JPH03256949A - Automatic document feed device - Google Patents

Abstract

PURPOSE:To shorten the time of exchange of documents so as to enhance the copying speed by providing such an arrangement that a halt position where the next document is once stopped is set near to the trailing end of the preceding document as far as possible when the next document is fed to the halt position during exposure of the preceding document. CONSTITUTION:A detecting means PS2 for detecting the size of a document is provided to a paper feed means 10. The next document is fed to a predetermined standby-by position which is upstream of the preceding document in accordance with a document size detection signal delivered from the document detecting means PS2 during stopping of the preceding document for scanning exposure, for a required number of copies, of the preceding document which has been fed to a predetermined position in an image-exposure section by a conveying means 20, and then the next sheet is allowed to stand by at the stand-by position. Thereafter, a press roller 26 is driven and controlled so as to press or separate a conveying belt 21 against or from a document setting glass surface 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to improvements in automatic document conveyance devices in recording devices such as electrophotographic copying machines, image reading devices, and the like.

[Background of the invention]

An automatic document feeder is generally used by being mounted on a document table glass (platen glass) of an image exposure unit of a copying machine or the like.

In an optical system moving type copying machine equipped with this automatic document feeder, the automatic document feeder feeds sheets of originals (hereinafter simply referred to as originals) one by one from the document tray (stack section) on which they are placed. The document is fed onto a document table glass by a conveyor belt, exposed there by an exposure section lamp in the main body of the copying machine, and then further conveyed onto a document discharge table.

Conventionally, the operation of exchanging originals on the original platen glass by an automatic document feeder is to send out the next original from the stack section after a paper ejection sensor detects that the original on the original platen has been ejected. It was conveyed upward and stopped at a predetermined position. As a result, it takes a long time to exchange originals, and therefore a lot of time is required for copy processing, resulting in a decrease in copy productivity.

[Problem to be solved by the invention]

When using an automatic document feeder to automatically feed and eject documents onto the document table, copy productivity can be increased by 10% if the document is exchanged within the return time of the scanning optical system.
It becomes 0% and no time is wasted. However, as the size of the originals becomes smaller, the gap between the originals becomes wider, resulting in a loss of conveyance time and lowering copy productivity.

To achieve this, it is necessary to increase the document transport speed from the document double-feed prevention position in the stack unit to the document stop position on the document table glass surface.

However, increasing the document conveyance speed causes various problems such as an increase in the size of the motor, an increase in power consumption, generation of noise, abrasion of the conveyor belt, an increase in the degree of document damage, and a decrease in document separation performance.

Japanese Unexamined Patent Application Publication No. 1-236136 discloses a conventional technique for a document conveying device that eliminates the above problem and shortens the time required to exchange documents without increasing the document conveyance speed.

This document conveying device stops conveying the first document at a predetermined position, then stops conveying the second document to a position that is not on the upstream platen glass adjacent to the predetermined position, and then performs image reading processing. conveying the first original document that has already been completed by the conveying means to a downstream position on the platen glass adjacent to the predetermined position and at a position where it can be conveyed, and at the same time stopping the second original document at a predetermined position; This procedure is repeated for subsequent documents, and the conveyance is stopped one after another.

However, with this document transport method, three documents move at the same time, so if a jam occurs, the next document may collide with the preceding document and be damaged, and there is little margin for jam detection and jam removal. becomes complicated.

In addition, in the above example, the distance between the rear edge of the first document on the platen glass and the leading edge of the second document on the feeding path is large, which increases the traveling distance of the next document when exchanging documents. The disadvantage is that the time required to exchange originals increases.

In order to improve these drawbacks, the leading edge of the next document is conveyed to a contact nip position between the conveyor belt above the platen glass and the platen glass, and is kept on standby.

However, the contact position of the conveyor belt is determined by the position of the document pressing roller that presses the conveyor belt against the platen glass surface from inside the conveyor belt, and the leading edge of the document cannot be brought any closer to the preceding document.

Unfortunately, it is impossible to shorten the document exchange time when transporting small-sized documents.

[Means to solve the problem]

The object of the present invention is to solve the above-mentioned problems in an automatic document feeder and to increase the number of copies processed.

In other words, when feeding the next original to the temporary stop position during exposure of the previous original, the temporary stop position of the next original is brought as close to the trailing edge of the previous original as possible to shorten the original exchange time and improve the web processing speed. This is the purpose.

The automatic document feeder of the present invention that achieves the above object separates the originals one by one from a stack of originals stacked on the original platen, feeds the originals one by one to an image exposure unit, and exposes the originals to the image exposure unit on the platen glass. The optical system is moved to perform scanning exposure.
In an automatic document feeder that transports the original document to a document eject table after exposure, the document feeder feeds the original document to the image exposure section, and the conveyance means stops conveying the document to a predetermined position of the image exposure section. and a paper ejecting means for transporting the document after exposure, and a control means for driving and controlling these means, and a paper feeding means is disposed on the upstream side of the document conveyance side of the image exposure section, and a paper ejecting means is arranged on the downstream side. In addition, the conveying means includes a driving roller, a driven roller, a conveying belt that can be rotated around both rollers, a document pressing roller, and a conveying means rotated inside the conveying belt on the upstream side of the conveying belt. It is characterized by comprising at least one movable pressing roller positioned therein, and a driving means that presses the movable pressing roller from inside the conveyor belt and drives the movable pressing roller so as to be able to press against and separate from the document table glass surface.

The automatic document feeder according to the present invention has (1) a document feed inlet and a document ejection port on the document table glass provided in different directions;
In addition, a document copy standard is set on the paper ejection side, and ■ the feeding of the next original during image exposure and the ejection of the exposed original during ejection are completed, and ■ the leading edge of the next original is fed during image exposure. , the document standby was arranged near the upper end of the glass surface of the document table upstream from the pressing position of the conveyor belt, and the ejecting operation of the preceding document was completed during image exposure.

Also, in the automatic document feeder according to the present invention, the paper feeding means is provided with a detection means for detecting the document size, and the image exposure is performed by the conveyance means based on the document size detection signal detected by the document detection means. While the preceding document is stopped, which has been conveyed to a predetermined position on the copy sheet and subjected to scanning exposure for a predetermined number of copies, the next document is conveyed to a predetermined standby position upstream of the preceding document and held there, and the pressure roller is driven to move the conveyor belt. This feature is characterized in that it is controlled so that it is pressed against or separated from the glass surface of the document table.

Furthermore, in the automatic document conveying device according to the present invention, the driving control of the pressing roller is such that the leading edge of the next document at the standby position of the image exposure section is selected to be downstream of the position where the pressing roller is pressed; In some cases, the press roller is driven to separate the conveyor belt and the document table glass in the vicinity of the press position in a direction that increases the gap therebetween.

[Example] Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 is a configuration diagram showing the document conveyance path of the automatic document feeder according to the present invention, and FIG. 2 is an external perspective view of the automatic document feeder installed in a copying machine. @31! I is a configuration diagram showing the drive system (power transmission system) of the automatic document feeder, Figure 4 is a schematic diagram of the overall drive system configuration of this device, and Figure 5 is a schematic diagram of the document conveyance path when copying double-sided originals. It is. Note that these illustrated devices are automatic document feeder t (RADF) with automatic document reversing function.
).

The structure and operation of the automatic document feeder will be explained with reference to these figures.

The automatic document feeder (RADF) of the present invention is installed on the copying machine main body l as shown in FIGS.
A paper feeding unit IO feeds one original from a stack of originals placed on the original tray 11 onto the original platen glass 2, and a document fed from the original paper feeding unit IO is fed to the original platen glass 2 on the original platen. Conveyance unit 2 that conveys the image to a predetermined position (IF image exposure scanning position)
0, and a document transport section 30 that discharges the document sent out from the document transport section 20 onto a paper discharge tray 39 after image exposure is completed.
It is composed of.

First, FIGS. 3 and 4 will be explained from the drive system. There is a motor M as a drive source in the center, and a paper feed section l is on the right side of the diagram.
The transport section 20 is arranged in the center of O1, and the drive system for document discharge fi30 is arranged on the left side. GO, G using motor M as a driving source
Rotate the toothed pulleys PI and P2 through each gear of l,
It branches into a paper feed section 10 and a document discharge section 30 by toothed belts B1 and B2, respectively.

The drive transmission system that branches to the right in the diagram has a tooth row G2゜G.
3, G4, G5, and G6, the paper feed section 10
The feed roller 15A for the separation belt, the intermediate conveyance roller 18, and the conveyance belt 21 drive roller 23 of the conveyance section 20 are driven. Gear G at the shaft end of feed roller 15A
6 has a built-in clutch Kl, which is free except during paper feeding rotation.

On the other hand, a drive transmission system branched from the pulley PI to the left side in the drawing via the belt Bl drives the paper discharge reversing roller 31 via Boo'J P 4 , P 5 and gears G 7 and G 8 . In addition, gear G9 has a one-way clutch of 2, and gear G9.
7 is provided with a one-way clutch 3, respectively.

As a result, the paper ejection reversing roller 31 and the paper ejection roller 35
always rotates in one direction, in the direction of the arrow shown, regardless of whether the motor M is in the forward or reverse direction.

In the schematic diagram of FIG. 5, the automatic document feeder according to the present invention is also capable of double-sided copying of double-sided originals. The original passes through the same transport path as normal one-sided copying, and the first side is exposed (copying).
When this is completed, the path of the arrows S l and S 2 is taken, and the paper ejection reversing roller 31 . It is not ejected even after passing through the pinch rollers 32 and 33, but is reversely conveyed, takes the reverse path indicated by arrows R1 and R2, and is again conveyed backwards to the document platen glass 2 for exposure (copying) on the second side (copying). Then, the path of arrows St and S2 is taken again, and this time the sheet discharge reversing roller 31. After passing through the pinch rollers 32 and 33, the paper exit roller 35 follows the path of arrow S3.
This shows the state in which the paper is ejected onto the paper ejection tray 39.

A document placement table 11 is provided on the upper right side of the paper feed section 10 of the automatic document feeder, and allows documents to be stacked on top of each other.

A solenoid SD is installed on the downstream side of the tip of the document mounting table 11.
I. A movable guide plate 12 and a document leading edge stopper 13 are provided which can be swung by the solenoid SDI.

When a stack of originals is placed on the original platen 11, the presence or absence of originals on the original platen is detected by the original set detection sensor (zero original detection sensor) PSL, and the RADF mode is displayed on the control panel of the copying machine body 1. Is displayed.

A width regulating plate 14 is movably provided on the document mounting table 11 to regulate the width direction of the document.

On the document feeding downstream side of the document mounting table 11, there is a feed belt 16 that rotates around a feed roller 15A and a driven roller 15B, and a double feed prevention roller 1 located below the feed belt 16.
Separate paper feeding means consisting of 7 is provided.

The driving force of the drive motor M is transmitted to the separation sheet feeding means via the electromagnetic clutch Kl.

By operating the copy button 4 on the control panel 3 of the copying machine body 1, the automatic document feeder is started, and the paper feed solenoid SDI is energized and operated.
Raising the tip of the movable guide plate 12 connected to this,
The feed belt 1 presses the document bundle against the feed belt 16 surface and at the same time begins to rotate by the driving force of the drive motor M.
6, the document is sent out, and a fixed double-feed prevention roller 17 separates and sends out only the uppermost document among the plurality of documents sent out. At this time, the progress of the lower document being followed by the double-feed prevention roller 17 is prevented.

A document passage detection sensor (document size detection sensor) PS2, an intermediate conveyance roller 18, and a curved guide plate 19 are provided on the document feeding downstream side of the separation sheet feeding means. The document feeder is nipped and conveyed by the pair of intermediate conveyance rollers 18, with the second clutch ONL, and when its tip crosses the sensor PS1, the first clutch Kl, which was driving the feed roller 15A, is turned OFF. The feed belt 16 is driven to rotate between the drive shaft and a directional clutch press-fitted into the feed roller 15A until the document tray is removed and then stopped.

When the passage of the leading edge of one document sent out by the separation feeding means is detected by the document passage detection sensor PS2 and the sensor PS1 is turned on, the first timer TMI starts counting. The document is then fed by a pair of intermediate conveyance rollers 18 in the vicinity thereof, passes between guide plates 19, and is fed toward document table glass 2. Further, the original document is conveyed over the document table glass 2 under pressure by a conveyor belt 21 that rotates at approximately the same speed as the circumferential speed of the intermediate conveyance roller 18 . When the first timer TMI counts up, the third clutch that was driving the conveyor belt 21 is turned off and the brake (BK) is activated to move the document to the 2nd edge of the document table glass on the paper ejection side. The document is stopped when it hits the document stopper 5 that protrudes from the side. I;, the sensor PS
2 detects that the trailing edge of the document has passed.The document size (
length) is detected. Further, the sensor PS2 is connected to the paper feed section I.
A paper jam of the document at O is also detected.

The conveyor belt 21 is stretched between a conveyor belt drive roller 22, a driven roller 23, two document pressing rollers 24, 25, and a movable pressing roller 26 that can be pressed and separated.
Motor M allows forward and reverse rotation.

The lower running surface of the transport bell 1-21 is pressed against the surface of the document table glass 2 by the document pressing rollers 24, 25 and the movable pressing roller 26.

Here, the document length is measured from the time when the leading edge and trailing edge of the document tray pass through the sensor PS1, and three types of modes are switched within the following three classifications.

(i) When the document length L is Ll>L>L4 (ii)
) Original length is L2>L>Ll or L3>
In the case of L (LII) the document length is L
>L 2 Here, Ll is the distance from the original stopper 5 to the original holding roller 25, L2 is the distance from the original stopper 5 to the movable pressing roller 26, and L3 is the distance from the original holding roller 25 to the intermediate conveyance roller 18. It is.

FIG. 6 is a schematic diagram illustrating the arrangement and distance relationship between the main document conveying members of the automatic document conveying device.

(i) When Ll>L>L3 (small size original) The leading edge of the original DI comes into contact with the original stopper 5 and stops, and the movable pressing roller 26 is raised by a solenoid (not shown). This causes the conveyor belt 21 to move to the sixth position.
The stretched position shown by the broken line in the figure changes to the state shown by the solid line, and the conveyor bell 1-21 between the document pressing roller 25 and the movable pressing roller 26 is lifted up, creating a gap with the document table glass 2.

At this time, the driven roller side of the conveyor belt 21 also applies tension to the outside by spring pressure to absorb fluctuations in the slack of the conveyor belt 21 due to the movement of the movable pressing roller 26.

The document plate is exposed to light by an exposure lamp 6 in the copying machine main body 1 at a stop position on the document platen glass 2, and a document image is formed on the recording medium by scanning by a scanning exposure section consisting of a lens, a mirror, etc.

At the start of the exposure, the first clutch Kl.

2 is set ONL to the second clutch, the subsequent next original D2 is sent out, and when its leading edge crosses the sensor PS2, the second timer TM2 starts counting. This second timer T
M2 is set so that the leading edge of the document D2 passes over the movable pressing roller 26 and counts up before the document pressing roller 25. When the count is up, the second clutch 2 of the intermediate conveyance roller 18 is turned OFF and the brake is turned ON, so that the leading edge of the next document D2 is stopped between the document pressing roller 25 and the movable pressing roller 26 and is on standby. This operation is configured to be completed before the exposure of the set number of copies of the preceding document Dl is completed.

FIG. 7 is a schematic diagram showing the stop exposure of the preceding original Di and the standby state of the next original D2, where L is the length of the original, A is the distance from the rear end of the preceding original DI to the leading edge of the next original D2, and B indicates the distance from the document stopper 5 to the paper ejection roller 35 (ejection distance).

Next, when exposure for the set number of copies is completed, clutch 2 and clutch 3 are ONL, and the preceding original Di is ejected, and the next original D2, which has been stopped at the standby position, is conveyed over the original platen glass 2 and brought to the original stopper 5. hit it against. At this time, the required distance (A +
For the preceding original Dlf: (L), the distance required to complete ejection is (L + B), but if (A + L) < (L + B), the original stops in the middle of the ejection process.

However, if (A+L)>(L+B), then (A and B) must be set so that (A>B)&.

However, as shown in FIG. 1, in a structure in which the original document after exposure processing is reversed and ejected and placed on the upper side of the automatic document feeder, the ejection distance B is long, and therefore the interval A is
must be made larger. Therefore, it takes a long time for the document to be exchanged until the next document D2 reaches the stop position of the document stopper 5 from the standby position.

In the automatic document feeder of the present invention, 3 is OFF in the clutch.
L, even after the brake (BK) is turned on, the paper ejection reversing roller 31 is rotated, and the rear end of the document is aligned with the sensor PS3.
Turn on solenoid SD4 after a certain period of time after crossing the
By pressing the pressing lever 34, the paper discharge roller 35, which rotates at a lower speed than the paper discharge reversing roller 31, pinches the document and discharges it at a low speed. Each speed is determined so that this discharge operation is completed by the time the copying operation of the next document is completed. The above operations are repeated until there is no paper left.

(■) In the case of L2>L>L l or L3>L Figure 8 is a schematic diagram of conveying a document of the above size.
and the intermediate conveyance roller 18.

If the document length is less than L3 (the distance from the nip position of the intermediate conveying roller 18 to the pressing position of the document holding roller 25), if the movable pressing roller 2
If the number 6 is increased, the pressing force between the rollers 1g and 26 against the document platen glass 2 is lost, which reduces the conveyance force and tends to cause conveyance defects. Therefore, the movable pressure roller 2
6 must be lowered.

(IiI) When L>L2 FIG. 9 is a schematic diagram of conveying a document of the above size.

In this case, either the standby position is set to the front of the glass edge, or the next original D2 is not put into standby operation, and the next original D2 is moved from the standby position in front of the glass in synchronization with the ejection of the preceding original Dl.
is fed out from the nip position of the double-feed prevention roller 17 of the paper feed section IO, and after the next document D2 is stopped by the document stopper 5, the preceding document D1 is discharged at a low speed during the exposure operation.

In the above explanation, the document length was detected by the document passage detection sensor PS2, but the width regulating plate 14 on the document placement table 11
It is also possible to control the vertical movement of the movable pressing roller 26 in advance by detecting the width direction of the document size based on the amount of movement, and detecting the document length based on the corresponding predetermined length in the feeding direction. Alternatively, the document size may be stored manually using a key.

FIG. 10 is a perspective view showing an embodiment of a driving device for the movable pressing roller 26. As shown in FIG.

Spring-biased tension members 23A and 23B are provided at both shaft ends of the driven roller 23, and are movable along a long groove (not shown) in parallel to the document conveyance direction. The conveyor belt 21 wound between the drive roller 22 and the driven roller 23 is stretched without slack by the tension members 23A and 23B.

Both shaft ends of the movable pressure roller 26 are arms 28A, 2
8B, and the arms 28A, 28B are supported by a support shaft 29
It is integral with A and 29B and is swingably supported.

One end of an arm 29G is integrally attached to the one support shaft 29B. A plunger of a latch control solenoid SD5 is rotatably connected to the other end of the arm 29C. Bearings 29D and 29E are fitted onto the support shafts 29A and 29B, respectively, and rotatably supported.

When the solenoid SD5 is energized and the plunger is attracted, the arm 29C rotates counterclockwise around the support shaft 29B, and the arms 28A and 28B also rotate together around the support shaft 29B. Then, the movable pressure roller 26 is oscillated and moved upward, and the conveyor belt 21
The pressing force on the conveyor belt 21 is released by separating from the inner surface of the belt. The slack in the conveyor belt 21 that occurs at this time is tightened by the spring urging force of the tension members 23A and 23B.

When the suction force of the solenoid SD5 is released and returned, the movable pressing roller 26 descends due to its own weight and spring bias, presses the inner surface of the conveyor bell 1-21, and presses it against the upper surface of the document table glass 2.

FIG. 11 is a perspective view showing another embodiment of the movable pressure roller driving device according to the present invention.

In this embodiment, the driven roller 23 is supported in a fixed position so as to be freely rotatable, and the tension roller 27A interlocked with the movable pressure roller 26 eliminates the slack in the conveyor belt 21 that occurs in response to the vertical movement of the movable pressure roller 26. It is characterized by Arms 28C and 28D that support both shaft ends of the movable pressure roller 26 are swingable by support shafts 29A and 29B. A tension roller 27A is rotatably supported at the other ends of the arms 28C and 28D. A support shaft 29B, which is integral with one arm 28D, is rotationally driven by a solenoid SD5 as in the previous embodiment.

Arm 28C,
28D rotates counterclockwise, the movable pressing roller 26 separates from the lower inner surface of the conveyor belt 1-21, and the tension roller 27A presses against the upper outer surface of the conveyor roller 21.

FIG. 12 is a perspective view showing still another embodiment of the movable pressure roller driving device according to the present invention.

an arm 28E that supports both shaft ends of the movable pressure roller 26;
28F is swingable by support shafts 29A and 29B. A tension roller 27B is rotatably supported at an intermediate position between the arms 28E and 28F. The lower end of an arm 29C fixed to the other end of a support shaft 29B integral with one arm 28F is connected to a plunger of a solenoid SD5.

By the suction operation of the solenoid SD5, the arm 28
E, 28F swings counterclockwise, and the movable pressing roller 26
is separated from the lower inner surface of the conveyor belt 21, and the tension roller 27B pushes up the upper inner surface of the conveyor belt 21 to remove slack in the conveyor belt.

〔Effect of the invention〕

As described above, according to the automatic document feeder of the present invention, it is possible not only to reduce the document feed speed, but also to stabilize and improve separation performance and smooth document feed by performing low-speed separation during document feeding. This is effective in preventing damage to the leading edge of the document. In addition, it is possible to reduce the load on the motor, save power consumption, and install a small, low-torque motor. Furthermore, if the speed is not reduced, it is possible to improve copy productivity, that is, the ratio between (the number of original sheets fed per minute in an ADF) and (the number of copies per minute in a copying machine).

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the document conveyance path of the automatic document feeder according to the present invention, FIG. 2 is a block diagram showing the drive system (power transmission system) of the document feeder on the main body of the copying machine, and FIG. A schematic diagram of the overall drive system configuration of the apparatus, FIG. 5 is a schematic diagram of the document conveyance path during double-sided document copying, and FIG. 6 is a schematic diagram illustrating the arrangement distance between the main document conveyance members of the automatic document feeder. FIGS. 7, 8, and 9 are schematic diagrams showing the process of conveying documents of various sizes, and FIGS. 1O, 11, and 12 are other embodiments of the movable pressure roller driving device according to the invention. FIG. ■...Copying machine main body 5...Document stopper 11...Document mounting table 18...Intermediate conveyance roller 21...Conveyance belt 23...Followed roller 26...Movable pressure roller 30... Original discharge section 34...Pressing lever D...Original D2...Next original 2...Original platen glass 10...Paper feeding section 16...Feed belt 20...Transportation section 22... Drive rollers 24, 25... Original holding roller 27... Tension roller 31... Paper ejection reversing roller 35... Paper ejection roller Di... Preceding originals 28A, 28B, 28C, 28E, 28F... Arms Kl, K2, K3...Clutch M...Motor PS2...Document size detection sensor PS3...Document discharge detection sensor SDI...Paper feed section solenoid SD2...Transport section solenoid SD3 ... Paper discharge section solenoid SD5 ... Movable pressure roller drive solenoid A, B, L
l, L 2, L 3... Interval L... Document length BK... Brake

Claims (3)

[Claims] (1) Separate the originals one by one from the stack of originals stacked on the original platen, feed them one by one to the image exposure section, stop the originals on the image exposure part of the platen glass, and move the optical system. In an automatic document feeder that performs scanning exposure and transports the document to a document eject table after exposure, the document feed means feeds the document to the image exposure section, and the document is moved to a predetermined position of the image exposure section. A paper feeding means is provided on the upstream side of the image exposure section for transporting the original, comprising a transport means for stopping the transport, a paper ejection means for transporting the document after exposure, and a control means for driving and controlling these means.
A paper ejection means is disposed on the downstream side, and the transport means includes a drive roller, a driven roller, a transport belt that can be rotated around both rollers, a document holding roller, and an inner side of the transport belt. The present invention is comprised of at least one movable pressing roller located on the upstream side that is rotated by the conveyor belt, and a driving means that presses the movable pressing roller from inside the conveyor belt and drives the movable pressing roller so that it can be pressed against and separated from the document platen glass surface. Features automatic document feeder. (2) The paper feeding means is provided with a detection means for detecting the document size, and based on the document size detection signal detected by the document detection means, the document is conveyed to a predetermined position in the image exposure section by the conveyance means and a predetermined number of copies are made. While the preceding original to be subjected to scanning exposure is stopped, the next original is conveyed to a predetermined standby position upstream of the preceding original and held there, and the pressing roller is driven to press or separate the conveying belt from the glass surface of the original platen. The automatic document feeder according to claim 1, wherein the automatic document feeder is controlled as follows. (3) The driving control of the pressing roller is such that when the leading edge of the next document at the standby position of the image exposure unit is selected to be downstream of the conveyance position from the pressing position of the pressing roller, driving the pressing roller; 3. The automatic document conveying apparatus according to claim 1, wherein the conveyor belt and the document table glass are separated from each other in a direction that increases a gap between the conveyor belt and the document table glass in the vicinity of the pressure contact position.