JP2849846B2 - Automatic document feeder - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a recording apparatus such as an electrophotographic copying machine and an automatic document feeder in an image reading apparatus and the like.

[Background of the Invention]

The automatic document feeder is generally used by mounting it on a platen glass (platen glass) of an image exposure unit such as a copying machine. 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 it is exposed by an exposure unit lamp in the copier body, and is further conveyed to a document discharge table.

Conventionally, the operation of replacing the original on the platen glass by such an automatic document feeder is conventionally performed by detecting that the original on the platen has been ejected by a sheet ejection sensor, and then sending the next original from the stack unit to the original platen glass. It was conveyed upward 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.

[Problems to be solved by the invention]

When using the automatic document feeder to exchange documents within the return time of the scanning optical system during the document exchange operation in which documents are automatically fed and ejected onto the platen, copy productivity will be 10%.
It is 0% and no wasted time is required. However, as the size of the document decreases, the paper interval between the documents increases, resulting in a loss of transport time and a decrease in copy productivity.

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.

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 separation performance occur.

Eliminate the above problems and do not increase the document transport speed.
Japanese Patent Application Laid-Open No. 1-236136 discloses a conventional technique of a document feeder for shortening the time required to change a document.

This document transport device stops transporting the first document to a predetermined position and then stops transporting the second document to a position adjacent to the predetermined position and not on the upstream platen glass,
Next, the first document after the image reading process is conveyed to a downstream position on the platen glass adjacent to the predetermined position at a position where the first document can be conveyed by the conveyance unit, and at the same time, the second document is moved to the predetermined position. The conveyance is stopped, and the third and subsequent documents are sequentially stopped by repeating this procedure.

However, in this document transport method, since three documents move at the same time, when a jam occurs, the next document may collide with the preceding document and be damaged. Is also complicated.

Further, in the above example, the distance between the trailing edge of the first document on the platen glass and the leading edge of the second document on the feeding path is large, and the next document travel distance at the time of document replacement is increased. There is a disadvantage that the time required for document replacement increases.

To remedy these drawbacks, the leading edge of the next original is transported to a contact nip position between the transport belt on the platen glass and the platen glass and is kept on standby. However, the contact position of the transport belt is determined by the position of a document pressing roller that presses the transport belt against the platen glass surface from the inside of the transport belt, and the leading edge of the document cannot be brought closer to the preceding document. For this reason, when transporting small size documents,
It is impossible to shorten the document exchange time.

[Means for solving the problem]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-described problem in the automatic document feeder and to improve the number of copies to be processed.

In other words, when sending the next document to the temporary stop position during the preceding document exposure, the pause position of the next document should be as close to the trailing edge of the preceding document as possible, thereby shortening the document replacement time and improving the copy processing speed. It is the purpose.

An automatic document feeder according to the present invention, which achieves the above object, includes a paper feed unit for separating and feeding originals one by one from a bundle of originals stacked on an original placing table onto a platen glass, A transport section for stopping the transport of the fed document on the basis of a document copy positioned on the discharge side of the platen glass, and a transport section positioned opposite to the sheet supply section with respect to the platen glass, and image exposure completed A document discharge unit that discharges the document sent from the transport unit onto a discharge tray, and a document detection unit that detects a document size, and detects a next document during exposure of a preceding document by the document detection unit. In an automatic document feeder that separates and conveys to a standby position according to a result and keeps the standby, the conveyance unit includes a pair of rollers, a conveyance belt stretched between the pair of rollers, and an inside of the conveyance belt. Document holding roller and the front A movable pressing roller provided on the upstream side of the document pressing roller in the transport direction inside the transport belt and capable of pressing and separating the transport belt with respect to the document table glass; A driving unit that raises the movable pressing roller when the downstream side in the transport direction from the pressing position of the transport belt against the platen glass by the movable pressing roller is the standby position of the next original. Is what you do.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing a document conveying path of the automatic document conveying apparatus according to the present invention, FIG. 2 is a perspective view showing the appearance of the automatic document conveying apparatus mounted on a copying machine, and FIG. FIG. 4 is a schematic diagram of the entire drive system configuration of the apparatus, and FIG. 5 is a schematic diagram of a document conveying path at the time of duplex document copying. The illustrated devices are automatic document feeders (RADF) 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 (RADF) of the present invention is shown in FIGS.
As shown in the figure, a paper feeding unit 10 installed on the copying machine main body 1 for feeding one document from a bundle of documents placed on a document tray 11 onto the platen glass 2, A transport unit 20 that transports the original fed from the unit 10 to a predetermined position (image exposure scanning position) of the original table glass 2 on the original table, and a document sent from the original transport unit 20 after the image exposure is completed. And a document discharge unit 30 that discharges the paper onto a paper discharge tray 39.

First, FIG. 3 and FIG. 4 will be described from the driving system.
A motor M as a drive source is located at the center, and a paper feeding unit
10, a drive system for a transport unit 20 at the center and a document discharge unit 30 at the left are arranged. The toothed pulleys P1 and P2 are rotated via the gears G0 and G1 using the motor M as a drive source, and are branched to the paper feed unit 10 and the document discharge unit 30 by the toothed belts B1 and B2, respectively.

The drive transmission system branched to the right in the figure is a gear train G2, G3, G4, G
5, G6, the feed roller 15 for the separation belt of the paper feed unit 10
A and the intermediate transport roller 18 and the transport belt 2 of the transport section 20
1 Drive the driving roller 23. A clutch K1 is built in the gear G6 at the shaft end of the feed roller 15A, and becomes free except when the paper is rotated.

On the other hand, a drive transmission system branched leftward in the drawing from the pulley P1 via the belt B1 drives the paper discharge reversing roller 31 via the pulleys P4 and P5 and the gears G7 and G8. A one-way clutch K2 is provided on the gear G9, and a one-way clutch K3 is provided on the gear G7. As a result, the paper discharge reversing roller 31 and the paper discharge roller 35 always rotate in one direction in the direction of the arrow shown in the figure regardless of the forward / reverse rotation of the motor M.

In the schematic diagram of FIG. 5, the automatic document feeder according to the present invention is capable of double-sided copying of a double-sided document. When the original D passes through the same transport path as the normal one-sided copy and the first-side exposure (copy) is completed, the original D follows the path indicated by arrows S1 and S2, and is not discharged even after passing through the paper discharge reversing roller 31 and the pinch rollers 32 and 33. It is conveyed, takes the reversal path of the arrows R1 and R2, is sent back to the platen glass 2 again for the second side exposure (backside copying), is exposed (copied), and takes the path of the arrows S1 and S2 again. Indicates a state in which the sheet is discharged onto the sheet discharge tray 39 by the sheet discharge roller 35 via the sheet discharge reversing roller 31, the pinch rollers 32, 33, and the path of the arrow S3. An original placing table 11 is provided on the upper right side of the paper feeding unit 10 of the automatic document feeder, and enables the originals to be stacked and placed. On the downstream side of the leading end of the document table 11,
A solenoid SD1, a movable plate guide plate 12 swingable by the solenoid SD1, and a document leading end stopper 13 are provided.

When the stack of originals is placed on the original mounting table 11, the presence or absence of the originals on the original mounting table is detected by the original set detection sensor (zero original detection sensor) PS1, and the control panel of the copier body 1 is set to the RADF mode. Is displayed.

On the document mounting table 11, a width regulating plate 14 for regulating the width direction of the document is movably provided.

On the downstream side of the original placing table 11 from which the original is fed, there is provided a separation feeding unit including a feed belt 16 that winds around and rotates a feed roller 15A and a driven roller 15B, and a double feed prevention roller 17 located below the feed belt. It is provided. The driving force of the driving motor M is transmitted to the separation sheet feeding means via the electromagnetic clutch K1.

By manipulating the copy button 4 on the control panel 3 of the copier body 1, the automatic document feeder is started up and energized by the paper feed solenoid SD1 to operate. , The document bundle is pressed against the surface of the feed belt 16 and the driving motor M
The original is sent out by the feed belt 16 which has started to rotate by the driving force of, and further, only the uppermost one of the plurality of originals sent out by the fixed double feed prevention roller 17 is separated and sent out. At this time, double feed prevention roller
The lower document following at 17 is prevented from advancing.

A document passing detection sensor (document size detection sensor) PS2, an intermediate conveyance roller 18, and a curved guide plate 19 are provided on the downstream side of the document feeding of the separation sheet feeding means. Document D
When the second clutch K2 is turned on, the nip is conveyed to the intermediate conveyance roller pair 18, and when the tip crosses the sensor PS1, the first clutch K1 that was driving the feed roller 15A is turned off and the feed belt 16 is turned off. Is driven and rotated between the one-way clutch press-fitted into the feed roller 15A and the drive shaft until the document D is completely removed, and stops.

When the leading edge of the original sent from the separate sheet feeding unit is detected by the original passage detection sensor PS2 and the sensor PS1 is turned on, the first timer TM1 starts counting. Next, a pair of intermediate conveyance rollers 18 in the vicinity thereof
And is fed toward the original platen glass 2 between the guide plates 19. Further, the original D is transported by a transport belt 21 that rotates at substantially the same speed as the peripheral speed of the intermediate transport roller 18.
And is conveyed over the document glass 2. The first
When the timer TM1 counts up, the conveyor belt 21
The third clutch K3 that was driving the brake is turned off and the brake (B
K) operates to stop the original D by hitting the original stopper 3 projecting from the end of the original platen glass 2 on the paper discharge side. The document size (length) is detected by the sensor PS2 detecting the passage of the trailing edge of the document. In addition, the sensor PS
Reference numeral 2 also detects a paper jam in the paper feed unit 10.

The transport belt 21 is stretched between a transport belt driving roller 22, a driven roller 23, two document pressing rollers 24, 25, and a movable pressing roller 26 that can be pressed and separated, and can be rotated forward and reverse by a motor M. I have.

The lower running surface of the conveyor belt 21 is
Platen glass 2 by 24, 25 and movable pressing roller 26
It is pressed against the surface.

Here, the document length is measured from the time when the leading edge and the trailing edge of the document D pass through the sensor PS1, and the mode is switched to three types in the following three ranges.

(I) When the document length L is L1>L> L3 (ii) When the document length L is L2>L> L1 or L3> L (iii) When the document length L is L> L2 L1 is the distance from the document stopper 3 to the document pressing roller 25, L2 is the distance from the document stopper 3 to the movable pressing roller 26, and L3 is the distance from the document pressing roller 25 to the intermediate conveyance roller 18.

FIG. 6 is a schematic diagram for explaining the arrangement and distance relationship between the main document conveying members of the automatic document conveying apparatus.

(I) When L1>L> L3 (Small Size Document) The leading end of the document D1 comes into contact with the document stopper 3 and stops, and the movable pressing roller 26 is raised by a solenoid (not shown). As a result, the transport belt 21 changes from the stretched position shown by the broken line in FIG. 6 to the state shown by the solid line, and the transport belt 21 between the document pressing roller 25 and the movable pressing roller 26 rises, and Creates a gap in At this time, the driven roller side of the conveyor belt 21 also applies tension tension to the outside by a spring pressure, and the movable pressing roller
Absorption of slack in the conveyor belt 21 caused by the movement of 26 is absorbed.

The document D is exposed at a stop position on the platen glass 2 by an exposure lamp 6 in the copying machine main body 1, and a document image is formed on a recording body by scanning of a scanning exposure unit including a lens, a mirror, and the like.

At the same time as the above exposure, the first clutch K1 and the second clutch K2 are turned on, the next original D2 is sent out, and when the leading end crosses the sensor PS2, the second timer TM2 starts counting. The second timer TM2 is set so that the leading end of the document D2 exceeds the movable pressing roller 26 and counts up before the document pressing roller 25. When counting up, the second clutch K2 of the intermediate transport roller 18 is turned off.
Then, the brake is turned on, and the leading end of the next document D2 stops between the document pressing roller 25 and the movable pressing roller 26 and waits.
This operation is configured to be completed by the completion of the exposure of the set number of copies of the preceding original D1.

FIG. 7 is a schematic diagram showing the stop exposure of the preceding original D1 and the standby state of the next original D2, where L is the original length, A is the interval from the rear end of the preceding original D1 to the leading end of the next original D2, B indicates the distance (discharge distance) from the document stopper 3 to the discharge roller 35.

Next, upon completion of the set number of exposures, the clutch K2 and the clutch K3 are turned on, the preceding document D1 is discharged, and the next document D2 stopped at the standby position is conveyed on the platen glass 2 to the document stopper 3. Strike. At this time, the distance required to complete the discharge of the preceding document D1 is (L + B) with respect to the distance (A + L) required to stop the conveyance of the next document D2, but (A + L) <(L + B) The document stops during the paper ejection process.

However, if (A + L)> (L + B), that is, (A> B) must be set so that (A> B).

However, as shown in FIG. 1, in a structure in which the original D after the exposure processing is reversed and discharged and placed on the upper surface side of the automatic document feeder, the discharge distance B is long, and therefore the interval A is long. Must be bigger. For this reason, the time required to replace the original D2 from the standby position to the stop position of the original stopper 3 becomes longer.

In the automatic document feeder of the present invention, the clutch K3 is turned off.
After the brake (BK) is turned on, the discharge reversing roller 31
Is turned on, and a fixed time after the trailing edge of the document D has traversed the sensor PS3, the solenoid SD4 is turned on, and the pressure roller is rotated to the discharge roller 35 which rotates at a lower speed than the discharge reverse roller 31.
By pressing 34, the document D is nipped and discharged at a low speed. Each speed is determined so that this discharging operation is completed by the time the copying operation of the next original is completed. The above operation is for document D
Repeat until there is no more.

(Ii) In the case of L2> L> L1 or L3> L FIG. 8 is a schematic diagram for conveying a document of the above size.

With the movable pressing roller 26 lowered with respect to (i) above, the temporary standby position at the leading end of the next document D2 is set between the movable pressing roller 26 and the intermediate conveyance roller 18.

If the document length L is equal to or less than L3 (the distance from the nip position of the intermediate conveyance roller 18 to the pressing position of the document pressing roller 25), if the movable pressing roller 26 is raised as described in (i) above. The platen glass 2 between the rollers 18 and 26
Since there is no pressing force on the sheet, the transfer force is reduced, and transfer failure is likely to occur. Therefore, it is necessary to lower the movable pressing roller 26.

(Iii) When L> L2 FIG. 9 is a schematic diagram for conveying a document of the above size.

In this case, the standby position is set to the position near the glass edge, or the next document D2 is not set in the standby operation, and the next document D2 is fed from the standby position before the glass or the next document D2 in synchronization with the discharge of the preceding document D1. From the nip position of the double feed prevention roller 17,
After the next document D2 is stopped by the document stopper 3, the preceding document D1 is discharged at a low speed during the exposure operation.

In the above description, the document length is detected by the document passage detection sensor PS2.However, the width direction of the document size is detected by the movement amount of the horizontal width regulating plate 14 on the document table 11, and the predetermined feed corresponding thereto is detected. It is also possible to detect the length of the document based on the length in the direction and control the vertical operation of the movable pressing roller 26 in advance. Alternatively, the document size may be input by key and stored.

FIG. 10 is a perspective view showing an embodiment of a driving device of the movable pressing roller 26.

A spring-biased tension member is attached to both shaft ends of the driven roller 26.
23A and 23B are provided, and are movable in parallel with the document conveying direction along a long groove (not shown). The drive roller
The transport belt 21 wound between the roller 22 and the driven roller 23 is stretched without slack by the stretching members 23A and 23B.

Both shaft ends of the movable pressing roller 26 are supported by arms 28A and 28B, and the arms 28A and 28B are integral with the support shafts 29A and 29B.
It is swingably supported. One end of an arm 29C is integrally attached to the one support shaft 29B. The arm 29C
A plunger of a latch type solenoid SD5 is rotatably connected to the other end. Reference numerals 29D and 29E denote bearings which are fitted on the support shafts 29A and 29B and rotatably supported.

When the solenoid SD5 is energized and the plunger is sucked, the arm 29C rotates counterclockwise about the support shaft 29B, so that the arms 28A and 28B are integrated and the support shaft 2 is rotated.
By rotating the movable pressing roller 26 around the center 9B, the movable pressing roller 26 is swung upward to move away from the inner surface of the conveyor belt 21 and release the pressing force on the conveyor belt 21. The slack of the conveyor belt 21 that occurs at this time is tensioned by the spring urging force of the tension members 23A and 23B.

When the suction force of the solenoid SD5 is released and the solenoid SD5 returns, the movable pressing roller 26 descends by its own weight and the urging of the spring, and presses the inner surface of the transport belt 21 to be pressed against the upper surface of the document glass 2.

FIG. 11 is a perspective view showing another embodiment of the driving device of the movable pressing roller according to the present invention.

In this embodiment, the driven roller 23 is rotatably supported at a fixed position, and the slack of the transport belt 21 caused by the vertical movement of the movable pressing roller 26 is eliminated by the tension roller 27A interlocked with the movable pressing roller 26. It is characterized by: Arm 28 supporting both shaft ends of movable pressing roller 26
C and 28D are swingable by support shafts 29A and 29B.
A tension roller 27A is rotatably supported at the other end of each of the arms 28C and 28D. A support shaft 29B integral with one arm 28D is rotationally driven by a solenoid SD5 as in the above-described embodiment.

The arms 28C and 28D rotate counterclockwise by the suction force of the solenoid SD5, and the movable pressing roller 26
21 and the tension roller
27A is pressed against the upper outer surface of the transport roller 21.

FIG. 12 is a perspective view showing still another embodiment of the driving device of the movable pressing roller according to the present invention.

Arms 28E, 28F supporting both ends of the movable pressing roller 26
Is swingable by supporting shafts 29A and 29B. At an intermediate position between the arms 28E and 28F, a tension roller 27B is rotatably supported. The lower end of an arm 29C fixed to the other end of a support shaft 29B integral with one arm 28F is connected to a plunger of a solenoid SD5.

By the suction operation of the solenoid SD5, the arms 28E, 2
8F swings counterclockwise, the movable pressing roller 26 is separated from the lower inner surface of the conveyor belt 21, and the tension roller 27B pushes up the upper inner surface of the conveyor belt 21 to remove slack of the conveyor belt.

〔The invention's effect〕

As described above, according to the automatic document feeder of the present invention, the document replacement time can be reduced without increasing the load on the motor or increasing the power consumption, and without requiring the provision of a large motor. In addition to shortening, the separation performance is improved due to low-speed separation during document feeding, document conveyance is smoothed,
In addition, it has become possible to prevent damage to the leading edge of the document.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a document feed path of an automatic document feeder according to the present invention, FIG. 2 is an external perspective view of the automatic document feeder mounted on a copying machine main body, and FIG. FIG. 4 is a schematic diagram of the entire drive system configuration of the present apparatus, FIG. 5 is a schematic diagram of a document conveyance path at the time of duplex document copying, and FIG. 6 is an automatic document conveyance. FIG. 7 is a schematic view for explaining an arrangement distance between main document conveying members of the apparatus.
8 and 9 are schematic views showing a process of transporting originals of various sizes, and FIGS. 10, 11, and 12 are perspective views showing another embodiment of the driving device of the movable pressing roller according to the invention. It is. DESCRIPTION OF SYMBOLS 1 ... Copier main body, 2 ... Document platen glass 5 ... Document stopper, 10 ... Supply section 11 ... Document placement table, 16 ... Feed belt 18 ... Intermediate transport roller, 20 ... Transport section 21 … Conveying belt, 22… Conveying roller 23… Driving roller, 24,25… Document pressing roller 26… Movable pressing roller, 27… Tension roller 30… Document discharging section, 31… 34 ... Crimping lever, 35 ... Discharge roller D ... Document, D1 ... Preceding document D2 ... Next document 28A, 28B, 28C, 28E, 28F ... Arm K1, K2, K3 ... Clutch M ... Motor PS2: Document size detection sensor PS3: Document discharge detection sensor SD1: Feed unit solenoid SD2: Transport unit solenoid SD3: Discharge unit solenoid SD5: Movable pressing roller drive solenoid A, B, L1, L2 , L3 …… Interval L …… Document length BK …… Brake

Claims (2)

(57) [Claims] A sheet feeding unit for separating and feeding originals one by one from a bundle of originals stacked on an original placing table onto an original table glass; and an original sheet fed from the sheet feeding unit to the original table glass. A transport unit for stopping transport based on a document copy reference positioned on the upper discharge side; and a document sent from the transport unit after image exposure is completed, the transport unit being positioned on the opposite side of the paper feed unit with respect to the platen glass. And a document detection unit that detects the size of the document. During the exposure of the preceding document, the next document is separated and conveyed to the standby position according to the detection result of the document detection unit. An automatic document feeder, wherein the transfer unit includes a pair of rollers, a transfer belt stretched between the pair of rollers, a document pressing roller disposed inside the transfer belt, and the transfer unit. Press the document inside the belt. A movable pressing roller that is provided on the upstream side in the transport direction from the feeding roller and that enables the transport belt to be pressed into contact with and separated from the document table glass. An automatic document feeder, comprising: a driving unit that raises the movable pressing roller when the downstream side in the transport direction of the transport belt from the pressure contact position of the transport belt against the platen glass is set as the standby position for the next document. 2. The apparatus according to claim 1, wherein the length of the document in the transport direction is less than a length from the document copy reference to the document pressing roller located on the most upstream side in the transport direction, and the most upstream side in the transport direction. 2. The automatic document feeder according to claim 1, wherein the drive unit raises the movable pressing roller when it is detected that the length is greater than a length from the document pressing roller to the intermediate feed roller of the sheet feeding unit. .