JP3074966B2 - Paper transport device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet conveying apparatus, and more particularly, to a sheet conveying apparatus for separating stacked paper sheets one by one and feeding the sheets in one direction.

[0002]

2. Description of the Related Art In recent years, in order to improve copy efficiency, a copying system has been widely constructed by combining an electrophotographic copying machine with an automatic document feeder. In addition, there is a demand for a high-speed copying process, and with an increase in the speed of copy sheet conveyance in a copying machine body, a high-speed sheet (original) conveyance technique is also required for an automatic document conveyance device.

[0003] In the paper transport technology, a paper feed mechanism that reliably separates the stacked paper sheets into one sheet and feeds the paper in a fixed direction without skew has a very delicate and difficult problem. There is a limit to speeding up.
Therefore, a conveying means (register roller) having a paper register function is provided downstream of the separating means in the conveying direction, and
The document separated into sheets is brought into contact with the nip portion of the register roller to form a slight loop at the leading end, and after adjusting the posture of the document, the document is conveyed at a high speed.

[0004] However, when the conveyance is started at a high speed by the register roller, if the driving of the upstream separation means is stopped, the separation means acts as a large load on the conveyance of the document until the original leaves the separation means. However, there has been a problem that the document is damaged, and noise (loop cancellation sound) is emitted at the moment when the loop at the leading end is eliminated. As a solution to this, it has been proposed to rotate the separating means even when a document is conveyed at high speed by a register roller. As a result, although the damage to the original document and the sound for eliminating the loop are reduced, the separation performance is reduced, and there is a possibility that the feeding is caused. That is, the separating means prevents the advance of the second and third originals which are to be fed together at the same speed at the transport speed (first speed) at the time of separation. Is configured. But,
When the first original is conveyed by the register roller at a second speed higher than the first speed, the second and third originals are also fed at the second speed and enter the separating means. I do. However, the separation performance of the separating means does not effectively act on the next original fed at the second speed, and the probability that the next original will pass through the separating means increases.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to not only eliminate the damage to the paper and the noise for eliminating the loop, but also to prevent the paper separation performance from being lowered even when the high-speed conveyance is performed. An object of the present invention is to provide a sheet transport device. In order to achieve the above object, the paper transport device according to the present invention is
In addition to sequentially arranging pickup means for stacked paper sheets, separating means for separating picked-up sheets into one sheet, and conveying means for separated sheets, rotation driving means are provided, and the separating means conveys sheets. And a separation member for separating the conveyed paper into one sheet. Furthermore, between the normal rotation member and the separation member,
The first pressure required to separate the sheet when the sheet is conveyed at the first speed by the normal rotation member, and the sheet pressure when the sheet is conveyed at the second speed by the downstream conveying means. A pressurizing means for selectively applying a second pressure necessary for separation is provided. The separating means is driven by the first driving means (first speed). At this time, the leading end of the separated sheet abuts on the non-driven conveying means, where the leading end of the sheet forms a loop. And the skew is corrected. After a certain period of time, the conveying unit is driven by the second driving unit (second speed), and when conveyance of the sheet by the conveying unit starts, the separating unit is driven by the first driving unit for a predetermined time. The predetermined time is at least a time until the loop at the leading end of the paper is eliminated.By driving the separating means, the load on the paper is greatly reduced, the loop elimination sound is not generated, and the paper is damaged. Disappears. On the other hand, the pressurizing means applies the first pressure between the normal rotation member and the separating member until the conveying means is driven, and applies the second pressure after the conveying means is driven. Let it. That is, the pressure of the separating means is switched to an optimum value in accordance with the sheet conveying speed, and the separating performance of the separating means does not decrease.

Normally, the second speed by the conveying means is set to be higher than the first speed by the normal rotation member, and the first pressure is such that two or more sheets intervene between the normal rotation member and the separation member. When the separation member is rotated by the first driving means so as to push the sheet back to the upstream side, and when one sheet is interposed, the separation member is set to a value which rotates following the conveyance of the sheet to the downstream side. . At this time, the second pressure is set smaller than the first pressure. If the pressure is reduced, even if the second sheet and the third sheet enter while the sheet is being conveyed between the normal rotation member and the separation member, the separation member immediately rotates it even if it is driven and rotated. It stops, reverses, and pushes the entering paper back to the upstream side. When one sheet is conveyed in a state where the second pressing force is acting, the separation member is driven to rotate,
Either stopped or reversed.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a sheet conveying apparatus according to an embodiment of the present invention. FIG. 1 shows an automatic document feeder 50 (hereinafter, referred to as ADF), a copying machine main body 1 and a sorter 90 according to an embodiment of the present invention.

At substantially the center of the copying machine main body 1, a photosensitive drum 10 is installed so as to be rotatable at a constant peripheral speed v in the direction of arrow a. Around the photosensitive drum 10, along a rotation direction thereof, a main eraser 11, a charging charger 12, a sub-eraser 13, a developing device 14 using a magnetic brush system, a transfer charger 15, and a paper separating charger 1.
6. A blade-type cleaner 17 is provided. Further, an optical system 20 is disposed above the photosensitive drum 10.

The photoreceptor drum 10 is a known drum having a photoreceptor layer on the surface, and rotates in a direction indicated by an arrow a in response to rotation of a main eraser 11, a charging charger 12, and a sub-eraser 13.
As a result, the image of the document set on the platen glass 29 is exposed by the optical system 20. The electrostatic latent image formed on the photosensitive drum 10 by the exposure is converted into a toner image by the developing device 14.

The optical system 20 scans an image of a document set on the platen glass 29 on the photosensitive drum 10 directly below the platen glass 29. That is, at the time of image scanning, the exposure lamp 21 and the first mirror 22 are integrated with the peripheral speed v of the photosensitive drum 10 (constant irrespective of the same magnification or variable magnification) by v / m (m: copy magnification). Arrow b at speed
Move in the direction. At the same time, the second mirror 23 and the third mirror 24 move in the direction of the arrow b at a speed of v / 2m. When the copy magnification is changed, the projection lens 25 moves on the optical axis and the fourth mirror 26 swings to correct the optical path length.

The copy sheets are accommodated in an upper sheet feeding section 31 and a lower sheet feeding section 34, and are fed one by one from one of the sheets based on an operator's selection. Each paper feed unit 31, 3
4 is provided with paper feed rollers 32 and 35, and separation rollers 33 and 36 composed of a forward rotation roller and a reverse rotation roller.
The paper fed from the upper paper feed unit 31 is transported by a transport roller 37.
It is sent out to the timing roller 38 installed immediately before the image transfer section through b and 37c. Sheets fed from the lower sheet feeding section 34 are transport rollers 37a, 37b, 37c.
To the timing roller 38.

Immediately above the upper paper feed unit 31, both sides /
An intermediate tray 47 for processing the composite copy is provided. The sheet re-supplied from the intermediate tray 47 by the sheet re-supply roller 48 and separated by the separating roller 49 is sent out to the timing roller 38 through the transport roller 37c. The sheet sent to the timing roller 38 once waits here, and is sent to the transfer unit by turning on the timing roller 38 in synchronization with the image formed on the photosensitive drum 10. The paper is brought into close contact with the photosensitive drum 10 at the transfer section, and the transfer charger 15
The toner image is transferred by the corona discharge from the photosensitive drum 10 and separated from the photoreceptor drum 10 by the AC corona discharge from the separation charger 16 and the strength of the paper itself. Thereafter, the sheet is sent to the fixing device 40 through the conveyor belt 39,
The toner is fixed, and is stored in the sorter 90 through the transport rollers 41 and 42.

On the other hand, the photosensitive drum 10 keeps the arrow a even after the transfer.
Then, the remaining toner is removed by the cleaner 17 and the remaining charge is erased by the main eraser 11 to prepare for the next copy process. In the composite copy mode, the paper on which the image of the odd-numbered original has been transferred is changed in the paper passing direction downward by the paper passing switching claw 43, and
4, 45, and 46 are stored on the intermediate tray 47. In the two-sided copy mode, the sheet is temporarily sorted by the sorter 90.
And is switched back by reversing the transport roller 42, the paper feed direction is changed downward by the switching claw 43, and the transport rollers 44 and
5 and 46 are stored on the intermediate tray 47. Thereafter, the sheet is re-fed from the intermediate tray 47 in order to double-sided / composite copy the image of the even-numbered document.

By the way, in the copying machine body 1, the copying process is started and the first sheet is
When the printer stands by just before 8, the advance processing is performed in which not only the second sheet but also the third sheet is fed to the sheet feed path in advance. For example, in the paper feeding from the lower sheet 34, second sheet P ₂ Following first sheet P ₁ is fed to the feeding path, further the third sheet P ₃ Also transport roller 3
Paper is fed just before 7a. Such advance processing is performed not only in the multi-copy mode but also in the single copy mode using the ADF 50 to improve the copy speed.

On the other hand, the sorter 90 is a non-sort tray 9
This is a well-known type having a 1, 20-stage sort tray 92, and the description thereof is omitted. Next, the ADF 50 will be described in detail. FIG. 2 shows a schematic configuration of the ADF 50. This AD
F50 generally includes a document tray 51, a pickup roller 54, a register roller 58, a transport belt 60,
It comprises a discharge roller 65 and a paper discharge tray 69.
The ADF 50 is installed on the upper surface of the copying machine main body 1 so that the transport belt 60 is positioned on the platen glass 29, and a hinge fitting (not shown) provided on the back side for an operator to manually set a document. ), The platen glass 29 can be opened. The opening and closing of the ADF 50 is detected by a magnet sensor (not shown), and the operation of the ADF 50 becomes possible only after it is detected that the ADF 50 is correctly closed.

The document tray 51 includes a pair of side regulating plates 5.
2. A tip stopper 53 is provided. The document is placed on the tray 51 with the first page facing upward. The leading end stopper 53 swings downward during sheet feeding and retracts from the regulation position. The pickup roller 54 is attached to the tip of a lever 57 rotatable around a support shaft of the normal rotation separating roller 55 as a fulcrum, and moves down together with the lever 57 to press the upper surface of the document when feeding paper. A reverse separating roller 56 is elastically pressed against the forward separating roller 55 from below.
This pressing force can be switched in two stages by an electromagnetic solenoid SL (see FIGS. 3 and 4) in order to improve the document separation performance, and the configuration will be described in detail below.

The register roller 58 is provided with pinch rollers 59a and 59b on the upper and lower sides thereof, and once positions the leading end of the fed document at a nip portion with the pinch roller 59a.
Thereafter, the document is conveyed to the entrance of the platen glass 29 while turning over the document. The transport belt 60 is a platen glass 29
Driven roller 61 and driving roller 62 so as to cover the entire surface of
It is stretched endlessly between and. In order to bring the surface of the belt 60 into contact with the platen glass 29 at a constant pressure, a number of backup rollers 63 are rotatably installed inside the conveyor belt 60. This transport belt 60
Is normally rotated in the direction of arrow c, and the original is
The extremity is adjusted to the exposure reference point O, which is the boundary between the platen glass and the platen glass 29, and stopped. The document feed / transport / stop / discharge processing will be described in detail below.

As a method of stopping the original at the exposure reference point O, there are a scale mode and a pulse control mode. The scale mode is a mode in which the leading end of the scale 28 is made to protrude from the surface of the platen glass 29, and the leading end of the document conveyed by the carrying belt 60 is brought into contact with the scale 28 to forcibly stop. In the pulse control mode, the scale 28 is retracted below the surface of the platen glass 29, the transport amount of the document is counted based on the number of rotations of the drive motor, and the transport is performed so that the leading edge of the document reaches the exposure reference point O. In this mode, the rotation of the belt 60 is stopped.
The ADF 50 employs a pulse control mode.

The reversing / discharging roller 65 has pinch rollers 66a and 66b above and below the reversing / discharging roller 65. The reversing / discharging roller 65 further includes a switching claw 67 for switching a paper passing path for reversing the duplex document around the reversing / discharging roller 65. I have. That is, at the time of document reversal, the switching claw 67 is located away from the surface of the roller 65 as shown in FIG.
The document discharged from above is guided to the outer peripheral surface of the roller 65. The document is turned around the rollers 65 and returned to the platen glass 29 again. At this time, the transport belt 60 is driven to rotate in the direction opposite to the arrow c. On the other hand, when the document is discharged, the switching claw 67 has the tip of the reversing / discharging roller 65.
The document is discharged onto the tray 69 through the discharge roller 68 while being guided by the lower surface of the switching claw 67.

The ADF 50 is driven and controlled by various motors, clutches, and sensors shown in FIGS. That is, the pickup roller 54 is moved up and down by a cam (not shown) rotated by the pickup motor M1, and the lowered position is detected by the pickup sensor SE10 which is turned on and off by the notch of the cam. As shown in FIG. 15, the pickup roller 54 and the separating rollers 55 and 56 are driven to rotate by a sheet feeding motor M2, and the transport belt 60 is driven by a main motor M3 that can rotate forward and reverse. A one-way clutch OCL1 is provided between the sheet feeding motor M2 and the normal rotation separating roller 55.
And a torque limiter TL is interposed between the roller 56 and the reverse rotation separating roller 56. The reverse / discharge roller 65 and the discharge roller 68 are driven to rotate by a reverse / discharge motor M4. The register roller 58 is driven to rotate by the paper feed motor M2 when the document clutch is turned on when the electromagnetic clutch CL is turned on. When the document is conveyed by the transport belt 60, the register clutch 58 is turned off and driven to rotate by the main motor M3. A one-way clutch OCL2 is interposed between the main motor M3 and the register roller 58. The one-way clutch OCL2 rotates the register roller 58 only when the motor M3 rotates forward, and does not transmit the rotational force when the motor M3 rotates reversely. An electromagnetic brake BRK1 is mounted on the support shaft of the register roller 58, and an electromagnetic brake BRK2 is mounted on the support shaft of the drive roller 62 of the transport belt 60, to prevent unnecessary rotation of the register roller 58 and the transport belt 60. It has become.

Further, the motors M2 and M3 are provided with encoders E2 and E3 for generating rotation pulse signals in order to detect the number of rotations, and the pulse signals are input to the microcomputer CPU2. The pulse signal is used for detecting the document length and controlling the document stop position. The ADF 50 is provided with the following document detection sensor. The empty sensor SE11 is installed near the pickup roller 54 and detects the presence or absence of a document on the tray 51. The register sensor SE12 is provided immediately before the register roller 58, and detects a document sent from the tray 51. The width sensor SE13 is installed at a side portion substantially at the same position as the sensor SE12, and has a role of detecting the size of the document in the width direction. The timing sensor SE14 is installed at the entrance of the platen glass 29,
It serves as a reference for document transport control and has a role in detecting the length of the document. The discharge sensor SE15 detects a document discharged from the platen glass 29, and detects the document SE1.
Reference numeral 6 detects a document that has been inverted by the inversion / discharge roller 65.

Here, the separating mechanism will be described. As shown in FIG. 3, the document D is fed to the left. The rotation direction for conveying the document is x, and the rotation direction for pushing back the document is y. Pickup roller 54 is rotated at a peripheral speed v ₁ in the x direction. Forward separation roller 55 is x
It is rotated at a peripheral speed v ₁ in the direction. The reverse rotation separating roller 56 is driven to rotate in the y direction. Register roller 58
Is rotationally driven in the x direction at a peripheral speed v ₂ (v ₂ > v ₁ ), and the pinch roller 59a is accordingly driven to rotate in the x direction.

The frictional force between the original is μ ₀ , the frictional force between the paper and the normal separation roller 55 is μ ₁ , and the paper and the reverse separation roller 5 are
When the frictional force between 6 and mu _2, is set to _{μ 1> μ 2> μ 0} . Therefore, when the intervening plurality of documents between the rollers 55 and 56, the uppermost original is conveyed to the downstream side at a speed v ₁ by the rotation of the x-direction of the regular separating roller 55, 2
The original after the first sheet is pushed back to the upstream side by the rotation of the reverse separating roller 56 in the y direction.

As shown in FIG. 5, the normal separation roller 55
Is attached to shaft 71 via a holder 72, it is rotated at a peripheral speed v ₁ in the x direction by the feed motor M2. A one-way clutch OCL1 is interposed between the roller 55 and the motor M2. When the document is conveyed at high speed v ₂ by the register rollers 58, the one-way clutch OCL1 permits that regular separating roller 55 is driven to rotate at a speed V ₂ in accordance with the conveyance of the document.

The reverse separating roller 56 is provided with a holder 74.
, And the holder 74 is attached to the support shaft 73 so as to be rotatable in both the x and y directions. A drive holder 75 is fixed to the support shaft 73 by a screw 76 adjacent to the holder 74. The boss portions 74a of the holders 74 and 75,
A coil spring that functions as a torque limiter TL is wound around 75a in a crimped state. One end of the torque limiter TL is locked by the drive holder 75, and when the holder 75 rotates together with the support shaft 73 in the y direction, the torque limiter TL
Is wound in the direction of tightening the boss 74a of the holder 74. The reverse separation roller 56 is rotationally driven in the y direction by the torque Ts at this time. By the way, when the reverse rotation separating roller 56 is in direct contact with the normal rotation separating roller 55 or contacts through one document and receives a force in the x direction at the speed v ₁ or v ₂ , the torque received at this time is torque If the torque Ts of the limiter TL is set to be larger, the reverse rotation separating roller 56 is driven to rotate in the x direction.
However, when the second and third originals enter between rollers 55 and 56, the torque received by reverse separating roller 56 is T
s, the roller 56 switches to the rotation in the y direction, separates the second and third documents, and pushes them back to the upstream side.

Next, the pressing force between the separating rollers 55 and 56 and the function of applying the pressing force will be described. In the present embodiment, pressure contact force N ₂ when the document is against contact pressure N ₁ when it is conveyed at a speed v ₁ by regular separating roller 55, the document is conveyed at a speed v ₂ by the register rollers 58 Is set small. This is so as not to lower the velocity v ₂ o'clock separation performance as described in detail below.

FIG. 3 shows a state of N _{1 with} a large pressing force, and FIG. 4 shows a state of N _{2 with} a small pressing force. Specifically, the reverse separating roller 56 is supported by the support plate 81 and the support plate 8
The one base is integrally connected to a lever 83 via a rotatable support shaft 82. A coil spring 84 is fixed to the upper end of the lever 83, and urges the lever 83 counterclockwise with a spring force Pa. On the other hand, an adjustment lever 85 is rotatably attached to the support shaft 82. Adjustment lever 85
The lower end is locked to the plunger 87 of the electromagnetic solenoid SL, the upper end is close to the side of the lever 83, and the coil spring 86 is fixed thereto. The coil spring 86 urges the adjustment lever 85 clockwise with the spring force Pb.

In such a configuration, when the electromagnetic solenoid SL is turned on (see FIG. 3), the plunger 87 is retracted, and the adjusting lever 85 pushes the spring force P of the coil spring 86.
b rotates slightly counterclockwise around the support shaft 82 as a fulcrum. At that time, the upper end projection 85a of the adjustment lever 85
Is located away from the side of the lever 83, and the lever 83 receives the spring force Pa of the coil spring 84, and based on the spring force Pa, the reverse rotation separating roller 56 is moved by a force of N ₁ with respect to the normal rotation separating roller 55. Crimp. On the other hand, the electromagnetic solenoid SL
Is in the off state (see FIG. 4), the plunger 87 projects, and the adjustment lever 85 applies the spring force Pb of the coil spring 86.
With the support shaft 82 as a fulcrum, it rotates clockwise. The spring force Pb is set to be larger than Pa, and the upper end protrusion 85a of the adjustment lever 85 presses the side of the lever 83, and the lever 83 is pressed by the spring force of Pc (Pb−Pa).
Is slightly rotated clockwise. Lever 83
The clockwise direction of rotation becomes possible to weaken the pressing force against the regular separating roller 55 of the reverse separating roller 56, the pressure contact force N ₂ at this time is smaller than the pressing force N ₁ when the electromagnetic solenoid SL is turned on .

Here, the document feeding operation will be described.
When the document D is placed on the tray 51 and a copy start signal is issued, the pickup roller 54 descends and presses the document D. Next, the paper feed motor M2 is turned on, the pickup roller 54 and the normal rotation separation roller 55 are driven to rotate in the x direction, and the reverse rotation separation roller 56 is driven to rotate in the y direction. At the same time, the electromagnetic solenoid SL is turned on,
The adjustment lever 85 releases the restriction on the lever 83, and the lever 83 receives the spring force Pa by the coil spring 84, so that the reverse separation roller 56 is rotated forward by the forward rotation roller 5.
Pressed against a pressure of N ₁ against 5.

The reverse separating roller 56 includes rollers 55, 5
When it is not fed document between 6, x at a peripheral speed v ₁
Since the driving force received from the normal rotation separating roller 55 rotating in the direction is larger than the torque Ts of the torque limiter TL, the rotation is driven in the x direction. When one document is fed between the rollers 55 and 56 by the pickup roller 54, the document is moved by the forward separation roller 55 at a speed v _1.
Is transported downstream. At this time, the reverse rotation separating roller 5
Numeral 6 receives a driving force in the x direction via one document, and the driving force at this time is larger than the torque Ts of the torque limiter TL, and the driven rotation in the x direction is maintained. However, when the second and third originals are fed between the rollers 55 and 56, the driving force in the x direction received by the reverse separating roller 56 via the plurality of originals becomes smaller than the torque Ts. The reverse separating roller 56 is immediately switched to the rotation in the y direction. By this rotation, the second and third originals are pushed back to the upstream side, and only the uppermost (first) original is reliably separated and sent to the nip portion between the register roller 58 and the pinch roller 59a. To go.

At this time, the register roller 58 is locked when the electromagnetic clutch CL is turned off, the driving force from the sheet feeding motor M2 is not transmitted, and the electromagnetic brake BRK1 is turned on. The leading edge of the separated document is the register roller 58 and the pinch roller 5.
9a, and a loop is formed at the tip portion (see FIG. 4). The leading edge of the document is a register sensor SE
The paper feed motor M2 is once turned off for a predetermined time counted by the timer T102 after the detection at 12. Timer T
Reference numeral 102 is set to be slightly longer than the time during which the document is conveyed at the speed v ₁ from the detection point of the sensor SE12 to the nip between the rollers 58 and 59a (see FIG. 3)
Within this time, the leading end of the document forms a loop, and the skew is corrected.

Next, the electromagnetic brake BRK1 for the register roller 58 is turned off, and the sheet feeding motor M2 is turned on. As a result, the register roller 58 has a peripheral speed v
_{At 2} (a value larger than v ₁ ), the pickup roller 54 and the separation rollers 55 and 56 are again driven to rotate in the x direction. At this time, the electromagnetic solenoid SL is turned off at the same time when the sheet feeding motor M2 is turned on, and the lever 83 is regulated by the adjustment lever 85.
Pressing force is weakened in N ₂ for regular separating roller 55 of 6 (see FIG. 4).

In this state, the first document D ₁ registered at the nip portion between the rollers 58 and 59 a is conveyed at a speed v ₂ by the rotation of the register roller 58. At this time, the pickup roller 54 moves upward to release the pressing on the document. The normal rotation separating roller 55 is the original D ₁
The driving force in the x direction faster rate v ₂ than its velocity v ₁ is applied from by the action of the one-way clutch OCL1, rotationally driven in the x direction at a speed v _2. Reverse separating roller 56 is also applying a driving force in the x direction of the velocity v ₂ from the document D _1. Depending on the relationship between the driving force at this time and the torque Ts of the torque limiter TL, the reverse separating roller 56 is driven to rotate in the x direction, stops, or reverses in the y direction.

However, since the pressing force N ₂ is set to be smaller than N ₁ , the driving force received from the document D ₁ is not so large. Therefore, even if the second original D ₂ is brought into the original D ₁ it has been entered into between the rollers 55 and 56,
2nd driving force received from the document D ₂ of less than torque Ts, reverse separating roller 56 is switched to immediately reverse the y direction as has been rotated in the x-direction, pushing back the original D ₂ to the upstream side . Even if the document D ₁ is being conveyed at the speed v ₂ , if a large pressing force N ₁ is acting, the switching of the reverse rotation separating roller 56 to the reverse rotation is delayed, and the document D 1 is delayed during this response delay. There is a possibility that the leading end portion of No. ₂ may pass between the rollers 55 and 56 (decrease in separation performance). Further, the third original D ₃ is provided with rollers 55 and 5.
6, the reverse separating roller 56 is moved to the original D
₃ is the second original D ₂ is further conveyed between the being pushed back, the original D ₂ is that would be conveyed downstream in the register rollers 58 with the first document D _1. The above is one example in which dragging occurs. Such a dragging,
Due to the demand for speeding up document conveyance, register rollers 5
Conveying speed v ₂ by 8 is remarkable when it is set faster than the conveying speed v ₁ by regular separating roller 55. In the present embodiment, by weakening the pressing force from N ₁ to N _2,
The separation performance of the reverse separating roller 56 is prevented from lowering.

In this embodiment, when the transport of the separated document is resumed by the register roller 58, the roller 55, 56 is driven simultaneously with the driving of the register roller 58.
Also drive. When the separating rollers 55 and 56 during transport restart is stopped, a loop formed at the distal end portion of the document is once eliminated by the conveying force of the speed v _2, or large loop eliminates noise occurs, the image surface of the document May cause damage. However, by driving the separating rollers 55 and 56 at the same time as the driving of the register roller 58, not only the entrainment can be prevented, but also the loop is loosened gently, and the sound for eliminating the loop and the damage to the document are almost eliminated. The time during which the separating rollers 55 and 56 are rotated after the restart of the conveyance may be set to at least a time at which the loop at the leading end of the document is eliminated. However, in consideration of the dragging prevention function, it is desirable to set the time longer than the loop elimination time.

Next, the relationship between the pressing force of the separating rollers 55 and 56 and the torque of the torque limiter TL will be described in detail. As shown in FIG. 6, the frictional force between the paper is μ ₀ , the frictional force between the paper and the normal separation roller 55 is μ ₁ , the frictional force between the paper and the reverse separation roller 56 is μ ₂ , and the frictional force between the rollers 55 and 56 is The frictional force is μ ₃ , and the pressure contact force between the rollers 55 and 56 is N
(G), the torque of the torque limiter TL is expressed as Ts (g−c
m), the radius of the forward rotation roller 55 is R ₁ (cm), and the radius of the reverse rotation roller 56 is R ₂ (cm).

The forces acting on the reverse separating roller 56 are as follows. Fa: the reverse rotation forced driving force from the support shaft 73 Fb: the normal rotation driving force from the normal rotation separating roller 55 The normal rotation driving force Fb is expressed by (A), (B), and (C) in FIG. A) Fb ₁ : When no paper is interposed between rollers (B) Fb ₂ : When one sheet is interposed between rollers (C) Fb ₃ : When two or more sheets are interposed between rollers The forward drive force Fb changes depending on the above three conditions and the type of paper. On the other hand, the reverse rotation forced driving force Fa is always constant if the reverse rotation torque Ts is constant.

Therefore, the following equation is established. (A) Fb ₁ = μ ₃ N (1) (B) Fb ₂ = μ ₂ N (2) (C) Fb ₃ = μ ₀ N (3) From the forward separating roller 55 to the reverse separating roller 56 The applied forward rotation torque Tf (g-cm) is as follows: (A) Tf ₁ = Fb ₁ R ₂ = μ ₃ NR ₂ (4) (B) Tf ₂ = Fb ₂ R ₂ = μ ₂ NR ₂ ( 5) (C) Tf ₃ = Fb ₃ R ₂ = μ ₀ NR ₂ (6) On the other hand, the reverse rotation torque Ts is constant in any of (A), (B) and (C).

Ts: const (7) That is, the reverse rotation separating roller 56 rotates reversely when Ts> Tf, and rotates forward when Ts <Tf. However, in practice, the inertia torque Tα and the friction loss Tβ of the reverse rotation separating roller 56 are generated, so that the roller 56 has the following relationship: Ts> Tf + Tα + Tβ: reverse rotation Ts <Tf + Tα + Tβ: normal rotation. Although the friction loss Tβ is almost constant, the inertia torque Tα is proportional to the paper transport speed v.

Here, conditions for reliably separating paper and providing a sufficient conveying force will be considered. (A) When no paper is interposed When no paper is interposed, as shown in FIG. 6A, the rollers 55 and 56 come into direct contact with each other, and at this time, the reverse separating roller 56 needs to rotate forward. Is given by the following equation (8)
Is represented by

Μ ₃ N> Ts / R ₂ (8) At this time, if the reverse rotation separating roller 56 rotates in the reverse direction, the frictional force between the rollers 55 and 56 increases, and the life is shortened. Further, when the sheet enters between the rollers 55 and 56, there is a possibility that the sheet is caught by the reverse rotation separating roller 56. Therefore, it is required to satisfy Expression (8). (B) When one sheet is interposed As shown in FIG. 6B, when one sheet is interposed between the rollers 55 and 56, the reverse separating roller 56 can be rotated forward or backward. Often, the conditions are as follows. (B ₁₎ reverse separating rollers reverse rotation Ts> Tf + Tα + Tβ ∴Ts / R 2> μ 2 N + Tα + Tβ In these conditions, the conveying force Ff acting on the sheet D ₁ shown in FIG. _{7, Ff = μ 1 N ... (} 9 The separation force Fr acting on the sheet D ₁ is: Fr = μ ₂ N (10) Accordingly, the condition for reliably conveying the sheet D ₁ based on the equations (9) and (10) is given by the following equation (11). Is represented. In addition,
Fmin is the minimum required conveying force.

[0042] F = Ff-Fr = (μ 1 -μ 2) N> Fmin ... (11) (B 2) reverse separating roller forward at Ts <Tf + Tα + Tβ ∴Ts / R 2 <μ 2 N + Tα + Tβ such conditions In FIG. 8, the transport force Ff acting on the sheet D ₁ is: Ff = μ ₁ N (9) The separating force Fr acting on the sheet D ₁ is: Fr = Ts / R ₂ (12) Therefore, the equation (9) ), conditions for conveying the sheet D ₁ reliably based on (12) is represented by the following equation (13).

F = Ff−Fr = μ ₁ N−Ts / R ₂ > Fmin (13) (C) When Two Sheets Intervene As shown in FIG. 6C, between the rollers 55 and 56 When two sheets are interposed, the reverse rotation separating roller 56 needs to be reversely rotated or stopped, and the conditions are as follows.

According to the above equation (6), the forward rotation torque Tf ₃ applied from the reverse rotation separation roller 56 to the forward rotation separation roller 55 is μ ₀ NR ₂ . Therefore, the conveying force Ff acting on the first sheet D ₁ shown in FIG. _{9, Ff = μ 1 N-μ} 0 N ... (14) 2 sheet separation force Fr acting on the sheet D ₂ of, (C ₁ ) Reverse rotation roller reverse rotation Fr = μ ₂ N−μ ₀ N (15) (C ₂ ) Reverse rotation roller stops Fr = Ts / R ₂ −μ ₀ N (16) From the above equation (14), Ff = Μ ₁ N−μ ₀ N> Fmin ∴N> Fmin / (μ ₁ −μ ₀ ) (17) where μ ₁ −μ ₀ > 0 From the above equation (15), Fr = μ ₂ N−μ ₀ N>Frmin∴N> Frmin / (μ ₁ −μ ₀ ) (18) where μ ₁ −μ ₀ > 0 From the above equation (16), Ts / R ₂ −μ ₀ N> 0 ΔN <Ts / R ₂ μ ₀ (19) Here, the conditions for reliably separating and transporting the paper are summarized, and the pressing force N may satisfy the following expression.

N> Ts / R ₂ μ ₃ (8 ′) N> Fmin / (μ ₁ −μ ₂ ) ... (11 ′) N> (Fmin + Ts / R ₂ ) / μ ₁ (13 ′) N> Fmin / (μ ₁ −μ ₀ ) (17) N> Frmin / (μ ₂ −μ ₀ ) (18) N> Ts / R ₂ μ ₀ (19) Here, a graph of the relationship between the pressing force N and the torque Ts is as shown in FIG. Pressing force N and torque Ts
Are set in the hatched area in FIG.
No misfeeding or misfeeding occurs. In this embodiment, the following numerical values are set.

Μ ₀ : 0.5 μ ₁ : 2.0 μ ₂ : 1.0 μ ₃ : 5.0 R ₁ , R ₂ : 1.0 cm Fmin: 150 g Frmin: 100 g By the way, in such a separating mechanism, As described above, the torque Ts of the torque limiter TL decreases due to the inertia torque Tα of the reverse rotation separating roller 56 and the friction loss Tβ. In particular, the inertia torque Tα depends on the transport speed.
Tα at the transport speed v ₁ by the forward rotation separating roller 55 is T
α ₁ , Tα at the time of conveyance speed v ₂ by the register roller 58
When the the T [alpha _2, the formula (8 '), (13'), (1
9) can be rewritten as follows.

N> (Ts−Tα−Tβ) / R ₂ μ ₃ (8 ″) N> {Fmin + (Ts−Tα−Tβ) / R ₂ } / μ ₁ (13 ″) N> (Ts− Tα−Tβ) / R ₂ μ ₀ (19 ′) In the present embodiment, Tα _{1 is} 150 g-cm, Tα _{2 is} 50 g-cm, and Tβ is 50 g-cm.
When the graph in FIG. 11 is modified, the graph shown in FIG. 11 is obtained. In the graph of FIG. 11, the diagonal hatching represents the proper region o'clock conveying speed v _1, vertical hatching indicates the proper region o'clock conveying speed v _2.

In the embodiment, in order to reduce the stress on the original as much as possible at the time of conveyance / separation (conveyance speed v ₁ ),
Sets the torque Ts to 400 g-cm, have set the pressing force N ₁ to 450 g. Also, during transport after the resist the pressure contact force N ₂ of (conveying speed v ₂₎ is set to 250 g. In other words, when the document conveying speed between the rollers 55 and 56 increases and the trailing feed is likely to occur, the rollers 5
The pressure contact force between 5, 56 is reduced to prevent a decrease in separation performance.

Next, the document feeding / transporting / discharging processing by the ADF 50 will be described in detail. The original is placed on the tray 51 with the first page facing upward, and the sides are
2 and the tip is regulated by the stopper 53.
The document is detected by the empty sensor SE11, and a copy process (document feeding operation) is enabled. When the print key is turned on by the operator, the pickup motor M1 is turned on for a predetermined time, and the pickup roller 54 is turned on.
There was lowered onto the original D _1, and the stopper 53 is retracted FIG 12 (a) Reference. At the same time, the electromagnetic solenoid SL is turned on, and the reverse rotation roller 56 is rotated to the normal rotation roller 5.
5 with a first pressing force N ₁ .

After a certain time, the paper feed motor M2 is turned on,
As the rollers 54, 55, 56 are driven to rotate,
First original D ₁ is separated into one roller 55, 56
It is sent out from between, and its tip comes into contact with the nip between the register roller 58 and the pinch roller 59a. Document transportation speed at this time is v _1. When the leading edge of the document D ₁ is detected by the register sensor SE12, the electromagnetic brake BRK1 is turned on, to lock the register roller 58. This register roller 58 by abutment of the leading end of the original D ₁ is to prevent the driven rotation.

[0051] The predetermined time after the detection of the leading end of the original by the sensor SE12, the tip end of the original D ₁ forms a slight loop immediately before the register roller 58 FIG 12 (b)
Reference], and the sheet feeding motor M2 is turned off. This in skew of the document D ₁ is corrected. Also, the pickup motor M
1 is turned on for a predetermined time, and the pickup roller 54 is raised. At the same time, the electromagnetic solenoid SL is turned off, reducing the contact pressure between the rollers 55 and 56 to N _2.

Next, the electromagnetic clutch CL is turned on, the electromagnetic brake BRK1 is turned off, and the sheet feeding motor M2 is turned on. This in document D ₁ is started the conveyance at a speed v ₂ by the register rollers 58, and is also rotated separating rollers 55 and 56 at the same time. Separating rollers 55, 5
As described above, the rotation of No. 6 eliminates the occurrence of the loop elimination sound and the damage to the document. It is also as previously described that prevent deterioration of the separation performance for the next document D _2, D ₃ by pressing force between the time rollers 55 and 56 is reduced to N _2.

Simultaneously with the turning on of the sheet feeding motor M2, the counting of the number of rotation pulses of the motor M2 issued from the encoder E2 is started.
1 is turned on, and the register roller 58 is stopped. Thereafter, the electromagnetic brake BRK1 and the electromagnetic clutch CL are turned off. At this, it becomes possible to first sheet of first-out feeding of the document D ₁ is completed [see FIG. 12 (c)], the document D ₁ has a tip at the inlet portion of the platen glass 29, details of the timing sensor SE14 It stands by immediately before (the first reference point P).

[0054] When the above first-out feeding for the original D ₁ as is completed, then the main motor M3 rotates forward on.
At this time, the electromagnetic clutch CL is off, and the register roller 58 is rotationally driven together with the transport belt 60,
Original D ₁ is carried onto the platen glass 29 [Fig. 12
(D)]. During this loading, the timing sensor SE1
4 detects the leading end of the original D ₁ and at the same time, the encoder E
3 starts counting the number of rotation pulses of the main motor M3. The sensor SE14 the document D ₁
Upon detection of the trailing end, the pickup motor M1 is turned on a predetermined time, to press the document D ₂ pickup roller 54 is lowered for the next feed process, waits.

In this embodiment, when a document is carried onto the platen glass 29 from the advance feeding position, the register roller 58 and the transport belt 60 are rotated by the main motor M3. This is because, when both are driven by different motors, it is difficult to synchronize the drive start timing and the document conveyance speed of both, and special control is required for synchronization. If the two driving sources are the same, the difficulty of such synchronization is eliminated.

The number of pulses from the encoder E2 counted during the advance feeding of the original and the timing sensor S
The length of the document in the transport direction is detected by the sum of the number of pulses from encoder E3 counted until E14 is turned off (document trailing edge detection). Further, the width of the document is detected by turning on and off the width sensor SE13, and the size of the document is determined by both of them. The platen glass 29 has an area corresponding to the A3 size. Therefore, when the one-sided original is set on the tray 51 and the length of the original is 216 mm or less, the original is stopped when its leading end reaches the intermediate reference point O ′ (see FIG. 12D),
The pre-step mode described below is executed. on the other hand,
If the length of the original exceeds 216 mm, the original is conveyed until its leading end reaches the exposure reference point O, and the normal single-sided normal mode is executed.

In the pre-step mode, to stop the original at the pre-step position, the main motor M3 is turned off and the electromagnetic brake BRK2 is turned on when the n3 pulses from the encoder E3 are counted, so that the conveyance belt is stopped. Stop 60. Thus, the transport belt 60
Stopping the rotation, the leading edge of the original D ₁ is designed to reach the intermediate reference point O '.

Next, the second original D ₂ on the tray 51 to the first-out feeding position-feed [FIG 13 (e) Reference. First-out feeding process is basically the same as described above, the document D ₂
Is turned on after the paper feed motor M2 is turned on
When one pulse is counted, the sheet feeding motor M2 is turned off. This in, the next document D ₂ stops in first-out feeding position.

Next, conveys a document D ₁ from the pre-step position to the exposure position where the front end is positioned in the exposure reference point O.
First, the main motor M3 is turned on. With this, original D
_1, the transport of D ₂ is resumed, at the same time starts counting the number of pulses from the encoder E3 and on the motor M3. In this embodiment, the leading end of the document reaches the exposure reference point O from the intermediate reference point O 'when the pulse from the encoder E3 is counted by n5 after the main motor M3 is turned on. Therefore, when the pulse from the encoder E3 has counted n5 pulses, the main motor M3 is turned off, the electromagnetic brake BRK2 is turned on, and the transport belt 60 is stopped. This in document D ₁ is the leading end is stopped at the exposure position located in the exposure reference point O. 2
Sheet document D ₂ stops to reach its tip to the intermediate reference point O '[FIG. 13 (f) Reference.

On the other hand, at the same time as the conveyance of the originals D ₁ and D ₂ is started (the main motor M3 is turned on), the pickup motor M1 is turned on to start lowering the pickup roller 54 from the upper home position. It is pressed against the _third original D3. As described above, the pressing of the _second original D2 is started after the trailing end of the _first original D1 is detected by the register sensor SE12.
By the way, at the time of advance feeding of the _third original D3, the size of the _first original D1 has already been detected, and
m. Then, the document D ₂ of the second sheet is also considered to be the same size. In the ADF 50, if the document length is 216 mm or less, even if the pickup roller 54 starts lowering at the same time as the main motor M3 is turned on, the document is 216 mm or less before the pickup roller 54 is completely lowered. Even if the rear end does not pass through the detection point of the register sensor SE12, it is designed to pass through the pressing point of the pickup roller 54. The lowering of the pickup roller 54 is started early, and at the same time, the sheet feeding motor M2 is turned on to turn on the rollers 54,5.
If the rollers 5 and 56 are driven to rotate, the document feeding process can be started earlier. In this case, the pickup roller 54 presses the rear end of the document D _2, have never cause trouble in feeding of the original D ₃ is a matter of course. Note that the timing at which the lowering of the pickup roller 54 is started is not at the same time as the start of transport of the originals D ₁ and D ₂ , but is later than the timing of detecting the trailing end of the original D ₂ by the register sensor SE12 which has been conventionally performed. If it is performed earlier, the document feeding process is earlier.

In the ADF 50, pulses from the encoder E3 are counted by n5 pulses, and the original D ₁ is counted.
The tip of reaches the exposure reference point O, the leading end of the original D ₂ reaches the intermediate reference point O ', at the time when the main motor M3 is turned on, third original D ₃ is the tip is still registers The nip portion between the roller 58 and the pinch roller 59a has not been reached, but has reached the nip portion with a slight delay,
Wait for a while [see FIG. 13 (f)]. Here, image exposure is performed on the _first document D1 by the optical system 20. During this image exposure, the feed motor M2 is turned on to feed the _third original D3 in advance (see FIG. 13 (g)).
This advance feeding process is completed by the end of image exposure on the _first document D1. When performing one-sided copying on a one-sided original using the ADF with one copy, the copier body 1 This is an essential condition so as not to lower the copy speed. In order to achieve this condition, it is necessary to increase the paper feed speed or to advance the paper feed start timing. However, if the paper feeding speed is increased, the damage to the original document is increased, skew occurs, and the separation performance by the reverse rotation separating roller 56 is reduced. Therefore, in the present embodiment, the timing of lowering the pickup roller 54 is set earlier than the normal timing (the timing at which the trailing end of the preceding document is detected by the register sensor SE12) for the third and subsequent documents. The conditions have been achieved.

Next, the main motor M3 and the discharge motor M
Turn on 4. At this, the first document D ₁ tray 6
Is discharged onto the 9, second original D ₂ is transported to the exposure position, third original D ₃ is conveyed to the pre-step position [Figure 13 (h) Reference. Specifically, the counting of the number of pulses from the encoder E3 is started simultaneously with the turning on of the main motor M3, and when the n5 pulses are counted, the main motor M3 is turned off, the electromagnetic brake BRK2 is turned on, and the transport belt 60 is stopped. .

[0063] On the other hand, at the same time as on of the main motor M3 in this case, the same manner, by pressing the 4-sheet document D ₄ by the pickup roller 54, and turns on the sheet feed motor M2,
Its tip a document D ₄ once wait for the nip between the register roller 58 and the pinch roller 59a [13
(H)]. At this time, image exposure is performed on the _second document D2, and the sheet feeding motor M2 is turned on to feed the _fourth document D4 in advance (see FIG. 14 (i)). Also in this advance feeding process, the motor M2 is turned off when the n1 pulse is counted after turning on the feeding motor M2.

Hereinafter, the above-described operation is repeatedly executed.
With second original D ₂ is discharged onto the tray 69,
Third original D ₃ is transported to the exposure position, 4-sheet document D ₄ is conveyed to the pre-step position [Figure 14 (j) Reference. When the image exposure is completed for the original D _3, the document D ₃
Is discharged onto the tray 69 and the fourth document D ₄
Is transported / stopped to the exposure position [see FIG. 14 (k)].
Further, when the image exposure is completed for the original D _4, so that the document D ₄ is discharged onto the tray 69 [Figure 14
(L)].

On the other hand, if the length of the original exceeds 216 mm, the single-sided normal mode is executed. In this case, when the trailing end of the first document is detected by the register sensor SE12, the pickup roller 54 is lowered. After the leading edge of the first document is detected by the timing sensor SE14, the pulse from the encoder E3 of the main motor M3 changes to n.
When the count of 7 is completed, the motor M3 is turned off.
The electromagnetic brake BRK2 is turned on, and the transport belt 60 is stopped. As a result, the first document is conveyed / stopped to the exposure position where the leading end is located at the exposure reference point O. Where 1
The image of the second document is exposed, and the second document is fed in advance. That is, after a predetermined time from the stop of the main motor M3, the paper feed motor M2 is turned on to separate the second document from other documents, and the leading end of the document is placed in the nip between the register roller 58 and the pinch roller 59a. Make contact and correct skew. After that, the electromagnetic clutch CL is turned on, the paper feed motor M2 is turned on again, and the register roller 58 is rotated. As a result, the conveyance of the second document to the advance feeding position is started, and the motor M2 is turned off at the time when the pulse of the encoder E2, which starts counting simultaneously with the turning on of the feeding motor M2, is counted by n1, and The electromagnetic brake BRK1 is turned on, and the advance feeding process of the second document is completed.

When the image exposure for the first document is completed, the main motor M3 and the discharge motor M4 are turned on, the first document is discharged onto the tray 69, and the second document is advanced to the first sheet feeding position. To the exposure position. Thereafter, the above-described control is repeated until the final document is discharged onto the tray 69. In the pre-step mode, the description of the advance feeding of the originals D ₂ , D ₃ , and D ₄ is omitted.
Turn on / off the electromagnetic solenoid SL to separate the roller 5
Switching of the pressing forces N ₁ and N ₂ between the _first and _second documents 5 and 56 and driving of the separating rollers 55 and 56 during the conveyance of the document after registration are the same as the sheet feeding process for the _first document D ₁ . Further, such control is also performed in the sheet feeding process in the single-sided normal mode.

Next, the control of the ADF 50 will be described in detail. The control is performed by a CPU 1 for controlling the copying machine body 1.
(See FIG. 16) and a CPU for controlling the ADF 50
2 (see FIG. 17). The CPUs 1 and 2 exchange information at necessary timing. By the way, in the description of the control procedure, on-edge is a sensor,
A flag, a signal, or the like means that the state is switched from the off state to the on state, and an off edge means that these are switched from the on state to the off state.

FIG. 18 shows a CPU 1 for controlling the main body 1 of the copying machine.
The main routine of FIG. When the power is turned on and the CPU 1 is reset and the program starts, in step S1, the RAM is cleared, various registers are reset, and initial settings for setting various devices to the initial mode are performed. Subsequently, the internal timer is started in step S2. The internal timer determines the time required for one of the main routines, and its value is set in step S1. Further, this internal timer is a reference for counting of various timers appearing in each subroutine.

Next, the respective subroutines of steps S3 and S4 are sequentially called, necessary processing is performed, and the process returns to step S2 after waiting for the end of the internal timer in step S5. Step S3 is a subroutine for executing a copy process. Step S4 carries out other processing, for example, control of the toner fixing device 40, detection of a paper jam, and the like.

The CPU 1 is connected to the CPU 2 via a serial communication line, and its transmission and reception are performed in step S6 by interrupt processing. Next, a control procedure of the CPU 2 for controlling the ADF 50 will be described. Before that, a counter, a pulse, and a timer used in the control there will be described. Counter PCNTM2: Encoder E of paper feed motor M2
It is incremented by one pulse output from 2.

Counter PCNTM3a: Main motor M
3 is incremented by one pulse output from the encoder E3. Counter PCNTM3b: Similarly, is incremented by one pulse output from the encoder E3 of the main motor M3. Counter PSIZE: stores the number of pulses corresponding to the length of the document.

Counter LST: The number of documents located inside the ADF 50 is displayed. "0" indicates that the document is at the advance feeding position, pre-step position, and exposure position, and "1" indicates that the document is at the pre-step position and exposure position (that is, the last two sheets). Is displayed, and when the value is "2", it is displayed that the document is only at the exposure position (that is, the last sheet).

Pulse n1: feeding motor M during advance feeding
Number of pulses from turning on 2 to turning off. Pulse n3: The first document is the timing sensor SE14
The number of pulses from the detection in step (1) until the main motor M3 is turned off to stop at the pre-step position. Pulse n5: the number of pulses from turning on the main motor M3 to turning it off in order to convey the document from the pre-step position to the exposure position.

Pulse n7: the number of pulses from when the original is detected by the timing sensor SE14 to when the main motor M3 is turned off to stop at the exposure position in the single-sided normal mode. Pulse nL: the number of pulses when the length of the document corresponds to 216 mm. It is used to determine whether to execute the pre-step mode by comparing the number of pulses stored in the counter PSIZE.

Timer T102: Set to the time from when the leading edge of the document sent out from the tray 51 is detected by the register sensor SE12 to when it comes into contact with the nip portion between the register roller 58 and the pinch roller 59a and the skew is corrected. Have been. Timer T103: Set to the time from when the paper feed motor M2 is turned off until it stops.

Timer T201 is set to the time from when the electromagnetic brake BRK2 is turned on to when the transport belt 60 stops. Timer T301: Set to the time to delay the start of document ejection. Timer T302 is set to the time from when the trailing end of the document is detected by the discharge sensor SE15 to when the document is discharged onto the tray 69.

Timer T303: Set to the time from when the discharge motor M4 turns off until it stops. FIG. 19 shows a main routine of the CPU 2 for controlling the ADF 50. When the power is turned on and the CPU 2 is reset and the program is started, in step S11, the RAM is cleared, various registers are reset, and initial settings for setting various devices to the initial mode are performed. Subsequently, the internal timer is started in step S12. The internal timer determines the time required for one of the main routines, and its value is set in step S11. Also,
This internal timer is also a reference for counting of various timers appearing in a subroutine described below.

Next, the subroutines of steps S13 to S15 are sequentially called to perform necessary processing.
At 16, the process returns to step S12 after the end of the internal timer. Step S13 is a subroutine for exchanging the original on the platen glass 29. Step S14 is a subroutine for counting various timers. Step S15 performs other processing, that is, A / D conversion, input processing, output processing, paper jam detection, and the like.

The interrupt processing for the CPU 2 includes various interrupt processing such as controlling the main motor M3 in step S17, and data transmission processing and data reception processing with the CPU 1 in steps S21 and S22 shown in FIG. Is performed as appropriate regardless of the processing of. FIG. 21 shows an initialization subroutine executed in step S11.

In step S31, each data in the RAM is
Clear each counter. In step S32, the timer T
101, T103, T201, T301, T302, T
Reset 303. In step S33, each flag described below is reset. In step S34, the motors M1, M2, M3, and M4, the electromagnetic solenoid SL, the electromagnetic clutch CL, and the electromagnetic brakes BRK1 and BRK2 are turned off. In step S35, the internal timer is set to a predetermined value. In step S36, the paper feed status K is set to "1". In step S37, other initial settings are processed.

FIG. 22 shows a document exchange subroutine executed in step S13. In this subroutine, MODE is checked in step S40, and the following processing is performed based on the value. MODE is initially reset to "0". At this time, a start check is processed in step S41. In the subroutine of step S41, MODE is set to a predetermined value according to the document conveyance mode selected by the operator. (See FIG. 23, steps S68, S69, S70).

When MODE is "1", the mode is a one-sided document transport mode, and in step S42, the paper is transported from the tray 51 to the advance feeding position. Subsequently, in step S43, pre-step feeding for transporting the one-sided document to the pre-step position and the exposure position, or single-sided normal feeding for transporting the one-sided document directly to the exposure position is performed. Further, in step S44, a process of discharging the document from the exposure position to the tray 69 is performed.

When MODE is "2", the mode is a double-sided document transport mode, in which sheet feeding is performed in step S45, and setting of the double-sided document to the exposure position is performed in step S46.
In step S47, the sheet is discharged. Details of these processes are omitted. When MODE is "3", it is a 2-in-1 mode. 2-in-1 mode means that two originals are
This is a copy mode in which two original images are formed on a single copy sheet by arranging them successively on the platen glass 29 as a set. Here, sheet feeding is performed in step S48, setting of two documents on the platen glass 29 is performed in step S49, and sheet discharging is performed in step S50. Details of these processes are omitted.

FIG. 23 shows a start check subroutine executed in step S41. This subroutine is processed when MODE is "0", that is, when the ADF 50 is in a standby state. First, in step S61, it is determined whether or not the empty sensor SE11 is on. If it is not turned on, the document has not yet been set on the tray 51, and this subroutine is immediately terminated.
When the sensor SE11 is turned on (when a document is set on the tray 51), it is determined in a step S62 whether or not the flag DCHG is "1". The flag DCHG is a command for requesting the exchange of a document when it is “1”.
Sent from This flag DCHG is set to “1” when the print key is turned on and the image scanning for the number of copies is completed.
Is set to Therefore, if the flag DCHG is "1", the flag DCHG is reset to "0" in step S63, and the sheet feeding status K is set to "3" in step S64.
And return. The status K is used in the paper feeding subroutine, and the paper feeding process is started when it is set to “3”.

On the other hand, when the sensor SE11 is on and the flag D
If CHG is “0”, it is determined in step S65 whether or not the status K is “2”, and in step S66, whether or not the status K is “20”. If the status K is “2”, that is, if the return of the pickup roller 54 to the home position has been completed, as described below,
If the value is other than "20", the subroutine is terminated. If the status K is "20", that is, as described below, after the first original has been fed in advance, the original mode is checked in step S67.
If in the single-sided mode, MODE is set to "1" in step S68.
And if the mode is the duplex mode, the MO is set in step S69.
DE is set to "2", and if it is a 2-in-1 mode, MODE is set to "3" in step S70. continue,
In step S71, the set status S used when the original is set on the platen glass 29 is set to "1", and this subroutine ends.

FIGS. 24 to 27 show a sheet feeding subroutine executed in step S42. In this subroutine, the paper feed status K is checked in step S80, and the following processing is performed based on the values "0" to "8" and "20". The status K is initially reset to "0", and no processing is performed at this time.

If the status K is "1" (see step S36 of the initial setting), the pickup roller 54 is returned to the upper home position. First, step S
At 81, the pickup motor M1 is turned on, and step S8
2 turns off the electromagnetic solenoid SL. When the off-edge of the pickup sensor SE10 is confirmed in step S83, the motor M1 is turned off in step S84 assuming that the pickup roller 54 has returned to the home position, and the status K is set to "2" in step S85. When the status K is "2", nothing is processed,
stand by.

When the status K is "3" (see step S64 for start check, steps S215, S230, and S336 for single-sided document setting), document feeding is started. First, in step S91, the pickup motor M1 is turned on. Here, when the pickup roller 54 descends and the on-edge of the sensor SE10 is confirmed in step S92, the motor M1 is turned off in step S93 because the pickup roller 54 has descended to a predetermined position.
In step S94, the paper feed motor M2 is turned on, and
At 95, the electromagnetic solenoid SL is turned on. This at first contact pressure N ₁ acts between separating rollers 55 and 56.
At the same time, the pickup roller 54, the judgment roller 55,
The document 56 is rotated from the tray 51 to be sent out from the tray 51, separated into one sheet of the uppermost layer, and directed to the register roller 58.
The document conveying speed at this time is the first speed V ₁ , and the document is separated by an appropriate pressing force N ₁ between the separating rollers 55 and 56. Further, the status K is set to "4" in step S96.

If the status K is "4", it is determined in step S101 whether or not the register sensor SE12 is on-edge.
If detected at E12), the timer T
102 and set the electromagnetic brake B in step S103.
Turn on RK1. Thus, the register roller 58 is locked. Subsequently, the status K is set to “5” in step S104.

If the status K is "5", the process waits for the end of the timer T102 in step S111, and then proceeds to step S111.
At 112, the sheet feeding motor M2 is turned off. Here, the leading end of the document comes into contact with the nip portion between the register roller 58 and the pinch roller 59a to form a predetermined amount of loop, and skew is corrected. Subsequently, the timer T103 is set in step S113, and the status K is set to "6" in step S104.

If the status K is "6", the process waits for the end of the timer T103 in step S121, and then proceeds to step S1.
At 22, the electromagnetic clutch CL is turned on, and at step S123, the electromagnetic brake BRK1 is turned off. Thus, the register roller 58 can be driven to rotate by the sheet feeding motor M2. Subsequently, at step S124, the counter PCNTM2
Is reset to "0", the electromagnetic solenoid SL is turned off in step S125, and the sheet feeding motor M2 is turned on in step S126.
Is turned on, and in step S127, the pickup motor M1
Is turned on, and the status K is set to "7" in step S128. With the original by-one of the feed motor M2 is started the conveyance at the speed V ₁ second velocity V ₂ faster than by the register rollers 58, the number of pulses from the encoder E2 PCNTM2 starts counting. The pickup roller 54 starts returning upward when the pickup motor M1 is turned on. On the other hand _{, when the} electromagnetic solenoid SL is turned off, a second pressing force N ₂ acts between the separation rollers 55 and 56.
This second pressing force N ₂ is smaller than the first pressing force N ₁ ,
The original is moved by the register roller 58 to a high second speed V.
It acts to enhance the separation performance for the next original when it is transported in ₂ . Further, in the conveyance after the registration, the separating rollers 55 and 56 are rotationally driven, so that
The elimination of the loop at the leading end of the document is performed gently, so that the occurrence of loop elimination sound and damage to the document are avoided.

If the status K is "7", it is determined in step S131 whether the count value of PCNTM2 is n1. Normally, before PCNTM2 counts n1 (NO in step S131), sensor SE10 is determined to be off-edge in step S135, and step S13 is performed.
At 6, the pickup motor M1 is turned off. Thus, the pickup roller 54 has returned to the home position. When PCNTM2 counts n1, the paper feed motor M2 is turned off in step S132, the electromagnetic brake BRK1 is turned on in step S133, and the status K is set to "8" in step S134. Thus, the rotation of the register roller 58 is stopped, and the advance feeding of the document is completed. At this time, the original is stopped when the leading end reaches the advance reference point P.

If the status K is "8", the count value of PCNTM2 is stored in PSIZE in step S141. Subsequently, at step S142, the electromagnetic clutch C
L is turned off, and in step S143, the electromagnetic brake BRK1 is turned off.
Turn off. As a result, the connection of the register roller 58 with the sheet feeding motor M2 is released, and the register roller 58 becomes free. Further, the status K is set to "20" in step S144.

When the status K is "20", since the advance feeding of the original has been completed, the process stands by without any processing. FIGS. 28 to 38 show a subroutine for setting a one-sided original at a predetermined position on the platen glass 29, which is executed in step S43. In this subroutine, step S
At 170, the set status S is checked, and the following processing is performed based on the values "0" to "16".

When the status S is "0" (at the initial stage), MODE is reset to "0" in step S171, and the paper feeding status K is set to "2" in step S172. When the status S is "1" (feeding completed,
The main motor M3 is turned on in step S175, and the status S is set to "2" in step S176. Here, the register roller 58 and the transport belt 60 are driven to rotate, and the first-fed original is started to be conveyed onto the platen glass 29.

When the status S is "2", if the on-edge of the timing sensor SE14 is confirmed in step S181, that is, if the leading edge of the document is detected by the sensor SE14, the encoder E3 of the main motor M3 is determined in step S182. PC that counts the number of pulses output from
The NTM 3a is reset to "0" and the counting is started. Subsequently, the status S is set to "3" in step S183.

When the status S is "3", if the off-edge of the register sensor SE12 is confirmed in step S191, that is, if the rear end of the document is detected by the sensor SE12, the count value of PSIZE (step S192) is reached. Step S141) and PCNTM3 at that time
The count value of “a” is added and stored in PSIZE. This count value corresponds to the length of the document. Subsequently, in step S193, PSIZE is compared with the pulse nL. nL
Is the number of pulses corresponding to a document length of 216 mm,
If PSIZE <nL, the status S is set to "4" in step S194, and the pre-step mode is executed. If PSIZE ≧ nL, the status S is set to “14” in step S195, and the single-sided normal mode is executed.

When the status S is "4", when it is confirmed in step S201 that the count value of the PCNTM 3a has reached n3, the main motor M3 is turned off in step S202 and the electromagnetic brake BRK2 is turned on in step S203. . Thus, the document is set at the pre-step position. Subsequently, the timer T201 is set in step S204, and the status S is set to "5" in step S205.

When the status S is "5", the end of the timer T201 is confirmed in step S211.
After the transport belt 60 is completely stopped, the process proceeds to step S212.
To turn off the electromagnetic brake BRK2. Subsequently, it is determined in step S213 whether the empty sensor SE11 is on or off. If the sensor SE11 is on, the next document is present on the tray 51, so the paper feed status K is set to "3" in step S215, and the status S is set to "6" in step S216. If the sensor SE11 is off, all the documents on the tray 51 have been fed, so the LST is set to "1" in step S214, and the status S is set to "6" in step S216.

If the status S is "6", it is determined in step S221 whether the paper feeding status K is "20". If the status K is set to "20", the advance feeding of the next original has been completed, and therefore, step S2
At 22, PCNTM3b is reset to “0”, and
Start the count. Subsequently, step S223
It is determined whether or not the flag DSET is “1”. Flag D
SET indicates that the document is set at the exposure position (see step S264). If the flag DSET is "0", the flow proceeds to step S226. If the flag DSET is "1", the flag DSET is reset to "0" in step S224, and the paper discharge used for discharging the original to the tray 69 in step S225. The status H is set to "1", and the routine goes to Step S226.

In step S226, the main motor M3 is turned on, and in step S227, the value of the counter LST is checked. LST indicates the number of originals in the ADF 50. If "0", the original is at the advance feeding position. In this case, the feeding status K is set to "3" in step S228.
And the status S is set to “7” in step S229.
Set to. As a result, the advance feeding of the third and subsequent documents is started at the same time when the main motor M3 is turned on in step S226. If the LST is not "0", there is no original at the advance feeding position. In this case, the LST is incremented to "1" in step S230, and the status S is set to "9" in step S231.

When the status S is "7", when the on-edge of the timing sensor SE14 is confirmed in step S235, that is, when the leading edge of the document is detected by the sensor SE14, the PCNTM 3a is set to "0" in step S236.
And the counting is started. Here, the measurement of the transport amount of the next document to the pre-step position is started. Subsequently, in step S237, the status S
Is set to “8”.

When the status S is "8", the off-edge of the register sensor SE12 is confirmed in step S241, that is, when the trailing edge of the document passes the detection point of the sensor SE12, the empty sensor S is determined in step S242.
It is determined whether E11 is on or off. If the sensor SE11 is ON, the next document is present on the tray 51, so that the status S is set to "9" in step S243, and the operation shifts to a document stopping operation. If the sensor SE11 is off,
Since all the documents on the tray 11 have been fed, step S
The paper feed status K is set to "1" at 244, and the counter LST is set to "1" at step S245.

When the status S is "9", when it is confirmed in step S251 that the count value of the PCNTM 3b has reached n5, the main motor M3 is turned off in step S252, and the value of the counter LST is checked in step S253. . If LST is other than "2", that is,
If at least two documents exist on the platen glass 29 before the document conveyance here, the electromagnetic brake BRK2 is turned on in step S254, and the timer T201 is set in step S255. If LST is "2",
Since only the last original was present at the exposure position before the original was transported here, the timer T2 was set in step S255 without turning on the electromagnetic brake BRK2 (for discharging the original).
Set 01. Subsequently, the status S is set to "10" in a step S256.

When the status S is "10", after the end of the timer T201 is confirmed in step S261, that is, after the transport belt 60 is completely stopped, step S2 is executed.
At 62, the electromagnetic brake BRK2 is turned off. Subsequently, the value of the counter LST is checked in step S263,
If it is "2", that is, if only the last original is at the exposure position, the LST is reset to "0" in step S266, and the status S is set to "0" in step S267.
And the subroutine ends. If the LST is other than “2”, and if at least two documents exist on the platen glass 29, the process proceeds to step S2.
At step 64, the flag DSET is set to "1". Flag D
SET indicates that the document has been set at the exposure position. Further, at step S265, the status S is set to "1".
Set to "1".

When the status S is "11", the flag DCHG is "1" in step S281 (document replacement is requested), and in step S282, the paper feeding status K is "20" (advance paper feeding). Is completed) and that the discharge status H is “6” (completion of discharge) in step S283, and the flag D is set in step S284.
CHG is reset to "0", and the status S is set to "6" in step S285. Thus, the document exchange process is restarted.

If the status S is "12" (when executing the one-sided normal mode, see step S355), it is determined in step S291 whether or not the flag DSET is "1". If "0", the main motor M3 is turned on in step S294. If "1", that is, if the document is set at the exposure position, step S292
Resets the flag DSET to “0” and proceeds to step S2
In step 93, the paper discharge status H is set to "1", and in step S294, the main motor M3 is turned on. Thus, the discharge of the document from the exposure position is started. Subsequently, the value of the counter LST is checked in step S295. LS
If T is "0", the next original has been fed in advance, so the status S is set to "13" in step S296. If LST is not “0”, that is, if there is no original at the advance feeding position, PCNT is set in step S297.
M3a is reset to “0” and the counting is started. Subsequently, in step S298, the status S
Is set to “14”.

When the status S is "13", when the on-edge of the timing sensor SE14 is confirmed in step S301, that is, when the leading edge of the document is detected by the sensor SE14, the PCNTM 3a is set to "0" in step S302. Reset and start counting. Subsequently, in step S303, the status S is set to "1".
4 ”.

When the status S is "14", when it is confirmed in step S311, that the count value of the PCNTM 3a has reached n7, the main motor M3 is turned off in step S312, and the value of the counter LST is checked in step S313. . LST is not "1", that is,
Since the next document is located at the advance feeding position, step S3
In step 14, the electromagnetic brake BRK2 is turned on, and in step S31
Go to 5. If LST is "1", that is, since there is no original at the advance sheet feeding position and only the last original has been set at the exposure position, the timer T201 is reset at step S315 while the electromagnetic brake BRK2 is kept off. Is set, and the status S is set to "15" in step S316.
Set to.

When the status S is "15", after the end of the timer T201 is confirmed in step S331, that is, after the conveyance belt 60 is completely stopped, the process proceeds to step S3.
At 32, the electromagnetic brake BRK2 is turned off. Subsequently, the value of the counter LST is checked in step S333. L
If ST is not "1", that is, if the next original has been set at the advance feeding position, the next original has been set at the exposure position, and the flag DSET is set at step S334.
Is set to “1”. Further, in step S335, it is determined whether or not the empty sensor SE11 is on. If the sensor SE11 is on and the original remains on the tray 51,
In step S336, the paper feed status K is set to "3", and in step S338, the status S is set to "16". If the sensor SE11 is off and no document remains on the tray 51, the document is currently set only at the exposure position. Therefore, the LST is set to "1" in step S337, and the status S is set to "16" in step S338. Set to. On the other hand, if the LST is “1” (YES in step S333), that is, since the last original has been discharged, the LST is reset to “0” in step S339.
In step S340, the status S is reset to "0", and this subroutine ends.

If the status S is "16", the flag DCHG is "1" (document replacement request) in step S351, and the paper feeding status K is "20" in step S352 (the advance feeding Completion), and that the paper discharge status H is “6” (completion of paper discharge) in step S353, and in step S354, the flag D
CHG is reset to "0", and the status S is set to "12" in step S355. Thus, the document exchange process is restarted.

FIGS. 39 to 41 show a subroutine for processing the discharge of the original, which is executed in step S44. Here, the paper discharge status H is checked in step S370, and the following processing is performed based on the values “0” to “6”. When the status H is "0", it is the initial state,
Do nothing.

If the status H is "1" (when the document starts to be discharged from the exposure position, steps S225 and S2
93), the timer T301 is set in a step S371, and the status H is set to “2” in a step S372. The timer T301 delays the driving of the discharge motor M4 until immediately before the leading edge of the document reaches the reverse / discharge roller 65.

When the status H is "2", when the end of the timer T301 is confirmed in step S375, the discharge motor M4 is turned on in step S376, and the process proceeds to step S3.
At 77, the status H is set to "3". Here, the reversing / discharge roller 65 and the discharge roller 68 start rotating, and the document starts to be discharged onto the tray 69. When the status H is "3", the discharge sensor S is determined in step S381.
After confirming the off edge of E15, that is, when the trailing edge of the document is detected by the sensor SE15, the timer T302 is set in step S382, and the status H is set to "4" in step S383.

When the status H is "4", the end of the timer T302 is confirmed in step S385, that is,
After the document is completely discharged onto the tray 69, the process proceeds to step S
At 386, the discharge motor M4 is turned off. Further, in step S387, the timer T303 is set, and in step S38
At step 8, the status H is set to "5". Status H
Is "5", the timer T303 is determined in step S391.
Is completed, that is, when the discharge motor M4 is completely stopped, the status H is set to "6" in step S392.

When the status H is "6", no processing is performed and the process stands by. The paper transporting device according to the present invention is not limited to the above embodiment, but can be variously modified within the scope of the invention.

[Brief description of the drawings]

FIG. 1 illustrates an automatic document feeder (A) according to an embodiment of the present invention.
DF) and a schematic configuration diagram of a copying machine main body.

FIG. 2 is a sectional view showing an internal configuration of the ADF.

FIG. 3 is a front view of the document separating mechanism, showing a state before document registration.

FIG. 4 is a front view of the document separation mechanism, showing a state after document registration.

FIG. 5 is a sectional view of a separating roller.

FIG. 6 is an explanatory diagram showing a contact state of a separating roller.

FIG. 7 is an explanatory diagram when one sheet is interposed between the separation rollers.

FIG. 8 is an explanatory diagram when one sheet is interposed between the separation rollers.

FIG. 9 is an explanatory diagram when two sheets are interposed between the separation rollers.

FIG. 10 is a graph showing a relationship between a torque Ts and a roller pressing force N;

FIG. 11 is a graph showing a relationship between a torque Ts and a roller pressing force N;

FIG. 12 is an explanatory diagram illustrating document conveyance in a pre-step mode.

FIG. 13 is an explanatory view showing document conveyance in the pre-step mode, continued from FIG. 12;

FIG. 14 is an explanatory view showing document conveyance in the pre-step mode, and is a continuation of FIG. 13;

FIG. 15 is a block diagram showing a drive system.

FIG. 16 is a block diagram showing a CPU 1 for controlling a copying machine main body.

FIG. 17 is a block diagram showing a CPU 2 that controls the ADF.

FIG. 18 is a flowchart showing a main routine of the CPU 1;

FIG. 19 is a flowchart showing a main routine of the CPU 2;

FIG. 20 is a flowchart showing a subroutine of an interrupt process in the CPU 2;

FIG. 21 is a flowchart showing a subroutine for initialization in the CPU 2;

FIG. 22 is a flowchart showing a document exchange subroutine in the CPU 2;

FIG. 23 is a flowchart showing a subroutine of a start check in the CPU 2;

FIG. 24 is a flowchart showing a paper feed subroutine in the CPU 2;

FIG. 25 is a flowchart showing a sheet feeding subroutine in the CPU 2, and FIG. 24 is continued.

FIG. 26 is a flowchart showing a sheet feeding subroutine in CPU 2, and is a continuation of FIG. 25.

FIG. 27 is a flowchart showing a sheet feeding subroutine in CPU 2, and is a continuation of FIG. 26.

FIG. 28 is a flowchart showing a one-sided document setting subroutine in the CPU 2;

FIG. 29 is a flowchart showing a one-sided document setting subroutine in the CPU 2, and FIG. 28 is continued.

30 is a flowchart showing a one-sided document setting subroutine in CPU 2, and is a continuation of FIG. 29.

FIG. 31 is a flowchart showing a one-sided document setting subroutine in the CPU 2, and is a continuation of FIG. 30;

32 is a flowchart showing a one-sided document setting subroutine in the CPU 2, and is a continuation of FIG. 31. FIG.

FIG. 33 is a flowchart showing a one-sided document setting subroutine in the CPU 2, and is a continuation of FIG. 32;

FIG. 34 is a flowchart showing a one-sided document setting subroutine in the CPU 2, and FIG. 33 is continued.

FIG. 35 is a flowchart showing a one-sided document setting subroutine in the CPU 2, and FIG. 34 is continued.

FIG. 36 is a flowchart showing a one-sided document setting subroutine in the CPU 2, and is a continuation of FIG. 35;

FIG. 37 is a flowchart showing a one-sided document setting subroutine in the CPU 2, and is a continuation of FIG. 36;

FIG. 38 is a flowchart showing a one-sided document setting subroutine in the CPU 2, and FIG. 37 is continued.

FIG. 39 is a flowchart showing a paper discharge subroutine in the CPU 2;

40 is a flowchart showing a paper discharge subroutine in the CPU 2, and is a continuation of FIG. 39.

FIG. 41 is a flowchart showing a sheet discharging subroutine in the CPU 2, and is a continuation of FIG. 40;

[Explanation of symbols]

 Reference Signs List 50 automatic document feeder 54 pickup roller 55 forward separation roller 56 reverse rotation roller 58 register roller 59a pinch roller 83 lever 84 coil spring 85 adjustment lever 86 coil spring TL torque limiter M2 Paper feed motor M3 ... Main motor SL ... Electromagnetic solenoid CL ... Electromagnetic clutch SE12 ... Register sensor CPU2 ... Microcomputer

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Tomoyuki Atsumi 2-3-13 Azuchicho, Chuo-ku, Osaka-shi, Osaka Osaka International Building Minolta Camera Co., Ltd. (58) Field surveyed (Int. Cl. ⁷ , DB Name) B65H 1/00-3/68

Claims (3)

(57) [Claims] A pickup unit configured to apply a conveying force to a sheet in one direction while pressing the sheet in a stacked state; a normal rotation member for conveying the sheet; and a unit for separating the conveyed sheet into one sheet. A separating unit that is located downstream of the pickup unit, separates the picked-up sheet into one sheet, and conveys the sheet downstream, and a first driving unit that drives the separating unit A transport unit that is located downstream of the separating unit and transports the separated sheet further downstream; a second driving unit that drives the transport unit; the forward rotation member and the separation member A first pressure required to separate the sheet when the sheet is conveyed at a first speed by the normal rotation member, and a time when the sheet is conveyed at a second speed by the conveying means. Needed to separate paper into Pressurizing means for selectively applying a second pressure; and conveying means after a predetermined time when the leading end of the sheet separated by the separating means driven by the first driving means abuts on the conveying means. Is driven by a second driving means, and a first control means for driving the separating means by a first driving means for a predetermined time after the conveyance of the sheet is started by the conveyance means; Then, after the transport unit receives the driving force from the second driving unit, the second pressure is increased so that the first pressure acts until the conveying unit receives the driving force from the second driving unit. And a second control means for controlling the pressurizing means so as to operate. 2. The first driving means and the second driving means have the same driving source, and the second driving means selectively transmits a driving force from the driving source to the conveying means. The sheet conveying device according to claim 1, further comprising: 3. A second speed by the transport means is set to be higher than a first speed by the normal rotation member, and the normal rotation member moves the sheet downstream at a first speed by a first drive means. When the sheet is conveyed at a second speed by the conveying means, the roller is driven to rotate at a second speed, and the separating member is a roller capable of pushing the sheet back to the upstream side. The first pressure is such that when two or more sheets are interposed between the normal rotation member and the separation member, the separation member is rotated by the first driving means so as to push the sheet back to the upstream side, and When a sheet is interposed, the value is set to a value that rotates following the conveyance of the sheet to the downstream side, and the second pressure is set to be smaller than the first pressure. The sheet conveying device according to claim 1.