JP6165092B2 - Image reading device - Google Patents

Description

  The present invention relates to an image reading apparatus.

  In general, a digital multi-function peripheral is an image reading unit that reads an image of an object to be read such as a document placed on contact glass, an image processing unit that performs predetermined image processing on image data obtained by the image reading unit, and an image A printing unit for printing an image based on the image data subjected to the image processing by the processing unit on a recording sheet or the like is provided.

  Since the object to be read of the image reading device is usually a sheet-like document, the document cover of the image reading device has a flat plate shape so that the sheet-like document is brought into close contact with the contact glass.

  For this reason, when the object to be read is a three-dimensional object having a large thickness, the object to be read is not sufficiently covered by the document cover, and fogging occurs in the background around the image of the object to be read in the read image.

  In some image reading apparatuses, the document cover has an accommodating space for accommodating a three-dimensional object to be read placed on the contact glass, so that even when reading an image of the three-dimensional object to be read, the background The fog is prevented from being generated (see, for example, Patent Document 1). However, the document cover having the storage space as described above has a complicated structure, so that the production cost increases, and the size of the object to be read may be limited to the size of the storage space.

  Therefore, the present inventor forms a planar mark at a predetermined position on the cover plane of the original cover, detects the mark image of the mark in the image read by the image reading unit, and determines the density and / or the mark image. A technique has been proposed in which the position is specified and image quality degradation such as fog is reduced by image processing based on the density and / or position of the mark image (see, for example, Patent Document 2).

JP 2001-343802 A JP 2013-115616 A

  In the above-described technology, when the density or color difference between the cover plane of the document cover and the mark formed on the document cover is large, the mark is not detected when reading a document image of a sheet-like document that easily transmits light. There is a possibility that the image quality of the document image that is shown through and read is deteriorated.

  The present invention has been made in view of the above problems, and is low in cost and reduces image quality deterioration when the object to be read is a three-dimensional object, and also reduces image quality when the object to be read is a sheet document. An object of the present invention is to obtain an image reading apparatus capable of reducing the above.

An image reading apparatus according to the present invention includes a transparent mounting table on which a reading object is mounted, a document cover having a three-dimensional mark at a predetermined position on a cover plane covering the reading object mounted on the mounting table, An image reading unit that reads an image of an object to be read and a cover plane placed on the mounting table, and a mark image of the three-dimensional mark is detected in the image read by the image reading unit, and the density and / or position of the mark image And a mark specifying unit for specifying. The three-dimensional mark has a surface parallel to the cover plane, and the color of all the surfaces of the three-dimensional mark is the same as the color of the cover plane.

  Thus, by providing a mark on the document cover, it is possible to reduce deterioration in image quality such as fog by image processing from the density and / or position of the mark image. Therefore, it is possible to reduce image quality degradation such as fogging at a low cost when the object to be read is a three-dimensional object.

  In addition, by using the three-dimensional mark, when the object to be read is a three-dimensional object, a density difference between the three-dimensional mark and the surrounding area can be obtained in the image read by the image reading unit. It is not necessary to use a density or color different from that of the surrounding area, and even if the object to be read is a sheet-like transparent original, it is possible to reduce image quality deterioration due to show-through.

  According to the present invention, in the image reading apparatus, it is possible to reduce image quality deterioration when the object to be read is a three-dimensional object at low cost, and reduce image quality deterioration when the object to be read is a sheet-like document. Can do.

FIG. 1 is a side view showing an internal configuration of an image reading apparatus according to an embodiment of the present invention. FIG. 2 is a perspective view of the image reading apparatus according to the embodiment of the present invention. FIG. 3 is a plan view showing the document cover in FIGS. 1 and 2. FIG. 4 is a block diagram showing an electrical configuration of the image reading apparatus shown in FIG. FIG. 5 is a flowchart for explaining image reading processing by the image reading apparatus shown in FIGS. 1, 2, and 3. FIG. 6 is a cross-sectional view for explaining the distribution of the distance from the surface of the three-dimensional mark when the object to be read has a three-dimensional shape in the image reading apparatus shown in FIGS. 1, 2, and 3. FIG. 7 is a flowchart for explaining a document cover misalignment detection process performed by the image reading apparatus shown in FIGS. 1, 2, and 3.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a side view showing an internal configuration of an image reading apparatus according to an embodiment of the present invention. The image reading apparatus shown in FIG. 1 is an apparatus such as a scanner, a copying machine, or a digital multifunction machine.

  In FIG. 1, a contact glass 1 is a transparent mounting table that is placed on the upper surface of the image reading apparatus main body and on which an object to be read such as a document is placed during image reading.

  The carriage 2 is installed so as to be movable in the sub-scanning direction by a drive source (not shown). The carriage 2 has a light source 11 and a mirror 12. The light source 11 is arranged along the main scanning direction, and emits light with, for example, a plurality of light emitting diodes arranged. The light emitted from the light source 11 is reflected by an object to be read such as a document placed on the contact glass 1 according to the position of the carriage 2. The mirror 12 reflects reflected light from an object to be read.

  The carriage 3 is installed so as to be movable in the sub-scanning direction together with the carriage 2 by a drive source (not shown). The carriage 3 has mirrors 13 and 14. The mirrors 13 and 14 reflect the light from the mirror 12 of the carriage 2 twice and emit it along the sub-scanning direction.

  The imaging lens 4 focuses the light from the mirror 14 on the image sensor 5.

  The image sensor 5 is a one-dimensional image sensor having light receiving elements with a predetermined number of pixels arranged in the main scanning direction, and outputs an electrical signal corresponding to the amount of light received for the pixels with the number of pixels for each line. For example, a CCD (Charge Coupled Device) is used as the image sensor 5.

  Image reading for reading the image of the object to be read placed on the contact glass 1 and the cover plane of the document cover 7 by the carriages 2 and 3, the imaging lens 4, the image sensor 5, the light source 11, the mirror 12, and the mirrors 13 and 14. Part 15 is configured. The image reading unit 15 reads an image in a predetermined rectangular area on the contact glass 1.

  FIG. 2 is a perspective view of the image reading apparatus according to the embodiment of the present invention. FIG. 3 is a plan view showing the document cover 7 in FIGS. 1 and 2.

  As shown in FIGS. 1, 2, and 3, the document cover 7 has a plurality of three-dimensional marks 22 at predetermined positions on a white cover plane 21 that covers an object to be read placed on the contact glass 1. The member is a substantially flat member that is rotatably installed around the rotation end 7a as an axis so that the contact glass 1 can be brought into surface contact when the object to be read is not placed. The document cover 7 allows an object to be read such as a sheet document to be in close contact with the contact glass 1 and prevents ambient light from entering the apparatus from the contact glass 1 during image reading.

  The cover plane 21 is a surface of an elastic member 21a in which a white resin sheet is bonded to an elastic base sheet made of an elastic material such as sponge. The three-dimensional mark 22 is formed on the cover plane 21 and has a predetermined three-dimensional shape (for example, a polygonal column such as a cylinder or a quadrangular column). The number and arrangement pattern of the three-dimensional marks 22 are not limited to the cases shown in FIGS.

  Specifically, in this embodiment, the three-dimensional mark 22 is formed on the elastic member 21a and has a concave shape.

  The three-dimensional mark 22 may be formed of an elastic material and have a convex shape. By using the elastic material, the three-dimensional mark 22 is elastically deformed when the document cover 7 covers the sheet-like document, and as a result, the cover plane 21 can be sufficiently adhered to the sheet-like document. In this case, for example, the three-dimensional mark 22 is formed in a convex shape so as to be continuous from the elastic member 21a.

  Of the surface of the three-dimensional mark 22, the color of the surface parallel to the cover plane 21 (in the case of a concave shape, the bottom surface of the three-dimensional mark 22 and in the case of a convex shape, the color of the three-dimensional mark 22) The color around the shape mark 22 is the same. For example, the same white resin sheet as that of the elastic member 21 a is used on the surface of the three-dimensional mark 22 that is parallel to the cover plane 21. Of the surface of the three-dimensional mark 22, the surface perpendicular to the cover plane 21 may be the same as or different from the color around the three-dimensional mark 22 on the cover plane 21. Further, the entire surface of the three-dimensional mark 22 may be the same color as the cover plane 21.

  FIG. 4 is a block diagram showing an electrical configuration of the image reading apparatus shown in FIG.

  In FIG. 4, a document detection sensor 31 is a sensor that is disposed at a plurality of positions below the contact glass 1 and optically detects a document or the like placed on the contact glass 1.

  The user interface 32 includes an input device such as a button switch or a touch panel that detects a user operation, and a display device such as a liquid crystal display that displays various types of information to the user.

  The printing unit 33 is an internal device that prints an image based on image data on a recording sheet or the like by an electrophotographic method or the like.

  The image processing device 34 is a device that performs image processing on the image read by the image reading unit 15. The image processing device 34 is realized by, for example, an ASIC (Application Specific Integrated Circuit) or a computer that operates according to a control program.

  The storage device 35 is a nonvolatile storage device such as a hard disk or a nonvolatile memory, and stores various data and control programs. A default color correction table 51 is stored in the storage device 35 in advance.

  The default color correction table 51 is a color correction table applied to an image read by the image reading unit 15 when the object to be read is a sheet document.

  The image processing apparatus 34 includes a control unit 41, a read object type identification unit 42, a mark identification unit 43, a color correction unit 44, an output image generation unit 45, and a cover shift detection unit 46.

  The control unit 41 controls the image reading unit 15 and the user interface 32, and acquires quantized bitmap image data from the output of the image reading unit 15.

  The read object type identification unit 42 reads on the contact glass 1 based on the output of the document detection sensor 31 and / or the position of the image of the three-dimensional mark 22 in the image read by the image reading unit 15. The presence / absence of an object, the type of object to be read (either a three-dimensional object or a sheet-like document), the size of the object to be read, and the like are specified.

  In the case where the presence / absence of the object to be read, the type of the object to be read, the size of the object to be read is specified based on the output of the original detection sensor 31, the type of the object to be read is determined when the original cover 7 is closed. The identifying unit 42 may identify them based on the output of the document detection sensor 31.

  The mark specifying unit 43 detects the mark image of the mark in the image read by the image reading unit 15 and specifies the density and / or position of the mark image.

  Furthermore, in this embodiment, the mark specifying unit 43 specifies the stationary angle (open angle when the fully closed state is 0 degree) of the document cover 7 based on the density and / or position of the mark image. Specifically, the mark specifying unit 43 uses the mark image in the image read by the image reading unit 15 based on the shape of the three-dimensional mark 22, the density characteristic of the mark image, the density characteristic of the image on the cover plane 21, and the like. And the stationary angle of the document cover 7 is specified from the density and / or position of the mark image.

  That is, the density characteristic of the mark image with respect to the distance to the three-dimensional mark 22 is specified in advance by experiments or the like, and from the density characteristic, the mark specifying unit 43 determines the distance of each three-dimensional mark 22 from the contact glass 1. Based on the distance and the position of the three-dimensional mark 22 on the cover plane 21, the stationary angle of the document cover 7 is specified.

  As shown in FIG. 2 and FIG. 3, when a plurality of three-dimensional marks 22 are provided and a plurality of mark images are found in the image read by the image reading unit 15, the mark specifying unit 43 displays each mark image. The stationary angle of the document cover 7 is defined as the stationary angle of the document cover 7.

  The color correction unit 44 performs color correction (correction of each color of CMYK) on the image read by the image reading unit 15. The color correction unit 44 corrects the image read by the image reading unit 15 according to the density and / or position of the mark image. In this embodiment, the color correction unit 44 corrects the image read by the image reading unit 15 according to the stationary angle of the document cover 7 described above. Thereby, the color correction unit 44 indirectly corrects the image read by the image reading unit 15 according to the density and / or position of the mark image. As a result, the color correction unit 44 may of course correct the image read by the image reading unit 15 directly according to the density and / or position of the mark image.

  In this embodiment, the color correction unit 44 increases the luminance of a predetermined low-luminance region with respect to the image read by the image reading unit 15 at this time. That is, the width of the low luminance region and the amount of increase in luminance are adjusted according to the stationary angle of the document cover 7.

  At this time, the color correction unit 44 may adjust the threshold value of “background skip” in color correction. That is, the threshold value for “skin removal” is adjusted according to the stationary angle of the document cover 7.

  Further, in this embodiment, the color correction unit 44 corrects the default color correction table 51 according to the density and / or position of the mark image, and is read by the image reading unit 15 with the corrected color correction table. The above-described image correction is performed by performing color conversion of the image. In this embodiment, the color correction unit 44 corrects the default color correction table 51 according to the stationary angle of the document cover 7 described above. Thereby, the color correction unit 44 indirectly corrects the default color correction table 51 according to the density and / or position of the mark image. As a result, the color correction unit 44 may of course correct the default color correction table 51 directly according to the density and / or position of the mark image.

  The output image generation unit 45 generates and outputs image data in a predetermined format from the image after color correction by the color correction unit 44. When copying, the output image generation unit 45 performs various image processing on the image after color correction by the color correction unit 44, generates image data in a format that can be processed by the printing unit 33, and prints the printing unit. The image data may be supplied to the printer 33 and printing based on the image data may be executed. Image processing at this time includes edge enhancement using a differential filter for character areas, smoothing using an integration filter for halftone areas, sharpening of character areas and reduction of moire and noise in halftone areas. Adaptive processing for a region, UCR (Under Color Removal) processing, and the like are included as appropriate.

  The cover shift detection unit 46 detects the shift of the document cover 7 based on the shift amount of the position of the mark image obtained by the mark specifying unit 43 from the reference position. In this embodiment, the cover shift detection unit 46 detects the shift of the document cover 7 when the document detection sensor 31 has not detected a read object such as a document on the contact glass 1.

  Next, the operation of the image reading apparatus will be described.

  Here, an image reading process for an object to be read (such as a sheet-like document or a three-dimensional object) and a document cover misalignment detection process will be described.

(1) Image reading process

  FIG. 5 is a flowchart for explaining image reading processing by the image reading apparatus shown in FIGS. 1, 2, and 3.

  When performing a copy or image scan, the user places a read object on the contact glass 1 and then performs a user operation for the copy or image scan on the user interface 32.

  When the object to be read is a sheet-like document (for example, one sheet of A4 size), the sheet-like document is in close contact with the contact glass 1, and the document cover 7 is a sheet-like document or a sheet-like document. The original and the contact glass 1 are in close contact with each other. At this time, the stationary angle of the document cover 7 is approximately 0 degrees.

  On the other hand, when the object to be read is a three-dimensional object, the document cover 7 comes into contact with the three-dimensional object, but is not in close contact with the three-dimensional object and the contact glass 1 and is opened. At this time, the stationary angle of the document cover 7 is an angle corresponding to the shape of the three-dimensional object.

  When the above-described user operation is detected by the user interface 32, the control unit 41 first controls the image reading unit 15 to execute image reading and obtains image data (step S1).

  Next, the read object type specifying unit 42 specifies the type of the read object (either a three-dimensional object or a sheet-like original) based on the output of the original detection sensor 31 (step S2).

  At this time, the mark specifying unit 43 specifies the density and position of the mark image of the three-dimensional mark 22 in the image read by the image reading unit 15, and the read object type specifying unit 42 reads the mark image. The type of the object to be read may be specified from the density and position.

  The control unit 41 determines whether or not the type of the read object specified by the read object type specifying unit 42 is a sheet document (step S3), and when the type of the read object is a sheet document In this case, the color correction unit 44 performs color correction by the default color correction table 51 on the image read by the image reading unit 15 (step S4).

  On the other hand, when the type of the read object is not a sheet-like document (that is, when the type of the read object is a three-dimensional object), the control unit 41 first reads the mark specifying unit 43 by the image reading unit 15. The density and position of the mark image of the three-dimensional mark 22 in the obtained image are specified (step S5). The mark specifying unit 43 specifies the density and position of the mark image, and specifies the stationary angle of the document cover 7 from the density and position of the mark image.

  FIG. 6 is a cross-sectional view for explaining the distribution of the distance from the surface of the three-dimensional mark 22 when the object to be read has a three-dimensional shape in the image reading apparatus shown in FIGS. 1, 2, and 3. As shown in FIG. 6, since the distance from the contact glass 1 to the three-dimensional mark 22 is changed, a density change corresponding to the change in the distance occurs in the image read by the image reading unit 15. Therefore, the mark specifying unit 43 specifies the density and position of the mark image based on the change in density.

  If the mark specifying unit 43 has already specified the density and position of the mark image of the three-dimensional mark 22 in the image read by the image reading unit 15 in step S2, the process of step S5 is unnecessary. It is. However, in step S5, the mark specifying unit 43 specifies the stationary angle of the document cover 7 from the density and position of the mark image.

  The color correction unit 44 reads the default color correction table 51, corrects the default color correction table 51 according to the stationary angle of the document cover 7, and generates a custom color correction table (step S6). Color correction is performed on the image read by the image reading unit 15 using the color correction table (step S7). At this time, the color correction unit 44 generates a custom color correction table so that the luminance of a predetermined low luminance region is increased from the default color correction table 51. By increasing the luminance of the low luminance region, the luminance of the fogged portion is increased in this color correction.

  Thereafter, the output image generation unit 45 executes predetermined image processing on the image after the color correction in step S4 or step S7, and outputs the image after the image processing to the printing unit 33, for example.

  As described above, by executing different image processing depending on the type of the object to be read, image quality deterioration such as fogging at the time of image reading of the three-dimensional object is suppressed. Further, since it is not necessary to make the density and color of the three-dimensional mark 22 different from that of the cover plane 21, show-through of the three-dimensional mark 22 when reading a sheet-like document is reduced.

(2) Misalignment detection processing of document cover 7

  If a deviation occurs in the position of the document cover 7, an error occurs in the position of the detected mark image. Therefore, in order to accurately perform the above-described image reading process, the deviation detection process of the document cover 7 is appropriately executed. FIG. 7 is a flowchart for explaining the displacement detection processing of the document cover 7 by the image reading apparatus shown in FIGS.

  The user performs a user operation for pre-scanning on the user interface 32.

  When the above-described user operation is detected by the user interface 32, the control unit 41 first controls the image reading unit 15 to execute image reading and acquires image data (step S21).

  Next, the read object type specifying unit 42 determines whether the read object is placed on the contact glass 1 based on the output of the document detection sensor 31 (step S22).

  When the object to be read is not placed on the contact glass 1, the mark specifying unit 43 specifies the position of the mark image in the image read by the image reading unit 15 (step S23). Next, the cover shift detection unit 46 specifies the shift amount of the specified mark image. Here, the cover shift detection unit 46 specifies the distance between the position of the specified mark image and the reference position of the mark image in the main scanning direction and the sub-scanning direction (step S24). Note that the reference position of the mark image is measured in advance without any deviation of the document cover 7, and data of the reference position is held in the cover deviation detection unit 46 in advance.

  Then, the cover shift detection unit 46 determines whether or not the shift amount specified in step S24 is large enough to satisfy a predetermined condition (step S25).

  For example, when the distance between the position of the mark image in the main scanning direction and the reference position is X, and the distance between the position of the mark image in the sub-scanning direction and the reference position is Y, the above condition is X + Y > A (where A is a predetermined threshold).

  When the amount of deviation satisfies a predetermined condition, the cover deviation detection unit 46 displays a warning message indicating that the document cover 7 is displaced on the user interface 32 (step S26). When the deviation amount does not satisfy the predetermined condition, the cover deviation detection unit 46 ends the process without displaying the warning message.

  If it is determined in step S22 that the object to be read is placed on the contact glass 1, the above-described deviation detection processing of the document cover 7 is not executed.

  As described above, when the object to be read is not placed, the three-dimensional mark 22 on the cover plane 21 is read, and the deviation of the document cover 7 is detected based on the position of the mark image for the three-dimensional mark 22. The user is notified. When the user notices the above warning message, the user returns the position of the document cover 7 to the correct position. As a result, the document cover 7 is not inclined, image quality deterioration during image reading is suppressed, and the above-described image correction based on the density and / or position of the mark image is accurately executed.

  As described above, according to the above embodiment, the three-dimensional mark 22 is provided at a predetermined position on the cover plane 21 of the document cover 7, and the mark specifying unit 43 is three-dimensional within the image read by the image reading unit 15. The mark image of the shape mark 22 is detected, and the density and / or position of the mark image is specified. The color correction unit 44 corrects the image read by the image reading unit 15 according to the density and / or position of the mark image.

  Thus, by providing the three-dimensional mark 22 on the document cover 7, it is possible to reduce image quality degradation such as fogging by image processing from the density and / or position of the mark image. Therefore, it is possible to reduce image quality degradation such as fogging at a low cost when the object to be read is a three-dimensional object. As a result, it is possible to reduce the toner consumption of the fogged portion when printing the read image. Further, since it is not necessary to make the density and color of the three-dimensional mark 22 different from that of the cover plane 21, show-through of the three-dimensional mark 22 when reading a sheet-like document is reduced.

  Further, according to the above embodiment, the cover shift detection unit 46 detects the shift of the document cover 7 based on the shift amount of the position of the mark image from the reference position.

  As a result, the document cover 7 is correctly arranged by the user so that the position of the mark image becomes the reference position, so that the density and position of the mark image are accurately detected.

  The above-described embodiments are preferred examples of the present invention, but the present invention is not limited to these, and various modifications and changes can be made without departing from the scope of the present invention. is there.

  For example, in the above embodiment, the color correction unit 44 or the output image generation unit 45 may remove the mark image.

  The present invention is applicable to, for example, a scanner, a copying machine, a digital multifunction machine, and the like.

1 Contact glass (an example of a mounting table)
7 Document Cover 15 Image Reading Unit 21 Cover Plane 22 3D Mark 31 Document Detection Sensor (Example of Sensor)
35 Storage Device 43 Mark Identification Unit 44 Color Correction Unit (Example of Image Correction Unit)
46 Cover shift detection unit 51 Default color correction table (an example of a color correction table)

Claims (9)

A transparent mounting table on which the object to be read is mounted;
A document cover having a three-dimensional mark at a predetermined position on a cover plane covering the object to be read placed on the table;
An image reading unit that reads an image of the object to be read and the cover plane placed on the mounting table;
A mark specifying unit for detecting a mark image of the three-dimensional mark in an image read by the image reading unit and specifying a density and / or position of the mark image;
Equipped with a,
The three-dimensional mark has a surface parallel to the cover plane,
The color of all surfaces of the three-dimensional mark is the same as the color of the cover plane;
An image reading apparatus.   The image reading apparatus according to claim 1, wherein the three-dimensional mark has a concave shape.   The image reading apparatus according to claim 1, wherein the three-dimensional mark is made of an elastic material and has a convex shape.   The image reading apparatus according to claim 1, further comprising an image correcting unit that corrects an image read by the image reading unit according to a density and / or position of the mark image. The image reading apparatus according to claim 4 , wherein the image correction unit increases the luminance of a predetermined low luminance region with respect to the image read by the image reading unit. Wherein the image correction unit includes an image reading apparatus according to claim 4 or claim 5, wherein removing the mark image in the image read by the image reading unit. A storage device for storing a color correction table;
The image correction unit corrects the color correction table according to the density and / or position of the mark image, and performs color conversion of an image read by the image reading unit with the corrected color correction table;
An image reading apparatus according to claim 4 or 5, wherein The position of the mark image on the basis of the deviation amount from the reference position, any one of the claims 1 to 7, wherein, characterized in that it comprises further a Kabazure detector for detecting a deviation of the document cover The image reading apparatus described. 9. The image reading apparatus according to claim 8 , wherein the cover shift detection unit detects a shift of the document cover when the object to be read is not detected on the mounting table.

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