JPH11139596A - Sheet feeding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely feed sheets one by one with a separating mechanism separating the front end portions of multiple sheets mounted in stack. SOLUTION: When a swing duct 22 sucking sheets is lifted to a feeding position, a part of the air discharged from the nozzle 38 of a fixed duct 23 is guided to a sheet opposing face 22a along an air flowing face 22c into contact with the front end sections of the sheets sucked to the sheet opposing face 22a. The contact angle of air against the front end sections of the sheets sucked to the sheet opposing face 22a is gradually changed while the swing duct 22 is rocked from the sucking position to the feeding position, and the air discharged from the nozzle 38 surely flows into the gaps of multiple sheets sucked to the swing duct 22 at some timing during this period. The sheets other than the uppermost sheet having relatively weak suction force to the swing duct 22 are separated from the uppermost sheet, and multiple sheets are surely prevented from being fed simultaneously.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to an apparatus having a sheet processing function such as an image forming apparatus and an image reading apparatus.
The present invention relates to a sheet feeding apparatus that feeds stacked stacked sheets one by one to a processing unit, and particularly to a sheet feeding apparatus that sucks and feeds a sheet at a feeding position by negative pressure.

[0002]

2. Description of the Related Art In an apparatus having a sheet processing function such as an image forming apparatus such as a copying machine or a printer, a plurality of sheets stacked and placed on a feeding section are transferred to a processing section such as an image forming process section. As a sheet feeding apparatus for feeding sheets one by one, there is a sheet feeding apparatus that sucks sheets by negative pressure.

In such a sheet feeding apparatus that sucks and feeds sheets one by one by a negative pressure, if another sheet is closely attached to a sheet to be fed due to static electricity or the like, the sheet is sucked by a negative pressure. A plurality of sheets are fed at a time while another sheet is in close contact with the sheet. Therefore, at least the sheet to be fed must be separated from other sheets before the sheet is sucked.

Japanese Patent Application Laid-Open No. 53-26066 discloses a vacuum plate which is disposed on the upper surface of a sheet so as to be swingable up and down and sucks the sheet by a negative pressure. A configuration of an air feeding device provided with a sheet pressing portion that forms a space between the plate and the plate is disclosed.

More specifically, when the sheet is moved to a position where the sheet comes into contact with the feeding roller by swinging the vacuum plate having sucked the sheet upward, the vacuum plate is bent at a portion where the feeding roller is exposed. Forming a sheet pressing portion, and pressing the middle portion of the sheet downward by the sheet pressing portion when the vacuum plate is moved downward before starting suction, thereby vacuuming the leading end portion of the sheet that has bent upward. The plate is used for suction.

[0006]

However, in the above-described conventional air sheet feeding device, the leading end of the sheet is sucked downstream of the feeding roller in the feeding direction, so that the elastic force of the sheet is relatively weak. In this case, even when the feeding roller is rotated, the sheet may be loosened between the suction portion and the feeding roller while the leading end of the sheet is suctioned by the vacuum plate, and the sheet may be moved in the feeding direction. There is a problem that can not be done.

When the vacuum plate is moved upward while the uppermost sheet is being sucked, a negative pressure is applied to the lower side of the uppermost sheet, and the sheet located below the uppermost sheet becomes the uppermost sheet. There is a problem that a plurality of sheets are fed at a time by being attracted to the lower surface of the sheet.

Further, since the sheet is brought into contact with the feeding roller by the suction force of the vacuum plate and the feeding force is given to the sheet by the rotation of the feeding roller, the feeding force of the sheet by the rotation of the feeding roller is reduced. To increase the size, it is necessary to increase the suction force of the sheet to increase the contact force of the sheet against the feeding roller. However, increasing the suction force makes it difficult for the sheet to separate from the vacuum plate, and conversely causes a problem in that the sheet transportability is reduced, resulting in defective transport.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a sheet feeding apparatus capable of feeding sheets one by one using a separation mechanism for separating a front end portion of each of a plurality of stacked sheets. It is to provide a device.

[0010]

According to a first aspect of the present invention, there is provided a sheet storage unit which includes a sheet facing surface facing a sheet, and vertically including a feeding roller and independently of the feeding roller. A suction container that is swingably supported and has a hole that includes an exposed portion of the feed roller on the sheet facing surface, a suction position where the hole on the sheet facing surface contacts the sheet, and a part of the feed roller. A swing mechanism for swinging the suction container between the feeding position exposed from the exposed portion, and a suction mechanism for reducing the pressure in the suction container while at least the suction container swings from the suction position to the feeding position, and A discharge mechanism that discharges air from a discharge port facing the front end of the sheet during this time.In the sheet feeding device, the suction container is discharged from the discharge port facing the discharge port of the discharge mechanism. Air at the front end of the sheet facing surface Characterized by providing an air flow plane to guide.

According to the first aspect of the present invention, when the inside of the suction container located at the suction position is depressurized by the suction mechanism, the sheet abutting on the hole is attracted to the sheet facing surface, and in this state, the swing mechanism is rotated. Swings the suction container to the feeding position, a part of the feeding roller exposed from the exposed portion comes into contact with the sheet, and the sheet is fed by rotating the feeding roller.

While the suction container, which has adsorbed the sheet on the sheet-facing surface, moves from the suction position to the feeding position, the air discharged from the discharge port of the discharge mechanism contacts the air flow surface of the suction container. The sheet is guided to the front end of the sheet, and flows into the front end of the sheet adsorbed on the sheet facing surface. Depending on the swing angle of the suction container during the swing from the suction position to the feeding position, the angle that the air circulation surface makes with the air discharged from the discharge port gradually changes. The inflow angle of air to the front end of the attracted sheet also changes gradually.

Therefore, even when the front end of the sheet is deformed when a plurality of sheets are attracted to the sheet-facing surface, the plurality of sheets can be moved at any timing while the suction container swings. Air flows into each gap of the sheet. At this time, since a sufficient suction force from the suction container is not applied to the sheets other than the sheet that is in contact with the sheet facing surface, the air that has flowed into the gap causes the sheet that is in contact with the sheet facing surface to move away from the other sheets. The sheet is separated, and only one sheet in contact with the sheet facing surface is fed by the feeding roller.

According to a second aspect of the present invention, a conveying member for sandwiching a sheet is provided downstream of the suction container in the feeding direction, and the inside of the suction container is moved when the front end of the sheet reaches the conveying member. A pressurizing mechanism for pressing is provided.

According to the second aspect of the present invention, when the front end of the sheet fed by the feed roller reaches the conveying member, the inside of the suction container is pressed by the pressing mechanism. Therefore, after the front end of the sheet reaches the conveying member, the suction state of the sheet on the sheet facing surface of the suction container is positively released, and the sheet moving in the feeding direction by the feeding roller and the conveying member is opposed to the sheet. The frictional resistance acting from the surface is reduced.

According to a third aspect of the present invention, there is provided an image forming apparatus according to the first aspect of the present invention, wherein a position parallel to the sheet feeding direction is provided between a position facing the discharge port on the air flow surface and a position near the front end of the sheet attracted to the sheet facing surface. It is characterized in that a groove is formed.

According to the third aspect of the present invention, the air discharged from the discharge port is guided through the groove to the vicinity of the front end of the sheet adsorbed on the sheet facing surface, and is directly transferred from the discharge port to the vicinity of the front end of the sheet. It collides with the discharged air. For this reason, the air pressure near the front end of the sheet adsorbed on the sheet facing surface increases, and the air expands in this portion. Therefore, when a plurality of sheets are attracted to the sheet facing surface, the gap at the front end of the plurality of sheets is enlarged, and sufficient air flows to separate the respective sheets into the gap between the sheets.

According to a fourth aspect of the present invention, the discharge mechanism is provided with a slit-shaped discharge port which is inclined downward from a central portion to both side ends in a plane perpendicular to the sheet feeding direction. And

According to the fourth aspect of the present invention, the discharge port for discharging air to the front end of the sheet has a slit shape inclined downward from the center toward both side ends in a plane perpendicular to the feeding direction. The interval between the discharge ports in the direction perpendicular to the feeding direction changes up and down. Therefore, the front end of the sheet adsorbed on the sheet-facing surface of the suction container moves up and down while the suction container adsorbing the sheet on the sheet-facing surface swings from the suction position to the feeding position. Regardless of the width of the sheet in the orthogonal direction, the air discharged from the discharge port at any timing during the swinging of the suction container abuts on the corner at the front end of the sheet.

The invention described in claim 5 is characterized in that the discharge mechanism includes a moving mechanism for moving a discharge port in accordance with a size of a sheet in a direction orthogonal to a feeding direction. In the invention described in claim 5, the discharge port moves according to the sheet size in the direction orthogonal to the feeding direction. Therefore, regardless of the size of the sheet to be fed, the air discharged from the discharge port reliably contacts the front end of the sheet.

According to a sixth aspect of the present invention, there is provided a sheet-facing surface facing a sheet in a sheet storage portion, and is supported swingably up and down independently of the feeding roller with the feeding roller included therein. In addition, a suction container in which a hole including an exposed portion of the feeding roller is formed in the sheet facing surface, a suction position where the hole in the sheet facing surface contacts the sheet, and a part of the feeding roller is exposed from the exposed portion. A swing mechanism for swinging the suction container between the feeding position, a suction mechanism for reducing the pressure in the suction container at least while the suction container swings from the suction position to the feeding position, and a sheet facing the suction container. A separation mechanism for separating the front end of the sheet adsorbed on the surface from the front ends of other sheets,
And a pressurizing means for pressurizing the vicinity of the front end of the sheet adsorbed on the sheet facing surface of the suction container when the suction container starts swinging from the suction position to the feeding position. It is characterized by having.

In the invention described in claim 6, when the suction container having the sheet adsorbed on the sheet facing surface is swung to the feeding position, the front end of the sheet adsorbed on the sheet facing surface is separated by another separation mechanism. While being separated from the front end of the sheet, the vicinity of the front end of the sheet adsorbed on the sheet facing surface is pressed by the pressing means. Therefore, when the suction container starts swinging, the pressure applied by the pressing means from the front end of the sheet separated by the separation mechanism acts between the sheet adsorbed on the sheet facing surface and the sheet contacting this sheet. Then, the negative pressure generated between the two sheets is canceled.

[0023]

FIG. 1 is a diagram showing a schematic configuration of a copying machine which is a sheet processing apparatus to which a sheet feeding apparatus according to an embodiment of the present invention is applied. The copier 1 is provided with an image reading device 6 provided with a light source 3, a mirror 4 and a lens 5 below a document table 2 arranged on an upper surface, and rotatably supports a photosensitive drum 7 in a central portion thereof. A process unit 13 is provided around the photoreceptor drum 7 and includes a charging charger 8, a developing device 9, a transfer charger 10, a cleaner 11, and a discharging lamp 12.

A sheet cassette 1 is provided on one side of the copying machine 1.
4 is configured, and on the other side surface, a paper discharge unit 17 with a paper discharge tray 16 is configured. Inside the copier 1, a paper delivery path 18 from the paper supply unit 15 to the paper discharge unit 17 via the process unit 13 is formed, and a fixing device is provided between the process unit 13 and the paper discharge unit 17. 19 are arranged.

When copying an original image in the copying machine 1 having the above-described configuration, the light source 3 and the mirror 4 of the optical system device 6 are moved horizontally relative to the original placed on the original table 2. Then, the reflected light of the light of the light source 3 on the image surface of the document is distributed to the surface of the photosensitive drum 7 via the mirror 4 and the lens 5.

Prior to exposure of the reflected light, the surface of the photosensitive drum 7 is uniformly charged with a single-polarity charge by corona discharge of the charger 8, and the surface of the photosensitive drum 7 exposed to the original reflected light is exposed. An electrostatic latent image is formed on the surface by photoconductive action. The surface of the photosensitive drum 7 on which the electrostatic latent image is formed is opposed to the developing device 9, and the developer supplied from the developing device 9 visualizes the electrostatic latent image into a developer image. The paper fed from the paper feed unit 15 is guided between the photosensitive drum 7 and the transfer charger 10 in synchronization with the rotation of the photosensitive drum 7, and the corona discharge of the transfer charger 10 causes the surface of the surface of the photosensitive drum 7 to be discharged. The developer image is transferred to the surface of the paper.
The sheet on which the developer image has been transferred is heated and pressed in the fixing device 19, and the developer image is melted and fixed on the surface of the sheet. The sheet that has passed through the fixing device 19 is discharged to the sheet discharge tray 16 of the sheet discharge unit 17.

On the other hand, the surface of the photosensitive drum 7 that has passed the position facing the transfer charger 10 is subjected to removal of the residual developer by the cleaner 11 and removal of the residual charge by the charge removing lamp 12 and then to the charging charger 8. Oppositely, they are repeatedly subjected to charging of a single-polarity charge, formation of an electrostatic latent image by exposure, visualization by supplying a developer, transfer of the developer, removal of the residual developer, and removal of the residual charge.

The sheet feeding device 21 according to the embodiment of the present invention is provided in the sheet feeding section 15 of the copying machine 1 configured as described above.
Is arranged. The sheet feeding device 21 is provided on the upper side of the sheet feeding cassette 14 on the sheet feeding side, and the sheet positioned at the top of the plurality of sheets stacked and stored inside the sheet feeding cassette 14. Is provided with a swing duct 22 opposed to the upper surface.

FIG. 2 is a perspective view showing the structure of the sheet feeding apparatus. The sheet feeding device 21 includes a swing duct 22, which is a suction container of the present invention, a fixed duct 23, which is a discharge mechanism of the present invention, a sheet conveying unit 26, which is a conveying member of the present invention, and an air control unit described later. Have been. The swing duct 22 is connected to the sheet cassette 14.
A feeding roller 31 is included above the sheet housed therein so as to be swingable. That is, the rear end of the swing duct 22 is fitted to a vacuum house 28 attached to the tip of a suction duct 27 extending above the sheet from the upstream side in the sheet feeding direction. It is swingable about the center of rotation.

The rotation of the swing motor 30 is transmitted to the swing duct 22 via a link 29. Swing motor 3
0 rotates in both forward and reverse directions, and when the swing motor 30 rotates forward, the front end of the swing duct 22 descends, and the swing motor 3 rotates.
When 0 is reversed, the front end of the swing duct 22 rises. Feed roller 3 inside swing duct 22
1 is supported at a position fixed by a bearing 32 extending from the vacuum house 28. Therefore, the swing duct 22 swings independently of the feed roller 31. The rotation of a feed motor 33 provided outside the swing duct 22 is transmitted to the feed roller 31 via a belt 34, a drive shaft 35, and a belt 36. Seat facing surface 2 which is the bottom surface of swing duct 22
A hole 22b is opened in 2a. When the swing duct 22 moves upward, a part of the feed roller 31 is exposed below the swing duct 22 from the hole 22b.

The paper transport section 26 includes upper and lower paper guides 24.
a, 24b and a pair of upper and lower transport rollers 25a, 25
b. The paper fed by the rotation of the feed roller 31 is sandwiched between the transport rollers 25a and 25b via the space between the paper guides 24a and 24b, and is transported to the above-described copying process unit by the rotation of the transport rollers 25a and 25b. You. The fixed duct 23 is attached to the end of a discharge duct 37 extending from the downstream side in the paper feeding direction to the front end side of the paper stored in the paper cassette 14, and is attached to the paper stored in the paper cassette 14. A nozzle 38, which is a discharge port of the present invention, is formed on the facing surface. Further, a portion of the swing duct 22 facing the fixed duct 23 is formed as an air flow surface 22c. This air flow surface 22c can be constituted by an inclined surface or a partial arc surface.

FIG. 3 is a diagram showing a configuration of an air control unit which constitutes a part of the sheet feeding device. Air control unit 41
Are a suction fan 42, a suction valve 43, a suction solenoid 44, a discharge fan 45, a discharge valve 46, a discharge solenoid 47, a pressure release valve 48, and a pressure release solenoid 4.
9 is provided. When the suction solenoid 44 is turned off and the suction valve 43 is opened, the air in the suction duct 27 is sucked by the suction fan 42, and a negative pressure acts on the vacuum house 28 and the swing duct 22. Air is sucked into.

When the discharge solenoid 47 is turned off and the discharge valve 46 is opened, air flows into the discharge duct 37,
The inside of the fixed duct 28 is pressurized and air is discharged from the nozzle 38. When the pressure release solenoid 49 is turned on and the pressure release valve 48 is opened, the inside of the vacuum house 28 and the swing duct 22 is pressurized via the suction duct 27, so that air is not sucked into the swing duct 22 from the hole 22 b.

FIG. 4 is a block diagram showing a configuration of a control section of the sheet feeding apparatus. The control unit of the sheet feeding device 21 includes a CPU 61 having a ROM 62 and a RAM 63.
A suction fan 42, a discharge fan 45, a swing motor 30, a feed motor 33, a suction solenoid 44, a discharge solenoid 47, a pressure release solenoid 49, a paper detection sensor 51, a paper feed detection sensor 52 via an interface (not shown). And input / output devices such as the home position sensor 53 are connected. Further, the CPU 61 is connected to a master CPU 60 constituting a control unit of the copying machine 1. C
The PU 61 controls and controls each input / output device according to a program written in the ROM 62 in advance, and stores data input / output during this time in a predetermined memory area of the RAM 63.

That is, the CPU 61 receives a paper feed command input from the master CPU 60 at a predetermined timing and a detection signal input from the paper detection sensor 51, the paper feed detection sensor 52, and the home position sensor 53.
Suction fan 42, discharge fan 45, swing motor 30, feed motor 33, suction solenoid 44, discharge solenoid 4
7 and a drive signal for the pressure release solenoid 49.
The sheet detection sensor 51 is turned on when detecting that the sheet is attracted to the sheet facing surface 22a of the swing duct 22. The paper feed detection sensor 52 includes the transport rollers 25a, 25
The presence or absence of a sheet at the position b is detected. The home position sensor 53 is turned on in a state where the swing duct 22 is located at the feeding position which is the home position.

FIG. 5 is a flowchart showing a processing procedure of the control section of the sheet feeding apparatus. Sheet feeding device 2
The CPU 61 that constitutes one control unit includes a master CPU 60.
Is waiting for the input of a paper feed command from the master CPU 60 (s1).
Then, the discharge fan 45 is driven (s2), and the suction solenoid 44, the discharge solenoid 47, and the pressure release solenoid 49 are turned off (s3). As a result, the inside of the swing duct 22 is made negative, and the inside of the fixed duct 23 is pressurized.

Next, the CPU 61 sets the paper detection sensor 5
1 is turned on, the swing motor 30 is rotated forward to lower the swing duct 22 (s4, s5). When the paper detection sensor 51 is turned on, the swing motor 30 is turned reversely until the home position sensor 53 is turned on. Duct 22
Is raised to the feeding position (s6, s7). When the home position sensor 53 is turned on, the CPU 61 stops the swing motor 30 (s8), and
Is driven to start paper feeding (s9). When the front end of the fed paper reaches the transport rollers 25a and 25b and the paper feed detection sensor 52 is turned on (s10), the CPU 61
Turns on the suction solenoid 44, the discharge solenoid 47 and the pressure release solenoid 49 (s11), and turns on the suction valve 4.
3 and the discharge valve 46 are closed, and the pressure release valve 48 is opened to pressurize the inside of the swing duct 22.

Thereafter, the trailing edge of the sheet is set at the transport rollers 25a,
25b and the paper feed detection sensor 52 is turned off (s
12), the CPU 61 turns off the feed motor 33 and stops the rotation of the feed roller 31 (s13). The CPU 61
Until the paper feed stop command is input from the CPU 60, the above s
The processes of 3 to s13 are repeatedly executed (s14), and when the sheet feed stop command is input, the suction fan 42 and the discharge fan 4
5. The suction solenoid 44, the discharge solenoid 47, and the pressure release solenoid 49 are turned off (s15).

As described above, in the sheet feeding apparatus 21, the swing duct 22 in a state where the inside is at a negative pressure is lowered to the suction position by the processing of s1 to s5, and the hole formed in the sheet facing surface 22a is formed. The sheet is attracted to the sheet 22b (see FIG. 6A). Thereafter, the swing duct 22 in a state where the sheet is adsorbed to the hole 22b is raised to the feeding position by the processes of s6 to s8 (see FIG. 6B).

At this time, a fixed duct 23 is provided at the front end of the sheet.
The air is discharged from the nozzle 38 of FIG. Further, as described above, the portion of the swing duct 22 facing the fixed duct 23 is a partially arcuate air flow surface 22c. Part of the air discharged from the nozzle 38 is guided to the sheet facing surface 22a along the air flow surface 22c, and comes into contact with the front end of the sheet adsorbed on the hole 22b of the sheet facing surface 22a. The swing duct 22 is connected to the drive shaft 3 near the rear end.
5, the swinging duct 22 swings from the suction position to the feeding position.
The angle between 2c and the direction in which the air is discharged from the nozzle 38 gradually changes, and during this time, the contact angle of the air to the front end of the sheet adsorbed on the sheet facing surface 22a also gradually changes.

Therefore, as shown in FIG. 6B, this is the case where a plurality of sheets are attracted to the swing duct 22 by the action of static electricity or the like. Even when the angle between the discharge duct and the discharge direction changes variously, at any timing during which the swing duct 22 swings from the suction position to the feeding position, a plurality of sheets of paper adsorbed on the swing duct 22 are removed. The air discharged from the nozzle 38 can flow into each gap without fail. By causing air to flow into the gaps between the plurality of sheets in this manner, sheets having a relatively weak suction force on the swing duct 22 other than the top sheet are separated from the top sheet,
It is possible to reliably prevent a plurality of sheets from being fed at once.

By the processing of s10 and s11, when the paper feed detection sensor 52 detects that the fed paper has reached the transport rollers 25a and 25b, the inside of the swing duct 22 and the inside of the fixed duct 23 are detected. Is the air control unit 41
And the negative pressure does not act inside the swing duct 22 (see FIG. 6C). Therefore, the sheet is not attracted to the hole 22b of the swing duct 22, and the frictional resistance of the sheet fed by the rotation of the feed roller 31 from the sheet facing surface 22a can be reduced. It is possible to prevent the feeding force from being reduced and the paper from being damaged.

Thereafter, by the processing of s12 and s13, when the paper feed detection sensor 52 detects that the rear end of the fed paper has passed the transport rollers 25a and 25b, the rotation of the feed roller 31 is started. The operation is stopped (see FIG. 6D).

A sensor is provided for detecting that the swing duct 22 has risen to a feeding start position at which the front end of the sheet adsorbed on the swing duct 22 does not come into contact with the air discharged from the fixed duct 23. The process of starting the rotation of the feed roller 31 after detecting the swing duct 22 at the feeding start position may be inserted between the processes of s6 and s7, and the process of s9 may be deleted. By this processing, the swing duct 2
Sheet feeding can be started before the sheet 2 reaches the home position, and the sheet feeding work time can be reduced.

In the sheet feeding apparatus according to this embodiment, as shown in FIG. 6A, the swing center of the swing duct 22 is disposed above the uppermost surface of the stacked sheets. As a result, the uppermost sheet adsorbed by the swing duct 22 moves obliquely upward with respect to the lower sheet by the swing of the swing duct 22, thereby increasing the separation between the uppermost sheet and the next sheet. Can be enhanced. Further, since the swing duct 22 moves to the fixed duct 23 side when swinging, the swing duct 22
As a result, the air pressure between the front end of the sheet and the fixed duct 23 is increased, so that when a plurality of sheets are adsorbed to the swing duct 22, the air easily enters between the sheets, and is adsorbed to the swing duct 22. The separation of the sheet after the separation is also improved.

FIG. 7 is a partial sectional view showing the structure of a feeding roller applied to the sheet feeding apparatus. The feed roller 31 is configured by covering a surface of a plurality of hollow rollers 31b connected by a shaft 31a with a rubber roller 31c. The hollow roller 31b and the rubber roller 31c include:
A plurality of through holes 31d and 31e are formed, and air freely flows through the hollow roller 31b and the rubber roller 31c. Therefore, the swing duct 22 is moved to the position shown in FIG.
(C) and (D) at the feeding position,
In a state in which a part of the swing duct 1 is exposed from the hole 22b, the air below the swing duct 22 flows through the feed roller 31 into the swing duct 22 due to the negative pressure acting on the swing duct 22. I do.

With this configuration, the sheet is attracted to the surface of the feed roller 31 so that a sufficient feeding force can be applied to the sheet, and a portion of the opening of the hole 22b where the feed roller 31 is not located. , The frictional force acting on the sheet from the sheet facing surface 22a can be reduced, and the sheet can be fed reliably.

FIG. 8 is a diagram showing a configuration of a main part of a sheet feeding apparatus according to an embodiment of the present invention.
In the sheet feeding device according to this embodiment, as shown in FIG.
At the positions corresponding to both ends in the direction orthogonal to the sheet feeding direction of the sheets of each size, grooves 9 are formed in parallel with the sheet feeding direction.
1 is formed. The upper end of the groove 91 is
In (c), the swing duct 22 is located at a position facing the nozzle 38 of the fixed duct 23 at least while swinging from the suction position to the feeding position. The lower end of the groove 91 is located near the front end position of the sheet adsorbed on the sheet facing surface 22a of the swing duct 22.

With this configuration, as shown in FIG. 8B, the air discharged from the nozzle 38 of the fixed duct 23 is guided through the groove 91 to the vicinity of the front end of the sheet adsorbed on the sheet facing surface 22a. , And collides directly with the air discharged from the nozzle 38 near the front end of the sheet. For this reason, the air pressure near the front end of the sheet adsorbed on the sheet facing surface 22a increases, and the air expands in this portion, and the sheet facing surface 2a
When a plurality of sheets are attracted to 2a, the gap at the front end of the plurality of sheets is enlarged, and sufficient air can be caused to flow into the gap between each sheet to separate each sheet. The other sheets can be reliably separated from the upper sheet, and only the uppermost sheet can be fed accurately.

FIG. 9 is a view showing the shape of the nozzle of the fixed duct of the sheet feeding apparatus. A plurality of nozzles 38 having a vertically long rectangle are formed on a surface of the fixed duct 23 facing the front end of the sheet. The length of the nozzle 38 in the vertical direction is sufficient for the sheet located at the bottom of the plurality of stacked sheets and the sheet adsorbed on the swing duct 22 at the feeding position. The length is set so that the air of the air volume can be discharged. Thereby, each of the plurality of sheets can be sufficiently separated before the uppermost sheet is sucked by the swing duct 22, and when a plurality of sheets is sucked on the sheet facing surface 22a. While the swing duct 22 swings from the suction position to the feeding position, the uppermost sheet can be reliably separated from the other sheets.

FIG. 10 is a diagram showing the shape of the nozzle of the fixed duct provided in the sheet feeding device according to the fourth embodiment of the present invention. In the sheet feeding device according to this embodiment, the sheet facing surface 23a of the fixed duct 23 includes:
A slit-shaped nozzle 81 that is inclined downward from the center toward both side ends is formed.

With this configuration, while the swing duct 22 swings from the suction position to the feeding position, the front end of the sheet adsorbed on the sheet facing surface 22a of the swing duct 22 moves upward, so that the sheet moves in the feeding direction. Regardless of the width of the sheet in the orthogonal direction, the air discharged from the nozzle 81 abuts in order from the corner at the front end of the sheet toward the center at any timing during the swing of the swing duct 22. Thus, a plurality of sheets can be efficiently separated.

FIG. 11 is a diagram showing another configuration of the nozzle formed in the fixed duct in the sheet feeding device. In the configuration shown in FIG. 11, an upper nozzle 38a and a lower nozzle 38b are formed on the sheet facing surface of the fixed duct 23. The air discharge direction of the upper nozzle 38a is downward, and the air discharge direction of the lower nozzle 38b is substantially horizontal.

With this configuration, the air discharged from the upper nozzle 38a is supplied to the air flow surface 22 of the swing drum 22.
c can reliably contact the front end of the sheet adsorbed on the sheet facing surface 22a via the sheet facing surface 22a.
It is possible to reliably separate a plurality of sheets adsorbed on the sheet. In addition, the air discharged from the lower nozzle 38b can be reliably brought into contact with the front ends of a plurality of stacked papers, and the sheet facing surface 22 of the swing drum 22 can be contacted.
It is possible to reliably separate the front end portions of a plurality of sheets before being attracted to the sheet a.

FIG. 12 is a view showing still another configuration of the nozzle formed in the fixed duct in the sheet feeding apparatus. In the configuration shown in FIG. 12, the nozzle 38 formed on the sheet facing surface of the fixed duct 23 is provided with a shutter 38c for increasing or decreasing the opening range of the nozzle 38, and a lifting mechanism 38d for moving the shutter 38c up and down. Lifting mechanism 38
d is constituted by a motor, a transmission mechanism and a position detection means, converts the rotation of the motor into a linear operation of the shutter 38c through a transmission mechanism including a rack gear and a pinion gear, and detects the position based on the rotation amount of the motor. By detecting the position of the shutter 38c by the means, the shutter 38c is moved in accordance with the vertical swing of the swing duct 22.
Up and down.

With this configuration, the opening range of the nozzle 38 of the fixed duct 23 is increased or decreased in accordance with the range of the nozzle 38 to which the air flow surface 22c of the swing duct 22 is opposed, and is attracted to the sheet facing surface 22a of the swing duct 22. The air can be effectively brought into contact with the paper. In particular, when the swing duct 22 reaches the feeding position, the opening area of the nozzle 38 is minimized, the discharge pressure of air from the nozzle 38 is increased, and a plurality of sheets adhere to the sheet facing surface 22a of the swing duct 22. In such a case, these sheets can be reliably separated.

FIG. 13 is a view showing still another configuration of the nozzle formed in the fixed duct in the sheet feeding apparatus. In the configuration shown in FIG. 13, the horizontal nozzle 38e having a width in a direction perpendicular to the feeding direction of the minimum size sheet that can be fed by the sheet feeding device, and the maximum size that can be fed by the sheet feeding device from both ends of the horizontal nozzle 38e. And inclined nozzles 38f continuous to both end positions in a direction perpendicular to the feeding direction of the sheet of the size.

With this configuration, for the sheets of all sizes that can be fed by the sheet feeding device, the swing duct 22 is attracted to the sheet facing surface 22a of the swing duct 22 while swinging from the suction position to the feeding position. By moving the front end of the sheet upward, the air discharged from the nozzle 81 is sequentially brought into contact from the corner of the front end of the sheet toward the center, thereby efficiently separating a plurality of sheets. In addition, the swinging range of the swing duct 22 can be narrowed by reducing the vertical dimension of the fixed duct 23, and the device can be downsized.

FIG. 14 is a view showing a configuration of a fixed duct of the sheet feeding apparatus according to the fifth embodiment of the present invention. The sheet feeding device according to this embodiment has the configuration shown in FIG.
The inclined nozzle 38f in the configuration shown in FIG.
3 is formed so as to be movable in a direction perpendicular to the sheet feeding direction. That is, as shown in FIG.
A parallelogram opening 38g is formed at both ends of the horizontal nozzle 38e in the configuration shown in FIG.
A movable plate 100 having an inclined nozzle 38f formed outside is provided so as to be movable in the horizontal direction. The movable plate 100 is formed with a locking piece 100a that protrudes and engages with the locking portion 101a of the paper mounting table 101 on which the side surface regulating portion 102 is formed. The paper mounting table 101 is formed into two parts, left and right, and the left and right paper mounting tables 101 are pinion gears 103.
Are interlocked with each other in a direction approaching or separating from each other in accordance with the width of the sheet placed in the direction perpendicular to the feeding direction.

With the above arrangement, when the left and right paper placing tables 101 are moved in accordance with the width of the paper to be placed, the moving plate 100 is also moved, and the moving plate 100 is moved to the vicinity of both ends of the paper. The lower ends of the formed inclined nozzles 38f face each other. Therefore, irrespective of the size of the paper placed on the paper placing table 101, the swing duct 22 is moved upward from the suction position to the feeding position and inward from near both ends of the front end of the paper sucked to the swing duct 22. The air can be sequentially brought into contact with each other, and when a plurality of sheets are attracted to the swing duct 22, the respective sheets can be reliably separated and only the uppermost sheet can be fed accurately.

FIG. 15 is a view for explaining the configuration and operation of a sheet feeding apparatus according to another embodiment of the present invention. The sheet feeding apparatus according to this embodiment includes a solenoid 7 provided with an actuator 73 that pivotally supports an alignment plate 71 at a front end of a sheet mounting table 70 and engages one end of the alignment plate 71.
2 is provided. Due to the air blown from the fixed duct 23 at the time of feeding the paper, the positions of the front ends of the plurality of papers stacked and mounted on the paper mounting table 70 may not be aligned, and FIG. As shown in FIG. 7, the sheet adsorbed on the feed roller 31 together with the uppermost sheet may drop during swinging of the swing duct 22 and may not be aligned with the position of another sheet on the sheet mounting table 70. In these cases, if the misalignment of the front end position of the sheet is left unchecked, the interval between the front end of the sheet and the fixed duct 22 becomes improper at the next sheet feeding, and the sheets are surely separated one by one. Can not be fed.

Therefore, in this sheet feeding apparatus, the front end of the uppermost fed sheet reaches the sheet feed detection sensor 52,
When the suction of the paper by the swing duct 22 and the discharge of the air from the fixed duct 23 are stopped (s1 in FIG. 5).
0, s11), as shown in FIG. 15 (B), the solenoid 72 is driven for a certain time to rotate the matching plate 71,
The front end positions of a plurality of sheets on the sheet mounting table 70 are aligned. Thereby, the interval between the front end of the sheet and the fixed duct 23 can always be properly maintained at the time of sheet feeding, and the sheets can be reliably separated and fed one by one.

FIG. 16 is a view showing a configuration of a sheet feeding apparatus according to an embodiment of the present invention. The sheet feeding device according to this embodiment includes an air pulse generator 12 instead of the fixed duct 23 in the configuration shown in FIG.
1 is provided, and a separation claw 123 is provided to abut on a corner at the front end on the upper surface of the paper stacked and mounted on the paper mounting table 122. Air pulse generator 121 and separation claw 1
Since the configuration other than 23 is the same as the configuration shown in FIG.
The same reference numerals as those in FIG. 2 denote the same parts, and a description thereof will be omitted.

The air pulse generator 121 corresponds to the pressurizing means of the present invention, and discharges pressurized air to the vicinity of the front end of the paper mounting table 122 for a short period of time, and pressurizes this portion. The separation claw 123 corresponds to the separation mechanism of the present invention,
The front end of the uppermost sheet adsorbed on the sheet facing surface 22a of the swing duct 22 is separated from the front end of the next sheet.

In the sheet feeding apparatus, the uppermost sheet is adsorbed on the sheet facing surface 22a of the depressurized swing duct 22, and the swing duct 2
When 2 starts to ascend to the feeding position, the air pulse generator 121 is driven for a certain period. When the swing duct 22 that has adsorbed the sheet on the sheet facing surface 22a starts to move up to the feeding position, the front end of the uppermost sheet that has been adsorbed on the sheet facing surface 22a has the separation claw 123.
Is separated from the front end of the next sheet by the
The pressure applied by the air pulse generator 121 from the front end of the sheet separated by 23 acts between the uppermost sheet and the next sheet, thereby canceling the negative pressure generated between the two sheets. You. Therefore, the uppermost sheet and the next sheet are reliably separated, and only the uppermost sheet can be fed accurately. Further, according to this configuration, there is no need to provide a fixed duct that discharges air that separates the front end of the stacked sheets of paper, so that the configuration of the air control unit can be simplified. Further, the air pulse generator 121 can be constituted by, for example, an air compressor.

In each of the embodiments described above, the sheet feeding apparatus for feeding a sheet in the sheet feeding section of the copying machine has been described as an example. Even in devices with sheet processing functions other than sheet feeding devices and copiers that feed documents,
The present invention can be similarly implemented.

[0067]

According to the first aspect of the present invention, when a plurality of sheets are attracted to the sheet facing surface, the suction container swings even if the front end of the sheet is deformed. Air can flow into each gap of a plurality of sheets at any time during the period, and only one sheet in contact with the sheet facing surface of the suction container can be accurately fed. .

According to the second aspect of the present invention, after the front end of the sheet reaches the conveying member, the state of suction of the sheet with respect to the sheet facing surface of the suction container can be positively released. In addition, it is possible to reduce the frictional resistance acting on the sheet moving in the feeding direction by the conveying member from the sheet facing surface, thereby improving the sheet feeding state. According to the invention described in claim 3, the air discharged from the discharge port is guided to the vicinity of the front end of the sheet adsorbed on the sheet facing surface via the groove, and is discharged directly from the discharge port to the vicinity of the sheet front end. Due to the collision with the air, the air pressure in the vicinity of the front end of the sheet adsorbed on the sheet facing surface is increased to expand the air in this portion, whereby a plurality of sheets are adsorbed on the sheet facing surface of the suction container. In this case, the gap at the front end of the plurality of sheets can be enlarged, and sufficient air flows into the gap between each sheet to separate each sheet, and only one sheet is accurately fed. be able to.

According to the fourth aspect of the present invention, the front end portion of the sheet sucked on the sheet facing surface of the suction container while the suction container sucking the sheet on the sheet facing surface swings from the suction position to the feeding position. Is moved up and down, regardless of the width of the sheet in the direction orthogonal to the feeding direction, the air discharged from the discharge port at any timing during the swinging of the suction container at the front end of the sheet. When a plurality of sheets are adsorbed on the sheet facing surface, it can be reliably separated from each other and only one sheet can be fed accurately. .

According to the fifth aspect of the present invention, the discharge port of the discharge mechanism is moved according to the sheet size in the direction orthogonal to the feeding direction, so that the discharge is performed regardless of the size of the sheet to be fed. The air discharged from the outlet can reliably contact the front end of the sheet, and only one sheet can be fed accurately.

According to the invention described in claim 6, when the suction container having the sheet sucked on the sheet facing surface is swung to the feeding position, the front end of the sheet sucked on the sheet facing surface is separated by the separating mechanism. The sheet is separated from the front end of the sheet, and the vicinity of the front end of the sheet adsorbed on the sheet facing surface is pressed by the pressing means, so that at the start of swinging of the suction container, the sheet is separated from the front end of the sheet separated by the separation mechanism. The pressure applied by the pressurizing means acts between the sheet adsorbed on the sheet facing surface and the sheet in contact with this sheet to cancel the negative pressure generated between the two sheets, and a plurality of sheets of the suction container Adsorption to the sheet facing surface can be reliably prevented.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a copying machine which is a sheet processing apparatus to which a sheet feeding apparatus according to an embodiment of the present invention is applied.

FIG. 2 is a perspective view illustrating a configuration of the sheet feeding device.

FIG. 3 is a diagram illustrating a configuration of an air control unit that forms a part of the sheet feeding apparatus.

FIG. 4 is a block diagram illustrating a configuration of a control unit of the sheet feeding device.

FIG. 5 is a flowchart illustrating a processing procedure of a control unit of the sheet feeding apparatus.

FIG. 6 is a diagram illustrating an operation state of a swing duct of the sheet feeding device.

FIG. 7 is a partial cross-sectional view illustrating a configuration of a feeding roller applied to the sheet feeding apparatus.

FIG. 8 is a diagram illustrating a configuration of a main part of a sheet feeding apparatus according to an embodiment of the invention described in claim 3;

FIG. 9 is a diagram illustrating a shape of a nozzle of a fixed duct of the sheet feeding device.

FIG. 10 is a view showing a shape of a nozzle of a fixed duct provided in the sheet feeding device according to the embodiment of the invention described in claim 4;

FIG. 11 is a diagram showing another configuration of a nozzle formed in a fixed duct in the sheet feeding device.

FIG. 12 is a view showing still another configuration of a nozzle formed in a fixed duct in the sheet feeding device.

FIG. 13 is a view showing still another configuration of a nozzle formed in a fixed duct in the sheet feeding device.

FIG. 14 is a diagram illustrating a configuration of a fixed duct of the sheet feeding device according to the embodiment of the invention described in claim 5;

FIG. 15 is a diagram illustrating the configuration and operation of a sheet feeding apparatus according to another embodiment of the present invention.

FIG. 16 is a diagram showing a configuration of a sheet feeding apparatus according to an embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1-Copying machine 14-Paper cassette 15-Paper feeding unit 21-Sheet feeding device 22-Swing duct (suction container) 22a-Sheet facing surface 22b-Hole 22c-Air flow surface 23-Fixed duct (Discharge mechanism) 29 -Link (oscillation mechanism 30)-Oscillation motor (oscillation mechanism) 31-Feed roller 38-Nozzle 41-Air control unit

Claims (6)

[Claims] An image forming apparatus includes a sheet-facing surface facing a sheet in a sheet storage portion, and is supported swingably up and down independently of the feeding roller with a feeding roller included therein. A suction container having a hole including an exposed portion of the feeding roller, between a suction position where the hole of the sheet facing surface contacts the sheet and a feeding position where a part of the feeding roller is exposed from the exposed portion. A swing mechanism for swinging the suction container, a suction mechanism for reducing the pressure in the suction container while at least the suction container swings from the suction position to the feeding position, and a discharge port facing the front end of the sheet during this time. A discharge mechanism for discharging air,
In the sheet feeding device provided with, the suction container is provided with an air circulating surface facing the discharge port of the discharge mechanism and guiding air discharged from the discharge port to the front end of the sheet facing surface. Sheet feeding device. 2. The apparatus according to claim 1, further comprising a conveying member for sandwiching the sheet at a downstream side of the suction container in the feeding direction, and a pressurizing mechanism for pressurizing the inside of the suction container when the sheet reaches the conveying member. 3. The sheet feeding device according to 1. 3. The sheet feeding apparatus according to claim 1, wherein a groove parallel to a sheet feeding direction is formed on the air flow surface. 4. The sheet feeding device according to claim 1, wherein the discharging mechanism has a discharging port inclined downward from a central portion in a direction perpendicular to the sheet feeding direction toward both side ends. apparatus. 5. The sheet feeding apparatus according to claim 1, wherein said discharge mechanism comprises a moving mechanism for moving the discharge port in accordance with a size in a direction orthogonal to a sheet feeding direction. . 6. A sheet facing surface which faces a sheet in a sheet storage portion, and is supported vertically swingably independently of the feeding roller in a state in which the feeding roller is included, and is provided on the sheet facing surface. A suction container having a hole including an exposed portion of the feeding roller, between a suction position where the hole of the sheet facing surface contacts the sheet and a feeding position where a part of the feeding roller is exposed from the exposed portion. A swing mechanism for swinging the suction container, a suction mechanism for depressurizing the inside of the suction container at least while the suction container swings from the suction position to the feeding position, and a front end of the sheet adsorbed on the sheet facing surface of the suction container And a separation mechanism for separating the sheet from the front end of another sheet.When the suction container starts swinging from the suction position to the feeding position, the sheet container faces the sheet facing surface of the suction container. Add the area near the front end of the sucked sheet. A sheet feeding device comprising a pressurizing means for pressing.