Patent Publication Number: US-2004057199-A1

Title: Expansion unit and electronic-apparatus system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001] This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2002-190895, filed Jun. 28, 2002, 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 an expansion unit for expanding the function of portable electronic apparatus such as a personal digital assistant (PDA) and an electronic-apparatus system including the expansion unit and electronic apparatus. More specifically, the invention relates to an expansion unit and an electronic-apparatus system, which decrease the number of connectors through the shared use of a connector for both data synchronization and function expansion and which allow a plurality of expansion units to be added in multiple stages through a single connector with the connector available for data synchronization.  
       [0004] 2. Description of the Related Art  
       [0005] In recent years, battery-operable portable electronic apparatus such as a PDA has become widespread. In general, the main body of this type of electronic apparatus has only the fundamental function to prevent its portability from deteriorating and an expansion unit for expanding the function can be connected to the electronic apparatus when the need arises.  
       [0006] For example, in the electronic apparatus disclosed in Jpn. Pat. Appln. KOKAI Publication No. 6-195153, a plurality of option modules can be connected through a single additionally optional connector by connecting the option modules in series to the additionally optional connector. According to this apparatus, even though a number of expansion options are mounted, a number of connectors need not be provided and thus the electronic apparatus can be prevented from increasing in size.  
       [0007] The above electronic apparatus always includes a connector for transmitting/receiving data to/from a so-called personal computer such as a desktop one and a notebook one. In order to downsize the electronic apparatus further, recently, a connector for connecting signal lines for data synchronization and a connector for connecting signal lines for function expansion have been combined into one.  
       [0008] However, the above-described connector causes a problem that one of transmission/reception of data to/from a personal computer and function expansion has only to be exclusively used. Furthermore, the above Jpn. Pat. Appln. KOKAI Publication No. 6-195153 teaches connecting a plurality of expansion units to an additionally optional connector that is provided separately and does not have any concept of relaying a data-synchronizing signal line that is not used for function expansion. If, therefore, the electronic apparatus of the Publication is adopted, a plurality of expansion units can be used simultaneously, but no data can be transmitted to or received from the personal computer while the expansion units are connected.  
       BRIEF SUMMARY OF THE INVENTION  
       [0009] An embodiment of the present invention may provide an expansion unit and an electronic-apparatus system that allow a plurality of expansion units to be connected in multiple stages through a single connector with the connector available for data synchronization.  
       [0010] According to an aspect of the invention, it provides an expansion unit that is detachably capable to be connected to electronic apparatus having a first connector, comprising a second connector electrically connected to the first connector, a third connector whose shape is equal to that of the first connector and which is connected to other electronic apparatus being different from the electronic apparatus, and a signal line which electrically connects the second connector and the third connector together.  
       [0011] The another aspect of the invention, it provides an electronic-apparatus system comprising electronic apparatus and a first expansion unit detachably connected to the electronic apparatus, the electronic apparatus comprising a first connector used for both data communications with other electronic apparatus and function expansion of the electronic apparatus, and the first expansion unit comprising a second connector electrically connected to the first connector, a third connector having a same shape as that of the first connector and being connectable to the other electronic apparatus, and a first signal line which electrically connects the first connector and the second connector together.  
       [0012] Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The features and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter. 
     
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
     [0013] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the invention.  
     [0014]FIG. 1 is an external view of an electronic-apparatus system according to an embodiment of the present invention;  
     [0015]FIGS. 2A and 2B are diagrams each showing a connection mode of the electronic-apparatus system according to the embodiment of the present invention;  
     [0016]FIG. 3 is a diagram showing an example of a structure of signal lines formed in an expansion unit of the electronic-apparatus system shown in FIGS. 1 and 2A and  2 B; and  
     [0017]FIG. 4 is a block diagram showing an example of use of the electronic-apparatus system according to the embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     [0018] The embodiments of the present invention will be described below with reference to the drawings.  
     [0019]FIG. 1 is an external view of an electronic-apparatus system according to the embodiment of the present invention.  
     [0020] As shown in FIG. 1, the electronic-apparatus system includes a main device  10  that is called, for example, a PDA and an expansion unit  20  for expanding the function of the main device  10 . An LCD  11  for displaying data and operating buttons  12  for inputting data are arranged as a user interface on the front of the main device  10 . A connector  13  for connecting both a data-synchronizing signal line and a function-expanding signal line to a personal computer is formed on the bottom of the main device  10 . In other words, the connector  13  is a shared connector serving to connect both the data-synchronizing signal line and the function-expanding signal line in order to reduce the number of connectors. Thus, the main device  10  is decreased in size and cost.  
     [0021] The expansion unit  20  includes a connector  22  having the same shape as that of the connector  13  of the main device  10  as well as a connector  21  that is fitted to the connector  13 . In other words, another expansion unit  20  can be connected in series to the expansion unit  20 . The expansion unit  20  includes a group of signal lines for deriving a signal line, which is connected through the connector  21 , from the connector  22 . Thus, the main device  10  can transmit/receive data to/from a personal computer even though the expansion unit  20  is connected to the main device  10 .  
     [0022] The expansion unit  20  shown in FIG. 1 is used to add a function of displaying an image, which is displayed on the LCD  11 , on an external display device such as a cathode ray tube (CRT). To do so, a connector  23  for connecting the expansion unit  20  to the external display device through a cable is provided on one side of the expansion unit  20 .  
     [0023] The area of the surface of the expansion unit  20  on which the connector  21  is provided is substantially the same as that of the bottom of the main device  10 . Further, the width of the expansion unit  20  is substantially the same as that of the main device  10  and so is the thickness.  
     [0024]FIGS. 2A and 2B are diagrams showing a connection mode of the electronic-apparatus system.  
     [0025] In FIGS. 2A and 2B, reference numeral  30  indicates a cradle in which the main device  10  is held when data is transmitted to/received from a personal computer. Like the expansion unit  20 , the cradle  30  has a connector  31  that is fitted into the connector  13  of the main device  10 . Since the connector  22  of the expansion unit  20  has the same shape as that of the connector  13  as described above, the connector  31  of the cradle  30  is also fitted into the connector  22 .  
     [0026] In the electronic-apparatus system described above, a connector for connecting the data-synchronizing signal line and a connector for connecting a function-expanding signal line are combined into a single shared connector (connector  13 ). However, the expansion unit  20  and cradle  30  can be used simultaneously, not exclusively or selectively.  
     [0027]FIG. 3 is a diagram showing an example of a structure of the group of signal lines formed in the expansion unit  20  shown in FIGS. 1 and 2A and  2 B.  
     [0028] In FIG. 3, reference symbol a indicates a signal line for outputting display data to an external display device, which relays a line between the connectors  21  and  23 . Reference symbol b denotes a signal line for data synchronization with a personal computer, which relays a line between the connectors  21  and  22 . Reference symbol c indicates, for example, a power supply line and other signal lines that relay a line between the connectors  21  and  22 .  
     [0029] The signal line b relays a data-synchronizing signal line, which is derived from the main device  10 , from the connector  21  of the expansion unit  20  to the connector  22  thereof; therefore, the expansion unit  20  can be used as shown in FIG. 4. In other words, a function of increasing a memory capacity while data is being transmitted to/received from a personal computer  41  via the cradle  30  or a function of a global positioning system (GPS) for measuring the current position is added by the first expansion unit  20 . A function of displaying an image, which is displayed on the LCD  11 , on an external display device  42  is added by the second expansion unit  20 . Further, a function of inputting data through an external keyboard or gaining access to an external magnetic disk drive (HDD)  44  is added by the third expansion unit  20 .  
     [0030] As described above, the electronic-apparatus system reduces the number of connectors by the shared use of a connector for both data synchronization and function expansion and allows a plurality of expansion units  20  to be added in multiple stages through a single connector with the connector available for data synchronization.  
     [0031] Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.