JPH09315605A - Paper feeder, and image forming device equipped with it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve separation of the rear end part of large size sheets, and the loading performance of the large size sheet, without affecting the separating performance of a small size sheet. SOLUTION: Air is blown by nozzles 5a and 5b, to one side part of plural sheets loaded on a tray 6, to float the sheets other that a sheet on the lowermost surface, and feed the sheet on the lowermost surface by a sheet feeding means 1. Blowing air to sheet side part eliminates the effect of a small size sheet on separating performance, and the crossing of the directions of the air flows of the nozzles 5a and 5b, consequently air is blown to the rear end part too of a large size sheet, thereby improving the separation performance of the rear end part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine and the like, and more particularly to a paper feeding device for feeding stacked originals or recording sheets separately.
The present invention relates to a lower separation sheet feeding device that separates sheets from the lowermost surface of stacked sheets and feeds the sheets.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine, stacked sheets such as originals and recording sheets are printed from the bottom surface to the bottom.
A sheet feeding device for sequentially feeding sheets one by one is often provided.

In such a sheet feeding device, one sheet is fed.
As the means for separating the sheets one by one, there are a separation method by injecting air from the downstream side to the upstream side in the transport direction, and a separation method by a roller (retard roller) that rotates in the opposite direction to the sheet feeding direction.

However, in the separation method by injecting air from the downstream side to the upstream side in the conveying direction, a stacked sheet is blown backward by the air flow, so that a member for regulating the rear end is indispensable. When different originals are mixed, the position of a small sheet is not guaranteed, which makes it difficult to convey the sheets.

Further, in the retard roller system, since the difference between the coefficient of friction between sheets and the coefficient of friction between sheets and rollers is utilized, pressure must be applied to the sheet, which causes a problem of document stain called edge stain. There is.

As a separation system which does not have these drawbacks, a system has been devised in which air is blown to the side surface of the sheet along the sheet feeding direction to separate the sheets.

This separation method has the advantages that the original is not smeared because no pressure is applied to the original and that the mixed sizes of the fed originals are possible.

FIG. 7 is a perspective view showing the structure of the paper feeding device devised above, and FIG. 8 is a vertical sectional view of the paper feeding device.

The sheet feeding device 110 has a sheet tray 106 on which sheets S are stacked, and the sheet tray 106.
A sheet feeding unit 101 disposed on the lower surface of the stacking sheet near the leading end of the stacked sheets S to suck and convey the lowermost sheet Sl of the stacked sheets S, and a sheet feeding direction of the sheets S stacked on the sheet tray 106. A nozzle 105 for injecting air toward the front side end surface and restriction means 121, 120 for restricting the side surface of the stacked sheet S in the sheet feeding direction are provided. Also,
A holding member 123 that holds the stacked sheets is provided substantially at the center of the regulation unit 121.

The sheet feeding means 101 comprises a plurality of rotating rollers 103a, 10 arranged on the lower surface of the sheet tray 106.
It has a feeding belt 104 which is stretched around 3b and 103c and in which a large number of through holes are formed. Rotating roller 103
In the space formed between a and 103b, the intake duct 1
02 is arranged, and the lowermost sheet Sl of the sheets stacked on the sheet tray 106 is provided with an opening for vacuum suction through a large number of through holes of the feeding belt 104.

Then, the sheet S placed on the sheet tray 106 is sewn by the air jetted from the nozzle 105.
8 floats slightly as shown in FIG. 8, and only the stacked lowermost sheet S1 is vacuum-adsorbed to the feeding belt 104. Then, the air flow from the nozzle 105 enters between the lowermost sheet S1 and the sheet S2 immediately above the sheet S1, and the air layers thus generated separate the sheet S1 and the sheet S2.

By rotating the rotary roller 103a, the separating and conveying operation of the lowermost sheet is completed.

[0013]

However, in the sheet feeding device having the above-described structure, when a large size sheet (eg, A3 or B4) is stacked on the sheet tray, the air flow toward the rear end of the sheet is small. However, there was a problem that the separability at the rear end portion of the sheet was poor and that the number of sheets to be loaded in the large size sheet could not be too large.

The present invention aims to improve the separating performance of the rear end portion of the large size sheet without affecting the separating performance of the small size sheet and to improve the stackability of the large size sheet. It is also intended to provide a device.

[0015]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and the present invention according to claim 1 is a stacking means for stacking a plurality of sheets, and a sheet feeding direction of the sheets. A side regulating means for regulating the sheet, a means for injecting air to the side surface of the sheet intersecting the sheet feeding direction to float the stacked sheets, and a sheet at the bottom of the sheets stacked on the tray. A sheet feeding device including a sheet feeding unit that sucks and conveys by vacuum, and has one or more jetting units that jet air in at least two directions toward the side surface of the sheet, and the air jetted by these jetting units. It is characterized in that the flow directions do not intersect each other.

According to a second aspect of the present invention, the first jetting means for jetting air toward the downstream side in the sheet feeding direction is supplied to the sheet side surface of the sheet on the stacking means, and the sheet side surface is supplied. A second jetting unit that jets air toward the downstream side in the paper direction.

According to a third aspect of the present invention, the stacking means has a recess at a position corresponding to the upper side of the sheet feeding means in a direction intersecting the sheet conveying direction, and the sheet at the lowermost surface formed by the sheet feeding means. At the time of adsorption, a space is formed between the lowermost sheet and the sheet above it.

According to a fourth aspect of the present invention, a stacking unit for stacking a plurality of sheets, a side restricting unit for restricting a sheet feeding direction of the sheets, and an air flow on a side surface of the sheet intersecting the sheet feeding direction of the sheets are provided. A sheet feeding device for ejecting the sheet to float the stacked sheet, and a sheet feeding section for vacuum-sucking and conveying the lowermost sheet of the sheet stacked on the tray. A plurality of jetting means for jetting air toward the sheet side surface of the sheet on the means are provided, and at least one of the jetting means is an intermittent jetting means.

According to a fifth aspect of the present invention, the stacking means has a recess at a position corresponding to the upper side of the sheet feeding means in a direction intersecting the sheet conveying direction, and the sheet at the lowermost surface by the sheet feeding means. At the time of adsorption, a space is formed between the lowermost sheet and the sheet above it.

The present invention according to claim 6 is the sheet feeding apparatus according to claim 4 or 5, wherein the intermittent jetting means jets air toward the side surface of the sheet in the upstream direction of the sheet feeding direction.

The present invention according to claim 7 is characterized in that the intermittent means of the intermittent injection means is a valve provided between the air supply source and the intermittent injection means.

The present invention according to claim 8 is characterized in that the driving means of the intermittent injection means is a solenoid.

The present invention according to claim 9 is characterized in that the driving means of the intermittent injection means is a motor.

The present invention according to claim 10 is characterized in that the intermittent jetting means jets air after the sheet feeding means adsorbs the lowermost sheet by air.

The present invention according to claim 11 is characterized in that, after the sheet feeding means stops air adsorption of the lowermost sheet, the intermittent jetting means stops the air jetting.

[Operation] Based on the above configuration, the sheet bundle stacked on the stacking means has one side portion along the conveying direction,
The air is blown by the jetting means for jetting in two directions, and the sheet at the lowermost surface is vacuum-sucked by the sheet stacking means to be separated and fed. The injection means,
By injecting air in two directions that do not intersect, the force exerted by the air flow on the sheet bundle is prevented from locally increasing, and even if there is no regulation means for regulating the rear end of the sheet bundle, the small size The rear end of the large size sheet can be floated up without affecting the separation of the sheets, and the large size sheet on the bottom surface can be reliably separated and fed.

Further, by providing a gap in the portion of the stacking means corresponding to the sheet feeding means, when the lowermost sheet is adsorbed by the stacking means, the sheet is placed between the lowermost sheet and the sheet above it. A space is formed in the space, and the air flow by the injection means enters into the space, so that the sheet above the lowermost sheet can be reliably floated and the lowermost sheet can be reliably separated.

Further, by using one of the plurality of jetting means as the intermittent jetting means, the intermittent jetting means is operated, for example, in a state where a part of the sheet bundle other than the lowermost surface is floated by the other jetting means. By doing so, the other part of the sheet bundle can be floated, whereby the inclination angle of the intermittent jetting means with respect to the stacking means can be made small, and the sheet bundle other than the lowermost sheet is floated by a small air flow.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION

<First Embodiment> First, an example of an image forming apparatus main body (copier main body) to which a paper feeding device according to the present invention can be applied will be described with reference to FIG.
It will be described based on.

An image forming apparatus main body (copier main body) 900 includes a platen glass 906 as a document placing table, a light source 9
07, a lens system 908, a paper feeding unit 909, an image forming unit 90
2, an automatic document feeder 940 that feeds a document to the platen glass 906, a sheet processing device that sorts and stores sheets on which images formed on the sheet are discharged from the copying machine main body, and the like.

The sheet feeding unit 909 accommodates the recording sheet S and is detachably attached to the apparatus main body 900.
1 and the deck 913 arranged on the pedestal 912
have. Each of the cassettes 910 and 911 is provided with the sheet feeding device 1 according to the present invention, and separates the sheets on the bottom surface one by one to feed the sheets as described later.

The image forming portion 902 includes a cylindrical photosensitive drum 914, a developing device 915 around the photosensitive drum 914, and a transfer charger 91.
6, separation charger 917, cleaner 918, primary charger 9
19 etc. are respectively provided. Downstream of the image forming unit 902, a transport device 920, a fixing device 904, a discharge roller pair 905, and the like are provided.

The operation of the main body of the image forming apparatus will be described.

When a paper feed signal is output from the control device 930 provided on the apparatus main body side 900, the cassette 91
The sheet S is fed from the deck 0, 911 or the deck 913. On the other hand, the document D placed on the document table 206
The light reflected from the light source 907 is applied to the photosensitive drum 914 via the lens system 908. The photosensitive drum 914 is charged in advance by a primary charger 919, and an electrostatic latent image is formed by irradiation with light, and then the electrostatic latent image is developed by a developing unit 915 to form a toner image. .

The sheet S fed from the sheet feeding section 909 is
The skew is corrected by the registration rollers 901, and the skew is sent to the image forming unit 902 at the same timing. In the image forming unit 902, the toner image on the photosensitive drum 914 is transferred to the fed sheet S by the transfer charger 916, and the sheet S on which the toner image has been transferred is transferred to the separation charger 91.
7, is charged to a polarity opposite to that of the transfer charger 916,
It is separated from the photosensitive drum 914.

Then, the separated sheet S is conveyed to the fixing device 904 by the conveying device 920, and the fixing device 9
The transfer image is fixed to the sheet S by 04. The sheet S on which the image is fixed is discharged from the apparatus main body 900 by the discharge roller pair 905.

In this way, an image is formed and discharged on the sheet S fed from the sheet feeding section 909.

Next, a schematic structure of the sheet feeding device according to the first embodiment will be described with reference to FIGS.

In the figure, 1 is a sheet feeding means for feeding stacked sheets, 2 is an intake duct connected to a suction fan (not shown) through a valve (not shown), and 3a is rotationally driven by a driving means (not shown). The rotation rollers 4 of the feeding belt are wound around the rotation rollers 3a and 3b, and the feeding belt 5 that sucks and conveys the sheet by the suction force of the sheet feeding duct 2 is provided on the side surface of the sheet, and is not shown. Nozzle (sheet floating means) connected to the blowing fan of
Are outlets (injection means) 5a, 5 directed in different directions
with b.

The jet direction 5A of the nozzle 5a (first jetting means) is directed toward the leading edge of the stacked sheets S.
is oriented with an inclination angle of α1, while the nozzle 5b
The blowing direction 5B of the (second ejecting unit) is directed to the conveying rear end direction of the stacked sheets with an inclination angle of α2.

The tray (stacking means) 6 has a stacking surface 6c on which the sheets S are stacked, an inclined surface 6a which is orthogonal to the sheet S feeding direction and is inclined downward from the stacking surface 6c, and an inclined surface 6
an inclined surface 6 that intersects a and inclines upward from the loading surface 6c.
It is configured to have a concave portion with b.

Reference numeral 7 is a pair of pull-out rollers for conveying the separated sheet downstream, 8 is a sensor lever for detecting that the sheet has been conveyed, and 20 and 21 are regulations for preventing deviation of the sheet S in the direction perpendicular to the conveying direction. Means, 23 is a holding member for preventing deviation of the sheet S, S is a stacked sheet, P is a void of the recess created by the extension line of the loading surface 6c and the inclined surfaces 6a and 6b, and this void is referred to as a pocket P. To call.

The pocket P is located downstream of the central portion of the large size sheet in the transport direction and upstream of the small size sheet in the transport direction.

Next, the operation of this embodiment will be described.

First, a plurality of sheets S are stacked on the tray 6. When a start signal is input from the main body CPU (control means) 930 to the paper feeding means 1, both nozzles 5
a, 5b to one side of the stacked sheet S and the pocket P
Air is jetted in the direction, and the sheet S floats in a bundled state as shown in FIG.

At this time, the air flow ejected from the nozzle 5a is set to flow through the pocket P toward the downstream side in the sheet passing direction. On the other hand, the airflow ejected from the nozzle 5b is set so as to flow toward the upstream side in the sheet passing direction via the pocket P, and when a large size sheet is stacked, the airflow is positively applied to the rear end portion. It is constructed so that air can be sent in and the rear end can be reliably floated.

Here, both nozzles 5a and 5b are constructed so that the air streams ejected from them do not directly join.

In addition, the air flow ejected from the nozzle 5b is set so as to flow toward the diagonal portion of the sheet on the upstream side of the conveyance with respect to the small size sheet. This allows
It does not affect the separability of the small size sheet, and even when the sheet sizes are mixed, while giving the effect of improving the separability for the large size, It has a function that does not give a shadow rate.

At this time, the vertical angle θ between the nozzles 5a and 5b shown in FIG. 3 and the sheet S is 0 ° <θ <90 °, and in consideration of the rectification effect, 25 ° ≦ θ ≦ 60 °.
Is preferred.

On the other hand, the inclination angle α1 of the nozzle 5a is preferably set in the direction near the diagonal portion on the downstream side of the stacked sheets S in the sheet passing direction. Further, the inclination angle α1 of the nozzle 5b with respect to one side portion of the sheet may be set in the direction near the diagonal portion on the upstream side in the sheet passing direction of the stacked sheets S.

Next, the valve (not shown) is released, the inside of the intake duct 2 becomes negative pressure, and the lowermost sheet S1 of the sheets stacked on the suction belt 4 is adsorbed. When the sheet S1 is adsorbed, the sheet S1 is curved according to the shape of the recess of the tray 6. However, since the suction force of the intake duct 2 does not act on the sheet S2 immediately above it, it cannot follow the shape of the tray 6, and as a result, the pocket P is formed between the sheets S1 and S2. To be done.

Since the airflow from the nozzles 5a and 5b is blown into the pocket P, the sheets S2 and S
Air enters between the sheets 1 and the air layer separates the sheet at the lowermost surface from the sheet immediately above, whereby the sheet S1 at the lowermost surface and the sheet S2 immediately above are separated.

Next, when the rotary drive is applied to the rotary roller 3a, the sheet S1 attracted to the suction belt 4 is conveyed toward the pull-out roller pair 7 and the sensor lever 8 indicates that the sheet S1 has reached the pull-out roller pair 7. When detected, the rotation drive of the rotation roller 3a is stopped after a certain period of time,
Although the valve (not shown) connected to the intake duct 2 is closed, the sheet S1 is conveyed further downstream by the pull-out roller pair 7.

Although the regulation means for regulating the rear end of the stacked sheets is not used in this embodiment,
Even when the small size sheets are separated or when the small size sheets are mixed, the small size sheets are separated by blowing the air flow that floats the sheet bundle other than the bottom surface to one side of the sheet bundle. Has no effect on. Then, the air flow of the nozzle 5b flows toward the rear end of the large size sheet, preventing the separability of the rear end of the large size sheet from being increased, and increasing the loading amount of the large size sheet.

Next, the effect of the first embodiment will be described.

According to the present embodiment, in a system in which air is blown from the side surface in the sheet feeding direction for separation with a simple structure, the separation of the small size sheet can be performed without any adverse effect on the separation of the small size sheet. Poor separability at the ends can be prevented, and a large number of large size sheets can be stacked.

Further, since the airflows blown from both nozzles 5a and 5b do not join, the force exerted by the airflows on the sheets S does not locally increase, so that the bundle of sheets S becomes violent during the conveying operation. Therefore, a stable paper feeding operation can be performed.

<Embodiment 2> Embodiment 2 of the present invention
Will be described with reference to FIGS. 4 to 5. However, the same parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

The schematic structure of the present invention will be described with reference to FIG. 4. Reference numeral 9 is an electromagnetic valve (intermittent means) for controlling ON / OFF of the nozzle 5b (intermittent injection means).

Next, the operation of this embodiment will be described.

In the first embodiment, during the paper feeding operation,
Although the nozzles 5a and 5b continuously ejected the airflow, in the present embodiment, as shown in FIG. 5, the nozzle 5b is turned ON / OFF at the timing of the sheet feeding operation. The operation procedure will be described below.

First, the paper feed signal is the CPU 930 of the apparatus main body.
From the nozzle 5a, the air is jetted from the nozzle 5a, and the valve connected to the suction duct 2 is also in the open position to perform the sheet suction operation. After Tl seconds, the solenoid valve 9 is opened, and air is also jetted from the nozzle 5b.

After that, although not shown in FIG. 5, after the negative pressure in the intake duct 2 is reached, the feed belt 4 operates to convey the sheet Sl. When the sheet Sl is conveyed in the direction of the pull-out roller, the sensor lever 8 detects the leading edge of the sheet, and T2 seconds after that, the valve connected to the intake duct is OF.
It becomes F, and the suction of the feeding belt 4 is turned off.

Then, after T3 seconds, the solenoid valve 9 is turned off.
It becomes F, and the injection of air from the valve 5b is stopped. Then, after repeating the sequence for the required number of times,
When the operation ends, the injection of all air is stopped and the operation ends.

Here, the waiting time during the sequence from T1 to T3 is a value that should be appropriately determined depending on the copy speed of the apparatus main body 900, the type of the sheet S, the number of sheets loaded in the sheet, and the like.

Further, in this embodiment, the nozzle 5
Although the example in which the nozzles a and 5b are branched from the same nozzle is shown, it is obvious that there is no problem even if the nozzles 5a and 5b are independently installed.

Further, in the present embodiment, the nozzle 5
Although the example of using the solenoid valve for ON / OFF of b has been described, this is not limited to the solenoid valve, and ON / OFF of the air flow,
Anything that can perform strength-weakness may be used.

For example, the nozzle 5b may be turned on / off by driving the shutter member with a solenoid or a motor. At this time, it can be constructed at low cost by driving with a solenoid, but only binary control is possible. When it is desired to continuously change the air flow in the nozzle 5b, or when multi-valued control of the air flow is performed, the stepping motor may be used for driving, but an AC motor or a DC motor may be used.

Next, the effect of the second embodiment will be described.

According to the second embodiment, in addition to the effect shown in the first embodiment, the air is blown by the nozzle 5a. After being blown to one side of the sheet bundle, the suction force of the intake duct 2 attracts the lowermost sheet S1 to the feeding belt 4 to form a pocket P between the sheets S1 and S2,
By opening the solenoid valve 9 and operating the nozzle 5b, the air flow ejected from the nozzle 5b can be surely blown into the pocket P without exposing the sheet S. Therefore, the inclination angle θ of the nozzle 5b in the vertical direction is increased. Even if is small, there is an effect that problems such as flapping of the sheet S do not occur.

If the inclination angle θ is small, the loss of the air flow in the nozzle 5b is reduced, so that the nozzles 5a, 5
It is possible to reduce the flow rate of the air flow of b, so that
The number of rotations of the fan is low, and it is effective in realizing low noise and power saving.

[0072]

As described above, according to the present invention,
The ejecting unit that blows air on one side of the sheet ejects the air in two directions that do not intersect, thereby affecting the separation of the small size sheets without a regulating unit that regulates the rear end of the sheet bundle. Instead, the rear end portion of the large size sheet can be floated up to reliably separate and feed the lowermost large size sheet, and the stacking amount of the large size sheet on the stacking unit can be increased. Also, because the air flow to one side of the seat does not intersect,
It is possible to prevent the force of the air flow applied to the sheet bundle from locally increasing, and to prevent the sheet being conveyed from violently moving.

Further, by providing the concave portion in the portion of the stacking means corresponding to the sheet feeding means, when the sheet of the lowermost surface is adsorbed by the stacking means, the sheet between the lowermost sheet and the sheet above it is provided. A space is formed in the space, and the air flow from the jetting means enters into the space, so that the sheet bundle above the lowermost sheet can be reliably floated and the lowermost sheet can be reliably separated.

Further, by using one of the plurality of jetting means as the intermittent jetting means, for example, the intermittent jetting means is operated in a state where a part of the sheet bundle other than the lowermost surface is floated by the other jetting means. Thus, the other portion of the sheet bundle can be floated, whereby the inclination angle of the intermittent jetting means with respect to the stacking means can be reduced, and the sheet bundle other than the lowermost sheet can be floated with a small air flow, and Reduction of air flow,
Low noise and power saving can be realized.

[Brief description of drawings]

FIG. 1 is a plan view of a sheet feeding device according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional side view of the sheet feeding device.

FIG. 3 is a vertical sectional front view of the sheet feeding device.

FIG. 4 is a plan view of the sheet feeding device according to the second embodiment of the present invention.

FIG. 5 is a flowchart of the operation of the paper feeding device.

FIG. 6 is a vertical sectional front view showing an example of an image forming apparatus to which the present invention is applicable.

FIG. 7 is a perspective view showing an example of a sheet feeding device.

FIG. 8 is a vertical side view of the sheet feeding device of FIG.

[Explanation of symbols]

S sheet S1 lowermost sheet S2 sheet immediately above the lowermost sheet P pocket (gap) 1 sheet feeding means 2 intake duct 5 sheet floating means 5a nozzle (first ejection means) 5b nozzle (second ejection means, Second tray means (intermittent jetting means) 6 Tray (loading means) 6a, 6b Inclined surface forming recess 9 Electromagnetic valve (intermittent means) 20,21 Side regulating means α1 Wall surface of nozzle 5a with respect to one side of seat Inclination angle α2 Inclination angle of nozzle 5b with respect to one side of sheet θ Vertical inclination angle of nozzle with respect to sheet

Claims (12)

[Claims] 1. A stacking unit for stacking a plurality of sheets, a side restricting unit for restricting a sheet feeding direction of the sheets, and air is jetted to a side surface of the sheet intersecting the sheet feeding direction to stack the sheets. A sheet feeding device including means for floating a sheet and sheet feeding means for vacuum-sucking and transporting a sheet on the lowermost surface of sheets stacked on the tray, in at least two directions toward the side surface of the sheet. A sheet feeding device, characterized in that it has one or more jetting means for jetting air, and the directions of the air streams jetted by these jetting means do not intersect with each other. 2. A first jetting unit that jets air toward the sheet side surface of the stacking unit toward the downstream side in the sheet feeding direction; and a first jetting unit toward the downstream side in the sheet feeding direction with respect to the sheet side surface. The sheet feeding device according to claim 1, further comprising: a second ejecting unit that ejects air. 3. The stacking means has a recess at a position corresponding to the upper side of the paper feeding means in a direction intersecting a sheet conveying direction, and when the lowermost sheet is adsorbed by the paper feeding means, 3. An air gap is formed between the sheet and the sheet above the sheet.
A paper feeder according to claim 1. 4. A stacking means for stacking a plurality of sheets, a side restricting means for restricting a sheet feeding direction of the sheet, and air is jetted to a side surface of the sheet intersecting the sheet feeding direction to stack the sheets. A sheet feeding device comprising: a unit for floating a sheet; and a sheet feeding unit for vacuum-sucking and transporting the lowermost sheet of sheets stacked on the tray. A sheet feeding device, comprising a plurality of jetting means for jetting air toward, and at least one of the jetting means is an intermittent jetting means. 5. The stacking means has a recess at a position corresponding to the upper side of the sheet feeding means in a direction intersecting a sheet conveying direction, and when the sheet at the lowermost side is adsorbed by the sheet feeding means, the stacking means has a lowermost surface. The sheet feeding device according to claim 4, wherein a gap is formed between the sheet and the sheet above the sheet. 6. The sheet feeding device according to claim 4, wherein the intermittent jetting unit jets air toward the side surface of the sheet in the upstream direction of the sheet feeding direction. 7. The intermittent injection means of the intermittent injection means is a valve provided between an air supply source and the intermittent injection means, according to any one of claims 4 to 6. Paper feeder. 8. The sheet feeding device according to claim 4, wherein the driving unit of the intermittent ejection unit is a solenoid. 9. The paper feeding device according to claim 4, wherein the driving means of the intermittent ejection means is a motor. 10. The sheet feeding apparatus according to claim 4, wherein the intermittent jetting unit jets air after the sheet feeding unit adsorbs the lowermost sheet by air. apparatus. 11. The intermittent injecting means stops the air injection after the sheet feeding means stops the air adsorption of the lowermost sheet, and the intermittent air injecting means stops the air injection.
The paper feeding device according to the item. 12. A sheet feeding device according to claim 1, and an image forming unit for forming an image on a sheet fed by the sheet feeding device. Image forming apparatus.