JP2012199798A - Image reader, and control method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that the color of a background member used in a conventional image reader is divided into white and black each having disadvantages, respectively, and since a user must switch or set the switching of the white part and the black part of the background member according to a document to be read, efficiency of image reading operation is low.SOLUTION: A determination means for determining the type of a document is disposed on the upstream side of an image reading position in the conveyance direction of the document, and the color of a background member is switched based on the results from the determination means. Consequently, switching can be made to a background member suitable for the document without requiring the operation by the user.

Description

  The present invention relates to an image reading apparatus that prevents show-through of a read image or a decrease in contrast. The present invention also relates to an image reading apparatus that prevents the show-through of the read image and the ground cover and detects the inclination and size of the document.

  In a conventional image reading apparatus, light is emitted from an image reading sensor arranged on the same side as the image reading unit with respect to the document arranged between the image reading unit and the background member with the image reading unit facing the document side. Irradiate. The image information is acquired by the image reading unit reading the reflected light. Further, the color of the background member used in the image reading apparatus is roughly classified into white and black, and each has the following disadvantages. When the background member is white, after the light irradiated on the original passes through the original, it is reflected by the background member, passes through the original again from the back side, and enters the image reading means. In this case, if a high-density image exists on the back side of the document, so-called show-through or lowering of the image density occurs where the image on the back side is seen through the surface to be read, and the image quality is significantly reduced. End up. On the other hand, when the background member is black, the intensity of light incident on the image reading unit from the document side is easily influenced by the light transmittance of the document. For example, in the case of a document having a high light transmittance such as a second original drawing sheet, the intensity of light incident on the image reading means is reduced, the entire image is darkened, and the contrast of the image is deteriorated.

  Therefore, the background member is formed with a white portion and a black portion, and provided with means for allowing the user to switch the background member according to the manuscript (for example, Patent Document 1) or based on the reading setting designated by the user. There has been proposed one in which background members are automatically switched (for example, Patent Document 2). Further, there has been proposed a detector that acquires light transmittance on the upstream side in the document transport direction of the image reading apparatus, and controls light intensity or corrects image information based on the detected transmission amount. (For example, Patent Documents 3 and 4).

  Also, a white area portion having a width corresponding to a plurality of document sizes and white is applied to the background member, and a black area portion having a predetermined width on the outer side in the width direction of the white area and black. A technique using a background member formed with a predetermined length in the scanning direction is disclosed. This is because the background members are formed in the number corresponding to the number of document sizes in the sub-scanning direction, the background portion corresponding to the document size is positioned at the reading position, and the inclination of the document is detected based on the reading result. As a result, there has been proposed an apparatus that detects the inclination and size of a document while improving the quality of a read image (for example, Patent Document 5).

JP 2000-244718 A JP-A-7-84423 JP 2006-93791 A JP 2008-11450 A JP 2004-282151 A

  However, the image reading apparatuses described in Patent Documents 1 and 2 must switch or set the white portion and the black portion of the background member according to the original that the user himself / herself reads. For this reason, there is a problem that the user is troublesome and the efficiency of the image reading operation is poor. In the image processing apparatuses described in Patent Documents 3 and 4, the light intensity is controlled or the image information is corrected based on the transmission amount of the document and the color of the background member. It must switch or set the white and black portions of the background member. Therefore, these patent documents also have a problem that the efficiency of the image reading operation is poor. Also in the image processing apparatus described in Patent Document 5, the user himself / herself must switch or set the white portion and the black portion of the background member, and the same problem occurs. In addition, in Patent Document 5, it is possible to detect the inclination and size of an original for paper having a predetermined width, but it is not possible to detect the inclination and size of an original for paper of an irregular size.

  The present invention has been made paying attention to this point, and provides an image reading apparatus that prevents show-through or contrast reduction of a read image and improves the quality of the read image.

  In order to achieve the above object, the present invention has the following configuration. That is, an image reading apparatus including a conveying unit that conveys a document and a reading unit that reads the document at a predetermined reading position, and is arranged to face the reading unit and has a plurality of background colors as a background of the document A background member that includes: a determination unit that determines a type of the document; and a control unit that switches a background color of the background member when the reading unit reads the document based on the document type determined by the determination unit. And have.

  Moreover, this invention has the following structures as another structure. That is, a control method of an image reading apparatus including a conveying unit that conveys a document and a reading unit that reads the document at a predetermined reading position, and is disposed opposite to the reading unit and serves as a background of the document A background member having a plurality of background colors, the control unit determines the type of the document, and determines the background color of the background member when the reading unit reads the document based on the determined document type; Switch.

  According to the present invention, it is possible to acquire a high-quality image with high efficiency of the image reading operation and preventing the show-through or contrast reduction of the read image.

6 is a flowchart of an image reading operation according to the first embodiment. FIG. 3 is a schematic side sectional view illustrating a configuration example of the image reading apparatus according to the first embodiment. FIG. 3 is a block diagram showing electrical connection of the image reading apparatus according to the first embodiment. 10 is a flowchart of an image reading operation according to the second embodiment. 10 is a flowchart of an image reading operation according to the third embodiment. 10 is a flowchart of an image reading operation according to a fifth embodiment. The block diagram which shows the electrical connection of the image reading apparatus which concerns on 5th embodiment. Schematic explaining the detection method of the main scanning (width) direction of the document size which concerns on 5th embodiment. Schematic explaining the detection method of the sub-scanning (length) direction of the document size which concerns on 5th embodiment. Schematic explaining the detection method of the inclination of the conveyed document which concerns on 5th embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

<First embodiment>
[Equipment configuration]
FIG. 2 is a schematic side sectional view showing a configuration example of the image reading apparatus 200 according to the first embodiment of the present invention. Hereinafter, each part of the image reading apparatus 200 will be described. A document 201 is a document to be scanned. The document table 202 stacks documents 201. The pickup roller 204 feeds the document 201. The feed roller 206 conveys the document 201. The separation roller 211 feeds one by one when there are a plurality of documents 201. Further, the image reading apparatus 200 includes a document transport path 240, and the transport roller pairs 241, 242, 243, 244, and 245 assist the transport of the document 201. The discharge roller pair 251 assists the discharge of the document 201. The paper discharge tray 261 stores the discharged original 201. In the document reading unit 271, an image reading sensor light source 303 and an image reading sensor 304 are integrated.

  FIG. 3 is a block diagram showing electrical connection of the image reading apparatus 200 according to the first embodiment of the present invention. Each part will be described. The main control unit 301 includes an image reading sensor light source light amount control unit 309, an image reading sensor control unit 310, an AFE control unit 311, a transmittance detection sensor light source light amount control unit 312, an A / D conversion unit 315, an external IF control unit 308, A timer 341 is provided. Each part plays the following roles. The image reading sensor light source light quantity control unit 309 adjusts the light quantity of the image reading sensor light source 303. The image reading sensor control unit 310 drives the image reading sensor 304. The AFE control unit 311 controls the AFE (analog front end) 305 and acquires image data output from the AFE 305. The transmittance detection sensor light source light amount control unit 312 adjusts the light amount of the transmittance detection sensor light source 313. The A / D conversion unit 315 converts an analog signal from the transmittance detection sensor into a digital signal. The external IF control unit 308 communicates image data and control commands to an external information terminal (not shown). The timer 341 measures the time for each process.

  The main control unit 301 also includes control units, background member drive motors 316, a background member color detection sensor 319, an image reading position detection sensor 320, and a document stacking detection sensor 321 based on inputs stored in the storage unit. The paper feed motor 317 and the transport motor 318 are controlled.

  The ROM 302 stores a program for the main control unit 301. The RAM 306 temporarily stores a part of the program of the main control unit 301 and the image data acquired by the main control unit 301 from the AFE 305. The image reading sensor light source 303 enters reflected light for image formation into the image reading sensor 304. The image reading sensor 304 converts reflected light for image formation into an analog image data signal. The AFE 305 adjusts the amplification factor and offset level of the analog image data signal sent from the image reading sensor 304 based on the control of the main control unit 301. The AFE 305 performs A / D conversion on the digital image data signal and sends the image data signal to the AFE control unit 311.

  The background member 307 has a white portion 307 a and a black portion 307 b and is disposed to face the image reading sensor 304. The transmittance detection sensor light source 313 enters the transmitted light to the transmittance detection sensor 314. The transmittance detection sensor 314 is a photoelectric conversion element that converts the amount of light transmitted through the document 201 from the transmittance detection sensor light source 313 into an analog detection data signal, and detects the transmittance. Here, the background member 307 is disposed at a position facing the background member color detection sensor 319 and the document reading unit 271. The background member color detection sensor 319 and the document reading unit 271 are arranged so as to face each other differently between the white portion 307a and the black portion 307b of the background member 307. That is, in the state where the background member color detection sensor 319 faces the white portion 307a, the document reading unit 271 faces the black portion 307b. In addition, when the background member color detection sensor 319 is opposed to the black portion 307b, the document reading unit 271 is opposed to the white portion 307a.

  The background member drive motor 316 switches between the white portion 307a and the black portion 307b of the background member 307. In the present embodiment, the part facing the document reading unit 271 is switched by rotating the background member 307 by the background member drive motor 316. A paper feed motor 317 feeds the original 201. A conveyance motor 318 conveys the document 201. The background member color detection sensor 319 reflects the light of the original 201 and detects the color position of the background member. The image reading position detection sensor 320 takes the timing of image reading by reflecting the light of the original 201. The image reading position detection sensor 320 can measure the timing at which the document is conveyed and passed. The document stacking detection sensor 321 detects that the document 201 is stacked by reflecting light on the document 201.

[Processing flow]
Hereinafter, the image reading operation in the present embodiment will be described with reference to the flowchart of FIG. When the user turns on the image reading apparatus 200 and an external information terminal (not shown) transmits a reading start signal to the main control unit 301, the image reading apparatus 200 starts image reading.

  When image reading is started, first, in step S <b> 101, the main control unit 301 determines whether or not the document 201 is stacked on the document table 202 using the document stack detection sensor 321 arranged on the document table 202. When the document 201 is not stacked on the document table 202 (NO in S101), the main control unit 301 transmits an unload notification signal to an external information terminal (not shown), and the feed motor 317 and the transport motor 318 The driving is stopped and the image reading is finished.

  When document 201 is stacked on document table 202 (YES in S101), main control unit 301 starts driving paper feed motor 317 and transport motor 318 in S102, thereby pick-up roller 204 and feed roller. 206 begins to rotate. Here, the document 201 is fed into the image reading apparatus by the pickup roller 204 that has started rotating. The document 201 fed by the pickup roller 204 is transported to the document transport path 240 in the apparatus by the feed roller 206 that has started rotating. At this time, if there are a plurality of documents 201 fed by the pickup roller 204, only one document 201 is separated and conveyed by a separation roller 211 disposed facing the feed roller 206.

  In step S <b> 102, the conveyance of the document 201 is started, and the document 201 is conveyed to the transmittance detection sensor light source 313 disposed opposite to the transmittance detection sensor 314 and the transmittance detection sensor 314. Then, when the transmittance detection sensor 314 and the transmittance detection sensor light source 313 are blocked by the original 201, the amount of light reaching the transmittance detection sensor 314 from the transmittance detection sensor light source 313 is reduced, and the output of the transmittance detection sensor 314 is output. The value changes.

  Further, the amount of change in the output value of the transmittance detection sensor 314 is such that the amount of light that blocks the transmittance detection sensor 314 is small if the document 201 is a transparent document having a high transmittance. Therefore, when the transmittance with respect to the transparent document is detected, the amount of change in the output value of the transmittance detection sensor 314 becomes a predetermined value or less as a result. Therefore, in step S103, the main control unit 301 determines whether the change amount of the output value of the transmittance detection sensor 314 is equal to or less than a predetermined value, and determines whether the document is a transparent document based on the result.

  Further, the determination of whether or not the amount of change in the output value of the transmittance detection sensor 314 is equal to or less than a predetermined value is made by determining the determination location at one location on the sub-scanning line because the document 201 is moving in the sub-scanning direction. Alternatively, the determination may be made at a predetermined plurality of locations. Note that the predetermined value used in this determination is set based on a value obtained by detecting in advance a paper type handled by the image forming apparatus using a sensor. The predetermined value is stored in the ROM 302 or the like that is a storage unit.

  When the amount of change in the output value of transmittance detection sensor 314 is equal to or less than the predetermined value (YES in S103), main control unit 301 determines that document 201 is a transparent document. Therefore, in order to prevent ground fogging, in step S104, the main control unit 301 determines whether the background member 307 arranged to face the document reading unit 271 is the white portion 307a by using the background member color detection sensor 319. Use to determine. In this determination, the main control unit 301 determines based on whether the output of the background member color detection sensor 319 is a predetermined value or less. If the output of the background member color detection sensor 319 is equal to or less than a predetermined value, the background member 307 facing the background member color detection sensor 319 becomes a black portion 307b. Therefore, the background member 307 disposed opposite to the document reading unit 271 located on the opposite side becomes the white portion 307a.

  Conversely, if the output of the background member color detection sensor 319 is greater than a predetermined value, the background member 307 facing the background member color detection sensor 319 becomes a white portion 307a. Therefore, the background member 307 arranged to face the document reading unit 271 located on the opposite side is a black portion 307b. The predetermined value used here is set based on information obtained by causing the background member color detection sensor 319 to detect each of the white portion 307a and the black portion 307b of the background member 307 in advance. This predetermined value is held in the ROM 302 or the like that is a storage unit.

  When the output of background member color detection sensor 319 is equal to or less than a predetermined value (YES in S104), in S105, main control unit 301 causes image reading position detection sensor 320, image reading sensor light source light quantity control unit 309, and image reading sensor. Control of the control unit 310 and the AFE control unit 311 is performed. As a result, the main control unit 301 reads the image of the original 201 conveyed to the original reading unit 271 in the image reading apparatus 200. Then, the main control unit 301 transmits the read image data to an external information terminal (not shown). Further, the original 201 conveyed to the original conveying path 240 is discharged to the paper discharge tray 261 via the discharge roller pair 251. After completion of image reading and document discharge, the main control unit 301 determines again whether the document 201 is loaded on the document table 202 by the document stack detection sensor 321 arranged on the document table 202 in S101.

  If the output of background member color detection sensor 319 is greater than the predetermined value (NO in S104), main controller 301 starts driving background member drive motor 316 in S107, thereby rotating background member 307. After that, when the output of the background member color detection sensor 319 is equal to or less than a predetermined value, the main control unit 301 changes the background member 307 disposed to face the document reading unit 271 to the white portion 307a. The driving of 316 is stopped. As a result, the background color of the background member 307 facing the document reading unit 271 is switched to white.

  Note that the document 201 is also conveyed during the process of determining whether the amount of change in the output value of the transmittance detection sensor 314 is equal to or less than a predetermined value and switching the background color. Therefore, before the document 201 reaches the document reading unit 271, it is necessary to determine whether the amount of change in the output value of the transmittance detection sensor 314 is equal to or less than a predetermined value and to switch the background color.

  After the background member 307 disposed facing the document reading unit 271 is switched to the white portion 307a in S107, the main control unit 301 performs image reading of the document 201 and document discharge in S105. If the amount of change in the output value of transmittance detection sensor 314 is greater than the predetermined value (NO in S103), main controller 301 determines that document 201 is a document with low transmittance. Therefore, in order to prevent show-through, the main control unit 301 determines whether or not the background member 307 arranged to face the document reading unit 271 is the black portion 307b in step S109. Use to determine.

  When the background member 307 arranged to face the document reading unit 271 is the black portion 307b (YES in S109), the main control unit 301 performs image reading of the document 201 and document discharge in S105. After completion of image reading and document discharge, in step S101, the main control unit 301 determines again whether the document 201 is stacked on the document table 202 by the document stack detection sensor 321 arranged on the document table 202.

  When the background member 307 arranged to face the document reading unit 271 is the white portion 307a (NO in S109), in S111, the main control unit 301 starts driving the background member drive motor 316, and the background The member 307 is rotated. After that, when the output of the background member color detection sensor 319 exceeds a predetermined value, the main control unit 301 changes the background member 307 arranged to face the document reading unit 271 to the black portion 307b, and the background member drive motor 316 Stop driving. As a result, the background color of the background member 307 is switched to black.

  Similarly to S107, the document 201 is also conveyed during the period from the determination of whether the change amount of the output value of the transmittance detection sensor 314 is equal to or less than the predetermined value to the switching of the background color. Therefore, before the document 201 reaches the document reading unit 271, it is necessary to determine whether the amount of change in the output value of the transmittance detection sensor 314 is equal to or less than a predetermined value and to switch the background color.

  After the background member 307 arranged facing the document reading unit 271 is switched to the black portion 307b in S111, the main control unit 301 performs image reading of the document 201 and document discharge in S105.

  In this embodiment, the light quantity is used for detecting the transmittance, but an ultrasonic sensor may be used for detecting the transmittance. Moreover, the background member 307 showed the structure divided into two area | regions of the white part 307a and the black part 307b in FIG. However, the present invention is not limited to this. For example, the area of the background member 307 may be further divided and the white portions 307a and the black portions 307b may be alternately arranged. As a result, when the color of the background member 307 is switched, for example, if it is arranged in two regions, a rotation of 180 degrees is necessary, but a smaller rotation angle can be used, thereby enabling a high speed switching control. Can be realized. In the present embodiment, white and black are used as the plurality of background colors constituting the background member. However, the present invention is not limited to this, and other colors may be included according to the type of document. In the present embodiment, as shown in FIG. 2, the background member 307 has a drum shape, and the background color is switched by rotating it. However, the present invention is not limited to this shape.

  As described above, in the present embodiment, the background member suitable for the document is switched based on the light transmittance of the document without any user operation. Therefore, it is possible to acquire a high-quality image with high efficiency of the image reading operation and preventing the show-through or contrast reduction of the read image.

  Further, since the document determination unit is a transmittance acquisition unit that acquires the transmittance of the document, it is possible to determine a document having a high light transmittance such as a second original drawing sheet. Therefore, it is possible to acquire a high-quality image with high efficiency of the image reading operation and preventing the show-through or contrast reduction of the read image.

<Second embodiment>
In the second embodiment, in addition to the first embodiment, the main control unit 301 moves the document to a position where the document can be read when the background member 307 is switched. This is a configuration corresponding to the document passing through the reading position within the time required for performing the switching control. Hereinafter, an image reading operation in the present embodiment will be described with reference to the flowchart of FIG.

  When the user turns on the image reading apparatus 200 and an external information terminal (not shown) transmits a reading start signal to the main control unit 301, the image reading apparatus 200 starts image reading. When image reading is started, first in step S <b> 101, the main control unit 301 determines whether or not the document 201 is stacked on the document table 202 by the document stack detection sensor 321. When the document 201 is not stacked (NO in S101), the main control unit 301 transmits an unloading notification signal to an external information terminal (not shown), and stops driving the paper feed motor 317 and the conveyance motor 318. Then, the image reading is finished.

  When documents 201 are stacked (YES in S101), main control unit 301 starts driving of paper feed motor 317 and transport motor 318 in S102. As a result, the document 201 is fed into the image reading apparatus and conveyed to the document conveyance path 240 in the apparatus. At this time, when there are a plurality of documents 201, only one document 201 is separated and conveyed.

  In step S <b> 102, the conveyance of the document 201 is started, and the document 201 is conveyed to the transmittance detection sensor light source 313 disposed opposite to the transmittance detection sensor 314 and the transmittance detection sensor 314. The transmittance detection sensor 314 and the transmittance detection sensor light source 313 are blocked by the document 201. As a result, the amount of light reaching the transmittance detection sensor 314 from the transmittance detection sensor light source 313 decreases, and the output value of the transmittance detection sensor 314 changes.

  Further, the amount of change in the output value of the transmittance detection sensor 314 is less than a predetermined value because the amount of light that blocks the transmittance detection sensor 314 is small if the document 201 is a transparent document with high transmittance. . Therefore, in step S103, the main control unit 301 determines whether the amount of change in the output value of the transmittance detection sensor 314 is equal to or less than a predetermined value, and as a result, determines whether the conveyed document 201 is a transparent document. To do.

  Note that whether or not the change amount of the output value of the transmittance detection sensor 314 is equal to or less than a predetermined value is determined at one place on the sub-scanning line because the document 201 is moving in the sub-scanning direction. Alternatively, the determination may be made at a predetermined plurality of locations.

  If the amount of change in the output value of transmittance detection sensor 314 is equal to or smaller than the predetermined value (YES in S103), in S104, main controller 301 causes background member 307 facing document reading unit 271 to white portion 307a. It is determined using the background member color detection sensor 319. This determination is made based on whether or not the output of the background member color detection sensor 319 is a predetermined value or less. In addition, about the predetermined value used here, it is the same as that of 1st embodiment.

  When the output of background member color detection sensor 319 is equal to or less than a predetermined value (YES in S104), in S105, main control unit 301 causes image reading position detection sensor 320, image reading sensor light source light quantity control unit 309, and image reading sensor. Control of the control unit 310 and the AFE control unit 311 is performed. Thus, the image of the original 201 conveyed to the original reading unit 271 in the image reading apparatus is read, and the read image data is transmitted to an external information terminal (not shown). Further, the original 201 conveyed to the original conveying path 240 is discharged to the paper discharge tray 261 via the discharge roller pair 251. After completion of image reading and document discharge, in step S101, the main control unit 301 determines again whether the document 201 is stacked on the document table 202 by the document stack detection sensor 321 arranged on the document table 202.

  When the background member 307 arranged to face the document reading unit 271 is the black portion 307b (NO in S104), in S106, the main control unit 301 causes the paper feed motor 317 and the conveyance motor 318 to move to the document 201. Is rotated in the direction opposite to the direction of rotation when transporting. As a result, the main control unit 301 returns the document 201 to a predetermined position and then stops the rotation.

  After stopping the paper feed motor 317 and the conveyance motor 318 in S106, the main control unit 301 starts driving the background member drive motor 316 and rotates the background member 307 in S107. At this time, when the sensor output of the background member color detection sensor 319 is equal to or less than a predetermined value, the background member 307 disposed facing the document reading unit 271 becomes the white portion 307a. Accordingly, the main control unit 301 stops the driving of the background member drive motor 316. As a result, the background color of the background member 307 facing the document reading unit 271 is switched to white.

  After the background member 307 facing the document reading unit 271 is switched to the white portion 307a in S107, the main control unit 301 starts driving the paper feed motor 317 and the conveyance motor 318 in S108, similarly to S102. Accordingly, the main control unit 301 conveys the document 201 to the document conveyance path 240 in the apparatus. In step S <b> 105, the main control unit 301 performs image reading and document discharge of the document 201.

  When the change amount of the output value of transmittance detection sensor 314 is larger than the predetermined value (NO in S103), document 201 is a document with low transmittance. Therefore, in order to prevent the show-through, in S109, the main control unit 301 uses the background member color detection sensor 319 to check whether the background member 307 facing the document reading unit 271 is a black portion 307b. judge. In addition, regarding the predetermined value used here, it is the same as that of 1st embodiment.

  If the output of background member color detection sensor 319 is greater than the predetermined value (YES in S109), main controller 301 performs image reading and document discharge of document 201 in S105. After completion of image reading and document discharge, the main control unit 301 determines again whether or not the document 201 is stacked on the document table 202 using the document stack detection sensor 321 disposed on the document table 202 in S101.

  When the sensor output of background member color detection sensor 319 is equal to or smaller than a predetermined value (NO in S109), main controller 301 normally feeds document 201 by feeding motor 317 and transport motor 318 in S110. Rotate in the direction opposite to the direction of rotation. As a result, the main control unit 301 returns the document 201 to a predetermined position and then stops the rotation.

  After stopping the paper feed motor 317 and the conveyance motor 318 in S110, the main control unit 301 starts driving the background member drive motor 316 and rotates the background member 307 in S111. At this time, when the output of the background member color detection sensor 319 becomes larger than a predetermined value, the background member 307 arranged to face the document reading unit 271 becomes the black portion 307b. Accordingly, the main control unit 301 stops the driving of the background member drive motor 316. As a result, the background color of the background member 307 facing the document reading unit 271 is switched to black.

  After the background member 307 facing the document reading unit 271 is switched to the black portion 307b in S111, the main control unit 301 starts driving the paper feed motor 317 and the conveyance motor 318 in S112 similarly to S102. Accordingly, the main control unit 301 conveys the document 201 to the document conveyance path 240 in the apparatus. In step S <b> 105, the main control unit 301 performs image reading and document discharge of the document 201.

  In the present embodiment, when the background member 307 is switched, the paper feed motor 317 and the transport motor 318 are stopped and rotated in the reverse direction to move the document 201 to a predetermined position. However, there are few determination points for the amount of change in the output value of the transmittance detection sensor 314, and the amount of change in the output value of the transmittance detection sensor 314 is determined and the background color is switched before the document 201 reaches the document reading unit 271. It can be done. In such a case, the document 201 may be transported as it is without stopping the paper feed motor 317 and the transport motor 318.

  Further, the determination of the change amount of the output value of the transmittance detection sensor 314 is performed in time for the determination of the change amount of the output value of the transmittance detection sensor 314 and the switching of the background color before the document 201 reaches the document reading unit 271. It is provided for each case and when it is not in time. Then, when the determination is different from the case where the background color is switched in time and the case where the background color is not switched, the document 201 is returned to a predetermined position by reversing the paper feed motor 317 and the conveyance motor 318 so that the background is switched. May be.

  As described above, in this embodiment, in addition to the configuration of the first embodiment, a configuration is provided in which the conveying unit moves to a position where the document can be read when the background member is switched. Thereby, even if there is a document that has passed the reading position within the time required for the switching process, it can be returned to a predetermined position. Further, according to the configuration of the present embodiment, the distance between the transmittance acquisition means and the background member can be shortened, and the document transport speed can be increased. Therefore, in addition to the effects of the first embodiment, the efficiency of the image reading operation is high, and the image reading apparatus can be made compact and fast.

<Third embodiment>
In the third embodiment, in addition to the configuration of the second embodiment, the main controller 301 measures the time for the original 201 to pass through the transmission means, and minimizes the amount of movement of the original. Hereinafter, an image reading operation in the present embodiment will be described with reference to the flowchart of FIG.

  FIG. 5 is a flowchart for explaining an image reading operation according to the present embodiment. The block diagram showing the electrical connection of the image reading apparatus in the present embodiment is the same as that in the first embodiment.

  When the user turns on the image reading apparatus 200 and an external information terminal (not shown) transmits a reading start signal to the main control unit 301, the image reading apparatus 200 starts image reading. When image reading is started, first, in step S101, the main control unit 301 determines whether the document 201 is stacked on the document table 202 by the document stack detection sensor 321.

  When the document 201 is not stacked (NO in S101), the main control unit 301 transmits an unloading notification signal to an external information terminal (not shown), and stops driving the paper feed motor 317 and the conveyance motor 318. Then, the image reading is finished.

  When the original 201 is stacked (YES in S101), the main control unit 301 starts driving the paper feed motor 317 and the conveyance motor 318 in S402, separates only one original 201, and reads the image. Paper is fed and conveyed to a document conveyance path 240 in the apparatus. Further, the main control unit 301 starts the timer 341 and starts measuring time. When the conveyance of the document 201 and the measurement of time are started and the document 201 is conveyed to the transmittance detection sensor light source 313 facing the transmittance detection sensor 314 and the transmittance detection sensor 314, the transmittance detection sensor 314 and the transmission are transmitted. The rate detection sensor light source 313 is blocked by the document 201. As a result, the amount of light reaching the transmittance detection sensor 314 from the transmittance detection sensor light source 313 decreases, and the output value of the transmittance detection sensor 314 changes.

  In step S103, the main control unit 301 determines whether the amount of change in the output value of the transmittance detection sensor 314 is equal to or less than a predetermined value. When the amount of change in the output value of transmittance detection sensor 314 is equal to or smaller than the predetermined value (YES in S103), main controller 301 has background member 307 arranged to face document reading unit 271 as white portion 307a. It is determined using the background member color detection sensor 319. The predetermined value used here is the same as in the first embodiment.

  If the output of background member color detection sensor 319 is less than or equal to the predetermined value (YES in S103), main controller 301 stops timer 341 and ends the time measurement in S411. After the timer 341 is stopped, the main control unit 301 controls the image reading position detection sensor 320, the image reading sensor light source light amount control unit 309, the image reading sensor control unit 310, and the AFE control unit 311 in S105. As a result, the main control unit 301 reads the image of the original 201 conveyed to the original reading unit 271 in the image reading apparatus 200. The main control unit 301 transmits the read image data to an external device (not shown). Further, the original 201 conveyed to the original conveying path 240 is discharged to the paper discharge tray 261 via the discharge roller pair 251. Further, the main control unit 301 clears the counter of the timer 341 and returns the time measurement time to the initial value.

  After the completion of the image reading, document discharge, and timer 341 counter clear processes, the main control unit 301 determines whether the document 201 is stacked on the document table 202 by the document stack detection sensor 321 disposed on the document table 202 in S101. Determine again.

  If the output of background member color detection sensor 319 is greater than the predetermined value (NO in S104), main controller 301 stops timer 341 and ends the time measurement in S412. After completing the time measurement, in S106, the main control unit 301 reversely rotates the paper feed motor 317 and the conveyance motor 318, and the distance that the document 201 is conveyed by the time measured by the timer 341. After returning to, stop. The distance transported at a certain time can be defined in advance, and the document 201 may be returned using the transport distance in time units and the time measured by the timer 341.

  After stopping the paper feed motor 317 and the transport motor 318, the main control unit 301 starts driving the background member drive motor 316 and rotates the background member 307 in S107. Thereby, the main control unit 301 switches the background color of the background member 307 to white. After switching the background member 307 facing the document reading unit 271 to the white portion 307a, in S108, the main control unit 301 starts driving the paper feed motor 317 and the conveyance motor 318 in the same manner as S102, and the document 201 is moved to the apparatus. It is conveyed to the original document conveyance path 240. In step S <b> 405, the main control unit 301 performs image reading and document discharge of the document 201, and clears the counter of the timer 341 to return the time measurement time to the initial value.

  If the amount of change in the output value of transmittance detection sensor 314 is greater than the predetermined value (NO in S103), in S109, main controller 301 causes background member 307 facing document reading unit 271 to become black portion 307b. It is determined using the background member color detection sensor 319. The predetermined value used here is the same as in the first embodiment.

  If the output of background member color detection sensor 319 is greater than the predetermined value (YES in S109), main controller 301 stops timer 341 and ends the time measurement in S413. After completing the time measurement, in step S405, the main control unit 301 performs a process of reading the document 201, discharging the document, and clearing the counter of the timer 341 to return the time measurement time to the initial value. After the image reading, document discharge, and timer 341 counters are cleared, the main control unit 301 loads the document 201 on the document table 202 by the document stacking detection sensor 321 disposed on the document table 202 in S101. It is determined again.

  If the output of background member color detection sensor 319 is equal to or smaller than the predetermined value (NO in S109), main controller 301 stops timer 341 and ends the time measurement in S414. After the timer 341 is stopped and the time measurement is completed, in S110, the main control unit 301 rotates the paper feed motor 317 and the conveyance motor 318 in the reverse direction so that the document 201 is a document corresponding to the time measured by the timer 341. After returning to the distance that 201 is conveyed, it stops.

  After stopping the paper feed motor 317 and the transport motor 318, the main control unit 301 starts driving the background member drive motor 316 and rotates the background member 307 in S111. As a result, the main control unit 301 switches the background color of the background member 307 to black. After the background member 307 arranged facing the document reading unit 271 is switched to the black portion 307b, the main control unit 301 starts driving the paper feed motor 317 and the conveyance motor 318 in S112 in the same manner as S102. The document 201 is transported to a document transport path 240 in the apparatus. In step S <b> 405, the main control unit 301 performs image reading and document discharge of the document 201, and clears the counter of the timer 341 to return the time measurement time to the initial value.

  After completing the image reading, document discharge, and timer 341 counter clear processes, the main control unit 301 loads the document 201 on the document table 202 by the document stacking detection sensor 321 disposed on the document table 202 in S101. It is determined again.

  In the present embodiment, when the background member 307 is switched, the paper feed motor 317 and the transport motor 318 are stopped and rotated in the reverse direction to move the document 201 to a predetermined position. However, there are few determination points for the amount of change in the output value of the transmittance detection sensor 314, and whether the amount of change in the output value of the transmittance detection sensor 314 is equal to or less than a predetermined value before the document 201 reaches the document reading unit 271. Judgment and background color switching may be possible. In such a case, the document 201 may be transported as it is without stopping the paper feed motor 317 and the transport motor 318.

  Further, the determination of the change amount of the output value of the transmittance detection sensor 314 is performed in time for the determination of the change amount of the output value of the transmittance detection sensor 314 and the switching of the background color before the document 201 reaches the document reading unit 271. It is provided for each case and when it is not in time. Then, when the determination is different from the case where the background color is switched in time and the case where the background color is not switched, the document 201 is returned to a predetermined position by reversing the paper feed motor 317 and the conveyance motor 318 so that the background is switched. May be.

  As described above, in this embodiment, means for controlling the position (distance) at which the document is moved based on the time that the document has passed through the transmission means is added to the second embodiment. As a result, the amount of movement of the document can be minimized and the accuracy can be further increased. Therefore, in addition to the effects of the first and second embodiments, the efficiency of the image reading operation can be improved.

<Fourth embodiment>
In the fourth embodiment, in addition to the second embodiment, the main control unit 301 moves the document to the detection position of the image reading position detection sensor 320 for taking the image reading timing, and thereby the amount of movement of the document is set. Minimize. Here, as shown in FIG. 2, the image reading position detection sensor 320 is positioned before the reading position with respect to the transport direction of the document transport path 240.

  As described above, in this embodiment, the amount of movement of the document can be minimized by moving the position where the document is moved to the position of the image reading position detecting means for taking the timing of image reading. Thereby, in addition to the effect of the second embodiment, the efficiency of the image reading operation is further increased.

<Fifth embodiment>
In the fifth embodiment, the transmittance acquisition means for acquiring the transmittance of the first to fourth embodiments is arranged on a line in the main scanning direction of the document, and the frame (outer shape) of the document is detected from the transmission amount. Thus, the size and inclination of the document are detected.

  FIG. 7 is a block diagram showing an electrical connection of the image reading apparatus in the present embodiment. Hereinafter, a different part from the image reading apparatus in 1st thru | or 4th embodiment already demonstrated is demonstrated.

  The main control unit 701 includes a frame detection sensor control unit 702, an image reading sensor light source light quantity control unit 309, an image reading sensor control unit 310, an AFE control unit 311, an external IF control unit 308, and a timer 341. The frame detection sensor control unit 702 adjusts the light amount of the frame detection sensor light source 711, drives the frame detection sensor 712, and controls the frame detection AFE 713. The frame detection sensor control unit 702 acquires the image data output from the frame detection AFE 713, rearranges the acquired image data, and performs binarization processing and frame cutting processing. The image reading sensor light source light quantity control unit 309 adjusts the light quantity of the image reading sensor light source 303. The image reading sensor control unit 310 drives the image reading sensor 304. The AFE control unit 311 acquires control of the AFE 305 and image data output from the AFE 305. The external IF control unit 308 communicates image data and control commands to an external information terminal (not shown). The timer 341 measures time.

  Further, the main control unit 701 is based on the programs stored in the storage unit, the background member color detection sensor 319, the image reading position detection sensor 320, and the document stacking detection sensor 321, and the respective control units, the background member drive motor 316, The paper feed motor 317 and the transport motor 318 are controlled.

  The frame detection sensor light source 711 emits transmitted light to the frame detection sensor 712. In this embodiment, the frame detection sensor light source 711 is disposed at the same position as the transmittance detection sensor light source 313 shown in FIG. The frame detection sensor 712 includes a photoelectric conversion element that converts light transmitted through the document 201 from the frame detection sensor light source 711 into an analog detection data signal, and detects the frame and transmittance of the document 201. Similarly to the image reading sensor 304, the frame detection sensor 712 is arranged on the line in the main scanning direction of the document 201, and the length of the frame detection sensor 712 is wider than the width of the document 201. In the present embodiment, the frame detection sensor 712 is disposed at the same position as the transmittance detection sensor 314 shown in FIG.

  The frame detection AFE 713 adjusts the amplification factor and offset level of the analog image data signal transmitted from the frame detection sensor 712 based on the control of the main control unit 701, and performs A / D conversion to a digital image data signal. An image data signal is sent to the frame detection sensor control unit 702.

[Processing flow]
Hereinafter, the image reading operation in the present embodiment will be described with reference to the flowchart of FIG. When the user turns on the image reading apparatus 200 and an external information terminal (not shown) transmits a reading start signal to the main control unit 701, the image reading apparatus 200 starts image reading.

  When image reading is started, first in step S <b> 601, the main control unit 701 uses the document stacking detection sensor 321 to determine whether the document 201 is stacked on the document table 202. When the document 201 is not stacked (NO in S601), the main control unit 701 transmits a non-load notification signal to an external information terminal (not shown), and stops driving the paper feed motor 317 and the conveyance motor 318. Then, the image reading is finished.

  When the originals 201 are stacked (YES in S601), the main control unit 701 starts driving the paper feed motor 317 and the conveyance motor 318 in S602. As a result, only one original 201 is separated and fed and transported to a document transport path 240 in the image reading apparatus. Further, the main control unit 701 starts the timer 341 and starts measuring time.

  When the conveyance of the document 201 and the measurement of the time are started and the document 201 is conveyed to the frame detection sensor light source 711 disposed opposite to the frame detection sensor 712 and the frame detection sensor 712, the frame detection sensor 712 and the frame detection sensor are detected. The light source 711 is blocked by the document 201. As a result, the amount of light reaching the frame detection sensor light source 711 from the frame detection sensor 712 decreases, and the output value of the frame detection sensor 712 changes.

  In step S603, the main control unit 701 determines whether the amount of change in the output value of the frame detection sensor 712 is equal to or less than a predetermined value. Since the frame detection sensor 712 is arranged on the line in the main scanning direction of the document, the determination point of the change amount of the output value may be determined at one place on the line, or determined by a predetermined plurality of pixels. You may do it. Further, the determination of whether or not the change amount of the output value of the frame detection sensor 712 is equal to or less than the predetermined value is made by determining the determination location at one location on the sub-scanning line because the document 201 is moving in the sub-scanning direction. Alternatively, the determination may be made at predetermined plural positions on the sub-scanning line. The predetermined value used here is the same as in the first embodiment.

  When the amount of change in the output value of transmittance detection sensor 314 is equal to or smaller than a predetermined value (YES in S603), main controller 701 has background member 307 arranged to face document reading unit 271 as white portion 307a. Is determined using the background member color detection sensor 319.

  If the output of background member color detection sensor 319 is equal to or less than the predetermined value (YES in S604), main control unit 701 stops timer 341 in S611 and ends the time measurement. After the timer 341 is stopped, the main control unit 701 controls the image reading position detection sensor 320, the image reading sensor light source light quantity control unit 309, the image reading sensor control unit 310, and the AFE control unit 311 in S605. As a result, the main control unit 701 reads the image of the document 201 conveyed to the document reading unit 271 in the image reading device, and transmits the read image data to an external device (not shown). Further, the original 201 conveyed to the original conveying path 240 is discharged to the paper discharge tray 261 via the discharge roller pair 251. Further, the main control unit 701 clears the counter of the timer 341 and returns the time measurement time to the initial value.

  After completion of the image reading, document discharge, and timer 341 counter clear processing in S605, the main control unit 701 uses the frame detection image data 801 sent to the frame detection sensor control unit 702 in S615. Detect size and tilt.

[Frame detection (main scanning direction)]
Here, a method for detecting the document size in the main scanning (width) direction will be described with reference to FIG. In FIG. 8, frame detection image data 801 is digital data obtained by A / D converting the output signal of the frame detection sensor 712. The frame detection image data 801 is sequentially input to the frame detection sensor control unit 702 with the pixel data corresponding to the light receiving element at the end as the head.

  The frame detection sensor control unit 702 performs binarization processing using the threshold value 802 on the frame detection image data 801 based on the output signal of the frame detection sensor 712. The document edge image data 803 and 804 are obtained by binarizing the frame detection image data 801 by the frame detection sensor control unit 702. White represents a pixel having a pixel value of 1, and black represents a pixel having a pixel value of 0. . The frame detection sensor control unit 702 performs binarization using an appropriate threshold defined in advance. As a result, in the frame detection image data 801, a portion where the document 201 does not overlap the frame detection sensor 712 becomes a white pixel, and a portion where the document 201 overlaps becomes a black pixel.

  Further, since it is necessary to detect all originals, the change amount (threshold value) for frame detection is lower than the change amount (transmission rate determination) of the output value of the frame detection sensor 712 performed in S603.

  When detecting the left end of the document 201 in the width direction, if the frame detection sensor 712 performs line scanning from the left, the frame is detected from the left end (front end) of the frame detection sensor 712 in the direction of arrow C, and is received by the light receiving element at the left end. The binarized data of the corresponding pixel is input to the frame detection sensor control unit 702 with the head.

  The frame detection sensor control unit 702 monitors the binarized frame detection image data 801 in the order of input from the leftmost pixel as the head, and detects what pixel the color has changed from white to black first. In FIG. 8, the binarized document edge image data 803 changes from white to black at the m-th pixel counted from the left end of the frame detection sensor 712. When detecting the change point, the frame detection sensor control unit 702 ends the detection processing of the left end of the document 201 in the line. It should be noted that detection may be continued over several pixels after detection of the change point to prevent erroneous detection due to noise.

  Next, when detecting the right end of the document 201 in the width direction, if the frame detection sensor 712 performs line scanning from the right, the arrow D from the right end (rear end) of the frame detection sensor 712 is opposite to the case of detecting the left end. Scan in the direction of. Then, the binarized data of the pixel corresponding to the rightmost light receiving element is sequentially input to the frame detection sensor control unit 702 in the direction of the arrow D with the binarized data as the head.

  The frame detection sensor control unit 702 monitors the order in which the rightmost pixel is input as the head, and detects the pixel at which the pixel first changed from white to black. The binarized document edge image data 804 changes from white to black at the nth pixel counting from the right edge of the frame detection sensor 712. When this change point is detected, the process for detecting the right edge of the document in the line ends. It should be noted that detection may be continued over several pixels after detection of the change point to prevent erroneous detection due to noise.

[Frame detection (sub-scanning direction)]
Next, detection of the document size in the sub-scanning (length) direction will be described with reference to FIG. FIG. 9 is a diagram illustrating a position where the frame detection sensor 712 scans the conveyed document. A broken line 1002 indicates a position scanned by the frame detection sensor 712 at time t (0). Similarly, broken lines 1003 to 1008 indicate scanning positions at times t (1) to t (n), respectively.

  At time t (0), since the document 201 has not yet reached the frame detection sensor 712, all image signals output from the frame detection sensor 712 are white pixel signals. That is, since the right edge and the left edge of the document 201 cannot be detected, it can be determined that the document 201 has not reached the frame detection sensor 712. At time t (1), since the document 201 has reached the frame detection sensor 712, the right end and the left end of the document 201 can be detected. Therefore, it is considered that the leading edge of the document 201 in the conveyance direction has reached the frame detection sensor 712 while elapses from t (0) to t (1).

  Similarly, regarding the trailing edge in the document transport direction, the right and left edges of the document can be detected at time t (n−1), and the right and left edges of the document cannot be detected at time t (n). Therefore, it can be considered that the trailing edge of the document 201 has passed through the frame detection sensor 712 while elapses from t (n−1) to t (n).

  Here, since the frame detection sensor 712 is scanned at regular intervals, the length of the document can be detected from the number of scans and the conveyance speed from when the leading edge of the document is detected until the trailing edge passes. . Further, since the scanning time of the frame detection sensor 712 is very short with respect to the conveyance speed of the document 201, the distance traveled by the document 201 between t (0) and t (1), and t (n-1). The distance traveled by the document 201 between t and n (n) is a value that can be almost ignored.

[Tilt detection]
Next, detection of the tilt of the conveyed document 201 will be described with reference to FIG. Since the frame detection sensor 712 scans the document 201 at regular time intervals, the pixel position of the document edge pixel, which is a change point from the white pixel to the black pixel, can be detected every time one line is scanned. The detected pixel position of the document edge pixel is stored in the RAM 306 for each line.

  In FIG. 10, the pixel positions of the stored document edge pixels are simplified and arranged on the XY coordinates for each distance the document travels at regular intervals. The coordinates (x11, y1), (x13, y3), (x15, y5), (x17, y7), (x19, y9) are the coordinates of the leftmost pixel of the document. Similarly, coordinates (x22, y2), (x24, y4), (x26, y6), and (x28, y8) are the coordinates of the right edge pixel of the document.

  As shown in FIG. 10, the coordinates of the leftmost pixel and the coordinates of the rightmost pixel are detected every two lines. The coordinates of the document edge pixels that are not detected for each line can be obtained by interpolation or the like. Note that the detection interval is not limited to the above, and may be performed every three lines or more in consideration of, for example, the load on the processing unit and the required accuracy.

  The distance that the document 201 is transported in the predetermined time can be determined from the transport speed of the document 201. The frame detection sensor control unit 702 can detect the inclination of the document from the distance that the document 201 is conveyed in the predetermined time and the average deviation amount per line of the document edge pixel position. Further, the four corners of the document 201 can be calculated from the detected tilt of the document, and the size of the document 201 can be detected even when the document 201 is stacked in a tilted state.

  Returning to the description of the processing shown in FIG. After the main control unit 701 detects the size and inclination of the document in S615, the main control unit 701 again checks whether the document 201 is stacked on the document table 202 by the document stack detection sensor 321 arranged on the document table 202. judge.

  If the output of background member color detection sensor 319 is greater than the predetermined value (NO in S604), main controller 701 stops timer 341 and ends the time measurement in S612. After completing the time measurement, in step S606, the main control unit 701 reversely rotates the paper feed motor 317 and the transport motor 318, and the distance that the document 201 is transported by the time measured by the timer 341. After returning to, stop. After stopping the paper feed motor 317 and the transport motor 318, the main control unit 701 starts driving the background member drive motor 316 and rotates the background member 307 in S607. Thereby, the main control unit 701 switches the background color of the background member 307 to white.

  After switching the background member 307 facing the document reading unit 271 to the white portion 307a, in S608, the main control unit 701 starts driving the paper feed motor 317 and the conveyance motor 318 in the same manner as S602, and the document 201 is moved to the apparatus. It is conveyed to the original document conveyance path 240. In step S <b> 605, the main control unit 701 performs processing for reading the document 201 and discharging the document and clearing the counter of the timer 341 to return the time measurement time to the initial value.

  If the amount of change in the output value of frame detection sensor 712 is greater than the predetermined value (NO in S603), in S609, main controller 701 causes background member 307 facing document reading unit 271 to become black portion 307b. It is determined by the background member color detection sensor 319. The predetermined value used here is the same as in the first embodiment. If the output of the background member color detection sensor 319 is greater than the predetermined value (YES in S609), the main control unit 701 clears the image reading and document discharge of the document 201 and the counter of the timer 341 in S605 and measures the time. To return to the initial value.

  After the image reading, document discharge, and timer 341 counters have been cleared in S605, the main control unit 701 uses the frame detection image data 801 sent to the frame detection sensor control unit 702 in S615 to determine the size of the document. And tilt detection. After detecting the size and inclination of the document 201, the main control unit 701 determines again whether or not the document 201 is stacked on the document table 202 by the document stacking detection sensor 321 disposed on the document table 202 in S 601.

  If the output of background member color detection sensor 319 is less than or equal to the predetermined value (NO in S609), main controller 701 stops timer 341 and ends the time measurement in S614. After completing the time measurement, the main control unit 701 rotates the paper feed motor 317 and the transport motor 318 in reverse in S610, and the distance that the document 201 is transported by the time measured by the timer 341. After returning to, stop. About the distance conveyed per fixed time, it is the same as that of 1st embodiment.

  After stopping the paper feed motor 317 and the carry motor 318, the main control unit 701 starts driving the background member drive motor 316 and rotates the background member 307 in S611. As a result, the main control unit 701 switches the background color of the background member 307 to black. After switching the background member 307 facing the document reading unit 271 to the black portion 307b, the main control unit 701 starts driving the paper feed motor 317 and the conveyance motor 318 in S612 similarly to S602, and the document 201 is moved to the apparatus. It is conveyed to the original document conveyance path 240. In step S <b> 605, the main control unit 701 performs image reading and document discharge of the document 201 and the counter of the timer 341 to perform processing for returning the time measurement time to the initial value. After the completion of the image reading, document discharge, and timer 341 counter clear processes, the main control unit 701 uses the frame detection image data 801 sent to the frame detection sensor control unit 702 in step S615 to determine the size of the document. Detect tilt.

  In the present embodiment, when the background member 307 is switched, the paper feed motor 317 and the transport motor 318 are stopped and rotated in the reverse direction to move the document 201 to a predetermined position. However, there are few determination points for the amount of change in the output value of the transmittance detection sensor 314, and whether the amount of change in the output value of the transmittance detection sensor 314 is equal to or less than a predetermined value before the document 201 reaches the document reading unit 271. Judgment and background color switching may be possible. In such a case, the document 201 may be transported as it is without stopping the paper feed motor 317 and the transport motor 318.

  Further, the determination of the change amount of the output value of the transmittance detection sensor 314 is performed in time for the determination of the change amount of the output value of the transmittance detection sensor 314 and the switching of the background color before the document 201 reaches the document reading unit 271. It is provided for each case and when it is not in time. Then, when the determination is different from the case where the background color is switched in time and the case where the background color is not switched, the document 201 is returned to a predetermined position by reversing the paper feed motor 317 and the conveyance motor 318 so that the background is switched. May be.

  As described above, in this embodiment, in addition to the first to fourth embodiments, the transmittance acquisition unit is arranged on the line in the main scanning direction of the document, and detects the frame of the document from the transmission amount. Thereby, in addition to the effects of the first embodiment, it is possible to acquire a high-quality image that can detect the size and inclination of the document.

<Sixth embodiment>
In the fifth embodiment, the frame detection sensor control unit 702 performs background member switching determination and document size and inclination detection. In contrast, in the sixth embodiment, frame detection data acquired from the frame detection AFE 713 is transmitted as image data to an external information terminal (not shown), and the background information switching determination and document size are performed at the external information terminal. And tilt detection.

  As described above, in this embodiment, in addition to the first to fourth embodiments, the transmittance acquisition unit is arranged on the line in the main scanning direction of the document, and detects the frame of the document from the transmission amount. Therefore, it is possible to acquire a high-quality image that can detect the size and inclination of the document.

<Seventh embodiment>
In the seventh embodiment, the part of the transmittance acquisition unit that acquires the transmittance of the first to sixth embodiments is changed to a document thickness acquisition unit that acquires the thickness of the document. The thickness of the document is detected using ultrasonic waves, radio waves, light intensity, the amount of pushing the document by a lever, and the like.

  As described above, in the present embodiment, the background member suitable for the document is switched based on the thickness of the document without any user operation. Therefore, it is possible to acquire a high-quality image with high efficiency of the image reading operation and preventing the show-through or contrast reduction of the read image.

<Eighth embodiment>
In the eighth embodiment, the portion of the transmittance acquisition unit that acquires the transmittance of the first to seventh embodiments is changed to a reflectance acquisition unit that acquires the reflectance of the document. The reflectance is detected using ultrasonic waves, radio waves, light quantity, and the like.

  As described above, in the present embodiment, the background member suitable for the document is switched based on the reflectance of the document without any user operation. Therefore, it is possible to acquire a high-quality image with high efficiency of the image reading operation and preventing the show-through or contrast reduction of the read image.

<Other embodiments>
The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, or the like) of the system or apparatus reads the program. It is a process to be executed.

Claims (12)

An image reading apparatus comprising a conveying means for conveying an original and a reading means for reading the original at a predetermined reading position,
A background member disposed opposite to the reading means and having a plurality of background colors as a background of the document;
Determining means for determining the type of the document;
An image reading apparatus comprising: a control unit that switches a background color of the background member when the reading unit reads the document based on the type of document determined by the determination unit. The determination unit includes a transmittance acquisition unit that acquires the transmittance of the document.
The image reading apparatus according to claim 1, wherein the type of the original is determined according to the transmittance acquired by the transmittance acquiring unit. The determination unit includes a thickness acquisition unit that acquires the thickness of the document.
The image reading apparatus according to claim 1, wherein the type of the original is determined according to the thickness acquired by the thickness acquisition unit. The determination unit includes a reflectance acquisition unit that acquires the reflectance of the document.
The image reading apparatus according to claim 1, wherein the type of the original is determined according to the reflectance acquired by the reflectance acquisition unit.   5. The determination unit according to claim 1, wherein the determination unit is arranged on a line in the main scanning direction of the document, and detects the size and inclination of the document by detecting the outer shape of the document. The image reading apparatus according to one item.   The image reading apparatus according to claim 5, wherein the determination unit detects the transmittance of the document and detects the outer shape of the document based on a change in the transmittance in the main scanning direction.   The control means returns the original conveyed from the conveying means to a position where the reading means can read the original using the switched background color when the background color of the background member is switched. An image reading apparatus according to any one of claims 1 to 6.   The image according to claim 7, wherein the distance to which the document conveyed by the conveyance unit is returned when the background color of the background member is switched is based on the time when the document is conveyed by the conveyance unit. Reader. An image reading position detecting means that is arranged before the reading position in the transport direction and detects an image reading timing by passing a document;
The position where the document conveyed by the conveying unit is returned when the control unit switches the background color of the background member is a detection position of the image reading position detecting unit. Image reading apparatus. The background member has a drum shape, and has a plurality of regions each composed of the plurality of background colors,
The image reading apparatus according to claim 1, wherein the control unit switches a background color by rotating the background member.   The image reading apparatus according to claim 1, wherein the plurality of background colors constituting the background member include white and black. A method for controlling an image reading apparatus, comprising: a conveying unit that conveys a document; and a reading unit that reads the document at a predetermined reading position,
The image reading apparatus further includes a background member disposed opposite to the reading unit and having a plurality of background colors as a background of the document,
A control method comprising: determining a type of the original; and switching a background color of the background member when the reading unit reads the original based on the determined original type.

Images