JP2005109976A - Image scanner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect contaminants or the like on contact glass easily, speedily and over a large area by one operation. <P>SOLUTION: The image scanner is provided with a reading means without document which reads an image of an upper constant width on the contact glass by moving the reading position by a predetermined width in the direction of vertical scanning with no document in the reading position on the contact glass and an information output means which outputs image data read out by the reading means without document or predetermined information according to the image data. In this way, positions of contaminants on the contact glass or the degree of contamination can be got in a manifestly apparent manner. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image reading apparatus that irradiates a document moving on a contact glass in a sub-scanning direction with light from a light source, receives a reflected light from the document, and reads a document image. The present invention relates to an image reading apparatus capable of comprehensively solving problems such as dirt and dust.

2. Description of the Related Art Conventionally, in a digital image reading apparatus equipped with an automatic document reading device (ADF), light is irradiated onto a document that is sequentially sent out by the ADF and moves on the contact glass along the sub-scanning direction. A system is adopted in which a document image is read by receiving the reflected light. In this reading method, when there is dirt or dust having a size larger than a predetermined size on the contact glass corresponding to the reading position for reading the original image, the dirt or the like is continuously obtained as image data regardless of the original image. Will be read. As described above, when a document is read in a state where dirt is adhered on the contact glass corresponding to the reading position, the dirt is read as a so-called black streak image and appears in the read image, and the quality of the read image is deteriorated. Become.
On the other hand, in Patent Document 1, a predetermined reference color image is read before reading a document image, and the presence or absence of dirt on the contact glass is determined based on the reading result. There has been proposed an image reading apparatus having a function of notifying an operator of the effect and the adhesion position of dirt. When the image processing apparatus determines that there is dirt, the image processing apparatus moves the light receiving device that receives the reflected light from the document by a predetermined amount within a predetermined movable range, and again determines whether there is dirt at the moved position. It also has a function of executing processing. This function not only prompts the operator to remove dirt, but also repeatedly performs the process of judging whether or not dirt is present until it is judged that there is no dirt. An image can be read.
JP-A-10-56542

However, the image reading apparatus described in Patent Document 1 reads the reference color image corresponding to one line in the main scanning direction, determines whether there is any dirt in the image data for one line, and outputs it. Therefore, the operator can confirm only one line of dirt on the contact glass. When cleaning and removing the dirt on the contact glass, it is desirable that the position of dirt to be cleaned or the degree of dirt to be cleaned is clearly understood, but the image reading apparatus described in Patent Document 1 can do so. There wasn't.
Further, the stain on the contact glass appears as a black streak image in the read image even if it cannot be visually recognized by human eyes. However, in the image reading apparatus described in Patent Document 1, the contact glass is cleaned. It was not possible to confirm the degree of dirt removal.
Further, when there are a large number of stains on the contact glass, the image reading apparatus described in Patent Document 1 executes the process of determining the presence or absence of stains by moving the light receiving device many times. There also occurs a situation where a long time is required until the light receiving device moves to a clean position. Furthermore, depending on the degree of contamination, it may not be possible to determine a position without contamination, and as a result, the time spent on the determination processing is wasted.
Accordingly, the present invention has been made in view of the above circumstances, and an object of the present invention is to provide an image reading apparatus that can easily and quickly detect dirt on the contact glass in a wide range at a high speed. Is to provide.

In order to achieve the above object, the present invention irradiates light from a light source onto a document that moves the reading position on the contact glass in the sub-scanning direction, and receives reflected light from the document through the contact glass. In the image reading apparatus that reads the image of the original by receiving light by the means, the reading position is moved by a predetermined width in the sub-scanning direction in a state where no original is provided at the reading position. A non-document reading unit that reads an image in the predetermined width; and an information output unit that outputs image data read by the non-document reading unit or predetermined information based on the image data. Configured as an image reading apparatus.
As a result, the operator can confirm not only the image data for one line but also the image data on the contact glass corresponding to a wide range in which the light receiving means such as the carriage and the CCD can move. This makes it possible to clearly grasp the position of dirt or the degree of dirt, so that the dirt to be cleaned can be easily and quickly recognized. It is also possible to confirm dirt that cannot be visually recognized by human eyes. As a result, since the dirt is reliably removed, the occurrence of black streak images in the read image can be reduced, and a high-quality read image can be obtained.

Further, the non-document reading means compares the open state image data read with the document cover covering the contact glass open and the closed state image data read with the document cover closed. And a common image extraction means for extracting a common portion where the positional relationships of the open state image data and the closed state image data substantially coincide with each other based on the collation result by the collation means, and the information output means The image data of the common part extracted by the common image extraction means or predetermined information based on the image data of the common part may be output. As a result, an image reflecting only the dirt on the contact glass is output, so that the operator can reliably grasp only the dirt on the contact glass.
In this case, the common image extraction means extracts a common portion having a substantially coincident positional relationship among the boundary portions where the image level changes in each of the open state image data and the closed state image data. Also good. As a result, not only on the contact glass but also on the contact glass side surface of the document cover, only the dirt adhered on the contact glass is extracted and displayed. It becomes possible.

  Further, if the information output means outputs the image data read by the non-document reading means after being emphasized, it is emphasized to such an extent that dirt that is difficult to visually recognize can be visually recognized. Makes it possible to more clearly grasp the dirt on the contact glass and the like. In this case, it is desirable that the enhancement process is a binarization process or an outline enhancement process.

  Preferably, the predetermined information based on the image data of the common part output by the information output means is a caution notice or warning for notifying the presence of dirt on the contact glass. For example, if the contact glass is displayed as a caution notice on the display panel or the like, the operator can recognize that the contact glass is dirty, and an alarm or buzzer sounds as a warning. It can be easily recognized by making a sound.

As described above, according to the present invention, an image in the predetermined width on the contact glass is obtained by moving the reading position by a predetermined width in the sub-scanning direction in a state where no document is provided at the reading position on the contact glass. And an information output means for outputting predetermined data based on the image data read by the no-document reading means. By confirming not only the image data but also the image data on the contact glass corresponding to a wide range in which the light receiving means such as the carriage and CCD can move, the position or degree of contamination on the contact glass can be seen at a glance. It becomes possible to grasp and dirt which should be cleaned can be recognized easily and quickly. It is also possible to confirm dirt that cannot be visually recognized by human eyes. As a result, since the dirt is reliably removed, the occurrence of black streak images in the read image can be reduced, and a high-quality read image can be obtained.
The non-document reading means reads an image with the document cover covering the contact glass open and / or closed. For example, when reading an opaque document, the non-document reading means adheres to the contact glass. When an image that reflects only the stained dirt is output and a transparent document is read, an image that reflects not only the contact glass but also the dirt adhered to the contact glass side surface of the document cover is output. Therefore, it is possible to output image data corresponding to the type of document to be printed, and to accurately notify the operator of the position of dirt.
Further, since the information output means emphasizes and outputs the image data read by the non-document reading means, the operator can more clearly grasp the dirt and dirt on the contact glass. Is possible.
Further, since the reading position moving means for moving the reading position by moving the light receiving means on the basis of the image data read by the non-document reading means is further provided, the contact with the least dirt or no dirt is obtained. The original image can be read at the reading position on the glass, and it is possible to effectively prevent the occurrence of the black stripe image and obtain a high-quality read image.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings so that the present invention can be understood. The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.
FIG. 1 is a schematic diagram showing a schematic configuration of a scanner device X which is an example of an image reading device according to an embodiment of the present invention. FIG. 2 is a diagram of a control device for the scanner device X according to the embodiment of the present invention. FIG. 3 is a flowchart for explaining the procedure of dust detection processing by the control unit of the scanner device X, and FIG. 4 is a flowchart for explaining the procedure of dust avoidance processing by the control unit of the scanner device X.

<< First Embodiment >>
Here, the schematic configuration of the scanner device X according to the first embodiment of the present invention will be described with reference to the schematic cross-sectional view of FIG. FIG. 1A is a schematic view seen from the side of the scanner device X, and FIG. 1B is a front view of the scanner device X seen from the arrow A shown in FIG. The scanner apparatus X is merely an example of an image reading apparatus according to an embodiment of the present invention. As another example, a copying machine, a printer apparatus, a facsimile apparatus, or a digital apparatus having the functions of these apparatuses can be used. This applies to multifunction devices.
As shown in FIG. 1, the scanner device X is roughly composed of an apparatus main body 20 and an automatic document feeder 10 (hereinafter referred to as “ADF 10”) disposed above the apparatus main body 20. ing.
In the apparatus main body 20, an exposure device 21 (light source) that irradiates light to the document S moving in the sub-scanning direction at the reading position P on the contact glass 26, and reflected light from the document S is transmitted to the contact glass 26. A carriage 22 (an example of a light receiving means) including a mirror that receives light through the light guide, light guide mirrors 23a and 23b that guide reflected light received by the carriage 22 to the optical lens 24, and the light guide mirrors 23a and 23b. An optical lens 24 for condensing the reflected light guided through the optical lens 24, a CCD 25 for converting image information contained in the reflected light collected by the optical lens 24 into an electric signal, and an electric signal converted by the CCD 25. And a control device 30 that executes image processing of the recognized image data.
The carriage 22 is fixed so as to receive the reflected light from a preset reading position P during the reading operation of the document S. In this scanner apparatus X, the reading position P is the width T in the sub-scanning direction of the area Q surrounded by the two-dot chain line shown in FIG. 1B, that is, the area where the position of the reading position P can be set. The carriage 22 can be arbitrarily changed by moving the carriage 22 in the interior, and therefore, the carriage 22 has a structure capable of movement control in the sub-scanning direction.
A contact glass 26 is provided on the upper surface of the apparatus body 20, and an operation display panel 29 (an example of information output means) having an operation unit 27, a display unit 28, and the like is disposed on the front side surface.
The operation unit 27 is input means provided with various operation keys such as a keyboard and a cross key. When the operation key is operated on the operation unit 26, various functions such as “dust detection mode” and “dust avoidance mode” of the scanner device X are set, and a scanner reading instruction is made. The dust detection mode and the dust avoidance mode are specific functions provided in the scanner apparatus X, and will be described in detail later.
The display unit 28 includes a liquid crystal display or the like, and is an example of an information display unit that displays various types of information output from the control device 30 and information input from the operation unit 27.
The ADF 10 sequentially conveys the document S set on the document setting unit 11 one by one through a plurality of conveyance rollers (not shown). The transported document S is transported in the sub-scanning direction through the reading position P on the contact glass 26, and then transported to the document discharge unit 13. The ADF 10 also serves as a document cover that covers the contact glass 26, and the surface 14 of the ADF 10 that covers the contact glass 26 (hereinafter referred to as "document cover surface 14") is stabilized from the document. In order to obtain reflected light, the entire reading width in the main scanning direction is white.

Next, the schematic configuration of the control device 30 will be described with reference to the block diagram of FIG.
As shown in FIG. 2, the control device 30 controls the storage unit 50, an interface (I / F) 60 that enables data communication by connecting to an external device, a signal conversion unit 70, and the above-described units. And a control unit 40 having a no document reading function 41 (achieved by the no document reading means), an information output function 42 (achieved by the information output means), and a reading position moving function 43 (achieved by the reading position moving means). It is configured. The control device 30 is connected to the CCD 25, the operation unit 27, and the display unit 28 via the interface 60 so as to be able to communicate data. Each of the functions (the no-document reading function 41, the information output function 42, and the reading position moving function 43) is calculated by reading the program stored in the program storage unit 52 of the storage unit 50 by the control unit 40. The functions realized by processing will be described in detail later.
The
The storage unit 50 includes a data storage unit 51 and a program storage unit 52. The data storage unit 51 is a semiconductor memory such as a ROM or a RAM, and the data storage unit 51 temporarily stores image data read by the CCD 25. Further, it is used as a work area when image processing of stored image data is executed. The program storage unit 52 is a non-volatile semiconductor memory such as a ROM. The program storage unit 52 causes the control unit 30 to execute the non-document reading function 41, the information output function 42, and the reading position moving function 43. Is stored. The data storage unit 51 and the program storage unit 52 are not limited to a semiconductor memory, and may be any storage medium that can rewrite data, such as a hard disk. Further, a storage device externally connected via the interface 60 may be used.
The signal converter 70 is for improving the efficiency of storing image data or shortening the data transmission time. For example, the signal converter 70 decodes the electric signal converted by the CCD 25 and converts it into digital image data, or The image data is encoded and converted into an electrical signal.

Next, with reference to FIG. 1 and FIG. 2, a document image reading operation by the scanner device X will be briefly described.
When the operator presses a document reading start key (not shown) after the document S is set on the document setting unit 11, a conveyance roller (not shown) is driven, and the document S is sent one by one to the conveyance path. It is. When the leading edge of the document S reaches the contact glass 26 via the conveyance path, the document S is detected by a document detection sensor (not shown), and the document S is irradiated with light from the exposure device 21. The Thereafter, the document S is exposed by the exposure device 21 while moving on the contact glass 26 in the sub-scanning direction, and the reflected light from the document S at the reading position P is received by the carriage 22. The reflected light received by the carriage 22 reaches the CCD 25 via the light guide mirrors 23a and 23b and the optical lens 24, is converted into an electric signal, and is then transmitted to the control device 30, so that it is finally obtained. The original image is read.

Next, a procedure of dust detection processing executed by the control unit 40 of the scanner device X when the dust detection mode is set will be described with reference to the flowchart of FIG. In the figure, S10, S20,... Indicate processing procedure (step) numbers. The process starts from step S10.
When it is confirmed by the control unit 40 that a dust detection mode selection key (not shown) from the operation unit 27 has been pressed, and subsequently, a dust detection execution key (not shown) has been pressed (S10). , S20), the control unit 40 enables the dust detection mode, and executes a non-document reading process in step S30. That is, when the control unit 40 confirms that the dust detection execution key has been pressed by a key input signal or the like, the carriage 40 is in a state where the document S is not provided at the reading position P (FIG. 1). 22 is moved by the width T in the sub-scanning direction shown in FIG. 1B, and the region Q is exposed and scanned to read the image in the width T on the contact glass 26, that is, the image in the region Q. . Thereafter, the read image data is stored in the data storage unit 51 (FIG. 2). The no document reading process in step S30 is a process executed when the control unit 40 implements the no document reading function 41. As a result, image data reflecting the dirt existing in the width T on the contact glass 26 (dirt existing in the region Q) and the dirt existing on the surface of the ADF 10 in contact with the contact glass 26 is read. The non-document reading process is executed in response to the pressing operation of the dust detection mode selection key and the dust detection execution key. One dust detection execution key that also functions as the dust detection mode selection key and the dust detection execution key, etc. The non-document reading process may be executed in response to the pressing operation.
Subsequently, in step S40, the enhancement processing of the image data in the region Q read in step S30 and stored in the data storage unit 51 is executed. Specifically, the enhancement processing is executed by performing binarization processing or contour enhancement processing on the image data. The information output and displayed on the display unit 28 by the information output process to be described later may be the image data itself read by the non-document reading process. However, the information may be emphasized and output and displayed on the display unit 28. Accordingly, it is possible to confirm even the dirt on the contact glass 26 that is not visible to the eye.
Subsequently, in step S50, the control unit 40 executes information output processing. That is, the control unit 40 outputs the image data enhanced in step S40 from the data storage unit 51 to the display unit 28 for display. The emphasis process in step S40 and the information output process in step S50 are processes executed by the control unit 40 realizing the information output function 42.
In this way, the dust detection mode is executed by the control unit 40 executing the non-document reading process and the information output process. As a result, the image data of the region Q in which the reading position P can be set is displayed on the display unit 28, so that the operator refers to the displayed image data and the contact glass 26 corresponding to the region Q. It becomes possible to grasp at a glance the adhesion position or the degree of dirt on the top, and the dirt on the contact glass 26 to be cleaned can be recognized easily and quickly. As a result, it is possible to surely remove the dirt, prevent the occurrence of black streak images in the read image, and obtain a high-quality read image.

The non-document reading process described above is an image in the width T in the open state where the ADF 10 does not cover the contact glass 26 and / or in the closed state where the ADF 10 covers the contact glass 26. It also reads an image in the area Q.
Usually, most of the originals read by the image reading apparatus are opaque sheets such as plain paper. However, a transparent sheet such as OHP or a translucent sheet may be used as a document. When such an image of an opaque document is read by the scanner apparatus X, only the dirt adhering to the contact glass 26 appears as a black streak image, so that the ADF 10 is read in the open state by the above-described non-document reading process. It is sufficient to read and display the displayed image, that is, the image reflecting only the dirt adhered on the contact glass 26. An image read with the ADF 10 open is a black image. However, if dirt is adhered on the contact glass 26, only the dirt appears as a white image. It is possible to accurately grasp the dirt attached only on the top.
On the other hand, when the image of the transparent document is read, not only the stain on the contact glass 26 but also the stain adhering to the document cover surface 14 of the ADF 10 appears as a black streak image. It is necessary to read and output and display an image that is read in a closed state, that is, an image that reflects not only the dirt adhering to the contact glass 26 but also the dirt adhering to the document cover surface 14. An image read with the ADF 10 closed is a white image. However, when dirt is adhered on the contact glass 26 and the document cover surface 14, only the dirt appears as a black image. The operator can accurately grasp the dirt adhering to the contact glass 26 and the document cover surface 14.
Further, the image of the region Q is read when the ADF 10 is open and the ADF 10 is closed, and the open state image data read when the ADF 10 is open and the open state read when the ADF 10 is open. Both image data of the image data may be output and displayed on the display unit 28 or the like. In this case, the control unit 40 first reads the image of the region Q (open state image) while the ADF 10 is open, and then notifies the operator that the ADF 10 is closed. After receiving the closing signal of the illustrated cover switch, the image of the region Q (closed state image) is read while the ADF 10 is closed.
As described above, if the non-document reading process reads an image when the ADF 10 is open and / or closed, the area Q is read according to the type of the document S to be read by the scanner device X. The image data can be output to the display unit 28 by the information display process, and this makes it possible to accurately notify the operator of the position of the dirt depending on the type of the document S.

Next, with reference to a flowchart of FIG. 4, a description will be given of a procedure of dust avoidance processing executed by the control unit 40 of the scanner device X when the dust avoidance mode is set. In the figure, S110, S120,... Indicate processing procedure (step) numbers. The process starts from step S110.
When the control unit 40 confirms that a dust avoidance mode selection key (not shown) from the operation unit 27 has been pressed, and further, a dust avoidance execution key (not shown) has been pressed (S110, In step S120, the control unit 40 enables the dust avoidance mode, and in step S130, executes the non-document reading process described above with reference to the flowchart of FIG.
When the non-document reading process is completed in step S130, subsequently, in step S140, the carriage 22 is moved based on the image data of the area Q read in step S130, and the reading position P is set to the area Q. Is moved within the range of the width T. More specifically, the carriage 22 is moved in the main scanning direction of the image data in the area Q to a position where there is no image corresponding to the dirt adhering to the contact glass 26 or the document cover surface 14. The reading position moving process in step S140 is a process executed when the control unit 40 realizes the reading position moving function 43.
As described above, the non-document reading process and the reading position moving process are executed by the control unit 40, whereby the dust avoidance mode is executed. As a result, it is not necessary to repeatedly perform the process of determining the presence or absence of dirt for each line in the main operation direction by moving the light receiving device many times as in the prior art. Since the original image is read at a reading position with less dirt, it is possible to effectively prevent the occurrence of black stripe images and obtain a high-quality read image.

<< Second Embodiment >>
Next, a scanner device X according to a second embodiment of the invention will be described. Unlike the first embodiment described above, the control unit 40 of the scanner apparatus X further has a collation function (achieved by the collation means) and a common image extraction function (achieved by the common image extraction means).
In the scanner device X, in addition to the above-described non-document reading process, information output process, and reading position movement process, the control unit 40 executes a collation process and a common image extraction process. The collation process is a process executed when the control unit 40 implements a collation function, and the common image extraction process is a process achieved when the control unit 40 implements a common image extraction function. is there. Hereinafter, the collation processing and common image extraction processing executed by the control unit 40 when the dust detection mode is selected will be described.
The non-document reading process is executed by the control unit 40, and the image of the region Q (open state image) when the ADF 10 is open and the image of the region Q (closed state image) when the ADF 10 is closed are displayed. When both are read, a collation process for collating the open state image and the closed state image stored in the data storage unit 51 is executed.
When the collation process is executed, a common image extraction process for extracting a common portion in which the positional relationship between the open state image and the closed state image substantially coincides is executed based on the collation result by the collation process. The That is, in each of the open state image and the closed state image, a common portion having a substantially coincident positional relationship is extracted from each boundary portion where the image level changes. For example, among the peripheral pixels of pixels that have a difference in gradation in the open state image and the closed state image, the peripheral pixels (where the position in the entire open state image substantially matches the position in the entire top closed state image ( Common part) is extracted. In the open state image, a portion corresponding to dirt appears as a white image, and in the closed state image, a portion corresponding to dirt appears as a black image. Therefore, the common image extraction processing is performed in the open state image. A common portion in which the positional relationship between the white image data and the black image data in the closed state image substantially matches may be extracted.
When the common part is extracted by the common image extraction process, the information output process is executed by the control unit 40, whereby the image data of the common part extracted by the common image extraction process or the common part is extracted. The predetermined information based on the image data is output and displayed on the display unit 28.
As a result, not only on the contact glass 26 but also on the document cover surface 14 of the ADF 10, only the dirt adhering to the contact glass 26 is extracted and displayed. Thus, the operator can reliably grasp only the dirt on the contact glass. Further, a warning notice or warning for actively notifying the operator that dirt is attached on the contact glass 26 is displayed on the display unit 28, or a message to that effect is printed out. Good. Further, the degree of contamination on the contact glass 26 may be determined on the basis of a comparison result obtained by comparing the output image data with image data in a state free from dust and contamination, and a change in the data amount of the output image data. Good. As a result, the operator can be made aware of even a small amount of dust or dirt.

  In the description of the first embodiment and the second embodiment described above, an embodiment in which the operator himself sets the dust detection mode or the dust avoidance mode and causes the control unit 40 to execute dust detection processing and dust avoidance processing. However, the dust detection mode or the dust avoidance mode may be automatically set and executed. For example, when the control unit 40 determines whether or not the read document image includes a black streak image, and determines that the black streak image is included, the dust detection mode and the dust avoidance mode are automatically performed. Alternatively, the dust detection process and the dust avoidance process may be executed.

  In the description of the first and second embodiments described above, the carriage 22 is illustrated as the light receiving means, and the reflected light from the document is received by the carriage 22, and then the light guide mirrors 23a, 23b, etc. However, the present invention is not limited to such a configuration. For example, instead of the carriage 22, the CCD 25 can directly receive the reflected light from the document. There may be. At this time, the CCD 25 may be replaced with an image sensor such as CIS (Contact Image Sensor) or CMOS (Complementary Metal-Oxide Semiconductor).

  Further, the scanner device according to the second embodiment described above extracts a common part where the positional relationship between the open state image and the closed state image substantially coincides, and the image data of the common part or the common part is extracted. By outputting and displaying predetermined information based on the image data, the operator is allowed to confirm only the dirt adhering to the contact glass 26, but the positional relationship between the open state image and the closed state image is different. By extracting a non-matching portion that does not substantially match and outputting and displaying predetermined information based on the image data of the non-matching portion or the image data of the common portion, the dirt attached to only the document cover surface 14 of the ADF 10 is displayed to the operator. It may be to confirm only. This is effective when a transparent document is read.

1 is a schematic diagram showing a schematic configuration of a scanner device X which is an example of an image reading device according to an embodiment of the present invention. 1 is a block diagram showing a schematic configuration of a control device of a scanner device X according to an embodiment of the present invention. 6 is a flowchart for explaining a procedure of dust detection processing by a control unit of the scanner device X. 9 is a flowchart for explaining a procedure of dust avoidance processing by the control unit of the scanner device X.

Explanation of symbols

X ... Scanner device P ... Document reading position S ... Document 10 ... Automatic document feeder (ADF)
DESCRIPTION OF SYMBOLS 11 ... Document setting part 13 ... Document discharge part 14 ... Document cover surface 20 ... Apparatus main body 21 ... Exposure apparatus (light source)
22 Carriage (light receiving means)
23 ... Light guide mirror 24 ... Optical lens 25 ... CCD
26 ... contact glass 27 ... operation unit 28 ... display unit (information display means)
29 ... Operation display panel 30 ... Control device 40 ... Control unit 50 ... Storage unit 60 ... Interface (I / F)
70: Signal converter

Claims (5)

An image of the original is obtained by irradiating light from a light source onto an original moving in the sub-scanning direction on the contact glass and receiving reflected light from the original with a predetermined light receiving means through the contact glass. In an image reading device that reads
A non-document reading means for reading an image in the predetermined width on the contact glass by moving the reading position by a predetermined width in the sub-scanning direction in a state where no document is provided at the reading position;
Information output means for outputting image data read by the non-document reading means or predetermined information based on the image data;
An image reading apparatus comprising: Collation means for collating the open state image data read with the original cover covering the contact glass open with the non-original reading means and the closed state image data read with the original cover closed; ,
A common image extracting means for extracting a common portion where the positional relationships of the open state image data and the closed state image data substantially coincide with each other based on the collation result by the collation means;
2. The image reading apparatus according to claim 1, wherein the information output means outputs predetermined information based on the image data of the common part extracted by the common image extraction means or the image data of the common part.   3. The common image extracting unit extracts a common portion having a substantially coincident positional relationship among boundary portions whose image levels change in each of the open state image data and the closed state image data. The image reading apparatus described.   The image reading apparatus according to claim 1, wherein the information output unit is configured to emphasize and output the image data read by the non-document reading unit.   The image according to any one of claims 2 to 4, wherein the predetermined information based on the image data of the common part output by the information output means is a caution notice or a warning notifying the presence of dirt on the contact glass. Reader.

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