  is stably fixed in the inside of the gondola  15  by the card rails  32  also after it is accommodated into the gondola  15 . The lower portion of the gondola  15  forms a platform  22  integrated with the gondola  15 . A ball screw  23  is inserted in the threaded hole  22   a  and held in meshing engagement with a threaded hole  22   a  provided at the central portion of the platform  22 . Further, a first bevel gear  24  is fixed coaxially to the ball screw  23  and a second bevel gear  25  is held in meshing engagement with the first bevel gear  24 . If the second bevel gear  25  is rotated, then also the first bevel gear  24  is rotated thereby, and as a result, the ball screw  23  is rotated to move the platform  22  upwardly or downwardly. Guide holes  22   b  for allowing the perpendicular guide rails  21  to pass therethrough are provided at four corners of the platform  22 . 
   Referring to  FIG. 4 , in the present embodiment, a spacer  41  for fixing the card  13  is inserted in the driving mechanism  17  side of the cord  13  connected to a mother board side connector  18   b  of the mother board  12  through the card side connector  18   a  so that the card side connector  18   a  provided on the upper end of the card  13  does not come off from the mother board side connector  18   b  by vibration and so forth upon driving of the system. 
   Next, operation of the card mounting rack according to the present embodiment is described with reference to  FIG. 5 . If the second bevel gear  25  is rotated from the front or rear face side of the rack  11  not shown in  FIG. 5  by force of rotation generated using a rotating tool  26  for rotating the ball screw  23 , then the rotational force is transmitted to the ball screw  23  through the first bevel gear  24  held in meshing engagement with the second bevel gear  25 . The ball screw  23  moves the platform  22  upwardly or downwardly by the rotational force thereof. The platform  22  moves the gondola  15  integrated therewith along the guide rails  21 . Therefore, if force of rotation for moving the platform  22  upwardly is applied to the ball screw  23 , then also the card  13  placed in the gondola  15  moves upwardly. Then, if the card  13  sufficiently moves upwardly, then the card side connector  18   a  provided at the upper end of the card  13  is inserted into the motherboard side connector  18   b  provided on the mother board  12  to connect the card  13  to the mother board  12 . On the other hand, if force of rotation for moving the platform  22  downwardly is applied to the ball screw  23 , then the platform  22  moves downwardly to move the gondola  15  downwardly along the guide rails  21 . As a result, also the card  13  placed in the gondola  15  moves downwardly, and thereupon the card side connector  18   a  provided at the upper end of the card  13  comes off from the mother board side connector  18   b  provided on the mother board  12 . 
   According to the present embodiment, a great number of cards  13  can be mounted in high density by placing the mother board  12  horizontally in the inside of the rack  11  and mounting a plurality of cards  13  from both of the top and bottom faces of the mother board  12  through the connectors  18 . Therefore, such a problem of degradation of performance of the entire system arising from increase of the length of a connection cable between cards of the prior art methods as described above is eliminated. Further, the air-sucking cooling fan  14   a  and the air-exhausting cooling fan  14   b  for cooling heat generated upon driving of the mother board  12  and the cards  13  are provided on the front face panel  19  and the rear face panel  20  of the rack  11 , respectively. Consequently, heat generated in the inside of the rack  11  can be radiated efficiently. Furthermore, in the present embodiment, each card  13  is mounted perpendicularly to the mother board  12  and the bottom faces of the rack  11 . Therefore, the width of the rack  11  does not limit the size of the card  13  at all. Where there is the necessity to mount cards of a greater size, the card mounting rack of the present embodiment can be easily extended in a vertical direction and forward and backward directions of the rack. 
   Further, in the present embodiment, the gondola  15  is moved upwardly or downwardly in high accuracy along the guide rails  21 . Therefore, the gondola  15  is not deflected in a left or right direction, and the card side connector  18   a  and the mother board side connector  18   b  are not displaced from each other. Further, if also the top face side of the mother board  12  is configured similarly with the structure just described, then a great number of cards can be mounted in high density. 
   It is to be noted that, in the present embodiment, a panel having an air-sucking cooling fan provided thereon and a panel having an air-exhausting cooling fan provided thereon are placed onto the front and rear faces of the rack  11 , respectively, after predetermined numbers of cards  13  are mounted onto the top and bottom faces of the mother board  12 . Consequently, heat generated from the mother board  12  and the cards  13  upon driving can be radiated efficiently. 
   Further, in the present embodiment, the material for forming the gondolas  15  is not limited specifically. Preferably, however, a material having an intercepting characteristic for magnetism and electromagnetic wave is used. Thus, occurrence of a problem that electromagnetic wave which is generated from the cards upon driving of the cards leaks to the outside can be prevented. 
   While a preferred embodiment of the present invention has been described using specific terms, such description is for illustrative purposes only, and it is to be understood that changes and variations may be made without departing from the spirit or scope of the following claims.