JPH09110223A - Paper sheet feeder and image forming device having it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic document feeder which can prevent duplicate feed of documents and can reliably feed documents even when a wedge phenomenon is caused, and an image forming device having it. SOLUTION: A semicircular roller 4 is arranged in a document guide part R arranged between a document tray 1 and a separating part C, on the one hand, a shutter 3 is arranged in the document guide part R so as to freely protrude and retreat, and a document bundle DX is prevented from entering the separating part C before feed is started by the shutter 3. When the lowest document D4 is fed, after the semicircular roller 4 is rotated until a locking part 4a is put in a condition of locking the lowest document D4 , the shutter 3 is retreated from the document guide part R, and the lowest document D4 is carried to the separating part C in a most precedent condition. When the document cannot be fed, pressing-down operation by a pressing-down member 14 is repeated by the prescribed number of times, and a wedge phenomenon is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding device and an image forming apparatus including the same, and more particularly to a structure of a separating unit for separating a document.

[0002]

2. Description of the Related Art In an automatic document feeder, which is an example of a conventional paper feeder, one original is fed from a stacked original bundle.
A separating unit that separates the sheets one by one, and a document feeding unit that is provided on the downstream side of the separating unit pulls out the document separated from the separating unit and places it on a platen as a document reading unit. Some are configured to be discharged from.

Some image forming apparatuses equipped with such an automatic document feeder have both a facsimile function and a document copying function. In such an image forming apparatus, an automatic document feeder is provided. The feeding device needs to change the page order (separation method) of a bundle of documents to be processed during facsimile and copying (copying a document) as follows.

That is, in the case of a facsimile, for example, in the case of a document stack with the image surface facing upward, the pages are sequentially transmitted from the first page, so the upper separation system is used in which the sheets are sequentially fed from the uppermost sheet of the document stack. The lower separation system is used in which the lowermost sheet of the original stack is sequentially fed so that the original stack is stacked on the sheet discharge tray of the apparatus in the same order as the original stack.

Here, for example, when the lower separation method is adopted,
As shown in FIG. 17, the originals of the original bundle DX stacked on the tray 201 are stored in the half-moon roller 204, the paper feed roller 220,
By rotating the separation belts 221 counterclockwise, the document at the bottom of the document stack DX (hereinafter referred to as the bottom sheet) D ₃
The sheets are separated one by one in order. Then, the separated bottom sheet D ₃ is pulled out by the registration roller 209,
It is adapted to be placed on the platen 251 by the conveyor belt 206.

On the other hand, when the upper separation method is adopted, the half-moon roller 204 rotates counterclockwise and the separation belt 2
21 and the feeding roller 220 rotate or rotate clockwise, so that the uppermost document (hereinafter referred to as the uppermost sheet) D ₁ of the document bundle DX is sequentially separated.

By the way, the tray 201 is a document bundle DX.
Is inclined toward the separating section C so that the document stack DX naturally falls on the separating section C, but the separating section C is prevented from dropping the document bundle DX until the processing in the image forming apparatus is started.
A shutter 203 is provided on the upstream side of.

[0008]

By the way, in such a conventional automatic document feeder, for example, in the case of performing the lower separation, when the feeding operation is started, it is raised as shown in FIG. The shutter 203, which is located at the position and prevents the document bundle DX from naturally falling, descends as shown in FIG. 18B, and then the half-moon roller 204 starts to rotate.

Here, the half-moon roller 204 has a circumferential portion and a chord portion, and is configured to convey an original by bringing a conveying point 204a, which is a corner thereof, into contact with the original. Since the position of the transport point 204a when the shutter is lowered is the position shown in FIG. 18A, the transport point 204a comes into contact with the bottom sheet D ₄ after the half-moon roller 204 has passed a predetermined time. .

Therefore, it takes time for the half-moon roller 204 to start conveying after the shutter 203 descends, and during this time, the document bundle DX enters the separation nip C1 by a natural drop. Then, for example, when the bottom paper D ₄ has a high coefficient of friction, the upper paper comes into the separation nip C1 much earlier than the bottom paper D ₄ , and in such a case, the bottom paper D ₄ There is a problem that the document that has entered the separation nip C1 is fed the earliest.

When performing the upper separation, first, the pre-separation guide 205 is switched to the upper separation state as shown in FIG. 19A by the reverse rotation of the separation unit drive motor (not shown). Is in a raised position, which prevents the document bundle DX from falling naturally.

Next, when the shutter 203 descends and then the discharge roller 214 driven in the CW direction rotates downward and falls on the document stack DX as shown in FIG. The conveyance of D _{1 to} the separating section C is started. Also here, the shutter 20 is operated by the same action as in the lower separation.
During the period from the lowering of 3 to the start of the conveyance of the paper discharge roller 214, the free fall of the document occurs. Then, for example, when the coefficient of friction of the uppermost paper D ₁ is particularly low, the documents other than the uppermost paper D ₁ enter the separation nip C1 first, and there is a problem that double feeding occurs.

On the other hand, for example, the separation upper guide 290 is provided in the separation section C as shown in FIG.
The leading edge of the original is guided to the separation nip by 0, and the leading edge of the original is prevented from contacting with the curved surface portion 221c of the separating belt 221. When provided, the paper guide G formed by the guide forming surface 290a of the upper separation guide 290 and the upper surface 205a of the pre-separation guide 205 has a wedge shape.

Therefore, when a bundle of many originals is received by the paper guide G by the conveying force F ′ by the half-moon roller 204 and advances in the nip direction, a vertical force received by the paper guide G from the vertical direction by the paper guide G. F, F gradually increases,
By these forces F, F, the pre-separation guide 20 for the bottom sheet D ₄
5 and the resultant force F ″ of the frictional force received from the second document D ₃ from the bottom increases.

When the resultant force F ″ of the frictional force becomes larger than the conveying force F ′ by the half-moon roller 204 (F ″> F ′), the lowermost paper D ₄ cannot be conveyed to the separation nip. The wedge phenomenon will occur.

As a countermeasure against this, as shown in the figure, the discharge roller 214 is dropped on the document bundle DX in a state where it is not rotated, and the weight of the discharge roller 214 causes the contact pressure between the lowermost sheet D ₄ and the half-moon roller 204. Although so as to increase the F 'by increasing, in some cases can not convey the lowermost sheet D ₄ to the separation nip from it is a fraction of a second contact pressure even when configured in this manner will increase There was a problem.

Therefore, the present invention has been made in order to solve such a problem, and provides a sheet feeding device capable of preventing double feeding of documents and an image forming apparatus having the same. The purpose is. It is another object of the present invention to provide a sheet feeding device that can reliably feed an original even when a wedge phenomenon occurs and an image forming apparatus including the same.

[0018]

SUMMARY OF THE INVENTION According to the present invention, a stack of originals is stacked on a slanted original tray, and one of the originals of the original stack is fed from the bottom by a separating portion provided on the slanted side of the original tray. In the paper feeding device that separates and feeds each,
The document guide is provided between the separating section and the document tray, and the lowermost document of the document stack is locked on the peripheral surface to convey the document to the separating section. A feed rotary member having a portion formed therein, a feed rotary member driving unit for rotating the feed rotary member, and a feed rotary member provided between the separating portion of the document guide unit and the feed rotary member so as to start feeding. A stopper member for preventing the document bundle from entering the separating portion due to the inclination of the document tray, a stopper member retracting means for retracting the stopper member in and out of the document guide portion, and feeding of the lowermost document. When the feeding is performed, after rotating the conveying rotary member until the locking portion locks the lowermost document, the conveying rotary member driving means and the conveying rotary member driving means for retracting the stopper member from the document guiding portion. The stopper member retractable hand It is characterized in that and a control device for controlling driving.

According to the present invention, a stack of originals is stacked on an inclined original tray, and the originals of the original bundle are separated one by one from the uppermost portion by a separating portion provided on the inclined side of the original tray. In a paper feeding device for feeding, it is vertically movable above a document guide part provided between the separating part and the document tray, and is lowered when feeding the uppermost document of the document stack. And the uppermost original, and an upper conveying rotary body that rotates in the original feeding direction, an upper conveying rotary body moving unit that vertically moves the upper conveying rotary body, and an upper portion that rotates the upper conveying rotary body. It is provided so as to be retractable between the conveying rotating body driving means, the separating section of the document guiding section, and the upper conveying rotating body, and the document bundle is fed to the separating section by the inclination of the document tray before the feeding is started. The stopper member that prevents entry and the front Stopper member retracting means for retracting the stopper member into and out of the document guide portion, and driving the upper transporting rotating body moving means so as to bring the upper transporting roller into contact with the uppermost document when feeding the uppermost document. On the other hand, a control device for controlling the upper transporting rotator driving means and the stopper member retracting means so as to retract the stopper member from the document guide portion after rotating the upper transporting rotary body. It is characterized by that.

Further, according to the present invention, a stack of originals is stacked on a slanted original tray, and the originals of the original bundle are separated one by one from the top or the bottom by a separating portion provided on the slant side of the original tray. In a paper feeding device that feeds separately,
The document guide is provided between the separating section and the document tray, and the lowermost document of the document stack is locked on the peripheral surface to convey the document to the separating section. Is provided above the document guide unit and is movable up and down to feed the uppermost document of the document stack. When carrying out, after descending and coming into contact with the uppermost document, an upper transport rotator rotating in the document feeding direction, an upper transport rotator moving means for vertically moving the upper transport rotator, and the upper transport rotation. An upper conveyance rotating body driving means for rotating the body, and a stopper provided so as to be retractable into and out of the document guide portion and for preventing the document bundle from entering the separating portion due to the inclination of the document tray before starting feeding. Member and the stopper member to the document guide section. And the stopper member releasing means to be,
When feeding the lowermost original, the stopper member is retracted from the original guide after rotating the transport rotary member until the locking portion locks the lowermost original. When the uppermost original document is fed by driving and controlling the conveying rotary member driving unit and the stopper member retracting / retracting unit, the upper conveying rotary member is brought into contact with the uppermost original document. A controller for driving and controlling the moving means, and for driving and controlling the upper conveying rotator driving means and the stopper member retracting means so as to retract the stopper member from the document guide portion after rotating the upper conveying rotator. , Is provided.

Further, according to the present invention, a stack of originals is stacked on a slanted original tray, and the originals of the original stack are separated one by one from the top by a separating portion provided on the slant side of the original tray. In a paper feeding device for feeding to a reading section, a conveyance rotating body which is arranged in a document guide section provided between the separation section and a document tray and conveys the bundle of documents to the separation section, and the document. A stopper member that is provided so as to be retractable between the separating portion of the guide portion and the conveying rotary body, and that prevents the document bundle from entering the separating portion due to the inclination of the document tray before starting feeding. A pressing member that is vertically movable above the document guide unit and that moves downward to press the document bundle against the conveying rotary member when feeding the document bundle, and a pressing member that vertically moves the pressing member. Moving means and the separating section A document detecting unit that is provided between the document reading unit and detects that the separated document is fed to the document reading unit, and the stopper member guides the document when the document is fed. If the document feeding signal is not input from the detection means after the document is retracted from the copy unit,
A control device for driving and controlling the pressing member moving means so as to repeat the pressing operation a predetermined number of times.

Further, according to the present invention, the pressing member descends when the uppermost document of the document stack is fed, contacts the uppermost document, and then rotates in the document feeding direction. It is characterized by being a body.

Further, according to the present invention, a paper feeding device for feeding a document to a document placing portion, an image forming portion for reading a document fed by the paper feeding device and forming an image on a sheet,
An image forming apparatus comprising: the paper feeding device is the paper feeding device according to any one of claims 1 to 5.

With this structure, the lowermost document of the document stack is provided on the peripheral surface in the document guide portion provided between the inclined document tray and the separating portion provided on the inclined side of the document tray. On the other hand, a conveying rotary body is provided which is locked to convey an original to the separating section, and a stopper member is provided between the separating section of the original guide section and the conveying rotary body so that the stopper can be retracted. The member prevents the bundle of documents from entering the separation unit due to the inclination of the document tray in the document guide unit before the feeding is started.

Then, when feeding the lowermost original, the control device rotates the conveying rotary member until the locking portion locks the lowermost original, and then causes the stopper member to move from the original guide. The conveying rotary member driving means and the stopper member retracting means are drive-controlled so as to be retracted so that the lowermost document is conveyed to the separating section in the most preceding state.

Further, when the uppermost document of the document stack is fed above the document guide portion, an upper conveyance rotator which descends and comes into contact with the uppermost document and then rotates in the document feeding direction is moved up and down. While it is movably provided, a stopper member is provided between the separation portion of the document guide portion and the upper transport rotary member so that the stopper member can be retracted and retracted. Try to block entry.

Then, when feeding the uppermost document, the control device brings the upper conveyance rotary member into contact with the uppermost document and then rotates it, and then the upper conveyance so that the stopper member is retracted from the document guide portion. The rotator moving means, the upper conveying rotator driving means, and the stopper member retracting means are drive-controlled so that the uppermost document is conveyed to the separating section in the most preceding state.

Further, above the document guide portion, a pressing member for lowering and pushing the document bundle against the conveying rotary member when the document bundle is fed is provided so as to be vertically movable, while the separating portion and the document reading portion are provided. A document detecting unit is provided between the document detecting units and detects that the document separated by the document detecting unit is fed to the document reading unit.

When the document is fed, the control unit retracts the stopper member from the document guiding portion, and then, when the document feeding signal is not input from the detecting means, the pressing member performs a pressing operation. The pressing member moving means is drive-controlled so as to be repeated a number of times to prevent the wedge phenomenon.

[0030]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of the essential parts of an automatic document feeder, which is an example of a paper feeding device according to the present invention. This automatic document feeder A is mounted on a paper feed tray 1 which is a document tray. The user has a structure in which the document stack DX is stacked face-up, is an example of an image forming apparatus, and is provided in a digital composite copying machine (hereinafter referred to as a composite copying machine) B that also has a FAX function as well as a copy function. It is a thing.

In the figure, 2 is a swing guide, 3 is a shutter which is a stopper member, 4 is a half-moon roller which is a conveying rotary member, 5 is a pre-separation guide, 6 is a conveyor belt, 7,
8, 12, 13 are guides, 14 is an upper conveyance rotating body, and a discharge roller that also serves as a pressing member to be described later.
5 is a pinch roller, 16 is a rotation center axis of the arm 17, 1
Reference numeral 9 is a paper retainer, and 20 is a separation roller which is a rotating body.

Reference numeral 21 denotes a separation belt which is provided so as to face the separation roller 20 and sandwiches the original bundle DX, and which is a belt for separating originals which is rotated in the same direction as the separation roller 20 to separate the originals. 22 is a drive pulley, 23 is a belt support, 24 is a driven pulley, 25 is a cam shaft, 51
Is a platen, and 52 is a left jump table.

In the automatic document feeder A having such a structure, when performing document processing, first, the document bundle D
X is set face up on the paper feed tray 1, and in the copy mode, the lowermost sheet D ₃ of the document bundle DX is separated by the half belt 4 as shown in (1) of FIG.
1 is fed to a separating section C provided with a separating roller 20 and the separating roller C, and the lowermost sheet D ₃ is placed on the platen 51 on the upper surface of the composite copying machine B after being separated by the separating section C.

Next, when the image exposure for the copying operation of the composite copying machine B is completed, the original (lowermost paper D ₃ ) is conveyed by the conveyor belt 6 in the left direction as shown by the arrow in the figure, and the conveyor roller 9 is used. And is returned to the paper feed tray 1 again via the paper discharge roller 14. In this way, the originals are sequentially fed and ejected, and when all the originals are ejected, the original bundle DX returns to the state set by the user for the first time.

By the way, when separating the original bundle in this way, when the original bundle DX is set on the paper feed tray 1, the shutter 3 is moved to the paper feed tray 1 as shown in FIG. , The swing guide 2, and the pre-separation guide 5 project upward from a paper guide surface R which is a document guide portion up to the separation nip, and the shutter 3 causes the document bundle D
The free fall of X is prevented.

On the other hand, the operation unit 1 of the composite copying machine B shown in FIG.
When the copy mode is selected at 50, the control device 151
First, the half-moon roller drive motor M1 which is a conveyance rotator driving means is driven to rotate the half-moon roller 4 CCW as shown by the arrow in FIG.

Then, in this way, the half-moon roller 4 is CCWed.
After rotation for a predetermined time, in this embodiment, when the half-moon roller 4 starts rotating and 120 msec elapses,
As shown in FIG. 4B, the control device 151 drives the shutter drive motor M2, which is a stopper member retracting unit, to lower the shutter 3 and retract it from the paper guide surface R.

Here, this 120 msec is formed on the circumferential surface of the half-moon roller 4 which has started to rotate, and the conveying point 4a, which is a locking portion for locking the lowermost sheet D ₄ and transporting it to the separating section C, is the lowest. It is time to start contact with paper D ₄ ,
After the lapse of 0 msec, the shutter 3 is lowered, so that the lowermost sheet D ₄ is immediately conveyed by the conveying force of the half-moon roller 4.

[0040] Thus, the original bundle DX separation nip C1 in a state in which the lowermost sheet D ₄ is the most prior without free fall
It is possible to prevent the double feed.

On the other hand, in the FAX mode, as shown in (2) of FIG. 2, the document stack DX is fed toward the separation section by the paper discharge roller 14 acting as a so-called pickup roller. The paper discharge roller 14 is held at the tip of an arm 17 (see FIG. 1) that is rotatable around a rotation center shaft 16, and in the FAX mode, it is placed on the document bundle every time one document is fed. It is designed to fall.

Then, when the uppermost sheet D ₁ enters the separating section C by the discharge rollers 14, the separating section C performs the function of upper separation, whereby only the uppermost sheet D ₁ is fed in the direction of the arrow and the platen. It is placed on 51. Next, when the original is placed on the platen 51 in this manner, the composite copying machine B
Reads the document image information for FAX transmission.

The read original (the uppermost sheet D ₁ ) is conveyed rightward in the figure by the conveyor belt 6 along the arrow, and is fixed to the composite copying machine B via the right paper discharge roller pair 18M. The sheets are discharged face down (original surface downward) onto the existing discharge tray 18, and are sequentially stacked. As a result, when all the originals have been conveyed and read, the original bundle D
Xs are stacked in the same page order as when they were first set on the discharge tray 18.

By the way, when the document bundle DX is separated in this way, the pre-separation guide 5 is switched to the upper separation state by the reverse rotation of the separation unit drive motor (not shown), and the document stack is placed on the paper feed tray 1. Set to. At this time, the shutter 3
Protrudes above the paper guide surface R as shown in FIG. 5 (a), whereby the document stack DX is prevented from falling naturally.

In this state, the control device 151 first drives the paper discharge roller moving motor M3, which is an upper conveying member moving means, to move the paper discharge roller 14 onto the uppermost original D ₁ as shown in FIG. 5A. Drop it on. At this time, the discharge roller 14
Is not driven, so that the document stack DX is pressed by the weight of the paper discharge roller 14 and is not naturally dropped at the moment when the shutter 3 is lowered.

After that, the control device 151 drives the shutter drive motor M2 to lower the shutter 3 as shown in FIG. 5B, and at the same time, the discharge roller drive motor M4 which is the upper conveyance body drive means is activated. Drive and eject roller 1
4 is rotated in the CW direction. Then, by simultaneously lowering the shutter 3 and rotating the paper ejection roller 14 in the CW direction, the uppermost original D ₁ is immediately conveyed by the conveyance force of the paper ejection roller 14.

As a result, the document stack DX can be allowed to enter the separation nip with the uppermost document D ₁ being most advanced without naturally falling, and therefore double feeding can be prevented.

By the way, in the case of lower separation, in the case where the separation upper guide 29 is provided in the separation portion C, the wedge phenomenon may occur as described above. In this case, as described above, the contact pressure increases for a moment only by dropping the paper discharge roller 14 onto the uppermost sheet D _1. Therefore, by continuously generating the contact pressure, the wedge phenomenon occurs. I try to prevent it.

FIG. 6 is a view showing the arrangement of the separating section C of the automatic document feeder according to another embodiment of the present invention. In the figure, reference numerals 94 and 95 denote paper guides, and the original that has passed through the separation nip is the paper guides 94 and 95.
It is supposed to be introduced during. On the other hand, a sensor flag 91 projects between the paper guides 94 and 95, and the sensor flag 91 is pressed by a document introduced between the paper guides 94 and 95 to CCW around the fulcrum 92. It rotates so as to block the optical path of the photo interrupter 93 which is the document detecting means.

Here, the photo interrupter 93 is
As shown in FIG. 7, it is connected to the control device 151, and the control device 151 detects the passage of the document based on the signal from the photo interrupter 93.

By the way, the document is not introduced between the paper guides 94 and 95 due to, for example, a wedge phenomenon, and the paper discharge roller 14
If a signal from the photo interrupter 93 is not input after a predetermined time has elapsed after driving the
In the present embodiment, the first embodiment forms a document bundle DX by driving the paper discharge roller 14 that functions as a pressing member and the paper discharge roller drive motor M3 that functions as a pressing member moving unit in the forward and reverse directions a predetermined number of times at a predetermined timing. I try to drop it repeatedly.

By dropping the paper discharge roller 14 onto the original bundle DX in this manner, the original bundle DX can be pressed against the half-moon roller 4, whereby the half-moon roller 4 is pressed.
Then, the pressure contact force between the lowermost paper sheet D ₄ and the lowermost paper sheet D ₄ is increased, and the conveying force F ′ is increased. Further, the contact pressure can be continuously generated by repeatedly dropping the paper discharge roller 14 a predetermined number of times at a predetermined timing and dropping it onto the document bundle DX, and the lowermost paper D ₄ is surely introduced into the separation nip. I am able to do that.

The position of the paper discharge roller 14 at this time,
FIG. 8 is a graph showing the conveyance force F ′ by the half-moon roller 4 and the conveyance amount 1 from the wedge portion of the document. Where P
₁ , P ₃ , P ₅ indicate that the paper discharge roller 14 is in a position to start dropping, and P ₂ , P ₄ , P ₆ indicate the paper discharge roller 14
Indicates that it is in the position where it started to rise. The lowermost sheet D ₄ is conveyed only while the conveying force F ′ exceeds the resultant frictional force F ″ (t).

The reason why the conveying force F'has a peak value at the moment when the paper discharge roller 14 falls on the document is that the kinetic energy at the moment when the paper discharge roller 14 which has kinetic energy due to the fall falls on the document surface. This is because the rubber of the half-moon roller 4 under the original is deformed by the inertial force and a large pressure contact force is obtained.

By the way, the automatic document feeder A is provided with a switching mechanism for switching the functions of the upper separation and the lower separation of the separation section C, and as described above, the FAX mode and the copy mode. Separation part C
The functions of upper separation and lower separation are switched. Here, in this switching mechanism, as shown in FIG.
That is, by rotating in the transport direction and the transport reverse direction and making the coefficient of friction of the member rotating in the transport direction higher than the friction coefficient of the member rotating in the transport reverse direction, This is a so-called comb tooth separation system in which only one sheet of paper that is in direct contact is fed, while the rest is returned by a member that rotates in the reverse direction of conveyance.

FIG. 9 shows the details of the switching mechanism 20A. In FIG. 9, 20a is a first separating roller, which is an EPDM having a friction coefficient with paper of 2.0. The first separating roller 20a is fixed to the flange 20a 'made of P0M resin by press fitting. 2l
a is the first separation belt, and the coefficient of friction with paper 1.
2 EPDM.

Here, the first separating roller 20a and the first separating belt 2la form a lower separating nip in pairs in the copy mode.
By rotating a in the transport direction and a separation belt 21a in the transport reverse direction, only the bottom sheet is fed.

A second separating roller 20b is provided between the first separating roller 20a and the first separating belt 2la.
And a second separation belt 21b are provided respectively.
Here, the second separation roller 20b and the second separation belt 21b are paired in the FAX mode, and by rotating the separation belt 2lb in the transport direction and the separation roller 20b in the transport reverse direction, only the uppermost sheet is printed. Is designed to be fed. The separation roller 20b is an EPDM having a friction coefficient of paper of 1.2, and the separation belt 2lb is an EPDM having a friction coefficient of paper of 2.0.

By the way, in this way, the switching mechanism 20A
In case of the above, when the lower separation is performed, the upper separation separation pair 20b,
21b hinders the separation, and at the time of the upper separation, the lower separating pair 20a, 21a also hinders the separation. Therefore, at the time of lower separation, the lowermost position of the first separation belt 2la is set to the height h in the drawing, and the second separation belt 2lb is set to the height h'in the drawing, so that the upper separation separation pair 20b, Two
The nip of 1b is released, and at the time of upper separation, the second separation belt 2
lb is set to the height h in the figure, and the first separation belt 2la
To the height of h'in the figure, the separating pair for lower separation 20
It is configured to release the nip between a and 21a.

Next, a mechanism for releasing such a nip will be described with reference to FIG.

In the figure, 22 is a drive shaft for the first and second separation belts 21a and 21b, 22a and 22b are driven pulleys made of resin, and fixed to the drive shaft 22 by integral molding. Reference numerals 23a and 23b denote shafts of the drive pulleys 22a and 22b and the driven pulleys 24a and 24b that hold the first and second separation belts 2la and 2lb so as to stretch and stretch the first and second separation belts 2la and 2lb. First and second belt supports 23a and 23b for maintaining the distance between them.
Is rotatable with respect to the drive shaft 22 and the driven pulleys 24a and 24b.

Then, these belt supports 23a, 2
3b rotates about the drive shaft 22 together with the first and second separation belts 2la, 2lb by changing the height of the positioning surface 23A in the figure, and the height with the separation roller 20 is shown in FIG. It can be changed to h or h '. With this, the nip is released.

Next, in this way, the belt supports 23a, 2
Changing the height of the positioning surface 3b will be described with reference to FIG.

In the figure, the cam shaft 25 is set so as to rotate 90 ° in each of CW (clockwise direction) and CCW (counterclockwise direction). The height of the separation belt 21 is set to the upper separation state at a position rotated by 90 °.

By the way, the first cam 25a and the second cam 25b made of resin are fixed to the cam shaft 25 by integral molding, and the first cam 25a is the first belt support 23a.
At a position corresponding to the positioning surface 23A in the longitudinal direction,
The second cam 25b is located at a position corresponding to the positioning surface of the second belt support 23b in the longitudinal direction.

Incidentally, (1) in the figure shows a copy state (lower separation state), and the first belt support member 23 is moved depending on the cam phase.
a is lowered, and the positioning surface is in contact with the screw head of the screw 25A attached to the first cam 25a. Further, the second belt support member 23b is in the nip release position by the positioning surface 23A being lifted by the second cam 25b. The first and second belt supports 23a,
23b is constantly subjected to a force in the P direction in the figure by a biasing member (not shown), and the positioning surface is always displaced along the cams 25a and 25b.

Here, when the copy state is changed to the FAX state (upper separation state), the cam shaft 25 is changed to C
Rotate CW 90 °. Thereby, the first
The cam 25a and the second cam 25b go through the state shown in (2) of the figure and stop at the upper separation position shown in (3) of the figure.

When the first cam 25a and the second cam 25b stop at this position, the positioning surface 23A is lifted by the first cam 25a, the first belt support 23a rises and the belt nip is released. Meanwhile,
When the contact of the second cam 25b with the second belt support 23b is released, the second belt support 23b descends and an nip for upper separation is formed. When the cam shaft 25 is rotated by 90 degrees to CW from this state, the cam shaft 25 returns to the lower separation position.

On the other hand, the positioning surface 23A at the nip forming position
Is on the screw head of the screw 25A because the height of the belt at the nip has a great influence on the separation performance, so high-precision position accuracy is required. This is because if it is not inside, it can be adjusted by the screw height. Further, after adjustment, the nut shown is tightened to form a double nut to prevent loosening, and the screw head position is maintained.

By the way, when switching between upper separation and lower separation in this way, the shape of the paper guide surface up to the separation nip constituted by the paper feed tray 1, the swing guide 2, and the pre-separation guide 5 is changed. I am trying.

Here, the paper feed tray 1 is fixed to the main body of the apparatus, and the swing guide 2 is rotatably supported on a unit side plate 40 shown in FIG. The tension spring 33 stretched between the fixed portion 400 and the fixed portion 400 applies a bias in the CCW direction, and the biasing force abuts against the cut-and-raised portion 35 of the side plate 40 for positioning.

The pre-separation guide 5 is rotatably supported by the swing guide 2 by a fulcrum shaft 34. Note that 31
Is a caulking shaft provided on the unit side plate 40, on which the pre-separation guide 5 abuts by its own weight.

In the upper separation, the guide surface before the separation nip configured as described above is formed into a downward convex V shape as shown in FIG. 12 (1). As a result, the document stack DX slides in the lower left direction in the figure under its own weight, and the leading end contacts the stopper 3 and stops.

On the other hand, in the lower separation, (2) in FIG.
As shown in, the cam shaft 25 is adapted to rotate from the upper separated state to 90 ° CW. In the figure, 25
Reference numeral c is a guide switching cam, and 30 is a positioning arm rotatably held by the central shaft 20c of the separation roller 20.

When the cam shaft 25 rotates in this way, the positioning arm 30 is pushed down by the guide switching cam 25c as the cam shaft 25 rotates, and the central shaft 20
It swings CCW around c, and the right end of it swings 2
To lift the tip of. Here, when the tip of the swing guide 2 is lifted in this way, the pre-separation guide 5
The fulcrum shaft 34 rises and the pre-separation guide 5 no longer contacts the positioning shaft 31 accordingly, so that the pre-separation guide 5 further rotates CCW with respect to the swing guide 2 and the positioning surface 5b bends and raises the swing guide 2. Positioned by abutting on the portion 2a.

As a result, the guide shape at the time of lower separation is constructed as shown in the figure, and in this state, the user stacks the document bundle DX on the paper stacking portion formed by the paper feed tray 1 and the swing guide 2.
When is set, the document stack DX comes into contact with the stopper 3 and stops.

As described above, in the present embodiment, both the upper separation and the lower separation can be performed by one separating portion by changing the pressurization and release of the separation belt and the shape of the paper guide before the separation. There is.

By the way, in this structure, the upper and lower separations are switched by changing the phase of the cam shaft 25. As a method for changing the phase, a solenoid, an electromagnetic clutch or the like is used. Although a means by electric control is also conceivable, cost reduction and simplification of electric control are realized by using the following mechanical means in the present embodiment.

Next, the switching of the cam shaft 25 will be described. FIG. 13 is a top view of the separating portion for explaining the camshaft switching mechanism. In FIG.
Is a first and second arm with a one-way clutch fitted to the separation roller shaft 20c. Here, the driving force is transmitted only to the first arm 36 when the separation roller shaft 20c rotates to CW, and the driving force is transmitted to the second arm 37 only when the separation roller shaft 20c rotates to CCW. Is.

The third and fourth arms 25d and 25e are fixed to the cam shaft 25.
5d is attached to the first arm 36, and the fourth arm 25e is attached to a portion corresponding to the second arm 37.

Further, a spring support plate 38 is screwed to the end portion of the cam shaft 25, and a space between the spring support plate 38 and the cut-and-raised portion 40a of the side plate 40 is as seen from the arrow B in FIG. As shown in FIG. 14, a tension spring 39 is hooked,
A toggle force is applied to the cam shaft 25 by the tension of the tension spring 39.

By the way, in the figure, 1 is the force axis 25.
When the force shaft 25 is in the neutral phase, the rotational moment by the spring 39 is 0, but the cam shaft 25
When is moved to CCW, the rotation moment to CCW becomes
In addition, when it is moved to CW, a rotational moment to CW is generated.

Here, when the cam shaft 25 rotates toward CW, the spring support plate 38 contacts the stopper 4Ob which is the cut-and-raised portion of the side plate 40, and the spring force is received to stop the rotation. This state is when the copy is separated. Also,
When rotated to CCW, the spring support plate 38 contacts the stopper 4Oc and stops the rotation. This state is when the FAX is separated.

On the other hand, FIG. 15 is a sectional view of the present embodiment showing the action of the arm for switching the phase of the force shaft 25, as seen from the front, and (1) in the same figure shows the upper separation state. There is. Here, in this upper separation, since the separation roller shaft 20c is rotated to CW, the drive is transmitted to the first arm 36 via the one-way clutch, but the corresponding third arm 25d is rotated by the first arm 36. It is in a position where it does not interfere or engage even if it moves. The fourth arm 25e is
Although there is a position where the corresponding second arm 37 interferes when it rotates, it does not matter because the drive is not transmitted to the second arm 37 by the one-way clutch.

Next, the operation of switching from upper separation to lower separation will be described. At the time of switching, the separation unit drive motor (not shown) reversely rotates, and the separation roller shaft 20C driven by this reverse rotation.
Also changes the rotation direction from CW to CCW. As a result, the second arm 37 becomes capable of transmitting drive, and the fourth arm 25e
Engage with each other and rotate the cam shaft 25 to CW.

Then, when the cam shaft 25 rotates to a point beyond the toggle neutral position shown in (2) of the same figure, the rotation moment of the tension spring 39 causes the lower separated state shown in (3) of the same figure. Rotate to the position. Here, when this state is reached, the fourth arm 25e is in turn connected to the corresponding second arm 25e.
At a position where it does not interfere with the arm 37, the third arm 25d
Are set to have a positional relationship in which they interfere with the first arm 36.

As a result, when the separating portion drive motor is rotated in the reverse direction again from the lower separated state, the first arm 36 becomes capable of transmitting the drive force, meshes with the third arm 25d, and rotates the cam shaft 25 to CCW. Then, when the cam shaft 25 rotates to a position beyond the toggle neutral position, the tension spring 39
The rotation moment causes the rotation to the position of the upper separation state shown in (1) of FIG.

Thus, in this embodiment, the separation belt 2
1 and the separation section drive motor that drives the separation roller 20 in the forward and reverse directions to reverse the rotation direction of the separation pair (belt, roller) to switch between upper separation and lower separation, and also to change the phase of the cam shaft. It has the effect of changing the paper guide shape before separation and pressing and releasing the separation nip.

Next, an embodiment of an image forming apparatus for forming an image using the above-described sheet feeding apparatus or automatic sheet feeding apparatus will be described with reference to FIG.

In the figure, the original document conveyed by the conveyor belt 6 is placed on the platen 51, and an image is formed by the image forming apparatus arranged below. That is, the light 101 reflected by the original on the platen 51, which is irradiated by a lamp (not shown), is converted into an image information signal by an optical reading device 102 such as a CCD, while the laser scanner unit 103 responds to the image information signal. The photosensitive drum 10 as an image carrier is irradiated with a laser.
4 is exposed and a latent image is formed.

Then, this latent image is the toner 10 of the developing device.
5, the developed image is transferred to the transfer means 10.
6, 107 is transferred to the sheet P fed by the registration roller 108. The sheet P is fed to the registration rollers 108 from the removable cassettes 109 and 110, the deck 111 or the manual feed tray 112.

On the other hand, the sheet P to which the developed image has been transferred is sent to the fixing device 114 by the conveyance belt 113 and fixed therein, and in the case of one-sided copying, the sheet is ejected to the ejection tray 115 by the conveyance roller. In the case of double-sided copying, the sheet P after the single-sided fixing is reversed / conveyed by the conveyor belts 117 and 118 and the reversal guide 119 by switching the flapper 116, temporarily placed on the intermediate tray 120, and from there, the half-moon roller 121. The registration roller 1 by the roller 122, etc.
08, the developed image is transferred and fixed on the other surface of the sheet P in the same image forming process as described above. When an image is to be formed again on the same fixed surface, the sheet P is conveyed in the direction of 124 by the flapper 123, and from there, the sheet P is transferred as in the case of the double-sided image formation.
Is conveyed to form an image.

[0093]

As described above, according to the present invention,
When feeding the lowermost original, the stopper member is retracted from the original guide portion after rotating the transport rotary member until the locking portion locks the lowermost original.
The lowermost document can be conveyed to the separation unit in the most advanced state. Further, when the uppermost original is fed, the upper conveyance rotary member is brought into contact with the uppermost original and then rotated, and then the stopper member is retracted from the original guide section. It can be conveyed to the separation unit in the preceding state. By thus transporting the uppermost document or the lowermost document to the separating unit in the most advanced state, it is possible to prevent double feeding of the documents.

Further, when the document is fed, the document can be reliably fed by repeating the pressing operation by the pressing member a predetermined number of times.

[Brief description of the drawings]

FIG. 1 is a diagram showing an internal configuration of an automatic document feeder, which is an example of a sheet feeding device according to an embodiment of the invention.

FIG. 2 is an explanatory view of a paper feeding operation of the automatic document feeder.

FIG. 3 is a block configuration diagram of a control device of the automatic document feeder.

FIG. 4 is a diagram showing operations of a stopper and a half-moon roller at the time of lower separation.

FIG. 5 is a diagram showing operations of a stopper and a half-moon roller at the time of upper separation.

FIG. 6 is a view showing operations of a stopper and a half-moon roller at the time of lower separation of the automatic document feeder according to another embodiment of the present invention.

FIG. 7 is a block configuration diagram of a control device of the automatic document feeder.

FIG. 8 is a diagram showing a relationship among a position of a paper discharge roller, a carrying force, and a carrying amount in the automatic document feeder.

FIG. 9 is an explanatory diagram of a separation unit of the automatic document feeder.

FIG. 10 is an enlarged explanatory view of a main part of a separation section of the automatic document feeder.

FIG. 11 is an explanatory diagram of belt pressing and releasing of the separating unit.

FIG. 12 is a view showing a state of the separating section when separating a document.

FIG. 13 is a top view of the separation unit.

FIG. 14 is an enlarged side view of a main part of the separation section.

FIG. 15 is an explanatory diagram of a cam shaft phase switching of the automatic document feeder.

FIG. 16 is an overall schematic view of an image forming apparatus according to the present invention.

FIG. 17 is a diagram showing an internal configuration of a conventional automatic document feeder.

FIG. 18 is a diagram showing operations of a stopper and a half-moon roller at the time of lower separation of a conventional automatic document feeder.

FIG. 19 is a view showing operations of a stopper and a half-moon roller at the time of upper separation of a conventional automatic document feeder.

FIG. 20 is a diagram showing a manner in which a wedge phenomenon occurs in a conventional automatic document feeder.

[Explanation of symbols]

1 Original Tray 3 Shutter 4 Half Moon Roller 4a Conveying Point 14 Paper Ejection Roller 93 Photo Interrupter 151 Control Device A Automatic Document Feeder B Composite Copying Machine C Separator D ₁ Top Paper D ₄ Bottom Paper M1 Half Moon Roller Drive Motor M2 Shutter Drive motor M3 Paper ejection roller drive motor M4 Paper ejection roller drive motor

Claims (6)

[Claims] 1. A sheet for stacking a stack of documents on a slanted document tray, and separating and feeding the documents of the stack of documents one by one from the lowermost part by a separating section provided on the slant side of the document tray. In the paper feeding device, the document is disposed in a document guide part provided between the separating part and the document tray, and the lowermost document of the document stack is locked on the peripheral surface to separate the document from the separating part. And a conveying rotary body driving means for rotating the conveying rotary body, and a retractable conveying body provided between the separating section of the document guide section and the conveying rotary body. A stopper member for preventing the bundle of documents from entering the separating portion due to the inclination of the document tray before the start of feeding; stopper member retracting means for retracting the stopper member in and out of the document guide portion; When feeding the bottom document, After rotating the transport rotating body until the locking portion locks the lowermost document, the transport rotating body driving means and the stopper member retracting means so as to retract the stopper member from the document guide portion. A paper feeding device comprising: a control device for driving and controlling the paper feeding device. 2. A sheet for stacking a stack of documents on a slanted document tray, and separating and feeding the documents of the stack of documents one by one from the uppermost part by a separating section provided on the slant side of the document tray. In the sheet feeding device, the uppermost and lowermost movable parts are provided above a document guide part provided between the separating part and the document tray, and when feeding the uppermost document of the document stack, the document is lowered to the uppermost position. An upper transport rotator that rotates in the document feeding direction after coming into contact with the upper document, an upper transport rotator moving unit that vertically moves the upper transport rotator, and an upper transport rotator that rotates the upper transport rotator. It is provided so as to be retractable between the driving means and the separating section of the document guide section and the upper transporting rotating body, and the document bundle enters the separating section at the inclination of the document tray before the start of feeding. Stopper member for preventing the A stopper member retracting means for retracting a member into and out of the document guide part, and a drive control of the upper transporting rotary body moving means so that the upper transporting rotary body is brought into contact with the uppermost document when feeding the uppermost document. On the other hand, a control device for driving and controlling the upper conveying rotator driving means and the stopper member retracting means so as to retract the stopper member from the document guide portion after rotating the upper conveying rotator. Paper feeding device characterized by. 3. An original stack is stacked on an inclined original tray, and the originals of the original stack are separated one by one from the top or the bottom by a separating unit provided on the inclined side of the original tray. In a paper feeding device for feeding, the document is arranged at a document guide part provided between the separating part and the document tray, and the lowermost document of the document stack is locked on the peripheral surface to convey the document. A transport rotary body having a locking portion for transporting to the separation portion, a transport rotary body drive means for rotating the transport rotary body, and a vertically movable assembly provided above the document guide portion, and the document stack. When feeding the uppermost original, the upper conveying rotary body that descends and contacts the uppermost original and then rotates in the original feeding direction, and the upper conveying rotary body that moves the upper conveying rotary body up and down. Moving means and an upper transporting means for rotating the upper transporting rotating body. A body driving unit, a stopper member that is provided so as to be retractable in the document guide unit and that prevents the document bundle from entering the separation unit due to the inclination of the document tray before starting feeding, and the stopper member. Stopper member retracting means for retracting and retracting in the document guide part, and when feeding the lowermost document, the transport rotating body is rotated until the locking part locks the lowermost document. After that, when the feeding rotary member driving unit and the stopper member retracting unit are drive-controlled so that the stopper member is retracted from the document guiding unit, and when the uppermost document is fed, the upper feeding rotating member is moved. While driving and controlling the upper transporting rotator moving means so as to contact the uppermost document, the stopper member is retracted from the document guide portion after rotating the upper transporting rotator. Paper feeding apparatus characterized by comprising a control device that drives and controls the parts conveying rotating body driving means and the stopper member releasing means, the. 4. A stack of originals is stacked on an inclined original tray, and the originals of the original bundle are separated one by one from the uppermost portion by a separating unit provided on the inclined side of the original tray, and are separated by the original reading unit. In a paper feeding device for feeding, a conveyance rotating body which is arranged in a document guide portion provided between the separating portion and a document tray and conveys the bundle of original documents to the separating portion; A stopper member, which is provided between the separating unit and the conveying rotary member so as to be retractable and retractable, and which prevents the document bundle from entering the separating unit due to the inclination of the document tray before starting feeding, and the document guide. A pressing member that is vertically movable above the unit and that moves downward to press the document bundle against the conveying rotary member when feeding the document bundle; and a pressing member moving unit that moves the pressing member up and down. , The separation section and document reading And a document detection unit that is provided between the document guide unit and the document detection unit that detects that the separated document is fed to the document reading unit. After the evacuation, when the document feeding signal is not input from the detecting means, a control device for driving and controlling the pressing member moving means so as to repeat the pressing operation a predetermined number of times, and Paper equipment. 5. The pressing member is an upper conveyance rotator that rotates in the document feeding direction after descending and contacting the uppermost document when the uppermost document of the document stack is fed. The sheet feeding device according to claim 4, wherein the sheet feeding device is a sheet feeding device. 6. A paper feeding device for feeding a document to a document placing part, and an image forming part for reading a document fed by the paper feeding device and forming an image on a sheet. The image forming apparatus according to claim 1, wherein the sheet feeding device is the sheet feeding device according to any one of claims 1 to 5.