JP3259063B2 - Automatic document feeder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a recording apparatus such as an electrophotographic copying machine and an automatic document feeder attached to an image reading apparatus and the like. A feeding unit that feeds out the original by the feeding unit, separates and feeds the original by the separating unit, further arranges the posture of the original by a pair of registration rollers, waits for the original, and feeds the image to the image reading unit. It is about improvement.

[0002]

2. Description of the Related Art As a device capable of efficiently feeding an image-recorded document to a recording device such as an electrophotographic copying machine or a recorded image reading device even in an unmanned state, an automated document feeder ( (ADF) has already been provided.

Further, as a copying machine capable of copying each image of a document having a recording image on both sides (double-sided document) on one side or both sides of a recording body and an image reading apparatus capable of reading and recording the image, the ADF is provided with the front and back sides of the document. An automatic document feeder (R-ADF device) provided with a reversing function has been put to practical use.

As an example of the automatic document feeder, a document stacked on a document placing section is sent out by a sending means, one sheet is separated and fed by a separating means, and one sheet is fed by a pair of registration rollers. After the original is adjusted to a standby state, the feeding unit feeds the original to the image reading unit on the platen glass, and the original fed to the image reading unit is transported and stopped at a predetermined image reading position. image and conveying unit for unloading the document after reading, the paper discharge unit Toka et structure for discharging the document delivered from the transport unit located on the downstream side in the transport direction from the image reading unit to the discharge tray portion of the outside after the Some have been made.

(1) In a conventional document feeding section, a document is fed by a feed-out roller, and is fed while being separated by a double feed prevention roller (with a built-in torque limiter) of a separation section, so that a nip portion of a registration roller pair is provided. , And is conveyed to a document reading position thereafter. In this standby state, when the document is separated from the feed roller, there is a problem that the document is reversed by the charging force of the torque limiter of the double feed prevention roller of the separation unit, and the document is returned. For this reason, there is a problem that the document is not fed even when the registration roller pair rotates.

[0006]

[0007]

( 2 ) The conventional separating means has a problem that after the registration of the document, the judgment of the spring clutch torque limiter mounted on the double feed prevention roller is reversed and the document is returned (see (1) above). For this reason, an intermediate roller is provided between the conventional separation unit and the registration roller downstream in the feeding direction of the double feed prevention roller (retard roller), and the trailing edge of the document is subjected to the separating action at the nip position of the retard roller, After passing through the intermediate roller, it is brought into contact with the nip of the pair of registration rollers and stopped. For this reason, the paper feed path becomes long, and the structure is not complicated and compact.

Conversely, if the pair of registration rollers is nipped and stopped so as not to be returned without the intermediate roller, it becomes impossible to enter the passage sensor near the downstream side of the nip of the pair of registration rollers to measure the length of the paper. Further, if the passage sensor is further away from the nip position of the pair of registration rollers, the paper feed length becomes longer, and the size and size are not reduced as in the case where the intermediate roller is provided.

( 3 ) The conventional feeding means uses a generally rotatable feed belt, and presses against the uppermost layer of the stacked originals to feed the original to the separating means side.

However, if only the feed belt is used, the original pressing area is small, the load per unit area is large, and original contamination occurs.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has improved a feeding means, a separating means, a registration means, and the like constituting a feeding section of an automatic document feeder. An object of the present invention is to provide an automatic document feeder capable of reliably feeding a document and shortening a document replacement time.

[0013]

In order to achieve the above object, an automatic document feeder according to the present invention is arranged such that a document stacked on a document placing section is sent out by sending means, and a torque limiter is provided.
A single document is separated and fed by a separating means with a built-in printer, and the position of the single document is adjusted by a pair of registration rollers, and the document is made to stand by, and then fed to an image reading unit on a platen glass. parts and a transport unit which transports the document after the image reading after stopping to the fed original predetermined image is conveyed to the reading position in the image reading unit, the document delivered from the conveyance section outside of An automatic document feeder comprising: a paper discharge unit for discharging to a paper discharge tray unit; and a control unit for controlling a drive unit including at least a motor for driving the feed unit and the transport unit and calculating a length of the document. The automatic document feeder,
A pass sensor for detecting the passage of the leading and trailing edges of the document is provided near the downstream side in the document feeding direction from the nip position of the pair of registration rollers in the feeding unit , and the length of the document is detected in the control means by the detection signal of the pass sensor. A hardware counter for calculating the length of the original, and a standby stop position near the upstream of the image reading unit beyond the passage sensor by nipping the leading end of the original sent out by the separation unit to the registration roller pair. Until it stops at the standby stop position.
And re-feed the paper toward the image reading unit.
Te, the control means, wherein a required count m from the passage sensor passage of the document leading end when the preliminary feeding up to the standby stop position
A required total number n from the start refeed until the trailing edge of the document passes the passage sensor is measured, the document is paused
Counting between does not measure, the hard and the required count m and n
It is characterized in that what determines the document size by adding the de-ware counters.

[0014]

[0015]

The automatic document feeder according to the present invention further comprises an electromagnetic clutch provided at the end of the drive shaft of the registration roller pair of the feeding section, and a portion near the nip position of the registration roller pair on the upstream side in the document feeding direction. A photo sensor provided at a position between the registration roller pair and the nip of the registration roller pair in a stopped state after feeding the document for a predetermined time after the photo sensor detects the leading end of the document fed from the separating unit. The registration is performed, and thereafter, the electromagnetic clutch is turned on within a certain period of time, and the original is re-fed by the pair of registration rollers, and the leading end of the original is nipped into a standby position and temporarily stopped. is there.

Further, in the automatic document feeder of the present invention, the feed means of the feeding section includes a feed belt which presses the uppermost original surface of the originals wound around the driving roller and the driven roller. It is characterized by comprising a pair of feed rollers arranged on a drive shaft of the drive roller with the feed belt interposed therebetween, and feeding the original by the feed belt and the feed roller.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an automatic document feeder according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an overall configuration diagram of an automatic document feeder according to the present invention, and FIG. 2 is a sectional view of a feeding section of the automatic document feeder. The illustrated apparatus is an automatic document feeder (R-ADF) with an automatic document reversing function. The structure and operation of the automatic document feeder will be described with reference to these drawings.

The automatic document feeder (R-AD) of the present invention
F) is mounted on the copying machine main body 1 as shown in FIG. 1, and is placed on a document tray 10 for loading a plurality of documents and on a document tray 11 of the document tray 10. A feeding unit 20 for sending one document from a document bundle onto a platen glass (platen glass) 2 serving as an image reading unit, and a document fed from the feeding unit 20 to a platen glass 2 on the platen And a transport section 30 for transporting the original to a predetermined position (image exposure scanning position), and discharging the original sent from the transport section 30 after the end of the image exposure from the discharge port to the outside, or turning the original upside down and re-opening the original. It comprises a paper discharge reversing section 40 for returning the original document to the platen glass 2 again, and a paper discharge tray section 50.

A plurality of originals D are manually set on an original tray 11 which is provided so as to protrude to the side of the copying machine body 1, and is positioned in the width direction by an original width regulating member 12. The leading end of the document D passes above the movable guide plate 21 near the entrance of the feeding unit 20 in the automatic document feeder main body 100, contacts the stopper member 22, and stops. In this document stop state, the leading edge of the document is flipped up to allow the actuator 27 to swing, and an ON signal is transmitted from the document set detection sensor S1 to set the ADF mode.

When the copy button on the copying machine body is pressed, the paper feeding solenoid SD1 is operated, and the movable guide plate 21 is moved.
The document D is pressed against the separation belt 23 and the feed roller 24. Next, when the motor M is driven, the separation belt 23 starts rotating by the feed roller 24 connected to the drive source, and only the uppermost original D is fed in cooperation with the retard roller 25. The leading edge of the document D, which is separated and fed, abuts against the peripheral surface of the roller near the nip position of the pair of registration rollers (the pair of intermediate transport rollers) 26, the posture of the document is adjusted, and only the leading edge of the document temporarily stops.

On the other hand, the registration sensor S2 provided on the upstream side of the registration roller pair 26 detects the passage of the leading edge of the document, and after a predetermined count by the encoder count, the registration clutch is turned on, and the registration roller pair 26 starts rotating and the document is rotated. Re-feed. When the leading edge of the document reaches the exit of the nip position of the pair of registration rollers 26, the sheet feeding clutch is turned off by a detection signal of the passage sensor (document size detection sensor) S3, and free rotation is performed after the driving force transmission of the separation belt 23 is stopped. And only the preceding original D is paired with the registration rollers.
Conveyed by 26.

The original D conveyed by the pair of registration rollers 26 passes above a stopper plate 4 for positioning the original when the automatic original feeder is not used, and is placed on an upper surface of the main body 1 of the copying apparatus. The transport unit on the glass 2
It is transported by the frictional force of the 30 transport belts 33.

The transport belt 33 is stretched between a rotatable transport drive roller 31 and a transport driven roller 32 on bearing plates fixed to both side walls of the housing, and can be rotated forward and reverse by a motor M. I have. The lower running surface of the conveyor belt 33 is pressed against the platen glass 2 by pressing rollers 34A, 34B, and 34C. Reference numeral 35 denotes a pressure contact roller which is pressed against the conveyance belt 33 and is driven to rotate so as to increase the amount of winding of the conveyance belt 33 around the drive roller 31.

When the trailing edge of the document D is detected by passing the trailing edge of the document D through the passage sensor S3, the trailing edge of the document D is controlled by a pulse count by an encoder synchronized with the transport driving roller 31. At a predetermined image reading position. Thereafter, copying is performed by optical scanning in the copying machine body 1. After the image reading and scanning, the transport belt 33 is driven to rotate forward to feed the document D to the discharge reversing unit 40.

The original D conveyed to the paper discharge reversing section 40 passes through a guide plate 43, and is then driven by a paper discharge reversal roller 41 and punch rollers 42A and 42B.
The sheet is conveyed after being nipped by the sheet discharge reversing switching means 44, a sheet discharge restricting member (movable pressing member) 45, and a sheet discharge roller 46, and is discharged to a sheet discharge tray section 50 outside the apparatus.

The trailing edge of the conveyed document D is detected by a document ejection detecting sensor (discharge sensor) S4 near the pinch roller, and after a time necessary to clamp the trailing edge, a sheet ejection solenoid is operated. Activate SD2 to move the movable pressing member 45
Is displaced, and the vicinity of the rear end of the document D is nipped by a discharge roller 46 and a movable pressing member 45 that rotate at a low speed. Discharged on 51.

Next, FIG. 3 will be described from the driving system.
FIG. 3 is a configuration diagram of the drive system viewed from the original pressing surface side of the transport belt.

A driving source motor M is provided substantially at the center of the automatic document feeder, and a driving system for a feeding unit 20 is provided at the left side of the drawing, a transporting unit 30 is provided at the center, and a discharge unit 40 is provided at the right side. I have. The pulleys P1 and P2 on the intermediate shaft 61 are rotated via the gear G0 and the gear G1 of the intermediate shaft 61 using the motor M as a drive source.
The belt B1 around the pulley P1 transmits a driving force to the intermediate conveyance roller shaft 62 having the pulley P3. Meanwhile, the intermediate shaft
The belt B2 for winding the pulley P2 on 61 is a reversing roller shaft
The driving force is transmitted to 63.

An electromagnetic clutch (registration clutch) MC for turning on / off the driving force is provided on the intermediate conveyance roller shaft 62.
2. An intermediate conveyance pulley P3 and an encoder 64A are provided. The pulley P4 on the shaft of the intermediate conveyance roller shaft 62 transmits driving force to the clutch pulley P6 via the belt B3 integrally with the pulleys P3 and P5. The pulleys P3 and P
4 and a pulley P5 integrated with a pulley P7 via a belt B4.
To transmit the driving force. The paper feed drive shaft 66 is provided with a paper feed clutch MC1 for turning on / off the drive transmission from a pulley P7.

The transfer clutch shaft 65 is
A transport clutch MC3 for turning on / off the pulley P6, an electromagnetic brake MB, an encoder 64B, and a pulley P8 fixed to the transport clutch shaft 65 are provided. The pulley P8 has a pulley P9 via a belt B5. The driving force is transmitted to the transport drive roller shaft 67. The transport drive roller 31 is formed integrally with the transport drive roller shaft 67. A transport belt 33 is wound and rotatable between the transport drive roller 31 and the transport driven roller 32.

On the other hand, the drive transmission system branched rightward in the figure from the pulley P2 via the belt B2 includes pulleys P20, P21,
Via the gears G20 and G21, a reversing roller shaft 63 integral with the paper reversing roller 41 is driven and rotated.

A pulley P22 provided at the other end of the reversing roller shaft 63
Rotates the pulley P23 and the discharge roller 46 integral therewith via the belt B20.

The gear G20 has a one-way clutch C5.
However, the pulley P20 has an electromagnetic clutch (reversed discharge clutch)
MC4 is built in each.

Thus, at the time of reverse rotation of the motor, G20 integrated with P21 and G20 and built-in one-way clutch C5
As a result, when viewed from the front, it rotates CW (clockwise). When the motor is running forward, the anti-nuclear discharge clutch MC4 is turned on and off.
With this, clockwise rotation or stop can be selectively performed from the pulley P20. At the time of forward rotation, the gear G20 rotates in the opposite direction to that at the time of reverse rotation, so that drive is not transmitted by the one-way clutch C5. 68A and 68B are frames fixed to the apparatus main body. Each of the belts used was a toothed belt (timing belt), and each pulley was a toothed pulley (timing pulley).

Next, the structure of each section of the feeding section 20 of the automatic document feeder according to the present invention will be described.

FIG. 4 is a side view of the driving system of the feeding section 20.

The oscillating shaft 21A of the movable guide plate 21 is rotatably supported by a bearing of the machine frame side plate, and is always urged by being pulled in one direction by a spring.

A movable plate lever (cam follower) 213 is fixed to one end of the vibration shaft 21A. The movable plate lever 213 is in pressure contact with a peripheral surface of an eccentric cam plate 215 fixed to a rotating shaft 214 of a gear G12 meshing with a gear G11 fixed to the shaft end of the paper feed drive shaft 66.

A spring clutch with a pawl is provided coaxially with the rotation shaft 214 of the eccentric cam plate 215, and a protrusion of the slide operation plate is engaged with a pawl of the clutch. The slide operation plate is slidably supported by a support plate that supports and fixes the sheet feeding solenoid SD1, and is urged by a return spring.

Next, the operation of the movable plate operating means will be described.

In response to the copy start signal, the main motor M starts driving rotation, the driving rotation is transmitted to the sheet feeding driving shaft 66 via the intermediate conveying roller shaft 62, and transmitted to the gear G12 via the coaxial gear G11. Then, the eccentric cam plate 215 integrated with the spring clutch is rotated. At the time of the copy start signal, the paper feed clutch MC1 is in the off state, and the driving force is not transmitted to the paper feed belt 23 and the feed roller 24.

When the feed solenoid SD1 is turned on, the rotation of the eccentric cam plate 215 integrated with the spring clutch starts,
The movable plate lever 213 is swung along the cam peripheral surface of the eccentric cam plate 215 to raise the movable guide plate 21.

After a lapse of a predetermined time by the timer from the copy start signal, when the paper feed clutch MC1 is turned on, the movable guide plate 21 and the separation belt 23 which have already risen and are pressed against each other are pressed.
Starts rotating, and feeds the document D to the separating means.

FIG. 5 is a plan view of a main part of the feeding section 20.

The feed belt 23 of the feeding means is
A belt drive roller 241 fixed to the sheet feed drive shaft 66 and a driven roller 242 provided near the separating means can be wound around each peripheral surface and rotated. A pair of delivery rollers 243 are provided on both side ends of the belt drive roller 241. The outer diameter of the feed roller 243 is set so as to be equal to the circumferential speed of the feed belt 23. At the time of feeding the original, the movable guide plate 21 rises and presses against the original feed belt 23, and then the feed belt 23 and the pair of feed rollers 243 load the original at the same peripheral speed by the driving rotation of the paper feed drive shaft 66. The sheet passes through the upper surface of the feeding regulating member 22 and is sent to the nip portion of the separating means.

FIG. 6A is a side sectional view of a double feed prevention roller (retard roller) 25 of the separating means, and FIG. 6B is a sectional view of the roller 25 taken along the line AA.

A torque limiter 252 is mounted on a retard roller shaft 251 for preventing double feed of the double feed prevention roller 25.
A protrusion 252a of the torque limiter 252 and a stop collar 253
Each end of the double feed reverse rotation spring 254 is engaged with the insertion hole 253a. The double feed reverse rotation spring 254 and the stop collar 253 are fitted on the double feed prevention retard roller shaft 251. The stop collar 253 is press-fitted with a one-way clutch 255, and the double feed reverse spring 254 does not open in the direction of the arrow shown in FIG. Therefore, the original is registered with the registration sensor S
2 or the passage sensor S3, when a double feed of the original is detected, or when the original stops as a paper jam in the feeding path of the feeding unit 20, the original is pulled out to the Even if the feed preventing roller 25 is rotated in the reverse direction, the deformation of the double feed reverse rotation spring 254 is prevented.

FIG. 7A is a sectional view of the separating means.
(B) is an adjusting plate 24 for adjusting the height position of the driven roller 24B.
FIG. 6 is a perspective view of FIG.

A sheet feed drive shaft 66 is fitted in a bearing 245 provided at a fixed position of a mounting plate 244 fixed above the separating means, and a drive roller 241 integral with the feed shaft is rotatably supported. . A shaft end 242a of the driven roller 242 is movably held in a U-shaped long groove 244a provided on one side of the mounting plate 244.

The upper end of the shaft end portion 242a is pressed against the lower end surface 246b of the adjusting plate 246, and two left and right small screws 247 screwed into the screw holes of the mounting plate 244 for adjustment after adjustment. The right and left heights are adjusted by pressing with the pressing portion 246c.

An elongate hole 246a protrudes from the upright surface of the adjusting plate 246, and a small screw 248 penetrates into a screw hole of the mounting plate 244. The adjustment plate 246 moves along the upright surface of the mounting plate 244 by adjusting the two small screws 247, and the lower end surface 246b of the adjustment plate 246 presses the shaft end 242a of the driven roller 242 to be driven. The height of the roller 242 is adjusted.

On the other hand, the double feed prevention roller 25 is capable of swinging the swing plate 256 about the fulcrum shaft 257, and is urged by a spring 258 to be constantly nip pressed against the feed belt 23.

A stopper member 22 is fixedly mounted on a claim (both side plates) of the feeding portion 20 supporting the fulcrum shaft 257. On the back side of the stopper member 22, a double feed regulating member 22 is provided.
1 is integrally fixed by bonding with double-sided tape or the like. The double feed restricting member 221 restricts the number of documents to a small number before the document fed from the bundle of documents abutting the stopper member 22 by the feed belt 23 and the feed roller 243 reaches the nip position of the separating unit. Do (before judgment)
Things. The double feed restricting member 221 is a friction plate processed with synthetic leather or the like, and its upper surface forms a gentle curved surface, and maintains a minimum gap with the driven roller 242 near the nip position. Therefore, the driven roller near the nip position
It is necessary to maintain the gap h between the lower surface of 242 and the upper surface of the double feed restricting member 221 at an optimum size.

Next, the gap adjusting operation by the adjusting plate 246 will be described.

Loosen the horizontal machine screw 248 and adjust the adjustment plate 246
Is movable.

The adjustment screw is moved up and down by rotating the machine screw 247 in the vertical direction forward or backward to move the adjusting plate up and down.
The gap h between the upper surface of the double feed regulating member 221 at the fixed position and the lower surface of the driven roller 242 is adjusted to a predetermined optimum value by moving the shaft end 242a of the driven roller 242 abutting on b vertically. . Note that, due to the vertical movement of the driven roller 242, the double feed prevention roller 25 that is in pressure contact with the feed belt 23 wound around the driven roller 242 is urged by a spring 258 to swing.

When the adjustment of the gap h is completed, the small screw 248 is tightened to fix the adjusting plate 246 to the mounting plate 244.

As described above, it is possible to adjust the gap h at the nip position by adjusting the height of the separating means, to improve the separating performance of the original, and to solve the problems such as double feeding and non-feeding of the original. Also, the accuracy of the mounting plate 244 and the driven roller 242
Even if there is a variation in component accuracy such as the diameter of the feed belt 23 or the thickness of the feed belt 23, it is possible to always exhibit stable document separation performance.

Next, the document feeding control of the feeding section 20 will be described.
A description will be given based on FIGS. 8, 9, and 10. FIG. 8 is a flowchart of document size detection, FIG. 9 is a detailed flowchart of document size detection, and FIG. 10 is a one-sided document copy mode (A
9 is a time chart in (DF mode).

(1) First Document (D1) Feeding (1a) The main motor M starts normal rotation when the copy button is turned on, and the movable guide plate 21 is lifted when the sheet feeding solenoid SD1 is turned on. Next, when the paper feed clutch MC1 is turned on, a small number of document bundles are sent out by the feed belt 23 and the feed roller 24 by the rotation of the paper feed drive shaft 66 and the drive roller 241 from the motor M via the drive transmission means.

(1b) The bundle of a small number of originals fed continuously is then separated between the driven roller 242 and the double feed restricting member 221 and sent to the nip position of the double feed prevention roller 25.

(1c) The fed bundle of documents is fed and separated by the feed belt 23 and the double feed prevention roller (with a built-in torque limiter 252) so that only the topmost document is separated and passed through the leading edge of the document. A signal is generated by detection by the registration sensor S2, and at this detection, the sheet feeding solenoid SD1 is turned off, the movable guide plate 21 is lowered to release the pressing, and the leading end of the document is conveyed to the nip position of the registration roller pair 26.

(1d) The leading edge of the document is brought into contact with the peripheral surface of the roller near the nip position of the registration roller pair 26, and the leading edge of the document is slipped on the peripheral surface of the roller while applying a conveying force for a certain time to form a loop (accumulation). And correct the skew of the original.

(1e) After a lapse of a predetermined time from the detection of the leading edge of the document by the resist sensor S2, the registration roller pair 26 starts rotating by turning on the registration clutch MC2 and the conveying clutch MC3, and takes in the leading edge of the document D1. When the leading end passes through the passage sensor S3, the registration clutch MC2 and the paper feed clutch MC1 are turned off. After detecting the trailing edge of the document D1 by the passage sensor S3, a fixed count is counted by the encoder 64B, and the reverse rotation brake is applied to the main motor M. After the constant count of the reverse rotation brake, the transport clutch MC3 is turned off, and after the constant count, the transport brake MB is turned on to stop the document abruptly, and the trailing edge of the document is moved to the document reading reference position BL of the platen glass 2. Stop the original so that

(2) Second Original (D2) Feeding (2a) Sending Out While the first original D1 is being exposed on the original platen glass 2, the second original preliminary feeding is performed. That is, after the preceding document D1 is stopped at the reference position BL, the paper feed solenoid SD1 is turned on to lift the movable guide plate 21 which has been stopped and lowered, and then the paper feed clutch MC1 is turned on to feed the belt 23 and the feed roller 24. Is rotated to feed the document D2.

(2b) Separation... (1b), (1)
Same as c) (2c) Registration: Same as (1d) above (2d) Standby: Thereafter, the registration clutch MC2 is turned on and the registration roller pair 26 is rotated to take in the original D2, and the original is detected by the passage sensor S3. The leading end passage is detected, the resist signal clutch MC2 and the sheet feeding clutch MC1 are turned off by this detection signal, and the registration clutch MC2 is temporarily stopped at a feeding upstream position near the document reading reference position BL on the document table glass 2 and stands by.

FIG. 11 is a main part configuration diagram of the feeding section 20 showing the original standby state.

At the stage before the detection of the document size, the distance L1 from the leading edge of the document to the standby state until the leading edge of the document passes through the passage sensor S3 is counted up by the encoder 64A and loaded into the hardware counter 72. In this standby state, the encoder 64A counts down and is not counted.

At the later stage of the document size detection, the remaining length L2 of the document for which the trailing edge of the document is detected by the passage sensor S3 is counted by the encoder 64A, and loaded into the hardware counter 72 by counting up, and the standby at the previous stage is performed. Counting of the pre-feed length L1 to the position and the length L2 of the re-feed at a later stage
The total count value is calculated by a hardware counter and an addition process by the CPU 73 to determine the document size L (= L1 + L2).

(3) At the same time when the exposure of the first document D1 is completed, the transport clutch MC3 is turned on, and the reverse discharge clutch M
C4 is turned on, and the transport driving roller 31 and the paper discharge reversing roller 41 rotate. The paper discharge sensor S4 detects the rear end of the first document D1, and thereafter, turns on the paper discharge solenoid SD2, raises the leading end of the switching claw 44, and performs deceleration discharge in conjunction with the movable pressing member 45. After completion of the document discharge, the discharge solenoid SD2 is turned off.

At the same time, the document D2 is stopped so that the rear end of the second document D2 is located at the document reading reference position BL.

(4) As described above, the subsequent document is preliminarily fed during the preceding document exposure, and stands by at an upstream position near the reading position. Then, when the exposure is completed, the preceding document is discharged,
At the same time, the subsequent document is stopped so that the rear end thereof comes to the reading reference position BL, and this is repeated thereafter.

(5) According to the automatic document feeder of the present invention, since the front end of the document is nipped by the pair of registration rollers 26, the charging force of the torque limiter built in the double feed prevention roller 25 of the separating means is used. The document will not be returned even if it is reversed. Also, before the original size detection by the original preliminary feeding, the leading edge of the original is preliminarily fed to an upstream position near the original reading reference position BL, so that copy productivity can be improved.

[0075]

As described above, according to the automatic document feeder of the present invention, the following excellent effects can be obtained in the document feeder.

(1) When one sheet of original sent from the separating means is preliminarily fed, the leading end of the original is nipped by the pair of intermediate conveying rollers (the pair of registration rollers). Even if the double feed prevention roller rotates reversely due to the charging force of the built-in torque limiter, the original is not returned and the original is reliably fed.

(2) Document size detection is accurate.

(3) The leading edge of the original document can be preliminarily fed near the upstream side of the original reading reference position of the original platen glass on the downstream side of the intermediate conveyance roller and the passage sensor, and the copy productivity can be improved. I do.

[0079]

[0080]

[0081]

( 4 ) The original can be fed directly from the separation section to the pair of registration rollers without using an intermediate roller or the like by using an inexpensive spring charge torque limiter, so that the original is reliably fed. In addition, the structure of the feeding section is simplified, and the feeding path can be shortened.

( 5 ) By providing a pair of feed rollers on both sides of the conventional feed belt, the load per unit area of the original on the upper surface of the original is reduced, and the original is prevented from being stained.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an automatic document feeder according to the present invention.

FIG. 2 is a cross-sectional view of a feeding unit of the automatic document feeder.

FIG. 3 is an overall configuration diagram showing a drive system of the automatic document feeder.

FIG. 4 is a side view of a configuration of a driving system of a feeding unit of the automatic document feeder.

FIG. 5 is a plan view of a main part of a feeding unit.

FIG. 6 is a cross-sectional view of a double feed prevention roller.

FIG. 7 is a sectional view of a separating unit and a perspective view of an adjusting plate.

FIG. 8 is a flowchart of document size detection.

FIG. 9 is a detailed flowchart of the document size detection.

FIG. 10 is a time chart of an ADF mode for one-sided original copy.

FIG. 11 is a main part configuration diagram of a feeding unit showing a standby state of a pre-fed document.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Copier main body 2 Platen glass (platen glass) 10 Document placement part 20 Feeding part 21 Movable guide plate 22 Stopper member 221 Double feed regulating member 23 Feed belt (Separation belt) 24,243 Feeding roller 241 Belt driving roller 242 Driven roller 244 Mounting plate 246 Adjustment plate 25 Double feed prevention roller (retard roller) 251 Double feed prevention retard roller shaft 252 Torque limiter 253 Stop collar 254 Double feed reverse rotation spring 256 Swinging plate 26 Registration roller pair (intermediate transfer roller pair) 30 transport unit 31 transport drive roller 33 transport belt 45 movable pressing member 46 discharge roller 62 intermediate transport roller shaft 65 transport clutch shaft 66 feed drive shaft 67 transport drive roller shaft 70 control means 71 control board 72 hardware counter M motor ( Main motor) MB Electromagnetic brake MC2 Registration clutch MC3 Transport clutch S2 Registration sensor S3 Passage Sensor h gap

Continuation of the front page (56) References JP-A-62-269853 (JP, A) JP-A-4-189240 (JP, A) JP-A-61-90952 (JP, A) JP-A-60-170329 (JP) , U) (58) Field surveyed (Int. Cl. ⁷ , DB name) B65H 7/02 B65H 9/14 G03G 15/00 107

Claims (3)

(57) [Claims] The method according to claim 1] originals stacked on the document stack section, delivery by delivery means, and fed to separate a piece of original by minute <br/> away means with a built-in torque limiter, the resist B < a feeding unit for feeding a document to the image reading unit on the platen glass after adjusting the posture of one document by a pair of rollers and waiting the document;
Paper discharge tray outside a machine and conveying section, the document delivered from the conveyance unit for unloading an original after image reading after stopping to the fed original predetermined image is conveyed to the reading position in the image reading unit a paper discharge portion for discharging the parts, and controls the drive means comprising a motor for driving at least said feeding unit and the conveyance unit, before
An automatic document feeder comprising: control means for calculating the length of the document ; wherein the automatic document feeder is located near the downstream side in the document feeding direction from the nip position of the registration roller pair of the feeding section, and provided with a passage sensor for detecting passage of the ends, prior to
Comprises a hardware counter for calculating the original length by the detection signal of the passage sensor in serial control means, the cashier the front end of the document fed by said separating means
Beyond the passage sensor by nipping the strike rollers preliminary feeding to the standby stop position upstream vicinity of the image reading unit
Then, after temporarily stopping at the standby stop position, further reading the image.
The controller re-feeds the paper toward the take-off section, and the control means calculates a required count m from the passage of the leading edge of the original document through the passage sensor to the standby stop position during the preliminary feeding and the re-feeding.
From the start feeding measures a required total number n to the rear end of the document passes through the passage sensor, the original is between paused
Figures are not measured, the and said required counts m and n Hardware
Automatic document feeder, characterized in that is what determines the document size by adding the air counter. 2. An image forming apparatus, comprising: an electromagnetic clutch provided at an end of a drive shaft of a pair of registration rollers of the feeding unit; and a photosensor provided near an upstream side in a document feeding direction from a nip position of the pair of registration rollers. The leading end of the document fed from the separation unit is detected for a predetermined time after the photosensor detects the document, and the document is fed to contact the nip of the registration roller pair in a stopped state to perform registration. feed automatic document according to claim 1, wherein the temporarily stopping by the nip state document is turned on for a certain time in the electromagnetic clutch to the standby position the document leading end Rikyu is fed by the resist roller pair apparatus. 3. A feed belt which presses an uppermost original surface of a stack of originals wound around a drive roller and a driven roller by feeding means of the feeder, and the drive roller sandwiching the feed belt 3. The automatic document feeder according to claim 1, wherein the automatic document feeder comprises a pair of feed rollers arranged on the drive shaft, and feeds the document by the feed belt and the feed roller.