JP2695686B2 - Document feeder - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document feeding apparatus provided in a copying machine for sequentially feeding a plurality of sheet-shaped documents onto a document reading surface for reading exposure.

2. Description of the Related Art Conventionally, copiers have tended to be equipped with a document feeder which automatically and sequentially feeds a plurality of sheet-shaped documents onto a document reading surface for the convenience of an operator. . The document to be copied is placed on a placing member, and is sequentially fed, for example, from the bottom in the stacking direction. On the original reading surface, an original image is sequentially fed toward the inside of the machine by a transport belt, read and exposed by, for example, an optical reading unit, and cooperated with a copying machine to perform double-sided or single-sided copying. And so on.

In order to make the front and back surfaces of the fed document face the document reading surface, for example, reversing means is provided between the placing member and the document reading surface. The reversing means,
It is formed by branching into a first transport path and a second transport path between the placing member and the document reading surface. In the case of single-sided copying, the original fed from the placing member is inverted via the first transport path, and is transported with the original image on one side facing the original reading surface. On the other hand, at the time of duplex copying, the original fed from the placing member is once transported to the first transport path,
Thereafter, the conveyance direction in the first conveyance path is reversed, the sheet is guided to the second conveyance path, and then conveyed onto the document placing surface. Thus, the document placed on the placing member is conveyed without reversing the front and back surfaces, that is, the lower side faces the document reading surface. After reading and exposing the lower side surface, the original that has been turned over and returned is transported again through the first transport path and the second transport path, so that the remaining surface, that is, the upper side surface is read. .

In this manner, in a configuration in which a plurality of sheet-shaped originals are sequentially fed onto the original reading surface, the timing at which the subsequent original is fed after the previously fed original is determined for the entire copy. It greatly affects the time you spend. Therefore, while the previously fed document stops on the document reading surface and is read and exposed by the optical reading unit,
A configuration is conceivable in which the time required to feed a plurality of documents onto the document reading surface is reduced by feeding the subsequent documents in advance and waiting for the document to approach the preceding document. As described above, a configuration in which a subsequent document is fed in advance and put on standby is called a so-called preliminary sheet feeding, and an example thereof is disclosed in JP-A-62-12533. According to the disclosed configuration, the succeeding document that has been pre-fed is waiting just before the transparent plate forming the document reading surface.

Problems to be Solved by the Invention For example, in the preliminary sheet feeding for duplex copying, as described above, the document fed from the placing member is reversed once after passing through the first conveyance path and then moved to the second sheet. You have to go through the transport route. Therefore, in order to complete the preliminary feeding, regardless of the size of the original having a relatively large dimension along the feeding direction, the path length of the first transport path must be secured long enough to allow the dimension. No. That is, the reversing means tends to be large. In other words, if the size of the reversing means is reduced, it is not possible to execute the preliminary sheet feeding for a document having a large size. In addition, an increase in the path length due to an increase in the size of the reversing means leads to an increase in the document transport time. In particular, when the original is conveyed only to the first conveyance path in one-sided copying, the time is remarkably increased. As described above, there is a restriction in reducing the time spent for transporting between a plurality of documents, and as a result, it is not possible to shorten the copying time.

Therefore, an object of the present invention is to reduce the size of the reversing means with a simple configuration, and to reliably perform preliminary sheet feeding.
An object of the present invention is to provide a document feeder capable of shortening a copying time.

Means for Solving the Problems A document feeder according to the present invention feeds a sheet-like document stacked on a placing member, and sequentially conveys the document on a document reading surface facing an optical reading unit. A first conveyance path for communicating with a path fed from the placement member for reversing the front and back of the document, and an upstream position of the first conveyance path communicating with the path for feeding. A second transport path, which is more branched and leads to a document reading surface facing the optical reading means, and a junction between the first and second transport paths and the document reading surface; A third transport path having a wide gap, wherein the first transport path is formed to be longer than the second transport path, and after transporting the two-sided document to the first transport path, the rear end thereof is near the branch position. When the document is detected by the placed detector, the conveyance direction of the document is reversed and the There is provided a means for transporting the one-sided document from the transport path to the third transport path, and transporting the one-sided document from the first transport path to the third transport path with the front and back surfaces of the document reversed.

According to the configuration of the present invention, when a double-sided document is fed, when the preceding document is being read by the optical reading means on the document reading surface, the subsequent document is transported to the first transport path, and There is no problem even if a part enters the third transport path. In this way, the path length for the preliminary sheet feeding required for a document having a large size in the conveying direction is sufficiently secured by the third conveying path, and the configuration of the conveying unit can be significantly reduced. In the case of a double-sided document, the first transport path is used as it is, and if the trailing edge of the document passes near the upstream position of the first reverse path, it is reversed and diverged to the second transport path. The two transport paths may be shorter than the first transport path,
Since the time required for the preliminary feeding can be reduced and the branch point is located upstream of the first transport path, the path length including the path to the reversal and the second transport path is very short, and the apparatus is downsized. Further, the configuration of the transporting means can be simplified.

Therefore, although the transport path can be shortened and the entire apparatus can be downsized, a sufficient path length can be ensured. Can be. Further, by making the reversing means smaller and realizing the preliminary paper feeding, the transport time between a plurality of documents can be remarkably reduced, and the copying time can be reduced.

FIG. 1 is a sectional view showing a simplified configuration of a document feeder 1 according to an embodiment of the present invention, and FIG. 2 is a transfer electrostatic copying machine equipped with the document feeder 1. 2 is a sectional view showing a simplified configuration of FIG.

A transparent plate 5 made of a material such as hard glass is provided on the upper body side surface 3 of the copying machine body 2. The transparent plate 5 forms a document reading surface. The document feeder 1 is mounted above the transparent plate 5 and is attached, for example, on the upper side surface 3 of the machine body so as to be angularly displaceable with respect to the rotation shaft 4. When the document is not fed by the document feeder 1 (for example,
When the original is a book or the like), the apparatus 1 is angularly displaced around the rotation axis 4, and the original is placed on the transparent plate 5 with the original image directed toward the inside of the machine, and is pressed and fixed. The copying operation is performed in the state in which the copying is performed.

Generally, as shown in FIGS. 1 and 2, the document feeder 1 is arranged so as to cover a transparent plate 5 and is a sheet-shaped document stacked and placed on a placing member 6. D is automatically fed sequentially to the reading position 5a on the transparent plate 5, and the original image is presented. The presented document image is optically scanned by an optical reading means provided in the copying machine 2, and the reading operation of the document image is performed. The original D from which the original image has been read is
It is stored again in the mounting member 6. The transfer is performed by the placing member 6.
Are performed sequentially on the originals D stacked on each other, and are circulated between the originals according to the required number of copies, thus performing one-sided copying or double-sided copying on the recording paper P.

Hereinafter, the configuration of the document feeder 1 will be described with reference to FIG.

The originals D to be copied are stacked and mounted on the mounting member 6. The placement member 6 is provided with a pair of alignment plates 8 facing each other in the width direction perpendicular to the paper feeding direction 7. The alignment plate 8
Move toward and away from each other according to the width dimension of the documents D to be stacked along the directions facing each other to align both ends of the documents D in the width direction. That is, originals D to be stacked
The center position in the width direction is constant irrespective of the size in the width direction. Further, a rear end alignment plate 9 that aligns the upstream end of the stacked originals D in the feeding direction is disposed at the upstream end in the paper feeding direction 7 of the originals D stacked on the placing member 6.

On the downstream side of the placing member 6 in the sheet feeding direction, a sheet feeding means 10 for sequentially feeding the documents D one by one is provided. The paper feeding unit 10 includes, for example, a suction conveyance unit 11 disposed below the mounting member 6 and an exhaust duct 12 disposed above the mounting member 6. The suction conveyance unit 11 includes two drive rollers each having an axis in a direction perpendicular to the paper feeding direction 7.
An endless belt 15 having an infinite number of openings is wound between 13 and 14. On the inner side of the belt 15, an intake duct 16 is arranged, and by driving an intake fan (not shown), an attraction force acts from the intake duct 16 via the belt 15, and the intake duct 16 is stacked. The lowermost original of the original D is sucked by the belt 15. Therefore, the belt 15
By driving clockwise (see FIG. 1),
The lowermost originals D in the stacking direction are sequentially fed in the feeding direction 7.

The nozzle of the exhaust duct 12 ejects an exhaust stream toward the downstream end of the document D in the stacking direction in the sheet feeding direction. As a result, the downstream end is separated one by one, so that the suction and conveyance means 11 can surely feed one sheet at a time. In this way, the documents D to be stacked can be sequentially fed from the lower side in the stacking direction by the feeding means 10. The configuration of the paper feeding unit 10 is not limited.

The document D fed by the paper feed unit 10 is transported to the transport path 40 and the reversing unit 18 via the transport roller 17. Further, a first transport detector S1 including, for example, a light emitting element S1a and a light receiving element S1b is provided downstream of the placing member 6 in the sheet feeding direction. The first conveyance detector S1 detects the reliable feeding of the originals D one by one.

In FIG. 1, a reversing means 18 includes a substantially cylindrical support cylinder 19.
Formed on the outer surface of the A transport path 40 having the transport rollers 17 includes a first transport path 22 extending in a clockwise direction (see FIG. 1) on the outer surface of the support tube 19 and a second transport path 22 extending in a counterclockwise direction. It branches into two transport paths 29 and merges at a junction 27a. Therefore, the first transport path 22 is longer than the second transport path 29. On the first transport path 22, transport rollers 20 and 21, which can be driven forward and reverse, to press and transport the document D along the outer surface of the support cylinder 19, are provided. On the first transport path 22, a second transport detector S2 including, for example, a light emitting element S2a and a light receiving element S2b is provided. The conveyance state of the document D conveyed on the first conveyance path 22 is detected by the second conveyance detector S2, and the rotation timing and rotation direction of the conveyance rollers 20, 21 are controlled.

The second transport path 29 is provided with a transport roller 30 for pressing and transporting the original along the outer surface of the support cylinder 19, and is driven to rotate in one direction. On the second transport path 29, a third transport detector S3 including, for example, a light emitting element S3a and a light receiving element S3b is provided. By the third transport detector S3,
The transport state of the document D transported on the second transport path 29 is detected, and the rotation timing of the transport roller 30 and the like are controlled.

At a branch point between the first transport path 22 and the second transport path 29, a direction changing claw 28 driven by a solenoid SOL1 (not shown) is provided. For example, solenoid SOL1
Is demagnetized, the transfer path as shown by the solid line in FIG.
The path for transporting the document from 40 to the first transport path 22 is opened. On the other hand, when the solenoid SOL1 is excited,
The direction changing claw 28 is angularly displaced to a position shown by a dotted line, and opens a passage for conveying a document from the first conveyance path 22 to the second conveyance path 29. The switching of the solenoid SOL1 is controlled based on the detection result of the second transport detector S2, for example.

The side of the first transport path 22 and the second transport path 29 opposite to the direction changing claw 28 joins near the upstream end of the transparent plate 5 in the feeding direction 23. Therefore, the document D transported by the reversing means 18 based on each copy mode set as described later is transported onto the transparent plate 5 along the feeding direction 23.

Above the transparent plate 5, two rollers 24a and 24b having an axis parallel to the width direction of the original D to be fed are arranged along the feeding direction 23, and a plurality of endless belts 26 are provided. Is wrapped around. With respect to the lower tension portion 26a of the belt 26, a plurality (4 in this embodiment)
) Press rollers 25a to 25d are arranged in this order along the feeding direction 23. The press rollers 25a to 25d press the belt 26 toward the transparent plate 5 to avoid a loosening of the tension of the belt 26 and to float the original D fed between the belt 26 and the transparent plate 5. To prevent

In this embodiment, due to the step between the position where the belt 26 is stretched on the roller 24a and the position where the belt 26 is stretched on the press roller 25a on the most upstream side in the feeding direction, the feeding direction 23 is upstream with respect to the transparent plate 5 in the feeding direction. A gap is formed near the side. That is, on the upstream side in the feeding direction with respect to the press roller 25a, the belt 26 is inclined with a constant angle θ with respect to the transparent plate 5 with the press roller 25a as a base point.

In the present embodiment, the gap is formed wider on the side of the junction 27a, and forms the third transport path 27. Even when the belt 26 is stopped on the third path 27, the original D can enter and be conveyed by the conveying force of the conveying rollers 20, 21, 30 in the reversing means 18.

The document D conveyed on the transparent plate 5 by the belt 26 is conveyed to a reading position 5a on the transparent plate 5.
The reading position 5a corresponds to a position where the downstream end of the fed document D in the feeding direction abuts on a contact piece 32 protruding near the downstream end of the transparent plate 5 in the feeding direction 23. . In this manner, the original image conveyed to the reading position 5a has its original image presented to the inside of the machine, and the original image is
Optical scanning is performed by an optical system 31 which is an optical reading means provided on the inner side, and the reading and exposing operation of the original image is performed.

While the previously fed original is read and exposed, the subsequent original is preliminarily fed. Subsequent documents are the third
In a state in which the sheet has entered the transport path 27, the preliminary sheet feeding can be completed and the apparatus can be on standby. From the vicinity of the press roller 25a where the downstream end in the feeding direction of the document to be pre-fed reaches from the contact piece 32
The interval until is set to a size that is sufficiently acceptable regardless of the size of the fed document, and is appropriately selected so that the preceding document does not collide with the succeeding document after preliminary feeding.

When the reading exposure operation of the original image is completed, the contact piece 32 is driven to be angularly displaced by the control of the solenoid SOL2, and the reading position is changed.
The passage from 5a to the transport path 36 is opened. at the same time,
The belt 26 is driven to rotate again, and the document D is transported to the transport path 36 by the transport rollers 33 to 35, and then is re-stored at the highest position in the stacking direction of the document D stacked on the placing member 6.

A discharge detector S4 and the like for detecting the conveyance state of the document D are arranged on the conveyance path 36, and control the driving timing of the solenoid SOL2. In addition, in the vicinity of the placing member 6, a one-circulation detector that detects the conveyance of one circulation over the documents D to be stacked.
S5 is provided. The detector S5 includes, for example, an operating member that comes into contact with the top of the stacked originals D. The original D is placed between the operating member and the mounting member 6 according to the feeding of the originals D. Is detected, for example, optically, it can be determined that all the originals D have been fed and circulated once.

As described above, the reading exposure operation is performed by the optical system 31 on the document image presented to the reading position 5a. Optical system
In 31, a first moving body 43 including a light source 41 such as a halogen lamp and a reflecting mirror 42 is arranged in a horizontal direction with respect to the reading position 5 a.
The document reciprocates along 44 and irradiates the presented document with light, and the reflected light is reflected by the reflecting mirrors 46 and 47 of the second moving body 45 and the zoom lens 4.
An image is formed on a photoreceptor 51 of a straight cylindrical shape which is driven to rotate in the direction of arrow 50 through 8 and a reflecting mirror 49. The second moving body 45
Also, it is driven to travel in the same direction as the first moving body 43 at half the scanning speed, and the optical path length of the reflected light is kept constant.

The surface of the photoconductor 51 is charged in advance by a charging corona discharger 52, and an electrostatic latent image corresponding to a document image is formed on the photoconductor 51 by the image formation. The electrostatic latent image is visualized as a toner image by a developing device 53 and is transferred to one surface of the recording paper P by a corona discharger 54 for transfer. The recording paper P is stored in a paper feed cassette 55 in advance, is transported along a transport path 57 having a pair of registration rollers 56, and is guided to a transfer area 58 where transfer is performed.

Power transmission means is connected to the rotation shaft of the registration roller 56 via a clutch CLT (not shown). By controlling the engagement / disengagement of the clutch CLT based on the control of the conveyance timing of the document D in the document feeder 1, the registration roller 56 is applied to the toner image on the photoconductor 51.
Of the recording paper P can be matched.
The recording paper P on which the toner image has been transferred by the transfer corona discharger 54 is guided from the conveying means 59 to the fixing device 60 and is fixed.

The recording paper P after fixing is reversed in the transport direction of the recording paper P by the recording paper reversing means 61, and is temporarily stored in the intermediate tray 63 via the transport path 62. The recording paper P on the intermediate tray 63 is again transferred to the transfer area by the conveying means 64 and the registration rollers 56.
The toner image is transferred to the other surface of the recording paper P by being guided to 58. The recording paper P on which the transfer has been completed is conveyed to the conveying means 59 and the fixing device.
The sheet is discharged to a discharge tray 66 outside the apparatus via the transfer path 60 and the transfer path 65. In this way, the original images of the originals D corresponding to the front and back sides of the corresponding recording paper P are copied. Note that when only copying is performed on one side, the recording paper P copied on one side is not discharged to the intermediate tray 63, but is discharged to the discharge tray 66.
Is discharged to From the paper feed cassettes 55, 67 to 69, for example, recording papers P having mutually different dimensions are selectively conveyed to the transfer area 58.

FIG. 3 is a block diagram showing an electrical configuration of the document feeder 1 and the copying machine 2. The motors M1,... For driving the plurality of rollers, etc., are connected to a motor drive circuit 110, the clutches CLT,.
Are connected to the solenoid drive circuit 112, respectively. The control elements used for document transport control, recording paper transport control, and copy process control such as the drive circuits 110 to 112 and the DC power supply 114 are interface circuits (I /
O) Connected to 113. The interface circuit 113 includes various detectors for detecting the conveyance of the document D and the recording paper P.
S1, S2,… are connected and a microcomputer (CP
U) 120 is connected. The signal from the detector is given to the microcomputer 120, and the microcomputer 120
The arithmetic processing corresponding to this signal is performed in each drive circuit.
Drive control signals are supplied to 110 to 112 via the interface circuit 113.

A ROM (Read Only Memory) 121 and a RAM (Random Access Memory) 122 are connected to the microcomputer 120. The microcomputer 120 has a ROM 121
The control operation is performed using the storage area of the RAM 122 as a work area based on the control program stored in the.

The interface circuit 113 is connected to the optical system 31 via a drive circuit 115, energizes the light source 41, and supplies a display control signal to each display unit 118 of the operation panel 116 via the display drive circuit 117. An operation key 119 is connected.

Hereinafter, the document D in the document feeding apparatus 1 in each copy mode is described.
Will be described.

FIG. 4A shows the state of conveyance of the one-sided document D. For convenience, FIG. 4 (1) shows the mounting member 6,
The positions of the transparent plate 5 and the reversing means 18 are shown in a simplified manner. The single-sided original D to be copied is stacked on the placing member 6 with the original image facing upward. When the direction changing claw 28 is fixedly set as shown by the solid line in FIG. 1, the document D fed from the bottom in the stacking direction is
It is transported to the first transport path 22 of the reversing means 18. The document D having passed through the first transport path 22 is transported to the reading position 5a via a third transport path 27 formed on the upstream side of the transparent plate 5 in the feeding direction. In this way, the front and back surfaces on the placing member 6 are reversed by passing through the reversing means 18, and the document D is brought to the reading position 5a, and the document image is presented.

After the presented original image is read and exposed by the optical system 31, the belt 26 is driven again, and the conveyance path 36
The originals D stacked on the placing member 6 via the sheet are re-stored at the highest position in the stacking direction. Thus, the original image of the one-sided original conveyed to the reading position 5a is read, and one-sided copying and two-sided copying on the recording paper P are realized in cooperation with the copying machine 2.

When sequentially feeding a plurality of originals to the reading position 5a, the original following the original to be fed in advance is preliminarily fed, and sufficient for the preceding original being read and exposed. It is necessary to wait at a close position. According to the present embodiment, since the third transport path 27 is formed on the transparent plate 5 following the first transport path 22, the downstream end of the subsequent document in the feeding direction is the third transport path. 27 said press rollers 25
Preliminary paper feeding can be performed until the paper reaches the vicinity of a, and a standby can be made sufficiently close to the preceding document. The first transport path 22 and the third transport path 27 allow the path length l1 for reversing the front and back surfaces in one-sided copying and for preliminary sheet feeding.
(See FIG. 1).

Therefore, by appropriately setting the third transport path 27, the size of the reversing means 18 due to the path length of the first transport path 22 can be sufficiently reduced. Further, the miniaturization of the reversing means 18 and the realization of the preliminary sheet feeding do not cause a restriction such as an increase in the transport time of the document D irrespective of the securing of the path length.

FIG. 4B shows the state of conveyance of the double-sided document D. The double-sided document D having a document image to be copied on both front and back surfaces is stacked on the mounting member 6 so that the number of pages is aligned from the upper side in the stacking direction to the lower side. You. The document D fed from the bottom in the stacking direction is conveyed to the reversing means 18. The direction changing claw 28 is first set as shown by the solid line in FIG. 1, and as a result, the conveyed document D is conveyed toward the first conveyance path 22 and the third conveyance path 27.

Feeding direction 7 of document D transported to first transport path 22
When the downstream end has passed through the direction changing claw 28, for example, when the second conveyance detector S2 detects that the downstream end has passed, the rotation direction of the conveyance rollers 20, 21 on the first conveyance path 22 is driven to reversely rotate,
Further, the direction changing claw 28 is switched to the position shown by the dotted line in FIG. Therefore, the document D is reversed in the feeding direction, is conveyed from the first conveyance path 22 to the second conveyance path 29, and again passes through the third conveyance path 27 to the reading position 5a on the transparent plate 5.
Transported to

In this manner, at the reading position 5a, the lower surface is presented with respect to the front and back surfaces when being placed on the placing member 6.
Accordingly, the lower surface is read and exposed, and thereafter,
The originals D stacked on the placing member 6 are again stored at the highest position in the stacking direction of the originals D stacked on the placing member 6 via the transport path 36. With respect to the documents D stacked on the placing member 6, the lower surface of each document is read and exposed by circulating the conveyance once, and the lower surface of the intermediate tray 63 in the copying machine 2 is The copied recording papers P are stacked and stored.

Subsequently, the conveyance shown in FIG. 4 (2) is performed again on the originals D stored and stacked again. As a result, an unread upper surface is presented at the reading position 5a. The original image on the upper surface is read and exposed, and is copied to the other surface of the recording sheet P fed from the lowermost in the stacking direction of the intermediate tray 63, which has not been copied yet,
In this way, the recording paper P on which double-sided copying has been completed is sequentially completed.
The document D whose upper surface has been read and exposed is again turned upside down via the transport path 36, and is again stored at the highest position in the stacking direction of the documents stacked on the placing member 6. Thus,
The document D that has been subjected to two circulations returns to the original state before placing before copying.

Even when the two-sided document D is conveyed, preliminary feeding is performed to shorten the copying time as described above, and the next document is brought close to the preceding document being read and exposed, and the next document is on standby. Need to be done.

According to this embodiment, since the third transport path 27 that is continuous with the first transport path 22 and the second transport path 29 is provided on the transparent plate 5, the third transport path 27 passes through the direction changing claw 28 to reverse the feeding direction. A sufficient path length l1 can be ensured, and the document D that has passed through the second transport path 29 is fed until the downstream end in the feeding direction 23 reaches the vicinity of the press roller 25a on the third transport path 27. As a result, it is possible to realize the preliminary sheet feeding sufficiently close to the preceding document. That is, together with the path length l1, the path length l2 (see FIG. 1) of the second conveyance path 29 and the third conveyance path 27 for the preliminary sheet feeding of the two-sided document is the path length l3 of the third conveyance path. Can be sufficiently secured by appropriately supplementing

Accordingly, the size of the reversing means 18 can be appropriately reduced. In addition, the downsizing of the reversing means 18 and the realization of the preliminary paper feeding can significantly reduce the time spent for transporting the original to the reading position 5a, and as a result, the copying time can be significantly reduced. In the present invention, as shown in FIG. 1, the position where the first transport path 22 and the second transport path 29, which are reversing paths, diverge is set to the first transport path communicating with the path fed from the receiver 6. 22 is the initial position, that is, the upstream position of the first transport path 22 at the start of reversal. for that reason,
When the trailing edge of the document sent from the placing section 6 passes near the branch position, the detector S2 detects this, reverses the feeding direction, is branched and transported to the second transport path 29, and the transport is reversed. As soon as the trailing edge of the original document passes the branch position, the next original document is immediately conveyed to the first conveyance path 22, and the preliminary feeding is performed in which the subsequent feeding is reversed. The time to complete can be reduced.

In addition, since the branch position is located upstream of the first transport path 22 which is the reverse path, the transport path length for feeding the document to the second transport path can be shortened, and the transport path for transporting a long document in the transport path direction can be shortened. The length can be sufficiently secured in the third transport path 27.

FIG. 5 is a flowchart for explaining the document feeding operation in the present embodiment, and FIG. 6 is a diagram intermittently showing the state of conveyance of the double-sided document D. FIG. 5 and FIG.
With reference to the drawings, the conveyance state of the double-sided document D in the document feeding operation in the present embodiment will be described. In FIG. 6, it is assumed that there are four originals D, and the suffixes 1 to 4 added to the reference D correspond to the order of the originals to be fed.

When it is detected in step a1 that the originals D are stacked on the placing member 6, in step a2, the feeding operation of the lowermost original D1 in the stacking direction is started. In step a3, as shown in FIG. 6A, the reversing means 18 performs reversal conveyance on the document D1 whose downstream end in the paper feeding direction 7 has passed through the direction changing claw 28. Therefore, as shown in FIG. 6 (2), the document D1 passes through the switching
It enters the third transport path 27 via the transport path 29.

Therefore, according to the present embodiment, in the transparent plate 5,
A third conveyance path 27 is formed upstream of the feeding direction with the belt 26 so that the document D conveyed through the first conveyance path 22 and the second conveyance path 29 can be conveyed freely. Therefore, the first transport path 22 and the second transport path 29 can be made smaller regardless of the sufficient securing of the path lengths l1 and l2. As a result, the size of the reversing means 18 can be reduced.

As described above, the document D entering the third transport path 27 is
In step a4, the conveyance by the belt 26 is further continued,
In step a5, the document D is brought to the reading position 5a,
The belt 26 stops. In step a6, for example, 1
The circulation detector S5 determines whether the conveyed document D1 is the last document. If the determination is negative, the process proceeds to step a7 to start feeding a subsequent document, in this case, document D2, and execute so-called preliminary sheet feeding.

Thereafter, the process proceeds to step a8, and as shown in FIG. 6 (3), the reading and exposure operation of the preceding document D1 by the optical system 31 is started, and the subsequent document D2 is conveyed by preliminary feeding. Execute The following document D2 to be conveyed passes through the first conveyance path 22 and the second conveyance path 29 by the same conveyance as described above during the reading and exposure operation of the preceding document D1, and is shown in FIG. To enter the third transport path 27 so as to wait for the original D1 to come close enough. That is, the succeeding document D2 before the end of the reading exposure of the preceding document D1 is conveyed to the vicinity of the document D1.

Thereafter, in step a9, it is determined whether or not the reading exposure has been completed. After the completion of the reading exposure, the process
Proceeding to a10, the belt 26 is driven again, and the document D1 on the reading position 5a is transported to the transport path 36 and discharged. In step a11, it is determined whether or not a document D2 subsequent to the document D1 to be discharged has been preliminarily fed.

If the determination is affirmative, the process proceeds to step a4, and conveys the waiting original D2 to the reading position 5a, executes the above-described processes of step a4 to step a11 again, and further executes the subsequent processes. Document D3 is preliminarily fed. Sixth
FIG. 5 (5) shows a state in which the original D1 is ejected and the following original D3 is preliminarily fed.

Thereafter, when the final document D4 is conveyed to the reading position 5a via the preliminary sheet feeding, the determination in step a6 becomes affirmative, and the process proceeds to step a12. Step a
At 12, it is determined whether double-sided copying has been completed. If the determination is negative, the process returns to step a7 again, the original D1 is again pre-fed for reading exposure on the front side that has not been read and exposed, and the second circulation of conveyance is started. Thus, Steps a4 to a12 are repeated again, and if it is determined in Step a12 that double-sided copying has been completed, the process proceeds to Step a8, in which the copy operation of the conveyed original D4 is performed without preliminary feeding. After termination, the program ends.

In this way, according to the present embodiment, since the reversing means 18 can be downsized and the preliminary sheet feeding can be reliably realized, the time spent for transporting a plurality of documents to the reading position can be significantly reduced. As a result, the copying time can be significantly reduced.

Although the present embodiment has been described with reference to the configuration of the transfer type electrostatic copying machine, the configuration may be such that recording is performed on a recording sheet having photosensitivity, for example.

Effects of the Invention As described above, according to the document feeding apparatus of the present invention, the first and second conveyances required for reversing the front and back of the document fed to the document reading surface and reversing the feeding direction. The path length of the path can be sufficiently ensured by the third transport path provided at the junction.

Moreover, the branch position of the first and second transport paths is set to the upstream side of the first transport path, and the merging section by the third transport path is formed on the opposite side, thereby reducing the length of the entire transport path. Although the length can be shortened, the path length of the first transport path can be adapted to a document long in the transport direction.
Therefore, the pre-feeding can be reliably performed irrespective of the different size of the original document while the transport time is shortened.

Further, the size of the reversing unit and the realization of the preliminary sheet feeding can significantly reduce the time spent for transporting the fed document onto the document reading surface, and as a result,
Copying time can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a simplified configuration of a document feeder 1 according to an embodiment of the present invention, and FIG. 2 is a simplified type of a transfer type electrostatic copying machine 2 equipped with the document feeder 1. FIG. 3 is a block diagram showing an electrical configuration of the document feeder 1 and the copying machine 2, and FIG. 4 is a diagram showing a state of transport of the document D in the document feeder 1 in each copy mode. FIG. 5 is a flowchart for explaining the document feeding operation in the present embodiment, and FIG. 6 is a diagram for intermittently explaining the conveyance state of a double-sided document. 1. Original document feeding device 2. Copy machine 5. Transparent plate 6.
... a mounting member, 18 ... reversing means, 22 ... a first transport path,
26... Belt, 27... Third transport path, 28... Directional change claw, 29... Second transport path, 31... Optical system, D.

Claims (1)

(57) [Claims] 1. A document feeding apparatus for feeding a sheet-like document stacked on a mounting member and continuously conveying the document on a document reading surface facing an optical reading means. A first transport path for reversing the front and back of the document by communicating with a path fed from the printer; and the optical reading means branched from an upstream position of the first transport path communicating with the fed path. A second transport path leading to a document reading surface facing the document, and a third transport path having a wide gap at the junction side between a junction of the first and second transport paths and the document reading surface. The first transport path is formed longer than the second transport path, and after the double-sided document is transported to the first transport path, when the trailing end is detected by a detector arranged near the branch position, Is transported from the second transport path to the third transport path, Document feeder, characterized in that it comprises means for conveying by inverting the document from the first transport path the front and back surfaces of the document to the third transport path.