JP2012186515A - Image reading apparatus and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correctly extract a pattern formed on an original based on presence/absence of the luster without increasing the scale of the apparatus configuration and the cost.SOLUTION: By controlling a CPU 38, an image reading apparatus sets a light source 24 to an irradiation position where halation is not generated by light emitted onto an image reading surface and reads an image to which halation is not generated from the image reading surface, sets the light source 24 to an irradiation position where halation is generated by light emitted onto the image reading surface and reads the image to which halation is generated from the image reading surface, and thereby detects a glossiness portion of an original based on both images with or without halation by a glossiness detection part 35.

Description

  The present invention relates to an image reading apparatus that reads an image of a document, and an image forming apparatus that includes a facsimile apparatus, a printer, a copying machine, and a multi-function peripheral including the image reading apparatus.

There is a technique called marking represented by a bar code.
This is a technique for reading a document on which a specific pattern is printed and extracting information indicated by the pattern from a pattern extracted from the read image.
This technology is still used for various purposes.
For example, many barcodes (QRcodes) for guiding to related homepages are found in product labels and publications.

In office documents, a copy-forgery-inhibited pattern designating permission or prohibition of copying by a copying machine is also used.
A barcode is a type that occupies the local area of a manuscript with a specific pattern, and a background pattern is a type that overlays a pattern composed of many small dots and lines with content. It can be said that it is a “jam” for the viewer.

This is because content (characters and figures) that humans see and understand are mixed in the same page with patterns that make the machine understand.
Therefore, in order to eliminate a pattern such as a barcode or a background pattern in a document content from being “unobtrusive”, for example, the pattern may be printed with inconspicuous color toner (ink).

  In recent years, it has become possible to use a transparent toner in an electrophotographic process of an image forming apparatus including a facsimile machine, a printer, a copier, and a multifunction peripheral. In this example, the transparent toner is used in a document content. Think about removing the bar codes and background patterns such as those that aren't “jams”.

First, if a pattern is printed with transparent toner, a pattern such as a barcode or a tint block can be removed from “jamming”, but a problem arises regarding the extraction of a new pattern.
In other words, a transparent toner pattern that cannot be seen by humans cannot be read even if it is read by an image reading device (scanner) that reads an image of a document.

This is because a normal image reading apparatus is designed to obtain an image having the same appearance as that observed by a human.
Therefore, the above problem cannot be solved unless this design is changed somewhat.
Therefore, conventionally, the following techniques have been proposed as means for solving the above problems.

(1) Technology to mix a special material with transparent toner An image is formed on a manuscript with fluorescent ink that emits fluorescence with respect to ultraviolet rays. The manuscript is irradiated with ultraviolet rays, and is formed with fluorescent ink by light excited by the fluorescent ink. An invisible image is formed using an image detection technique (see, for example, Patent Document 1) or a recording material having an absorption region for invisible light on a manuscript, and the manuscript is irradiated with invisible light including infrared rays to absorb the light. There is a technique (for example, refer to Patent Document 2) for detecting an invisible image based on the applied portion.

(2) Technology for generating gloss with transparent toner The area where the transparent toner is applied has increased smoothness and gloss, and the area where the transparent toner is not applied maintains the low smoothness of the paper and does not generate gloss.
Therefore, there is a technique (for example, Patent Document 3) in which a binary pattern is observed in both regions by detecting regular reflection light. According to this technology, it can be seen by humans from a specific angle, but it is not so much as a “stupid” thing.

(3) Since the color of the original (wavelength absorbed by the original) can be read more accurately when the irregularly reflected light is detected than the regular reflected light, a CCD for receiving the irregularly reflected light is provided, and only the irregularly reflected light is detected. There exists a technique (for example, patent document 4) to detect.
The amount of diffusely reflected light increases or decreases depending on the color of the document (the color of the paper itself or the toner or ink attached), but also increases or decreases depending on the degree of gloss.

As shown in FIG. 9, if the color of the original is the same, the glossy glossy area of the original shown in FIG. 9B is compared to the non-glossy non-glossy area of the original shown in FIG. There is a principle that the amount of irregularly reflected light with respect to incident light is reduced.
Using this principle, the gloss pattern on the background of the paper (the portion where no toner or ink is attached) is read.

  However, in the technique (1) described above, if a pattern is formed by a region printed with fluorescent ink and a region not printed, a binary pattern image with different light reception can be detected, but the fluorescent ink itself is also transparent. Therefore, although it does not become a “jamming”, it is necessary to provide the image reader with special illumination and light receiving elements that cover even the invisible wavelength range, and there is a problem that the manufacturing of the image reader becomes expensive. .

The technique (2) is not for reading a gloss pattern, but a gloss pattern can be read by using a regular reflection light receiving element.
However, since a dedicated light receiving element is provided in the image reading apparatus, there is a problem that the system of the image reading apparatus becomes enormous and the manufacturing of the image reading apparatus becomes expensive.

  Furthermore, in the technique (3), the luminance value of the glossy area and the non-glossy area is specified from the frequency distribution (histogram) of the luminance value of the image obtained by scanning with a specific illumination light amount (normally 85%). Therefore, it is not necessary to provide special illumination or light receiving elements in the image reading apparatus, and there is no problem that the manufacturing of the image reading apparatus is expensive.

However, there arises a new problem that the diversity of paper cannot be dealt with.
That is, the pattern may not be detected correctly depending on the whiteness of the paper.
Even if a pattern can be detected on a sheet with high whiteness, the brightness value of the glossy area and the non-glossy area are too close to each other on a sheet with low whiteness and cannot be discriminated.

  The present invention has been made in view of the above points, and in order to correctly extract a pattern formed with glossiness on a manuscript, the apparatus configuration is not enlarged and the cost of the apparatus is not increased. With the goal.

  In order to achieve the above object, the present invention irradiates the image reading surface with light from the light source while conveying the image reading surface of the document in the sub-scanning direction of image reading with respect to the light source. In the image reading apparatus that reads the image of the original document based on the reflected light, the light source is set to an irradiation position that does not cause halation by the light applied to the image reading surface, and an image when no halation occurs from the image reading surface is obtained. Read and set the light source to an irradiation position where halation is caused by the light applied to the image reading surface, reading means for reading an image when halation occurs from the image reading surface, and the halation read by the reading means occurs. The glossy part of the document is detected based on both the images when it is touched and when it does not wake up To provide an image reading apparatus provided with gloss sensing means.

Further, in the image reading apparatus as described above, an image provided with means for causing the image reading surface to be curved in the sub-scanning direction of image reading with respect to light irradiated from the light source during conveyance of the document. It may be a reader.
Furthermore, in the image reading apparatus as described above, the reading unit sets the irradiation position where the halation does not occur as a normal position of the light source, and reads the image when the halation occurs when the light source is used as the image. It is preferable to include means for moving in the sub-scanning direction of image reading to a preset irradiation position where halation is caused by light irradiated on the reading surface.

  In the image reading apparatus as described above, the reading unit includes a second reading unit that reads an image on the other image reading surface of the document, and an image reading surface of the document with respect to the second reading unit. The original reversing means for reversing and the light source at the irradiation position where halation is caused by the light irradiated on the image reading surface, and after reading the image when the halation occurred from the image reading surface, the original reversing means It is preferable to include means for inverting the image reading surface of the document and reading an image when halation does not occur from the image reading surface by the second reading means.

  Further, in the image reading apparatus as described above, the reading unit causes halation by a document reversing unit that reverses the image reading surface of the document with respect to the light source, and light irradiated on the image reading surface by the light source. After reading an image when halation occurs from the image reading surface at the irradiation position, the image reading surface of the document is reversed by the document reversing means, and an image when no halation occurs from the image reading surface is obtained. A means for reading may be included.

Further, in the image reading apparatus as described above, it is preferable to provide means for temporarily increasing the document conveyance speed when the document is reversed by the document reversing means.
Further, in the image reading apparatus as described above, it is preferable to provide correction means for correcting the line interval in the sub-scanning direction of image reading for the image when the halation occurs.
In the image reading apparatus as described above, the gloss detecting unit may include a portion where the difference in reflectance between the images when the halation read by the reading unit occurs and when the halation does not occur exceeds a predetermined value. It is preferable to include means for detecting as a glossy part of the.

  Furthermore, in the image reading apparatus as described above, the output characteristics with respect to the reflectance of the image when the halation read by the reading means occurs, and the reflectance of the image when the halation read by the reading means does not occur It is preferable to provide means for correcting the difference with respect to the output characteristic.

In the image reading apparatus as described above, the output characteristics with respect to the reflectance of the image when the halation read by the reading unit occurs, and the image of the image when the halation read by the second reading unit does not occur. Means for correcting a difference from the output characteristic with respect to the reflectance may be provided.
Further, an image forming apparatus provided with the image reading apparatus as described above is also provided.

  The image reading apparatus and the image forming apparatus according to the present invention can correctly extract a pattern formed with glossiness on a document, so that the apparatus configuration is not enlarged and the cost of the apparatus is not increased.

FIG. 3 is a block diagram illustrating a functional configuration related to image processing of the image reading apparatus illustrated in FIG. 2. 1 is a schematic configuration diagram illustrating a mechanism unit of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is an enlarged view of a peripheral portion including a conveyance drum and a light source of the image reading apparatus illustrated in FIG. 2.

FIG. 3 is an enlarged view of a peripheral portion including a conveyance drum and a light source of the image reading apparatus shown in FIG. 2. It is a flowchart figure which shows the glossiness detection process by the process part shown in FIG. It is a figure which shows the example of an image with which it uses for description of the glossy area identification process in the glossiness detection part shown in FIG.

It is a figure of the graph of the approximate straight line of linearity. It is a flowchart figure which shows the other gloss detection process by the process part shown in FIG. It is a figure which shows an example of the mode of the reflected light in the glossy area and the non-glossy area of a document. It is a figure with which it uses for description of the halation which arises when light is irradiated to a book original.

Hereinafter, embodiments for carrying out the present invention will be specifically described with reference to the drawings.
FIG. 2 is a schematic configuration diagram showing a mechanism portion of the image forming apparatus 100 according to one embodiment of the present invention.
The image forming apparatus 100 is a multi-function apparatus in which a plurality of functions including a copy function, a printer function, a communication function including facsimile communication and communication via the Internet are integrated, and the main body of the image forming apparatus 100 is An image reading device (scanner) 1 is mounted on the top. An operation unit (not shown) is provided on the upper surface on the front side.

The image reading apparatus 1 includes an automatic document feeder (auto document feeder: ADF) 2 and a reader 3.
The ADF 2 drives a pickup roller 10, a conveyance roller group 12 including a conveyance drum 11, and the like, and the sheet-like document P placed on the document tray 13 passes through the position of the sheet document glass 22 of the reading unit 3 at a constant speed. To be conveyed. The original P from which the image has been read is conveyed to the paper discharge tray 14 and discharged.

In the reading unit 3, a contact glass 20, a reference white plate 21, and a sheet original glass 22 are arranged on the upper side.
The contact glass 20 is for setting the document P ′ in the book document reading mode (also referred to as “pressure plate reading mode”).
The book document reading mode is a mode for reading an image of the document P ′ while moving the first carriage 23 and the second carriage 26 with respect to the document P ′ placed on the reference white plate 21 and the contact glass 20. .

  The sheet original glass 22 is provided at a sheet original reading position for reading the original P conveyed in the sheet original reading mode (also referred to as “sheet through reading mode”).

  In this sheet document reading mode, when the reference white plate 21 is read, the first carriage 23 and the second carriage 26 are moved to the reference white plate 21 and when reading the document P, the first carriage 23 and the second carriage 26 are moved. In this mode, the image of the original P is read while the original P is being conveyed to the sheet original reading position while being stopped at the sheet original reading position.

The reference white plate 21 is a member that is read in order to obtain correction data at the time of shading correction, and is a substantially white member having a uniform density provided in the main scanning direction of the image reading direction.
The reading unit 3 includes a first carriage 23, a second carriage 26, a lens 29, a CCD 30, a scanner motor 31, and a processing unit 32.

The first carriage 23 includes a light source 24 and a mirror 25 and is movable in the sub-scanning direction of the image reading direction.
The second carriage 26 has mirrors 27 and 28, and is similarly movable in the sub-scanning direction of the image reading direction.

The light source 24 is a lamp, which is turned on by applying a driving voltage from a lamp ballast (not shown in FIG. 2) and illuminates the image reading surfaces of the originals P and P ′ at a predetermined angle.
The light emitted from the light source 24 is reflected by the reference white plate 21 or the image reading surface of the originals P and P ′, passes through the three mirrors 25, 27 and 28 and the lens 29, and is a CCD 30 which is a photoelectric conversion element. Is incident on.
The first carriage 23 and the second carriage 26 stand by at the reading position in the sheet document reading mode when not operating.

  In the book document reading mode, the first carriage 23 and the second carriage 26 are driven by a motor of a scanner motor 31 such as a stepping motor, while the distance between the image reading surface of the document P ′ and the CCD 30 is kept constant. It moves in the scanning direction and reads the image reading surface of the original P ′ placed on the reference white plate 21 and the contact glass 20.

On the other hand, in the sheet original reading mode, the image reading surface of the original P conveyed by the ADF 2 is read while the first carriage 23 and the second carriage 26 are stopped at the sheet original reading position.
The CCD 30 includes a known clock driver, timing signal generation unit, and signal processing unit (not shown).

The CCD 30 outputs a voltage corresponding to the incident light amount of the incident light and passes it to the processing unit 32 as image data. When the CCD 30 reads an image on the front side of the document P, the back side is read again at a predetermined position by the document reversing mechanism 16 that reverses the front and back of the document, or downstream in the transport direction from the reading position on the front side. The image surface on the back side of the document P can be read by a CIS (Contact Image Sensor) 15 disposed at the reading position on the back side.
The CIS 15 uses an LED (light emitting diode) as a light source, directly reads an image with a linear sensor, and passes the read image data to the processing unit 32.

Next, the writing unit 4 includes a laser output unit 41, an imaging lens 42, a mirror 43, and the like.
Inside the laser output unit 41, a laser diode that is a laser light source and a polygon mirror (rotating polygon mirror) (not shown) that is rotated at a constant high speed by a motor are provided.

The laser output unit 41 irradiates a laser beam based on the image data from the processing unit 32, the laser beam is deflected by a polygon mirror that rotates at a constant speed, passes through an imaging lens 42, is folded by a mirror 43, and is exposed to light. The light is condensed on the charged surface of the body drum 44 and imaged.
The deflected laser beam is exposed and scanned in a direction (main scanning direction) orthogonal to the direction in which the photosensitive drum 44 rotates, and image data output by a selector of an image processing unit (not shown) is written in line units. Recording is performed for main scanning.

By repeating this main scanning at a predetermined cycle corresponding to the rotational speed of the photosensitive drum 44 and the scanning density (recording density), an electrostatic latent image is formed on the charged surface of the photosensitive drum 44.
Although not shown, a beam sensor is arranged at a position where a laser beam near one end of the photosensitive drum 44 is irradiated, and a main scanning synchronization signal is generated therefrom. Based on the main scanning synchronization signal, a control signal for controlling image recording timing in the main scanning direction and inputting / outputting the image signal is generated.

As the electrostatic latent image on the photosensitive drum 44 passes through the developing unit 45, a toner image is formed on the photosensitive drum 44.
On the other hand, transfer paper (paper) for forming an image is stacked on the first paper feed tray 51, the second paper feed tray 52, or the third paper feed tray 53, and the first paper feed device 54, The paper is fed by the second paper feeding device 55 and the third paper feeding device 56 and is transported by the vertical transport unit 50 to a position where it abuts on the photosensitive drum 44.

Actually, any one of the paper feed trays 51 to 53 is selected, and the transfer paper is fed therefrom.
The toner image on the photosensitive drum 44 is transferred to one of the first surfaces while the fed transfer paper is conveyed by the conveyance belt (transfer belt) 46 at the same speed as the rotation of the photosensitive drum 44. Then, the toner image is fixed by the fixing unit 47 and discharged to a discharge tray 57 outside the apparatus.

  In addition, when forming toner images on both sides of the transfer paper, the transfer paper with the toner image formed on the first side is not transported to the discharge tray 57 side, and the path is switched by a branching claw not shown in the figure. Once transported to the duplex transport path 49. Thereafter, the transfer paper is fed again, and the toner image formed on the photosensitive drum 44 is transferred to the other second surface. Thereafter, the toner image is fixed by the fixing unit 47, and then the paper discharge tray 57. To discharge.

The paper discharge unit 48 discharges the transfer paper to the paper discharge tray 57 when the staple mode is not performed.
In this manner, the image forming apparatus 100 operates the double-sided conveyance path 49 when images are formed on both sides of the transfer paper.

Next, a functional configuration relating to image processing of the image reading apparatus 1 shown in FIG. 2 will be described.
FIG. 1 is a block diagram showing a functional configuration related to image processing of the image reading apparatus 1 shown in FIG.
The processing unit 32 is realized by a microcomputer, and includes image processing units 33 and 34, a gloss detection unit 35, and a CPU 38.

The gloss detection unit 35 includes a difference calculation unit 36 and a memory 37.
The image reading device 1 sends an analog electric signal of an image obtained by the CCD 30 to the image processing unit 33.
The image processing unit 33 inputs an analog electrical signal of an image to an analog processing part that performs analog processing via an analog signal buffer (not shown) and AC coupling because it is publicly known.

Similarly, the analog processing portion not shown because it is publicly known is processed in the order of the line clamp, S & H, gain processing unit, and A / D conversion unit to obtain digital image data of the images of the documents P and P ′.
The obtained digital image data (image data) of the images of the originals P and P ′ is subjected to various image processing including shading correction and interline correction using a dedicated image processing IC and field memory.

  The shading correction process is an image process for correcting reading unevenness of the reading system, particularly the optical system. This is a process of correcting and making the dynamic range of all pixel data in the output image data of the reading system equal.

  The inter-line correction process is a correction process for correcting the line interval in the sub-scanning direction of image reading in image data. For example, when a 3-line CCD 30 is used, the reading positions of RGB originals P and P ′ are different. Therefore, the other two colors are input to the field memory so as to match the slowest color at which the same position is read, respectively, and the read timing is changed, that is, an electrical delay is given. This is a process for adjusting the reading position of the colored light.

  In addition, when the magnification is changed by changing the speed of the first carriage 23 and the second carriage 26, the line interval also changes. Therefore, the read amount of the field memory is changed, and the delay amount is changed each time.

  Further, the movement of the first carriage 23 and the second carriage 26 is performed in the book document reading mode or the sheet document reading mode based on the manuscript size information obtained by an operation unit (not shown) or manuscript size detection. The reciprocating operation of the first carriage 23 and the second carriage 26 with respect to the image reading surface of the originals P and P ′ and the reference white plate 21 is performed, and the moving speed during the reciprocating operation is similarly determined by the CPU 38 in accordance with the input magnification ratio. Is changed by sending a control signal to the scanner motor 31 and controlling the rotational speed of the scanner motor 31.

  In the sheet original reading mode, the processing unit 32 of the image reading apparatus 1 conveys the original P in the image reading sub-scanning direction, and on the background plate 60 curved along the conveying drum 11 as shown in FIG. , The image reading surface of the document P moves so as to be curved in the sub-scanning direction of image reading with respect to the light L emitted from the light source 24.

  Then, the light source 24 is set to an irradiation position that does not cause halation by the light L applied to the image reading surface (the light L from the light source 24 is set to the normal reading position in the drawing), and the image reading surface of the light source 24 is illuminated. The reflected light is guided to the CCD 30 by the reduction optical system, and the image on the surface of the document P can be read line by line without causing halation.

  Further, the light source 24 is moved to the irradiation position where halation is caused by the light L irradiated to the image reading surface (from the position where the light L from the light source 24 is irradiated to the gloss detection position in the figure to the position where the gloss detection position is reached). The image reading surface of the light source 24 is illuminated and the reflected light is guided to the CCD 30 by the reduction optical system, so that the image on the surface of the document P can be read line by line in a state where halation has occurred.

  In general, in an image reading apparatus that irradiates an original from an oblique direction using a tube light and a scanner light source using an LED, the reflected light from the original out of the light reflected on the original is used because it can be read with high accuracy as described above. In general, the reflected light (diffuse reflected light) in the direction perpendicular to the original is read without being read in many directions, that is, in the regular reflection direction.

However, even when illuminated from an oblique direction, as shown in FIG. 10, for example, when a binding portion such as a book is read, the light emitted from the light source 70 to the bent portion A that is farther than the document table by binding. When L is a certain angle, the specularly reflected light is emitted in the direction perpendicular to the surface of the document table.
As a result, the specularly reflected light is directly taken into the CCD 30, and the amount of light is too much larger than the amount of reflected light when a normal document is being read, causing white spots (halation) on the image.

As described with reference to FIG. 9, this halation phenomenon is more prominent because the specular reflection light is more intense in the glossy part having a smooth surface than in the non-glossy part.
Therefore, in the image forming apparatus 100 of this embodiment, in order to identify the glossy portion and the non-glossy portion of the document P by detecting this halation on the image, the object is to surely generate halation on the image, By providing the background plate 60, the original P is read in a bent state.

  2 is reversed by the document reversing mechanism 16 shown in FIG. 2, so that the document once transported in the positive direction of the sub-scanning direction of image reading is sub-scanned with the back surface of the document P as the light source 24 side. By conveying in the negative direction, the image on the back side of the document P can be read line by line with the CCD 30 in a state of causing halation.

As for the image on the back side of the front side of the original, the front side of the original P is read as described above, the image on the back side of the original P is simultaneously read by the CIS 15, and the image on the front side of the original P is read by the CIS 15. Thus, the back side of the document P can be read.
The image data read by the CIS 15 is subjected to the same processing as the image processing unit 33 by the image processing unit 34 and is sent to the gloss detection unit 35.

  Then, the CPU 38 in FIG. 1 controls each part including the CCD 30, the CIS 15, and the scanner motor 31 to bring the light source into an irradiation position where no halation is caused by the light irradiated on the image reading surface, and halation from the image reading surface. The reading unit reads an image when no occurrence occurs, sets the light source to an irradiation position where halation is caused by light applied to the image reading surface, and functions as a reading unit that reads an image when halation occurs from the image reading surface.

Further, the gloss detecting unit 35 of FIG. 1 functions as a gloss detecting unit that detects a glossy portion of the document based on both images when the halation read by the reading unit occurs and when the halation does not occur.
Further, the background plate 60 shown in FIG. 3 corresponds to means for causing the image reading surface to be curved in the sub-scanning direction of image reading with respect to the light emitted from the light source during conveyance of the document. .

When the CPU 38 in FIG. 1 controls each part including the CCD 30, the CIS 15, and the scanner motor 31, the irradiation position where the halation does not occur is set as the normal position of the light source, and the image when the halation occurs is read. In addition, it also functions as a means for moving the light source in the sub-scanning direction of image reading to a preset irradiation position where halation is caused by light irradiated on the image reading surface.
Further, the CIS 15 in FIG. 2 corresponds to a second reading unit that reads an image on the other image reading surface of the document.

  Further, the CPU 38 in FIG. 1 controls each part including the CCD 30, the CIS 15, and the scanner motor 31, whereby a document reversing unit that reverses the image reading surface of the document with respect to the second reading unit, and the light source for the image. After reading the image when halation occurs from the image reading surface at the irradiation position where halation is caused by the light irradiated on the reading surface, the image reading surface of the document is reversed by the document reversing means, and the second The reading means also functions as a means for reading an image when no halation occurs from the image reading surface.

Further, the document reversing mechanism 16 shown in FIG. 2 corresponds to the document reversing means for reversing the image reading surface of the document with respect to the light source.
Further, the CPU 38 in FIG. 1 controls each part including the CCD 30, the CIS 15, and the scanner motor 31, so that the light source is brought into an irradiation position where halation is caused by light irradiated on the image reading surface, and halation is generated from the image reading surface. After reading the image when it occurred, the document reversing means reverses the image reading surface of the document, and also functions as a means for reading the image when halation does not occur from the image reading surface.

Further, the CPU 38 shown in FIG. 1 functions as a means for temporarily increasing the document transport speed when the document is reversed by the document reversing means by controlling each part including the scanner motor 31.
Further, the CPU 38 in FIG. 1 functions as a correction unit that corrects the line interval in the sub-scanning direction of image reading for the image when the halation occurs.

Further, the gloss detecting unit 35 in FIG. 1 detects a portion where the difference in reflectance between both images when the halation read by the reading unit occurs and when it does not occur as a glossy portion of the document. It also serves as a means.
Further, the gloss detecting unit 35 in FIG. 1 outputs an output characteristic with respect to the reflectance of the image when the halation read by the reading unit occurs, and the reflectance of the image when the halation read by the reading unit does not occur. It also functions as a means for correcting the difference from the output characteristic for.

  Further, the gloss detection unit 35 in FIG. 1 outputs the output characteristics with respect to the reflectance of the image when the halation read by the reading unit occurs and the image when the halation read by the second reading unit does not occur. It also functions as a means for correcting the difference between the output characteristic and the reflectance.

Next, gloss detection processing in the image reading apparatus 1 will be described.
FIG. 3 is an enlarged view of a peripheral portion including the conveyance drum 11 and the light source 24 of the image reading apparatus 1 shown in FIG.
FIG. 5 is a flowchart showing gloss detection processing by the processing unit 32 shown in FIG.
FIG. 6 is a diagram illustrating an example of an image that is used for explaining the gloss area identification process in the gloss detection unit 35 illustrated in FIG. 1.

  When gloss detection reading is instructed by an instruction from the user or automatic start, as shown in FIG. 5, the CPU 38 in FIG. 1 first turns on the light source 24 in FIG. (Indicated by “S” in the drawing) 1), the first carriage 23 in FIG. 2 (described as “carriage” in FIG. 5) is moved below the reference white plate 21, the reference white plate 21 is read, and the image Data (reference white board image data) is acquired (S2).

Next, the carriage is moved to move the light source 24 of FIG. 2 to the gloss detection position, which is the irradiation position where halation is caused by the light irradiated on the image reading surface (S3).
Next, when the document P is conveyed, the image reading surface (front surface) of the document P is curved in the sub-scanning direction of image reading with respect to the light irradiated from the light source 24 by the curved background plate 60 shown in FIG. Therefore, when the original P is irradiated with light in this state, the specular reflection component is strongly emitted in the glossy area of the image reading surface (front surface), and the image data (surface halation image) in the state where halation has occurred. Data) is acquired (S4).

  Note that the irradiation position at which halation occurs on the document P differs depending on the light source to be used and the configuration of the optical system of the automatic document feeder.

Next, after reading the image reading surface of the surface of the document P, the light source 24 in FIG. 2 is turned off (S5).
Then, it is determined whether or not gloss detection is performed on the back side (S6). If gloss detection is also targeted on the back side of the document P (Y in S6), the document P shown in FIG. The back side of the document P is normally read by the CIS 15 arranged on the downstream side in the conveyance direction of the image, and the image data (normal image data) is acquired (S7). The image data acquired by the CIS 15 is an image in a normal state in which no halation has occurred.

  If the gloss detection is not targeted for the back side of the document P (N in S6), the process of step 7 for reading the back side is not performed, and then the document P is output to the discharge port. The document is conveyed to the previous document reversing mechanism 16, and the document reversing mechanism 16 reverses the front and back surfaces of the document P (S18).

  Next, the original P is conveyed again toward the light source 24 with the front and back sides reversed. When the back side is also a reading target as described above, the gloss detection position is also applied to the back side. 2, the light source 24 is turned on (S 9), the first carriage 23 (described as “carriage” in FIG. 5) 23 in FIG. 2 is moved below the reference white plate 21, the reference white plate 21 is read, and the image data (Reference white board image data) is acquired (S10).

  Next, the carriage is moved, and the light source 24 in FIG. 2 is moved to the gloss detection position, which is an irradiation position where halation is caused by the light applied to the image reading surface (the back side of the document) (S11).

  Next, when the document P is conveyed, the image reading surface (back surface) of the document P is curved in the sub-scanning direction of image reading with respect to the light irradiated from the light source 24 by the curved background plate 60 shown in FIG. Therefore, when the original P is irradiated with light in this state, the specular reflection component is strongly generated in the glossy area of the image reading surface, and the back side image data (back side halation image data) in a state of causing halation is generated. Obtain (S12).

Next, after reading the image reading surface on the back side of the document P, the light source 24 in FIG. 2 is turned off (S13).
Then, the back side of the original P is normally read by the CIS 15 arranged on the downstream side in the conveyance direction of the original P shown in FIG. 2, and the image data (normal image data) is acquired (S14). The image data acquired by the CIS 15 is an image in a normal state in which no halation has occurred.
Thereafter, glossy area identification processing is executed (S15).

Next, the gloss area identification process will be described.
The image data acquired in each of the above steps (S4, S7, S12, S14) is stored in the memory 37 of the gloss detecting unit 35 shown in FIG. Using the front side halation image data and the front side normal image data, and for detecting the glossy area on the back side of the document P, the back side halation image data and the back side normal image data are used. The difference calculation unit 36 performs calculation processing, and detects a glossy region based on the calculation processing result.

Regarding the contents of the above arithmetic processing, for example, the image of the original P shown in FIG. 6A includes an image of a gloss application portion (glossy pattern) indicated by a dotted line frame portion in the drawing, n, m) are the pixel positions of the nth pixel in the main scanning direction and the mth line in the subscanning direction on the document P.
Further, D (n, m) of the original P shown in FIG. 6B is read by the CCD 30 when read by the CIS 15 of FIG. 2 or at a position where the light L of the light source 24 is irradiated to the normal reading position. The reflected light level is shown.

Further, H (n, m) of the original P shown in FIG. 6C indicates the reflected light level when the CCD 30 reads the light L from the light source 24 at the position where the gloss detection position is irradiated. In this case, the image reading surface of the original P has halation, and the gloss application portion is glossy.
In addition, the calculation result of (D (n, m) + P0 (n, m)) − H (n, m) is set to P (n, m) as a linearity difference value P0 (D (n, m)) described later. .

  Here, P0 (D (n, m)) is a level difference caused by the difference in the optical system between the image acquired by the CIS 15 and the image acquired at the gloss detection position. At a manufacturing or process stage, a specific gray scale chart (non-gloss) is read at the gloss detection position, and a read image at the CIS 15 and a read image at the gloss detection position are acquired. As shown by the approximate straight line and the approximate straight line of the gloss detection position read image linearity, each output value at each specific reflectance (for example, 20 points) and information on the approximate straight line are stored in the memory 37 of FIG. Keep it.

In the information of the approximate straight line of these linearities, for example, the difference value at the reflectance (pixel level) X includes the image obtained by reading the same reflectance (pixel level) X by the CIS 15 and the CCD 30 in the gloss detection position plane. A level change P0 (X) is caused by a difference corresponding to a difference between the original optical system and an image read by the reduction optical system, or by floating from the reading surface due to bending.
That is, the above (D (n, m) + P0 (n, m)) is a halation when the reflected light level D (n, m) of a certain part of the original P read by the CIS 15 is read at the gloss detection position. This is a predicted value of the reflected light level in a state where no occurrence occurs.

The difference between the predicted value (D (n, m) + P0 (n, m)) and the reflected light level H (n, m) of the image portion actually read at the gloss detection position, (D When (n, m) + P0 (n, m)) − H (n, m) becomes almost zero, it can be determined that no halation has occurred.
Further, since the glossy portion is subjected to a level change due to halation in addition to P0 (D (n, m)) which is a difference in the optical system, a difference (D (n, m) + P0 (n, m)) − H ( n, m) is not 0 but has a specific value.

When this specific value is greater than or equal to α × D (n, m), it is determined that a level change due to halation of the glossy part is added, and the pixel of (n, m) is determined as a glossy pixel, Set glossy pixel to 1.
On the other hand, if the specific value is not greater than α × D (n, m), it is determined that it is not a level change due to halation, but simply due to a difference in the optical system, and non-glossy pixels are set to 0 and binarization processing is performed. Do.

That is, α × D (n, m) is the minimum value of the level change amount due to the occurrence of halation with respect to the reflected light level D (n, m), and α is a correction coefficient determined according to the degree of halation. Design in advance so that gloss is not erroneously detected.
Therefore, the calculation result after the binarization process can identify a glossy area and a non-glossy area in G (n, m) in the image of the document P shown in FIG.
If the amount of data is enormous when saving to the memory 37 when acquiring an image and it takes a long time to save or calculate, the compression processing or the like may be performed as long as the accuracy of the detection does not drop.

Further, since the image reading surface of the original P is bent when reading the image at the gloss detection position, the acquired halation image has a wider RGB line interval of the CCD 30 than the normal image.
Therefore, the gloss detection unit 35 applies the readout timing of the inter-line correction according to the bending in advance to the halation image instead of the normal readout timing of the inter-line correction, and performs the arithmetic processing.

The read timing is determined at the design stage in the same way as the halation occurrence position because the line interval that spreads varies depending on the optical system and shape of the automatic document feeder and the configuration of the CCD 30.
In this way, the CPU 38 outputs the result of the gloss area information detected by the gloss detector 35 in the form of an image or a table of its position information and the like according to the application.

Next, expressions used for the above calculation are listed.
P (n, m) = (H (n, m) + P0 (D (n, m))-D (n, m)
P (n, m): Value after calculating the difference in reflected light level between the n-th pixel in the main scanning direction and the m-th pixel in the sub-scanning direction of image reading

D (n, m): Reflected light level (normally read image with no halation) of the nth pixel in the main scanning direction and the mth line in the subscanning direction of image reading
H (n, m): Reflected light level (read image in which halation has occurred) of the nth pixel in the main scanning direction and the mth line in the subscanning direction of image reading
P0 (X): Linearity difference value due to a difference in engineering system at the reflected light level X of a pixel extracted with a dedicated non-gloss chart obtained in advance

When | P (n, m) | ≧ | α × D (n, m) |, G (n, m) = 1 (glossy pixel)
If | P (n, m) | <| α × D (n, m) |, G (n, m) = 0 (non-glossy pixel)
G (n, m): a value indicating the gloss determination result of the n-th pixel in the main scanning direction and the m-th line in the sub-scanning direction of image reading α: a threshold correction coefficient determined according to the degree of halation

Next, it is determined whether or not all the originals have been read (S16). If they have not been read (in the case of N in S16), the process returns to the first process and the above-described processing is repeated. When the detection reading is an object, each original is sequentially conveyed in the same manner as the normal sheet-through plural-sheet original reading, and the glossy area and the non-glossy area are identified.
If it is determined that all the originals have been read (Y in S16), the carriage is returned from the gloss detection position to the home position (S17), and this gloss detection process is terminated.

  Next, in the above-described processing, the image reading apparatus 1 in which both the CIS 15 and the document reversing mechanism 16 are provided in the automatic document conveying apparatus 2 has been described. However, the image reading apparatus in which the automatic document conveying apparatus without the CIS 15 is provided. Can also be implemented.

2, an example in which the CIS 15 and the image reading function by the CIS 15 are not used will be described, and the image reading apparatus 1 provided with the automatic document feeder without the CIS will be described. Instead of an example description.
FIG. 4 is an enlarged view of a peripheral portion including the transport drum 11 and the light source 24 of the image reading apparatus 1 shown in FIG. FIG. 8 is a flowchart showing another gloss detection process performed by the processing unit 32 shown in FIG.

  When gloss detection reading is instructed by a user instruction or automatic start, as shown in FIG. 8, the CPU 38 in FIG. 1 first turns on the light source 24 in FIG. (Indicated by "S" in the figure) 21), the first carriage 23 (described as "carriage" in FIG. 5) 23 in FIG. 2 is moved below the reference white board 21, the reference white board 21 is read, and the image Data (reference white board image data) is acquired (S22).

  Next, as in the normal reading, the carriage is moved to the normal reading position, and the light source 24 in FIG. 2 is moved to the normal reading position that is an irradiation position that does not cause halation by the light irradiated on the image reading surface. The surface is read and image data (normal image data) that does not cause halation is obtained (S23).

  With the conveyance of the document P, the curved background plate 60 shown in FIG. 3 causes the image reading surface (front surface) of the document P to be curved in the sub-scanning direction of image reading with respect to the light emitted from the light source 24. Therefore, if the original P is irradiated with light in this state, the specular reflection component may be strong depending on the irradiation position, causing halation. However, as shown in FIG. If the light L from the light source 24 is irradiated to the normal reading position, the sheet original glass 22 and the original P are read in a parallel state, so that no halation occurs at this position.

After the document P passes, the light source 24 is turned off (S24), and it is determined whether or not only the surface is to be glossy detected (S25).
If only the front side of the document P is not gloss detected (N in S25), it is determined whether or not the back side is read (S37). If it is read (Y in S37), the process proceeds to S28, and if it is not read (S37). In the case of N in S37, the document P is conveyed to the document reversing mechanism 16 in front of the paper discharge port, the front and back surfaces of the document P are reversed by the document reversing mechanism 16 (S38), and the back surface of the document P is read in S21 to S25. Image data that does not cause halation (normal image data) is acquired.

  On the other hand, if only the front surface of the document P is to be glossy (Y in S25), the document P is conveyed to the document reversing mechanism 16 in front of the paper discharge port, and the front and back surfaces of the document P are reversed by the document reversing mechanism 16 (S26). ). At this time, since the original is conveyed only from the back side to the front side, the CPU 38 in FIG. 1 starts the scanner motor so as to increase the speed of the original conveyance within a range in which the original P is not damaged in order to maintain productivity. A control signal is sent to 31 (S27).

  Thereafter, the original P is reversed (S28), and reading on the front surface is performed again, but the light source 24 is turned on (S29) in the same manner as described above, and the first carriage in FIG. 2 (described as “carriage” in FIG. 5). 23) is moved below the reference white plate 21, the reference white plate 21 is read, and its image data (reference white plate image data) is acquired (S30).

  Next, when the carriage is moved to move the light source 24 of FIG. 2 to the gloss detection position, which is an irradiation position where halation is caused by the light applied to the image reading surface (back side of the document), and the document P is conveyed, FIG. The curved background plate 60 shown in FIG. 5 is bent so that the image reading surface (front surface) of the document is curved in the sub-scanning direction of image reading with respect to the light emitted from the light source 24. When the light is irradiated, regular reflection components are strongly produced in the glossy area of the image reading surface, and image data in the state of causing halation (halation image data, in this case, surface halation image data) is acquired (S31).

Next, the light source 24 in FIG. 2 is turned off (S32), and it is determined whether or not only the surface is to be glossy detected (S33).
If only the front side of the document P is not glossy detected (N in S33), it is determined whether or not the back side is read (S39). If it is read (Y in S39), the process proceeds to S34, and if it is not read (S39). In the case of N in S39, the document P is conveyed to the document reversing mechanism 16 in front of the paper discharge port, the front and back surfaces of the document P are reversed by the document reversing mechanism 16 (S40), and the back surface of the document P is read in S29 to S33. Image data that has caused halation (halation image data, in this case, halation image data on the back surface) is acquired.

  On the other hand, if only the front side of the document P is glossy detected (Y in S33), or if the image on the back side is read (Y in S39), a glossy area identification process is executed (S34). Since this glossy area identification process is the same as described above, its description is omitted here.

  In the glossy area identification process here, a specific gray scale chart (non-gloss chart) is read in advance by the gloss detection reading at the stage of manufacturing or the process of the image reading apparatus, and is read at the normal reading position. The image and the read image at the gloss detection position are acquired, and each output value at each specific reflectance (20 points in the figure) is stored in the memory 37 of the gloss detection unit 35 as shown in FIG. .

  Next, it is determined whether or not all the originals have been read (S35). If they have not been read (N in S35), the above processing is repeated after returning to the beginning, and if read (if Y in S35), The carriage is returned from the gloss detection position to the home position (S36), and this gloss detection process is terminated.

  Since the document reversing operation is increased in this way, the productivity is inferior to that of the automatic document conveying apparatus provided with both the CIS 15 and the document reversing mechanism 16, but the automatic document conveying apparatus without the CIS is also performed once. The glossy region can be identified by automatically reading a plurality of times in the job.

In the image forming apparatus of this embodiment, the image reading apparatus can correctly extract a pattern created with or without gloss with the current mechanical configuration, while suppressing an increase in the size of the system and an increase in the cost of the apparatus.
In addition, by making the background plate directly above the reading surface during document conveyance a curved surface, it is possible to reliably generate halation on the image by reading the read document in a bent state.

  Furthermore, when a sheet-through document is conveyed on a curved background plate, the carriage is moved to a position where halation occurs, and reading is executed at that position, so that an image when halation occurs can be reliably acquired. it can.

  In addition, in order to identify glossy and non-glossy parts of a document, in addition to the image at the time of halation, a normal read image must be acquired simultaneously for comparison. By acquiring the read image data when halation occurs and the read image data in the normal CIS, the user can acquire two images in one reading job without performing the reading job twice. Can do.

  Furthermore, in order to identify the glossy and non-glossy parts of the document, it is necessary to simultaneously acquire the normal read image in addition to the image at the time of halation occurrence. By acquiring the read image data at the time of occurrence of halation and the read image data in the normal reading on the same document surface once, without the user performing the reading job twice. Two images can be acquired by the reading job.

  In addition, the conventional document transport device temporarily increases the transport speed between document reversal and document scanning. However, when gloss detection is performed only on the surface, the document reversal is performed to transport the document again on the surface. Although the mechanism is operated twice, only the document transport without reading is performed between the first reversal and the second reversal. Therefore, in order to maintain productivity, the document transport speed is increased within a range that does not damage the document. can do.

Further, since the original is read in a bent state at a position farther than normal reading, the RGB line interval on the image becomes longer than that during normal reading.
This line interval is corrected using a normal memory or the like, but when reading when halation occurs, the line shift can be corrected by automatically switching to the correction setting for when halation occurs.

  Further, by calculating the difference between the image at the time of halation occurrence and the normal image, it is possible to detect which portion is a glossy portion by detecting the difference between the time of halation occurrence and the time of normal occurrence, that is, the halation occurrence portion.

  Furthermore, when reading an original with an image reading device and performing a difference calculation, the optical system is different between reading by CIS and reading by a reduction optical system at the gloss detection position, so output characteristics (linearity) with respect to the original original reflectivity. If the above is not taken into consideration for the determination of gloss or non-gloss on the result of the difference calculation for gloss detection, the accuracy of the determination is reduced.

  Therefore, by reading the dedicated non-gloss chart by reading at the CIS and the gloss detection position respectively, the difference in linearity between the optical systems is output and stored in the memory of the gloss detection unit. The accuracy can be increased.

  In addition, when reading an original with an image reader and performing a difference calculation, the optical system is different between reading at the normal reading position and reading at the gloss detection position, so there is a difference in output characteristics (linearity) with respect to the reflectance of the original original. If the above is not taken into consideration for the gloss / non-gloss determination on the result of the difference calculation of the gloss detection, the accuracy of the determination is reduced.

Therefore, by reading the dedicated non-gloss chart at the normal reading position and the reading at the gloss detection position respectively, the difference in linearity in those optical systems is output and stored in the memory of the gloss detection unit, The accuracy of gloss detection can be increased.
Furthermore, the image forming apparatus according to this embodiment includes the image reading apparatus as described above, so that a glossy portion is automatically detected and printing using transparent toner or the like is performed on the portion, digital watermark processing, or the like. Can be implemented.

  The image reading apparatus and the image forming apparatus according to the present invention can also be applied to a facsimile machine, a printer, a copying machine, and a multifunction machine.

1: Image reading device 2: ADF 3: Reading unit 4: Writing unit 10: Pickup roller 11: Conveying drum 12: Conveying roller group 13: Document tray 14: Paper discharge tray 15: CIS 16: Document reversing mechanism 20: Contact Glass 21: Reference white plate 22: Sheet original glass 23: First carriage 24: Light source 25, 27, 28: Mirror 26: Second carriage 29: Lens 30: CCD 31: Scanner motor 32: Processing unit 41: Laser output unit 42: imaging lens 43: mirror 44: photosensitive drum 45: development unit 46: transport belt (transfer belt) 47: fixing unit 48: paper discharge unit 49: duplex transport path 50: vertical transport unit 51: first paper feed Tray 52 The second paper feed tray 53: third paper feed tray 54: first sheet feeding device 55: the second paper feeding device 56: the third sheet feeding device 57: discharge tray

JP 2005-170007 A JP 2001-265181 A Japanese Patent Laid-Open No. 06-070097 JP 2010-102032 A

Claims (11)

While the image reading surface of the document is conveyed in the sub-scanning direction of image reading with respect to the light source, the image reading surface is irradiated with light from the light source and the image of the document is read based on the reflected light from the image reading surface. In the image reading device,
The light source is set to an irradiation position that does not cause halation by the light applied to the image reading surface, an image when no halation occurs from the image reading surface is read, and halation is performed by the light applied to the image reading surface. A reading means for reading an image when halation occurs from the image reading surface at an irradiation position for raising;
An image reading apparatus comprising gloss detecting means for detecting a glossy portion of the document based on both images when the halation read by the reading means occurs and when the halation does not occur.   2. The image reading device according to claim 1, further comprising means for making the image reading surface curved in the sub-scanning direction of image reading with respect to light irradiated from the light source during conveyance of the document. apparatus.   The reading means sets the irradiation position where the halation does not occur as a normal position of the light source, and when reading the image when the halation occurs, the reading means causes the halation by the light irradiated on the image reading surface in advance. 3. The image reading apparatus according to claim 1, further comprising means for moving in a sub-scanning direction of image reading to a set irradiation position.   The reading unit includes a second reading unit that reads an image on the other image reading surface of the document, a document reversing unit that reverses the image reading surface of the document with respect to the second reading unit, and the light source. After reading the image when halation occurs from the image reading surface at the irradiation position where halation is caused by the light irradiated to the image reading surface, the image reversing means is used to reverse the image reading surface of the document, and 4. The image reading apparatus according to claim 1, further comprising means for reading an image when halation does not occur from the image reading surface by the two reading means. 5.   The reading means includes a document reversing means for reversing the image reading surface of the document with respect to the light source, and an irradiation position where halation is caused by the light emitted from the light source to the image reading surface. And a means for reversing the image reading surface of the document by the document reversing means and reading the image when no halation occurs from the image reading surface. The image reading apparatus according to any one of claims 1 to 3.   6. The image reading apparatus according to claim 4, further comprising means for temporarily increasing a document conveying speed when the document is reversed by the document reversing unit.   7. The image reading apparatus according to claim 1, further comprising a correction unit configured to correct a line interval in a sub-scanning direction of image reading for an image when the halation occurs.   The gloss detecting means includes means for detecting, as a glossy part of the document, a part where a difference in reflectance between both images when the halation read by the reading means occurs and when the halation does not occur is a predetermined value or more. The image reading apparatus according to claim 1, wherein the image reading apparatus is an image reading apparatus.   Means for correcting a difference between an output characteristic for the reflectance of the image when the halation read by the reading means occurs and an output characteristic for the reflectance of the image when the halation read by the reading means does not occur; The image reading apparatus according to claim 1, wherein the image reading apparatus is provided.   The difference between the output characteristic with respect to the reflectance of the image when the halation read by the reading unit occurs and the output characteristic with respect to the reflectance of the image when the halation read by the second reading unit does not occur are corrected. 5. The image reading apparatus according to claim 4, further comprising means.   An image forming apparatus comprising the image reading apparatus according to claim 1.