JP2018098527A - Original reading device, control method of original reading device, image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To continue or cancel original feed by determining whether an original can be discharged to the outside of an original feeder without damage, when determined that skew correction of the original image is impossible.SOLUTION: In an original reader for reading the original image by means of a read sensor, when the skew amount of an original is detected in the main scanning direction by reading the coordinate value at the tip of the original transported in the sub-scanning direction by means of the read sensor, and a determination is made that the skew amount of the original exceeds a predetermined threshold level, the coordinate value at the rear end of the original is calculated. When a determination is made that the coordinate value at the rear end of the original thus calculated is a value capable of passing through the original transport path, the original is discharged, re-read of the discharged original is notified, and when a determination is made that the coordinate value cannot pass the original through the original transport path, from the coordinate value at the rear end of the original thus calculated, the original size, and the coordinate value at the tip of the original, transport of the original is canceled, and release of the stopped original is notified.SELECTED DRAWING: Figure 8

Description

  The present invention relates to an original reading apparatus, an original reading apparatus control method, and an image forming apparatus.

  2. Description of the Related Art Conventionally, an image forming apparatus including a document reading apparatus sets a plurality of documents on an automatic document feeder (hereinafter referred to as a document feeder (ADF)) and automatically transports the documents one by one. As a result, there is a so-called flow-reading method in which a document is read using a reading optical system device fixed at a document reading position. In this method, a bar-shaped light source is used, and a reading line is set in parallel with a direction (main scanning direction) perpendicular to the document conveyance direction (sub-scanning direction). Then, light is emitted from the light source to the image surface of the document being conveyed, and the reflected light when the image surface passes through the reading line is received to sequentially read the images on the image surface.

  Therefore, when the document is conveyed obliquely and the image passes obliquely through the reading line (hereinafter referred to as skew), the image is read obliquely. In the above-described image forming apparatus, when image formation is performed based on such a skewed original image, an image defect that an image is formed obliquely on the recording material occurs.

In order to prevent such a formed image defect from occurring, a technique for forming an image without skew by performing correction processing on the read image data according to the skew angle of the document is known. Correction processing for skewed image data is performed by storing a part of the image data in a memory and processing the image data stored in the memory. In order to create one line of read line for corrected image data, image data from end to end of the document is required, so the larger the skew angle, the more read line image data needs to be stored in memory. There is.
That is, the larger the skew angle, the larger the memory capacity required for the image data correction process and the longer the time required for the correction process. As a countermeasure against such a problem, a warning is displayed when the skew angle of the document exceeds a predetermined threshold value, and the skew image correction is not performed, or the skew correction processing at an angle smaller than the skew angle of the document is performed. There is a conventional technique in which a user is instructed whether to perform (Patent Document 1).

  In this conventional technique, the user cannot place the original on the original feeder and read the original again. As a countermeasure, the original reading is interrupted when the skew angle of the original exceeds a predetermined threshold. However, there is a technique for prompting the user to re-place the original.

JP 2000-244728 A

  However, in the above-described prior art, if an original whose reading has been interrupted is kept in the original feeder, the user must manually pull out the original from the original feeder, and the original may be damaged at that time. However, if the skewed document is transported as it is to be discharged out of the document feeder, the document may come into contact with the inner wall of the transport path during transport, causing a document jam and damage.

  The present invention has been made to solve the above problems. An object of the present invention is to determine whether or not a document can be discharged out of the document feeder without damaging the document when it is determined that the skew correction of the document image cannot be performed, and to continue or stop the document conveyance. It is to provide a mechanism that can do this.

The document reading apparatus of the present invention that achieves the above object has the following configuration.
An original reading apparatus that reads an image of an original with a reading sensor, and the reading sensor detects a skew value of the original with respect to the main scanning direction by reading a coordinate value of a leading end of the original conveyed in the sub-scanning direction. A detection unit; and a calculation unit that calculates a coordinate value of the trailing edge of the document detected by the detection unit when it is determined that the skew amount of the document detected by the detection unit exceeds a predetermined threshold value; When it is determined that the coordinate value of the trailing edge of the document calculated by the calculating unit is a value that can pass through the document conveyance path, the document is discharged and a first re-reading of the discharged document is notified. A value from which the document cannot pass without contacting the document conveyance path from the coordinate value of the trailing edge of the document calculated by the control unit, the size of the document, and the coordinate value of the leading edge of the document. If it is determined that Stops the conveyance of the document, characterized in that it comprises a second control means for notifying the cancellation of a document is stopped, the.

  According to the present invention, when it is determined that the skew correction of the document image cannot be performed, it is determined whether the document can be discharged out of the document feeder without damaging the document, and the document conveyance can be continued or stopped. it can.

2 is a block diagram illustrating a hardware configuration of the image forming apparatus. FIG. It is a block diagram which shows the structural example of a scanner control part. 2 is a cross-sectional view illustrating a configuration of a scanner provided in the image forming apparatus. FIG. It is a figure which shows an example of a skew conveyance model. It is a figure explaining the write-in or read-out process with respect to the memory for skew correction. FIG. 10 is a schematic diagram illustrating an example of skew state determination for a standard-size document. It is a figure which shows UI screen displayed on an operation part. 6 is a flowchart illustrating a method for controlling the document reading apparatus.

Next, the best mode for carrying out the present invention will be described with reference to the drawings.
<Description of system configuration>
[First Embodiment]

<Description of Image Forming Apparatus>

FIG. 1 is a block diagram illustrating a hardware configuration of the image forming apparatus according to the present exemplary embodiment. In this example, an example is a multi-function machine in which the controller unit 100 communicates with a scanner 113 serving as a document reading apparatus and a printer 114 to execute a copy function, a scan function, and a print function.
In FIG. 1, the image forming apparatus controls a controller unit 100 that controls the whole, a scanner 113 that is an image input device, and a printer 114 that is an image output device. Further, the image forming apparatus includes an operation unit 109 for inputting instructions from the operator and displaying information to the operator. The controller unit 100 controls the scanner 113, printer 114, and operation unit 109 connected thereto.

  The controller unit 100 has a CPU 101. A CPU 101 is a processor that controls the entire system, and is connected to a RAM 102, a ROM 103, an HDD 104, an operation unit I / F 106, and a network I / F 107 through a system bus 108. The CPU 101 comprehensively controls access to various connected devices based on a control program or the like stored in the ROM 103 or the HDD 104.

  A RAM 102 is a memory for providing a work area for the CPU 101. The RAM 102 is used as a setting value storage memory for temporarily recording parameter settings and an image memory for storing part of the image data. A ROM 103 is a boot ROM and stores a system boot program. The HDD 104 is a hard disk drive and stores system software, parameter setting value history, image data, and the like. A network I / F 107 is connected to the LAN 105 and inputs / outputs information to / from the LAN 105.

  The printer control unit 117 is connected to the printer 114 and communicates with the CPU 114A installed in the printer 114. In addition, the printer control unit 117 performs image processing for synchronous / asynchronous conversion of image data and print output. The printer 114 has at least one paper feed cassette for storing paper to be printed (not shown). Information such as the remaining amount of paper in each paper feed cassette and the presence / absence of toner is transmitted to the CPU 101 via the printer control unit 117.

  The scanner control unit 116 is connected to the scanner 113 and communicates with the CPU 113A mounted on the scanner 113. Further, the scanner control unit 116 performs image processing such as synchronous / asynchronous conversion of image data and skew correction processing described later.

  The operation unit I / F 106 is an interface for performing input / output between the controller unit 100 and the operation unit 109. The operation unit I / F 106 receives an instruction from the CPU 101, outputs image data to be displayed to the operation unit 109, and transmits information input by the operator via the operation unit 109 to the CPU 101.

<Scanner control unit>
FIG. 2 is a block diagram illustrating a configuration example of the scanner control unit 116 illustrated in FIG. The scanner control unit 116 corrects the skew feeding state of the document P by controlling the reading of image data written in a skew feeding correction memory 205 described later electrically, that is, the skew feeding state of the document P.

The shading correction unit 201 receives a Din pixel signal output from the scanner 113 when reading a document at a fixed position of the optical system in a flow reading mode described later. The shading correction unit 201 corrects the luminance unevenness due to the characteristics of the optical system and the imaging system using a known technique so as to obtain an image with uniform brightness, and outputs the pixel signal Dsh after the correction processing. Output to the subsequent stage.
The gamma correction unit 202 corrects a difference in color characteristics between the reading element and the device using a known technique. The pixel signal Dg subjected to the gamma correction process is output to the subsequent stage.

  The skew feeding correction unit 203 once writes the pixel signal Dg in the skew feeding correction memory 205 as image data. The skew correction memory 205 has a capacity capable of storing image data for a predetermined number of read lines. Based on the image data stored in the skew correction memory 205, the positions of both ends of the leading edge of the document and the skew amount of the document are calculated. The skew feeding correction unit 203 executes image position correction processing based on the calculated skew feeding amount, and outputs the pixel signal Ds subjected to the skew feeding correction processing to the subsequent stage. Details of the skew correction processing will be described later.

  Reference numeral 204 denotes a DMA controller (DMAC) that directly controls the pixel signal Ds output from the skew feeding correction unit 203 as image data Dout in a designated area of the RAM 102 without using the CPU 101.

  FIG. 3 is a cross-sectional view illustrating the configuration of the scanner included in the image forming apparatus according to the present embodiment. This example corresponds to the scanner 113 using a linear image sensor. In particular, a description will be given of the main configuration and reading operation in the case of “flow-reading” in which a document is read by operating the document feeder 115. The scanner 113 is communicably connected to the controller unit, and executes a document reading process, which will be described later, in accordance with a reading instruction from the controller unit 100.

  In FIG. 3, a document bundle 100P to be read is placed on a tray 309 by a user. Further, a delivery roller 301 and a separation / conveying roller pair 302 are disposed at the lower part in the document conveying direction.

  The feed roller 301 is rotated by a driving source (not shown) and feeds one document P separated from the document bundle 100P placed on the tray 309 to the downstream side. A separation / conveying roller pair 302 disposed downstream of the delivery roller 301 includes a drive roller and a stop roller that can be rotated by the drive source. Accordingly, the separating and conveying roller pair 302 separates and conveys the uppermost document P from the conveyed document bundle 100P. A drive source for driving the feed roller 301 and the separation / conveying roller pair 302 includes, for example, a stepping motor.

  The document P discharged from the pair of separation and conveyance rollers 302 travels along the document conveyance path along the guide plate 308, and is sandwiched between the large-diameter conveyance drum 303 and the driven rollers 304, 305, and 306, and the conveyance drum 303 It is conveyed along the outer periphery. At this time, the document P is once transported at a constant speed in the direction of the arrow passing through the surface of the document table glass 311.

  The image reading of the document P by an image reading unit, which will be described later, is performed when the document P passes through the surface of the document table glass 311. After the image reading, the image is continuously conveyed along the outer periphery of the conveyance drum 303 and is discharged onto the document feeder 115 by the discharge roller 307.

Next, the document reading operation of the scanner 113 in this embodiment will be described.
In the flow-reading mode, the document P passes through the surface of the document table glass 311 as described above. At this time, the first mirror unit 319 and the second mirror unit 320 are moved by the motor 318 and fixedly arranged at the positions shown in the drawing. Therefore, the original P is irradiated by the illumination lamp 312 in the first mirror unit 319 when facing the surface of the original table glass 311, and the reflected light passes through the mirrors 313, 314, 315, and on the CCD sensor 317 by the lens 316. Is imaged.

  The reflected light input to the CCD sensor 317 is converted into an electrical signal by the sensor, and the electrical signal of the pixel is converted to digital data by an A / D converter (not shown) and input to the controller unit 100 as a pixel signal Din.

In addition to the flow-reading mode, there is a method for reading an image by placing a document to be read on the platen glass 311. In the case of this method, the first mirror unit 319 including the mirror 313 and the illumination lamp 312 moves in the sub-scanning direction at a speed V under the document table glass 311 on which the document P is placed.
Further, the second mirror unit 320 including the mirrors 314 and 315 moves in the same direction as the first mirror unit 319 at a speed of 1/2 V, thereby scanning the entire surface of the document P.

<Details of skew correction processing>
The skew correction unit 203 mainly controls in which position (address) of the skew correction memory 205 the input pixel signal Dg is written or from which position the written pixel signal is read. The skew correction unit 203 writes pixel signals to the skew correction memory 205 and controls the reading position to correct image misalignment due to skew of the document in units of pixels. That is, the skew correction unit 203 realizes skew correction by changing the skew amount calculated based on the read position of the skew correction memory 205.

Hereinafter, the skew correction process will be described using the skew conveyance model shown in FIG. 4 as an example.
For example, assume that the main scanning width W2 is 600 pixels and the sub-scanning width L2 is 6 lines as shown in FIG. At this time, if it is desired to correct the shift amount in the sub-scanning direction, the reading position of the skew correction memory 205 may be shifted downward by one line (one pixel in the sub-scanning direction) in units of 100 pixels.

  Also assume that the main scanning width W1 shown in FIG. 4 is 4 pixels and the sub-scanning width L1 is 400 lines. At this time, if it is desired to correct the shift amount in the main scanning direction, the readout position of the skew correction memory 205 may be shifted by one pixel leftward in units of 100 lines.

  In FIG. 4, values such as W1, W2, L1, and L2 can be calculated using a trigonometric function if the skew feeding amount θ and the document size in the figure are known. For example, if the sub-scan size of the document P is C1 line and the main scan size is C2 pixels, W1 = C1 · sinθ, W2 = C2 · cosθ, L1 = C1 · cosθ, and L2 = C2 · sinθ.

Next, an example of writing and reading control by the skew feeding correction unit 203 to the skew feeding correction memory 205 by the skew feeding correction unit 203 will be described with reference to FIG.
FIG. 5 is a diagram for explaining a write or read process for the skew correction memory 205 shown in FIG. In FIGS. 5A, 5B, and 5C, 501 indicates the main scanning direction, and 502 indicates the sub-scanning direction. 5A shows the writing state of the pixel signal Dg to the skew correction memory 205, and FIGS. 5B and 5C show the reading state of the image signal Dg from the skew correction memory 205. FIG. Indicates.
In the example of FIG. 5, the size of the skew correction memory 205 in the sub-scanning direction is 7 lines from line 1 to line 7.

A control example in which the pixel signal Dg is written from the skew correction memory 205 by the skew correction unit 203 will be described with reference to FIG.
The pixel signal Dg subjected to signal processing by the γ correction unit 202 is written in the main scanning direction 501 in order from the line 1 of the skew correction memory 205. When writing to the last line (line 7 in this example) of the skew correction memory 205 is completed, the writing position in the sub-scanning direction is returned to the first line as shown in FIG. That is, as shown in 503 and 504, when the pixel signal Dg for the nth line of the document is written to the line 7 of the skew correction memory 205, the pixel signal Dg for the (n + 1) th line of the document is written back to the line 1. .

Next, a control example in which the pixel signal Ds is read out from the skew correction memory 205 by the skew correction unit 203 will be described with reference to FIG.
The skew correction unit 203 reads out along the main scanning direction 501 when the skew amount θ is calculated as 0 degree from the coordinates of the two vertices of the leading edge of the document. On the other hand, when the skew amount θ is not 0 degree, the readout of the pixel signal Ds is controlled in the direction of the arrow in the figure.
That is, the skew correction unit 203 reads the pixel signal Ds from the skew correction memory 205 while shifting the reading position in the sub-scanning direction 502 in accordance with the skew amount θ, and the position shift in the sub-scanning direction is set to one pixel Correct in units of (1 line). For example, if the main scanning width W2 is 600 pixels and the sub-scanning width L2 is 6 lines as described above, the reading position of one line is shifted downward in units of 100 pixels. Thereby, the positional deviation in the sub-scanning direction 502 is corrected in units of one line (pixel).

At this time, the position in the main scanning direction where reading is started is shifted line by line. For example, as described above, when the main scanning width W1 is 4 pixels and the sub-scanning width L1 is 400 lines, the reading start position of 1 pixel is shifted leftward in units of 100 lines. Thereby, the positional deviation in the main scanning direction is corrected in units of one pixel.
When the readout from the last line of the skew correction memory 205 is completed, the readout position in the sub-scanning direction is returned to the first line as indicated by the arrow in FIG.

  The skew correction unit 203 detects the two apexes of the leading edge of the document every time writing of one line to the skew correction memory 205 is completed, and starts reading from the skew correction memory 205 when it is detected. . Thereafter, every time one line is written, one line is read. In this manner, the skew feeding correction unit 203 controls writing and reading with respect to the skew feeding correction memory 205 synchronously. As a result, even if the memory capacity of the skew correction memory 205 is small with respect to the image size, it is possible to perform skew correction without destroying the image data and output it to the subsequent stage.

  In addition, the skew correction unit 203 can only perform correction in units of one pixel in the main scanning / sub-scanning direction in the memory control for writing or reading the image signal described above, and thus the image data is unstable. In order to correct such rattling (jaggy), the skew correction unit 203 performs interpolation processing such as a bilinear method and a bicubic method, which are known techniques.

<Method for Determining if Document and Contact with Inner Wall of Document Transport Path>
Next, a method for determining whether or not the document P and the inner wall of the document transport path are in contact with each other will be described with reference to FIG.
FIG. 6 is a schematic diagram illustrating a determination method when the document P is a standard size. FIG. 6 shows a state in which the positions of both ends of the leading edge of the document are specified from the pixel data stored in the skew correction memory 205 and the skew amount of the document is calculated from the coordinates of the two points. . The coordinates of the left vertex and the right vertex of the leading edge of the document are (x1, y1) and (x2, y2), respectively, and the skew amount of the document P is θ. In FIG. 6, solid lines L and R represent the extension lines of the left and right inner walls of the document transport path, and the x coordinates of the solid lines L and R are xL and xR, respectively.

よって、下記の条件が成立すれば原稿Ｐと原稿搬送経路の内壁とが接触しないと判定できる。

内壁のｘ座標にある程度マージンを持たせてｘＬ、ｘＲを設定することで、内壁に接触するリスクを下げることができる。
図７は、図１に示した操作部109に表示されるＵＩ画面を示す図である。なお、ＵＩ画面は、操作部109に搭載されている不図示のＬＣＤタッチパネルに表示される。以下、ポップアップ表示されるＵＩ画面について説明する。 In FIG. 6, whether or not the document P and the inner wall of the document transport path are in contact is determined by whether or not both vertices at the rear end of the document P are inside extension lines L and R of the inner wall of the document transport path. Can do. Here, assuming that the coordinates of the left and right vertices at the trailing edge of the document P are (x4, y4) and (x3, y3), respectively, and the length of the document P in the sub-scanning direction is C1, the x coordinates x4 and x3. Is obtained as follows.

Therefore, if the following condition is satisfied, it can be determined that the document P and the inner wall of the document transport path do not contact each other.

By setting xL and xR with a certain margin in the x coordinate of the inner wall, the risk of contact with the inner wall can be reduced.
FIG. 7 is a diagram showing a UI screen displayed on the operation unit 109 shown in FIG. The UI screen is displayed on an LCD touch panel (not shown) mounted on the operation unit 109. Hereinafter, a UI screen displayed as a pop-up will be described.

In FIG. 7A, 700 is a UI screen corresponding to the document skew correction error screen, and notifies the user that the skew correction of image data cannot be performed because the skew amount of the document exceeds a predetermined value. This is a pop-up screen. This screen is also a screen for notifying the rereading of the document.
Reference numeral 701 denotes a scan restart button, which is a button for restarting document reading after the user places the document on the tray 309 again. Reference numeral 702 denotes a cancel button for canceling the job.

In FIG. 7B, reference numeral 710 denotes a UI screen corresponding to the document skew jam screen, and it is determined that the document has stopped contacting the document because it is determined that the document contacts (contacts) the wall in the document transport path. It is a pop-up screen for notifying. This screen is also a screen for notifying the user of the cancellation of the document.
Reference numeral 711 denotes a scan restart button, which is a button for restarting document reading after the user places the document on the tray 309 again. Reference numeral 712 denotes a cancel button for canceling the job. When the user presses the scan restart button 711 or the cancel button 712 without taking out the remaining document from the document feeder 115, the CPU 101 detects the remaining document P by a document detection sensor (not shown) in the document feeder 115. Can do. In this case, the CPU 101 cancels the interrupted job, displays a document jam screen (not shown), and prompts the user to take out the document P from the document feeder 115.

<Processing flowchart>
FIG. 8 is a flowchart illustrating a method for controlling the document reading apparatus according to the present embodiment. This example corresponds to the skew correction control example. Each step is realized by executing a control program stored in the CPU.
First, in S101, the scanner control unit 116, which is instructed to start reading the document P from the CPU 101, initializes the number of read lines RLC held in a memory (not shown) to zero. The scanner control unit 116 instructs the skew correction unit 203 to erase the skew correction memory 205 and erase the skew amount information of the previous document, and then starts conveying the next document to the scanner 113. Instruct.

In S102, the scanner control unit 116 determines whether or not the read line number RLC is smaller than the upper limit of the number of lines. Here, the upper limit of the number of lines is the maximum value of the number of read lines that can store document image data in the skew correction memory 205, and is held in a register (not shown) provided in the scanner control unit 116.
In S102, when the scanner control unit 116 determines that the number of read lines RLC is smaller than the upper limit of the number of lines, the scanner control unit 116 performs line reading of the original P, and the skew correction unit 203 stores one line in the skew correction memory 205. (S103). Then, the scanner control unit 116 increments the read line number RLC by 1.

In step S <b> 104, the skew feeding correction unit 203 determines whether the two vertices at the leading edge of the document can be detected from the document image data stored in the skew correction memory 205. If it is determined in S104 that the two vertices at the front end of the document cannot be detected, the process returns to S102, and the document line reading is repeated up to the upper limit of the number of lines.
On the other hand, when it is determined in S104 that the skew correction unit 203 has detected the two vertices of the leading edge of the document, the skew correction unit 203 calculates the document skew amount θ of the document P from the detected coordinate values of the two vertices. (S105). The skew feeding correction unit 203 holds the calculated document skew feeding amount θ in the above-described register since it is used for skew feeding correction of the image until the document being read is finished thereafter.

Next, in S106, the scanner control unit 116 determines whether or not the calculated document skew amount θ is smaller than the threshold value x °. Here, the threshold value x ° is a threshold angle of the correction accuracy of the skew correction performed by the skew correction unit 203, and may be a fixed value or a value determined by the document size and the document orientation.
As described above, correction of a document image having a large skew amount requires a lot of processing time and affects the performance index of the image forming apparatus. Therefore, the skew amount which is not so large as about 1.5 ° is set as a threshold value. Is desirable.

In S106, when the scanner control unit 116 determines that the document skew amount θ is smaller than the threshold value x °, the scanner control unit 116 causes the skew correction unit 203 to execute the skew correction process described above. Further, the scanner control unit 116 transfers the pixel signal Ds to the designated area of the RAM 102 by the DMA controller 204 (S107).
Next, in S108, the scanner control unit 116 reads the next line of the document P, and the skew correction unit 203 stores image data for one line in the skew correction memory 205.

In step S109, the scanner control unit 116 analyzes the image data read in step S108 and detects the end of the document P. The scanner control unit 116 repeats the skew correction execution (S107) and the document line reading (S108) until the end of the document P is detected.
In S109, when the scanner control unit 116 detects the end of the document P in S109, the scanner control unit 116 ends the reading process of the document P, and proceeds to S110.

In S110, the CPU 101 determines whether or not the document P to be read still remains on the tray 309 by a document detection sensor (not shown) mounted on the tray 309 of the document feeder 115. If the CPU 101 determines that there is no document P to be read on the tray 309, the document reading process ends.
On the other hand, if the CPU 101 determines in S110 that the document P still remains on the tray 309, the process returns to S101, and the CPU 101 starts the next document P reading process.

  On the other hand, in S106, when the scanner control unit 116 determines that the skew amount θ is not smaller than the threshold value x °, the above-described method is performed using the coordinates of the two vertices at the leading edge of the document, the skew amount, and the document size. The coordinates of the two vertices at the end of the document are calculated (S111).

  Next, in S112, the scanner control unit 116 discharges the document P without contacting the inner wall of the transport path by the method shown in comparing the coordinates of the two apexes at the end of the document with the coordinates of the inner wall of the document transport path. Determine if you can. If the scanner control unit 116 determines that the document P can be discharged without contacting the inner wall of the transport path, the process proceeds to S113. Then, the scanner control unit 116 instructs the scanner 113 to discharge the document P, notifies the CPU 101 that the document P has been discharged because the skew amount exceeds a threshold value (allowable value) (S113), and performs processing. To S114.

  In step S114, the CPU 101 displays a document skew correction error screen 700 for notifying the user to place the document P on the tray 309 on the operation unit 109, suspends the job, and ends the document reading process. To do. Thereafter, when the user places the original P again on the tray 309 and presses the resume key on the skew detection screen, the CPU 101 resumes the interrupted job and resumes the original reading in S101.

  If it is determined in S112 that the document P cannot be discharged without being brought into contact with the inner wall of the conveyance path, the scanner control unit 116 regards that a document jam has occurred, and executes document skew feeding jam processing (S115). In step S115, the scanner control unit 116 instructs the scanner 113 to stop document conveyance, and notifies the CPU 101 that a document skew has occurred. Specifically, the scanner control unit 116 displays a message indicating that the conveyance of the document is stopped because the document itself may be damaged due to the skew of the document. Further, the scanner control unit 116 displays a message to the effect that the canceled document is opened by opening the cover of the document feeder, taking out the document, placing the document on the tray, and restarting the document.

In step S116, the CPU 101 displays a document skew jam screen 710 on the operation unit 109 to notify the user that the cover of the document feeder 115 is opened and the document inside is removed and placed on the tray 309. Further, the CPU 101 suspends the job and ends the document reading process.
Thereafter, when the user removes the original P from the original feeder 115 and re-places it on the tray 309 and presses the resume key on the skew detection screen, the CPU 101 resumes the suspended job, and in S101. Resume scanning.

  On the other hand, when it is determined in S102 that the number of read lines RLC has reached the upper limit of the number of lines, that is, it means that there are no two vertices at the leading edge of the document in the predetermined number of read lines. The amount of skew is expected to be large. Accordingly, in this case, the scanner control unit 116 regards that a document jam has occurred, performs document jam processing (S115), and advances the processing to S116.

  The present invention supplies a program that realizes one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium. It can also be realized by a process in which one or more processors in the computer of the system or apparatus read and execute the program. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

113 scanner
115 Document feeder
116 Scanner control unit
203 Skew correction unit
205 Skew correction memory

Claims (5)

A document reading device that reads an image of a document with a reading sensor,
Detecting means for detecting a skew amount in the main scanning direction of the document by reading the coordinate value of the leading edge of the document conveyed in the sub-scanning direction by the reading sensor;
A calculation unit that calculates a coordinate value of the trailing edge of the document detected by the detection unit when it is determined that the skew amount of the document detected by the detection unit exceeds a predetermined threshold;
When it is determined that the coordinate value of the trailing edge of the document calculated by the calculating unit is a value that can pass through the document conveyance path, the document is discharged and a first re-reading of the discharged document is notified. Control means;
Based on the coordinate value of the trailing edge of the document calculated by the calculation means, the size of the document, and the coordinate value of the leading edge of the document, it is determined that the document cannot pass without contacting the document conveyance path. The second control means for canceling the conveyance of the document and notifying the cancellation of the stopped document;
An original reading apparatus comprising: Storage means for storing image data of the original read by the reading sensor;
A correction unit that corrects the image data of the document stored in the storage unit in a line unit when it is determined that the skew amount of the document detected by the detection unit does not exceed a predetermined threshold;
The document reading apparatus according to claim 1, further comprising:   The detection unit detects a skew amount with respect to a main scanning direction of the document by reading coordinate values of two apexes of a leading edge of the document conveyed in the sub-scanning direction by the reading sensor. The document reading apparatus according to 1.   An image forming apparatus comprising the document reading device according to claim 1. A method of controlling a document reading device that reads an image of a document with a reading sensor,
A detection step in which the reading sensor detects the skew value of the document in the main scanning direction by reading the coordinate value of the leading edge of the document conveyed in the sub-scanning direction;
A calculation step of calculating a coordinate value of the trailing edge of the document detected in the detection step when it is determined that the skew amount of the document detected in the detection step exceeds a predetermined threshold;
When it is determined that the coordinate value of the trailing edge of the document calculated in the calculation step is a value that can pass through the document conveyance path, the document is discharged and a first re-reading of the discharged document is notified. Control process;
Based on the coordinate value of the trailing edge of the document calculated in the calculating step, the size of the document, and the coordinate value of the leading edge of the document, it is determined that the document cannot pass without contacting the document conveyance path. A second control step of canceling the conveyance of the document and notifying the cancellation of the stopped document;
An original reading apparatus control method comprising:

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