JP2001066832A - Automatic document feeder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the distortion of a copied image caused by the dispersion of document speed by reducing the carrying force when the trailing edge of a document goes through a roller stepwise, dispersing the sudden change of feeding force when the trailing edge of the document goes through in the axial direction and restraining the unevenness of carrying speed to the minimum in the case of ejecting the document from an exposure part. SOLUTION: As for a carrying roller 43 and a pressure roller 41 carrying the document to the exposure part, the difference of distance from the pressure roller 41 to each exposure position is given to the pressure roller group 41 nearest to the exposure position (41-e<41-c or the like). Thus, the sudden change of the feeding force is restrained and the distortion of the copied image is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document processing apparatus for exposing a document on a contact glass and performing copying or data processing, such as a copying machine, and more particularly, to an automatic document feeder with less uneven feeding of the document.

[0002]

2. Description of the Related Art Conventionally, a copying machine or the like has used an automatic document feeder for transferring a document from a set position to an exposure position such as on a contact glass and discharging the document from the exposure position.

In this automatic document feeder (conveying a document at a constant speed to an exposure unit stopped at a predetermined position and exposing the document), the speed of the document conveyed at a constant speed to the exposure unit varies. One of the causes is that when the trailing edge of the original passes through the transport roller downstream of the exposure unit closest to the exposure unit, the driven roller of the roller is placed at the same position in the transport direction. Therefore, it is known that the transport speed varies due to a sudden change in the feed force.

[0004]

SUMMARY OF THE INVENTION The present invention has been made on the background of the prior art, and a plurality of the rollers are arranged in an axial direction in contact with a transport roller downstream of the exposure unit closest to the exposure unit. By providing a plurality of contact angles for the driven rollers, the transport force when the trailing edge of the document exits the roller is reduced in stages, and the sudden change in feed force when the trailing edge of the document exits is distributed in the axial direction. It is an object of the present invention to provide an automatic document feeder that minimizes unevenness in speed and prevents copy image distortion caused by unevenness in original speed.

[0005]

According to the first aspect of the present invention,
In order to solve the above-mentioned problem, an automatic document feeder includes: a paper feed unit that separates and feeds a document on a document placement unit; and a transport unit that transports the fed document to a predetermined exposure position and discharges the document. In the transport device, the transport unit has a transport roller that transports the document to the exposure position and a pressure roller that transports the document by pressing the document against the transport roller, and a plurality of the pressure rollers in the axial direction, Another pressure roller is provided at a position farther from the exposure position than the pressure roller in the transport direction with respect to the pressure roller on the downstream side closest to the exposure position.

According to a second aspect of the present invention, in order to solve the above-mentioned problem, in the automatic document feeder according to the first aspect, the pressure roller disposed near the center of separation in the axial direction is replaced with another pressing roller. It is characterized in that it is arranged at a position farther from the exposure position in the transport direction than the pressure roller.

According to a third aspect of the present invention, in order to solve the above-mentioned problems, in the automatic document feeder according to the second aspect, the smallest transportable document passes through a pressure roller disposed near the separation center. It is characterized by being arranged within the range.

According to a fourth aspect of the present invention, in order to solve the above problem, in the automatic document feeder according to any one of the first to third aspects, the automatic document feeder is disposed near a separation center in the axial direction. The contact pressure of the pressure roller with respect to the transport roller is higher than the contact pressure of the other pressure rollers.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to an automatic document feeder used in an apparatus which conveys a document to be read to a fixed reading unit and reads an image while conveying the document at a predetermined speed.

The basic configuration, operation, and operation will be described with reference to an embodiment.

FIG. 1 is a sectional view of the apparatus, FIGS. 2 and 3 are control block diagrams, FIGS. 4 to 16 are control flowcharts, and FIG. 17 is a sectional view of a reading and conveying roller.

The operation of processing a bundle of originals of the same size will be described first with reference to the drawings.

The apparatus includes a document set unit 1 for setting a bundle of documents to be read, a separation feeding unit 2 for separating and feeding each document from the set document bundle, and a primary feeding unit for feeding the fed documents. A registration unit 3 having a function of aligning and aligning and pulling out and transporting the aligned document, a turning unit 4 for turning the transported document and transporting the document surface toward the reading side (downward), and a surface image of the document A first reading and conveying unit 5 for reading from below the contact glass, a second reading and conveying unit 6 for reading the back side image of the read document,
A paper discharge unit 7 for sending the original document whose front and back reading has been completed to the outside or to the reversing unit, a reversing unit 8 for performing reversal for re-reading, a stack unit 9 for stacking and holding the document after the reading is completed, Driving units 101 to 10 for driving
4. Controller 10 for controlling a series of operations
0.

The original bundle 13 to be read is set on the original set table 10 with its leading end abutting against the broken line position of the original stopper 25. Further, the width direction of the original bundle 13 is adjusted by the side guide 11 (not shown, front and rear). ) To perform positioning in the direction perpendicular to the transport direction.

In this state, the original set detection filler 21
Is displaced from the position indicated by the broken line to the position indicated by the solid line. With this, the light shielding of the document set detection sensor 28 is released.
1, a document set signal is transmitted. Further, an original length detecting sensor 12 provided on the original set table 10,
14 (A reflective sensor or an actuator type sensor that can detect even one original is used.)
, The approximate length of the document in the transport direction is determined (at least a sensor arrangement that can determine whether the document is the same size vertically or horizontally is necessary).

Thereafter, an original feeding operation is performed by an original feeding signal (a signal input from an operation unit (not shown) and instructed from the main body control unit 111 to the controller unit 100 via the I / F unit 107) (see FIG. 1). 4, 4, 5 and 6). The document stopper 25 is a CW (forward rotation) drive of the calling motor 101 (in the embodiment, a stepping motor,
Evacuate to the position indicated by the solid line.
The leading edge of the document is opened (S1). Thereafter, the pickup roller 20 is moved from the position indicated by the broken line to the upper surface of the document indicated by the position indicated by the solid line by the reverse rotation of the calling motor 101, and is pressed against by a predetermined force (S2). Home position sensor 1
9 is a pickup roller 20 and a document stopper 2
5 is a sensor for detecting the state of FIG.

When the number of originals is small during the pressing operation of the pickup roller, if the number of originals is small, the drop height of the originals is small, and the cushioning effect of the originals between the original set table 10 and the pickup rollers 20 is small. The problem that the impact sound becomes loud occurs.
As a solution to this, a concave roller clearance is formed at the point of contact of the document set table 10 with the pickup roller 20, and care has been taken to prevent the pickup roller 20 from directly hitting the document set table 10. I have.

Thereafter, after a predetermined time, the separation / feed unit 2
And the feed motor 102 for driving the registration unit 3
The pickup roller 20 rotates in the W (forward) direction (S3), and the pickup roller 20 is rotated clockwise to feed the uppermost sheet of the document bundle 13 in the direction of the separation feeding unit 2. At this time, the paper feed belt 23 is stretched around the belt pulleys 22 and 24 with a predetermined tension, and is pressed against the separation roller 26 provided opposite thereto. The separation roller 26 is friction-driven via a torque limiter (not shown) having a predetermined magnitude of torque.
In the case of direct connection with the printer 3 or in the state of connection via one document, the feed belt 23 is rotated in a counterclockwise direction by rotation of the feed belt 23, and two or more documents are fed by any chance. When entering between the belt 23 and the separation roller 26, the co-rotating force is set to be lower than the torque of the torque limiter, and the separation roller 26 rotates clockwise, which is the original driving direction, and is Works to push back the original
Double feed is prevented.

The document separated into one sheet by the action of the paper feed belt 23 and the separation roller 26 is further fed by the paper feed belt 23 and advances in the paper feed path 27. In this process, the leading end is detected by the abutting sensor 29, and the abutting sensor 29 further abuts against the stopped registration roller 30. Thereafter, the sheet is fed by a predetermined distance from the detection of the abutment sensor 29 described above (S4). As a result, the paper feed motor 102 is pressed while being pressed against the registration roller 30 with a predetermined amount of deflection. By reversing the feed belt 23
Is stopped (S5).

At this time, by rotating the calling motor 101 in the CCW direction, the pickup roller 20 is retracted from the upper surface of the original, and the original is fed only by the conveying force of the paper feed belt 23. Of the pair of upper and lower rollers, and the tip is aligned (skew correction).

Thereafter, the registration roller 30 is driven by the reverse rotation of the paper feed motor 102, and conveys the document in the direction of the turn section 4. Here, when the first sheet of the document bundle is fed to the registration stop position, the conveyance speed of the registration roller 30 is set higher than the reading speed, and the reading conveyance roller 43 is also driven by the reading motor 103 at the same speed. I do.

In the case of the second and subsequent sheets, as shown in FIGS. 15 and 16, the form of advance of the next original is adopted. The reading and conveying roller 43 during reading of the original image is driven by the reading motor 103 at a speed corresponding to the reading magnification instructed from the main body control unit 111, so that the conveying speed of the next original is equal to the speed of the reading and conveying roller 43. Fast
It must be fed into the nip between the reading and conveying roller 43 and the pressure roller 35.

When the trailing edge of the original being read passes through the abutting sensor 29, a pulse count for controlling the sheet interval is started, and the progress of the trailing edge of the original being read is monitored (S23). Then, advance feeding of the next original is started.

First, the pickup roller 20 is brought into pressure contact with the upper surface of the next original by the normal rotation of the calling motor 101, and then the paper feed motor 102 is driven to rotate forward to carry the sheet until it hits the stopped registration roller 30 (S24). Here, the rear end position of the document being read is calculated from the inter-sheet pulse count value, and when the sheet advances from the registration roller 30 by a predetermined inter-sheet distance, the sheet feeding motor 102 is driven to rotate in the reverse direction (S
25), the registration roller 30 is driven at a high speed similarly to the first sheet, is fed to the leading edge detection sensor 34 at this speed, and is decelerated to the reading speed (the speed of the reading transport roller 43) by the detection of the leading edge detection sensor 34.
(S26). By performing this operation between successive documents, it is possible to recover the time stopped in the document abutting operation and maintain a predetermined document interval.

The width of the leading end of the document past the registration roller 30 is detected by the size detection sensor 32 in the direction perpendicular to the conveyance direction. When an accurate document size is determined by a combination of the width signal and the length signals obtained by the document length detection sensors 12 and 14, the document size signal is sent to the main body control unit 111 by the controller unit 100. The data is transmitted via the I / F unit 107 (S6 and S26 for the second and subsequent sheets).

Thereafter, the original is sent to the nip between the reading and conveying roller 43 and the pressure roller 35, stops at a position where a predetermined pulse has been conveyed from the detection of the registration sensor 40, and transmits a registration stop signal to the main body control unit 111. Then, it waits for an input of a read start signal (a signal transmitted at the time of preparation for synchronizing with the transfer paper or storing in the image memory) from the main body control unit 111 (S8).

Next, an original reading operation is executed by inputting a reading start signal (FIGS. 7 to 14).
The document whose registration is stopped is sent to the first reading and conveying unit 5 by the reading and conveying roller 43 and the pressing roller 41 which are rotated by the normal rotation of the reading motor 103. The driving speed of the reading motor 103 at this time depends on the reading magnification input from a main body operation unit (not shown).
The determination is made based on information transmitted from the main body control unit 111 to the controller unit 100 (S9).

The first reading / transporting section 5 passes between a reading glass 54 and a white background plate 51 arranged at a predetermined interval on the upper surface thereof. During this time, the image is read by a reading system (not shown), electrically converted via a CCD, and stored in a memory device (not shown). The first reading / transporting unit 5 takes a transport gap as narrow as possible, and measures are taken to minimize the degree of freedom of the original. As a method, the reading entrance guide 4
For example, a method of extending a flexible guide member from the inner surface of the second member toward the white background plate 51 to fill the gap is effective. Further, the white background plate 51 has a gap of about 0.5 mm ± 0.2 mm on the reading glass 54, is pressed against with predetermined elasticity, and an error in the reading depth direction is suppressed.

The surface of the reading glass 54 is treated with a surfactant (silicone-based activator) so that ink or the like hardly adheres or adheres. In addition, the above-mentioned flexible guide is extended to the vicinity of the reading point. At the reading point position, the document surface does not actively contact the reading glass 54, and the leading edge of the document wipes the vicinity of the reading point of the reading glass 54 ( The tip is configured so that foreign matter on the glass surface can be scraped off at the tip.

The timing at which the leading edge of the document arrives at the reading section is controlled by the pulse count of the reading motor 103, and a front DF gate signal indicating the front image effective reading area in the sub-scanning direction is transmitted at the timing (S1).
0). After that, the document advances while reading, and is sent to the intermediate conveyance pressure roller 53 via the pickup guide 52. Since the pressure roller 41 and the intermediate conveyance pressure roller 53 are commonly driven by the reading conveyance roller 43, the feeding speed and the pulling speed are the same, which has the effect of reducing the occurrence of a transfer shock.

The original sent from the first reading / conveying section 5 by the intermediate conveying / pressing roller 53 is sent to the second reading / conveying section 6, and the contact image sensor 61 disposed with the reading section downward from the upper surface. Then, it passes between the pressing members 63 arranged at a predetermined pressure and a predetermined interval on the reading surface of the contact image sensor 61 from below.

In the case of the double-sided mode, the timing at which the leading edge of the document reaches the close contact image sensor 61 is controlled by the conveyance pulse count from the leading end detection of the registration sensor 40, and at this timing, the effective reading area of the back side image is sent to the close contact sensor unit. It transmits (S11).

Based on this signal, the image of the surface corresponding to the back side of the original is read and converted electrically like the front side,
After being temporarily stored in the frame memory unit 205 shown in FIG. The pressing member 63 is
It serves as a reference for shading and as a white background plate.

The pressing member 63 may be constituted by a plate-like guide member as shown in FIG. 1, or may be constituted by a rotating body (not shown).

The timing of terminating the original reading area on the front and back sides is controlled by the pulse count from the time when the registration sensor 40 detects the rear end of the original (S1).
2).

Thereafter, the original is discharged to the stack unit 9 by the discharge drive roller 71 and the discharge pressure roller 72.
The discharge stacker 90 is configured to be high on the downstream side, and contributes to preventing discharge documents from jumping out and improving stack document alignment accuracy.

At the time of continuous reading of a plurality of originals, the next original is advanced before the original discharge completion timing (see FIGS. 15 and 1).
Since the drive of the reading motor is stopped by the registration stop operation according to 6), the discharge operation of the read original is resumed when the rear end of the original passes through the paper discharge sensor by resuming the driving of the read motor by starting reading of the next original. A discharge completion signal is transmitted to the main body controller 111 to complete the processing (S13).

When stacking small size documents, the reversing switching claw 80 of the reversing section 8 is turned over to the reversing switching solenoid 1.
05 to the state shown by the broken line,
The original is conveyed to the stacker 90 and is discharged from the pair of reverse discharge rollers 81 and 82 onto a small-size stacker 91 configured as a part of the discharge stacker 90.

As a result, the visibility of the small-size document after the discharge is improved.

The document set table 10 is configured so as to be able to retreat upward around the rotation fulcrum 15,
The ability to take out stack documents is improved.

When the original is ejected, the operation of the inversion switching claw 80 is synchronized with the trailing end of the ejected original, and immediately after the original is ejected, the inversion switching claw 80 is rotated in the direction of the broken line by the inversion switching solenoid 105. A control is performed to strike the trailing end of the discharged document and prevent the trailing end of the discharged document from remaining.

The above is one side of the same size original bundle or
This is an outline of the processing for a two-sided original.

Next, processing of single-sided and double-sided originals when mixed sizes are described.

At the time of mixed size, since the document lengths are mixed, the document length detection sensors 12 and 14 on the document set table 10 cannot distinguish them. The size can be determined only when the end separates from the original bundle 13 and becomes completely independent. Therefore, if you want to determine the original size before scanning, change the original path configuration from the first original trailing edge detection position after separation to the registration sensor position before scanning by half or more of the maximum original length. Must be set to the length.

When this is satisfied, the original setting position is
There is a disadvantage that it is necessary to be largely separated from the reading position, the portion including the document set table 10 and the transport path becomes large, and the whole apparatus becomes wide. Therefore, in order to make the apparatus small, it is necessary to devise a method for detecting the length of the original when the originals are mixed.

As a countermeasure, if the original size cannot be determined before reading when mixed sizes are loaded, no reading is performed in the first conveyance, and the paper is passed only for reading the size, A method is adopted in which the front surface and the back surface are read at the same time during the second reading pass (FIGS. 9 to 14).

In this case, the transport operation up to the first registration stop is the same as that for processing a bundle of originals of the same size, but the operation after receiving the read start signal transmitted from the main body control unit 111 (particularly after the paper discharge unit 7) Is different).

When the document is discharged through the reading unit, the reversing switching claw 80 is moved in the direction of the broken line by the reversing switching solenoid 105 before the leading edge of the document comes out of the discharge rollers 71 and 72 (S14). ), The original is turned over
Side. Thereafter, the document is sent by the pair of reverse discharge rollers 81 and 82 driven by the reverse motor 104 until the rear end of the document passes through the pair of discharge rollers 71 and 72.
This control is performed by a pulse count from the paper discharge sensor 70 (S16).

After the document is stopped, the reversing switching claw 80 is moved in the solid line direction by the reversing switching solenoid 105, and the rear end of the document is directed to the nip direction of the pair of reversing conveyance rollers 71 and 85. Thereafter, the reversing discharge drive roller 81 rotates counterclockwise in the counterclockwise direction, and abuts the original end (which is the rear end when viewed from the initial state) against the nip portion of the reversal conveyance roller pair 71, 85 which is stopped. A skew matching operation is performed (S17),
Thereafter, the pair of reverse conveying rollers 71 and 85 starts feeding by the reading motor 103, passes through the turn section 4 again, and returns to the first reading conveying section 5 and the second reading conveying section 6.
And the front and back are read (S18).

At this time, since the back side and the front side of the document are reversed, the reading order is the back side and the front side is read later, first, the back side gate ON signal is transmitted (S19), and then the front side gate signal ON. A signal is transmitted (S20).
On the basis of this signal, the image processing apparatus performs a page order change process.

Now that the reading operation has been completed,
If the sheet is ejected as it is, the page order will be out of order, and the sheet is ejected after repeating the reversing operation again (S21).

The transport for the size reading only and the transport for the page alignment only are performed at the highest transport speed of the apparatus because of the transport operation without image reading. (S
15 and S22).

Next, a description will be given of a configuration having no second reading / transporting section 6.

FIG. 1 shows a configuration having a second reading / conveying unit 6 for both-side originals. However, this reading device is expensive, and even in a configuration without this device, a reversing mechanism is used. And double-sided document processing is possible. It is thought that this type will increase as an actual product.

If the second reading / transporting unit 6 is not provided, the original whose front surface has been read by the above-described reading operation by the first reading / transporting unit 5 passes through the reversing unit 8 and is again returned to the first reading / transporting unit. The sheet is transported to the stack 5 and the back side is read. Thereafter, the sheet is discharged onto the stack section 9 through reverse discharge of page alignment.

As described above, in an apparatus having no second reading / transporting section 6, productivity is reduced when a double-sided copy is made from a double-sided original. As a countermeasure, a method has been adopted in which a plurality of originals are fed into a unit, image reading is performed, and original reversal discharge is alternately combined to reduce inter-sheet loss.

First, the first original is fed, and the first reading / transporting unit 5 reads an image of one page, and then feeds it to the reversing unit 8 to make it abut against the pair of reversing transport rollers 71 and 85 for alignment. Thereafter, the sheet is sent to the first reading / conveying unit 5 again to read the second page, and is sent to the reversing unit 8 in order to align the page order when the sheet is discharged. Around this, a second document is fed, and the first reading / transporting unit 5 reads the third page. Subsequently, the reverse discharge of the first document is executed. Subsequently, the fourth page of the second document is read. Thereafter, the second document is sent to the reversing unit 8, and before and after the third document, the third document is sent. Perform a read of. Subsequently, the reverse discharge of the second document is performed. In this manner, by performing the processing with the reversal discharge operation of the document already read between the front surface reading and the back surface reading, the inter-sheet loss time of the reversal discharging operation without performing the reading is minimized. It is possible to stop.

Note that this processing can be performed only on a document having a size that can be accommodated between the pair of reverse discharge rollers 81 and 82 and the registration sensor 40.

Next, the control of a plurality of originals of the present apparatus being simultaneously conveyed in the apparatus will be described in detail.

FIGS. 7 to 16 show the sheet feeding motor 10 according to the present invention.
2 is a flowchart of the next original advance operation (from the original set position to the registration stop) controlled by the scanner 2 and a flowchart of the reading operation controlled by the reading motor (described in the overall description).

Hereinafter, the next original advance operation and the reading operation will be described.

The n-th original, which has already been advanced and waits for a start signal from the main body controller 111 at the registration position, reads the motor 1 by the start signal from the main body.
The reading motor 103 controls the pulse count of the reading motor 103 so that the reading operation is started at a position before the leading end of the document reaches at least the reading position.

When the abutting sensor 29 detects the trailing end of the n-th document from which the reading has been started, the advance operation of the (n + 1) -th document is started, and at the same time, the sheet interval pulse for determining the timing for driving the registration roller 30 Counting (pulse counting of the reading motor 103) is started.

Here, as shown in FIGS. 15 and 16, the advance operation of the next original is performed by the reading / conveying roller 43 during reading of the original image at a speed corresponding to the reading magnification instructed from the main body control unit 111. Since the document is driven by the reading motor 103, the next document must be fed into the nip between the reading and conveying roller 43 and the pressure roller 35 at the same speed as that of the reading and conveying roller 43. Then, when the trailing edge of the original being read passes through the abutting sensor 29, a pulse count for controlling the sheet interval is started, and the progress of the trailing edge of the original being read is monitored (S23). Start the advance conveyance.

In the advance operation, first, the calling motor 10
The pickup roller 20 is pressed against the upper surface of the next original by the normal rotation of 1, and then the paper feed motor 102 is driven to rotate in the normal direction to carry the sheet until it hits the stopped registration roller 30 (S24). Here, the rear end position of the document being read is calculated from the sheet interval pulse count value,
When a predetermined paper interval has elapsed from 0, the paper feed motor 102 is driven to rotate in the reverse direction (S25), and the registration roller 30 is driven at a high speed and fed to the leading edge detection sensor 34 at this speed. The speed is reduced to (the speed of the reading conveyance roller 43) (S26).

Thereafter, the (n + 1) th original is sent to the nip between the reading and conveying roller 43 and the pressure roller 35, stops at a position where a predetermined pulse has been conveyed from the detection of the registration sensor 40, and outputs a registration stop signal to the main body controller 111. And waits for an input of a read start signal (a signal transmitted at the time of preparation for synchronizing with the transfer paper or storing in the image memory) from the main body control unit 111 (S8).

The shorter the time between the end of reading the n-th image and stopping the registration of the (n + 1) -th image, the higher the production efficiency becomes.
The inter-sheet pulse count for determining the timing for driving 0 is controlled.

Further, the registration roller 30 of the separation feeding section 2
In order to absorb the variation in conveyance up to the point, the separation and feeding should be performed so that the time when the leading edge of the document abuts on the registration roller 30 and reaches the nip portion at least becomes zero or more even under the separation feeding condition that takes the longest time. Sending unit 2
The transfer speed and transfer timing of the motor 10
1, controlled by a paper feed motor 102.

Next, the control of the present invention will be described. FIG. 17 shows the reading / conveying roller 43 and the pressing roller 4 of the present invention.
1 is a schematic view of FIG. The right side view of FIG. 17 shows the reading and conveying roller 43 and the pressure roller 41 as viewed from the direction shown in FIG. 1, and the front view is a schematic diagram of the reading and conveying roller 43 and the pressure roller 41 as viewed from the left side in FIG. is there.

In the reading and conveying roller of the present invention, for example, five pressure rollers 41 are arranged in the axial direction, and as shown in FIG.
(The center of the paper) is located substantially in the middle between the pressure rollers 41-b and 41-c, and is located inside the minimum width (axial direction) that allows paper to pass. The pressure rollers 41-b and 41-c arranged at the separation center are pressure rollers 41-a, 41-c.
As compared with d and 41-e, it is arranged on the side closer to the separation feeding unit 2 with respect to the transport direction (the direction viewed from FIG. 1). The pressure rollers 41-b and 41-c may be at the same position in the transport direction, or may be arranged at a fixed distance.

The pressure rollers 41-b and 41-c are
The pressure contact pressure is higher than the pressure rollers 41-a, 41-d, and 41-e, so that all of the originals that can be passed through are not bent and conveyed by the load of the separation feeding unit 2, The document is set to be conveyed at a constant speed without slipping.

That is, the pressure roller 41 at the separation center
-B and 41-c output a conveying force capable of conveying at a constant speed without bending required for reading, and the other pressing rollers suddenly move when the rear ends of the originals pass through the pressing rollers 41-b and 41-c. The pressing force is set so that an optimum slip occurs between the reading and conveying roller 43 and the document in order to prevent the conveyance force from being lost.

At this time, since the leading end of the document has already been conveyed at a constant speed by the pressure roller 55, speed unevenness due to slip does not occur. Of course, all the pressure roller pressures may be kept constant, but by setting the pressure roller pressures as described above, the fluctuation of the conveying force when the trailing edge of the document passes through the pressure rollers becomes smaller.

The pressure rollers 41-a, 41-d, 4
1-e is “C” with respect to the separation center as shown in FIG.
It is arranged in the shape of a letter (tail spread). As a result, the change in the conveyance force when the trailing edge of the document passes through the pressure roller is further subdivided in the axial direction, and the change in the conveyance force can be further reduced.

In this embodiment, the separation center is set between the two pressure roller pairs, and a conveying force capable of conveying at a constant speed without bending required for reading is provided. It is needless to say that the same effect can be obtained by disposing the pressure roller pair in the vicinity of the separation center and arranging the other pressure rollers as described above.

The arrangement of the pressure roller pair set at the separation center and the other pressure rollers is such that the pressure roller pair set at the separation center in the transport direction is
, And at least two other pressure rollers at the far side and at least two positions in the transport direction. Further, in the present embodiment, the separation center is not at the center of the transport roller, but it goes without saying that the same effect can be obtained regardless of the position where the separation center is set.

[0077]

According to the first aspect of the present invention, since the pressure roller is disposed stepwise in the transport direction, the force of pressing the document gradually decreases, and the rear end of the document is The transport force when exiting the document gradually decreases, and the sudden change in feed force when the trailing edge of the document exits is dispersed in the axial direction, minimizing transport speed unevenness, and copying that occurs because the document speed varies. Image distortion can be prevented.

According to the second aspect of the present invention, since the pressure roller disposed near the center is located farther from the exposure position than the other pressure rollers, the roller pressure and the pressure can be adjusted regardless of the document size. It is easy to set the arrangement of the pressure roller.

According to the third aspect of the present invention, since the pressing roller disposed near the center is disposed within a range in which the smallest conveyable document passes, the conveyer roller is conveyed in all the document sizes that can be passed. It is possible to prevent unevenness in the speed at which the roller comes off.

According to the fourth aspect of the present invention, since the contact pressure of the other pressure rollers is lower than the contact pressure of the pressure roller disposed near the center, the pressure roller applied to the end Can be kept low, and the change in the feeding force when the trailing edge of the document passes through the transport roller can be dispersed in the axial direction to reduce the change, thereby preventing uneven transport speed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an embodiment of a document feeder.

FIG. 2 is a control block diagram of one embodiment.

FIG. 3 is a control block diagram of one embodiment.

FIG. 4 is a flowchart illustrating a document feeding operation process according to an embodiment;

FIG. 5 is a flowchart illustrating a document feeding operation process according to an embodiment;

FIG. 6 is a flowchart illustrating a document feeding operation process according to an embodiment;

FIG. 7 is a flowchart illustrating a document reading operation process according to an embodiment;

FIG. 8 is a flowchart illustrating a document reading operation process according to an embodiment.

FIG. 9 is a flowchart illustrating a document reading operation process according to an embodiment.

FIG. 10 is a flowchart illustrating a document reading operation process according to an embodiment.

FIG. 11 is a flowchart illustrating a document reading operation process according to an embodiment.

FIG. 12 is a flowchart illustrating a document reading operation process according to an embodiment;

FIG. 13 is a flowchart illustrating a document reading operation process according to an embodiment.

FIG. 14 is a flowchart illustrating a document reading operation process according to an embodiment.

FIG. 15 is a flowchart illustrating a next original advance operation process according to the embodiment;

FIG. 16 is a flowchart illustrating a next original advance operation process according to the embodiment;

FIG. 17 is a cross-sectional view of a reading and conveying roller according to an embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Document setting part 2 Separation feeding part 3 Registration part 4 Turn part 5 First reading conveyance part 6 Second reading conveyance part 7 Paper discharge part 8 Inversion part 9 Stack part 10 Document setting table 11 Side guide 12 Document length detection sensor 13 Document Bundle 14 Document Length Detection Sensor 15 Rotation Support 16 Table Open / Close Detection Sensor 19 Home Position Sensor 20 Pickup Roller 21 Document Set Detection Filler 22 Belt Pulley 23 Feeding Belt 24 Belt Pulley 25 Document Stopper 26 Separation Roller 27 Feeding Path 28 Document set detection sensor 29 Butt sensor 30 Registration roller 32 Size detection sensor 34 Tip detection sensor 35 Pressure roller 40 Registration sensor 41 Pressure roller 42 Reading entrance guide 43 Reading conveyance roller REFERENCE SIGNS LIST 51 White background plate 52 Pickup guide 53 Intermediate transport press roller 54 Reading glass 61 Close contact image sensor 63 Press member 70 Discharge sensor 71 Discharge drive roller 72 Discharge press roller 73 Finished stamp 80 Reverse switching claw 81 Reverse discharge drive Roller 82 Reverse discharge pressure roller 83 Reverse path 84 Reverse sensor 85 Reverse transport roller 90 Discharge stacker 91 Small size dedicated stacker 100 Controller 101 Calling motor 102 Feed motor 103 Reading motor 104 Reverse motor 105 Reverse switching solenoid 107 I / F section 111 Body control section 205 Frame memory section

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H076 BA24 3F049 DA12 DA19 LA02 LB02 5C062 AA02 AA06 AB31 AB32 AB53 AC12 AD06 AF10 BA00

Claims (4)

[Claims] An automatic document feeder comprising: a sheet feeder for separating and feeding a document on a document placement section; and a feeder for feeding and feeding the fed document to a predetermined exposure position. In the above, the conveying means includes a conveying roller for conveying the original to an exposure position, and a pressing roller for pressing and conveying the original against the conveying roller, and having a plurality of the pressing rollers in an axial direction. Automatic feeding of an original document, wherein another pressing roller is provided at a position farther from the exposure position than the pressing roller in the feeding direction with respect to the pressing roller on the downstream side closest to the exposure position. apparatus. 2. The automatic document feeder according to claim 1, wherein the pressure roller disposed near the separation center with respect to the axial direction is moved from the exposure position in the transport direction more than other pressure rollers. An automatic document feeder which is arranged at a remote position. 3. The automatic document feeder according to claim 2, wherein the pressure roller disposed in the vicinity of the separation center is disposed within a range where a minimum transportable document passes. apparatus. 4. The automatic document feeder according to claim 1, wherein a contact pressure of the pressing roller, which is disposed near the separation center with respect to the axial direction, with respect to the transfer roller, is further reduced. Wherein the contact pressure is higher than the contact pressure of the pressure roller.