JPH11263500A - Automatic document feeder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct diagonal carriage of a document at the time of reversing front surface and rear surface by once discharging the document to a copy placing part at a turning-around carrier part and switching it back. SOLUTION: A turning-around carrier part 42 to reverse front surface and rear surface of a document P against a document reading part 6 by switch back is provided on an upper part of a U shaped carrier part 41. Switching-back is carried out by carrying the document P in the opposite direction after it is discharged to a document placing part 2 once at the turning-around carrier part 42. A pair of document guides 202 to carry out width arrangement of the document P is provided on the document placing part 2. A tapered part 202a to guide the document P once discharged to an upper end part in the height direction of the document guide 202 to the inside of the document guide 202 is formed. Diagonal carriage is corrected by certainly guiding the document P once discharged by the tapered part 202a to the inside of the document guide part 202 and guiding the document P after switch back by this document guide 202.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic document feeder used for a copying machine, a facsimile machine, and the like. In particular, the present invention relates to an automatic document feeder for reading information on both sides of a document by switching the direction of document transport. This system is called a switchback system.) The present invention relates to an automatic document feeder that reverses the front and back of a document and automatically conveys each side to a document reading unit.

[0002]

2. Description of the Related Art Conventionally, as disclosed in Japanese Patent Application Laid-Open No. 7-64359, for example,
2. Description of the Related Art There is known an automatic document feeder that reverses the front and back surfaces of a document by a switchback method and transports the document to a document reading unit.

In this automatic document reading apparatus, a document supply tray and a document discharge tray are arranged up and down, and switchback of the document is performed by temporarily discharging the document to the document discharge tray and then transporting the document in the reverse direction. It is done in.

[0004]

In the conventional automatic document feeder described above, the leading end of the document is temporarily discharged to a document discharge tray which does not have a document guide or the like for regulating the width of the document. Since the switchback is performed, when the document is discharged to the document discharge tray or when the discharged document is reversely transported, the document may be skewed. It is conceivable to provide a document guide on the document discharge tray.However, since the document discharge tray is arranged in two stages below the document supply tray, in this method, the width of the document guide is used for switchback during double-sided reading. Adjustment is difficult and impractical.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an automatic document feeder capable of suitably correcting the skewed conveyance of a document during switchback.

[0006]

According to the present invention, the original is placed on the original transport path between an original placing section and an original reading section for reading an original fed from the original placing section. An automatic document feeder provided with a fold conveyance section for reversing and feeding the original in a conveying direction after reversing and feeding the original to a predetermined position on the original side, and re-feeding the original to the original conveyance path. A part of the document is configured to be able to be discharged to the document placing portion, and a leading end portion of the document discharged from the folding transport portion is switched to a proper position on the bottom surface of the document placing portion to switch a transport direction. It is discharged to the inside of a pair of document guides that are erected to prevent oblique sheet feeding. (Claim 1).

According to the above configuration, for example, when the reading surface of the original fed from the original placing portion with respect to the original reading portion is reversed, the original is provided between the original placing portion and the original reading portion. The document is conveyed from the original transport path to the turn-back transport section, the front and back of the transport direction are switched at the return transport section, and the sheet is again transported to the original transport path to be turned upside down.

The document conveyed to the folding conveyance section is bent upward in a U-shape and conveyed to the document mounting section side, and after its leading end portion is conveyed to a predetermined position of the document mounting section to be discharged, The document is conveyed in the reverse direction and returned to the document conveying path.

The leading end portion of the document discharged to the document placing portion is located inside a pair of document guides provided upright on the bottom surface of the document placing portion (that is, when there is an unfed document on the document placing portion). Is ejected (to be stacked on the unfed original), thereby correcting the skewed conveyance in the switchback of the original.

According to the present invention, in the above-mentioned automatic document feeder, at least a part of a leading end portion of a document discharged from a document discharge port of a folding conveyance section is guided into the document guide at an upper end portion of the pair of document guides. In this case, a divergent tapered portion is formed (claim 2).

According to the above arrangement, the original discharged from the folding conveyance section to the original placing section is guided by the tapered portion formed at the upper end of the original guide, so that the original is reliably inserted inside the pair of original guides. Is discharged.

Further, according to the present invention, in the above-mentioned automatic document feeder, at one end of at least one of the document guides facing the document discharge port of the return transport section, a document placement section for the document discharged from the return transport section is provided. The projection is provided with a regulating piece that regulates the falling of the surface to the bottom surface.

According to the above configuration, when there is an unfed original in the original placing portion, a portion of the original placing portion facing the original feed opening includes:
A gap is temporarily created between the discharged document and the unfed document on which the document is stacked due to the switchback due to the restriction piece provided on at least one of the document guides. No contact. As a result, when the temporarily discharged original is conveyed in the reverse direction, the unsupplied original does not come into contact with the original to prevent the conveyance.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a configuration diagram of a main portion showing an embodiment of an automatic document feeder according to the present invention.

The automatic document feeder 1 has a document placing portion 2 on which a document is placed and a document discharging portion 3 for discharging the document, which are provided in two upper and lower stages. The document is read at a front end (left side in FIG. 1). A document transport unit 4 for transporting a document to perform the document is provided. In the following description, for convenience, the side on which the original is fed (the left side in FIG. 1) by the original placing section 2 is the “front side”, and the side where the original is discharged by the original discharge section 3 (the right side in FIG. 1).
Is called "rear side".

The automatic document feeder 1 automatically feeds the documents stacked on the document placing portion 2 one by one from the top. Hereinafter, this document feeding method is referred to as “document pick-up method”. In addition, the automatic document feeder 1 not only feeds a document for reading a single-sided document (hereinafter, referred to as a single-sided document reading) but also reads a document for reading a double-sided document (hereinafter, referred to as a double-sided document reading). Feeding is also possible. For this reason, the document transport unit 4 performs a U-shaped transport unit 41 for transporting a document in a U-shape from the document placement unit 2 to the document discharge unit 3 when performing one-sided document reading, and performs double-sided document reading. A folding conveyance unit 42 for turning the original upside down by a switchback method at the time, and a return conveyance unit 43 for returning the original after scanning the original to the folding conveyance unit 42 to reverse the original when performing double-sided original reading. Have been.

The automatic document feeder 1 is configured so that a plurality of documents can be discharged to the document discharge unit 3 in the same page order in either one-sided document reading or two-sided document reading. That is, in the present embodiment, since the original document pick-up system is adopted, as shown in FIG. 2, after the original document P fed from the original document placement unit 2 is switched back by the folding conveyance unit 42 (ie, , After flipping to the “back side”),
The document P is conveyed to the document reading unit 6 to read the image data of the “back side”. Then, the document P is returned to the return conveyance unit 42 again by the return conveyance unit 43, and the document P is further returned to the “front surface” by the return conveyance unit 42. Then, the document is conveyed to the document reading section 6 to read the image data of the "front surface".

In FIG. 2, a thick line portion of the document P indicates the "back side" of the document, and a triangular mark indicates an upper side of the "front side" of the document. In the drawing, even if the document P placed on the document placing portion 2 is upside down on the paper surface, the order of the pages after the ejection is not affected.

The original placing section 2 has an original tray 20 made of resin.
1 and is detachably attached to the document feed port 101 with its rear end inclined upward. Document tray 20
A pair of document guides 202 are provided upright on the front end of the bottom surface of the document 1. The document guide 202 is provided on the document tray 201.
In addition to aligning the width of the original placed on the original, the oblique feeding of the original at the time of feeding is prevented. Both manuscript guide 20
As shown in FIGS. 3 and 4, reference numeral 2 is provided so as to move in a mirror image relationship with the center line L of the document tray 201 in conjunction with each other.

The document guide 202 is formed of a rectangular plate, and has an upper end bent outward at a predetermined angle to form a divergent tapered portion 202a. A bar-shaped protruding piece 202b protrudes from the inner surface of the front end of the document guide 202 facing the document feed port 101 (see FIG. 4). When the document is switched back by the folding conveyance unit 42 (when the document conveyance direction is reversed), the tapered portion 202a partially discharges the document as described later. The document is temporarily discharged from the exit 102 to the document tray 201, and the leading end of the discharged document is guided to the inside of the pair of document guides 202 (that is, the unfeeded document placed on the document placing portion 2). (Guide on the original P).

The protruding piece 202b is
This is for setting the drop position of the document temporarily discharged on the document tray 201 to a position separated from the document feed port 101. That is, the document P temporarily discharged onto the unfed document P is prevented from overlapping near the document feed port 101.

The document P temporarily discharged during switchback of document transport is guided into the pair of document guides 202 by oblique sheet feeding when the document P is re-fed in the reverse direction. This is because the width is adjusted by the document guide 202 to perform correction. To increase the reliability of the skew correction, a guide for skew correction may be provided near the document discharge port 102. However, this method is different from the document guide 202 depending on the size of the fed document. Since it is necessary to adjust the width of the guide and there remains a problem in terms of operability, in the present embodiment, the document guide 202 of the document placing section 2 is also used as a guide for oblique correction. By also using the document guide 202 in this manner, the guide for oblique correction does not protrude from the upper surface of the automatic document feeder 1, and the appearance of the apparatus is not spoiled.

The reason why the position where the document P is dropped on the document tray 201 is separated from the document feed port 101 is that the document P for switchback is temporarily discharged onto the unfed document P. Therefore, when the original P is conveyed in the reverse direction, the unsupplied original P does not obstruct the conveyance of the original P after switchback.

As described above, the protruding piece 202b is used to regulate the position where the temporarily discharged document P is dropped onto the document tray 201, and is not limited to a rod-like shape. Any shape can be adopted as long as the shape is acceptable. The position of the document guide 202 protruding in the height direction can be appropriately selected so as to achieve the above object. For example, it may be provided at a predetermined height position of the document guide 202 so that the protrusion 202b can also be used as a member for regulating the number of documents that can be placed on the document tray 201. The skew correction and the prevention of the interruption of the feeding due to the temporarily discharged original will be described in detail in the description of the operation of the automatic original feeder 2.

Returning to FIG. 1, a separation feeding section 21 is provided at the leading end of the document placing section 2. The separation feeding unit 21 includes a document set sensor S1, a paper feed roller 211, a separation roller 212
And a forward feed roller 213.

The document set sensor S1 is connected to the document tray 20.
1 to detect the presence of the original P on the original tray 20.
1 is provided at the bottom of the tip. Forward feed roller 213
Is for picking up a document P, and is provided at a position above the leading end of the document tray so as to be able to move up and down. The forward feed roller 213 is switched between an ascending position and a descending position by a sheet feeding solenoid (not shown). The paper feed roller 211 and the separation roller 212 separate only the uppermost document P while separating the document P picked up by the forward feed roller 213.
And is arranged at the front end of the document tray 201. The paper feed roller 211 is driven to rotate by using a paper feed motor (not shown) as a drive source, and the separation roller 212 rotates following the paper feed roller 211. Note that the paper feed roller 211
In FIG. 1, a rotational driving force in one direction of a paper feed motor is transmitted by a paper feed clutch (not shown), and only a clockwise rotation in FIG. 1 (hereinafter, a rotation in this direction is referred to as a forward rotation) is performed. Has become.

The U-shaped transport section 41 of the document transport section 4 includes a first transport path 411 to a fifth transport path 41 constituting a U-shaped transport path.
5, feed sensor S2, timing sensor S3, registration roller pair 416, upper transport roller pair 417, lower transport roller pair 418, intermediate roller pair 419, and discharge roller pair 4
20.

First transport path 411 and second transport path 412
Extends substantially linearly downstream of the feed roller 211 and the separation roller 212, a feed sensor S <b> 2 is provided at the base end of the first transport path 411, and the first transport path 411 and the second transport path The registration roller pair 416 is disposed between the pair of registration rollers 416. A document reading position P3 for reading the document P is provided below the second conveyance path 412, and the fourth conveyance path 414 is arranged so as to pass through the document reading position P3. Then, the fourth transport path 414 and the second transport path 212
A third conveyance path 413 curved in a C-shape is disposed between the first conveyance path 414 and the fifth conveyance path 415 between the fourth conveyance path 414 and the document discharge unit 3. Further, a timing sensor S3 is provided at a base end of the fourth conveyance path 414.

The second transport path 412 and the third transport path 41
3, the upper transport roller pair 417, at the connection positions of the respective transport paths between the third transport path 413 and the fourth transport path 414 and between the fourth transport path 414 and the fifth transport path 415. A lower transport roller pair 418 and an intermediate roller pair 419 are provided, and a discharge roller pair 420 is provided at the end position of the fifth transport path 415.
Are arranged.

The feed sensor S 2 detects that the document P has been fed from the document placing section 2. The detection signal of the feed sensor S2 is transmitted to a registration roller pair 41 described later.
6 is used to control the drive start timing.

The registration roller pair 416 corrects the oblique feeding of the document P fed from the document placing section 2.
The registration roller pair 416 is also driven by a sheet feeding motor that drives the sheet feeding roller 211 so that the rotational driving force in the other direction of the sheet feeding motor is transmitted to the registration roller pair 416 via the above-described sheet feeding clutch. Has become. Therefore, the registration roller pair 416 is rotated only in the counterclockwise direction in FIG. 1 (hereinafter, this direction is referred to as a reverse rotation direction), that is, only in the direction of transporting the document P to the downstream side.

The upper transport roller pair 417 and the lower transport roller pair 418 apply a transport force to the original P in the transport path and transport the original P to the original reading position P3. The upper transport roller pair 417 also functions as a registration roller pair for correcting the inclination of the original P when the original P is transported from the return transport unit 42.

The intermediate roller pair 419 applies a conveying force to the original P after reading the original to discharge the original P to the original discharge unit 3 or return the original P to the first conveying path 411. The document P after the reading is completed is discharged to the document discharge unit 3.

Upper transport roller pair 417, lower transport roller pair 4
18, the intermediate roller pair 419 and the discharge roller pair 420
It is driven by a transport motor (not shown) different from the paper feed motor. The upper transport roller pair 417, the lower transport roller pair 418, and the intermediate roller pair 419 are rotated in the reverse direction by the transport motor, and the discharge roller pair 420 is rotated in the forward direction by the transport motor.

The document reading position P on the fourth conveyance path 414
A contact glass 7 is provided below the contact glass 3, and a document reading unit 6 provided with an image sensor such as a CCD line sensor is provided below the contact glass 7.

The folding transport section 42 is provided above the U-shaped transport section 41. The folding transport section 42 reverses the original reading surface by reversing the transport direction of the original by the switchback method. That is, the U-shaped transport unit 41
The document P is transported from the first transport path 411 to the turn-back transport section 42, and the transport direction of the document P is reversed and the U-shaped transport path 41
Of the document P, the surface of the document P facing the outside of the transport path of the U-shaped transport unit 41 is turned over, thereby inverting the document reading surface facing the document reading unit 6. It is.

The return transport section 42 includes a sixth transport path 421-
Eighth transport path 423, reversing roller 424, and reversing roller 42
5 is provided.

The sixth transport path 421 guides the document P from the transport path of the U-shaped transport section 41 to a seventh transport path 422 (a return transport path; hereinafter, referred to as a return transport path 422). The 8-conveyance path 423 guides the document P, which has been switched back in the return conveyance path 422, to the conveyance path of the U-shaped conveyance section 41 again. In addition, the folding conveyance path 422 is used to switch the original P back to the U-shaped conveying section 4.
This is an evacuation path for evacuation from one transport path. The document P is conveyed to the return conveyance path 422, and is temporarily stopped. Then, the document P is reversed, whereby the document P is switched back.

In the present embodiment, the U-shaped transport section 41
Of the folding conveyance path 42 provided adjacent to the upper surface of the apparatus.
By omitting a part of 2, the size of the apparatus is reduced. In other words, when the document P is bent upward in a U-shape from the U-shaped transport unit 41 and once retracted to the document placing unit 2 side, as shown in FIG. 422 and the remaining leading end is
By discharging the document from the document feeder 02 to the document placement unit 2, a part of the folded conveyance path 422 (see the dotted line in FIG. 5) arranged on the upper surface of the apparatus is omitted.

The sixth transport path 421 branches off from the base end of the second transport path 412 and is formed diagonally upward. An eighth transport path 423 is formed at the distal end and extends diagonally downward and leftward. I have. The tip of the eighth transport path 423 joins the tip of the second transport path 412. Folded transport path 422
Is formed so as to be curved toward the original placing section 2 side continuously to the tip of the sixth transport path 421.

The second transport path 412 and the sixth transport path 42
The second transport path 412 and the sixth transport path 42
1 and a reversing branch lever 51 for switching between
A reversing sensor S4 for detecting that the document P is being conveyed to the folding conveyance section 42 is provided at an appropriate position on the conveyance path 421.

The sixth transport path 421 and the eighth transport path 4
A reversing roller 424 and a reversing roller 425 are disposed at a connection position between the reversing conveyance path 422 and the reversing roller 424 so as to be able to approach and separate from each other. In the present embodiment, the reversing roller 425 is disposed so as to be switchable between a pressure contact position with respect to the reversing roller 424 and a release position for releasing the pressure contact, and the set position is switched by a not-shown reversing pressure solenoid. ing. When the roller is set to the pressure contact position, the reversing roller 425
24, the document P can be transported to the return transport path 422 side or the eighth transport path 423 side. When the document P is set to the release position, the nip is released by the reversing roller 424 and the reversing roller 425 of the document P, and the skew correction of the document P after the switchback can be performed.

The reversing roller 424 and the reversing roller 425 are
The switchback of the document P is performed. The reversing roller 424 is driven to rotate by the above-described paper feeding motor. The driving force of the paper feeding motor is transmitted to the reversing roller 424 without going through the paper feeding clutch, and the reversing roller 424 is driven to rotate in both forward and reverse directions according to the driving of the paper feeding motor.

The return transport section 43 is formed of a curved transport path, is provided at the base end of the fifth transport path 415, and has a leading end joined to a distal end of the first transport path 411. A discharge branch lever 52 for switching between the fifth transport path 415 and the return transport path 43 is provided at a branch position between the fifth transport path 415 and the return transport path 43.

FIG. 6 is a block diagram showing an embodiment of a control system of the automatic document feeder. In FIG.
The same members as those shown in FIG. The control unit 8 centrally controls the document feeding process in the document reading operation, and is configured by, for example, a microcomputer. The control unit 8 includes a user's instruction input via input means 16 such as a switch and a numeric keypad provided on an operation panel (not shown), and a document set sensor S1, a feed sensor S2, a timing sensor S3, and a reversing sensor S4. Paper feed motor 9, transport motor 10, paper feed clutch 11, registration clutch 12, paper feed solenoid 13, reverse pressure solenoid 14, reverse solenoid 15, and discharge solenoid 16 based on the detection signals from the respective sensors
The automatic feeding of the original is performed by controlling the driving of each of the driving members.

The paper feed motor 9 is a drive source for the paper feed roller 211, the advance roller 213, the pair of registration rollers 416, and the reversing roller 424. That is, the paper feed motor 9
It is a driving source for feeding the original P placed on the original placing section 2 to the transport path and for performing switchback of the original P transported to the return transport section 42. The paper feed clutch 11 is formed of a one-way clutch, and transmits the driving force (forward rotation drive) of the paper feed motor 9 to the paper feed roller 211 and the forward feed roller 213. The registration clutch 12 is formed of a one-way clutch, and transmits the driving force (reverse rotation drive) of the sheet feeding motor 9 to the registration roller pair 416.

When the paper feed motor 9 is driven to rotate forward, the driving force is transmitted to the paper feed roller 211 and the forward feed roller 213 via the paper feed clutch 11, and when the paper feed motor 9 is driven to rotate in the reverse direction, the driving force is transmitted. The force is transmitted to the registration roller pair 416 via the registration clutch 12. Further, the driving force of the sheet feeding motor 9 is directly transmitted to the reversing roller 424, and the reversing roller 424 rotates in both forward and reverse directions according to the forward and reverse rotation of the sheet feeding motor 9.

The transport motor 10 includes an upper transport roller pair 41
7, a driving source for the lower conveying roller pair 418, the intermediate roller pair 419, and the discharge roller pair 420.

The paper feeding solenoid 13 includes a forward feed roller 21
Reference numeral 3 denotes a switching member for switching between a raised position and a lowered position (document contact position). The paper feeding solenoid 13 is, for example, “O
N ", the forward feed roller 213 is at the lowered position,
When it is set to “OFF”, the advance roller 213 is at the raised position.

The reversing pressure solenoid 14 has a reversing roller 42
5 is a switching member for switching between a pressing position to the reversing roller 424 and a releasing position. For example, when the reversing pressure solenoid 14 is set to “ON”, the reversing roller 425 is at the pressure contact position, and when the reversing pressure solenoid 14 is “OFF”, the reversing roller 425 is at the detached position.

The reversing solenoid 15 and the discharging solenoid 16 are switching members for the reversing branch lever 51 and the discharging branch lever 52, respectively. For example, when the reversing solenoid 15 is turned “ON”, the sixth transport path 421 is “open” (the second transport path 412 is “closed”), and when the reverse solenoid 15 is “OFF”, the sixth transport path 421 is “closed”. (The second transport path 412 is “open”). For example, when the discharge solenoid 16 is set to “ON”, the return transport unit 43 is “open” (the fifth transport path 415 is “closed”), and when the discharge solenoid 16 is “OFF”, the return transport unit 43 is “closed”. (The fifth transport path 415 is “open”.)

Next, a description will be given of the document transport control of the automatic document feeder 1 in reading a double-sided document according to the document transport sequence shown in FIGS.

The original placing section 2 is detected by the original set sensor S1.
Is detected (YES in step S1), the count value n of the number of times of document conveyance is set to “0” (step S3), and the paper feed clutch 1
1 and the paper feed solenoid 13 are each turned “ON”,
The discharge solenoid 16 is turned on (step S
5). That is, the return conveyance unit 43 is connected to the U-shaped conveyance unit 41, the forward feed roller 213 is lowered to the position where the original P abuts, and the transmission direction of the driving force of the paper feed motor 9 is changed to the feed roller 211 and the forward direction. It is set on the feed roller 213 side.

Subsequently, the paper feeding motor 9 is driven to rotate forward, and the feeding of the uppermost original P of the original P placed on the original placing section 2 to the original transport section 4 is started (step S7). ). When the document P fed to the document transport unit 4 is detected by the feed sensor S2 (YES in step S9), the sheet feeding motor 9 is stopped at a predetermined timing T1 based on the detection signal, and the sheet feeding clutch is stopped. 11 is turned "OFF" (steps S11, S13). That is, the conveyance of the document P is stopped at a predetermined timing when the leading end of the document P is nipped by the registration roller pair 416, and the oblique conveyance of the document P is corrected.

Subsequently, after a lapse of a predetermined time T2 after the stop of the sheet feeding motor 9 (step S15), the reversing pressure solenoid 14 and the reversing solenoid 15 are each turned "ON". That is, while the folding conveyance section 42 is connected to the U-shaped conveyance section 41, the reversing roller 42
5 are pressed (step S17). Subsequently, the paper feed motor 9 is driven to rotate in the reverse direction (step S19), and the conveyance of the document P is restarted by the registration roller pair 416.

Document P that has passed through registration roller pair 416
Is guided to the sixth transport path 421 by the reverse branch lever 51, and is transported to the return transport section 42. Then, when the reversing sensor S4 detects that the document P has been conveyed to the sixth conveying path 421 (YES in step S21), after a lapse of a predetermined time T3 from the detection timing of the reversing sensor S4, the sheet feeding motor 9 outputs “ OFF ", and the reversing pressure solenoid 14 is turned" OFF "(step S2).
3, S25). During the predetermined time T3, the original P is fed back by the reversing roller 424 and the reversing roller
And the predetermined position of the rear end of the document P is
This is the time until the sheet is nipped by 24 and the reversing roller 425.

The original P is conveyed to the return conveying path 422 during a predetermined time T3 from the detection timing of the reversing sensor S4, as shown in FIG.
2 is discharged to the upper surface of the cover 214 of the separation feeding unit 21,
The document P is conveyed onto the unfed document P stacked on the document placing portion 2. As shown in FIG. 10, the leading end of the discharged document P pushed out from the document discharge port 102 to the document placing portion 2 is easily inserted into the document guide 202 by the two tapered portions 202a of the pair of document guides 202. Unguided document P
It is laminated on.

Then, the rear end of the document P is
4 and a predetermined position before the reversing roller 425, the pressure contact of the reversing roller 425 with the reversing roller 424 is released, and the rear end of the document P becomes free.
When the document P is discharged obliquely from the document discharge port 102,
Is corrected by the pair of document guides 202, and the correction extends to the rear end of the document P, so that the tilt of the entire document P can be surely corrected. In addition, even when the document P is re-conveyed from the document discharge port 102 due to switchback, the leading end of the document P (the rear end of the document P in the conveying direction) is guided by the pair of document guides 202, Transport is prevented.

Subsequently, after a lapse of a predetermined time T4 since the feed motor 9 is turned off, the reverse pressure solenoid 14
Becomes “ON”, and the reversing roller 425 becomes the reversing roller 424.
(Steps S27 and S29), and the feed motor 9
Is driven in the normal direction to start the reverse conveyance of the document P (step S31).

The feed motor 9 is temporarily stopped at a predetermined timing T5 from the start of the normal rotation drive (steps S33, S3).
35) After that, normal rotation driving is performed again at a predetermined timing T6. At the same time, the transport motor 10 is driven to rotate in the reverse direction (steps S37 and S39). That is, the conveyance of the document P to the document reading position P3 by the upper conveyance roller pair 417 to the intermediate roller pair 419 is started.

As shown in FIG. 11, the paper feed motor 9 is temporarily stopped at a predetermined timing T5 at the rear end of the document P (the front end in the reverse conveyance direction. The “leading end” and the rear side of P are referred to as “rear end”. The upper conveying roller pair 417 nips the upper conveying roller pair 417 to correct the skewed conveyance of the document P after switchback, thereby ensuring the skew correction. This is to enhance the character. That is,
The upper transport roller pair 41 for the original P after switchback
7 functions as a registration roller pair.

As described above, the upper transport roller pair 417 functions as a registration roller pair because oblique transport may occur during switchback even if the document P is obliquely corrected by the registration roller pair 416. In consideration of the case where the skew conveyance is not sufficiently corrected even by the document guide 202, the skew correction is surely performed by the roller pair when the document P is conveyed from the folding conveyance section 42 to the U-shaped conveyance section 41. .

Note that a pair of registration rollers dedicated to the document P after switchback may be provided on the seventh transport path 422, but in this embodiment, the upper transport roller pair 417 is connected to the third transport path 413. And the seventh transport path 422, the upper transport roller pair 417 is also used as a registration roller pair, thereby simplifying the structure. However, the upper conveying path roller pair 417 may be considered as a pair of registration rollers for performing the diagonal correction of the document P after the switchback, and the pair of registration rollers may also be used as a pair of conveying rollers in the single-sided document conveyance of the U-shaped conveyance unit 41. .

Subsequently, when a predetermined time T7 elapses after the conveyance of the document P to the image reading position P3 by the upper conveyance roller pair 417 and the lower conveyance roller pair 418 has been started (step S41), the paper feed motor 9 is set to ""OFF" and the reversing pressure solenoid 14 is turned "OFF" (step S43). That is, while the driving of the reversing roller 424 is stopped, the reversing roller 42 of the reversing roller 425 is stopped.
4 is released.

After the original P is conveyed by the predetermined amount by the upper conveying roller pair 417, the reversing roller 424, and the reversing roller 425, the reversing roller 424 and the reversing roller 42
The stop of the conveyance of the document P by 5 and the release of the press-contact of the reversing roller 425 are performed when the document P is nipped by the upper conveying roller pair 417, and the press-contact of the reversing roller 425 to the reversing roller 424 is released. However, if the document P is transported to the third transport path 413 only by the upper transport roller pair 417, the trailing end of the document P is free, and there is a risk of oblique transport. This is because the reliability of the oblique correction decreases. In the present embodiment, even after the skew correction, the original P is conveyed by the upper conveyance roller pair 417, the reversing roller 424, and the reversing roller 425 by a predetermined amount, thereby increasing the reliability of the skew correction processing.

Subsequently, when the leading edge of the document P is detected by the timing sensor S3 (YES in step S45),
The count value n of the number of times of document conveyance is incremented by 1 (step S47), and the count value n is further increased to “2”.
Is determined (step S49).
If n = 2 (YES in step S49), this is the second conveyance (that is, conveyance for reading the “front side” of the original), so the discharge solenoid 16 is turned “OFF” in order to discharge the original P after reading the original. (Step S51), and the return conveyance path 43 is separated from the U-shaped conveyance path 41. On the other hand, if n <2 (YES in step S49), it is the first transport (that is, transport for reading the “back side” document), and thus the document P is folded back after the document is read.
Step S51 is skipped in order to return to 2, and "ON" of the discharge solenoid 16 is continued. This time, "Back"
Step S51 is skipped because the transport is for reading the original.

Subsequently, the "back side" of the document P is read by the document reading section 6 at a predetermined timing T8 based on the detection signal of the timing sensor S3 (step S5).
3, S55).

When the reading of the document P is completed, it is determined whether or not the count value n is "2" (step S).
57), if n <2 (NO in step S57), the document P is returned to the return transport unit 42 by the return transport unit 43 in order to read the “front side”, and the process returns to step S17.
On the other hand, if n = 2 (YES in step S57), the reading of the document P on both sides is completed and the document P is discharged to the document discharge unit 3, so it is determined whether or not the document P remains on the document placing unit 2. If it is determined (step S59) that the original P remains on the original placing section 2 (NO in step S59), the process returns to step S3, where the double-side reading process of the next original P is performed. If there is no original P left (YE in step S59)
S), the double-sided document reading process ends.

As described above, after the document P is once discharged to the document placing section 2, the folding transport section 42 for switching back the document P is provided, and the document P temporarily discharged to the document placing section 2 is provided. Since the document P is guided to the inside of the document guide 202, the leading end portion of the document P is guided by the document guide 202 when the document P is temporarily discharged or when the document P is reversely conveyed after switchback, so that the oblique conveyance is suitably prevented. Can be.

A tapered portion 202a for guiding the leading end of the document P temporarily discharged to the upper end of the document guide 202
Is formed, the leading end of the document P can be reliably guided inside the document guide 202. Further, since the protruding piece 202b is protruded at an appropriate position on the front side of the document guide 202, even when the document P for switchback is stacked and discharged on the unfed document P of the document placing portion 2, , The original P
When the original P is not conveyed in the reverse direction, the original P is not contacted with the original P to cause reverse conveyance obstruction, and the switchback can be performed smoothly.

In the above embodiment, the original placing section 2
Although the method of placing the original P upward and feeding the original P from the upper side has been described, the present invention temporarily discharges the leading end of the original P to the original placing section 2 at the time of switchback. Then, the method can be applied to the method of placing the document P on the document placing section 2 (upward or downward) and the order of feeding the document P (order of trade-in or trade-in).

[0072]

As described above, according to the present invention,
The original conveyed from the original placing section is conveyed again to the original placing section via the original turning-back transport section, and the leading end is discharged to the original placing section. An automatic document feeder that performs switchback,
Since the leading end of the document discharged from the folding conveyance unit to the document placement unit is discharged to the inside of a pair of document guides that are erected at appropriate positions on the bottom surface of the document placement unit, the document is returned by the folding conveyance unit. The oblique conveyance at the time of the switchback can be suitably corrected by the document guide.

Further, since a divergent tapered portion for guiding at least a part of the leading end portion of the document temporarily discharged from the folding conveyance section into the document guide is formed at the upper end portion of the pair of document guides, the temporarily discharged portion is formed. Original can be reliably ejected to the inside of the pair of original guides, and the reliability of the skew correction is increased.

Further, at one end of at least one of the original guides facing the original discharge opening of the return conveyance section, a restricting piece for restricting the original discharged from the return conveyance section from dropping to the bottom surface of the original mounting section is projected. Therefore, even if a document for switchback is ejected over an unfed document in the document tray, the unfed document is switched back near the document feed port of the document tray. The document does not come in contact with the document.

[Brief description of the drawings]

FIG. 1 is a main part configuration diagram showing an embodiment of an automatic document feeder according to the present invention.

FIG. 2 is a diagram illustrating document conveyance control in double-sided document reading in the document pick-up mode.

FIG. 3 is a view of a document placing section viewed from the rear side.

FIG. 4 is a perspective view of a main part showing a structure of a document guide.

FIG. 5 is a diagram illustrating a state in which a document is transported to a return transport unit.

FIG. 6 is a block diagram showing an embodiment of a control system of the automatic document feeder according to the present invention.

FIG. 7 is a diagram illustrating a sequence of a document conveying process for reading a double-sided document.

FIG. 8 is a diagram illustrating a sequence of a document conveying process for reading a double-sided document.

FIG. 9 is a diagram illustrating a state in which a document is transported in a switchback process in the folding transport unit.

FIG. 10 is an essential part perspective view showing a state in which a document is discharged onto an unfed document in a document placing portion by switchback processing.

FIG. 11 is a diagram illustrating a state in which a document after switchback is nipped by an upper conveying roller pair;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 automatic document feeder 101 document feed port 102 document discharge port 2 document placing section 201 document tray 202 document guide 202 a taper section 202 b protrusion (restriction piece) 21 separation feed section 3 document discharge section 4 document transport section 41 U Character feeder 42 Folded feeder 43 Return feeder 51 Reverse branch lever 52 Discharge branch lever 6 Document reading unit 7 Contact glass 8 Control unit 9 Feed motor 10 Feed motor 11 Feed clutch 12 Registration clutch 13 Feed solenoid 14 Feed reverse Pressure solenoid 15 Reverse solenoid 16 Discharge solenoid 17 Input means

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hiroshi Aso 1-2-28 Tamatsukuri, Chuo-ku, Osaka-shi Inside Mita Kogyo Co., Ltd. (72) Inventor Shigeo Kurato 1-2-28 Tatamazo, Chuo-ku, Osaka-shi Inside the Industrial Co., Ltd. (72) Kuniaki Shinishi, 1-2-28 Tamatsukuri, Chuo-ku, Osaka-shi Mita Kogyo Co., Ltd. (72) Inventor Masaki Exit 1-2-28 Tamatsukuri, Chuo-ku, Osaka-Mita Industrial Co., Ltd.

Claims (3)

[Claims] An original is fed upside down to a predetermined position on the original placement section side on an original transport path between an original placement section and an original reading section for reading an original fed from the original placement section. An automatic document feeder provided with a return transport unit for re-feeding the document in the document transport path by reversing the direction of transport of the document after transporting the document, wherein the return transport unit includes a part of the document. Can be ejected to the original placing section, and the leading end of the original ejected from the folding transport section for switching the transport direction is provided at an appropriate position on the bottom of the original placing section to prevent oblique sheet feeding. An automatic document feeder, which is ejected to the inside of a pair of document guides. 2. The automatic document feeder according to claim 1, wherein at least a part of a leading end portion of a document discharged from a document discharge port of a folding conveyance unit is guided into the document guide at an upper end portion of the pair of document guides. An automatic document feeder, wherein a divergent taper portion is formed. 3. The automatic document feeder according to claim 1, wherein at least one of the original guides has a document loading portion on one end of the folding transport portion facing the document discharge port, the document being ejected from the folding transport portion. An automatic document feeder, characterized in that a restricting piece for restricting a drop to a bottom surface of the placing portion is protruded.