JP3191233B2 - Automatic document feeder and method - Google Patents

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 and method, and more particularly, to an apparatus and method for automatically feeding a document to a reading position in a recording device such as an electrophotographic copying machine or an image reading device. It is about improvement.

[0002]

2. Description of the Related Art An automatic document feeder is generally used by mounting it on a platen glass (original platen glass) of an image exposure section of a copying machine or the like. In an optical system movable copier equipped with this automatic document feeder, the automatic document feeder feeds out one sheet at a time from a document table (stack section) on which a sheet-like document (hereinafter simply referred to as a document) is placed. The document is fed onto a platen glass by a transport belt, where the document is exposed by an exposure unit lamp in the copying machine main body, and further conveyed to a document discharge table.

[0003]

A document exchange operation on a platen glass by such an automatic document feeder has conventionally been performed after a discharge sensor detects that a document on the platen glass has been discharged. The next original is sent out from the stack unit, transported onto the platen glass, and stopped at a predetermined position. For this reason, the document replacement time is increased, and thus the copy processing time is required, and the copy productivity is reduced.

At the time of a document exchange operation in which an original is automatically fed and discharged onto a platen glass using an automatic document feeder,
If the original is replaced within the return time of the scanning optical system, the copy productivity becomes 100% and no time is required. For this purpose, it is necessary to increase the document conveyance speed from the document double feed prevention position of the stack portion to the document stop position on the platen glass surface.

[0005] However, when the document conveying speed is increased, various problems such as an increase in the size of the motor, an increase in power consumption, generation of noise, abrasion of the conveying belt, an increase in the degree of document breakage, and a decrease in document separating performance occur. . When copying a two-sided original, the two-sided original is conveyed onto a platen glass, the first side of the original is exposed, and the original is turned over by a reverse conveying means.
The document is again conveyed onto the platen glass to expose the second surface of the document, and then the document is turned over again by the sheet discharge reversing means and discharged outside the apparatus in a state where the pages are aligned. In such a two-sided automatic document feeder, the distance between the trailing edge of the first document and the leading edge of the second document is large, and the travel distance of the next document during document replacement or reverse transport is increased. There is a disadvantage that the required time increases.

As a technique capable of solving such a problem, the present applicant first separates and feeds the next original from the original mounting table during the reading operation of the second side of the preceding original (the stop state of the transport belt). When the operation of reading the second side of the preceding document is completed and the preceding document is discharged, the next document that has been kept waiting is read. An automatic document feeder configured to be conveyed to a position has been proposed (see Japanese Patent Application No. 3-330736).

However, in such a configuration, the positional relationship between the reading section on the platen glass and the upstream end of the conveyor belt (the distance from the upstream end of the conveyor belt to the reading position).
Since the distance between the leading edge of the next document and the trailing edge of the preceding document is restricted, there is a problem that the interval between the preceding document and the next document cannot be shortened to further reduce the document replacement time. there were.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has the following problem of causing a next document to wait at a position as close as possible when reading the second surface of a preceding document without being restricted by the transport distance of the transport belt. It is an object of the present invention to shorten the time required for document replacement and thereby improve the copy processing speed. It is another object of the present invention to stabilize the feeding and discharging operations of the next original from the original plate while realizing the shortening of the original exchange time.

[0009]

SUMMARY OF THE INVENTION Therefore, an automatic document feeder according to the present invention separates documents one by one from a bundle of documents stacked on a document table and transports the documents to an image reading section for reading a document image. Transporting means, reversing means for reversing the front and back of the document, second transporting means for transporting the document from the image reading unit to the reversing means, and transporting the document from the reversing means to the image reading unit And a discharge unit for conveying the original from the image reading unit to a discharge stack unit. Before the reading of the first side of the preceding original is completed, the first original is transferred to the first original. Is conveyed to a first standby position by the conveyance means, and after the reading of the first surface of the preceding document is completed, the next document is started to be conveyed from the first standby position;
Conveying the preceding document to the image reading unit for reading the second surface and simultaneously conveying the next document to a second standby position, and discharging the preceding document from the image reading unit to the discharge stack unit Then, the next original is conveyed from the second standby position to the image reading unit in parallel with the preceding original.

Here, when the transport paths in the first, second and third transport means have a common portion, the first
The standby position may be located at a position other than the common portion of the transport path in the first transport unit. In addition, it is preferable that the posture of the document is corrected by an operation of making the document stand by at the first standby position.

Further, when the second transport means is constituted by an endless belt stretched over two axes, the second standby position is such that the leading end of the next document in the transport direction is the endless belt. It is preferable that the position be in contact with. Further, it is preferable that the discharge operation of the preceding document conveyed to the paper discharge unit after the completion of the reading is completed from the first surface reading of the next document to the completion of the second surface reading operation in the image reading unit.

Further, it is also possible to adopt a configuration in which the discharge stack portion is a document placing table, and the document discharged by the sheet discharging means is circulated to the document placing table. On the other hand, the automatic document feeding method according to the present invention is a method of separating documents one by one from a document bundle loaded on a document table and transporting the documents to an image reading unit that reads a document image. Separating and transporting the preceding document to the image reading unit, reading the first surface of the preceding document, and simultaneously transporting the next document to the first standby position,
To read the second side of the preceding document, the preceding document is turned upside down and transported to the image reading unit, and at the same time, the next document is transported to the second standby position, and the second surface of the preceding document is At the same time, the preceding document is discharged from the image reading section to the discharge stack section, and at the same time, the next document is transported from the second standby position to the image reading section along with the preceding document.

[0013]

According to the automatic document feeder and method of the present invention, the next document is transported to the first and second standby positions in parallel with the transport of the preceding document, thereby shortening the document replacement time. Further, since the next original is separated and fed from the original placing table and is waiting at the first standby position, the separation of the next original from the original placing table and the transport to the second standby position are continuously performed. The transfer to the second standby position can be performed from a state in which the separation of the next document from the document mounting table is surely completed.

Further, since the first standby position is set to a position which does not interfere with other conveyance, for example, it does not hinder the reversal of the preceding document, and the standby state at the first standby position is stabilized.
Thus, the transfer to the second standby position can be performed smoothly. Also, when the document is caused to stand by at the first standby position, there is sufficient time, so if the posture of the document is corrected here,
Posture correction is performed well.

Further, in the second conveying means constituted by an endless belt stretched on two axes, the second standby position of the next original is set to a position where the leading end of the next original in the conveying direction contacts the endless belt. In this way, the next document can be brought close to the previous document as much as possible without being restricted by the transport distance of the endless belt, etc. It is easy to transport the next original document to the image reading unit.

Further, the discharge operation of the preceding document conveyed to the discharge means after the completion of the reading is completed from the first surface reading of the next document to the second surface reading operation of the next document in the image reading section. For example, by using the reading time or the reversing time of the next document, the time required for paper discharge can be increased, and the conveyance speed of the paper discharging means can be made slower than the speed at the time of document replacement, thereby improving the alignment of the discharged paper. .

Further, instead of separately providing the paper discharge stack section and the document placing table, the document can be circulated by discharging the read document to the document placing table.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an overall configuration diagram of an image recording apparatus (copier) equipped with an automatic document feeder according to the present invention. In FIG. 1, 1 is a copying machine main body, 2 is a scanning exposure optical system, 3 is an image forming means around the photosensitive drum 31, 4 is a copy paper supply means, 5 is a copy paper transport means, 6 is a fixing device, 7 Is a reverse paper discharge switching means, 8 is a reverse conveyance means, 9 is a double-sided recording paper conveyance means (ADU), and 10 is an automatic document conveyance device (RADF) with a double-sided document automatic reversal function.

FIG. 2 shows the automatic document feeder according to the present invention.
FIG. 3 is a configuration diagram showing a drive system (power transmission system) of the automatic document feeder 10. The above automatic document feeder
Reference numeral 10 is installed on the copying machine main body 1 as shown in FIG.
Paper feed unit 12 (paper feed unit) that separates and sends out two originals D
An intermediate transport unit 13 that transports the original D fed from the paper feed unit 12, a transport unit 15 that transports the original transported by the intermediate transport unit 13 to a predetermined reading position on the platen glass 21, The reversing means 14 inverts the original conveyed in the reverse direction by the conveying means 15 and feeds the reversal original to the conveying means 15 again. And a sheet reversing section 16 (sheet discharging means) for discharging to the paper stack section or returning to the document table.

Here, the paper feed section 12, the intermediate transport section 13, and the transport section 15 constitute a first transport section, and the transport section 15 constitutes a second transport section. Further, a third transport unit is constituted by the intermediate transport unit 13 and the transport unit 15. Therefore, in the present embodiment, the first, second, and third
Has a common part in the transport path. A stack tray (document placement table) 110 for stacking a bundle of documents is fixed to the document placement unit 11.
A width regulating plate 111 for regulating the width of the document is movably provided.

When a stack of documents is placed on the stack tray 110, the presence or absence of a document on the stack tray 110 is detected by a document set detection sensor (zero document detection sensor) PS1. The mode is displayed. When the document bundle is placed at a predetermined position, the document size (B5 to A3) is
This is detected by S2 and input to the control unit of the copying machine body 1.

A movable pressing plate 112 is supported at the leading end of the stack tray 110 on the downstream side of the document feeding so as to be able to swing up and down around the swing shaft 114.
A drive plate 118 is fixed to the swing shaft 114 with a screw, and the swing shaft 114 and the drive plate 118 swing integrally. Further, an elastically deformable member (for example, a torsion spring) 119 is wound around the swinging shaft 114, and both ends thereof are connected to the driving plate.
The movable pressing plate 112 can be pressed upward at the center and the movable pressing plate 112 can be pressed upward at the center.

The driving plate 118 is provided with two actuator portions, and one of the actuator portions turns on / off an optical path of a pressing plate detection sensor (for example, a photo interrupter) PS3 fixed to the movable pressing plate 112. . The other actuator unit turns on and off the optical path of a sensor (for example, a photo interrupter) PS4 fixed to the fixed bottom plate 116, and detects the home position of the drive plate 118.

A feeding section 12 is provided on the downstream side of the movable pressing plate 112 for document feeding. The feeding section 12 includes a document leading end stopper 120, a driving roller 121, a driven roller 122, a feed belt 123 that winds around these rollers and rotates, and a double feed prevention reverse roller 124 located below the feed belt 123. I have. The drive roller 121 has a drive motor M2
Is transmitted via the electromagnetic clutch CL1.

An intermediate transport section 13 that rotates in the forward direction is provided downstream of the document feed section 12 in the document transport direction. The intermediate transport unit 13 includes:
First intermediate transport roller pair 130 driven by drive motor M2 via transport clutch CL5, document passage detection sensor PS
5. A curved guide plate 131, a second intermediate transport roller pair 132 which is always driven to rotate forward by a one-way clutch CL3.
A transport path for transporting to one end of 21 is formed.

A reversing means 14 is provided below the second intermediate conveying roller pair 132 and to the right of the platen glass in the figure. The reverse transport roller 141 is a one-way clutch C
L3 is built in and is always driven to rotate forward. Reference numeral 142 denotes a curved guide plate that connects each nip position between the second intermediate transport roller pair 132 and the reverse transport roller pair 141, and forms a document reversal feed path. A reversal detection sensor PS7 is provided in a part of the reversal feed path, and detects the passage of the reversal fed document.

On the surface of the platen glass 21, a transport belt 151 (endless belt) is driven by a driving roller 152 and a driven roller.
153 (two axes), a transport means which is rotatably stretched between three document pressing rollers 154 and a tension roller 155
15 are provided. On the axis of the drive roller 152,
The clutch CL2 and the brake BRK are pivotally supported, and the drive roller 152 is operated by the drive force of the drive motor M2.

The paper discharge reversing section 16 includes a paper discharge roller 160, a switching claw.
161, multiple transport rollers 162, 163, 164 and guide plate 1
65, 166, 167, etc. Discharge rollers 160,
The transport rollers 162 to 164 are driven by a paper discharge motor M3. The discharge roller 160 and the transport roller 162 are driven to rotate forward and the transport rollers 163 and 164 are driven to rotate forward and reverse.
The switching claw 161 is driven by a solenoid SOL.

FIG. 9 is a block diagram showing the electrical configuration of the automatic document feeder 10. In FIG. 9, motors M1, M2 and M3 for driving the rollers for document conveyance, clutches CL1 to CL5, brake BRK, and a solenoid SOL for driving the switching claw 161 are connected to a control unit (CPU) via an interface circuit. Is done. The interface circuits further include sensors PS1 to PS4 for detecting document conveyance.
PS10 and encoders 1 to 3 are connected. Further, the operation unit is connected to the control unit (CPU).

Through the interface circuit, the sensor,
The control unit (CPU) that receives the signal from the encoder performs arithmetic processing based on the received signal and the signal of the operation unit, and controls the driving of each motor, clutch, and solenoid. The control unit performs a control operation based on a control program stored in the ROM. When operations such as start of copying, switching of the original reading mode, selection of the discharge mode, and the like are performed on the operation unit, signals corresponding to the respective operations are supplied to the control unit (CPU).

FIGS. 4A to 6L are schematic diagrams for explaining the operation of feeding, transporting, and discharging a plurality of double-sided documents D (documents having images on both sides). The dashed line in the drawing indicates the conveyance path of the double-sided document D. FIGS. 7 and 8 are time charts of a document feeding and conveying operation process of the automatic document feeder (RADF) of the present embodiment. Hereinafter, the document feeding operation will be described.

(1) In the state shown in FIG. 3, when the main switch of the copying machine main body 1 is turned on, the pressing motor M1 is rotated, and the movable pressing plate 112 detects the initial stop position by the home position detecting sensor PS4. Then, the pressing motor M1 is stopped. That is, the home position detection sensor PS4 is turned on at the home position.

If the main switch is on and the home position detection sensor PS4 is off, the pressing motor M
1 to reversely move the movable pressing plate 112 to detect that the home position detection sensor PS4 is turned on, stop the pressing motor M1, and move the driving plate 118 and the movable pressing plate 112 to the lowest initial positions. To stop. If the home position detection sensor PS4 is on, the pressing motor M1 is rotated forward once, the home position detection sensor PS4 is turned off to raise the movable pressing plate 112, and then the motor M1 is rotated in reverse. When the sensor PS4 is turned on, the motor M1 is turned on.
To stop and return to the home position. This is effective for absorbing the time lag between the driving gear and the sensor ON. At the home position stop position, a clearance capable of accommodating a predetermined maximum amount of the document bundle is held.

(2) Stack tray 110 and movable pressing plate
When the original bundle D is placed on the original 112, the original set detection sensor PS1 is turned on, and the ADF mode (automatic original transport mode) is set. At the same time, the document size sensor PS2 is turned on to detect the document size. (3) When the copy button is turned on, ADF and copying can be started, and the pressing motor (stepping motor)
M1 starts driving rotation, and the movable pressing plate 112 is driven by the elastically deformable member 119 and the driving member 118 fixed to the swing shaft 114.
Swings to raise its leading end, and lifts the stacked document stack D. During this rising process, the swing angle of the swing shaft 114 is detected by counting the pulse count by a rotary encoder or the like.

(4) When the upper surface of the original bundle D stacked on the movable pressing plate 112 is pressed against the outer peripheral surface of the feed belt 123, the movable pressing plate 112 stops while holding the original bundle. The driving plate 118 is further driven and rotated to rotate counterclockwise in the figure while compressing the elastically deformable member (torsion spring) 119, and the distance between the movable pressing plate 112 and the driving plate 118 is reduced.

(5) When the distance reaches the set distance, the actuator section at one end of the drive plate 118 turns on the press detection sensor PS3 fixed to the movable press plate 112, and reaches the initial set pressure (for example, 50 g). Further, the pressing force is increased by the driving of the driving plate 118, and when the movable pressing plate 112 is counted to a predetermined pressing force (for example, 100 g), the driving of the pressing motor M1 is stopped.

With the above operation, preparation for sending the original document is completed.
Subsequently, document feeding is started. Next, the operation of feeding a two-sided original will be described. Note that, for simplicity of description, a document bundle composed of two double-sided documents D1 and D2 will be described below. (A) FIG. 4A is a schematic diagram showing a document conveyance path of the automatic document conveyance device in a state in which the double-sided documents D1 and D2 are placed and in a feeding preparation state. In the figure, a first original D1 in the upper layer
Of the stack document 110 and the movable pressing plate with the first surface of the
The automatic document feeder 10 is activated by being placed on the document feeder 112, and is set to the ADF mode. Further, the duplex document mode setting button on the control panel of the copying machine main body 1 is operated to set and input the duplex copy mode.

(B) Next, when the copy button on the control panel is turned on, the pressing motor M1 is activated, the movable pressing plate 112 is raised, and the original bundles D1, D2
Is pressed against the feed belt 123, the drive motor (main motor) M2 is turned on almost simultaneously, the clutch CL1 is also turned on at the same time, and document feeding is started. That is, the upper layer document D is sent out by the feed belt 123 which has started to rotate by the driving force of the drive motor M2, and further, the uppermost document D1 of the plurality of documents D sent out by the reverse roller 124 Only feeds are separated.

One original D separated and fed as described above
When the skew correction sensor PS10 detects the leading edge of the document, the timer T1 starts counting, and when the timer T1 counts up, the drive motor M2 is turned off.
At this time, the value of the timer T1 is set to
The leading end of the document abuts on the first intermediate conveyance roller 130 stopped by the FF, and the document is set so as to be stopped and straightened. If the feeding speed up to this point is set to a low conveying speed (for example, about 速度 of the speed at the time of document exchange), the skew correction operation becomes more stable.

When the timer T2, which has started counting upon detecting the leading edge of the original document by the skew correction sensor PS10, counts up, the drive motor M2, the clutches CL1, CL2, and CL5.
Is turned on to convey the document again. In accordance with this, the transport speed is switched to high-speed transport. When the leading edge of the document crosses the document passage detection sensor PS5, the clutch CL1 that has driven the driving roller 121 is turned off, and the feed belt
Reference numeral 123 rotates following rotation until the rear end of the document D1 passes through the sensor PS3, and then stops.

When the document passage detection sensor PS5 is turned on, the pressing motor M1 is switched to the reverse rotation, and the driving plate 118 and the movable pressing plate 112 are lowered to release the pressing. When the drive plate 118 returns to the initial position,
When the home position detection sensor PS4 detects, the pressing motor M1 is stopped. Alternatively, when continuously sending a plurality of documents, the driving plate 118 and the movable pressing plate
The lowering of the driving plate 118 and the movable pressing plate 112 is stopped intermediately based on the detection signal of the pressing detection sensor PS3 or the driving start signal of the driving unit in the separating direction without returning the 112 to the home position position.

When the trailing edge of the first document D1 passes and the document passage detection sensor PS5 is turned off, the pressing of the driving means is started based on this detection signal, and the driving plate 118 and the movable pressing plate 112 are moved. Then, the pressing of the subsequent original (the next original D2) is started. The first document D1 sent out by the paper feeding means and conveyed by the first intermediate conveyance roller pair 130 is detected by the notification detection sensor PS5 when the document passes through the leading edge of the document, and passes through the space between the guide plates 131. The sheet is fed by the second intermediate conveying roller pair 132 on the downstream side, and is further fed between the guide plates 133 on the downstream side.

When the leading edge of the document passes through a registration sensor (document passing synchronization sensor) PS6 disposed in a part of the feeding path, the registration sensor PS6 issues a detection signal to control the document conveyance. That is, the registration sensor PS6 controls the operation of the drive motor M2, the paper feed clutch CL2, and the like by a clock timer or the count of an encoder directly connected to the transport belt shaft.

Next, the document D1 is clamped between the rotating conveyor belt 151 and the platen glass 21 (reading section) by the conveying means 15, and is conveyed while being pressed against the platen glass 21. Then, the original is stopped by the clock timer or the count of an encoder directly connected to the transport belt shaft. In the present embodiment, an encoder sensor for detecting the output of an encoder (not shown) directly connected to the conveyance belt is provided, and when the registration sensor PS6 detects the leading edge of the document, the encoder sensor starts counting, and is driven when a predetermined count (N1) is reached. The motor M2 is turned off.

The transport belt and the second intermediate transport roller rotate while being decelerated by the inertial force and the load. At this time, the count of the encoder count is further continued and a predetermined count (N
3) When the clutch CL2 is turned off, the brake BRK is turned on and the brake BRK is turned on to forcibly stop the clutch CL2. Of course,
The document may be stopped by mechanical means such as a document stopper.

The first surface of the document D1 is exposed at a stop position on the platen glass 21 by an exposure lamp of the scanning exposure optical system 2, and a two-dimensional document image is formed on the photosensitive drum 31 via a lens, a mirror, and the like. It is formed. The same exposure is repeated for the set number of copies, and the original D
A series of copying processes are performed on the first side.

During the exposure operation of the first side of the original D1, the next original D2 is sent out by the paper feeding means, and when the leading edge of the original is detected by the skew correction sensor PS10, the timer T1 starts counting, and the timer T1 starts counting. When T1 counts up, the drive motor M2 is turned off. At this time, the timer T
The value of 1 is set so that the leading end of the document abuts on the first intermediate conveyance roller stopped by the OFF of the conveyance clutch CL5 and stops to correct the bending. The feeding speed up to this point is the low transport speed (for example, about の of the speed at the time of document replacement)
Is set, the bending correction operation is stabilized.

When the count of the timer T2, which has started counting when the leading edge of the original is detected by the skew correction sensor PS10, is counted up, the drive motor M2, the clutches CL1, CL2, CL are started.
5 is turned on, and the document is conveyed again. In accordance with this, the transport speed is switched to high-speed transport. When the leading edge of the document crosses the document passage detection sensor PS5, the timer T4 starts counting. Then, when T4 counts up, the drive motor M2 is turned off. The next original D2 is sent out so as to reach the first standby position at the end of the exposure of the preceding original D1.

Then, the sheet is nipped by the first intermediate conveyance roller and is located between the paper feeding means 12 and the reversing means 14 outside the conveyance path of the original of the reversing means 14 (the first conveying means is common with other conveying means). T4 is set so as to stop at the first standby position where the reversal of the preceding document D1 is not hindered in the unconveyed path portion. At this first standby position, the reading of the first side of the preceding document is completed, and it is waited that the preceding document is reversed.

(C) When the copying of the first side of the original D1 is completed, the drive motor M2 is switched to the reverse rotation drive, the transport belt 151 is rotated in the reverse direction, and the platen glass 21 is rotated.
The upper document D1 is nipped by a pair of reverse conveying rollers 141 rotating in the forward direction, makes a U-turn through a guide plate 142, and is clamped by the pair of second intermediate conveying rollers 132 rotating in the forward direction. Enter 133.

(D) When the leading edge of the document D1 is detected by the PS 6, the drive motor M1 is switched to forward rotation by this detection signal, and the drive roller 152 rotates forward to rotate the transport belt 151 in the forward direction. The document D1 is turned on the platen glass 21 to the left in the drawing. Here, when the trailing edge of the document D1 is detected by the PS7, the timer T8 starts, and after the timer counts up,
The drive motor M2 is turned on, and the conveyance of the next document D2 that has been waiting at the first standby position is started.

(E) While the second surface of the preceding document D1 is being conveyed to the exposure position (reading position), the next document D2 is held between the rotating conveyance belt 151 and the platen glass 21, The preceding document D1 and the next document D2 are simultaneously conveyed by the conveying belt 151 back and forth in the conveying direction. At the same time when the preceding document D1 stops at the exposure position (reading position), the next document D2 is located at an upstream position at a predetermined interval on the transport belt 151, and at least the leading end of the next document in the transport direction is the transport belt 151. It stops and waits at the second standby position, which is on the way.

At this time, when the leading edge of the preceding original D1 in the middle of reversing crosses the registration sensor PS6, the encoder count is started, but the leading end of the next original D2 also immediately crosses the registration sensor. Then, the counting operation is performed independently, and when the count of the inverted original D1 is counted up, the stop operation is started, and the count of the next original D2 is held.

(F) When the exposure of the first document D1 is completed, the switching pawl 161 is switched downward to switch the path upward,
The transport belt 151 rotates in the forward direction, and sends out the document D1 to the paper discharge reversing unit 16. That is, the rotation of the discharge motor M3, which is driven at the same time, causes the document D1 to move to the discharge roller 160 and the switching claw.
161 and a U-turn upward through the conveying roller 162, the guide plate 167, the conveying roller 164, the guide plate 166, the conveying roller
Reaches 163.

At the same time, the next original D2 is slid and conveyed on the platen glass 21 from the second standby position sandwiched between the conveying belt 151 and the second intermediate conveying roller pair 132, and the held count is restarted. When a predetermined count (N1) is reached, the drive motor is turned off. Conveyor belt 151 or second
The intermediate conveying roller pair 132 rotates while being decelerated by the inertial force and the load. At this time, counting of the encoder count is further continued.
At the same time when L2 is turned off, the brake BRK is turned on to forcibly stop and is positioned at the reading position.

(G) Even during the scanning exposure of the first surface of the original D2 stopped at the exposure position (reading position) on the platen glass 21 by the exposure lamp 23, the preceding original D1 It is being transported in the transport path. (H) During the scanning exposure of the document D2, the preceding document D1 is conveyed through the paper discharge reversing section 16 (paper discharge means) and is detected by the reverse paper discharge sensor PS9 for a predetermined time. Thereafter, the discharge motor M3 is rotated in the reverse direction, and the switching claw 161 is switched upward, so that the sheet is discharged to the discharge tray 168 (discharge stack unit) with the first surface facing downward.

Here, a new document is not fed into the paper discharge reversing section 16 until reading of the first and second surfaces of the document D2 is completed.
In this case, the sheet reversal can be performed by fully using the time until the reading operation of the second surface is completed. Therefore, the paper discharge reversal unit
In step S16, the document is conveyed at a speed lower than the document exchange speed and is discharged onto the paper discharge tray 168 when the paper discharge motor M3 is rotated reversely after a predetermined time after the rear end of the document is detected by the reverse discharge sensor PS9. It is.

This makes it possible to discharge at a low speed during the discharge and conveyance, thereby reducing the protrusion at the time of discharge onto the discharge tray 168 and improving the alignment of the originals, and smoothly performing the reverse conveyance operation. be able to. (I) The document D2 having been subjected to the exposure processing on the first surface is reversely fed on the platen glass 21 by the reverse rotation of the transport belt 151, and the reverse transport roller pair 141 of the reversing means 14 and the second
The sheet is nipped and conveyed by the intermediate conveying roller pair 132.

(J) The document D2 that has passed through the transport path in the reversing means 14 is again sent to the right end in the drawing on the platen glass 21 in a state where it is turned upside down, and is nipped and transported by the transport belt 151 to be transported. Gliding on 21 and braking again after counting. Document D in this stopped state
2 is subjected to the same scanning exposure as described above.

(K) Document D2 after double-sided exposure processing
Is transported by the transport belt 151 and sent to the paper discharge reversing unit 16, where the document D2 is transported upside down. (L) Document D transported through the paper discharge reversing unit 16 and turned upside down
2 is discharged onto a discharge tray 168 (discharge stack unit) outside the apparatus, and is mounted on the preceding document D1. In the one-sided original copy mode, the original is fed from the second intermediate transport roller pair 132 of the intermediate transport unit 13 to the platen glass 21.
160, a paper discharge tray 168 outside the machine through the lower surface of the switching claw 161.
The sheet is stored in the (discharge stack unit) with the first surface facing down (with the front and back states of the reading unit unchanged).

In the present embodiment, the conveying belt is exemplified as the conveying means, but it may be constituted by a plurality of rollers. As described above, when the double-sided document copy mode is selected, the automatic document feeder according to the present embodiment feeds out one double-sided document on the document mounting table (stack tray) 110, and outputs the document to the reading unit of the scanning exposure optical system. Before the reading operation of the first side of the original D1 is completed, the next original is separated from the original placing table and the first original is separated.
Feed it to the standby position. When the reading operation of the first surface of the document D1 is completed and the reversing unit 14 reverses the document surface and transports the second surface of the document D1 to the reading position, the transporting unit 15 causes the preceding document D1 to be read. Then, the next document D2 that has been waiting at the first standby position is moved back and forth in the transport direction and is simultaneously transported.

Thus, at the same time that the second surface of the preceding document D1 reaches the reading position, the next document D2 is transported from the first waiting position to the second waiting position upstream of the preceding document D1 by a predetermined interval. After the reading of the preceding document on the second side is completed, the discharge of the preceding document D1 and the conveyance of the next document D2, which has been waiting at the second standby position, to the reading position of the first side are simultaneously performed. It repeats until there is no more.

According to this transport process, when the second surface of the preceding document D1 is read, the next document D2 can also be made to stand by at a position near the upstream that is also nipped by the transport belt 155. After the two-sided reading is completed, the first side of the next original D2 can be transported to the reading position in a short time, thereby shortening the original transporting time and remarkably improving copy productivity.

That is, since the reversed original and the next original are simultaneously transported, the next original D2 can be made to stand by together with the preceding original D1 within the transport range of the transport belt 151, and the transport distance of the transport belt 151 is restricted. Thus, the next document D2 can be made to approach the preceding document D1 as much as possible, and can be put on standby. Before the simultaneous transport of the reversed preceding document and the next document is performed, the next document D2 is separated from the document placing table in advance and waits at the first standby position. There is enough time for the operation, separation operation at low speed and original posture correction operation can be performed, and the separation performance is lower than when separating from the document table and transporting to the second standby position continuously. In addition, the document interval can be stabilized, and a reliable document exchange operation can be performed.

In this embodiment, the configuration in which the original placing table and the discharge stack unit are separately provided has been described. However, the present invention employs a circulating image transport apparatus for circulating the read original document again to the original placing table. There may be. Further, the automatic document feeder as described in the above embodiment is disclosed in Japanese Patent Application No. 2-196654 or Japanese Patent Application No.
In combination with an automatic double-sided apparatus that speeds up the main body double-sided copy processing as proposed in JP-A-205964, the copy productivity can be greatly improved even when a double-sided copy is automatically obtained from a double-sided original.

[0066]

As described above, according to the automatic document feeder and method of the present invention, the next document is brought close enough to the preceding document to stand by without being restricted by the transport distance of the transport means. Therefore, the document transport time can be further reduced, and when applied to a copying machine, the copy productivity is significantly improved.

Further, the next original is separated from the original mounting table in advance and waits at the first standby position, and when the inverted preceding original is conveyed to the reading position, the next original is simultaneously moved from the first standby position to the second standby position. Since the document is conveyed to the standby position, the document exchange operation can be performed in a short time while reliably separating the document from the document table. Further, since the transport speed in the paper discharging process can be made slower than the transport speed at the time of document replacement, there is an effect that the paper transport operation can be performed smoothly and the documents to be discharged can be aligned well.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an image recording apparatus equipped with an automatic document feeder according to the present invention.

FIG. 2 is a sectional view of the automatic document feeder according to the present invention.

FIG. 3 is a drive system (power transmission system) of the automatic document feeder.
FIG.

FIG. 4 is a schematic diagram illustrating an operation process of feeding, transporting, and discharging a plurality of double-sided originals.

FIG. 5 is a schematic diagram of the document conveying operation process.

FIG. 6 is a schematic diagram of the document conveying operation process.

FIG. 7 is a time chart of a process of feeding and feeding a double-sided document.

FIG. 8 is a time chart of a process of feeding and feeding a two-sided original.

FIG. 9 is a block diagram illustrating a control circuit unit according to the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Copier main body 2 Scanning exposure optical system 21 Platen glass 3 Image forming means 10 Automatic document feeder 11 Document placement part 110 Stack tray (document placement table) 112 Movable press plate 12 Paper supply part (paper supply means) 121 Drive roller 123 feed belt 124 reverse roller 13 intermediate transport section 130 first intermediate transport roller pair 132 second intermediate transport roller pair 14 reversing means 141 reverse transport roller pair 142 guide plate 15 transport means 151 transport belt 152 drive roller 16 paper discharge reversing section ( Paper discharging means) 160 Paper discharging roller 161 Switching claw 162, 163, 164 Conveying roller 168 Paper discharging tray (paper discharging stack) D, D1, D2 Double-sided document (sheet), Document bundle M1 Pressing motor M2 Drive motor (Main Motor) M3 Discharge motor CL1, CL2, CL5 Clutch CL3, CL4 One-way clutch PS1 Document set detection sensor PS2 Document size sensor PS3 Pressing detection sensor PS4 Home position detection sensor PS5 Document passage detection sensor PS6 Registration sensor (document passage synchronization sensor) PS7 Inversion detection sensor PS8 Ejection detection sensor PS9 Inversion ejection sensor PS10 Bending correction sensor

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 15/00 107 G03G 21/00 370-500 G03G 21/14 G03B 27/58-27/64 B65H 83 / 00-85/00

Claims (7)

(57) [Claims] A first conveying unit that separates originals one by one from a bundle of originals stacked on an original placing table and conveys the originals to an image reading unit that reads an original image; and a reversing unit that reverses the originals. A second transport unit that transports the document from the image reading unit to the reversing unit, a third transport unit that transports the document to the image reading unit from the reversing unit, and the document from the image reading unit And a discharge means for transporting the next document to the first stack before the reading of the first surface of the preceding document is completed.
After the reading of the first surface of the preceding document is completed, the next document is started to be transported from the first waiting position, and the preceding document is read on the second surface. When the next original is conveyed to the second standby position at the same time as being conveyed to the image reading section, and the preceding original is discharged from the image reading section to the discharge stack section, the next original is transferred to the discharge stack section. An automatic document feeder for feeding a document from the second standby position to the image reading unit in parallel with a document. 2. The transfer path of the first, second, and third transfer means has a common portion, and the first standby position is a position other than the common portion of the transfer path of the first transfer means. 2. The automatic document feeder according to claim 1, wherein: 3. The automatic document feeder according to claim 1, wherein the posture of the document is corrected by an operation of making the document stand by at the first standby position. 4. The image forming apparatus according to claim 1, wherein the second conveying means is an endless belt stretched around two axes, and the second standby position is a position where a leading end of the next document in the conveying direction comes into contact with the endless belt. 2. The automatic document feeder according to claim 1, wherein: 5. The discharge operation of a preceding document conveyed to said discharge means after the completion of reading is completed from the first surface reading of the next document to the second surface reading operation of the next document in the image reading section. 2. The automatic document feeder according to claim 1, wherein: 6. The paper discharge stack section is a document mounting table,
2. The automatic document feeder according to claim 1, wherein the document discharged by the paper discharging means is circulated to a document table. 7. A method for separating originals one by one from a bundle of originals stacked on an original placing table and transporting the originals to an image reading unit for reading an original image. At the same time as reading the first side of the preceding original, the next original is transported to the first standby position, and the preceding original is turned over to read the second side of the preceding original. Simultaneously transporting the next document to a second standby position, reading the second side of the preceding document, and discharging the preceding document from the image reading unit to a discharge stack unit. At the same time, the next original document is transported from the second standby position to the image reading section in parallel with the preceding original document.