JP3452856B2 - Document feeder - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document feeder installed in a digital multi-function peripheral or an image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, as a document feeder mounted on a digital multi-functional peripheral or an image forming apparatus, there is a document feeder having a structure having a document reversing path adjacent to a document feeding path for reading both front and back sides of a document. Proposed.

For example, the document conveying apparatus disclosed in Japanese Patent Laid-Open No. 10-101257 discloses the production of image formation of double-sided originals while maintaining the productivity of reading (image formation) of single-sided originals and downsizing the apparatus. It is designed for the purpose of improving the performance of the document, and includes a separating unit for separating the document, a conveyance roller provided between the separation unit and a reading position (platen) for reading an image, and a document from the conveyance roller. Is provided to the reading position, a second conveying path that directly reverses the document and then directly leads to the reading position, and a switching unit that switches between the two conveying paths.

In the above structure, when only one side (front side) of the original is read, one original on the tray is fed by the separating means, and the original is moved to the reading position through the first conveying path switched by the switching means. The document is conveyed, the information on one side is read here, and then the document is ejected.

On the other hand, when reading both sides (front side and back side) of a document, one document on the tray is fed by the separating means, and the document is guided to the second conveyance path switched by the switching means. After reversing, the original is conveyed to the reading position and one side of the original is read. Next, the original is returned to the second conveyance path to reverse the original, and then the original is guided to the reading position through the first conveyance path switched by the switching means, and the surface opposite to the previous one is read. Then, the original is ejected.

By performing the reading of the single-sided original and the reading of the double-sided original as described above, the productivity of reading the single-sided original and the double-sided original is compatible with each other.

Further, in the document feeding apparatus disclosed in Japanese Patent Laid-Open No. 10-69129, the leading edge in the document feeding direction at the time of front side reading becomes the leading edge at the time of back side reading when reading both sides of the document. For this reason, a structure is provided in which an eight-shaped conveyance path is provided as a document reversing mechanism.

[0008]

However, in the document conveying apparatus described in Japanese Patent Laid-Open No. 10-101257, the speed at which the image information of the document is read and the document reversing path (second conveying path) are passed. Since time is constant,
There is a problem that it takes almost the same time to read an original regardless of the size of the original.

Further, in the document conveying apparatus described in Japanese Patent Laid-Open No. 10-69129, a plurality of reversing rollers (conveying rollers) are provided in a conveying path for reversing a document in order to convey the document without changing its leading edge. Is required, which not only hinders downsizing of the apparatus, but also complicates drive control for conveying the original.

In order to solve such a problem, in recent years,
In order to improve the reading speed of the original, a technology has been proposed to increase the speed of the original conveyance as compared with the original reading, but the original conveyance path with the same path length does not provide sufficient effect. is the current situation.

The present invention was devised to solve such a problem, and an object thereof is to arrange a plurality of inlets for introducing a document after reading information on the surface thereof into the sub-conveyance path. Not only does it enable efficient transport that corresponds to the document size, but also prevents the front and back edges of the inverted document from overlapping, preventing skewing of the document, damage, and image blurring during scanning An object of the present invention is to provide a document feeder that can read various images.

[0012]

In order to solve the above problems, a document feeder according to the present invention comprises a first main feeding path for feeding a document fed from a document tray to a document reading section,
The second main conveyance path that conveys the document whose front side image information has been read by the document reading section to the discharge tray, and the rear end of the document when front side scanning is performed to read the back side of the document after front side scanning. and a sub-passage for the switch back to the transport from the as the original tip second main transfer path to the first main conveying path, the sub-passage is, for each of a length corresponding to the type of document A plurality of paths are formed at each position of the second main transport path, and the plurality of sub-transport paths are formed.
After switching back to each position of the second main transport path
Each branch gate is installed to guide the originals to the sub-transport path.
The multiple branch gates are
Second main transport when the draft is transported to the output tray side
After opening the path and closing the sub-transport path, after reading this surface
When reading the back side of
At the position corresponding to the length of the original read by
Only the branch gate that closes the second main transport path
After the opening / closing control is performed to open the feeding path,
The document is switched back and the document is turned upside down,
From the transport path to the sub-transport path at the position corresponding to the length of the original
It is characterized by being transported .

According to the original conveying apparatus of the present invention having the above characteristics, by forming a plurality of sub-conveyance paths for switchback, the reading of a double-sided original can be performed depending on whether the original size is large or small. It is possible to change the introduction port of the sub-conveyance path for switching the document back and guiding it to the main conveyance path. That is, the document reading unit
All branch gates must be open during scanning of the original.
The original is transported to the second main transport path by
Depending on the length of the draft, the optimal location of each branch gate
Select a branch gate so that the trailing edge of the original passes through that branch gate.
When it passes, the branch gate is closed. By this
As a result, the efficiency of document transportation can be improved and the transportation time can be shortened. Further, since the original reversal point that matches the original size can be selected when reading one side of a document, the rear end of the document and the leading end of the document do not overlap when the reverse side of the reversed document is read, It is possible to prevent the occurrence of skew and jam.

Further, in the original conveying apparatus of the present invention, in the above structure, the plurality of sub-conveying paths are formed so as to merge as one sub-conveying path until they merge with the first main conveying path. It is characterized by being

According to the original conveying apparatus of the present invention having such characteristics, the plural conveying paths can be merged into the same conveying path so that the conveying paths can be made common and the size can be reduced. realizable.

[0016]

[0017]

[0018]

[0019]

[0020]

[0021]

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

First, before describing the document feeder A of the present invention, a copying machine equipped with the document feeder A will be described. FIG. 9 shows an example of the structure of a copying machine equipped with the document feeder A of the present invention.

This copying machine is provided with a scanner section 40 as an image reading means, a printing section 50, and a document feeder A which is a characteristic part of this embodiment. However, since the document feeder A will be described in detail with reference to FIG. 1 which will be described later, only representative symbols are given here.

The scanner section 40 reads the image of the original placed on the original table 31 made of transparent glass or the like or the image of the original fed one by one by the original conveying apparatus A to create image information. It is a part. This scanner unit 40 is
An exposure light source 41, a plurality of reflection mirrors 42a to 42c, an imaging lens 43, and a photoelectric conversion element (CCD) 44 are provided.

The exposure light source 41 irradiates the original placed on the original table 31 of the original conveying apparatus A or the original conveyed by the original conveying apparatus A with light. Each reflection mirror 4
As indicated by broken lines in FIG. 9, light rays 2a to 44c temporarily reflect the reflected light from the original document in the left direction in the figure, and thereafter, reflect it downward, and then toward the imaging lens 43 in the figure. It is designed to reflect to the right.

As the image reading operation of the original, the original table 3 is used.
When the document is placed on the document 1, the exposure light source 41 and the reflection mirror 42a are horizontally scanned along the document table 31 between the position shown by the solid line and the position shown by the phantom line in FIG. , The image of the original will be read. On the other hand, when reading a document transported by the document transport device A, the exposure light source 41 and the reflection mirror 42a are fixed to the positions shown by the solid lines in FIG. 9, and the document passes through the document reading unit 7 of the document transport device A. In that case, the image will be read.

The light reflected by the reflecting mirrors 42a to 42c and passing through the imaging lens 43 is guided to a photoelectric conversion element 44, and the reflected light is converted into an electric signal (original image information) in the photoelectric conversion element 44. It has become so.

The printing section 50 comprises an image forming section 51 and a transfer sheet conveying section 52. The image forming unit 51 includes a laser scanning unit (LSU) 51a and a drum-shaped photoconductor 51b. The laser scanning unit 51a irradiates the surface of the photoconductor 51b with laser light based on the original image information converted by the photoelectric conversion element 56. The photoconductor 51b rotates in the direction shown by the arrow in FIG. 9 and is irradiated with laser light from the laser scanning unit 51a to form an electrostatic latent image on its surface.

In addition to the laser scanning unit 51a, a developing device 51 is provided on the outer peripheral portion of the photoconductor 51b.
c, a transfer charger 51d, a cleaning device (not shown), a static eliminator 51e, and a main charger 51f are sequentially arranged along the circumferential direction. The developing device 51c develops the electrostatic latent image formed on the surface of the photoconductor 51b into a visible image with toner. The transfer charger 51d includes the photoconductor 51.
The toner image formed on the surface of b is transferred to the transfer paper P. The cleaning device removes the toner remaining on the surface of the photoconductor 51b after the toner transfer. The static eliminator 51e removes residual charges on the surface of the photoconductor 51b. The main charger 51f charges the surface of the photoconductor 51b before the electrostatic latent image is formed to a predetermined potential.

Therefore, when an image is formed on the transfer paper P, the surface of the photoconductor 51b is charged to a predetermined potential by the main charger 51f, and the laser scanning unit 51a is charged.
Irradiates the surface of the photoconductor 51b with laser light based on the document image information. After that, the developing device 51c turns the photoconductor 51b
A visible image with toner is developed on the surface of the toner, and the toner image is transferred to the transfer paper 5 by the transfer charger 51d. Further, thereafter, the toner remaining on the surface of the photoconductor 51b is removed by the cleaning device, and the residual charge on the surface of the photoconductor 51b is removed by the static eliminator 51e. As a result, one cycle of the image forming operation (printing operation) on the transfer paper P is completed. By repeating this cycle, it is possible to continuously form images on a plurality of transfer sheets P, P, ....

On the other hand, the transfer sheet conveying section 52 conveys the transfer sheets P, P, ... Stored in the sheet cassette 53 or the sheet tray 54 one by one to cause the image forming section 51 to form an image. The transfer sheet P on which an image is formed is discharged to the discharge tray 55.

The transfer paper carrying section 52 has a main carrying path 56 and a reverse carrying path 57. One end of the main transport path 56 is branched to face the discharge sides of the paper cassette 53 and the paper tray 54, and the other end faces the paper discharge tray 55. One end of the reverse conveyance path 57 is upstream of the position where the transfer charger 51d is provided (lower side in the drawing).
Is connected to the main conveyance path 56, and the other end is on the downstream side (upper side in the drawing) of the position where the transfer charger 51d is provided.
And is connected to the main transport path 56.

The upstream end of the main transport path 56 (the paper cassette 53
Pickup rollers 56a, 56a having a semicircular cross section are provided at the portion facing the discharge side of the sheet tray 54). Paper feed rollers 56b and 56b are arranged immediately downstream of the pickup rollers 56a and 56a.
The pickup roller 56a and the paper feed roller 56b
Rotation of the paper cassette 53 or paper tray 54
The transfer sheets P, P, ... Stored in the sheet can be intermittently fed to the main transport path 56 one by one.

A registration detection switch 56c and registration rollers 56d and 56d for detecting the passage of the transfer paper P are provided upstream of the position where the transfer charger 51d is provided in the main transport path 56, respectively. .
The registration rollers 56d and 56d convey the transfer paper P while aligning the toner image on the surface of the photoconductor 51b with the transfer paper P. A pair of fixing rollers 36e, 36e for fixing the toner image transferred onto the transfer paper 5 by heating and the transfer paper 5 are provided downstream of the position where the transfer charger 31d is provided in the main transport path 56. , 36e are provided for fixing detection switches 36f, respectively.
At the downstream end of the main transport path 36, the transfer paper P is discharged onto the paper discharge tray 55.
A pair of paper discharge rollers 56g for discharging paper to the sheet and a paper discharge detection switch 5 for detecting discharge of the transfer paper P
6h are arranged respectively.

A branch claw 58 is provided at the connecting position of the upstream end of the reversing conveyance path 57 with respect to the conveyance path 56. The branch claw 58 is rotatable about a horizontal axis between a first position shown by a solid line and a second position shown by a virtual line in FIG.
When the branch claw 58 is at the first position, the transfer paper P is discharged to the paper discharge tray 55, and when it is at the second position, the transfer paper P is supplied to the reverse conveyance path 57.
Transport rollers 57a, 57 are provided at a plurality of locations on the reverse transport path 57.
.. are provided, and when the transfer sheet P is supplied to the reversing conveyance path 57, these conveyance rollers 57a, 57 are provided.
The transfer paper P is conveyed by a, ...
The transfer paper P is reversed on the upstream side of 6d and is again conveyed through the main conveyance path 56 toward the transfer charger 51d. That is, an image can be formed on the back surface of the transfer paper P.

FIG. 10 is an operation flowchart in the copy mode of the copying machine having the above structure.

When a copy processing print request is issued to the copying machine (step S401), the number of prints, print magnification, recording paper size, etc. are set by this print request, and the original reading mode is selected (single-sided original or Double-sided original) and print mode selection (single-sided printing or double-sided printing) are performed (step S402).

Thereafter, the document is placed on the document tray (step S403), and the document reading process (step S40).
4) and the printing process (step S407) are processed in parallel.

In the document reading process, it is judged whether all the documents have been read (step S405),
It is determined whether or not the document is discharged to the document discharge tray (step S406), and these steps S405 and S4 are performed.
In the state in which both 06 are completed (that is, step S40
5, when both are determined to be Yes in S406), the document reading unit ends one job of the corresponding print request.

Further, in the printing process, it is judged whether or not there is next printing (step S408), and it is judged whether or not the recording paper has been completely discharged to the paper discharge tray (step S40).
9) and in the state where both of these steps S408 and S409 are completed (that is, steps S408 and S4).
When both are determined to be Yes in 09), the printing unit ends one job of the corresponding print request. Thus, the print request for one job is completed by the completion of both processes in which the parallel processes are performed.

FIG. 1 is a sectional view showing the basic structure of a document feeder A of the present invention mounted on a copying machine having the above structure.

First, the basic structure will be described, and then the document reading process in the document conveying device A having the basic structure will be described.

This document feeder A includes a document tray 1, a document feed section 2 including a pickup roller 2a and a separating plate 2b, a first main transport path 4a, a document input sensor 5 and a PS.
A document reading unit 7 including a roller 6, a platen glass 7a and a document pressing plate 7b, a second main transport path 4b, a transport roller 13 provided in the second main transport path 4b, a reversibly rotatable discharge roller 14, and an intermediate tray. Swing plate 15, intermediate tray 1
6. A document discharge tray 17 is provided.

That is, the originals placed on the original tray 1 are separated one by one by the original feeding section 2 composed of the pickup roller 2a and the separating plate 2b and conveyed to the first main conveying path 4a. It After the document is confirmed to be conveyed by the document input sensor 5, the conveyed document is temporarily stopped by the PS roller 6 arranged to adjust the image reading timing with the leading edge of the document, and is re-conveyed with the timing adjusted. To be done. When passing through the document reading unit 7, the document is illuminated by the light source 41, and the reflected light is reflected by the mirror 4.
CCD 44 through 2a to 42c and the imaging lens 43
Is received, the image information of the document is read, and image processing is performed by a control unit (not shown). The original document thus read is conveyed through the fourth main conveyance path 4b via the conveyance roller 13 and passes through the reversibly rotatable discharge roller 14.
Then, the traveling direction of the document is determined by the position where the intermediate tray swing plate 15 is arranged (either the home position 1 shown by the solid line in the figure or the home position 2 shown by the broken line in the figure), and the intermediate direction. The sheet is conveyed to either the tray 16 or the document discharge tray 17.

Next, the "single-sided reading process" in the document conveying apparatus A will be described with reference to the flowchart shown in FIG.

The document reading process shown in FIG. 9 (step S
In 404), when the single-sided reading process is selected,
It is determined whether or not the intermediate tray swing plate 15 of the document discharge unit is in the home position 1 (step S501). At this time, the home position 1 is the position shown by the solid line in FIG. 1, and is arranged to guide the read document to the document discharge tray 17. As a result of the determination in step S501, the intermediate tray swing plate 15 is set to the home position 1
If not, the intermediate tray swing plate 15 is moved to the home position 1 (step S510).

After the position of the intermediate tray swing plate 15 is determined in this manner, the document is conveyed by the pickup roller 2a for feeding the document through the first main conveyance path 4a (step S).
502), the PS roller 6 is temporarily stopped (step S50).
3) Then, the document is re-fed at the timing of reading the document (step S504). The re-conveyed document is read by the document reading unit 7 (step S505).

At this time, it is determined whether or not the image information of the read document is input to the memory of the control unit (not shown) (step S506). This determination is determined by the number setting of single printing or multi-printing when the number of printed sheets is set in step S402 shown in FIG. That is, multi-printing is performed when memory input is performed (step S507). On the other hand, when the memory input is not performed, single printing is performed (step S51).
1). In the case of single printing, after the image information of the read document is image-processed by the control unit, the image forming unit 5
1 to the laser scanning unit 51a.

While image processing and transmission are being performed in this manner, the original document is conveyed through the conveyance roller 13 to the paper discharge roller 14 which is reversibly rotatable on the second main conveyance path 4b.
The document is guided to the document discharge tray 17 due to the relationship between the rotation of the document discharge direction by the discharge rollers 14 (right rotation in FIG. 1) and the position of the intermediate tray swing plate 15 (home position 1) (step S508). ). In this way, the one-sided reading process of the document is performed.

Such a "single-sided reading process" is performed in the case where the image information is present only on one side of the document, or when the user's read request is a request to read the single-sided image information even if there is image information on both sides. Done.

Next, the "double-sided reading process" in the original conveying apparatus A having the above structure will be described with reference to the flowcharts shown in FIGS.

When the double-sided reading process is selected in the document reading process (step S404) shown in FIG. 10, the double-sided document is conveyed by the pickup roller 2a for feeding the document through the first main conveyance path 4a (step S60).
1), temporarily stop at the PS roller 6 (step S60)
2). Next, it is determined whether or not the intermediate tray swing plate 15 of the document discharge section is at the home position 2 (step S).
603). At this time, the home position 2 is the position shown by the broken line in FIG.
It is arranged to lead to 6. This step S60
As a result of the determination in 3, when the intermediate tray swing plate 15 is not in the home position 2 (when it is determined No in step S603), the intermediate tray swing plate 15 is moved to the home position 2 (step S624). In this way, after moving the position of the intermediate tray swing plate 15 to the home position 2, the document is re-fed at the document reading timing (step S604). The image information on the document surface of the document that has been re-fed is read by the document reading unit 7 (step S605). The image information on the surface of the document read at this time is input to the memory in the control unit (step S606).

At this time, the image information of the front surface of the document to be stored is in a state of being image-processed. While the image is processed and stored as described above, the original is conveyed to the paper discharge roller 14 which is reversibly rotatable in the second main conveyance path 4b through the conveyance roller 13, and the paper discharge roller 14 rotates the original in the paper discharge direction ( 1) and the position of the intermediate tray swing plate 15 is guided to the intermediate tray 16 (step S607).

The original guided to the intermediate tray 16 is temporarily stopped while the trailing end of the original in the original conveying direction is sandwiched by the paper discharge rollers 14 (step S608).

The process up to this point is the "front-side document reading conveyance process". After that, the reversible rotatable discharge roller 14 rotates in a direction opposite to the rotation direction in step S607 (see FIG.
The original is conveyed through the sub-conveyance path 18 by performing the middle left rotation (step S609). The conveyed original is temporarily stopped by the PS roller 6 (step S610), and is conveyed again at the original reading timing (step S611). The original that has been re-fed is read by the original reading unit 7.
At, the image information on the back side of the document is read (step S612). At this time, the read image information of the back side of the document is subjected to image processing by the control unit and then image forming unit 51.
Is transmitted to the laser scanning unit 51a (step S613).

While image processing and transmission are being performed in this manner, the original document is conveyed through the conveyance roller 13 to the paper discharge roller 14 which is reversibly rotatable in the second main conveyance path 4b.
The document is guided to the intermediate tray 16 due to the relationship between the rotation of the document discharge direction by the discharge rollers 14 (right rotation in FIG. 1) and the position of the intermediate tray swing plate 15 (home position 2) (step S614). The documents led to the intermediate tray 16 are
The trailing end in the document transport direction is temporarily stopped while being sandwiched by the reversible rotatable discharge rollers 14 (step S615).

The process up to this point is the "reverse side document reading and conveying step". Further, the temporarily stopped document is conveyed through the sub-conveyance path by the reversible rotatable discharge roller 14 rotating in the opposite direction to the rotation direction in step S614 (left rotation in FIG. 1) (step). S616). For the document conveyed in this manner, it is determined by the document input sensor 5 whether the trailing edge of the passing document has passed the document input sensor 5 (step S617). At this time, if the trailing edge of the original has passed and there is a next original (if Yes in step S618), the next original is picked up by the pickup roller 2a for feeding the original to the first main conveyance path 4a. Is conveyed (step S619), the PS roller 6 is temporarily stopped (step S620), and the process stands by until the reading timing comes.

Thus, even while the next original is being conveyed,
After the front and back sides of the document are read, the document is conveyed through the conveyance path.

The original conveyed in this way is detected by the paper input sensor 5.
After passing through, it is determined whether the intermediate tray swing plate 15 of the document discharge unit is at the home position 1 (step S621). At this time, since the intermediate tray swing plate 15 is in the state of being arranged in the home position 2 in step S603, it moves to the home position 1 (step S625). In this way, the intermediate tray swing plate 15
Is determined as home position 1. Even during this period, the original document passes through the transport roller 13 and the second main transport path 4
b is conveyed to the paper ejection roller 14 capable of reversible rotation, and the paper ejection roller 14 rotates in the original paper ejection direction (right rotation in FIG. 1),
Due to the position of the intermediate tray swing plate 15, the document is discharged to the document discharge tray 17 (step S623).

At this time, when it is confirmed that the next original document, which has been waiting by the PS roller 6, has passed through the original document reading section 7 (step S6).
22) Then, the document is re-fed and the document is read.

The process up to this point is the "document empty conveyance process". In this way, the double-sided reading process of the document is performed.

As described above, when reading both sides of a document,
There are three processes of document transportation: a "front-side document reading transport process", a "rear-side document reading transport process", and an "document empty transport process". In this case, the reason why the "conveyance process for front-side document reading" and the "rear-side document reading and conveying process" are naturally carried out, and the "idual document conveying process" is subsequently performed is
After the "reverse side document reading and conveying step" is completed, the position of the intermediate tray swing plate 15 is moved to move the original sheet discharge tray 17
This is because if the originals are ejected, the front and back of the originals will not be aligned when a plurality of originals are placed, and the pages cannot be aligned. In order to eliminate such an inconvenience, the "manual empty conveyance process" is essential.

The operation of the basic configuration of the document feeder A has been described above. Next, the configuration of the switchback mechanism, which is a characteristic part of the document feeder A of the present invention, will be described with reference to FIG.
Will be described with reference to. FIG. 2 is a diagram showing a transport path having a plurality of branch gates.

In FIG. 2, in the present invention, the first sub-transport path 23 and the second sub-transport path 2 are provided at three locations on the second main transport path 4b.
4 and a third sub-transport path 25 are provided. These sub-conveyance paths 23 to 25 are formed at the respective positions of the second main conveyance path 4b so as to correspond to the respective lengths according to the type of document. Further, these sub-transport paths 23 to 25 are formed so as to merge as one sub-transport path 18 until they merge with the first main transport path 4a. In addition, each sub transport path 2
First to third branch gates 20 to 22 for guiding the switched-back originals to the sub-transport paths 23 to 25 are provided at the confluence of the third to the second transport paths 4 to 25, respectively. .

The operation of each branch gate 20 to 22 at the time of reading one side of a document and at the time of reading both sides of a document will be described.

Regarding the open / closed state of each of the branch gates 20 to 22, all the first branch gate 20, the second branch gate 21, and the third branch gate 22 are in a solid line state and in a broken line state are closed states.

In the normal state, the first guide for guiding the original document to the first sub-transport path 23, the second sub-transport path 24, and the third sub-transport path 25.
The branch gate 20, the second branch gate 21, and the third branch gate 22 are all in an open state by turning off all solenoids (not shown) that control the opening and closing of the branch gates 20 to 22, and pass through the second main transport path 4b. It does not interfere with the transportation of the originals.

In the case of single-sided reading, the original fed by the pickup roller 2 is conveyed to the original reading section 7 through the first main conveyance path 4a, and the surface information of the original is read by the original reading section 7. . The document whose surface information has been read is transported to the transport roller 13 and is then transferred to the second roller.
The main conveyance path 4b is further sent to the paper discharge roller 14 which is reversibly rotatable. At that time, the first branch gate 20, the second branch gate 21, and the third branch gate 22 are turned off by turning off all solenoids (not shown) that control opening and closing of each branch gate, and open the second main transport path 4b. Be careful not to interfere with the passage of originals. The document sent to the paper discharge roller 14 is directly discharged to the document discharge tray 17 and the one-sided reading is completed.

Similarly, when the next original is fed, after the reading of the next original is completed, each branch gate 20 ...
The operation of discharging the document to the document discharge tray 17 by the transport roller 13 and the discharge roller 14 is repeated with 22 kept open, and the above operation is repeated until the document is completely fed. Read.

Next, the case of double-sided reading will be described with reference to the control flowcharts shown in FIGS. 6 and 7. This control flowchart is shown in FIG. 4 and FIG.
In the flowchart shown in FIG. 5, processing is performed between steps S605 and S609 and between steps S612 and S616.

In double-sided reading, the original fed by the pickup roller 2 is conveyed to the original reading section 7 through the first main conveying path 4b, and the original reading section 7 reads the surface information of the original. . The document whose surface information has been read is transported to the transport roller 13 and is then transferred to the second roller.
The main conveyance path 4b is further sent to the paper discharge roller 14 which is reversibly rotatable. The first branch gate 20, the second branch gate 21, and the third branch gate 2 are fed to the discharge roller 14.
Indicated at 2 are solenoids (not shown) for controlling the opening and closing of the respective branch gates, which are all turned off so as to be in an open state so that the conveyance of the document passing through the second main conveyance path 4b is not hindered.

The original sent to the paper discharge roller 14 is conveyed at its rear end to each reversal point or discharged to the original paper discharge tray 17 (not shown) depending on the length of the original.

The relationship between each reversal point and the document length is as follows. When the original is reversed, select the reversal point where the leading edge of the original does not come into contact with the trailing edge of the original and pass the shortest conveyance path according to the length of the original, and then select the trailing edge of the original. Transport to the reversal point. That is, in the case of the present embodiment, each inversion point 26, 27, 2
The selection of 8 is selected according to the document size length, for example,
The reverse point 26 is selected when the original size length is short, the reverse point 27 is selected when the original size length is medium, and the reverse point 2 is selected when the original size length is long.
8 is selected. At this time, if the document size length is extremely long or extremely short, the sub-transport paths 23 to 25
In this case, there is a possibility that the document may be retained or the front end and the rear end of the document may overlap during the reversing operation. In this case, the document is forcibly discharged from the discharge roller 14.

That is, to explain in detail with reference to the control flowcharts shown in FIGS. 6 and 7, the original is conveyed to the first reversal point 26 (step S701), and it is confirmed that the document has reached the first reversal point 26. Then, it is determined whether the document size length corresponds to the first branch gate 20 (steps S702, S703). Here, when the document size length corresponds to the first branch gate 20 (when it is determined Yes in step S703), the trailing end of the document (the trailing end in the document transport direction) is set to the discharge roller 14 It is stopped in the state sandwiched by (step S704), and the first branch gate 20
The first branch gate 20 by turning on the solenoid for controlling the
Is closed (step S705).

On the other hand, the original size length is the first branch gate 2
If it does not correspond to 0 (if No is determined in step S703), the document is conveyed to the second reversal point 27 (step S706), and it is confirmed that the document has reached the second reversal point 27. It is determined whether the document size length corresponds to the second branch gate 21 (step S70).
7, S708). If the document size length corresponds to the second branch gate 21 (Yes in step S708).
If it is determined to be s), the trailing edge of the document (the trailing end in the document transport direction) is stopped while being sandwiched by the discharge rollers 14 (step S709), and the solenoid for controlling the second branch gate 21 is turned on. Then, the second branch gate 21 is closed (step S710).

On the other hand, when the original size length is the second branch gate 2
If it does not correspond to 1 (No in step S708), the document is conveyed to the third reversal point 28 (step S711), and it is confirmed that the document has reached the third reversal point 28, It is determined whether the document size length corresponds to the third branch gate 22 (step S71).
2, S713). Here, when the document size length corresponds to the third branch gate 22 (Yes in step S713).
If it is determined to be s), the trailing edge of the document (the trailing end in the document transport direction) is stopped with the discharge rollers 14 sandwiched (step S714), and the solenoid for controlling the third branch gate 22 is turned on. Then, the third branch gate 22 is closed (step S715).

On the other hand, if it is determined No in step S713, that is, if the document size length is extremely long or extremely short, the documents are retained in the sub-conveyance paths 23 to 25, or the document is being reversed. Since there is a possibility that the leading edge and the trailing edge of the original will overlap, the operation proceeds to step S716, and in this case, the original is forcibly ejected by the discharge roller 14.
Eject more.

Next, a specific example will be given and described again. For example, when the original is A4, the rear end of the original is conveyed to the first reversal point 26, the driving of the paper discharge roller 14 is stopped, and the original conveyance is stopped. Then, at the same time when the driving of the paper discharge roller 14 is stopped, the driving of the PS roller 6 and the conveyance roller 13 is also stopped. This is the original that has been reversed by the operation described below.
This is because the sheet is temporarily stopped by the PS roller 6 so that skew feeding of the document can be corrected.

After the trailing edge of the original is conveyed to the first reversing point 26, the solenoid for controlling the first branch gate 20 among the solenoids (not shown) for controlling the opening and closing of each branch gate is turned on to turn on the first branch gate 20. Closed.
After the first branch gate 20 is closed, the discharge roller 14
Is rotated in the opposite direction to the paper discharge direction (hereinafter referred to as the reverse paper feed direction). When the paper discharge roller 14 is rotated in the reverse paper feeding direction, the original returns to the inside of the apparatus, but since the first branch gate 20 is in the closed state, the original is not conveyed to the conveying roller 13 but is conveyed to the first sub-conveying path 23. Is guided.

The document guided to the first sub-transport path 23 joins another sub-transport path 18 as it is and is transported to the first main transport path 4a. The original conveyed to the first main conveying path 4a hits the PS roller 6 and is temporarily stopped, and the skew feeding of the original is corrected. For the document whose skew feeding correction has been completed, the back side information of the document is read by the document reading unit 7 by rotating the PS roller 6. When the PS roller 6 is rotated, among the solenoids that control the opening and closing of the branch gates 20 to 22, the solenoid that controls the first branch gate 20 is turned off and the first branch gate 20 is opened.
The reading of the back side is completed so that the conveyance path of the document conveyed on the second main conveyance path 4b is not obstructed. Further, the operation of the paper discharge roller 14 is stopped, and the first branch gate 20 is opened so that the PS roller 6 is rotated so that no load is applied to the original when it is conveyed to the original reading unit 7. , Be careful not to degrade the reading quality. After that, the paper discharge roller 14 is rotated in the paper discharge direction again after the back surface of the document is read, and the document is conveyed after the conveyance roller 13.

At this time, since the optimum reversal point is selected according to the length of the document, the leading edge of the document whose back side has been read does not come into contact with the trailing edge of the document whose back side has not been read. The skew of the document can be prevented and the document can be transported for a shorter time because it passes through the shortest transport path. In the case of the conventional technique, since there is only one reversal point, the leading edge of the document that has been read and the trailing edge of the document that has not been read may come into contact with each other, depending on the length of the document, so that the document is skewed. There was a problem that it took a long time to convey the document because a line occurred and the reading quality deteriorated, and it did not pass the shortest conveyance path.
In the document feeder A of the present invention, such a problem does not occur as described above.

After the back surface is read, the "reverse operation of empty originals" for page alignment is performed, so the same reversing operation as that performed before the back surface reading is performed.

After the "original empty conveyance process" for page alignment is completed, the original that has been reversed up to the discharge roller 14 is discharged to the original discharge tray 17 and the double-sided reading process ends. However, the original is not read during the "original empty conveyance process".

Similarly, when the next original is fed, the reversing operation is performed after the front side reading is completed, and the reversing operation is performed after the back side reading is completed. The operation of discharging the document to the paper tray 17 is repeated, and the document is read by repeating the above-described reading and reversing operations until the feeding of the document is completed.

Note that the relationship between the document length and the reversal point is not uniformly determined, and may be changed to an optimum relationship depending on the device for carrying out the present invention. Further, the opening / closing timings of the respective branch gates are not uniformly determined, and may be changed to an optimum relationship depending on the device implementing the present invention.

FIG. 8 is a timing chart showing the timing for controlling the branch gates 20 to 22 depending on the size of the original. Referring to this timing chart,
The difference in timing for controlling each branch gate due to the difference in document size will be described.

The timing for controlling each of the branch gates 20 to 22 is set to a corresponding predetermined value after a predetermined time corresponding to the size of the fed document is passed after the trailing edge of the document passes the document input sensor 5. Control the branch gate.

FIG. 8A shows the timing when the document size length is short, and after the time a has elapsed since the trailing edge of the document passed through the document input sensor 5, the discharge roller 14 and the PS roller 6 are stopped. At the same time, among the solenoids that control the opening and closing of each branch gate, the solenoid that controls the first branch gate 20 is turned on to close the first branch gate 20. After the first branch gate 20 is closed, the paper discharge roller 14 is rotated in the reverse feeding direction to reverse the original. In this case, when reversing an original having a small original size length, the solenoids controlling the second branch gate 21 and the third branch gate 22 among the solenoids controlling the opening and closing of each branch gate (not shown) are turned off. , The second branch gate 21 and the third branch gate 22 are left open.

FIG. 8B shows the timing when the size of the original is medium, that is, when the trailing edge of the original has passed the original paper input sensor 5 and b hours have elapsed, the paper discharge roller 14 and the PS roller 6 are provided. Of the solenoids that control the opening and closing of each branch gate, the solenoid that controls the second branch gate 21 is turned on to close the second branch gate 21. After the second branch gate 21 is closed, the paper discharge roller 14 is rotated in the reverse feeding direction to reverse the original. In this case, when reversing a medium-sized document, the solenoids controlling the first branch gate 20 and the third branch gate 22 among the solenoids controlling the opening and closing of each branch gate (not shown) are turned off. And then the first
The branch gate 20 and the third branch gate 22 are left open.

FIG. 8C shows the timing when the size of the document is long, and after c time has elapsed since the trailing edge of the document passed the document input sensor 5, the discharge roller 14 and the PS roller 6 are stopped. At the same time, among the solenoids that control the opening and closing of each branch gate, the solenoid that controls the third branch gate 22 is turned on to close the third branch gate 22. After the third branch gate 22 is closed, the paper discharge roller 14 is rotated in the reverse paper feed direction to reverse the original. In this case, when reversing an original having a long original size, the solenoids controlling the first branch gate 20 and the second branch gate 21 among the solenoids controlling the opening and closing of each branch gate are turned off, and the 1 branch gate 20
And the second branch gate 21 is left open. In this way, depending on the size of the original, 1 from each branch gate.
By selecting one of them and reversing the original, the front edge of the inverted original and the rear edge of the original do not overlap, so skew and damage of the original and image blurring during scanning can be prevented, and good image reading is possible. Is possible.

The opening / closing timing of each branch gate is not uniformly determined, but may be changed to an optimum relationship depending on the device for carrying out the present invention.

[0093]

According to the document feeder of the present invention, by forming a plurality of switchback sub-conveyance paths,
When reading a double-sided original, the introduction port of the sub-conveyance path for guiding the original to the main conveyance path by switching back can be changed depending on whether the original size is large or small. That is, while the document is being read by the document reading unit
Opens the second branch by opening all branch gates.
Documents are fed to the feed path, and the
Select the most suitable branch gate among the various branch gates
When the trailing edge of the original passes the branch gate,
The document is switched by closing the branch gate.
Click to change the introduction port of the sub-transport path to lead to the main transport path
It is possible to As a result, the efficiency of document transportation can be improved and the transportation time can be shortened. Also,
When scanning both sides of one document, you can select the document reversal point that matches the document size. Therefore, when scanning the reverse side of the reversed document, the trailing edge of the document does not overlap the leading edge of the document, Lines and jams can be prevented.

Further, according to the document conveying apparatus of the present invention, the plurality of sub-conveying paths are joined to the same conveying path, whereby the conveying paths can be made common and the size can be reduced.

Further, according to the document conveying apparatus of the present invention, at each position of the second main conveying path where a plurality of sub-conveying paths are formed,
Since branch gates for guiding the switched-back document to the sub-conveyance path are respectively provided, whether the document read by the document reading unit is discharged from the second main conveyance path or guided to the sub-conveyance path. Can be selected.

Further, according to the document feeder of the present invention, while the document is being read by the document reading unit, all the branch gates are opened to convey the document to the second main conveyance path and read the read document. Depending on the length of the branch gate, the optimum branch gate is selected from the branch gates, and the branch gate is closed when the trailing edge of the original passes the branch gate. The efficiency can be improved and the transportation time can be shortened. Further, since the original reversal point that matches the original size can be selected when reading one side of a document, the rear end of the document and the leading end of the document do not overlap when the reverse side of the reversed document is read, It is possible to prevent the occurrence of skew and jam.

Further, according to the document feeder of the present invention, the detection switch for detecting the presence / absence of a document provided on the main conveyance path, the front end of the document provided on the main conveyance path, and the image reading timing are adjusted. And a PS roller for controlling the opening / closing timing of the branch gate according to the on / off timing of the detection switch, the rotation timing of the PS roller, and the timing of detecting the trailing edge of the document by the document reading unit. There is. That is, by detecting the accurate transport position of the document, the opening / closing timing of the branch gate and the document transport timing can be synchronized, and therefore the document transport operation and the document reversing operation can be accurately performed.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the basic configuration of a document feeder of the present invention mounted on a copying machine.

FIG. 2 is a cross-sectional view showing a conveyance path having a plurality of branch gates.

FIG. 3 is a flow chart showing a single-sided reading process in the document feeder of the present invention.

FIG. 4 is a flowchart showing a double-sided reading process in the document feeder of the present invention.

FIG. 5 is a flowchart showing a double-sided reading process in the document feeder of the present invention.

FIG. 6 is a control flowchart for double-sided scanning.

FIG. 7 is a control flowchart for double-sided scanning.

FIG. 8 is a timing chart showing the timing of controlling each branch gate depending on the document size.

FIG. 9 is an explanatory diagram showing the structure of a copying machine equipped with the document feeder of the present invention.

FIG. 10 is an operation flowchart of the copy mode of the copying machine.

[Explanation of symbols]

A Document feeder 1 Document tray 2 Document feeder 2a Pickup roller 2b separation board 4a First main transport path 4b Second main transport path 5 Document input sensor 6 PS roller 7 Document reading section 7a Platen glass 7b Document holding plate 13 Conveyor rollers 14 Paper ejection roller 15 Intermediate tray swing plate 16 Intermediate tray 17 Document output tray 18 Sub transport path 20 First Branch Gate 21 Second Branch Gate 22 Third Branch Gate 23 First sub-transport path 24 Second sub-transportation path 25 Third sub-transportation path 26 First reversal point 27 Second inversion point 28 Third Reversal Point

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-9-114143 (JP, A) JP-A-8-133551 (JP, A) JP-A-10-101257 (JP, A) JP-A-10- 69129 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G03G 15/00 107 G03G 15/00 106 B65H 29/58 B65H 85/00

Claims (2)

(57) [Claims] 1. A first main transport path for transporting a document fed from a document tray to a document reading unit, and a second main transport for transporting a document whose surface image information has been read by the document reading unit to a discharge tray. And a switchback for transporting the rear side of the original after the front side reading from the second main conveying path to the first main conveying path as the front end of the original for reading the back side in order to read the rear side of the original after the front side reading. and a sub-passage for use, the sub-passage is a plurality paths formed at each position of said made to correspond to each of a length corresponding to the type of original second main transport path, the plurality of sub-passage Each position of the second main conveyance path where the
To guide the original after switchback to the sub-transport path.
Each branch gate is equipped with a plurality of branch gates, and the originals after the front surface is scanned
Open the second main transport path when transporting to the tray side
At the same time, the sub-transport path is closed, and the
When scanning the back side,
The divergence gate located at the position corresponding to the length of the original document
Only the second main transport path and the sub-transport path open
After the opening and closing control, the document feeding direction is switched.
When the original is backed, the original is turned upside down,
From the original to the sub-transport path at the position corresponding to the length of the original.
Document feeder, characterized in that that. 2. The plurality of sub-conveyance paths are formed so as to merge as one sub-conveyance path until they merge with the first main conveyance path. The document feeder described.