JP7205106B2 - IMAGE READING DEVICE AND IMAGE FORMING APPARATUS INCLUDING THE IMAGE READING DEVICE - Google Patents

Description

The present invention relates to an image reading device and an image forming apparatus equipped with the image reading device.

2. Description of the Related Art Conventionally, an image reading apparatus having a reading unit that optically reads an image of an original placed on a contact glass is known. The reading unit has a light source for irradiating a document with light, and a mirror for guiding reflected light from the light source to linearly arranged light receiving elements. There are two methods of image reading by this image reading apparatus.

The first method is to read the document image while moving the reading unit in the sub-scanning direction, and the second method is to fix the reading unit and transport the document to be read by the document feeder. This is a method of reading an original image by In the second method, a contact image sensor (image reading sensor) may be provided in the middle of the document conveying path. In this case, in addition to the reading unit reading the front side image of the document, the contact image sensor reads the back side image of the document, thereby enabling both sides of the document to be read.

In the above image reading apparatus, shading correction is performed using a white reference member in order to correct variations in light receiving sensitivity among the light receiving elements provided in the reading unit.

This white reference member is normally arranged opposite to the image reading unit with the document conveying path interposed therebetween. For this reason, the white reference member may be scratched or soiled due to the contact of the document passing through the document transport path with the white reference member. If the white reference member is scratched or soiled, the correction value for that portion will be abnormal during shading correction, so shading correction cannot be performed with high accuracy.

Therefore, for example, in an image reading apparatus disclosed in Patent Document 1, a roller member whose peripheral surface is coated with white is used as a white reference member. In this image reading device, when the correction data for shading correction includes an abnormal value, the roller member is rotated to reacquire the correction data at a spot free from scratches or stains on the roller peripheral surface. ing.

JP 2010-34932 A

However, in the image reading apparatus disclosed in Patent Document 1, as described above, when the shading correction data includes an abnormal value, it is necessary to drive the white reference member and reacquire the correction data. For this reason, when scratches and stains increase on the peripheral surface of the roller, reacquisition of the correction data is frequently executed. As a result, there is a problem that the time required for shading correction becomes long.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to prevent deterioration in shading correction accuracy due to scratches and stains caused by contact of a document with a white reference member. .

An image reading apparatus according to one aspect of the present invention includes a conveying mechanism that conveys a document along a document conveying path, and an image reading sensor that reads an image of a document passing through a predetermined reading position set in the middle of the document conveying path. and a white reference member arranged to face the image reading sensor and functioning as a white reference during shading correction of the image reading sensor.

The image reading sensor further comprises a transparent member provided at the predetermined reading position of the document transport path and forming a guide surface for guiding the document being transported, wherein the image reading sensor is located on the opposite side of the transparent member to the document transport path side. The white reference member is positioned between the transparent member and the image reading sensor and functions as the white reference. and a second position where the document image can be read by the image reading sensor by retreating from the first position. During shading correction, the white reference member is moved to the first position. A white reference member driving unit is further provided for retracting the white reference member to the second position when the white reference member is positioned and the shading correction is not executed.

An image forming apparatus according to another aspect of the present invention includes the above image reading apparatus.

According to the present invention, it is possible to prevent deterioration in shading correction accuracy due to scratches and stains caused by contact of the document with the white reference member.

FIG. 1 is a schematic cross-sectional view showing an image forming apparatus equipped with an image reading device according to an embodiment. FIG. 2 is a schematic longitudinal sectional view showing the document feeder. FIG. 3 is a schematic diagram showing a driving mechanism for driving the white reference tape (slide plate), showing a state where the white reference tape is at the first position. 4 is a view in the direction of arrow IV in FIG. 3. FIG. FIG. 5 is a view equivalent to FIG. 3 showing a state where the white reference tape is at the second position.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail based on the drawings. In addition, the present invention is not limited to the following embodiments.

<<Embodiment>>
FIG. 1 shows an image forming apparatus 1 having an image reading device 200 according to this embodiment. The image forming apparatus 1 is a laser printer using an electrophotographic method. The image forming apparatus 1 includes an image forming apparatus main body 100, the image reading device 200 attached to the top of the image forming apparatus main body 100, and a panel 290 that can be operated by a user. In the following description, the front side and the rear side respectively mean the front side and the rear side (right side and left side in FIG. 1) of the image forming apparatus 1, and the left side and the right side are when the image forming apparatus 1 is viewed from the front side. means the left side and the right side of (the front side and the back side in the direction perpendicular to the paper surface of FIG. 1).

The image forming apparatus main body 100 has a box-shaped housing 60 . An image reading device 200 is provided on the top of the housing 60 . The housing 60 accommodates the paper feeding section 10 , the image forming section 20 , and the fixing section 40 . A plurality of transport roller pairs 11 to 13 are arranged on the paper transport path L from the paper feed unit 10 to the paper discharge tray unit 50 to sandwich and transport the paper P. As shown in FIG. In addition, a reversal transport path L' is provided that branches from the downstream side of the paper transport path L and merges with the upstream side. Conveying roller pairs 14 to 16 are arranged on the reverse conveying path L'.

The paper feeding unit 10 is arranged in the lower part of the housing 60 . The paper feed unit 10 has a paper feed cassette 10a in which sheet-like paper P is accommodated, and a pickup roller 10b for taking out the paper P in the paper feed cassette 10a and sending it out of the cassette. The paper P fed out of the paper feed cassette 10 a is supplied to the image forming section 20 via the transport roller pair 11 .

In the image forming section 20, four image forming units 20Bk, 20M, 20C, and 20Y that form toner images respectively corresponding to the respective colors of black, magenta, cyan, and yellow are arranged in a line. Each of the image forming units 20Bk, 20M, 20C and 20Y includes a photosensitive drum 21, a charging device 22, a developing device 23 and a cleaning device 24. As shown in FIG.

Below the imaging units 20Bk, 20M, 20C, and 20Y, an exposure device 25 that irradiates the surface of each photosensitive drum 21 with laser light is arranged. An intermediate transfer unit 26 is arranged above the image forming units 20Bk, 20M, 20C, and 20Y. The intermediate transfer unit 26 is provided with an intermediate transfer belt 27 that runs in contact with each photosensitive drum 21 . A primary transfer roller 28 is provided inside the intermediate transfer belt 27 so as to sandwich the intermediate transfer belt 27 between itself and the photosensitive drum 21 . A secondary transfer roller 29 is provided downstream of the image forming unit 20Bk so as to contact the surface of the intermediate transfer belt 27 . Above the intermediate transfer unit 26, toner containers 30Bk, 30M, 30C and 30Y are arranged. The toner containers 30Bk, 30M, 30C, and 30Y contain toners of respective colors to be supplied to the developing devices 23 of the image forming units 20Bk, 20M, 20C, and 20Y.

In the image forming unit 20, the exposure device 25 irradiates the surface of each photosensitive drum 21 with laser light based on predetermined image data (document image data read by the image reading device 200 in this embodiment), thereby electrostatically form a latent image. The image forming section 20 develops the formed electrostatic latent image with the developing device 23 to form a toner image of each color. The toner images of each color formed on the surface of each photosensitive drum 21 are sequentially transferred to the surface of the intermediate transfer belt 27 by the primary transfer roller 28 and superimposed. Then, the toner image transferred onto the intermediate transfer belt 27 is transferred onto the paper P supplied from the paper supply unit 10 by the secondary transfer roller 29 . The paper P after the transfer is supplied to the fixing section 40 .

In the fixing section 40, the toner image is fixed on the paper P by pressing the paper P supplied from the image forming section 20 between the fixing roller 40a and the pressure roller 40b. Then, the paper P on which the toner image is fixed by the fixing section 40 is fed downstream by both rollers 40a and 40b. The paper P sent out from the fixing section 40 is discharged to the paper discharge tray section 50 via the conveying roller pair 13 . When toner images are formed on both sides of the paper P, the paper P is switched back by the transport roller pair 13 and transported to the reverse transport path L'.

[Configuration of image reading device]
The image reading device 200 has a substantially rectangular parallelepiped case body 250 , a document pressing cover 240 and a document feeding device 221 . On the upper surface of the case body 250, a first contact glass 250a (shown only in FIG. 2) for reading the image of the document G (shown only in FIGS. 4 and 5) by a sheet fixing method and a sheet-through glass for reading the image of the document G are provided. A second contact glass 250b is mounted for reading in the manner.

A scanner unit 210 (see FIG. 2) is housed inside the case body 250 . The scanner unit 210 is composed of, for example, a reflecting mirror, a CCD sensor, and the like. The scanner unit 210 optically reads the image of the document G on the first contact glass 250a in the sheet fixing method. On the other hand, scanner unit 210 optically reads an image of a document passing over second contact glass 250b in the sheet-through method. Then, the scanner unit 210 generates digital data of the read document image.

The document holding cover 240 covers the upper surface of the case body 250 so that it can be opened and closed. The document pressing cover 240 is rotatably attached to the case body 250 via a hinge mechanism (not shown). The document feeding device 221 is provided on the top side of the document pressing cover 240 . The document feeder 221 feeds and passes a plurality of documents G onto the second contact glass 250b during document image reading by the sheet-through method.

[Details of document feeder]
FIG. 2 is a longitudinal sectional view of the document feeder 221. As shown in FIG. The document feeder 221 has a body case 222 . The body case 222 is provided at the left end of the upper surface of the document holding cover 240 .

A paper feed port 222c and a paper discharge port 222d are formed vertically on the right side of the body case 222 . A paper feed tray 223 and a paper discharge tray 228 are provided on the right side of the paper feed port 222c and the paper discharge port 222d, respectively. A substantially U-shaped document transport path 225 is formed in the body case 222 from the paper feed port 222c to the paper discharge port 222d. Inside the body case 222, a feed roller 261, a paper feed roller 262, transport roller pairs 263, 264, 265, and a paper discharge roller pair 266 are provided in this order from the upstream side to the downstream side along the transport path 225. It is These rollers 261 and 262 and transport roller pairs 263 to 265 are arranged so as to extend parallel to the main scanning direction (front-to-rear direction) and function as a transport mechanism for transporting the document G. FIG.

The delivery roller 261 and the paper feed roller 262 are connected via the bracket portion 231 . During the paper feed operation, the bracket portion 231 rotates around the support shaft 232 in the clockwise direction in the figure, so that the delivery roller 261 comes into contact with the upper surface of the document G. As shown in FIG.

When the document feeding operation of the document feeding device 221 starts, the document G placed on the feeding tray 223 is fed to the document feeding path 225 by the sending roller 261 and the feeding roller 262, and then the feeding roller pair 263 to 265 are discharged to a paper discharge tray 228 by a paper discharge roller pair 266 .

The body case 222 has an openable upper cover 222a. The upper cover 222a is pivotally supported by a support shaft 222b provided at the left end of the main body case 222. By rotating the main body case 222 around the support shaft 222b and lifting it upward, the upper part of the main body case 222 is lifted. be released. As a result, the user can deal with jammed paper jammed in the document transport path 225 and replace defective parts.

A first image reading position 226 and a second image reading position 227 are set in the middle of the document transport path 225 . At the first image reading position 226 , a contact image sensor 211 reads the image of the back side of the document G. FIG. At the second image reading position 227, the scanner section 210 reads the image of the surface G of the document.

At the first image reading position 226, a transparent guide plate 252 (transparent member) that forms a guide surface that guides the document G from below is arranged opposite to the transparent guide plate 252 to prevent floating of the document G during passage. A U-shaped guide 251 for regulation is provided. The transparent guide plate 252 and the U-shaped guide 251 are provided over the entire document passage area in the main scanning direction. At the second image reading position 227, there are a second contact glass 250b that guides the document from below, and a U-shaped guide 253 that is arranged to face the second contact glass 250b and restricts floating of the document G during passage. is provided. The second contact glass 250b and the U-shaped guide 253 are provided over the entire document passage area in the main scanning direction.

A contact image sensor 211 (image reading sensor) that reads the back surface of the document G at the first image reading position 226 is arranged below the transparent guide plate 252 with a gap therebetween. A reading surface of the contact image sensor 211 faces the transparent guide plate 252 . The contact image sensor 211 includes a light source that emits light toward the document G passing through the document transport path 225 and a plurality of light receiving elements (not shown) that are arranged in the main scanning direction (the direction coinciding with the front-rear direction of the image forming apparatus). and Each light-receiving element receives reflected light from the document G and outputs an image signal (voltage signal in this embodiment) having a magnitude corresponding to the amount of light received. An image signal output from each light receiving element is sent to a controller 350 (not shown). The controller 350 generates image data of the back surface of the document G based on the image signals received from the respective light receiving elements.

A slide plate 301 is provided between the contact image sensor 211 and the transparent guide plate 252 . The slide plate 301 is reciprocatingly driven in the document transport direction by a drive mechanism 310, which will be described later. A white reference tape 302 as a white reference member is attached to the slide plate 301. As the slide plate 301 reciprocates along the document transport direction, the white reference tape 302 moves between the first position and the second position. It is designed to move back and forth between Although not shown, the slide plate 301 is guided by a rail member.

Here, the first position is a position where the white reference tape 302 is positioned between the contact image sensor 211 and the transparent guide plate 252 and functions as a white reference. In this embodiment, the white reference tape 302 faces the entire reading surface of the contact image sensor 211 at the first position. It is preferable that there is a slight gap between the reading surface of the contact image sensor 211 and the white reference tape 302 . As a result, it is possible to prevent the white reference tape 30 from being scratched or stained due to contact between the two.

On the other hand, the second position is a position where the white reference tape 302 is retracted from the first position and the contact image sensor 211 can read the document image. In this embodiment, at the second position, the white reference tape 302 is retracted together with the slide plate 301 upstream of the image reading surface of the contact image sensor 211 in the document transport direction.

[Drive mechanism]
Next, the driving mechanism 310 (white reference member driving section) for reciprocatingly driving the slide plate 301 will be described with reference to FIGS. 3 to 5. FIG. The drive mechanism 310 does not have a power source such as a motor, and drives the slide plate 301 using the propulsive force when the document G is conveyed. 3 and 4, the basic configuration of the driving mechanism 310 will be described first, and then the principle of operation of the driving mechanism 310 by the driving force of the document G will be described.

The drive mechanism 310 has a pair of rocking levers 311 that engage with a pair of protruding pins 303 provided on the slide plate 301 . Here, as shown in FIG. 4, the slide plate 301 has a wide portion 301a covering the entire reading surface of the contact image sensor 211, and a narrow portion 301b connected to the upstream side of the wide portion 301a in the document transport direction. have. The white reference tape 302 is attached only to the wide portion 301a. The pair of protruding pins 303 protrude from both end surfaces of the narrow portion 301b in the main scanning direction.

The pair of rocking levers 311 is supported by a fixed member 229 in the document feeder 221 so as to be rotatable about a support pin 312 (about a support shaft). Each rocking lever 311 is formed in an elongated trapezoidal plate shape having a slope 311a at its tip. A U-shaped open groove 311b extending in the longitudinal direction is formed at the base end of each rocking lever 311 . A projecting pin 303 is slidably engaged with the open groove 311b of each rocking lever 311. As shown in FIG. The width of the open groove 311 b is slightly larger than the diameter of the projecting pin 303 . Each rocking lever 311 is always biased clockwise in FIG. 3 with a support pin 312 as a fulcrum by a torsion spring 313 (biasing member). In FIG. 3, a stopper 314 is provided near the lower end of the swing lever 311 to receive the swing lever 311 against the biasing force of the torsion spring 313 . When the rocking lever 311 is in contact with the stopper 314 , the upper end (tip) of the rocking lever 311 vertically penetrates the document transport path 225 to block it. At this time, the inclined surface 311a of the upper end portion of the swing lever 311 faces the upstream side in the document transport direction.

When the document G is fed from the document feed tray 223 into the document transport path 225 in this state, the leading edge of the document G abuts against the slope 311 a of the swing lever 311 . As a result, as shown in FIG. 5, the swing lever 311 rotates about the support pin 312 in the D1 direction (predetermined direction). Along with this, the protruding pin 303 fixed to the slide plate 301 moves rightward while sliding in the longitudinal direction in the open groove 311b. As a result, the slide plate 301 moves to the right of the reading surface of the contact image sensor 211 (upstream in the document transport direction), and the white reference tape 302 moves from the first position to the second position. After that, when the trailing edge of the document G has passed the slope 311a of the swing lever 311, the driving force (pressing force) from the document G to the swing lever 311 ceases to act. Therefore, the swing lever 311 returns to its original position (the position shown in FIG. 3) by the restoring force of the torsion spring 313, and the white reference tape 302 also returns from the second position to the first position in conjunction with this. When the white reference tape 302 returns to the first position, the reading surface of the contact image sensor 211 is covered with the white reference tape 302 to enable shading correction.

The controller 350 acquires white reference data (read data) for each light receiving element each time the white reference tape 302 returns to the first position (that is, each time the contact image sensor 211 reads one document image). Then, the controller 350 executes sensitivity correction (seeding correction) of each light receiving element of the contact image sensor 211 based on the acquired white reference data.

[Effect]
As described above, in this embodiment, the transparent guide plate 252 is provided at the first image reading position (predetermined reading position) of the document conveying path to guide the document G being conveyed. A white reference tape 302 is positioned between the transparent guide plate 252 and the contact image sensor 211 and functions as a white reference. It is movable between a first position and a second position where the contact image sensor 211 can read the document image by retreating from the first position.

According to this configuration, the white reference tape 302 is on the lower side of the transparent guide plate 252 (on the side opposite to the document conveying path 225 side), so that the white reference tape 302 does not come into contact with the document G being conveyed. Therefore, it is possible to prevent the white reference tape 302 from being scratched or soiled by the original document G coming into contact with the white reference tape 302, thereby improving the shading correction accuracy using the white reference tape 302. FIG.

Further, the drive mechanism 310 retracts the white reference tape 302 to the second position when the document G passes the first image reading position 226 (an example of when the shading correction is not performed). When G has not passed the first image reading position 226, the white reference tape 302 is positioned at the first position.

According to this configuration, even if the light source of the contact image sensor 211 is turned on due to a malfunction of the control unit 350 while the user opens the upper cover 222 (see FIG. 2), the contact image sensor 211 will not be exposed to the white reference tape 302. , it is possible to prevent the user from being directly exposed to the light.

In the drive mechanism 310 , when the driving force of the document G fed into the document transport path 225 acts on the swing lever 311 , the swing lever 311 moves against the biasing force of the torsion spring 313 to move the support pin 312 . It is configured to rotate around to move the white reference tape 302 from the first position to the second position.

According to this configuration, the white reference tape can be automatically moved from the first position to the second position without using an actuator such as an electric motor. Therefore, product cost can be reduced.

That is, in the conventional image forming apparatus, when the correction value at the time of shading correction indicates an abnormal value, the white reference member is rotated or linearly moved by an electric motor or the like, and white reference data is obtained at a spot free from scratches and stains. had to be reacquired. However, in the present embodiment, since the document does not come into contact with the white reference tape 302, scratches and stains do not stick to it in the first place. Therefore, there is no need to adopt an expensive mechanism using such an electric motor.

<<Other embodiments>>
In the above embodiment, the white reference tape 302 as the white reference member is attached to the slide plate 301. However, the present invention is not limited to this, and the slide plate 301 itself may be used as the white reference member. . In this case, the slide plate 301 may be made of a resin plate having a white background, for example.

In the above embodiment, the control unit 350 executes shading correction each time the contact image sensor 211 reads a document image. Alternatively, it may be performed only once when the power is turned on.

In the above-described embodiment, the driving mechanism 310 drives the slide plate 301 by using the driving force when the document G is conveyed, but the driving mechanism 310 is not limited to this. That is, the drive mechanism 310 may reciprocate the slide plate 301 by an actuator such as an electric motor or an air cylinder.

INDUSTRIAL APPLICABILITY As described above, the present invention is useful for an image reading device and an image forming apparatus equipped with the image reading device.

G: Document 1: Image forming apparatus 30: White reference tape (white reference member)
200: image reading device 211: contact image sensor 221: document feeding device 261: delivery roller (conveyance mechanism)
262: Paper feed roller (transport mechanism)
263: transport roller pair (transport mechanism)
264: transport roller pair (transport mechanism)
265: transport roller pair (transport mechanism)
266: pair of discharge rollers (conveyance mechanism)
290: Panel 300: Controller (control unit)
302: White reference tape (white reference member)
312: Support pin 313: Spring (biasing member)

Claims (6)

A transport mechanism for transporting a document along a document transport path, an image reading sensor for reading an image of a document passing through a predetermined reading position set in the middle of the document transport path, and an image reading sensor arranged to face the image reading sensor. and a white reference member that functions as a white reference during shading correction of the image reading sensor,
further comprising a transparent member fixed at the predetermined reading position of the document transport path and forming a guide surface for guiding the document being transported;
The image reading sensor is provided on the opposite side of the transparent member from the document conveying path side, and is configured to be able to read the image of the document through the transparent member,
The white reference member is configured to be movable separately from the transparent member, and is positioned between the transparent member and the image reading sensor to function as the white reference; movable between a first position and a second position at which the image reading sensor can read the document image;
The image processing apparatus further comprises a white reference member driving unit that positions the white reference member at the first position during shading correction and retracts the white reference member to the second position when shading correction is not performed. reader. The image reading device according to claim 1,
The white reference member drive section retracts the white reference member to the second position when the document passes through the predetermined reading position, and retracts the white reference member to the second position when the document does not pass the predetermined reading position. An image reading device configured to position the white reference member at the first position. 3. The image reading device according to claim 1, wherein
The white reference member drive section includes a support shaft, a swing lever supported by the support shaft and interlocking with the white reference member, and biasing the swing lever around the support shaft in a predetermined direction to drive the white reference member. an urging member for positioning the reference member at the first position, and when the propulsive force of the document fed into the document conveying path acts on the swing lever, the swing lever is moved by the urging member. an image reading device configured to rotate about the support shaft against the biasing force of to move the white reference member from the first position to the second position. The image reading device according to any one of claims 1 to 3,
further comprising a control unit that performs shading correction of the image reading sensor based on read data of the white reference member by the image reading sensor;
The control unit is configured to perform shading correction of the image reading sensor each time the white reference member is driven from the second position to the first position by the white reference member driving unit. Image reader. A transport mechanism for transporting a document along a document transport path, an image reading sensor for reading an image of a document passing through a predetermined reading position set in the middle of the document transport path, and an image reading sensor arranged to face the image reading sensor. and a white reference member that functions as a white reference during shading correction of the image reading sensor,
further comprising a transparent member provided at the predetermined reading position of the document transport path and forming a guide surface for guiding the document being transported;
The image reading sensor is provided on the opposite side of the transparent member from the document conveying path side, and is configured to be able to read the image of the document through the transparent member,
The white reference member is positioned between the transparent member and the image reading sensor to function as the white reference at a first position, and retreats from the first position to allow the image reading sensor to read the document image. is movable between a second position to
a white reference member driving unit for positioning the white reference member at the first position during shading correction and retracting the white reference member to the second position when shading correction is not performed;
The white reference member drive section retracts the white reference member to the second position when the document passes through the predetermined reading position, and retracts the white reference member to the second position when the document does not pass the predetermined reading position. configured to position the white reference member at the first position;
The white reference member drive section includes a support shaft, a swing lever supported by the support shaft and interlocking with the white reference member, and biasing the swing lever around the support shaft in a predetermined direction to drive the white reference member. an urging member for positioning the reference member at the first position, and when the propulsive force of the document fed into the document conveying path acts on the swing lever, the swing lever is moved by the urging member. an image reading device configured to rotate about the support shaft against the biasing force of to move the white reference member from the first position to the second position. An image forming apparatus comprising the image reading apparatus according to claim 1 .

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