United States Patent
`Ohkubo et al.
`
`[19]
`
`[11] Patent Number:
`
`4,593,324
`
`[45] Date of Patent:
`
`Jun. 3, 1986
`
`4,386,416
`
`5/1983 Giltner et al.
`
`..................... .. 364/900
`
`OTHER PUBLICATIONS
`
`CCITT, Yellow Book, vol. VII—Fascicle VII.2, Tele-
`graph and Telematic Services, Terminal Equipment,
`Nov. 1980, pp. 222-235.
`Computer Storage Systems and Technology, Richard
`E. Matick, @1977, J. Wiley & Sons, pp. 540-546.
`Microcomputer Architecture and Programming, John
`F. Wakerly, ©1981, J. Wiley & Sons, pp. 340-344.
`
`Primary Examiner—Gareth D. Shaw
`‘
`Assistant Examz'ner—John G. Mills
`Attorney, Agent, or Firm—Sughrue, Mion, Zinn,
`Macpeak and Seas
`
`[57]
`
`ABSTRACT
`
`An image data storing device according to the inven-
`tion includes a data compression/expansion device be-
`tween the main memory of a CPU and an auxiliary
`memory device, such that image data are transmitted
`between the main memory and the data compression-
`/expansion device, while data which are obtained by
`compressing the image data are transmitted between the
`data compression/expansion device and the auxiliary
`memory device.
`
`3 Claims, 2 Drawing Figures
`
`[54]
`
`[75]
`
`IMAGE DATA STORING DEVICE
`
`Inventors: Tetsuo Ohkubo; Hiroyuki Kataoka,
`both of Kanagawa, Japan
`
`[73] Assignee:
`
`Fuji Xerox Co., Ltd., Tokyo, Japan
`
`[21] App]. No.: 780,241
`
`[22] Filed:
`
`Sep. 26, 1985
`
`Related U.S. Application Data
`
`[63]
`
`Continuation of Ser. No. 368,236, Apr. 13, 1982, aban-
`doned.
`
`Foreign Application Priority Data
`[30]
`Apr. 14, 1931 [JP]
`Japan .................................. 56-55110
`
`H04M 1/00; G06F 9/00
`Int. Cl.‘
`[51]
`
`[52] U.S. Cl. ........................................... .. 358/261
`[58] Field of Search ............... .. 364/200, 900; 358/261
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`................. .. 364/200
`9/1958 Nettleton et al.
`2,853,698
`2/1965 Foin et al.
`......... ..
`364/200
`3,168,723
`8/1971 Jackson et al.
`..
`.. 364/900
`3,599,178
`5/1977 Fort et al.
`364/900
`4,021,649
`4,232,375 11/1980 Paugstat et al.
`364/900
`4,376,933
`3/1983 Saran et al.
`.. 364/900
`4,382,286
`5/1983 Mitchell et al. .................‘.’... 364/900
`
`
`
`.
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`Oracle 1110
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`Oracle 1 1 10
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`

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` U.S. Patent
`
`‘Jun. 3,1986
`
` 4,593,324
`
`F/C‘9.
`
`7
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`PRIOR ART
`
`

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`4,593,324
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`2
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`IMAGE DATA STORING DEVICE
`
`This application is a continuation of Ser. No. 368,236
`filed Apr. 13, 1982, which is now abandoned.
`BACKGROUND OF THE INVENTION
`
`5
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`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a block diagram of a conventional image
`data storage system; and
`FIG. 2 is a block diagram illustrating one example of
`an image data storage device according to this inven-
`tion.
`_
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`
`FIG. 2 is a block diagram showing one example of an
`image data memory device according to the invention.
`In FIG. 2 reference numerals 1, 3, 4 and 5 designate
`those items designated by the same reference numerals
`in FIG. 1; 6, a data compression/expansion device; 7
`and 8, FIFO (first-in first-out) memories; 9 and 10, con-
`necting lines; 11, a magnetic disc control device; 12, a
`magnetic disc; and 13, an auxiliary memory device. The
`auxiliary memory device 13 is made up of the FIFO
`memories 7 and 8, the magnetic disc control device 11
`and the magnetic disc 12.
`In the image processing device thus arranged, the
`main memory 5 has a memory capacity of 2 M bytes and
`has stored therein binary image data obtained by read-
`ing data from a sheet of “B4” size in 1/ 12 mm units. The
`main memory 5 is the main memory of the CPU 4 and
`is accessed by the data compression/expansion device 6
`according to a conventional direct memory access sys-
`tem.
`
`When an instruction for storing binary image data in
`the magnetic disc is issued to the data compression/ex-
`pansion device 6 and the magnetic disc control device
`11 by the CPU (according to a conventional method
`(not illustrated)), the data compression/expansion de-
`vice 6 reads image data out of the main memory 5 suc-
`cessively. The image data thus read are compressed by
`one-dimensional run length coding, and are then applied
`to the FIFO memory 7. The FIFO memory 7 has a
`capacity of 11 bits. When the FIFO memory 7 receives 11
`bits of data from the data compression/expansion de-
`vice 6,
`it sends a “FIFO Full 1” signal (hereinafter
`referred to as “an FF 1 signal”) to the data compression-
`/expansion device 6 through the connecting line 9, so
`that data transfer and data compression are suspended.
`On the other hand, similar to the operation of a com-
`mercially available magnetic disc control device, the
`magnetic disc control device 11 carries out format con-
`trol and CRC check data formation. The magnetic disc
`control device 11 is instructed to store the image data
`by the CPU 4 as was described above. Therefore, after
`moving the head according to the cylinder address and
`track address in the instruction, the magnetic disc con-
`trol device 11 fetches the data from the FIFO memory
`7 for storage in the magnetic disc 12. Upon the start of
`this operation, the FF 1 signal becomes inactive, be-
`cause the data has been taken out of the FIFO memory
`7. Therefore, the data compression/expansion device 6
`again carries out data transfer to the FIFO memory 7
`and data compression.
`An ordinary image is compressed by 0.1 to 0.3 by
`one-dimensional run length coding. In the case where
`an average transfer rate in storing compressed data in
`the magnetic disc 12 is 8 M bits/sec, the number of
`picture elements per line of an image is m bits and the
`standard compression rate is 0.2, the one-line minimum
`transfer time T is 0.2 m/8 microseconds.
`Where the access unit of the data compression/ex-
`pansion device is 16 bits and the main memory 5 has a
`
`This invention relates to an image data storing device
`in which binary image data are stored in a memory
`means having a large capacity.
`FIG. 1 outlines a conventional image processing de-
`vice. In FIG. 1, reference numeral 1 designates an
`image input device; 2, a large capacity memory unit; 3,
`an image output device; 4, a CPU, and 5, the main mem-
`ory of the CPU 4. In this image processing device, an
`image is read as binary signals by the image input device
`1, and is stored in the large capacity memory unit 2
`through the main memory 5. Thereafter, in response to
`an instruction from the CPU, the binary signals are
`suitably processed, so that the image is outputted by the
`image output device 3.
`In order to read an image with high quality with the
`image input device, each picture element shoud be
`about 1/12 mm in size. For instance, if the entire area of
`a sheet of “B4” size (364 mmX257 mm) is read with
`1/ 12 mm? per picture element, then the amount of data
`on one sheet is about 1.7 M bytes.
`In general, a magnetic disc is employed as the large «
`capacity memory unit Z. In the case where an 8-inch
`commercially available disc is employed as the large
`capacity memory unit 2, the memory capacity is about
`40 M bytes at maximum. Therefore, if the conventional
`image processing device is used to store an image of the
`aforementioned “B4” sized sheets, the magnetic disc
`can store data for no more than twenty-three such
`sheets.
`Recently, a laser scan type image printer has been
`developed for use as the image output device 3. That is,
`the image output device may operate at a high speed,
`and some such image output devices have an average
`video rate of about 20 M bits/sec. On the other hand,
`the data transfer rate between the large capacity mem-
`ory unit 2 and the main memory 5 is of the order of 7 M
`to 8 M bits/sec. Therefore, the data transfer rate be-
`tween the large capacity memory unit 2 and the main
`memory 5 becomes an obstruction or bottleneck in the
`operation of outputting the image stored in the large
`capacity memory unit 2 from the image output device 3.
`Thus, the conventional image processing device is in-
`sufficient in systematic capability. This is another draw-
`back of the conventional device.
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`SUMMARY OF THE INVENTION
`
`An object of this invention is to provide an image
`data storing device in which the above-described draw-
`backs accompanying the conventional image processing
`device have been eliminated, and wherein a large
`amount of image data can be stored, and the image data
`inputted and outputted at high speed.
`An image data storing device according to the inven-
`tion includes a data compression/expansion device be-
`tween the main memory of a CPU and an auxiliary
`memory device, such that image data are transmitted
`between the main memory and the data compression-
`/expansion device, while data which are obtained by
`compressing the image data are transmitted between the
`data compression/expansion device and the auxiliary
`memory device.
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`cycle time of 250 ns, the transfer rate between the main
`memory 5 and the data compression/expansion data 6 is
`40 M bits/sec. Therefore, if the read data are applied to
`the FIFO memory 7 after being compressed by 0.2 by
`the data compression/expansion device 6,
`then the
`transfer rate between the device 6 and the memory 7 is
`40><0.2=8 M bits/sec, which is equal to the aforemen-
`tioned average transfer rate. When the compression rate
`is increased to higher than 0.2, for instance to 0.1, then
`the amount of data is further decreased. In this case, a
`fill code may be inserted until the compression rate
`reaches 0.2, according to the one-dimensional mm
`length coding system, and therefore the amount of the
`useless portion is somewhat increased in the image data
`on the disc; however, the problem in the control can be
`solved thereby.
`In the case where the compression rate is of the order
`of 0.3, the amount of data applied to the FIFO memory
`7 is increased, that is, more data than that which can be
`transferred to the disc 12 from the FIFO memory 7 are
`inputted. Therefore, the FF 1 signal is issued, so that
`data transfer to the FIFO memory 7 and data compres-
`sion are suspended. Thus, there is no problem in the
`control.
`As is apparent from the above description, the image
`data in the main memory 5 are stored in the magnetic
`disc, after being compressed at a maximum compression
`rate of 0.2 by the data compression/expansion device 6.
`Therefore, the amount of image data stored in this case
`may be five times that in the case where no compression
`is effected. Furthermore, the image data transfer rate
`between the main memory 5 and the data compression-
`/expansion device 6 is greatly increased, i.e. to 40 M
`bits/sec at maximum.
`In the case when the compressed image data stored in
`the magnetic disc 12 are loaded in the main memory 5,
`the image data storing device operates as follows:
`When a read instruction is applied to the disc control
`device 11 and the data compression/expansion device 6
`by the CPU 4, the compressed data are read out of the
`magnetic disc 12 by the disc control device 11, and are
`written in the FIFO memory 8.
`When the data have been written in the FIFO mem-
`ory 8, a “FIFO EMPTY” signal which is otherwise
`applied to the data compression/expansion device
`through the connecting line 10 from the FIFO memory
`8 is made inactive. Upon detection of this change, the
`data compression/expansion device 6 extracts data from
`the FIFO memory 8. In the device 6, the image data
`compressed by one-dimensional coding are expanded
`into the original image data. The image data thus pro-
`cessed are written in the main memory 5 according to
`the direction access system. Similarly as when the data
`is read from the main memory, the data can be written
`at a data transfer rate of about 40 M bits/sec at maxi-
`mum. The data compressed at the maximum rate of 0.2
`is restored into the original image data at a sufficiently
`high speed.
`In the above-described embodiment, the data com-
`pression/expansion device 6 employs a one-dimensional
`run length coding system; however, this system may be
`replaced by a two-dimensional coding system (G III
`standard) employed as a standard system in CCITT, or
`by other systems having data compression and expan-
`sion functions.
`In this embodiment, the standard compression rate is
`0.2; however, it should be noted that the standard com-
`pression rate is determined from the employed coding
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`4,593,324
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`system and the ratio of the data transfer rate between
`the main memory and the data compression/expansion
`device to the data transfer rate between the data com-
`pression/expansion device and the disc. The standard
`compression rate should be set to an optimum value,
`taking these two factors into account.
`As was described above, according to the invention,
`a data compression/expansion device is provided be-
`tween the main memory of the CPU and the auxiliary
`memory. Therefore, the invention has an effect such
`that the image data transfer rate between the main mem-
`ory and the auxiliary memory can be increased, and a
`large amount of image data can be stored in the auxil-
`iary memory.
`What is claimed is:
`1. An image data storage system comprising a central
`processing unit connected to a main memory and con-
`nected to input/output devices, including:
`an auxiliary data storage system having a magnetic
`storage disc, read/write control means for said
`magnetic storage disc and a disc controller;
`a data compression/expansion device provided be-
`tween said main memory and said auxiliary mem-
`ory device, which compresses data by means of a
`one dimension run length coding technique with
`the compression rate of said compression/expan-
`sion device being selected according to the ratio
`between the data transfer rate from said memory to
`said compression/expansion device and the data
`transfer rate from said compression/expansion de-
`vice to the storage media of said magnetic storage
`disc;
`said auxiliary memory device comprising a pair of
`FIFO memories for transfer of data in either direc-
`tion between said magnetic storage disc and said
`compression/expansion device;
`wherein image data are transmitted between said
`main memory and said data compression/expan-
`sion device at the same time that compressed data
`which are obtained by compressing said image data
`are transmitted between said data compression/ex-
`pansion device and said auxiliary memory device.
`2. An image data storage device, comprising;
`a CPU having a main memory, an auxiliary memory
`device including an auxiliary data storage system
`having a magnetic storage disc, read/Write control
`means for said magnetic storage disc and a disc
`controller, and a data compression/expansion de-
`vice provided between said main memory and said
`auxiliary device for compressing data by one-
`dimensional run length coding, wherein image data
`are transmitted between said main memory and
`said data compression/expansion device, while
`data which are obtained by compressing said image
`data are transmitted between said data compres-
`sion/expansion device and said auxiliary memory
`device, said auxiliary memory device, said auxil-
`iary memory device comprising a pair FIFO mem-
`ories for transfer of data in either direction between
`said magnetic storage disc and said compression-
`/expansion device.
`3. An image data storage device, comprising;
`a CPU having a main memory, an auxiliary memory
`device including an auxiliary data storage system
`having a magnetic storage disc, read/write control
`means for said magnetic storage disc and a disc
`controller, and a data compression/expansion de-
`vice provided between said main memory and said
`
`

`
`5
`auxiliary device for compressing data by two-di-
`mensional run length coding, wherein image data
`are transmitted between said main memory and
`said data compression/expansion device, while
`data which are obtained by compressing said image
`data are transmitted between said data compres-
`sion/expansion device and said auxiliary memory
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`4,593,324
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`device, said auxiliary memory device, said auxil-
`— iary memory device comprising a pair FIFO mem-
`ories for transfer of data in either direction between
`
`said magnetic storage disc and said compression-
`/expansion device.*
`
`It
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`it
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