JPH0530368A - Image forming device - Google Patents

Abstract

(57) [Abstract] [Purpose] To realize the real-time processing of compression / decompression processing and the reliability of data processing, make the processing speed equal to that of the input / output device, and improve the copying efficiency. A compressor 102 that compresses image data obtained by scanning a document 101, and a memory unit 103 that stores the compressed data and the image data before compression.
And a decompressor 104 that decompresses the compressed data read from the memory unit 103, and an error detector 201 that detects an error in the compressor 102 and the decompressor 104. When the error is detected before completion, the image data before compression is adopted, and when the error is not detected, the compressed data is adopted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for inputting and outputting an image such as a digital copying machine, a facsimile machine, etc., which executes image data compression / decompression processing in real time, and performs an error check at that time. The present invention relates to an image forming apparatus that performs

[0002]

2. Description of the Related Art FIG. 20 is a block diagram showing a conventional processing flow of image data. In the figure, image data output from an image processor (IPU) 743 is temporarily stored in a memory device (MEM) 744. To be done. Then, when necessary, the memory device (MEM) 74
The stored data was taken out from No. 4 and output to the printer (PR). In addition, the image processor (IPU) 7
While outputting the image data output from 43, the data is stored in the memory device (MEM) 744 at the same time.
A method in which image data from a memory device (MEM) 744 is used for the copying process for the first and subsequent sheets is generally used. Further, in a conventional digital copying machine or the like, when image data is stored in a storage unit, data processing is executed using a compressor and an expander in order to reduce the data capacity.

Further, conventional techniques such as image data storage processing related to the present invention are as follows. First, a "digital copying machine" disclosed in Japanese Patent Laid-Open No. 63-146567 has an image data scanner for scanning an original and converting it into an electric signal, and a printer for outputting the electric signal as a hard copy. The copying machine is provided with means for adding and storing an external storage medium for storing image data converted into an electric signal, and comparing the image data capacity with the remaining amount of the storage medium, the image data capacity is determined by the remaining amount. When the image data is large, the image data is reduced and scaled and stored, and when the image data capacity is less than or equal to the remaining amount, the image data is stored as it is. In the process of inputting a specific number of image data to the storage medium as described above, if the image data amount exceeds the remaining capacity of the storage medium, a reduction process according to the remaining capacity is applied to the image data to obtain continuous image data. It is intended not to straddle a plurality of storage media.

Secondly, the "image reproducing apparatus" disclosed in Japanese Patent Laid-Open No. 1-231778 discloses a document by designating a desired image area on the original and a desired reproduction area on the recording material. An image in a desired area can be satisfactorily reproduced in a desired area on a recording material, and both a mode of preferentially reproducing an original image and a mode of preferentially reproducing a reproduction area of a recording material can be arbitrarily executed. Thus, processing suitable for desired editing can be performed.

Thirdly, the "image editing apparatus" disclosed in Japanese Examined Patent Publication No. 2-2346 discloses an image recording material using the image signals of two pages of the book opened from the reading means as they are. Instead of recording it on the upper side, the image signals for two pages corresponding to the images on the front and back pages of the book are read out from the first storage means for storing the image signals output from the reading means for a plurality of pages, and the second storage means is read out. Since the image is recorded on the same surface of the same recording material based on the image signals for two pages corresponding to the images on the front and back pages of the book stored in the storage unit and read from the second storage unit, On the same side of the same recording material, not the images of the two pages of the book that are opened, but the images of the front and back pages of the book are recorded, and the recording material with the image recording is folded in half. And by binding Copy image of the same sequence as seen took present can be reproduced.

[0006]

However, the conventional method as shown above has the following problems. Since the processing speed of the compressor and the decompressor changes depending on the content of the image data, there is a problem that some documents cannot perform real-time processing in synchronization with the speed of the reading device and the writing device. In addition, the problem that the processing speed does not follow the input / output device was solved by temporarily storing the raw data in the memory and then compressing it, but input → memory → compressor → memory → decompressor. Since the memory is used as a buffer such as → memory → output, the total processing speed is reduced, and the efficiency of the copying work is not improved.
In addition, even in the technologies disclosed in the above publications,
It cannot solve the above problems at all.

The present invention has been made in view of the above, and realizes real-time processing of compression / expansion processing and reliability of data processing, makes the processing speed equal to that of the input / output device, and improves the copy efficiency. The purpose is to plan.

[0008]

In order to achieve the above object, the present invention has a data compression means for compressing image data obtained by scanning an original, and a data compression means for compressing the data. Storage means for storing compressed data and image data before compression, data decompression means for decompressing the compressed data read from the storage means, and error detection for detecting an error in the data compression means and the data decompression means And an image forming apparatus that employs the image data before compression when the error detection unit detects an error by the time one scan of the document is completed, and adopts the compressed data when the error is not detected. Is provided.

When the error detecting means detects an error by the time one scan of the original is completed, the compressed data is canceled from the storage means, and when the error is not detected, the image data before the compression is deleted from the storage means. An image forming apparatus for canceling is provided.

Further, when each processing by the data compressing means and data decompressing means is completed by the time one scan of the original is completed, the image data before compression is canceled from the storing means, and when each processing is not finished, the storing is carried out. An image forming apparatus for canceling compressed data from a means is provided.

[0011]

In the image forming apparatus according to the present invention, the image data before compression is adopted when the error detecting means detects an error by the time one scan of the document is completed, and the compressed data when the error is not detected. To adopt.

Further, when the error detecting means detects an error by the time one scan of the original is completed, the compressed data is canceled from the storing means, and when the error is not detected, the image data before the compression is deleted from the storing means. cancel.

Further, when each processing by the data compression means and data expansion means is completed by the time one scan of the original is completed, the image data before compression is canceled from the storage means, and when each processing is not completed, the storage is performed. Uncompress the compressed data from the means.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram showing an outline of image data processing according to the present invention. In the figure, 101 is a document to be copied, 102 is a compressor (COMP) for compressing data, and 103 is a compressor (CO) in addition to actual data.
MP) a memory unit that stores the compressed data processed by 102, and a decompressor (E) that decompresses the data.
XP).

In the image data processing as described above, the image data output by scanning the original 101 with exposure is stored as raw data in one area (raw data area) of the memory unit 103. At the same time, the data compressed by the compressor (COMP) 102 is stored in another compressed data area. Memory unit 1
The compressed data stored in 03 is simultaneously output to the decompressor (EXP) 104 by the memory management unit (MMU) 1801 (see FIG. 19). Expander (EXP) 10
In 4, the data decompression process is executed at the data speed synchronized with the printer device (not shown).

FIG. 2 is a block diagram showing an example of a structure that enables error detection processing in comparison with FIG. In the figure, 2
01 is a compressor (COMP) 102 and an expander (EXP) 1
The error detector monitors the error signal 04.

In the above configuration, the error detector 201
Is a compressor (COMP) 102 and an expander (EXP) 104
The error signal of the memory management unit (MM) is immediately monitored when the real-time data processing cannot be performed.
U) An area cancellation signal is output to 1801. Further, the memory management unit (MMU) 1801 cancels the raw data stored in the memory unit 103 when there is no cancellation instruction from the error detector 201 when one exposure scanning of the original 101 is completed. Then, when the next original 101 is exposed and scanned, a new raw data area and a new compressed data area are set in the memory unit 103, and the above operation is repeated.

In addition, the configuration of FIG. 1 and FIG.
This is a memory system capable of saving compressed data when the compression / expansion processing of 01 image data can be processed in real time, and saving raw data when it cannot be processed in real time. In addition, in the above embodiment, 1 of the original 101 is used.
Although the test is performed on the image data of the page, the same test is performed on the image data of one main scan, and it is possible to mix the raw data and the compressed data on one page. In this case, the memory management unit (M
The MU) 1801 sorting table (which area is raw data, compressed data, and the order of data, etc., must be created at the same time), but the above method is the most efficient. Memory can be used.

FIG. 3 is an explanatory view showing the structure of the digital copying machine according to the present invention. As shown in the figure, the present digital copying machine comprises a copying machine main body 301, an automatic document feeder (ADF) 302, a sorter 303, and a double-sided reversing device (DPX) 304.

Referring to FIG. 3, the detailed structure of the above unit will be described below. The copying machine main body 301 includes a scanner unit 305, an optical writing unit 306, a photoconductor and an image forming unit 307 around the photoconductor, a developing unit 308, a paper feeding unit 309, and the like.

First, the structure of the scanner unit 305 will be described. Reference numeral 310 is a contact glass made of transparent glass on which an original (not shown) is placed, 311 is an exposure lamp using a fluorescent lamp or a halogen lamp for illuminating the original on the contact glass 310, and 312 is the light of the exposure lamp 311. A reflection plate 313 that reflects the original document side includes a first reflection mirror 313 that refracts reflected light of the original document and guides it to a second reflection mirror 314.
Reference numeral 14 denotes a second reflecting mirror that guides the reflected light from the first reflecting mirror 313 to the next third reflecting mirror 315, and 315 receives the reflected light from the second reflecting mirror 314 and the color filter 316.
A third mirror 316 which guides the light to a color filter 316 is a color filter which transmits light of a required color, 317 is an image forming lens for forming an image of the reflected light on the next CCD image pickup device 318, and 318 photoelectrically converts the reflected light of the document. The CCD image sensor 319, which converts the electric signal, performs predetermined image processing (shading correction,
The image processing board performs MTF correction, binarization processing, multi-value processing, gradation processing, scaling processing, image editing processing, and the like.

Further, in the above, the exposure lamp 311,
The reflection plate 312 and the first reflection mirror 313 are a first scanner that is integrally configured and moves at a constant speed, and the second reflection mirror 314 and the third reflection mirror 315 are called a second scanner. It is configured to move following the first scanner at a speed of / 2.

The scanner unit 305 configured as described above
Is configured to optically scan a document set on the contact glass 310 by the first scanner and the second scanner, and reflect the reflected light from the first reflection mirror 312 to the third reflection mirror 31.
5, the light is transmitted through the color filter 316 and the imaging lens 31
At 7, the image is formed on the CCD image pickup device 318. The reflected light imaged on the CCD image pickup device 318 is converted into an electric signal having an analog value and further converted into a digital image signal by an A / D converter (not shown). Next, after a series of image processing is executed by the image processing board 319, a digital image signal is output.

Next, the structure of the optical writing section 306 shown in FIGS. 3, 4 and 5 will be described. FIG. 4 shows the optical writing unit 306.
Is shown in a plan view, and FIG. 5 is a side view of the optical writing section 306. In FIG. 3, reference numeral 320 denotes a polygonal mirror which is provided on the side surface of a regular polyhedron and rotates at a high speed to scan a laser beam. 321 denotes a polygon motor serving as a drive source for rotating the polygon mirror 320 at a high speed. An fθ lens 323 for converting and correcting a laser beam polarized at an equal angle pitch so that the surface of the photosensitive drum 307 is scanned linearly at an equal linear pitch. Reference numeral 323 denotes a laser beam passed through the fθ lens 322.
The reflection mirror 324 that leads to 07 is dust-proof glass for preventing foreign matter from entering the optical writing unit 306.

In FIG. 4, 401 is a semiconductor laser that oscillates a laser beam having an emission wavelength of about 780 nm, and 4
Reference numeral 02 designates a collimate lens for collimating a laser beam emitted from the semiconductor laser 401 into a parallel beam, 403 an aperture for shaping the laser beam into a predetermined size, 4
Reference numeral 04 denotes a first cylinder lens that compresses the laser beam that has passed through the aperture 403 in the sub-scanning direction, and 405 denotes a synchronization detection mirror that receives the laser beam outside the image area that has passed through the fθ lens 322 and guides it to the synchronization detection light input unit 406. Reference numerals 406 denote sync detection light input units that input the laser beam guided by the sync detection mirror 405 and guide the laser beam to a sync detector (not shown).

The operation of the optical writing section 306 constructed as above will be described. The semiconductor laser 401 oscillates a laser beam by modulating it according to an image signal output by being image-processed by the image processing board 319. The laser beam having this certain angle is collimated by the collimator lens 402.
Is converted into a parallel light flux by, and further, the beam is shaped by the aperture 403, is compressed in the sub-scanning direction by the first cylinder lens 404, and is irradiated onto the polygon mirror 320.

After that, the laser beam applied to the polygon mirror 320 which has already been rotated at a predetermined speed by the polygon motor 321 is conformally scanned as shown in FIG.
After being corrected by the fθ lens 322 to have an equal linear pitch on the photoconductor drum 307, the photoconductor drum 307 is exposed and irradiated by the reflection mirror 323. At this time, the synchronization detection mirror 405 receives the laser beam outside the image area, guides it to the synchronization detection light input unit 406, detects the writing start position in the main scanning direction, and writes in the main scanning direction based on this synchronization detection. Is done.

Next, each structure for forming an electrostatic latent image will be described centering on the photosensitive drum 307 of FIG. A photoconductor layer is formed on the surface of the photoconductor drum 307. For example, an organic photoconductor (OPC) of a photoconductor layer having a sensitivity characteristic corresponding to an emission wavelength of 780 nm of the semiconductor laser 401, α-Si, Se. Among -Te and the like, an organic photoconductor (OPC) is adopted in this embodiment. Also,
The image forming process of this embodiment employs a negative / positive (N / P) process in which light is applied to the image portion. In FIG.
In 325, the surface of the photosensitive drum 307 is uniformly corona-discharged,
This is a charger that performs a (-) pole charging process, and employs a scorotron system having a grid on the side of the photoconductor drum 307.

In the structure described above, the surface of the photosensitive drum 307 is charged by the charging charger 325, and then the laser beam is irradiated to the surface of the photosensitive drum 307 by the optical writing unit 306, so that the irradiated portion. The potential of is decreased. As a result, the ground potential on the surface of the photosensitive drum 307 is -750 to -800 V, and the image potential is -500.
The value is about V, and an electrostatic latent image corresponding to image information is formed on the surface of the photosensitive drum 307.

Next, the structure of the developing section 308 will be described. In this embodiment, the first developing device 326 for black toner and the second developing device 327 for color toner are connected to the developing unit 3.
08 is configured. Reference numeral 328 is a black toner cartridge for containing and supplying black toner, and 329 is a color toner cartridge for containing and supplying color toner.

The developing unit 308 configured as described above is
The developing roller of the first developing device 326 and the second developing device 32 are applied to the electrostatic latent image formed on the surface of the photoconductor drum 307.
Bias voltage of −500 to −600 V is applied to the developing roller of No. 7 to apply (−) charged toner to the photosensitive drum 307.
It is made visible by attaching it to the electrostatic latent image on the surface. In the case of color copying, during the development of one color, the development is selectively performed by setting the main pole position of the developing roller of the developing device of the other color. As a result, the color information of the original is read by switching the color filter 316 in the scanner unit 305, and the multifunctional color copying and the color image editing can be performed by the combination of the multiple transfer by the paper conveyance and the double-sided copying function.
Further, development of three or more colors can be performed by a method of arranging three or more developing devices around the photosensitive drum 307, a revolver method of rotating and switching three or more developing devices, and the like.

In FIG. 3, 330 is a transfer charger for transferring the visible image on the photosensitive drum 307 to the conveyed recording paper, and 331 is integrally formed with the transfer charger 330, and is in close contact with the photosensitive drum 307. This is a separation charger that separates the recording paper by AC neutralization. Three
Reference numeral 32 denotes a cleaning blade that removes residual toner after the transfer processing on the surface of the photoconductor drum 307, 333 a recovery tank that collects and stores the waste toner removed by the cleaning blade 332, and 334 a residual charge of the photoconductor drum 307. A static elimination lamp 335 that is removed by light irradiation is a separation claw that comes into contact with the photoconductor drum 307 with a small force to assist separation of the recording paper.

Reference numeral 336 is a density sensor using a photosensor consisting of a light emitting element and a light receiving element, and a predetermined latent image pattern is formed on the photosensitive drum 307 by the optical writing section 306, and this latent image pattern is formed. After development, the reflection density is read by a photo sensor. This is to judge the density of an image from the ratio of the reflectance of the pattern portion after the development processing and the reflectance of the photoconductor drum 307 other than the pattern portion, and when it is light, a toner replenishment signal is output. Further, when the predetermined density is not reached within a certain time after replenishment, it is determined that the toner is out, and a detection signal to that effect is output.

Further, the paper feeding unit 309 in FIG. 3 will be described. Reference numerals 337a, 337b, and 337c denote paper feed cassettes 338a for accommodating and setting recording papers of different sizes.
338b, 338c are sheet feeding rollers for feeding the recording sheets one by one, 339 is a registration roller for conveying the fed recording sheets to a transfer portion at a predetermined timing, and 340 is a recording sheet after transfer / separation. A conveyor belt 341, a fixing roller 341 which has a built-in heater and is heated to a predetermined temperature,
Is a pressure roller which is arranged so as to face the fixing roller 341 so as to have a predetermined pressure.

Photoreceptor drum 30 constructed as described above
The operations of the image forming unit and the paper feeding unit 309 around the periphery will be described. The copying machine main body 301 includes paper feed cassettes 337a, 33
7b and 337c are detachably loaded. Paper feed roller 3
The recording paper fed by 38a, 338b, 338c is conveyed by the registration roller 339 to the photosensitive drum 307 at a predetermined timing.

The photoconductor drum 307 is driven to rotate clockwise, and at that time, the toner image formed on the photoconductor drum 307 is transferred by the transfer charger 330 onto the recording paper conveyed to the photoconductor drum 307. The recording paper that has been transferred (transfer processing) and is in close contact with the photosensitive drum 307 is electrostatically separated by the separation charger 331. After that, the recording paper is conveyed to the nip between the fixing roller 341 and the pressure roller 342 by the conveyance belt 340, so that the unfixed toner on the recording paper is fixed (fixing process). On the other hand, the photosensitive drum 307 after the transfer processing is the cleaning blade 3
The residual toner is removed by 32, and the static elimination lamp 3
The residual charge is removed by 34, and a standby state is set up for the next copying process.

In FIG. 3, 343 is a switching claw for switching the conveying direction of the recording paper after the fixing process, 344 is a switching claw for allowing the recording paper to enter the double-sided reversing device (DPX) 304, and 345 is a re-feed unit 346. A switching claw for admitting the recording paper to the side, 346 is a re-feeding unit for re-feeding the recorded recording paper, 347 is a tray for reversing the recording paper,
A conveyance roller 348 conveys the recording paper to the tray 347 and then rotates in the reverse direction to re-feed the recording paper from the rear end.

A case where double-sided copying is performed in the above configuration will be described. The recording paper guided downward by the switching claw 343 is further guided downward by the switching claw 344, and is sent to the transport roller 348 by the next switching claw 345. The conveyance roller 348 conveys the recording paper onto the tray 347, and when the recording paper reaches the trailing end of the recording paper, the recording paper is fed again in the reverse direction, and is fed to the refeed portion 346 by switching the switching claw 345. After that, it is fed to the registration roller 339.

Next, the automatic document feeder (A) shown in FIG.
The configuration of the DF) 302 will be described. In the figure, 3
Reference numeral 49 is a document feed table on which a plurality of documents to be copied can be set, 350 is a side guide that aligns and guides the side edges according to the document size, and 351 is one document set on the document table 349. Paper feeding roller 352 for feeding one by one
Is a conveyor belt 353 that conveys the original sent by the paper feed roller 351 to a predetermined position on the contact glass 310.
Is a paper discharge tray from which the document after the copying process is discharged.

The operation of the automatic document feeder (ADF) 302 configured as above will be described. A plurality of originals set on the original feeding table 349 are aligned in the widthwise direction of the originals by the side guides 350. The set originals are fed one by one by the rotation of the feed roller 351 and the contact glass 3 by the rotation of the conveyor belt 352.
It is conveyed to a predetermined position on 10 and stopped. After that, the exposure operation is performed and the image formation is performed as described above.
When a predetermined number of copy processes are completed in this way, the document on the contact glass 310 is discharged to the discharge tray 353 by the rotation of the conveyor belt 352. The side guide 350
The size of the document is detected by counting the set position of and the feeding time of the document. As described above, the automatic document feeder (ADF) 302 sequentially conveys the originals one by one onto the contact glass 310 for each copy cycle,
The copy processing operation is automatically performed.

Next, the structure of the sorter 303 shown in FIG. 3 will be described. In the figure, reference numerals 354a to 354x denote bins for ejecting the recording paper after the copying process in page order, page by page, or at preset positions, and 355 is a drive motor that rotationally drives a plurality of transport rollers.

The sorter 303 configured as described above is
Depending on the method of ejecting the recording paper ejected from the copying machine main body 301, for example, in page order (sort), page by page (stack), or preset positions selected in the bins 354a to 354x (mailbox). This is a device for selectively ejecting recording paper to the bins 354a to 354x. The recording paper sent by the plurality of transport rollers rotated by the drive motor 355 is guided to the selected bin 354 by switching the claws near the entrance of each bin 354.

Next, the structure of the double-sided reversing device 304 shown in FIG. 3 will be described. In the figure, reference numeral 356 is a conveying roller for accumulating recording sheets sent from the copying machine main body 301, and 35.
7 is a tray for accumulating the recording papers sent from the conveying roller 356, 358 is an alignment guide for aligning the recording papers,
Reference numeral 359 denotes a conveyance roller that aligns and conveys the recording paper, and 36
Reference numeral 0 denotes a refeed roller for refeeding the recording paper.

Double-sided reversing device 30 constructed as described above
The operation of No. 4 will be described. When performing a double-sided copy collectively for a plurality of sheets, the recording paper is sent to the double-sided reversing device 304 by switching the switching claw 343. The fed recording sheets are stacked on the tray 357 by the transport rollers 356. At that time, the conveyance rollers 359 and the alignment guide 358 align the side faces of the recording paper in the vertical and horizontal directions. The recording paper accumulated on the tray 357 is sent to the re-feeding unit 346 by the re-feeding roller 360 and is sent to the registration roller 339 as described above, and the toner image is transferred to the back surface of the recording paper. As described above, the re-feeding unit 346 of the copying machine main body 301 can perform double-sided copying only for each sheet, but by mounting the double-sided reversing device 304, a plurality of double-sided copies can be collectively performed.

Further, 361 shown in FIG. 3 is a main motor for rotationally driving each roller and the like of the copying machine main body 301, and 362 is a fan motor for keeping the temperature inside the copying machine main body 301 rise below a certain value. Is.

FIGS. 6 and 7 are circuit diagrams showing the electrical equipment control section of the digital copying machine according to the present invention. In the figure, 6
01 is a CPU (a) for controlling sequence-related, 60
Reference numeral 2 denotes a CPU (b) that controls operations, and the CPU (a) 601 and the CPU (b) 602 are connected by a serial interface (RS232C).

Further, 603 is a paper size sensor for detecting the size of the recording paper in the paper feeding unit 309, 604 is a sensor such as a registration sensor and a paper discharge sensor, and 605 is each condition setting (for example, recording by the registration roller 339). A dip switch provided for the loop amount of the paper, a margin amount of the leading edge of the recording paper, and the like, and 606 applies high-voltage power to the charging charger 325, the transfer charger 330, the separation charger 331, and the developing bias electrode (not shown). High-voltage power supply, 607
Is a relay driver for driving and controlling a power relay, 608
Is a toner replenishment solenoid, a solenoid such as a paper feed clutch, and a solenoid driver for driving and controlling clutches, 6
Reference numeral 09 is a motor driver for driving and controlling motors such as the main motor 361 and the fan motor 362.

Reference numeral 610 is the fixing temperature of the fixing roller 341, the photosensor input of the density sensor 336, the monitor input of the semiconductor laser 401, and the analog input portion to which the reference voltage of the semiconductor laser 401 is input, and 611 is the use management for each operator. A key card unit for reading a key card for use in data processing, 612 is a ROM storing programs for various control conditions, 613 is an address decoder for the CPU (a) 601, and 614 is connected to each sensor (603 to 605). RAM, I / O port, timer, 615 double-sided reversing device 304, I / O port for high-voltage power supply 606, 616
Is a relay driver 607, a solenoid driver 608,
I / O port for motor driver 609, 617 is US connected to sorter 303 by serial interface
ARP, 618 is an A / D converter for converting analog data into digital data and outputting it to the optical writing unit 306, 6
Reference numerals 19a to 619c are timer counters for executing processing based on the set time widths, and 620 is an address latch.

Reference numeral 621 denotes a gate array which outputs three-direction image data (DATA0 to DATA7) of the image processing board 319, the scanner control circuit 623, and the application circuit 624 and a synchronizing signal in response to a select signal from the CPU (b) 602. 622 is an address decoder for the CPU (b) 602, 623 is a scanner control circuit, and 624 is an external device (facsimile device, printer, etc.) and CPU.
(B) The interface 602 is an application circuit that outputs a signal based on preset information.

Reference numeral 625 denotes an operation unit including a key input unit for inputting operations such as a copy mode and a display unit for displaying the status of the copying machine. Reference numeral 626 denotes an editor for performing image editing processing.
27 is a calendar IC that stores the date and time and outputs them to the CPU (b) 602 at any time, and 628 is the CPU (b) 602.
ROM for storing programs for CPU, 629 for CPU
(B) RAM for 602, 630 is USARP connected to the operation unit 625 via a serial interface, 631 is USARP connected to the scanner control circuit 623 via a serial interface, and 632 is an application circuit 6
24 to connect with serial interface
P, 633 is USARP connected to the editor 626 via a serial interface, 634 is calendar IC 62
7 address latch.

The operation of the electrical equipment control section of the digital copying machine configured as described above will be described. Sequence-related control is performed by the CPU (a) 601 and control of paper conveyance, image forming conditions, and the like is performed. For example, the paper feed cassette 33
The size and feeding direction of the recording paper set in No. 7 are detected by the paper size sensor 603, and paper conveyance, image control, etc. are performed based on this detection signal. In addition to this, the signals of the sensors 604 such as the registration sensor and the paper discharge sensor and the setting conditions of the dip switch 605 are input to the CPU (a) 601 to perform jam detection, paper interval control, and image forming control. Be seen.

The double-sided reversing device 304 has a motor for making the width of the recording paper uniform, a paper feed clutch, a solenoid for switching the conveying path, a solenoid for vertically moving a roller for bringing the recording paper to the leading end, a paper presence sensor, and a paper width uniform. Input and output by the home position sensor of the side fence and the sensor related to the conveyance of the recording paper. The high-voltage power supply 606 applies high-voltage power of a predetermined value to the charging charger 325, the transfer charger 330, the separation charger 331, and the developing bias electrode (not shown) at predetermined timing. Drivers such as a relay driver 607, a solenoid driver 608, a motor driver 609, etc. are connected to a CPU such as a paper feed clutch, a registration clutch, a drive motor, etc.
(A) On / off control is performed based on the control signal 601.

The sorter 303 is connected by a serial interface, and conveys the recording paper at a predetermined timing by the control signal of the CPU (a) 601 and discharges it to each bin 354. A fixing temperature of the fixing roller 341, a photo sensor input of the density sensor 336, a monitor input of the semiconductor laser 401, and a reference voltage of the semiconductor laser 401 are input to the analog input unit 610. This fixing temperature is the same as that of the fixing roller 34.
The heater in the fixing roller 341 is controlled to be turned on / off so that the temperature of the fixing roller 341 falls within a certain range by an input from a thermistor (not shown) arranged in contact with or close to the surface of the fixing roller 341. As a photosensor input of the density sensor 336, a photosensor pattern formed at a predetermined timing is input by a phototransistor, and the toner density is controlled by detecting the pattern density and controlling the on / off of the toner supply clutch.

Further, an A / D is provided as an adjusting mechanism for keeping the output value of the laser beam from the semiconductor laser 401 constant.
The analog inputs of converter 618 and CPU (a) 601 are used. This is controlled so that the monitor voltage during oscillation of the semiconductor laser 401 matches a preset reference voltage of the semiconductor laser 401 (for example, the output value is set to be 3 mW).

The image processing board 319 generates timing signals for masking / trimming of image data, erasing, photosensor pattern of the density sensor 336, etc., and outputs a video signal to the semiconductor laser 401. The gate array 621 outputs the image data continuously transmitted in 2-bit parallel from the scanner unit 305 to the synchronization signal P from the optical writing unit 306.
Image writing position signal RGAT synchronized with MSYNC
It is converted into a 1-bit serial signal synchronized with E and output to the image processing board 319.

Next, operation-related control will be described below. CPU (b) 602 (main CPU)
Controls multiple serial ports and calendar IC 627. A sequence control CPU (a) 601 is connected to the plurality of serial ports, and an operation unit 62 is also provided.
5, scanner control circuit 623, application circuit 6
24, an editor 626, etc. are connected.

In the operation unit 625, the key input information by the operator is serially transmitted to the CPU (b) 602, and the CP
The display is turned on by serial reception from the U (b) 602. In the scanner control circuit 623, C of information regarding drive control of the scanner servo motor, image processing, and image reading is displayed.
Serial transmission processing for PU (b) 602 and ADF
Interface processing between 302 and the CPU (b) 602 is performed.

The application circuit 624 exchanges preset information through an interface with an external device (facsimile device, printer, etc.).
Further, the editor 626 serially transmits the image edit data (masking, trimming, image shift, etc.) input from the operation unit 625 to the CPU (b) 602, and inputs the content of image edit processing. The calendar IC 627 reads the stored date and time by the CPU (b) 602 at any time, and displays the current time on the display unit of the operation unit 625 and timer control by setting the on time and off time of the copying machine. Etc. are executed.

FIG. 8 is a block diagram showing the overall configuration of the control system in the digital copying machine according to the present invention. In the figure, 701 is a main control board that controls the entire digital copying machine, and 702 is an AD that controls the ADF 302.
F control plate, 703 is a sorter control plate that controls the sorter 303, 704 is a double-sided control plate that controls the double-sided reversing device 304, 705 is a paper feed control plate that performs various controls of the paper feed unit 309, and 706 is an application system. , 707 are sensors such as a fixing sensor, a density sensor 336, and a registration sensor, 708 is a fan such as an APL fan and an exhaust fan,
709 is a counter such as a total counter or a key counter, and 710 is a fixing thermistor for detecting the surface temperature of the fixing roller 341.

Further, 711 is an LD control plate for controlling the semiconductor laser 401, 712 is a PWM control plate, 713 is a drive plate for driving the polygon motor 321, 714 is a drive plate for driving the main motor 361, and 715 is a fixing roller 341. Fixing heater and temperature fuse to prevent overheating,
Reference numeral 716 is an AC drive plate serving as an AC power source for a fixing heater or the like, 717 is a DC power source serving as a drive source for each DC drive component by rectifying the AC from the AC driver 716 into DC.
Is a toner replenishment SOL (solenoid) of the developing unit 308, a blade SOL (solenoid) that causes the cleaning blade 332 to abut and separate from the photosensitive drum 307, a first to third pickup SOL (solenoid), and first and second lock SOL. (Solenoid) 719 is a registration CL (clutch) for drivingly transmitting to the registration rollers 339, an ascending relay CL (clutch), and first to third sheet feeding CLs.
(Clutch), 720 are sensors related to the sheet feeding unit 309,
Reference numeral 721 is an intake fan, and 722 is a conveyance fan that adsorbs the recording paper of the conveyance unit 340.

Further, 723 is each sensor of the sorter 303, 724 is a drive motor for rotationally driving each roller of the sorter 303, 725 is a solenoid for switching the entry of recording paper into each bin 354 of the sorter 303, and 726 is a double-sided. Solenoids of reversing device 304, 727 clutches of double-sided reversing device 304, 728 jogger motor for aligning sheets of double-sided reversing device 304, 729 each sensor of double-sided reversing device 304, 730 each sensor of ADF 302 , 731 is each solenoid of the ADF 302, 73
Reference numeral 2 is a motor for rotatably driving each conveying roller of the ADF 302, 733 is a switch for detecting the set state of the ADF 302 and a switch for switching the paper thickness of the original, and 734 is A.
The DF 302 is a display unit that displays the number of documents, jam status, and the like.

Further, 735 is a scanner motor for scanning and driving the scanner unit 305, and 736 is a scanner motor 735.
Rotary encoder connected to the drive shaft of
7 is a lamp control circuit for controlling the lighting of the exposure lamp 311;
Reference numeral 738 is an HP sensor for detecting the reference position of the sub-scanning drive mechanism, 739 is ADFSOL (solenoid), 740 is APSSOL (solenoid), and 741 is a fluorescent lamp heater and a thermistor for temperature control.

Further, 742 is an image preprocessor (IPP) having functions of shading correction, black level correction and light amount correction, and 743 is an MTF correction function (spatial frequency high range emphasis), speed conversion function (magnification), γ conversion function. , An image processing unit (IPU) having a data depth conversion function (8 bit / 4 bit / 1 bit conversion), a memory device (MEM) 744 for capturing the output of the IPU 743,
An external storage device 745 inputs / outputs data to / from the memory device 744.

FIG. 9 is a block diagram showing the scanner unit 305 in the digital copying machine according to the present invention. In the figure, 801 is a timing control circuit that outputs each signal based on an instruction from the scanner control circuit 623, 802 is a signal processing circuit that performs image signal amplification and light amount correction processing,
803 A for converting analog data into digital data
A / D converter 804 is a shading correction circuit that corrects distortion of image data.

The scanner unit 305 configured as described above
The image reading operation will be described. The scanner control circuit 623 receives the lamp control circuit 737, the timing control circuit 801, and the IPU 7 based on an instruction from the printer control unit (not shown).
The electric variable magnification circuit 43 and the scanner motor 735 are controlled. The lamp control circuit 737 turns on / off the exposure lamp 311 and controls the light amount based on an instruction from the scanner control circuit 623. Further, the electrical scaling circuit of the IPU 743 performs electrical scaling processing based on the magnification data on the main scanning side set by the scanner control circuit 623.

Further, the timing control circuit 801 outputs each signal based on the instruction from the scanner control circuit 623. That is, when the reading of the original is started, a transfer signal for transferring the data for one line to the shift register and a shift clock pulse for outputting the data in the shift register bit by bit are output to the CCD image sensor 318. It also outputs a pixel synchronization clock pulse CLK, a main scanning synchronization pulse LSYNC, and a main scanning effective period signal LGATE to an image reproduction system control unit (not shown).

This pixel synchronizing clock pulse CLK is C
The signal is almost the same as the shift clock pulse input to the CD image sensor 318. In addition, the main scanning synchronization pulse LS
YNC is almost the same signal as the main scanning sync signal PMSYNC output from the sync sensor of the optical writing unit 306, but is output in response to the pixel sync clock pulse CLK. The main scanning effective period signal LGATE is output data DATA0 to DATA0.
It becomes H level at the timing when DATA7 is regarded as valid data. In this case, the CCD image sensor 318
Outputs 4800 bits of valid data per line.

When the scanner control circuit 623 receives a reading start instruction from the printer control unit (not shown), the exposure lamp 311 is turned on, the scanner motor 735 is driven, and the timing control circuit 801 is controlled. The reading by the CCD image pickup device 318 is started. Further, the sub-scanning effective period signal FGATE is set to the H level. The sub-scanning effective period signal FGATE becomes L-level after the time required to scan the maximum reading length (in this case, the size in the longitudinal direction of A size) in the sub-scanning direction after being set to H level.

The analog signal output from the CCD image pickup device 318 is an image preprocessor (IPP).
A signal processing circuit 802 inside 741 performs amplification processing and light amount correction, and is converted into a digital multilevel signal by an A / D converter 803. The converted image signal is subjected to distortion correction by the shading correction circuit 804 and input to the next image process unit (IPU) 743.

FIG. 10 shows an image process unit (I
(PU) 743 is a block diagram showing details. In the figure, 901 is an MTF correction unit that corrects blurring or deterioration of an image signal, 902 is a scaling processing unit that electrically scales the image signal based on a designated scaling factor, and 903 is an input / output characteristic of the image signal. A γ conversion unit 904 that corrects so as to be optimum for the process characteristics, and 904 is a data depth switching mechanism unit including a 4-bit conversion circuit 905, a binarization circuit 906, a dither circuit 907, a changeover switch 908, and a changeover switch 909. is there.

The data processing operation of the image process unit (IPU) 743 configured as above will be described. The image signal input from the image preprocessor (IPP) 741 is high-frequency emphasized by the MTF correction unit 901. Next, the scaling processing unit 902 performs electrical scaling to a predetermined magnification, and the γ conversion unit 903 optimizes the input / output characteristics of the image signal with respect to the image forming process characteristics. γ conversion unit 9
The image signal output from 03 is input to the data depth switching mechanism unit 904 and converted into a predetermined quantization level.

This data depth switching mechanism section 904 is 4 bi
The t conversion circuit 905 outputs 4 bit DATA.
The binarization circuit 906 converts the inputted 8-bit multi-valued data into binary data by a preset fixed threshold value and outputs 1-bit DATA. Dither circuit 907 is 1
An area gradation is formed by bitDATA. At this time, the changeover switch 909 selects and outputs the output of the binarization circuit 906 or the dither circuit 907. Then, the changeover switch 908 uses the three data (8 bit DATA,
One of the data formats (4DATA, 1bitDATA) is selected and DATA0 to DATA7 are output. The output data format of this image process unit (IPU) 743 is shown in FIG.

FIG. 12 is a block diagram showing a memory system according to the present invention. In the figure, 1101 to 110
Reference numeral 3 designates multiplexers MUX1, MUX2, MUX3 for selecting and switching a plurality of input data, and E in the figure
XTIN indicates an image data input signal from the outside,
EXTOUT indicates an output signal to the outside.

An operation example of the memory system configured as above will be described. For example, a single exposure scan of the scanner unit 305 may be performed on a plurality of image processing units (IP
U) When outputting a copy with the parameters of 743 changed, first, MUX1 is set to A, MUX2 when scanning the scanner.
To B and MUX3 to A to output one copy. The raw data at this time is input to the memory device (MEM) 744 via the MUX2.

Next, for the second and subsequent sheets, the MUX1 is set to B, the data from the memory device (MEM) 744 is input to the image process unit (IPU) 743, and the MU is set.
Output to the printer (PR) via X3. Then 1
Image process unit (IP
U) Change the parameters of 743. Also, 1bitD
If you want to store compact data like ATA,
The MUX2 is set to A, and the output of the image processing unit (IPU) 743 is output to the memory device (MEM) 744.
Take in. At this time, the printer (PR) switches to the binary data (1 bit) mode and executes the copying process.

FIG. 13 is an explanatory diagram showing the flow of the image signal according to the present invention, and shows the data flow by the processing described in FIG. In this way, both the data processed by the image processing unit (IPU) 743 and the raw data can be loaded into the memory device (MEM) 744.

FIG. 14 shows the memory device (MEM) 74.
4 is a block diagram showing an example of the internal configuration of FIG. In the figure, reference numeral 1301 denotes a compressor (COM) that performs data compression processing.
P) 1302 is an image process unit (IPU)
Multiplexers MUX4, 1 for selecting and switching data input from the H.743 and the compressor (COMP) 1301
Reference numeral 303 denotes a memory unit that stores compressed data processed by a compressor (COMP) 1301 in addition to actual data, and 13
Reference numeral 04 designates a decompressor (EXP) for decompressing data, 13
05 is a memory unit 1303 and an expander (EXP) 13
Multiplexers MUX5 and 1306 that select and switch the data input from 04 are error detectors that monitor the error signals of the compressor (COMP) and the decompressor (EXP) 1304.

The memory device (ME
M) 744 has a compressor (COMP) 1301 placed in front of the memory unit 1303 and an expander (EXP) 130.
4 is arranged after the memory unit 1303, and further, the multiplexer MUX4 and the multiplexer MUX5 are connected to the memory unit 1303, respectively, so that the actual data and the compressed data can be selectively stored. That is, when the actual data is stored in the memory unit 1303, the multiplexer MUX4 and the multiplexer M
Set each UX5 to A. In addition, the compressor (COM
P) The data processed in 1301 is stored in the memory unit 13
In the case of storing in M.03, the multiplexers MUX4 and MUX5 are set to B respectively. In the above configuration, the compressor (COMP) 1301 performs memory processing according to the scanning speed of the scanner unit 305,
The decompressor (EXP) 1304 executes processing according to the speed of the printer (PR).

FIG. 15 shows the above memory unit 1303.
3 is a block diagram showing an example of the internal configuration of FIG. In the figure, 1401 is an input data width converter for processing code data which is image data and compressed data, 1402 is a memory block for storing the number of packed data, 140
3 is an output data width converter for processing code data which is image data and compressed data, and 1404 is data at a predetermined address of the memory block 1402 corresponding to the number of data packed by the input data width converter 1401 and the memory data width. A direct memory controller (DMC1) 1405 for performing the writing / reading operation of the data is written / read to / from a predetermined address of the memory block 1402 corresponding to the number of data packed by the output data width converter 1403 and the memory data width. It is a direct memory controller (DMC2) that operates.

Memory unit 1 configured as described above
303 has an input data width converter 1401 and an output data width converter 1403 on the input side and output side of the memory block 1402, respectively, and has three image data types (see FIG. 1).
5)) and the compressed data from the compressor (COMP) 1301 are processed. The direct memory controller (DMC1) 1404 and the direct memory controller (DMC2) 1405 store data at a predetermined address of the memory block 1402 according to the number of data packed by the input data width converter 1401 and the output data converter 1403 and the memory data width. Write / read processing is performed.

FIG. 16 is an explanatory diagram showing the format of the image data processed in FIG. (A) Type 1 is 1-bit data, (b) Type 2 is 4-bit data,
(C) Type 3 indicates 8-bit data. The speed of image data from a scanner or the speed of image data to a printer in a normal case is constant regardless of 8-bit data, 4-bit data, or 1-bit data because the period of 1 pixel is fixed in the apparatus.

In the present invention, the MBS (Most Significant Bi) of eight data lines is used.
(t: the most significant bit of the data) is defined as 1-bit data, 4-bit data, 8-bit data and MBS justification. This data is stored in the memory block 1402.
The blocks to be packed and unpacked to the data width (16 bits) are the input data width converter 1401 and the output data width converter 1403, and by performing the packing process, the memory can be used according to the data depth. MEM) 744 can be effectively used.

FIG. 17 is a block diagram showing a configuration example in which a pixel process unit (PPU) is connected to the memory unit 1303. In the figure, 1601 is a logical operation between image data (for example, AND, OR, EOR,
Pixel process unit (PP) that performs NOT
U) and 1602 are image process units (IPU)
743 and Pixel Process Unit (PPU) 1601
The multiplexers MUX6 and 1603 for selecting and switching the data input from are the multiplexers MUX for selecting and switching the data input from the pixel process unit (PPU) 1601 and the memory unit 103.
7

As described above, the memory device 74 shown in FIG.
4, the pixel process unit (PPU) 1601 is replaced by the memory unit 1303 instead of the compressor (COMP) 1301 and the decompressor (EXP) 1304.
It is configured to be disposed outside the. In such a configuration,
The pixel process unit (PPU) 1601 logically operates the memory output data and the input data and outputs it to the printer (PR). Further, a memory output and input data (for example, data from the scanner unit 305) can be logically operated and stored again in the memory unit 1303. The output destination printer (PR) and the memory unit 1303 are switched by the multiplexers MUX6 and MUX7. Such a function is generally used for image composition processing, for example, image composition processing such as overlaying overlay on scanner data.

FIG. 18 is a block diagram showing the configuration of the external storage device 745 that executes the image data storage process. In the figure, 1701 is an interface (I / F) that controls input / output of image data, 1702 is a floppy disk controller (FDC) that controls a floppy disk driver (FDD) 1703, 1703.
Is a floppy disk driver (FDD) that drives a floppy disk (FD) serving as a storage medium, 1704 is a hard disk controller (HDC) that controls writing / reading of a hard disk (HDD) 1705, and 1705 is a writable / readable hard disk. (HDD), 1706
Is a floppy disk controller (FDC) 1702
A file controller (FC) that controls the hard disk controller (HDC) 1704, and a line drawer (LD) 1707 that controls the interface (I / F) 1701.

The operation of storing the image data in the external storage device 745 in the above configuration will be described. When the image data is stored in the floppy disk (FD), it is output from the EXTOUT shown in FIG. 12 to the floppy disk controller (FDC) 1702 controlled by the file controller (FC) 1706 via the interface (I / F) 1701. , A floppy disk driver (FDD) 1703 and a floppy disk (FD). The hard disk controller (HDC) 1704 also controls the hard disk (HD) under the control of the file controller (FC) 1706.
DD) 1705 is executed for writing / reading. A hard disk (HDD) 1705 stores format data and overlay data that are used for general purposes and can be used as needed.

FIG. 19 is a block diagram showing an example in which recovery is possible when the processing speed of image data compression and expansion is not in time. In the figure,
Reference numeral 1801 denotes a memory management unit (MMU) for controlling the memory by simultaneously inputting / outputting two input data and one output data to / from the memory unit 103, and 1802 inputs from the memory unit 103 and the decompressor (EXP) 104. The multiplexer MUX8 selects and switches the data to be switched.

In the above configuration, the memory unit 10
3 includes a compressor (COMP) 102 at the same time as the scanner scanning.
The data and image data compressed by are input to the memory unit 103. The data input to the memory unit 103 is stored in separate memory areas, and the compressed data is input to the decompressor (EXP) 104 as it is for decompression processing. By the time the input of all data for one page to the memory unit 103 is completed, the compressor (C
When the processing time by the OMP) 102 and the decompressor (EXP) 104 is in time and the processing is completed normally, the memory area of the compressed data is left and the area of the raw data is released.

Here, when the error detector 201 detects an error signal from the compressor (COMP) 102 or the decompressor (EXP) 104, the data area of the compressed data is immediately canceled and the raw data is adopted. By thus performing the verification process of the compressor (COMP) 102 and the decompressor (EXP), high-speed and reliable data processing and effective use of the memory area can be realized.

As described above, the memory management unit (M
Although the MU) 1801 enables dynamic allocation of the memory area, the same processing can be performed by disposing two memory units for raw data and compressed data as another method. Such a configuration is used for applications such as electronic sorting in which a plurality of pages are to be stored and the conditions for satisfying both the number of pages to be stored and the printing speed to be output in real time to a printer (PR) must be satisfied. Then it is effective.

[0091]

As described above, according to the image forming apparatus of the present invention, when the error detecting means detects an error by the time one scan of the document is completed, the image data before compression is adopted to eliminate the error. When not detected, the compressed data is adopted, when the error detection means detects an error by the completion of one scanning of the document, the compressed data is canceled from the storage means, and when the error is not detected, the compressed data is stored from the storage means before compression. The image data is canceled, and further, when each process by the data compressing means and the data decompressing means is completed by the time one scanning of the original is completed, the image data before compression is canceled from the storing means, and when each processing is not finished, the storing means is executed. Since the compressed data is canceled, the real-time processing of compression / decompression processing and the reliability of data processing are realized, and the processing speed is increased. And equivalent to the output device can be improved replication efficiency.

[Brief description of drawings]

FIG. 1 is a block diagram showing an outline of image data processing in an image forming apparatus according to the present invention.

FIG. 2 is a block diagram showing a configuration example that enables error detection processing according to the present invention.

FIG. 3 is an explanatory diagram showing a configuration example of a digital copying machine to which the image forming apparatus according to the present invention is applied.

FIG. 4 is an explanatory view showing a plan view of the optical writing section shown in FIG.

5 is an explanatory diagram showing a side surface of the optical writing section shown in FIG.

6 is a circuit diagram showing an electrical equipment control unit in the digital copying machine shown in FIG.

FIG. 7 is a circuit diagram showing an electrical equipment control unit in the digital copying machine shown in FIG.

8 is a block diagram showing an overall configuration of the digital copying machine shown in FIG.

9 is a block diagram showing an image reading operation of the scanner of the digital copying machine shown in FIG.

10 is a block diagram showing details of the image processing unit shown in FIG.

11 is an explanatory diagram showing an output data format of the image process unit shown in FIG.

FIG. 12 is a block diagram showing a memory system according to the present invention.

FIG. 13 is an explanatory diagram showing a flow of an image signal according to the present invention.

14 is a block diagram showing an example of an internal configuration of the memory device shown in FIG.

15 is a block diagram showing an internal configuration of the memory unit shown in FIG.

16 is an explanatory diagram showing a format of image data processed by the memory device shown in FIG.

FIG. 17 is a block diagram showing a configuration example in which a pixel process unit is connected to a memory unit according to the present invention.

18 is a block diagram showing a configuration of the external storage device shown in FIG.

FIG. 19 is a block diagram showing a configuration example that enables recovery when the processing speed of image data compression and expansion according to the present invention is not in time.

FIG. 20 is a block diagram showing a flow of processing of conventional image data.

[Explanation of symbols]

102 Compressor (COMP) 103 Memory Unit 104 Expander (EXP) 201 Error Detector 301 Copy Machine Main Body 302 Automatic Document Feeder (ADF) 303 Sorter 304 Double-sided Reversing Device (DPX) 305 Scanner Section 306 Optical Writing Section 318 CCD Image sensor 319 Image processing plate 601 CPU (a) 602 CPU
(B) 701 Main control board 741 Image preprocessor (IPP) 743 Image process unit (IPU) 744 Memory device (MEM) 745 External storage device 904 Data depth switching mechanism section 1303 Memory unit 1401 Input data width converter 1402 Memory block 1403 Output data width converter 1404 Direct memory controller (DMC) 1405 Direct memory controller (DMC) 1601 Pixel process unit (PPU) 1801 Memory management unit 1802 Multiplexer (MUX8)

Claims (3)

[Claims] 1. A data compression means for compressing image data obtained by scanning a document, a storage means for storing the compressed data compressed by the data compression means and the image data before compression, and the storage. Data decompression means for decompressing the compressed data read from the means, and error detection means for detecting an error in the data compression means and the data decompression means are provided, and the error detection means completes one scan of the document. The image forming apparatus employs the image data before the compression when an error is detected up to the time, and adopts the compressed data when the error is not detected. 2. The compressed data is canceled from the storage means when the error detection means detects an error by the time one scan of the document is completed, and the image data before the compression is deleted from the storage means when no error is detected. The image forming apparatus according to claim 1, wherein the image forming apparatus is canceled. 3. The image data before compression is canceled from the storage means when each processing by the data compression means and the data expansion means is completed by the time one scanning of the original is completed, and the storage is performed when each processing is not ended. The image forming apparatus according to claim 1, wherein the compressed data is canceled from the means.