JP2009303057A - Image reader and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the sheet-through reading quality, to improve the reading productivity and to accomplish them, using a simple configuration and functionality. <P>SOLUTION: An image reader includes: a first control means 212 wherein, before moving a first document on a document tray to a sheet-through reading window position, shading data are produced by lighting a reference white plate 102 with a light source 107 and stored in a first storage means and next; shading correction is performed, on the basis of the shading data, upon image data of each of documents to be moved to the reading window position, on the document tray by moving the light source to the window position; and second control means 114, 212 wherein a change in the image data obtained by reading another reading target 118, different from the reference white plate, reflecting the light of the light source at the window position is monitored; and when there is a prescribed change, shading data are produced by driving the light source to the reference white plate position and stored in the first storage means. In another mode, the second control means corrects document image data, on the basis of the image data obtained by reading the reading target. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an apparatus for reading an image of a document and an image forming apparatus using the apparatus, and is used in, for example, a scanner device, a copying machine, a facsimile machine, a digital multifunction machine, or the like.

Japanese Patent Laid-Open No. 2002-262041.

  For example, in an MFP (multifunction machine having functions of scanner, copy, printer, FAX, etc.), a sheet-through document feeder (hereinafter abbreviated as SDF) for transporting a document is mounted, and the document is moved by sub-scanning. The ratio of models that read original images with a stationary optical system increases, and the copy function in addition to the scanner and FAX functions is also compared to reading (BOOK scan) in which the original is fixed on the original table and the optical system is driven by sub-scanning. Thus, the reading ratio in SDF is high.

  In an image reading apparatus provided with an SDF, an SDF contact glass (sheet through reading window) is provided as an SDF original plate, in addition to a contact glass as an original plate for fixing and reading an original. In some cases, an optical system that scans and scans a document set on a contact glass as a document table in the sub-scanning direction is fixed at the position of the SDF sheet through reading window, and the document passes through the window. Documents are sequentially read by an optical system fixed below.

  Conventionally, there is a shading operation at the time of sheet-through reading every time before reading sequentially conveyed documents. Recently, in order to ensure reading productivity, a shading operation is performed for every predetermined number of readings. There are also image reading apparatuses that reduce the reading time by performing shading correction processing using the shading data immediately before (currently stored) at the time of reading a document, which is performed only once or several times in a predetermined time. It has been developed. This method is called intermittent shading here.

  By the way, at the time of continuous reading of a plurality of originals, the light amount of the reading light source decreases due to heat generated by continuous lighting, and the reading level of the originals decreases accordingly. For this reason, when the shading correction process is performed on a plurality of originals using the same shading data, there arises a problem that a density difference between the first and last read originals occurs.

  In the image reading apparatus using the intermittent shading operation performed every predetermined number of sheets or every predetermined interval, the light amount reduction amount of the light source varies depending on the light source and further depends on the environment such as the ambient temperature in the reading apparatus. A case where the optimum shading correction is not performed can be considered sufficiently.

  In the first embodiment of the image reading apparatus described in Patent Document 1, in the sheet-through reading using the SDF, a reference white plate immediately before the image reading of the first document of a plurality of documents loaded on the document tray is performed. Is generated and stored in the memory, and the image reading image data of the first and subsequent originals is corrected with the shading data (shading correction), and the originals sequentially passing through the sheet-through reading windows are also read. Detects the level of reflected light from the white platen that transports the document or the guide plate that guides the document, that is, the back member that opposes the sheet-through reading window, between the sheets, and the level is blacker than the criterion value. When the density changes, it is determined that there is an abnormality, and the reading of the original reading data is stopped. In the second embodiment, the image data obtained by reading the reference white plate and the image data read by the back member are compared with the judgment reference values assigned to the respective images. It is determined that the reading of the original reading data is stopped. In another aspect, each time the shading data is generated by reading the reference white board, the back member reading image data abnormality determination is performed in response to the change in the shading data, compared to the previous shading data. Change the criterion value.

  The first object of the present invention is to increase the image data quality of sheet-through reading, and the second object is to increase the read productivity by reducing the frequency of shading data update for these purposes. A third object is to realize with a simple configuration and function.

(1) Document conveying means (212, 14) for sequentially transferring the documents on the document tray (11) one by one across the sheet through reading window (102) in response to the document reading instruction;
A reference white plate (103) for shading correction at a position different from the position of the reading window;
Illumination light source (107);
Light source driving means (212-214) for driving the illumination light source at a window position (Y) where the illumination light source faces the reading window and a reference white plate position where the illumination light source faces the reference white plate (103);
Imaging means (24) for converting incident light into an image signal:
When the illumination light source is at the window position, the reflected light of the original facing the window of the light irradiated by the illumination light source on the reading window is incident on the imaging means, and the illumination light source is at the reference white plate position. Sometimes, the optical means (108, 110, 111, 23) that makes the reflected light of the reference white plate of the light irradiated by the illumination light source to the reference white plate enter the imaging means;
Signal conversion means (202, 203) for converting the image signal converted by the imaging means into image data which is digital data;
Shading processing means for generating shading data based on the image data of the reference white plate and storing it in the first storage means (206), and correcting the shading of the image data of the document based on the shading data of the first storage means. (113);
Before transferring the first sheet of the document loaded on the document tray to the window position, the shading processing unit generates the shading data by illuminating the reference white plate with the illumination light source, and stores the first shading data. The image data of each of the originals loaded in the original tray is stored by the shading processing means, and then the illumination light source is driven to the window position and transferred to the reading window by the original conveying means. First control means (212) for correcting shading; and
When the illumination light source is at the window position, the change of the image data obtained by reading the reading object (118) different from the reference white plate that reflects the light of the illumination light source is monitored, and a predetermined change is detected. If there is, second control means (114, 212) for driving the illumination light source to the reference white plate position, generating the shading data by the shading processing means, and storing it in the first storage means;
(Example 1 and Example 3).

  In order to facilitate understanding, the reference numerals or corresponding matters of corresponding elements of the embodiments shown in the drawings and described later are shown in parentheses for reference. The same applies to the following.

(2) The image reading apparatus further includes a document set detection unit (215) for detecting the loading of the document on the document tray, and measures an elapsed time after the document set detection unit detects the loading of the document. Timer (701) to be
The first control means (212) turns on the illumination light source in response to the loading of the document and drives it to the reference white plate position to generate shading data based on the image data of the reference white plate. 1 is stored in one storage means, and if there is a document reading instruction before the elapsed time measurement value of the timer exceeds a set value (Tth), the image data of each document loaded on the document tray is stored in the shading processing means. If there is no document reading instruction and the elapsed time measurement value of the timer exceeds a set value (Tth), the illumination light source is turned off, and then the illumination light source is turned on in response to the document reading instruction. Generating the shading data, storing it in the first storage means, and correcting the shading of the document image data;
The image reading apparatus according to (1) (Example 3).

  (3) The other reading object (118) is a back member (118) that faces the reading window and is located on the opposite side of the reading window with respect to the original when the original is being transferred. The image reading apparatus according to the above (1) or (2) (Example 1, Example 3);

  (4) The second control means (114, 212) stores the image data of the back member in the second storage means (208) immediately before or immediately after the generation of the shading data by the first control means, and then the original document. The document is transported sequentially from the document tray to the reading window by the conveying means, between the tail end of the preceding document passing through the reading window and before the leading edge of the succeeding document enters the reading window. When the image data of the back member is read and the amount of light is changed in a direction in which the amount of light is reduced with respect to the image data of the second storage unit, the illumination light source is driven to the reference white plate position, and the shading process is performed. Means for generating the shading data and updating the shading data in the first storage means; the image reading apparatus according to (3) above (Example 1, Example 3).

  (5) The image pickup means (24) converts the full width of the original in the main scanning direction orthogonal to the sub-scanning direction, which is the moving direction of the original, into an image signal for each pixel; the first control means (212) Each time the shading data is generated, stored in the first storage means, and the shading correction is performed; the second control means (114, 212) monitors the change in the image data for each pixel; (1) to ( 4) The image reading device according to any one of (1) and (3).

(6) Document conveying means (212, 14) for conveying the documents on the document tray (11) one by one in order to cross the sheet through reading window (102) in response to the document reading instruction;
A reference white plate (103) for shading correction at a position different from the position of the reading window;
Illumination light source (107);
Light source driving means (212-214) for driving the illumination light source at a window position (Y) where the illumination light source faces the reading window and a reference white plate position where the illumination light source faces the reference white plate (103);
Imaging means (24) for converting incident light into an image signal:
When the illumination light source is at the window position, the reflected light of the original facing the window of the light irradiated by the illumination light source on the reading window is incident on the imaging means, and the illumination light source is at the reference white plate position. Sometimes, the optical means (108, 110, 111, 23) that makes the reflected light of the reference white plate of the light irradiated by the illumination light source to the reference white plate enter the imaging means;
Signal conversion means (202, 203) for converting the image signal converted by the imaging means into image data which is digital data;
Shading processing means for generating shading data based on the image data of the reference white plate and storing it in a first storage means (206), and correcting the shading of the image data of the document based on the shading data of the storage means ( 113);
Before transferring the first sheet of the document loaded on the document tray to the window position, the shading processing unit generates the shading data by illuminating the reference white plate with the illumination light source, and stores the first shading data. The image data of each of the originals loaded in the original tray is stored by the shading processing means, and then the illumination light source is driven to the window position and transferred to the reading window by the original conveying means. First control means (212) for correcting shading; and
Based on the image data obtained by reading the reading object (118) different from the reference white plate, which reflects the light of the illumination light source when the illumination light source is at the window position, the light amount variation of the illumination light source Second control means (114, 212) for adding correction for compensating for fluctuations in image data due to the image data before or after the shading correction by the shading processing means;
(Example 2).

(7) The image reading apparatus further includes a document set detection unit (215) for detecting the loading of the document on the document tray, and measures an elapsed time after the document set detection unit detects the loading of the document. Timer (701) to be
The first control means (212) turns on the illumination light source in response to the loading of the document and drives it to the reference white plate position to generate shading data based on the image data of the reference white plate. 1 is stored in one storage means, and if there is a document reading instruction before the elapsed time measurement value of the timer exceeds a set value (Tth), the image data of each document loaded on the document tray is stored in the shading processing means. If there is no document reading instruction and the elapsed time measurement value of the timer exceeds a set value (Tth), the illumination light source is turned off, and then the illumination light source is turned on in response to the document reading instruction. Generating the shading data, storing it in the first storage means, and correcting the shading of the document image data;
The image reading apparatus according to (6) (Example 4).

  (8) The other reading object (118) is a back member (118) that faces the reading window and is located on the opposite side of the reading window with respect to the original when the original is being transferred. The image reading device according to the above (6) or (7) (Example 2, Example 4);

  (9) The second control means (114, 212) stores the image data of the back member in the second storage means (208) immediately before or immediately after the generation of the shading data by the first control means, and then the original document The document is transported sequentially from the document tray to the reading window by the conveying means, between the tail end of the preceding document passing through the reading window and before the leading edge of the succeeding document enters the reading window. Read the image data of the back member and use the ratio to the image data of the second storage means to correct the fluctuation of the image data due to the light quantity fluctuation of the illumination light source before the shading correction by the shading processing means. Or added to subsequent image data; the image reading apparatus according to (8) above (Example 2, Example 4).

  (10) The image pickup means (24) converts the full width of the original in the main scanning direction orthogonal to the sub-scanning direction, which is the moving direction of the original, into an image signal for each pixel; the first control means (212) The shading data is generated and stored in the first storage means and the shading correction is performed every time; the second control means (114, 212) compensates for fluctuations in the image data due to the light quantity fluctuation of the illumination light source for each pixel. Correction is performed; the image reading apparatus according to any one of (6) to (9) above (Examples 2 and 4).

  (11) Image data processing means (1) for converting the image data subjected to the shading correction by the shading processing means (113) into an image data format for image output; any one of (1) to (10) above (Examples 1, 2, 3, and 4).

(12) The image reading device (10, 20, 1) according to any one of (1) to (10) above;
Image forming means (30) for forming an image represented by the image data on a sheet; and
Image data processing means (42) for converting the image data output by the image reading device into image data suitable for the image forming characteristics of the image forming means and supplying the image data to the image forming means;
An image forming apparatus comprising:

  According to the above (1) to (5), since the light source light amount decrease is constantly monitored and the shading data is updated before the image data quality is deteriorated due to the light source light amount decrease, the image data quality by the shading correction is maintained high. . In addition, when the illumination light source is at the position of the sheet-through reading window, the change in the image data obtained by reading the reading object (118) different from the reference white plate that reflects the light of the illumination light source is monitored. Therefore, it is not necessary to move the illumination light source from the position of the reading window during the image reading by sequentially transferring each set of a plurality of documents placed on the document tray. The reading productivity of one set of originals does not decrease. Further, it is possible to determine whether or not shading data needs to be updated by simple calculations and comparisons without requiring complicated and complicated components and processing functions. Further, by executing whether or not the shading data needs to be updated for each pixel in the entire main scanning direction, highly accurate shading data update control can be realized in consideration of the distribution variation of the reading light source light amount decrease.

  According to the above (6) to (10), an image before or after the shading correction by the shading processing means is performed to constantly monitor the decrease in the light amount of the light source and compensate for the variation in the image data due to the variation in the light amount of the illumination light source. Since it is added to the data, the image data quality by shading correction is kept high. Further, based on the image data obtained by reading the reading object (118) different from the reference white plate, which reflects the light of the illumination light source when the illumination light source is at the position of the sheet-through reading window. Since the fluctuation of the image data due to the fluctuation of the amount of light is compensated, it is necessary to move the illumination light source from the position of the reading window during the image reading by sequentially transferring each of a plurality of sets of documents placed on the document tray. In addition, the reading productivity of a set of a plurality of documents is not lowered. In addition, it is possible to compensate for fluctuations in image data due to fluctuations in the amount of light of the illumination light source by simple calculation without requiring complicated and complicated components and processing functions. Further, by executing the above compensation for each pixel in the entire main scanning direction, it is possible to realize highly accurate shading correction in consideration of the distribution variation of the reading light source light amount decrease.

  Further, according to the above (2) and (7), when the document set detecting means is added and the document set is detected, the shading data is immediately acquired and the reading object (118) is read. The time required to start reading a document (first scan time) can be shortened as much as possible. Further, since the light source is kept on even during the time from the completion of the acquisition of the shading data until the reading start signal that is an original reading instruction is output, naturally the light quantity of the light source gradually decreases. . Therefore, the time elapsed since the document set was detected is measured, and when the predetermined time (Tth) has elapsed, the shading data acquired in advance and the image data read from the reading object (118) are invalidated. When the reading start signal is received, the acquisition of the shading data and the reading of the reading object (118) of (1), (3) to (5) or (6), (8) to (10) are performed again. By doing so, the above problem can be avoided.

  Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

  FIG. 1 shows the external appearance of a multi-function full-color digital copying machine MF1 that is a first embodiment of the present invention. This full-color copying machine is roughly an automatic document feeder (SDF) 20 having an image reading function on the back side of the document, an operation display device 9 (FIG. 2), a color scanner 10, a color printer 30, a paper supply bank. It is composed of 80 units. A LAN (Local Area Network) to which a personal computer PC is connected is connected to the main electrical unit 42 (FIG. 2) which is an image data processing means in the apparatus.

  The printer 30 includes a transfer unit, and the transfer unit includes a transfer belt 31 that is an endless belt. The transfer belt 31 is wound around three support rollers and one tension roller, and is driven to rotate counterclockwise. Near the tension roller, there is a transfer body cleaning unit that removes residual toner remaining on the transfer belt 31 after image transfer.

  On the transfer belt 31 between one support roller and another support roller, Y (yellow), M (magenta), c (cyan) and k (black) colors are formed along the moving direction. An image forming unit is provided, and there is a transfer roller 33 facing each photoconductor drum 32 in the image forming unit with the transfer belt 31 interposed therebetween. Above the image forming unit, there is a laser exposure unit 34 that irradiates each photoconductor drum of each color photoconductor unit with laser light for image formation. The photosensitive drum 32 is uniformly charged by the charging roller 35, and the laser exposed by the laser exposure unit 34 is projected onto the charged surface by the image signal. The electrostatic latent image generated thereby is developed by the developing device 40 into a toner image. This toner image is transferred to the transfer belt 31.

  Below the transfer belt 31 is a transport belt 39. The conveyor belt 39 transfers the toner image on the transfer belt 31 onto a sheet, that is, a sheet. The sheet on which the toner image is transferred (transfer sheet) is sent out to the fixing device 40 by the transport belt 39. Below the conveying belt 39 and the fixing device 40 is a double-sided drive unit 41 that is a sheet reversing unit that feeds a sheet immediately after an image is formed on the front surface and reverses the front and back to record an image on the back surface.

  When the start switch of the operation display device 9 (FIG. 2) (not shown) is pressed, if there is a document on the automatic document feeder (SDF) 20, it is transported onto the contact glass 101 (FIG. 3) of the scanner 10. After that, when there is no document in the SDF 20, the scanner 10 is immediately driven to read the manually placed document on the contact glass, and the first carriage 21 and the second carriage 22 in the scanner 10 are read and scanned. Then, light is emitted from the light source 107 (FIG. 3) on the first carriage 21 to the contact glass, and reflected light from the document surface is reflected by the first mirror on the first carriage 21 toward the second carriage 22. The light is reflected by a mirror on the second carriage 22 and forms an image on a CCD 24 as an image pickup means through an image forming lens 23. Based on the image signal obtained by the CCD 24, each color recording data of Y, M, C, K (Bk) is generated.

  Further, when the start switch is pressed, the rotation driving of the transfer belt 31 is started, the image forming preparation of each unit of the image forming apparatus is started, and the image forming sequence of each color image is started. Thus, an exposure laser modulated based on each color recording data is projected onto the photosensitive drum for each color, and each color toner image is transferred onto the transfer belt 31 as a single image by each color image forming process. When the leading edge of the toner image enters the conveyor belt 39, the sheet is fed from the registration roller pair 38, that is, the feeding roller to the transfer belt 39 at a timing so that the leading edge enters the conveyor belt 39. The toner image on the belt 31 is transferred to the paper. A voltage for transferring toner is applied to the transfer belt 31 by a transfer roller 33. The sheet on which the toner image has moved is sent to the fixing device 40, where the toner image is fixed on the sheet.

  Note that the above-described sheet is selectively rotated by driving one of the sheet feeding rollers immediately above the sheet feeding trays (also referred to as sheet feeding stages or cassettes) 71 to 73 of the sheet feeding bank 80, so that the sheet feeding bank 80 has multiple stages. The sheet is fed out from one of the paper feed trays 81 to 83, separated by one separation roller, put into a vertically arranged transport roller unit, transported upward, and guided to the transport path in the printer 30. The conveying roller 37 conveys the paper to the registration roller pair 38 and stops the front end of the sheet abutting against the registration roller pair 38. Then, the registration roller pair 38 and the conveyance roller 37 are rotationally driven at the timing described above to the conveyance belt 39. It will be sent out. It is also possible to feed paper by inserting paper on the right side manual feed tray. When the user is inserting paper onto the manual feed tray, the printer 30 rotates the paper feed roller of the manual feed tray to separate one sheet on the manual feed tray and pull it into the manual feed path. Stop by hitting 38.

  The paper discharged after receiving the fixing process by the fixing device 40 is guided to a discharge roller by a switching claw and stacked on a paper discharge tray (not shown). Alternatively, it is guided to the double-sided drive unit by the switching claw, reversed there and led again to the transfer position, and the image is recorded also on the back surface, and then discharged onto the paper discharge tray by the discharge roller. On the other hand, residual toner remaining on the transfer belt 31 after image transfer is removed by a transfer body cleaning unit (not shown) to prepare for image formation again.

  When a document is placed on the document feeding table 11 and the start switch is pressed, the document on the feeding table 11 is drawn into the SDF 10 by the rotation of the feeding roller 12, and when performing the back side scanning, the back side reading head 13 is used. The back image is read. The front image is stationary while the document passes between the document guide 118 and the window 102, which are directly behind the platen 14 and opposes the sheet-through reading window 102 (FIG. 3) and has high light reflectance. It is projected onto the CCD 24 and read by the mirrors of the first and second carriages. The document set detection circuit 215 detects the document placement on the document feeder 11. In the embodiment in which the document guide 118 is not provided, the platen 14 is used as a back member that is an object to be read.

  FIG. 2 shows the configuration of the electrical component of the multifunction function copying machine MF1. The scanner 10 includes a CCD 24, an A / D converter, and a circuit for driving them, and generates and outputs digital image data of 8 bits for each RGB from the density information of the original obtained by scanning the set original. The reading head 13 of the SDF 20 includes a CCD in which pixels are distributed in the document width direction, a member for guiding light at each position in the width direction, an A / D converter, and a circuit for driving them, and the density of the document passing immediately before the head. From the information, RGB 8-bit digital image data is generated and output.

  The first image data processing apparatus 1 performs processing for correcting image reading distortion and converting the digital image data from the scanner 10 and the reading head 13 into image data having a predetermined characteristic format. The conversion of the image data format is a format suitable for receiving image data as an output destination. Output image data formats include monochrome binary, gray scale (monochrome multivalue), sRGB, JPEG, Adobe-RGB data, and others.

  The image data whose data format has been converted by the first image data processing device 1 is sent to the bus control device 2. When the bus control device 2 receives the image data from the first image data processing device 1, the bus control device 2 stores it in the memory 4 via the CPU 3. The image data expanded in the memory 4 may be stored and stored in the disk main body of the HDD device 15 as necessary in preparation for re-output. Next, the image data stored in the memory 4 is sent to the second image data processing device 5 via the CPU 3 and the bus control device 2.

  The bus control device 2 is a data bus control device that exchanges various data such as image data and control commands, and also has a bridge function between a plurality of types of bus standards. In this embodiment, the first image data processing device 1, the second image data processing device 5, the CPU 3 and the HDD device 15 are connected by a PCI-Express bus, and the HDD device 70 is connected to the CPU 3 via the bus control device 2. They are connected by a PCI-Express bus.

  The second image data processing device 5 is digital image data whose characteristics predetermined by the first image data processing device 1 are unified, and image data input through the line I / F device 25 or the external I / F device 27. On the other hand, image adjustment / processing and image processing suitable for the output destination designated by the user are performed.

  When receiving the CMYK image data from the second image data processing device 5, the bus control device 2 stores the data in the memory 4 via the CPU 3. The CMYK image data stored in the memory 4 is sent to the printer 30 via the CPU 3 and the printer I / F 8. The printer 30 outputs the received CMYK image data to a transfer sheet. That is, an image appears on the paper with a developer.

  The HDD device 15 is a large-sized storage device for storing electronic data that is also used in a desktop personal computer, and mainly stores an image processing program, digital image data, and accompanying information of the digital image data. In this embodiment, an ATA bus-connected hard disk standardized by expanding IDE is used.

  The CPU 3 is a microprocessor that controls the entire control of the copying machine MF1, and is the main body of the system controller. The memory 4 stores data to be temporarily exchanged in order to absorb a speed difference when bridging between a plurality of types of bus standards and a processing speed difference between connected components themselves, and the CPU 3 performs the digital image processing. It is a volatile memory that temporarily stores programs and intermediate processing data when controlling the apparatus. Since the CPU 3 is required to perform high-speed processing, the system is activated by a boot program stored in the ROM 7 at normal activation, and thereafter, the processing is performed by a program developed in the memory 4 that can be accessed at high speed.

  When the printer 30 receives the digital image data composed of CMYK, the printer 30 outputs the received image data to the transfer paper using an electrophotographic process using a laser beam. Of course, the process used for output can be arbitrarily selected, and may be an ink jet printer that is often used for personal use in recent years.

  S. B. Reference numeral 14 denotes a chip set used for a personal computer, which is a general-purpose electronic device called South Bridge. A bus bridge function often used for constructing a CPU system mainly including PCI-Express and an ISA bridge is formed as a general-purpose circuit. In this embodiment, the ROM 7 is bridged. The ROM 7 is a memory that stores a program (including boot) when the CPU 3 performs image processing control.

  The operation display device 9 is an interface between the copying machine MF1 and a user, and is composed of an LCD (liquid crystal display device) and a key switch. The operation display device 9 displays various states of the device, operation methods and announcements on the LCD, and keys from the user. Detect switch input. In this embodiment, the CPU 3 is connected via a PCI-Express bus.

  The line I / F device 25 is a device that connects a PCI-Express bus and a telephone line. With this apparatus, the machine MF1 can exchange various data via the telephone line.

  The FAX 26 is a general facsimile machine, and exchanges image data with the digital image processing apparatus via a telephone line.

  The external I / F 27 is a device that connects a PCI-Express bus and an external device. With this device, the machine MF1 can exchange various data with the external device. In this embodiment, a network (Ethernet (registered trademark)) and USB are used for the connection I / F. That is, this machine MF1 can be connected to a network or an external medium (such as an SD card) via the external I / F 27 to send image data to the outside or read image data from the outside.

  The PC 28 is a so-called personal computer, and the user performs various controls and input / output of image data with respect to the machine MF1 via application software and drivers installed in the personal computer.

  The external media 29 is a memory device such as a so-called compact flash (registered trademark) card or SD card, and records various electronic data including image data. The user can transfer image data between the MF1 and the memory device. Input / output (read, write) can be performed.

  3A shows a reading optical system of the scanner 10, and FIG. 3B shows an enlarged view around the platen 14 of the scanner 10. As shown in FIG. The scanner 10 includes a contact glass 101 on which a document is mounted, a sheet-through reading window 102, a reference white plate 103 for white level adjustment (gain adjustment) and shading correction data generation, a light source 107 for irradiating the document, and a first mirror 108. On the first carriage 21, the second carriage 110 on which the second mirror 110 and the third mirror 111 are mounted, a home position sensor (hereinafter referred to as HPS) 117 provided for detecting the carriage position, and the CCD 24. A lens unit 23 for image reduction, an image reading circuit 112 equipped with a CCD 24, an image processing circuit (a shading processing unit 113, a light amount fluctuation monitoring unit 114), and a first carriage and a second carriage (not shown). Scanner drive motor 213 (FIG. 4) for driving 21 and 22; Document set detection circuit 215 which includes a support consisting of (Fig. 4) or the like.

  In the above configuration, when the original 105 is mounted on the contact glass 101, the light source 107 is turned on, and the first carriage 21 and the second carriage 22 (hereinafter, the first and second carriages are collectively referred to as a carriage). ) Is scanned in the right direction A by rotating the scanner drive motor 213 (FIG. 4) in response to a control signal from a control unit (CPU 212: FIG. 4) (not shown) to read the image information of the original 105. Then, with the carriage stopped, the light source 107 is turned on, and is conveyed by the platen 14 through the sheet-through reading window 102 to irradiate the original 106 passing between the original guide 118 serving as a back member and the window 102. A sheet-through reading method for reading document image information can be selected.

  In the case of the BOOK scan method in which the original is read by scanning the carriage, the reference white plate 103 is read to obtain the white reading data, and the shading correction data is generated and stored in the memory, and the shading correction is performed. By normalizing the read image data of the original 105 with the use data, the uneven light amount distribution in the main scanning direction and the sensitivity unevenness of the CCD 24 in the apparatus are corrected, and the image information of the original is read with high quality. The image data subjected to the shading correction process is output to the first image data processing apparatus 1 (FIG. 2) of the main electrical unit 42.

  In the case of sheet-through reading in which the original 106 is conveyed and the original image data is read while the carriage is stopped, the carriage is first moved below the reference white plate 103 before reading the original 106 (FIG. 3). (B) (direction of arrow A) The shading correction data is generated, and after returning to the home position Y, the conveyance of the document on the document tray is started, and the document reading operation of the document 106 is started.

  The conveyed document is fed between the document guide 118 and the sheet through reading window 102 by the platen 14 and the support roller 112, and when the reading position (home position) Y is reached, the lower document surface side is illuminated by the light source 107, The reflected light of the document is reflected by the first mirror 108, the second mirror 110, and the third mirror 111 at a predetermined timing, is imaged on the CCD 24 through the lens unit 23, and is photoelectrically converted. When the document passes directly under the document guide 118, the document is sent out on the document discharge tray by the platen 14 and the support roller 113.

  FIG. 4 shows a read data correction circuit of the scanner 10. The original image is irradiated by the light source 107, and the reflected light is read by the CCD 24 mounted on the image reading circuit 112. When the document is read, an analog image signal is output from the CCD 24 to the analog signal processing circuit 202 in synchronization with a CCD drive signal output from a drive timing signal generator (not shown). The analog image signal is subjected to signal processing such as sample hold and signal amplification by a variable gain amplifier in the analog signal processing circuit 202, converted into digital data, that is, image data by the A / D conversion unit 203, and then the subsequent stage. Are output to the shading processing unit 113 or the light amount fluctuation monitoring unit 114.

Image data obtained by reading the reference white plate 103 is input to the shading processing unit 113, averaged in the sub-scanning direction for each pixel by the averaging circuit 205, and stored in the shading data storage unit 206. . The document reading data is subjected to a shading correction calculation based on the shading data stored in the shading storage unit 206 by the shading correction circuit 207 in the shading processing unit 113, and the corrected image data is stored in the main electrical unit 42. Are output to the first image data processing apparatus 1. For example, when outputting image data in 10 bits, the shading correction calculation is as follows.
Dout (n) = {Din (n) / Dsh (n)} × 1023
Dout (n): Data after shading correction
Din (n): Data before shading correction
Dsh (n): performed according to the shading data calculation formula.

  The light amount fluctuation monitoring unit 114 sequentially acquires each time the document reading is completed after reading the first document and the storage unit 208 that holds the back member initial data W′1 for storing the data acquired before the document reading. There are two types of storage units, a storage unit 209 that holds back member data W′m. The light quantity fluctuation monitoring unit 114 is set with a calculation unit 210 that calculates the above-described ratio “W′m / W′1” between W′1 and W′m, and a threshold value W′th that is compared with the ratio. Register 211 is provided. Further, a CPU 212 is provided for outputting control signals for acquiring various data described above, a control signal for the scanner motor 213 that drives the carriage, a control signal for controlling the lighting of the reading light source 204, and the like.

  In most color image reading apparatuses, a light source of white light is used. However, as shown in FIG. 14, the reduction in the amount of light of Red, Green, and Blue shows different characteristics for each color. Therefore, the color image reading apparatus performs processing according to the light quantity fluctuation characteristics of Red, Green, and Blue. Accordingly, when the read data correction circuit (112 to 114) shown in FIG. 4 reads a color image, the various calculation and processing units such as the averaging circuit 205 and the calculation unit 210 have red, green, and blue, respectively. Process for each channel. Further, for the shading data storage unit 206 and the back member data storage unit 209, storage units for three channels of Red, Green, and Blue are prepared.

  FIG. 5 shows a control flow of the CPU 212, and FIG. 6 shows generation timings of input / output control signals of the scanner 10. In FIG. 6, unless otherwise specified, the high level H of the control signal means assert (valid), and L means negate (invalid).

  Receiving the reading start signal output from the main electrical unit 42 (CPU 3 thereof), the CPU 212 turns on the reading light source 204 and outputs a control signal to the motor driving circuit 214 to rotate the scanner motor 213 and perform a reference operation. The carriage is driven in the white plate direction (S401). Note that the reading light source 107 continues to be lit until all document reading is completed. Further, the traveling body speed in FIG. 6 does not indicate a signal level, but simply expresses the speed of the first carriage 21.

  The SHGT signal is asserted at the timing when the carriage starts to be driven and the carriage reaches below the reference white plate 103. Then, the average value of the image data of the same pixel in the main scanning direction for a plurality of lines output from the image reading circuit 112 during the SHGT assert period is calculated by the averaging circuit 205 in the shading processing unit 113, and the average of each pixel is calculated. The value is stored as shading data in the shading data storage unit 206 as the first storage means (S402).

  When the acquisition of the shading data is completed and the carriage is driven backward to return to the home position Y (S403), the CPU 212 asserts the SHGT2 signal in order to acquire the back member initial data W'1 (S404). The CPU 212 outputs a storage unit selection signal (SEL) for instructing whether the data acquired by reading the document guide 118 serving as the back member is stored in the W′1 storage unit 208 or the W′m storage unit 209. And output to the light quantity fluctuation monitoring unit 114. For example, in FIG. 6, when it is desired to store the initial data: W′1 (n), the data obtained by reading the document guide 118 as “H” (storage unit 208 designation) is used as the back member initial data storage unit as the second storage unit. 208 is stored. When the back member data for the second and subsequent times is stored in the back member data storage unit 209, the storage unit selection signal (SEL) is set to “L” (storage unit 209 designation).

  When the acquisition of W′1 is completed, the CPU 212 outputs a document conveyance start signal to a document conveyance unit (not shown). As a result, conveyance of one original from the original tray 11 to the sheet through reading window 102 is started (S405).

  The transport of the document is started, and the SSCAN signal indicating the document area (sub-scanning width) is asserted at the timing when the first document reaches the document reading position Y, and is output by the image reading circuit during the SSCAN signal assertion period. The image data is subjected to shading correction by the shading processing unit 113 and output to the first image data processing apparatus 1 which is an image processing unit at the subsequent stage (S406).

  In step S407 in FIG. 5, when the first original is read, the SSCAN signal is negated, and it is checked whether the original remains on the original table based on the original set detection signal output from the original set detection circuit 215. If no document remains on the document table, the reading operation ends. In S407, if the document remains on the document table, SHGT2 is asserted again and W'2 is acquired until the second document reaches the reading position (S408). At this time, since the CPU 212 switches the SEL signal logic to “L” which is different from the first time and outputs it, W′2 is stored in the back member data W′m storage unit 209.

  FIG. 15 is a diagram illustrating an example of a main scanning distribution of image data obtained by reading a document guide 118 serving as a back member. As shown in FIG. 15, when a reading object having a uniform density is read using a light source that emits the same light amount in the entire main scanning region, in the case of a reduction optical system scanner as shown in FIG. Because of the COS4 law of the lens 23, a phenomenon in which the amount of light is less likely to be transmitted toward the end portion in the main scanning direction occurs, so that the output data is generally lowered on both shoulders. In addition, a decrease in light amount over time of the reading light source 107, such as a rare gas xenon lamp, does not decrease uniformly in the main scanning direction. For this reason, in order to detect the light amount decrease with high accuracy, it is preferable to detect the ratio “W′m / W′1” for each pixel over the entire main scanning region. The ratio is calculated for each pixel.

  When the acquisition of W′2 is completed, the comparison calculation unit in the back member data processing unit calculates the data ratio “W′2 / W′1” between W′1 and W′2 for each pixel (S409). Then, it is determined whether or not there is a pixel whose ratio is smaller than a preset threshold value W′th in the register 211 in the back member data processing unit (S410). Here, the value set in W′th is a set value determined in consideration of a level acceptable as a density difference of document image data in the design and evaluation stages.

  If there is a pixel satisfying W′m (n) / W′1 (n) <W′th, the CPU 212 determines that the light source light amount is greatly decreased and outputs a DFSSTART signal to stop document conveyance. Assert to suspend document reading temporarily, assert a SHSTART signal for updating shading data, reciprocate the carriage again to acquire and update shading data (S401 to S403), and back member initial data : W′1 is also acquired and updated again (S404), and the process proceeds to acquisition of the second document image data.

  On the other hand, when all the pixels satisfy W′m (n) / W′1 (n) ≧ W′th, the conveyance of the document is started again (S405), and the document image data is read (S406).

  Although most of the hardware of the second embodiment is the same as that of the first embodiment, the shading processing unit 113 of the second embodiment includes a data correction unit 601 as shown in FIG. FIG. 8 shows the control flow of the CPU 212 of the second embodiment. Since other components are the same as those in the first embodiment, the description thereof is omitted.

In the data correction unit 601 shown in FIG. 7, the ratio {W′m (n) / W′1 (n)} calculated for each pixel by the calculation unit 210 to the original image data corrected by the shading correction circuit 207. Is multiplied by the coefficient {W′1 (n) / W′m (n)} as a coefficient and output to the first image data processing apparatus 1 (FIG. 2). Therefore, the image data output to the first image data processing apparatus 1 is
Dout (n) = [{Din (n) / Dsh (n)} × 1023] × {W′1 (n) / W′m (n)}
The data follows the formula.

  Since the control flow from S501 to S509 shown in FIG. 8 is the same as that of the first embodiment, description thereof is omitted. In the second embodiment, using {W′1 (n) / W′m (n)} calculated by the calculation unit 210 in S510, the output data from the shading correction circuit 207 is converted into the above calculation formula. The correction calculation is performed accordingly. In step S507, it is checked whether or not a document remains on the document table based on a document set detection signal output from the document set detection circuit 215. When documents remain on the document table, reading of all documents is completed. The shading data correction of S508 to S510 is repeated every time the original is read. Other configurations and functions of the second embodiment are the same as those of the first embodiment.

Note that the original image data corrected by the shading correction circuit 207 is corrected to compensate for fluctuations in the image data due to the light amount fluctuation of the light source. However, the image data before correction by the shading correction circuit 207 may be corrected. I can do it. In this case, the data correction unit 601 is disposed immediately before the shading correction circuit 207, and the reciprocal number {W′m (n) / W′1 (n)} calculated by the calculation unit 210 for each pixel { W′1 (n) / W′m (n)} is used as a coefficient to multiply the original reading image data input to the shading correction circuit 207, and the product is input to the shading correction circuit 207. Also in this case, the image data output to the first image data processing apparatus 1 is
Dout (n) = [{Din (n) / Dsh (n)} × 1023] × {W′1 (n) / W′m (n)}
It becomes.

Most of the hardware of the third embodiment is the same as that of the first embodiment described above, but in the third embodiment, as shown in FIG. 9, a timer for measuring the time elapsed since the document set was detected. 701 is added. The control flow of the CPU 212 of the third embodiment is as shown in FIG. Since other components are the same as those in the first embodiment, the description thereof is omitted.
FIG. 11 shows the generation timing of the input / output control signal of the scanner 10 of the third embodiment.

  In the third embodiment, when a document is set (S801), the reading light source 107 is turned on to acquire shading data (S802 to 804) and back member initial data W′1 is acquired (S805). And stored in the respective storage units. In response to the document set detection signal, the timer 701 starts time measurement.

  In step S806, the CPU 212 confirms whether a predetermined time Tth has elapsed. If the time Tth has elapsed in S806, the light source 107 is turned off (S807), and a reading start command is awaited (S808). Then, after receiving the reading start signal, the CPU 212 performs the same control as the control flow shown in FIG. 5 of the first embodiment.

  In step S806, when the CPU 211 receives a reading start signal in step S808 in a state where the time Tth has not elapsed, a series of operations for acquiring shading data (steps S401 to 403 in FIG. 5) and the initial back member are performed. The data acquisition operation (S404 in FIG. 5) is omitted, and the same control as the control after S405 in FIG. 5 is performed. Other configurations and functions of the third embodiment are the same as those of the first embodiment.

  As shown in FIG. 12, the hardware of the fourth embodiment includes a data correction unit 601 in the shading processing unit, the light amount fluctuation monitoring unit omits the register 211 (FIG. 4), and the document A timer 701 for measuring the time elapsed since the set was detected is added. The control flow of the CPU 212 of the fourth embodiment is as shown in FIG. Since other components are the same as those in the first embodiment, the description thereof is omitted.

  When a document is set (S901), the CPU 212 of the fourth embodiment turns on the reading light source 204 to acquire shading data (S902 to 904), and acquires back member initial data W′1 (S905). ), And stored in each storage unit. In response to the document set detection signal, the timer 701 starts time measurement. In S906, the CPU 212 confirms whether a predetermined time Tth has elapsed.

  In step S906, when the time Tth has elapsed, the light source 204 is turned off (S907), and a reading start command is awaited (S908). Then, after receiving the reading start signal, the CPU 212 performs the same control as the control flow shown in FIG. 8 in the second embodiment.

  In step S906, when the CPU 211 receives a reading start signal in step S908 when the time Tth has not elapsed, a series of operations for acquiring shading data (steps S501 to 503 in FIG. 8) and the first back member are performed. The operation of the data acquisition operation (S404 in FIG. 8) is omitted, and the same control as the flowchart after S505 in FIG. 8 is performed. Other configurations and functions of the fourth embodiment are the same as those of the second embodiment.

1 is a longitudinal sectional view of a copying machine MF1 equipped with an image reading apparatus according to a first embodiment of the present invention. FIG. 2 is a block diagram illustrating a configuration of an electrical component of the multifunction function copying machine MF1 illustrated in FIG. (A) is an enlarged longitudinal sectional view showing the configuration of the image reading optical system of the scanner 10 shown in FIG. 1, and (b) is an enlarged longitudinal sectional view showing the periphery of the platen 14 shown in (a). It is a block diagram which shows the outline | summary of the image reading processing circuit of the scanner 10 shown in FIG. 6 is a flowchart showing an outline of sheet-read reading type image reading control of a CPU 212 shown in FIG. 4. 5 is a time chart showing generation timings of input / output control signals of the image reading processing circuit shown in FIG. 4. It is a block diagram which shows the structure of the image reading process circuit of 2nd Example. It is a flowchart which shows the outline | summary of the image reading control of a sheet | seat through reading system of CPU212 of the image reading processing circuit of 2nd Example. It is a block diagram which shows the structure of the image reading process circuit of 3rd Example. It is a flowchart which shows the outline | summary of the image reading control of a sheet | seat through reading system of CPU212 of the image reading processing circuit of 3rd Example. It is a time chart which shows the generation timing of the input-output control signal of the image reading processing circuit of 3rd Example shown in FIG. It is a block diagram which shows the structure of the image reading processing circuit of 4th Example. It is a flowchart which shows the outline | summary of the image reading control of a sheet | seat through reading system of CPU212 of the image reading processing circuit of 4th Example. 5 is a graph showing the light quantity reduction characteristics of each of Red, Green, and Blue components in a color image reading apparatus using a white light original illumination light source. 4 is a graph showing a level change of one-line image data of a CCD 24 that has read a document guide 118 shown in FIG.

Explanation of symbols

11: Document feeder 12: Feed roller 13: Back side reading head 14: Platen 21: First carriage 22: Second carriage 23: Imaging lens 24: CCD
31: transfer belt 32: photosensitive drum 33: transfer roller 34: laser exposure unit 35: charging roller 39: transport belt 40: developing device 41: double-sided drive unit 101: contact glass 102: sheet through reading window 103: reference white plate 105, 106: Document 107: Light source 108: First mirror 110: Second mirror 111: Third mirror 112: Image reading circuit 118: Document guide

Claims (12)

Document conveying means for conveying the documents on the document tray one by one sequentially across the sheet-through reading window in response to the document reading instruction;
A reference white plate for shading correction at a position different from the position of the reading window;
Illumination light source;
Light source driving means for driving the illumination light source at a window position where the illumination light source faces the reading window and a reference white plate position where the illumination light source faces the reference white plate;
Imaging means for converting incident light into an image signal:
When the illumination light source is at the window position, the reflected light of the original facing the window of the light irradiated by the illumination light source on the reading window is incident on the imaging means, and the illumination light source is at the reference white plate position. Sometimes, optical means for causing the reflected light of the reference white plate of the light irradiated by the illumination light source to the reference white plate to enter the imaging means;
Signal conversion means for converting the image signal converted by the imaging means into image data which is digital data;
Shading processing means for generating shading data based on the image data of the reference white board and storing the shading data in a first storage means, and correcting the shading of the image data of the document based on the shading data of the first storage means;
Before transferring the first sheet of the document loaded on the document tray to the window position, the shading processing unit generates the shading data by illuminating the reference white plate with the illumination light source, and stores the first shading data. The image data of each of the originals loaded in the original tray is stored by the shading processing means, and then the illumination light source is driven to the window position and transferred to the reading window by the original conveying means. First control means for correcting shading; and
When the illumination light source is located at the window position, the light of the illumination light source is reflected and the reading target object different from the reference white plate is monitored. Second control means for driving the illumination light source to the reference white plate position, generating the shading data by the shading processing means, and storing it in the first storage means;
An image reading apparatus comprising: The image reading apparatus further includes a document set detection unit that detects loading of a document on a document tray, and a timer that measures an elapsed time after the document set detection unit detects loading of the document.
The first control means turns on the illumination light source in response to the loading of the document and drives the illumination light source to the reference white plate position, generates shading data based on the image data of the reference white plate, and stores the first storage means. And when the document reading instruction is issued before the elapsed time measurement value of the timer exceeds the set value, the shading processing means corrects the shading of the image data of each document loaded on the document tray. When there is no document reading instruction and the elapsed time measurement value of the timer exceeds a set value, the illumination light source is turned off, and then the illumination light source is turned on in response to the document reading instruction to generate the shading data. Storage in one storage means and the shading correction of document image data;
The image reading apparatus according to claim 1.   3. The back reading member according to claim 1, wherein the another reading object is a back member that faces the reading window and is located at a position opposite to the reading window with respect to the original when the original is being transferred. Image reading device.   The second control means stores the image data of the back member in the second storage means immediately before or immediately after the generation of the shading data by the first control means, and then the document conveying means sequentially from the document tray. Reading the image data of the back member between the tail of the preceding document passing through the reading window and before the leading edge of the succeeding document enters the reading window When the image data of the second storage means is changed in the light amount decreasing direction from the setting ratio, the illumination light source is driven to the reference white plate position, and the shading processing means generates the shading data. The image reading apparatus according to claim 3, wherein the shading data in the first storage unit is updated.   The imaging means converts the entire width of the original in the main scanning direction orthogonal to the sub-scanning direction, which is the document transfer direction, into an image signal for each pixel; the first control means generates the shading data and generates the first shading data for each pixel. The image reading apparatus according to any one of claims 1 to 4, wherein storage in one storage unit and the shading correction are performed; a second control unit monitors a change in the image data for each pixel; Document conveying means for conveying the documents on the document tray one by one sequentially across the sheet-through reading window in response to the document reading instruction;
A reference white plate for shading correction at a position different from the position of the reading window;
Illumination light source;
Light source driving means for driving the illumination light source at a window position where the illumination light source faces the reading window and a reference white plate position where the illumination light source faces the reference white plate;
Imaging means for converting incident light into an image signal:
When the illumination light source is at the window position, the reflected light of the original facing the window of the light irradiated by the illumination light source on the reading window is incident on the imaging means, and the illumination light source is at the reference white plate position. Sometimes, optical means for causing the reflected light of the reference white plate of the light irradiated by the illumination light source to the reference white plate to enter the imaging means;
Signal conversion means for converting the image signal converted by the imaging means into image data which is digital data;
Shading processing means for generating shading data based on the image data of the reference white plate and storing it in a first storage means, and correcting the shading of the image data of the document based on the shading data of the storage means;
Before transferring the first sheet of the document loaded on the document tray to the window position, the shading processing unit generates the shading data by illuminating the reference white plate with the illumination light source, and stores the first shading data. The image data of each of the originals loaded in the original tray is stored by the shading processing means, and then the illumination light source is driven to the window position and transferred to the reading window by the original conveying means. First control means for correcting shading; and
Based on the image data obtained by reading an object to be read that is different from the reference white plate and reflects the light of the illumination light source when the illumination light source is at the window position, image data due to fluctuations in the amount of light of the illumination light source Second control means for applying correction for compensating for fluctuations to image data before or after the shading correction by the shading processing means;
An image reading apparatus comprising: The image reading apparatus further includes a document set detection unit that detects loading of a document on a document tray, and a timer that measures an elapsed time after the document set detection unit detects loading of the document.
The first control means turns on the illumination light source in response to the loading of the document and drives the illumination light source to the reference white plate position, generates shading data based on the image data of the reference white plate, and stores the first storage means. And when the document reading instruction is issued before the elapsed time measurement value of the timer exceeds the set value, the shading processing means corrects the shading of the image data of each document loaded on the document tray. When there is no document reading instruction and the elapsed time measurement value of the timer exceeds a set value, the illumination light source is turned off, and then the illumination light source is turned on in response to the document reading instruction to generate the shading data. Storage in one storage means and the shading correction of document image data;
The image reading apparatus according to claim 6.   8. The back reading member according to claim 6, wherein the another reading object is a back member that faces the reading window and is located on a side opposite to the reading window with respect to the original when the original is being transferred; Image reading device.   The second control means stores the image data of the back member in the second storage means immediately before or immediately after the generation of the shading data by the first control means, and then the document conveying means sequentially from the document tray. Reading the image data of the back member between the tail of the preceding document passing through the reading window and before the leading edge of the succeeding document enters the reading window Using the ratio of the second storage means to the image data, a correction for compensating for fluctuations in the image data due to fluctuations in the amount of light of the illumination light source is added to the image data before or after the shading correction by the shading processing means; Item 9. The image reading apparatus according to Item 8.   The imaging means converts the entire width of the original in the main scanning direction orthogonal to the sub-scanning direction, which is the document transfer direction, into an image signal for each pixel; the first control means generates the shading data and generates the first shading data for each pixel. 10. The storage in one storage means and the shading correction are performed; the second control means performs the correction to compensate for fluctuations in image data due to fluctuations in the amount of light of the illumination light source for each pixel; The image reading apparatus according to one.   The image reading apparatus according to claim 1, further comprising image data processing means for converting the image data subjected to shading correction by the shading processing means into an image data format for image output. The image reading apparatus according to claim 1;
Image forming means for forming an image represented by the image data on a sheet; and
Image data processing means for converting image data output by the image reading device into image data suitable for image forming characteristics of the image forming means and supplying the image data to the image forming means;
An image forming apparatus comprising:

Images