PATENT ABSTRACT
A stackable mobile storage device is provided, including a first mobile drive, at least a second mobile drive and a detachable module plugged between the first mobile drive and the second mobile drive to stack each other. The detachable module is composed of a male connector and a female connector. Especially, the second mobile drive is connected to a control unit of the first mobile drive by a switching unit when serving as a mobile drive for expanding capacity, to be enabled by the control of the first mobile drive. Therefore, the memory capacity of the second mobile drive can be added to the first mobile drive with more capacity to store more data.

PATENT DESCRIPTION
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims the priority benefit of Taiwan application serial no. 94104990, filed on Feb. 21, 2005. All disclosure of the Taiwan application is incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of Invention  
         [0003]     The present invention relates to a mobile storage device, more specifically, to a stackable mobile storage device.  
         [0004]     2. Description of Related Art  
         [0005]     Nowadays is information and multi-media age, a vast amount of information is digitized before being processed. Large size magnetic disks were used in the past, however, affected by magnetization effect, so that the magnetic disks were gradually eliminated due to its insufficient capacity, and small storage memories with larger capacity. A smaller storage medium with larger storage capacity and smaller volume has been introduced instead. Memory card, mobile drive (or walk drive) and micro hard drive in most common use have been developed based on the flash memory technology. In addition, these new type drives have advantages of easy carrying and convenient access.  
         [0006]     Generally speaking, in the fabrication of the mobile drive, the mobile drive can mutually supports USB1.1 interface and USB2.0 interface to transport vast amount of data, so as to be compatible to a computer and its peripherals. And, the mobile drive requires no reading device (such as card reader), and features in plug-and-play. Moreover, since the capacity of the mobile drive is getting larger and larger, and it can store up to hundreds of compressed songs (such as MP3 music, etc.). Therefore, it can be very conveniently used as a walkman or pen recorder.  
         [0007]     Remarkably, the capacity of the conventional single mobile drive is fixed, and no extension slot is designed on the drive. Thus, it is impossible to expand the capacity of the mobile drive when the user finds that the capacity is insufficient. As a result, one has to partially delete or completely erase the data on the original mobile drive, or transfer the data to a computer hard drive, so that new data can be stored on the mobile drive. This is very inconvenient. If the size of the new data is larger than the capacity of the mobile drive, the user has to use an alternative method or purchase a drive with lager capacity to solve this issue. However this will increase the cost. Therefore, the conventional single-capacity mobile drive is not convenient in various uses, and the capacity of each mobile drive can&#39;t be shared, thus its usability is affected.  
       SUMMARY OF THE INVENTION  
       [0008]     The object of the present invention is to provide a stackable mobile storage device which can expand the capacity of the mobile drive.  
         [0009]     Another object of the present invention is to provide a control circuit by which the capacity of each mobile drive can be aggregated into a larger capacity to store more data conveniently.  
         [0010]     The present invention provides a stackable mobile storage device including a first mobile drive, at least one second mobile drive and a detachable module. The first mobile drive includes a transmitting interface and a control unit, and the second mobile drive is stacked on the first mobile drive. Wherein, the first mobile drive has a first memory, while the second mobile drive has a second memory, and the capacity of the second memory can be added to the capacity of the first memory through a switching unit and is enabled by the control unit. In addition, the detachable module is coupled between the first and second mobile drives.  
         [0011]     The present invention provides a control circuit which is suitable for using in a mobile storage device with a plurality of mobile drives. Each of the mobile drives has a memory, a control unit, a detachable module and a switching unit. Wherein, the detachable module has a male connector and a female connector, and the mobile drives are electrically coupled to each others by a manner of the combination of the male and the female connectors. In addition, the switching unit has a first switch, a second switch and a third switch, wherein the first switch is coupled between the control unit and the memory, and the second switch is coupled between the male connector and the memory, and the third switch is coupled between the female connector and the memory, so that the memory of each mobile drive is enabled by the control unit.  
         [0012]     The present invention further provides a capacity expandable mobile drive which includes a base block, a transmitting interface, at least one connector and a switching unit. The base block includes a control unit and a memory, wherein the control unit is to control the reading and the writing operations on the memory. Moreover, the transmitting interface can be protruded out or hidden within the base block, and be electrically connected with the control unit. In addition, the connector is implemented on the base block to connect at least one second mobile drive which has a second memory. Furthermore, the switching unit has a plurality of switches wherein one of these switches is coupled between the control unit and the memory, and another one of these switches is coupled between the connector and the memory. As a result, the second memory of the second mobile drive can be enabled through the control unit.  
         [0013]     According to the embodiment of the present invention, the above control unit for example includes a control chip and a circuit board, and the control chip is electrically connected to a transmitting interface through the circuit board. In addition, the transmitting interface is, for example, a universal serial bus (USB) interface. Moreover, the switching unit is, for example, an electronic three-way switch or a mechanical three-way switch.  
         [0014]     The detachable module and the switching unit coupled between two mobile drives are used in the present invention to form a stackable mobile storage device with expandable capacity and its control circuit. Therefore, a single mobile drive can be used individually, and when a plurality of mobile drives are stacked together, the memories can be shared so as to increase the selectivity and manipulability of the mobile drive on using.  
         [0015]     These and other exemplary embodiments, features, aspects, and advantages of the present invention will be described and become more apparent from the detailed description of exemplary embodiments when reading in conjunction with accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]      FIG. 1A - FIG. 1B  schematically illustrate the outer appearance and internal block diagram of a stackable mobile storage device, according to an embodiment of the present invention.  
         [0017]      FIG. 2  schematically illustrates the block diagram of the internal equivalent circuit of the storage device of  FIG. 1A .  
         [0018]      FIG. 3  and  FIG. 4  respectively schematically illustrate the outer appearance and the block diagram of the internal equivalent circuit of a stackable mobile storage device, according to an embodiment of the present invention.  
         [0019]      FIG. 5  schematically illustrates the disassembling and assembling diagram of a stackable mobile storage device, according to another embodiment of the present invention.  
         [0020]      FIG. 6  schematically illustrates the block diagram of the internal equivalent circuit of the stackable flash storage device of  FIG. 5 . 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0021]      FIG. 1A - FIG. 1B  schematically illustrate the outer appearance and internal block diagram of a stackable storage device, according to an embodiment of the present invention. And  FIG. 2  schematically illustrates a block diagram of the internal equivalent circuit of the storage device of  FIG. 1A . Referring to  FIGS. 1A-1B , first, the stackable storage device  100  for example includes a base block  110 , a transmitting interface  120 , a male connector  132 , a female connector  134  and a switching unit  140 . Wherein, the base block  110  has a built-in control unit  112 , such as control a chip  114 , a circuit board  116  and the related parts thereof (not shown) etc. The control chip  114  can be electrically connected with the transmitting interface  120  through the circuit board  116  as shown in  FIG. 1B . A usual transmitting interface  120  is, for example, a universal serial bus (USB) interface, an IEEE 1394 transmitting interface or other high speed transmitting interface, and preferably, the transmitting interface satisfying the specification of USB1.1 and USB2.0. In the present embodiment, although the transmitting interface  120  is protruded out of the base block  110 , it can also be a retractable design (not shown) within the base block  110 . The transmitting interface  120  can be electrically connected to the control unit  112  through a flat cable  136 , so that the transmitting interface  120  can be hidden in the base block  110 .  
         [0022]     With referring to  FIG. 1B , the base block  110  further includes a memory  118  inside, which includes for example a flash memory or other types of high capacity storage medium, implemented on the circuit board  116 . The control chip  114  can access data on the memory  118 . Remarkably, the switching unit  140  is implemented on the circuit board  116 . In the equivalent circuit shown in  FIG. 2 , a switching unit  140  including a plurality of switches  141 - 143  or a single three-way switch (shown in  FIG. 1A ) is implemented between the control chip  114  and the memory  118  to switch the master/slave property of the storage device. When the storage device  100  is used individually, just by switching the switching unit  140  to the master connection end (close the switch  140  in the middle, and leave the upper and lower switches  141  and  143  open), the mobile drive can serve as a regular mobile drive. Moreover, to use a plurality of storage devices  100 , just by combining the male connector  132  and the female connector  134  for switching its storage device to slave connection end (leaving the switch  142  in the middle open, and closing the upper and lower switches  141  and  143  respectively), the mobile drive can then serve as an expanded mobile drive to expand the capacity of the memory  118 .  
         [0023]     With referring to  FIG. 3  and  FIG. 4 , both respectively show the diagram of the outer appearance and the block diagram of the internal equivalent circuit of a stackable mobile storage device of an embodiment of the present invention. The stackable mobile storage device  200  for example includes a first mobile drive  210 , at least one second mobile drive  220  and a detachable module  230 . The structure and function of the first mobile drive  210  are the same as those of the second mobile drive  220 . Inside the base block,  212 ,  222 , both have control chips  214 ,  224  and memories  216  and  226 , respectively. The difference is that when the first mobile drive  210  serves as the mobile drive of the master control end, the switch  218  in the middle is electrically coupled between the control chip  214  and the memory  216 , and leaves the circuit of upper and lower switches open. The second mobile drive  220  can only open the circuit of the middle and upper switches, and close the circuit of the lower switch  228  to connect the memory  226  and the corresponding female connector  234 , so that the second mobile drive serves as a mobile drive with an expanded capacity. In addition, the first and the second mobile drives  210  and  220  can be stacked on top of each other through a detachable module  230  that combines the male connector  232  to the female connector  234 . Specifically, the memory  226  of the second mobile drive  220  can be enabled by the control of the control chip  214  to store data.  
         [0024]     In the above embodiment, the transmitting interface (not shown) can be hidden within the base block  222  to avoid hindering the use of the transmitting interface  240  of the first mobile drive  210  when the second mobile drive  220  serves as the capacity expanding mobile drive. Moreover, if the second mobile drive  220  is used individually, the user can just conveniently set the transmitting interface (not shown) to protrude out of the base block  222 , thus enable the users to have various options of memory capacities without causing the insufficient memory problem.  
         [0025]     In addition, with referring to the  FIG. 5  and  FIG. 6 , both illustrate the diagram of the outer appearance and the internal equivalent circuit about a stackable mobile storage device, with an embodiment of the present invention. The stackable mobile storage device  300  for example includes a first mobile drive  210 , at least a second mobile drive  220 , at least a third mobile drive  320  and two detachable modules  230  and  330 . The structure and function of the first mobile drive  210  and the second mobile drive are as described in the previous embodiment, and there are also a control chip  324  and a memory  326  inside the base block  322  of the third mobile drive  320 . Specifically, when the first and the second mobile drive  210 ,  220  are stacked on top of each other through a detachable module  230  between them, the first and the third mobile drives  210  and  320  can also be stacked on top of each other through another detachable module  330  (the combination of the male connector  332  and the female connector  334 ). In addition, the middle and the lower switches of the third mobile drive  320  are off, and the upper switch between the memory  326  and the corresponding male connector  332  is conducted, so that the whole of drive serves as a capacity expanding mobile drive, thus the mobile drive can be used very conveniently.  
         [0026]     Similarly, the memory  326  of the third mobile drive  320  can also be enabled through the control chip  214  in the first mobile drive  210 . Also and, the transmitting interface (not shown) can be hidden within the base block  322  to avoid hindering the use of the transmitting interface  240  in the first mobile drive  210  when the third mobile drive serves as a capacity expanding mobile drive. In addition, the transmitting interface (not shown) can be just protruded out of the base block  322  if the third mobile drive is used individually. The switch at the middle is conducted and the upper and lower switches are off. The reading and writing operations on the memory  326  are controlled by its own control unit  324 .  
         [0027]     It can be understood from the above descriptions, since a detachable module and a switching unit are used in the present invention to connect two mobile drives, a stackable mobile storage device and its control circuit with expandable memory capacity are formed. Wherein, each of the mobile drives is equipped with at least one connector (e.g. a male connector or a female connector, or both) which is capable of expanding the capacity of the memory, so that the capacity of the memory can be aggregated into a larger capacity. Moreover, the switching unit can be an electronic three-way switch, a mechanical three-way switch or a plurality of switches in combination.  
         [0028]     In summary, the stackable mobile storage device and the control unit thereof of the present invention have at least the advantages as follows:  
         [0029]     (1) Each mobile drive can be used individually, and a plurality of mobile drives can also be stacked on top of each other to share the memory to increase the selectivity and manipulability of the mobile drive.  
         [0030]     (2) The transmitting interface can be hidden within the base block to avoid hindering the use of the transmitting interface in the master control end of the mobile drive when the mobile drive serves as a capacity expanding mobile drive.  
         [0031]     While the present invention has been particularly shown and described with referring to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.