JP2013062645A - Image reading apparatus and image processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent occurrence of inaccurate reading.SOLUTION: In an image reading apparatus which includes a CIS14a for reading an original document P and a white roller 14b for supporting the original document P from the side of a surface to be read at a position facing the CIS14a, and conveys the original document P between the CIS14a and the white roller 14b and reads the original document P, the image reading apparatus includes: supporting an original document that is thicker than a distance D between the white roller 14b and the CIS14a while applying pressure to the CIS14a by the movement of the white roller 14b to an opposite side to the CIS14a against a predetermined force when conveying the original document; obtaining information on glossiness of the original document before the original document P reaches the CIS14a, and adjusting the distance D between the CIS14a and the white roller 14b by the movement of the white roller 14b on the basis of the glossiness; and performing adjustment processing for adjusting the magnitude of such a force as to hold the white roller 14b.

Description

  The present invention relates to an image reading apparatus that reads an image of a document and an image processing apparatus including such an image reading apparatus.

2. Description of the Related Art Conventionally, in an image processing apparatus, an ADF (automatic document feeder) is used to sequentially convey a document placed at a predetermined placement position while separating the documents one by one and read a document image. It has been broken.
When reading both sides of an original image with such an ADF, the image formed on the front side of the original is read by the scanner unit used for reading the original on the contact glass, and the back side of the original It is known that the image formed in the above is read by a color contact image sensor (hereinafter referred to as “CIS”) in which the light source, the lens, and the image sensor are integrated in the ADF of the image reading apparatus.

In such an image processing apparatus capable of reading both sides, for example, Patent Document 1 discloses a second fixed reading unit and a second fixed reading unit in order to stably run a document in a second fixed reading unit corresponding to CIS. It is disclosed that the distance from the second reading roller at the position facing the fixed reading unit is adjusted.
Japanese Patent Application Laid-Open No. 2004-228620 includes a white reference plate that serves as a white reference at the time of reading an original and presses the original in an image reading apparatus using a contact image sensor unit corresponding to CIS as a reading unit. It is disclosed that the pressing force is adjusted.

  In addition to the above-mentioned Patent Documents 1 and 2 related to CIS, Patent Document 3 discloses that an original is irradiated with light from a light source while changing an irradiation position in order to efficiently acquire a glossy amount. It is disclosed that a regular reflection component of reflected light from the light is received by an image sensor and subjected to photoelectric conversion.

By the way, the above-mentioned CIS is an equal magnification reading unit fixed inside the ADF, and has a shallow depth of field as compared with the scanner unit of the reduction optical system. Therefore, when reading a document in order to prevent out-of-focus, etc. It is desirable to read the original while making contact with the glass surface of the CIS.
However, there is a known problem that uneven reading occurs when glossy paper is read as a document read by CIS.

  This problem will be described with reference to FIG. FIGS. 14A and 14B are schematic diagrams showing the light trajectories when reading plain paper and glossy paper using CIS. FIG. 14A shows the case where plain paper Pa is read, and FIG. Each case of reading the paper Pb is shown.

Here, the CIS 500 common to FIGS. 14A and 14B is a unit obtained by unitizing members necessary for image reading, and includes a sensor substrate 501, an image sensor 502, a lens array 503, and light sources 504a and 504b ( Hereinafter, it is simply referred to as “light source 504”) and glass 505.
Note that the CIS 500 is shown with a simple configuration in order to explain the above-described problem, and the actual CIS includes configurations other than those illustrated. In the figure, an arrow indicated by a solid line indicates incident light from the light source 504, and an arrow indicated by a broken line indicates reflected light from the plain paper Pa or glossy paper Pb.

In such a CIS 500, when the plain paper Pa is conveyed by the ADF, the light emitted from the light source 504 is emitted to the plain paper Pa through the glass 505 as shown in FIG. After being diffusely reflected on the paper Pa, a part of the reflected light is collected via the lens array 503 and then received by the image sensor 502.
On the other hand, when the glossy paper Pb is conveyed by the ADF, as shown in FIG. 14B, the light emitted from the light source 504 is applied to the glossy paper Pb through the glass 505, and the glossy paper Pb is irradiated on the glossy paper Pb. A phenomenon occurs in which the light is regularly reflected and the reflected light does not enter the lens array 503.

This is because in the case of glossy paper Pb, the portion that is in close contact with the glass surface is in a mirror state. Actually, it does not reflect specularly as much as a mirror, but there is also diffused light, but since almost no reflected light is incident on the lens array 503, there are some puddles where the glass surface and the glossy paper Pb are in close contact. A blackened spot appears.
This phenomenon is the same principle as when a mirror is placed on the contact glass of a copying machine to make a copy and the part where the mirror is placed becomes black.

On the other hand, depending on the angle at which the glossy paper Pb contacts the glass surface, the specularly reflected light is incident on the lens array 503 as it is, so that the charge stored in the image sensor 502 becomes higher than the surroundings and appears whitish. The background is white, so the difference is difficult to understand.
However, when the background is black, the part where the specular reflection light is incident becomes white, and white spots appear in some places.

As described above, when the glossy paper Pb is read by the CIS, there is a problem that uneven reading occurs. For example, when the glossiness is high, such as photographic paper, and thick paper, the photographic paper is often pressed against the glass surface, and reading unevenness is likely to occur.
In this regard, Patent Documents 1 to 3 do not describe means for solving the problem of uneven reading.

  An object of the present invention is to solve such problems and prevent reading unevenness that may occur when reading glossy paper in an image reading apparatus that reads an image of a document.

  In order to achieve the above object, an image reading apparatus according to the present invention includes a reading unit that reads an image of a document, a support unit that supports the document from the non-reading surface side at a position facing the reading unit, and transports the document. An image reading apparatus that conveys the original document between the reading unit and the support unit by the conveyance unit, and reads an image of the original. The support unit includes the reading unit. Means for supporting the original while applying pressure toward the reading means by moving to a side opposite to the reading means against a predetermined force when conveying an original thicker than And a glossiness information acquisition means for acquiring the glossiness information of the document before the document reaches the reading means, and the support means is moved based on the glossiness acquired by the glossiness information acquisition means. Allowed by and performs adjustment processing for adjusting the size of the predetermined force while adjusting the distance between said reading means and said support means.

  According to the image reading apparatus of the present invention as described above, it is possible to prevent reading unevenness that may occur when reading glossy paper in an image reading apparatus that reads an image of a document.

1 is a cross-sectional view illustrating a schematic configuration of an image processing apparatus according to a first embodiment of the present invention. It is a figure which shows schematic structure of the image reading apparatus with which the image processing apparatus shown in FIG. 1 is provided. FIG. 3 is an enlarged view of a paper thickness measuring unit shown in FIG. 2. FIG. 3 is an enlarged view of a glossiness measurement unit shown in FIG. 2. FIG. 3 is an enlarged view of a back surface reading unit illustrated in FIG. 2. FIG. 3 is a diagram for explaining a document conveyance mechanism in a back surface reading unit illustrated in FIG. 2. FIG. 3 is a block diagram of a hardware configuration of a control system of the image reading apparatus shown in FIG. 2. FIG. 8 is a more detailed circuit diagram of the comparator shown in FIG. 7. It is the flowchart which showed the adjustment process which a control part performs when performing double-sided reading in 1st Embodiment.

It is a figure which shows the structure of the back surface reading part in 2nd Embodiment. FIG. 10 is a flowchart illustrating an adjustment process corresponding to FIG. 9 executed by the control unit when performing double-sided reading in the second embodiment. It is a figure which shows the structure of the back surface reading part in 3rd Embodiment. FIG. 10 is a flowchart illustrating an adjustment process corresponding to FIG. 9 executed by a control unit when performing double-sided reading in the third embodiment. It is the schematic diagram which showed the locus | trajectory of each light, when reading plain paper and reading glossy paper using CIS.

[First Embodiment]
Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
First, a schematic configuration of an image processing apparatus according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view showing a schematic configuration of the image processing apparatus.

In FIG. 1, the image processing apparatus 100 is a digital multi-function peripheral (MFP) having functions such as copying, scanning, facsimile communication, and document storage, and includes an image reading apparatus 10 that is an image reading section and a main body section 50. ing. In the figure, R indicated by a broken line indicates an optical path of reflected light from the original, and L indicates an optical path of laser light for writing.
Among these, the image reading apparatus 10 is an image reading apparatus capable of automatically conveying a document and reading images formed on both sides of the document. The detailed configuration of the image reading apparatus 10 will be described later.

The main body 50 includes a paper feed unit 51, a transport unit 52, a registration roller 53, an image forming unit 54, a writing unit 55, a transport belt 56, a fixing unit 57, a paper discharge unit 58, and a paper discharge tray 59.
Among these, the paper feed unit 51 is composed of three paper feed units provided in each of the three trays, and the uppermost document among the documents stacked on each tray is fed by any one of the paper feed units. A sheet feeding unit that feeds out one sheet and feeds the sheet to the transport unit 52.

The transport unit 52 includes a plurality of transport rollers and a guide plate (not shown), and is transport means for transporting the document fed from the paper feed unit 51 to the registration rollers 53.
The registration roller 53 performs skew correction by once abutting and stopping the document transported by the transport unit 52, and the skew-corrected document is placed between the photosensitive drum of the image forming unit 54 and the transport belt 56. This is a roller for feeding the toner image developed on the photosensitive drum to the nip portion at the timing when the toner image comes.

The image forming unit 54 includes a photosensitive drum, a charger for charging the surface of the photosensitive drum to a predetermined potential, a developing unit for developing a toner image on the electrostatic latent image formed by the writing unit 55, and the like. As an integrated image forming means.
The writing unit 55 irradiates and exposes the charged photosensitive drum surface with a laser beam L corresponding to the image information read by the image reading apparatus 10, thereby forming an electrostatic latent image on the photosensitive drum surface. belongs to.

The conveyance belt 56 rotates at the same speed as the photosensitive drum, and conveys the original after transferring the toner image to the fixing unit 57.
The fixing unit 57 includes a fixing roller and a pressure roller, and is a fixing unit that fixes unfixed toner on the document by heating and pressing the document conveyed by the conveyance belt 56.
The paper discharge unit 58 is a paper discharge means for guiding the document after fixing to the paper discharge tray 59. The paper discharge tray 59 is for stacking and holding the discharged documents.

In the image processing apparatus 100 as described above, when an image is formed on a document, first, one document on the uppermost surface among the documents stacked on one of the trays is fed by the paper feed unit 51, and the transport unit. 52 is conveyed to a position in contact with the registration roller 53.
On the other hand, the image information read by the image reading device 10 is written on the photosensitive drum by the laser light L from the writing unit 55, and a toner image is formed by passing through the developing unit.

The original is conveyed by a registration roller at the timing when the developed toner image reaches the transfer position, and is conveyed by a conveyance belt 56 that rotates at the same speed as the rotation of the photosensitive drum. The image is transferred to the original.
Thereafter, the unfixed toner is fixed by the fixing unit 57 and discharged to the discharge tray 59 by the discharge unit 58.

Next, a detailed configuration of the image reading apparatus 10 according to the first embodiment of the present invention will be described with reference to FIG. FIG. 2 is a diagram showing a schematic configuration of the image reading apparatus 10.
In FIG. 2, the image reading apparatus 10 includes an automatic document feeder (ADF) 11, a paper thickness measuring unit 12, a glossiness measuring unit 13, a back surface reading unit 14, a front surface reading window 15, a contact glass 16, a reference. A white plate 17, a first carriage 18, a second carriage 19, a lens unit 20, and a CCD 21 are provided.

Note that R indicated by a broken line in the drawing indicates an optical path of reflected light from the document.
In addition, P indicated by a two-dot chain line in the drawing is a document, and the document here may be of any material and thickness including the plain paper Pa and the glossy paper Pb described in the problem section. When it is not necessary to specify and explain the thickness, the document P is assumed to be described.

Among them, the ADF 11 is a conveying means for automatically feeding and conveying the documents P placed on the document table one by one automatically.
The paper thickness measuring unit 12 is a paper thickness measuring unit that measures the thickness of the document P using two opposing rollers. The detailed configuration of the paper thickness measuring unit 12 will be described later.
The gloss measurement unit 13 is a gloss measurement unit that measures the gloss of the document P. The detailed configuration of the gloss measurement unit 13 will also be described later.

The back side reading unit 14 is for optically reading an image formed on the back side of the document P. The detailed configuration of the back side reading unit 14 will also be described later.
The front surface reading window 15 is a window provided at a reading position for reading an image formed on the front surface of the document P automatically conveyed by the ADF 11, and is a member through which light passes (for example, glass ), The original P is irradiated with the light emitted from the light source 18a, and the reflected light from the original P can be incident on the first reflecting mirror 18b.
The contact glass 16 is used to place the document P when the document is read without using the ADF 11.
The reference white plate 17 is a reference member that is read prior to reading the document P in order to generate shading data for performing shading correction on the read image.

The first carriage 18 includes a light source 18a for document exposure and a first reflecting mirror 18b. The first carriage 18 is driven by a stepping motor (not shown) to feed the document P placed on the contact glass 16 in the direction indicated by arrow A (sub-scanning). Optical scanning while moving in the direction). Further, it can be used for reading an image of the document P automatically stopped by the ADF 11 after stopping at the reading position of the front surface reading window 15.
In addition, as a light source, well-known illumination means, such as LED, a fluorescent lamp, or a xenon lamp, can be used.

The second carriage 19 includes a second reflecting mirror 19a and a third reflecting mirror 19b. The second carriage 19 is driven by a stepping motor (not shown) similarly to the first carriage 18, and follows the first carriage 18 in the direction of arrow A. To move on.
The lens unit 20 is for focusing the reflected light sequentially reflected and deflected from the first reflecting mirror 18b to the third reflecting mirror 19b on the CCD 21 to form an image.
The CCD 21 is a one-dimensional line image sensor that photoelectrically converts the collected reflected light into an analog electric signal.

In such an image reading apparatus 10, when reading an image of the document P placed on the contact glass 16, the light source 18 a is turned on, and the first carriage 18 and the second carriage 19 are moved to the right by a stepping motor (not shown). Scan the original P.
On the other hand, when reading both sides of the document P conveyed by the ADF 11, the light source 18 a is turned on, and the first carriage 18 is on standby in a state where it is stopped at the reading position of the surface reading window 15.

Then, by guiding the document P in the direction of arrow B by the plurality of rollers of the ADF 11, the front surface of the document P is scanned at the reading position of the front surface reading window 15 and formed on the front surface. Read the image.
The image formed on the back side of the document P is read by the back side reading unit 14.
In this way, the images formed on both sides of the document are read.

Next, a detailed configuration of the paper thickness measuring unit 12 will be described with reference to FIG. FIG. 3 is an enlarged view of the paper thickness measuring unit 12 shown in FIG.
As shown in FIG. 3, the paper thickness measuring unit 12 includes a pull-out roller 12a, a pull-out driven roller 12b, a rotating shaft 12c, a support mechanism 12d, and a displacement sensor 12e.

Among these, the pull-out roller 12a and the pull-out driven roller 12b perform skew correction by aligning the leading end of the document P by bending and pressing the leading end of the document P against the nip portion when the document P enters, and after skew correction. The original P is conveyed to a roller located downstream.
The rotating shaft 12c is a rotating shaft that protrudes from both ends in the longitudinal direction of the pull-out driven roller 12b.

The support mechanism 12d includes an upper bar inserted into the protruding portion of the rotating shaft 12c, a lower bar fixed at a position facing the upper bar, and an upper bar and a lower bar. It consists of a connecting spring. Among these, the upper bar is configured to be movable in the direction of the arrow by the fixed lower bar and the spring, and the rotary shaft 12c and the pull-out driven roller 12b are also moved in the direction of the arrow in accordance with this movement. It can be moved to.
The displacement sensor 12e is a sensor for detecting the thickness of the original P by detecting the amount of displacement of the spring.

In such a paper thickness measurement unit 12, first, skew correction of the document P is performed by the nip portion between the pull-out roller 12a and the pull-out driven roller 12b. Thereafter, when the document P enters, the pull-out driven roller 12b and the rotary shaft 12c are moved. Then, it moves in the direction of the arrow by a distance corresponding to the thickness of the original P.
Then, the spring of the support mechanism 12d contracts and the displacement amount is detected by the displacement sensor 12e, whereby the paper thickness of the document P can be measured.

Next, the detailed configuration of the glossiness measurement unit 13 will be described with reference to FIG. FIG. 4 is an enlarged view of the glossiness measurement unit 13 shown in FIG. In the figure, solid line arrows indicate irradiation light from the light source 13b, and broken line arrows indicate reflection light from the document P.
As shown in FIG. 4, the gloss measuring unit 13 includes a gloss meter 13a, and the gloss meter 13a includes a light source 13b and a light receiving sensor 13c.

Then, when measuring the glossiness of the document P, light is emitted from the light source 13b, the ratio of the regular reflection light to the irradiated light is measured, and the glossiness of the document P is measured. Thus, for example, it is possible to determine that the paper is plain paper Pa if the ratio of specular reflection light is low, and to determine that the paper is glossy paper Pb if the ratio of specular reflection light is high.
In consideration of the fact that the original P is waved and conveyed to some extent, the light receiving surface of the light receiving sensor 13c is preferably made somewhat large. The gloss meter 13a may be simple and may be replaced by another sensor built in the ADF 11 as long as the ratio of the regular reflection light to the irradiation light can be measured.

Next, a detailed configuration of the back surface reading unit 14 will be described with reference to FIG. FIG. 5 is an enlarged view of the back surface reading unit 14 shown in FIG.
As shown in FIG. 5, the back surface reading unit 14 includes a color CIS 14a and a white roller 14b. In addition, although there are two each of the light source 14e, the white tape 14f, and the condensing lens 14g shown in FIG. 5, since it is the same member arrange | positioned left-right symmetrically, it shows with the same code | symbol. D is the distance between the CIS 14a and the white roller 14b.

The CIS 14a is an equal magnification reading sensor in which various members necessary for image reading are integrated, and includes a glass 14c, a lens array 14d, a light source 14e, a white tape 14f, a condensing lens 14g, an image sensor 14h, a sensor substrate 14i, A signal processing board 14j and an aluminum die cast 14k are provided.
Among these, the glass 14c is a transmissive member serving as a reading surface when reading an image formed on the back surface of the document P being conveyed.

The lens array 14d is a cylindrical lens that collects the reflected light of the light emitted from the light source 14e and forms an image on the image sensor 14h.
The light source 14e is for irradiating light to the back surface of the conveyed document P.
The white tape 14f is a reflecting material for reflecting the light emitted from the light source 14e to the side opposite to the original P and efficiently applying the light to the original P.
The condensing lens 14g is a lens that condenses the light emitted from the light source 14e and efficiently applies the light to the document P.
The image sensor 14h is a one-dimensional line-shaped image sensor that photoelectrically converts collected light into an analog electric signal.

The sensor substrate 14i is a substrate for mounting the image sensor 14h.
The signal processing board 14j is a board on which a signal processing circuit that performs various kinds of signal processing on the analog electric signal obtained from the image sensor 14h is mounted.
The aluminum die cast 14k is a housing for housing the various members described above.
The white roller 14b supports the original P from the non-reading surface side (front surface side) when reading the original P, and before reading the original P, the white roller 14b is read by the CIS 14a to generate shading data. Is. The white roller 14b corresponds to a support unit.

  The white roller 14b includes an unillustrated distance adjusting mechanism for adjusting the distance D from the CIS 14a, and an unillustrated elastic force adjusting mechanism capable of adjusting the elastic force of the white roller 14b. Is attached. These mechanisms will be described later.

In such a back side reading unit 14, since the depth of field of the CIS 14a is shallow, in order to prevent blurring when reading the document P, in principle, it is preferable to read while contacting the reading surface of the glass 14c. Considering this, it is conceivable that the interval D is set to an interval that allows the plain paper Pa to pass.
For example, when the plain paper Pa has a thickness of 0.08 mm, it is conceivable that the interval D is set to the same or a margin with a little margin so that it can be read while being in contact with the glass 14c. .

Here, when thick paper having a thickness of, for example, 0.1 mm thicker than the distance D has been conveyed, the white roller 14b has elasticity, so that it moves in the direction of the arrow a in the drawing while conversely, For thick paper, reading is performed while applying pressure in the direction of arrow b to bring it into contact with the glass surface.
However, in the case of photographic printing paper or the like, since it is thicker and glossy than ordinary cardboard, even if it can pass through the distance D due to the elasticity of the white roller 14b, it is strongly pressed against the glass 14c. As a result, uneven reading occurs as described in the problem section.

Next, the above-described distance adjustment and elastic force adjustment mechanisms for solving the problem of uneven reading will be described with reference to FIG. FIG. 6 is a diagram for explaining the document conveying mechanism in the back surface reading unit 14.
For convenience of explanation, the CIS 14a in FIG. 6 shows only the portion of the aluminum die cast 14k that is a casing.
First, in the back surface reading unit 14, an upper guide plate 31 and a lower guide plate 32 are provided at the entrance of the document P so that the document P is smoothly guided to the interval D.

Further, the white roller 14b is provided with a mechanism for performing the above-described interval adjustment and elastic force adjustment. The mechanism for performing the interval adjustment is realized by using, for example, a solenoid 200. .
The solenoid 200 is in a state in which the pin 200a protrudes in a steady state, and one end of the pin 200a (a tip portion indicated by a solid line) is inserted into a shaft protruding from both ends of the white roller 14b as shown in the figure. It is integrated with the bearing 200b.
On the other hand, a projection 200c is provided at the other end of the pin 200a of the solenoid 200 (a tip portion indicated by a broken line), and the projection 200c is in contact with a movable stopper 210 indicated by a one-dot chain line.

The movable stopper 210 is configured to be movable in the direction of arrow E by driving the interval adjusting motor 430 (see FIG. 7) in the normal direction, and a protrusion that contacts the movable stopper 210 in conjunction with this movement. The portion 200c also moves in the direction of arrow E, and the pin 200a can be gradually retracted. As the pin 200a is retracted, the white roller 14b is also moved in the direction of the arrow F so that the interval D is increased.
Further, a force is applied to the pin 200a by a spring (not shown) in the opposite direction to the arrow E, and when the movable stopper 210 is moved in the opposite direction to the arrow E, the pin 200a gradually protrudes accordingly. D can be narrowed (returned to the original).
In this embodiment, the interval is adjusted in this way.

The mechanism for adjusting the elastic force is realized by using a spring constant variable spring 300, for example. The spring constant variable spring 300 includes a movable part 300a and a fixed part 300b. The movable portion 300a includes a permanent magnet, one end is fixed to the bar 320, and the other end is not fixed and is inserted into a recess of the fixed portion 300b fixed to the guide plate 310. .
The fixed portion 300b is composed of a pair of coils and a ferromagnetic body (for example, iron) surrounding the pair of coils. When the movable portion 300a is inserted as shown in the figure, the permanent magnet of the movable portion 300a. Holds the state in the figure by attracting the ferromagnetic material.

The holding force to be held can be regarded as an elastic force, and the steady state in the figure is held unless a force is applied. Even if a force is applied in the direction of the arrow G, the elastic force works in the direction opposite to the direction of the arrow G to try to maintain the original fixed position.
In order to weaken this elastic force, the magnetic flux (broken arrow in the figure) is canceled by energizing the pair of coils of the fixed portion 300b, and the spring constant of the magnetic spring is lowered to weaken the elastic force. As a result, the elastic force applied to the shaft of the white roller 14b fixed to one end of the bar 320 can be reduced, and the elastic force of the white roller 14b itself can be reduced. Such a configuration is called a magnetic spring.

Here, for example, when a paper thicker than the interval D is conveyed in a state where the coil of the fixed portion 300b is energized, the white roller 14b is pushed up by the thick paper and a force is applied in the arrow G direction. Since the elastic force acting in the opposite direction is weak, the pressure applied to the thick paper is also reduced.
In this embodiment, the elastic force is adjusted in this way, and the pressure applied to the paper is adjusted.

  In a state where paper thicker than the interval D is being conveyed, the pin 200a of the solenoid 200 can move slightly in the direction of the arrow E without using the movable stopper 210. A slight gap is formed between 200c and the movable stopper 210. The gap is filled with the elastic force of the spring constant variable spring 300 after the thick paper passes. This relationship is the same even when a thicker paper than the widened interval is conveyed in the state after the interval D is widened using the movable stopper 210.

A technique for adjusting the elastic force using the spring constant variable spring 300 is described in, for example, Patent Document 4.
The above-described mechanism using the solenoid 200 for adjusting the distance is only an example, and it is needless to say that the distance may be adjusted by a combination of other known mechanical members. In addition, the configuration including the movable portion 300a and the fixed portion 300b using the spring constant variable spring 300 for adjusting the elastic force is an example, and the elastic force adjustment is performed by the spring constant variable spring using another configuration. Of course it is good.
The interval adjustment and the elastic force adjustment as described above will be collectively referred to as an adjustment process hereinafter unless there is a particular need to distinguish between both.

Next, the hardware configuration of the control system of the image reading apparatus 10 will be described with reference to FIG. FIG. 7 is a block diagram of a hardware configuration of the image reading apparatus 10 shown in FIG.
As shown in FIG. 7, the image reading apparatus 10 includes a control unit 400, an operation unit 410, a storage unit 420, an interval adjustment motor 430, a spring constant control switch 440, comparators 450a and 450b, a displacement sensor 12e, and a light receiving sensor 13c. ing.

Note that the displacement sensor 12e of the paper thickness measurement unit 12 and the light receiving sensor 13c of the gloss measurement unit 13 are as described above, and thus description thereof is omitted.
In addition, the hardware configuration shown in the figure is centered on the hardware configuration related to the invention of the present application. Apart from this configuration, a motor group and various sensors for rotating various rollers of the ADF 11 A group is also provided separately.

First, the control unit 400 controls various hardware (a sensor group, a motor group, and the like) provided in the image reading apparatus 10 with the CPU as a core, and controls image data obtained by conveying the document P, reading the image, and reading the image. Processing for realizing functions such as correction is performed.
The control unit 400 also includes storage means such as a ROM that stores programs and data for executing the above processing, and a RAM that serves as a work area for developing and executing the programs.

The operation unit 410 includes a display unit such as a liquid crystal display, and a touch panel or buttons. The operation unit 410 notifies the user of the state of the image reading apparatus 10 on a screen display, or executes single-sided reading or double-sided reading from the user. An operation such as an instruction is accepted.
The storage unit 420 is an image memory for storing the image data of the front surface read by the CCD 21 and the image data of the back surface read by the back surface reading unit 14.
The interval adjusting motor 430 is an interval adjusting motor for moving the movable stopper 210 in the direction of arrow E by forward rotation and moving the movable stopper 210 in the direction opposite to the direction of arrow E by reverse rotation.

The spring constant control switch 440 is a switch for changing the spring constant of the spring constant variable spring 300, and controls on / off of energization to the pair of coils of the fixed portion 300b. The spring constant control switch 440 is off in a steady state, and is turned on to lower the spring constant of the movable portion 300a, thereby reducing the elastic force of the white roller 14.
The comparator 450 is a comparator provided for each of glossiness and paper thickness, and includes a threshold value set by the control unit 400, a paper thickness obtained from the displacement sensor 12e and the light receiving sensor 13c, and This is for comparing the glossiness and outputting High or Low.

A usage example of the comparator 450 will be specifically described with reference to the circuit diagram of FIG.
As shown in FIG. 8, the comparator 450 includes a glossiness comparator 450a and a paper thickness comparator 450b, each having two inputs and one output. A glossiness threshold value is input from the control unit 400 to one input of the glossiness comparator 450a, and a glossiness measurement value measured by the light receiving sensor 13c is input to the other input.

Then, the glossiness comparator 450a binarizes whether the glossiness measurement value is High or Low with respect to the glossiness threshold value and outputs it.
In this case, for example, if the glossiness measurement value is High with respect to the glossiness threshold, the control unit 400 determines that the document being conveyed needs to be prevented from being in close contact with the CIS 14a because of the high glossiness, and the interval adjustment motor The adjustment processing is performed by controlling 430 and the spring constant control switch 440.

However, similarly, the paper thickness comparator 450b performs comparison by inputting the paper thickness threshold value and the paper thickness measurement value. Finally, referring to the paper thickness determination result, the interval adjustment motor 430 or the spring constant control switch 440 is controlled to perform the adjustment process.
As described above, in the image reading apparatus 10 described with reference to FIGS. 2 to 8, the characteristic points are the paper thickness measured by the displacement sensor 12e of the paper thickness measuring unit 12, and the light receiving sensor 13c of the gloss measuring unit 13. This is an adjustment process performed based on the glossiness measured in (1). Therefore, the adjustment process executed by the control unit 400 will be described below with reference to FIG.

FIG. 9 is a flowchart illustrating an adjustment process executed by the control unit 400 when performing duplex reading. This adjustment process is executed by the CPU of the control unit 400, but will be described as being performed by the control unit 400 for convenience of explanation.
In the image reading apparatus 10, when the user instructs double-sided reading using a touch panel or the like (not shown) of the operation unit 410 with the document P set, the control unit 400 starts the process illustrated in FIG. 9.

First, the control unit 400 sets the glossiness threshold value and the paper thickness threshold value input to the comparators 450a and 450b to appropriate values (S101), and starts document conveyance (S102). Then, the paper thickness of the original P measured by the displacement sensor 12e of the paper thickness measuring unit 12 is acquired (S103), and the glossiness of the original P measured by the light receiving sensor 13c of the glossiness measuring unit 13 is acquired (S104).
Then, the control unit 400 inputs the paper thickness and glossiness acquired in S103 and S104 to the comparators 450a and 450b as measured values, respectively (S105).
Then, the control unit 400 determines whether or not the glossiness measurement value exceeds the glossiness threshold (S106). Here, this determination can be made based on whether or not the output value of the glossiness comparator 450a is High (the measured glossiness value is larger than the glossiness threshold value).

If it is determined in step S106 that the measured glossiness value exceeds the glossiness threshold value (Yes in S106), the control unit 400 determines that it is necessary to prevent document adhesion in the CIS 14a. Then, the process proceeds to step S107.
In step S107, it is determined whether the paper thickness measurement value exceeds the paper thickness threshold value. Here, this determination can be made based on whether or not the output value of the paper thickness comparator 450b is High (the measured paper thickness value is larger than the paper thickness threshold value).

When the control unit 400 determines in step S107 that the measured paper thickness value exceeds the paper thickness threshold value (Yes in S107), the control unit 400 determines that it is necessary to prevent document adhesion in the CIS 14a. Proceed to step S108.
In step S108, the control unit 400 drives the interval adjustment motor 430 to rotate forward and turns on the spring constant control switch 440 before the document P enters the back side reading unit 14.

As a result, the pin 200a of the solenoid 200 is retracted and the white roller 14b is moved to increase the interval D, and the pair of coils in the fixed portion 300b of the spring constant variable spring 300 is energized to reduce the elastic force of the white roller 14b.
As described above, in step S108, when it is determined that both the glossiness and the paper thickness exceed the threshold value, an adjustment process for adjusting the interval between the white rollers 14b and the magnitude of the elastic force is performed. It progresses to step S110 after a process.

On the other hand, the control unit 400 determines that the measured gloss value is equal to or lower than the gloss threshold value in the determination in step S106 (No direction in S106), or the measured thickness in the determination in step S107. If it is determined that the value is equal to or less than the threshold value (No in S107), it is determined that it is not necessary to prevent document adhesion in the CIS 14a, and the process proceeds to step S109.
Then, the distance adjustment motor 430 is driven to rotate in the reverse direction, the spring constant control switch 440 is turned off (S109), and the adjustment of returning the distance and the elastic force of the white roller 14b to the initial values is performed, and then the process proceeds to step S110.

Then, in step S110, the control unit 400 determines whether or not there is a next document. If not (Yes in S110), the control unit 400 ends the process. If there is a next original (No direction in S110), the process returns to step S102 to start conveying the next original P (S102).
In the process described above with reference to FIG. 9, when the control unit 400 determines that both the measured glossiness and the paper thickness are equal to or greater than the threshold, the interval between the white rollers 14b is increased and the position of the white roller 14b is maintained. Adjustment processing for reducing the elastic force is performed. As a result, it is possible to smoothly pass the thick glossy paper Pb, which is expected to cause reading unevenness, and to prevent occurrence of reading unevenness.

In the process of FIG. 9, the adjustment process is performed when it is determined that both the measured glossiness and the paper thickness exceed the threshold value. However, the process is not limited to this. For example, it is conceivable to perform adjustment processing when it is determined that the glossiness exceeds a threshold value based on the measured glossiness regardless of the paper thickness.
In this case, although the adjustment process cannot be performed by narrowing down the target to thick glossy paper, there is no particular problem from the viewpoint of preventing occurrence of uneven reading. Furthermore, the processing for setting the paper thickness threshold, the processing for obtaining the paper thickness of the document, the processing for comparing the measured paper thickness with the paper thickness threshold (S103 and S107, etc.) in FIG. In addition, since it is not necessary to use the paper thickness comparator 450b, the circuit can be simplified.

In addition, the glossiness threshold value and the paper thickness threshold value set in step S101 do not necessarily have to be set at the timing when the user issues a double-sided reading instruction. For example, the respective threshold values are preset in the comparators 450a and 450b as defaults. It may be left.
In FIG. 9, as the adjustment process, the interval between the white rollers 14 b and the magnitude of the elastic force are adjusted simultaneously, but it is also conceivable to adjust only one of them. This example will be described in detail in the following second and third embodiments.

[Second Embodiment]
Next, a second embodiment will be described. In the second embodiment, only the interval adjustment processing is performed in the interval adjustment and elastic force adjustment processing of the white rollers 14b performed in the first embodiment.
For this reason, the configuration of the back surface reading unit 14 in the first embodiment and the adjustment process corresponding to the process of FIG. 9 performed by the control unit 400 are slightly different, but the other processes are the same. This will be described with reference to FIG.

First, the configuration of the back surface reading unit 14 'in the second embodiment will be described. FIG. 10 is a diagram showing the configuration. In addition, in the back surface reading part 14 'in 2nd Embodiment, the same code | symbol is attached | subjected to the same structure as the back surface reading part 14 of 1st Embodiment.
The back surface reading unit 14 'is specialized for adjusting the distance D. Therefore, the mechanism using the solenoid 200 for adjusting the distance is the same as that of the first embodiment. The difference is that the spring constant variable spring 300 is normal. The only point is the spring 300 '. Similar to the first embodiment, the distance D can be widened by the movable stopper 210 of the solenoid 200 of the back surface reading unit 14 '.
Although the spring constant cannot be varied by providing the normal spring 300 ', the white roller 14b is given an elastic force.

Next, adjustment processing performed by the control unit 400 in the second embodiment will be described. FIG. 11 is a flowchart illustrating an adjustment process corresponding to FIG. 9 executed by the control unit 400 when performing duplex reading.
Note that the adjustment processing in the second embodiment only performs interval adjustment, and the processing from step S201 to S207 is the same as the processing from step S101 to S107 in FIG. explain.
In the image reading apparatus 10, when the user instructs double-sided reading with a touch panel (not shown) of the operation unit 410 in a state where the document P is set, the control unit 400 starts the process illustrated in FIG. 11.

First, the control unit 400 sequentially performs the processing from step S201 to S207, and as a result, when it is determined that both the glossiness and the paper thickness exceed the threshold for the conveyed document P (Yes direction in S207). ), The interval adjustment motor 430 is driven to rotate forward as an adjustment process (S208).
As a result, the pin 200a of the solenoid 200 of the back surface reading unit 14 'shown in FIG. 10 is retracted, the white roller 14b is moved in the direction of arrow F, and the interval D is widened. After this adjustment process, the process proceeds to step S210.

On the other hand, when the control unit 400 determines that either the glossiness of the document P or the paper thickness is equal to or less than the threshold (No in S206 or S207), the process proceeds to step S209. Then, the interval adjustment motor 430 is driven in reverse (S209) to adjust the interval between the white rollers 14b to the initial value, and then the process proceeds to step S210.
In step S210, the control unit 400 determines whether or not there is a next document. If there is no next document (Yes direction in S210), the control unit 400 ends the process. If there is a next document (No in S210), the process returns to step S202 to start the next document conveyance.

In the processing described with reference to FIG. 11, when the control unit 400 determines that both the measured glossiness and the paper thickness are equal to or greater than the threshold value, the control unit 400 adjusts the distance D between the CIS 14a and the white roller 14b to be increased. Yes. As a result, occurrence of uneven reading can be suppressed.
Also in the case of the second embodiment, similarly to the first embodiment, adjustment processing for increasing the interval D may be performed when the glossiness exceeds a threshold value without determining the paper thickness.

[Third Embodiment]
Next, a third embodiment will be described. In the third embodiment, only the adjustment processing of the elastic force is performed among the adjustment processing of the interval and the elastic force performed in the first embodiment. For this reason, the configuration of the back surface reading unit 14 in the first embodiment and the adjustment process corresponding to the process of FIG. 9 performed by the control unit 400 are slightly different, but the other processes are the same. This will be described with reference to FIG.

First, the configuration of the back side reading unit 14 ″ in the third embodiment will be described. FIG. 12 is a diagram showing the configuration. In the back side reading unit 14 ″ in the third embodiment, the configuration of the first embodiment is described. The same components as those of the back surface reading unit 14 are denoted by the same reference numerals.
The back surface reading unit 14 ″ is specialized for adjusting the elastic force of the white roller 14b. Therefore, a mechanism using the solenoid 200 for adjusting the interval is not provided, and a spring constant variable spring 300 for adjusting the elastic force is provided. However, a member (not shown) that holds the shaft of the white roller 14b so as to be movable in the direction of the arrow G is provided.

For this reason, in the back surface reading unit 14 ″ in the third embodiment, the interval D in a state where the force is not applied to the white roller 14b (fixed position) cannot be adjusted, but as in the first embodiment, the spring constant variable spring 300 is not adjusted. By energizing the pair of coils in the fixed portion 300b, the elastic force for holding the white roller 14b in its fixed position can be adjusted.
For this reason, when the paper thicker than the space | interval D is conveyed, the pressure given to the paper can be made small.

Next, adjustment processing performed by the control unit 400 in the third embodiment will be described. FIG. 13 is a flowchart illustrating an adjustment process corresponding to FIG. 9 executed by the control unit 400 when performing duplex reading.
Note that the adjustment processing in the third embodiment only adjusts the elastic force, and the processing from step S301 to S307 is the same as the processing from step S101 to S107 in FIG. The explanation is centered.

In the image reading apparatus 10, when the user instructs double-sided reading with a touch panel (not shown) of the operation unit 410 in a state where the document P is set, the control unit 400 starts the process illustrated in FIG. 13.
First, the control unit 400 sequentially performs the processing from step S301 to S307, and as a result, when it is determined that both the glossiness and the paper thickness exceed the threshold (Yes direction in S307), the spring is set as the adjustment processing. The constant control switch 440 is turned on (S308).
Thereby, the spring constant of the spring constant variable spring 300 of the back surface reading unit 14 ″ shown in FIG. 12 is lowered, and the elastic force of the white roller 14b is reduced. After this adjustment process, the process proceeds to step S310.

On the other hand, when the control unit 400 determines that either the glossiness or the paper thickness of the document P is equal to or less than the threshold (No in S306 or S307), the process proceeds to step S309. Then, the spring constant control switch 440 is turned off to adjust the elastic force for holding the white roller 14b to the initial value (S309), and then the process proceeds to step S310.
Then, in step S310, the control unit 400 determines whether there is a next document. If there is no next document (Yes direction in S310), the control unit 400 ends the process. If there is a next original (No direction in S310), the process returns to step S302 to start the next original conveyance.

In the processing described above with reference to FIG. 13, when the control unit 400 determines that both the measured glossiness and the paper thickness are equal to or greater than the threshold value, the pair of coils in the fixing unit 300 b of the spring constant variable spring 300 are energized. Thus, the elastic force of the white roller 14b is reduced.
As a result, the original is not strongly pressed against the glass 14c of the CIS 14a, and the occurrence of uneven reading can be suppressed.
Also in the case of the third embodiment, similarly to the first embodiment, the adjustment process for adjusting the magnitude of the elastic force of the white roller 14b when the glossiness exceeds the threshold without judging the paper thickness. May be performed.

Although the description of the first to third embodiments is finished as described above, the specific configuration of the image reading apparatus 10, the contents of the processing performed by the control unit 400, and the like are not limited to those described in the above-described embodiments. Of course.
For example, in the image reading apparatus 10 according to the first to third embodiments described above, the paper thickness measuring unit 12 is configured by the pull-out roller 12a and the pull-out driven roller 12b. Alternatively, other pairs of rollers may be substituted.
In each of the first to third embodiments, the case where the back surface of the document P is read has been described as an example. However, the adjustment processing in each of the above embodiments is performed when the front surface of the document P is read. It doesn't matter.

In each of the first to third embodiments, the interval and the elastic force of the white roller 14b are adjusted in two steps, ie, whether the glossiness or the paper thickness exceeds the threshold value. Of course, it may be performed in stages.
The glossiness and paper thickness may be divided into three or more stages, and the interval and elastic force corresponding to each stage may be set. The relational expression between the glossiness and paper thickness, the distance and elastic force can be expressed as follows: Based on these relational expressions, the interval to be set and the value of the elastic force may be determined from the glossiness and the paper thickness.

  By performing such multi-stage adjustment, it is possible to prevent occurrence of uneven reading more precisely. If the distance between the white roller 14b and the CIS 14a is too wide, or if the elastic force for holding the position of the white roller 14b is too weak, the document may rise significantly from the reading surface of the CIS 14a and cause blurring. Therefore, it can be said that it is preferable to perform precise adjustments that match the characteristics of the document.

  In the above-described embodiment, an example in which the glossiness and paper thickness of a document are measured each time has been described. However, the glossiness and paper thickness values are acquired by referring to data of registered paper types. May be. For example, values of glossiness and paper thickness are registered in advance for each paper type such as plain paper, thick paper, glossy paper, and photographic paper, and the glossiness and paper thickness corresponding to the paper type selected by the user at the time of reading are registered. For example, adjustment processing is performed using values. It is also conceivable to directly register the spacing and elastic force of the white roller 14b suitable for each paper type, not the glossiness and paper thickness.

Of course, the present invention can be implemented as a single image reading apparatus.
Further, it goes without saying that the configurations of the respective embodiments and modifications described above can be arbitrarily combined and implemented as long as they do not contradict each other.

DESCRIPTION OF SYMBOLS 100: Image processing apparatus 10: Image reading apparatus 11: Automatic document feeder (ADF) 12: Paper thickness measurement part 12a: Pull-out roller 12b: Pull-out driven roller 12c: Rotating shaft 12d: Support mechanism 12e: Displacement sensor 13: Glossiness Measuring unit 13a: Gloss meter 13b: Light source 13c: Light receiving sensor 14: Back side reading unit 14a: CIS
14b: White roller 14c: Glass 14d: Lens array 14e: Light source 14f: White tape 14g: Condensing lens 14h: Image sensor 14i: Sensor substrate 14j: Signal processing substrate 14k: Aluminum die cast 15: Front surface reading window 16 : Contact glass 17: reference white plate 17 18: first carriage 19: second carriage 20: lens unit 21: CCD
31: Upper guide plate 32: Lower guide plate
200: Solenoid 200a: Pin 200b: Bearing 200c: Projection part 210: Movable stopper 300: Spring constant variable spring 300 ': Spring 300a: Movable part 300b: Fixed part 310: Guide plate 320: Bar 400: Control part 410: Operation Unit 420: storage unit 430: interval adjustment motor 440: spring constant control switch 450a, b: comparator
500: CIS 501: sensor substrate 502: image sensor 503: lens array 504a, b: light source 505: glass

JP 2009-21715 A JP 2005-159482 A JP 2010-245917 A JP 2004-360747 A

Claims (5)

A reading unit that reads an image of the document; a support unit that supports the document from the non-reading surface side at a position facing the reading unit; and a transport unit that transports the document. An image reading apparatus that conveys the original between the supporting means and reads an image of the original,
The supporting means moves the document to the side opposite to the reading means against a predetermined force when transporting a document thicker than the distance between the reading means and the pressure toward the reading means. Is a means to support while adding
Glossiness information acquisition means for acquiring glossiness information of the document before the document reaches the reading means;
Based on the glossiness acquired by the glossiness information acquisition unit, the support unit is moved to adjust the distance between the reading unit and the support unit and adjust the magnitude of the predetermined force. An image reading apparatus. A reading unit that reads an image of the document; a support unit that supports the document from the non-reading surface side at a position facing the reading unit; and a transport unit that transports the document. An image reading apparatus that conveys the original between the supporting means and reads an image of the original,
Glossiness information acquisition means for acquiring glossiness information of the document before the document reaches the reading means;
An image reading apparatus characterized in that, based on the glossiness acquired by the glossiness information acquisition means, adjustment processing is performed to adjust the interval between the reading means and the support means by moving the support means. A reading unit that reads an image of the document; a support unit that supports the document from the non-reading surface side at a position facing the reading unit; and a transport unit that transports the document. An image reading apparatus that conveys the original between the supporting means and reads an image of the original,
The supporting means moves the document to the side opposite to the reading means against a predetermined force when transporting a document thicker than the distance between the reading means and the pressure toward the reading means. Is a means to support while adding
Glossiness information acquisition means for acquiring glossiness information of the document before the document reaches the reading means;
An image reading apparatus that performs an adjustment process for adjusting the magnitude of the predetermined force based on the glossiness acquired by the glossiness information acquisition means. The image reading apparatus according to any one of claims 1 to 3,
Paper thickness information acquisition means for acquiring thickness information of the original before the original reaches the reading means;
An image reading apparatus that performs the adjustment processing based on the paper thickness of the document acquired by the paper thickness information acquisition unit in addition to the glossiness.   An image processing apparatus comprising the image reading apparatus according to claim 1 as an image reading unit.

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