JP2016204107A - Medium transport device, image reading apparatus, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect a skew of a transport object medium during transporting.SOLUTION: A medium transport device includes: a transport means 20, 21, 22, and 23 for transporting a transport object medium F; first reading means 14 and second reading means 15 arranged separately from each other with respect to a transporting direction D1 of the transport object medium F; and detection means for detecting a skew mode of the transport object medium while transporting on the basis of information acquired by the first reading means 14 and the second reading means 15.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a medium conveying apparatus.

  In an image reading apparatus such as a document scanner, in order to reliably read a document (hereinafter also referred to as a medium or a transported medium), it is desirable that the document is transported without being inclined with respect to the transport direction. In some cases, it may be transported at an angle. In this case, the skew of the document being conveyed (inclined conveyance) appears as an inclination or distortion of the read image. Therefore, conventionally, the degree of inclination of the end of the document is examined from the read image, and skew is detected based on this (Patent Document 1).

Japanese Patent No. 5367241

  However, in the method described in Patent Document 1, when the image of the original is read, the conveyance of the original is completed, and skewing of the original is detected during the conveyance or occurs during the conveyance of the original. It was difficult to accurately detect the skew.

  The present invention provides a technique for accurately detecting skew during transport of a transported medium.

  According to one aspect of the present invention, for example, a transport unit that transports a transported medium, first and second reading units that are spaced apart from each other in the transport direction of the transported medium, And detecting means for detecting a skew mode of the transported medium being transported based on information acquired by the second reading means.

  Moreover, according to one aspect of the present invention, for example, the program is executed by a computer connected to a medium conveyance device, and the medium conveyance device includes a conveyance unit that conveys a medium to be conveyed, and conveyance of the medium to be conveyed. First and second reading means that are arranged apart from each other and detect the position of the end of the transported medium in a direction intersecting the transport direction of the transported medium, and the transported medium The position of the end portion is read while conveying the medium, and the program conveys the computer based on the measurement result, receiving means for receiving the measurement results of the first and second reading means from the medium conveying device. It is made to function as a detection means which detects the skew mode of the said to-be-conveyed medium in it.

  According to the present invention, it is possible to provide a technique for accurately detecting skew during transport of a transported medium.

Sectional drawing which showed schematic structure of the image reading apparatus in 1st to 3rd embodiment. Schematic which showed the positional relationship of the image reading sensor in 1st to 3rd embodiment. The block diagram of the image reading apparatus in 1st to 3rd embodiment. The flowchart of skew detection in 1st embodiment. Explanatory drawing showing the skew state, (A) no skew, (B) constant amount of controversy, (C) the skew amount changes. The flowchart of skew detection in 2nd embodiment. The flowchart of skew detection in 3rd embodiment.

  Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings. In each figure, the same reference numerals indicate the same elements. In each drawing, the vertical and horizontal directions with respect to the paper surface are used as the vertical and horizontal directions of the apparatus according to the present embodiment and used in the description in the text.

  FIG. 1 is a schematic diagram of an image reading apparatus 100 to which the medium conveyance device according to the embodiment is applied. In the schematic diagram shown in FIG. 1, each mechanical element is conceptually illustrated to explain a process in which a document (conveyed medium) F is conveyed in the image reading apparatus 100. Further, the medium conveying apparatus according to the present embodiment is not limited to the image reading apparatus 100 shown in FIG. 1, and is an apparatus that needs to convey the document F (medium to be conveyed), such as a printer. The present invention can also be applied to an image forming apparatus, a facsimile, a copying machine, and the like.

  On the left side of the image reading apparatus 100 in FIG. The document table 1 is loaded with a plurality of documents F and can be moved up and down by a document table drive motor 2. A document detection sensor 3 for detecting the document F on the document table 1 is disposed adjacent to the document table 1. A document feeding roller 4 is disposed in contact with the uppermost document F placed on the document table 1, and the document feeding roller 4 sends the document F from the document table 1 into the image reading apparatus 100. The document feeding motor 5 rotates the document feeding roller 4 via a known belt driving mechanism or the like.

  A feed roller 6 and a separation roller 7 are arranged in the vertical direction across the conveyance path through which the document F is conveyed. The feed roller 6 is rotated by a feed motor 9 through a known belt drive mechanism or the like in a direction in which the document F is transported downstream in the transport direction (rightward in FIG. 1). The separation roller 7 always receives a rotational force for conveying the document F upstream in the conveyance direction (left direction in FIG. 1) from the separation motor 8 via a slip clutch (not shown) via a known belt drive mechanism or the like. ing. When the document F is a single sheet, the separation roller 7 receives the conveying force of the document F and is allowed to follow the rotation of the feed roller 6 by the slip clutch and rotates. When there are a plurality of documents F, the separation roller 7 rotates in the direction of transporting the document F upstream, and transports the document F that contacts the separation roller 7 back to the upstream side.

  Due to the action of the feed roller 6 that transports the document F downstream, and the action of the separation roller 7 that transports the document F back upstream, the document F overlaps and is sandwiched between the feed roller 6 and the separation roller 7. When fed, the upper document F is conveyed downstream, the lower document F is pushed back upstream, and the overlapping documents F are separated and conveyed. Therefore, the feed roller 6 and the separation roller 7 constitute a pair of separation rollers 6 and 7. Note that a separation belt roller pair (not shown) may be used instead of the separation roller pair. A gap between the feed roller 6 and the separation roller 7 or a pressure contact pressure of the feed roller 6 with respect to the separation roller 7 is adjusted by a nip gap adjusting motor 11, and the document F is separated by a gap suitable for the thickness of the document F or a pressure contact pressure. It is designed to be transported.

  Further, the image reading apparatus 100 includes registration roller pairs 17 and 18, first transport roller pairs 20 and 21, second transport roller pairs 22 and 23, and third transport roller pairs 24 and 25. The 2nd conveyance roller 23 is rotated by the conveyance motor 10 which is a drive source via a well-known belt drive mechanism. The transport motor 10 can transport the separated document F from a document reading position (described later) to a discharge position, and can change the speed according to the resolution of the document F and the like.

  The pre-registration sensor 32 is disposed on the upstream side of the registration roller pair 17 and 18 and detects the document F being conveyed. The post-registration sensor 33 is disposed on the downstream side of the registration roller pair 17 and 18 and detects the document F being conveyed. The document detection sensor 34 is disposed downstream of the second transport roller pair 22 and 23 and detects the document F being transported.

  Further, the image reading apparatus 100 includes a pair of discharge rollers 26 and 27 at a discharge position of the document F, and the discharge roller 27 is driven by a discharge unit drive motor 28 that is a drive source via a known belt drive mechanism or the like. The The discharge roller pairs 26 and 27 convey the document F to the document discharge unit 44.

  An upper guide plate 40 is disposed between the separation roller pair 6 and 7 and the registration roller pair 17 and 18. A lower guide plate 41 is disposed on the upstream side of the pair of separation rollers 6 and 7. Two guide plates, an upper guide plate 40 and a lower guide plate 41, guide the document F conveyed between the feed roller 6, the separation roller 7, and the first and second roller pairs 20, 21, 22, and 23. To do.

  A first reading unit (first reading unit) 43 is disposed between the first conveyance roller pair 20 and 21 and the second conveyance roller pair 22 and 23 and below the conveyance surface. A second reading unit (second reading unit) 42 is disposed between the second conveyance roller pair 22 and 23 and the third conveyance roller pair 24 and 25 and above the conveyance surface. The In the first image portion 43, a document reading sensor (first image reading portion) 14 and a light source (first light source) 30 are arranged. In the second image section 42, a document reading sensor (second image reading section) 15 and a light source (second light source) 31 are arranged.

  As the document reading sensors 14 and 15, for example, a contact image sensor (CIS) can be adopted. As the document reading sensors 14 and 15, any other sensor system such as a CCD (Charged Coupled Devices) sensor using a reduction optical system may be used. Further, the document reading sensors 14 and 15 are not limited to reading an image or the like recorded on the document F, and can also read an end portion of the document F. For example, a backing portion having a color different from that of the document F is arranged at a position facing the respective document reading sensors 14 and 15 via the conveyance path, and the color density of the document F is set to the placed backing portion. Based on the difference, the document reading sensors 14 and 15 may read the edge of the document F. The edge of the document F indicates a predetermined area including the edge of the document F that forms the contour of the document F, but is not limited thereto, and may be simply the edge of the document F.

  The first and second image reading units 42 and 43 including the document reading sensors 14 and 15 can change the scanning interval based on the reading speed and resolution of the document F when reading the document F. The light sources 30 and 31 irradiate the document F with light, make the image and outline of the document F clearer by the light reflected from the document F, and read the document reading sensors 14 and 15 that receive this light. Contribute.

  The document discharge sensor 16 is disposed between the third transport roller pair 24, 25 and the discharge roller pair 26, 27, passes through the first and second image reading units 42, 43 and is discharged to the document discharge unit 44. Document F to be detected is detected. As described above, the conveying operation and the reading operation of the document F are performed, and an image can be acquired.

  FIG. 2 shows in detail the positional relationship of the image reading sensors 14 and 15 with respect to the first and second conveying roller pairs 20, 21, 22 and 23. In FIG. 2, for example, an image reading sensor 14 that reads the front surface (lower side surface in FIG. 2) of the document F reads the back surface (upper side surface in FIG. 2) of the document F across the document (conveyance path). 15 and on the upstream side (right side in FIG. 2) with respect to the transport direction (arrow D1 in FIG. 2). Further, the light sources 30 and 31 are arranged on the upstream side with respect to the respective image reading sensors 14 and 15. Note that the image reading sensors 14 and 15 can reverse the arrangement with respect to the conveyance direction, the arrangement with respect to the document (conveyance path), and the like.

  FIG. 3 is a block diagram illustrating a schematic configuration of an electric circuit of the image reading apparatus 100. The A / D conversion unit 70 converts the output signals of the image reading sensor 14 on the front surface and the image reading sensor 15 on the back surface into digital data after performing analog processing such as amplification and black level clamping. The image processing unit 71 controls the image reading sensors 14 and 15, the front surface light source 30 and the back surface light source 31, the A / D conversion unit 70, and the like, and the image data generated by digitizing the output signals of the image reading sensors 14 and 15. Various image processing (such as skew correction described later) is performed.

  The storage unit 12 stores image data and the like. The interface unit 72 is connected to an external host device 200 such as a PC by a signal cable 73. The CPU 57, the image processing unit 71, and the storage unit 12 serving as a control unit of the image reading apparatus 100 are connected to each other via a bus. The CPU 57 accesses the storage unit 12 via the image processing unit 71. A drive unit for feeding and transporting the document F (for example, the paper feed motor 9 and the transport motor 10 are operated by the motor drivers 74 and 75 receiving an instruction from the CPU 57 passing an exciting current. A pickup motor (not shown), a separation motor, and a paper discharge motor are also connected to a motor driver (not shown), and these motors are also operated when an excitation current is passed by the motor driver receiving an instruction from the CPU 57.

<First embodiment>
FIG. 4 is a flowchart illustrating a skew detection method in which the image reading apparatus 100 according to the first embodiment detects skew while the document F is being conveyed. When the image reading apparatus 100 starts reading in response to an instruction from an unillustrated external host device or the like, the image reading apparatus 100 starts a reading operation in S201. In step S <b> 202, the motor 9 is driven to feed the document F via the feeding roller 6, and the motor 10 is driven to transport the document F via the transport roller pair 22 and 23. For example, the CPU 57 transmits a command to the motor drivers 74 and 75, and the motor drivers 74 and 75 drive the motors 9 and 10 according to the received command.

  In S203, based on the detection result of the post-registration sensor 33, the CPU 57 determines whether or not the document F has passed the position of the post-registration sensor 33 in front of the image reading unit (first reading unit) 43 which is a surface sensor. . If the document F has not passed the position of the post-registration sensor 33 (NO in S203), the conveyance of the document F is repeated in S202.

  When the document F passes the position of the post-registration sensor 33 (YES in S203), the image reading sensor (first image reading unit) 14 of the image reading unit 43 starts image reading in S204.

  In S205, from the detection result of the document detection sensor 34, the CPU 57 determines whether or not the document F has passed the position of the document detection sensor 34 adjacent to the image reading unit (second reading unit) 42 which is a back surface sensor. To do. When the document F has not passed the position of the document detection sensor 34 (NO in S205), the CPU 57 transmits an instruction to the image reading unit 43 to read the document F.

  In step S <b> 206, the image reading unit 43 acquires image data for one line in the main scanning direction from the light emitted from the light source 30 and reflected from the surface of the document F in accordance with the received reading command. Here, a gradation level serving as a reference for determining the edge of the document F is set as a document edge detection threshold Th1.

  In S207, the information acquired by the image reading unit 43, that is, the gradation level for each pixel data for one line in the main scanning direction is compared with the document edge detection threshold Th1. Here, when the gradation level for each pixel data for one line in the main scanning direction acquired by the image reading unit 43 is smaller than the document edge detection threshold Th1 (NO in S207), it is assumed that the document edge reading is incomplete. The reading operation is continued by repeating S206 to S207.

  If the gradation level for each pixel data for one line in the main scanning direction acquired by the image reading unit 42 in S208 is equal to or higher than the document edge detection threshold Th1 (YES in S207), it is determined as the document edge, and the main scanning pixel position is determined. (Main scanning direction position (direction position intersecting the conveyance direction) and sub-scanning direction position (conveyance direction position)) are stored in the storage unit 12 as the pixel position of the document edge on the front side.

  In step S209, the CPU 57 calculates the amount of skew on the front surface from the amount of change in the pixel position at the front document edge stored in the storage unit 12, and returns to step S205. The skew amount refers to the amount of change in the pixel position (main scanning direction position) of the document edge on the front surface and the amount of movement of the document F in the transport direction (sub-scanning direction) used for detecting the skew mode of the document F. And the ratio.

  When the document F passes the position of the document detection sensor 34 (YES in S205), in S210, in addition to the image reading sensor 14 on the front surface, the image reading sensor (second reading) of the image reading unit (second reading unit) 42 on the back surface. The image reading unit 15 starts image reading.

  In S211, the image reading units 42 and 43 acquire image data for one line in the main scanning direction from the light emitted from the light sources 30 and 31 and reflected from the front and back surfaces of the document F in accordance with the received reading command. Here, the gradation level serving as a reference for determining the end portion of the document F in the same manner as described above is set as the document end detection threshold Th1.

  The gradation level for each pixel data for one line in the main scanning direction acquired by the image reading units 42 and 43 in S212 is compared with the document edge detection threshold Th1. When the gradation level for each pixel data for one line in the main scanning direction acquired by the image reading units 42 and 43 is smaller than the document edge detection threshold Th1 (NO in S212), the reading operation is continued by repeating S211 to S212. .

  When the gradation level for each pixel data for one line in the main scanning direction acquired by the image reading units 42 and 43 is equal to or higher than the document edge detection threshold Th1 (YES in S212), it is determined as the document edge in S213, and the main scanning pixel position is determined. (Main scanning direction position and sub-scanning direction position) are stored in the storage unit 12 as pixel positions of the document edges on the front and back surfaces, respectively.

  In S <b> 214, the CPU 57 calculates the skew amount of the front and back surfaces from the change amount of the pixel position of the front and back document edges and the change amount of the pixel position of the back document edge stored in the storage unit 12.

  In S215, the CPU 57 calculates the difference between the front and back skew amounts from the front and back skew amounts calculated in S209 and S214. The skew amount on the front surface and the skew amount on the back surface are compared with the skew amount at the end of the document F at the same position. Here, a skew amount difference Th2 serving as a reference for determining that the skew amount of the document F has changed during the reading operation is defined as a skew threshold Th2.

  In S216, the CPU 57 compares the skew amount difference between the front and back sides of the document F calculated in S215 with the skew threshold Th2.

  If the difference between the skew amount on the front surface and the skew amount on the back surface is smaller than the skew threshold Th2 (NO in S216), the skew has not occurred or the image after the scanning by the skew has been completed is corrected by the skew correction. The CPU 57 repeats S211 to S216, and continues the reading operation in S217.

  If the difference between the skew amount on the front surface and the skew amount on the back surface is equal to or greater than the skew threshold Th2 (YES in S216), the CPU 57 determines that the document F is skewed in S218, and ends the process.

  Here, FIGS. 5A, 5 </ b> B, and 5 </ b> C show states where the document F is conveyed, and each state will be described. FIG. 5A is a diagram illustrating a read image acquired when transported without skew. Since no skew has occurred, the skew amount difference calculated in S215 is smaller than the skew threshold Th2.

  FIG. 5B is a diagram illustrating a read image acquired when the sheet is conveyed with a constant skew amount. The skew amount calculated from the image data acquired by the image reading sensor 14 on the front surface and the image reading sensor 15 on the back surface is constant (same inclination). For this reason, the difference in the amount of skew calculated in S215 is smaller than the skew threshold Th2. Further, when the irregular document F is read, the read image as described above is obtained.

  FIG. 5C is a diagram showing a read image acquired when skewing occurs during conveyance. The same applies when the skew amount changes during the conveyance. The image reading sensor 14 on the front surface and the image reading sensor 15 on the back surface are disposed at positions separated from each other in the conveying direction as shown in FIG.

  When the skew amount changes when the motor 10 transports the document F through the transport roller pairs 22 and 23, the front and back images have the same sub-scanning direction (the same predetermined position on the document F) in a certain area. The image reading sensor 14 acquires image data that is not skewed from the document F, and the image reading sensor 15 on the back surface acquires image data that is skewed from the document F. Therefore, the skew amounts acquired from the image data acquired by the image reading sensors 14 and 15 have different inclinations. Therefore, the difference in the skew amount calculated in S215 is larger than the skew threshold Th2.

  As described above, in the first embodiment, the document F is read during image reading by obtaining the skew amount from the image data for one line in the main scanning direction at the same position of the document F acquired by the image reading units 42 and 43. Therefore, it is possible to provide an image reading apparatus that accurately determines that the skew amount has changed. That is, since the two image reading sensors on the front and back surfaces are arranged apart from each other in the conveyance direction, it can be accurately determined that the skew amount at the same position of the document F has changed during image reading.

  Further, when the difference between the skew amount on the front surface and the skew amount on the back surface is equal to or greater than the skew threshold Th2 (YES in S216), it can be determined that the document F whose skew amount has changed during conveyance is being read. The fact that the skew has changed during conveyance can be displayed on an external host device (not shown). Further, it is possible to distinguish between a case where an image of a document F whose skew feeding amount has changed during conveyance is scanned and a case where an image of an irregular document F is scanned. That is, since the skew amount at the same position on the front and back surfaces of the document F is determined, it is possible to distinguish between an image acquired when the skew amount changes during image reading and an image obtained by reading an irregular document F. Therefore, an appropriate skew correction process can be performed.

  When the difference between the skew amount on the front surface and the skew amount on the back surface is smaller than the skew threshold value Th2 (NO in S216), the document discharge sensor 16 causes the document F to pass through the image reading units 42 and 43 and the document discharge unit. It is detected whether it is discharged to 44 or not. When the document F is discharged to the document discharge unit 44, an optimum image can be acquired by performing skew correction processing on the image. Specifically, when the document F passes through the image reading units 42 and 43 and is discharged to the document discharge unit 44, the CPU 57 transmits a command to the image processing unit 71. The image processing unit 71 performs image processing on the image data acquired by the image reading units 42 and 43 in accordance with the received command, and then stores the image data in the storage unit 12.

<Second embodiment>
Next, an image reading apparatus according to the second embodiment will be described. The schematic configuration of the image reading apparatus according to the second embodiment is the same as that of the first embodiment (see FIGS. 1 to 3). FIG. 6 shows a flowchart of the skew detection method in the second embodiment. In addition, since each step from S301 to S315 corresponds to each step from S201 to S215 in the first embodiment described above, a description thereof will be omitted. Hereinafter, description will be made from S316.

  In S316, the CPU 57 compares the skew amount difference between the front and back sides of the document F calculated in S315 with the skew threshold Th2.

  If the difference between the skew amount on the front surface and the skew amount on the back surface is equal to or greater than the skew threshold value Th2 (YES in S316), the CPU 57 determines that the document F whose skew amount has changed during conveyance is being read. Then, a command is transmitted to the motor drivers 74 and 75 to stop the motors 9 and 10. In S317, the motor drivers 74 and 75 stop the conveyance of the motors 9 and 10 according to the received command. After stopping, the process ends. If the skew amount changes during image reading, the skew angle cannot be accurately calculated from the frame of the document F, and the skew correction processing cannot be performed. Therefore, it is necessary to stop the image reading. There is.

  At this time, the fact that the skew correction has not been properly performed may be displayed on an external host device (not shown). Similarly to the case of the first embodiment, it is possible to distinguish between a case where an image of a document F whose skew feeding amount has changed during conveyance is scanned and a case where an image of an irregular document F is scanned.

  If the difference between the skew amount on the front side and the skew amount on the back side is smaller than the skew threshold Th2 (NO in S316), the document discharge sensor 16 in S318 and the document F passes through the image reading units 42 and 43 and the document. It is detected whether or not it has been discharged to the discharge unit 44. In this case, an optimum image can be acquired by performing skew correction processing on the image.

  If the document F has not passed through the image reading units 42 and 43 and is not discharged to the document discharge unit 44 in S318 (NO in S318), the CPU 57 repeats S311 to S318 in S319 and continues the reading operation. When the document F passes through the image reading units 42 and 43 and is discharged to the document discharge unit 44 (YES in S318), the CPU 57 transmits a command to the image processing unit 71. In step S <b> 320, the image processing unit 71 performs image processing on the image data acquired by the image reading units 42 and 43 in accordance with the received command, and then stores the image data in the storage unit 12. The image processing includes skew correction processing for the image. By performing the skew correction process on the image, the user can obtain an optimum image.

  In the second embodiment, when the difference between the skew amount on the front surface and the skew amount on the back surface is equal to or greater than the skew threshold value Th2 (YES in S316), the CPU 57 does not stop the conveyance of the motors 9 and S315. The following control may be performed using the difference between the skew amount on the front surface and the skew amount on the back surface calculated in step (1). In an image reading apparatus configured to clean a reading glass (not shown) with a brush (not shown) attached to the conveying rollers 20 and 23 between the papers when the document F is continuously read, the timing for executing the cleaning and whether or not to execute the cleaning are controlled. To do. For example, when the CPU 57 determines that the document F is skewed, there is a possibility that a part of the document F does not pass through the reading glass, so that cleaning with a brush can be prevented.

<Third embodiment>
Next, an image reading apparatus according to the third embodiment will be described. The schematic configuration of the image reading apparatus according to the second embodiment is the same as that of the first embodiment (see FIGS. 1 to 3). FIG. 7 shows a flowchart of the skew detection method in the third embodiment. Since each step from S401 to S415 corresponds to each step from S201 to S215 in the first embodiment described above, a description thereof will be omitted. Hereinafter, description will be made from S416.

  In S416, the CPU 57 compares the skew amount difference between the front and back sides of the document F calculated in S415 with the skew threshold Th2. If the difference between the skew amount on the front surface and the skew amount on the back surface is equal to or greater than the skew threshold value Th2 (YES in S416), the CPU 57 determines that the document F whose skew amount has changed during conveyance is being read. Then, a command is transmitted to the motor drivers 74 and 75 to stop the motors 9 and 10. In S417, the motor drivers 74 and 75 stop the conveyance of the motors 9 and 10 according to the received command.

  In step S418, the CPU 57 controls the motor 10 in accordance with the calculated skew amount of the document F. If the skew amount is equal to or greater than the skew angle at which skew correction processing by image processing is possible, the document is corrected while correcting the skew state. After F is returned to the paper feed port, the process returns to S402 and image reading is performed again. If the skew amount is smaller than the angle at which skew correction processing is possible, the original F is returned to the paper feed port without correcting the skew, and then the process returns to S411 and image reading is performed again.

  When the difference between the skew amount on the front surface and the skew amount on the back surface is smaller than the skew threshold Th2 (NO in S416), the document discharge sensor 16 causes the document F to pass through the image reading units 42 and 43 in S419. It is detected whether or not the document is discharged to the document discharge unit 44.

  When the document F has not passed through the image reading units 42 and 43 and is not discharged to the document discharge unit 44 (NO in S419), the CPU 57 repeats S411 to S419 in S420 and continues the reading operation.

  When the document F passes through the image reading units 42 and 43 and is discharged to the document discharge unit 44 (YES in S419), in this case, the image is subjected to skew correction processing to obtain an optimal image. Can do. That is, the CPU 57 transmits a command to the image processing unit 71, and in S 421, the image processing unit 71 performs image processing on the image data acquired by the image reading units 42 and 43 according to the received command, and stores the image data in the storage unit 12. The image processing includes skew correction processing for the image. By performing the skew correction process on the image, the user can obtain an optimum image.

  As described above, when it is accurately determined that the skew amount of the document F has changed during image reading, the transport of the document F is stopped and the transport direction that is the reverse direction is corrected while correcting the skew of the document F. By returning to the upstream side and then carrying it again, the user can acquire an image that has been subjected to appropriate skew correction without worrying about the case where the skew amount changes during image reading.

<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.

  With the above configuration, in the present embodiment, the document F is obtained during image reading by obtaining the skew amount from the image data for one line in the main scanning direction at the same position of the document F acquired by the image reading units 42 and 43. Therefore, it is possible to provide an image reading apparatus that accurately determines that the skew amount has changed. That is, since the two image reading sensors on the front and back surfaces are arranged apart from each other in the conveyance direction, it can be accurately determined that the skew amount at the same position of the document F has changed during image reading. Further, it is possible to distinguish between a case where an image of a document F whose skew feeding amount has changed during conveyance is scanned and a case where an image of an irregular document F is scanned. In addition, when it is accurately determined that the skew amount of the document F has changed during image reading, the transport of the document F is stopped, and after returning to the upstream side in the transport direction while correcting the skew of the document F, By carrying it again, the user can acquire an image that has been subjected to appropriate skew correction without worrying about the case where the skew amount changes during image reading.

  As a device to which the medium conveying device is applied, in addition to the above-described image reading device, an image forming device such as a copying machine, a printer, a facsimile, or a complex machine thereof can be applied. In addition to the ink dot method, the image forming unit may be configured by an electrophotographic method, an electrostatic recording method, or the like.

DESCRIPTION OF SYMBOLS 1 Document platen, 2 Document platen drive motor, 3 Document detection sensor, 4 Document feed roller, 5 Document feed motor, 6 Feed roller, 7 Separation roller, 8 Separation motor, 9 Feed motor, 10 Conveyance motor, 11 Crevice Adjustment motor, 12 storage unit, 14, 15 image reading sensor, 16 document discharge sensor, 17, 18 registration roller, 20, 21, 22, 23, 24, 25 transport roller, 26, 27 discharge roller, 28 paper discharge motor, 30, 31 Light source, 32 Pre-registration sensor, 33 Post-registration sensor, 34 Document detection sensor, 40 Upper guide plate, 41 Lower guide plate, 42, 43 Image reading unit, 44 Document discharge unit, 57 CPU, 70 A / D conversion Section, 71 image processing section, 72 interface section, 73 signal cable, 74, 75 motor driver, 100 image reading Location, 200 external host device (PC), F document

Claims (9)

A conveying means for conveying a medium to be conveyed;
First and second reading means disposed apart from each other in the transport direction of the transported medium;
Detecting means for detecting a skew mode of the transported medium being transported based on information acquired by the first and second reading means;
A medium conveying apparatus comprising: The first and second reading means detect a position of an end of the transported medium in a direction intersecting the transport direction;
The medium conveying apparatus according to claim 1, wherein the detection unit detects a skew mode of the medium to be conveyed from the position of the end detected by the first and second reading units. The position of the end detected by the first and second reading means is the position of the end at the same predetermined position of the transported medium,
The detecting means includes a comparing means for comparing the position of the end portion detected by the first reading means and the position of the end portion detected by the second reading means,
The medium conveying apparatus according to claim 2, wherein the detecting unit detects a skew mode of the medium to be conveyed based on a result of the comparing unit. The first and second reading means respectively include first and second light sources that irradiate the transported medium with light,
First and second image reading means for receiving light emitted from the first and second light sources and reflected from the transported medium;
With
The said 1st and 2nd reading means detects the position of the said edge part from each image data which the said 1st and 2nd image reading means acquired, The Claim 1 characterized by the above-mentioned. The medium conveying apparatus as described.   The medium transport apparatus according to claim 1, further comprising a control unit that stops the transport unit according to a result of the detection unit.   6. The medium transport apparatus according to claim 5, wherein the control unit causes the transport unit to transport the transported medium in a direction opposite to the transport direction after the stop.   The medium conveying apparatus according to any one of claims 1 to 6, wherein the first and second reading units are arranged to face each other across a conveyance path of the medium to be conveyed. A medium conveying device according to any one of claims 1 to 7, comprising:
An image reading apparatus, wherein at least one of the first and second reading means reads an image of the transported medium. A program that is executed by a computer connected to the medium conveying device;
The medium conveying device is:
A conveying means for conveying a medium to be conveyed;
First and second reading means that are arranged apart from each other in the transport direction of the transported medium and detect the position of the end of the transported medium in a direction intersecting the transport direction of the transported medium;
Have
Read the position of the end while transporting the transported medium,
The program is a receiving means for receiving the detection results of the first and second reading means from the medium conveying apparatus.
Detection means for detecting a skew mode of the transported medium being transported based on the detection result;
Program to function as.

Images