JP2017103699A - Image processing device and image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology capable of efficiently analyzing the existence/nonexistence of a stripe image.SOLUTION: An image processing device includes conveyance means for conveying an original along a conveyance path, image reading means for reading an image of the conveyed original, and image analyzing means for analyzing whether a stripe image along a conveyance direction is included in a background image of the original obtained by reading a tip part side or a rear end part side of the original in the conveyance direction. The image processing device may have a function for notifying a user of an occurrence of abnormality on the basis of an analysis result of the image analyzing means. Also, an image reader can include an image processing device.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an image processing apparatus and an image reading apparatus that analyze an image obtained when reading an image of a document. For example, in an image reading apparatus that reads a document image by moving the document on an image reading unit, The present invention relates to an image reading apparatus suitable for specifying a streak image caused by foreign matter such as dust or dirt on a reading unit.

  2. Description of the Related Art An image reading apparatus having an automatic document feeder (ADF: Auto Document Feeder) is known. Such an image reading apparatus reads a document fed from the ADF while conveying the document at a constant speed with the image reading unit fixed. Since this reading method only requires moving the document in a certain direction at a constant speed, the time interval between the documents is shortened compared to reading the document while moving the image reading unit while the document is fixed. There is an advantage that you can.

  In such a reading method, if foreign matter such as dust or dirt adheres to the glass surface of the document reading sensor, the foreign matter is detected as a black pixel or a white pixel in all scanning scans. Therefore, a streak appears at a position in the sub-scanning direction of the read image corresponding to the position of the black pixel or the white pixel, and there is a problem that the quality of the image obtained by reading is remarkably deteriorated.

  With regard to streaks due to foreign matters such as dust and dirt at the reading position, a method has been proposed in which pre-read data is acquired before the start of an image reading job and is detected by comparing it with read data of a document. . (See Patent Document 1)

JP 2009-246467 A

  However, in the method disclosed in Patent Document 1, an actual original image is acquired immediately before the start of an image reading job for line image detection, after the execution of an image reading job, or in a section outside the original area between originals. It is necessary to carry out an extra reading operation only for detecting dust and dirt, which is different from the above reading operation.

  The present invention provides a technique that can efficiently analyze the presence or absence of a streak image.

  The present invention relates to a conveying unit that conveys a document along a conveyance path, an image reading unit that reads an image of the conveyed document, and a document obtained by reading the leading end side or the trailing end side in the document conveying direction. Image analysis means for analyzing whether or not a streak image along the conveyance direction is included in the background image.

  According to the present invention, it is possible to realize an image processing apparatus that can efficiently analyze the presence or absence of a streak image.

1 is a schematic diagram of an image reading apparatus according to an embodiment of the present invention. The block diagram of the control unit which concerns on one Embodiment of this invention. FIG. 4 is a dust detection sequence diagram at an image leading end according to an embodiment of the present invention. FIG. 6 is a dust detection sequence diagram at the rear end of an image according to an embodiment of the present invention. FIG. 3 is a schematic diagram of a pre-read image and a post-read image according to an embodiment of the present invention. FIG. 3 is an image reading sequence diagram according to an embodiment of the present invention. FIG. 4 is an example of a read image according to an embodiment of the present invention. FIG. FIG. 4 is an example of a read image according to an embodiment of the present invention. FIG.

  Hereinafter, with reference to drawings, it explains in detail based on an embodiment of the invention.

FIG. 1 is a schematic diagram of an image reading apparatus according to an embodiment of the present invention.
<Device configuration>
The image reading apparatus shown in FIG. 1 is an apparatus that conveys one or a plurality of conveying media S stacked on a mounting table 1 one by one into the apparatus along a route RT, reads the image, and discharges the image onto a discharge tray 2. is there. The reading medium S to be read is, for example, a sheet such as OA paper, a check, a check, a business card, or a card, and may be a thick sheet or a thin sheet. Examples of the cards include an insurance card, a driver's license, and a credit card. The transport medium S also includes a booklet such as a passport. When targeting a booklet, a holder (not shown) can be used. By storing the booklet in a spread state in the holder and placing it on the mounting table 1, the booklet is transported together with the holder and the image can be read.

<Feed>
A first transport unit 10 is provided as a feeding mechanism that feeds the transport medium S along the route RT. In the case of this embodiment, the first transport unit 10 includes a feed roller 11 and a separation roller 12 disposed to face the feed roller 11, and sequentially transports the transport medium S on the mounting table 1 one by one in the transport direction D1. Transport.

<Driver>
A driving force is transmitted to the feed roller 11 from the driving unit 3 such as a motor through the transmission unit 5 and is rotationally driven in the direction of the arrow in the drawing (the forward direction in which the transport medium S is transported along the path RT). The transmission unit 5 is, for example, an electromagnetic clutch, and interrupts the driving force from the driving unit 3 to the feed roller 11.

<Separation structure>
The separation roller 12 disposed to face the feed roller 11 is a roller for separating the transport medium S one by one, and is in pressure contact with the feed roller 11 with a constant pressure. In order to secure this pressure contact state, the separation roller 12 is provided so as to be swingable and is urged to the feed roller 11. The separation roller 12 is driven to rotate in the direction indicated by the solid line arrow (the direction opposite to the forward direction of the feed roller 11) when the driving force is transmitted from the driving unit 3 via the torque limiter 12a.

  Since the driving force transmission is restricted by the torque limiter 12a, the separation roller 12 rotates in a direction (indicated by a broken arrow) along with the feed roller 11 when contacting the feed roller 11. As a result, when a plurality of transport media S are transported to the pressure contact portion between the feed roller 11 and the separation roller 12, two or more transport media S are blocked so that they are not transported downstream except one. .

  In the present embodiment, the separation roller 12 and the feed roller 11 constitute a separation mechanism. However, such a separation mechanism is not necessarily provided, and the conveyance medium S is sequentially fed to the path RT one by one. Any feeding mechanism may be used. In the case where a separation mechanism is provided, instead of the configuration of the separation roller 12, a separation pad that applies a frictional force to the transport medium S is brought into pressure contact with the feed roller 11 so as to have a similar separation operation. May be.

<Conveying structure>
The second transport unit 20 as a transport mechanism on the downstream side in the transport direction of the first transport unit 10 includes a drive roller 21 and a driven roller 22 driven by the drive roller 21 and has been transported from the first transport unit 10. The transported medium S is transported downstream. Driving force is transmitted to the driving roller 21 from the driving unit 4 such as a motor, and the driving roller 21 is rotationally driven in the direction of the arrow in the figure. The driven roller 22 is brought into pressure contact with the driving roller 21 at a constant pressure, and rotates with the driving roller 21. The driven roller 22 may be configured to be biased against the driving roller 21 by a biasing unit (not shown) such as a spring.

  The third transport unit 30 located downstream of the second transport unit 20 in the transport direction includes a drive roller 31 and a driven roller 32 that is driven by the drive roller 31 and is transported from the second transport unit 20. The transport medium S is transported to the discharge tray 2. That is, the third transport unit 30 functions as a discharge mechanism. Driving force is transmitted to the driving roller 31 from the driving unit 4 such as a motor, and the driving roller 31 is rotationally driven in the direction of the arrow in the figure. The driven roller 32 is brought into pressure contact with the driving roller 31 at a constant pressure, and is driven by the driving roller 31. The driven roller 32 may be configured to be biased against the driving roller 31 by a biasing unit (not shown) such as a spring.

  The discharge tray 2 is pivotally supported via a first hinge 101 provided below the image reading device A so as to be rotatable with respect to the image reading device A. Further, the first discharge tray 2a on the first hinge 101 side and the second discharge tray 2b connected to the tip end side thereof are configured, and the second discharge tray 2b is rotatable with respect to the first discharge tray 2a. Is pivotally supported.

<Image reading structure and control>
Here, in the image reading apparatus A of the present embodiment, since the image reading unit 70 disposed between the second transport unit 20 and the third transport unit 30 reads an image, the second transport unit 20 and the second transport unit 20 The three transport unit 30 transports the transport medium S at a constant speed. By always setting the transport speed to be equal to or higher than the transport speed of the first transport unit 10, it is possible to reliably avoid a situation in which the subsequent transport medium S catches up with the preceding transport medium S. For example, in this embodiment, speed control is performed so that the transport speed of the transport medium S by the second transport section 20 and the third transport section 30 is faster than the transport speed of the transport medium S by the first transport section 10. did.

  Even when the transport speed of the transport medium S by the second transport section 20 and the third transport section 30 and the transport speed of the transport medium S by the first transport section 10 are the same, the drive section 3 is controlled. It is also possible to form a minimum interval between the preceding transport medium S and the subsequent transport medium S by intermittently shifting the feeding start timing of the subsequent transport medium S.

<Double feed detection>
When the double feed detection sensor 40 disposed between the first transport unit 10 and the second transport unit 20 is in contact with transport media S such as paper due to static electricity or the like, and passes through the first transport unit 10 ( In other words, this is an example of a detection sensor (a sensor for detecting the behavior and state of the sheet) for detecting this in the case of a double feed state in which the sheets are conveyed in an overlapping manner. Various sensors can be used as the double feed detection sensor 40, but in the case of the present embodiment, it is an ultrasonic sensor, and includes an ultrasonic transmission unit 41 and a reception unit 42, and is a conveyance medium such as paper. Double feed is detected based on the principle that the attenuation amount of the ultrasonic wave passing through the transport medium S is different between the case where S is transported one by one and the case where S is transported one by one.

<Registration sensor>
The medium detection sensor 50 arranged on the downstream side in the conveyance direction with respect to the double feed detection sensor 40 is located on the upstream side of the second conveyance unit 20 and on the upstream side arranged on the downstream side of the first conveyance unit 10. This is an example of a detection sensor (a sensor for detecting the behavior and state of a sheet). The position of the transport medium S transported by the first transport unit 10, specifically, the position of the transport medium S at the detection position of the medium detection sensor 50. Detect whether the end has reached or passed. As the medium detection sensor 50, various sensors can be used. In the case of the present embodiment, the medium detection sensor 50 is an optical sensor, and includes a light emitting unit 51 and a light receiving unit 52. The transport medium S is detected based on the principle that the intensity (the amount of received light) changes.

  In the case of this embodiment, when the leading edge of the transport medium S is detected by the medium detection sensor 50, the above medium is used so that the transport medium S reaches a position where the double feed detection sensor 40 can detect double feed. The detection sensor 50 is provided on the downstream side in the vicinity of the double feed detection sensor 40. The medium detection sensor 50 is not limited to the optical sensor described above. For example, a sensor (image sensor or the like) that can detect the end of the transport medium S may be used, or a lever-type sensor that protrudes into the path RT. It may be a sensor.

  A medium detection sensor 60 different from the medium detection sensor 50 is disposed on the upstream side of the image reading unit 70. This is an example of a downstream detection sensor disposed downstream of the second transport unit 20 and detects the position of the transport medium S transported by the second transport unit 20. Various media detection sensors 60 can be used. In the case of the present embodiment, the medium detection sensor 60 is an optical sensor similar to the medium detection sensor 50, and includes a light emitting unit 61 and a light receiving unit 62. The transport medium S is detected based on the principle that the received light intensity (received light amount) changes due to arrival or passage. In the present embodiment, the medium detection sensors 50 and 60 are disposed on the upstream side and the downstream side in the transport direction of the second transport unit 20, respectively, but only one of them may be used.

<Image reading unit arrangement>
The image reading unit 70 on the downstream side of the medium detection sensors 50 and 60 is, for example, optically scanned, converted into an electric signal and read as image data, and includes a light source such as an LED, an image sensor, A lens array is provided. In the present embodiment, one image reading unit 70 is disposed on each side of the path RT, and reads the front and back surfaces of the transport medium S. However, only one side of the path RT may be arranged to read only one side of the transport medium S. Further, in the present embodiment, the image reading unit 70 is configured to be opposed to both sides of the route RT. However, for example, the image reading unit 70 may be arranged with an interval in the direction of the route RT.
A background plate 70a that can be switched to white or black as a background at the time of reading is provided at a position facing the conveyance path of the image reading unit 70.

<Explanation of block diagram>
The control unit 80 will be described with reference to FIG. FIG. 2 is a block diagram of the control unit 80 of the image reading apparatus A.
The control unit 80 includes a CPU 81, a storage unit 82, an operation unit 83, a communication unit 84, an actuator 85, a sensor 87, and an image processing unit 86. The CPU 81 controls the entire image reading apparatus A by executing a program stored in the storage unit 82. The storage unit 82 includes, for example, a RAM, a ROM, and the like. The operation unit 83 includes, for example, a switch, a touch panel, and the like, and accepts an operation from the operator. The actuator 85 includes the drive unit 3, the drive unit 4, the transmission unit 5, and the like, and inputs and outputs data to and from the CPU 81. The sensor 86 includes a double feed detection sensor 40 and medium detection sensors 50 and 60.

  The communication unit 84 is an interface that performs information communication with an external device. When a PC (personal computer) is assumed as the external device, examples of the communication unit 84 include a USB interface and a SCSI interface. In addition to such a wired communication interface, the communication unit 84 may be a wireless communication interface, and may include both wired communication and wireless communication interfaces.

  The image processing unit 86 is connected to an image reading unit 89 and an image analysis unit 88. The image processing unit 86 has a function of processing the image data read by the image reading unit 89. The image processing unit 86 has a function of transmitting the image data read from the image reading unit 89 to the image analysis unit 88.

  The image analysis unit 88 performs an abnormality analysis of the image data transmitted from the image processing unit 86 and notifies the image processing unit 86 of the result.

<Driving by receiving start instruction from PC>
A basic operation of the image reading apparatus A will be described. When the control unit 80 receives an image reading start instruction from, for example, an external personal computer to which the image reading apparatus A is connected, the transport medium S loaded on the mounting table 1 is one by one from the transport medium S positioned at the bottom. Be transported.

<Control during double feeding>
In the middle of the conveyance, the conveyance medium S is determined by the double-feed detection sensor 40 to determine whether or not there is a double-feed. If it is determined that there is a double feed, the transport is stopped or the capture of the subsequent transport medium S by the first transport unit 10 is stopped, and the transport medium S in the double feed state is discharged as it is. It may be.

<Reading start according to the output of the registration sensor>
The control unit 80 starts reading the image by the image reading units 70 and 70 of the transport medium S transported by the second transport unit 20 at a timing based on the detection result of the medium detection sensor 60, and reads the read image. Temporarily memorize and send to external PC. The transport medium S on which the image has been read is discharged to the discharge tray 2 by the third transport unit 30, and the image reading process for the transport medium S is completed. Here, the image reading start timing for the document is set before the leading edge of the document reaches the image reading position of the image reading unit 70. In addition, the timing for finishing the image reading of one original is set to be after a predetermined time has elapsed since the trailing edge of the original passes through the image reading position of the image reading unit 70. Thereby, even if the document is skewed in the conveyance path, it is possible to prevent the document area from being lost. That is, the leading edge portion and the trailing edge portion of the document are redundantly read as a peripheral image of the document area including the background, and a margin (background portion of the document) is given to the leading edge side or the trailing edge side of the document. For example, the margin may be automatically given on the image reading apparatus side in advance, or control of the image reading apparatus installed in the image reading apparatus or a personal computer connected to the image reading apparatus. The user may arbitrarily set the settings on the setting screen which is a user interface through the application. In the latter case, the margin setting information received through the user interface of the control application is transmitted to the image reading apparatus directly or through the control driver, and the image reading apparatus controls the timing of image reading start based on the margin setting information.

<Dust analysis in the image analysis unit>
A dust analysis method of an image analysis unit (an example of image analysis means) 88 using the read image leading end will be described. The image read by the image reading unit 70 is sent to the storage unit 82. The image analysis unit 88 sequentially takes out the read data for the number Ltop lines of the number of lines at the front end in the sub-scanning direction of the image read from the storage unit 82 and converts it into 256-level density data, for example, 0 for black and 255 for white. (Step S101). Note that the obtained image data is _SNm (represents data of the mth pixel in the main scanning direction of the Nth line in the subscanning direction).

If the image data S _{0m of} line 0 is less than or equal to the dust determination threshold Lg, 1 is set to the dust detection data Sg _m (step 103). The dust determination threshold value Lg can be set to an arbitrary value at an arbitrary timing, and may be set via the operation unit 82, for example.

It is confirmed whether the comparison has been made up to the final pixel (step S105). If not compared to the last pixel, the process returns to step S103. If the comparison has been performed up to the final pixel, it is confirmed whether the comparison has been completed up to the line Ltop (step S106). If the comparison has not been completed up to the line Ltop, the data of the next line is read (step S107), and the process returns to step S103. If the comparison to the line Ltop has been completed, to check whether the value in the dust detection data Sg _m is what has become Ltop (step S108), the dust detection data Sg _m had become Ltop In this case, it is determined that streaks due to foreign matters such as dust and dirt have occurred, and a dust flag is set (step S109). If it is not reversed, it is determined that there are no streaks due to foreign matter such as dust or dirt.

  If there is a streak due to foreign matter such as dust or dirt, for example, an external control device (for example, a personal computer) connected to the operation unit 83 or the communication unit 84 is notified that dust is attached to the reading unit. By this notification, the user can immediately know that the streak due to the foreign matter has occurred, and can quickly take measures against the foreign matter and enable efficient reading.

Similarly, a dust analysis method of the image analysis unit 88 using the rear end portion of the read image will be described. The image read by the image reading unit 70 is sent to the storage unit 82. The image analysis unit 88 sequentially takes out read data for the number Lear of the number of lines at the rear end in the sub-scanning direction of the image read from the storage unit 82, and converts it into 256-level density data, for example, 0 for black and 255 for white. Conversion is performed (step S201). From the last line Lrear-1 line preceding image data _{S Nm} is less dust determination threshold value Lg, sets 1 to the dust detection data Sg _m (step 203). It is confirmed whether the comparison has been made up to the final pixel (step S205). If not compared to the last pixel, the process returns to step S203.

If the comparison has been performed up to the final pixel, it is confirmed whether the processing for the L rear line has been completed and the comparison has been completed up to the final line (step S206). If the comparison has not been completed up to the last line, the data of the next line is read (step S207), and the process returns to step S203. If the comparison to the last line has been completed, to check whether the value in the dust detection data Sg _m is what has become Lrear (step S208), the dust detection data Sg _m is in Lrear In this case, it is determined that streaks due to foreign matters such as dust and dirt have occurred, and a dust flag is set (step S209). If not, it is determined that there are no streaks due to foreign matters such as dust and dirt.

  If there is a streak due to foreign matter such as dust or dirt, for example, an external control device (for example, a personal computer) connected to the operation unit 83 or the communication unit 84 is notified that dust is attached to the reading unit. By this notification, the user can immediately know that the streak due to the foreign matter has occurred, and can quickly take measures against the foreign matter and enable efficient reading.

  As described above, if streaks due to foreign matters such as dust and dirt can be detected at the leading edge of the image, the image data of the transport medium that has been transported and read immediately is normal, and the image data of the transport medium that is currently transported You can immediately see that there are streaks due to foreign matter. Therefore, at the same time that the user is notified of dust adhering, when resuming reading, it is possible to instruct which transport medium should be resumed (in this case, the currently transported transport medium), and reading can be performed in a short time without waste. It is possible to resume. If a streak caused by a foreign matter can be detected at the rear end of the image, it can be immediately recognized that there is a streak caused by a foreign matter in the read image data, and it can be instructed whether to resume from the last transported medium. That is, even if not all the images of the document are read, the subsequent image reading can be interrupted when the streak image is generated in the background area of the document. Of course, according to the present invention, even after the image of the document area is read, it is not determined whether the streak image exists in the entire document area, and the streak image is partially detected in the read image (only the background area of the document). By confirming the existence, earlier detection becomes possible. Of course, if the presence or absence of a streak image is analyzed in the background area of the original in the read image after reading all the images of the original, the processing load is reduced as compared to analyzing all the images of the original.

As mentioned above, although this invention was demonstrated in detail based on one Embodiment, this invention is not limited to one Embodiment mentioned above.
In the above example, the dust analysis is performed in the image analysis unit, the dust analysis is performed while acquiring the image reading data at the leading end of the scanned image, or the dust analysis is performed while the image data at the trailing end of the scanned image is performed. However, the present invention is not limited to this, and the dust analysis in the image analysis unit is performed by taking out the read data of the leading end portion or the rear end portion from the data read after reading the entire document, and performing the dust analysis in the image analysis unit. An example in which dust analysis is performed after the entire document has been read will be described below. Note that parts different from the above-described embodiment will be described.

  Specifically, the image read by the image reading unit 70 is sent to the storage unit 82. When the reading of the document is completed, the image processing unit 88 acquires the image data of the leading edge or the trailing edge, or the leading edge and the trailing edge, which is the background area of the document, from the image data read from the storage unit 82, The image analysis unit 88 is instructed to start dust analysis.

  As described above, after reading the entire image of the document, if the data at the leading edge or trailing edge of the scanned image is taken out and the dust analysis is performed to detect streaks due to foreign matter such as dust or dirt, the scanned image Since only a part of the analysis process needs to be performed, the processing load can be reduced. In addition, when streak detection is performed on the entire document image, if the document contains vertical ruled lines, etc., there is a possibility of false detection of streaks. Therefore, the streak image can be detected with high accuracy without erroneously detecting the streak.

<Other embodiments>
As mentioned above, although this invention was demonstrated in detail based on one Embodiment, this invention is not limited to one Embodiment mentioned above.
For example, in the above-described embodiment, the detection of the streak image at the leading edge or the trailing edge of the image has been described. However, the present invention is not limited to this, and scanning is performed before the leading edge of the document reaches the image reading position. The streak image may be detected based on the image.

  Specifically, an example of streak image detection by prefetch processing will be described. Note that prefetching processing, which is different from the above-described embodiment, will be described. The position of the transport medium S transported by the first transport unit 10, specifically, whether or not the end of the transport medium S has reached or passed through the detection position of the medium detection sensor 50 is detected. As the medium detection sensor 50, various sensors can be used. In the case of this embodiment, the medium detection sensor 50 is an optical sensor, and includes a light emitting unit 51 and a light receiving unit 52, and receives light when the transport medium S reaches or passes therethrough. The transport medium S is detected based on the principle that the intensity (the amount of received light) changes. The medium detection sensor 50 is not limited to the optical sensor described above. For example, a sensor (image sensor or the like) that can detect the end of the transport medium S may be used, or a lever-type sensor that protrudes into the path RT. It may be a sensor.

  The time from when the medium detection sensor 50 detects the arrival of the medium S to when the leading end of the medium S reaches the image reading unit 70 is defined as T1. Reading of the medium S by the image reading unit 70 is started earlier by T2 time than the leading end of the medium S arrives. That is, image reading is started from the time when T1-T2 time has elapsed after the leading end of the medium S reaches the medium detection sensor 50. Note that T1> T2 and it is necessary to capture image data of Ltop lines or more in the sub-scanning direction during T2.

  The time T2 can be set to an arbitrary value that satisfies the above-described restrictions at an arbitrary timing, and may be set via the operation unit 82, for example.

  Accordingly, as shown in FIG. 5B, the leading edge of the image data read from the image reading sensor 70 is obtained as a pre-read image before the reading of the medium S is started. Even if there is a vertical streak-like pattern at the tip of the medium S, dust analysis can be performed using an image pre-read from the medium S, so that the adhesion of dust can be detected reliably and instantly regardless of the pattern on the medium S. It becomes possible to do.

  In the above description, the streak image is detected on the front end side of the image. However, the present invention is not limited to this, and the streak image may be detected on the rear end side of the image. An example of streak image detection by post-read processing will be described. The post-reading process, which is a different part from the above-described embodiment, will be described.

  Specifically, it detects whether or not the end of the transport medium S has reached or passed through the position of the transport medium S transported by the first transport unit 10, specifically, the detection position of the medium detection sensor 50. As the medium detection sensor 50, various sensors can be used. In the case of this embodiment, the medium detection sensor 50 is an optical sensor, and includes a light emitting unit 51 and a light receiving unit 52, and receives light when the transport medium S reaches or passes therethrough. The transport medium S is detected based on the principle that the intensity (the amount of received light) changes. The medium detection sensor 50 is not limited to the optical sensor described above. For example, a sensor (image sensor or the like) that can detect the end of the transport medium S may be used, or a lever-type sensor that protrudes into the path RT. It may be a sensor.

  The time from when the medium detection sensor 50 detects the passage of the medium S to when the trailing edge of the medium S reaches the image reading unit 70 is T3. The reading of the medium S by the image reading unit 70 is performed for T4 hours after the rear end of the medium S passes through the image reading unit 70. In other words, the image reading is continued until T3 + T4 time elapses after the rear end of the medium S passes through the medium detection sensor 50. Note that it is necessary to capture image data of the Lear line or more in the sub-scanning direction during T4 time. The time T4 can be set to an arbitrary value that satisfies the above-described restrictions at an arbitrary timing, and may be set via the operation unit 82, for example. Therefore, the rear end portion of the image data read from the image reading sensor 70 can obtain a post-read image even after the reading of the medium S is completed as shown in FIG. Even if there is a vertical streak-like pattern at the rear end of the medium S, dust analysis can be performed using an image read later from the medium S, so that the medium S can reliably read the image regardless of the pattern of the medium S. While passing through the unit 70, it is possible to immediately detect dust attached to the image reading unit 70.

  In the above description, the streak image detection by the pre-reading process and the post-reading process for reading the image of the document has been described. Of course, the present invention is not limited to this. For example, the present invention can also be applied to a case where a streak image is detected by switching the background plate during the pre-reading process and the post-reading process. Hereinafter, a reading process which is a different part from the above-described embodiment will be described.

  Specifically, white or black is used for the background plate 70a as a background color when reading an image. In this example, the background plate 70a shown in FIG. 6 is composed of two colors, white and black, and the background plate 70a is moved during pre-reading and post-reading to switch between white and black as the background of the image reading unit 70. Indicates a possible case. In this example, the background plate 70a is slid in the horizontal direction in the figure to switch the background color of the opposing surface across the conveyance path of the image reading unit 70 to the white background plate 70c and the black background plate 70d. The background color may be switched by a rotating body, and the switching means is not particularly limited.

  An image reading sequence is shown in FIG. When the CPU 81 receives a reading instruction from the operation unit 83 or the communication unit 84, the background plate 70a located at the position facing the image reading unit 70 with the conveyance path 71 interposed therebetween is replaced with the white background plate 70c using the background plate switching motor 70b. Is switched to the black background plate 70d (step S301).

  Wait until the medium detection sensor 50 detects the arrival of the medium S (step S302). When the medium detection sensor 50 detects the arrival of the medium S, step S303 is performed. Wait until T1-T2 time elapses after the medium detection sensor 50 detects the arrival of the medium S (step S303). Here, T <b> 1 is the time from when the leading edge of the medium S is detected by the medium detection sensor 50 until reaching the image reading unit 70. T2 is the time from the start of reading by the image reading unit 70 until the leading edge of the medium S reaches the image reading unit 70. That is, T1-T2 time is the time from when the leading edge of the medium S is detected by the reading detection sensor 50 until reading is started. Therefore, the relationship of T1> T2 needs to be satisfied. When the time T1-T2 has elapsed, reading is started by the image reading unit in step S304. At this time, since the background plate 70a at the opposite position across the conveyance path 71 of the image reading unit 70 is the black background plate 70d, the read image becomes a black background image.

  Wait until T21 time elapses from the start of reading (step S305). Here, T21 is the time from the start of reading until the background switching of the background plate 70a is performed, and is the time when the black background plate 70d is the background. After T21 time elapses, the background plate 70a is switched from the black background plate 70d to the white background plate 70c (step S306). At this time, the time required for switching is T22 time. After switching, the read image becomes a white background image. The leading end of the medium S reaches the image reading unit 70 T23 hours after the background plate switching is completed. Here, T23 is the time from when the background plate 70a is switched from the black background plate 70d to the white background plate 70c until the leading edge of the medium S reaches the image reading unit 70. Accordingly, the relationship T2 = T21 + T22 + T23 is established.

  Waiting until the medium detection sensor 50 detects the passage of the medium S while continuing the reading (step S307). When the medium detection sensor 50 detects the passage of the medium S, step S308 is performed. After the medium detection sensor 50 detects the passage of the medium S, it waits for the elapse of T3 + T41 time (step S308). Here, T3 is the time from when the trailing edge of the medium S is detected by the medium detection sensor 50 until reaching the image reading unit 70. T41 is the time from when the trailing edge of the medium S reaches the image reading unit 70 until the background plate 70a is switched from the white background plate 70c to the black background plate 70d. After the time T3 + T41, the background plate 70a is switched from the white background plate 70c to the black background plate 70d (step S309). At this time, the time required for switching is T42 time. After switching, the read image becomes a black background image. Wait until T43 time elapses after completing the switching of the background plate (step S310). Here, T43 is the time from when the background plate 70a is switched from the white background plate 70c to the black background plate 70d until reading is stopped. That is, the post-reading is performed for the time T4 (= T41 + T42 + T43) after the rear end of the medium S passes the reading sensor. When the final medium S is read after the reading is stopped, the reading operation is completed. If the final medium S has not been read, the reading operation is continued.

  A read image of one medium S obtained by the above sequence is as shown in FIG. Here, it is difficult to determine whether white dust attached to the reading sensor is a streak due to dust in the white background portion, but it is possible to determine that it is a streak due to dust in the black background portion. . Conversely, it is possible to determine that black dust is a streak due to dust in the white background portion. For an image read with a black background in the pre-read or post-read section, for example, each pixel data obtained by converting each read pixel into 256-level density data in which black is 0 and white is 255 is a dust determination threshold (black background). ) Compared with Lg_blk, if there is pixel data whose pixel data is greater than or equal to the dust determination threshold (black background) Lg_blk, it is determined that there is dust. Note that the dust determination threshold (black background) Lg_blk can be set to an arbitrary value at an arbitrary timing, and may be set, for example, via the operation unit 82.

  Similarly, for an image read with a white background in the pre-reading or post-reading portion, each pixel data obtained by converting each read pixel into 256-level density data in which black is 0 and white is 255 is set as a dust determination threshold ( White background) Compared with Lg_wht, if there is pixel data whose pixel data is less than or equal to the dust determination threshold (white background) Lg_wht, it is determined that there is dust. Note that the dust determination threshold (white background) Lg_wht can be set to an arbitrary value at an arbitrary timing, and may be set via the operation unit 82, for example.

  In this way, by switching the background plate 70a during pre-reading and post-reading, it is possible to reliably detect streaks due to dust, whether black dust or white dust.

As mentioned above, although this invention was demonstrated in detail based on one Embodiment, this invention is not limited to one Embodiment mentioned above. In the above description, an example in which a streak image is detected at the front end portion or the rear end portion has been described. However, both the front end portion and the rear end portion may be analyzed to detect the presence of a streak image in either one. An example in which a streak image is detected at both the front end and the rear end will be described. In addition, the alerting | reporting process to the user after the stripe detection which is a different part from one Example mentioned above is demonstrated.

  Specifically, when the image analysis unit 88 performs dust analysis and the image analysis unit 88 detects that there is dust at the tip, for example, an external control device (for example, a personal computer) connected to the operation unit 83 or the communication unit 84 ), It is possible to notify the user that dust is attached to the image reading unit 89 and that there is a possibility of streaking on the read image of the original to be read. At the same time as the notification, the user may select to continue reading or clean the image reading unit 89 to perform re-reading.

Similarly, when the image analysis unit 88 detects that there is dust at the rear end, it can notify the user that there is a high possibility that the image of the document read by the user has a streak. In this case, since the document has already been read, the read image may be displayed on an external control device (for example, a personal computer) connected to the operation unit 83 or the communication unit 84 to prompt the user to confirm the image. At this time, the displayed read image may be displayed so that the streak position can be easily recognized by, for example, adding a mark so that the streak position can be recognized. Further, as described above, the user continues reading, disables the streak image detection at the P pixels before and after the main scanning direction of the pixel where the detected streak image appears, continues reading, and rereads without cleaning the image reading unit 89. The image reading unit 89 may be cleaned and re-reading may be selected. In the case of continuing reading while ignoring the streak image near the detected streak image, it may be ignored until the batch is completed, and cleaning may be promoted after the batch is completed. In addition, the number of pixels P that determines the range in which the detection of the streak image is invalid can be set to an arbitrary value at an arbitrary timing, and may be set via the operation unit 82, for example.

As described above, if streak detection is performed at both the front end portion and the rear end portion, the streak due to dust can be detected more reliably than when streak detection is performed only at the front end portion or only at the rear end portion. It becomes possible. Further, the content notified to the user can be changed depending on whether the streak is detected at the front end or the rear end, and more effective post-processing can be performed. Of course, the processing load is reduced rather than detecting a streak image in the entire read image.

As mentioned above, although this invention was demonstrated in detail based on one Embodiment, this invention is not limited to one Embodiment mentioned above.
For example, in the above-described embodiment, an example is described in which when a streak image is detected at either the front end or the rear end of the image, the user is immediately notified as streak detection. However, the present invention is not limited to this. When a streak image is detected at the front end (or rear end), the user may be notified after confirming the presence or absence of a streak image at the continuous rear end (or front end). An example is described below. Note that a processing unit after streak image detection, which is a different part from the above-described embodiment, will be described.

Specifically, when dust analysis is performed by the image analysis unit 88 and a streak is detected at the leading end, notification processing is performed to the user by reflecting the result of the dust analysis at the subsequent trailing end. Similarly, when streak detection is performed at the rear end, notification processing is performed to the user by reflecting the result of dust analysis at the subsequent front end.

For example, when a streak is detected at the front end and a streak is not detected at the subsequent rear end, it can be notified that there is a possibility that there is a streak in the read image. In this case, since the document has already been read, the read image may be displayed on an external control device (for example, a personal computer) connected to the operation unit 83 or the communication unit 84 so that the user can check the image. At this time, the displayed read image may be displayed so that the streak position can be easily recognized by, for example, adding a mark so that the streak position can be recognized. In addition, the user continues reading as post-processing, disables streak image detection at P pixels before and after the main scanning direction of the pixel where the streak image is detected, continues reading, and generates a streak image without cleaning the image reading unit 89 The image reading unit 89 is cleaned and the image reading unit 89 is cleaned to continue processing from the re-reading of the document in which the streak image is generated. The external unit connected to the operation unit 83 or the communication unit 84 can be selected. You may notify via a control apparatus (for example, personal computer). In the case of continuing the reading by disabling the streak image detection at the P pixels before and after the main scanning direction of the pixel in which the streak image is detected, the pixels at which the streak image is detected at the P pixels before and after the main scanning direction until the batch is completed. The streak detection may not be performed, and cleaning may be prompted after the batch is completed. The number P of pixels for determining the range in which the detection of the streak image is invalid can be set to an arbitrary value at an arbitrary timing. For example, an external control device connected to the operation unit 82 or the communication unit 84 (for example, It may be set via a personal computer.
Further, for example, when a streak is detected at the front end and a streak is detected at the subsequent rear end, it is highly possible that there is a streak in the read image. The external connected to the operation unit 83 or the communication unit 84 The user can be notified via the control device (for example, a personal computer). Also in this case, since the document has already been read, the read image may be displayed on an external control device (for example, a personal computer) connected to the operation unit 83 or the communication unit 84 so that the user can check the image. At this time, the read image displayed may be displayed so that the streak position can be easily recognized by a method such as marking the streak position. Further, as described above, the user may be notified so that post-processing can be selected.
For example, if streak detection is performed at the rear end and no streak detection is performed at the leading end, a streak image may have occurred in the middle of the document immediately before the current document, and the streak has already occurred. It is thought that this factor has been eliminated. That is, no cleaning is necessary. In this case, the read image of the previous document may be displayed on an external control device (for example, a personal computer) connected to the operation unit 83 or the communication unit 84 so that the user can check the image. At this time, the displayed image may be displayed so that the streak position can be easily recognized by adding a mark so that the streak position can be recognized. Further, the user continues reading as post-processing, disables streak image detection at the P pixels before and after the data pixels of the detected streak image, continues reading, and re-reads the previous document in which the streak image occurred. You may notify so that processing, such as continuation from reading, can be selected.
Further, for example, when a streak is detected at the rear end and a streak is detected at the leading end, a streak is generated across the document, so that it can be seen that dust is reliably attached to the image reading unit 89. Therefore, the user may be strongly advised to clean the image reading unit 89.

As described above, when a streak image is detected at the front end (or rear end), the user is notified after confirming the presence or absence of a streak image at the continuous rear end (or front end). By doing so, it is possible to notify the optimal post-processing method according to the situation in which the streak image is detected, and it is possible to reduce the burden of the user's processing determination. Of course, the processing load is reduced rather than detecting the streak image in the entire read image, and the false detection rate of streaks can be reduced.

In the above description, it is assumed that dust or the like that generates a streak image does not move in the main scanning direction of reading. However, the present invention also applies when dust or the like moves in the main scanning direction of reading. Applicable. For example, when there is a pixel equal to or smaller than the dust determination threshold Lg in the Pw pixels before and after the m-th pixel at the time of image analysis, it is assumed that dust detection is performed on the m-th pixel, and finally L in the sub-scanning direction. Enable streaks to be detected when parsing lines.
As described above, streaks can be detected even when dust or the like moves in the main scanning direction.

As mentioned above, although this invention was demonstrated in detail based on one Embodiment, this invention is not limited to one Embodiment mentioned above.
For example, in the above-described embodiment, an example has been described in which the occurrence of a streak image is detected without performing a determination as to whether or not the streak is applied to the document portion in the read image when the streak is detected. However, the present invention is not limited to this, and when a streak is detected at the leading edge, the document is continuously read and from the obtained image, or when a streak is detected at the trailing edge, from the read image, the original portion and the background portion are detected. After the separation, the pixel position in the main scanning direction of the detected streak image is determined, and if the pixel where the streak image is generated does not reach the separated document part, the user may not be notified. An example is described below. A processing unit that determines whether or not the streak position is on the document portion, which is a different part from the above-described embodiment, will be described.

Specifically, when a streak is detected at the leading edge of the image, the document is continuously read in order to determine whether or not the detected streak position is on the document portion. After reading the document, the image processing unit 86 separates the document portion and the background portion, and extracts only the document portion from the read image. At this time, if the pixel that has read the original portion in the main scanning direction is separated into the pixel that has not read the original portion, and the pixel in which the streak image is generated is the pixel that has read the original portion, Notify that there is a streak image. On the contrary, when the pixel where the streak image has occurred is a pixel that has not read the original portion, the reading may be continued without notifying the user, and the user may be notified when the final original of the batch is read.

  As described above, when the detected streak image does not affect the image of the original document separated from the read image, by preventing the user from notifying that the streak image has occurred during the batch, the effect of the streak on the read image is reduced. In such a case, it is possible to notify the user unnecessarily and not to reduce the reading efficiency. Of course, the processing load is reduced as compared with the case where the streak image is detected in the entire read image.

As mentioned above, although this invention was demonstrated in detail based on one Embodiment, this invention is not limited to one Embodiment mentioned above.
The present invention is not limited to performing streak detection for each document. For example, after performing streak image detection processing on the first document in a batch, streak detection is performed at certain document intervals, and for other documents. The streak detection may not be performed. It should be noted that the document interval at which the streak detection is performed can be set to an arbitrary value that satisfies the above-described restrictions at an arbitrary timing, and may be set via the operation unit 82, for example.
In this way, it is not necessary to perform streak detection on all originals, leading to a reduction in processing load. Of course, the processing load is reduced as compared with the case where the streak image is detected in the entire read image.

As mentioned above, although this invention was demonstrated in detail based on one Embodiment, it is not limited to one Embodiment mentioned above.
For example, an example has been described in which the background plate described above is switched between reading the leading edge portion and reading the trailing edge portion, and the background plate is switched twice per document to detect streaks. The background plate may be switched between the originals and the background plate may be switched once per original, and an example thereof will be described below. A background plate switching processing unit, which is different from the above-described embodiment, will be described.

Specifically, the first document in the batch is read with the white background plate 70c. At this time, since the background is white, black dust can be detected. In addition, the background plate 70a is switched from the white background plate 70c to the black background plate 70d after the reading of the original is completed and before the reading of the next original is started. The next original is read with a black background 70d. At this time, since the background is black, white dust can be detected. Thereafter, the white background plate 70c and the black background plate 70d are switched between documents. Note that the background plate of the document at the beginning of the batch need not be fixed to any background plate, and reading may be started with the background plate when the last document of the previous batch is read. The background plate switching timing does not necessarily have to be between documents. For example, it may be at the time of reading the leading edge, reading the trailing edge, or reading the document.

  By reducing the background plate switching timing as described above, streaks due to dust can be reliably detected without being affected by the color of the dust, and the background plate is switched every time at the front and rear ends. Compared to the case, the number of times of switching can be reduced, so the processing load can be reduced, the time required for switching can be shortened, and the reading efficiency can be improved.

In addition, this invention is not limited to the aspect mentioned above, The following aspects are included.
The present invention relates to a conveying unit that conveys a document along a conveyance path, an image reading unit that reads an image of the conveyed document, and a document obtained by reading the leading end side or the trailing end side in the document conveying direction. The image processing apparatus may include image analysis means for analyzing whether or not the background image includes a streak image along the conveyance direction.
According to the aspect of the present invention, since it is analyzed whether or not a streak image is included in the background image of the document, the presence or absence of the streak image can be analyzed efficiently.

Further, the present invention further includes document detection means for detecting the arrival of the document on the upstream side in the transport direction from the image reading means, and before the leading edge of the document reaches the image reading position of the image reading means, The image reading unit starts image reading based on the detection result of the document detection unit, and the image analysis unit adds the streak image to the background image obtained by reading before the leading edge of the document reaches the image reading position. May be analyzed.
According to this aspect of the present invention, the streak image can be analyzed using the background image of the document read before the document reaches the image reading position.

Further, in the present invention, the apparatus further includes a document detection unit that detects the passage of the document on the upstream side in the transport direction with respect to the image reading unit, and after the trailing end of the document passes through the image reading position of the image reading unit, Based on the detection result of the original detection means, the image reading means continues to read the image, and the image analysis means obtains a background obtained by continuously reading even after the rear end of the original has passed the image reading position. It may be characterized by analyzing whether the streak image is included in the image.
According to this aspect of the present invention, the streak image can be analyzed using the background image of the document that is continuously read after the document has passed the image reading position.

The present invention includes a conveying unit that conveys a document along a conveying path, an image reading unit that reads an image of the conveyed document, and an image analysis unit that analyzes the read image. The read image may be analyzed to detect a streak image along the transport direction at the front end portion or the rear end portion in the transport direction.
According to this aspect of the present invention, the streak image can be analyzed using the background image other than the document area in the read image.

In the present invention, the transport path is provided with a document passage detection means for detecting the leading edge of the document on the upstream side in the transport direction with respect to the image reading means, and the image reading means is a part of the document passage detection means. Based on the detection result, a pre-reading process for starting the reading process before the document reaches the image reading position is performed, and the image analyzing means obtains a pre-read image obtained by the pre-reading process in the leading end portion of the read image. It may be characterized in that it is determined whether or not the streak image is included.
According to this aspect of the present invention, a streak image can be analyzed using a prefetched image.

In the present invention, the conveyance path is provided with a document passage detection unit that detects a trailing edge of the document on the upstream side in the conveyance direction with respect to the image reading unit, and the image reading unit includes the document passage detection unit. Based on the detection result, post-reading processing is performed to continue the reading process even after the rear end of the document has passed the image reading position, and the image analysis means includes the post-reading portion of the rear end portion of the read image. It may be characterized by determining whether or not the streak image is included in the post-read image obtained by the processing.
According to this aspect of the present invention, the streak image can be analyzed using the post-read image.

Further, in the present invention, the image reading unit has a background color changing unit that is on an opposite surface across the conveyance path and can change a background color as a background of the read image. It may be characterized by analyzing whether or not the streak image is included in the background image read by changing the color.
According to this aspect of the present invention, it is possible to analyze a streak image regardless of the color of dust.

The present invention may have a function of notifying the user of the occurrence of an abnormality based on the analysis result of the image analysis means.
According to such an aspect of the present invention, by notifying the user of the abnormality, the user can quickly remove dust attached to the image reading unit.

The present invention can be widely applied to an image reading apparatus including the above-described image processing apparatus.
According to this aspect of the present invention, when an image is read in an office machine such as a scanner or a copying machine, a streak image can be quickly identified without reading the image up to the document area, so that a streak image is not generated. Response can be implemented immediately.

A image reading device S transport medium 1 mounting table 2 discharge tray 2a first discharge tray 2b second discharge tray 3, 4 drive unit 5 transmission unit 10 first transport unit 11 feed roller 12 separation roller 12a torque limiter 20 second transport unit 21 driving roller 22 driven roller 30 third conveying unit 31 driving roller 32 driven roller 40 double feed detection sensor 50, 60 medium detection sensor 51 light emitting unit 51 light receiving unit 70 image reading unit 70a background plate 70b background switching motor 70c white background plate 70d Black background plate 71 Conveyance path 80 Control unit 81 CPU
82 Storage unit 83 Operation unit 84 Communication unit 85 Actuator 86 Image processing unit 87 Sensor 88 Image analysis unit 89 Image reading unit

Claims (9)

Conveying means for conveying the original along the conveying path;
Image reading means for reading an image of a conveyed document;
Image analysis means for analyzing whether or not a streak image along the conveyance direction is included in the background image of the document obtained by reading the front end side or the rear end side in the document conveyance direction;
An image processing apparatus comprising: A document detection unit that detects arrival of the document upstream of the image reading unit in the transport direction;
Before the leading edge of the document reaches the image reading position of the image reading unit, the image reading unit starts image reading based on the detection result of the document detection unit,
2. The image analysis unit according to claim 1, wherein the image analysis unit analyzes whether or not the streak image is included in a background image obtained by reading before the leading edge of the document reaches the image reading position. Image processing apparatus. A document detection unit that detects the passage of the document upstream of the image reading unit in the transport direction;
Even after the trailing edge of the original passes through the image reading position of the image reading means, the image reading means continues image reading based on the detection result of the original detection means,
The image analysis means analyzes whether or not the streak image is included in a background image obtained by continuously reading the document after the trailing edge of the document has passed the image reading position. Item 8. The image processing apparatus according to Item 1. Conveying means for conveying the original along the conveying path;
Image reading means for reading an image of a conveyed document;
Image analysis means for analyzing the read image read,
The image analysis unit is an image processing apparatus that analyzes the read image and detects a streak image along a conveyance direction at a front end portion or a rear end portion in a conveyance direction. The conveyance path is provided with document passage detection means for detecting the leading edge of the document on the upstream side in the conveyance direction with respect to the image reading means,
The image reading unit performs a pre-reading process for starting a reading process before the document reaches the image reading position based on a detection result of the document passage detection unit,
5. The image processing according to claim 4, wherein the image analysis unit determines whether or not the streak image is included in a pre-read image obtained by the pre-read process in a front end portion of the read image. apparatus. The conveyance path is provided with document passage detection means for detecting the trailing edge of the document on the upstream side in the conveyance direction with respect to the image reading means,
The image reading unit performs a post-reading process that continues the reading process even after the trailing edge of the document has passed the image reading position based on the detection result of the document passage detection unit,
The image analysis means determines whether or not the streak image is included in a post-read image obtained by the post-read process in a rear end portion of the read image. Image processing apparatus. A background color changing unit that is on an opposite surface across the image reading unit and a conveyance path, and that can change a background color as a background of the read image;
7. The image processing according to claim 5, wherein the image analysis unit analyzes whether or not a streak image is included in a background image read by changing a background color by the background color changing unit. apparatus.   The image processing apparatus according to claim 1, further comprising a function of notifying a user of the occurrence of an abnormality based on an analysis result of the image analysis unit.   An image reading apparatus comprising the image processing apparatus according to claim 1.

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