JPH08146674A - Automatic document feeder - Google Patents

Abstract

PURPOSE: To stop a document in a fixed stopping position with high accuracy by eliminating the need of the high accuracy in the detection of the document and imparting the degree of freedom in the attaching position of a sensor, at the time of making a both-face copy. CONSTITUTION: After a reverse sensor 28 detects the leading edge of the document A, it is carried by a reverse roller 22 by a distance L3 and then, by a carrying belt 18 driven with a driving source different from that of the reverse roller 22, by a distance L4 , to be stopped in the fixed stopping position 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic document feeder used in a copying machine or the like for copying double-sided originals, and more specifically, it accurately stops an original conveyed with its front and back reversed. The present invention relates to an automatic document feeder that can be operated.

[0002]

2. Description of the Related Art FIG. 5 schematically shows a conventional automatic document feeder for copying double-sided originals. The originals A are sent to the conveyor belt 50 one by one via an appropriate original feeding means (not shown). The transport belt 50 is the transport drive roller 5
1 and a conveyance driven roller 52, and the conveyance driving roller 51 is driven by a motor 53. The document A is conveyed while being sandwiched between the conveyance belt 50 and the platen 54, and is stopped when the rear end reaches a predetermined stop position 55. While the original A is stopped at the stop position 55, the original A is
Image is read by the main body of the copying machine. After the image reading is completed, the document A is sent to the downstream side by the conveyor belt 50, passes through the sensor 56, contacts the reversing roller 57 and the reversing roller 57, and three pinch rollers 58a that rotate in the opposite direction to the reversing roller 57. , 58b, 58c
Leading to. After that, the document A is conveyed along the reversing roller 57 as shown by arrows a, b, and c, and is turned over. After that, the sheet passes through the sensor 56 again, is sandwiched between the conveyor belt 50 and the platen 54, and is conveyed until the leading end thereof reaches the stop position 55.

In order to perform double-sided copying without shifting the image as the original A, it is necessary to accurately stop the original A at the stop position 55. For this reason,
Various methods have been taken. (1) A stopper is provided at the stop position 55 of the document A, and the conveyed document A is abutted against the stopper and stopped. (2) The distance L between the stop position 55 and the sensor 56 is converted into the number of pulses of the motor 53, and the sensor 56 displays the original A.
After detecting the tip of the
Drive and stop. (3) The distance (L-L1) obtained by subtracting the length L1 of the document A detected by an appropriate method from the distance L between the stop position 55 and the sensor 56 is converted into the number of pulses of the motor 53, and the sensor 56 is detected. Detects the trailing edge of the document A, then drives the motor 53 by the number of pulses and stops it. (4) In the above method (3), the length L1 of the document A is treated as a standard size for each group. (5) In the above method (3), in order to detect the length L1 of the document A with higher accuracy, the length L1 of the document A is detected by the reversing mechanism of the document A.

[0004]

[Problems to be Solved by the Invention] However, the above 5
Each of the two methods has the following problems.
In the method (1), there is a great possibility that the document is damaged when the document is abutted against the stopper. In the method (2), when the sensor 56 detects the leading edge of the document A, the document A
Is nipped between the reversing roller 57 and the pinch roller 58a, and the conveyance of the document A is governed by the rotation of a motor (not shown) that drives the reversing roller 57. Therefore, even if the stop position of the document A is controlled by the number of pulses of the motor 53, high accuracy cannot be expected. If the reversing roller 5
Even if the original A is stopped by a motor (not shown) for driving the original 7, if the original A moves away from the reversing roller 57 and moves to the conveyor belt 50, the original A is conveyed by the conveyor belt 5.
Since it is done by the motor 53 that drives 0, high accuracy cannot be expected.

In the method (3), a detection error of the length L1 of the document A directly affects the stop position, and therefore, there is a problem that a highly accurate length detecting means is required. For example, if the distance L is 100 and the actual length of the document is 30, it is assumed that the length detection unit detects the length L1 of the document as 20.
After the sensor 56 detects the trailing edge of the document A, L-L1
When the original is fed by a distance of 100-100, the leading edge of the original stops at a position 10 times past the stop position 55. Further, theoretically, there is a constraint that the mounting position of the reversing sensor 56 should be located on the downstream side of the pinch roller 58c which is the last nip means of the reversing roller 57, and the degree of freedom in design is limited. The method (4) does not require high precision for detecting the length of the document, but has a problem that it cannot cope with a document of an irregular size. Further, as in the case described above, there is a problem with the mounting position of the sensor 56. The method (5) also has the problem of the mounting position of the sensor 56. Further, even if the reversing roller 57 has a strong nip force and the slippage of the original document is extremely small, the original document length that satisfies the required accuracy of the original document stop position depending on the conditions such as the folded original document, the original document exposure, and the sensor performance. It is difficult to obtain detection accuracy.

The present invention has been made in view of the above problems and does not require high accuracy in detecting the length of a document when copying a two-sided document, and the sensor mounting position is not required. An object of the present invention is to provide an automatic document feeder capable of stopping a document at a predetermined stop position with a high degree of accuracy with a high degree of freedom.

[0007]

To achieve this object, an automatic document feeder according to the present invention comprises a document length detecting means for detecting the length L1 of the document in the feeding direction and a document conveyed by a predetermined distance. And a document reversing unit for reversing the document and sending it back to the first document conveying unit.
An original leading edge detection unit that is located at a distance L from the position where the original should be stopped and is located on the downstream side of the original reversing unit and that detects the leading edge of the original, and the original from the original leading edge detection unit to L1-L2 (L2 Is a second original conveying means for conveying a distance equal to the distance between the original inverting means and the leading edge detecting means) and the first original conveying means for conveying the original by a distance equal to L- (L1-L2). It is characterized by comprising a first control means for carrying.

The automatic document feeder according to the present invention also includes
An original length detecting means for detecting the length L1 of the original in the feeding direction, a first original conveying means for conveying the original by a predetermined distance, and an original inverting means for inverting the original and returning it to the first original conveying means. , L1 + L2 (where L2 is the above-mentioned document), which is located at a distance L from the position where the document should be stopped and which is located upstream of the document reversing unit and detects the leading end of the document. The second original conveying means for conveying the original by a distance equal to the distance between the original reversing means and the leading edge detecting means) and the original are L- (L
1 + L2) and a first control means for carrying the first original carrying means by a distance equal to (1 + L2).

The first original feeding means includes a first driving means for driving the first original feeding means, and the first driving means is controlled according to the number of pulses generated by the first control means. It is preferably one.

The second original feeding means comprises a second driving means for driving the second original feeding means and a second control means for controlling the second driving means, and the second driving means. The second control means is preferably controlled according to the number of pulses emitted.

[0011]

The length L1 of the document in the feeding direction is detected by the document length detecting means and stored in the memory in the microprocessor. The original is conveyed by the first original conveying means over the platen by a predetermined distance and stopped. In the case of the double-sided copy mode, the document reversing unit operates to reverse the front and back of the document, and returns the document to the first document conveying unit.

When the document leading edge detecting means for detecting the leading edge of the document is installed at a position separated by a distance L from the position where the document should be stopped downstream of the document reversing means, the document is fed by the second document feeding means. From the document leading edge detecting means
1-L2 (L2 is the distance between the document reversing means and the document leading edge detecting means) is conveyed by the second document conveying means, and further L- (L1-L by the first document conveying means.
Transported by a distance equal to 2).

When the document leading edge detecting means is installed upstream of the document reversing means, the document is transported by the second document transporting means by the second document transporting means by a distance equal to L1 + L2 from the document leading edge detecting means. Then, the first original conveying means conveys the sheet by a distance equal to L- (L1 + L2).

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the automatic document feeder according to the present invention will be described with reference to FIGS. The automatic document feeder shown in FIG. 1 includes a document stacking tray 1 on which a document A is placed, and a document pressing plate 2 is arranged on the downstream side of the document stacking tray 1. The document pressing plate 2 is connected to the motor 3 via a cam mechanism (not shown), and the document pressing plate 2 is connected to a sheet feeding solenoid 4 (see FIG. 2). While the motor 3 is rotating, the document pressing plate 2 is raised or lowered by turning the paper feeding solenoid 4 on or off.

A paper feed drive roller 5 and a paper feed driven roller 6 are arranged opposite to the original pressing plate 2, and a paper feed belt 7 is stretched over both rollers 5, 6. The paper feed drive roller 5 is driven by the motor 3 via the belt 3A, and the drive force of the motor 3 drives the paper feed belt 7. The paper feed belt 7 has a paper feed clutch 8 (see FIG. 2).
Are connected, and the paper feed belt 7 is rotated or stopped by turning on or off the paper feed clutch 8.

On the downstream side of the document pressing plate 2, a double feed preventing roller 9 is arranged in contact with the paper feeding belt 7. The double feed prevention roller 9 is adapted to rotate only in the upstream direction.

A pair of registration rollers 10a and 10b is arranged downstream of the paper feed drive roller 5. The roller 10a is connected to the motor 3 via a registration clutch 11 (see FIG. 2), and the roller 10b is rotated by being driven by the roller 10a. By turning the registration clutch 11 on or off, the registration roller pair 1
0a and 10b rotate or stop. In addition, the pair of registration rollers 10a and 10b are the pulse encoder 12 (see FIG.
See). A registration sensor 13 is arranged between the paper feed drive roller 5 and the pair of registration rollers 10a and 10b. The registration sensor 13 detects the passage of the document A and determines the timing of the registration operation by the pair of registration rollers 10a and 10b. taking it.

Further, the pair of registration rollers 10a, 10
A document passage sensor 14 is arranged on the downstream side of b. The document passage sensor 14 detects the passage of the document and detects the length of the document A sent in the feed direction based on the number of pulses generated by the encoder 12 (see FIG. 2) of the pair of registration rollers 10a and 10b.

A platen 15 extends on the downstream side of the pair of registration rollers 10a and 10b in the document conveying direction. A transport driving roller 16 and a transport driven roller 17 are arranged at both ends of the platen 15, and both rollers 1
A conveyor belt 18 is stretched around 6 and 17. The transport driving roller 16 is connected to the stepping motor 19 via a belt 19A and is driven by the stepping motor 19. A document stop position 20 is set at a position near the transport driving roller 16 of the platen 15, and the document A sent via the pair of registration rollers 10a and 10b has its rear end positioned on the document stop position 20. It is configured to stop on the platen 15. While the document A is stopped on the platen 15, the copying machine body reads the image on the surface of the document A.

A document discharging mechanism is arranged downstream of the platen 15. In the single-sided mode in which only one side of the document A is copied, the document discharge mechanism discharges the document A sent from the platen 15 onto the discharged document table 21 and outputs the document A.
Platen 15 in duplex mode for copying both sides of
The original A sent from is turned inside out and sent back to the platen 15. The document discharging mechanism will be described below.

A reversing roller 22 is arranged above the conveying driven roller 17 on the downstream side. The reversing roller 22 is connected to the motor 3 via the belt 3B and the reversing clutch 23 (see FIG. 2) and is driven by the motor 3. That is, by turning the reversing clutch 23 on or off, the reversing roller 22 rotates or stops. The reversing roller 22 is a pulse encoder 24.
(See FIG. 2). Furthermore, the reversing roller 22
Drives the paper discharge roller 25 via the belt 22a. Further, three pinch rollers 26a, 26b, and 26c are rotatably contacted around the reversing roller 22 so that the fed document A is nipped by the reversing roller 22.

Transport driven roller 17 and reversing roller 22
A paper discharge sensor 27 and a reversal sensor 28 are arranged between and. The paper discharge sensor 27 detects the passage of the document,
This is to set the timing of the registration operation when reversing the original and the timing of the original discharging operation. Further, the reversing sensor 28 is similar to the paper discharge sensor 27 in that it detects a document, but the reversing sensor 28 serves as a reference position of the document stop position in the double-sided mode.

As shown in FIG. 3, restriction pawls 29a and 29b are arranged downstream of the reversing roller 22. The regulating pawls 29a and 29b are supported so as to be pivotable about fulcrums 30a and 30b, respectively, and the movement of the regulating pawls 29a and 29b is reversed by a reverse discharge solenoid 31 (see FIG. 2) connected to the regulating pawls 29a and 29b. ) Is turned on or off. That is, in the single-sided mode,
The reverse discharge solenoid 31 is turned off. In this state, the two regulating claws 29a and 29b are separated from each other, as shown in FIG. 3B, and the document A passes between the two regulating claws 29a and 29b and is ejected. The document is discharged onto the document table 21. On the other hand, in the double-sided mode, the reverse sheet discharge solenoid 31 is turned on. In this state, the two regulating claws 29a and 29b are in contact with each other, as shown in FIG. 3A, and the document A passes between the regulating claw 29b and the reversing roller 22 and again. It is conveyed to the platen 15.

As shown in FIG. 2, the motor 3 and the stepping motor 19 are each an encoder 3 for control.
1, 32 are provided. The automatic document feeder also has a microprocessor 40 for controlling the operation of the entire apparatus.
It has. The microprocessor 40 includes encoders 12, 24, 31, 32 and a registration sensor 1
3, passage sensor 14, paper discharge sensor 27, reversal sensor 28
Signals from the motor 40, the microprocessor 40, based on these signals, the motor 3, the sheet feeding solenoid 4, the sheet feeding clutch 8, the registration clutch 11, and the reversing clutch 2.
3, stepping motor 19, reverse discharge solenoid 3
A control signal is sent to 1 to control these.

The operation of the automatic document feeder having the above structure will be described below. After the document A is placed on the document stacking tray 1, the motor 3 is driven. Next, the paper feed solenoid 4 is turned on, the pressing plate 2 is raised, and the document A on the document stacking tray 1 is pressed against the paper feed belt 7. After the pressing plate 2 completely presses the document A, the paper feed clutch 8 is turned on and the paper feed belt 7 is rotated to start the conveyance of the document A.

When the registration sensor 13 detects the leading edge of the conveyed document A, the sheet feeding solenoid 4 is turned off to lower the pressing plate 2 and prevent the document from being double-fed. In addition, the registration roller pair 1 is used until a predetermined timing after the registration sensor 13 detects the leading edge of the document A.
0a and 10b are stopped, and the original A is made to have a loop for straightening.

At the predetermined timing, the registration clutch 11 is turned on, the pair of registration rollers 10a and 10b are rotated, and the document A is fed further into the interior. Passage sensor 14
However, when the leading edge of the document A sent via the pair of registration rollers 10a and 10b is detected, both the paper feed clutch 8 and the registration clutch 11 are turned off, and the paper feed belt 7
And the pair of registration rollers 10a and 10b are stopped, and the document A is made to stand by at that position.

The length of the original A is detected by the registration roller pair 10 while the passage sensor 14 detects the original A.
This is performed by counting the number of pulses of the encoder 12 synchronized with a and 10b. Therefore, the encoder 1
The count value C1 of the pulse number of 2 is the microprocessor 4
0 is stored in the memory.

Further, both the paper feed clutch 8 and the registration clutch 11 are turned on to rotate the paper feed belt 7 and the registration roller pairs 10a and 10b, and at the same time, the stepping motor 19 is activated to rotate the conveyor belt 18. , The original A is conveyed to the downstream side. At this time, the paper feeding belt 7
Is also driven by the registration roller pair 10a, 10b
This is to prevent the original A from being damaged due to the load on the paper feed belt 7 when the original A starts to be pulled downstream. Therefore, the paper feed belt 7 does not need to be driven until the original A has been transferred to the transport belt 18, and the paper feed clutch 8 may be turned off at a predetermined time to stop the rotation of the paper feed belt 7.

Original A whose passage sensor 14 is sent to the downstream side
When the rear end of the vehicle is detected, the registration clutch 11 is turned off,
The pair of registration rollers 10a and 10b are stopped. The document A is conveyed again from the standby state, and the passage sensor 14
Counts the number of pulses of the encoder 12 synchronized with the pair of registration rollers 10a and 10b until the trailing edge of the document A is detected, and this count value C2 is counted value C1 stored in the memory of the microprocessor 40. The length L1 of the document A in the feed direction is determined by adding to.

Next, after the passage sensor 14 detects the trailing edge of the document A, the stepping motor 19 is operated by the number of pulses corresponding to the distance between the passage sensor 14 and the stop position 20.
Rotates. As a result, the document A stops with its trailing edge positioned on the document stop position 20 on the platen 15. When the passage sensor 14 detects the rear end of the document A,
Since the document A has already passed through the pair of registration rollers 10a and 10b and is transported by the transport belt 18 driven by the stepping motor 19, the document stop position 20 is set.
It can be stopped with high precision.

The reverse sheet discharge solenoid 31 is turned on, and the regulating claws 29a and 29b are pivoted as shown in FIG. 3 (A) to set the conveying passage for the double-sided mode. After that, the stepping motor 19 is driven and the conveyance belt 18 conveys the document A stopped at the document stop position 20 to the downstream side.

After the paper discharge sensor 27 detects the leading edge of the document A, the reversing roller 22 is stopped for a certain period of time, and the reversing roller 22 and the pinch roller 26a form a loop for correcting the bend in the document A. Let

After a lapse of a certain time, the reversing clutch 23 is turned on and the reversing roller 22 is rotated, so that the document A
Is nipped between the reversing roller 22 and the pinch roller 26a. After this nip stepping motor 19
Is reversed, and the conveyor belt 18 is reversed.

As shown in FIG. 3 (A), the document A is guided by the regulating claw 29b and is discharged from between the reversing roller 22 and the pinch roller 26c while being turned upside down.
As shown in FIG. 4, the reversing sensor 28 and the document stop position 20
Is L, the length of the document A is L1, and the reversal sensor 2 is
8 and the distance between the pinch roller 26c are L2, L3 =
Let L1-L2 and L4 = L-L3. When the reversing sensor 28 is on the downstream side of the pinch roller 26c as in the present embodiment, L3 = L1-L2 is defined. Conversely, the reversing sensor 28 is on the upstream side of the pinch roller 26c. In this case, L3 = L1 + L2 is defined.

The distance L3 is converted into the number of pulses of the encoder 24 of the reversing roller 22 and designated as P1, and L4 is converted into the number of pulses of the stepping motor 19 and designated as P2.

First, from when the reversing sensor 28 detects the leading edge of the document A (FIG. 4A), when the reversing roller 22 rotates by the number of pulses P1 (that is, the document A has a distance L3).
Only when the document is conveyed toward the document stop position 20 (see FIG.
Starting from (B)), the stepping motor 19 rotates by the number of pulses P2 and stops. As a result, the original A
Further advances by a distance L4, and the document A stops when the leading edge of the document A reaches the document stop position 20 (FIG. 4).
(D)).

While the document A is stopped on the platen 15, the main body of the copying machine reads the image on the back surface of the document A. After the reading is completed, the transport belt 18 rotates in the forward direction, and the document A is sent to the reversing roller 22. After a lapse of a predetermined time after the discharge sensor 27 detects the trailing edge of the document A, the fixed amount of the trailing edge of the document A is nipped by the regulating claws 29a and 29b as shown in FIG. To prevent the paper from popping out too much
The originals A ejected on the first side are aligned. After the discharge sensor 27 detects the trailing edge of the document A, the timing at which the discharge of the document A to the discharged document table 21 is completed is measured, and the regulating claw 29
A and 29b are returned to the state of FIG. 3 (B). This completes the copying of both the front and back sides of the original A.

The force with which the reversing roller 22 nips the original A is significantly larger than the force with which the conveyor belt 18 conveys the original A. For this reason, in the state where the document A straddles both the reversing roller 22 and the transport belt 18, the document A is controlled by the nip force of the reversing roller 22.

Therefore, in the present embodiment, when the document A is in the area controlled by the reversing roller 22 driven by the motor 3, the conveyance amount of the document A is controlled by the rotation amount of the reversing roller 22, When the document A is in the area controlled by the transport belt 18 driven by the stepping motor 19, the transport amount of the document A is controlled by the rotation amount of the stepping motor 19. In this way, by controlling the conveyance amount of the document A by the motor 3 and the stepping motor 19 according to the position of the document A, even if the rotation speeds of the motor 3 and the stepping motor 19 fluctuate asynchronously, the document A It does not affect the stop position of.

As described above, the conventional automatic document feeder has a design restriction on the sensor position and a problem in the accuracy of detecting the document length. In the present invention, the number of pulses P1 is determined by the detected document length L1, and P2 is determined so that L = P1 + P2. Therefore, even if the detected value of the length of the document includes an error, L is kept constant only by changing the ratio of P1 and P2.

For example, the distance L is 100 and the actual length of the original is 3.
Assuming that the detected original length L1 is 20, and the detected original length L2 is 5, the distance L1-L2 = where the reversing roller 22 should feed the original A after the paper ejection sensor 27 detects the leading edge of the original A.
20-5 = 15, and then the distance L- (L1-L2) = 100-15 at which the conveyor belt 18 should send the original A.
Send only = 85. When the reversing sensor 28 is located upstream of the pinch roller 26c, the reversing roller 22 sends the original A by the distance L1 + L2 = 20 + 5 = 25 after the paper ejection sensor 27 detects the leading edge of the original A. Then, the distance L- (L
1 + L2) = 100−25 = 75 is sent. In this way, even if the length of the document A includes an error, the distance L to which the document A should be sent can be kept constant.

It should be noted that it is conceivable that the stop position of the original A may be affected by the error in the detection of the length of the original and the timing of changing the transfer belt 18 from the reversing roller 22 to the wrong position. Only the influence of the speed difference between the motor 3 and the stepping motor 19 affects the stop position. Also in the present invention, the reading error of the sensor affects the stop position of the document A, as in the prior art. However, in the prior art, a double error is included in the reading of the leading edge and the trailing edge of the document, but in the present invention, only the reading error of the document leading edge is included, and the influence of the reading error on the stop position is extremely small.

In this embodiment, the conveyor belt 1
Although 8 is open-loop controlled by the stepping motor 19 and the reversing roller 22 is closed-loop controlled by the encoder 24, it is also possible to use other control methods. Further, the present invention is not limited to the document reversal control, but is also effective for the control of the document movement amount when the document passes through the control area by the different driving sources.

[0045]

According to the automatic document feeder of the present invention, it is not necessary to detect the length of the document with high accuracy, and the degree of freedom of the mounting position of the sensor is improved, and the document is moved to a predetermined stop position. It can be stopped with high precision.

[Brief description of drawings]

FIG. 1 is a sectional view of an automatic document feeder according to a first embodiment of the present invention.

FIG. 2 is a block diagram of the automatic document feeder of FIG.

FIG. 3 is a schematic view of a document front / back reversing mechanism in the automatic document feeder of FIG.

4 is a schematic view showing the operation of the automatic document feeder of FIG.

FIG. 5 is a schematic view of a conventional automatic document feeder.

[Explanation of symbols]

 1 Document Loading Tray 2 Pressing Plate 3 Motor 7 Feeding Belt 10a, 10b Registration Roller Pair 13 Registration Sensor 14 Passage Sensor 15 Platen 18 Conveyor Belt 19 Stepping Motor 20 Document Stop Position 21 Discharged Document Platen 22 Reversing Roller 22a Belt 26a, 26b , 26c Pinch roller 27 Paper ejection sensor 28 Inversion sensor 29a, 29b Restriction claw 40 Microprocessor

Claims (4)

[Claims] 1. A document length detecting means for detecting a length L1 of a document in a feeding direction, a first document transporting means for transporting a document by a predetermined distance, and a document being turned upside down to the first document transporting means. An original reversing means for returning the original, an original leading edge detecting means for detecting the leading edge of the original located at a distance L from the position where the original should be stopped and located downstream of the original reversing means, and the original from the original leading edge detecting means. , L1-L2 (L2
Is a second original conveying means for conveying a distance equal to the distance between the original inverting means and the original leading edge detecting means), and the first original conveying means for conveying the original by a distance equal to L- (L1-L2). An automatic document feeder, which comprises: 2. An original length detecting means for detecting the length L1 of the original in the feeding direction, a first original conveying means for conveying the original by a predetermined distance, and an original being turned upside down to the first original conveying means. An original reversing means for sending back, an original leading edge detecting means for detecting the leading edge of the original located at the upstream side of the original reversing means at a distance L from the position where the original should be stopped, and an original for the original leading edge detecting means. L1 + L2 (L2 is a distance between the document reversing unit and the document leading edge detecting unit), and a second document conveying unit that conveys the document, and a document is conveyed by a distance equal to L- (L1 + L2). An automatic document feeder comprising: a first control unit that conveys the document by means. 3. The first original feeding means comprises first driving means for driving the first original feeding means, and the first driving means is controlled according to the number of pulses emitted by the first control means. The automatic document feeder according to claim 1 or 2, wherein the automatic document feeder is provided. 4. The second original feeding means comprises a second driving means for driving the second original feeding means, and a second control means for controlling the second driving means. 3. The automatic document feeder according to claim 1, wherein the means is controlled according to the number of pulses generated by the second control means.