MEDIUM FEEDING APPARATUS AND IMAGE READING APPARATUS

Abstract

A medium feeding apparatus includes a curved path that is a medium feeding path formed between a first pair of feeding rollers and a second pair of feeding rollers. The medium is transported along the curved path while being curved downward. The medium feeding apparatus further includes an accommodating portion formed outside a curve of the curved path and configured to accommodate a deformed part of the medium at the curved path. The first pair of feeding rollers is provided at a center area in a medium width direction intersecting with a medium feeding direction. The accommodating portion has a pushing member configured to push the deformed part of the medium upstream in the medium feeding direction.

Description

The present application is based on, and claims priority from JP Application Serial Number 2018-144075, filed Jul. 31, 2018, the disclosure of which is hereby incorporated by reference herein in its entirety.

BACKGROUND

1. Technical Field

Embodiments of the present disclosure relate to a medium feeding apparatus and an image reading apparatus equipped therewith.

2. Related Art

Scanners, printers and the like are equipped with a medium feeding apparatus that feeds a medium. For example, in scanners, a medium feeding apparatus is sometimes called as ADF, which is an acronym for Automatic Document Feeder. Some ADFs have a curved path structure for, after a pickup feed of a sheet of medium, transporting the medium along its curve downward to turn over the medium. An example of an ADF that has such a structure is disclosed in JP-A-8-34544.

In some ADFs, a skew is corrected by performing registration of the leading edge of a medium into alignment with a pair of resist rollers. In the skew correction process, ridge-like partial deformation occurs in the curved part of the medium. In JP-A-8-34544, the term “loop” is used for referring to the curved part of the medium, and the term “bulge” is used for referring to the ridge-like deformed part mentioned above. The ADF disclosed in JP-A-8-34544 has a pivotable guide member that pushes the bulge. This structure pushes the leading edge of the medium for edge registration into alignment with the pair of resist rollers.

When the leading edge of a medium that is skewed reaches a pair of resist rollers, the degree of deformation of a deformed part at one side that reaches the pair of resist rollers earlier than the opposite side in the width direction of the medium because of the skew tends to be greater than the degree of deformation of a deformed part at the opposite side that reaches the pair of resist rollers later. The following is a detailed explanation of this phenomenon. The upper part of FIG. 9 depicts an example of a state before the leading edge of a medium D transported toward the bottom of FIG. 9 reaches a resist roller pair 100, wherein, as illustrated therein, the medium D is skewed, that is, inclined with respect to a virtual line Lv that is in parallel with a transportation direction.

The leading edge at one side S1 of the medium in its width direction reaches a resist roller pair 100 earlier than the leading edge at the opposite side S2 because of the skew, and the degree of deformation of a deformed part H1 produced by subsequent transportation at the one side S1 tends to be greater than the degree of deformation of a deformed part H2 produced by subsequent transportation at the opposite side S2. To be exact, “the degree of deformation is greater” means that the deformed part is larger both in the transportation direction and in the height direction, in most cases.

The pivotable guide member disclosed in JP-A-8-34544 has a pivot located upstream in the transportation direction, and, if the pivotable guide member disclosed in JP-A-8-34544 is applied to the example illustrated in FIG. 9, the deformed part H1 and the deformed part H2 are pushed toward the resist roller pair 100. However, if this structure is used, it is impossible to perform proper skew correction because the deformed part H1, which is at the side that arrives earlier due to the skew, is pushed excessively and because a force of pushing the deformed part H2, which is at the side that arrives later due to the skew and is supposed to be pushed hard for the purpose of skew correction, tends to be insufficient.

SUMMARY

A medium feeding apparatus according to an aspect of the present disclosure includes: a first pair of feeding rollers configured to feed a medium downstream; a second pair of feeding rollers provided downstream of the first pair of feeding rollers; a curved path that is a medium feeding path formed between the first pair of feeding rollers and the second pair of feeding rollers, the medium being transported along the curved path while being curved downward; and an accommodating portion formed outside a curve of the curved path and configured to accommodate a deformed part of the medium at the curved path; wherein the first pair of feeding rollers is provided at a center area in a medium width direction intersecting with a medium feeding direction, and wherein the accommodating portion has a pushing member configured to push the deformed part of the medium upstream in the medium feeding direction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a medium feeding apparatus and an image reading apparatus according to an exemplary embodiment of the disclosure.

FIG. 2 is a side sectional view of a medium feeding apparatus and an image reading apparatus according to an exemplary embodiment of the disclosure.

FIG. 3 is a block diagram that illustrates a control system in a medium feeding apparatus and an image reading apparatus according to an exemplary embodiment of the disclosure.

FIG. 4 is an enlarged side sectional view of a part of a medium feeding path in a medium feeding apparatus according to an exemplary embodiment of the disclosure.

FIG. 5 is an enlarged side sectional view of a part of a medium feeding path in a medium feeding apparatus according to an exemplary embodiment of the disclosure.

FIG. 6 is an enlarged plan view of a part of a medium feeding path in a medium feeding apparatus according to an exemplary embodiment of the disclosure.

FIG. 7 is an enlarged side sectional view of a part of a medium feeding path in a medium feeding apparatus according to an exemplary embodiment of the disclosure.

FIG. 8 is a flowchart that illustrates the flow of control performed when a medium is fed.

FIG. 9 is an enlarged plan view of a part of a medium feeding path in a medium feeding apparatus according to related art.

FIG. 10 is an enlarged side sectional view of a part of a medium feeding path on which a pushing member is not provided.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following is a brief overview of the present disclosure. A medium feeding apparatus according to a first aspect of the present disclosure includes: a first pair of feeding rollers configured to feed a medium downstream; a second pair of feeding rollers provided downstream of the first pair of feeding rollers; a curved path that is a medium feeding path formed between the first pair of feeding rollers and the second pair of feeding rollers, the medium being transported along the curved path while being curved downward; and an accommodating portion formed outside a curve of the curved path and configured to accommodate a deformed part of the medium at the curved path; wherein the first pair of feeding rollers is provided at a center area in a medium width direction intersecting with a medium feeding direction, and wherein the accommodating portion has a pushing member configured to push the deformed part of the medium upstream in the medium feeding direction.

In this aspect, the accommodating portion configured to accommodate a deformed part of the medium is provided at the curved path, and the first pair of feeding rollers is provided at the center area in the medium width direction intersecting with the medium feeding direction. This structure allows the bulge of the deformed part to escape upstream in the feeding direction from the lateral side of the first pair of feeding rollers and ensures easy rotation of the medium turning on the portion of contact with the first pair of feeding rollers, thereby making it easier to correct the skew. Since the accommodating portion has the pushing member configured to push the deformed part of the medium upstream in the medium feeding direction, the medium is rotated on the portion of contact with the first pair of feeding rollers, and the skew is therefore corrected well. If the pushing member is not provided, the medium tends to cling to the outer portion of the curved path. The clinging makes it harder for the medium to rotate, that is, makes it harder to correct the skew. Since the pushing member is provided, the pushing member fulfills a function of separating the medium from the wall surface thereof. This is another reason why the skew is corrected well.

In the first aspect, the pushing member may be an elastic member whose downstream portion in the medium feeding direction is fixed and whose upstream portion in the medium feeding direction pushes the deformed part of the medium. In this mode, since the pushing member is an elastic member whose downstream portion in the medium feeding direction is fixed and whose upstream portion in the medium feeding direction pushes the deformed part of the medium, it is possible to push the deformed part of the medium upstream in the medium feeding direction properly.

In the first aspect, the pushing member may be a pivot member that has a pivot at a downstream portion in the medium feeding direction, and an upstream portion located upstream of the pivot in the medium feeding direction pushes the deformed part of the medium. In this mode, since the pushing member is a pivot member that has a pivot at a downstream portion in the medium feeding direction, and since an upstream portion located upstream of the pivot in the medium feeding direction pushes the deformed part of the medium, it is possible to push the deformed part of the medium upstream in the medium feeding direction properly.

In the first aspect, the pushing member may be provided at a center area in the medium width direction. In this mode, since the pushing member is provided at a center area in the medium width direction, it is easier for the force of pushing the medium by the pushing member to equally act at one side and the opposite side in the medium width direction, and thus it is possible to correct the skew properly even if it is not predictable which one of the two in the medium width direction will be the side where the degree of deformation is greater.

The medium feeding apparatus according to the first aspect may further include a controller configured to control the first pair of feeding rollers and the second pair of feeding rollers; wherein the controller changes an amount of driving the first pair of feeding rollers depending on feeding conditions when the first pair of feeding rollers is driven, with the second pair of feeding rollers stopped.

In this mode, since the controller configured to control the first pair of feeding rollers and the second pair of feeding rollers changes an amount of driving the first pair of feeding rollers depending on feeding conditions when the first pair of feeding rollers is driven, with the second pair of feeding rollers stopped. Therefore, it is possible to correct the skew suitably in accordance with the feeding conditions.

An image reading apparatus according to a second aspect of the present disclosure includes: a reader configured to read a medium; and the medium feeding apparatus according to the first aspect configured to feed the medium toward a reading position where the medium is read by the reader. With this aspect, the same operational effects as those described above can be obtained in the image reading apparatus.

Embodiments of the present disclosure will now be explained in detail. Described below with reference to the accompanying drawings are a medium feeding apparatus according to an exemplary embodiment of the disclosure and an image reading apparatus equipped therewith. In the description below, a scanner 10 is taken as an example of the image reading apparatus. In the X-Y-Z coordinate system depicted in each drawing, the X direction corresponds to the width direction of a medium transported inside the apparatus. The Z direction corresponds to the height direction of the apparatus and to the vertical direction. The Y direction is orthogonal to the X direction and the Z direction. The −X direction is defined as a direction toward the front of the apparatus. The +X direction is defined as a direction toward the rear of the apparatus.

As illustrated in FIG. 1, the scanner 10 is provided over a recording unit 2 and is configured as a component of a multifunction peripheral 1 that has both a recording function and an image reading function. As illustrated in FIG. 2, the scanner 10 includes a scanning unit 11 and a medium feeding apparatus 12. The scanning unit 11 includes a reading device 16 that reads a document set on a document table 14. The medium feeding apparatus 12 feeds sheets of a document stacked on a feeding tray 20 toward the reading device 16. The document is hereinafter referred to as medium P.

The medium feeding apparatus 12 is switchable between a closed positional state and an open positional state. The document table 14 (FIG. 2) of the scanning unit 11 is covered when the medium feeding apparatus 12 is closed as indicated by solid-line illustration in FIG. 1. The document table 14 of the scanning unit 11 is not covered when the medium feeding apparatus 12 is open as indicated by dotted-line illustration in FIG. 1. More specifically, the medium feeding apparatus 12 is connected to the scanning unit 11 such that it can be opened away from and closed toward the scanning unit 11, wherein the pivot of its opening operation and closing operation exists near the +X directional end of the scanning unit 11.

An operation unit 6 is provided on the front portion of the multifunction peripheral 1. The operation unit 6 includes a display such as a liquid crystal display panel. By operating the operation unit 6, a user is able to input, into the multifunction peripheral 1, instructions for recording operation performed by the recording unit 2 and image reading operation performed by the scanner 10.

In the multifunction peripheral 1, a plurality of sheet cassettes 3 containing sheets of printing paper are provided under the recording unit 2. A printer device 4 that performs recording on the medium P that is transported is provided inside the recording unit 2. Recording is performed on the medium sheet transported from the sheet cassette 3. After recording, the recorded sheet is ejected from an ejection port 7. In the multifunction peripheral 1, the ejection port 7 is provided between the scanner 10 and the sheet cassettes 3 as viewed in the Z direction, that is, the apparatus height direction. An ejection tray 5 receives each sheet ejected from the ejection port 7 after recording.

In FIG. 2, for example, an optical reading device conforming to a CIS imaging format or a CCD imaging format is used as the reading device 16 of the scanning unit 11. The reading device 16 is provided under the document table 14, is capable of moving in the Y direction, and is capable of reading a medium set on the document table 14. The document table 14 is made of, for example, colorless transparent glass.

A holder plate 15 for holding the medium P set on the document table 14 is provided on the bottom of the medium feeding apparatus 12 illustrated in FIG. 2. The document table 14 becomes exposed when the medium feeding apparatus 12 is opened. A user places a sheet of medium P on the document table 14, closes the medium feeding apparatus 12 to hold the medium P with the holder plate 15, and gives a scanning instruction for causing the reading device 16 to move in the Y direction, with the medium P held. It is possible to scan the medium P in this way. The scanner 10 is capable of not only scanning the medium P set manually on the document table 14 but also scanning the medium P fed by the medium feeding apparatus 12.

With reference to FIG. 2, the medium feeding apparatus 12 will now be explained. In FIG. 2, the dashed dotted line denoted as T represents a medium feeding path in the medium feeding apparatus 12. The medium feeding path T is a path leading to an ejection tray 39 from a pickup position where the medium P is grabbed by a pick roller 21 described below.

As illustrated in FIG. 2, sheets of the medium P to be fed by the medium feeding apparatus 12 are stacked on the feeding tray 20. That is, the feeding tray 20 is a medium setting portion on which the medium P before feeding is set. The medium P to be fed is picked up by the pick roller 21 from the feeding tray 20. The pick roller 21 is provided at a region corresponding to the +Y side of sheets of the medium P stacked on the feeding tray 20, that is, at a position facing the leading-edge part of the medium P in a feeding direction. A feeding roller 22 is provided relatively at the +Y side downstream of the pick roller 21 in the feeding direction. In other words, the pick roller 21 is located upstream of the feeding roller 22 in the feeding direction.

The pick roller 21 is able to change its position between a position of being in contact with the medium P and a position of being not in contact with the medium P. The pick roller 21 draws out the medium P toward the feeding roller 22 by rotating in the contact state. The pick roller 21 is attached to a holder 27 that operates coaxially with the feeding roller 22. The pick roller 21 rotates by receiving motive power from a first motor 63 (FIG. 3).

The feeding roller 22 feeds the medium P picked up by the pick roller 21 downstream. The feeding roller 22 rotates by receiving motive power from the first motor 63 (FIG. 3).

A separation roller 23 is provided opposite and beneath the feeding roller 22. A rotational torque of a second motor 64 (FIG. 3) is transmitted to the separation roller 23. In addition, a predetermined rotation resistance is applied to the separation roller 23 by a torque limiter that is not illustrated. Although a rotational torque that acts in a reverse rotation direction of returning the medium P upstream (clockwise direction in FIG. 2) is transmitted to the separation roller 23 from the second motor 64 (FIG. 3), during document feeding operation, the separation roller 23 rotates as a follower roller in a forward rotation direction of feeding the medium P downstream (counterclockwise direction in FIG. 2) against the reverse rotational torque due to the action of the torque limiter when there is no medium P between the separation roller 23 and the feeding roller 22 or when there is one sheet only of the medium P between the separation roller 23 and the feeding roller 22.

If two or more sheets of the medium P enter the nip between the separation roller 23 and the feeding roller 22 together in a multiple-fed one-on-the-other state, the separation roller 23 rotates in the reverse rotation direction of returning the medium P upstream because of the reverse rotational torque described above. This prevents multiple feeding of the medium P from occurring.

Next, an acceleration roller pair 26 provided downstream of the feeding roller 22 and the separation roller 23 in the feeding direction will now be explained. The acceleration roller pair 26 is made up of an acceleration driving roller 24 and an acceleration driven roller 25. The acceleration driving roller 24 rotates by receiving motive power from the second motor 64 (FIG. 3). The acceleration driven roller 25 rotates as a follower roller when the acceleration driving roller 24 rotates. The acceleration roller pair 26 is an example of a first pair of feeding rollers. The acceleration roller pair 26 further feeds the medium P downstream.

The medium feeding path T illustrated in FIG. 2 is curved downward downstream of the acceleration roller pair 26. The medium P is fed by the acceleration roller pair 26 to a resist roller pair 35, which is an example of a second pair of feeding rollers. The resist roller pair 35 is made up of a driving resist roller 35a and a driven resist roller 35b. The driven resist roller 35b rotates as a follower roller when the driving resist roller 35a rotates. The resist roller pair 35, and other feeding rollers provided downstream of the resist roller pair 35, are driven by a third motor 65 (FIG. 3).

The apparatus has a transportation roller pair 36 that is located downstream of the resist roller pair 35. The medium P is turned over while it is transported along the curve of the medium feeding path T by the resist roller pair 35 and the transportation roller pair 36 provided downstream thereof. The medium P that has been turned over is fed to a reading area R1 of the medium feeding path T. The side facing the scanning unit 11 at the reading area R1 of the medium feeding path T is made of a colorless transparent material, for example, a glass plate. When the medium P passes through the reading area R1, the lower surface of the medium P at the reading area R1 is scanned by the reading device 16 of the scanning unit 11. Although the illustrated position of the reading device 16 in FIG. 2 is shifted from the reading area R1 in the Y direction, the reading device 16 is moved to a position corresponding to the reading area R1 when the medium P transported by the medium feeding apparatus 12 is scanned.

An upper reading device 18 is provided downstream of the reading area R1 of the medium feeding path T. The upper reading device 18 is provided over the medium feeding path T. After reading by the reading device 16, the medium P is transported toward the upper reading device 18 by another transportation roller pair 37. The medium P passes through a reading area R2 where scanning is performed by the upper reading device 18. During this process, the upper reading device 18 scans the upper surface of the medium P at the reading area R2. Since the reading device 16 and the upper reading device 18 are provided, it is possible to scan both sides of the medium P.

After reading by the upper reading device 18, the medium P is ejected onto the ejection tray 39 by an ejecting roller pair 38. The ejection tray 39 receives the medium P ejected by the ejecting roller pair 38 in a sloped manner.

Control System in Scanner

Next, with reference to FIG. 3, a control system in the scanner 10 will now be explained. FIG. 3 is a block diagram that illustrates a control system in the scanner 10 according to the present embodiment. In FIG. 3, a control unit 50, which is an example of a controller, performs various kinds of control on the scanner 10, including feeding control and reading control for the document P and other control. The control unit 50 receives signal inputs from the operation unit 6. Signals for display on the operation unit 6, in particular, signals that realize user interface (UI), are sent from the control unit 50 to the operation unit 6. The control unit 50 controls the first motor 63, the second motor 64, and the third motor 65. As described above, the first motor 63 is a driving source for the pick roller 21 and the feeding roller 22, the second motor 64 is a driving source for the separation roller 23 and the acceleration driving roller 24, and the third motor 65 is a driving source for the resist roller pair 35 and feeding rollers provided downstream of the resist roller pair 35. Scan data is inputted from the reading device 16 and the upper reading device 18 to the control unit 50. Signals for controlling the reading device 16 and the upper reading device 18 are sent from the control unit 50 to the reading device 16 and the upper reading device 18 respectively. Detection signals are inputted to the control unit 50 from a size detection unit 57, a first document detection unit 58, a multiple feeding detection unit 59, a second document detection unit 60, and a temperature humidity detection unit 61. The control unit 50 performs necessary control based on these detection signals.

The size detection unit 57 is provided in the feeding tray 20 and detects the size of the medium P set on the feeding tray 20. The size detection unit 57 includes a plurality of sensors that is not illustrated. Specifically, the size detection unit 57 includes a plurality of optical sensors arranged at intervals in the medium feeding direction and a plurality of optical sensors arranged at intervals in the medium width direction. A change in detection signals outputted from the optical sensors, which constitute the size detection unit 57, occurs when covered by the medium P set thereon. Based on a combination of the detection signals of the optical sensors, the control unit 50 detects the size of the medium P set on the feeding tray 20.

An example of the positions of the first document detection unit 58, the multiple feeding detection unit 59, and the second document detection unit 60 is illustrated in FIG. 4. As illustrated in FIG. 4, the first document detection unit 58 is provided near and downstream of the feeding roller 22 and the separation roller 23. The first document detection unit 58 is an optical sensor. Based on a change in a detection signal outputted from the first document detection unit 58, the control unit 50 detects the passing of the leading edge and the trailing edge of the document P therethrough. The multiple feeding detection unit 59 is provided immediately downstream of the first document detection unit 58. The multiple feeding detection unit 59 includes a non-illustrated ultrasonic transmitter and a non-illustrated ultrasonic receiver that are provided in such a way as to face each other, and the document feeding path traverses therebetween. An electric signal that indicates the intensity of an ultrasonic wave received by the ultrasonic receiver is sent to the control unit 50. The level of the electric signal indicating the intensity of the ultrasonic wave changes if multiple feeding of the medium P occurs or if there is a change in the thickness of the medium P. Based on such a change, the control unit 50 is able to detect the occurrence, or non-occurrence, of multiple feeding of the medium P and detect the thickness of the medium P.

The second document detection unit 60 is provided near and upstream of the resist roller pair 35. The second document detection unit 60 is another optical sensor. Based on a change in a detection signal outputted from the second document detection unit 60, the control unit 50 detects the passing of the leading edge and the trailing edge of the document P therethrough. The temperature humidity detection unit 61 is provided in, for example, the feeding tray 20 and detects temperature and humidity.

Referring back to FIG. 3, the control unit 50 includes a CPU 51, a ROM 53, and a memory 54. The CPU 51 performs various kinds of arithmetic processing in accordance with a program 52 stored in the ROM 53 and controls the entire operation of the scanner 10. The memory 54, which is an example of storage, is a readable and writeable nonvolatile memory. A variety of data necessary for various kinds of control are stored in the memory 54. In addition, the control unit 50 writes predetermined data into the memory 54 when necessary.

The scanner 10 is able to get connected to an external computer 70. Information is inputted from the external computer 70 into the control unit 50. Based on the information transmitted from the external computer 70, the control unit 50 performs necessary control.

Next, with reference to FIG. 4 and the subsequent figures, correcting the skew of the medium P will now be explained. First, a basic method for correcting the skew of the medium P will now be explained. In FIG. 4, Ta denotes a part of a curved portion of the medium feeding path T along which the medium P is transported while being curved downward. More specifically, Ta denotes a path section between the acceleration roller pair 26 and the resist roller pair 35. The numerals 40 and 41 denote a pair of medium guide members constituting the curved path Ta. The medium guide member 41 has a recess 41a. The recess 41a is able to accommodate a deformed part when the medium P becomes partially deformed outward. This recessed portion is hereinafter referred to as an accommodating space 42. The deformed part of the medium P may be named as a warped part.

After detection of the leading edge of the medium P by the first document detection unit 58, the control unit 50 causes the acceleration roller pair 26 to rotate by a predetermined amount, with the resist roller pair 35 stopped. As a result of this operation, a deformed part H that enters the accommodating space 42 is produced in the medium P as illustrated in FIG. 5. Because of the action of the deformed part H, the leading edge Pf of the medium P is pushed against the resist roller pair 35. This acts to correct the skew. The deformed part H is a part that is produced locally only when skew correction is performed, aside from a curve that is formed when the medium P makes its way while being curved along the curved path Ta. The foregoing is a basic method for correcting the skew of the medium P.

With reference to FIG. 10, a technical problem that occurs in a structure that does not include a pushing member described later will now be explained in detail. As illustrated in the upper part of FIG. 10, the leading edge of the medium P is directed toward the resist roller pair 35 while being guided along and in contact with the outer guide member 41 because of the curve of the curved path Ta. After the leading edge of the medium P reaches the resist roller pair 35, the acceleration roller pair 26 is rotated by a predetermined amount, with the resist roller pair 35 stopped. As a result of this operation, the medium P clings to the outer guide member 41 of the curved path Ta as illustrated in the lower part of FIG. 10. If the medium P clings to the guide member 41 in this way, it becomes harder to rotate the medium P, which is necessary for skew correction.

To provide a solution to such a problem, in the present embodiment, first, the acceleration roller pair 26 is provided at a center area in the medium width direction, which is orthogonal to the medium feeding direction, as illustrated in FIG. 6. In FIG. 6, the deformed part H is categorized into three areas distinguished from one another as H1, H2, and H3 by their respective positions in the medium width direction. In the present embodiment, the deformed part H3 is an area overlapping with a pushing member 43 described later, the deformed part H1 is an area located to the left of the deformed part H3 in FIG. 6, and the deformed part H2 is an area located to the right of the deformed part H3 in FIG. 6. In the description below, the deformed parts H1, H2, and H3 are collectively referred to as the deformed part H when it is unnecessary to distinguish them from one another.

In FIG. 6, the deformed part that is formed in the medium P during the process of skew correction is distinguished into the deformed part H1 at one side and the deformed part H2 at the opposite side in the medium width direction. The degree of deformation of the deformed part H1 at the side having the leading edge Pf1 of the medium P reaching the resist roller pair 35 earlier is greater than the degree of deformation of the deformed part H2 at the opposite side. Therefore, the tendency of the above-described clinging of the medium P to the guide member 41 at the side where the deformed part H1 is formed is greater than that at the side where the deformed part H2 is formed in the medium width direction. In the present embodiment, in order to overcome such a phenomenon, the acceleration roller pair 26 is provided at a center area in the medium width direction, which is orthogonal to the medium feeding direction, as mentioned above. Therefore, the bulge of, in particular, the deformed part H1, which is more deformed than the deformed part H2, is allowed to escape upstream in the feeding direction as indicated by the arrow Y1 from the lateral side of the acceleration roller pair 26. The escaping of the bulge of the deformed part H1 upstream in the feeding direction from the lateral side of the acceleration roller pair 26 eliminates the clinging of the medium P to the guide member 41 or reduces the degree of such clinging.

It is the pushing member 43 that fulfills a function of allowing the bulge of the deformed part H1 to escape upstream in the feeding direction from the lateral side of the acceleration roller pair 26. Specifically, in the present embodiment, the pushing member 43 is provided in the accommodating space 42. The downstream portion 43a of the pushing member 43 is fixed to the medium guide member 41, which is the upper guide. The portion located upstream of the downstream portion 43a is able to deform into the accommodating space 42 elastically.

The pushing member 43 pushes the deformed part H3, which is the center deformed part of the medium P, upstream in the medium feeding direction. In a cross-sectional view, the pushing member 43 pushes the deformed part H3 of the medium P in the direction indicated by the arrow E in FIG. 5. The pushing force acting in the direction indicated by the arrow E includes a force component of separating the deformed part H3 from the medium guide member 41 and a force component of pushing the deformed part H3 upstream in the feeding direction. Since the pushing member 43 pushes the deformed part H3 in the direction of separation from the medium guide member 41 and upstream in the feeding direction, at the deformed part H1, the bulge is allowed to escape in the direction indicated by the arrow Y1 in FIG. 6. The escaping of the bulge eliminates the clinging of the medium P at its deformed part H1 to the guide member 41 or reduces the degree of such clinging. Therefore, it becomes easier to rotate the medium P, which is necessary for skew correction. That is, in the illustrated example, it becomes easier to rotate the medium P in the direction indicated by the arrow r in FIG. 6. The rotation causes the leading edge Pf2 of the medium P at the side that is behind in transportation to advance properly toward the resist roller pair 35 as indicated by the arrow Y2 in FIG. 6. Therefore, the skew is corrected well.

The directional force of pushing the medium P, which results from pushing the deformed part H3 of the medium P by the pushing member 43, is split into directional components indicated by the arrows E21, E22, and E23 in FIG. 6. The directional component indicated by the arrow E21 acts to allow the bulge of the deformed part H1 to escape upstream as described above. The directions indicated by the arrows E22 and E23 are directions of bringing the leading edge of the medium P into abutment against the resist roller pair 35. Although these directional components therefore act in such a way as to cause the medium P to cling to the guide member 41 otherwise, the above-described layout of the acceleration roller pair 26 and the above-described function of the pushing member 43 prevent the clinging of the medium P to the guide member 41 from occurring or reduce the degree of such clinging.

In the present embodiment, segments of the acceleration roller pair 26 are provided at positions that are symmetric with respect to the center in the medium width direction. The description “the acceleration roller pair 26 is provided at a center area in the medium width direction” is not necessarily limited to a structure in which the acceleration roller pair 26 is located at the center in the medium width direction. Specifically, the description “the acceleration roller pair 26 is provided at a center area in the medium width direction” encompasses not only such a structure but also a structure in which a segment of the acceleration roller pair 26 is provided at one side and a segment of the acceleration roller pair 26 is provided at the opposite side, with the center located between the segment at the one side and the segment at the opposite side in the medium width direction.

In the present embodiment, the pushing member 43 is an elastic member whose downstream portion in the medium feeding direction is fixed and whose upstream portion in the medium feeding direction pushes the deformed part H of the medium P. Although any member that is able to deform due to its elastic property can be used as such an elastic member, a preferred example is a member that is made of a material that has a low coefficient of friction with the medium P and is not obstructive to the rotation of the medium P, such as polyethylene terephthalate (PET). Since the pushing member 43 is made of an elastic material, it is possible to push the deformed part H of the medium P upstream in the medium feeding direction properly.

The pushing member may be a member that has a pivot structure as illustrated in FIG. 7. A pushing member 44 illustrated in FIG. 7 has a pivot 44a near its downstream end in the medium feeding direction. The body located upstream of the pivot 44a in the medium feeding direction serves as a pivot member that pushes the deformed part H of the medium P. The upstream portion of the pushing member 44 is urged by a spring 45. The modified structure described here also makes it possible to push the deformed part H of the medium P upstream in the medium feeding direction properly.

The pushing member may be, for example, a member like a piston that advances toward and retreats from the deformed part H, instead of a member that has a pivot structure. For example, a solenoid that is switchable between a current-applied state and a non-applied state may cause such a piston to advance toward and retreat from the deformed part H under the control of the control unit 50. The piston may be usually in a retreated position away from the curved path Ta and may advance toward the curved path Ta and push the deformed part H under the control at the same time as the producing of the deformed part H or after the producing of the deformed part H.

In the present embodiment, the pushing member 43 is provided at a center area in the medium width direction as illustrated in FIG. 6. This layout makes it easier for the force of pushing the medium P by the pushing member 43 to equally act at one side and the opposite side in the medium width direction and thus makes it possible to correct the skew properly even if it is not predictable which one of the two in the medium width direction will be the side where the degree of deformation is greater. The description “the pushing member 43 is provided at a center area in the medium width direction” is not necessarily limited to a structure in which the pushing member 43 is located at the center in the medium width direction. This description encompasses not only such a structure but also a structure in which a segment of the pushing member is provided at one side and a segment of the pushing member is provided at the opposite side, with the center located between the segment at the one side and the segment at the opposite side in the medium width direction.

Although the pushing member is provided at a center area in the medium width direction in the present embodiment, the pushing member may have a size that is large enough for the entire area in the medium width direction.

The control unit 50 configured to control the acceleration roller pair 26 and the resist roller pair 35 may change an amount of driving the acceleration roller pair 26 depending on feeding conditions when the acceleration roller pair 26 is driven, with the resist roller pair 35 stopped. The drive amount corresponds to an amount of bringing the leading edge of the medium P into abutment against the resist roller pair 35. Therefore, the drive amount is hereinafter referred to as “abutment amount”.

The feeding conditions may include, for example, the speed of feeding the medium P by the acceleration roller pair 26, the size of the medium P, the thickness of the medium P, and temperature and humidity. It is possible to set the abutment amount depending on these feeding conditions. Table 1 shows an example of abutment amount addition values that depend on the feeding speed. Table 2 shows an example of abutment amount addition values that depend on the size of the medium P. Table 3 shows an example of abutment amount addition values that depend on temperature and humidity and the thickness of the medium P.

For example, an addition value “6” is obtained from Table 1 when the feeding speed is “high”. An addition value “−2” is obtained from Table 2 when the size of the medium P is “A5 landscape”. An addition value “1” is obtained from Table 3 when the temperature/humidity condition is that “temperature T: 1° C. or lower, and humidity S: higher than 1%” and when the thickness of the medium P is “thick”. In this example, it is possible to calculate the abutment amount (mm) as follows: abutment amount (mm)=“6”+“−2”+“1”=5 (mm). The size of the medium P shown in Table 2 is A-series paper size and B-series paper size set forth in ISO 216, which is an international standard.

As explained above, the control unit 50 configured to control the acceleration roller pair 26 and the resist roller pair 35 changes the amount of driving the acceleration roller pair 26 depending on the feeding conditions when the acceleration roller pair 26 is driven, with the resist roller pair 35 stopped, that is, switches the abutment amount. Therefore, it is possible to correct the skew suitably in accordance with the feeding conditions.

TABLE 1
Feeding speed
High Low
6    4

TABLE 2
A5 Landscape
B5 Landscape	B5 Portrait	B4 Portrait
A4 Landscape	A4 Portrait	A3 Portrait
−2	0	−1

	TABLE 3
	Temperature
Humidity/Sheet thickness	T: 1° C. or lower	T: Higher than 1° C.
S: 1% or lower	Thin	0	0
	Thick	1	1
S: Higher than	Thin	0	−2
1%	Thick	1	0

With reference to FIG. 8, the flow of feeding control performed by the control unit 50 will now be explained. Upon receiving a medium feeding instruction (step S11), the control unit 50 acquires information on the size of the medium P (step S12) and information on temperature and humidity (step S13) and then starts feeding the medium P (step S14). When the leading edge of the medium P reaches the multiple feeding detection unit 59 after starting the feeding of the medium P, the control unit 50 acquires information on the thickness of the medium P (step S15) and calculates an abutment amount depending on the feeding conditions (step S16). Based on the calculated abutment amount, the leading edge of the medium P is brought into abutment against the resist roller pair 35 for skew correction (step S17). The feeding operation further continues, and the medium P is fed to the reading position and is read thereat (step S18) In the above feeding control, the skew of the medium P is properly corrected because of the action of the pushing member 43 described above.

Claims

1. A medium feeding apparatus, comprising:

a first pair of feeding rollers configured to feed a medium downstream;

a second pair of feeding rollers provided downstream of the first pair of feeding rollers;

a curved path that is a medium feeding path formed between the first pair of feeding rollers and the second pair of feeding rollers, the medium being transported along the curved path while being curved downward; and

an accommodating portion formed outside a curve of the curved path and configured to accommodate a deformed part of the medium at the curved path; wherein

the first pair of feeding rollers is provided at a center area in a medium width direction intersecting with a medium feeding direction, and wherein

the accommodating portion has a pushing member configured to push the deformed part of the medium upstream in the medium feeding direction.

2. The medium feeding apparatus according to claim 1, wherein

the pushing member is an elastic member whose downstream portion in the medium feeding direction is fixed and whose upstream portion in the medium feeding direction pushes the deformed part of the medium.

3. The medium feeding apparatus according to claim 1, wherein

the pushing member is a pivot member that has a pivot at a downstream portion in the medium feeding direction, and an upstream portion located upstream of the pivot in the medium feeding direction pushes the deformed part of the medium.

4. The medium feeding apparatus according to claim 1, wherein

the pushing member is provided at a center area in the medium width direction.

5. The medium feeding apparatus according to claim 1, further comprising:

a controller configured to control the first pair of feeding rollers and the second pair of feeding rollers; wherein

the controller changes an amount of driving the first pair of feeding rollers depending on feeding conditions when the first pair of feeding rollers is driven, with the second pair of feeding rollers stopped.

6. An image reading apparatus, comprising:

a reader configured to read a medium; and

the medium feeding apparatus according to claim 1 configured to feed the medium toward a reading position where the medium is read by the reader.