Patent Publication Number: US-2003223142-A1

Title: Method and device for data storage using wireless communication

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. 2002-162877, filed Jun. 4, 2002, the entire contents of which are incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002] 1. Field of the Invention  
       [0003] This invention relates to an electronic device having a wireless data communications function, in particular, a technique to be applied to a portable data storage device which can record data received in the form of a radio wave on a recording medium.  
       [0004] 2. Description of the Related Art  
       [0005] Recently, a technique of performing data transfer between personal computers, or between a personal computer and a peripheral device, by using short-range wireless data communications, in particular, has been put into practical use. As a developed form of such a technique, a portable data storage device having a wireless data communications unit has been proposed.  
       [0006] The portable data storage device is a dedicated terminal including a disk drive, such as a hard disk drive (HDD) and a magnetic optical disk drive, or a flash memory as a storage medium, and recording data demodulated from a radio wave received by its wireless data communications unit on the storage medium. A transmitting source of data is an information device, such as a digital camera. The digital camera has a wireless data communications unit, and transmits data of taken images by a radio wave to the portable data storage device.  
       [0007] The portable data storage device can store a large amount of image data since it has a storage medium having a large capacity, such as a disk drive. When storing data, the portable data storage device is connected to the digital camera by wireless communications, and thus it is possible to greatly ease restrictions on operating the digital camera, unlike the case where they are connected by a cable. Specifically, the user can store data of images taken by the digital camera in the storage medium of the portable data storage device, placed distantly from the digital camera, in real time.  
       [0008] Although the portable data storage device having a wireless data communications function is very useful, if a radio wave which is being transferred is interrupted, data writing into the storage medium is interrupted. In particular, a short-range wireless communications unit has a short effective communications range with an information device which transfers data. Therefore, if the distance between the portable data storage device and the information device increases, sometimes a wave reception state (that is, data reception state) of the portable data storage device becomes poor.  
       [0009] If such a poor radio wave reception state occurs during data writing, data writing to the portable data storage device is forcibly interrupted. Therefore, data recording becomes unstable, e.g. a part of data which is being written is erased, and only partial data among data to be written is recorded on the storage medium. Therefore, if the data reception state becomes poor, it is desirable to stop data writing in the storage medium to prevent erase of the data, etc.  
       [0010] However, when the data reception state becomes satisfactory and wireless communications connection with the information device which transfers data is resumed, generally data transfer is performed again from the beginning. Therefore, the portable data storage device repeats writing of the same data as that, whose writing was interrupted, to the storage medium from the beginning. Thus, as a matter of course, the data which was written into the storage medium before wireless communications connection has been interrupted is wasted.  
       [0011] To avoid such a situation, it is desirable to effectively use existing data which has been recorded on the storage medium before interruption of the writing, and record data following the existing data on the storage medium. In short, when the wireless communications connection has been resumed, the portable data storage device performs continued writing. However, performing such an operation requires general users to perform complicated and troublesome operations.  
       BRIEF SUMMARY OF THE INVENTION  
       [0012] In accordance with one embodiment of the present invention, there is provided a data storage device including a wireless communications unit. The data storage device has a structure of stopping data writing to a storage medium when a radio wave received by a wireless data communications function is unallowably weak, and continuing the writing at the point of interruption when wireless communications connection is resumed.  
       [0013] The data storage device comprises:  
       [0014] an antenna device for wireless communications connection with a device being a communications partner;  
       [0015] a receiving unit which demodulates data from a radio wave transmitted from the communications partner device via the antenna device;  
       [0016] a unit which generates transfer control information including identification information to identify the communications partner device connected by wireless communications, and information indicating a range of the data transmitted from the communications partner device;  
       [0017] a data storage medium to record the data demodulated by the receiving unit;  
       [0018] a writing controller which stops writing of the data onto the data storage medium when a wave reception state of the receiving unit has become unallowable during writing; and  
       [0019] a data transfer controller which requests, when the wireless communications connection has been resumed, the communications object device being a transfer source of the data, the writing of which was stopped, to transfer data following data which has been recorded on the data storage medium, in accordance with the transfer control information. 
     
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
     [0020] 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.  
     [0021]FIG. 1 is a block diagram showing a structure of a portable data storage device according to an embodiment of the present invention;  
     [0022]FIG. 2 is a block diagram for explaining a data writing control operation concerning the embodiment;  
     [0023]FIG. 3 is a diagram for explaining contents of transfer control information concerning the embodiment;  
     [0024]FIG. 4 is a flow chart for explaining a writing control operation concerning the embodiment;  
     [0025]FIG. 5 is a flow chart for explaining operations of a device of the other party concerning the embodiment; and  
     [0026]FIG. 6 is a flow chart for explaining a writing control operation at the time of resuming communications connection concerning the embodiment. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     [0027] An embodiment of the present invention will now be explained with reference to the drawings.  
     [0028] (Structure of Portable Data Storage Device)  
     [0029]FIG. 1 is a block diagram showing a main part of a portable data storage device having a wireless communications function according to the embodiment.  
     [0030] The device  1  comprises a disk drive  10  serving as a storage medium, a microprocessor (CPU)  11 , an antenna  12 , an antenna module  13 , a memory  14 , a battery  15 , and a regulator circuit  16 .  
     [0031] The disk drive  10  is assumed to be a hard disk drive (HDD) using a disk storage medium. The CPU  11  is operated by a program stored in the memory  14 , and controls the whole device.  
     [0032] In addition to the program, the memory  14  includes a storage region  140  which stores transfer control information, and a buffer region  141  which temporarily stores data to be written into the HDD  10  (please refer to FIG. 2), as described later. The memory  14  is formed of, for example, a flash EEPROM.  
     [0033] The antenna module  13  is a circuit which controls transmission and reception of data through the antenna  12 , and realizes a function of wireless data communications between an information device  2  being the other party of communications. The battery  15  and the regulator circuit  16  form a power supply unit for supplying power for activating the whole device. The power supply switch  18  controls the power supply from the power supply unit to supply it or cut it off.  
     [0034] The device  1  of the present invention further comprises an alarm unit  17  controlled by the CPU  11 . The alarm unit  17  issues an alarm to the user when data writing into the HDD  10  has been interrupted.  
     [0035] (Data-writing Control Operation)  
     [0036] The data-writing control operation of the embodiment will now be explained, with reference to FIGS.  2  to  6 , in addition to FIG. 1.  
     [0037] The device  1  is assumed to be a portable data storage device which receives, by the antenna  12 , a radio wave (for example, a radio wave obtained by modulating image data) transmitted from an information device  2  (a device which the device  1  is to communicate with), and stores it in the HDD  10 . The information device  2  is a digital camera or the like having a wireless data communications function.  
     [0038] The antenna module  13  demodulates the radio wave received by the antenna  12  into data (e.g. image data), and transfers the data to the buffer region  141  of the memory  14  (please refer to FIG. 2). The CPU  11  successively reads the data stored in the buffer region  141 , and transfers them to the HDD  10 . The HDD  10  writes the transferred data on the disk storage medium, by control of a CPU in the drive.  
     [0039] As shown in FIG. 2, the antenna module  13  includes an RSSI (Reserved Signal Strength Indication) unit  130  for monitoring the reception state of a radio wave received by the antenna  12  (in short, data reception state). The RSSI unit  130  detects intensity of an electric field of a radio wave received by the antenna  12 , and holds the detection result as RSSI information.  
     [0040] At the time of data writing, the CPU  11  reads the RSSI information (α) from the RSSI unit  130  of the antenna module  13  at a predetermined timing (step S 1 ). Further, the CPU  11  reads, from the memory  14 , determination information (β) for determining whether the state of the received radio wave is allowable or not (step S 2 ). The determination information (β) is information corresponding to reference electric field intensity information, which indicates an allowable limit value of a radio wave state. The determination information is stored in advance in a predetermined storage region of the memory  14 .  
     [0041] Further, from the memory  14 , the CPU  11  reads reading interval data (γ) which corresponds to intervals of sampling the RSSI information (step S 3 ). Specifically, the CPU  11  determines whether the state of radio wave is allowable or not on the basis of the RSSI information, at the intervals indicated by the reading interval data (step S 6 ).  
     [0042] (Transfer Control Information)  
     [0043] Furthermore, with establishment of wireless communications connection with the device  2  with which the device  1  communicates, the CPU  11  generates transfer control information for controlling writing of data transmitted from the device  2 , and stores the information in the predetermined storage region  140  in the memory  14  (step S 4 ).  
     [0044] The transfer control information is divided broadly into a header section and data sections, as shown specifically in FIG. 3. The header section is information representing the number of the data sections (N) and the size of the whole data sections (NS). Each of the data sections (1-N) comprises partner device identification information  301 , transfer continuation information  302 , transferred data size  303 , and a file name  304  of the data stored in the disk storage medium of the HDD  10 . The partner device identification information  301  is information of an address or the like by which the information device  2  being an object of communications can be identified. The transfer continuation information  302  is flag information for instructing whether or not to perform continued data transfer (data writing) at the time of reconnection (resumption of communications connection) concerning the embodiment. In this embodiment, generally the transfer is continued, and the user can cancel the function.  
     [0045] The transferred data size  303  is information, which is transferred from the information device  2  being the other party of communications and indicates a range of data (specified by the file name  304 ) stored in the disk storage medium of the HDD  10 .  
     [0046] As described below, the transfer control information is also stored in the information device  2  being the other party of communications connection.  
     [0047] (Data Transfer and Writing Operation)  
     [0048] Before data writing, the CPU  11  acquires, through the antenna module  13 , the partner device identification information  301  for identifying the information device  2  with which the wireless communications connection has been established, and stores it as an item of the transfer control information stored in the memory  14  (step S 5 ).  
     [0049] Next, the CPU  11  compares the acquired RSSI information (α) with the determination information (β) and, if the intensity of the electric field of the received radio wave is greater than the reference value (α&lt;β), executes data writing into the HDD  10  (steps S 6  and S 9 ). Specifically, the CPU  11  transfers the received data (image data in the embodiment) buffered in the memory  14  to the HDD  10 .  
     [0050] The CPU  11  continues the data writing for the time indicated by the reading interval data (γ), and stores the size of the written data, as a transferred data size in the transfer control information (step S 10 ).  
     [0051] Further, the CPU  11  determines whether transfer of data to be stored has been completed or not (step S 1 ). When transfer of all the data transmitted from the information device  2  has been completed, the CPU  11  terminates the data writing into the HDD  10  (YES of step S 11 ). At the time of termination, the CPU  11  deletes information of the data section corresponding to the data (specified by the file name) transfer of which has been completed (i.e., writing has been completed) from the transfer control information ( 140 ) stored in the memory  14  (step S 12 ).  
     [0052] If writing is not completed within the predetermined time (γ), the CPU  11  determines whether the radio wave state is allowable or not (NO of step S 11 ). The CPU  11  acquires new RSSI information (α) from the antenna module  13 , and determines whether the state of the received radio wave is allowable or not, on the basis of the determination information (β). Specifically, the CPU  11  updates the RSSI information (α) by reading new RSSI information (α) from the antenna module  13  at predetermined time intervals (γ).  
     [0053] The CPU  11  compares the acquired RSSI information (α) with the determination information (β) and, if the intensity of an electric field of the received radio wave does not exceed the reference value (α≦β), the CPU stops data writing into the HDD  10  (step S 7 ). Specifically, the CPU  11  stops data transfer from the memory  14  to the HDD  10 . Therefore, at this point of time, the antenna module  13  has already demodulated the radio wave received by the antenna  12  into data, and transferred the data to the memory  14 . Thus, the CPU  11  controls the alarm unit  17 , and the alarm unit  17  outputs an alarm for notifying of stop of the data writing to the HDD  10  (step S 8 ).  
     [0054] As described above, when the wave reception state has become poor while data transmitted from the external information device  2  by a radio wave is being written into the disk storage medium of the HDD  10 , the apparatus  1  stops data writing into the HDD  10 , and gives an alarm to the user. Thereby, when the intensity of the received radio wave has weakened, the data writing into the HDD  10  can be stopped before starting it, and thus it is possible to prevent the situation that the data is erased. Further, since the user can recognize, by the alarm, that the radio reception state has become poor and the data writing into the HDD  10  has been stopped, the user can take suitable measures.  
     [0055] (Resumption of Communications Connection)  
     [0056] In this embodiment, the transfer control information ( 140 ) for managing the data which has been transferred (written) before the data transfer (writing) is stopped is stored in the memory  14 . The operation concerning the resumption (continue of writing) of communications connection using the transfer control information will now be explained.  
     [0057] With reference to the flow chart of FIG. 5, data transfer of the information device  2  being the partner of communications will now be described.  
     [0058] The device  2 , which the device  1  communicates with, executes basically the same operations as those of the device  1 , except that the device  2  transfers data to be recorded to the device  1  (i.e. writing).  
     [0059] Specifically, at the time of data writing (data transfer), the information device  2  reads RSSI information (α) from an RSSI circuit of an antenna module at a predetermined timing (step S 21 ). Further, the information device  2  acquires determination information (β) for determining whether the wave reception state is allowable or not, and reading interval data (γ) (steps S 22 , S 23 ).  
     [0060] On the basis of the RSSI information, the information device  2  determines whether the wave reception state is allowable or not, at time intervals indicated by the reading interval data (γ). If the intensity of the electric field of the received wave is greater than a reference value (α&lt;β), the device  2  executes data writing to the device  1  (steps S 26 , S 28 ).  
     [0061] With establishment of wireless communications connection with the device  1 , the information device  2  also generates transfer control information similar to that generated by the device  1 , and stores the information in a memory (step S 24 ). Further, prior to data writing, the information device  2  also acquires the partner device identification information for identifying the device  1  which has established wireless communications connection, and stores it in the memory as an item of the transfer control information in the memory (step S 25 ).  
     [0062] When transfer of all the data has been finished, the information device  2  deletes information of the data section concerning the data from the transfer control information stored in the memory (YES of step S 29 , and step  30 ). In the meantime, if the wave reception state has become poor during data writing operation, the information device  2  stops the data writing operation (steps S 26  and S 27 ).  
     [0063] Next, with reference to the flow chart of FIG. 6, data transfer control (writing operation control) performed with resumption of wireless communications connection in the device  1 .  
     [0064] First, when the wave reception state of the antenna  12  has become satisfactory and wireless communications connection between the device  1  and the information device  2  has been resumed, the CPU  11  acquires, through the antenna module  13 , the partner device identification information for identifying the information device  2 , and the transfer control information stored in the information device  2  (steps S 41  and S 42 ). Also at the time of resumption of communications connection, the CPU  11  compares the RSSI information (α) acquired from the RSSI circuit  130  of the antenna module  13  with the determination information (β), thereby determines whether the wave reception state has become allowable or not. In the same manner, the CPU  11  also reads the reading interval data (γ) corresponding to the sampling intervals of the RSSI information.  
     [0065] Further, the CPU  11  refers to the transfer control information ( 140 ) stored in the memory  14 , and searches it for data section information including the partner device identification information  301  being the same as the identification information acquired from the information device  2 . If the data section information is not stored, the CPU  11  terminates processing involved in the reconnection (NO of step S 43 ).  
     [0066] If the data section information exists, the CPU  11  takes out the data section information from the transfer control information ( 140 ) stored in the memory  14 , and refers to the information together with the transfer control information (data section information) acquired from the information device  2  (step S 44 ). If the transfer continuation information ( 302 ) of any of the transfer control information is set to flag information indicating “not continue”, the processing involved in the reconnection is terminated (NO of step S 44 ).  
     [0067] If both of the transfer continuation information ( 302 ) are set to flag information indicating “continue”, the CPU  11  requests data retransfer of the information device  2  (YES of step S 44  and step S 45 ). At this time, the CPU  11  transfers to the information device  2  the transferred data size (written data size  303 ) and the file name which are recorded as the data section information of the transfer control information ( 140 ).  
     [0068] In response to such a request, the information device  2  transfers data following the transferred data before transfer from the information device  2  is stopped. When the following data has been transferred to the device  1 , the CPU  11  executes data writing into the HDD  10  (steps S 46  and S 47 ). Specifically, in the HDD  10 , the data following the data recorded on the disk storage medium before the writing was stopped due to a poor wave reception state is written on the disk storage medium. Also in resumption of the writing, the processing from the step S 9  to step S 12  shown in FIG. 4 is repeated.  
     [0069] (Modification)  
     [0070] In the method shown in FIG. 6, it is determined, on the basis of the transfer information acquired from the information device  2  and the transfer continuation information ( 302 ), whether writing of the data following the data recorded before the writing was stopped is to be executed or not (step S 44 ).  
     [0071] Generally, in the case of using a portable data storage device, if transmission of data has been resumed after interruption of a writing operation, it is desirable to continue writing of the following data without condition.  
     [0072] Therefore, as a modification, as shown in FIG. 6, when wireless communications connection between the device  1  and the information device  2  is resumed, the CPU  11  acquires, via the antenna module  13 , the partner device identification information for identifying the information device  2 , and the transfer control information ( 14 ) stored in the memory  14  (steps S 41  and S 42 ).  
     [0073] In this step, if the memory  14  does not store any transfer control information ( 140 ), it means that the writing of the data transmitted from the information device  2  has been completed (please refer to YES of step S 11  in FIG. 4). Therefore, the CPU  11  terminates the processing involved in the reconnection (NO of step S 43 ).  
     [0074] In the meantime, if the transfer control information ( 140 ) is stored in the memory  14 , the CPU  11  searches the transfer control information ( 140 ) for data section information (a data section in which identification information of the information device  2  is recorded). Then, as indicated by a broken line in FIG. 6, the CPU  11  requests data retransfer of the information device  2  (YES of step S 43 , and step  45 ).  
     [0075] In this step, the CPU  11  transfers, to the information device  2 , the size of the transferred data (written data size  303 ) and the file name which are recorded as data section information of the transfer control information ( 140 ). Thereby, when the information device  2  has transferred data following the data recorded before transfer from the information device  2  was stopped, the CPU  11  executes data writing into the HDD  10  (steps S 46  and S 47 ).  
     [0076] According to this modification, it is not necessary to acquire the transfer control information from the information device  2 . Further, the transfer control information ( 140 ) has no need of including transfer continuation information  302 .  
     [0077] In short, the portable data storage device  1  having the wireless communications function according to this modification can automatically continue data transfer (data writing) from the interrupted point, if communications connection is resumed after the data transfer (data writing) has been interrupted due to deterioration of a communications state between the device  1  and the information device  2  which the device  1  communicates with. Therefore, it is possible to effectively use the data recorded on the disk storage medium of the HDD  10  before interruption of the writing operation, without wasting it.  
     [0078] Further, when the wave reception state becomes satisfactory and wireless communications connection with the information device  2  being a data transmitting source is resumed, the user can automatically continue a writing operation to record data following the existing data, without performing complicated and troublesome operations.  
     [0079] Although a storage medium in this embodiment is assumed to be the HDD  10  using a disk storage medium, it is not limited to it, but may be a magnetic optical disk drive using a magnetic optical disk, or a flash memory using a flash EEPROM. Further, although the alarm device  17  is assumed to be a device which give an alarm to the user, it is not limited to it, but may be a device which displays a warning message on an LCD (liquid crystal display).  
     [0080] Furthermore, generally the device  1  is to be applied to a portable external storage unit such as a card-shaped memory.  
     [0081] As described above in detail, according to the above embodiment, if a wave reception state of a portable data storage device having a wireless data communications function has become poor, the device stops writing into a storage medium. Further, when a wireless communications connection has been resumed by restoration of the satisfactory wave reception state, it is possible to automatically continue the writing operation from data following the data recorded before interruption of the writing operation.  
     [0082] 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.