JP3698890B2 - Image reading device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image reading apparatus such as a scanner, a copying machine, or a facsimile.
[0002]
[Prior art]
In the conventional image reading apparatus, as shown in FIG. 2, the vicinity of the reading position is narrowed in order to reduce the entire apparatus, and a conveyance roller 8 for conveying the separated original to the reading position and a post-reading The first conveyance path R ₁ between the original conveyance roller 11 for conveying the document to the paper discharge unit is configured to have a curved portion. On the first transport path R ₁ , an ADF side guide 100 a, a reading guide member 102, a main body side guide 100 b, and the like are arranged at appropriate intervals so as not to cause a document transport load. The document feed speed is usually set so that the feed speed by the intermediate transport roller 11 downstream of the reading position is slightly higher than the feed speed of the transport roller 8 upstream of the reading position. ing. This is to prevent the original from being bent at the reading position because the document feed speed at the reading position changes and accurate reading cannot be performed when the original is bent at the reading position. Although it is conceivable that the same feed speed is set upstream and downstream of the reading position, the downstream side may be slow due to variations in the parts of the conveyance roller diameter and the like, and usually the downstream side is set to be fast. In such an apparatus, while the document is held between the transport roller 8 and the intermediate transport roller 11, the document 1 is stretched as shown by a one-dot chain line in the figure, and the image of the document is read at the reading position. There is no expansion or contraction in information. Thereafter, when the trailing edge of the document passes the conveyance roller 8, the document conveyance state changes from a state in which the document 1 is stretched to a state in which the document is bent as indicated by a broken line in the drawing. For this reason, at the reading position on the contact glass 101, the document feed speed is changed due to the bending of the document, so that the read image information partially expands and contracts.
[0003]
In addition, there are JP-A-7-64359 and JP-A-7-17527 as related devices of this type.
[0004]
[Problems to be solved by the invention]
In the conventional technique, when the trailing edge of the document passes the conveying means (conveying roller 8) upstream from the reading position, the document conveying state changes from a stretched state to a bent state. There is a problem that a change occurs in speed, and as a result, partial expansion and contraction occurs in the read image information.
[0005]
An object of the present invention is to improve such a problem, to stabilize the document conveyance state before and after the reading position, and to suppress a change in the document feeding speed at the reading position, which is accurate and has high reading accuracy. An object of the present invention is to provide an image reading apparatus.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides an upstream transport unit that is disposed upstream of a document reading position and sandwiches and transports the document, and a downstream side that is disposed downstream of the scanning position and sandwiches and transports the document. Arranged between the conveying means, the reading position and the downstream conveying means, and partly protrudes on the original conveying path, and its leading end is sandwiched between the upstream conveying means and the downstream conveying means. Maintaining means for maintaining the document conveyance state provided at a position in contact with the document surface in a state, and the conveyance path on which the upstream conveyance means, the maintenance means, and the downstream conveyance means are arranged is curved. It is formed to have a portion.
[0007]
Further, the maintaining means has a convex portion formed higher than the document conveying surface downstream of the maintaining means, and the original after the document trailing edge has passed through the upstream conveying means at the convex portion. It is characterized in that it is configured to maintain the conveyance state.
Further, the maintaining means is a guide roller disposed so as to come into contact with the transported document at a position higher than the document transport surface downstream of the maintaining means, and the back end of the document is located on the upstream transport means in the guide roller. It is characterized in that it is configured to maintain the state of conveyance of the original document after passing through.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating an image reading apparatus according to a first embodiment of the present invention, and an automatic document feeder (ADF) 200 is mounted on an apparatus main body 100. The first document transport path R ₁ of the automatic document transport apparatus 200 has a curved portion, and on the first transport path R ₁ , upstream of the reading position when the image surface of the document 1 is read by the reading unit 10. A pair of conveying rollers (conveying roller 8 and conveying driven roller 8a = upstream conveying unit) for nipping and conveying the document 1 to the reading position is disposed. A reading guide member 102 is disposed in the vicinity of the reading position, and an intermediate conveying roller pair (intermediate conveying roller 11 and intermediate conveying driven roller 11a = downstream) for nipping and conveying the document 1 is disposed downstream of the reading guide member 102. Side conveying means) is arranged.
[0009]
Further, in the middle of the reading guide member 102 in the vicinity of the reading position and the intermediate conveying roller pair 11, 11a, a main body side guide 100c (= maintained ) that partially protrudes on the first conveying path R1 and maintains the conveying state of the document 1. Means) are arranged. That is, as shown in FIG. 3, the main body side guide 100c has a leading end portion (= convex portion) formed higher than the document conveyance surface (guide surface of the ADF side guide 100a) downstream from the main body side guide 100c. Is sandwiched between the pair of conveyance rollers 8 and 8a and the pair of intermediate conveyance rollers 11 and 11a so as to be in contact with the tangent line between the reading guide member 102 facing the contact glass 101 and the pair of intermediate conveyance rollers 11 and 11a. It is provided between the reading guide member 102 disposed in the vicinity of the reading position and the intermediate conveyance roller pair 11 and 11a so as to be in a position in contact with the stretched document surface. With such a configuration, while the pair of conveying rollers 8 and 8a and the intermediate conveying rollers 11 and 11a hold the document 1, the document 1 is stretched upstream and downstream of the reading position as indicated by a one-dot chain line. It is in. Further, when the trailing edge of the document passes through the pair of conveying rollers 8 and 8a, the portion upstream of the reading position of the document 1 changes to a bent state as indicated by a dotted line. On the other hand, the portion downstream of the reading position of the document 1 is lifted by the front end portion of the main body side guide 100c, so that the transported state (the state in which the document trailing edge is stretched without being bent) before the trailing end of the document passes through the pair of transport rollers 8 and 8a. ).
[0010]
Note that when the main body side guide 100c is formed, the tip of the main body side guide 100c may be simply raised so as to be in contact with the tangent line, but the curvature of the conveyance path itself may be reduced, making it unsuitable for conveying thick paper documents. Therefore, more preferably, the intermediate conveyance roller pair 11 and 11a are arranged lower so that the guide member at the lower part of the conveyance path (the front end portion of the main body side guide 100c) is in contact with the document surface. Further, in order to reduce the document transport load due to the main body side guide 100c, the height of the leading edge may be set lower by about 0.5 to 1 mm than the height at which the leading edge contacts the document surface.
[0011]
Furthermore, a guide roller 103 as shown in FIG. 4 may be provided instead of the main body side guide 100c. The guide roller 103 is disposed so as to be in contact with the transported document at a position higher than the document transport surface on the downstream side (guide surface of the ADF side guide 100a), that is, so as to be in contact with the tangent line. It is possible to correct the conveyance state after passing through the pair of rollers 8 and 8a and reduce the conveyance load of the document 1 as compared with the above embodiment.
[0012]
In the present embodiment, the paper feed / separation unit for sequentially transporting the originals 1 stacked and placed on the original table 2 one by one from the topmost one supports the original paper supply side on the original table 2. The bottom plate 4 is moved up to a position in contact with the calling roller 5, is rotated in the paper feeding direction, and is fed in a direction opposite to the paper feeding direction. The separating member 7 separates only the topmost sheet of the fed document 1. The paper feed member 6 and the separation member 7 are driven by a drive motor (not shown) (for example, a stepping motor).
[0013]
The transport unit for transporting the document 1 transported from the paper feed / separation unit to the reading position on the contact glass 101 includes transport roller pairs 8 and 8a, intermediate transport rollers 11 and 11a, and the like. These rollers are driven by a drive motor (not shown) (for example, a stepping motor). Since the conveyance speed of the intermediate conveyance roller 11 is set slightly faster (for example, about 1%) than the conveyance speed of the conveyance roller 8, the original 1 that has been nipped and conveyed by the conveyance roller pair 8, 8a is After moving on the contact glass 101 and scooped by the main body side guide 100c, the original 1 is stretched while the original 1 is sandwiched between the conveying roller pairs 8, 8a and the intermediate conveying rollers 11, 11a. The contact glass 101 is not contacted and the contact surface with the reading guide member 102 is kept small. Further, even after the document trailing edge passes through the conveying roller pair 8 and 8a, the document 1 is kept stretched by the main body side guide 100c as described above and passes the reading position.
[0014]
The reading unit 10 that reads the image surface of the document 1 includes an exposure lamp, a first mirror, and an optical system such as a lens (not shown), and is provided in the apparatus main body 100 below the contact glass 101. . When reading an image, the exposure lamp and the first mirror are moved in the left-right direction in FIG. 1 below the contact glass 101 or stopped below the reading position, and the exposure lamp irradiates the image surface with light. After that, the reflected light is imaged on a photosensitive drum (not shown) via the first mirror and the optical system, and toner or the like is attached to the electrostatic latent image formed on the photosensitive drum to form a recording paper. The image is transferred, or the reflected light is imaged on an image sensor such as a CCD via a first mirror and an optical system, and the optical signal is converted into an electric signal by the image sensor, and various image forming means are used. Transfer the image onto the recording paper.
[0015]
In addition, a paper discharge unit for discharging the document 1 after reading to the paper discharge tray 15 or the intermediate tray 17 is a paper discharge sensor (for example, a paper discharge sensor for detecting the document 1 conveyed through the intermediate conveyance roller pairs 11 and 11a). Optical reflection type sensor) 13, switching claw 14 for changing the conveyance direction at the time of paper discharge or reversal, and a reverse sensor (for example, an optical reflection type sensor) for obtaining detection information as a trigger for timing control of changing the conveyance direction. 18 and a discharge roller 12 and a reverse roller 16 driven by a drive motor (not shown).
[0016]
The ADF 200 of this embodiment is connected to the apparatus main body 100 by a connecting member such as a hinge (not shown) and is configured to be openable and closable in the direction of arrow C.
Next, the paper feeding / separating operation in this embodiment will be described. In the present embodiment, a document 1 stacked on the document table 2 with the first image surface facing upward is sent to the ADF 200 side when a start button (not shown) in the operation unit of the apparatus main body 100 is pressed. Thus, the sheets are fed one by one from the top. The operation procedure is described below. When the document 1 is stacked and placed on the document table 2, the leading end of the document is positioned by abutting against the paper feed guide plate 3. When the original 1 is set in this manner, the bottom plate 4 is raised in the direction of arrow A by a solenoid (not shown) by the start signal, and pushes up the original 1 to a position where it contacts the calling roller 5. The document 1 pressed by the calling roller 5 is conveyed to a separation unit composed of a sheet feeding member 6 and a separating member 7 by the calling roller 5 rotating in the sheet feeding direction, and is separated one by one from the top. The bottom plate 4 that has been lifted as described above is lowered after a certain time from the start of feeding or after the registration sensor 9 detects the leading edge of the document. This is because when the bottom plate 4 is lowered, the pressure between the bottom plate 4 applied to the document 1 and the calling roller 5 is released, and the second image surface of the document 1 being conveyed is rubbed against the first image surface of the next document. This is to shorten the time. As described above, when the bottom plate 4 is lowered after a certain time from the start of paper feeding, it is desirable to set the time as short as possible in order to reduce contamination due to rubbing. When the document 1 is only a single-sided image (first image surface), there is no second image surface, so there is no need to lower the bottom plate 4. Whether the single-sided reading or the double-sided reading is set in advance by the user arbitrarily selecting the single-sided / double-sided mode on the operation unit.
[0017]
The documents 1 separated one by one in this way are transported to the first transport path R ₁ where the transport roller pairs 8 and 8a are arranged. The registration sensor 9 disposed in the vicinity of the pair of conveying rollers 8 and 8a detects the leading edge of the document, and matches the timing of passing the leading edge of the document to the reading unit 10 and the start of image reading. If the registration sensor 9 does not detect the leading edge of the document after a certain time has elapsed after the document 1 is separated and conveyed, it is determined that a jam has occurred.
[0018]
Further, the reading operation is started according to the setting of the single-sided / double-sided mode in the operation unit. When only the first image surface is read in the single-side mode, the document 1 is read by the reading unit 10 as described above, and then the intermediate conveyance roller pairs 11 and 11a and the paper discharge roller are read out. 12 and the second delivery path R ₂ where the paper ejection lower driven roller 12 a is disposed, and is ejected to the paper ejection tray 15. At this time, if the leading edge of the document is not detected by the paper discharge sensor 13 even after a certain time elapses, or the trailing edge of the document is not detected by the paper discharge sensor 13 even after a certain time has elapsed after the leading edge of the document is detected. In the case, it is determined as a jam. The switching claw 14 is at the B position (home position) and guides the document 1 held and conveyed by the paper discharge roller 12 and the paper discharge driven roller 12a to the paper discharge tray 15 side.
[0019]
On the other hand, when the first image surface and the second image surface are read in the duplex mode, the original 1 is read through the first conveyance surface R ₂ as described above, and then passes through the second conveyance path R ₂ . and is discharged to the intermediate tray 17 through the third conveyance path R ₃ to reversing driven roller 16a is disposed. At this time, the switching claw 14 is moved to the B position (home position) by a solenoid (not shown) at a predetermined timing after the leading edge of the document is detected by the paper discharge sensor 13 or the document 1 is detected by the registration sensor 9. The document 1 is lowered to the B ′ position from the position) and guided to the intermediate tray 17 by the sheet discharge roller 12 and the sheet discharge lower driven roller 12a. If the document 1 passing through the third transport path R ₃ is not detected by the reversal sensor 18 even after a predetermined time has elapsed, it is determined that a jam has occurred.
[0020]
The switching claw 14 lowered to the B ′ position is a predetermined time after the leading edge of the document has passed through the paper discharge sensor 13 (time until the trailing edge of the document passes through the paper discharge roller pairs 12 and 12a and reaches the switching claw 14). After the elapse of time, the solenoid is released to return to the B position (home position). After the switching claw 14 returns, the reverse roller 16 rotates in the reverse direction, and the leading edge of the original enters the nip portion of the paper discharge roller 12 and the paper discharge driven roller 12b. At this time, the discharge roller 12 stops driving, and skew (document skew) abutting correction is performed. After completion of the abutting correction, the document 1 is conveyed to the reading position through the fourth conveying path R ₄ and the first conveying path R _1, and the second image surface is read by the reading unit 10.
[0021]
After the second image plane is read in this way, the switching claw 14 moves to the B ′ position in order to arrange the page order of the document 1 (so that the first image plane is stacked downward). As a result, the document 1 after reading through the second transport path R ₂ passes through the third transport path R ₃ and is temporarily held on the intermediate tray 17 with the second image surface facing downward. Thereafter, the switching claw 14 returns to the B position (home position), and the document 1 once held on the intermediate tray 17 is transferred to the fourth transport path R ₄ , the first transport path R ₁ , and the second transport path R _2. , And the first image surface is discharged downward onto the paper discharge tray 15.
[0022]
Thereafter, the feeding operation of the next original by the calling roller 5 is started by the start signal from the operation unit. When the bottom plate 4 is raised by the start signal, the time taken for the bottom plate 4 to rise to a predetermined position. Therefore, the bottom plate 4 is raised beforehand in preparation for feeding the next original before receiving the start signal. In other words, when the current document is ejected, when the leading edge of the document passes through the fourth conveyance path R ₄ and the leading edge of the document is detected by the registration sensor 9, the bottom plate 4 is raised. The bottom plate 4 may be raised when the trailing edge of the original passes through the calling roller 5 until the start of feeding the next original. However, in order not to give vibration due to the rise, except when reading an image. It is set so that the bottom plate 5 rises at the time of.
[0023]
【The invention's effect】
As described above, according to the present invention, after the document trailing edge has passed through the upstream conveying unit (= conveying roller pair) between the reading position and the downstream conveying unit (= intermediate conveying roller pair). Maintenance means (= main body side guide) for maintaining the document conveying state is provided, and the maintaining means has a convex portion formed higher than the downstream document conveying surface, so that the leading edge of the document is from the reading position to the downstream conveying means. While the document is being transported, the transport state of the document is transported in substantially the same state as the document transport state stretched by the upstream and downstream transport means, and the change in the document feed speed at the reading position is suppressed, so that an accurate image can be obtained. Information can be read.
[0024]
Further, the maintaining means is constituted by a guide roller arranged so as to be in contact with the original at a position higher than the downstream original conveying surface, and in addition to the above-described effects, no conveying load is applied to the original. An effect is obtained.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an image reading apparatus according to a first embodiment of the present invention.
FIG. 2 is a diagram illustrating a configuration in the vicinity of a reading unit in a conventional image reading apparatus.
FIG. 3 is a diagram illustrating a configuration in the vicinity of a reading unit in the image reading apparatus according to the first embodiment of the present invention.
FIG. 4 is a diagram illustrating a configuration in the vicinity of a reading unit in an image reading apparatus according to a second embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Document 8 Conveyance roller 8a Conveyance driven roller 10 Reading part 11 Intermediate conveyance roller 11a Intermediate conveyance driven roller 102 Reading guide member 101 Contact glass 100a ADF side guide 100c Main body side guide

Claims (3)

An upstream conveying unit disposed upstream of the document reading position and sandwiching and conveying the document; a downstream conveying unit disposed downstream of the reading position and sandwiching and conveying the document; and the reading position and the downstream conveying unit And a part of which protrudes on the document conveyance path, and a tip portion thereof is provided at a position in contact with the document surface that is sandwiched between the upstream conveyance device and the downstream conveyance device. And maintaining means for maintaining the conveying state of the document, and the conveying path in which the upstream conveying means, the maintaining means, and the downstream conveying means are arranged is formed to have a curved portion. An image reading apparatus.   The maintaining means has a convex portion formed higher than the document conveying surface downstream of the maintaining means, and the document is conveyed after the document trailing edge has passed through the upstream conveying means at the convex portion. The image reading apparatus according to claim 1, wherein the image reading apparatus is configured to maintain a state.   The maintaining means is a guide roller disposed so as to come into contact with the transported document at a position higher than the document transport surface downstream of the maintaining means, and the trailing end of the document passes through the upstream transport means at the guide roller. The image reading apparatus according to claim 1, wherein the image reading apparatus is configured to maintain a conveyed state of the original after being processed.

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