JPH09202467A - Sheet feed device and sheet treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To separate the sheet one by one even when a curl or a folding is present on a tip of the sheet delivered from a sheet loading part without fouling the sheet delivered from the sheet loading part. SOLUTION: The sheet S to be delivered by a delivering roller 2 to be rotated counterclockwise in the figure is carried downstream by a carrying roller 3 to be rotated counterclockwise. Surplus sheets (other sheets than the highest sheet) delivered by the delivering roller 2 are returned upstream by a separation roller 4 to be rotated counterclockwise. The carrying roller 3 and the separation roller 4 suck the sheet S with the suction force of air and carry it. The carrying roller 3 and the separation roller 4 are opposite to each other with the specifies distance therebetween. The distance is temporarily set to 2-5 times the thickness of the sheet S. The suction force P1 of the carrying roller 3 and the suction force P2 of the separation roller are set to satisfy the inequality of P1>P2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding apparatus provided in a sheet processing apparatus such as a copying machine, a printer, a facsimile and a scanner. The sheet processing apparatus referred to here is a generic term for an apparatus having a sheet processing unit that performs a predetermined process (for example, image formation, image reading, etc.) on sheets fed one by one. doing.

[0002]

2. Description of the Related Art Sheet processing apparatuses such as copying machines, printers, and facsimiles are equipped with a sheet feeding apparatus for feeding sheets stacked in a sheet stacking unit one by one.

This sheet feeding device has a function of feeding out the sheets stacked in the sheet stacking portion in order from the topmost or the bottommost sheet, separating the fed-out sheets one by one, and conveying them downstream. doing.

There are various types of sheet separating means provided in the sheet feeding apparatus, and here, two typical conventional methods are listed.

(1) Retard Separation System This system is composed of a transport roller for transporting the delivered sheet downstream and a separation roller (retard roller) for returning the delivered sheet to the sheet stacking section.
Drive is transmitted to the separation roller via a torque limiter.

When one sheet enters between the opposing conveying roller and separating roller (nip), the torque limiter slips and the separating roller rotates following the conveying roller. When the sheet enters, the torque limiter does not slip and the separation roller reversely rotates to return the sheets other than the uppermost or the lowermost sheet to the sheet stacking unit.

In this case, the sheets are separated one by one according to the difference between the friction coefficient between each roller and the sheet and the friction coefficient between the sheets.

(2) Air Separation Method In this method, the sheets stacked in the sheet stacking section are attracted to the conveyor belt (endless belt), which is the sheet conveying means, by the suction force of air, and the sheets are adsorbed to the conveyor belt. Blow air between the 1st and 2nd sheets to 2
The second and subsequent sheets are peeled from the first sheet (separation), and only the first sheet is conveyed downstream by the conveyor belt.

Here, the conveyor belt is arranged at a position facing the sheets on the sheet stacking portion. Innumerable suction holes are formed on the belt surface of the transport belt, and the air suction means sucks a plurality of sheets on the sheet stacking unit through the suction holes. In addition, a gap is formed on the leading end side of the first sheet and the second sheet adsorbed on the conveyor belt. When air is blown into this gap, the second and subsequent sheets are the first sheet. Stripped from the sheet.

[0010]

However, in the case of the retard separation system, there is a problem that a plurality of sheets in the nip between the transport roller and the separation roller rub against each other and become dirty. Further, since the separation roller repeats normal rotation and reverse rotation in a state in which the separation roller is in contact with the conveyance roller at a predetermined pressure, there is a problem that it is easily worn.

Further, in the case of the above air separation system, if a sheet having a curl or a fold at the tip of the sheet is used,
There is a problem that it is difficult to blow air between the first sheet and the second sheet, the second and subsequent sheets do not separate from the first sheet, and the separation performance deteriorates. Further, in the sheet stacking unit, it is necessary to regulate the rear end position of the sheets so that the sheets are not blown off by the force of air sucking the sheets. For this reason, it is not possible to mix sheets with different sizes in the transport direction in the sheet stacking unit. There was also a problem that only sheets of the same size could be fed.

Therefore, the present invention has been made in view of the above circumstances, and an object of the present invention is to provide a sheet feeding apparatus which does not stain a sheet or lower the separation performance.

[0013]

SUMMARY OF THE INVENTION The present invention relates to a sheet feeding device for separating and transporting sheets stacked in a sheet stacking unit one by one.

In order to achieve the above object, the present invention provides a sheet conveying means for adsorbing and conveying the sheets stacked in the sheet stacking section by the suction force of air, and an extra sheet fed out from the sheet stacking section. And a sheet separating unit that sucks and separates the sheet by the suction force of air.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. <First Embodiment> FIG. 1 shows a structural example (1) of a sheet feeding apparatus of the present invention.

The sheet feeding apparatus 100A has a feeding roller 2 for feeding sheets S stacked on a stacking tray (deck) 1 in order from the uppermost sheet, and a feeding roller 2 for the same.
The conveyance roller 3 that adsorbs and conveys the sheet S fed by the air suction force, and the feeding roller 2 that adsorbs the fed sheet other than the uppermost sheet (double-fed sheet) by the air suction force. And a separating roller 4 for separating. The transport roller 3 and the separation roller 4 face each other with a predetermined distance. That is, the transport roller 3 and the separation roller 4 form a non-contact roller pair.

FIG. 2 shows the structure of the conveying roller 3 and the separating roller 4. Drive from a drive source (not shown) is transmitted to the roller shaft 5 of the transport roller 3 and the roller shaft 6 of the separation roller 4. As shown in FIG. 2B, the drive from the drive source is transmitted to the gear 8 via the electromagnetic clutch 7 and to the roller shafts 5 and 6 via the gears 9 and 10 meshing with the gear 8. Further, the driving of the roller shaft 5 is transmitted to the roller shaft 12 of the feeding roller 2 via the endless belt 11.

The roller shafts 5 and 6 of the conveying roller 3 and the separating roller 4 are hollow shafts. Pipes 15 and 16 connected to a vacuum pump VP (not shown) are connected to one ends of the roller shafts 5 and 6 via highly airtight couplings 13 and 14, respectively. Therefore, when the vacuum pump VP is turned on, the inside of the roller shafts 5 and 6 is in a negative pressure state. The other ends of the roller shafts 5 and 6 are closed. A large number of holes 17 and 18 communicating with the inside of the roller shafts 5 and 6 are formed on the outer circumferences of the conveying roller 3 and the separating roller 4. Therefore, when the roller shafts 5 and 6 are in a negative pressure state, an air suction force is generated on the outer peripheral surfaces of the transport roller 3 and the separation roller 4.

In this case, the suction force P1 of the transport roller 3 and the suction force P2 of the separation roller 4 are set to have a relationship of P1> P2. The range in which the suction forces P1 and P2 act on the sheet S is the range indicated by the arrow X in FIG.

The feeding roller 2 is supported on the tip end side of a support member 19 mounted on the roller shaft 5 so as to be rotatable in the vertical direction about the roller shaft 5. The feeding roller 2 is provided with the link mechanism 20.
The pickup operation is performed by the solenoid 21 connected via the.

The stacking tray 1 can be moved up and down by an elevator mechanism (not shown). When the sheets S are stacked on the stack tray 1, the tray 1 is lowered to a predetermined position and the sheets S are stacked. After stacking the sheets S,
The driven lifting mechanism automatically stops driving when the uppermost sheet reaches a predetermined height.

Incidentally, reference numeral 22 in FIG.
It is a pair of conveyance rollers (a pair of drawing rollers) that conveys the sheet S conveyed by the downstream.

Next, the operation of the sheet feeding apparatus 100A will be described with reference to FIG.

First, the sheets S are stacked on the tray 1 and the lifting mechanism is driven. In this way, the tray 1 is raised and stopped when the top surface of the uppermost sheet S1 reaches a predetermined position by a tray height sensor (not shown). At this time,
The solenoid 21 is on, and the roller 2 is not in contact with the uppermost sheet S1.

When the carrying operation is started, the vacuum pump V
P is turned on, and a negative pressure is applied to the transport roller 3 and the separation roller 4. When the electromagnetic clutch 7 is turned on,
The drive from the drive source is transmitted to the roller shafts 5 and 6, and the feeding roller 2, the transport roller 3, and the separation roller 4 start rotating.
At this time, the rotation direction is the feeding roller 2, the conveying roller 3,
Both the separation rollers 4 are in the counterclockwise direction.

When the solenoid 21 is turned off, the feeding roller 2 descends onto the uppermost sheet S1 (state shown in FIG. 1) to feed the sheet S. Then, after a certain time, the solenoid 21 is turned on again, and the feeding roller 2 is separated from the sheet S.

Two sheets S are fed by the feeding roller 2.
When 1 and S2 are fed, the uppermost sheet S1 is attracted to the transport roller 3. The one sheet S2 is not adsorbed to the conveyance roller 3 because the sheet S1 has blocked the adsorption portion of the conveyance roller 3, and is adsorbed to the separation roller 4 rotating in the direction opposite to the sheet conveyance direction. Sheet S1
And the sheet S2 are separated. Then, the sheet S1 attracted to the transport roller 3 is transported downstream without being wrapped around the transport roller 3 due to the waist force of the sheet S1 itself and the curvature of the transport roller 3. In this way, only one sheet is conveyed downstream.

The suction force P1 of the transport roller 3> the suction force P2 of the separation roller 4 is set so that the sheet S1 is not attracted to the separation roller 4.

The conveying roller 3 and the separating roller 4 are both suction rollers, and can be constructed in a non-contact manner so that the sheet is conveyed and separated by the suction force, but the optimum gap between the rollers is the thickness of the sheet to be conveyed and the suction. It depends on the forces P1 and P2. Generally, a gap of about 2 to 5 times the thickness of the sheet S is suitable. When the sheet S is made of a thin material such as paper or film, the gap between the rollers is preferably about 1 to 10 mm in consideration of curling and bending.
However, even when the sheet S is made of a thin material, it is appropriate that the gap between the rollers is about 1 to 5 mm if curling or bending is not necessary to be considered.

Here, when the conveyance of the sheet S1 is completed, in order to prevent the conveyance roller 3 from continuously adsorbing and conveying the sheet S2, the rear end of the sheet S1 may be removed from the conveyance roller 3. When detected by a sensor (not shown), the electromagnetic clutch 7 is turned off and the drive transmission to the transport roller 3 and the separation roller 4 is stopped. As a result, the sheet S1 is conveyed downstream by the conveying roller pair 22, and the sheet S2 is not conveyed. Even if the sheet S2 is dragged by the sheet S1, the sheet S2 is attracted to the conveyance roller 3 and the separation roller 4 which are not rotating, and is not sent further downstream.

When the sensor (not shown) detects that the rear end of the sheet S1 has reached the pair of conveying rollers 22, the vacuum pump VP is turned off, and the conveying operation is completed. However, during the continuous transport operation, the vacuum pump VP is turned off after transporting a predetermined number of sheets, and the transport operation ends. <Second Embodiment> In the case of the sheet feeding device 100A, when the suction force P1 of the conveying roller 3 is stronger than the waist force of the sheet S1 such as the sheet S1 is thin material, the sheet S1 is the conveying roller 3 There is a fear of being wrapped around. In order to avoid such a situation, in the sheet feeding apparatus 100B of the configuration example (2) shown in FIG. 4, the auxiliary separating means 23 is attached to the conveying roller 3.

In this case, as shown in FIG. 4, the auxiliary separating means 2
When 3 is in contact with the transport roller 3, it causes wear of the transport roller 3. Therefore, as shown in FIG. 5, by providing the auxiliary separating means 23 so as not to contact the transport roller 3 and to extend from the outer diameter outer side to the outer diameter inner side of the transport roller 3 in the transport region of the sheet S. It is possible to separate the sheet S1 and the transport roller 3 without causing wear of the transport roller 3. <Third Embodiment> In the case of the sheet feeding apparatus 100A of the first embodiment, the guide plate 24A for guiding the sheet S fed by the feeding roller 2 to the nip between the conveying roller 3 and the separating roller 4 is provided on the tray 1. Although the sheet stacking surface 1A has a shape (horizontal state) substantially parallel to the sheet stacking surface 1A, in the sheet feeding device 100C of the configuration example (3) shown in FIG. The shape is inclined at a predetermined angle.

Next, the operation of the guide plate 24B will be described with reference to FIG.

When the feeding operation starts, the feeding force is applied to the uppermost sheet S1 of the sheets S stacked by the feeding roller 2 and the sheet S1 is fed. At this time, when a plurality of sheets S1, S2, S3 are delivered by the delivery roller 2, the plurality of sheets S1, S2, S3 abut the guide plate 24B, bend and head toward the nip between the transport roller 3 and the separation roller 4. . The leading ends of the sheets S1, S2, S3 that have abutted against the guide plate 24B and are bent are separated and separated one by one. Therefore, the separation roller 4
Separation performance is improved by. <Fourth Embodiment> In the case of the sheet feeding apparatus 100C, the gap between the conveying roller 3 and the separating roller 4 is constant, but the sheet feeding of the configuration example (4) shown in FIG. In the apparatus 100D, the separation roller 4 is attached so that the gap between the transport roller 3 and the separation roller 4 can be changed.

That is, the separation roller 4 is attached to the front end side of the support member 26 which is rotatable about the support shaft 25 in the vertical direction. The support member 26 is a coil spring 27.
Is urged clockwise by the separating roller 4
Are arranged at a position separated from the transport roller 3 by a predetermined distance. At this time, the setting position of the separation roller 4 is adjusted by the adjusting screw 28.
Can be changed by

If the setting position of the separation roller 4 is changed, the gear 10 on the roller shaft 6 will not mesh with the gear 8. In order to eliminate such a thing, here, as shown in FIG. 9, a part of the roller shaft 6 is formed by a flexible and highly airtight hollow joint member 29.

When configured in this way, one sheet S
Even when the thickness of the separation roller 4 is larger than the gap between the conveyance roller 3 and the separation roller 4, the separation roller 4 can move in the direction away from the conveyance roller 3, so that the gap between the conveyance roller 3 and the separation roller 4 is Can be changed. <Fifth Embodiment> In the sheet feeding device 100E of the configuration example (5) shown in FIG. 10, the feeding roller 2 and the conveying roller 3 used in the sheet feeding device 100A of the first embodiment are replaced. The endless conveyor belt 30 is used instead.

A large number of air suction holes (not shown) are formed on the entire belt surface of the conveyor belt 30, and these air suction holes communicate with the air suction opening 31 in the belt. A vacuum pump VP (not shown) is connected to the air suction opening 31. Vacuum pump V
When P is turned on, the air suction opening 31 is in a negative pressure state, and an air suction force is generated on the belt surface of the conveyor belt 30.

The conveyor belt 30 can be moved up and down by a solenoid 21 connected through a link mechanism 20.

Next, the operation of the sheet feeding apparatus 100E will be described.

When the feeding operation starts, the vacuum pump V
P operates, the separation roller 4 and the inside of the air suction opening 31 are in a negative pressure state, and an air suction force is generated in the separation roller 4 and the conveyance belt 30.

The uppermost sheet S1 of the stacked sheets S
Is attracted to the belt surface by the suction force of the transport belt 30. When the clutch (not shown) is turned on, the shaft 32 and the shaft 6
The driving force is transmitted to the conveyance belt 30 and the separation roller 4 rotate counterclockwise, and the sheet S1 is conveyed downstream.

At this time, when the solenoid 21 is turned on, the link mechanism 20 causes the conveyor belt 30 to rotate upward about the shaft 32 as shown by the dotted line, and conveys the sheet S1 while separating it from the sheet S2. go. When the sheet S1 reaches the conveying roller pair (not shown) by a sensor (not shown), the clutch (not shown) is turned off, the conveying belt 30 and the separation roller 4 stop rotating, and the sheet S1 is conveyed by the conveying roller pair. It When the rear end of the sheet S1 passes through the pair of conveying rollers by a sensor (not shown), the solenoid 21 is turned off and the conveying belt 30 returns to the initial position (the position shown by the solid line).

In the sheet feeding apparatus 100E, the separating performance can be further improved by performing the operation of peeling the sheet S1 and the sheet S2 in the process of conveying the uppermost sheet S1. Further, a sensor for detecting whether or not the sheet S is adsorbed on the conveyor belt 30 may be provided, and the conveyor belt 30 may be moved up and down after the adsorption. <Sixth Embodiment> In the sheet feeding device 100F of the configuration example (6) shown in FIG. 11, the separation roller 4 of the sheet feeding device 100E is replaced with a suction separation pad 33.

The suction separation pad 33 air is supplied to the suction chamber 33A.
And an air suction hole 33B. Air suction chamber 33
A vacuum pump VP (not shown) is connected to A.

In this sheet feeding apparatus 100F, when the two sheets S1 and S2 are conveyed by the conveyor belt 30, the lower sheet S2 is sucked and separated by the suction separation pad 33, and only the sheet S1 is conveyed. It is transported downstream.

In this case, the separation performance can be further improved by making the surface of the suction separation pad 33 have a high friction coefficient. <Seventh Embodiment> The sheet feeding device 100E, 1
When an endless belt is used as the conveying means or the separating means as in 00F, the sheet S is bent and the sheet S is bent by providing ribs 35 and the like in the endless belt 34 as shown in FIG. Adhesion between them can be reduced and the separation performance can be improved. In addition, it is possible to avoid a phenomenon in which the uppermost sheet S1 is bent so that the sheet S1 becomes stiff such that it is difficult to bend in the direction perpendicular to the conveyance direction, and the sheet S1 is adsorbed by both the conveyance belt and the separation belt and cannot be conveyed. You can <Eighth Embodiment> When the rib 3S is provided on the conveyor belt 30 of the sheet feeding apparatus 100F like the belt 34 of the seventh embodiment, the air suction of the suction separation pad 33 is performed as shown in FIG. The chamber 33A can be configured to be longer than the air suction opening 31 of the conveyor belt 30 on the downstream side in the conveying direction, and with this structure, the section B in which only the separation suction force is generated is provided. It is possible to further improve the separation performance. At this time, the sheet S1 to be conveyed is not attached to the suction separation pad 33 because the ribs 3S support the sheet S1. <Ninth Embodiment> When the sheet S is sucked by the air suction force as in the present invention, a stable suction force is generated on the entire suction surface by providing an independent suction passage in the air suction portion. FIG. 14 shows an example of the configuration. Here, a plurality of partition plates 37 are provided in the air suction portion 36 to form a plurality of independent intake passages 36A. Each partition plate 37 extends radially from the center of the axial fan 38.

In the present specification, the case where the present invention is applied to the sheet feeding apparatus of the type in which the sheets stacked in the sheet stacking unit are sequentially fed out from the uppermost sheet has been described. It is needless to say that the present invention can be applied to a sheet feeding device of the type in which the sheets stacked in the unit are sequentially fed out from the lowest sheet.

[0049]

FIG. 15 shows an example of the overall structure of a sheet feeding apparatus of the present invention (here, a copying machine (sheet processing apparatus) equipped with the sheet feeding apparatus 100A of the structural example (1)).

The copying machine main body 200 includes a document table 20.
6, a light source 207, a lens system 208, a paper feeding unit 209, an image forming unit 202, and the like.

The paper feeding section 209 has cassettes 210 and 211 for accommodating the sheet S and being detachable from the copying machine main body 200, and a deck 213 arranged on the pedestal 212.
Above the deck 213, the sheet feeding device 10 of the present invention.
0A is arranged.

The image forming unit 202 includes a cylindrical photosensitive member 2
14, a developing device 215 containing a toner, a transfer charger 2
16, a separate charger 217, a cleaner 218, a primary charger 219, etc. are provided respectively.

A conveying device 220, a fixing device 204, a pair of paper discharge rollers 205 and the like are arranged on the downstream side of the image forming section 202.

Next, the operation of this copying machine will be described.

When a paper feed signal is output from a control device (not shown) provided on the copying machine main body 200 side, one sheet S is fed from the designated paper feed unit (cassette 210, 211 or deck 213). Paper is fed one by one. Deck 2
When 13 is designated, the sheet feeding apparatus 100A of the present invention feeds the sheets S on the deck 213 one by one.

On the other hand, the light reflected from the light source 207 on the original D placed on the original placing table 206 is reflected on the photosensitive drum 214 via the lens system 208, and the light is emitted. Form an electrostatic latent image, and then the developing device 215 forms a toner image.

The skewed state of the sheet S fed from the sheet feeding unit 209 is corrected by the pair of registration rollers 201, and the sheet S is further fed to the image forming unit 202 at the same timing.

In the image forming section 202, the transfer charger 21 is used.
The toner image on the photosensitive drum 214 is transferred to the sheet S sent by the transfer roller 6 and the transferred sheet S is separated by the separation charger 2
It is charged to the opposite polarity to the transfer charger 216 by 17 and separated from the photosensitive drum 214.

The separated transferred sheet S is
The transfer device 220 conveys the image to the fixing device 214, and the identification fixing device 204 permanently fixes the unfixed transferred image on the sheet S. The sheet S that has undergone the fixing process is the discharge roller 20.
The sheet is ejected from the copying machine main body 200 by 5.

[0060]

As described above, in the sheet feeding apparatus of the present invention, the sheet conveying means adsorbs the sheets stacked on the sheet stacking section by the suction force of air and conveys the sheets.
Further, the sheet separating unit sucks and separates the sheet unwound from the sheet stacking unit by the suction force of air.
Therefore, it becomes possible to dispose the sheet conveying means and the sheet separating means at a predetermined distance. Therefore, the abrasion of the sheet conveying means and the sheet separating means is reduced. Also,
A plurality of sheets fed from the sheet stacking unit are not rubbed between the sheet conveying unit and the sheet separating unit, and the sheets can be separated without being contaminated.

Further, since the separating roller sucks and separates the unwound extra sheet by the suction force of air, the sheet can be surely separated even if the tip of the unwound sheet is curled or bent.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional side view showing a configuration example (1) of a sheet feeding device of the present invention.

FIG. 2 is a front view (FIG. (2) (a)) showing a detailed configuration of a sheet separating unit in the sheet feeding device of the same configuration example (1) and a configuration of a drive system for transmitting drive to the sheet separating unit. The side view shown (Fig. (2) (b)).

FIG. 3 is a vertical cross-sectional side view illustrating a sheet separating operation in the sheet feeding device of the configuration example (1).

FIG. 4 is a vertical sectional side view showing a configuration example (2) of the feeding device of the present invention.

FIG. 5 is a front view (FIG. 5A) showing a detailed configuration of a sheet separating unit in the sheet feeding device of the configuration example (2), and a configuration of a drive system for transmitting drive to the sheet separating unit. A side view (FIG.5 (b)).

FIG. 6 is a vertical cross-sectional side view showing a configuration example (3) of the sheet feeding apparatus of the present invention.

FIG. 7 is a vertical cross-sectional side view illustrating a sheet feeding operation in the sheet feeding device of the configuration example (3).

FIG. 8 is a vertical cross-sectional side view showing a configuration example (4) of the sheet feeding device of the invention.

FIG. 9 is a front view (FIG. 9A) showing a detailed configuration of a sheet separating unit in the sheet feeding device of the configuration example (4), and a configuration of a drive system for transmitting drive to the sheet separating unit. A side view (FIG.9 (b)).

FIG. 10 is a vertical sectional side view showing a configuration example (5) of the sheet feeding device of the invention.

FIG. 11 is a vertical sectional side view showing a configuration example (6) of the sheet feeding device of the present invention.

FIG. 12 is a side view (FIG. 12A) showing another configuration example of the endless belt used in the sheet separating portion in each of the sheet feeding devices of configuration examples (5) and (6); Bottom view (Figs. (12) and (b)).

FIG. 13 is a vertical cross-sectional side view showing another configuration example of the separation pad used in the sheet separation unit in the sheet feeding device of configuration example (6).

FIG. 14 is a plan view showing a configuration example in which independent suction paths are formed in the suction portions of the sheet conveying unit and the sheet separating unit.

FIG. 15 is a vertical cross-sectional side view showing the overall configuration of a copying machine (sheet processing apparatus) including the sheet feeding apparatus of the present invention.

[Explanation of symbols]

 1 Stacking Tray (Sheet Stacking Section) 3 Conveying Rollers (Sheet Conveying Means) 4 Separation Rollers (Sheet Separating Means) 30, 34 Conveying Belts (Sheet Conveying Means) 33 Suction Separation Pads (Sheet Separating Means) 100A to 100F Sheet Feeding Devices 214 Photosensitive drum (sheet processing means) S sheet

Claims (5)

[Claims] 1. A sheet feeding device that separates and conveys sheets stacked in a sheet stacking unit one by one, and a sheet that sucks and conveys the sheets stacked in the sheet stacking unit by an air suction force. A sheet feeding device comprising: a conveying unit; and a sheet separating unit that sucks and separates an extra sheet fed from the sheet stacking unit by an air suction force. 2. The sheet feeding apparatus according to claim 1, wherein the sheet conveying means and the sheet separating means are arranged with a predetermined distance therebetween. 3. The sheet feeding apparatus according to claim 1, wherein the sheets stacked on the sheet stacking unit are fed in order from the uppermost sheet. 4. The sheet feeding apparatus according to claim 1, wherein the sheets stacked on the sheet stacking unit are fed in order from the lowest sheet. 5. The sheet feeding device according to claim 1, and a sheet processing for performing a predetermined process on the sheets fed one by one by the sheet feeding device. A sheet processing apparatus comprising: