JP2019199352A - Manuscript feeding device and image reading device - Google Patents

Abstract

To provide a manuscript feeding device that can restrict occurrence of feeding failure.SOLUTION: The invention includes: a device main body that has a loading part for loading sheets provided thereon; a feeding part that is provided on the loading surface of the loading part and feeds sheets; a separation part that is positioned facing the feeding part and forms a nip between it and the feeding part; and a transportation part that transports sheets separated between the feeding part and the separation part. The transportation part includes: a rotational axis; a first roller part and a second roller part that are provided with a gap made in the axial direction of the rotational axis; a first one-way clutch part that is provided between the first roller part and the rotational axis; and a second one-way clutch part that is provided between the second roller and the rotational axis. A plurality of first grooves that extend in the roller rotating direction are provided on the circumferences of the first roller part and the second roller part, and the separation part has a rotational axis and a plurality of second grooves that extend in the axial direction of the rotational axis.SELECTED DRAWING: Figure 12

Description

  The present invention relates to a document feeder such as a document scanner, a facsimile, a printer, a copying machine, and the like.

As a conventional document feeder, for example, a plurality of rollers are rotatably mounted on a feeding shaft via a one-way clutch, and a predetermined conveying load is supplied by contacting the feeding roller. 2. Description of the Related Art A medium supply device is known that includes a brake unit that acts on a medium that has entered between a feed roller (see Patent Document 1).

JP2013-184818A

  In the medium supply device disclosed in Patent Document 1 described above, since a plurality of rollers constituting the feed roller individually operate by each one-way clutch, the medium is separated and fed one by one between the feed roller and the brake means. When feeding, it is possible to prevent the skew chaining of the media.

  However, in the conventional medium transport apparatus, the plurality of feed rollers do not always stop at the same position with respect to the brake means, and therefore friction with the document depends on the surface state of the feed roller. For this reason, even if a one-way clutch is individually incorporated in each roller of the feeding roller as in Patent Document 1, the state of friction with the document varies depending on the roller, so that the operation of separation feeding is not stable, There is a possibility that double feed and skew chain of sheets cannot be reduced sufficiently.

In view of the above, the document feeder according to the present invention is
An apparatus main body provided with a stacking unit for stacking a plurality of sheets;
A feeding unit that is disposed on a stacking surface side of the stacking unit and feeds sheets;
A separation unit that is disposed to face the feeding unit and forms a nip with the feeding unit;
A conveying unit that conveys the sheet separated between the feeding unit and the separating unit,
The feeding unit is provided between a rotating shaft, a first roller unit and a second roller unit provided with a gap in an axial direction of the rotating shaft, and the first roller unit and the rotating shaft. A first one-way clutch portion, and a second one-way clutch portion provided between the second roller and the rotation shaft. A roller is disposed on the circumference of the first roller portion and the second roller portion. A plurality of first grooves extending in the rotational direction;
The separation unit includes a rotation shaft and a separation roller having a plurality of second grooves extending in an axial direction of the rotation shaft.

  According to the present invention, the frictional state with the document is the same regardless of the roller position, and the grip force between the roller and the document can be increased, so that a more stable feeding operation can be realized and the sheet skew can be realized. Row chaining can be prevented more effectively.

1 is a schematic cross-sectional view (conveyance state) of a document feeder according to an embodiment. 1 is a schematic sectional view of a document feeder according to an embodiment (standby state). FIG. 3 is an enlarged view of a main part of a feeding unit of the document feeding device according to the embodiment. The perspective view of the feeding part which concerns on one Embodiment. Sectional drawing of the feeding part which concerns on one Embodiment. The other sectional view of the feeding part concerning one embodiment. The block diagram of the control unit which concerns on one Embodiment. 6 is a flowchart illustrating an operation of the document feeder according to the embodiment. Conventional feeding roller. The feed roller which concerns on one Embodiment. The separation roller which concerns on one Embodiment. Sectional drawing of the feeding part and separation part which concern on one Embodiment. The separation roller which concerns on other embodiment.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic diagram of a document feeder A according to the first embodiment of the present invention.

<Device configuration>
The document feeder A is a device having a document transport system such as an image reading device (scanner or the like) that reads an image of a document, a printing device (printer or the like) that prints on a document, or a combination machine that combines these. This embodiment will be described as an example applied to an image reading apparatus.

  The document feeder A of the present embodiment reads one or a plurality of documents S stacked on the mounting table 1 (stacking unit) one by one in the apparatus main body by a route RT, reads the image, and discharges the discharge tray. 2 is an apparatus for discharging. The document S to be read is, for example, a sheet such as OA paper, a check, a business card, or a card, and may be a thick sheet or a thin sheet. Examples of the cards include an insurance card, a driver's license, and a credit card.

<Feeding department>
As shown in FIG. 1, a first transport unit 10 serving as a feeding unit that feeds a document S along a path RT is provided on the document stacking surface side of the stacking table 1. In the case of the present embodiment, the first transport unit 10 includes a feeding roller 110 and a separation roller 120 disposed to face the feeding roller 110, and one document S on the mounting table 1 is placed in the feeding direction D <b> 1. Transport sequentially. In contrast to the conveyance state shown in FIG. 1, FIG. 2 shows a standby state, and the feeding roller 110 and the separation roller 120 are stopped. FIG. 3 shows an enlarged view of the main part of the feeding unit. In the present embodiment, the feeding direction D1 is inclined with respect to the placement surface of the document feeder A at a predetermined angle, and is fed by the weight of the document S placed on the placement table 1. A document is supplied to the feeding unit.

  The feed roller 110 is supported by the feed roller shaft 11b via the one-way clutch 11a. The feeding roller 110 is driven via the one-way clutch 11a when the driving force of the motor 3 is transmitted to the feeding roller shaft 11b via a drive transmission unit (not shown). When the feed roller shaft 11b rotates in the feed direction (solid arrow D2 direction in FIG. 1) by driving the motor 3, the one-way clutch 11a meshes with the feed roller shaft 11b, and the feed roller 110 rotates in the feed direction. . The conveyance speed of the feeding roller 110 is set to be slower than the conveyance speed of the conveyance roller 21 described later. Therefore, when the fed document S reaches the transport roller 21 and the transport speed of the document S increases, the one-way clutch 11a and the feed roller shaft 11b are disengaged, and the feed roller 110 rotates with the transport document S. The motor 3 rotates faster than the rotation speed by the drive transmission from the motor 3.

  That is, the transported document S that has reached the transport roller 21 receives a transport force from the transport roller 21 that is set to have a large speed difference from the feed roller 110, and is thus brought into contact with the feed roller 110 and the feed roller 110. Then, the separation roller 120 is pulled out.

  As shown in FIG. 3, the feeding roller 110 has two feeding roller portions (first roller portion and second roller portion) 11 formed of, for example, a rubber material or the like individually on the wheel portion 111. The wheel portion 111 is individually supported by a feed roller shaft (rotary shaft) 11b via a one-way clutch 11a. That is, the one-way clutch 11a of the present embodiment is provided for each of a plurality of feed roller portions 11 that are separately provided with a gap on the left and right in the axial direction of the feed roller shaft 11b, and is independently independent on the left and right. The first one-way clutch part and the second one-way clutch part. Therefore, in the present embodiment, even if the transported document S that has reached the transport roller 21 is pulled out from between the feed roller 110 and the separation roller 120 in a skewed state, the subsequent one-way clutch 11a operates, The skew chain of the document S is suppressed (hereinafter referred to as “the skew chain suppression effect”). Details of the feeding roller 110 of this embodiment will be described later.

  Further, each of the feeding roller 110 and a separation roller 120 described later is one unit, and is a unit that can be attached to and detached from the apparatus. Therefore, maintenance is easy and the unit can be replaced when the roller surface is worn.

<Separation part>
The separation roller 120 disposed to face the feeding roller 110 is a roller for separating the documents S one by one, and is in pressure contact with the feeding roller 110 with a constant pressure. In order to ensure this pressure contact state, the separation roller 120 is rocked and supported by a separation rocking member 121 as shown in FIG. The separation rocking member 121 is supported so as to be rotatable about a shaft portion 121a, and a biasing force is applied by a compression spring 122 so that the separation roller 120 is pressed against the feeding roller 110.

As shown in FIG. 1, the separation roller 120 receives a rotational driving force from the motor 3 via the torque limiter 12a and is rotationally driven in the direction of the solid line arrow D3. Since the transmission of the driving force is restricted by the torque limiter 12a, the separation roller 120 rotates in a direction (a broken line arrow D4 direction) that rotates with the feeding roller 110 when it is in contact with the feeding roller 110. As a result, when a plurality of originals S are conveyed to the pressure contact portion between the feeding roller 110 and the separation roller 120, the two or more originals S are blocked so as not to be conveyed downstream except one. Details of the separation roller 120 of this embodiment will be described later.

<Document detection structure of feeding unit>
In order to detect the presence or absence of the document S on the mounting table 1, a document detection sensor 90 is provided upstream of the feeding roller 110 as shown in FIG. The document detection sensor 90 is a lever-type sensor that is provided so as to hang down from the upper side in the vertical direction under its own weight. As another example, optical sensors such as medium detection sensors 50 and 60 described later may be used.

  As shown in FIG. 4, the document detection sensor 90 is provided at a position between the plurality of feeding rollers 110. The document detection sensor 90 is pivotally supported by a detection sensor shaft 90a and is suspended by its own weight. In order to be able to retract around the detection sensor shaft 90a regardless of the type of the document S that arrives, it is configured to be as light as possible and almost free from friction due to friction and the like.

<Feeding roller guide>
A feeding roller guide 17 is provided on the upstream side of the document detection sensor 90. The feed roller guide 17 is supported by a guide shaft 17a provided on the upstream side of the feed roller 110, and extends toward the downstream side in the feed direction. The feeding roller guide 17 is moved in a direction orthogonal to the feeding direction (in the thickness direction of the transported document) so that the tip is moved from the feeding roller 110 side to the separation roller 120 side by the guide urging means 17b shown in FIG. When the document S is energized and the document S does not exist on the mounting table 1, the tip protrudes from the outer periphery of the feeding roller 110 when viewed from the axial direction of the feeding roller 110 (direction shown in FIG. 6). In a state of being urged to the position, it is positioned by a not-shown abutting portion.

  When a plurality of documents S are placed on the placing table 1 by the feeding roller guide 17, the feeding roller guide 17 moves toward the feeding roller 110 against the urging means as shown in FIG. As shown in FIG. 6, when the number of originals S is small, especially when only one thin paper S is placed on the placement table 1, and so on. The document is urged toward the separation roller 120 by the feeding roller guide 17 so that the document S does not come into contact with the feeding roller 110 while the leading edge of the document S is in sliding contact with the feeding roller guide 17. . With this configuration, when the document S is set on the mounting table 1, it is possible to prevent the document S from being caught by the feeding roller 110 and being unable to be set at a predetermined setting position when the document S is small.

  In the present embodiment, as shown in FIG. 4, the leading end on the separation roller 120 side (downstream in the feeding direction) of the feeding roller guide 17 is located between both sides of the feeding roller 110 and between the feeding rollers 110. Since the feeding roller guide 17 is provided so as to be arranged, the leading edge of the document S is more likely to come into contact with the feeding roller 110 when the number of document bundles on the mounting table 1 is reduced. It can be surely prevented.

  Further, the feeding roller guide 17 can locally lift the original S and apply the stiffness to the original S. According to the feeding roller guide 17 in the present embodiment, the plurality of feeding roller guides 17 urge the document S in the direction of lifting the document S on the upstream side of the feeding roller 110, and perform feeding in a state in which the stiffness is applied. The document S can enter the nip between the roller 110 and the separation roller 120.

  In the present embodiment, a feed roller cover 18 shown in FIG. 4 is provided so as to cover the feed roller 110 and the feed roller guide 17. A guide shaft 17a and a guide urging means 17b of the feed roller guide 17 are attached to the opposite side (the lower side in FIG. 5) of the feed roller cover 18 to which the document comes into sliding contact. The unit 18 and the feeding roller guide 17 constitute an integral unit.

  By removing the feeding roller cover 18, the shaft and bearing of the feeding roller 110 are exposed, and the feeding roller 110 can be detached from the document feeding apparatus A. The feeding roller cover 18 is provided with a concave storage portion at a position where a leading end of a document stopper 14 described later is stored.

<Pick arm / document stopper>
As shown in FIG. 1, the document feeder A includes a pick roller 131 that presses the document S against the feed roller 110 on the upstream side of a nip where the feed roller 110 and the separation roller 120 are in contact (hereinafter referred to as a feed nip), A pick arm 13 that pivotally supports the pick roller 131 is provided. The pick roller 131 assists the feeding of the document S by increasing the conveying force of the document S by pressing the document S against the feeding roller 110.

  The pick arm 13 is supported by the apparatus A so that the shaft portion 13a of the pick arm 13 is rotatable, and is urged by a spring (not shown) in a direction in which the pick roller 131 is pressed against the feeding roller 110. The pick arm 13 is described below in a pressure contact position where the pick roller 131 shown in FIG. 1 presses the document S against the feeding roller 110 and a retreat position where the pick roller 131 shown in FIG. 2 is retracted from the feeding roller 110. It can be moved by the driving force of the motor 4.

  As another configuration for assisting the feeding of the feeding roller 110, there is a configuration in which another feeding roller is provided upstream of the feeding roller 110. However, the configuration of FIG. Cost reduction can be realized.

  The document feeder A includes a document stopper 14 as shown in FIG. In the state shown in FIG. 2, the document stopper 14 has a role of blocking the stacked document bundle by projecting its tip toward the conveyance path.

The document stopper 14 is configured such that the shaft portion 14a of the document stopper 14 is rotatably supported by the apparatus A, and an opening position that opens the conveyance path so that the document S shown in FIG. 1 can be fed, and the feeding shown in FIG. It is possible to move to a closing position where the conveyance path is closed so that the document bundle does not enter the nip. FIG. 2 shows a standby state of the document feeder A. In this state, the document bundle can be set on the mounting table 1 by abutting the leading edge of the document bundle against the document stopper 14.

  The pick arm 13 and the document stopper 14 are driven by the motor 4 via a drive transmission mechanism (not shown). When the motor 4 drives the predetermined number of pulses in the forward direction, the pick arm 13 moves to the pressure contact position and the document stopper 14 moves to the opening position, and when the motor 4 drives the predetermined number of pulses in the reverse direction, the pick arm 13 Moves to the retracted position, and the document stopper 14 moves to the closing position. When the motor 4 drives the predetermined number of pulses in the reverse direction, the pick arm 13 moves to the retracted position and the document stopper 14 moves to the closing position. Here, the positive direction is a direction in which conveyance rollers 21 and 31 described later are rotated so as to convey the document S in the feeding direction D1 in FIG.

The motor 4 is a drive source that drives the transport rollers 21 and 31, and is provided as a motor different from the motor 3 that drives the feeding roller described above. As a result, if the motors 3 and 4 are individually controlled, highly accurate feeding and conveying control can be realized by performing separate control for feeding driving and conveying driving.

<Conveying structure>
As shown in FIG. 1, the second transport unit 20 as a transport mechanism on the downstream side in the feeding direction of the first transport unit 10 includes a transport roller 21 and a driven roller 22 driven by the transport roller 21. The document S conveyed from the first conveying unit 10 is conveyed downstream. A driving force is transmitted from the motor 4 to the transport roller 21 and is driven to rotate in the direction of the solid arrow in the figure. The driven roller 22 is brought into pressure contact with the conveying roller 21 at a constant pressure, and rotates with the conveying roller 21.

  The third transport unit 30 on the downstream side in the feeding direction from the second transport unit 20 includes a transport roller 31 and a driven roller 32 that is driven by the transport roller 31 and is transported from the second transport unit 20. The received original S is conveyed to the discharge tray 2. That is, the third transport unit 30 functions as a discharge mechanism. A driving force is transmitted from the motor 4 to the transport roller 31 and is driven to rotate in the direction of the solid arrow in the figure. The driven roller 32 is brought into pressure contact with the conveying roller 31 at a constant pressure, and rotates around the conveying roller 31.

<Double feed detection>
The double feed detection sensor 40 disposed between the first transport unit 10 and the second transport unit 20 is in a case where the documents S such as paper are brought into close contact with each other due to static electricity or the like and have passed through the first transport unit 10 (that is, This is an example of a detection sensor (a sensor for detecting the behavior and state of the document S) for detecting this in the case of a double-feed state in which the sheets are conveyed in an overlapping manner.

Various sensors can be used as the double feed detection sensor 40, but in the case of the present embodiment, it is an ultrasonic sensor, and includes an ultrasonic transmission unit 41 and a reception unit 42, and a document S such as paper. Double feed is detected based on the principle that the attenuation amount of the ultrasonic wave passing through the document S is different between when the paper is being fed one by one and when it is being transported one by one.

<Registration sensor>
The medium detection sensor 50 arranged on the downstream side in the feeding direction from the double feed detection sensor 40 is upstream from the second conveyance unit 20 and upstream from the first conveyance unit 10. Detection sensor (a sensor for detecting the behavior and state of the document S). The position of the document S transported by the first transport unit 10, specifically, the position of the document S at the detection position of the medium detection sensor 50. Detect whether the end has reached or passed.

Various media detection sensors 50 can be used. In the case of the present embodiment, the medium detection sensor 50 is an optical sensor. The medium detection sensor 50 includes a light emitting unit 51 and a light receiving unit 52. The document S is detected based on the principle that (the amount of received light) changes.

  In the case of this embodiment, when the leading edge of the document S is detected by the medium detection sensor 50, the medium detection is performed so that the document S has reached a position where the double feed detection sensor 40 can detect double feed. The sensor 50 is provided on the downstream side in the vicinity of the double feed detection sensor 40. The medium detection sensor 50 is not limited to the optical sensor described above. For example, a sensor (image sensor or the like) that can detect the edge of the document S may be used, or a lever-type sensor that protrudes in the path RT. But you can.

  A medium detection sensor 60 different from the medium detection sensor 50 is disposed on the upstream side of the image reading unit 70. This is an example of a downstream detection sensor disposed downstream of the second transport unit 20 and detects the position of the document S transported by the second transport unit 20.

Various media detection sensors 60 can be used. In the case of the present embodiment, the medium detection sensor 60 is an optical sensor similar to the medium detection sensor 50, and includes a light emitting unit 61 and a light receiving unit 62, and reaches the document S. Alternatively, the document S is detected based on the principle that the received light intensity (received light amount) changes due to passage.

<CIS layout>
The image reading unit 70 on the downstream side of the medium detection sensor 60 is, for example, optically scanned, converted into an electric signal and read as image data, and internally includes a light source such as an LED, an image sensor, and a lens array. Etc. In the present embodiment, one image reading unit 70 is disposed on each side of the path RT, and is configured by a contact image sensor (CIS) that reads the front and back surfaces of the document S.

<Explanation of block diagram>
The control unit 80 will be described with reference to FIG. FIG. 7 is a block diagram of the control unit 80 of the document feeder A.

  The control unit 80 includes a CPU 81, a storage unit 82, an operation unit 83, a communication unit 84, and an interface unit 85. The CPU 81 controls the entire document feeder A by executing a program stored in the storage unit 82. The storage unit 82 includes, for example, a RAM, a ROM and the like. The operation unit 83 includes, for example, a switch, a touch panel, and the like, and accepts an operation from the operator.

  The communication unit 84 is an interface that performs information communication with an external device. When a PC (personal computer) is assumed as the external device, examples of the communication unit 84 include a USB interface and a SCSI interface. In addition to such a wired communication interface, the communication unit 84 may be a wireless communication interface, and may include both wired communication and wireless communication interfaces.

  The interface unit 85 is an I / O interface that inputs and outputs data with the actuator 86 and the sensor 87. The actuator 86 includes the motor 3 and the motor 4. The sensor 87 includes a double feed detection sensor 40, medium detection sensors 50 and 60, an image reading unit 70, a document detection sensor 90, and the like.

<Driving by receiving start instruction from PC>
A basic operation of the document feeder A will be described. For example, when the control unit 80 receives an image reading start instruction from an external personal computer to which the document feeder A is connected, the control unit 80 starts driving the first to third transport units 10 to 30. The documents S stacked on the mounting table 1 are conveyed one by one from the document S located at the bottom. The image reading start instruction may be executed by pressing a start button provided in the document feeder A.

<Start reading according to the output of the registration sensor>
The control unit 80 starts reading an image of the document S conveyed by the second conveying unit 20 by the image reading units 70 and 70 at a timing based on the detection result of the medium detection sensor 60, and primarily reads the read image. Memorize and send to external PC sequentially. The document S from which the image has been read is discharged to the discharge tray 2 by the third transport unit 30, and the image reading process for the document S is completed.

<Flow of feeding / conveying>
Next, the operation flow of feeding / conveying will be described with reference to FIG.

  In step S <b> 1, the control unit 80 receives an image reading start instruction from, for example, an external personal computer to which the document feeder A is connected.

  In step S <b> 2, the control unit 80 determines the presence or absence of the document S on the mounting table 1 by the document detection sensor 90.

  In step S3, when the control unit 80 determines that the document S is not present by the document detection sensor 90, a notice that there is no document S is displayed on an external personal computer or the like, and the process is terminated without feeding / conveying.

  In step S <b> 4, when the control unit 80 determines that the document S is on the placement table 1 by the document detection sensor 90, the motor 4 is driven in the forward direction. At this time, the pick arm 13 is moved to the press contact position, and the document stopper 14 is moved to the opening position.

  In step S <b> 5, the control unit 80 drives the motor 3, rotates the feeding roller 110 in the direction in which the document S is fed (forward direction), and feeds the document S.

  In step S6, it is detected that the leading edge of the conveyed document S has passed the medium detection sensor 50, and then in step S7, it is detected that the leading edge of the conveyed document S has passed the medium detection sensor 60.

  At this time, since the transport document S has reached the second transport unit 20 because the leading edge of the transport document S has passed through the medium detection sensor 60, the transport document S remains even if the first transport unit 10 is stopped. Since it is conveyed by the 2nd conveyance part 20, the control part 80 stops the motor 3 by step S8.

  On the other hand, from the time when the leading edge of the document S reaches the medium detection sensor 60, image reading of the document S is started after a predetermined time for reaching the image reading unit 70.

  In step S9, it is detected that the trailing edge of the conveyed document S has passed through the medium detection sensor 60. After a predetermined time has elapsed from this time, the image reading of the document S is terminated. Thus, a series of reading operations for one document S is completed.

  In step S <b> 10, the control unit 80 determines the presence or absence of the document S on the table 1 by the document detection sensor 90. If it is determined that the document S is present, the process proceeds to step S5, where the document S is conveyed and the image is read.

  If the document detection sensor 90 determines in step S10 that there is no document S on the mounting table 1, the control unit 80 stops the motor 4 in step S11. At this time, the motor 4 is stopped after a lapse of a predetermined time so that the document that has passed through the medium detection sensor 60 is discharged by the third transport unit 30. When the motor 4 does not drive the third transport unit, the motor 4 may be stopped immediately.

  Thereafter, in step S12, the control unit 80 drives the motor 4 in the reverse direction by a predetermined number of pulses and then stops. At this time, the pick arm 13 is moved to the retracted position and the document stopper 14 is moved to the closing position to stop. This completes the feeding / conveying operation.

  With the above operation flow, the conveyance control for feeding the next document S is performed using the medium detection sensor 60 as a trigger. As a result, since a predetermined sheet interval is provided at the reading position of the image reading unit 70, the document S can be stably conveyed continuously.

<Feeding roller>
FIG. 9 shows a conventional feeding roller, and FIG. 10 shows a feeding roller 110 in this embodiment. The difference between the conventional feeding roller and the feeding roller 110 in this embodiment is that two feeding roller portions (first roller portion and second roller portion) formed of a rubber material or the like as is apparent from FIGS. 9 and 10. It is in the shape of a roller part) 11.

In the case of FIG. 9A, by repeatedly performing the feeding operation, the roller surface is covered with dust or the like adhering to the surface of the conveyed document, and the coefficient of friction with the document is lowered. Therefore, there is a possibility that the roller slips with respect to the original, and the feeding operation is not stable, which is likely to cause non-feeding.

  Further, as shown in FIG. 9B, in order to prevent dust and the like from adhering to the roller surface, there may be a configuration in which a plurality of grooves are provided in the rotation axis direction on the roller surface circumference. In this case, since the deposits escape into the groove of the roller, the friction between the roller and the document is kept within a certain range, and a stable feeding operation can be performed without slipping.

  However, when the independent one-way clutch 11a is provided for a plurality of feed roller portions 11 provided separately on the left and right as in this embodiment, the left and right rollers are moved by the operation of the individual one-way clutch 11a. Operate separately. Therefore, as shown in FIG. 9C, a phase difference a is generated between the left and right rollers. As a result, the contact state with the original differs between the left and right rollers, so that the balance of the left and right friction coefficients is lost, and there is a possibility that the effect of suppressing the skew chain cannot be fully exhibited.

  Therefore, as shown in FIG. 10, the feed roller 110 in the present embodiment is configured to have a plurality of grooves extending in the roller rotation direction on the roller surface circumference. As shown in FIG. 9B, by providing a groove on the roller surface, the deposits escape to the roller groove, so that the friction between the roller and the document is kept within a certain range, and a stable feeding operation without slip occurs. Yes.

  Further, by providing the groove in the roller rotation direction instead of the axial direction, the phase shift between the left and right rollers as shown in FIG. 9C does not occur, so the contact state with the document is the same regardless of the roller. . As a result, the balance between the left and right friction coefficients is maintained, so that the effect of suppressing the skew chain can be sufficiently exhibited. In this embodiment, the grooves are provided in the roller rotation direction, but may be provided so as to extend obliquely with respect to the roller rotation direction. Further, the shape and number of grooves and the depth of the grooves are not particularly limited as long as the grooves extend in the roller rotation direction.

<Separation roller>
FIG. 11 shows a separation roller in this embodiment. In the present embodiment, a plurality of grooves extending in the roller axial direction are provided on the circumference of the roller surface of the separation roller 120. Similar to the feeding roller 110, the separation roller 120 repeatedly performs the feeding operation, so that the roller surface is covered with dust or the like adhering to the surface of the conveyed document, and the coefficient of friction with the document decreases. Therefore, there is a possibility that the roller slips with respect to the original, and the feeding operation is not stable, which is likely to cause non-feeding.

  By providing the groove as in the present embodiment, the deposits escape into the groove of the roller, so that the friction between the roller and the document is kept within a certain range, and a stable feeding operation can be performed without slipping. Further, the separation roller 120 of the present embodiment is provided with separation roller portions 12 at both ends of a separation roller shaft 12b (roller shaft member) formed of a single member, and the separation roller shaft 12b and the separation roller portion. Since the rollers 12 rotate together, the left and right roller grooves can be provided in the same phase, so that the left and right balance of the friction coefficient with respect to the original can be maintained, and the effect of suppressing the skew chain can be sufficiently exhibited.

  In addition to preventing dust from adhering to the roller surface, there is an effect of improving document separation performance. FIG. 12 shows a cross-sectional view of the feeding unit of this embodiment. When grooves are provided as in the present embodiment, there are a plurality of corners 12c on the surface of the separation roller 120 as shown in FIG. 12, and the corners 12c are caught on the document. Therefore, compared with the case where there is no groove on the surface of the separation roller 120, the braking force applied to the document increases, so that the document can be more reliably separated than before. Further, since the degree of catching with the leading edge of the document is changed by changing the number of grooves, the braking force applied to the document can be adjusted.

  For example, when document non-feeding is likely to occur, by reducing the number of grooves, the number of corners 12c can be reduced and the braking force can be suppressed to prevent non-feeding. On the other hand, when document double feed is likely to occur, by increasing the number of grooves, the number of corners 12c can be increased and the brake force can be increased to prevent double feed.

  In this embodiment, the groove is provided on the surface of the separation roller 120 in parallel to the roller axial direction. However, the groove may be extended obliquely within the range of the feeding nip formed by the feeding roller 110 and the separation roller 120. . Further, the depth and shape of the groove are not particularly limited.

  In this embodiment, the separation roller 120 has a configuration in which a roller shaft and a plurality of roller portions are integrated. However, the present invention is not limited to this, and the separation roller 120 may be configured by only one roller portion as shown in FIG. Good.

  Further, as described with reference to FIG. 1, the separation roller 120 is in pressure contact with the feeding roller 110 at a constant pressure. The separation rocking member 121 for securing the pressure contact state is supported so as to be rotatable around the shaft portion 121a, and a biasing force is applied by the compression spring 122 so that the separation roller 120 is in pressure contact with the feeding roller 110. Is given. A biasing portion that applies a biasing force generated by the compression spring 122 to the separation roller 120 may be provided at the center of the plurality of separation roller portions 12. Taking FIG. 11 as an example, the urging force generated by the urging portion is applied to the separation roller 120 via the urged portion provided at the center of the separation roller shaft 12b of the separation roller 120.

  In this way, by applying the urging force for swinging the separation roller 120 at the central portion in the width direction of conveyance, the pressing force to the feeding roller 110 in the pressure contact state between the left and right separation roller portions 12 varies. Can be prevented.

  The present invention is not limited to the embodiment described above, and various modifications can be made without departing from the spirit of the present invention.

A Document feeder S Document 1 Placement table 2 Discharge tray 3, 4 Motor 10 First transport section 110 Feed roller 11 Feed roller section 11a One-way clutch 11b Feed roller shaft 11c Friction member 11d Cylindrical section 120 Separation roller 12 Separation Roller portion 12a Torque limiter 12b Separating roller shaft 12c Groove corner portion 13 Pick arm 14 Document stopper 20 Second conveying portion 21 Conveying roller 22 Followed roller 30 Third conveying portion 31 Conveying roller 32 Followed roller 40 Double feed detection sensors 50, 60 Medium Detection sensor 70 Image reading unit 80 Control unit 84 Communication unit 90 Document detection sensor 115 Compression spring 121 Separation rocking member

Claims (7)

An apparatus main body provided with a stacking unit for stacking a plurality of sheets;
A feeding unit that is disposed on a stacking surface side of the stacking unit and feeds sheets;
A separation unit that is disposed to face the feeding unit and forms a nip with the feeding unit;
A conveying unit that conveys the sheet separated between the feeding unit and the separating unit,
The feeding unit is provided between a rotating shaft, a first roller unit and a second roller unit provided with a gap in an axial direction of the rotating shaft, and the first roller unit and the rotating shaft. A first one-way clutch portion, and a second one-way clutch portion provided between the second roller and the rotation shaft. A roller is disposed on the circumference of the first roller portion and the second roller portion. A plurality of first grooves extending in the rotational direction;
The separation unit includes a rotation shaft and a separation roller having a plurality of second grooves extending in an axial direction of the rotation shaft. The separation roller is
The sheet fed in the feeding direction by the feeding unit is rotationally driven so as to return to the direction opposite to the feeding direction,
A first separation roller and a second separation roller respectively facing the first roller portion and the second roller portion;
The document feeder according to claim 1, further comprising a single roller shaft member that transmits a rotational driving force to each of the first separation roller and the second separation roller.   3. The document feeding device according to claim 2, wherein the grooves formed in the first separation roller and the second separation roller are provided in the same phase with respect to the roller rotation direction.   4. The document feeding apparatus according to claim 1, wherein the first groove extends obliquely with respect to a roller rotation direction of the feeding unit. 5.   The document feeder according to claim 2, wherein the second groove extends obliquely in the nip. The separation roller is rocked and supported by a rocking member, and is pressed against the feeding portion by receiving a biasing force from the rocking member.
The document feeding device according to claim 2, wherein the urging force from the swing member is exerted on the roller shaft member between the first separation roller and the second separation roller.   An image reading apparatus comprising the document feeding device according to claim 1.

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