JP2000191169A - Sheet feeder and image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet feeder capable of preventing a feeding failure of overlapped feeding, etc., even against a diversified sheet by providing a separation member not to interrupt returning carriage of sheets carried in a bundle by a separation rotor even while handling and separating a sheet bundle before a retard separation means in the case when a plural number of the sheets are fed in a bundle from a sheet placing means and a image formation device furnished with it. SOLUTION: A pre-separation plate 32 is provided free to revolve around an axis of revolution 32a as its center, and it is constantly urged to a position to project on a carrier passage 31 by a torsion coil spring 33. It is constituted so as to separate pick-up rollers 5, 6, 7 from a sheet S by a link 35 driven by a solenoid 36 and to oscillate a pick-up roller support member 34 and to refuge from the carrier passage 31 by pushing down the pre-separation plate 32 simultaneously.

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 provided in an image forming apparatus such as a copying machine, a printer, and a facsimile.

[0002]

2. Description of the Related Art An example of a conventional sheet feeding apparatus will be described with reference to FIGS. In FIG. 5, the sheet feeding device 10
Reference numeral 1 denotes a pickup roller 103 for feeding the uppermost sheet S one by one from a sheet storage device 102 in which a plurality of sheets S are stacked and stored on a sheet mounting table (not shown).
And the sheet storage device 10 by the pickup roller 103.
2 is fed into the main body of the image forming apparatus (FIG. 5).
Feed roller 104 for transporting in the direction of arrow a), and a retard roller disposed opposite to the feed roller 104.
105, and a pair of transport rollers 106 disposed on the front side of the image forming apparatus main body.

When a plurality of sheets S are fed by the pickup roller 103, the retard roller 105 rotates in the direction opposite to the rotation direction of the feed roller 104 (the direction of the arrow b in FIG. 5) to remove the lower sheet S. The sheet is returned and conveyed, and only the uppermost sheet is separated and fed.

An upper guide 108 is disposed in a sheet passage area 107 between the pickup roller 103, the feed roller 104, and the retard roller 105, and a feed roller
A lower guide 109 is provided between the transport roller pair 106 and the transport roller pair 106 and between the transport roller pair 106 and the image forming apparatus main body. And the upper guide 10
The sheet S is guided and fed by 8 and the lower guide 109.

[0005] Feed roller 104 and retard roller 10
5 is driven by a drive transmission device 110 shown in FIG.
The drive transmission device 110 includes a feed roller shaft 104a on which a feed roller 104 is supported, a retard roller shaft 105a on which a retard roller 105 is supported, and the retard roller shaft 105a.
And a retard roller drive shaft 105b connected to the shaft is arranged substantially in parallel.

As shown in FIG. 5, the retard roller shaft 105a is supported by a support member 111 which can swing about a rotation shaft 111a, and can be moved parallel to and away from the feed roller shaft 104a. A coupling 112 and a torque limiter 113 are provided between the retard roller shaft 105a and the retard roller drive shaft 105b.

At the end of the feed roller shaft 104a, the driving force transmitted from the main drive means of the image forming apparatus main body (not shown) via the drive input belt 114 is fed.
An electromagnetic clutch 115 for transmitting to 4a is provided.

A retard driving belt 116 for transmitting the rotational driving force transmitted to the feed roller shaft 104a to the retard roller driving shaft 105b is wound around the feed roller shaft 104a and the retard roller driving shaft 105b. . still,
The coupling 112 drives the retard roller 105 from the retard roller drive shaft 105b even if the retard roller 105 is displaced.
It is for communicating to 5a.

The driving of the feed roller 104 and the retard roller 105 by the drive transmission device 110 will be described. First, the rotational driving force given from the main driving means of the image forming apparatus main body (not shown) is transmitted to the drive input belt 114, ON / OF according to the feeding timing of the sheet S
The signal is input to a pulley 115a provided at an amateur portion of the electromagnetic clutch 115 to be F-controlled.

Here, the feed roller shaft 104a, the retard roller drive shaft 105b, and the retard roller shaft 105a, which rotate integrally with the rotor portion of the electromagnetic clutch 115, are connected by the retard drive belt 116.
104a, retard roller shaft 105a and retard roller drive shaft
105b rotates in the same direction, and the feed roller 104 and the retard roller 105 are driven to rotate in synchronization with the sheet S feeding timing ON.

When the sheets S are fed one by one in the feeding direction (the direction of the arrow a in FIGS. 5 and 6) by the drive transmission device 110, the retard roller 105 applies a frictional force between the feed roller 104 and the sheet S. As a result, the torque limiter 113 idles and rotates in a direction opposite to the drive rotation direction of the retard roller drive shaft 105b.

When a plurality of sheets S are fed, the frictional force between the plurality of sheets S is smaller than the frictional force between the retard roller 105 and the sheets S. Without idling, the retard roller 105 rotates in the same direction as the rotational drive direction of the retard roller drive shaft 105b.

As a result, the feed roller 104 side of the plurality of fed sheets S, that is, the uppermost sheet S and the lower sheet S are separated from each other, and the sheet S is inserted into the image forming apparatus main body. To prevent double feeding.

Next, the principle of satisfying the condition for separating and feeding the sheet S by the sheet feeding apparatus 101 having the above structure will be described. The following equation shows a relational expression that satisfies the feeding condition, the equation shows the separation condition, and the equation shows the rotation condition of the retard roller 105.

In the following equation, μ _AP is a coefficient of friction between the pickup roller 103 and the sheet S, μ _BP
Is the coefficient of friction between the feed roller 104 and the sheet S, μ _CP is the coefficient of friction between the retard roller 105 and the sheet S, μ _APP is the coefficient of friction between the sheet S under the pressing portion of the pickup roller 103, and μ _BPP is the feed roller 104 And retard roller 10
5 is the coefficient of friction between the sheets S in the nip.

N is the pressing force of the retard roller 105, T is the idling torque of the torque limiter 113, and r
Is the radius of the retard roller 105, and W is the pressing force of the pickup roller 103.

[0017]

(Equation 1)

[0018]

(Equation 2)

[0019]

(Equation 3)

Incidentally, if the same sheet S is used in each of the above equations, the friction coefficient of each roller pressing portion does not vary so much. Therefore, when replacing μ _APP ≒ μ _BPP = μ _PP , Are the following equations, respectively.

[0021]

(Equation 4)

[0022]

(Equation 5)

The relationship between the above expressions is expressed by a retard roller.
FIG. 7 is a graph in which the pressure N of 105 and the idling torque T of the torque limiter 113 are used as parameters. In the figure, a hatched area is an appropriate sheet feeding area A of the sheet S. That is, in order to enlarge the appropriate feeding area A, it is necessary to increase the friction coefficient between each roller and the sheet S or to decrease the pressing force of the pickup roller 103.

Also, it is better to set the feeding condition of the sheet S under such a condition that both the pressing force N of the retard roller 105 and the idling torque T of the torque limiter 113 are increased (upper right direction in FIG. 7). The area A becomes wider.

However, if the idling torque T of the torque limiter 113 is excessively increased, the load torque in driving the roller increases, so that the upper limit (the upper right limit in FIG. 7) of the appropriate feeding area A is also limited to some extent. become.

With the recent increase in the speed of the image forming apparatus main body,
The sheet feeder 101 that supplies the sheet S to the image forming unit is also required to have a higher speed. As a matter of course, the higher the speed, the more difficult it is to secure the reliability of the sheet S feeding performance.

In particular, since the time for picking up the sheet S from the sheet storage device 102 is shortened, the pick-up roller 10
It is necessary to set the transfer force of 3 larger. However, in this case, there is a problem that double feeding is likely to occur.

The reason is that the pick-up roller 103 and the sheet S
There is no choice but to increase the friction coefficient of the pickup roller 103 or increase the pressure of the pickup roller 103.However, it is difficult to greatly change the friction coefficient by changing the material of the pickup roller 103. In many cases, means for increasing the size is used.

However, when the pressure of the pickup roller 103 increases, the uppermost sheet S of the sheet storage device 102
And the frictional force between the lower sheet S and
It becomes difficult to pick up only the top sheet S, and the top sheet S is conveyed while pulling the sheet S below it, and the feed roller 104 and the retard roller
A plurality of sheets S are conveyed in a nip portion with the sheet 105.

The bundle of sheets S is separated one by one by the reverse rotation of the retard roller 105. However, if too many sheets S enter in a bundle at the same time, the separation capacity limit will be exceeded and multifeed will be performed. . In particular, recently, various kinds of sheets S exist, and depending on the type of the sheets S, there is a sheet S having a friction coefficient much larger than usual.

Therefore, in the conventional sheet feeding apparatus 101, as shown in FIG. 5, the feed roller 104 and the retard roller 105 are located downstream of the sheet storage apparatus 102 in the sheet feeding direction (hereinafter, simply referred to as "downstream side"). Upstream of the nip portion in the sheet feeding direction (hereinafter simply referred to as “upstream”)
And a pre-separation plate 118 which protrudes above the conveyance path 117 of the sheet S fed by the pickup roller 103 and abuts on the sheet S to separate the sheet S.

The pre-separation plate 118 is a pickup roller 103
When a plurality of sheets S are fed, the leading end of the sheet S bundle is brought into contact with the pre-separation plate 118 on the front side of the retard separation mechanism consisting of the original feed roller 104 and the retard roller 105 to position the leading end. By displacing them, they can be easily separated to some extent.

However, the transport path 11 of the pre-separation plate 118
If the protrusion amount to the sheet S and the contact angle to the sheet S are increased, the feed roller 104 and the retard roller 105 may not be able to be fed by the pickup roller 103.
However, it is not possible to expect the effect of completely preventing the sheet S bundle from entering the nip portion, and it is merely an auxiliary of the original retard separating mechanism including the feed roller 104 and the retard roller 105. In addition to the sheet S having extremely poor separation properties, a sufficient effect can be obtained by combining with the retard separation mechanism.

[0034]

However, in the above-mentioned conventional example, the sheet S having extremely poor separability or the sheet S having high rigidity cannot be separated by the pre-separation plate 118, and the feed roller 104 and the retard roller When the sheet enters the nip portion with the sheet 105, the sheet S on the retard roller 105 side is returned and conveyed by the reverse rotation of the retard roller 105. There is a problem that performance is reduced.

The present invention solves the above problems,
The purpose thereof is that, when a plurality of sheets are fed as a bundle from the sheet placing means, the sheets are separated and conveyed by the separating rotary body while separating and separating the sheet bundle before the retard separating means. By providing a separating member that does not hinder return conveyance of a sheet, it is possible to provide a sheet feeding apparatus and an image forming apparatus having the same that can prevent a feeding failure such as double feeding even for diversified sheets. Is what you do.

[0036]

A typical configuration according to the present invention for achieving the above object is to provide a sheet placing means for placing a sheet, and to supply a sheet placed on the sheet placing means. A sheet feeding unit for feeding, a conveying rotator disposed downstream of the sheet feeding unit in the sheet feeding direction, and conveying the sheet fed by the sheet feeding unit; And a separation rotator that separates the sheet by the cooperative action with the conveyance rotator, and a sheet rotation direction downstream of the sheet placing unit, and the conveyance rotator and the separation rotator. A separating member that is disposed upstream of the nip portion in the sheet feeding direction, protrudes on a conveyance path of a sheet fed by the sheet feeding unit, and separates the sheet by contacting the sheet; By the sheet feeding means. A projecting position to project on the conveying path of the sheet to be fed, a sheet feeding apparatus characterized by having a moving means for moving into a retracted position retracted from the transport path.

According to the present invention, as described above, the projecting position at which the separating member is projected by the moving means onto the conveying path of the sheet fed by the sheet feeding means, and the retracting position at which the sheet is retracted from the conveying path. When a plurality of sheets are fed as a bundle from the sheet placing means by moving the sheet separating means, the separating member is placed on the conveying path of the sheet fed by the sheet feeding means before the retard separating means. When the sheet bundle is separated and separated by holding the sheet at the projecting position where the sheet is to be projected, and when the sheet conveyed by the separation rotating body is returned, the sheet is conveyed to the retreat position where it is retracted from the conveyance path. Not hinder.

As a result, it is possible to prevent defective feeding such as double feeding even for diversified sheets.

[0039]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, an embodiment in which the present invention is applied to a copying machine as an example of a sheet feeding apparatus according to the present invention and an image forming apparatus provided with the same will be specifically described. FIG.
2 is an explanatory cross-sectional view illustrating a configuration of an image forming apparatus provided with a sheet feeding device according to the present invention, and FIG. 2 is an enlarged view of a main part illustrating a configuration of a first embodiment of the sheet feeding device according to the present invention.

Referring to FIG. 1, an image forming apparatus provided with a sheet feeding apparatus according to the present invention has a large number of sheets S made of paper, synthetic resin, or the like stacked and housed on one side of an image forming apparatus main body 1. In addition to a sheet feeding deck 2 serving as a sheet placing unit, a plurality of sheet cassettes 3 and 4 also serving as a sheet placing unit are provided at a lower portion in the image forming apparatus main body 1 and have a predetermined amount of sheets S stacked therein. I have.

Pickup rollers 5, 6, and 7 serving as sheet feeding means and constituting a retard separating mechanism are provided at the positions where the sheet feeding deck 2 and the sheet cassettes 3 and 4 for feeding the sheet S are provided. Feed rollers 8, 9, and 10 serving as rotating bodies and retard rollers 11, 12, and 13 serving as separating rotating bodies are provided.

The sheet feeding deck 2, the sheet cassettes 3,
The sheets S in 4 are pickup rollers 5, 6, 7 respectively.
After being separated by being separated by being brought into contact with a pre-separation plate 32 serving as a separation member which will be described in detail later with reference to FIG. 2, the feed rollers 8, 9, 10 and the retard roller 1
The skewed state is corrected by being sent to the registration roller pair 14 that has been separated and fed by the first, second, and thirteen and is temporarily stopped.

On the other hand, when a document image is read by the image reading device 15 and a laser beam corresponding to the image information is irradiated on an electrophotographic photosensitive drum 16 serving as an image forming means, an electrostatic latent image is formed and developed. The toner is supplied by the machine 17 to form a toner image.

The sheet S is fed between the photosensitive drum 16 and the transfer charger 18 facing the photosensitive drum 16 by a pair of registration rollers 14 rotating at a timing with respect to the electrostatic latent image formed on the photosensitive drum 16. Then, the toner image on the photosensitive drum 16 is transferred to the sheet S by the operation of the transfer charger 18.

Thereafter, the sheet S is sent to the fixing device 20 by the transport belt 19, where the sheet S is heated and pressed, and the toner image transferred to the sheet S is permanently fixed. The image forming apparatus main body 1 is provided with a duplex copying mode for performing duplex copying on the sheet S and a multiplex copying mode for performing multiple copying. In the normal copying mode, the sheet S after the fixing process is applied to the inner discharge roller pair.
The paper is discharged onto a discharge tray 22 outside the machine by the device 21.

In the case of the double-sided copy mode and the multiple copy mode, the pair of inner discharge rollers 23 or the pair of switchback rollers 24 temporarily place the sheet on the intermediate tray 27 via the re-feeding path 25 and the double-sided conveying path 26. It is loaded and accommodated.

Then, the sheet S accommodated on the intermediate tray 27 is again conveyed to the registration roller pair 14 by the re-feeding device 28, and an image is formed through the same process as the one-sided copying, and is discharged out of the apparatus. You.

FIG. 2 is a diagram showing a main part around the retard separation mechanism. In FIG. 2, sheets S placed on a sheet feeding deck 2 and sheet cassettes 3 and 4 serving as sheet loading means are fed out by pickup rollers 5, 6, and 7 serving as sheet feeding means, respectively. Feed rollers 8, 9, 10 which are disposed on the downstream side in the sheet feeding direction (hereinafter, simply referred to as "downstream side") with respect to 5, 6, 7, and 7 and serve as a conveying rotating body;
The sheet cassettes 3 and 4 are separated and fed one by one through a pair of conveying rollers 29 and 30, respectively, in cooperation with retard rollers 11, 12 and 13 serving as separating rotating bodies disposed opposite to each other. It is sent to the roller pair 14 and the sheet feeding deck 2
Is sent directly to the registration roller pair 14.

The structure of the driving system of the feed rollers 8, 9, 10 and the retard separating mechanism of the retard rollers 11, 12, 13 is substantially the same as that of the conventional example shown in FIG. .

The sheet feeding deck 2, the sheet cassette 3,
4 and on the upstream side in the sheet feeding direction (hereinafter simply referred to as “upstream side”) from the respective nips between the feed rollers 8, 9, 10 and the retard rollers 11, 12, 13. A pre-separation plate 32 is provided, which protrudes onto the conveyance path 31 of the sheet S fed by the pickup rollers 5, 6, and 7 and serves as a separation member that comes into contact with the sheet S and separates the sheet S.

The pre-separation plate 32 is itself a rocking means and is provided rotatably about a rotation shaft 32a. The pre-separation plate 32 is biased by a torsion coil spring 33 to a projecting position which always projects on the transport path 31. Is held. On the other hand, the pickup rollers 5, 6, 7 are rotatably supported by a pickup roller support member 34, which is a swinging means rotatable around the feed roller shafts 8a, 9a, 10a of the feed rollers 8, 9, 10. The sheet S placed on each of the sheet feeding deck 2 and the sheet cassettes 3 and 4 is brought into contact with a predetermined pressing force by a pressing means (not shown).

At a position where the pre-separation plate 32 and the pickup roller support member 34 are brought into contact with each other, a link 35 that is rotatable about a rotation shaft 35 a is provided. One end of the link 35 is connected to a solenoid 36. Are linked.

The projecting position at which the pre-separation plate 32 is projected onto the conveying path 31 by the solenoid 36 and the link 35, and the conveying path
31 constitutes a moving means for moving to an evacuation position for evacuation from above.

Then, the solenoid 36 is turned on and the link is established.
When the link 35 is rotated clockwise in FIG. 2 around the rotary shaft 35a, one end of the link 35 is connected to the pickup roller support member.
The pickup roller supporting member 34 is rotated in a counterclockwise direction in FIG. 2 around the feed roller shafts 8a, 9a, and 10a against the pressing force of a pressing means (not shown). The sheet is separated from the sheet S placed on the sheet feeding deck 2 and the sheet cassettes 3 and 4.

At the same time, the other end of the link 35 comes into contact with the upright piece of the pre-separation plate 32 to move the pre-separation plate 32 to the rotating shaft 32a.
2 is rotated counterclockwise in FIG. 2 against the urging force of the torsion coil spring 33 and retracted from the transport path 31.

In the above configuration, when the sheets S loaded on the sheet feeding deck 2 or the sheet cassettes 3 and 4 are fed, the pickup rollers 5, 6, and 7 are moved to the uppermost position as shown by the solid line in FIG. It is in contact with the surface of the sheet S.

In this state, the pre-separation plate 32, which is swingably supported, is urged by the torsion coil spring 33 to the projecting position shown by the solid line in FIG. When a plurality of sheets S are picked up in a bundle by the pickup rollers 5, 6, 7 when the coefficient of friction between the sheets S is large or when the pressing force of the pickup rollers 5, 6, 7 is large. The leading end of the S bundle comes into contact with the pre-separation plate 32 and is loosened.
The sheet S is conveyed to the respective nip portions of the feed rollers 8, 9, 10 and the retard rollers 11, 12, 13 through 1 '.

When the leading end of the sheet S is nipped by the feed rollers 8, 9, and 10 and the retard rollers 11, 12, and 13, respectively, the solenoid 36 is activated, and the link 35 causes the pickup roller support member 34 to move as shown in FIG. The pickup rollers 5, 6, 7 are retracted from the feeding position by being lifted to the separated position indicated by the broken line.

At the same time, the pre-separation plate 32 is
2 is also moved to the retreat position indicated by the broken line in FIG.
Even if the pre-separation plate 32 retreats from the transport path 31 even if the bundle enters the nip portion of each of the retard rollers 11, 12 and 13, the retard rollers 11, 12 and 13 rotate backward and It does not hinder the return conveyance of the sheet S.

As described above, during the pick-up operation in which the pick-up rollers 5, 6, 7 which start the feeding operation according to the conveying state of the sheet S, the pre-separation plate 32 is moved along the conveying path 31.
When the retard rollers 11, 12, and 13 are rotated backward and the lower sheet S is returned and conveyed, the pre-separation plate 32 is retracted from the conveyance path 31 during the retard separation operation, so that the probability of occurrence of double feeding is reduced. Can be done.

Next, a second embodiment of the sheet feeding apparatus according to the present invention will be described with reference to FIGS. FIG. 3 is an enlarged view of a main part showing a configuration of a sheet feeding apparatus according to a second embodiment of the present invention, and FIG. 4 is a perspective explanatory view showing a configuration of moving means for moving a separating member in the second embodiment. still,
Components configured in the same manner as in the first embodiment are given the same reference numerals and description thereof is omitted.

In the first embodiment, the pre-separation plate 32 is always swung in conjunction with the separating operation of the pickup rollers 5, 6, and 7 from the sheet S, but in the present embodiment, the retard rollers 11 and The conveyance state of the sheet S is detected based on the rotation directions of the sheets 12 and 13, and the pre-separation plate 32 is automatically swung.

As in the first embodiment, the pre-separation plate 32 serving as a separation member is pivotally supported so as to be pivotable about a rotation shaft 32a, and is moved to a retracted position indicated by a broken line in FIG. Being energized.

On the side where the pre-separation plate 32 is urged by the torsion coil spring 33, a protruding position where the pre-separation plate 32 is brought into contact with the pre-separation plate 32 to protrude onto the transport path 31.
A cam 41 is provided as a moving means for moving to a retreat position to retreat from the transport path 31.

As shown in FIG. 4, the rotating shaft 41a of the cam 41 is connected to the retard roller shafts 11a, 12a and 13a via a torque limiter 42 and a gear train 43. When the retard rollers 11, 12, and 13 follow the feed rollers 8, 9, and 10, the cam 41 causes the pre-separation plate 32 to protrude above the transport path 31 as shown by the solid line in FIG. Hold.

The pre-separation plate 32 does not swing beyond the projecting position shown by the solid line in FIG. 3 by abutting against a striking member (not shown), and the cam 41 also rotates as shown in FIG. The torque limiter 42 and the stopper 44 provided on the 41a are configured to be rotatable within the range of the broken line and the solid line shown in FIG.

When the sheet S is fed, first, the pickup rollers 5, 6, and 7 are moved to the uppermost sheet S loaded on the sheet feeding deck 2 and the sheet cassettes 3, 4 as shown by the solid line in FIG. Is in contact with

Then, the first feeding operation, or the case where the pickup rollers 5, 6, 7 are feeding only one sheet S to the nip portion between the feed rollers 8, 9, 10 and the retard rollers 11, 12, 13 Are retard roller shafts 11a and 12
The pre-separation plates a and 13a are driven to rotate with respect to the feed rollers 8, 9 and 10, and the cam 41 is swingably supported via a gear train 43 supported by retard roller shafts 11a, 12a and 13a. 32 is urged to the projecting position shown by the solid line in FIG.

When the coefficient of friction between the stacked sheets S is large or when the pressing force of the pickup rollers 5, 6, 7 is large, the sheet feeding deck 2 or the sheet Cassette 3, 4
When a plurality of sheets S are picked up in a bundle, the leading edge thereof contacts the pre-separation plate 32 and is loosened by the pre-separation plate 32, and exceeds the upper end of the pre-separation plate 32 above the transport path 31. Feed rollers 8, 9,
Sheet S at the nip between the roller 10 and the retard rollers 11, 12, 13
Is transported.

When the leading end of the sheet S is nipped by the feed rollers 8, 9, and 10 and the retard rollers 11, 12, and 13, the solenoid 36 is operated, and the link 35 causes the pickup roller support member 34 to move as indicated by a broken line in FIG. The pickup rollers 5, 6, and 7 are separated from the sheet S and retracted from the feeding position.

Then, the sheet S bundle is not completely separated by the pre-separation plate 32 and the feed rollers 8, 9, 10 and the retard roller 1
When the bundle enters the nip portion between the feed rollers 1, 12, and 13, the retard roller shafts 11a, 12a, and 13a are connected to the feed rollers 8, 9,
10 and rotates in reverse with respect to the retard roller shafts 11a, 12a,
The cam 41 is a pre-separation plate via a gear train 43 supported by 13a.
32 is moved to the retracted position shown by the broken line in FIG.

As a result, since the pre-separation plate 32 is lower than the original conveyance path 31, the retard rollers 11, 12,
13 does not hinder when the lower sheet S is rotated backward to convey a plurality of lower sheets S taken in.

Further, even if a plurality of sheets S are conveyed to the nip portion between the feed rollers 8, 9, and 10 and the retard rollers 11, 12, and 13 in the preliminary feeding operation, and the pre-separation plate 32 is at the retracted position. In the next feeding operation, the sheet S
If only one sheet has been conveyed, the pre-separation plate 32 returns to the protruding position again.
32 does not hinder the return conveyance of the sheet S taken in by the reverse rotation of the retard rollers 11, 12, and 13 in the retracted position.

As described above, the retard separating mechanism of the feed rollers 8, 9, and 10 and the retard rollers 11, 12, and 13 of the sheet feeding device always performs the retard separating operation.
The protrusion 32 is protruded when necessary, and is retracted so as not to hinder the retard separation operation, so that the occurrence probability of double feed can be reduced.

[0075]

Since the present invention has the above-described configuration and operation, the separation member is movably supported in a retard separation type sheet feeding apparatus using a conveying rotating body and a separating rotating body so as to be separated. By allowing the separating member to function when the separating operation is necessary, and by retracting the separating member so that it does not hinder the retard separating operation, both the separating operation by the separating member and the retard separating operation can be fully performed. Thus, the probability of occurrence of double feed can be reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory cross-sectional view illustrating a configuration of an image forming apparatus including a sheet feeding device according to the present invention.

FIG. 2 is an enlarged view of a main part showing a configuration of a sheet feeding device according to a first embodiment of the present invention.

FIG. 3 is an enlarged view of a main part showing a configuration of a second embodiment of the sheet feeding apparatus according to the present invention.

FIG. 4 is a perspective explanatory view illustrating a configuration of a moving unit that moves a separation member in a second embodiment.

FIG. 5 is a diagram illustrating a conventional example.

FIG. 6 is a diagram illustrating a conventional example.

FIG. 7 is a diagram illustrating a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus main body, 2 ... Sheet feeding deck, 3, 4
... Sheet cassettes, 5, 6, 7 ... Pickup rollers,
8, 9, 10: feed roller, 8a, 9a, 10a: feed roller shaft, 11, 12, 13: retard roller, 11a, 12
a, 13a: retard roller shaft, 14: registration roller pair,
15 ... Image reading device, 16 ... Photoconductor drum, 17 ... Developing machine, 18
... Transfer charger, 19 ... Conveyer belt, 20 ... Fixer, 21 ... Inner discharge roller pair, 22 ... Discharge tray, 23 ... Inner discharge roller pair, 24
… Switchback roller pair, 25… Refeed path, 26… Double-sided conveyance path, 27… Intermediate tray, 28… Refeed device, 29, 30…
Transport roller pair, 31: transport path, 32: pre-separation plate, 32a ...
Rotating shaft, 33: torsion coil spring, 34: pickup roller support member, 35: link, 35a: rotating shaft, 36: solenoid, 41: cam, 41a: rotating shaft, 42: torque limiter, 43
... gear train, 44 ... stopper, S ... seat

Claims (6)

[Claims] 1. A sheet mounting means for mounting a sheet, a sheet feeding means for feeding a sheet mounted on the sheet mounting means, and a downstream side of the sheet feeding means in a sheet feeding direction. And a conveying rotating body that conveys the sheet fed by the sheet feeding means; and a separating rotation that is arranged to face the conveying rotating body and separates the sheet by the cooperation of the conveying rotating body. And a body, disposed downstream of the sheet placement unit in the sheet feeding direction, and upstream of a nip between the transport rotator and the separation rotator in the sheet feeding direction, and provided by the sheet feeding unit. A separating member that protrudes on the conveying path of the fed sheet and separates the sheet by contacting the sheet; and a protruding position that protrudes the separating member onto the conveying path of the sheet fed by the sheet feeding unit. And the transport route Sheet feeding apparatus characterized by having, a moving means for moving into a retracted position retracted from. 2. The method according to claim 1, wherein the separating member is moved to a projecting position for projecting the sheet fed by the sheet feeding unit on a conveying path according to a sheet conveying state, and to a retreating position for retreating from the conveying path. The sheet feeding device according to claim 1, wherein the sheet is fed. 3. The sheet feeding means is brought into contact with / separated from a sheet placed on the sheet placing means by a first swing means, and the sheet separating means is fed by a second swing means. The sheet is protruded / retracted on a conveyance path of the sheet fed by the feeding means, and the separating member is retreated from the conveyance path of the sheet in conjunction with the separating operation of the sheet feeding means from the sheet. The sheet feeding device according to claim 1. 4. When the separation rotator rotates in reverse with respect to the conveyance rotator, the separation member is retracted from a sheet conveyance path, and when the separation rotator is driven by the conveyance rotator, The sheet feeding device according to claim 1, wherein the separation member protrudes on a sheet conveyance path. 5. The separation member is protruded / retracted by a rocking means on a conveyance path of a sheet fed by the sheet feeding means, and when the separation rotating body rotates reversely with respect to the conveyance rotating body, The sheet feeding device according to claim 4, wherein a cam interlocked with the rotation of the separation rotator retracts the separation member from a sheet conveyance path. 6. An image forming apparatus comprising: the sheet feeding device according to claim 1; and an image forming means for forming an image on a sheet according to image information.