JPH0683140A - Automatic document feeder and automatic document feeding method - Google Patents

Abstract

PURPOSE:To improve productivity in copying and to secure the separation stability of a document by shortening the exchanging time of the document whose both sides are read. CONSTITUTION:Before finishing the read of the 1st side of a preceding document D1, the next document D2 is separated from a document platen, carried to a 1st standby position where it does not become an obstacle when the document D1 is reversed by a reversing means and allowed to stand by. Next, the document D1 reversed after finishing the read of the 1st side and the document D2 allowed to stand by at the 1st standby position are carried in a carrying direction nearly at the same time. As soon as the document D1 is stopped at a read position, the document D2 is stopped at a 2nd standby position being at a specified distance on the upstream side of the document D1. Then, the document D2 is carried to the read position simultaneously with the ejection of the document D1.

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 Generally, an automatic document feeder is used by mounting it on a platen glass (original table glass) of an image exposure section of a copying machine or the like. In an optical system movable copying machine equipped with this automatic document feeder, sheets are fed one by one from an original placing table (stack section) on which sheet-like originals (hereinafter simply referred to as originals) are placed. The document is fed onto the platen glass by the conveyor belt, exposed here by the exposure unit lamp in the main body of the copying machine, and then carried out onto the document discharge table.

[0003]

In the document replacement operation on the platen glass by such an automatic document feeder, conventionally, after the discharge sensor detects that the document on the platen glass has been discharged, The next original was sent out from the stack section, conveyed onto the platen glass, and stopped at a predetermined position. For this reason, it takes a long time to replace the original, and thus a long copy processing time, resulting in low copy productivity.

During the document replacement operation of automatically feeding and discharging the document on the platen glass using the automatic document feeder,
If the originals are replaced within the return time of the scanning optical system, the copy productivity will be 100% and no time will be required. To this end, it is necessary to increase the speed of document transportation from the document double feed prevention position in the stack portion to the document stop position on the platen glass surface.

However, if the document feeding speed is increased, various problems occur such as an increase in size of the motor, an increase in power consumption, noise generation, abrasion of the feeding belt, an increase in the degree of document damage, and a reduction in the document separating performance. . When copying a double-sided original, the double-sided original is conveyed onto the platen glass, the first surface of the original is exposed, and then the original is reversed by the reverse conveying means.
The original is exposed again on the second side of the original by being conveyed onto the platen glass, and then the original is reversed by the paper ejection reversing means again and ejected outside the apparatus in a page-aligned state. In such a double-sided automatic document feeder, the distance between the trailing edge of the first original and the leading edge of the second original is large, and the next original travel distance is increased during original replacement and reverse conveyance. There is a drawback that the required time increases.

As a technique capable of solving such a problem, the present applicant first separated and fed the next original from the original placing table during the reading operation of the second surface of the preceding original (conveying belt stopped). When the preceding original is ejected, the next original is read when the second original of the preceding original is read and the preceding original is ejected. An automatic document feeder configured to convey the document 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).
However, since the distance between the leading edge of the next original and the trailing edge of the preceding original is regulated, there is a problem in that the interval between the leading original and the next original cannot be shortened to further reduce the original replacement time. there were.

The present invention has been made in view of the above problems, and makes the next document stand by at a position as close as possible when reading the second surface of the preceding document without being restricted by the conveyance distance of the conveyance belt. By so doing, 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 table while realizing the reduction of the original exchange time.

[0009]

Therefore, in the automatic document feeder according to the present invention, the document is separated one by one from the document stack loaded on the document table and is conveyed to the image reading unit for reading the document image. Transporting means, inverting means for inverting the front and back of the document, second transporting means for transporting the document to the inverting means from the image reading section, and transporting the document to the image reading section from the inverting means. And a sheet discharging unit that conveys the original document from the image reading unit to the sheet discharge stack unit. The first original document is transferred to the first original document before the first surface of the preceding original document is read. Is transported to the first standby position by the transporting means, and after the first surface of the preceding document is read, the next document is transported from the first standby position.
The preceding document is conveyed to the image reading unit for reading the second side, and at the same time, the next document is conveyed to the second standby position, and the preceding document is discharged from the image reading unit to the discharge stack unit. At this time, the next original is conveyed in parallel with the preceding original from the second standby position to the image reading unit.

Here, when the transport paths in the first, second and third transport means have a common portion, the first transport
The standby position may be set to a position other than the common portion of the transport path in the first transport means. Further, it is preferable to correct the posture of the document by the operation of waiting at the first waiting position.

Further, when the second conveying means is composed of an endless belt which is stretched around two axes, the second standby position is such that the leading end of the next original in the conveying direction is the endless belt. It is preferable to set it at a position in contact with. Further, it is preferable that the paper discharge operation of the preceding original document conveyed to the paper discharge means after the completion of reading is completed from the first surface reading to the second surface reading operation of the next original document in the image reading section.

It is also possible to use the original stacking unit as the paper discharge stack section and circulate the originals discharged by the paper discharge means to the original document mount. 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 stack placed on a document table and transporting them to an image reading unit for reading a document image. The separated original is conveyed to the image reading unit, and the first original of the preceding original is read, and at the same time, the next original is conveyed to the first standby position.
In order to read the second side of the preceding document, the preceding document is turned upside down and conveyed to the image reading unit, and at the same time, the next document is conveyed to the second standby position, and the second side of the preceding document is conveyed. At the time of reading, the preceding document is discharged from the image reading unit to the discharge stack unit, and at the same time, the next document is conveyed in parallel with the preceding document from the second standby position to the image reading unit.

[0013]

According to the automatic document feeder and method having such a configuration, the next document is transported to the first and second standby positions concurrently with the transport of the preceding document, and the document replacement time can be shortened. Further, since the next original is separated and fed from the original placing table in advance and stands by at the first standby position, separation of the next original from the original placing table and conveyance to the second standby position are continuous. Therefore, it is possible to carry the sheet to the second standby position from the state where the separation of the next original from the original placing table is surely completed.

Further, by setting the first standby position at a position where it 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 stable,
Therefore, the conveyance to the second standby position can be smoothly performed. Further, since there is a sufficient time margin when waiting at the first waiting position, if the posture of the original is corrected here,
Good posture correction.

Further, in the second conveying means constituted by the endless belt which is stretched around the two axes, the second standby position of the next original is located at the position where the leading end of the next original in the conveying direction comes into contact with the endless belt. In this case, the next original can be brought close to the preceding original as much as possible without being restricted by the conveyance distance of the endless belt. It becomes easy to convey the next original document to the image reading unit.

Further, after the completion of reading, the discharging operation of the preceding original document conveyed to the discharging means is completed from the first surface reading to the second surface reading operation of the next original in the image reading section. For example, by utilizing the reading time and reversing time of the next original, the time required for discharging the paper can be increased, and the conveying speed of the paper discharging means can be made slower than the speed at which the original is replaced, and the discharged originals can be aligned well. .

If the read original is discharged to the original placing table instead of separately providing the sheet discharging stack section and the original placing table, the original can be circulated.

[0018]

Embodiments of the present invention will now be described 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 image forming means around the photosensitive drum 31, 4 is copy paper supplying means, 5 is copy paper conveying means, 6 is a fixing device, and 7 is a fixing device. Is a reverse discharge switching unit, 8 is a reverse transport unit, 9 is a double-sided recording sheet transport unit (ADU), and 10 is an automatic document feeder (RADF) with a double-sided document automatic reversing function.

FIG. 2 shows the automatic document feeder according to the present invention.
10 is a sectional view, and FIG. 3 is a configuration diagram showing a drive system (power transmission system) of the automatic document feeder 10. The above automatic document feeder
As shown in FIG. 1, 10 is installed on the main body 1 of the copying machine.
Paper feed unit 12 (paper feed means) that separates and feeds a single document D
An intermediate conveyance unit 13 that conveys the document D fed from the paper feed unit 12, and a conveyance unit 15 that conveys the document conveyed by the intermediate conveyance unit 13 to a predetermined reading position on the platen glass 21. The reversing means 14 for reversing the original conveyed by the conveying means 15 in the opposite direction and feeding it again to the conveying means 15, and the reversing means 14 for reversing the original D after reading or the front and back of the original D as it is. It is composed of a paper discharge reversing unit 16 (paper discharge means) that discharges the paper to a paper stack portion) or returns it to the document placing table.

Here, the paper feeding section 12, the intermediate conveying section 13, and the conveying means 15 constitute a first conveying means, and the conveying means 15 constitutes a second conveying means. Further, the intermediate carrying section 13 and the carrying means 15 constitute a third carrying means. Therefore, in the present embodiment, the first, second, third
The transport means of has a common part in its transport path. A stack tray (document placing table) 110 for stacking a bundle of documents is fixedly provided on the document placing section 11, and on the stack tray 110,
A lateral width regulating plate 111 for regulating the lateral width of the document is movably provided.

When the stack of originals is placed on the stack tray 110, the presence or absence of originals on the stack tray 110 is detected by the original set detection sensor (zero original detection sensor) PS1 and the ADF is displayed on the control panel of the copying machine main body 1. The mode is displayed. Further, when the document stack is placed at a predetermined position, the document size (B5 to A3) is determined by the document size sensor P.
It is detected by S2 and input to the control unit of the copying machine main body 1.

A movable pressing plate 112 is supported on the tip end side of the stack tray 110 on the downstream side of document feeding so as to be vertically swingable with respect to a swing shaft 114 about the swing shaft 114.
A drive plate 118 is screwed to the swing shaft 114, and the swing shaft 114 and the drive plate 118 swing together. Further, an elastically deformable member (for example, a torsion spring) 119 is wound around the swing shaft 114, and both ends of the elastic deformable member 119 are connected to the drive plate.
118 can be pressed downward, and the central portion can press the movable pressing plate 112 upward.

The drive plate 118 is provided with two actuator parts, and one actuator part turns on / off the optical path of a pressing plate detection sensor (for example, a photo interrupter) PS3 fixedly mounted on the movable pressing plate 112. . The other actuator section turns on / off the optical path of a sensor (for example, a photo interrupter) PS4 fixedly mounted on the fixed bottom plate 116 to detect the home position of the drive plate 118.

A feeding section 12 is provided downstream of the movable pressing plate 112 for feeding the original. The feeding unit 12 is composed of a document leading edge stopper 120, a driving roller 121, a driven roller 122, a feed belt 123 that winds and rotates both rollers, and a double feed preventing reverse roller 124 located below the feed belt 123. There is. The drive roller 121 includes a drive motor M2.
Is transmitted via the electromagnetic clutch CL1.

An intermediate conveying section 13 which rotates in the forward direction is provided at the downstream side of the document conveying section of the sheet feeding section 12. The intermediate transfer unit 13
The first intermediate conveyance roller pair 130 driven by the drive motor M2 via the conveyance clutch CL5, the document passage detection sensor PS
5, a curved guide plate 131, and a second intermediate conveying roller pair 132 which is always positively driven by a one-way clutch CL3. The original D sent from the paper feeding unit 12 is fed to a platen glass.
A transport path for transporting is formed at one end of 21.

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 conveying roller 141 is a one-way clutch C.
It has L3 built-in and is always driven in forward rotation. Reference numeral 142 is a curved guide plate that connects the nip positions of the second intermediate conveyance roller pair 132 and the reversal conveyance roller pair 141, and forms a document reversal feed path. A reversal detection sensor PS7 is provided in a part of the reversal feeding path, and detects passage of a reversal fed document.

On the surface of the platen glass 21, a conveyor belt 151 (endless belt) is provided with a driving roller 152 and a driven roller.
153 (biaxial), 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 driving roller 152 is operated by the driving force of the driving motor M2.

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

FIG. 9 is a block diagram showing the electrical construction of the automatic document feeder 10. In FIG. 9, motors M1, M2, M3 for driving the rollers for document transportation, clutches CL1-CL5, brake BRK, and solenoid SOL for driving the switching pawl 161 are connected to a control unit (CPU) through an interface circuit. To be done. The interface circuit further includes sensors PS1 to PS1 for detecting the conveyance of the document.
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 drive of each motor, clutch, and solenoid. The control unit performs control operation based on the control program stored in the ROM. When operations such as copying start, document reading mode switching, and paper discharge mode selection are performed on the operation unit, signals corresponding to the respective operations are given to the control unit (CPU).

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

(1) In the state shown in FIG. 3, when the main switch of the copying machine 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. The pressing motor M1 is stopped. That is, the home position detection sensor PS4 is turned on at the home position.

When the main switch is on and the home position detecting sensor PS4 is off, the pressing motor M
1 is rotated in the reverse direction to lower the movable pressing plate 112, the home position detection sensor PS4 is detected to be turned on, the pressing motor M1 is stopped, and the drive plate 118 and the movable pressing plate 112 are set to the lowest initial positions. To stop. If the home position detection sensor PS4 is on, the pressing motor M1 is once rotated in the normal direction, the home position detection sensor PS4 is turned off to raise the movable pressing plate 112, and then the motor M1 is reversely rotated. Then, the movable pressing plate 112 is lowered, and when the sensor PS4 is turned on, the motor M1
To the home position. This is effective in absorbing the time lag of the drive gear and the sensor on. At the home position stop position, a clearance capable of accommodating a predetermined maximum amount of the document stack is maintained.

(2) Stack tray 110 and movable pressing plate
When the document stack D is placed on 112, the document set detection sensor PS1 is turned on, and the ADF mode (automatic document transport mode) is set. At the same time, the document size sensor PS2 is turned on and the document size is detected. (3) When the copy button is turned on, ADF and copy can be started, and the pressing motor (stepping motor)
The M1 starts driving rotation, and the movable pressing plate 112 is moved through the driving member 118 fixed to the swing shaft 114 and the elastic deformation member 119.
Oscillates and rotates, and its leading end rises to lift the stacked document stack D. During this ascending 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 document stack 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 document stack. The drive plate 118 is further driven and rotated to rotate the counterclockwise direction in the figure while compressing the elastically deformable member (torsion spring) 119, and the interval between the movable pressing plate 112 and the drive plate 118 is narrowed.

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

With the above operation, preparation for sending the manuscript is completed,
The document feeding continues. Next, the feeding operation of the double-sided original will be described. To simplify the description, a document stack composed of two double-sided documents D1 and D2 will be described below. (A) FIG. 4A is a schematic diagram showing a document feeding path of the automatic document feeding device in which the double-sided documents D1 and D2 are placed and in a feeding preparation state. In the figure, the upper first document D1
Both the first surface of the sheet and the first surface of the lower second original D2 are faced upward, and the stack tray 110 and the movable pressing plate.
When the automatic document feeder 10 is activated by being placed on the printer 112, the ADF mode is set, and the double-sided original designation button on the control panel of the copying machine body 1 is operated to set and input the double-sided copy mode.

(B) Next, by turning on the copy button on the control panel, the pressing motor M1 is activated, the movable pressing plate 112 is raised, and the document stacks D1 and D2 are moved.
The uppermost surface of the sheet is pressed against the feed belt 123, the drive motor (main motor) M2 is turned on almost at the same time, and the clutch CL1 is also turned on at the same time to start the document feeding. That is, the original D in the upper layer is sent out by the feed belt 123 which starts to rotate by the driving force of the drive motor M2, and further, the original D1 at the top of the plurality of originals D1 sent out by the reverse roller 124. Only separated and fed.

One sheet of the document D separated and fed as described above.
When the bending 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 0 for the transport clutch CL5.
It is set so that the leading edge of the original comes into contact with the first intermediate conveyance roller 130 stopped by the FF and stops, and the bending is corrected. If the feeding speed up to this point is set to a low-speed feeding speed (for example, about 1/2 of the speed at the time of document replacement), the bending correction operation becomes more stable.

When the timer T2, which started counting when the leading edge of the document is detected by the straightening sensor PS10, counts up, the drive motor M2, the clutches CL1, CL2 and CL5.
Is turned on and the document is conveyed again. In accordance with this, the transfer speed is switched to high speed transfer. When the leading edge of the document crosses the document passage detection sensor PS5, the clutch CL1 driving the drive roller 121 is turned off, and the feed belt is turned off.
123 is driven to rotate until the trailing edge 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 has returned to the initial position,
When the home position detection sensor PS4 detects it, the pressing motor M1 is stopped. Alternatively, the drive plate 118 and the movable pressure plate may be
Without returning 112 to the home position, the drive plate 118 and the movable pressing plate 112 are stopped in the middle based on a detection signal from the pressure detection sensor PS3 or a drive start signal in the separating direction of the drive means.

When the trailing edge of the first document D1 passes and the document passage detection sensor PS5 is turned off, the driving of the driving means is started based on this detection signal, and the driving plate 118 and the movable pressing plate 112 are driven. Then, it is raised and the pressing of the succeeding document (next document D2) is started. Regarding the first original D1 sent out by the paper feeding means and conveyed by the first intermediate conveying roller pair 130, passage of the front end of the original is detected by the notification detecting sensor PS5, and the first original D1 is passed between the guide plates 131. It is fed by the second pair of intermediate conveying rollers 132 on the downstream side, and further fed between the guide plates 133 on the downstream side.

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

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

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

The first surface of the original D1 is exposed by the exposure lamp of the scanning exposure optical system 2 at the stop position on the platen glass 21, and a two-dimensional original 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 copy processes for the first side of 1 is performed.

During the exposure operation of the first surface of the original document D1, the next original document D2 is sent out by the paper feeding means, and when the bending correction sensor PS10 detects the leading edge of the original document, the timer T1 starts counting and the timer is started. When T1 counts up, the drive motor M2 is turned off. At this time, timer T
The value of 1 is set so that the leading edge of the document abuts against the first intermediate conveyance roller that has stopped due to the OFF of the conveyance clutch CL5 and the curl is corrected. The paper feeding speed up to this point is a low-speed transportation speed (for example, about 1/2 of the speed at document replacement)
When set to, the straightening operation is stable.

When the timer T2, which started counting when the leading edge of the document is detected by the bending correction sensor PS10, counts up, the drive motor M2, the clutches CL1, CL2, CL.
5 is turned on and the document is conveyed again. In accordance with this, the transfer speed is switched to high speed transfer. 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 when the exposure of the preceding original D1 ends.

Then, between the paper feeding means 12 and the reversing means 14, being nipped by the first intermediate conveying roller, the document is not conveyed by the reversing means 14 (common to the other conveying means in the first conveying means). T4 is set so as to stop at the first standby position that does not hinder the reversal of the preceding document D1 in the non-conveyance path portion). At the first waiting position, the reading of the first side of the preceding document is completed and the waiting of the reverse of the preceding document is performed.

(C) When the copying of the first side of the document D1 is completed, the drive motor M2 is switched to the reverse rotation drive, the conveyor belt 151 is rotated in the reverse direction, and the platen glass 21 is rotated.
The upper original D1 is nipped by the pair of reverse conveying rollers 141 rotating in the forward direction, makes a U-turn through the guide plate 142, and is sandwiched 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 PS6, the drive signal M1 is switched to the normal rotation drive by this detection signal, the drive roller 152 rotates in the normal direction, and the conveyor belt 151 rotates in the forward direction. The original D1 whose front and back are reversed is slid to the left side in the drawing on the platen glass 21 by moving. Here, when the rear edge of the document D1 is detected by PS7, the timer T8 starts, and after the timer counts up,
The drive motor M2 is turned on, and the conveyance of the next original document D2 held in the first waiting 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 conveyor belt 151 and the platen glass 21. The preceding original document D1 and the next original document D2 are simultaneously conveyed by the conveyor belt 151 forward and backward in the conveying direction. Then, at the same time that the preceding document D1 stops at the exposure position (reading position), the next document D2 is at the upstream position on the conveyor belt 151 at a predetermined distance, and at least the leading end of the next document in the conveyance direction is located on the conveyor belt 151. It stops and waits at the second waiting position which is on the way.

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

(F) When the exposure of the first original D1 is completed, the switching claw 161 is switched downward and the path is switched upward.
The conveyance belt 151 rotates in the forward direction and sends the document D1 to the paper discharge reversing unit 16. That is, the original D1 is ejected by the ejection roller 160 and the switching claw by rotation of the ejection motor M3 which is driven simultaneously.
After making a U-turn upward through 161, the carrying roller 162, a guide plate 167, a carrying roller 164, a guide plate 166, a carrying roller
To 163.

At the same time, the next original document D2 is also slidably conveyed on the platen glass 21 from the second standby position held by the conveyor belt 151 and the second intermediate conveyor roller pair 132, and the held count is restarted. When the predetermined count (N1) is reached, the drive motor is turned off. Conveyor belt 151 and second
The intermediate conveyance roller pair 132 rotates while being decelerated by the inertial force and the load. At this time, the counting of the encoder count is further continued, and when the predetermined count (N3) is reached, the clutch C
At the same time when L2 is turned off, the brake BRK is turned on and forcibly stopped, and the position is set to the reading position.

(G) Even during the scanning exposure by the exposure lamp 23 on the first surface of the document D2 stopped at the exposure position (reading position) on the platen glass 21, the preceding document D1 is stored in the paper output reversing unit 16. It is being transported in the transport path. (H) During the scanning exposure of the document D2, the preceding document D1 is conveyed while passing through the paper discharge reversing unit 16 (paper discharge means), and when the document rear end is detected by the reverse paper discharge sensor PS9, a predetermined time is passed. After that, the paper discharge motor M3 is rotated in the reverse direction, and the switching claw 161 is switched to the upper side, and the paper is discharged to the paper discharge tray 168 (paper discharge stack portion) with the first surface facing downward.

Here, since a new document is not fed to the paper discharge reversing unit 16 until the reading of the first and second sides of the document D2 is completed, at least the next document D2 is sent.
It is possible to reverse the discharged sheet by fully using the time until the reading operation of the second surface is completed. Therefore, the paper output reversing unit
In 16, when the document is detected by the reverse sheet ejection sensor PS9 at the rear end and the sheet ejection motor M3 is rotated in the reverse direction after a predetermined time, the document is conveyed at a speed slower than the document replacement speed and ejected onto the sheet ejection tray 168. I am doing it.

As a result, it is possible to discharge the sheet at a low speed when the sheet is conveyed, and it is possible to reduce the protrusion of the sheet onto the sheet discharge tray 168 to improve the original alignment and to smoothly perform the reverse conveying operation. be able to. (I) The document D2 having undergone the exposure processing on the first surface is fed back on the platen glass 21 by the reverse rotation of the conveyance belt 151, and the reverse conveyance roller pair 141 of the reversing means 14 and the second side.
It is nipped and conveyed by a pair of intermediate conveyance rollers 132.

(J) The original D2 which has passed through the conveying path in the reversing means 14 is fed to the right end portion of the platen glass 21 in the figure in the state of being turned upside down, and is held and conveyed by the conveyor belt 151 to be conveyed to the platen glass. Glide over 21 and stop after the count. Document D in this stopped state
The same scanning exposure as described above is performed on the second surface of No. 2.

(K) Original D2 which has been subjected to double-sided exposure processing
Is conveyed by the conveyor belt 151 and sent to the paper discharge reversing unit 16, where the document D2 is conveyed with its front and back reversed. (L) Original D that has been conveyed through the paper output reversing unit 16 and has been turned upside down
The sheet 2 is discharged onto the sheet discharge tray 168 (sheet discharge stack section) outside the apparatus and is mounted on the preceding document D1. In the single-sided original copy mode, the original is sent from the second intermediate conveying roller pair 132 of the intermediate conveying unit 13 to the platen glass 21, and after reading, the sheet discharge rollers of the sheet discharge inverting unit 16 are read.
160, the output tray 168 outside the machine through the lower surface of the switching claw 161
The sheet is accommodated in the (sheet discharge stack section) with the first side facing down (the front and back sides of the reading section remain unchanged).

In this embodiment, the conveyor belt is illustrated as the conveyor means, but it may be composed of a plurality of rollers. As described above, when the double-sided document copy mode is selected, the automatic document feeder of the present embodiment feeds out one double-sided document on the document table (stack tray) 110, and causes the reading unit of the scanning exposure optical system to read it. Before the operation of reading the first side of the document D1 is completed, the next document is separated from the document table and the first document is separated.
Let it be fed to the standby position. When the reading operation of the first surface of the original document D1 is completed and the original surface is inverted by the reversing means 14 and the second surface of the original document D1 is conveyed to the reading position, the preceding original document D1 is conveyed by the conveying means 15. Then, the next original D2 held in the first waiting position is moved back and forth in the carrying direction to be carried at the same time.

As a result, the second surface of the preceding document D1 reaches the reading position, and at the same time, the next document D2 is conveyed from the first waiting position to the second waiting position upstream of the preceding document D1 by a predetermined distance. After the reading of the second side of the preceding document is completed, the discharging 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 performed at the same time. It is characterized by repeating until there is no.

According to this carrying 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 where it is also sandwiched by the carrying belt 155. After the two-sided reading is completed, the first side of the next original D2 can be conveyed to the reading position in a short time, whereby the original conveying time can be shortened and the copy productivity is remarkably improved.

That is, since the inverted original document and the next original document are conveyed at the same time, the next original document D2 together with the preceding original document D1 can be put on standby within the conveyance range of the conveyance belt 151, and the conveyance distance of the conveyance belt 151 is restricted. Then, the next original D2 can be brought close to the preceding original D1 as much as possible and can be put on standby. Further, before the simultaneous conveyance of the reversed original document and the next original document is performed, the next original document D2 is separated from the original document placing table and made to stand by at the first standby position in advance, so that the first standby position is waited. The operation has a sufficient time allowance, the low-speed separation operation and the document posture correction operation can be performed, and the separation performance is better than that in the case where the separation from the document placing table and the conveyance to the second standby position are continuously performed. Further, the document interval can be improved, and a reliable document replacement operation can be performed.

In the present embodiment, the document placing table and the sheet discharge stack section are separately provided, but it is possible to use a circulation type image conveying apparatus for circulating the read document again on the document placing table. It may be. In addition, an automatic document feeder as in the above-described embodiment is disclosed in Japanese Patent Application No. 2-196654 and Japanese Patent Application No. 3-163654.
By combining the main body double-sided copy processing as proposed in No. 205964 with an automatic double-sided device that speeds up, copy productivity can be significantly 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 made sufficiently close to the preceding document to stand by without being restricted by the transport distance of the transport means. As a result, the document transport time can be further shortened, and when it is applied to a copying machine, copy productivity is significantly improved.

Further, when the next original is separated from the original placing table in advance and made to stand by at the first standby position and the reversed preceding original is conveyed to the reading position, at the same time, the next original is moved from the first standby position to the second standby position. Since the document is conveyed to the standby position, it is possible to perform the document replacement operation in a short time while surely separating it from the document placing table. Further, since the transport speed in the paper discharge process can be made slower than the transport speed at the time of document replacement, there is an effect that the paper discharge transport operation can be performed smoothly and the discharged document originals can be aligned well.

[Brief description of 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 an 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, conveying, 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 view of the document conveying operation process.

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

FIG. 8 is a time chart of a double-sided document feeding / conveying process.

FIG. 9 is a block diagram showing a control circuit unit of the embodiment.

[Explanation of symbols]

 1 Copying Machine Main Body 2 Scanning Exposure Optical System 21 Platen Glass 3 Image Forming Means 10 Automatic Document Feeding Device 11 Document Loading Unit 110 Stack Tray (Document Loading Table) 112 Movable Pressing Plate 12 Feeding Unit (Feeding Unit) 121 Driving Roller 123 feed belt 124 reverse roller 13 intermediate conveying section 130 first intermediate conveying roller pair 132 second intermediate conveying roller pair 14 reversing means 141 reversing conveying roller pair 142 guide plate 15 conveying means 151 conveying belt 152 drive roller 16 paper ejection reversing section ( 160 Paper ejection roller 161 Switching claw 162, 163, 164 Conveying roller 168 Paper ejection tray (paper ejection stack) D, D1, D2 Double-sided original (sheet), original bundle M1 Pressing motor M2 Drive motor (main) Motor) M3 Paper discharge motor CL1, CL2, CL5 Clutch CL3, CL4 One-way clutch PS1 Original set detection sensor PS2 Original size sensor PS3 Press detection sensor PS4 Home position detection sensor PS5 Original passage detection sensor PS6 Registration sensor (Original passage synchronization sensor) PS7 Reverse detection sensor PS8 Paper ejection detection sensor PS9 Reverse paper ejection sensor PS10 Bending correction sensor

Claims (7)

[Claims] 1. A first conveying unit that separates documents one by one from a document stack loaded on a document table and conveys them to an image reading unit that reads a document image; and a reversing unit that reverses the front and back of the document. A second conveyance unit that conveys the document from the image reading unit to the reversing unit; a third conveyance unit that conveys the document from the reversing unit to the image reading unit; and a document conveyance unit from the image reading unit. And a sheet discharging unit that conveys the next document to the first stack before the reading of the first side of the preceding document is completed.
Is conveyed to the first standby position by the conveying means and after the reading of the first side of the preceding document is completed, the next document is started to be conveyed from the first standby position and the preceding document is read on the second side. For transporting the next original to the second standby position at the same time that the preceding original is discharged from the image reading section to the discharge stack section, An automatic document feeder which conveys a document in parallel with the document from the second standby position to the image reading unit. 2. The transport paths in the first, second and third transport means have a common portion, and the first standby position is other than the common portion of the transport paths in the first transport means. The automatic document feeder according to claim 1, wherein the automatic document feeder is provided. 3. The automatic document feeder according to claim 1, wherein the posture of the document is corrected by an operation of standing by at the first standby position. 4. The second conveying means is an endless belt stretched around two axes, and the second standby position is a position where the leading end of the next original in the conveying direction comes into contact with the endless belt. The automatic document feeder according to claim 1, wherein the automatic document feeder is provided. 5. The discharging operation of the preceding original document conveyed to the discharging means after the completion of reading is completed from the first side reading to the second side reading operation of the next original in the image reading section. The automatic document feeder according to claim 1. 6. The discharge stack unit is a document placing table,
2. The automatic document feeder according to claim 1, wherein the document discharged by the paper discharge means is circulated on the document table. 7. A method of separating originals one by one from a stack of originals placed on an original placing table and conveying the originals to an image reading unit for reading an original image, wherein the originals are separated one by one and the preceding originals are recorded. The preceding document is conveyed to the image reading unit, the first side of the preceding document is read, and at the same time, the next document is conveyed to the first standby position, and the preceding document is turned upside down to read the second side of the preceding document. When the next original is conveyed to the second standby position at the same time as being conveyed to the image reading section, the second side of the preceding original is read, and the preceding original is discharged from the image reading section to the discharge stack section. At the same time, the next original is conveyed in parallel with the preceding original and is conveyed from the second standby position to the image reading unit.