CONTROL UNIT OF FLASH MEMORY AND
FACSIMILE MACHINE USING SUCH
CONTROL UNIT
BACKGROUND OF THE INVENTION 5
(1) Field of the Invention
The present invention relates to a control unit of a flash memory and a facsimile machine, such as a portable facsimile machine, having a flash memory for storing image io data and the control unit of the flash memory.
(2) Description of the Related Art
A picture processor has been proposed in Japanese Laid Open Patent Application No. 3-179972 (a first reference). In this picture processor, when there is no idle area to record 15 picture data in a memory, a recording operation is interrupted and the processor waits for protection of therecording operation to be canceled. When the protection is canceled, the recording operation automatically restarts. As a result, picture data is recorded in the idle area of the memory 20 so that continuity of storage of picture data is maintained.
A facsimile machine has been also proposed in Japanese Laid Open Patent Application No. 3-177158 (a second reference). This facsimile machine is provided with a memory circuit for storing image data.
A flash memory, which is one type of rewritable nonvolatile memory, is expected to be used as a large-capacity memory. A flash memory can be used, for example, as a memory for storing image data in a facsimile machine as 30 disclosed in the second reference. In this case, the writing control of the flash memory can be performed in a manner, for example, as disclosed in the first reference.
However, if the writing control of the flash memory is performed so that image data is unmethodically stored in the 35 idle area of the flash memory as disclosed in the first reference, the following disadvantages occur.
The number of rewrites (the rewritable number) of the flash memory generally is limited in a range between 10 thousands and 100 thousands. Thus, in a case where the flash 40 memory is used as an image memory of the facsimile machine, the above limitation of the rewritable number of the flash memory must be considered. If the increase of the rewritable number is concentrated on only a part of the recording area in the flash memory, the part of the recording 45 area becomes unusable sooner than other parts thereof. That is, the flash memory cannot be used for a long time under the maximum memory size. In this case, the flash memory in which the image data is to be stored overflows more quickly.
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SUMMARY OF THE INVENTION
Accordingly, a general object of the present invention is to provide a novel and useful control unit of a flash memory and a facsimile machine using such in which the disadvantages of the aforementioned prior art are eliminated.
A more specific object of the present invention is to provide a control unit capable of rewriting information in a flash memory under a condition in which a recording area of the flash memory is usually uniformly used. 60
The above objects of the present invention are achieved by a control unit for controlling a flash memory in which a recording area is divided into a plurality of blocks, the control unit comprising: storage means for storing management information regarding history that blocks have been 65 used for recording information, the management information being updated every time each block has been used; and
selecting means for selecting, with reference to the management information stored in the storage means, a block in which information is to be written from among the plurality of blocks in the recording area of the flash memory so that all the blocks of the flash memory are uniformly used, wherein the information is recorded in the block selected by the selecting means in the flash memory.
Another object of the present invention is to provide a facsimile machine using the above control unit of the flash memory.
The above objects of the present invention are achieved by a facsimile machine comprising: a flash memory for temporally recording image data to be transmitted and/or received, the flash memory having a recording area divided into a plurality of blocks; and a control unit for controlling the flash memory so that the image data is recorded in a block of the flash memory, the control unit comprising: storage means for storing management information regarding history that blocks have been used for recording image data, the management information being updated every time each block has been used; and selecting means for selecting, with reference to the management information stored in the storage means, a block in which image data is to be written from among the plurality of blocks in the recording area of the flash memory so that all the blocks of the flash memory are uniformly used, wherein the image data is recorded in the block selected by the selecting means in the flash memory.
According to the present invention, a block in which information is to be written is selected from among the plurality of blocks of the flash memory so that all the blocks are uniformly used. Thus, information can be recorded in a flash memory under a condition in which a recording area of the flash memory is usually uniformly used.
Additional objects, features and advantages of the present invention will become apparent from the following detailed description when read in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram illustrating a facsimile machine according to a first embodiment of the present invention.
FIG. 2 is a diagram illustrating a recording area of a flash memory, shown in FIG. 1, in which a rewriting number of each block is controlled.
FIG. 3 is a flow chart illustrating a writing operation of the flash memory shown in FIG. 1.
FIG. 4 is a flow chart illustrating a reading operation of the flash memory shown in FIG. 1.
FIG. 5 is a block diagram illustrating a facsimile machine according to a second embodiment of the present invention.
FIG. 6 is a flow chart illustrating a recording area of the flash memory, shown in FIG. 5, in which a rewriting number of each block is controlled.
FIG. 7 is a flow chart illustrating an operation of the control unit shown in FIG. 5.
DESCRIPTION OF THE PREFERRED
EMBODIMENTS
A description will now be given, with reference to FIGS. 1-4, of a first embodiment of the present invention.
A facsimile machine according to the first embodiment of the present invention is formed as shown in FIG. 1. Referring to FIG. 1, the facsimile machine has an NCU (Network
