JP3487196B2 - Automatic document feeder - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic document feeder (hereinafter referred to as ADF) having means for removing an inclination (hereinafter referred to as skew) when a document is conveyed.

[0002]

2. Description of the Related Art Conventionally, as an image reading device for reading a document such as paper or film, a flat bed type or sheet feed type image reading device has been known. When reading a large number of originals at one time with these image reading devices, a flatbed image reading device equipped with an ADF is used, or a large number of originals are set in the sheet feeding unit of a sheet feed type image reading device and read. I was working. As a method of separating the document at the time of feeding, a nail separation method or a pad separation method has been used.

In the claw separation system, the tip corners of the stacked sheets are locked to the claws of the stacking container, and the feeding roller arranged behind the claws is rotated to cause the claws to rotate. This is a method in which a sheet is sandwiched between a feeding roller and a feeding roller to be bent, and by utilizing the fact that the sheet has a resilience, the uppermost sheet and the lower sheet are separated and fed.

Further, the pad separation method is such that the friction μ1 between the feeding roller and the paper and the friction μ between the paper and the separation pad μ
2 and friction between sheets μ3 μ1>μ2> μ
In this method, the uppermost paper is separated from the lower paper by configuring the feeding roller and the separation pad so as to have the relationship of 3.

[0005]

However, in the image reading apparatus for continuously reading a plurality of originals using the conventional ADF as described above, the originals separated and fed by the original feeding mechanism of the ADF are The irregularities on the guide surface that guide the movement of the original in the conveyance path, and the movement of the original while being regulated by the rollers that perform the conveyance may cause the original to be inclined with respect to the original conveyance direction. . Therefore, there is a problem in that the reading position is likely to shift for each document and the reading operation needs to be redone.

It is an object of the present invention to provide an ADF which removes a skew generated when a document is conveyed before reading the document.

[0007]

According to the ADF described in claim 1 of the present invention, a feeding roller that comes into contact with the surface of a document to be fed and rotates normally at the time of feeding, and the fed document is imaged. A conveyance path that guides to the reading position, a conveyance roller that normally rotates when the document is conveyed to the image reading position in the conveyance path, and a contact roller that is provided to face the conveyance roller and contact the conveyance roller are provided. ing.

In the above ADF, when the front edge of the conveyed document passes through the abutting portion between the conveying roller and the abutting roller, the feeding roller for feeding the original stops and the conveying roller reverses. A means for rotating the feeding roller and the feeding roller in the forward direction again after the leading edge of the document is fed in the opposite direction by the feeding roller which is rotated in the reverse direction to pass through the contact portion between the feeding roller and the contact roller. Therefore, the rear portion of the conveyed document abuts against the stopped feeding roller and is conveyed in the immovable state in the reverse direction, and the document is bent in the conveying path. The leading edge of the original that is bent in the transport path is
By aligning the contact part of the transport roller and the contact roller perpendicularly to the transport direction by the stiffness of the document, it is possible to transport the document without skewing the document during transport. Can be done easily.

According to the ADF of the second aspect of the present invention, the feeding roller has a side view substantially D having an arc portion and a straight portion.
It is a letter shape. The length of the arc portion of the feeding roller is longer than the distance of the conveyance path from the point where the contact between the arc portion and the document is released to the point where the conveyance roller and the document contact.
Since the distance is set to be shorter than the distance of the conveyance path from the point where the contact between the arc portion and the document is released to the image reading position, the document is reliably conveyed to the conveyance roller by the feeding roller. However, since the contact between the arc portion of the feeding roller and the original is released at the image reading position, it is possible to prevent the feeding roller from changing the conveyance speed at the image reading position.

According to the ADF of the third aspect of the present invention, the feeding roller and the conveying roller operate asynchronously. As a result, the feed roller and the transport roller can be independently rotated in the forward and reverse directions, so that the document is transported in the reverse direction with the rear portion stopped, and the skew can be removed.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments showing an embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, an ADF 2 is mounted on a housing 10 of a flatbed type image reading apparatus main body 1.

A document table 3 made of a material such as transparent glass is provided on the upper surface of the housing 10 of the image reading apparatus main body 1. A carriage 4 is provided inside the housing 10, and a light source 41 and a line sensor 42 are mounted on the carriage 4.
And are installed. Light emitted from the light source 41 is reflected on the surface of the original 5 on the original table 3 and is condensed by the condenser lens 43 on the line sensor 42. As the line sensor 42, a charge storage type photosensor such as a CCD is used.

An ADF 2 is mounted on the original table 3. As shown in FIG. 1, the conveyance path 6 for the original 5 is substantially U-shaped, and a plurality of read originals stacked on the hopper 210 are separated from each other by a separation pad 23 provided on a separation pad holder 230.
1. By the feeding roller 220 and the like, the feeding can be performed by the method described later while preventing the double feeding.

The fed original 5 is folded back into a U-shape while being guided by the conveying path 6 formed by the first guide 31, the second guide 32 and the frame 11 of the ADF 2, and is conveyed by the conveying rollers 12, The sheet is conveyed by the discharge roller 13 and discharged onto the discharge tray 14 while being guided by the transparent guide 34 and the third guide 33. At this time, the auxiliary roller 15 provided on the frame 11 of the ADF 2 facing the first guide 31 and the contact roller 16 provided in contact with the transport roller 12 move the document 5 on the transport path 6. It has the function of reducing transport resistance due to regulations. Further, a high friction material such as urethane is wound on the surface of the pressing roller 17 provided in contact with the discharge roller 13 so that the rear end of the conveyed document 5 can be reliably discharged. Has become.

As shown in FIG. 2, the transparent guide 34 has an AD
A plastic engaging portion 342 in which a locking hole 343 for locking and fixing to the protruding portion 71 of the cover portion 7 of F2 is formed.
And a sheet-shaped transparent portion 341, and the transparent guide 34 is provided with a locking hole 343 provided in the engaging portion 342.
Of the transparent sheet 341 to the frame 11 of the ADF 2 and the third portion.
By being inserted into the gap between the guide 33 and the guide 33, it is fixed to the document table 3 side of the bottom of the ADF 2 along the transport path 6. The transparent guide 34 not only guides the movement of the document 5, but also allows the line sensor 42 inside the housing 2 to read an image through the transparent sheet 341.

Next, the document separating mechanism of the ADF 2 will be described.

As shown in FIG. 3, the ADF 2 includes a frame 200, a feeding roller shaft 221 rotatably supported by the frame 200, and a pair of feeding rollers attached to the feeding roller shaft 221. Roller units 201, 20
2 and a hopper 210 rotatably attached to the frame 200.

An edge guide 203 slidable in the document width direction is attached to the hopper 210, and the feed roller unit 20 of the pair of feed roller units is attached.
Reference numeral 2 is connected to the edge guide 203, and is slidable along the feeding roller shaft 211 together with the edge guide 203. The hopper 210 is inclined as shown in FIG. 4, and it is possible to set a plurality of originals in a stacked state.

The edge guide 203 shown in FIG. 3 can be slid according to the width of the document, and guides one side edge of the document 5 to be fed. Since the other side edge is guided by the side wall 204 of the frame, the feeding roller unit 201 does not slide on the feeding roller shaft 211.

As shown in FIGS. 4 and 5, the feeding roller 220 has a substantially D-shaped side surface having an arc portion 222 and a straight portion 223, and the surface thereof has a high friction such as rubber. Made of material. Since the feeding roller 220 is fixed to the feeding roller shaft 221, the feeding roller 22 is fixed.
0 cannot rotate with respect to the feeding roller shaft 221. The feeding roller shaft 221 is adapted to rotate exactly once during the feeding operation by a driving means (not shown).

The hopper 210 is rotatably attached to the sub-frame 240 by a shaft 211 as shown in FIG. A plurality of originals can be set on the hopper 210 in a stacked state. Set original 5
The tips of the are supported and aligned by contacting the back surface 232 of the separation pad holder 230.

The sub-frame 240 includes the feeding roller 220.
This sub-frame 240 and hopper 2
A hopper spring (compression spring) 212 is provided between the tip end of 10 and
Is provided. As a result, the hopper 210 causes the hopper spring 212 to feed the document 5 in FIG.
It is always urged in the upper left direction in the figure so as to be brought into contact with 0.

The separation pad 231 is the separation pad holder 2
It is fixed at 30. The separation pad 231 has a friction coefficient with the original 5 smaller than that between the feeding roller 220 and the original 5 and larger than the mutual friction between the originals 5, such as cork material. To use.
At this time, the friction coefficient between the feeding roller 220 and the document 5 is
1, the friction coefficient between the separation pad 231 and the original 5 is μ2, and the friction coefficient between the originals 5 is μ3, the relationship between these friction coefficients is μ1>μ2> μ3. A pad spring 235 is provided between the lower surface of the pad support portion 233 of the separation pad holder 230 and the sub-frame 240 as a pad urging means, and the separation pad 231 is connected to the feed roller 2.
Energized towards 20.

The idle roller 250 is rotatably supported by the shaft 251 and can slide in the directions of arrows A and B in FIG. 4, and the original of the arc portion 222 of the feeding roller 220 and the separation pad 231. 5, the idle roller 250 is actuated so as to contact the separation pad 231 before the contact via the 5 is released, and the linear portion 223 of the feeding roller 220 is operated.
However, when the document 5 faces the separation pad 231 and is not in contact with the document 5, the document is prevented from moving in a direction other than the transport direction.

Next, a method of feeding the ADF will be described.

The feeding roller shaft 221 starts to rotate clockwise (forward rotation), and the feeding roller 220 and the bush 22.
4. The hopper cam 214 also rotates clockwise.

As shown in FIG. 6, when the hopper cam 214 rotating together with the feeding roller shaft 221 rotates forward by a predetermined angle and the contact between the hopper cam 214 and the hopper 210 is released,
The hopper 210 is momentarily pushed up together with the original 5 by the hopper spring 212, and the uppermost original 51 is pressed against the circular arc portion 222 of the feeding roller 220 and the hopper 210.
It is sandwiched between the feeding roller 220 and the feeding roller 220.

When the feeding roller 220 continues to rotate, the arc portion 222 of the feeding roller 220 causes the uppermost document 5 to move.
Although the first original 51 and the second original 52 are brought into contact with the sheet 1 toward the separation pad 231, the top original 51 and the next original 52 may be simultaneously sent to the separation pad 231 due to static electricity or frictional force.
However, the movement of the next-order document 52 is restricted by contacting the separation pad 231, and the movement is restricted, so that the next-order document 52 is primarily separated from the highest-order document 52.

When the feeding roller shaft 221 continues to rotate, the arc portion 222 of the feeding roller 220 causes the uppermost original 5 to move.
The separation pad 231 is pressed via 1. The separation pad 231 is pushed down, but at the same time, the uppermost original 51 between the circular arc portion 222 of the feeding roller 220 and the separation pad 231 is pressed by the biasing force of the pad spring 235. At this time, as described above, the second-order document 52 is also the highest-order document 51.
It may be sent with. However, as described above, the friction coefficient between the feeding roller 220 and the uppermost document 51 is set to μ
1. If the friction coefficient between the separation pad 231 and the next original 52 is μ2, and the friction coefficient between the originals 51 and 52 is μ3, the relationship between these friction coefficients is μ1>μ2>
Since it is μ3, the arc portion 22 of the feeding roller 220 is
Even if the original document is fed between the second and the separation pad 231, the movement of the next original document 52 is restricted by the frictional force between the second original document 52 and the separation pad 231, so that it is secondarily separated from the uppermost original document 51.
Only the highest document 51 will be fed.

When the feeding roller shaft 221 continues to rotate, the uppermost document 51 is moved to the arc portion 22 of the feeding roller 220.
2 and the separation pad 231 are sandwiched and sent.
The feed roller 220 continues to rotate together with the feed roller shaft 221, and the idle roller 250 moves before the contact between the arcuate portion 222 of the feed roller 220 and the separation pad 231 via the uppermost document 51 is released. Contact with the separation pad 231 is started.

Further, when the feeding roller shaft 221 continues to rotate and makes one full rotation from the reference state, the hopper 210 returns to the state of being pushed down by the hopper cam 214, as shown in FIG. The uppermost document 51 to be fed is released from being conveyed by the arc portion 222 of the feeding roller 220.
At this time, the leading edge of the uppermost original 51 reaches the position where the transport roller 12 and the contact roller 16 shown in FIG.
Until it passes through the abutting part of, the separation roller 231 and the idle roller 250 are in contact with each other and are conveyed by the conveyance roller 12. Further, since the idle roller 250 sandwiches the uppermost original 51 toward the separation pad 231, the next original is prevented from being fed together with the uppermost original 51.

Next, the document feeding path and the document reading method will be described.

As shown in FIG. 7, the original 5 output from the ADF 2
Contacts the first guide 31. The first guide 31 restricts the document 5 from rolling up. First
After coming into contact with the guide 31, the document 5 is placed on the first guide 31 and A
The transport path 6 formed by the frame 11 of the DF 2 is transported in an arc shape. Further, since the first guide 31 is rotatably fixed to the cover portion 7 by the guide fixing portion 35, even if the document 5 is jammed in the conveyance path 6, it can be easily removed. The original 5 is the first guide 31 and the ADF 2.
When it is guided to and passes through the transport path 6 formed by the frame 11 of, the transport path 6 formed by the second guide and the frame 11 of the ADF 2 transports it in an arc shape and reaches the transport roller 12. Contact roller 16 provided in contact with auxiliary roller 15 provided on frame 11 of ADF 2 and conveyance roller 12 so as to face first guide 31.
Rotate together with the movement of the document 5 and the guide 3
It has a function of reducing the conveyance resistance of the document 5 whose movement is restricted by 1, 32 and smoothly conveying the document 5.

The original 5 that has reached the conveying roller 12 is subjected to skew removal for correcting the inclination caused by the original feeding using the rigidity of the original 5. The procedure for removing this skew is shown below.

The leading edge 53 of the original 5 which reaches the conveying roller 12 in a tilted state by the original feeding, has the forwardly rotating conveying roller 12 and the contact roller 1 as shown in FIGS. 8 and 11.
It passes through the contact portion 62 with 6. At this time, the conveying roller 12 and the feeding roller 220 are temporarily stopped as shown in A of FIG. 14, but since the arc portion 222 of the feeding roller 220 is still in contact with the document 5, the movement of the rear portion of the document 5 is fixed. Has been done.

Here, as shown in FIG. 14B, the feeding roller 22
0 is stopped and the rear part of the document 5 is fixed, and the transport roller 1
When only 2 is reversed in the direction of the arrow in FIG. 9, the contact between the front edge 53 of the original 5 and the contact roller 16 is released and the movement of the original 5 is stopped, as shown in FIG. The document 5 is bent in the conveyance path, and the reverse rotation of the conveyance roller 12 is stopped as shown in FIG. 14C. Here, due to the elasticity of the original 5, the original 5
The leading end of the contact portion 6 between the transport roller 12 and the contact roller 16
2 can be aligned perpendicular to the transport direction to remove skew.

As shown in FIG. 14D, the transport roller 12 is again used.
And the feeding roller 220 starts forward rotation. Feeding roller 22
The forward rotation of 0 is stopped as shown in E of FIG. 14 when the straight line portion 223 of the document 5 feeding roller 220 faces each other.
0 and as shown in FIG. 13, the document 5 is transported by the transport roller 12. The document 5 is conveyed on the conveyance path formed by the transparent guide 34 and the conveyance roller 12 and reaches the image reading position 9, but the feeding roller 220 is stopped at the image reading position 9 as shown by F in FIG. This is before the start of image reading, and is not affected by the feeding roller during image reading.

The original is read line by line at the image reading position 9 by the line sensor 42 provided in the carriage 4 inside the housing 10. The carriage 4 in the housing 10 stops at a predetermined position and does not move in the housing 10 when reading a document.

At the time of reading the original, the original conveying speed is set such that the conveying roller 12 rotates so that the original 5 is conveyed so that the original conveying speed becomes a speed corresponding to the reading speed of one line of the line sensor 42. Further, at the time of reading, as shown in FIG.
Although the circular arc portion 222 is stopped at a position where it does not contact the original document 5, the idle roller 250 contacts the original document 5 as shown in FIG. 10 to prevent the original document 5 from moving. Manuscript 5
Is carried by the carrying roller 12 and the discharge roller 13 synchronized with the carrying roller 12, the feeding roller 22
The original 5 can be conveyed in a stable state without being affected by 0.

The above-mentioned feeding roller 220 and conveying roller 12
Although the discharge roller 13 and the discharge roller 13 are driven by the same drive device (not shown), the forward rotation and the stop of the feeding roller 220 are controlled by a solenoid 243 provided at one end of the sub-frame 240 as shown in FIG. The energization is performed by the contact and separation of the clutch 228 provided on the feeding roller drive shaft 221. When the solenoid 243 is energized, the driving force is transmitted to the feeding roller shaft 221 by the clutch 228 and the feeding roller 220 rotates. However, when the solenoid 243 is not energized, the feeding roller shaft 221 is driven. The transmission of the force is released and the feeding roller 220 stops.

In the above case, the original 5 needs to be conveyed from the feeding roller 220 until it reaches the conveying roller 12, but when the leading edge of the original 5 reaches the image reading position 9, the original 5 is fed. The contact between the arc portion 222 and the document 5 needs to be released. Therefore, as shown in FIG. 15, the arc portion 222 of the feeding roller 220 is provided in the conveying path 6.
The distance from the point where the separation pad 231 is released from the contact point to the point where the transport roller 12 and the contact roller 16 contact each other is D1, and the length of the arc portion 222 of the feeding roller 220 is D2.
D3>D2> D, where D3 is the distance from the point where the contact between the arc portion 222 of the feeding roller 220 and the separation pad 231 in the transport path 6 is released to the image reading position 9.
D1, D2, and D3 must be set so that they have a relationship of 1.

After passing the image reading position 9, the document 5
Moves to the discharge roller 13 along the transport path 6 formed by the third guide 33 and the frame 11 of the ADF 2. The document 5 reaching the discharge roller 13 is transferred to the transport roller 1
The discharge roller 13 synchronized with the rotation of 2 and the pressing roller 17 which rotates in association with the movement of the document 5 are discharged to the discharge tray 14. Since the rotation of the discharge roller 13 is synchronized with the conveyance roller 12, it does not affect the document conveyance speed at the image reading position 9. Further, a high friction material such as urethane is wound on the surface of the pressing roller 17, so that the original 5 does not remain even after the original 5 has passed through the contact portion between the discharge roller 13 and the pressing roller 17, and is surely kept until the end. It can be discharged to the discharge tray 14.

In this embodiment, the means for removing the skew by separating only the uppermost original from a plurality of originals and removing the skew has been described. However, even if there is only one original, the same effect can be obtained for the skew removal. be able to.

According to the embodiment of the present invention, the uppermost original separated from the next original by the feeding roller temporarily reverses the inclination of the original caused by the contact with the roller or the guide and the restriction during the conveyance. By doing so, it is possible to remove by utilizing the elasticity of the original, and it becomes easy to perform the continuous alignment operation of the original.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a schematic structure of an image reading apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic plan view of a transparent guide according to an embodiment of the present invention.

FIG. 3 is a schematic perspective view of a feeding unit of an ADF according to an exemplary embodiment of the present invention.

FIG. 4 is a partially cut side view of a feeding unit of an ADF according to an embodiment of the present invention, showing a positional relationship between a feeding roller, a separation pad, and a hopper.

FIG. 5 is a partially cut side view of an ADF according to an embodiment of the present invention, showing a state in which a hopper on which originals are stacked is pushed down by a hopper cam.

FIG. 6 is a partially cut side view of an ADF according to an embodiment of the present invention, showing a positional relationship between a document to be fed and a feeding roller.

FIG. 7 is a schematic diagram showing a schematic structure of an ADF according to an embodiment of the present invention.

FIG. 8 is an explanatory diagram of the operation of skew removal according to the embodiment of the present invention.

FIG. 9 is an operation explanatory diagram of skew removal according to the embodiment of the present invention.

FIG. 10 is an operation explanatory diagram of skew removal according to the embodiment of the present invention.

FIG. 11 is an operation explanatory diagram of skew removal according to the embodiment of the present invention.

FIG. 12 is a diagram illustrating an operation of skew removal according to the embodiment of the present invention.

FIG. 13 is an operation explanatory diagram of skew removal according to the embodiment of the present invention.

FIG. 14 is an operation sequence for deskewing according to an embodiment of the present invention.

FIG. 15 is an explanatory diagram showing the relationship between the length of the arc portion of the feeding roller and the length of the conveyance path according to the embodiment of the present invention.

FIG. 16 is a schematic diagram showing a schematic structure of a feed roller unit of an ADF according to an embodiment of the present invention.

[Explanation of symbols]

1 Reading device body 2 Automatic document feeder (ADF) 3 Platen 4 carriage 5 manuscripts 6 transport paths 9 Image reading position 10 housing 11 Transport frame 12 Conveyor rollers 13 Discharge roller 15 Auxiliary roller 16 Contact roller 17 Presser roller 31 First Guide 32 Second Guide 33 Third Guide 34 Transparent guide 41 light source 42 line sensor 51 Top manuscript 52 Second manuscript 53 Leading edge 61, 62 abutting part 210 hopper 220 feeding roller 222 Arc part 223 Straight part

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Claims (3)

(57) [Claims] 1. A feeding roller that comes into contact with the surface of a document and rotates in the forward direction to feed the document; a feeding path that guides the document fed by the feeding roller to an image reading position; A transport roller that rotates in the normal direction to transport the document, a contact roller that faces the transport roller and contacts the transport roller, and a contact portion between the transport roller and the contact roller that defines the document. Means for stopping the feeding roller and reversing the conveying roller after the leading edge of the front edge has passed, and after the leading edge has been conveyed in the opposite direction through the contact portion,
Again, the conveying roller and the feeding roller have means for rotating in the forward direction, and the automatic document feeder. 2. The feeding roller is a D-shaped feeding roller having a circular arc portion and a linear portion in a side view, and the length of the circular arc portion is such that the contact between the circular arc portion and the document is released. Longer than the distance of the conveyance path from the point where the contact between the conveyance roller and the document is made, and is longer than the distance of the conveyance path from the point where the contact between the arc portion and the document is released to the image reading position. The automatic document feeder according to claim 1, wherein the automatic document feeder is short. 3. The automatic document feeder according to claim 1, wherein the feeding roller and the conveying roller operate asynchronously.