JPH03100563A - Automatic document feeder - Google Patents

Abstract

PURPOSE:To shorten the time required for changing originals and to prevent the wasteful usage of a copy of a preceding document by controlling next document feeding based on a detecting signal indicative of passage of the preceding document and displaying a message about abnormality after the copying action of the preceding document is completed if abnormal feeding is detected. CONSTITUTION:When a first document is separated and fed and its leading edge passes by a document passage detecting sensor PS3, a leading edge passage signal is issued, a middle carrying roller 5 is driven and rotated to feed the document. After counting has been carried out for a specific length of time since the document passed by a document passage synchronizing sensor PS5, a paper feed clutch K2 is turned on, a drive motor M is driven, and a pickup roller 2 and a feed roller 3 feed a next document. The document passage detecting means PS3 and PS5 detect abnormal document feeding until the document stops in a temporary stop position. If abnormality is detected, a message of the abnormality is displayed after the entire action of the preceding document is completed. Consequently, the time required to feed documents is shortened, and wasteful copying can be prevented if abnormalities such as jam occur.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement of an automatic document feeder in a recording apparatus such as an electrophotographic copying machine.

[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 a predetermined number of copies 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 such that after a paper ejection sensor detects that the preceding original on the original platen has been ejected, the next original is sent out from the stack section and placed on the original platen. It was conveyed onto glass 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. Furthermore, if an abnormality such as a jam occurs, the copying machine itself will immediately stop.

[Problem to be solved by the invention]

Operations required to exchange the preceding document and the next document during the exposure time or during the return time of the scanning optical system during the document exchange operation in which the automatic document feeder is used to automatically feed and eject the document onto the document table. If you do this, copy productivity will be 100% and no time will be wasted.

To this end, it is necessary to increase the speed at which documents are transported from the document double-feed prevention position in the stack unit to the document stop position on the document platen glass surface, and to make use of the above-mentioned wasted time.

However, if the document transport speed is simply increased, or if the operation related to the next document is performed while the operation related to the previous document is not completed, the operation will become unstable due to friction between the document and the platen glass, etc. It becomes difficult to always stop the document at a predetermined position, which may cause a jam or the like. In addition, if an abnormality such as a jam occurs in the transport of the next original while the preceding original is being exposed, the copying machine will immediately stop, and the copying of the preceding original may be interrupted and wasted. .

[Failure 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.

An automatic document feeder of the present invention that achieves the above object sequentially transports a plurality of sheet-like originals to an image exposure section, stops the documents at a predetermined position in the image exposure section, and moves an optical system. In an automatic document feeder that performs scanning exposure and transports the document to the document eject tray after exposure, the subsequent document is started to be fed before the exposure operation of the preceding document is completed, and is placed at a predetermined position before the image exposure section. The automatic document feeder is placed on temporary standby, and is provided with a detection means for detecting the passage of the fed document, and controls the feeding start operation of the next document based on the passage detection signal of the preceding document, and , the document passage detecting means also detects an abnormality in document conveyance up to the temporary stop position, and when an abnormality in document conveyance is detected,
The present invention is characterized in that the abnormality is displayed based on the detection signal after all copying operations of the preceding document on the copying machine main body side are completed.

Further, the present invention is characterized in that the abnormality display is performed after the preceding document is ejected.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 is a block diagram of an image forming apparatus (for example, an electrophotographic copying machine) equipped with an automatic document feeder according to the present invention. In the figure, a copying machine main body 100 is composed of a scanning exposure section A1 an image forming section B1 a paper feeding section C1 a conveyance section E1 a fixing section F1 a paper discharge section G and a paper discharge tray H. In the figure, the broken line indicates the conveyance path of the recording paper.

FIG. 2 is a configuration diagram showing the document conveyance path of an automatic document conveyance device that can swing open and close on the top surface of the copying machine main body 100;
The figure is a configuration diagram showing the drive system (power transmission system) of the automatic document feeder, FIG. 4 is a perspective view showing the document feeder system and drive system inside the device, and FIG. 5 is a plan view of the main parts of the automatic document feeder. It is a diagram. Furthermore, FIG. 6 is an external perspective view of the upper part of the copying machine equipped with an automatic document feeder. FIG. 7(A) is a schematic diagram showing the document conveyance path. The illustrated devices are automatic document feeders (RADF) with an automatic document reversing function.

First, the structure and operation of the automatic document feeder will be explained with reference to FIGS. 2, 4, 6, and 7(A).

A document placement table l is provided on the left side of the upper surface of the automatic document feeder, and allows documents to be stacked on top of each other.

A document setting solenoid SDI and a document leading end stopper ID swingable by the solenoid SDI are provided below the leading end of the document placing table l. With the upper end of the leading edge stopper ID protruding near the leading edge of the document mounting table l, place the document stack on the document mounting table 1, and place the leading edge of the document stack on the document leading edge stopper ID. Align the butt paper.

When a stack of originals is placed on the original platen 1, the presence or absence of originals on the original platen is detected by the original set detection sensor (zero original detection sensor) PS2, and the ADF mode is displayed on the control panel 110 of the copying machine main body 100. is displayed.

Width regulating plates IA, IA are provided on the document mounting table l to regulate the width direction of the document. The width regulating plate IA is formed by rack gears IA that can alternately slide laterally across the pinion gear IB on the lower surface of the document table L.
C and Ic, respectively, and can be moved symmetrically around the center. The rack gears IC, Ic are connected to width regulating plates IA, IA, respectively, and the amount of movement thereof is detected by a document size detection sensor PS1, so that the width size of the document can be read. Based on this read value, the length of the standard size document is automatically converted. Therefore, place the document stack on the document placement table 1, and press the width regulating plate IA.
, IA is slid and brought into contact with the width of the document, so that various document sizes, that is, the lengths of each document are stored.

A pickup roller 2 is located above and near the tip of the document placement table 1, and is movable up and down by the operation of a paper feed solenoid (Usochi type) SD2 and spring pressure, and is also rotatable by the driving force of a drive motor M. It has become.

By operating the copy button ILL on the control panel 110, the automatic document feeder is started, the paper feed solenoid SD2 is energized and activated, and the pickup roller 2 connected thereto is lowered to move the top of the stack of documents. It comes into pressure contact with the upper surface, and at the same time begins to rotate by the driving force of the drive motor M, and the document is sent out.

On the document feeding downstream side of the pickup roller 2, there is a feed belt 3 that rotates around a feed roller 3A;
Separation sheet feeding means consisting of a double feeding prevention roller 4 located below is provided. The separation sheet feeding means is driven by a drive motor M.
The driving force is transmitted to the electromagnetic clutch 2 through the pickup roller 2, and only the uppermost original among the plurality of originals sent out by the pickup roller 2 is separated and sent out.

On the document feeding downstream side of the separation sheet feeding means, there is a document passage detection sensor PS3, an intermediate withdrawal roller 5, and a curved guide plate 6.
is the provision.

The passage of the leading edge of the original sheet sent out by the separation feeding means is detected by the original passage detection sensor PS3, and is then fed by a pair of intermediate conveyance rollers 5 in the vicinity, passing between the guide plates 60. be sent. The leading edge of the original passes through the original passage synchronization sensor (inverted original passage detection sensor) PS5 located in the middle of this feeding path! Kotoki,
Emit a detection signal to control document transport. The document passage synchronization sensor PS5 is connected to a document stopper 102, which will be described later. 2. Drive motor M and paper feed clutch. The operation of the transport latch K1 etc. is controlled via a clock timer.

Next, the rotating conveyor belt 8 and the copying machine main body 100
The document is conveyed while being pinched between 1 inch of the original platen glass for exposing the original image on the upper surface (hereinafter referred to as the document platen glass), and is projected from the upper surface of the left end of the document platen glass 101 by the operation of the document stopper solenoid (latch type) SD3. The document stops at the position where the leading edge of the document abuts the document stopper 102 which is set to .

The conveyance belt 8 is stretched between a conveyance belt drive roller 9, a driven roller 10, three document pressing rollers 11, and a tension roller 12.

The original is exposed to light by an exposure lamp 103 inside the copying machine main body at a stop position on the original platen glass 101.
An original image is formed on a recording medium by scanning with an optical system consisting of a mirror or the like.

Then, the same exposure is repeated for the set number of copies, and when a series of copying processes for the original is completed, the abutting portion of the original stopper 102 touches the original platen glass 10.
1, the leading edge of the original is released, and the original is conveyed out by the conveyor belt 8 and the pair of paper ejection rollers 13, which start rotating again, and passage of the trailing edge of the original is detected by the original ejection detection sensor PS4. Thereafter, the document is discharged and placed on a paper discharge tray (original paper discharge tray) 14.

Furthermore, this automatic document feeder is provided with a document reversing section 30 for reversing the front and back of the document using the document reversing path. The document reversing unit 30 includes a transport roller group 31.32.3.
3, a guide plate 34, and an inverted original passage detection sensor PS5 for detecting an original passing through the inversion section 30.

Next, the power drive system for the roller group and belt will be explained with reference to FIGS. 3, 4, and 5.

The drive motor M is a servo motor in which a DC motor and a speed control device (such as an encoder or a tacho generator) are integrated. A toothed pulley Pl that is integral with the drive shaft 20 of the servo motor M, and a toothed pulley P that is fixed to the intermediate shaft 21.
A toothed belt Bl is stretched between each of the booms 2 and 2, and the intermediate shaft 21 is rotated by the driving rotation of the motor M.

On the intermediate shaft 21, in addition to the toothed boolean IJ P2, there is also a toothed pulley P3. P4 and electromagnetic clutch Kl are shaft-mounted. Between the toothed pulley P3 and the toothed pulley P5 fixed to the shaft end of the conveyor belt drive roller 9, a toothed belt B2 is wound and meshed to be rotatable.

The conveyor belt 8 is rotated by the rotation of the conveyor belt drive roller 9.
The driven roller IO rotates via the driven roller IO, and the toothed pulley PIO fixed to the shaft end of the driven roller IO meshes with the toothed pulley pH via the toothed belt B5, thereby rotating the paper discharge roller 13.

Further, a toothed belt B3 that winds around the outer periphery of a toothed pulley P4 provided on the intermediate shaft 21 and meshes with the feed roller 3
A toothed Zuri P6 is attached to the shaft end of a feed roller shaft 22 that rotates A through gears Gl and G2, and a toothed Zuri P6 is attached to the shaft end of an intermediate conveyance roller shaft 23 that is integral with the intermediate conveyance roller 5. It is wound and meshed with each outer peripheral tooth portion of the toothed pulley P7. Note that R1 and R2 are tension rollers that are placed under tension in circumferential contact with the outer peripheral surface of the toothed bell 1-83.

Due to the rotation of the toothed belt B3, the feed roller shaft 22, which is integral with the toothed pulley P6, rotates the feed roller 3A via the gears Gl and G2.
Rotate the feed belt 3 wound between P8.B and the toothed pulley P8.B. With P9 and toothed belt B4,
Rotate the pickup roller 2. On the other hand, an electromagnetic clutch 2 is attached to the other end of the feed roller shaft 22, which is controlled based on an input signal to rotate the feed belt 3 and pickup roller 2 to feed the original.

When copying a double-sided document, the conveyor belt drive roller 9 starts rotating counterclockwise in synchronization with the completion of exposure of the document whose first side has been exposed in the process described above, so that the conveyor belt 8
The document is conveyed rightward on the document table glass lot.

The right end portion of the transported document is sent to the document reversing section 30. Therefore, the document tray is conveyed around the document reversing section 30 along the guide plate 34I while being sequentially nipped by the conveying rollers 31, 32, 33, and then the right end of the document tray, that is, the tip in this case, is placed on the document platen glass. Before the document is sent out onto IO1, the rotation of the conveyor belt drive roller 9 is switched clockwise again based on the signal from the document passage detection sensor PS5 in which the leading edge of the document is reversed.

The above is a schematic configuration of a drive system to which power is transmitted by the drive motor M. Next, the operation of the drive system will be explained. Figures 7 (B) and (C) are schematic diagrams showing the document feeding and conveyance process, Figure 8 is a diagram showing the rotational speed of each paper feed roller by the drive system, and Figure 9 is a block diagram of the drive system. 10(A) and (B') are time charts. All these controls are performed by the CPU.

(2) When a stack of originals is stacked on the original table L and hits the original leading edge stopper ID stopped at the raised position, the original set detection sensor PS2 detects the presence or absence of originals and the ADF mode is set.

(2) When the width regulating plates IA, IA are moved and brought into contact with the width side edges of the document bundle, the document size detection sensor PS1 detects the document width, and the CPU converts and stores the document length.

(2) When the copy button 111 is pressed, a copy start signal is input, and the copying machine main body 100 and automatic document feeder are activated.

(2) This ADF activation signal applies voltage to the document setting solenoid SDI, which lowers the tip of the document tip stopper ID. At the same time, a voltage is applied to the paper feed solenoid SD2, and the pickup roller 2 descends to press the top layer of the document bundle.

(2) At the same time, when the drive motor M starts driving, the toothed pulley Pl on the motor drive shaft 20 rotates, and the intermediate shaft 21 having the toothed pulley P1 is rotated via the toothed belt B1. At this time, both 1 and 2 of the electromagnetic clutch are O.
The feed roller shaft 22 is driven and rotated by the rotation of the toothed belt B3, and the gears Gl, G2 .
The feed belt 3 is rotated via the feed roller 3A, and the pickup roller 2 is also rotated 11 by the toothed belt B4. At the same time, the toothed gooley P7 that meshes with the toothed belt B3 is also rotated, rotating the intermediate conveyance roller shaft 23, and the intermediate conveyance roller shaft 5 enters a rotating state.

At the same time, the toothed belt B2 wound around the intermediate shaft 21 rotates the conveyor belt drive roller 9 having the toothed pulley P5. As a result, the conveyor belt 8 wound between the roller 9 and the driven roller 10 is rotated. At this time, the circumferential speeds of the pick-up roller 2, the feed belt 3, the intermediate conveyance roller 5, and the conveyance belt 8 are all set to the high-speed conveyance mode v+ (for example, the circumferential speed V is −1200 m).
m/5ec) - Due to the rotation of each of the rollers and the rotation of the belt, the uppermost original Di of the bundle of originals on the original platen L is
is sent out by the big amplifier roller 2, separated by the feed belt 3 and the double feed prevention roller 4, and then
The original document D1 is separated and fed.

■ When the leading edge of the document Di that has been separated and fed passes the document passing detection sensor PS3, a leading edge passing signal is generated, and the clock timer starts timing from the generation of this signal, and after t3 has elapsed, the paper feed clutch is activated. Turn 2 off. As a result, after the leading edge of the document Di passes through the nip position of the intermediate conveyance roller 5, the driving rotation of the pickup roller 2 and the feed belt 3 is stopped, and the driving rotation becomes driven rotation.

■ The intermediate conveyance roller 5 is then rotated and the document DI
The document is fed, passes the document passage synchronization sensor PS5, and is then pinched by the rotating conveyor belt 8 and slides on the document table glass +01.

■ Timed from the time the original passes through the synchronization sensor PS5.
After 6, the document stopper solenoid SD3 is activated, and the document stopper 102 projects to the upper surface of the left end of the document table glass 101. This solenoid SD3 is of a latch type, and even if the power is turned off, the suction state is maintained unless reset.

(2) At the time before the leading edge of the document reaches the document stopper 102, that is, after t9 measured from the time when the document passes by the synchronization sensor PS5, the drive motor M is temporarily set to 0FFt, and the brake is applied to stop the document. However, due to inertia, each mold moving part continues to operate to some extent, and the document continues to be transported. Does this motor brake short-circuit both terminals of motor M?
Methods such as applying a reverse voltage are effective.

0 Thereafter, at approximately t8, the conveyor latch Kl is turned off, and the conveyor belt 8 is controlled to stop the conveyor belt 8. However, even here, the conveyance belt 8 moves while decelerating due to the inertia of the conveyance system, but since there is a document stopper 102, the document hits the document stopper 102 and stops.

Also, almost simultaneously with this time measurement t8, the black Z rotation is switched from high speed to low speed.

■ At time t10, turn on the paper feed clutch 2 and drive the drive motor M. As a result, the next document D2 is fed by the pickup roller 2 and the feed roller 3.

While the document is in a stationary state in the image exposure section, scanning exposure by the optical system 103 on the copying machine main body 100 side is started. At this time, before or during scanning exposure, the next original D
When the leading edge of the next document D2 passes the document notification detection sensor PS3, a detection signal is emitted and the clock timer measures time t (or the counter measures pulses). ), the original document D2 is stopped at a predetermined position and kept on standby. During this time, the feeding electromagnetic clutch 2 is ON.

Since the conveyance electromagnetic craft Kl is turned off, the preceding document DI that is being exposed is in a stopped state, but the subsequent document D2 is being fed in the low-speed conveyance mode v2 during this time, and its leading edge is on the document glass platen. It has reached the vicinity of 101 and is waiting. However, the operation during this time should be completed at least after the end of scanning and before the restart signal is generated.
For example, the speed of V2-500mm/5ea) is determined.

The above-mentioned subsequent document standby position is set differently depending on various document sizes, that is, the length of the document in the conveyance direction.

FIG. 7(B) is a schematic diagram showing the process of feeding and conveying the preceding original Di and the succeeding original D2.

Timing by the clock timer starts when the leading edge of the subsequent document D2 passes the document passage detection sensor PS3, and after t2, the paper feed clutch 2 is turned OFF and paper feeding is stopped. Next, the leading edge of the document D2 is connected to the document synchronization sensor P.
Time measurement by the clock timer from the time of passing S5 t
After lJ, the driving of the drive motor M is stopped. Note that the leading edge of the document D2 at the - time stop position S is located near the document table glass 101 and is not in pressure contact with the conveyor belt 8, so it is close to the trailing edge of the preceding document at a short distance. .

■ Next, at the end of the scanning exposure, from the copying machine main body 100
A DF start signal is issued and the exposure operation for the second original is performed. That is, by turning on the drive motor M and turning on the electromagnetic clutch Kl for conveyance, the preceding document Di is conveyed by the conveyor belt 8, and is discharged and placed on the paper discharge tray 14 via the paper discharge roller 13. Ru. At the same time, the subsequent document D2 slides from the standby position on the document table glass 101, and reaches the document stopper 102 at W in the stopping operation, thereby completing the document exchange. Clock timer 18 at this time
Document conveyance based on timing is in high-speed conveyance mode v1. The above is a description of normal operation, but next, the case where an abnormality such as a jam occurs will be explained with reference to FIGS. 9(A) and 9(B).

When the leading edge of the document reaches the document passing sensor PS3 and the document passing sensor PS3 is turned ON, it is the timing TI of the jam timer which measures time from the ADF start at the same time as the clock timer. Therefore, if the document passing sensor PS3 is not turned on by the jam timer timing TI, the CPU determines that the document has jammed before it reaches the document passing sensor PS3.

Also, when the leading edge of the document reaches the document synchronization sensor PS5 and the document synchronization sensor PS5 turns ON, the jam timer is counted at T2, so the document synchronization sensor PS5 is turned ON at time T2.
If it is not N, it is assumed that the document is jammed between the document passage sensor PS3 and the document synchronization sensor PS5.
U judges. Further, if both the document synchronization sensor PS5 and the document passage sensor PS3 are not turned off at the jam timer timing T5, it means that the document has not passed through both sensors, and the CPU determines that a jam occurred between them. This jam detection is the same for both the preceding document and the next document.

If the preceding original is stopped on the original platen 1 and the next original is fed while a copying operation is being performed and a jam as described above occurs, the CPU will detect the jam and immediately issue an AD
Although the paper feeding operation of F is stopped, the copying machine main body 100 continues the copying operation for the preceding document, and after this copying operation is all completed, that is, the transfer paper pl+ in FIG.
p2. ．． After all the sheets p3 are discharged onto the paper discharge tray H, control is performed so that a display or warning regarding the jam is performed.

This is a message display provided on the control panel 110 shown in FIG.

■ Clock timer t is activated by the above ADF start signal.
5. t6. t7. t8. t9. tlO and jam timer Tl, T2. T3. T4. T5 starts at the same time. Clock timer t5. t7 activates the setting of the document stopper solenoid SD3, and clock timer [5 and ill activate the reset of the solenoid SD3. In addition, the clock timer L8 is set to O of the transport latch Kl.
Emit FF signal. Furthermore, a clock timer t9. tl
O and t14 control ON/OFF of the drive motor M.

The second document D2 is conveyed from the above-mentioned - time stop position S to the document table glass l in high speed mode v1, and after being temporarily stopped at time t9, the second document D2 passes through the same process as described above, and is moved to the document stop 7 by inertia.
It hits the bar 102 and stops.

Thereafter, it is operated in the same manner as the preceding document DI, and is subjected to exposure processing and discharged.

In this example, two systems of drive systems, including one motor and two TJL magnetic clutches, were controlled and operated, but it is also possible to perform similar operations using two motors and one electromagnetic clutch. .

Also, when copying a double-sided original, when the original is reversely fed and reversed to the original reversing unit 30 and then transported to the original platen glass again, the timing starts from the passage detection of the reversed original passage detection sensor PS5, and the original is processed as described above. A similar effect can be obtained by setting a temporary stop position.

Furthermore, the above embodiment has two speeds: a low paper feed speed and a high transport speed.
Although the description has been made regarding an automatic document feeder having a step-change speed means, the present invention is not limited to this embodiment. Those that start feeding from the position,
It can also be widely applied to systems that start feeding the next original after the discharge of the preceding original is detected.

〔Effect of the invention〕

As described above, according to the automatic document feeder of the present invention, it is possible to reliably feed documents at high speed, which not only makes it possible to shorten document feed time but also stabilizes separation performance. In addition to being effective in improving the quality of copying and smoothing the conveyance of documents, it also makes it possible to eliminate wasted copies during copying even if an abnormality such as a jam occurs. In addition, the control program is simple because the document transport is controlled by the CPU by starting the motor, clutch, solenoid, and various timers based on the ADF start signal from the copying machine body, and by means of detecting the passage of the preceding document. It has the advantage of being clear, having fewer causes of malfunctions, and reducing manufacturing costs.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an image forming apparatus equipped with an automatic document feeder according to the present invention, FIG. 2 is a block diagram showing the document feed path, and FIG. 3 is a drive system (power transmission system) of the automatic document feeder.
FIG. 4 is a perspective view showing the document conveying system and drive system inside the apparatus, and FIG. 5 is a plan view of the main parts of the automatic document conveying device. Furthermore, FIG. 6 is an external perspective view of the upper part of the copying machine equipped with an automatic document feeder. Figure 7 (A), (B
), (C) is fg, a schematic diagram showing the document conveyance process, No. 6 is a diagram showing the rotation speed of each paper feed roller by the drive system, No. 9 is a diagram showing the rotation speed of each paper feed roller by the drive system,
The figure is a block diagram of the drive system, and FIGS. 10(A) and 10(B) are time charts of the document feeding and conveying process. 1... Original table IA... Width regulation plate IB
...Pinion gear 1c...Rack gear ID...
・Document leading edge stopper 2...Pickup roller 3...Feet held 3A...Feed roller 4...Double feed prevention roller 5...Intermediate conveyance roller 6
... Guide plate 8 ... Conveyor belt 9 ...
Conveying belt drive roller 13... Paper ejection roller 14... Paper ejection tray 3
0... Original reversing section 31, 32. 33... Conveyance roller group 34... Guide plate 100...
Copying machine main body 101...image exposure section (original table glass) 1
02... Original stopper 110... Control panel 111... Copy button 112... Message display Kl, K2... Electromagnetic clutch (MC) M...
Drive motor D... Original DI... Preceding original
D2...Subsequent original PSl...Original size detection sensor PS2...Original set detection sensor PS3...Original passage detection sensor PS4...Original discharge detection sensor ps5...'Original synchronization sensor

Claims (2)

[Claims] (1) A plurality of sheet-shaped originals are sequentially conveyed to the image exposure unit, the originals are stopped at a predetermined position in the image exposure unit, the optical system is moved to perform scanning exposure, and after the exposure, the originals are transferred to the image exposure unit. An automatic document feeder that transports a document to a paper ejection table, the automatic document feeder starts feeding a subsequent document before the exposure operation of the preceding document ends, and temporarily waits at a predetermined position in front of the image exposure section, the automatic document feeder comprising: A detection means for detecting the passage of the fed original is provided, and an operation to start feeding the next original is controlled based on a passage detection signal of the preceding original, and the original passing detection means stops at a temporary stop position. If an abnormality in document transport is detected, the abnormality is displayed by the detection signal after all copying operations of the preceding original on the copying machine main body side are completed. Features automatic document feeder. (2) The automatic document feeder according to claim 1, wherein the abnormality display is performed after the preceding document is ejected.