Abstract:
A system includes a first apparatus and a second apparatus. The first apparatus includes a first surface, a depression in the first surface, and a first connector disposed on the first surface. The depression has a bottom with a hole through which a screw for assembling the apparatus is passed and accommodates the head of the screw. The second apparatus includes a second surface facing the first surface when the first apparatus is detachably attached, a second connector disposed on the second surface and engaging with the first connector, and a protrusion fixed into the depression when the first apparatus is attached.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2011-1309 filed on Jan. 6, 2011, the entire contents of which are incorporated herein by reference. 
     FIELD 
     This embodiment relates to a system including a first apparatus and a second apparatus. 
     BACKGROUND 
     A notebook personal computer (notebook PC) is an example of an electronic apparatus. There is a known detachable expansion apparatus for the notebook PC. Such an expansion apparatus is referred to as, for example, a port replicator, a docking station, or an expansion adaptor. A port replicator increases the number of connectors for connecting the notebook PC and external devices and allows the notebook PC to be carried while keeping cables connected to the external devices. 
     Notebook PCs of various different types and models are commercially available. Port replicators of various different models matching those of the notebook PCs are also commercially available. Even if a notebook PC and a port replicator allow the use of connectors conforming to the same standard, a notebook PC and a port replicator should not be used in combination if their models do not match. If an unmatching combination of notebook PC and port replicator is used, the notebook PC may not operate normally, and damage due to short-circuiting may be imposed to the internal circuits of the notebook PC. 
     In the related art, there is a known structure for preventing incorrect insertion and incorrect attachment that includes, for example, a plurality of protrusions attached to the edge section of a printed circuit board and a plurality of engagement holes fitted with these protrusions. 
     It is, however, not preferable for a notebook PC to have a special structure, such as that in the related art, for preventing incorrect insertion and incorrect attachment. Such a structure limits the design flexibility of the notebook PC. 
     Such a problem is common for notebook PCs and also various different apparatuses. 
     SUMMARY 
     According to an embodiment, a system includes a first apparatus and a second apparatus. The first apparatus includes a first surface, a depression in the first surface, and a first connector disposed on the first surface. The depression has a bottom with a hole through which a screw for assembling the apparatus is passed and accommodates the head of the screw. The second apparatus includes a second surface facing the first surface when the first apparatus is detachably attached, a second connector disposed on the second surface and engaging with the first connector, and a protrusion fixed into the depression when the first apparatus is attached. 
     The object and advantages of the various embodiments 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 various embodiments, as claimed. 
     Additional aspects and/or advantages will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the various embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a notebook PC in a closed state. 
         FIG. 2  is a perspective view of a notebook PC in an open state. 
         FIG. 3  is a perspective back view of a notebook PC in a closed state. 
         FIG. 4  illustrates the notebook PC in  FIG. 3  in an inverted state. 
         FIG. 5  is a perspective back view of a port replicator. 
         FIG. 6  is a bottom view of a main body of an apparatus. 
         FIG. 7  is a sectional perspective view taken along line X-X in  FIG. 6 , where a notebook PC is attached to a port replicator. 
         FIG. 8  is a sectional view taken along line X-X in  FIG. 6 , where the notebook PC is attached to the port replicator. 
         FIG. 9  is a perspective view of part of the bottom side of the main body of the apparatus. 
         FIG. 10  is a perspective view of a port replicator. 
         FIG. 11  is an enlarged perspective view of part of the upper side of the port replicator. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     An embodiment will be described below. 
       FIG. 1  is a perspective view of a notebook PC (Personal Computer) in a closed state.  FIG. 2  is a perspective view of a notebook PC in an open state. The notebook PC is an example of a first apparatus or a main apparatus according to the present invention. The notebook PC may otherwise be an example of an electronic apparatus. 
     The notebook PC  100  includes a main apparatus  110  and a display apparatus  120 . The display apparatus  120  is connected to the main apparatus  110  with a hinge  130 . 
     The display apparatus  120  of the notebook PC  100  can be freely opened or closed around the hinge  130 .  FIG. 1  illustrates a closed state of the display apparatus  120 ; and  FIG. 2  illustrates an open state of the display state. 
     The upper side of the main apparatus  110  has various indicators  111 , various function buttons  112 , a keyboard  113 , a track pad  114 , and so on. The main apparatus  110  accommodates a circuit board. On the circuit board, electronic parts, such as a central processing unit (CPU) (not shown), which is the core of computation, are mounted. 
     The display apparatus  120  includes a display screen  121 . The display screen  121  displays various images in accordance with instructions (signals) from the main apparatus  110 . 
       FIG. 3  is a perspective back view of the notebook PC in a closed state.  FIG. 4  illustrates the notebook PC in  FIG. 3  but in an inverted state. 
     The back side of the main apparatus  110  of the notebook PC  100  has an exhaust port  141 , a LAN port  142 , a USB port  143 , a display port  144 , a VGA connector  145 , a suction port  146 , and another exhaust port  147 . 
     The bottom side of the main apparatus  110  has a connector  148  for electrical connection with the port replicator, which will be described below. Additionally, the bottom side of the main apparatus  110  has depressions  149 , which receive screws (not shown) used for assembly of the main apparatus at positions sandwiching the connector  148  and other positions. By accommodating screws for assembly of the main apparatus  110  in the notebook PC  100 , electrostatic discharge caused by contact to the screws is prevented. Such a structure prevents the electronic circuits in the main apparatus  110  from being adversely affected by the electrostatic discharge. The screws may not be exposed on the bottom side of the notebook PC  100  to improve the external appearance. Metal contacts  150  are exposed on the bottom side of the main apparatus  110  to provide a ground electrical potential across main apparatus  110  and the port replicator. 
       FIG. 5  is a perspective back view of the port replicator. 
     The port replicator  200  is detachable from the notebook PC  100 . The bottom side of the backward part of the notebook PC, which is illustrated in  FIGS. 1 to 3 , is placed on the port replicator  200 . Accordingly, the port replicator  200  is shaped to fit together with the bottom side of the backward part of the notebook PC. The upper side of the port replicator  200  has a connector  210 , which engages with the connector  148  (see  FIG. 4 ) on the bottom side of the notebook PC  100 . The upper side of the port replicator  200  faces the bottom side of the notebook PC  100  when the notebook PC  100  is attached. The port replicator  200  has two protrusions  220  near the connector  210  for preventing incorrect connection of the connector. The protrusion  220   a  illustrated in  FIG. 5  is one of the two protrusions  220 . The protrusions  220  are inserted into the two protrusions  149   a  and  149   b  adjoining the connector  148  on the bottom side of the main apparatus  110 . In  FIG. 5 , the protrusion  220   a  is inserted into the depression  149   a , and the protrusion inserted into the depression  149   b  is disposed on the upper side of the port replicator  200  but is hidden behind the protruding part  201  and is not visible in the drawing. 
     The upper side of the port replicator  200  has a plurality of electric contacts  230  protruding upward. The electric contacts  230  provide a common ground potential across the main apparatus  110  and the port replicator  200 . The electric contacts  230  contact the metal contacts  150  exposed on the bottom side of the main apparatus  110 . 
     The protruding part  201  of the port replicator  200  covers the connectors on the back side of the main apparatus  110  to prevent the connectors from being used when the notebook PC  100  is attached to the port replicator  200 . Part of the upper side of the port replicator  200  is lower than the protruding part  201  so that the exhaust ports  141  and  147  and the suction port  146  (see  FIG. 3 ) of the main apparatus  110  are exposed at the back side of the port replicator  200 . 
     As illustrated in  FIG. 5 , the back side of the port replicator  200  has a LAN port  241 , four USB ports  242 , an ESATA port  243 , a VGA connector  244 , a DVI connector  245 , a display port  246 , and a serial connector  247 . These ports and connectors are wired to the connector  210 . The back side of the port replicator  200  also has a lock hole  248 . 
     When the notebook PC  100  is attached to the port replicator  200 , instead of the connectors on the notebook PC  100 , the connectors on the port replicator  200  are used via the connector  210  and the connector  148 . 
     In this way, a user can detach the notebook PC  100  from the port replicator  200  and carry the notebook PC  100  while keeping the cables connected to the connectors of the port replicators  200 . 
     The embodiment will be described in more detail below. 
       FIG. 6  is a bottom view of the main apparatus.  FIGS. 7 and 8  are sectional perspective views, taken along line X-X in  FIG. 6 , of the notebook PC  100  attached to the port replicator  200 .  FIG. 7  illustrates the port replicator  200  with the bottom surface facing upward.  FIG. 9  is a perspective view of part of the bottom side of the main apparatus  110 .  FIG. 10  is a perspective view of the port replicator  200 .  FIG. 11  is an enlarged perspective view of part of the upper side of the port replicator  200 . 
     As illustrated in  FIGS. 6 and 9 , the bottom side of the main apparatus  110  has the connector  148  and the two depressions  149   a  and  149   b . The connector  148  on the bottom side of the main apparatus  110  is interposed between the two depressions  149   a  and  149   b.    
     As illustrated in  FIGS. 7 and 8 , screw holes  151   a  and  151   b  for screws  161   a  and  161   b , respectively, are formed at the bottoms of the respective depressions  149   a  and  149   b  in the main apparatus  110 . The screws  161   a  and  161   b  secure a circuit board  162  embedded in the main apparatus  110  by being screwed into the holes  151   a  and  151   b . The heads of the screws  161   a  and  161   b  securing the circuit board  162  are accommodated in the depressions  149   a  and  149   b , respectively. As described above, this structure prevents the electronic circuit devices (not shown) on the circuit board  162  from being adversely affected by electrostatic discharge caused by contact to the screws and is often used in typical notebook PCs, regardless of the use of the port replicator  200 . 
     The port replicator  200  has the two protrusions  220   a  and  220   b  sandwiching the connector  210 . The connector  210  engages with the connector  148  (see  FIGS. 6 and 9 ) on the bottom side of the main apparatus  110  of the notebook PC  100  when the notebook PC  100  is attached to the port replicator  200 . The two protrusions  220   a  and  220   b  are respectively inserted into the two depressions  149   a  and  149   b  on the bottom side of the notebook PC  100  when the notebook PC  100  is attached to the port replicator  200 , as illustrated in  FIGS. 7 and 8 . 
     By positioning the depressions on the bottom side of the notebook PC and the protrusions on the upper side of the port replicator in accordance with the combination of the notebook PC and the port replicator, the protrusions  220   a  and  220   b  will collide with the bottom side of the notebook PC if a user tries to attach a notebook PC of a different model to the port replicator  200 , even if the notebook PC may happen to have a connector that is the same as the connector  148 . In this way, incorrect attachment of a notebook PC and the port replicator  200  can be prevented. 
     In this embodiment, the main apparatus  110  prevents incorrect attachment of the notebook PC  100  and the port replicator  200  by the depressions  149   a  and  149   b  accommodating the screws  161   a  and  161   b , which secure the embedded circuit board  162 . Accordingly, incorrect attachment of the notebook PC and the port replicator is prevented without carrying out any special processing or adding any parts to the notebook PC. 
     As described above, a circuit board is also embedded in the port replicator  200  to wire the various ports and connectors on the back side to the connector  210  on the upper side. The bottom side of the port replicator  200  has depressions accommodating screws, such as those in the main apparatus  110 . The circuit board is secured to the port replicator  200  by the screws whose heads are accommodated the depressions. In another embodiment, to prevent incorrect attachment of a notebook PC and a port replicator, screw-accommodating depressions may be formed on the upper side of the port replicator, and protrusions inserted into the depressions may be formed on the main apparatus. 
     The electronic apparatus may be other computer such as a workstation but the PC. And, the electronic apparatus may be a slate-type computer but the notebook-type computer. 
     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.