JP2000128378A - Automatic document feeder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic document feeder for a image reading device constituting a document separation mechanism to prevent double feeding and a U shaped document carrying route. SOLUTION: This automatic document feeder(ADF) 2 is furnished with a separation roller 220 to separate a document on the top level out of a plurality of documents 5 and a separation pad 231, and it is possible to prevent double feeding of the documents 5 by revolving a document returning lever after the separated copy on the top level is supplied and pushing back the document on the following position. Additionally, as a carrying passage 6 of the separated document 5 is made in a U shape, the documents are carried from the document on the top position in loading sequence, and as the document are discharged from the document on the top level in the same loading sequence as before carriage in order after carriage, it is needless to rearrange the document after working.

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 (AutoDocument) which is used in an image reading apparatus and which has means for preventing double feeding of originals and in which the order of stacking of originals does not change before and after image reading. Feeder: ADF).

[0002]

2. Description of the Related Art Conventionally, as an image reading apparatus for reading an original such as paper or film, a flatbed type or sheet feed type image reading apparatus is known. When reading a large number of documents at once with these image reading devices, use a flatbed image reading device equipped with an ADF, or set multiple documents in the feeding section of a sheet feed type image reading device and read them. As a method of separating a document at the time of feeding, a nail separation method, a pad separation method, and the like have been used.

[0003] In the claw separation method, a corner of the leading end of the stacked paper is engaged with a claw portion of a loading container, and a separation roller disposed behind the claw portion is rotated so that the claw portion is separated from the claw portion. In this method, the uppermost sheet and the lower sheet are separated and fed by utilizing the fact that the sheet is bent between the separation rollers and is repelled by the stiffness of the sheet.

In the pad separation method, the friction μ1 between the separation roller and the paper and the friction μ1 between the paper and the separation pad are used.
2, and friction between papers μ3, μ1>μ2> μ
In this method, the uppermost sheet is separated from the lower sheet by forming the separation roller and the separation pad so as to satisfy the relation of No. 3.

[0005]

However, the conventional ADF
In the image reading apparatus using the above, even if the separation method as described above is used, when a large number of documents are set, friction between the documents increases, and there is a problem that a plurality of documents are multi-fed,
When reading a large number of documents, it is necessary to perform the operation several times, and the operation is very complicated.

Further, a cylindrical roller is used as a separation roller for separating the original to be fed from the next original, and the feeding roller is always directly connected to the separation pad or the paper via the paper during the feeding operation. As a result, the material is in pressure contact, and as described above, it is necessary to use a soft material because of the need to increase the coefficient of friction with the paper, and there is a problem that the material is easily worn.

In the case of reading a loaded document, in the case of a conventional sheet feed type image reading apparatus using an ADF as shown in FIG. 17, the loaded document is read in the order of A, B, and C in the highest order. When the originals are discharged, the order of loading is reversed, C, B, and A. When using the originals for other purposes, it is necessary to rearrange all the originals. It was bothersome and time-consuming.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an ADF for an image reading apparatus which prevents double feeding and discharges originals in the same order of stacking as before reading originals after reading originals.

Another object of the present invention is to provide an ADF for an image reading apparatus which prevents wear of a separation roller and does not change the conveyance speed of a document during reading.

[0010]

According to the ADF of the present invention, there is provided a separation roller which comes into contact with the surface of the uppermost document among a plurality of stacked documents and separates from the next document. A separation pad provided at a position facing the separation roller to press the separation roller to prevent the next document from being fed, and a plurality of documents to be stacked and pressed against the separation roller via the document when the document is fed. Hopper, a document return lever that rotates after the document is fed and passed by the separation roller and pushes the leading edge of the next document into the hopper, and guides the document fed by the separation roller to the image reading position. A U-shaped transport path, a transport roller that transports the original in the transport path,
Since the document has a discharge roller for discharging the document, the separation roller and the separation pad ensure that the top document and the next document can be separated, and the document return lever moves to the next position each time a document is fed. By pushing back the original to the inside of the hopper, feeding of the next original is prevented, and double feeding of originals can be reliably prevented.

Further, since the original transport path is U-shaped, the originals are transported in the stacking order from the uppermost original, and after reading, the originals are discharged in order from the uppermost original in the same loading order as before the reading. There is no need to rearrange manuscripts.

According to the ADF of the present invention, the transport path includes a frame of the ADF, a plurality of guides provided to face the frame, and an auxiliary roller for reducing the transport resistance of the document caused by the guides. Therefore, the document is always conveyed in the conveyance path, and can be smoothly moved to the reading position.

According to the ADF according to the third aspect of the present invention, at least one of the guides constituting the transport path is located at an image reading position, has a transparent portion capable of reading an image, and has a transparent portion. The reading by the image reading device can be performed at the same time as guiding the conveyance.

According to the ADF of the fourth aspect of the present invention, the separation roller has a substantially D-shaped arc portion and a straight portion when viewed from the side, and the separation pad has a straight portion of the separation roller during non-separation operation. , A gap can be maintained between the sheet and the separation roller. In addition, since the separation roller is provided with an idle roller outside of the separation roller when the separation roller is not in contact with the separation pad, even when the separation roller is not in contact with the document, the separation roller may move in a direction other than the conveyance direction. Can be prevented. Further, at the time of non-separation operation, since the separation roller does not contact the original, the separation roller can be prevented from being worn.

According to the ADF according to the fifth aspect of the present invention, the length of the arc portion of the separation roller is from the point where the contact between the arc portion and the document is released to the point where the conveyance roller contacts the document. The fed document is transported by the separation roller because it is longer than the distance of the transport path and shorter than the distance of the transport path from the point where the contact between the arc and the document is released to the image reading position. Although the sheet is conveyed to the roller, the contact between the separation roller and the document is released at the time of image reading, so that a change in the conveyance speed at the image reading position by the separation roller can be prevented.

According to the ADF according to the sixth aspect of the present invention, the end of the shaft to which the separation roller is attached has means for interrupting the driving force of the driving device. The separation roller can be driven asynchronously with the conveyance roller and the discharge roller.

According to the ADF of the present invention, a pressing roller for discharging the rear end of the document after the contact between the discharge roller and the document is released is provided at the facing portion of the discharge roller. Thus, the trailing end of the document can be reliably discharged at the document discharge portion at the end of the transport path, and jamming can be prevented.

[0018]

Embodiments 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 main body 1 of a flat bed type image reading apparatus.

A document table 3 made of a material such as transparent glass is provided on an upper surface of a housing 10 of the image reading apparatus main body 1. A carriage 4 is provided inside the casing 10, and the light source 41 and the line sensor 4
2 is mounted. The irradiation light of the light source 41 is reflected on the surface of the original 5 on the original table 3 and is condensed on a line sensor 42 by a condenser lens 43. As the line sensor 42, for example, a charge accumulation type optical sensor such as a CCD is used.

An ADF 2 is mounted on the document table 3. As shown in FIG. 1, the transport path 6 of the original 5 is U-shaped, and a plurality of read originals stacked on the hopper 210 are separated by a separation pad 2 provided on a separation pad holder 230.
The feeding can be performed while preventing double feeding by a method described later by the separation roller 220 and the separation roller 220. Document 5 fed
While being guided by the transport path 6 formed by the first guide 31, the second guide 32 and the frame 11 of the ADF 2, is folded back into a U-shape, transported by the transport roller 12 and the discharge roller 13, and 34, the discharge tray 14 while being guided by the third guide 33 for movement.
Is discharged on top. At this time, A
A first auxiliary roller 15 provided on the frame 11 of the DF 2 and a second auxiliary roller 15 provided in contact with the transport roller 12.
The auxiliary roller 16 rotates in association with the movement of the document 5, and has a function of reducing the conveyance resistance in the conveyance path 6 due to the movement restriction of the document 5.

A material having a higher friction than the surface of the discharge roller 13 such as urethane is wound around the surface of the press roller 17 which is provided in contact with the discharge roller 13 and rotates with the movement of the document 5. Even after the contact between the rear end of the conveyed document 5 and the discharge roller 13 is released, the document can be reliably discharged.

As shown in FIG. 2, the transparent guide 34
A locking portion 342 made of plastic having a locking hole 343 formed to lock and fix to the projecting portion 71 of the cover 7 of F2.
And a sheet-shaped transparent portion 341. The transparent guide 34 is provided with a locking hole 343 provided in the locking portion 342.
Of the transparent sheet 341 with the frame 11 of the ADF 2 and the third
By being inserted into the gap between the guide 33 and the document table 3, the document is fixed to the bottom of the ADF 2 along the conveyance path 6. The transparent guide 34 not only guides the movement of the document 5, but also enables reading of an image by the line sensor 42 inside the housing 2 through the transparent sheet 341.

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

As shown in FIG. 3, the document stacking section of the ADF 2 includes a frame 200, a separation roller shaft 221 rotatably supported by the frame 200, and a pair of separation roller shafts 221 mounted on the separation roller shaft 221. The apparatus includes separation roller units 201 and 202 and a hopper 210 rotatably attached to the frame 200.

An edge guide 203 slidable in the width direction of the document is attached to the hopper 210. Of the pair of separation roller units, the separation roller unit 20 is provided.
2 is connected to the edge guide 203 and is slidable along the separation roller shaft 211 together with the edge guide 203. The hopper 210 is inclined as shown in FIG. 4, and can set a plurality of originals 5 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 fed document 5. Since the other side edge is guided by the side wall 204 of the frame, the separation roller unit 201 does not slide on the separation roller shaft 211.

FIGS. 4 and 5 are partial cutaway side views of separation roller units 201 and 202 which are main parts of the document feeding mechanism. In this embodiment, a pair of separation roller units 201 and 202 are used, but there is no difference in the structure and feeding method of the separation roller units 201 and 202.

4 and 5, the separation roller 22
0 indicates that the side surface having the arc portion 222 and the straight portion 223 is substantially D
The surface is formed of a high friction material such as rubber. The separation roller 220 is connected to the bush 2 as shown in FIG.
The separation roller 220 and the bush 224 cannot rotate with respect to the separation roller shaft 221 because the separation roller 220 and the bush 224 are fixed to the separation roller shaft 221 through the separation roller shaft 221. The separation roller shaft 221 is configured to rotate exactly one rotation during the feeding operation by a driving unit (not shown).

The hopper 210 is rotatably attached to the sub-frame 240 of FIG. 1 by a shaft 211 as shown in FIG. A plurality of documents can be stacked on the hopper 210. The leading end of the set document 5 is supported and aligned by contacting the back surface 232 of the separation pad holder 230.

The sub-frame 240 includes a separation roller 220
This sub-frame 240 and the hopper 2
A hopper spring (compression spring) 212
Is provided. Thus, the hopper 210 separates the original 5 in FIG.
0, the cam followers 213 formed at both ends of the hopper 210 are provided with the hopper cam 214 provided on the separation roller shaft 221 as shown in FIG. By the contact, the rotation is restricted. As shown in FIG.
A pad 215 similar to the separation pad 231 is provided on the upper surface of the tip of the ten.

The separation pad 231 is provided for the separation pad holder 2.
30. The separation pad 231 is made of a material having a coefficient of friction with the document 5 smaller than the coefficient of friction between the separation roller 220 and the document 5 and larger than the coefficient of friction between the documents 5, for example, a cork material. Used.
At this time, the friction coefficient between the separation roller 220 and the original 5 is expressed as μ
1. If 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.

As shown in FIG. 4, the separation pad holder 23
0 is the pad support 23 to which the separation pad 231 is fixed.
3, a back portion 232 supporting the leading end of the document 5, and an arm portion 234. The arm portion 234 is rotatably attached to the sub-frame 240 by an attachment portion 241. A pad spring 235 is provided as pad urging means between the lower surface of the pad support portion 233 of the separation pad holder 230 and the subframe 240, and urges the separation pad 231 toward the separation roller 220.

As shown in FIG. 6, the idle roller 250
Is a shaft 251 below the idle roller holder 252.
Is rotatably supported. The idle roller holder 252 to which the idle roller 250 is attached has a pin 255 provided on the idle roller holder 252 as shown in FIG. 7 and a track hole 242 formed in the sub-frame 240 as shown in FIGS. 4 can be slid in the directions of arrows A and B in FIG.

A roller spring 253 is provided above the idle roller holder 252 as urging means for the idle roller 250.
4 is constantly urged in the direction of arrow B in FIG. 4, but its movement is restricted by contacting the separation pad 231. The biasing force of the roller spring 253 is the same as that of the pad spring 2.
Since the urging force is set smaller than 35, the idle roller 250 does not push down the separation pad 231.

Further, as shown in FIG. 6, a cam follower 254 is formed on the idle roller holder 252, and the idle roller 250 is mounted by moving the cam follower 254 into and out of contact with a cam 225 mounted on the separation roller shaft 221. The idle roller holder 252 moves in the directions of arrows A and B in FIG. This cam 225 is
When the leading edge of the fed document 5 passes between the separation pad 231 and the idle roller 250, the idle roller 2
50 is separated from the separation pad 231, and after the leading end of the document 5 passes between the separation pad 231 and the idle roller 250, the arc portion 222 of the separation roller 220 and the separation pad 23 are separated.
The idle roller 250 is formed so as to operate so as to come into contact with the separation pad 231 before the contact with the document 1 via the document 5 is released. When the document 5 is not in contact with the document 5, the document is prevented from moving in a direction other than the transport direction.

Next, an ADF feeding method will be described.

(1) Reference State When the power of the image reading apparatus main body 1 or the ADF 2 is turned on, the reference state before starting the feeding is set as shown in FIG. At this time, the hopper cam 214 is in contact with the cam follower 213 of the hopper 210, and the hopper 210 is in a pressed state. The separation roller 220 has a linear portion 2
23 faces the original 5 and the separation pad holder 230, and the separation roller 220 and the original 5 are not in contact with each other.

(2) Standby state Before starting feeding from the above-mentioned reference state, the state is shifted to a standby state in order to facilitate setting of the original 5. The waiting state is
From the above-described reference state, as shown in FIG.
1 is a state rotated by a predetermined angle in the counterclockwise direction.

When the separation roller shaft 221 rotates counterclockwise, the separation roller 220 and the hopper cam 21 are rotated.
4 also rotates counterclockwise.

The original return lever 260 is turned to the right in FIG. 8 by the protrusion 227 formed on the disk 226 when the disk 226 attached to the separation roller shaft 221 shown in FIG. . In this standby state, since the hopper 210 is pressed down by the hopper cam 214, the separation roller 220 and the document 5 are not in contact with each other, and the document can be easily set on the hopper 210 pressed down. Also, the document return lever 260
Is the separation roller 2 viewed from the axial direction of the separation roller 220.
20 and the separation pad 231, the hopper 210 and the separation roller 220
It is possible to reliably prevent the leading end of the original set between the original and the original from entering the empty space, and prevent the original from being jammed or skewed and fed.

(3) Feeding State After the original is set in the standby state described above, feeding is started by a reading start command from a personal computer or the like (not shown) to the image reading apparatus.

First, the separation roller shaft 221 starts to rotate clockwise (forward rotation) to check the reference state, and while the separation roller shaft 221 continues to rotate clockwise, the separation roller 220, the bush 224, The hopper cam 214 also rotates clockwise.

As shown in FIG. 9, when the hopper cam 214 rotating together with the separation 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 arc portion 222 of the separation roller 220 and the hopper 210 is pushed.
And the separation roller 220.

In this state, the cam 225 of FIG. 6 and the cam follower 254 of the idle roller holder are not yet in contact with each other, and the idle roller 250 is in contact with the separation pad 231 by the urging force of the roller spring 253. The document return lever 260 is pushed by the protrusion 227 of the disk 226 and rotates counterclockwise to the position shown in FIG.

When the separation roller 220 continues to rotate, the arc portion 222 of the separation roller 220 is moved to the uppermost document 5.
1 and is sent toward the separation pad 231, but the top document 51 and the next document 52 may be simultaneously sent to the separation pad 231 due to static electricity or frictional force.
However, the movement of the next document 52 is restricted by contacting the separation pad 231, and the next document 52 is temporarily separated from the top document 52.

When the separation roller shaft 221 continues to rotate, the arc portion 222 of the separation roller 220 moves
1 is pressed against the separation pad 231. The separation pad 231 is pushed down, but simultaneously presses the uppermost document 51 between the arc portion 222 of the separation roller 220 and the separation pad 231 by the urging force of the pad spring 235. At this time, as described above, the next original 52 is also the uppermost original 51.
Sometimes sent with.

However, as described above, the friction coefficient between the separation roller 220 and the uppermost document 51 is μ1, and the separation pad 23
When the friction coefficient between the first document 52 and the next document 52 is μ2, and the friction coefficient between the documents 51 and 52 is μ3, the relationship between these friction coefficients is μ1>μ2> μ3. Arc part 222 of separation roller 220 and separation pad 23
1, the next original 52 is separated from the uppermost original 51 by the movement being regulated by the frictional force with the separation pad 231, and the uppermost original 51 is moved. Only will be fed.

At this point, the idle roller holder 25
2 is pushed up by the cam 225, the idle roller 250 moves in the direction of arrow A in FIG. 4, and is separated from the separation pad 231.
When 1 is fed by the arc portion 222 of the separation roller 220 and passes between the separation pad 231 and the idle roller 250, the idle roller 250 is separated from the separation pad 231.

When the separation roller shaft 221 continues to rotate, the uppermost document 51 is moved to the arc portion 22 of the separation roller 220.
2 and the separation pad 231.
The separation roller 220 continues to rotate with the separation roller shaft 221, and before the contact between the arc portion 222 of the separation roller 220 and the separation pad 231 via the uppermost document 51 is released, the idle roller 250 separates the separation pad 231. Start contact with.

Further, when the separation roller shaft 221 continues to rotate and makes just one rotation from the reference state, the hopper 210 returns to the reference state in which the hopper 210 is pushed down by the hopper cam 214 as shown in FIG. Top-level original 51 to be fed
The feeding by the arc portion 222 of the separation roller 220 is released. At this time, the leading end of the uppermost document 51 has reached the position where the transport roller 12 and the second auxiliary roller 16 shown in FIG. 1 are in contact with each other, and the trailing end is the contact portion between the separation pad 231 and the idle roller 250. Is transported by the transport roller 12 in a state of being in contact with the separation pad 231 and the idle roller 250 until the paper passes through. In addition, idle roller 2
50 is urged by the roller spring 253 toward the separation pad 231 and sandwiches the top document 51 between the separation pad 231 and the next document 52 becomes the top document 5.
1 is prevented from being fed.

As described above, the rear end of the uppermost document 51 is A
After detaching from the DF 2, the next original 52 is fed. However, as shown in FIG. 10, the leading end of the next original 52 descends to near the contact portion between the separation pad 231 and the idle roller 250. In the case of a slippery document such as an OHP sheet, the leading end of the document is
Since the document 1 may pass through the contact portion between the roller 1 and the idle roller 250, if the document is fed as it is, the originals successively enter between the separation roller 220 and the separation pad 231 and are fed twice.

Therefore, in the document separating mechanism of the ADF 2 of this embodiment, after the feeding of the top document 51 is completed, the document returning operation is performed before the feeding of the next document 52.

(4) Original Return Operation From the reference state (FIG. 10) in which the feeding is completed, the separation roller 220, the bush 224, and the hopper cam 214, together with the separation roller shaft 221, start to rotate counterclockwise and rotate by a predetermined angle. Then, as shown in FIG. 11, the edge of the document return lever 260 is pushed by the protrusion 227 of the disk 226 shown in FIG. At this time, the separation pad holder 230 is also pushed down, and the separation pad 231 is separated from the separation roller 220 and the idle roller 250, so that the next original 52 can be reliably pushed back.

Further, as the separation roller shaft 221 rotates in the reverse direction, the document return lever 260 continues to rotate clockwise,
By contacting the hopper cam 214, the next original 52 is reliably pushed back into the hopper 210 which is pushed down. At this time, each unit is in a standby state as shown in FIG.

After the original return operation as described above, if there is a reading command continuously, the separation roller shaft 221 rotates forward,
The feeding state is repeated after the reference state.

Next, an original transport path and an original reading method will be described.

As shown in FIG. 12, the original 5 fed from the original separating mechanism of the ADF 2 comes into contact with the first guide 31. The first guide 31 restricts the document 5 from winding up. After coming into contact with the first guide 31, the document 5 is conveyed in an arc along the conveyance path 6 formed by the first guide 31 and the frame 11 of the ADF 2. Further, since the first guide 31 is rotatably fixed to the cover unit 7 by the guide fixing unit 35, even if the document 5 is jammed in the conveyance path 6, it can be easily removed.

When the document 5 is guided and passed by the transport path 6 formed by the first guide 31 and the frame 11 of the ADF 2,
Subsequently, the sheet is conveyed in an arc shape by the conveyance path 6 formed by the second guide and the frame 11 of the ADF 2, and reaches the conveyance roller 12. The first auxiliary roller 15 provided on the frame 11 of the ADF 2 facing the first guide 31 and the second auxiliary roller 1 provided in contact with the transport roller 12
The guide 6 rotates together with the movement of the original 5 and the guide 3
The function of reducing the transport resistance of the original 5 whose movement is regulated by the first and second 32 and smoothing the original 5 is provided.

When the original 5 arrives at the transport roller 12, skew correction is performed to correct the inclination caused by the original feed by using the stiffness of the original 5. The procedure for removing the skew will be described below.

As shown in FIG. 13, the leading edge of the original 5 which has reached the transport roller 12 in a state of being inclined by the original feed is moved to a contact portion 62 between the forward rotating transport roller 12 and the second auxiliary roller 16. Pass slightly. At this time, the separation roller 220
Is still in contact with the original 5, so that the movement of the rear part of the original 5 is fixed. In this state, the separation roller 220 is stopped, and the rear portion of the original 5 is fixed while FIG.
When only the transport roller 12 is rotated in the direction of the arrow as shown in FIG. 7, the leading edge of the document 5 is also transported in the reverse direction, and the contact between the document 5 and the second auxiliary roller 16 is released, and the movement of the document 5 stops. At this time, the original 5 is bent in the transport path 6, and the front edge of the original 5 is aligned perpendicularly to the transport direction with the contact portion 62 between the transport roller 12 and the second auxiliary roller 16 due to the stiffness of the original 5. As shown in FIG. 15, the transport roller 12 rotates forward again, is transported along the transport path formed by the transparent guide 34 and the transport roller 12, and reaches the image reading position 9. At this time, the separation roller 220 rotates forward and stops when the straight portion 223 and the separation pad 231 face each other.

The original is read line by line at the image reading position 9 by a line sensor 42 provided on 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.

The transport roller 12 rotates so that the document transport speed at the time of reading the document is in accordance with the reading speed of one line of the line sensor 42, and the document 5 is transported. Also, at the time of reading, as shown in FIGS. 10 and 15, the arc portion 222 of the separation roller 220 is stopped at a position where it does not contact the original 5, but as shown in FIG. And the movement of the original 5 is prevented.
The original 5 is transported by the transport roller 12 and the transport roller 1.
2, the document 5 can be conveyed in a stable state without being affected by the separation roller 220.

The separation roller 220 and the transport roller 12
The discharge roller 13 and the discharge roller 13 are driven by the same driving device (not shown), but the control of the normal rotation and stop of the separation roller 220 is performed 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 separation roller drive shaft 221. When the solenoid 243 is energized, the driving force is transmitted to the separation roller shaft 221 by the clutch 228 and the separation roller 220 rotates, but when the solenoid 243 is not energized, the driving force is transmitted to the separation roller shaft 221. Is released, and the separation roller 220 stops. These controls include a sensor (not shown) provided in the transport path 6 for checking the position of a document, and a CP (not shown) provided in the ADF 2 for processing information from the sensor.
Done by U.

In the above case, the original 5 needs to be transported from the separation roller 220 to the transport roller 12, but when the leading end of the original 5 reaches the image reading position 9, the arc 5 It is necessary that the contact between the document 222 and the document 5 is released. Therefore, as shown in FIG.
From the point where the contact between the original 5 and the separation pad 231 is released, that is, the point where the contact between the original 5 and the arc portion 222 of the separation roller 220 is released.
D1 is the distance to the point at which 6 abuts, and separation roller 220
When the length of the arc portion 222 is D2 and the distance from the point at which the contact between the arc portion 222 of the separation roller 220 and the separation pad 231 is released on the transport path 6 to the image reading position 9 is D3, D3> D1, D2, and D3 must be set so that D2> D1.

After passing through the image reading position 9, the original 5
Moves the conveyance path 6 formed by the third guide 33 and the frame 11 of the ADF 2 to the discharge roller 13. The original 5 that has reached the discharge roller 13 is transported by the transport roller 1.
The document 5 is discharged to a discharge tray 14 by a discharge roller 13 that is synchronized with the rotation of the document 2 and a pressing roller 17 that rotates in association with the movement of the document 5. 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 around the surface of the pressing roller 17, and even after the original 5 has passed the contact portion between the discharge roller 13 and the pressing roller 17, the original 5 is securely stopped without stopping. Can be discharged to the discharge tray 14.

When the original 5 is conveyed along the transport path 6, the reading surface of the original 5 stacked on the hopper 210 is on the upper side in FIG. 12, and the original 5 is sent to the ADF 2 in order from the uppermost original. As the document 5 is conveyed, the document reading surface is conveyed in a state of facing the first and second guides 31 and 32 of the arc-shaped conveyance path 6, and faces downward at the image reading position 9. Document 42 can be read by reference numeral 42. The document is conveyed as it is, and remains downward even when the document 5 is discharged. As shown in FIG. 18, the documents stacked before reading can be stacked on the discharge tray in the order.

According to the present embodiment, by using the separation mechanism such as the separation roller, the separation pad, and the document return lever and the ADF having the U-shaped conveyance path, the multi-feed can be performed even when a large number of documents are stacked. The document is sent to the image reading unit in order from the highest document loaded, and the document can be discharged in the same order as before reading after image reading, so that many documents can be read in a short time. Also, after the reading operation, the stacking state is the same as that before the reading, so that it is not necessary to rearrange the originals, and the efficiency of the reading operation can be improved.

According to the present embodiment, the separation roller has a substantially D-shape having a circumferential portion and a linear portion, and the length of the circumferential portion of the separation roller is determined by a distance between the document exit side of the ADF and the conveying roller. Longer than the distance of the conveyance path to the second auxiliary roller and
F is shorter than the distance of the conveyance path from the document exit side of F to the image reading position, so that the document can be reliably conveyed to the conveyance rollers, and the separation roller does not affect the movement of the document at the image reading position. In addition, it is possible to stabilize the transport speed at the time of reading an image, and to prevent wear of the separation roller.

[Brief description of the drawings]

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

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

FIG. 5 is a partially cut-away side view of the ADF according to the embodiment of the present invention, showing a reference state in which a hopper on which a document is loaded is pushed down by a hopper cam.

FIG. 6 is a schematic diagram illustrating a schematic structure of a separation roller unit of an ADF according to an embodiment of the present invention.

FIG. 7 is a schematic perspective view mainly showing a sub-frame and an idle roller holder of the ADF according to the embodiment of the present invention.

FIG. 8 is a partially cutaway side view of the ADF according to the embodiment of the present invention, showing a standby state.

FIG. 9 is a partially cutaway side view of the ADF according to the embodiment of the present invention, showing a state in which a document stacked on a hopper and an arc portion of a separation roller are in contact with each other.

FIG. 10 is a partially cut-away side view of the ADF according to the embodiment of the present invention, showing a state where the uppermost document is being fed.

FIG. 11 is a partially cut-away side view of the ADF according to the embodiment of the present invention, showing a document returning operation.

FIG. 12 is a schematic diagram showing a schematic structure of an ADF according to an embodiment of the present invention.

FIG. 13 is a diagram illustrating the operation of skew removal according to the embodiment of the present invention.

FIG. 14 is an explanatory diagram of an operation of skew removal according to the embodiment of the present invention.

FIG. 15 is an explanatory diagram of an operation of skew removal according to the embodiment of the present invention.

FIG. 16 is an explanatory diagram showing a relationship between the length of the arc portion of the separation roller and the length of the conveyance path according to the embodiment of the present invention.

FIG. 17 is a schematic diagram showing a state in which documents are stacked in a conventional sheet feed type image reading apparatus.

FIG. 18 is a schematic diagram illustrating a state where originals are stacked in the image reading apparatus according to the embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 reading device main body 2 automatic document feeder (ADF) 3 document table 4 carriage 5 document 6 transport path 9 image reading position 10 housing 11 transport frame 12 transport roller 13 discharge roller 15 first auxiliary roller 16 second auxiliary roller 17 Holding roller 31 First guide 32 Second guide 33 Third guide 34 Transparent guide 41 Light source 42 Line sensor 51 Top document 52 Next document 61, 62 Contact portion 210 Hopper 220 Separation roller 221 Separation roller shaft 222 Arc portion 223 Linear portion 230 Separation pad holder 231 Separation pad 250 Idle roller 260 Document return lever 341 Transparent sheet 342 Locking portion 343 Locking hole

Claims (7)

[Claims] A separation roller that contacts a surface of an uppermost document among a plurality of stacked documents and separates and feeds the next document from the next document; and a separation roller provided to face the separation roller, A separation pad that presses against the document and prevents the next document from being fed; a hopper on which a plurality of documents are stacked and pressed against the separation roller via the document during document feeding; and a document fed by the separation roller. A document return lever that rotates after passing through and pushes the leading edge of the next document back into the hopper; a U-shaped conveyance path for guiding the document fed by the separation roller to an image reading position; An automatic document feeder for an image reading device, comprising: a transport roller that transports a document on a path; and a discharge roller that discharges the document. 2. The apparatus according to claim 1, wherein the conveyance path includes a frame of the automatic document feeder, a plurality of guides provided to face the frame, and an auxiliary roller. Automatic document feeder. 3. The automatic document feeder according to claim 1, wherein at least one of the guides has a transparent portion at the image reading position and capable of reading an image. 4. The separation roller is a substantially D-shaped separation roller having a circular arc portion and a straight portion in a side view, wherein the separation pad faces the straight portion of the separation roller during a non-separation operation. 2. A separation pad that maintains an interval between the separation roller and an idle roller that is in contact with the separation pad outside the pair of separation rollers.
Automatic document feeder as described. 5. A length of the arc portion is longer than a distance of a conveyance path from a point where the contact between the arc portion and the document is released to a point where the conveyance roller contacts the document. 5. The automatic document feeder according to claim 1, wherein a distance of a conveyance path from a point at which contact between the sheet and the document is released to the image reading position is shorter. 6. . 6. The device according to claim 1, further comprising means for interrupting the driving force of a driving device at an end of the shaft portion to which the separation roller is attached. Automatic document feeder. 7. The automatic document feeder according to claim 1, wherein a pressing roller is provided at a portion facing the discharge roller.