JP7325922B2 - Paper feeder and image forming device - Google Patents

Description

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

2. Description of the Related Art Conventionally, among image forming apparatuses that form images on paper, there is known an air suction type paper feeder that stocks paper in a stacked state and supplies the paper to an image forming unit.
This air suction type paper feeding device has a floating air blowing unit that floats the paper stacked in the paper stacking unit by blowing air from both sides along the direction orthogonal to the paper conveying direction to the upper paper, The paper is separated by a separation air blower that separates the uppermost paper from the other papers by blowing air from the leading edge of the topmost paper in the conveying direction, and a conveying belt that is placed above the stacked paper. and a belt conveying mechanism that feeds the sheet in the conveying direction while sucking the sheet. By sucking only the uppermost sheet by means of these mechanisms and reliably separating it from the other sheets, it is possible to feed the sheets one by one onto the sheet conveying path.

However, when the paper is heavy or large, the floating force by the floating air and the separation air is not sufficient, and the paper may not be sent out.
In order to address such a problem, Patent Document 1 discloses a technique for improving the levitation force by blowing air in such a direction that the levitation air and the separation air collide with each other. At this time, since the floating state of the paper may become unstable due to collision of air, a mechanism for sucking air from the trailing edge of the paper is provided.

JP 2014-169182 A

Under conditions where the paper is difficult to float, it is necessary to blow strong floating air, and if the invention described in Patent Document 1 is used, the collision of the air will further increase, and along with this, a strong suction force will be applied from the trailing edge side. Air must be sucked.
However, if the suction force becomes strong, there is a possibility that the paper may be sucked carelessly, so it becomes difficult to stabilize the airflow while maintaining the strength of the air.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a paper feeder and an image forming apparatus capable of stably feeding paper even under conditions in which the paper is difficult to float.

In order to solve the above problems, the sheet feeding device according to claim 1 comprises:
a paper stacking unit that accommodates paper in a stacked state;
a separation air blower that blows air from the leading end of the stacked paper in the paper feed direction to the paper;
a levitation air blower that blows air onto the paper from both sides of the edges of the stacked paper perpendicular to the paper feed direction;
a suction unit that suctions the uppermost sheet that has floated;
an air direction switching unit that changes the blowing direction of the floating air blowing unit to an arbitrary direction from the direction toward the leading edge side of the stacked paper in the paper feeding direction to the direction toward the trailing edge side;
a control unit for controlling change of the blowing direction of the floating air blowing unit by the wind direction switching unit according to at least the basis weight and size of the paper out of the basis weight and size of the paper and the floating state of the paper;
and a floating detection unit that detects floating of the stacked paper,
The control unit
When the basis weight of the paper is equal to or greater than a predetermined value, the wider the width of the stacked paper, the more the air blowing direction of the floating air blowing unit is directed toward the leading edge side in the paper feeding direction and the width of the paper. When the basis weight of the paper is smaller than a predetermined value, the blowing direction of the floating air blowing unit is directed toward the rear end side of the paper feeding direction,
When the grammage of the paper is equal to or greater than a predetermined value, and when the floating of the paper is detected by the floating detection unit, the blowing direction of the floating air blowing unit is set to the leading end of the stacked paper in the paper feeding direction. Change the direction from the facing direction to the direction facing the rear end side,
When the grammage of the paper is smaller than a predetermined value and when the floating of the paper is detected by the floating detection unit, the blowing direction of the floating air blowing unit is kept facing the rear end side in the paper feeding direction. to make
It is characterized by

The invention according to claim 2 is the paper feeding device according to claim 1,
The control unit
When the grammage of the paper is equal to or greater than a predetermined value, and 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 air blowing direction of the floating air blowing unit is changed to the direction of the stacked paper. Change the paper feed direction from the leading edge side to the leading edge side,
When the grammage of the paper is smaller than a predetermined value and 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 air blowing direction of the floating air blowing unit is changed to the paper feeding direction. Keep facing the rear end
It is characterized by

The invention according to claim 3 is the paper feeding device according to claim 1 or 2 ,
The floating air blower is movable in a direction parallel to the surface of the stacked paper and perpendicular to the paper feed direction.

The invention according to claim 4 is the sheet feeding device according to any one of claims 1 to 3 ,
The floating air blowing unit blows air obliquely upward with respect to the surface of the paper.

The image forming apparatus according to claim 5 ,
a sheet feeding device according to any one of claims 1 to 4 ;
an image forming unit that forms a toner image on a sheet of paper.

According to the present invention, it is possible to provide a paper feeder and an image forming apparatus that can stably feed paper even under conditions in which it is difficult for paper to float.

1 is a diagram showing a schematic configuration of an image forming apparatus; FIG. 2 is a block diagram showing the main functional configuration of the image forming apparatus; FIG. 2 is a perspective view of a paper feeding unit of the image forming apparatus; FIG. FIG. 3 is a partially cutaway side view showing a feeding section, a suction section, and a conveying section of the sheet feeding section; FIG. 10 is a plan view showing the operation of the wind direction switching member of the paper feed unit; FIG. 2 is a plan view showing a sending section, a suction section, and a conveying section of the sheet feeding section; FIG. 10 is a side view showing the state of paper in the paper feeding operation of the paper feeding unit; It is a top view explaining the ventilation direction of floating air. 4 is a flow chart showing the operation of the image forming apparatus;

EMBODIMENT OF THE INVENTION Below, embodiment which concerns on this invention is described using drawing. However, although various technically preferable limitations are attached to the embodiments described below in order to carry out the present invention, the scope of the invention is not limited to the following embodiments and illustrated examples.

[Configuration 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 the functional configuration of the image forming apparatus 100. As shown in FIG.
As shown in FIGS. 1 and 2, the image forming apparatus 100 mainly includes an image forming apparatus main body 100a, an image reading device SC, an automatic document feeder DF, an image processing section 30, a paper feeding device 500, a control section 400, a storage It is composed of a section 410 and a communication section 420 .

The image forming apparatus main body 100a comprises an image forming section 10 comprising a photoreceptor 1, a charging section 2, an image exposing section 3, a developing section 4, a transfer section 5, a cleaning section 6, etc., a fixing section 7, and a sheet conveying system. It is The sheet conveying system is composed of a first sheet feeding section 11, a second sheet feeding section 12, a sheet feeding cassette 13, a sheet discharging section 14, a conveying path switching section 15, a circulation re-feeding section 16, and a reverse sheet discharging section 17. ing.
The paper feeding device 500 is composed of three paper feeding units 50 arranged vertically.

(1) Image Processing Section The image processing section 30 performs various types of image processing on image data and transmits an image signal to the image forming section 10 .
The document d placed on the document platen of the automatic document feeder DF is scanned for images on one side or both sides thereof by the optical system of the image reader SC, and read by the image sensor CCD. The image processing unit 30 performs analog processing, A/D conversion, shading correction, image compression processing, etc. on the analog signal photoelectrically converted by the image sensor CCD, and then sends the image signal to the image exposure unit 3 .
Further, the control unit 400 can communicate with an external device (for example, a personal computer) connected to the communication network from the communication unit 420, and the image processing unit 30 can communicate with the external device under the control of the control unit 400. In some cases, the image signal received from the device is sent to the image exposure unit 3 .

(2) Image Forming Section In the image forming section 10 , charges are added to the photosensitive member 1 by the charging section 2 , an electrostatic latent image is formed by laser light irradiation from the image exposing section 3 , and an electrostatic latent image is formed by the developing section 4 . The electrostatic latent image is visualized to form a toner image. Next, the paper P accommodated in the paper feed cassette 13 is conveyed from the first paper feed section 11 . The paper P is conveyed in synchronization with the toner image by the second paper feeding unit 12 consisting of registration rollers. After that, the toner image is transferred to the paper P by the transfer section 5 and then fixed by the fixing section 7 . The toner remaining on the photosensitive member 1 after transfer is removed by the cleaning section 6 .
Further, not the paper P accommodated in the paper feed cassette 13, but the paper P accommodated in the paper feeder 500 is also fed to the image forming apparatus main body 100a, and the toner image is transferred and fixed on the paper P. .

After fixing, the paper P is discharged outside the apparatus by the paper discharge unit 14 . In the case of double-sided printing, the paper P on which the image is formed on the first side is sent to the circulatory re-feeding section 16 by the transport path switching section 15 and is reversed, and the image is formed on the second side in the image forming section 10 again. After the formation, the sheet is discharged outside the apparatus by the discharge section 14 . In the case of reverse paper discharge, the paper P branched from the normal paper discharge path is switched back in the reverse paper discharge section 17 to be turned upside down, and then discharged outside the apparatus by the paper discharge section 14 .

(3) Paper Feeding Device FIG. 3A is a perspective view showing an outline of the paper feeding section 50 of the paper feeding device 500 . As described above, the three paper feed units 50 are arranged vertically in the paper feed device 500, but since they all have the same configuration, only one of the paper feed units 50 will be described here. Assumed to be performed.

The paper feeding unit 50 includes a horizontally oriented paper stacking table 511 as a paper stacking unit on which a plurality of papers P are stacked, and a paper stacking table 511 behind the paper stacking table 511, that is, on the upstream side in the paper feeding direction a. A trailing edge regulating member 512 is provided, and a leading edge regulating member 513 is provided in front of the sheet stacking table 511, that is, downstream in the sheet feeding direction a.
In the following description of the paper feeding unit 50, the horizontal direction perpendicular to the paper feeding direction a is defined as "left" when facing the paper feeding direction a. , and the direction of the right hand in the state of facing the paper feed direction a is defined as "right".

The paper stacking table 511 is supported in the paper feeding section 50 so as to be vertically movable, and the trailing end regulating member 512 and the leading end regulating member 513 are fixedly installed in the paper feeding section 50 .
The upper end portion of the leading end regulating member 513 is slightly lower in height than the upper end portion of the trailing end regulating member 512 . On the other hand, the sheet stacking table 511 is moved up and down by an actuator (not shown), and the uppermost portion of the sheets P stacked on the sheet stacking table 511 maintains a prescribed height slightly lower than the upper end portion of the leading end regulating member 513. Thus, the actuator is controlled by the controller 400 . The height control by this actuator is performed based on sensing by a sensor (not shown) that detects the height of the uppermost sheet P provided on the trailing end regulating member 512 side.
In addition, when the paper P is not fed, such as when the paper P is supplied, the paper stacking table 511 can be lowered.

Adjacent to the leading end regulating member 513, a separation air blower 52 is provided downstream of the leading end regulating member 513 in the sheet feeding direction a. Floating air blowing units 53 and 54 are provided on both the left and right sides of the paper stacking table 511, respectively. function as a restricting member that restricts the lateral position of the
The floating air blowing units 53 and 54 are provided so as to be movable in the horizontal direction by actuators (not shown). The actuator is controlled by the controller 400 . The lateral position of the actuator is determined based on the size information of the sheets stacked on the paper feeding section 50 stored in the storage section 410 .

Blowing fans 521 , 531 and 541 are provided inside the separation air blowing section 52 and the floating air blowing sections 53 and 54 , respectively, and are configured to blow air from blowing ports 522 , 532 and 542 .

FIG. 3B is a configuration diagram of a main part of the floating air blower 54. As shown in FIG. Since the floating air blowing unit 53 has the same configuration as the floating air blowing unit 54, the configuration diagram of the essential parts thereof is omitted.
As shown in FIG. 3B, the floating air blowing units 53 and 54 extend horizontally or slightly more than horizontally toward the paper P from the left and right sides of the uppermost paper P positioned at the regulated height. It has nozzles 533 and 543 for blowing air in a direction inclined upward. The air outlets 532 and 542 of the nozzles 533 and 543 are formed so that the upper edges thereof are lowered with respect to the uppermost sheet P positioned at the regulated height.

As shown in FIG. 3, the floating air blowing units 53 and 54 are provided with 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 arranged between the air blowing ports 532 and 542 and the stacked sheets, and are rotatable around shafts 535 and 545 . Driving force from motors 537 and 547 is transmitted to shafts 535 and 545 by gear pairs 536 and 546, and shafts 535 and 545 rotate. The wind direction switching members 534 and 544 are formed so that their upper edges are higher than the uppermost sheet P positioned at the regulated height.
That is, 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 so as to blow obliquely upward against the paper surface of the upper paper P in the stacked state. It is possible to raise P.

FIG. 4 is a cross-sectional view showing the configuration around the leading edge of the uppermost sheet P in the sheet feeding direction a on the sheet stacking table 511. As shown in FIG.
The separation air blower 52 is provided with a nozzle 523 for blowing air from the air blower port 522 in a direction inclined slightly upward from the downstream direction of the paper feed direction a. By blowing air to the downstream edge of a plurality of sheets of paper that have floated up in the paper feed direction a, air is blown between the floated paper P and the other papers, and the papers except for the uppermost paper P are separated. Allows it to go down.

FIG. 5 shows the relationship between the orientation of the airflow direction switching member 544 and the airflow direction.
Hereinafter, the direction perpendicular to the sheet feeding direction a on the paper surface is defined as the left-right direction b, and the side surface of the wind direction switching member 544 connected to the shaft 545 is defined as the rotation surface 544a.
For example, as shown in FIG. 5A, when the rotating surface 544a stops at an angle (θ1) of 90 degrees with respect to the left-right direction b, floating air flows from the blower port 542 in a direction perpendicular to the paper feeding direction a. blown out.
On the other hand, as shown in FIG. 5B, when the rotation surface 544a stops at an angle (θ2) facing the trailing edge of the paper with respect to the horizontal direction b, The air is blown out toward the upstream side (the rear end side of the paper).
Further, as shown in FIG. 5C, when the rotation surface 544a stops at an angle (θ3) directed toward the leading edge of the paper with respect to the left-right direction b, the downstream side ( leading edge of the paper).
That is, the motors 537 and 547 are driven under the control of the control unit 400 to rotate the wind direction switching members 534 and 544, thereby changing the blowing direction of the floating air.

FIG. 6 is a plan view of the delivery section 55 and the suction section 56. As shown in FIG. As shown in FIGS. 3, 4, and 6, a delivery section 55 is provided above the sheet stacking table 511. As shown in FIGS. In FIG. 3, the feeding unit 55 is shown shifted to the position indicated by the arrow so as not to hide the surrounding structure, but actually, as shown in FIG. located above the downstream end of the

The sending unit 55 includes four sets of belts 556 arranged in the horizontal direction perpendicular to the paper feeding direction a on the paper feeding surface, a motor 551 serving as a paper feeding drive source for driving these belts 556 , each of the belts 556 and the motor 551 . and a transmission gear train 552 interposed between.
Each belt 556 includes a large-diameter roller 553 provided on the upstream side in the paper feed direction a, two small-diameter rollers 554 and 555 provided on the downstream side in the paper feed direction a, and these rollers 553 and 554 . , 555 and a belt 556 . Torque is applied from the motor 551 to the large diameter roller 553 of each belt mechanism in the direction in which the lower portion of each belt 556 advances in the paper feed direction a. Sprockets may be used instead of the rollers 553, 554, 555.
In addition, each belt 556 has a plurality of small holes penetrating the front and back sides over the entire surface thereof, and the sheet P is drawn under each belt 556 through the small holes by suction of the suction unit 56, which will be described later. It is possible to absorb.

At the upstream side of the belts 556 in the sheet feeding direction a, an adsorption detection unit 557 for detecting the adsorption of the paper to each belt 556 is provided. The suction detection unit 557 includes a substantially bar-shaped detection body 557a that is swingably supported, and a light-sensitive sensor 557b.
One end of the detection body 557a protrudes below the lower portion of the belt 556, and when the sheet P is attracted to the belt 556, the detection body 557a swings and the one end is pushed back upward. there is When the other end of the detection body 557a is pushed back upward, the other end of the detection body 557a descends to shield the sensor 557b. to make the control unit 400 recognize that the sheet P is attracted.

As shown in FIGS. 3, 4, and 6, the suction unit 56 includes a duct 561 arranged with one end inserted inside each belt 556 of the delivery unit 55, and the other end of the duct 561. A fan 562 is provided to create a negative pressure in the duct 561 .
One end of the duct 561 inserted into each belt 556 is formed in a substantially rectangular parallelepiped shape, and an opening 561a is formed in the lower part thereof. By creating a negative pressure in the duct 561 by the fan 562, the outside air can be sucked from the opening 561a.
The duct 561 is arranged so that its opening 561a straddles the lower portions of the four belts 556, and the range corresponding to the opening 561a of each belt 556 is the adsorption area B for the paper.

With the above configuration, the sending unit 55 and the suction unit 56 float by the suction force generated in the suction area B when the sheet P on the upper part of the sheet stacking table 511 is floated by the above-described floating air blowing units 53 and 54 . The uppermost paper sheet P is attracted to the lower part of each belt 556, and the rotation of each belt 556 enables the paper sheet P to be sent out in the paper feed direction a.

As shown in FIG. 4, a conveying section 57 is provided close to the sending section 55 and downstream in the sheet feeding direction a. The conveying portion 57 includes an insertion guide portion 571 into which the sheet P fed from the lower portion of the belt 556 can be inserted, and an insertion guide portion 571 provided in the middle of the insertion guide portion 571 to convey the sheet P to the downstream side in the sheet feeding direction a. large and small transport rollers 572 and 573, a motor (not shown) as a driving source for rotating the transport rollers 572 and 573, the arrival of the leading edge of the paper P to the insertion guide portion 571, and the trailing edge of the paper P and a paper detection unit 574, which is an optical or contact sensor that detects the passage of paper.

The insertion guide portion 571 is formed in a shape such that the end on the upstream side in the paper feeding direction a is wide open in the vertical direction, and the vertical width of the opening narrows toward the paper feeding direction a. The end on the upstream side is connected to the transport path of the paper P toward the main body 100a of the image forming apparatus.
The large-diameter transport roller 572 and the small-diameter transport roller 573 are arranged so as to contact each other, and the insertion guide portion 571 is arranged so that the paper P passing through the insertion guide portion 571 passes between the transport roller 572 and the small-diameter transport roller 573 . It is provided in the portion 571 .
The large-diameter conveying roller 572 is driven by a motor (not shown) whose driving is controlled by the control unit 400 . Since the small-diameter conveying roller 573 is in contact with the large-diameter conveying roller 572 , reverse rotation torque is transmitted to the large-diameter conveying roller 572 to rotate together.

The paper detection unit 574 is arranged close to the transport rollers 572 and 573 and on the upstream side in the paper feed direction a. is input to the control unit 400 at any time. That is, when the detection state changes from the state where there is no paper P to the state where there is paper P, the control unit 400 recognizes that the leading edge of the paper P has reached the position of the paper detection unit 574, and detects the state where the paper P is present. When the detection state changes to a state in which there is no gap, it recognizes that the trailing edge of the paper P has passed the position of the paper detection unit 574 .
The leading end of the paper P indicates the downstream end of the paper P in the paper feeding direction a, and the trailing end of the paper P indicates the upstream end of the paper P in the paper feeding 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 CPU 401 reads a program corresponding to the processing content from the ROM 402, develops it in the RAM 403, and cooperates with the developed program to execute each block (image reading device SC, automatic document feeder DF, image processing unit 30) of the image forming apparatus 100. , image forming apparatus main body 100a, sheet feeding device 500, etc.). At this time, various data stored in the storage unit 410 are referenced. The storage unit 410 is composed of, for example, a nonvolatile semiconductor memory (so-called flash memory) or a hard disk drive.
The control unit 400 also includes a communication unit 420 including a communication control card such as a LAN card (not shown). Various data can be transmitted and received to and from a device (for example, a personal computer).

[Paper feed control method]
A method of controlling the sheet feeding operation of each sheet feeding section 50 of the sheet feeding device 500 by the control section 400 will be described.

In the paper feeding operation of the paper feeding unit 50 , the upper paper P is floated by floating air from the floating air blowing units 53 and 54 , is attracted to the lower part of each belt 556 , and is sent to the transport unit 57 side. The floated paper P is attracted to the lower part of the belt 556, but as shown in FIG. 7A, not only the top paper P but also one or a plurality of papers below it float. Further, as shown in FIG. 7(B), the floating air pushes up the sheet P, and other sheets are brought into close contact with each other below the sheet P at the top.
Therefore, by blowing separation air to the floating paper from the separation air blower 52, the paper P attracted to the lower part of the belt 556 is separated from the other paper as shown in FIG. Let the paper fall by its own weight.

Here, if the blowing amount of floating air is not sufficient at the start of the blowing of floating air, as shown in FIG. Can not. Heavy paper such as thick paper (for example, paper with a basis weight of 300 g or more) is difficult to float, and the state shown in FIG. 7D is likely to occur. It should be larger than when the paper is fed.

However, if the floating air is too strong after the paper has floated, the posture of the paper may become unstable, such as the paper fluttering.
In addition, the efficiency of separation by the separation air is lowered because the floating air continues to hit the sheet during separation. In particular, when feeding soft paper with low density such as bulky paper, it is difficult to separate the floated paper. and may cause double feed.
Therefore, after the sheet has floated, it is necessary to reduce the blowing amount of the floating air with respect to the blowing amount of the separation air blown to the leading edge of the sheet.

Therefore, in the present embodiment, the blowing amount of air 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 is required to float the paper P at the start of paper feeding, as shown in FIG. Separation air and floating air collide with each other by directing them in the leading end direction (downstream side in paper feeding direction a). Since the colliding air travels upward, it becomes a strong floating force for floating the paper P.
At this time, the wind direction switching members 534 and 544 are controlled so that the air blow ports 532 and 542 open toward the separation air blower 52 side as shown in FIG. 8A.

Next, when the adsorption detection unit 557 detects the adsorption of the sheet P, the control unit 400 determines that the uppermost sheet P has floated. After the paper P floats, if the colliding air continues to hit the paper, the paper may flutter and disturb its posture. In addition, in order to separate the uppermost paper sheet P from the lower paper sheets, it is necessary to weaken the blowing of the floating air. Therefore, after the sheet P is floated, as shown in FIG. 8B, the air blow ports 532 and 542 are rotated toward the rear end side of the sheet P from the opening direction toward the separation air blower 52 side, and floated. By swinging the blowing direction of the floating air from the air blowing units 53 and 54 toward the trailing edge of the paper P (upstream side in the paper feeding direction a), an excessive floating force is suppressed and the airflow is stabilized.

In addition, as described above, since the easiness of floating or separation differs depending on the type of paper, it is possible to control the blowing direction of the floating air according to the type of paper.
For example, in the case of light paper such as bulky paper or thin paper, it is necessary to reduce the amount of floating air relative to separation air in order to ensure separability. In this case, as shown in FIG. 8C, from the start of paper feeding, the blowing direction of the floating air by the floating air blowing units 53 and 54 is directed toward the trailing edge of the paper P (upstream side in the paper feeding direction a). . In the case of a light sheet, even a weak floating air is enough to float the sheet, so there is no problem even if the blowing direction of the floating air is set as described above from the start of paper feeding. At this time, the wind direction switching members 534 and 544 are controlled to be oriented as shown in FIG. 8(C) by rotation.

Next, the operation of the image forming apparatus 100 will be described using the flowchart of FIG.
First, when a print instruction is received, the control unit 400 acquires paper information about the paper specified by the user (step S901). The paper information includes information about the basis weight and size of the paper.

Next, based on the paper information, the control unit 400 determines whether or not the paper is likely to float (step S902). If it is determined that the paper is likely to float (step S902: Yes), the process proceeds to step S911, and if it is determined that the paper is not likely to float (step S902: No), the process proceeds to step S903. In this case, it is assumed that the paper having a basis weight of less than 300 g is judged to float easily.

In step S903, the control unit 400 controls the motors 537 and 547 to rotate the wind direction switching members 534 and 544 so that floating air is blown toward the leading edge of the paper. That is, the wind direction switching members 534 and 544 are arranged in the direction shown in FIG. 8(A).

Subsequently, the control unit 400 controls the separation air blowing unit 52 and the floating air blowing units 53 and 54 to start blowing the separation air and the floating air (step S904), and the adsorption detection unit 557 detects the floating of the paper. It is determined whether or not it has been done (step S905). If the control unit 400 determines that floating has not been detected (step S905: No), it proceeds to step S906, and if it determines that floating has been detected (step S905: Yes), it proceeds to step S908.

In step S906, the control unit 400 determines whether or not the predetermined time has passed. If it is determined that the predetermined time has not passed (step S906: No), the process proceeds to step S905, but it is determined that the predetermined time has passed. Then (step S906: Yes), the motors 537 and 547 are controlled to rotate the wind direction switching members 534 and 544 so that the blowing direction of the floating air is further directed toward the leading end 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 to swing floating air toward the trailing edge of the paper. That is, the wind direction switching members 534 and 544 are operated as shown in FIG. 8(B).

Subsequently, the control unit 400 determines whether the page is the final page (step S909), and if it determines that the page is the final page (step S909: Yes), it ends the control, but if it determines that the page is not the final page. (Step S909: No), 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 blown toward the leading edge of the paper (step S910), and the process proceeds to step S905. and return.

In step S911, the control unit 400 controls the motors 537 and 547 to rotate the wind direction switching members 534 and 544 so that floating air is blown toward the trailing edge of the paper. That is, the wind direction switching members 534 and 544 are arranged in the direction shown in FIG. 8(C).

Subsequently, the control unit 400 controls the separation air blower 52 and the floating air blowers 53 and 54 to start blowing the separation air and the floating air (step S912), and determines whether or not the page is the last page. (Step S913) If it is determined that the page is the final page (Step S913: Yes), the control is terminated. If it is determined that the page is not the final page (Step S913: No), the processing of Step S913 is repeated.

As described above, by changing the blowing direction of the floating air according to the paper type, the air volume is adjusted to be suitable for floating and separating the paper.

As described above, the image forming apparatus 100 according to the present embodiment includes the separation air blower 52, the floating air blowers 53 and 54, and the delivery unit 55 having the suction unit 56. 53 and 54 are further equipped with wind direction switching members 534 and 544 and shafts 535 and 545, gear pairs 536 and 546, and motors 537 and 547, which are capable of switching the blowing direction. The control unit 400 changes the blowing direction of the floating air blowing units 53 and 54 according to the basis weight, size, and floating state of the paper. Therefore, when the paper is heavy or large, it is difficult to float, and by adjusting the amount of collision between the floating air and the separation air, stable paper feeding can be performed.

Further, in the image forming apparatus 100 according to the present embodiment, when the adsorption detection unit 557 detects that the uppermost paper sheet P has floated, the air blowing direction of the floating air blowing units 53 and 54 is set to the upstream side in the paper feeding direction. and turn. Therefore, after the sheet has floated, by flowing the floating air toward the trailing edge of the sheet, it is possible to obtain a stable airflow without excessively blowing air.

Further, in the image forming apparatus 100 according to the present embodiment, when the suction detection unit 557 does not detect that the uppermost paper sheet P has floated for a predetermined time, the air blowing direction by the floating air blowing units 53 and 54 is changed to the paper feeding direction. facing downstream. Therefore, until the paper floats, the floating air and the separation air are blown so as to collide with each other, and a strong floating force can be obtained.

Further, in the image forming apparatus 100 according to the present embodiment, the floating air blowing units 53 and 54 also function as regulating members and are movable in the left-right direction. Therefore, even if the size of the paper is changed, it can be moved to a position where air can be blown from the vicinity of the stacked paper.

Further, the 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 inclined slightly upward from the horizontal direction. Therefore, since the floating air is blown in the direction in which the paper floats, the paper can be floated efficiently.

In the above flowchart, two types of control are performed depending on whether the paper is likely to float or not, but the air blowing direction may be changed for each paper width for the type of paper. Note that the correspondence relationship between the types of paper and the angles of the wind direction switching members 534 and 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 according to the type of paper. It may be assumed that

It is also possible to change the blowing direction of the floating air according to the paper width size.
For example, when the width of the paper is large and the floating air blowing units 53 and 54 are separated from each other in the horizontal direction, the separation air and the floating air are less likely to collide with each other. In such a case, by directing the wind direction switching members 534 and 544 more toward the center side in the width direction of the paper, the separated air and floating air can easily collide with each other.
Note that the correspondence relationship between the paper width and the angles of the wind direction switching members 534 and 544 with respect to the horizontal direction b may be tabulated in advance and stored in the storage unit 410, or set by the user according to the paper width. It can be a thing.

[Other embodiments]
As mentioned above, although it explained concretely based on the embodiment which concerns on this invention, said embodiment is a suitable example of this invention, and is not limited to this.

For example, in the above embodiment, the case where the sheet feeding device is installed in an electrophotographic image forming apparatus is illustrated, but the type of image forming apparatus is not limited to this. For example, it is possible to apply the paper feeder 500 to any type of image forming apparatus that forms an image on paper, such as an inkjet type.

Further, in the above-described embodiment, floating of the paper is detected by detecting contact of the paper with the detection body 557a, but the present invention is not limited to this.
For example, when a sheet is adsorbed to the adsorption portion 56, the opening 561a is closed, so the suction pressure changes. It is also possible to detect the floating of the paper by detecting this suction pressure.
Further, reflective sensors may be provided on either one of the left and right sides of the paper stacking table 511 to detect the light reflected by the floating paper, thereby detecting the floating of the paper.

In addition, the detailed configuration and detailed operation of each device that constitutes the image forming apparatus can be changed as appropriate without departing from the gist of the present invention.

50 paper feed section 51 paper stacking table (paper stacking section)
52 Separation air blower 53, 54 Floating air blower 531, 541 Blower fan 532, 542 Blower port 533, 543 Nozzle 534, 544 Wind direction switching member (wind direction switching part)
535, 545 axis (wind direction switching part)
536, 546 gear pair (wind direction switching unit)
537, 547 motor (wind direction switching part)
55 delivery unit 557 adsorption detection unit (levitation detection unit)
557a Detector 557b Sensor 56 Suction unit 57 Conveying unit 100 Image forming apparatus 100a Image forming apparatus main body 400 Control unit 500 Paper feeder

Claims (5)

a paper stacking unit that accommodates paper in a stacked state;
a separation air blower that blows air from the leading end of the stacked paper in the paper feed direction to the paper;
a levitation air blower that blows air onto the paper from both sides of the edges of the stacked paper perpendicular to the paper feed direction;
a suction unit that suctions the uppermost sheet that has floated;
an air direction switching unit that changes the blowing direction of the floating air blowing unit to an arbitrary direction from the direction toward the leading edge side of the stacked paper in the paper feeding direction to the direction toward the trailing edge side;
a control unit for controlling change of the blowing direction of the floating air blowing unit by the wind direction switching unit according to at least the basis weight and size of the paper out of the basis weight and size of the paper and the floating state of the paper;
and a floating detection unit that detects floating of the stacked paper,
The control unit
When the basis weight of the paper is equal to or greater than a predetermined value, the wider the width of the stacked paper, the more the air blowing direction of the floating air blowing unit is directed toward the leading edge side in the paper feeding direction and the width of the paper. When the basis weight of the paper is smaller than a predetermined value, the blowing direction of the floating air blowing unit is directed toward the rear end side of the paper feeding direction,
When the grammage of the paper is equal to or greater than a predetermined value, and when the floating of the paper is detected by the floating detection unit, the blowing direction of the floating air blowing unit is set to the leading end of the stacked paper in the paper feeding direction. Change the direction from the facing direction to the direction facing the rear end side,
When the grammage of the paper is smaller than a predetermined value and when the floating of the paper is detected by the floating detection unit, the blowing direction of the floating air blowing unit is kept facing the rear end side in the paper feeding direction. to make
A sheet feeding device characterized by: The control unit
When the grammage of the paper is equal to or greater than a predetermined value, and 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 air blowing direction of the floating air blowing unit is changed to the direction of the stacked paper. Change the paper feed direction from the leading edge side to the leading edge side,
When the grammage of the paper is smaller than a predetermined value and 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 air blowing direction of the floating air blowing unit is changed to the paper feeding direction. Keep facing the rear end
2. The sheet feeding device according to claim 1 , wherein: 3. The paper feeder according to claim 1 , wherein the floating air blower is movable in a direction parallel to the surface of the stacked paper and perpendicular to the paper feed direction. 4. The paper feeding device according to claim 1, wherein the floating air blower blows air obliquely upward with respect to the surface of the paper. a sheet feeding device according to any one of claims 1 to 4 ;
and an image forming unit that forms a toner image on a sheet of paper.

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