JP2005045445A - Automatic document feeder - Google Patents

Abstract

An automatic apparatus capable of efficiently reading both front and back sides of a document without increasing the machine occupation area and suppressing adverse effects on images caused by flare and foreign matter in a second reading unit for reading the second side of the document. To provide a document feeder.
An automatic document feeder includes a first reading / conveying unit including a first reading / conveying unit that reads a surface image of a document from below the contact glass, and a second reading unit that reads a back side image of the document after reading the front side. F etc. are provided. The second reading unit 25 is disposed below the document setting unit A, and can read both sides of the document without increasing the machine occupation area. The case that houses the components of the second reading unit 25 has a step, and the light source installation unit that installs the light source is separated from the reading element installation unit that installs the reading element and the imaging lens, so that an image due to flare can be obtained. Suppress the impact. Further, by making this case a sealed structure, adverse effects on the image due to the mixing of foreign matters are eliminated.
[Selection] Figure 1

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an automatic document feeder mounted on an image forming apparatus such as a copying machine, a facsimile machine, a scanner device, or a multifunction machine.
[0002]
[Prior art]
An automatic document feeder (ADF) mounted on an image forming apparatus such as a copying machine, a facsimile machine, a scanner device, or a multi-function machine is a process of separating and conveying originals one by one from a bundle of originals set in a paper feeding unit. Then, the image information on each side of the document is read, and the document that has been read is discharged to the paper discharge unit. These conventional automatic document feeders have various purposes such as improving the transportability of transporting more documents per unit time and improving the transport quality of accurately transporting documents to the reading position.
Techniques for this measure are disclosed in the following patent documents.
[Patent Document 1]
JP 2002-354201 A [Patent Document 2]
No. 2894162 [Patent Document 3]
[Patent Document 1] Japanese Patent Laid-Open No. 2001-13740
Patent Document 1 discloses an image reading apparatus capable of reading a double-sided document by detachably attaching a second reading unit for reading a double-sided document to the first reading unit for single-sided reading. Says.
[0004]
Patent Document 2 can prevent image data from being lost by comparing the document sizes of the front and back sides, even if the detection level of the start and end of the document is reduced or a detection error of the start or end occurs in part. A simple double-sided reader is described.
[0005]
Patent Document 3 describes an automatic document feeder that has a means for detecting the width and length of a document, and is capable of conveying documents of different sizes in a mixed manner.
[0006]
[Problems to be solved by the invention]
Patent Documents 1 and 2 are ADFs in which a reduction optical system including a light source, an imaging lens, a reading element, and the like is used for reading a document second surface (back surface). These ADFs are all of a type that conveys a document straight, and have a document placement tray and a document discharge tray on both sides of the reading unit. For this reason, it is necessary to dispose the document placing portion and the document discharge portion on the left and right sides of the reading portion, and there is a problem that the occupied width of the reading device becomes large.
Further, in Patent Document 1, since the outer wall of the reading unit also serves as a sheet passing surface, paper dust, toner residue, dust, and the like adhering to the conveying roller may be mixed inside the reading unit, which may adversely affect the image. There is a problem that the nature is extremely high.
Patent Document 3 is an ADF in which a contact image sensor is arranged in a turn conveyance path, but when the first surface reading member of the document is configured by a reduction optical system, the second surface is configured by the contact image sensor. Then, it is necessary to tune the difference in the light source wavelength and the characteristics of the reading element in the image processing unit to match the image on the first surface, and there is a problem that the burden on the image processing unit increases.
[0007]
In view of the above-described problems, the present invention increases the area occupied by a machine by arranging a second reading unit for reading the second surface of the document at the lower part of the document placing table and effectively utilizing the space at the lower part of the document placing table. The first object of the present invention is to provide an ADF that can efficiently read both front and back sides of a document at the same image quality level.
[0008]
Further, by providing a step in the case for housing the components of the second reading unit and isolating the light source installation unit and the reading element installation unit, the influence of flare is suppressed in an optical system arranged in a limited space. The second object is to provide an ADF that can be used.
It is a third object of the present invention to provide an ADF that can eliminate an adverse effect on an image due to mixing of foreign matters by adopting a configuration in which the second reading unit is hermetically sealed.
[0010]
[Means for Solving the Problems]
According to the first aspect of the present invention, a document placing table on which a document to be read is placed, a feeding unit that separates and feeds a bundle of documents placed on the document placing table, and a feeding unit that feeds the bundle. A reading port for reading the first surface side of the fed document, and a side opposite to the first surface side of the document which is fed again by the feeding unit after reading the first surface side by the reading port. A reading unit that reads the second surface side, the document placing table and the reading unit are arranged so as to overlap each other, the document placing table is arranged in the upper part, and the reading unit is arranged in the lower part. To achieve the first objective.
[0011]
According to a second aspect of the present invention, in the automatic document feeder according to the first aspect, the reading unit includes a light source that irradiates the original, a reading element that reads reflected light from the original irradiated by the light source, and the A case for accommodating the light source and the reading element, wherein the case has a shape having a step for separating the light source and the reading element in a horizontal direction and a vertical direction, thereby achieving the second object. To do.
[0012]
According to a third aspect of the present invention, in the automatic document feeder according to the second aspect, the case of the reading unit has a sealed structure, thereby achieving the third object.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to FIGS. 1 to 3.
The present invention relates to an automatic document feeder (hereinafter referred to as ADF) that is used in an apparatus that conveys a document to be read to a fixed reader unit and reads an image while conveying the document at a predetermined speed. FIG. 1 is a sectional view showing a schematic configuration of an ADF according to an embodiment of the present invention, and FIG. 2 is a block diagram showing a system configuration of an image forming apparatus provided with the ADF according to the embodiment of the present invention. FIG. 3 is a diagram showing a schematic configuration of the second reading unit of the ADF according to the embodiment of the present invention.
[0014]
First, with reference to FIGS. 1 and 2, the basic configuration, operation, and action of an ADF according to an embodiment of the present invention and an image forming apparatus including the ADF will be described.
The ADF according to the embodiment of the present invention includes an original setting unit A for setting a read original bundle, a separation feeding unit B for separating and feeding originals one by one from the set original bundle, and a fed The registration section C, which has the function of aligning the original document with primary contact and the function of pulling out and conveying the aligned original document, and the turn for turning the conveyed original document and conveying the original surface toward the reading side (downward) Part D, first reading / conveying part E for reading the front surface image of the original document from below the contact glass, second reading / conveying part F for reading the back side image of the original document after the front side reading, and the original document that has been read on both sides A paper discharge unit G for discharging, a stack unit H for stacking and holding documents after reading, drive units 101 to 105 for driving these conveying operations, and a controller 100 for controlling a series of operations. That. The image forming apparatus including the ADF includes a main body operation unit 108 and a main body control unit 111, and performs communication with the ADF via the I / F 107.
[0015]
The original bundle 1 to be read is set on the original table 2 including the movable original table 3 with the original surface facing upward. Further, the width direction of the document bundle 1 is positioned in a direction perpendicular to the conveyance direction by a side guide (not shown). The document set is detected by the set filler 4 and the set sensor 5 and transmitted to the main body control unit 111 by the I / F 107. Further, an outline of the length in the document transport direction is determined by the document length detection sensor 30 or 31 provided on the surface of the document table 2. As the document length detection sensors 30 and 31, a reflection type sensor or an actuator type sensor that can detect even one document is used, and the sensor arrangement is an arrangement that can determine at least whether the document size is vertical or horizontal. And
The movable document table 3 can be moved up and down in the directions of arrows a and b shown in FIG. 1 by a bottom plate raising motor 105. When the set filler 4 and the set sensor 5 detect that a document is set, the bottom plate is moved. The movable motor table 3 is moved up so that the raising motor 105 is rotated forward so that the uppermost surface of the document bundle comes into contact with the pickup roller 7.
The pick-up roller 7 is moved in the directions of arrows c and d shown in FIG. 1 by a cam mechanism by the calling motor 101 while the movable document table 3 is raised, and is pushed by the upper surface of the document on the movable document table 3 to be raised in the c direction. The table rise detection sensor 8 detects the upper limit.
[0016]
When the print key is pressed from the main body operation unit 108 and a document feed signal is transmitted from the main body control unit 111 to the controller 100 which is the ADF control unit via the I / F 107, the pickup roller 7 moves the feed motor 102. The roller is rotated by forward rotation, and several (ideally, one) originals on the original table 2 are picked up. The rotation direction is a direction in which the uppermost document is conveyed to the sheet feeding port.
The paper feeding belt 9 is driven in the paper feeding direction by the normal rotation of the paper feeding motor 102, and the reverse roller 10 is driven to rotate in the reverse direction to the paper feeding by the normal rotation of the paper feeding motor 102, and the uppermost document and its uppermost document. The lower document is separated and only the uppermost document can be fed.
More specifically, the reverse roller 10 is in contact with the paper feeding belt 9 at a predetermined pressure, and in a state where it is in direct contact with the paper feeding belt 9 or through a single document, the reverse roller 10 rotates. Takes you counterclockwise. In the unlikely event that two or more documents have entered between the paper feeding belt 9 and the reverse roller 10, the reverse roller 10 is set so that the follower force is lower than the torque of the torque limiter. The paper rotates in the clockwise direction, which is the driving direction, and pushes back an excess document, thereby preventing double feeding.
[0017]
The original separated into one sheet by the action of the paper feed belt 9 and the reverse roller 10 is further fed by the paper feed belt 9, the leading edge is detected by the abutment sensor 11, and the pull-out roller 12 is stopped. bump into. Thereafter, the sheet is fed by a predetermined distance from the detection of the abutting sensor 11, and as a result, the paper feeding motor 102 is stopped while being pressed against the pull-out roller 12 with a predetermined amount of bending. Then, the driving of the paper feeding belt 9 is stopped.
At this time, by rotating the calling motor 101, the pickup roller 7 is retracted from the upper surface of the document, and the document is fed only by the conveying force of the paper feeding belt 9, so that the leading edge of the document is the nip of the pair of upper and lower rollers of the pullout roller 12. And the tip is aligned (skew correction). The pull-out roller 12 has a skew correction function and is a roller for conveying the skew-corrected document after separation to the intermediate roller 14 and is driven by the reverse rotation of the paper feed motor 102. During the reverse rotation of the paper feed motor 102, the pull-out roller 12 and the intermediate roller 14 are driven, but the pickup roller 7 and the paper feed belt 9 are not driven.
[0018]
A plurality of document width sensors 13 are arranged in the depth direction and detect the size in the width direction perpendicular to the transport direction of the document transported by the pull-out roller 12. Further, the length of the document in the conveyance direction is detected from the motor pulse by reading the leading edge and the trailing edge of the document with the butting sensor 11.
When the document is conveyed from the registration unit C to the turn unit D by driving the pull-out roller 12 and the intermediate roller 14, the conveyance speed at the registration unit C is higher than the conveyance speed at the first reading conveyance unit E. The processing time for setting and sending the document to the first reading unit is shortened.
When the leading edge of the document is detected by the reading entrance sensor 15, the conveyance speed of the document is read before the leading edge of the document enters the nip of the pair of upper and lower rollers of the reading inlet roller 16. Start deceleration to achieve the same speed. At the same time, the reading motor 103 is driven to rotate forward to drive the reading inlet roller 16, the reading roller 19, the reading outlet roller 23, and the second reading outlet roller 27.
When the registration sensor 17 detects the leading edge of the document, it decelerates over a predetermined conveyance distance, temporarily stops before the reading position 20, and transmits a registration stop signal to the main body control unit 111 via the I / F 107. . Subsequently, when a reading start signal is received from the main body control unit 111, the document whose registration has been stopped is transported at an increased speed so that the leading edge of the document rises to a predetermined transport speed when it reaches the reading position 20.
[0019]
At the timing when the leading edge of the document detected by the pulse count of the reading motor 103 reaches the first reading unit, a gate signal indicating an effective image area in the sub-scanning direction on the first surface is sent to the main body control unit 111. The document is transmitted until the trailing edge of the original comes off the reading unit.
In the case of single-sided original reading, the original that has passed through the first reading conveyance unit E is conveyed to the paper discharge unit G through the second reading unit 25. At this time, when the leading edge of the original is detected by the paper discharge sensor 24, the paper discharge motor 104 is driven to rotate forward to rotate the paper discharge roller 28 counterclockwise. Further, the discharge motor pulse count from the detection of the leading edge of the document by the discharge sensor 24 reduces the drive speed of the discharge motor immediately before the trailing edge of the document comes out of the nip of the pair of upper and lower rollers of the discharge roller 28, Control is performed so that the document discharged onto the discharge tray 29 does not jump out.
Further, in the case of double-sided document reading, after the leading edge of the document is detected by the paper discharge sensor 24, the controller 100 detects the leading edge of the document as detected by the pulse count of the reading motor 103 and reaches the second reading unit 25. A gate signal indicating an effective image area on the second surface in the sub-scanning direction is transmitted to the second reading unit 25 through the second reading unit 25 until the trailing edge of the document is removed. The second reading roller 26 serves as a reference white part for acquiring shading data in the second reading unit 25 as well as suppressing the floating of the original in the second reading unit 25.
[0020]
Next, the configuration of the second reading unit 25 will be described with reference to FIG.
The second reading unit 25 is disposed below the document setting unit A in FIG. 1 and includes a light source 203, folding mirrors 205 to 207, an imaging lens 209, a reading element 208, and a reflector 204 as components. These components are constituted by components having the same specifications as the components of the first reading unit (not shown) provided in the image forming apparatus, and the case 202 that also serves as the exterior of the second reading unit 25. And are fastened by a support member (not shown). The reflector 204 is disposed at a portion facing the light source 203 across the optical path indicated by the dotted line, and irradiates the document from the opposite side of the light source 203. The case 202 has a step so that the light source installation part for installing the light source 203 and the reflector 204 and the reading element installation part for installing the reading element 208 and the imaging lens 209 are separated, so that the light emitted from the light source 203 can be directly applied. It prevents the arrival of the image plane and suppresses the influence of flare.
Further, the other case 201 of the second reading unit 25 supports a reading glass 200 positioned on the document conveying surface, and is fitted so as to cover the case 201 on the case 202, and the outer peripheral surface of the case 202 or the case By providing the seal member 210 in the inner peripheral surface fitting portion 201, the second reading unit 25 is configured to be sealed, and foreign matter can be prevented from being mixed into the second reading unit 25.
[0021]
【The invention's effect】
According to the automatic document feeder of the first aspect, the second reading unit for reading the second surface of the document is arranged at the lower part of the document placing table, and the space occupied by the lower part of the document placing table is effectively used, thereby increasing the machine occupation area. Therefore, both the front and back sides of the document can be efficiently read at the same image level.
[0022]
According to the automatic document feeder of claim 2, the case that houses the component parts of the second reading unit is provided with a step, and the light source installation unit and the reading element installation unit are separated from each other, thereby being arranged in a limited space. The influence of flare can be suppressed in the optical system.
[0023]
According to the automatic document feeder of the third aspect, it is possible to eliminate the adverse effect on the image due to the mixing of foreign matter by adopting a configuration in which the second reading unit is hermetically sealed.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a schematic configuration of an ADF according to an embodiment of the present invention.
FIG. 2 is a block diagram illustrating a system configuration of an image forming apparatus including an ADF according to an embodiment of the present invention.
FIG. 3 is a diagram showing a schematic configuration of a second reading unit of the ADF according to the embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Document bundle 2 Document table 3 Movable document table 4 Set filler 5 Set sensor 7 Pickup roller 8 Table raising detection sensor 9 Paper feed belt 10 Reverse roller 11 Abutting sensor 12 Pull-out roller 13 Document width sensor 14 Intermediate roller 15 Reading entrance sensor 16 Reading entrance roller 17 Registration sensor 19 Reading roller 20 Reading position 23 Reading exit roller 24 Paper discharge sensor 25 Second reading unit 26 Second reading roller 27 Second reading exit roller 28 Paper discharge roller 29 Paper discharge tray 30 Document length detection sensor 31 Document length detection sensor 100 Controller 101 Calling motor 102 Paper feed motor 103 Reading motor 104 Paper discharge motor 105 Bottom plate raising motor 107 I / F
108 Main unit operation unit 111 Main unit control unit 200 Reading glass 201 Case 202 Case 203 Light source 204 Reflector 205 Folding mirror 206 Folding mirror 207 Folding mirror 208 Reading element 209 Imaging lens 210 Seal member

Claims (3)

A document table on which a document to be read is placed;
A feeding unit that separates and feeds a bundle of documents placed on the document placing table;
A reading port for reading the first side of the document fed by the feeding unit;
A reading unit that reads the first surface side at the reading port and then reads a second surface side opposite to the first surface side of the document fed again by the feeding unit;
An automatic document feeder, wherein the document placing table and the reading unit are arranged so as to overlap each other, the document placing table is arranged in the upper part, and the reading unit is arranged in the lower part. The reading unit is
A light source for illuminating the document;
A reading element for reading the reflected light from the document irradiated with the light source;
A case for housing the light source and the reading element;
2. The automatic document feeder according to claim 1, wherein the case has a shape having a step for separating the light source and the reading element in a horizontal direction and a vertical direction. The automatic document feeder according to claim 2, wherein the case of the reading unit has a sealed structure.

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