CN108861693B

CN108861693B - Sheet feeding device and image forming apparatus

Info

Publication number: CN108861693B
Application number: CN201810418626.2A
Authority: CN
Inventors: 中村元
Original assignee: Konica Minolta Inc
Current assignee: Konica Minolta Inc
Priority date: 2017-05-09
Filing date: 2018-05-04
Publication date: 2020-03-06
Anticipated expiration: 2038-05-04
Also published as: US20180327202A1; JP7325922B2; JP2018188272A; CN108861693A

Abstract

The invention provides a paper feeding device and an image forming apparatus capable of stably feeding paper even under the condition that the paper is difficult to float. The disclosed device is provided with: a paper loading table (511) for storing paper in a stacked state; a separated air blowing section (52) that blows air from the front end side in the paper feeding direction of the loaded paper; floating air blowing sections (53, 54) which are disposed on both sides in a direction parallel to the surface of the paper placed thereon and orthogonal to the paper feeding direction and blow air onto the paper; an adsorption unit (56) that adsorbs the uppermost sheet that has floated; wind direction switching members (534, 544) for changing the blowing direction of the floating air blowing part to any direction from the direction towards the front end side of the paper feeding direction of the loaded paper to the direction towards the rear end side; and a control unit (400) for controlling the wind direction switching member to change the wind blowing direction of the floating air blowing unit according to at least one of the basis weight and size of the paper and the floating state of the paper.

Description

Sheet feeding device and image forming apparatus

Technical Field

The invention relates to a paper feeding device and an image forming apparatus.

Background

Conventionally, in an image forming apparatus for forming an image on a sheet, there is known an air suction type sheet feeding apparatus for storing sheets in a stacked state and feeding the sheets to an image forming section.

The air suction type paper feeding device includes: a floating air blowing part for blowing air to the paper placed on the paper placing part from two sides along the direction orthogonal to the paper conveying direction to make the paper on the upper part float; a separated air blowing section for blowing air from a front end side of the uppermost sheet in the conveying direction to separate the uppermost sheet from the other sheets; and a belt conveying mechanism for conveying the stacked paper sheets in the conveying direction by the conveying belt. By sucking only the uppermost sheet by these mechanisms and separating the sheet from the other sheets reliably, the sheets can be fed out one by one to the sheet conveying path.

However, when the paper is heavy or large, the floating force generated by the floating air and the separated air may be insufficient, and the paper may not be fed.

In order to solve such a problem, patent document 1 discloses a technique of improving the levitation force by blowing air in a direction in which the levitation air and the separation air collide with each other. In this case, since the floating state of the sheet may be unstable due to the collision of air, a mechanism for sucking air from the rear end side of the sheet is provided.

Patent document 1: japanese patent laid-open No. 2014-169182

Under the condition that the sheet is hard to float, strong floating air needs to be blown onto the sheet, and if the invention described in patent document 1 is used, the collision of air needs to be further increased, and accordingly, air is sucked from the rear end side with a stronger suction force.

However, if the suction force becomes strong, the paper may be inadvertently sucked, and it is difficult to maintain the strength of the air and stabilize the air flow.

Disclosure of Invention

The present invention has been made in view of the above problems, and an object thereof is to provide a paper feeding device and an image forming apparatus capable of stably feeding paper even under a condition that paper is less likely to float.

In order to solve the above problem, the paper feeding device according to claim 1 includes:

a paper placing unit for storing paper in a stacked state;

a separated air blowing section for blowing air to the paper from the front end side of the loaded paper in the paper feeding direction;

a floating air blowing section for blowing air to the paper from both sides of the paper end orthogonal to the paper feeding direction of the loaded paper;

an adsorption part for adsorbing the floated uppermost paper;

an air direction switching unit that changes an air blowing direction of the floating air blowing unit to an arbitrary direction from a direction toward a front end side in a paper feeding direction of the loaded paper sheet to a direction toward a rear end side in the paper feeding direction of the loaded paper sheet; and

and a control unit for controlling the wind direction switching unit to change the blowing direction of the floating air blowing unit according to at least one of the basis weight and size of the paper and the floating state of the paper.

The invention described in claim 2 is characterized in that, in addition to the paper feeding device described in claim 1,

comprises a floating detection part for detecting the floating of the loaded paper,

when the floating of the paper is detected by the floating detection unit, the control unit changes the blowing direction of the floating air blowing unit to a direction toward the rear end side in the paper feeding direction of the loaded paper.

The invention described in claim 3 is the paper feeder described in claim 1 or 2,

when the floating of the paper sheet is not detected by the floating detection unit within a predetermined period from the start of paper feeding, the control unit changes the blowing direction of the floating air blowing unit to a direction toward the leading end side in the paper feeding direction of the paper sheet to be placed.

The invention described in claim 4 is the paper feeding device described in any one of claims 1 to 3,

the floating air blowing part can move in a direction parallel to the surface of the loaded paper and orthogonal to the paper feeding direction.

The invention described in claim 5 is the paper feeding apparatus according to any one of claims 1 to 4,

the floating air blowing part blows air obliquely upward to the surface of the paper.

The image forming apparatus according to claim 6 is characterized by comprising:

the paper feeding device according to any one of claims 1 to 5; and

an image forming section for forming a toner image on a sheet.

According to the present invention, it is possible to provide a paper feeding device and an image forming apparatus capable of stably feeding paper even under a condition where the paper is less likely to float.

Drawings

Fig. 1 is a diagram showing a schematic configuration of an image forming apparatus.

Fig. 2 is a block diagram showing a main functional configuration of the image forming apparatus.

Fig. 3 is a perspective view of a paper feed unit of the image forming apparatus.

Fig. 4 is a partially cut side view showing a feeding portion, an adsorbing portion, and a conveying portion of the paper feeding portion.

Fig. 5 is a plan view showing an operation of the air direction switching member of the paper feed unit.

Fig. 6 is a plan view showing the feeding unit, the suction unit, and the conveying unit of the paper feeding unit.

Fig. 7 is a side view showing a state of the paper during the paper feeding operation of the paper feeding unit.

Fig. 8 is a plan view for explaining the blowing direction of the floating air.

Fig. 9 is a flowchart showing an operation of the image forming apparatus.

Description of the reference numerals

A paper supply portion; a paper placing table (paper placing section); a separate air supply; 53. a floating air supply; 531. 541.. an air supply fan; 532. 542.. an air supply outlet; 533. 543.. nozzle; 534. a wind direction switching member (wind direction switching unit); 535. a shaft (wind direction switching section); 536. 546.. a gear pair (wind direction switching portion); 537. a motor (wind direction switching unit); a feeding portion; 557.. an adsorption detection portion (a floating detection portion); 557a.. detecting a body; 557b.. sensor; 56.. an adsorption portion; a handling portion; an image forming apparatus; an image forming apparatus main body; 400.. a control portion; a paper supply device.

Detailed Description

Hereinafter, embodiments according to the present invention will be described with reference to the drawings. However, the scope of the present invention is not limited to the following embodiments and the illustrated examples.

[ Structure of image Forming apparatus ]

Fig. 1 is an overall configuration diagram of an image forming apparatus 100 according to the present invention, and fig. 2 is a block diagram showing a functional configuration of the image forming apparatus 100.

As shown in fig. 1 and 2, the image forming apparatus 100 is mainly configured by an image forming apparatus main body 100a, an image reading apparatus SC, an automatic document feeder DF, an image processing section 30, a paper feeder 500, a control section 400, a storage section 410, and a communication section 420.

The image forming apparatus main body 100a includes an image forming section 10 including a photoreceptor 1, a charging section 2, an image exposing section 3, a developing section 4, a transfer section 5, a cleaning section 6, and the like, a fixing section 7, and a paper conveyance system. The sheet conveying system includes a first sheet feeding unit 11, a second sheet feeding unit 12, a sheet feeding cassette 13, a sheet discharging unit 14, a conveying path switching unit 15, a circulating re-sheet feeding unit 16, and a reverse sheet discharging unit 17.

The paper feeding device 500 includes three paper feeding units 50 arranged side by side in the vertical direction.

(1) Image processing unit

The image processing unit 30 performs various image processing on the image data and transmits the image signal to the image forming unit 10.

The original d placed on the original platen of the automatic document feeder DF is read by the optical system of the image reading device SC for one or both side images, and is read into the image sensor CCD. The image processing section 30 performs analog processing, a/D conversion, shading correction, image compression processing, and the like on the analog signal photoelectrically converted by the image sensor CCD, and then transmits the image signal to the image exposure section 3.

The control unit 400 can communicate with an external device (for example, a personal computer) connected to a communication network via the communication unit 420, and the image processing unit 30 may transmit an image signal received from the external device to the image exposure unit 3 under the control of the control unit 400.

(2) Image forming apparatus with a toner cartridge

In the image forming section 10, the photoreceptor 1 is charged by the charging section 2, an electrostatic latent image is formed by laser irradiation from the image exposing section 3, and the electrostatic latent image is developed into a toner image by the developing section 4. Then, the sheets P accommodated in the sheet feeding cassette 13 are conveyed from the first sheet feeding unit 11. The sheet P is conveyed in synchronization with the toner image by the second sheet feeding portion 12 formed of registration rollers. Then, the paper P is transferred with the toner image by the transfer unit 5 and fixed by the fixing unit 7. Further, the toner remaining after the transfer on the photoreceptor 1 is removed by the cleaning section 6.

Further, not only the sheet P accommodated in the sheet feeding cassette 13 but also the sheet P accommodated in the sheet feeding device 500 is supplied to the image forming apparatus main body 100a, and a toner image is transferred and fixed on the sheet P.

The fixed paper P is discharged outside the apparatus by the paper discharge portion 14. In the case of duplex printing, the paper P on which an image is formed on the first side is fed to the circulating re-feeding section 16 by the conveying path switching section 15, reversed, and again subjected to image formation on the second side in the image forming section 10, and then discharged to the outside of the apparatus by the paper discharge section 14. In the case of reverse paper discharge, the paper P branched from the normal paper discharge path is reversed in the reverse paper discharge unit 17, and then discharged outside the apparatus through the paper discharge unit 14.

(3) Sheet feeding device

Fig. 3 (a) is a schematic perspective view showing the paper feeding section 50 of the paper feeding device 500. As described above, the three paper feed units 50 are provided in the paper feed device 500 in a vertically aligned manner, but since they are configured in the same manner, one of the paper feed units 50 will be described here.

The paper feeding unit 50 includes a horizontally oriented paper placing table 511 as a paper placing unit on which a plurality of paper sheets P are placed in a stacked state, a rear end regulating member 512 provided behind the paper placing table 511, that is, on the upstream side in the paper feeding direction a, and a front end regulating member 513 provided in front of the paper placing table 511, that is, on the downstream side in the paper feeding direction a.

In the following description of the paper feed unit 50, a horizontal direction orthogonal to the paper feed direction a and a left-hand direction facing the paper feed direction a are referred to as "left", and a horizontal direction orthogonal to the paper feed direction a and a right-hand direction facing the paper feed direction a are referred to as "right".

The paper table 511 is supported in the paper feeding unit 50 so as to be vertically movable, and the rear end regulating member 512 and the front end regulating member 513 are fixedly provided in the paper feeding unit 50.

The height of the upper end of the front end restriction member 513 is slightly lower than the height of the upper end of the rear end restriction member 512. On the other hand, the paper-sheet-placing table 511 is moved up and down by an actuator not shown, and the controller 400 controls the actuator to maintain the uppermost part of the paper sheets P stacked on the paper-sheet-placing table 511 at a predetermined height slightly lower than the upper end of the front-end regulating member 513. The height control by the actuator is performed by sensing detection by a sensor, not shown, provided on the rear end restricting member 512 side for detecting the height of the uppermost sheet P.

Further, the paper table 511 can be lowered during non-paper feeding such as replenishment of the paper P.

A separate air blowing part 52 is provided on the downstream side of the front end regulating member 513 in the paper feeding direction a adjacent to the front end regulating member 513. Further, floating

air blowing portions

53 and 54 are provided on both left and right sides of the paper table 511, respectively, and inner side surfaces of the floating

air blowing portions

53 and 54 are vertically oriented on a plane and function as a regulating member for regulating the position of the paper in the left-right direction.

The floating

air blowing units

53 and 54 are provided so as to be movable in the left-right direction by an actuator not shown, and the control unit 400 controls the actuator so that the wall surfaces of the floating

air blowing units

53 and 54 are positioned to contact the end portions of the paper sheet in the width direction. The position in the left-right direction based on the actuator is determined based on the size information of the sheets placed on the sheet feeding unit 50 stored in the storage unit 410.

The separate air blowing unit 52 and the floating

air blowing units

53 and 54 are provided with blowing

fans

521, 531, and 541, respectively, and configured to blow air from the blowing

ports

522, 532, and 542.

Fig. 3 (B) is a main part configuration diagram of the floating air blowing unit 54. The floating air blowing unit 53 has the same configuration as the floating air blowing unit 54, and therefore, the configuration of the main part thereof is omitted.

As shown in fig. 3 (B), the floating

air blowing units

53 and 54 include

nozzles

533 and 543 that blow air from the left and right sides of the sheet P located at the uppermost part of the height restriction toward the sheet P in the horizontal direction or in a direction slightly inclined upward from the horizontal direction. The

air blowing ports

532 and 542 of the

nozzles

533 and 543 are formed such that the upper edge portions thereof are slightly lower than the sheet P positioned at the uppermost portion of the height restriction.

As shown in fig. 3, the floating

air blowing units

53 and 54 include wind

direction switching members

534 and 544,

shafts

535 and 545, gear pairs 536 and 546, and motors 537 and 547, respectively.

The wind

direction switching members

534 and 544 are disposed between the

air blowing ports

532 and 542 and the paper placed thereon, and are provided so as to be rotatable about the

shafts

535 and 545. The driving force based on the motors 537, 547 is transmitted to the

shafts

535, 545 through the gear pair 536, 546, so that the

shafts

535, 545 are rotated. Further, the wind

direction switching members

534, 544 are formed such that the upper edge portions thereof are higher than the sheet P positioned at the uppermost portion of the height restriction.

That is, the air is blown from the

air blowing ports

532 and 542, and the floating air is guided by the air

direction switching members

534 and 544 to be blown obliquely upward to the sheet surface of the upper sheet P in the stacked state, whereby the upper sheet P can be raised.

Fig. 4 is a cross-sectional view showing the configuration of the periphery of the leading end portion of the uppermost sheet P in the sheet feeding direction a of the sheet mounting table 511.

The separated air blowing section 52 includes a nozzle 523 for blowing air from an air blowing port 522 in a direction slightly inclined upward from the downstream side in the paper feeding direction a, and blows air to the downstream side tip end portion in the paper feeding direction a of the plurality of sheets floated by the floating

air blowing sections

53 and 54, whereby air can be blown between the floated sheet P and the other sheets, and the sheets other than the uppermost sheet P can be separated and lowered.

Fig. 5 shows a relationship between the direction of the wind direction switching member 544 and the air blowing direction.

Hereinafter, a direction perpendicular to the paper feeding direction a on the paper surface is referred to as a lateral direction b, and a side surface of the wind direction switching member 544 connected to the shaft 545 is referred to as a rotation surface 544 a.

For example, as shown in fig. 5 a, when the rotation surface 544a is stopped at an angle (θ 1) of 90 degrees with respect to the left-right direction b, the floating air is blown out from the air blowing port 542 in a direction orthogonal to the paper feeding direction a.

On the other hand, as shown in fig. 5B, when the rotation surface 544a is stopped at an angle (θ 2) toward the rear end side of the paper sheet with respect to the left-right direction B, the air is blown toward the upstream side (the rear end side of the paper sheet) with respect to the paper feed direction a.

As shown in fig. 5C, when the rotation surface 544a is stopped at an angle (θ 3) toward the front end side of the paper sheet with respect to the left-right direction b, the air is blown out toward the downstream side (the front end side of the paper sheet) with respect to the paper feed direction a.

That is, the blowing direction of the floating air is changed by driving the motors 537 and 547 under the control of the control unit 400 to rotate the wind

direction switching members

534 and 544.

Fig. 6 is a plan view of the feeding unit 55 and the suction unit 56. As shown in fig. 3, 4, and 6, a feeding unit 55 is provided above the paper table 511. Note that, in fig. 3, the feeding portion 55 is shown shifted to a position indicated by an arrow so as not to hide the surrounding structure, but actually, as shown in fig. 4, the feeding portion 55 is disposed above the end portion of the sheet mounting table 511 on the downstream side in the sheet feeding direction a.

The feeding section 55 includes four sets of belts 556 arranged in the left-right direction perpendicular to the paper feeding direction a on the paper feeding surface, a motor 551 as a paper feeding drive source for driving the belts 556, and a transmission gear train 552 interposed between each belt 556 and the motor 551.

Each belt 556 includes a large-diameter roller 553 provided on the upstream side in the paper feeding direction a, two small-

diameter rollers

554 and 555 provided on the downstream side in the paper feeding direction a, and a belt 556 stretched over these

rollers

553, 554, and 555. Then, a torque is applied to the large-diameter roller 553 of each belt mechanism from the motor 551 in the direction in which the lower portion of each belt 556 advances in the paper feeding direction a. In addition, a sprocket may be used instead of the

rollers

553, 554, 555.

Each belt 556 has a plurality of small holes penetrating the front and back surfaces over the entire surface thereof, and the paper P can be sucked to the lower portion of each belt 556 through the small holes by suction of the suction unit 56 described later.

An adsorption detection portion 557 for detecting adsorption of paper to each belt 556 is provided on the upstream side of the belt 556 in the paper feeding direction a. The adsorption detection unit 557 includes a substantially rod-shaped detection body 557a supported so as to be able to swing, and a photosensitive sensor 557b.

One end of the stopper 557a protrudes downward from the lower portion of the belt 556, and when the paper P is attracted to the belt 556, the stopper 557a swings and one end thereof is pushed back upward. The other end of the detector 557a is arranged to descend when the one end is pushed back upward, and to block the sensor 557b, and the sensor 557b inputs a change in the amount of received light due to the blocking to the control unit 400, and causes the control unit 400 to recognize the suction of the paper P.

As shown in fig. 3, 4, and 6, the suction unit 56 includes a duct 561 having one end inserted inside each belt 556 of the feeding unit 55, and a fan 562 that applies a negative pressure to the inside of the duct 561 at the other end of the duct 561.

One end of the pipe 561, into which the respective tapes 556 are inserted, is formed in a substantially rectangular parallelepiped shape, and an opening 561a is formed at the lower portion thereof. Then, the duct 561 is negatively pressurized by the fan 562, so that the outside air can be sucked from the opening 561 a.

The duct 561 is arranged such that the openings 561a thereof extend below four belts 556, and the range of each belt 556 corresponding to the openings 561a is a suction area B for the paper.

The sending unit 55 and the suction unit 56 can be realized by the above-described configuration: when the paper P on the upper portion of the paper table 511 is floated by the air blowing by the floating

air blowing units

53 and 54, the uppermost paper P floated by the suction force generated in the suction area B is sucked to the lower portion of each belt 556, and is fed in the paper feeding direction a by the rotational driving of each belt 556.

As shown in fig. 4, a conveying portion 57 is disposed on the downstream side in the paper feeding direction a in proximity to the feeding portion 55. The conveying unit 57 includes an insertion guide 571 into which the sheet P fed out from a lower portion of the belt 556 can be inserted, large and small conveying

rollers

572 and 573 provided in the insertion guide 571 on the downstream side in the paper feeding direction a with the sheet P interposed therebetween, a motor (not shown) as a drive source for rotationally driving the conveying

rollers

572 and 573, and a sheet detecting unit 574 as an optical or contact sensor for detecting that a leading end portion of the sheet P reaches the insertion guide 571 and that a trailing end portion of the sheet P passes through the insertion guide 571.

The insertion guide 571 is formed in a shape in which the upstream end in the paper feeding direction a is opened wide in the vertical direction and the vertical width is narrowed toward the paper feeding direction a, and the upstream end in the paper feeding direction a is connected to the conveyance path of the paper P toward the image forming apparatus main body 100a.

The large-diameter conveyance roller 572 and the small-diameter conveyance roller 573 are disposed in contact with each other, and are provided in the insertion guide portion 571 such that the sheet P passing through the insertion guide portion 571 passes between the conveyance roller 572 and the small-diameter conveyance roller 573.

The large-diameter conveyance roller 572 uses a motor, not shown, as a drive source, and the motor is driven under control of the control unit 400. The small-diameter conveying rollers 573 are in contact with the large-diameter conveying rollers 572, and therefore, are transmitted with a torque opposite to that of the large-diameter conveying rollers 572 to rotate together.

The paper detection unit 574 is disposed on the upstream side in the paper feed direction a in proximity to the

conveyance rollers

572 and 573, detects the presence or absence of the paper P at the position of the paper detection unit 574, and inputs the detection result to the control unit 400 as needed. That is, when the detection state changes from the state in which there is no paper P to the state in which there is paper P, the control unit 400 recognizes the position at which the leading end of the paper P reaches the paper detection unit 574, and when the detection state changes from the state in which there is paper P to the state in which there is no paper P, the control unit recognizes the position at which the trailing end of the paper P passes the paper detection unit 574.

The front end of the sheet P indicates the downstream end of the sheet P in the paper feed direction a, and the rear end of the sheet P indicates the upstream end of the sheet P in the paper feed direction a.

(4) Control unit

The control Unit 400 includes a CPU (Central Processing Unit) 401, a ROM (Read Only Memory) 402, a RAM (Random Access Memory) 403, and the like. The CPU401 reads out a program corresponding to the processing contents from the ROM402, expands the program in the RAM403, and collectively controls the operations of the respective modules (the image reading apparatus SC, the automatic document feeder DF, the image processing section 30, the image forming apparatus main body 100a, the paper feeder 500, and the like) of the image forming apparatus 100 in cooperation with the expanded program. At this time, various data stored in the storage unit 410 are referred to. The storage unit 410 is configured by, for example, a nonvolatile semiconductor memory (so-called flash memory) or a hard disk drive.

The control unit 400 includes a communication unit 420 including a communication control card such as a LAN card (not shown), and is capable of transmitting and receiving various data to and from an external device (for example, a personal computer) connected to a communication Network such as a LAN (Local Area Network) or a WAN (Wide Area Network).

[ paper feed control method ]

A method of controlling the paper feeding operation of each paper feeding unit 50 of the paper feeding device 500 by the control unit 400 will be described.

In the paper feeding operation in the paper feeding unit 50, the upper paper P is floated by the floating air from the floating

air blowing units

53 and 54, sucked to the lower portion of each belt 556, and sent to the conveying unit 57 side. The floated sheet P is attracted to the lower portion of the belt 556, but as shown in fig. 7 (a), not only the uppermost sheet P but also one or more sheets below the sheet P are floated. Further, as shown in fig. 7 (B), the sheet is pushed upward by the floating air, and the other sheet is in close contact with the sheet P below the uppermost sheet P.

Therefore, by blowing the separation air to the floated sheet by the separation air blowing unit 52, as shown in fig. 7 (C), the sheet P sucked to the lower portion of the belt 556 is separated from the other sheets, and the sheets other than the sheet P are dropped by their own weight.

Here, if the amount of air blown is insufficient at the start of blowing of the floating air, as shown in fig. 7 (D), the uppermost sheet P does not float to the lower portion of each belt 556 and cannot be sucked by the belt 556. Since heavy paper such as thick paper (for example, paper having a basis weight of 300g or more) is hard to float and is likely to be in a state as shown in fig. 7 (D), it is necessary to make the air blowing amount of the floating air larger at the time of floating such paper than at the time of feeding other paper.

However, if the floating air is too strong after the sheet floats, the posture of the sheet may become unstable, such as the sheet fluttering.

In addition, since the floating air is continuously blown to the paper sheet when the paper sheet is separated, the separation efficiency of the separated air is lowered. In particular, when feeding soft paper with low density such as bulky paper, the floating paper is difficult to separate, and therefore, the uppermost paper P and one or more lower papers may be fed to the conveying section 57 side with the uppermost paper P and the lower paper attached, and resupply may occur.

Therefore, after the paper is floated, the amount of blowing of the floating air needs to be reduced with respect to the amount of blowing of the separated air to the leading end portion of the paper.

Therefore, in the present embodiment, the amount of air blown onto the paper is controlled by controlling the blowing direction of the floating air by the floating

air blowing units

53 and 54.

First, since a large amount of air blowing is required for floating the paper P when paper feeding is started, the separated air collides with the floating air by directing the blowing directions of the floating air by the floating

air blowing units

53 and 54 toward the leading end direction of the paper P (downstream side in the paper feeding direction a), as shown in fig. 8 a. The air after the collision moves upward, and therefore becomes a strong floating force for floating the paper P.

At this time, the wind

direction switching members

534 and 544 are controlled by turning so that the blowing

ports

532 and 542 open to the side of the separated air blowing unit 52, as shown in fig. 8 (a).

Next, when the suction of the paper P is detected by the suction detection unit 557, the control unit 400 determines that the uppermost paper P is floating. If the air of the collision continues to blow the sheet after the sheet P floats, the sheet may be disturbed in its posture by the sheet shake or the like. In addition, in order to separate the uppermost sheet P from the lower sheet, the blowing of the floating air needs to be reduced. Therefore, as shown in fig. 8B, after the paper P is floated, the blowing

ports

532 and 542 are rotated from the direction of the mouth portion toward the separated air blowing section 52 side toward the rear end side of the paper P, and the blowing directions of the floating

air blowing sections

53 and 54 are respectively turned toward the rear end direction of the paper P (the upstream side in the paper feeding direction a), so that the excessive floating force is suppressed and the air flow is stabilized.

Further, since the degree of difficulty of floating or separating differs depending on the type of paper as described above, the blowing direction of the floating air can be controlled depending on the type of paper.

For example, in the case of a relatively light paper such as bulky paper or thin paper, in order to ensure separability, it is necessary to reduce the volume of the floating air with respect to the separated air. In this case, as shown in fig. 8C, the blowing directions of the floating air by the floating

air blowing units

53 and 54 are directed toward the rear end of the paper P (upstream side in the paper feeding direction a) from the start of paper feeding. In the case of a light paper, even a weak floating air is sufficiently floated, and therefore, there is no problem even if the blowing direction of the floating air is directed in the above-described direction from the start of paper feeding. At this time, the wind

direction switching members

534 and 544 are controlled to be in the direction shown in fig. 8 (C) by the rotation.

Next, the operation of image forming apparatus 100 will be described with reference to the flowchart of fig. 9.

First, when a print instruction is received, the control section 400 acquires paper information for a paper specified by a user (step S901). The paper information includes information about the basis weight and size of the paper.

Next, the control section 400 determines whether or not the sheet is a readily floating sheet based on the sheet information (step S902). If it is determined that the sheet is a readily floating sheet (yes in step S902), the process proceeds to step S911, and if it is determined that the sheet is not a readily floating sheet (no in step S902), the process proceeds to step S903. Here, in the case of paper having a basis weight of less than 300g, it is judged that the floating is easy.

In step S903, the control unit 400 controls the motors 537 and 547 to rotate the wind

direction switching members

534 and 544 to a position where the floating air is blown toward the leading end of the paper. That is, the wind

direction switching members

534 and 544 are arranged in the direction of fig. 8 (a).

Next, the control unit 400 controls the separated air blowing unit 52 and the floating

air blowing units

53 and 54 to start blowing the separated air and the floating air (step S904), and determines whether or not the floating of the paper is detected by the suction detection unit 557 (step S905). If the control unit 400 determines that the floating is not detected (no in step S905), the process proceeds to step S906, and if the floating is detected (yes in step S905), the process proceeds to step S908.

In step S906, the control unit 400 determines whether or not a predetermined time has elapsed, and if it is determined that the predetermined time has not elapsed (no in step S906), the process proceeds to step S905, but if it is determined that the predetermined time has elapsed (yes in step S906), the motors 537 and 547 are controlled to rotate the airflow

direction switching members

534 and 544 so that the blowing direction of the floating air is directed further toward the leading end side of the paper (step S907), and the process returns to step S905.

In step S908, the control unit 400 controls the motors 537 and 547 to rotate the wind

direction switching members

534 and 544 so that the floating air is diverted in the trailing end direction of the paper. That is, the wind

direction switching members

534 and 544 operate as shown in fig. 8 (B).

Next, the control unit 400 determines whether or not the sheet is the final sheet (step S909), and if it is determined that the sheet is the final sheet (yes in step S909), the control is terminated, but if it is determined that the sheet is not the final sheet (no in step S909), the control unit 400 controls the motors 537 and 547 to rotate the wind

direction switching members

534 and 544 to a position at which the floating air is blown toward the leading end of the sheet (step S910), and the process returns to step S905.

In step S911, the control unit 400 controls the motors 537 and 547 to rotate the wind

direction switching members

534 and 544 to a position where the floating air is blown toward the trailing end of the paper. That is, the wind

direction switching members

534 and 544 are arranged in the direction shown in fig. 8 (C).

air blowing units

53 and 54 to start blowing the separated air and the floating air (step S912), determines whether or not the page is the final page (step S913), and if the page is the final page (step S913: yes), the control is terminated, but if the page is determined not to be the final page (step S913: no), the process of step S913 is repeated.

As described above, the blowing direction of the floating air is changed according to the type of the sheet, thereby adjusting the flow rate suitable for the floating and separation of the sheet.

As described above, the image forming apparatus 100 according to the present embodiment includes the separated air blowing unit 52, the floating

air blowing units

53 and 54, and the blowing unit 55 having the adsorption unit 56, and the floating

air blowing units

53 and 54 further include the airflow

direction switching members

534 and 544, the

shafts

535 and 545, the gear pairs 536 and 546, and the motors 537 and 547, respectively, which are capable of switching the blowing directions. The control section 400 changes the blowing direction of the floating

air blowing sections

53 and 54 according to the basis weight, size, and floating state of the paper. Therefore, under conditions where the floating is difficult, such as when the sheet is heavy or when the sheet is large, stable paper feeding can be performed by adjusting the amount of collision between the floating air and the separation air.

In the image forming apparatus 100 according to the present embodiment, when the suction detection unit 557 detects that the uppermost sheet P is floating, the blowing direction of the floating

air blowing units

53 and 54 is directed upstream in the paper feeding direction. Therefore, by causing the floating air to flow to the rear end side of the paper after the paper floats, a stable air flow without an excessive air blowing amount can be obtained.

In the image forming apparatus 100 according to the present embodiment, when the suction detection unit 557 does not detect the floating of the uppermost sheet P for a predetermined period of time, the blowing direction of the floating

air blowing units

53 and 54 is directed to the downstream side in the paper feeding direction. Therefore, the air is blown so that the floating air collides with the separated air until the sheet floats, and a strong floating force can be obtained.

In the image forming apparatus 100 according to the present embodiment, the floating

air blowing sections

53 and 54 also function as restricting members and are movable in the left-right direction. Therefore, even if the size of the paper is changed, the paper can be moved to a position where air can be blown onto the paper from the vicinity of the paper placed thereon.

Further, image forming apparatus 100 according to the present embodiment includes wind

direction switching members

534 and 544 for blowing air in a horizontal direction or a direction slightly inclined upward from the horizontal direction. Therefore, since the floating air is blown out in the floating direction of the sheet, the sheet can be efficiently floated.

In the above flowchart, 2 kinds of control are performed depending on whether or not the sheet is easily floated, but the blowing direction may be changed according to the kind of sheet such as the sheet width. The correspondence relationship between the paper type and the angle of the wind

direction switching members

534, 544 with respect to the horizontal direction b may be tabulated in advance and stored in the storage unit 410, or may be set by the user in accordance with the paper type.

Further, the blowing direction of the floating air can be changed according to the paper width size.

For example, when the width of the sheet is large and the floating air blowing part 53 and the floating air blowing part 54 are located at positions separated from each other in the left-right direction, the separated air and the floating air are hard to collide with each other. In such a case, the air

direction switching members

534 and 544 are further directed toward the center side in the width direction of the sheet, so that the collision of the separated air and the floating air is likely to occur.

The correspondence relationship between the sheet width and the angle of the wind

direction switching members

534, 544 with respect to the left-right direction b may be tabulated in advance and stored in the storage unit 410, or may be set by the user in accordance with the sheet width.

[ other embodiments ]

The present invention has been described in detail with reference to the embodiments, but the above embodiments are preferred examples of the present invention and are not limited thereto.

For example, in the above-described embodiment, the case where the paper feeding device is mounted on the electrophotographic image forming apparatus has been described as an example, but the type of the image forming apparatus is not limited to this. For example, the paper feeding device 500 can be applied to any other image forming apparatus that forms an image on paper, such as an inkjet type image forming apparatus.

In the above embodiment, the floating of the paper is detected by detecting the contact of the paper with the detector 557a, but the present invention is not limited to this.

For example, when the paper is sucked to the suction unit 56, the opening 561a is closed, and thus the suction pressure is changed. Therefore, the floating of the sheet can also be detected by detecting the suction pressure.

Further, a reflection type sensor may be provided on both the right and left sides or on one side surface of the sheet mounting table 511, and the floating of the sheet may be detected by detecting reflected light generated by the floating sheet.

Further, the detailed configuration of each device constituting the image forming apparatus and the detailed operation of each device can be appropriately modified within a range not departing from the gist of the present invention.

Claims

1. A sheet feeding device is characterized by comprising:

a paper placing unit for storing paper in a stacked state;

a separated air blowing section for blowing air onto the paper from the front end side in the paper feeding direction of the loaded paper;

a floating air blowing part for blowing air onto the paper from both sides of the paper end part orthogonal to the paper feeding direction of the loaded paper;

an adsorption part for adsorbing the floated uppermost paper;

an air direction switching unit that changes an air blowing direction of the floating air blowing unit to any one of a direction toward a front end side of a paper feeding direction of the loaded paper and a direction toward a rear end side of the paper feeding direction of the loaded paper; and

and a control unit that controls the wind direction switching unit to change the blowing direction of the floating air blowing unit according to at least one of the basis weight and size of the paper and the floating state of the paper.

2. The sheet feeding apparatus as set forth in claim 1,

3. The sheet feeding apparatus as set forth in claim 1,

when the floating of the paper is not detected by the floating detection unit within a predetermined period from the start of paper feeding, the control unit changes the blowing direction of the floating air blowing unit to a direction toward the leading end side in the paper feeding direction of the loaded paper.

4. The sheet feeding apparatus as set forth in claim 2,

5. The sheet feeding apparatus as claimed in any one of claims 1 to 4,

6. The sheet feeding apparatus as claimed in any one of claims 1 to 4,

the floating air supply part supplies air to the surface of the paper towards the oblique upper direction.

7. The sheet feeding apparatus as set forth in claim 5,

8. An image forming apparatus is characterized by comprising:

a sheet supply device as set forth in any one of claims 1 to 7; and

an image forming section forms a toner image on a sheet.