JP4076682B2 - Automatic document feeder - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to document processing in a copying machine or the like that exposes a document on contact glass and performs copying or data processing, and more particularly, to an automatic document feeder with little unevenness in document feeding.
[0002]
[Prior art]
Conventionally, a copying machine or the like uses an automatic document feeder that transports a document from a set position to an exposure position such as on a contact glass and discharges the document from the exposure position.
[0003]
In this automatic document transport device (which transports and exposes a document to an exposure unit stopped at a predetermined position at a constant speed), a copy image generated due to variations in the document speed transported to the exposure unit at a constant speed Distortion is a problem, and one of the causes is that when the trailing edge of the original passes through the conveyance roller downstream of the exposure unit closest to the exposure unit, the driven roller of the roller is arranged at the same position in the conveyance direction. Therefore, it is known that the conveyance speed varies due to a sudden change in the feed force.
[0004]
[Problems to be solved by the invention]
The present invention has been made against the background of such prior art, and provides a plurality of contact angles of a plurality of driven rollers arranged in the axial direction in contact with a transport roller downstream of the exposure unit closest to the exposure unit. Therefore, the conveyance force when the trailing edge of the document passes through the roller is reduced step by step, and sudden changes in the feeding force when the trailing edge of the document comes off are dispersed in the axial direction to minimize uneven conveyance speed. An object of the present invention is to provide an automatic document feeder that prevents a distortion of a copy image that occurs due to variations in speed.
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 separates and feeds the document on the document placement section, and transports the fed document to a predetermined exposure position and discharges it. And a pressure roller for pressing and conveying the original against the conveyance roller, wherein the pressure roller includes: a conveying roller for conveying the original to an exposure position; A plurality of pressure rollers are provided in the axial direction, and 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 located on the downstream side closest to the exposure position. The contact pressure of the pressure roller disposed in the vicinity of the separation center with respect to the axial direction is higher than the contact pressure of the other pressure rollers. It is characterized by that.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to an automatic document feeder that is used in an apparatus that conveys a document to be read to a fixed reading device unit and reads an image while conveying the document at a predetermined speed.
[0010]
The basic configuration, operation, and action will be described according to the embodiment.
[0011]
1 is a cross-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 cross-sectional view of a reading conveyance roller.
[0012]
Hereinafter, the processing operation for a document bundle of the same size will be described with reference to the drawings.
[0013]
This apparatus includes a document setting unit 1 for setting a document bundle to be read, a separation feeding unit 2 for separating and feeding documents one by one from the set document bundle, and primary abutting and alignment of the fed documents. A resist unit 3 that pulls out and conveys the document after alignment, a turn unit 4 that turns the conveyed document and conveys the document surface toward the reading side (downward), and contacts the surface image of the document First reading / conveying unit 5 for reading from below the glass, second reading / conveying unit 6 for reading the back side image of the original after reading, and a paper discharging unit for feeding the original whose front and back sides have been read to the outside or the reversing unit 7, a reversing unit 8 that performs reversing for re-reading, a stack unit 9 that stacks and holds originals after reading, driving units 101 to 104 that drive these conveying operations, and a series of operations are controlled. Controller unit 100, and a city.
[0014]
The document bundle 13 to be read is set on the document setting table 10 with the leading end abutted against the position of the broken line of the document stopper 25, and the width direction of the document bundle 13 is set to the side guide 11 (not shown). The positioning in the direction orthogonal to the transport direction is performed by.
[0015]
In this state, the document set detection filler 21 is displaced from the broken line position to the solid line position, and accordingly, the shielding of the document set detection sensor 28 is released, and when a document set is detected, the document set detection sensor 28 is detected via the I / F unit 107. A document set signal is transmitted to the main body control unit 111. Further, the document length detection sensors 12 and 14 provided on the surface of the document setting table 10 (a reflection type sensor or an actuator type sensor that can detect even one document) are used. (At least a sensor arrangement that can determine whether the document size is vertical or horizontal is necessary).
[0016]
Thereafter, a document feeding operation is executed by a document 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) (FIG. 4). 5 and 6). The document stopper 25 is retracted to the solid line position by the CW (forward rotation) drive of the calling motor 101 (which is a stepping motor in the embodiment but can be realized by a solenoid), and the leading edge of the document is opened (S1). Thereafter, the pickup roller 20 moves from the broken line position to the upper surface of the document indicated by the solid line position by the reverse drive of the calling motor 101, and is pressed with a predetermined force (S2). The home position sensor 19 is a sensor for detecting the state of the pickup roller 20 and the document stopper 25.
[0017]
When the pick-up roller is pressed, if the number of originals is small, the drop height is large and the cushioning action of the original is small between the original setting table 10 and the pickup roller 20, so that the drop impact sound of the pickup roller 20 is generated. A bug that becomes larger occurs. As a solution to this, a concave roller relief is formed at the contact point of the document setting table 10 with the pickup roller 20, and consideration is given so that the pickup roller 20 does not directly hit the document setting table 10. Yes.
[0018]
Thereafter, after a predetermined time, the paper feed motor 102 that drives the separation feeding unit 2 and the registration unit 3 rotates in the CCW (forward rotation) direction (S3), the pickup roller 20 rotates in the clockwise direction, and the original bundle 13 top sheets are fed 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 so as to be wound around a separation roller 26 provided in an opposing manner. The separation roller 26 is friction-driven through a torque limiter (not shown) having a predetermined magnitude of torque, and is coupled directly with the paper feed belt 23 or via one original. In the state where the paper feeding belt 23 is rotated, it is rotated counterclockwise, and if two or more originals enter between the paper feeding belt 23 and the separation roller 26, the following force is applied to the torque limiter. The separation roller 26 is set to be lower than the torque, and rotates in the clockwise direction, which is the original driving direction, to push back the excess original, thereby preventing double feeding.
[0019]
The original 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 through the paper feed path 27. In this process, the front end is detected by the abutting sensor 29 and further abuts against the resist roller 30 that has stopped. After that, a predetermined distance is sent from the detection of the abutting sensor 29 (S4), and as a result, the paper feeding motor 102 is pressed against the registration roller 30 with a predetermined amount of warpage. By reverse rotation, the driving of the paper feed belt 23 is stopped (S5).
[0020]
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 document, and the document is fed only by the conveying force of the paper feeding belt 23, so that the leading edge of the document is the upper and lower rollers of the registration roller 30. A pair of nips is entered and tip alignment (skew correction) is performed.
[0021]
Thereafter, the registration roller 30 is driven by the reverse rotation of the paper feed motor 102 to convey the document in the direction of the turn portion 4. Here, when feeding the first sheet of the original bundle to the registration stop position, the conveyance speed of the registration roller 30 is set to be higher than the reading speed, and the reading conveyance roller 43 is also driven at the same speed by the reading motor 103. To do.
[0022]
In the case of the second and subsequent sheets, as shown in FIG. 15 and FIG. Since the reading conveyance roller 43 during reading of the document image is driven by the reading motor 103 at a speed corresponding to the reading magnification instructed from the main body control unit 111, the conveyance speed of the next original is the same as the speed of the reading conveyance roller 43. It must be fed at high speed into the nip between the reading and conveying roller 43 and the pressure roller 35.
[0023]
Therefore, when the trailing edge of the document being read passes through the abutting sensor 29, a pulse count for controlling the gap between sheets is started, and the progress of the trailing edge of the document being read is monitored (S23), while the next document is monitored. Start first-out transport.
[0024]
First, the pickup roller 20 is brought into pressure contact with the upper surface of the next original by forward rotation of the calling motor 101, and then the paper feeding motor 102 is driven forward to be conveyed until it comes into contact with the stopped registration roller 30 (S24). Here, the position of the trailing edge of the document being read is calculated from the inter-sheet pulse count value, and when the paper advances from the registration roller 30 by a predetermined interval, the paper feed motor 102 is driven in reverse (S25). It is driven at a high speed as in the case of the first sheet, and is fed to the leading edge detection sensor 34 at this speed, and is decelerated to the reading speed (speed of the reading conveyance roller 43) by the detection of the leading edge detection sensor 34 (S26). By performing this operation between successive original sheets, it is possible to recover the time stopped by the original abutting operation and maintain a predetermined original interval.
[0025]
Further, the width of the leading edge of the document that has passed the registration roller 30 is detected by the size detection sensor 32 in a direction perpendicular to the conveyance direction. When an accurate document size is determined by the 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 controller unit 100 to the main body control unit 111. Is transmitted via the I / F unit 107 (S6 and S26 for the second and subsequent sheets).
[0026]
Thereafter, the document is sent to the nip between the reading conveyance roller 43 and the pressure roller 35, stopped at a position where a predetermined pulse is conveyed from detection of the registration sensor 40, and a registration stop signal is transmitted to the main body control unit 111 to control the main body. It waits for the input of a reading start signal from the unit 111 (a signal transmitted when synchronization with the transfer paper or preparation for storage in the image memory is completed) (S8).
[0027]
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 / conveying unit 5 by the reading / conveying roller 43 and the pressure roller 41 which are rotated by the normal rotation driving of the reading motor 103. The driving speed of the reading motor 103 at this time is determined based on information transmitted from the main body control unit 111 to the controller unit 100 according to a reading magnification input from a main body operation unit (not shown) (S9).
[0028]
The 1st reading conveyance part 5 passes between the reading glass 54 and the white background board 51 arrange | positioned with the predetermined space | interval on the upper surface. During this time, the image is read by a reading system (not shown), electrically converted via the CCD, and stored in a memory device (not shown). The first reading / conveying unit 5 is provided with means for reducing the conveyance gap as much as possible and reducing the degree of freedom of the document as much as possible. As such a method, a method of projecting a flexible guide member from the inner surface of the reading entrance guide 42 toward the white background plate 51 and filling the gap is effective. The white background plate 51 has a gap of about 0.5 mm ± 0.2 mm on the reading glass 54, is pressed with a predetermined elasticity, and errors in the reading depth direction are also suppressed.
[0029]
The surface of the reading glass 54 is treated with a surface active agent (silicon-based activator) so that ink or the like does not easily adhere or adhere to the surface. Further, the above-mentioned flexible guide is extended to the vicinity of the reading point, and the original surface does not positively contact the reading glass 54 at the reading point position, and the front end of the original is wiped near the reading point of the reading glass 54 ( The structure is such that the tip can scrape off foreign matter on the glass surface.
[0030]
The timing at which the leading edge of the document reaches the reading unit is controlled by the pulse count of the reading motor 103, and a surface DF gate signal indicating a surface image effective reading area in the sub-scanning direction is transmitted at this timing (S10). Thereafter, the document advances while being read, and is fed to the intermediate conveyance pressure roller 53 through the pickup guide 52. Since the pressure roller 41 and the intermediate conveyance pressure roller 53 are driven by the reading conveyance roller 43 in common, the feeding and withdrawal speeds are the same, which has the effect of reducing the occurrence of a delivery shock.
[0031]
The document sent out from the first reading and conveying unit 5 by the intermediate conveying and pressing roller 53 is sent to the second reading and conveying unit 6, and a contact image sensor 61 arranged with the reading unit facing downward from the upper surface, and from below. It passes between the pressing members 63 arranged on the reading surface of the contact image sensor 61 with a predetermined pressure and a predetermined interval.
[0032]
In the double-sided mode, the timing at which the leading edge of the document reaches the contact image sensor 61 is controlled by the conveyance pulse count from the detection of the leading edge of the registration sensor 40, and the effective reading area of the back image is transmitted to the contact sensor unit at this timing ( S11).
[0033]
Based on this signal, the image of the surface corresponding to the back side of the document is read, electrically converted in the same manner as the front side, temporarily stored in the frame memory unit 205 shown in FIG. 3, and then transferred to the main body control unit 111. . The pressing member 63 serves as a reference for shading and serves as a white background plate.
[0034]
The pressing member 63 may be configured by a plate-shaped guide member as shown in FIG. 1 or may be configured by a rotating body (not shown).
[0035]
The timing of ending the front and back document reading areas is controlled by the pulse count from the time when the registration sensor 40 detects the trailing edge of the document (S12).
[0036]
Thereafter, the document is discharged to the stack unit 9 by the discharge driving roller 71 and the discharge pressure roller 72. The discharge stacker 90 is configured to be high on the downstream side, and contributes to prevention of jumping out of discharged documents and improvement of stacking document alignment accuracy.
[0037]
During continuous reading of a plurality of documents, the reading motor is stopped by the registration stop operation by the first document advance (FIGS. 15 and 16) rather than the document discharge completion timing. When the reading motor is restarted when reading is started, a paper discharge completion signal is transmitted to the main body control unit 111 when the trailing edge of the original leaves the paper discharge sensor, thereby completing the process (S13).
[0038]
When stacking small-size documents, the reversing switching claw 80 of the reversing unit 8 is switched to the state indicated by the broken line by the reversing switching solenoid 105 to transport the document to the reversing path 83 and from the reversing discharge roller pairs 81 and 82. The paper is discharged onto a small size dedicated stacker 91 configured as a part on the paper discharge stacker 90.
[0039]
This improves the visibility after discharging a small-size document.
[0040]
Further, the document setting table 10 is configured so as to be able to be rotated and retracted around the rotation fulcrum 15 to improve the stack document extraction performance.
[0041]
Further, when the document is discharged, the operation of the reverse switching claw 80 and the trailing edge of the discharged document are synchronized, and immediately after the document is discharged, the reverse switching claw 80 is rotated in the direction of the broken line by the reverse switching solenoid 105 to discharge the original. Control is performed so that the trailing edge of the discharged document is hit to prevent the remaining trailing edge of the discharged document.
[0042]
The above is an overview of the processing for single-sided or double-sided originals with the same size original bundle.
[0043]
Next, processing of single-sided and double-sided originals when sizes are mixed will be described.
[0044]
When the sizes are mixed, since the document lengths are mixed, the document length detection sensors 12 and 14 on the document set table 10 cannot discriminate. Therefore, after separating the documents into one sheet, the trailing edge of the document is the document. The size can be determined only after leaving the bundle 13 and becoming completely independent. For this reason, if you want to determine the document size before reading, set the document path configuration to ½ or more of the maximum document length between the first document trailing edge detection position after separation and the registration sensor position before reading. It is necessary to set the length.
[0045]
If this is satisfied, the document setting position needs to be greatly separated from the reading position, and there is a disadvantage that the part including the document setting table 10 and the conveyance path becomes large and the entire apparatus becomes wide. For this reason, in order to make the apparatus small, it is necessary to devise a method for detecting the document length at the time of mixed loading.
[0046]
As a countermeasure, if the document size cannot be determined before the start of reading at the time of mixed loading, the reading is not performed at all for the first conveyance, and the paper is passed only for reading of the size, and the second time through the reversing unit 8. A method of simultaneously reading the front surface and the back surface when reading is passed (FIGS. 9 to 14).
[0047]
In this case, the conveyance operation until the first registration stop is the same as when processing a bundle of documents of the same size, but the operation after receiving the read start signal transmitted from the main body control unit 111 (particularly the processing after the paper discharge unit 7). Is different.
[0048]
When the paper passes through the reading unit and is discharged, the reverse switching claw 80 is moved in the direction of the broken line by the reverse switching solenoid 105 before the leading edge of the document comes out of the discharge roller pair 71 and 72 (S14). To the reverse path 83 side. Thereafter, the original is fed by the reverse discharge roller pair 81 and 82 driven by the reverse motor 104 until the rear end of the original passes the discharge roller pair 71 and 72. This control is performed by the pulse count from the paper discharge sensor 70 (S16).
[0049]
After the document stops, the reverse switching claw 80 is moved in the direction of the solid line by the reverse switching solenoid 105, and the rear end of the document is directed in the nip direction of the pair of reverse conveying rollers 71 and 85. Thereafter, the reverse paper discharge driving roller 81 rotates in the counterclockwise direction, but the end of the original (which becomes the rear end when viewed from the initial state) is brought into contact with the nip portion of the stopped reverse conveyance roller pair 71, 85, and the front end The skew matching operation is performed (S17), and then the pair of reverse conveying rollers 71 and 85 starts feeding by the reading motor 103, and again passes through the turn unit 4 to the first reading conveying unit 5 and the second reading conveying unit 6. Then, the front and back sides are read (S18).
[0050]
At this time, since the document is in a state where the back side and the front side are reversed, the reading order is the back side first 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 signal is transmitted. (S20). Based on this signal, the page order is changed on the image processing apparatus side.
[0051]
This completes the reading operation, but if the sheet is discharged as it is, the page order will be out of order, so that the reversing operation is repeated once again, and the sheet is discharged (S21).
[0052]
In addition, the conveyance for only the size reading and the conveyance for only the page alignment are configured to be sent at the highest conveyance speed of the apparatus for the conveyance operation not involving image reading, and the loss time can be reduced. Illustrated (S15 and S22).
[0053]
Next, a configuration that does not include the second reading conveyance unit 6 will be described.
[0054]
Although FIG. 1 shows a configuration having a second reading and conveying unit 6 for both-side originals, this reading device is expensive, and even if there is no such device, a reversing mechanism is used to make a double-sided original. Processing is possible. This type is expected to increase in actual products.
[0055]
When the second reading and conveying unit 6 is not provided, the original whose surface has been read by the reading operation of the first reading and conveying unit 5 is conveyed to the first reading and conveying unit 5 again through the reversing unit 8. Then, reading of the back surface is performed, and then the sheet is discharged onto the stack unit 9 through reverse discharge of page alignment.
[0056]
As described above, in an apparatus having no second reading / conveying unit 6, productivity is lowered when double-sided copies are made from double-sided originals. As a countermeasure, a method is adopted in which a plurality of originals are fed into the unit and image reading and reverse document discharge are alternately combined to reduce a paper loss.
[0057]
First, the first original is fed, and one page image reading is executed by the first reading / conveying unit 5, which is sent to the reversing unit 8, and after being abutted and aligned with the pair of reversing conveying rollers 71 and 85, again. The first page is fed into the first reading / conveying unit 5 to read the second page, and is fed into the reversing unit 8 in order to align the page order at the time of paper discharge. Before and after this, the second original is fed, and the first reading conveyance unit 5 reads the third page. Subsequently, reverse discharge of the first original is executed. Further, the reading of the fourth page of the second original is executed subsequently, and then the second original is sent to the reversing unit 8 and the third original is sent before and after this. Perform reading of. Subsequently, the second original is reversed and discharged. In this way, by performing the process between the reverse reading operation of the document that has already been read between the reading of the front surface and the reading of the back surface, the loss time between papers of the reverse discharging operation without reading is minimized. It is possible to stay.
[0058]
Note that this processing is possible only for a document having a size that can be accommodated between the pair of reverse discharge rollers 81 and 82 and the registration sensor 40.
[0059]
Next, a detailed description will be given of the control for simultaneously conveying a plurality of originals in the apparatus.
[0060]
FIGS. 7 to 16 are flowcharts of the next document advance operation (from the document setting position to registration stop) controlled by the paper feed motor 102 of the present invention and the reading operation controlled by the reading motor (explained in the above description). It is.
[0061]
Hereinafter, the next original advance operation and the reading operation will be described.
[0062]
The n-th document that has already been advanced and waits for the input of the start signal from the main body control unit 111 at the registration position starts the operation so that the reading motor 103 conveys the document downstream by the start signal from the main body, and the leading edge of the original Is controlled by the pulse count of the reading motor 103 so that a constant reading speed is obtained at least before reaching the reading position.
[0063]
When the trailing edge of the nth document that has been read is detected by the butting sensor 29, the first-out operation of the (n + 1) th document is started, and at the same time, an inter-sheet pulse count (reading) that determines the timing for driving the registration roller 30 is started. The pulse count of the motor 103) is started.
[0064]
Here, as shown in FIGS. 15 and 16, in the first document advance operation, the reading conveyance roller 43 during reading of the document image is read at a speed corresponding to the reading magnification instructed from the main body control unit 111. Therefore, the conveyance speed of the next original must be sent to the nip between the reading conveyance roller 43 and the pressure roller 35 at the same speed as that of the reading conveyance roller 43. Therefore, when the trailing edge of the document being read passes through the abutting sensor 29, a pulse count for controlling the gap between sheets is started and the progress of the trailing edge of the document being read is monitored (S23). Start first-out conveyance.
[0065]
In the first-out operation, 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 feeding motor 102 is driven to rotate forward and is conveyed until it comes into contact with the stopped registration roller 30 (S24). ). Here, the position of the trailing edge of the document being read is calculated from the inter-paper pulse count value, and when the paper advances from the registration roller 30 by a predetermined paper interval, the paper feeding motor 102 is driven in reverse (S25). And is fed to the leading edge detection sensor 34 at this speed, and is decelerated to the reading speed (speed of the reading conveyance roller 43) by the detection of the leading edge detection sensor 34 (S26).
[0066]
Thereafter, the (n + 1) th original is sent to the nip between the reading conveyance roller 43 and the pressure roller 35, stops at a position where a predetermined pulse is conveyed from detection by 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 reading start signal from the main body control unit 111 (a signal transmitted when the synchronization with the transfer paper or the preparation for storage in the image memory is completed) (S8).
[0067]
The shorter the time between the end of reading the nth image and the stop of the (n + 1) th registration, the higher the production efficiency, and the inter-sheet pulse that determines the timing for driving the registration roller 30 so that this time becomes almost zero. The count is controlled.
[0068]
Further, in order to absorb the conveyance variation to the registration roller 30 of the separation feeding unit 2, theoretically at least 0 or more even in the separation feeding condition that takes the longest time for the leading edge of the document to abut against the registration roller 30 and enter the nip portion. The feeding speed and the feeding timing of the separating / feeding unit 2 are controlled by the calling motor 101 and the sheet feeding motor 102 so as to ensure a sufficient time.
[0069]
Next, the control of the present invention will be described. FIG. 17 is a schematic view of the reading and conveying roller 43 and the pressure roller 41 of the present invention. The right side view of FIG. 17 is the reading conveyance roller 43 and the pressure roller 41 as viewed from the direction shown in FIG. 1, and the front view is a schematic view of the reading conveyance roller 43 and the pressure roller 41 as viewed from the left direction in FIG. is there.
[0070]
The reading / conveying roller of the present invention has, for example, five pressure rollers 41 arranged in the axial direction, and the separation center in the axial direction (the center of the paper feeding belt 23) is the pressure roller as shown in FIG. It is arranged so as to be approximately halfway between 41-b and 41-c, and 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 separated and fed in the conveying direction (direction seen from FIG. 1) compared to the pressure rollers 41-a, 41-d, and 41-e. It is arranged on the side close to the part 2. The pressure rollers 41-b and 41-c may be at the same position in the transport direction, or may be arranged at a certain distance.
[0071]
Further, the pressure rollers 41-b and 41-c have higher pressure contact pressure than the pressure rollers 41-a, 41-d, and 41-e, and the separation feeding unit 2 in all documents that can be passed. It is set so as to be conveyed at a constant speed without being bent and conveyed by a load and without causing the reading roller 41 and the original to slip.
[0072]
That is, the pressure rollers 41-b and 41-c in the separation center generate a conveying force that can be conveyed at a constant speed without bending necessary for reading, and the other pressure rollers are the pressure rollers 41-b and 41-c. When the trailing edge of the original comes off, the pressure is set so that an optimum slip is generated between the reading and conveying roller 43 and the original in order to prevent the conveying force from suddenly disappearing.
[0073]
At this time, since the leading edge of the document has already been conveyed at a constant speed by the pressure roller 55, uneven speed due to slip does not occur. Of course, all the pressure roller pressures may be made constant, but by setting the pressure roller pressure as described above, the fluctuation in the conveyance force when the rear end of the document leaves the pressure roller becomes smaller.
[0074]
Further, as shown in FIG. 17, the pressure rollers 41-a, 41-d, and 41-e are arranged in a letter “C” shape (widening) with respect to the separation center. As a result, the fluctuations 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 fluctuations in the conveyance force can be further reduced.
[0075]
In this embodiment, the separation center is set to be between two pressure roller pairs, and a conveying force capable of conveying at a constant speed without bending necessary for reading is output. It goes without saying that the same effect can be obtained even if the roller pair is arranged in the vicinity of the separation center and the other pressure rollers are arranged as described above.
[0076]
Further, the arrangement of the pressure roller pair set at the separation center and the other pressure rollers is arranged such that the pressure roller pair set at the separation center with respect to the conveying direction is close to the separation feeding unit 2, It is sufficient that the pressure rollers are arranged at least at two locations with respect to the far side and the conveying direction. In this embodiment, the separation center is not located at the center of the transport roller, but it goes without saying that the same effect can be obtained regardless of the position of the separation center.
[0077]
【The invention's effect】
Book According to the invention, since the pressure roller is arranged stepwise with respect to the conveyance direction, the force with which the original is pressed is gradually weakened, and the conveyance force when the rear end of the original passes through the roller is stepwise. It is possible to reduce the variation in the feeding force when the trailing edge of the original comes off and to disperse the unevenness of the conveying speed to the minimum by suppressing the unevenness of the conveying speed, and to prevent the copy image distortion caused by the fluctuation of the original speed.
[0078]
Book According to the invention, since the pressure roller arranged near the center is located farther from the exposure position than the other pressure rollers, it is easy to set the roller pressure and the arrangement of the pressure roller regardless of the document size. Become.
[0079]
Book According to the present invention, since the pressure roller disposed in the vicinity of the center is disposed within a range through which the smallest document that can be conveyed passes, uneven speed of the conveyance roller is prevented in all document sizes that can be passed. be able to.
[0080]
Book According to the invention, the contact pressures of the other pressure rollers are lower than the contact pressures of the pressure rollers arranged near the center, so that the pressure of the pressure roller applied to the end can be kept low. The change in the feeding force when the trailing edge of the document leaves the conveying roller can be reduced in the axial direction, and unevenness in the conveying speed can be prevented.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of a document feeder.
FIG. 2 is a control block diagram according to one embodiment.
FIG. 3 is a control block diagram of one embodiment.
FIG. 4 is a flowchart illustrating document feeding operation processing according to an embodiment.
FIG. 5 is a flowchart illustrating document feeding operation processing according to an embodiment.
FIG. 6 is a flowchart illustrating document feeding operation processing according to an embodiment.
FIG. 7 is a flowchart illustrating document reading operation processing according to an embodiment.
FIG. 8 is a flowchart illustrating document reading operation processing according to an embodiment.
FIG. 9 is a flowchart illustrating document reading operation processing according to an embodiment.
FIG. 10 is a flowchart illustrating document reading operation processing according to an embodiment.
FIG. 11 is a flowchart illustrating document reading operation processing according to an embodiment.
FIG. 12 is a flowchart illustrating document reading operation processing according to an embodiment.
FIG. 13 is a flowchart illustrating document reading operation processing according to an embodiment.
FIG. 14 is a flowchart illustrating document reading operation processing according to an embodiment.
FIG. 15 is a flowchart illustrating next original advance operation processing according to an embodiment;
FIG. 16 is a flowchart illustrating next original advance operation processing according to an embodiment;
FIG. 17 is a cross-sectional view of a reading conveyance roller according to an embodiment.
[Explanation of symbols]
1 Document set section
2 Separate feeding section
3 resist section
4 Turn part
5 First reading transport unit
6 Second reading transport unit
7 Output section
8 Reversing 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 fulcrum
16 Table open / close detection sensor
19 Home position sensor
20 Pickup roller
21 Document set detection filler
22 Belt pulley
23 Paper feed belt
24 belt pulley
25 Document stopper
26 Separation roller
27 Paper feed path
28 Document set detection sensor
29 Butting sensor
30 Registration Roller
32 size detection sensor
34 Tip detection sensor
35 Pressure roller
40 resist sensor
41 Pressure roller
42 Reading Entrance Guide
43 Scanning roller
51 white background board
52 Pickup Guide
53 Intermediate transfer pressure roller
54 Reading glass
61 Contact image sensor
63 Pressing member
70 Paper ejection sensor
71 Paper discharge drive roller
72 Paper discharge pressure roller
73 finished stamp
80 Reverse switching claw
81 Reverse paper discharge drive roller
82 Reversed discharge pressure roller
83 Reverse path
84 Reversing sensor
85 Reverse conveying roller
90 Output stacker
91 Small size stacker
100 Controller
101 Calling motor
102 Paper feed motor
103 Reading motor
104 reverse motor
105 Reverse switching solenoid
107 I / F section
111 Main unit controller
205 Frame memory

Claims (1)

An automatic document feeder comprising: 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.
The transport means includes a transport roller for transporting the document to an exposure position, and a pressure roller for transporting the document by pressing the document against the transport roller;
A position where a plurality of pressure rollers are provided in the axial direction, and the other pressure roller is further away 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. An automatic document feeder , wherein the pressure of the pressure roller disposed near the separation center with respect to the axial direction is higher than the pressure of the other pressure rollers .

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