JP2005094060A - Image reading apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reading apparatus capable of suppressing speed variations in an original by more stabilizing the attitude of the original at image reading than that of prior arts. <P>SOLUTION: The image reading apparatus is provided with: a fixed image read means; and a plurality of original carrying means for carrying the original, and uses the image read means to read an image on the original while the original carrying means carry the original at a prescribed speed, pickup guides (52a, 52b) are provided with projections (56a, 56b) for applying restriction to the original whose tail end is escaped from a pair of a pressure roller 41 / a read carrying roller 43a being the original carrying means at an upperstream of the original read position and closest to an original read position from both sides of a gap of the original carrying path in an opposite directions to each other, and the positions of the projections (56a, 56b) are selected between the original read position and a pair of a read carrying roller 43b/intermediate conveyance pressure roller 53 being the original carrying means at a downstream of the original read position and closest to the original read position. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image reading apparatus mounted on a copying machine, a facsimile machine, a scanner, or the like, and more particularly, includes a fixed image reading means, and uses an image reading means while conveying an original at a predetermined speed by an original conveying means. The present invention relates to a transport mechanism of an image reading apparatus that reads an image on a document.

In response to market demands for space savings in office equipment such as copiers and facsimile machines, there is a growing demand for downsizing of image reading devices built into office equipment. Therefore, an automatic document feeder (hereinafter referred to as ADF) that can read the document is desired. In addition, since productivity improvement is also strongly desired, in recent years, an ADF (hereinafter referred to as a sheet-through type) ADF (hereinafter referred to as a sheet-through method) that reads an image by stopping an image reading unit such as an exposure apparatus and conveying an original at a predetermined speed. Demand for sheet-through ADF is increasing. In recent years, copying machines and scanners have shifted from monochrome machines to full-color machines, and sheet-through ADFs have been installed in full-color machines.
In such a sheet-through ADF, in order to achieve a reading quality of 600 dpi level, a general office full-color reading means uses many three-line CCDs. In such an example, however, reduction by coating each color of RGB. A mold CCD is arranged at a predetermined interval, and an image is formed by correcting a deviation corresponding to each CCD line interval.
When this type of CCD receives fluctuations in the document reading speed, a deviation occurs between the set correction amount of each CCD line interval deviation and the actual deviation amount, resulting in color deviation in the image. In the sheet-through ADF, an image is read by conveying the document at a predetermined speed on the ADF side, but the leading end of the document reaches a roller pair (or a roller pair or a roller roller pair) as document conveying means before and after the reading position. Variations in the document conveyance speed that occur when the trailing edge of the document passes or the like cause color misregistration, which is a technical problem in mounting a sheet through ADF in a full-color machine. Such a shift has an adverse effect not only on the image quality, but also on the function of determining whether the document is monochrome or color and the function of determining whether the document is text or photograph.

FIG. 17 is an example of a reading vicinity portion of the sheet-through ADF in the prior art. As shown in FIG. 17, when there are independent conveying rollers (43a, 43b) upstream and downstream of the reading position (the central portion of the reading glass 54), in order to prevent the deflection of the document in the reading portion, The linear speed is set so that the linear speed in the intermediate conveyance pressure roller 53 is higher than that of the pressure roller 41. In such a state, the document is pulled by the intermediate conveyance pressure roller 53 located downstream, and the document always tries to take the shortest path (see FIG. 17B). Here, when the trailing edge of the document comes off from the pressure roller 41 located upstream, the document feeding speed in the reading unit increases. Further, when both sides are sandwiched, the document is slightly lifted from the reading unit as shown in FIG. 17B, but at the moment when the trailing edge of the document is removed from the pressure roller 41, the document itself has. It swells to the outer peripheral side due to the characteristics (the waist of the document) (see FIG. 17C). As a result, the document conveyance speed in the reading unit after the document trailing edge passes through the pressure roller 41 becomes unstable.
The prior art disclosed in Japanese Patent Laid-Open No. 2001-33100 is intended to solve such a problem, and as shown in FIG. 18, between the reading unit and the pickup guide units 52a and 52b, or the pickup guide 52b. The protrusion 56 is configured to suppress the increase in the conveyance speed.
JP 2001-33100 A

However, in the prior art disclosed in Japanese Patent Laid-Open No. 2001-33100 described above, FIG. 18C shows a reaction when the trailing edge of the document is separated from the pressure roller 41 and comes out of the reading entrance guide 42. Thus, when a situation where the document is above the protrusion 56 dynamically occurs, the document becomes unregulated and the posture becomes unstable. Therefore, in this prior art, there remains a problem that the effect of suppressing fluctuations in the document speed is insufficient.
An object of the present invention is to solve such a problem of the prior art. Specifically, it suppresses fluctuations in the speed of the original by stabilizing the attitude of the original at the time of image reading by an improved method. An object of the present invention is to provide an image reading apparatus capable of performing the above. It is another object of the present invention to provide an image reading apparatus that can transport a document without damaging it and can stabilize the transportability of a thin paper document. In addition, the shape of the guide plate for realizing this can be simplified, and speed fluctuation suppression can be realized while avoiding interference of the conveying parts.

In order to solve the above-mentioned problem, the invention according to claim 1 comprises a fixed image reading means and a plurality of document conveying means for conveying the document, and the document conveying means conveys the document at a predetermined speed. On the other hand, in the image reading apparatus that reads an image on the document by the image reading unit, the document conveying path is arranged with respect to the document that has passed through the document conveying unit that is upstream from the document reading position and closest to the document reading position. A restricting means for restricting the opposite sides from both sides of the gap is provided between the document conveying means and the document reading position downstream of the document reading position and closest to the document reading position.
According to a second aspect of the present invention, in the first aspect of the present invention, the restricting means is a convex portion projecting from the document conveying path.
According to a third aspect of the present invention, in the second aspect of the present invention, when the document conveying path is curved, the upstream convex portion of the two convex portions forming a pair is arranged on the inner peripheral side, and the downstream side. The convex part of the side was provided in the outer peripheral side.
According to a fourth aspect of the present invention, in the first or second aspect of the invention, the restricting means includes an original contact portion closest to the original reading position, an original passage point at the position of the restricting means, The document contact portion at the position of the document transporting unit that is downstream of the document reading position and closest to the document reading position is arranged in a substantially straight line.
According to a fifth aspect of the present invention, in the first or second aspect of the present invention, the restricting means is arranged in a state of being divided in the width direction.
According to a sixth aspect of the invention, in the fifth aspect of the invention, the restricting means is a plurality of rib-shaped convex portions provided on the document guide.

According to the present invention, in the first aspect of the invention, when reading an image on a document while conveying the document at a predetermined speed, the document is moved from the document conveying means that is upstream from the document reading position and closest to the document reading position. For a document with a missing edge, a restriction is imposed between the document conveying means downstream of the document reading position and the document reading position closest to the document reading position in the opposite direction from both sides of the gap in the document conveying path. Therefore, the posture of the document at the time of image reading can be stabilized as compared with the conventional one, and therefore the speed fluctuation of the document can be more effectively suppressed.
Further, in the invention described in claim 2, in the invention described in claim 1, since the restricting means is a convex portion projecting from the document conveying path, the restricting means can be easily realized.
According to a third aspect of the present invention, in the second aspect of the present invention, when the document transport path is curved, the upstream convex portion of the pair of two convex portions is located on the inner peripheral side, and the downstream side. Since the convex portion is provided on the outer peripheral side, a force toward the outer peripheral side acts on the exit side of the reading unit, so that the original always has a shape along the outer periphery, and stable conveyance can be obtained.
According to a fourth aspect of the present invention, in the first or second aspect of the present invention, the document contact portion closest to the document reading position, the document passage point at the position of the regulating means, the downstream of the document reading position, and Since the original contact portion at the position of the original conveying means closest to the original reading position is positioned substantially in a straight line, the original can be smoothly conveyed, and therefore the original can be conveyed without being distorted, and the speed fluctuation occurs. It is possible to stabilize the transportability of thin paper originals that are difficult to perform.
In the invention according to claim 5, in the invention according to claim 1 or 2, the restricting means is arranged on the document guide plate in a state of being divided in the width direction. The shape of the guide plate is simplified compared to a configuration in which a convex portion is formed by bending, and the restricting means can be arranged while avoiding interference with the parts constituting the conveying means.
Further, in the invention described in claim 6, in the invention described in claim 5, since the restricting means is a plurality of rib-shaped convex portions provided on the document guide, the effect of the invention described in claim 5 is effectively realized. In addition, manufacturing can be simplified by integrally molding the document guide plate and the plurality of rib-shaped convex portions.

The present invention relates to an image reading apparatus that conveys an original to a fixed reading unit and reads an image on the original while conveying the original at a predetermined speed. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the components, types, combinations, shapes, relative positions, and the like described in this embodiment are not merely intended to limit the scope of this description unless otherwise specified, but are merely illustrative examples. .
FIG. 1 is a cross-sectional view of an image reading apparatus according to an embodiment of the present invention, FIGS. 2 and 3 are control block diagrams, and FIGS. 4 to 9 are operation flow diagrams. Hereinafter, a processing operation for a document bundle having the same size will be described with reference to these drawings.
As shown in FIG. 1, an image reading apparatus according to this embodiment includes a document setting unit 1 for setting a document bundle to be read, and a separation feeding unit for separating and feeding documents one by one from the set document bundle. 2. The registration unit 3 that abuts and aligns the fed document and pulls out and transports the aligned document. Turns the conveyed document and conveys the document surface toward the reading side (downward in FIG. 1). The turn unit 4, a first reading / conveying unit 5 that performs conveyance for reading the front surface image of the document from below the contact glass, and a second reading / conveying unit 6 that performs conveyance for reading the back side image of the document after surface reading. A paper discharge unit 7 that feeds a document whose front and back have been read out of the machine, a reversing unit 8 that performs reversal for re-reading, and a stack that holds a document after reading is completed. Tsu has a such as wards 9. Further, as shown in FIG. 2, a calling motor 101 that drives the conveyance operation, a paper feeding motor 102, a reading motor 103, a reversing motor 104, a controller 100 that controls a series of operations, and the like are provided.
With such a configuration, when reading an image on the original, the original bundle 13 is set on the original setting table 10 with the leading end abutting the broken line position of the original stopper 25 (Yes in S1 in FIG. 4). Further, the width direction of the original bundle 13 is positioned by the side guide 11 in the direction orthogonal to the conveyance direction.

In this state, the document set detection filler 21 is displaced from the broken line position to the solid line position. As a result, the shield of the document set detection sensor 28 is released, and when the document set is detected, the I / F unit 107 (FIG. 2), a document set signal is transmitted to the main body control unit 111. Further, the document length is detected by the document length detection sensor 12 or the document length detection sensor 14 (a reflective sensor or an actuator type sensor that can detect even one document) provided on the document table surface. An outline of the direction length is determined (at least a sensor arrangement that can determine whether the document size is vertical or horizontal is necessary).
Thereafter, the CW (forward rotation) drive of the calling motor 101 is performed by a document feed signal (a signal input from an operation unit (not shown) and instructed from the main body control unit 111 to the controller 100 via the I / F unit 207). In the embodiment, a stepping motor is used, but can be realized by a solenoid) (S2), the document stopper 25 is retracted to the solid line position (yes in S3), and the document leading edge is opened. Subsequently, the calling motor 101 is driven in reverse rotation (S4), the pickup roller 20 is moved from the broken line position to the upper surface of the document indicated by the solid line position (yes in S5), and is pressed by a predetermined force. End (S6). In FIG. 1, a home position sensor 19 is a sensor for detecting the states of the pickup roller 20 and the document stopper 25.

Further, when the pick-up roller 20 is pressed, if the number of originals is small, the drop height of the pick-up roller 20 is reduced due to the large drop height and the small cushioning action of the original between the original set table 10 and the pick-up roller 20. There is a problem that the sound is loud. 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. .
Thereafter, after a predetermined time, the sheet feeding motor 102 that drives the separation feeding unit 2 and the registration unit 3 rotates in the CCW (forward rotation) direction (S7), and the pickup roller 20 rotates in the clockwise direction, and the document bundle 13 top sheets are fed in the direction of the separation feeding unit 2. At this time, the paper feeding belt 23 is stretched around the belt pulleys 22 and 24 with a predetermined tension, and is in pressure contact with the separation roller 26 provided oppositely. The separation roller 26 is friction-driven through a torque limiter (not shown) having a predetermined magnitude of torque. When the separation roller 26 is directly engaged with the paper feed belt 23 or is engaged via a single original. When the paper feeding belt 23 is rotated counterclockwise, if two or more documents are entered between the paper feeding belt 23 and the separation roller 26, the follower force is larger than the torque limiter torque. The separation roller 26 rotates in the clockwise direction, which is the original driving direction, and pushes back an excess original, thereby preventing double feeding.

The document separated into one sheet by the action of the sheet feeding belt 23 and the separation roller 26 is further fed by the sheet feeding belt 23, and the leading edge is detected by the abutting sensor 29 in the process of proceeding through the sheet feeding path 27 (S8). yes), simultaneously, the calling motor 101 is rotated in the CCW direction (S9 in FIG. 5), the pickup roller 20 is retracted from the upper surface of the document (yes in S10), and the document is sent only by the conveying force of the paper feed belt 23, It strikes against the stopped pull-out roller 31. Then, the sheet is fed by a predetermined distance from the position detected by the abutting sensor 29. As a result, the paper feeding motor 102 is reversed while being pressed against the pull-out roller 31 with a predetermined amount of warpage. The driving of the paper feed belt 23 is stopped. At this time, the leading edge of the document enters the nip between the pair of upper and lower rollers of the pull-out roller 31 and the pull-out driven roller 30, and the leading edge is aligned (skew correction).
Thereafter, the pull-out roller 31 is driven by the reverse rotation of the paper feed motor 102 to convey the document in the direction of the turn part 4 (S11). Here, when the first sheet of the original bundle is fed to the registration stop position, the conveyance speed of the pull-out roller 31 is set higher than the reading speed. Note that the reading conveyance roller 43 is driven by the reading motor 103 and has the same speed as the pull-out roller 31.
The width of the document leading edge past the position of the pull-out roller 31 is detected by the size detection sensor 32 in a direction perpendicular to the conveyance direction (S12). 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 (yes in S12), the document size signal is sent to the main body control unit 111. Is transmitted from the controller 100 via the I / F unit 107 (S13). In the mixed loading mode in which originals of different sizes are mixed (yes in S14), original length information transmission described later is executed (S15).
Thereafter, the document is sent to the nip between the reading conveyance roller 43 and the pressure roller 35, and the pulse count for time measurement is started (S17) from the detection of the leading edge of the document by the registration sensor 40 (S16). Reaches the predetermined number of pulses (yes in S18), the paper feed motor 102 and the reading motor 103 are stopped at that position (S19), and a registration stop signal is transmitted to the main body control unit 111 (S20). Waits for input of a reading start signal (a signal for synchronizing with transfer paper conveyance or a signal transmitted when preparation for accumulation in the image memory is completed).

In step S11, the second and subsequent sheets are used in the form of first-out of the next document. 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 next original is read at the same speed as the reading conveyance roller 43. 43 and the pressure roller 35 must be sent to the nip. Therefore, as shown in FIG. 6, when the trailing edge of the document being read (yes in S21) passes through the abutting sensor 29 (yes in S22), the pulse count for controlling the paper interval is started and reading is in progress. The forward feeding of the next original is started by starting the forward rotation of the calling motor 101 while monitoring the progress of the trailing edge of the original (S23).
Then, the pickup roller 20 is brought into pressure contact with the upper surface of the next original (set to the calling position) (yes in S24), the calling motor is stopped (S25), and then the drive unit (paper feeding motor) 102 is driven forward ( S26), the abutting sensor 29 is turned ON (yes in S27), and further, the abutting amount count is started, the calling motor CCW is rotated, whether the pickup is at the retracted position, the calling motor is stopped when it is at the retracted position, Are sequentially executed (S27a to 27d), a predetermined number of pulses are counted (yes in S27e), and conveyed until stopped against the stopped pull-out roller 31 (S28 in FIG. 7). Here, the position of the trailing edge of the document being read is obtained from the sheet pulse count value (yes in S29), and when the paper advances from the position of the pull-out roller 31 by a predetermined sheet interval, the feed motor 102 is set to the first-out speed ( S30), reverse driving is performed (S31). Thus, the pull-out roller 31 is driven at a high speed as in the case of the first sheet, and is fed to the tip 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 tip detection sensor 34 (S32). (S33). By performing such an operation between successive documents, it is possible to recover the time stopped by the document abutting operation and maintain a predetermined document interval.

Next, a document reading operation executed by inputting a reading start signal will be described with reference to FIG.
At that time, first, the driving speed of the reading motor 103 is determined based on information transmitted from the main body control unit 111 to the controller 100 in accordance with a reading magnification input from a main body operation unit (not shown) (S42). Then, the document stopped at the registration position is started to rotate forward by the reading motor 103, and the leading edge count is started in order to measure the timing at which the leading edge of the document reaches the reading position by pulse counting (S43). In this way, the rotating reading conveyance roller 43 and the pressure roller 41 are sent to the first reading conveyance unit 5, and the reading glass 54 constituting the first reading conveyance unit 5 has a predetermined interval on the upper surface thereof. A document is conveyed between the arranged white background plate 51.
During this conveyance, an image is read by the reading system, is electrically converted via the CCD, and is stored in the memory. With respect to the first reading / conveying unit 5, a means for taking the conveyance gap as narrow as possible and reducing the degree of freedom of the document as much as possible is taken. For example, a method of extending 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 is pressed on the reading glass 54 with a gap of about 0.5 mm ± 0.2 mm and with a predetermined elasticity, and errors in the reading depth direction are also suppressed.
Further, the surface of the reading glass 54 is treated with a surface active agent (silicon-based activator) so that the ink does not easily adhere or adhere to the surface. Further, the above-described flexible guide is extended to the vicinity of the reading point, and at the reading point position, the original surface (portion other than the front end of the original) is not in contact with the reading glass 54 as much as possible. The structure is such that wiping (the action of scraping off foreign matter on the glass surface at the tip) can be performed.
As described above, the controller 100 performs pulse counting to measure the timing at which the leading edge of the document reaches the reading position. When the count value reaches a predetermined value (yes in S44), the surface image in the sub-scanning direction. A surface DF gate signal indicating an effective reading area is transmitted to the main body control unit 111 (S45).
Thereafter, the document advances while the image is read, and is sent 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 commonly driven by the reading conveyance roller 43, the feeding speed and the drawing speed are the same, which has the effect of reducing the occurrence of a delivery shock.

A 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 above, and below the image sensor 61. The contact image sensor 61 passes between the pressing members 62 arranged on the reading surface with a predetermined pressure and a predetermined interval. In the double-sided reading mode (Yes in S46), the timing at which the leading edge of the document reaches the position of the contact image sensor 61 is measured by the pulse count from the leading edge detection by the registration sensor 40, and when the count value reaches a predetermined value ( In step S47, the back side DF gate ON signal indicating the effective reading area of the back side image is transmitted to the contact image sensor 61 (S48). As a result, the image on the back side of the document is read based on the signal, and is electrically converted in the same manner as the front side. The converted image data is temporarily stored in the frame memory 205 shown in FIG. Transferred to the unit 111. The pressing member 62 also has a function as a shading reference and a function as a white background plate. The pressing member 62 may be constituted by a plate-shaped guide member as shown in FIG. 1 or may be constituted by a rotating body.
As for the timing of reading the front and back documents, the discharge sensor 70 detects the leading edge of the document (yes in S49), the registration sensor 40 detects the trailing edge of the document (yes in S50), and the pulse count from that point (rear) End count) (yes in S51 and S52). Subsequently, the original is discharged to a paper discharge stacker 90 of the stack unit 9 by a paper discharge roller pair constituted by a paper discharge driving roller 71 and a paper discharge pressure roller 72. The discharge stacker 90 is configured to be high on the downstream side, contributing to prevention of jumping out of discharged originals and improvement of stacking original alignment accuracy. During continuous reading of multiple originals, the drive of the reading motor is stopped by the registration stop operation by the next original advance than the original discharge completion timing, so the discharge operation of the original that has been read is driven by the reading motor by starting the reading of the next original When the rear end of the document leaves the paper discharge sensor 70 due to the restart (S53), a paper discharge completion signal is transmitted to the main body control unit 111 to complete the process (S54).
When a small-size document is stacked, the reversing switching claw 80 of the reversing unit 8 is switched to the state indicated by the broken line by the driving unit 105 to transport the document to the reversing path 85, and the reversing discharge driving roller 81 and the reversing discharge follower The paper is discharged onto a small-size dedicated stacker 91 configured as a part on the document stacker 90 by a pair of reverse conveying rollers formed of rollers 82. Thus, the visibility after discharging a small-size document is improved.
In the above description, the document setting table 10 is configured so as to be able to rotate upward with the rotation fulcrum 15 as a center, thereby improving the stacking document take-out performance.
When the document is discharged, the operation of the reverse switching claw 80 is synchronized with the trailing edge of the discharged document, and immediately after the document is discharged, the reverse switching claw 80 is rotated in the direction of the broken line by the drive source 105 to The trailing edge is hit to prevent the remaining trailing edge of the discharged document.

The above is an overview of the processing of single-sided and double-sided originals for the same size original bundle. Next, processing of single-sided and double-sided originals when sizes are mixed will be described.
In this case, since the document length is mixed, the document length detection sensors 12 and 14 on the document set table 10 cannot determine the document length. The size is determined only when the trailing edge of the document leaves the sheet bundle and becomes completely independent. Therefore, when it is desired to determine the document size before reading, the length from the first document trailing edge detection position after separation to the registration sensor position before reading is set to a length of ½ or more of the maximum document length. There is a need. However, if this is satisfied, the document setting position needs to be greatly separated from the reading position, and the portion including the document setting table and the conveyance path becomes large, resulting in a disadvantage that the entire apparatus becomes wide. Therefore, in order to make the apparatus small, it is necessary to devise an original length detection at the time of mixed loading.
As a countermeasure for this, in this embodiment, when the document size cannot be determined before the start of reading at the time of mixed size loading, the reading is not performed at the first conveyance, and the paper is passed only for the size reading, and the reversing unit 8 is set. The method of reading the front surface and the back surface at the same time when passing through the second reading. In this case, the transporting operation up to the first registration stop is the same as when a document of the same size is bundled, but the operation after receiving the reading start signal transmitted from the main body control unit 111, particularly after the processing by the discharging unit 7, is different. Hereinafter, different parts will be described with reference to FIG.

In the mixed size mode (Yes in S41 in FIG. 8), when the paper passes through the reading unit and is ejected, it is reversed before the leading edge of the document comes out from the pair of ejection rollers 71 and 72. The switching claw 80 is moved in the direction of the broken line by the reverse switching solenoid 105 (S61), and feeds the document to the reverse path side (upper side). Thus, the original is fed by the reverse paper discharge roller pair 81, 82 until the rear end of the original passes the paper discharge roller pair 71, 72. In this operation, after the paper discharge sensor 70 is turned on (yes in S62), when it is turned off again (yes in S63), pulse counting is started (S64), and the count value is a predetermined value. It continues until it becomes (yes in S65).
After the document is stopped, the reverse switching solenoid 105 is turned off to move the reverse switching claw 80 in the solid line direction (S66), and the rear end of the document is directed to the nip direction of the pair of reverse rollers 71 and 83. Then, the reverse discharge driving roller 81 is rotated in the counterclockwise direction by the reverse rotation of the reverse motor 104 (S66), and the reverse roller pair 71 composed of the stopped discharge driving roller 71 and the reverse upper roller 83, The end of the document (the rear end when viewed from the initial state) is abutted against the nip portion 83 to perform leading edge skew alignment, and the reversing roller pair 71 and 83 starts conveying the document by the forward rotation of the reading motor 103. (S67) The document is again sent to the first reading / conveying unit 5 and the second reading / conveying unit 6 through the turn unit 4, and the front and back sides are read. That is, the leading edge count is started in order to measure the timing at which the leading edge of the document reaches the reading position by the pulse count following the normal rotation driving of the reading motor 103 (S68), and the reading constituting the first reading conveyance unit 5 is started. A document is conveyed between the glass 54 and the white background plate 51. During this conveyance, an image is read by the reading system, is electrically converted via the CCD, and is stored in the memory.
When the count value reaches a predetermined value and the leading edge of the document reaches the reading position (Yes in S69), a back surface DF gate signal is transmitted (S70). 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.
In the duplex mode (yes in S71), when the count value reaches a predetermined value and the leading edge of the document reaches the reading position on the opposite side (yes in S72), the controller 100 sends a front gate signal ON signal to the main body control unit 111. (S73). Based on this signal, the main body control unit 111 performs a page order switching process.
The reading operation is now completed, but if it is discharged as it is, the page order will be out of order.

Next, an embodiment of the present invention will be described. In the image reading apparatus of this embodiment, the originals whose rear ends are removed from the pressure roller 41 which is the original conveying means that is upstream from the original reading position and closest to the original reading position are mutually connected from both sides of the original conveying path. A restricting means for restricting the facing direction is provided between the intermediate conveyance pressure roller 53 which is an original conveying means downstream of the original reading position and closest to the original reading position and the original reading position.
FIG. 10 is an explanatory diagram of the main part of the image reading apparatus according to the first embodiment of the present invention. When the original is sandwiched between the pressure roller 41 and the intermediate conveyance pressure roller 53 that are the original conveying means before and after the original reading position (see FIG. 10A), the original of the original in the image reading apparatus of this embodiment is The behavior is almost the same as in the case of the prior art shown in FIG. That is, in order to prevent the deflection of the document in the reading unit, the linear speed in the intermediate conveyance pressure roller 53 is set to be higher than that of the pressure roller 41. Therefore, the document at the reading position is stretched. Yes, the manuscript always tries to take the shortest path.
Here, let us consider a point in time when the trailing edge of the original passes through the pressure roller 41 as shown in FIG. The original that has passed through the pressure roller 41 having a relatively low linear velocity tries to move to the outer peripheral side in accordance with the characteristics of the paper (paper waist characteristics), and the linear velocity tends to increase. The document is regulated by the first convex portion 56a at the reading exit portion, which is a means, and the speed fluctuation is suppressed.

In this embodiment, further, a second convex portion 56b is provided as the restricting means on the opposite side of the first convex portion 56a with respect to the document conveyance path gap downstream thereof, and restriction is imposed in the facing direction. Restrictions are applied in opposite directions from both sides of the gap of the document conveyance path. In this case, as is apparent from FIG. 10B, the original contact portion at the reading position, the first and second convex portions 56a and 56b, and the original contact portion in the intermediate conveyance pressure roller 53 are substantially in a straight line (on the same plane). ), The leading edge of the document is smoothly conveyed without being caught by the convex portions 56a and 56b, and therefore, the document can be conveyed without being distorted. Further, it is possible to ensure the stability of transporting thin paper documents.
Further, since the original is restricted from both sides of the gap of the original conveying path by the first and second convex portions 56a and 56b, a force is applied in the direction in which the original is pressed against the white background plate 51 due to the waist characteristics of the paper. As shown in FIGS. 10B and 10C, even when a disturbance such as the posture of the rear end of the document changes upstream of the reading position, the amount of change in the document posture in the reading unit is reduced and the image is less blurred. Can be read.
In the example shown in FIG. 10, FIG. 16, and FIG. 17, the reading and conveying roller 43 is divided into two parts 43a and 43b and provided at the inlet and the outlet of the reading unit. The case where there is one roller at the entrance and the exit will be described.
FIG. 11 shows such an example, which corresponds to the prior art shown in FIG. As shown in FIG. 11A, when both ends of the original are sandwiched upstream and downstream of the reading position, since the reading conveyance roller 43 has the same roller diameter, the original is at a constant speed on both the entrance side and the exit side. It is carried by and there is no deflection or pulling. Therefore, the shape when the leading edge of the original first enters the reading portion is always maintained. Basically, a path close to the outer periphery of the document transport path is taken due to the low back characteristic of the paper.
Thereafter, even if the trailing edge of the document passes through the pressure roller 41 on the entrance side, the document posture does not change greatly. However, since there is no restriction on the trailing edge of the document, the orientation of the document in the vicinity of the reading unit becomes unstable, and a speed fluctuation is likely to occur (see FIG. 11B). In the case of the prior art shown in FIG. 17, the speed increases when the trailing edge of the document passes through the pressure roller 41. However, in the case of the example shown in FIG. It can be faster.

FIG. 12 is an explanatory diagram of the main part of the image reading apparatus showing the second embodiment of the present invention. As illustrated, pickup guides 52a and 52b, which are document guides provided downstream of the reading unit, are respectively provided with a first convex portion 56a and a second convex portion 56b, and the original is restricted by these convex portions. Is receiving. Speed fluctuations are more likely to occur in thick originals. However, the thicker the paper, the more the paper has a waist characteristic in the direction in which it is pressed against the white background plate 51 in FIG.
As described above, when there is a single reading drive roller 43, there is no difference in linear velocity between the entrance and the exit, and therefore, regulation in the direction opposite to that in FIG.
FIG. 13 shows a third embodiment of the present invention. As shown in the figure, the first convex portion 56a protrudes from the upper guide, and the second convex portion 56b protrudes from the lower guide. On the contrary to FIG. 12, a downward force is applied to the document at the reading portion. The settings are as follows. Here, the original takes a position close to the outer periphery in the conveyance path by the waist of the paper as in FIGS. 11 and 12, but a downward (outer peripheral) force acts on the exit side, so the original always follows the outer periphery. It becomes a shape and it becomes possible to obtain a stable conveyance.
14 to 16 are explanatory views showing a fourth embodiment of the present invention. In this embodiment, the convex portions 56a and 56b are not continuous in the width direction, but are formed in a shape divided in the width direction as shown in FIG. For example, a rib-like convex portion 56 may be provided on a substantially flat surface, such as the pickup guides 52a and 52b shown in FIG. 15 and the pickup guide 52a shown in FIG. In such a configuration, the conveyance resistance when the document passes is reduced, and the shape is simple and advantageous in terms of molding compared to a configuration in which the document guide plate itself is bent to form a convex portion.

1 is a cross-sectional view of an image reading apparatus showing an embodiment of the present invention. 1 is a control block diagram of an image reading apparatus according to an embodiment of the present invention. The other control block diagram of the image reading apparatus which shows one Embodiment of this invention. FIG. 3 is an operation flowchart of the image reading apparatus according to the embodiment of the present invention. The other operation | movement flowchart which shows one Embodiment of this invention, and an image reading apparatus. The other operation | movement flowchart which shows one Embodiment of this invention, and an image reading apparatus. The other operation | movement flowchart which shows one Embodiment of this invention, and an image reading apparatus. The other operation | movement flowchart which shows one Embodiment of this invention, and an image reading apparatus. The other operation | movement flowchart which shows one Embodiment of this invention, and an image reading apparatus. 1 is an explanatory diagram of a main part of an image reading apparatus according to a first embodiment of the present invention. Explanatory drawing of the principal part of an image reading apparatus based on 2nd Example of this invention. Explanatory drawing of the image reading apparatus principal part which shows the 2nd Example of this invention. Explanatory drawing of the image reading apparatus principal part which shows the 3rd Example of this invention. Explanatory drawing of the image reading apparatus principal part which shows the 4th Example of this invention. The other explanatory view of the principal part of the image reading apparatus showing the fourth embodiment of the present invention. The other explanatory view of the principal part of the image reading device showing the fourth embodiment of the present invention. Explanatory drawing of the principal part of an image reading apparatus which shows an example of a prior art. Explanatory drawing of the image reading apparatus principal part which shows the other example of a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Document setting part, 2 Separation feeding part, 3 Registration part, 4 Turn part, 5 1st reading conveyance part, 6 2nd reading conveyance part, 7 Paper discharge part, 8 Inversion part, 9 Stack part, 40 Registration sensor, 41 Pressure roller, 42 Reading entrance guide, 43 Reading conveyance roller, 51 White background plate, 52 Pickup guide, 53 Intermediate conveyance pressure roller, 54 Reading glass, 56 Convex, 100 Controller

Claims (6)

  In an image reading apparatus comprising a fixed image reading means and a plurality of document conveying means for conveying an original, and reading the image on the original by the image reading means while conveying the original at a predetermined speed by the original conveying means. A regulating means for regulating a document upstream of the document reading position and the document reading position at the document reading position from the nearest document conveying means in a direction facing each other from both sides of the gap of the document conveying path; An image reading apparatus provided between the original reading position and an original conveying means closest to the original reading position downstream of the original reading position.   2. The image reading apparatus according to claim 1, wherein the restricting means is a convex portion projecting from the document conveyance path.   3. The image reading apparatus according to claim 2, wherein when the document transport path is curved, the upstream convex portion of the pair of two convex portions is on the inner peripheral side, and the downstream convex portion is on the outer peripheral side. An image reading apparatus provided.   3. The image reading apparatus according to claim 1, wherein the restriction unit includes a document contact portion that is closest to the document reading position, a document passage point at the position of the regulation unit, a downstream of the document reading position, and An image reading apparatus having a configuration in which an original contact portion at a position of an original conveying means closest to an original reading position is positioned substantially in a straight line.   3. The image reading apparatus according to claim 1, wherein the restricting unit is arranged in a state of being divided in the width direction.   6. The image reading apparatus according to claim 5, wherein the regulating means is a plurality of rib-shaped convex portions provided on the document guide.

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