JP2009253919A - Document reading apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a document reading apparatus capable of dealing with variation in the quantity of light even without switching a background plate positioned on a document reading plane before reading a document when reading the document by means of a linear image sensor while distinguishing the document from a background. <P>SOLUTION: A document reading apparatus 41 comprises: a first regional part 95 in black that is read by a linear image sensor simultaneously with a document, in order to distinguish the document from a background; a second regional part 97 in white, provided at a position with the first regional part 95 side by side along a main scanning direction 93, that is read by the linear image sensor in order to acquire light quantity data; and a correction part which utilizes shading correction data and the light quantity data to perform shading correction upon image data obtained by reading the document. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a document reading apparatus that reads a document with a linear image sensor, and more particularly to shading correction.

  As a document reading device, a document size detection blackboard and a shading correction white reference plate are arranged side by side so as to be movable in the sub-scanning direction, and the blackboard and the white reference plate are switched in accordance with the reading of the document and the acquisition of shading correction data. There are some (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 6-189075 (paragraphs 0022 to 0024, paragraphs 0029 to 0030, FIGS. 3, 4, and 6)

In this apparatus, a plurality of documents fed one by one from the automatic document feeder are read by the following steps.
(1) Shading correction data is acquired by irradiating the white reference plate located on the original reading surface (contact glass) with light and reading the white reference plate.
(2) The board located on the original reading surface is switched from the white reference board to the blackboard.
(3) The first original and the blackboard are read by irradiating light to the first original sent to the original reading surface with the blackboard positioned on the original reading surface.
(4) The board located on the original reading surface is switched from the blackboard to the white reference board.
(5) Shading correction data is acquired by irradiating the white reference plate located on the original reading surface with light and reading the white reference plate. That is, the same step as (1) is performed.
(6) The plate located on the document reading surface is switched from the white reference plate to the blackboard. That is, the same step as (2) is performed.
(7) The second original and the blackboard are read by irradiating the second original sent to the original reading surface with the blackboard positioned on the original reading surface. That is, the same step as (3) is performed for the second original.
Repeat steps (4) to (7) for the third and subsequent originals.

  The above apparatus distinguishes the original from the background by using a blackboard background, thereby detecting the original size. In consideration of the fact that the amount of light from the light source is not constant and fluctuates, the above apparatus acquires shading correction data for each document before reading the document.

In the above apparatus, when reading a plurality of documents, the background plates (blackboard and white reference plate) positioned on the document reading surface are switched before reading each document.
The object of the present invention is to change the amount of light without changing the background plate located on the original reading surface before reading the original when the original is read by the linear image sensor while distinguishing the original from the background. An object of the present invention is to provide a document reading apparatus that can handle this.

  An original reading apparatus according to the present invention includes a linear image sensor, a first area portion that is read simultaneously with the original by the linear image sensor to distinguish the original from the background, and a main scanning direction of the linear image sensor. Along the first region portion, the second region portion that is read by the linear image sensor, the shading correction data, and the second region. A correction unit that performs shading correction on the image data obtained by reading the original by using the light amount data obtained by reading the region part.

  The document reading apparatus according to the present invention may include an automatic document feeding unit that automatically feeds the document to a position where reading by the linear image sensor is performed.

  The present invention is particularly effective when a large number of documents are read at high speed using the automatic document feeder.

  In the document reading apparatus according to the present invention, the size of the first region in the main scanning direction defines the size of the background in the main scanning direction, and the second region in the main scanning direction. The part may be located outside the background.

  According to this, it is possible to read the second area portion without causing any trouble in distinguishing between the document and the background.

  The document reading apparatus according to the present invention is movable in the sub-scanning direction with the third area portion read by the linear image sensor in order to acquire shading correction data. And a carriage that moves to a position where the second area can be read and moves to a position where the third area can be read when the shading correction data is acquired in advance. Can do.

  According to this, since the reading of the first and second area portions and the reading of the third area portion are selected not by moving the area portions but by moving the carriage, the area portions are moved. It is not necessary to provide a mechanism for making it.

  In the document reading apparatus according to the present invention, the third area portion may be adjacent to the first and second area portions in the sub-scanning direction.

  According to this, it is possible to shorten the time for switching between reading of the first and second area portions and selection of reading of the third area portion.

  In the document reading apparatus according to the present invention, when the linear image sensor reads a plurality of documents, the shading correction data is commonly used for the plurality of documents, and the plurality of documents are read. In order to suppress the occurrence of a difference in image quality between the originals, the correction unit can perform the shading correction on the image data of each original.

  According to this, when a plurality of originals are read by the linear image sensor while distinguishing the original from the background, the difference in image quality when the plural originals are read is different between the originals (for example, the first original and the last original). Can be suppressed from occurring between documents.

  In the document reading apparatus according to the present invention, the correction unit performs the shading correction on the image data in order to suppress a difference in image quality when the document is read between the lines of the document. be able to.

  According to this, it is possible to suppress a difference in image quality when the original is read between lines of the original (for example, between the first line and the last line).

  According to the present invention, when the original is read by the linear image sensor, the first and second area portions are read. The original and the background are distinguished by reading the first area portion. The light amount data is acquired by reading the second region portion. Then, the shading correction is performed on the image data obtained by reading the document by using the light amount data and the shading correction data. The first region portion and the second region portion are provided side by side along the main scanning direction. As described above, according to the present invention, when reading a document with a linear image sensor while distinguishing the document from the background, the amount of light can be reduced without switching the background plate located on the document reading surface before reading the document. Can handle fluctuations.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration of a multifunction machine 1 including a document reading apparatus according to the present embodiment. The multifunction device 1 has functions of a copy, a facsimile, a scanner, and a printer.

  The MFP 1 includes an MPU (Micro Processing Unit) 3, a linear image sensor 5, an image recording unit 7, a display unit 9, an operation unit 11, a modem 13, an NCU (Network Control Unit) 15, a ROM (Read Only Memory) 17, A RAM (Random Access Memory) 19, an image memory 21, a codec 23, a LAN (Local Area Network) interface 25, and the like are connected to each other via a bus 27. The MPU 3 controls the hardware constituting the multifunction device 1 and executes software necessary for the operation of the multifunction device 1.

  The linear image sensor 5 is also called a line sensor or a one-dimensional sensor, and reads a document (characters, drawings, photographs, etc.) and outputs it as image data. The linear image sensor 5 includes a CCD (Charge Coupled Device) type and a CMOS type (Complementary Metal Oxide Semiconductor). The image recording unit 7 is an electrophotographic printer or the like, and returns image data output from the linear image sensor 5, image data from another facsimile machine received by facsimile communication, and the like to record the image. Output paper.

  The display unit 9 displays the operation state of the multifunction device 1 and various setting contents. The display unit 9 is realized by an LCD (Liquid Crystal Display), a CRT (Cathode Ray Tube), or the like. The operation unit 11 includes keys (such as a numeric keypad, a start key, a reset key, and various function keys) necessary for operating the multifunction device 1.

  The modem 13 has a function of a facsimile modem for normal facsimile communication. The modem 13 is directly connected to the NCU 15. The NCU 15 has a function of closing and opening the public telephone line 29, a function of sending a dial pulse corresponding to a telephone number of a communication partner, and a function of detecting an incoming call. The NCU 15 connects the modem 13 to the public telephone line 29 as necessary.

  The ROM 17 is realized by a flash memory or the like, and stores software necessary for the operation of the multifunction machine 1. The RAM 19 is realized by an SRAM (Static Random Access Memory), a DRAM (Dynamic Random Access Memory), or the like. The RAM 19 is used for temporary storage of data generated during execution of software, storage of application software, and the like.

  The image memory 21 is realized by a DRAM or the like, and temporarily stores image data to be transmitted, received image data, image data output from the linear image sensor 5, and the like.

  The codec 23 encodes and compresses the image data and decodes the encoded and compressed image data. The LAN interface 25 is an interface through which the multifunction device 1 is communicably connected to the LAN 31.

  FIG. 2 is a diagram illustrating a main configuration of the document reading device 41 according to the present embodiment. The document reading device 41 constitutes a part of the multifunction machine 1 shown in FIG. 1, and is used when using a copy function, a scanner function, and a facsimile transmission function.

  The document reading device 41 includes a main body 43 and an automatic document feeder 45. First, the main body 43 will be described. The main body 43 has a surface facing the automatic document feeder 45. This surface is constituted by a document reading surface 47, a document table 49, and light shielding frames 51 and 53. The document reading surface 47 is an elongated glass plate extending in the main scanning direction of the linear image sensor 5 (the direction perpendicular to the paper surface in FIG. 2), and is used in the automatic document feeding method. The document table 49 is a glass flat plate and is a table used in the flat bed scanner system.

  The document reading surface 47 is supported by the frames 51 and 53. The document table 49 is supported by the frame 53. The frame 53 has a curved document feeding surface 55, and has an extending portion 57 that extends from the document feeding surface 55 onto the document table 49. An area member 59 is sandwiched between the extension portion 57 and the document table 49. The area member 59 is a white member extending in the main scanning direction, and serves as a third area portion that is read by the linear image sensor 5 in order to acquire shading correction data.

  Inside the main body 43, a carriage 61, which is a document reading unit, is arranged. The carriage 61 is movable in the sub-scanning direction 63 by a driving mechanism (not shown).

  The carriage 61 includes a linear image sensor 5, a light source 65, a mirror 67 and a lens 68. These extend in the main scanning direction. In FIG. 2, the light 69 emitted from the light source 65 passes through the document reading surface 47 and is reflected by the document 71, passes again through the document reading surface 47, is reflected by the mirror 67, passes through the lens 68, and is linear image. A state in which light is received by the sensor 5 is shown.

  Next, the automatic document feeder 45 will be described. A plurality of conveyance rollers 81 are arranged inside the automatic document feeder 45. The document 71 is sandwiched by the rotating transport roller 81, and the document 71 is automatically fed along a transport path 83 from the paper feed tray to the paper discharge tray.

  A back surface 85 of the automatic document feeder 45 faces the main body 43. A document exit portion 87 and a document entrance portion 89 are formed in the vicinity of the back surface 85 facing the document reading surface 47. The document 71 that is automatically fed through the conveyance path 83 once exits from the document exit portion 87, passes through the document reading surface 47, is guided by the document feeding surface 55, and is documented from the document inlet portion 89. It enters the automatic feeding section 45 and is sent to the paper discharge tray.

  The automatic document feeder 45 has an area member 91 disposed on the back surface 85 so as to face the document reading surface 47. The region member 91 will be described in detail. FIG. 3 is a cross-sectional view taken along the line AA of FIG. FIG. 4 is a plan view of the region member 91.

  The region member 91 is a member constituted by a first region portion 95 extending in the main scanning direction 93 and second region portions 97 located on both sides thereof. The dimension 99 in the main scanning direction 93 of the first region 95 defines the dimension in the main scanning direction 93 of the background. The first area portion 95 is a black area, and is read by the linear image sensor 5 simultaneously with the original 71 in order to distinguish the original 71 from the background when the original 71 is read by the linear image sensor 5. In order to distinguish between the document 71 and the background, the dimension 101 in the main scanning direction 93 of the document passage area is made smaller than the dimension 99.

  The second area 97 is a white area provided at a position along the main scanning direction 93 along with the first area 95. The second area 97 is read by the linear image sensor 5 in order to acquire light amount data. In the main scanning direction 93, the second region 97 is located outside the background. Therefore, the second region 97 can be read without causing any trouble in distinguishing between the document 71 and the background.

  The first area portion 95 and the second area portion 97 are simultaneously read by the linear image sensor 5. Therefore, in the main scanning direction 93, the size of the region member 91 is substantially the same as or larger than the size 103 of the readable region of the linear image sensor 5.

  Next, shading correction in the document reading device 41 will be described. Image data obtained by reading the document 71 is subjected to shading correction to prevent the peripheral portion of the image from becoming darker than the original. FIG. 5 is a graph showing an example of shading correction data of the linear image sensor 5. The horizontal axis indicates the order from the first pixel 111 constituting the linear image sensor 5. The number of pixels 111 of the linear image sensor 5 is 7500. The vertical axis represents shading correction data (in other words, correction coefficient). The shading correction data is, for example, a standard white density value for each pixel 111. Shading correction data is assigned to each of the first, second,..., 7500th pixels 111.

The following equation is applied to the reading value (input value) at each pixel 111 when the linear image sensor 5 reads the document 71 to perform shading correction.
Reading value x (maximum density value / shading correction data)
The maximum density value is, for example, 255. This is the maximum density value when the density value is expressed by 8 bits. 0 indicates the darkest and 255 indicates the brightest.

  As can be seen from the above equation, even if the read value is small, the corrected value can be increased by reducing the shading correction data. Since the peripheral portion of the image becomes darker than the original, the shading correction data is reduced near both ends of the linear image sensor 5 as shown in FIG.

  By the way, when reading a plurality of documents 71 by the linear image sensor 5, especially when a large number of documents 71 are continuously read by the automatic document feeding method, the light source 65 is turned on during the period from the start to the end of reading. Since it continues, the temperature of the light source 65 rises. Therefore, the light quantity from the light source 65 gradually decreases during the period. Therefore, if the image data is subjected to shading correction using the same (common) shading correction data, even if the image data of each original 71 can be corrected for shading, the difference in image quality when reading a plurality of originals 71 is different between the originals 71. Will occur. In other words, there arises a problem that the image quality when the original 71 is read differs for each original 71.

  In this embodiment, when reading a plurality of documents 71 by the linear image sensor 5, the reading of each document 71 is performed by reading the second area 97 by the linear image sensor 5 during the reading of each document 71. The light quantity data in is acquired. FIG. 6 is a diagram illustrating an example of the light amount data. The horizontal axis indicates the first original 71, the second original 71, and so on. The vertical axis represents the light amount data. As the light quantity data, for example, a density value can be used. When the density value is expressed by 8 bits, 0 is the darkest and 255 is the brightest.

  As can be understood by comparing the light quantity data during reading of the first original 71, the second original 71,..., The 100th original 71, that is, during each reading, the light source 65. Therefore, the light amount data decreases as the subsequent document 71 is reached.

  For example, the shading correction data in FIG. 5 is set as common shading correction data. The shading correction data shown in FIG. 5 is applied to the image data of the first original 71. For the image data of the second and subsequent originals 71, the shading correction data in FIG. 5 shifted downward, that is, the value becomes smaller, is applied as the shading correction data.

  The shift amount is a value with which the same density value can be obtained for the area of the same density in the original 71 and the first original 71. In other words, the image quality of the document 71 is a value that is the same as the image quality of the first document 71. As an example, the shift amount is determined based on the light amount data during reading of the original 71 and the light amount data during reading of the first original 71. For example, if the light amount data decreases by “3”, the shading correction data is shifted downward by “3”. As a shift method, there are a method of lowering shading correction data for all the pixels 111 by a certain rate (for example, 2.5 percent) and a method for lowering the shading correction data by a certain value (for example, 3).

  Although the color of the second region 97 has been described by taking white as an example, other colors (for example, light yellow) may be used as long as the light amount data can be acquired from the second region 97. The timing of reading the second area 97 is not limited to the time when the original 71 is being read, and may be during the period from when the reading of the original 71 is completed until the reading of the next original 71 is started.

  As described above, in this embodiment, in order to suppress a difference in image quality between the documents 71 when a plurality of documents 71 are read, the shading correction data and the second region 97 are obtained by reading the common shading correction data. The shading correction is performed on the image data of each document 71 using the obtained light amount data. The correction unit that executes this correction includes the MPU 3, the ROM 17, the RAM 19, and the image memory 21 shown in FIG.

  Next, a process for continuously reading a plurality of originals 71 by the automatic original feeding method in the original reading apparatus 41 of FIG. 2 will be described. A plurality of documents 71 are set on the paper feed tray of the automatic document feeder 45, various settings (resolution and other settings) are made as necessary, and a start key provided on the operation unit 11 in FIG. 1 is operated. .

  The carriage 61 moves in the sub-scanning direction 63 to a position where the area member 59 (that is, the third area portion made of a white member) can be read. By irradiating light 69 from the light source 65 toward the region member 59 and reading the region member 59 by the linear image sensor 5, common shading correction data is acquired in advance. Note that the size of the region member 59 in the main scanning direction is larger than the size 103 of the readable region of the linear image sensor shown in FIG. Thereby, shading correction data can be acquired.

  After acquiring the common shading correction data, the carriage 61 moves in the sub-scanning direction 63 to a position where the area member 91 (the first area portion 95 and the second area portion 97) can be read. With the light 69 from the light source 65 applied to the area member 91, the document 71 is fed one by one to the document reading surface 47 by the automatic document feeder 45, and the document 71 is continuously read by the linear image sensor 5. Reading using the automatic document feeder 45 in this embodiment is a so-called sheet-through method, and reading is performed by moving the document 71 while the carriage 61 is fixed.

  In reading each document 71, the black first area 95 overlapping the document 71 on the document reading surface 47 is read simultaneously with the document 71 by the linear image sensor 5 to distinguish the document 71 from the background. Thus, in the present embodiment, the skew angle of the document 71 is detected to correct the skew angle of the image data of the document 71 so that the image is not inclined. The distinction between the document 71 and the background can also be used to detect the document size.

  Then, the shading correction is performed on the image data obtained by reading each original 71 by the method described above.

  As described above, according to the present embodiment, when the linear image sensor 5 reads a plurality of documents 71, the first region portion 95 and the second region portion 97 are read while each document 71 is being read. Reading. By reading the first area portion 95, the document 71 and the background are distinguished. By reading the second area portion 97, light amount data during reading of the document 71 is acquired. Then, the shading correction is performed on the image data of each document 71 using the common shading correction data acquired in advance by reading the light amount data and the region member 59 (third region portion). Thereby, it is possible to suppress a difference in image quality between the documents 71 when a plurality of documents 71 are read due to fluctuations in the amount of light. The first region portion 95 and the second region portion 97 are provided side by side along the main scanning direction 93.

  As described above, according to the present embodiment, when the linear image sensor 5 reads a plurality of documents 71 while distinguishing the document 71 from the background, the document 71 is positioned on the document reading surface before each document 71 is read. Even if the background plate is not switched, it is possible to cope with fluctuations in the amount of light. In addition, since it is not necessary to switch the background plate located on the document reading surface before reading each document 71, the time until the start of reading can be shortened.

  In the present embodiment, the shading correction is performed for the light amount decrease caused by continuing to turn on the light source 65. As described above, the shading correction is performed on the image data of each document 71 by using the light amount data obtained by reading the second region 97 and the common shading correction data. Therefore, in this embodiment, shading correction is performed simultaneously with respect to the temporal decrease in the amount of light from the light source 65. Therefore, in order to perform shading correction for a decrease in light amount with time, an operation of switching the background plate before reading each document 71 or moving the carriage 61 to the position of the white reference plate to acquire shading correction data becomes unnecessary. Time to start reading can be shortened.

  As shown in FIG. 3, in the present embodiment, the second region 97 is provided on the document reading surface 47 at a position that does not overlap the document 71. Therefore, the reading of the second area 97 can be performed at the same time as the reading of the document 71, before the reading of the document 71, or after the reading of the document 71 is completed. Therefore, it is possible to improve the degree of freedom of timing for acquiring the light amount data.

  Due to fluctuations in the amount of light, a difference in image quality when the document 71 is read may occur between lines of the document 71 (for example, between the first row and the last row), in other words, a difference in image quality may occur in the sub-scanning direction 63. In the aspect described next to the present embodiment, it is possible to suppress the occurrence of the image quality difference. In this aspect, the shading correction is performed on the image data in the same manner as described above using the shading correction data acquired in advance or set in advance and the light amount data in each line.

  According to this aspect, when the original 71 is read by the linear image sensor 5 while distinguishing the original 71 from the background, it is possible to suppress a difference in image quality between the lines when the original 71 is read. . Also in this aspect, if the shading correction data is set in advance, it is not necessary to switch the background plate located on the original reading surface before reading the original 71, so that it is possible to shorten the time until the start of reading.

  In the present embodiment, as an example that can cope with fluctuations in the amount of light, it is possible to eliminate the influence of a decrease in the amount of light from the light source 65. As another example that can deal with fluctuations in the amount of light, there are cases where the amount of light from the light source 65 increases or decreases without being stabilized.

  The automatic document feeder 45 is a device that automatically feeds a document 71 to a position where the linear image sensor 5 performs reading (document reading surface 47). When this apparatus is used to read a large amount of originals, a problem that the amount of light from the light source 65 is reduced becomes large. Therefore, this embodiment is particularly effective when a large amount of documents are read at high speed using the automatic document feeder 45.

  According to the present embodiment, when reading the document 71, the carriage 61 is moved to a position where the area member 91 (the first area portion 95 and the second area portion 97) can be read. Further, when the common shading correction data is acquired in advance, the carriage 61 is moved to a position where the area member 59 (third area portion) can be read. As described above, the reading of the first area portion 95 and the second area portion 97 and the selection of reading of the third area portion are performed by the movement of the carriage 61 instead of the movement of these area portions. There is no need to provide a mechanism for moving the area portion. Note that the area member 91 and the area member 59 may be moved to positions that can be read by the linear image sensor 5.

  In the present embodiment, the common shading correction data is acquired before the reading of the document 71 is started. However, the common shading correction data is set in advance at the time of shipment of the multifunction machine 1 including the document reading device 41. You may do it.

  Next, an embodiment using a flatbed scanner system will be described. FIG. 7 is a perspective view showing an appearance of the document reading apparatus 41 according to the present embodiment. The document reading device 41 includes a main body 43 having an operation panel 121 and an automatic document feeder 45 provided to be openable and closable with respect to the surface of the main body 43 having a document reading surface 47 and a document table 49. The operation panel 121 is provided with the display unit 9 and the operation unit 11 shown in FIG.

  On the back surface 85 of the automatic document feeder 45, a first region 123 having a size covering the document table 49 and a second region 125 having the same size as the second region 97 are provided. ing. The second region portion 125 is located outside each side along the sub-scanning direction 63 of the first region portion 123. In other words, the second region 97 is provided at a position along the main scanning direction 93 along with the first region 123. In the flatbed scanner method, the first area portion 123 has the same function as the first area portion 95, and the second area portion 125 has the same function as the second area portion 97.

  In the flatbed scanner method, a document is placed on the document table 49, the automatic document feeder 45 is closed, and a start key is operated to perform reading. In the flatbed scanner method, reading is performed while moving the carriage 61 in the sub-scanning direction 63.

  Even in the flatbed scanner system, when reading a large amount of documents, it is necessary to continuously repeat the operation of setting the documents on the document table 49 and operating the start key. For this reason, since the temperature of the light source 65 rises and the problem that the light quantity from the light source 65 falls arises, this invention becomes effective. According to the embodiment using the flatbed scanner method, similarly to the embodiment of the automatic document feeding method, it is possible to solve the problem that the amount of light from the light source 65 decreases with time.

  As shown in FIG. 2, the document reading apparatus 41 according to the present embodiment separates the region member 91 (first region portion 95 and second region portion 97) from the region member 59 (third region portion). However, these may be adjacent to each other along the sub-scanning direction 63. FIG. 8 is a plan view showing the region member 91 and the region member 59 in this mode. In the embodiment of FIG. 8, the area member 91 and the area member 59 are arranged at the location of the area member 91 in FIG. According to the mode of FIG. 8, since the area member 91 and the area member 59 are adjacent to each other, the reading of the first area 95 and the second area 97 and the reading of the third area (area member 59) are performed. The time for switching between selections can be shortened.

  In the present embodiment, as shown in FIG. 4, the second region 97 is provided on both sides of the first region 95, but only one side may be provided.

  In addition, as shown in FIG. 9, the first region portion 95 may be arranged on both sides of the second region portion 97 along the main scanning direction 93. In the aspect of FIG. 9, the second region 97 is disposed in the center. If there is the second area portion 97 at this position, the second area portion 97 does not overlap the edge of the document 71, so that the distinction between the document 71 and the background is not hindered. According to the aspect of FIG. 9, the dimension of the linear image sensor 5 in the main scanning direction 93 can be reduced. Note that the position of the second region 97 is not limited to the center of the region member 91, and the document 71 having a size that can be read by the document reading device 41 may be any position where the edge does not pass through the document 71 of any size. . In the aspect of FIG. 9, since the original 71 and the second region 97 overlap, the light amount data cannot be acquired while the original 71 is being read. For this reason, it is necessary to acquire the light amount data during the period from the end of reading of the original 71 to the start of reading of the next original 71.

1 is a block diagram illustrating a configuration of a multifunction machine 1 including a document reading device 41 according to the present embodiment. It is a figure which shows the main structures of the original reading apparatus 41 concerning this embodiment. It is a figure which shows the AA cross section of FIG. FIG. 5 is a plan view of a region member 91 composed of a first region part 95 and a second region part 97. 4 is a graph showing an example of shading correction data of the linear image sensor 5. It is a figure which shows an example of the light quantity data obtained by reading the 2nd area | region part 97 during reading of each original. FIG. 2 is a perspective view illustrating an appearance of a document reading device 41 according to the present embodiment. It is a top view of the aspect which arranged the region member 91 and the region member 59 side by side. It is a top view of the area member 91 of the aspect which has arrange | positioned the 2nd area | region part 97 in the center part, and has arrange | positioned the 1st area | region part 95 in the both sides.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... MFP, 3 ... MPU, 5 ... Linear image sensor, 7 ... Image recording part, 9 ... Display part, 11 ... Operation part, 13 ... Modem, 15 ... NCU, 17 ... ROM, 19 ... RAM, 21 ... Image memory, 23 ... Codec, 25 ... LAN interface, 27 ... Bus, 29 ... Public telephone line , 31... LAN, 41... Document reading device, 43... Main body, 45... Automatic document feeder, 47. .. Frame, 55... Document feeding surface, 57... Extension part, 59... Area member (third area part), 61. ..Light source, 67 ... mirror, 68 ... lens, 69 ... light, 71 ... original, 81 Conveyance roller, 83... Conveyance path, 85 .. Back surface, 87... Document exit portion, 89... Document entry portion, 91. ... First area portion 97... Second area portion 99... Dimensions in the main scanning direction of the first area portion 101... Dimensions in the main scanning direction of the document passage area 103. ..Dimension of readable area of linear image sensor, 111... Pixel, 121... Operation panel, 123... First area portion, 125.

Claims (7)

A linear image sensor,
A first area that is read simultaneously with the original by the linear image sensor to distinguish the original from the background;
A region part provided at a position aligned with the first region part along the main scanning direction of the linear image sensor, and a second region part read by the linear image sensor to obtain light amount data; ,
An original reading apparatus comprising: a correction unit that performs shading correction on image data obtained by reading the original using shading correction data and light amount data obtained by reading the second area.   The document reading apparatus according to claim 1, further comprising an automatic document feeding unit that automatically feeds the document to a position where reading by the linear image sensor is performed. The size of the first region portion in the main scanning direction defines the size of the background in the main scanning direction,
3. The document reading apparatus according to claim 1, wherein the second region portion is located outside the background in the main scanning direction. A third region read by the linear image sensor to obtain shading correction data;
It is movable in the sub-scanning direction, moves to a position where the first and second area portions can be read when reading the original, and the third area portion when acquiring the shading correction data in advance. A document reading apparatus according to any one of claims 1 to 3, further comprising a carriage that moves to a position where the document can be read.   The document reading apparatus according to claim 4, wherein the third area portion is adjacent to the first and second area portions in the sub-scanning direction. When reading a plurality of originals with the linear image sensor, the shading correction data is commonly used for the plurality of originals,
The correction unit performs the shading correction on the image data of each document in order to suppress a difference in image quality between the documents when the plurality of documents are read. The document reading device described in the item.   The said correction | amendment part performs the said shading correction | amendment about the said image data, in order to suppress that the image quality difference at the time of reading the said document arises between the lines of the said document. Document reading device.

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