JPH05333630A - Document feeder - Google Patents

Abstract

PURPOSE:To obtain an document feeder capable of preventing the occurrences of jamming of a document and blurring of an image at the time of carrying the document. CONSTITUTION:The document feeder (RDF) is provided with a platen roller 21 and a table glass 22, and a white painted part 23 is formed on the table glass 22 by applying paint thereto. The painted part 23 is provided in order to carry out the correction of shading by a scanner unit incorporated in a copying machine, etc., with the RDF, and the end of the painted part 23 in the longitudinal direction (shown by an arrow M) forms an prescribed angle thetawith that in the direction (shown by an arrow L) parpendicular to the document 24 in the carrying direction (shown by an arrow K).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document feeder for feeding a document to a document reading position such as a copying machine, a scanner and a facsimile.

[0002]

2. Description of the Related Art FIG. 20 is a schematic structural view showing the structure of a conventional document conveying apparatus, and FIG. 20 (A) is a perspective view and FIG.
0 (B) is a sectional view taken along the line SS of FIG. 20 (A).

As shown in these figures, the conventional document feeder comprises a platen roller 11 and a table glass 12, and a white coating portion 13 is formed on the table glass 12 by painting. ..

In the image forming apparatus such as a copying machine equipped with the conventional document feeding device, the white coating section 13 has variations in sensitivity of the reading sensor of the document reading unit included in the image forming apparatus and uneven illumination of the document. It is provided to perform shading (white balance) correction for correcting the above.

The image of the document 14 conveyed by the document conveying device is read by the document reading unit at a position between the platen roller 11 and the table glass 12.

When the image of the original 14 is read, the white coating section 13 needs to accurately recognize the focus and the like by the reading unit. Therefore, the surface of the table glass 12 on which the original is conveyed (original conveyance). Surface) side.

The longitudinal direction of the end portion 13a of the white coating portion 13 (direction of arrow G in the figure) is perpendicular to the conveying direction of the document 14 (direction of arrow H in the figure).

[0008]

In such a conventional document conveying apparatus, since the white coating portion 13 is formed on the side of the table glass 12 on the document conveying surface, the end portion 13a of the white coating portion 13 is formed.
In this case, a step due to painting is formed on the original transport surface of the table glass 12. In addition, the end portion 13a of the white coating portion 13
Since the longitudinal direction G of the document 14 is orthogonal to the transport direction H of the document 14, the front end of the document 14 comes into contact with the step at the end portion 13a during document transport, which causes jamming of the document 14 and blurring of images. There is.

Therefore, the present invention provides a document feeding device capable of preventing the document from being jammed or the image from being blurred at the time of feeding the document by smoothly feeding the document in the white coating portion for shading correction. To do.

[0010]

A document feeding device for feeding a document to a document reading position on a document supporting plate, the document feeding device supplying the document to the document reading position, and shading correction on the document supporting plate. And a document discharging unit that discharges a document that has passed the document reading position. The layer has an end portion that forms a predetermined angle that is not orthogonal to the document transport direction. Have

[0011]

The document is supplied to the document reading position of the document support plate by the document feeding means, and when the image of the document is read at the document reading position, it is discharged by the document discharging means. In this way, when the image of the original is read, the edge of the layer provided on the original support plate for shading correction has a predetermined angle that is not orthogonal to the direction in which the original is conveyed. Since the document is formed, the document can be conveyed smoothly without the leading edge of the document coming into contact with the edge of the layer. Therefore, the jam of the document and the blurring of the image at the time of conveying the document can be prevented. be able to.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a side view showing the overall construction of a digital copying machine which is an embodiment of an image forming apparatus equipped with a document feeder according to the present invention.

As shown in FIG. 1, the digital copying machine 30 of this embodiment includes a scanner unit 31, a laser printer unit 32,
A multi-stage paper feeding unit 33 and a sorter 34 are provided.

The scanner section 31 is composed of a document placing table 35 made of transparent glass, a double-sided automatic document feeder (RDF) 36, and a scanner unit 40.

The multi-stage paper feeding unit 33 includes a first cassette 51,
It has a second cassette 52, a third cassette 53 and a fourth cassette 55 which can be added by selection.

In the multi-stage sheet feeding unit 33, the sheets are sent out one by one from the sheets stored in the cassettes of the respective stages,
It is conveyed toward the laser printer unit 32.

In the RDF 36, a plurality of originals are set at one time, and the originals are automatically read one by one in the scanner unit 40.
The scanner unit 40 is configured to read one side or both sides of a document according to the operator's selection.

The scanner unit 40 includes a lamp reflector assembly 41 for exposing a document and a plurality of reflecting mirrors 4 for guiding a reflected light image from the document to a photoelectric conversion element (CCD) 42.
3 and a lens 44 for forming a reflected light image from the document on the CCD 42.

When scanning a document placed on the document table 35, the scanner section 31 is configured to read the document image while the scanner unit 40 moves along the lower surface of the document table 35. When the RDF 36 is used, the original image is read while the original is conveyed while the scanner unit 40 is stopped at a predetermined position below the RDF 36.

The image data obtained by reading the original image with the scanner unit 40 is sent to an image processing unit (not shown), which will be described later, and subjected to various processing, and then temporarily stored in the memory of the image processing unit. In response to the output instruction, the image data in the memory is given to the laser printer section 32 to form an image on a sheet.

The laser printer unit 32 is a manual document tray 4
5. A laser writing unit 46 and an electrophotographic process unit 47 for forming an image are provided.

The laser writing unit 46 is a semiconductor laser which emits a laser beam according to the image data from the above-mentioned memory, a polygon mirror which deflects the laser beam at an equal angular velocity,
The laser beam deflected at a constant angular velocity is corrected so as to be deflected at a constant velocity on the photosensitive drum 48 of the electrostatic photography process section 47.
It has a -θ lens and the like.

The electrophotographic process section 47 has a charging device, a developing device, a transfer device, a transfer device
A peeling device, a cleaning device, a static eliminator and a fixing device 49 are arranged.

A conveying path 50 is provided downstream of the fixing device 49 in the conveying direction of the sheet on which the image is to be formed.
50 is a transport path 57 leading to the sorter 34 and a multi-stage paper feeding unit
It is branched to the conveyance path 58 leading to 33.

The conveying path 58 is branched in the multi-stage sheet feeding unit 33, and a reversing conveying path 50a and a double-sided / composite conveying path 50b are provided as the conveying paths after branching.

The reverse conveyance path 50a is a conveyance path for reversing the front and back sides of a sheet in a double-sided copy mode for copying both sides of a document. The double-sided / composite conveyance path 50b conveys paper from the reverse conveyance path 50a to the image forming position of the photosensitive drum 48 in the double-sided copy mode, or forms an image of a different original or a toner of a different color on one side of the paper. In a single-sided composite copy mode in which composite copying is performed, the transport path is for transporting the paper to the image forming position of the photosensitive drum 48 without reversing.

The multi-stage paper feeding unit 33 includes a common transport path 56, and the common transport path 56 includes the first cassette 51 and the second cassette.
Paper from 52 and third cassette 53 is electrophotographic process section
It is configured to carry out toward 47.

The common conveyance path 56 joins the conveyance path 59 from the fourth cassette 55 on the way to the electrophotographic process section 47 and communicates with the conveyance path 60.

The conveyance path 60 merges with the double-sided / composite conveyance path 50b and the conveyance path 61 from the manual document tray 45 at a confluence point 62 to form an image between the photoconductor drum 48 of the electrostatic photography process section 47 and the transfer device. It is configured to reach the formation position.
The confluence point 62 of the two transport paths is provided at a position close to the image forming position.

Therefore, in the laser writing unit 46 and the electrophotographic process section 47, the image data read from the above-mentioned memory is scanned on the surface of the photosensitive drum 48 by scanning the laser beam by the laser writing unit 46. The toner image formed as a latent image and visualized by toner is electrostatically transferred and fixed on the surface of the sheet conveyed from the multi-stage sheet feeding unit 33. The sheet on which the image is formed in this manner is sent from the fixing device 49 to the sorter 34 via the transport paths 50 and 57, or is transported to the reverse transport path 50a via the transport paths 50 and 58.

FIG. 3 is a block diagram of an image processing unit included in the digital copying machine 30 shown in FIG.

The image processing unit included in the digital copying machine 30 includes an image data input unit 70, an image processing unit 71, an image data output unit 72, a memory 73 including a RAM (random access memory) and a central processing unit. Arithmetic unit (CPU) 74
Is equipped with.

The image data input section 70 includes a CCD section 70a, a histogram processing section 70b and an error diffusion processing section 70c.

The image data input unit 70 processes the image data by the error diffusion method while binarizing and converting the image data of the original read from the CCD 42 of FIG. 2 and taking a histogram as a binary digital amount. The memory 73 is configured to be temporarily stored.

That is, in the CCD section 70a, after the analog electric signal corresponding to each pixel density of the image data is A / D (analog / digital) converted, MTF correction, black-and-white correction or gamma correction is performed, and the 256th floor It is output to the histogram processing unit 70b as a key (8-bit) digital signal.

In the histogram processing section 70b, the CCD section 70
The digital signal output from a is added for each pixel density of 256 gradations to obtain density information (histogram data), and if necessary, the obtained histogram data is sent to the CPU 74 or error diffusion as pixel data. It is sent to the processing unit 70c.

In the error diffusion processing unit 70c, the error diffusion method which is a kind of pseudo halftone processing, that is, the method of reflecting the binarization error in the binarization judgment of the adjacent pixel is output from the CCD unit 70a. The bit / pixel digital signal is converted into 1 bit (binary), and a redistribution operation is performed to faithfully reproduce the local area density in the original.

The image processor 71 is a multi-value processor 71a and 71b.
, Combination processing unit 71c, density conversion processing unit 71d, scaling processing unit 7
1e, an image processing section 71f, an error diffusion processing section 71g, and a compression processing section 71h.

The image processing section 71 is a processing section for finally converting the input image data into image data desired by the operator, until the memory 73 stores the finally converted output image data. The processing unit is configured to process.

However, each of the above-described processing units included in the image processing unit 71 functions as necessary and may not function.

That is, in the multi-valued processing units 71a and 71b, the data binarized by the error diffusion processing unit 70c is converted again into 256 gradations.

In the synthesizing section 71c, a logical operation for each pixel,
That is, the operation of logical sum, logical product, or exclusive logical sum is selectively performed. The data that is the object of this calculation is the pixel data stored in the memory 73 and the bit data from the pattern generator (PG).

In the density conversion processing section 71d, the relationship between the input density and the output density is arbitrarily set for the digital signal of 256 gradations based on a predetermined gradation conversion table.

In the scaling processing unit 71e, pixel data (density value) for the scaled target pixel is obtained by performing interpolation processing with the known data that is input according to the instructed scaling ratio. After the scanning is scaled, the main scanning is scaled.

In the image processing section 71f, various image processings may be performed on the input pixel data, and information collection such as feature extraction may be performed on the data string.

The error diffusion processing unit 71g performs the same processing as the error diffusion processing unit 70c of the image data input unit 70.

In the compression processing section 71h, binary data is compressed by the encoding called run length. Regarding the compression of the image data, the compression functions in the final processing loop when the final output image data is completed.

The image data output unit 72 includes a restoration unit 72a, a multi-value quantization processing unit 72b, an error diffusion processing unit 72c and a laser output unit 72d.
Is included.

The image data output section 72 is a memory in a compressed state.
The image data stored in 73 is restored, converted back to the original 256 gradations, and the error diffusion of 4-valued data, which is a smoother halftone expression than the binary data, is performed, and the data is output to the laser output unit 72d. It is configured to transfer.

That is, the decompression unit 72a decompresses the image data compressed by the compression processing unit 71h.

In the multi-value quantization processing unit 72b, the same processing as that of the multi-value quantization processing units 71a and 71b of the image processing unit 71 is performed. The error diffusion processing unit 72c performs the same processing as the error diffusion processing unit 70c of the image data input unit 70.

In the laser output section 72d, the digital pixel data is converted into a laser on / off signal based on a control signal from a sequence controller (not shown), and the laser is turned on / off.

The data handled by the image data input section 70 and the image data output section 72 is basically stored in the memory 73 in the form of binary data in order to reduce the capacity of the memory 73. It is also possible to process in the form of four-valued data in consideration of deterioration of image data.

Next, the structure and operation of the RDF 36 of FIG. 2 will be described.

FIG. 4 is a side view showing the structure of the RDF 36 shown in FIG.

As shown in the figure, the RDF 36 includes a paper feed tray 121, a paper feed roller 122, roller pairs 123a and 123b, conveyance roller pairs 124a and 124b, a branch selection unit 125, and conveyance roller pairs.
126a and 126b, conveying roller pair 127a and 127b, forward / reverse rotation roller 128, business card (postcard) tray 129, forward / reverse rotation roller 130,
Conveying roller pairs 131a and 131b, a conveying path 132 having a substantially semi-cylindrical shape having a curved surface, discharge roller pairs 133a and 133b,
In addition, output trays 134 and 135 are provided.

A plurality of documents are stacked on the paper feed tray 121. Documents on the paper feed tray 121 are fed by a paper feed roller 122 to a pair of rollers 123a and
It is taken up to the position of 123b.

Upper roller 123a of roller pair 123a and 123b
Rotates in the document transport direction (clockwise direction), and the lower roller 123b is in the same direction as the upper roller 123a (clockwise direction, that is, in the position in contact with the document, opposite to the document transport direction). Direction).

Therefore, when a plurality of originals are taken in by the paper feeding roller 122, the lower original is the lower roller 12
Only the top document is picked up by being flipped by 3b.

On the downstream side of the roller pairs 123a and 123b, there are arranged conveying roller pairs 124a and 124b for feeding the original.

The original sent from the pair of conveying rollers 124a and 124b is conveyed in one direction selected by the branch selecting unit 125 according to the type of original scanning.

When scanning only one side of the original at the original reading position P on the scanning surface 136 or when scanning the second side of both sides of the original, the pair of conveying rollers 124a and 124b which can be selected by the branch selecting unit 125 is selected. On the downstream side in one direction, there are arranged conveying roller pairs 126a and 126b for synchronously conveying the original from the right side (right hand direction in the drawing) of the scanning surface 136 to the left side (left hand direction in the drawing). ..

Further, when scanning the first side of both sides of the original, a pair of conveying rollers which can be selected by the branch selecting section 125.
On the downstream side in the other direction of 124a and 124b, the document is scanned on the scanning surface 136.
12 pairs of transport rollers for synchronous transport from the left side to the right side of
7a and 127b are arranged.

A forward / reverse roller 128 is arranged on the scanning surface 136 so that the original can be conveyed in either the left or right direction.

The scanning surface 136 corresponds to a part of the original placing table 35 of the digital copying machine 30 shown in FIG.

The downward surface of the original set on the paper feed tray 121 can be scanned on the scanning surface 136 by the pair of synchronous conveying rollers 126a and 126b and the forward / reverse rotation roller 128.
On the other hand, the upward surface is turned over and
The scanning surface 136 is formed by 127a and 127b and the forward / reverse rotation roller 128.
Can be scanned on.

On the left side of the scanning surface 136 in the drawing, the business card tray 12 is provided.
9 and a forward / reverse rotation roller 130 for transporting the business card from the business card tray 129 onto the scanning surface 136.

Downstream of the forward / reverse roller 128 (rightward in the drawing)
In addition, a branch selection unit 137 for branching the transport direction into two directions when scanning the first surface of both sides of the original is a transport roller pair 131a.
And 131b are located on the downstream side.

A discharge tray 135 for business cards and postcards is arranged in one direction on the downstream side (to the right in the drawing) of the pair of transport rollers 131a and 131b that can be selected by the branch selection unit 137.

A substantially semi-cylindrical guide portion 141 is arranged in the other direction downstream of the conveying roller pair 131a and 131b which can be selected by the branch selecting portion 137.

As shown in FIG. 4, the document conveying path 132 having a substantially semi-cylindrical shape so as to form a part of a protruding curved surface is provided with the document size detected by the sensor S27 (that is, the document conveying path 132). The length of the conveyance path 132 can be changed so that the front side and the back side of the document can be reversed at a predetermined timing.

Further, the transport path 132 whose length has been changed is configured to return to the neutral position when the end of the document whose front and back are reversed is detected by the sensor S26.

On the downstream side of the transport path 132 (to the left in the drawing),
A pair of conveyance rollers 124a and 124b for controlling the original direction described above.
Are arranged.

When only one side of the original is scanned at the original reading position P on the scanning surface 136 or when the second side of both sides of the original is scanned, the original is placed on the downstream side (upper left in the figure) of the forward / reverse roller 128. Discharge roller pairs 133a and 133b are arranged to reduce the length of the conveyance path in the linear direction and invert the document so that the surface to be scanned faces upward and discharges it to the outside.

Documents discharged by the pair of discharge rollers 133a and 133b are sequentially stacked on the discharge tray 134 from the bottom.

Conveying rollers 126a and 126b, conveying roller 127a
And 127b, and a sensor for detecting the document on the upstream side in the document conveyance direction of the conveyance rollers 131a and 131b.
S26, S27 and S31 are arranged respectively.

By the detection signal of the sensor S26, the conveying roller pairs 124a and 124b for direction control, and the conveying roller pair 13 are used.
The branch directions of 1a and 131b are controlled.

According to the detection signal of the sensor S27, the synchronization carrying rollers 126a and 126b, and the carrying rollers 127a and 12a.
The drive timing of 7b is controlled.

The detection signals of the sensor S31 control the driving directions of the forward / reverse rotation rollers 128 and 130.

FIG. 5 is a block diagram showing a schematic structure of the guide section 141 which constitutes a main part of the RDF 36 shown in FIG.

As shown in the figure, the guide section 141 includes a document size discrimination section 142 connected to the sensor S27, a drive section 143 connected to the document size discrimination section 142 and the sensor S26, and a drive section. Conveyor connected to 143
132 and

The operation of each part of the guide unit 141 shown in FIG. 5 will be described below.

The document size discriminating unit 142 receives a signal representing the size of the document output from the sensor S27, and discriminates the size of the document detected by the sensor S27 based on the input signal. ..

The drive unit 143 is configured to input a signal indicating the discrimination result by the document size discriminating unit 142 and move the conveying path 132 by a predetermined displacement amount according to the input discrimination result. Furthermore, when a signal is input from the sensor S26 that detects the end of the document, the drive unit 143 drives the transport path 132 to return to the neutral position based on the input signal.

Next, the operation of the RDF 36 of this embodiment when scanning only one side of the original will be described.

6 to 11 are views for explaining the operation in the case of scanning only one side of the original using the RDF 36 of FIG.
It is a side view of DF36.

As shown in FIG. 6, the document D is first set on the paper feed tray 121 with its scanning surface facing downward, and then set on the paper feed tray 121 as shown in FIG. The uppermost original D1 is conveyed to the pair of conveying rollers 124a and 124b for controlling the original direction by the paper feed roller 122 and the pair of rollers 123a and 123b for preventing two sheets from being taken.

The document D1 sent out by the pair of conveying rollers 124a and 124b is conveyed by the branch selecting section 125 in the direction in which the pair of conveying rollers 126a and 126b for synchronization are arranged.

Then, as shown in FIG. 8, the original D1 is
The front end of the scanning surface 136 is detected by the sensor S26, and is synchronously conveyed from the right side to the left side of the scanning surface 136 by the synchronous conveying roller pair 126a and 126b.

The original document D1 on the scanning surface 136 is sent out by the forward / reverse rotation roller 128 which rotates in the clockwise direction, and the branch selection units 138 and 139 discharge the discharge roller pair 133a and 13a.
3b is conveyed in the direction in which
Discharged on top.

During scanning of the document D1, the next document D
2 is conveyed to the position of the conveyance roller pair 126a and 126b for synchronization by the paper feed roller 122, the roller pair 123a and 123b, the conveyance roller pair 124a and 124b, and the branch selection unit 125, and the tip thereof is detected by the sensor S26. ..

Then, as shown in FIG. 9, the next original D2
Is the scanning surface by means of the pair of synchronization conveyance rollers 126a and 126b.
The document D2 is synchronously conveyed from right to left of the sheet 136, and as shown in FIG. 10, the document D2 is sent out by the forward / reverse roller 128, and the branch selection units 138 and 139 discharge the sheet discharge roller pair 133a.
And 133b are conveyed in the direction in which they are arranged.

Also in this case, similarly, the next original D3 is fed by the paper feed roller 122 and the pair of rollers 123a and 12 for preventing the two sheets from being taken in.
3b, conveying roller pairs 124a and 124b, and branch selection unit 125
Is conveyed to the position of the pair of conveying rollers 126a and 126b for synchronization, and its tip is detected by the sensor S26.

In the same manner, as shown in FIG. 11, the document D3 is synchronously conveyed from the right side to the left side of the scanning surface 136 by the synchronous conveying roller pair 126a and 126b.

Therefore, the first tray of a plurality of originals is at the bottom and the last page is at the top.
1 For the originals set on top, the last page is at the bottom and the scanning surface is ejected upward onto the output tray 134. No need to replace.

Next, the operation for scanning both sides of the original will be described.

12 to 17 are RDs for explaining the operation when scanning both sides of the original using the RDF 36 of FIG.
It is a side view of F36.

First, when a plurality of originals E are set on the paper feed tray 121, as shown in FIG.
The uppermost original E1 set above is fed by the paper feed roller 122.
Then, by the pair of rollers 123a and 123b for preventing the two-uptake, the sheet is conveyed to the pair of conveying rollers 124a and 124b for controlling the direction of the original.

Next, the original E1 is conveyed by the branch selection unit 125 from the conveying roller pairs 124a and 124b in the direction in which the synchronous conveying roller pairs 127a and 127b are arranged, and the leading end thereof is detected by the sensor S27.

Then, as shown in FIG.
The front and back sides of the sheet are reversed by the pair of transport rollers 127a and 127b and the forward / reverse roller 128 that rotates in the counterclockwise direction, and the sheets are synchronously transported from the left side to the right side of the scanning surface 136, and are transferred onto the paper feed tray 121. The upper surface of the set document E1 is scanned.

The original E1 on the scanning surface 136 is a forward / reverse roller.
It is sent out by 128, and sent out by the branch selection unit 140 to the pair of transport rollers 131a and 131b.

Then, the document E1 sent out by the pair of conveying rollers 131a and 131b is conveyed in the direction of the conveying path 132 by the branch selecting section 137, the front and back are reversed by the conveying path 132, and as shown in FIG. Roller pair 124a and
It is transported to 124b.

Further, the original E1 sent out by the pair of conveying rollers 124a and 124b is conveyed in the direction in which the pair of rollers 126a and 126b are arranged by the branch selecting section 125, and the leading end thereof is detected by the sensor S26. To be done.

The guide portion 141 includes a pair of conveying rollers 126a and 12a.
The sensor S26 on the upstream side of 6b and the pair of conveyance rollers 131a and 131b
When the sensor S31 on the upstream side of the document is both detecting the document E1, the document is conveyed by moving diagonally upward (the direction of the arrow) in the figure at a speed half the document conveying speed as shown in FIG. Increase the road length.

Further, in the conveyance path 132, the sensor S31 is used for the document E1.
When the trailing end is detected, as shown in FIG. 15, the document is moved diagonally downward (in the direction of the arrow) at a speed half that of the document to restore the length of the transport path 132 to the original length. ..

In FIG. 15, the document E1 is synchronized with the document reading position P on the scanning surface 136 from the right to the left by a pair of conveying rollers 126a and 126b for synchronization and a forward / reverse roller 128 which rotates clockwise. Transported and paper feed tray
The downward surface of document E1 set on 121 is scanned.

Then, as shown in FIG.
The upper document E1 is branched from the forward / reverse roller 128 by the branch selection unit 138.
And 139, the paper is conveyed toward the paper discharge rollers 133a and 133b.

Further, the next original E2 is fed by the paper feed roller 122, the roller pairs 123a and 123b, the conveying roller pairs 124a and 124b, and the branch selecting section 125 for synchronizing the conveying roller pair 127a and 127a.
It is conveyed to the upstream side of 127b, and its tip is detected by the sensor S27.

When the scanning of the first original E1 is completed, the process shown in FIG.
As shown in FIG. 7, the next original E2 is a pair of synchronization conveyance rollers.
The front and back sides are reversed by 127a and 127b and the forward / reverse rotation roller 128 that rotates in the counterclockwise direction, and the original reading position P on the scanning surface 136 is synchronously conveyed from left to right.
Similarly, both sides of the document E2 are similarly scanned.

Therefore, the plurality of originals E set on the paper feed tray 121 are set so that the first original of the plurality of originals is at the bottom and the final original E1 is at the top. The back surface and the front surface of the last sheet of document E1 are scanned in this order, and the front surface is discharged upward onto the paper discharge tray 134. Less than,
A plurality of originals E are sequentially scanned from the last original E1
Since the first original is scanned last, it is not necessary to change the order of the originals on the paper feed tray 121 and the paper discharge tray 134.

In the above-described embodiment, when scanning both sides of the original, the scanning directions of the respective sides are different, but when the first side of the original is read and stored and the second side is transferred to the recording paper. The directions may be matched with.

The direction of the transfer paper may be reversed before transferring the second surface to the recording paper.

FIG. 1 is a perspective view showing a schematic structure of an RDF which is an embodiment of a document feeder according to the present invention. FIG.
2 is a sectional view taken along line TT of FIG.

As shown in these figures, the R of this embodiment is
The DF includes a platen roller 21 and a table glass 22, and a white coating portion 23 is formed on the table glass 22 by painting.

The RDF of this embodiment is shown in FIGS.
The platen roller 21 and the table glass 22 correspond to the forward / reverse rotation roller 128 and the scanning surface 136 included in the RDF 36, respectively.

The coating unit 23 is a scanner unit included in the digital copying machine 30 shown in FIG. 2 equipped with this RDF.
It is provided to perform shading correction by 40.

The image of the original document 24 conveyed by the RDF is read by the scanner unit 40 shown in FIG. 2 at the position between the platen roller 21 and the table glass 22.

Since the coating unit 23 needs to accurately recognize the focus and the like by the scanner unit when the image of the original 24 is read, the surface of the table glass 22 on which the original is conveyed (original conveying surface). ) Side,
The longitudinal direction (direction of arrow M shown in the drawing) of the end portion 23a of the coating section 23 is perpendicular to the direction (direction of arrow K shown in the drawing) of the document 24 (direction of arrow K shown in the drawing). Are formed so as to form a predetermined angle θ.

FIG. 19 is a plan view of the table glass 22 shown in FIG. In FIG. 19, the platen roller 21 and the document 24 shown in FIG. 18 are omitted.

In the figure, a table glass is used without using RDF.
22 shows the reading position U of the scanner unit when the document is placed on 22 and scanned, the reading position V of the scanner unit when the document is scanned using RDF, and the reading position W of the shading correction data.

As shown in the figure, the shading correction data, that is, the white paint portion 23 is formed in a trapezoidal shape on the table glass 22, and the lower bottom of this trapezoidal original is centered at the reading position W. Length x along the transport direction K of 24
Further, the upper bottom corresponds to the length y of the document 24 including the reading position W along the transport direction K.

For example, when the length x is set to about 10 mm, the angle θ formed by the longitudinal direction M of the end portion 23a of the coating portion 23 with respect to the direction L perpendicular to the document conveying direction K is as follows. It can be determined by paying attention to the points, and in this embodiment, it is preferably 5 ° to 10 °.

When the angle θ is increased, the length y of the coating portion 23 above the table glass 22 in the figure becomes large, which causes a problem in space of the table glass 22. Further, when the angle θ is reduced, the leading edge of the conveyed document is likely to come into contact with the step at the end 23a of the coating section 23, and the document is easily jammed or the image is easily blurred.

However, from the viewpoint of preventing document jamming and image blurring during document transportation, the longitudinal direction M of the end portion 23a of the coating section 23 is in the direction L perpendicular to the document transportation direction K. On the other hand, it is preferable to have a large inclination, that is, it is preferable to select the angle θ as large as possible between the reading position V when RDF is used and the reading position U when RDF is not used. θ is not limited to 5 ° to 10 ° described above, and it is possible to select an optimum value for the angle θ according to the configuration of the image forming apparatus including the document conveying device.

The coating portion 23 of FIG. 1 is an embodiment of the layer formed on the original supporting plate of the present invention. 4, the paper feed tray 121, the paper feed roller 122, the roller pairs 123a and 123b, the transport roller pairs 124a and 124b, the branch selection unit 125, and the transport roller pair.
The pair of conveyance rollers 127a and 127b, and the forward / reverse rotation roller 128 are an example of the document feeding unit of the present invention. The normal / reverse rotation roller 130 and the discharge roller pair 133a and 13 of FIG.
3b and the paper discharge trays 134 and 135 are an example of the document discharge means. The document reading position P in FIG. 4 is an example of the document reading position of the present invention.

Therefore, according to the above-described embodiment, the shading correction coating portion 23 formed on the table glass 22.
Since the longitudinal direction M of the end portion 23a of the document forms a predetermined angle with respect to the direction L which is perpendicular to the document conveying direction K, the document can be conveyed smoothly, and therefore, when the document is conveyed. It is possible to prevent a document jam and an image blur.

[0128]

As described above, the present invention is a document feeding device for feeding a document to a document reading position on a document supporting plate, and a document feeding means for feeding a document to the document reading position and a document supporting device. The plate is provided with a layer provided for shading correction and a document ejection unit for ejecting a document that has passed the document reading position. The layer is a predetermined layer that is not orthogonal to the document conveyance direction. Since the document has the angled end portion, the document can be conveyed smoothly, and therefore, it is possible to prevent the document from jamming or the image from being blurred when the document is conveyed.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an embodiment of an original conveying apparatus according to the present invention, R
It is a perspective view which shows schematic structure of DF.

FIG. 2 is a side view showing the overall configuration of a digital copying machine which is an embodiment of an image forming apparatus equipped with a document feeder according to the present invention.

FIG. 3 is a block configuration diagram of an image processing unit included in the digital copying machine of FIG.

FIG. 4 is a side view showing the configuration of the RDF of FIG.

5 is a block configuration diagram showing a schematic configuration of a guide unit that constitutes a main part of the RDF of FIG.

FIG. 6 is a side view of the RDF for explaining the operation in the case of scanning only one side of a document using the RDF of FIG.

7 is a side view of the RDF for explaining the operation in the case of scanning only one side of a document using the RDF in FIG.

FIG. 8 is a side view of the RDF for explaining the operation when scanning only one side of a document using the RDF of FIG.

9 is a side view of the RDF for explaining the operation when scanning only one side of a document using the RDF of FIG.

FIG. 10 is a side view of the RDF for explaining the operation when scanning only one side of a document using the RDF of FIG.

FIG. 11 is a side view of the RDF for explaining the operation when scanning only one side of a document using the RDF of FIG.

FIG. 12 is a side view of the RDF for explaining the operation when scanning both sides of a document using the RDF of FIG.

FIG. 13 is a side view of the RDF for explaining the operation when scanning both sides of a document using the RDF of FIG.

FIG. 14 is a side view of the RDF for explaining the operation when scanning both sides of a document using the RDF of FIG.

FIG. 15 is a side view of the RDF for explaining the operation when scanning both sides of a document using the RDF of FIG.

16 is a side view of the RDF for explaining the operation when scanning both sides of a document using the RDF of FIG.

FIG. 17 is a side view of the RDF for explaining the operation when scanning both sides of a document using the RDF of FIG.

18 is a sectional view taken along line TT of FIG.

FIG. 19 is a plan view of the table glass of FIG.

FIG. 20 is a schematic configuration diagram showing a configuration of a conventional document feeder.

[Explanation of symbols]

 23 Coating unit 30 Digital copying machine 36 RDF 121 Paper feed tray 122 Paper feed rollers 123a, 123b Roller pair 124a, 124b, 126a, 126b, 127a, 127b Conveyor roller pair 125 Branch selection section 128, 130 Forward / reverse roller 133a, 133b Ejection Paper roller pair 134, 135 Output tray

Claims (1)

[Claims] 1. A document feeding device for feeding a document to a document reading position on a document supporting plate, comprising a document feeding means for feeding the document to the document reading position, and shading correction on the document supporting plate. Layers provided in
And a document discharge unit configured to discharge a document that has passed through the document reading position, wherein the layer has an end portion forming a predetermined angle that is not orthogonal to the document transport direction. Document transport device.