The present invention relates to a communication system, a storage device, and a control device for externally accessing a storage area storing file data, and particularly to a communication system, a storage device, and a control device for accessing file data handled in a file unit in a storage area of the storage device connected via a radio communication section.
More particularly, the present invention relates to a communication system, a storage device, and a control device that do not increase a process load on a storage device side at a time of access to file data, and particularly to a communication system, a storage device, and a control device that require addition of fewer functions necessary for access to file data on a storage device side.
With recent technological innovation, various information devices handling computer files of various media such as text, images, audio and the like have been developed and commercially available, the information devices including a personal computer, a PDA (Personal Digital Assistant), a digital camera, a portable media player and the like. Many of the information devices of this type have a connector or an interface for detachably mounting a cartridge type memory device such as a built-in memory, a hard disk, a memory stick, a memory card, a USB (Universal Serial Bus) memory or the like.
For example, a digital camera encodes a picked-up image into a predetermined file format such as JPEG (Joint Photographic Experts Group) or MPEG (Moving Picture Experts Group), and then stores the image on a memory card. In such a case, many images, which cannot be stored in a low-capacity built-in memory, can be stored. When the memory becomes full, a new capacity for storing picked-up images can be obtained by replacing the memory card.
In addition, files of images captured on the digital camera can be transferred to another information device such as a personal computer or the like to be subjected to image processing such as image quality adjustment, re-encoding and the like, and the images can be managed in the form of a database, an album or the like. Alternatively, an image file is transferred to a printer and printed out so that the image file can be appreciated as a photograph.
In a common method for transferring images and other data on the memory card between devices, the memory card is extracted and then loaded into a device to which to transfer the data. Alternatively, data transmission from the device in which the memory card is loaded to the device to which to transfer the data can be made via a wire or wireless transmission line using a wired interface or a wireless interface. The latter radio communication, in particular, eliminates a need for the operation of reattaching a connector and routing a cable each time data is transmitted, thus providing great convenience.
FIG. 21 shows an example of image transmission by radio. In the figure, a digital camera is assumed as a mobile device. The digital camera stores picked-up images as image data in a built-in memory or an external memory card. In radio transmission, the digital camera reads desired image data from the built-in memory or the external memory card, and transfers the image data to image reproducing devices such as a personal computer, a television set, a printer and the like via a wireless interface. Of course, a wireless interface module is provided as an adapter in each of the receiving devices such as the personal computer, the television set, the printer and the like. After the transfer of the image data via a radio transmission line, the image data is displayed and stored by the personal computer, displayed on the screen of the television set, and printed out by the printer.
As described above, for radio transmission from the digital camera, a wireless interface module needs to be provided also on the transmission source device side. A device without a built-in wireless interface needs to be provided with a wireless interface by an external adapter. On the other hand, when a cartridge type storage device itself such as a memory stick or the like has a wireless interface module, the digital camera does not need to have a wireless interface module. In addition, without being attached to a data processing device proper such as the digital camera or the like, the memory stick can singly transmit data to a target device such as the personal computer, the printer or the like by radio.
An external memory medium having a radio communication function, for example, is proposed, for example, in Japanese Patent Laid-Open No. 2001-77878. This external memory medium includes a wire communication section for sending and receiving data to and from a host device into which the external memory medium is loaded via a physical connection section and a short-distance radio communication section for transmitting and receiving data to and from an external communication network via a short-distance radio communication network such as a Bluetooth communication network or the like. Hence, the host device having the external memory medium loaded therein can transmit and receive data to and from the communication network by driving the short-distance radio communication section within the memory medium.
FIG. 22 is a diagram showing a common example of configuration of an electronic device to which a storage device such as a hard disk, a flash memory or the like is applied. The electronic device 4 shown in FIG. 22 includes a storage unit 43 and a function controlling unit 41.
The storage unit 43 includes a storage device 431 formed by a storage medium such as a magnetic disk, a memory element or the like and a storage device controlling functional unit 432 for making physical access to the storage medium.
The storage device 431 corresponds to a physical storage area itself. The storage device controlling functional unit 432 is a controller that performs control on the storage device 431 for faulty block management, error detection, error correction and the like. The storage unit 43 is controlled by the device controlling unit 41 via a predetermined electric interface 42 such as a processor bus.
The device controlling unit 41 is a controller for centralized control of operation of the device as a whole, which controller is provided by a microcontroller or a CPU (Central Processing Unit). The device controlling unit 41 has a file controlling unit 411 and a data controlling unit 412. The device controlling unit 41 reads and writes file data from and to the storage unit 43.
The data controlling unit 412 is a driver controlling unit that reads and writes data in a minimum physical access unit (generally 512 bytes) referred to as a “sector” or a “page” from and to the storage unit 43.
The file controlling unit 411 is generally referred to as a “file system,” and reads and writes file data, that is, data in a file unit from and to the storage unit 43 via the data controlling unit 412.
In related art, when the electronic device shares the data of the storage device with another device, a file system function and a data interface function (USB, IrDA, a wireless LAN or the like) are generally added to each device. FIG. 23 shows an example of configuration of the electronic device in such a case. The electronic device shown in FIG. 23 additionally includes an interface functional unit 44, and has an interface controlling unit 413 for driver control of the interface functional unit 44 in the device controlling unit 41.
However, a device configuration as shown in FIG. 23 has problems of an increase in a process load on the device controlling unit 41 and an increase in power consumption due to the addition of the data interface functional unit. In addition, a load of driver development and the like for function introduction is imposed on a developer.