JP2020028030A - Image reading apparatus and image forming apparatus provided with the image reading apparatus - Google Patents

Abstract

An object of the present invention is to prevent shading correction accuracy from being lowered due to scratches and stains caused by contact of a document with a white reference member.
An image reading apparatus includes a transparent member provided at a predetermined reading position of a document conveying path and forming a guide surface for guiding a document being conveyed. The image reading sensor 211 is provided on the opposite side of the transparent member 242 from the document conveying path side, and the white reference member 302 is located between the transparent member 252 and the image reading sensor 211 and functions as a white reference. It is configured to be movable between one position and a second position that is retracted from the first position and enables the image reading sensor 211 to read a document image.
[Selection diagram] FIG.

Description

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

  2. Description of the Related Art Conventionally, an image reading apparatus including a reading unit that optically reads an image of a document on a contact glass has been known. The reading unit includes a light source that irradiates light toward a document, and a mirror that guides reflected light from the light source to linearly arranged light receiving elements. There are two image reading methods by this image reading device.

  The first method is to read a document image while moving the reading unit in the sub-scanning direction, and the second method is to fix the reading unit and convey the document to be read by the document feeder. This is a method for reading a document image. In the second method, a contact image sensor (image reading sensor) may be provided in the middle of the document conveyance path. In this case, in addition to reading the front surface image of the document by the reading unit, both sides of the document can be read by reading the back surface image of the document by the contact image sensor.

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

  The white reference member is normally arranged opposite to the image reading unit with the original conveying path interposed therebetween. For this reason, when the document passing through the document conveyance path contacts the white reference member, the white reference member may be scratched or stained. If the white reference member is scratched or stained, the correction value of the portion becomes an abnormal value at the time of shading correction, so that the 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 the image reading apparatus, when an abnormal value is included in the correction data at the time of the shading correction, the roller member is rotated so that the correction data is reacquired at a portion where the peripheral surface of the roller is free from scratches and dirt. ing.

JP 2010-34932 A

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

  The present invention has been made in view of such a point, and an object of the present invention is to prevent a document from contacting a white reference member, thereby preventing scratches and stains from being generated and reducing the shading correction accuracy. .

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

  The image reading sensor further includes a transparent member provided at the predetermined reading position of the document conveying path to form a guide surface for guiding the document being conveyed, and the image reading sensor is located on the opposite side of the transparent member from the document conveying path side. And a white reference member is provided between the transparent member and the image reading sensor and functions as the white reference. It is movable between a position and a second position that allows the image reading sensor to read the original image by retreating from the first position, and when shading correction is performed, the white reference member is moved to the first position. In addition, a white reference member driving unit that retracts the white reference member to the second position for not performing the shading correction is provided.

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

  According to the present invention, it is possible to prevent a situation in which a document comes into contact with a white reference member, which causes scratches and dirt, thereby lowering shading correction accuracy.

FIG. 1 is a schematic cross-sectional view illustrating an image forming apparatus including 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), and is a diagram showing a state where the white reference tape is at the first position. FIG. 4 is a view taken in the direction of the arrow IV in FIG. FIG. 5 is a diagram corresponding to FIG. 3 showing a state where the white reference tape is at the second position.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the following embodiments.

<< Embodiment >>
FIG. 1 shows an image forming apparatus 1 including an image reading device 200 according to the present 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 apparatus 200 mounted on an upper portion 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 mean the front side and the rear side (the right side and the left side in FIG. 1) of the image forming apparatus 1, respectively, and the left side and the right side are when the image forming apparatus 1 is viewed from the front side. Left side and right side (front side and 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 an upper part of the housing 60. The paper supply unit 10, the image forming unit 20, and the fixing unit 40 are housed in the housing 60. A plurality of transport roller pairs 11 to 13 for nipping and transporting the paper P are arranged in a paper transport path L from the paper feed unit 10 to the paper output tray unit 50. Further, a reversing conveyance path L ′ that branches from the downstream side of the sheet conveyance path L and joins the upstream side is provided. Transport roller pairs 14 to 16 are arranged in the reverse transport path L ′.

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

  In the image forming unit 20, four image forming units 20Bk, 20M, 20C, and 20Y that form toner images corresponding to 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.

  Below the image forming 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 disposed 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 the intermediate transfer belt 27 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 store toner of each color to be supplied to each of 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 of the photosensitive drums 21 with laser light based on predetermined image data (in this embodiment, original image data read by the image reading device 200), thereby forming an electrostatic image. Form a latent image. The image forming section 20 develops the formed electrostatic latent image by 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 onto the surface of the intermediate transfer belt 27 by the primary transfer roller 28 and are superimposed. Then, the toner image transferred onto the intermediate transfer belt 27 is transferred by the secondary transfer roller 29 onto the sheet P supplied from the sheet feeding unit 10. The sheet P after the transfer is supplied to the fixing unit 40.

  In the fixing unit 40, the toner image is fixed on the sheet P by pressing the sheet P supplied from the image forming unit 20 between the fixing roller 40a and the pressing roller 40b. Then, the sheet P on which the toner image has been fixed by the fixing unit 40 is sent downstream by both rollers 40a and 40b. The sheet P sent from the fixing unit 40 is discharged to the discharge tray unit 50 via the pair of transport rollers 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 250, a document holding cover 240, and a document feeding device 221. A first contact glass 250a (shown only in FIG. 2) for reading an image of the document G (shown only in FIGS. 4 and 5) by a sheet fixing method, and an image of the document G in a sheet-through manner are provided on the upper surface of the case body 250. And a second contact glass 250b for reading by the system.

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

  The document pressing cover 240 covers the upper surface of the case body 250 so as to be openable and closable. The document holding cover 240 is rotatably attached to the case body 250 via a hinge mechanism (not shown). The document feeder 221 is provided on the upper surface side of the document holding cover 240. The document feeder 221 supplies and passes a plurality of documents G onto the second contact glass 250b when reading a document image by the sheet-through method.

[Details of Document Feeder]
FIG. 2 is a longitudinal sectional view of the document feeder 221. The document feeder 221 has a main body case 222. The main body case 222 is provided at the left end on the upper surface side of the document pressing cover 240.

  On the right side surface of the main body case 222, a paper feed port 222c and a paper discharge port 222d arranged in a vertical direction are formed. 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. In the main body case 222, a substantially U-shaped document conveying path 225 extending from the paper feed port 222c to the paper discharge port 222d is formed. In the main body case 222, a delivery roller 261, a paper feed roller 262, a pair of transport rollers 263, 264, 265, and a pair of paper discharge rollers 266 are provided in this order along the transport path 225 from the upstream side to the downstream side. Have been. The rollers 261, 262 and the transport roller pairs 263 to 265 are arranged so as to extend in parallel in the main scanning direction (front-back direction), and function as a transport mechanism for transporting the document G.

  The feed roller 261 and the paper feed roller 262 are connected via a bracket 231. During the paper feeding operation, the feeding roller 261 comes into contact with the upper surface of the document G by rotating the bracket 231 clockwise around the support shaft 232 in the drawing.

  When the sheet feeding operation of the document feeder 221 is started, the document G placed on the sheet feed tray 223 is supplied to the document feed path 225 by the feed roller 261 and the feed roller 262, and then the feed roller pair The sheet is discharged to a sheet discharge tray 228 by a pair of sheet discharge rollers 266 via 263 to 265.

  The main body case 222 has an openable top cover 222a. The upper cover 222a is supported by a support shaft 222b provided at the left end of the main body case 222, and the upper part of the main body case 222 is rotated by rotating the main body case 222 around the support shaft 222b and lifting it upward. Be released. Thus, the user can process jammed paper jammed in the document conveying path 225 or replace a failed component.

  A first image reading position 226 and a second image reading position 227 are set in the middle of the document conveying path 225. At the first image reading position 226, an image on the back surface of the original G is read by the contact image sensor 211. At the second image reading position 227, the scanner unit 210 reads an image of the front surface G of the document.

  At the first image reading position 226, a transparent guide plate 252 (transparent member) that forms a guide surface for guiding the document G from below and a transparent guide plate 252 are disposed so as to oppose the floating of the document G during passage. A U-shaped guide 251 for regulating 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, a second contact glass 250b that guides the original from below, a U-shaped guide 253 that is disposed to face the second contact glass 250b, and that controls the floating of the original 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.

  The contact image sensor 211 (image reading sensor) for reading the back surface of the document G at the first image reading position 226 is arranged with a gap below the transparent guide plate 252. The 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 conveying path 225, and a plurality of light receiving elements (not shown) arranged in a main scanning direction (a direction coinciding with the front-back direction of the image forming apparatus). And Each light receiving element receives the reflected light from the document G and outputs an image signal (a voltage signal in the present embodiment) having a magnitude corresponding to the amount of the received light. The image signal output from each light receiving element is transmitted to a controller 350 (not shown). The controller 350 generates image data of the back surface of the document G based on the image signal received from each light receiving element.

  A slide plate 301 is provided in a gap between the contact image sensor 211 and the transparent guide plate 252. The slide plate 301 is reciprocally driven in a direction along the document transport direction by a drive mechanism 310 described later. A white reference tape 302 as a white reference member is attached to the slide plate 301, and the white reference tape 302 moves between the first position and the second position as the slide plate 301 reciprocates along the document conveyance direction. It reciprocates 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 located between the contact image sensor 211 and the transparent guide plate 252 and functions as a white reference. In the present embodiment, at the first position, the white reference tape 302 faces the entire reading surface of the contact image sensor 211. 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. Accordingly, it is possible to prevent the white reference tape 30 from being damaged or stained due to the 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 original image can be read by the contact image sensor 211. In the present embodiment, at the second position, the white reference tape 302 and the slide plate 301 are retracted upstream of the image reading surface of the contact image sensor 211 in the document conveying direction.

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

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

The pair of swing levers 311 are rotatably supported around a support pin 312 (around a support shaft) with respect to a fixing member 229 in the document feeder 221. Each swing lever 311 is formed in an elongated trapezoidal plate shape having a slope 311a at the tip. A U-shaped open groove 311b extending in the length direction is formed at the base end of each swing lever 311. A projecting pin 303 is slidably engaged with the open groove 311b of each swing lever 311. The width of the open groove 311b is slightly larger than the diameter of the protruding pin 303. Each swing lever 311 is constantly urged clockwise in FIG. 3 by a torsion spring 313 (urging member) with the support pin 312 as a fulcrum. In FIG. 3, a stopper 314 that receives the swing lever 311 against the urging force of the torsion spring 313 is provided near the lower end of the swing lever 311. When the swing lever 311 is in contact with the stopper 314, the upper end (front end) of the swing lever 311 penetrates the document feed path 225 up and down and is shut off. At this time, the slope 311a at the upper end of the swing lever 311 faces the upstream side in the document transport direction.

  In this state, when the document G is supplied from the document feed tray 223 into the document transport path 225, the leading end of the document G comes into contact with the inclined surface 311a of the swing lever 311. As a result, as shown in FIG. 5, the swing lever 311 rotates in the direction D1 (predetermined direction) in the figure with the support pin 312 as a fulcrum. Along with this, the protruding pin 303 fixed to the slide plate 301 moves rightward while sliding in the length 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 conveying direction), and accordingly, the white reference tape 302 moves from the first position to the second position. Thereafter, when the rear end of the document G has passed through the inclined surface 311 a of the swing lever 311, the propulsive force (pressing force) from the document G to the swing lever 311 does not act. Therefore, the swing lever 311 returns to the original position (the position 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 the return. 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, and the shading correction can be performed.

  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 one document image is read by the contact image sensor 211). 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.

[Effects]
As described above, in the present embodiment, the transparent guide plate 252 that guides the document G being transported is provided at the first image reading position (predetermined reading position) of the document transport path. Then, the contact image sensor 211 and the transparent guide plate 252 are provided on the side opposite to the document conveying path side, and the white reference tape 302 is located between the transparent guide plate 252 and the contact image sensor 211 and functions as a white reference. It can be moved between one position and a second position where it is retracted from the first position and the original image can be read by the contact image sensor 211.

According to this configuration, since the white reference tape 302 is located below the transparent guide plate 252 (the side opposite to the document conveyance path 225), the white reference tape 302 does not contact the document G being conveyed. Therefore, it is possible to prevent the original G from contacting the white reference tape 302 to cause scratches and dirt, thereby improving shading correction accuracy using the white reference tape 302.

  When the document G passes through the first image reading position 226 (an example of non-execution of shading correction), the driving mechanism 310 retracts the white reference tape 302 to the second position, When G does not pass through 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 in a state where the user opens the upper cover 222 (see FIG. 2), the contact image sensor 211 remains on the white reference tape 302. , It is possible to prevent the light from being directly radiated to the user.

  When the driving force of the document G supplied into the document feed path 225 acts on the swing lever 311, the drive mechanism 310 moves the support lever 311 against the urging force of the torsion spring 313. The white reference tape 302 rotates 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 the shading correction indicates an abnormal value, the white reference member is rotated or linearly moved by an electric motor or the like so that the white reference Had to reacquire. However, in the present embodiment, since the document does not contact the white reference tape 302, scratches and dirt do not adhere in the first place. Therefore, it is not necessary to employ 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 stuck to the slide plate 301. However, the present invention is not limited to this. For example, the slide plate 301 itself may be used as the white reference member. . In this case, the slide plate 301 may be formed of, for example, a resin plate having a white background.

  In the above embodiment, the control unit 350 executes the shading correction every time one document image is read by the contact image sensor 211. However, the present invention is not limited to this. For example, when the control unit 350 returns from the energy saving mode, 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 using the propulsive force at the time of transporting the document G, but is not limited to this. That is, the drive mechanism 310 may be configured to reciprocally drive the slide plate 301 by an actuator such as an electric motor or an air cylinder.

  As described above, the present invention is useful for an image reading apparatus and an image forming apparatus including the image reading apparatus.

G: Original 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: Discharge roller pair (transport mechanism)
290: Panel 300: Controller (control unit)
302: White reference tape (white reference member)
312: Support pin 313: Spring (biasing member)

Claims (5)

A transport mechanism that transports the original along the original transport path, an image reading sensor that reads an image of the original passing a predetermined reading position set in the middle of the original transport path, and a photo sensor that is disposed to face the image reading sensor. And a white reference member functioning as a white reference at the time of shading correction of the image reading sensor,
A transparent member that is provided at the predetermined reading position of the document transport path and forms a guide surface that guides the document being transported;
The image reading sensor is provided on the side opposite to the original conveying path side of the transparent member, is configured to be able to read the image of the original through the transparent member,
The white reference member is located between the transparent member and the image reading sensor and functions as the white reference. The first position is retracted from the first position to read the original image by the image reading sensor. Movable between a second position allowing
At the time of shading correction, the white reference member is located at the first position, and when the shading correction is not performed, the white reference member is further retracted to the second position. Reader. The image reading device according to claim 1,
The white reference member driving section retracts the white reference member to the second position when the document passes through the predetermined reading position, and causes the white reference member to move to the second position when the document does not pass the predetermined reading position. An image reading device configured to position a white reference member at the first position. The image reading device according to claim 1, wherein
The white reference member driving unit includes a support shaft, a swing lever supported by the support shaft and interlocking with the white reference member, and a biasing lever that rotates the swing lever around the support shaft in a predetermined direction. A biasing member for positioning the reference member at the first position; and when the propulsion force of the document supplied into the document transport path acts on the swing lever, the swing lever is moved by the biasing member. An image reading device configured to rotate around the support shaft to move the white reference member from the first position to the second position against the urging force. The image reading device according to any one of claims 1 to 3,
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 execute 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 reading device. An image forming apparatus comprising the image reading device according to claim 1.

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