JP7283281B2 - Automatic document feeder, automatic document reader, and image forming device - Google Patents

Description

The present invention relates to an automatic document feeder, an automatic document reader, and an image forming apparatus.

2. Description of the Related Art A contact image sensor (CIS) is often used as a space-saving reading means in an automatic document feeder that reads a document conveyed on a contact glass by exposing it with a fixed reading unit. Since this contact image sensor has a shallow depth of focus, an opposing member such as a roller is placed on the opposing surface to control the gap between the document and the contact glass so that the document does not rise above the contact glass when the document is read. ing.
In addition, in order to prevent the influence of temporal changes in the amount of light from the light source that irradiates the document on the image data to be read, so-called shading correction, which corrects the image using the results of reading a white reference member, is used to improve the contact image. This is done in the use of sensors.

When the shading correction described above is performed before the start of a job or between sheets without physically moving the contact image sensor, the roller arranged on the facing surface described above is used as a reference white roller, and this white roller is used. There is known a technique of performing shading correction using Then, a portion of the white roller is cut along a plane parallel to the axial direction, and the circular arc portion of the white roller is brought into contact with the contact glass when acquiring shading data. A technique has also been proposed in which the focal length of the close contact image sensor is the same when acquiring shading data.

However, in the configuration in which a portion of the white roller is cut, there is a problem that the document is prevented from being transported when the document is transported with the cut surface facing the reading surface side. This is because when the document comes in contact with the white roller and the white roller rotates slightly, or when the position control of the white roller is deviated, the cut surface deviates from the reading position, and the arc portion becomes a gap in the document transport path. narrows or closes the opening, causing a document transport jam.
In order to solve the above-mentioned problems, a roller-shaped rotating body having portions with different distances from the center of rotation to the outer periphery, the outer peripheral surface having a radius r1 substantially equal to the distance from the center of rotation to the document reading surface of the contact glass, an outer peripheral surface with radius r2 shorter than the distance from the center of rotation to the document reading surface by a transport gap for transporting the document in substantially close contact with the document reading surface, and the outer peripheral surface with radius r1 is white. An image reading apparatus has been proposed that includes a white reference roller that is used as a reference portion and whose outer peripheral surface with a radius r2 is used as a conveyance guide portion (see, for example, Japanese Unexamined Patent Application Publication No. 2002-100003).

However, with the above-described technique, a document with a curved or folded leading edge, such as one that has not been straightened after the staple has been removed, cannot pass through the radius r2 portion, causing a document transport jam. There is a problem. Further, even if the document can pass through, there is a gap between the document surface and the document reading surface, which causes the contact image sensor to be out of focus, resulting in a problem that the document cannot be read accurately.
SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and provides an automatic document feeder capable of preventing the occurrence of a document feed jam even when a document with a bent or folded tip is fed and capable of accurately reading the document. An object of the present invention is to provide an automatic document reading device and an image forming device.

According to a first aspect of the present invention, there is provided an image reading means for reading an image of a conveyed document, a document conveying means arranged opposite to the image reading means for conveying the document read by the image reading means, and the document conveying means. between a contact position in contact with the image reading means and a separation position at a predetermined distance from the image reading means; and a guide member that guides the transport of the document on the upstream side of the contact position in the document transport direction. After the leading edge of the document passes through the opposing position between the image reading means and the document conveying means based on the detection signal, the displacement means displaces the document conveying means to the contact position , and the guide member moves to the contact position. and a second position corresponding to the spaced position in a direction perpendicular to the document conveying direction.

According to the present invention, even if there is a deformed portion bent or folded at the leading end of the document, the deformed portion passes through the contact position when the document conveying means occupies the separated position, so that deformation at the contact position is minimized. It is possible to prevent the jamming of the part, reliably prevent the occurrence of document transport jams, and perform accurate document reading. Therefore, an automatic document feeder, an automatic document reader, and an image forming apparatus capable of preventing the occurrence of a document feed jam even when a document with a curved or folded tip is fed and capable of accurately reading the document are provided. can provide.

1 is a schematic configuration diagram of an image forming apparatus to which one embodiment of the present invention can be applied; FIG. 1 is a schematic configuration diagram of a conventional automatic document feeder; FIG. It is a block diagram of the controller part used for one embodiment of the present invention. 1 is a schematic diagram of a main part of an automatic document feeder according to one embodiment of the present invention; FIG. 1 is a schematic diagram of a main part of an automatic document feeder according to one embodiment of the present invention; FIG. 1 is a schematic diagram of a main part of an automatic document feeder according to one embodiment of the present invention; FIG. 1 is a schematic diagram of a main part of an automatic document feeder according to one embodiment of the present invention; FIG. 4 is a flow chart of document reading operation in one embodiment of the present invention.

FIG. 1 is a schematic front view of an image forming apparatus according to one embodiment of the invention. In the figure, a full-color copier 1, which is an image forming apparatus, includes a reading device 2 for reading the contents of a document, an automatic document feeder 3 for automatically feeding the document, and a paper feeding device for supplying a transfer sheet S as a recording medium. 4. It has an image forming section 5 for forming an image on the transfer sheet S, and the like. In the present embodiment, a copying apparatus 1 using toner of four colors (black (K), cyan (C), magenta (M), and yellow (Y)) will be described as an example of an image forming apparatus. may be a monochrome image forming apparatus. In the copying machine 1 , the reading device 2 and the automatic document feeder 3 constitute an automatic document reading device 6 .

The reading device 2 is mounted on the top of the copying machine 1, and includes a reading unit 21 for irradiating a document with light to read the document image, a first mirror 22a and a second mirror 22b for bending the light reflected from the document, and a second mirror 22b for bending the light reflected from the document. It has three mirrors 22c, a lens 23, an imaging device 24 such as a CCD, an image processing board 25, and the like. A contact glass 26 on which a document can be placed is arranged on the upper surface of the reading device 2 . An automatic document feeder 3, which is a feature of the present invention, is arranged above the reading device 2. As shown in FIG. The automatic document feeder 3 will be described later. A first image reading sensor 29 made up of a contact image sensor for reading an image of a document conveyed by the automatic document feeder 3 is arranged above the reading device 2 .

The paper feeding device 4 includes paper feeding cassettes 41a, 41b, and 41c for storing the transfer sheets S, and paper feeding means 42a and 42b provided corresponding to the respective paper feeding cassettes 41a, 41b, and 41c for feeding the transfer sheets S. , 42c, a paper feed transport means 43 for transporting the transfer sheets S fed from the paper feed cassettes 41a, 41b, and 41c to the image forming section 5, a paper feed transport path 44 for feeding the transfer sheets S, and the like. are doing.

The image forming unit 5 includes an exposure device 51 that outputs image information of the document T obtained by the reading device 2 or the automatic document feeder 3 as an image signal, black (K), cyan (C), magenta (M), and yellow. It has photoreceptor drums 52a, 52b, 52c, and 52d that carry toner images of respective colors (Y). The image forming unit 5 also includes charging devices 53a, 53b, 53c, and 53d for charging the respective photosensitive drums 52a, 52b, 52c, and 52d, and developing devices for forming respective color toner images on the photosensitive drums 52a, 52b, 52c, and 52d. It has devices 54a, 54b, 54c and 54d. The image forming section 5 also transfers the primary transfer image on the intermediate transfer belt 55 onto which the toner images of respective colors formed on the photosensitive drums 52a, 52b, 52c, and 52d are primarily transferred onto the transfer sheet S. It has a secondary transfer roller 56 for subsequent transfer.

The image forming section 5 also includes a fixing device 57 that fixes the full-color toner image secondarily transferred onto the transfer sheet S by heat and pressure, and the transfer sheet S sent from the paper feeding and conveying path 44 . A sheet conveying path 58 a is provided to convey the sheet to the fixing device 57 . Further, the image forming section 5 includes a paper discharge tray 59 on which the transfer sheet S having the image formed thereon is stacked, a paper discharge transportation path 58b for conveying the transfer sheet from the fixing device 57 to the paper discharge tray 59, and images on both sides of the transfer sheet S. It has a switchback transport path 58c, a double-sided transport path 58d, and the like, which are used when forming is performed.

Next, a series of operations for forming an image of the content of the document on the transfer sheet S by the copying apparatus 1 will be described.
The document conveyed by the automatic document feeder 3 is irradiated with light from the light source of the reading section 21 , and after the reflected light is photoelectrically converted, an image signal, which is the surface read image, is output to the exposure device 51 . Further, the light reflected from the document is converted into signals by the lens 23, the imaging device 24 and the image processing board 25 by the refraction of the mirrors 22a, 22b and 22c.

In the case of single-sided image formation, an image signal is sent to the image forming section 5 after the image on the front side of the document is read by the reading device 2. After the information on the other side is read, image information on both sides is output to the exposure device 51 .
The automatic document feeder 3 is connected to the main body of the image forming apparatus by means of a hinge so that the document can be opened and closed. Image information of the document is read by driving the reading unit 21 in accordance with the size of the document while the document is placed.
When the document image information is read and an image signal is output to the exposure device 51, the transfer sheet S accommodated in, for example, the paper feeding cassette 41a is transferred to the secondary transfer roller 56 by the paper feeding means 42a and the paper feeding/conveying means 43. It is conveyed to the contact portion with the intermediate transfer belt 55 .

The exposure device 51 that has received the image signal irradiates the laser light L toward each of the photosensitive drums 52a, 52b, 52c, and 52d. As a result, electrostatic latent images are formed on the photosensitive drums 52a, 52b, 52c and 52d, the surfaces of which are previously charged to predetermined potentials by the charging devices 53a, 53b, 53c and 53d. Then, each color toner is supplied from each developing device 54a, 54b, 54c, 54d to each formed electrostatic latent image, and each electrostatic latent image is visualized. The visualized toner images of respective colors on the photosensitive drums 52a, 52b, 52c, and 52d are superimposed and transferred onto the intermediate transfer belt 55 in an overlapping manner, whereby a full-color toner image is formed on the intermediate transfer belt 55. It is formed.

The full-color toner image formed on the intermediate transfer belt 55 is collectively secondary-transferred onto the transfer sheet S conveyed at a position facing the secondary transfer roller 56, whereby a full-color toner image is formed on the transfer sheet S. is transcribed. The transfer sheet S to which the full-color toner image has been transferred is sent to a fixing device 57, where the full-color toner image is fixed by heat and pressure. The transfer sheet S on which the full-color toner image is fixed is discharged onto the paper discharge tray 59 via the paper discharge transport path 58b.
Image formation on one side of the transfer sheet S is completed by the series of operations described above. When image formation is performed on both sides of the transfer sheet S, after the image formation on one side of the transfer sheet S is completed in the fixing device 57, the transfer sheet S is conveyed to the switchback conveying path 58c. After reversing the conveying direction, the transfer sheet S is conveyed to the double-sided conveying path 58d and conveyed again to the position where the intermediate transfer belt 55 and the secondary transfer roller 56 face each other. After the reverse side image is formed on the other side of the transfer sheet S, which is turned upside down, the transfer sheet S is ejected onto the paper ejection tray 59 through the fixing device 57 and the paper ejection transport path 58b in the same manner as described above.

FIG. 2 is a schematic configuration diagram of a sheet-through type ADF, which is the automatic document feeder 3 according to this embodiment, and FIG.
The automatic document feeder 3 feeds a document as a sheet (including both the concepts of a single sheet and a stack of multiple stacked sheets) to a fixed portion of a reading device, and conveys an image at a predetermined speed. Used for reading devices.
An example of its basic configuration, operation, and action will be described below. As shown in FIG. 2, the automatic document feeder 3 includes a document setting section A for setting a document 7, a separation feeding section for separating and feeding the document 7 sheet by sheet from a plurality of sheets of the set document 7. B, there is a registration section C that temporarily abuts and aligns the fed originals 7 and draws out and conveys the aligned originals 7 . Further, the automatic document feeder 3 turns the transported document 7 and transports the document face downward, which is the reading side, at a turn portion D, and reads the surface image of the document 7 from below the second contact glass 27 . It has a first reading/conveying section E and a second reading/conveying section F for reading the back side image of the document 7 after reading the front side image. Further, the automatic document feeder 3 includes a paper ejection unit G for discharging the originals 7 whose front and back sides have been read, a stacking unit H for stacking and holding the originals 7 after reading has been completed, and a driving unit for driving the conveying operation. It has units 61 to 65 (see FIG. 3) and a controller unit 60 (see FIG. 3) as control means for controlling a series of operations.

A document 7 to be read is set on a document table 32 including a movable document table 31, and the document 7 is set with its image surface facing upward. The document 7 is positioned in a direction (main scanning direction) orthogonal to the document conveying direction by a side fence (not shown).
The setting of the document 7 is detected by the set filler 33 and the document set sensor 34 which is turned on and off by the set filler 33, and is transmitted to the main body control section 9 via the interface I/F 8 (see FIG. 3). The set filler 33 and the document set sensor 34 constitute sheet detection means.
The length of the document 7 in the conveying direction is roughly determined by the document length detection sensors 35 and 36 provided on the document table 32 . As the document length detection sensors 35 and 36, a reflective sensor or an actuator type sensor capable of detecting even one document 7 is used.

The movable document table 31 can be moved up and down in the directions of arrows a and b shown in FIG. , the bottom plate lifting motor 65 is rotated forward to raise the movable document table 31 so that the top surface of the document 7 contacts the pickup roller 37 .
The pickup roller 37 is displaced in the directions of arrows c and d shown in FIG. 2 by a cam mechanism to which a pickup lifting motor 61 (see FIG. 3) is connected. As the movable document table 31 rises, the pickup roller 37 is pushed by the upper surface of the document on the movable document table 31 and rises in the direction of arrow c. The lower limit position of the movable document table 31 is set as the home position, and the home position is detected by the bottom plate home position sensor 47 .

When a print key (not shown) provided on the operation unit 10 (see FIG. 3) of the copier 1 is pressed and a document transport signal is transmitted from the body control unit 9 to the controller unit 60 via the interface I/F 8, the pickup is performed. The roller 37 is rotationally driven by forward rotation of the paper feeding motor 62 (see FIG. 3), and picks up several (ideally one) originals 7 on the original table 32 . The forward rotation of the paper feed motor 62 drives the document transport belt 39 in the paper feed direction. Only the uppermost document 7 is conveyed by separating it from the lower document 7. - 特許庁The original conveying belt 39 and the reverse roller 11 constitute a separating and feeding means.

More specifically, the reverse roller 11 is in contact with the document conveying belt 39 with a predetermined pressure. rotates in the counterclockwise direction following the rotation of
When two or more documents enter between the document conveying belt 39 and the reverse roller 11, the driven rotational force is set to be lower than the torque of the torque limiter. It rotates clockwise, which is the driving direction, and pushes back excess documents to prevent double feeding.

Due to the action of the document conveying belt 39 and the reverse roller 11, the document 7 separated into one sheet is further fed by the document conveying belt 39, and after the leading edge is detected by the abutting sensor 12, it further advances and stops. The tip is brought into contact with the pullout roller pair 13 .
After that, the document 7 is fed by a predetermined distance from the detection of the abutment sensor 12, and as a result is pushed against the pullout roller pair 13 with a predetermined amount of flexure. By stopping the paper feeding motor 62 in this state, the driving of the document conveying belt 39 is stopped. At this time, by rotating the pickup lifting motor 61, the pickup roller 37 is retracted from the upper surface of the document 7, and the document 7 is fed only by the conveying force of the document conveying belt 39, so that the leading edge of the document 7 reaches the pull-out roller pair 13. Entering the nip, tip alignment (skew correction) is performed.

The pullout roller pair 13 has the skew correction function described above, and is a roller for conveying the skew-corrected document 7 to the intermediate roller pair 14 after separation. When the paper feed motor 62 is reversed, both the pullout roller pair 13 and the intermediate roller pair 14 are driven, but neither the pickup roller 37 nor the document transport belt 39 are driven.

A plurality of document width sensors 15 are arranged side by side in the paper surface direction in FIG.
The length of the document 7 in the conveying direction is detected from the motor pulse by reading the leading edge and the trailing edge of the document 7 with the abutting sensor 12 .
When the document 7 is conveyed from the registration section C to the turn section D by driving the pullout roller pair 13 and the intermediate roller pair 14, the conveyance speed at the registration section C is set higher than the conveyance speed at the first reading conveyance section E. is also set to a high speed to shorten the processing time for sending the document 7 to the reading section 21 .

When the leading edge of the document 7 is detected by the reading inlet sensor 16, before the leading edge of the document 7 enters the nip of the reading inlet roller pair 17, the pullout roller pair is activated to make the document conveying speed equal to the reading conveying speed. 13 and the intermediate roller pair 14 are started to decelerate. At the same time, the reading motor 63 is driven forward to drive the reading entrance roller pair 17, the reading exit roller pair 18, the second image reading sensor 19, and the exit roller pair 20. FIG. The intermediate roller pair 14 and the reading entrance roller pair 17 constitute transport means.

When the leading edge of the document 7 is detected by the registration sensor 28, the transport speed of the document 7 is decelerated over a predetermined transport distance, and the sensor 29 is provided on the second contact glass 27 before the reading position of the first image reading sensor 29. While temporarily stopped by the position sensor 30 , a registration stop signal is transmitted to the body control unit 9 via the interface I/F 8 . Subsequently, when a reading start signal is received from the body control unit 9, the document 7, which has been temporarily stopped, is conveyed at an increased speed so as to rise to a predetermined conveying speed until the leading edge of the document 7 reaches the reading position. At the timing when the leading edge of the document 7 detected by the pulse count of the reading motor 63 reaches the first image reading sensor 29, a gate signal indicating the effective image area in the sub-scanning direction of the first surface is sent to the body control unit 9. The position sensor 30 is transmitted until the trailing edge of the document 7 leaves.

In the case of single-sided document reading, the document 7 that has passed through the first reading/conveying section E is conveyed to the sheet discharge section G via the second image reading sensor 19 . At this time, when the discharge sensor 40 detects the leading edge of the document 7, the discharge motor 64 is driven forward to rotate the upper roller of the discharge roller pair 45 counterclockwise. Further, based on the ejection motor pulse count from the detection of the leading edge of the document 7 by the ejection sensor 40, the drive speed of the ejection motor 64 is reduced just before the trailing edge of the document 7 leaves the nip of the ejection roller pair 45. , the document 7 discharged onto the discharge tray 46 is controlled so as not to jump out of the discharge tray 46 .
In the case of double-sided document reading, after the discharge sensor 40 detects the leading edge of the document, the pulse count of the reading motor 63 causes the second image reading sensor 19 to reach the leading edge of the document 7 at the timing. 19, a gate signal indicating the effective image area in the sub-scanning direction is sent from the controller unit 60 to the second image reading sensor 19 until the trailing edge of the document 7 passes through.

A translucent member (not shown) constituting a document reading surface by the second image reading sensor 19 faces the second image reading sensor 19 as an image reading means composed of a close-contact image sensor, and a second translucent member (not shown) passes through the translucent member (not shown). 2 A white reference roller 48 is arranged to face the image reading sensor 19 .
A translucent member (not shown) is arranged on the side of the second image reading sensor 19 as one transport guide that forms the transport path of the document 7 , and the white reference roller 48 functions as the other transport guide that forms the transport path of the document 7 .
The white reference roller 48 suppresses floating of the document 7 at the second image reading sensor 19 and also serves as a white reference member for acquiring shading data at the second image reading sensor 19 .
A conventional automatic document feeder 3 is configured by these components.

In the above-described conventional automatic document feeder 3, as shown in the column of "Problems to be Solved by the Invention", for example, the leading end of the automatic document feeder 3 is bent or broken without correction after the staple is removed. A document has a problem that it cannot pass between the second image reading sensor 19 and the white reference roller 48 and a document transport jam occurs. In addition, even if the document can pass through, there is a gap between the surface of the document and the second image reading sensor 19, which causes the second image reading sensor 19 to be out of focus, resulting in a problem that the document cannot be read accurately. be.
The configuration of the present invention for solving such problems will be described below.

FIG. 4 shows the essential parts of an automatic document feeder 3A according to one embodiment of the present invention. Compared with the automatic document feeder 3 described above, the automatic document feeder 3A has a white roller supported by a shaft extending in the width direction of the second image reading sensor 19 as a document feeder in place of the white reference roller 48 . The use of a reference roller 66, the use of an eccentric cam 67 as a displacement means , the use of a guide member 68 along the width direction of the second image reading sensor 19, the leading edge of the document 7 conveyed by the discharge sensor 40, and the They are different in that they are used as document detection means for detecting the trailing edge, and the other configurations are the same. Note that the reading device 2 and the automatic document feeder 3A constitute an automatic document reading device 6A.

The white reference roller 66 is attached to the support shaft 49 and is driven to rotate by a driving motor 50 connected to the support shaft 49 and serving as a transport driving means. An urging force by an urging means (not shown) acts on the support shaft 49, and the white reference roller 66 is pressed against the second image reading sensor 19 with a predetermined pressing force by this urging force, and the contact shown in FIG. occupy a position The drive motor 50 , which is a stepping motor that can rotate in both forward and reverse directions, has its operation controlled by the controller section 60 .
An eccentric cam 67 is attached to the support shaft 49 via a one-way clutch (not shown). Due to the action of a one-way clutch (not shown), the eccentric cam 67 rotates together with the support shaft 49 when the support shaft 49 rotates counterclockwise in FIG. 4, and the support shaft 49 rotates clockwise in FIG. It is configured so that it does not rotate when The eccentric cam 67 has a large-diameter portion 67a. When the large-diameter portion 67a contacts the second image reading sensor 19, the support shaft 49 is moved downward in FIG. A predetermined gap is formed between the sensor 19 and the white reference roller 66 , and as shown in FIG . The eccentric cam 67 is arranged at a position outside the transport path of the document 7 in the width direction of the document 7 so that the transport of the document 7 is not hindered even if the outer shape of the eccentric cam 67 comes into contact with the second image reading sensor 19 . is configured to

The guide member 68 is a member that guides the leading edge of the transported document 7 between the second image reading sensor 19 and the white reference roller 66 , and is raised and lowered by the raising and lowering means 69 . The guide member 68 has a first guide position corresponding to the contact position of the white reference roller 66 near the second image reading sensor 19 shown in FIG. 4, and a second image reading sensor 19 shown in FIG. A second position spaced apart from the sensor 19 and corresponding to the spaced position of the white reference roller 66 is selectively occupied. As the lifting means 69, a known structure such as a rack and pinion mechanism or a pulley pair and belt mechanism is applied. The lifting means 69 has a drive motor, the operation of which is controlled by the controller section 60 .

Based on the above configuration, the operation of the automatic document feeder 3A will be described below with reference to the flow chart shown in FIG.
When a start switch (not shown) is turned on by the operator of the copying machine 1, the reading operation of the document 7 is started in the same manner as described above (ST01). In the initial state before starting the reading operation, in the automatic document feeder 3A, the large-diameter portion 67a of the eccentric cam 67 occupies a position where it does not come into contact with the second image reading sensor 19, and the white reference roller 66 moves its peripheral surface to the second position. 2 occupies the contact position shown in FIG. Further, the guide member 68 occupies the guide position shown in FIG. 4 (ST02).

When the document 7 on the document table 32 is conveyed and its leading edge is detected by the abutment sensor 12 (ST03), the driving motor 50 is operated to rotate the white reference roller 66 counterclockwise in FIG. At the same time, the eccentric cam 67 to which driving force is transmitted by a one-way clutch (not shown) is rotated in the same direction. When it is determined that the large-diameter portion 67a has come into contact with the second image reading sensor 19 from the number of steps of the driving motor 50, the rotation of the driving motor 50 is stopped, and the white reference roller 66 moves its peripheral surface toward the second image reading sensor. 19 is occupied (ST04).
At this time, the elevating means 69 is operated simultaneously with the operation of the drive motor 50 to move the guide member 68 occupying the guide position to the separated position shown in FIG. 5 (ST05).

Thereafter, the document 7 is conveyed in the same manner as described above, and after the discharge sensor 40 detects the leading edge of the document 7 as shown in FIG. 66 is recognized by the controller unit 60 from the number of steps of the driving motor, which is a stepping motor used in any of the conveying means for conveying the document 7 (ST06). Then, the white reference roller 66 is driven to rotate counterclockwise in FIG. The eccentric cam 67 to which the driving force is transmitted by the one-way clutch is also rotationally driven in the same direction. When it is determined that the large-diameter portion 67a is separated from the second image reading sensor 19 by the number of steps of the drive motor 50, the rotation of the drive motor 50 is stopped, and the white reference roller 66 is moved to the peripheral surface as shown in FIG. to the second image reading sensor 19 (ST07).
At this time, the elevating means 69 is operated simultaneously with the operation of the drive motor 50 to move the guide member 68 occupying the spaced position to the guide position shown in FIG. 7 (ST08).

The white reference roller 66 occupies the contact position, the guide member 68 occupies the guide position, and the automatic document feeder 3A enters the state shown in FIG. It is rotationally driven in the rotation direction (ST09). At this time, the eccentric cam 67 does not rotate due to the action of a one-way clutch (not shown), and the original document 7 is conveyed downstream while being in contact with the second image reading sensor 19 due to the rotation of the white reference roller 66. The reading operation of the document 7 is performed by the reading sensor 19 (ST10).
After that, when the read document is discharged onto the discharge tray 46 by the discharge roller pair 45, the driving motor 50 is operated to rotate the white reference roller 66 counterclockwise in FIG. 67 is returned to the initial position shown in FIG. 4, a series of operations is completed, and the automatic document feeder 3A is put into the standby state again (ST11). By detecting the trailing edge with the discharge sensor 40, the position shown in FIG. 5 can be set as the initial position.

In the automatic document feeder 3A described above, the white reference roller 66 is positioned at the spaced position before the document 7 is conveyed, and based on the signal from the discharge sensor 40, the leading edge of the document 7 is detected by the second image reading sensor 19 and the white reference. After passing the contact position with the roller 66, the eccentric cam 67 displaces the white reference roller 66 to the contact position. With this configuration, as shown in FIGS. 6 and 7, even if the leading edge of the document 7 has a deformed portion 7a that is curved or folded, the deformed portion is formed when the white reference roller 66 occupies the spaced position. Since the document 7a passes through the contact position, jamming of the deformed portion 7a at the contact position is prevented, and the document 7 is reliably prevented from being jammed. Since they are brought into contact with each other, accurate document reading can be performed.

Further, the eccentric cam 67 is used as a displacement means for displacing the white reference roller 66 between the contact position and the separated position, and the eccentric cam 67 is arranged near the white reference roller 66, so that the construction is simple and space saving. , the white reference roller 66 can be displaced, and cost reduction and space saving can be achieved.
In addition, since the drive motor 50 has a one-way clutch and the eccentric cam 67 is rotationally driven by the drive motor 50, the white reference roller 66 and the eccentric cam 67 can be driven by the single drive motor 50. can be reduced to achieve cost reduction and space saving.

In the above embodiment, the material of the eccentric cam 67 is not mentioned, but the eccentric cam 67 does not generate frictional noise or vibration, and the reading exit roller pair 18 on the upstream side of the eccentric cam 67 or the exit roller pair 20 on the downstream side of the eccentric cam 67 is used. By using a material with excellent slidability, wear resistance, self-lubricating properties, high-speed sliding properties, noise resistance, durability, etc. can be improved, and usability can be greatly improved.
Further, since the guide member 68 for guiding the transport of the document 7 can be displaced between the guide position and the separated position, even if the leading edge of the document 7 has a deformed portion 7a, the transport jam of the document 7 can be reliably prevented. It is possible to reliably guide the transport of the document 7 while preventing the document 7 from being overwhelmed, thereby improving the transportability of the document 7 .

In the above embodiment and each modified example, an example of using a full-color copier 1 as an image forming apparatus has been shown, but the image forming apparatus is not limited to this, and may include printers, facsimiles, multi-function machines, monochrome machines such as these, and the like. The present invention can also be applied to In each of the embodiments, the transfer sheet S is used as a recording medium on which an image is formed. Art paper, etc.), tracing paper, OHP sheet, OHP film, resin film, etc., and any material can be used as long as it has a sheet shape, image formation is possible, and folding processing is possible.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to such specific embodiments, and unless otherwise limited in the above description, the scope of the present invention set forth in the appended claims. Various modifications and changes are possible within the scope of the gist.
The effects described in the embodiments of the present invention merely exemplify the most suitable effects resulting from the present invention, and the effects of the present invention are limited to those described in the embodiments of the present invention. isn't it.

1 Image forming apparatus (copier)
2 reading device 3A automatic document feeder 5 image forming section 6A automatic document reading device 7 document 19 image reading means (second image reading sensor)
26 contact glass 40 document detection means (discharge sensor)
50 transport driving means (driving motor)
66 Document transport means (white reference roller)
67 displacement means (eccentric cam)
68 guide member

JP 2014-3385 A

Claims (6)

an image reading means for reading an image of the document being conveyed;
document conveying means arranged opposite to the image reading means for conveying a document to be read by the image reading means;
displacement means for displacing the document conveying means between a contact position in contact with the image reading means and a separation position at a predetermined distance from the image reading means;
a document detecting means arranged upstream of the image reading means in a document conveying direction and capable of detecting an edge of the conveyed document ;
a guide member that guides the transport of the document on the upstream side of the contact position in the document transport direction ;
The document conveying means is positioned at the separated position, and after the leading edge of the document passes through the opposing position between the image reading means and the document conveying means based on the detection signal from the document detecting means, the displacement means moves the document. displacing the conveying means to the contact position ;
The automatic document feeder, wherein the guide member is displaceable in a direction perpendicular to the document feed direction between a first position corresponding to the contact position and a second position corresponding to the separation position. The automatic document feeder according to claim 1,
An automatic document feeder, wherein said displacement means is a cam, and said cam is arranged on said document feed means. The automatic document feeder according to claim 2,
An automatic document feeder , comprising a feed drive means having a one-way clutch, wherein said cam is rotationally driven by said feed drive means. The automatic document feeder according to claim 2 or 3,
The automatic document feeder, wherein the cam is made of a member having excellent slidability which does not generate frictional noise and frictional vibration. 5. An automatic document feeder comprising: an automatic document feeder according to claim 1; a contact glass on which a document is placed; and a reader for reading an image of the document on the contact glass. reader. An image forming apparatus comprising: the automatic document reading apparatus according to claim 5; and an image forming section for forming an image.

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