JP4131325B2 - Sheet supply apparatus and image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sheet feeding apparatus that sequentially feeds stacked sheets one by one, and more particularly to a sheet feeding apparatus that can effectively prevent so-called double feeding in which two or more sheets are fed in a superimposed manner. .
[0002]
[Prior art]
In an image forming apparatus such as a printer or a copying machine, a recording sheet cut into a predetermined size is used as a recording medium on which an image is formed. As the recording paper, high-quality paper for copying machines is generally used, and the surface smoothness of these recording papers is relatively low. For this reason, the adhesion between the recording sheets is small, and it is relatively easy to prevent double feeding when the recording sheets are fed one by one from the sheet tray. However, in recent years, with the diversification of recording media, recording sheets having high surface smoothness are often used. Such a recording sheet has high surface adhesion, and double feeding is likely to occur. In particular, with the widespread use of full-color image forming apparatuses, highly glossy coated paper is often used, and in addition to this, OHP sheets and tracing paper are sometimes used.
[0003]
In this situation, as a technology to prevent double feeding of highly adhesive recording sheets, in addition to separating the sheets taken out by the paper feed roll and the separation roll from other sheets, they are stacked on the sheet tray and stored. A technique has been proposed in which separation of air is promoted by blowing an air flow onto the end face of the formed sheet to form an air layer between the sheets (for example, Patent Document 1).
[0004]
In addition, a shutter that can be moved in the vertical direction is provided at the airflow outlet, and the airflow is blown out while moving the shutter up and down to change the range of the airflow and operate to roll the stacked sheets. A technique for promoting separation is also disclosed (Patent Document 2).
[0005]
Furthermore, when moving the shutter up and down as described above, a technique has been proposed in which the moving speed is changed in a predetermined pattern so that separation between the sheets is effectively performed in the upper layer portion of the stacked sheets. (Patent Document 3).
[0006]
[Patent Document 1]
JP-A-4-23747 [Patent Document 2]
Japanese Patent Laid-Open No. 11-5643 [Patent Document 3]
Japanese Patent Laid-Open No. 2002-128300
[Problems to be solved by the invention]
However, in the conventional apparatus as described above, it is desired to further improve the following points.
By blowing an air flow on the end faces of the laminated sheets, the sheets are separated so as to spread and the air flow is generated between the sheets to reduce the adhesion, but the size of high glossy paper etc. For large sheets, a sufficient separation effect may not be obtained. In a sheet having a high gloss and a large size, the sheet is in close contact with a wide area, so that it is difficult to spread the airflow over the entire large area. Further, when an air flow is blown, it is difficult to cause a whispering operation, and it is difficult to separate and separate the sheets. And even if a strong air flow is blown, a phenomenon such that the two or three sheets are lifted up tends to occur.
[0008]
On the other hand, the speed of image formation by a copying machine or the like has increased the sheet supply speed, and the effect of separating and floating the sheet by blowing an air flow is not sufficient, and double feeding is likely to occur. There is also.
[0009]
The invention according to the present application has been made in view of the situation as described above, and blows an air flow to the end faces of the stacked sheets to reduce the adhesion between the sheets and more reliably prevent double feeding. For the purpose.
[0010]
[Means for Solving the Problems]
In order to solve the above-described problem, the invention according to claim 1 includes: a sheet storage unit that stacks and stores sheets on which images are recorded; and a sheet stored in the sheet storage unit in order from the uppermost sheet. A sheet delivery means for delivering, and a blowout opening facing a stacking end face parallel to the delivery direction of the sheets stacked in the sheet storage means, and a first air blown from the blowout opening to the stacked end face of the sheets Air blowing means, and a blowout opening facing the downstream end face in the delivery direction of the sheets stacked in the sheet storage means, and a second air blowing the airflow from the blowout opening to the laminated end face of the sheets An air blowing means, wherein the second air blowing means is set to have a smaller air volume or speed than the first air blowing means. To provide a sheet feeding apparatus characterized by.
[0011]
The sheet supply apparatus as described above has a plurality of outlets, which are provided on the downstream side and the side of the sheet feeding direction so as to blow airflow from two directions. The effect of reducing the adhesion force extends over a wide range of sheets accommodated in the sheet tray. Also, the air flow from the outlet provided on the downstream side in the sheet feeding direction is set so that the air speed or air volume is smaller than the air flow from the outlet provided on the side, and plays an auxiliary role Therefore, it is possible to avoid a situation in which the conveyance of the fed sheet is hindered by the air flow.
[0012]
Further, the sheets accommodated in the sheet tray are generally B5 size to A3 size, and the length of the sheet in the sending direction varies greatly from the short side length of the B5 size sheet to the long side length of the A3 size. For this reason, it is difficult to set an air flow that effectively acts on a sheet of any size as the air flow from the downstream side in the sheet feeding direction. In contrast, the width in the sheet feeding direction changes only from the short side length of the B5 size sheet to the short side length of the A3 size sheet, and the change in the sheet width is smaller than the sheet feeding direction. For this reason, the air flow blown from the side of the sheet is less dependent on the size of the sheet, and by separating the sheet mainly using the air flow from the side, any size sheet can be obtained. In addition, the air flow effectively acts, and separation between sheets and reduction of adhesion force occur.
[0013]
The invention according to claim 2 is the sheet supply apparatus according to claim 1, wherein the second air blowing unit is configured such that the air volume or the wind speed is such that the sheets fed one by one from the sheet storage unit do not deviate from the conveyance path. Is limited to a small size.
[0014]
In such an apparatus, the air flow from the downstream side in the sheet feeding direction is appropriately set, and the sheet feeding from the sheet tray by the roll is not hindered. That is, if the air flow from the downstream side is too strong, the sheet to be fed may be bent by the wind pressure or may not be fed into the nip portion of the two rolls, but such a situation is prevented.
[0015]
The invention according to claim 3 is the sheet supply device according to claim 1, wherein the first air blowing means has a plurality of blowing ports, and the blowing port on the most downstream side in the sheet feeding direction is It is assumed that it is provided at a position facing the end surface of the smallest size sheet that can be accommodated in the sheet accommodating portion.
[0016]
In such an apparatus, a plurality of outlets are provided on the side, and when a large sheet is accommodated, an air flow can be effectively blown over a wide range. Even when the size of the sheet stored in the sheet tray is small, the air flow from the most downstream outlet in the sheet feeding direction acts on the end surface of the sheet, separating the sheets and reducing the adhesion force Effect is obtained.
[0017]
The invention according to claim 4 is the sheet feeding apparatus according to claim 1, wherein the second air blowing means has a plurality of blowing ports, and at least one blowing port can be accommodated in the sheet accommodating portion. It is assumed that it is provided at a position facing the end face of the smallest sheet.
[0018]
In this apparatus, at least one of the plurality of outlets provided on the downstream side in the sheet feeding direction is always opposed to the end face of the sheet regardless of the sheet size, and is blown from the downstream side. The separation between the sheets is effectively promoted by the action of the air flow, and the adhesion is reduced.
[0019]
The invention according to claim 5 is the sheet supply apparatus according to claim 1, wherein the sheet storage means has a wall body that regulates the position of the stacked sheets on the downstream side in the sheet feeding direction, The wall body is inclined at a position facing at least the upper layer portion of the sheets stacked in the sheet storage means to the downstream side, and the outlet of the second air blowing means is formed by the inclined portion of the wall body. It is assumed that it is provided at a position including it.
[0020]
In such an apparatus, when the sheets are sent out one by one from the sheet tray, the stacked sheets are drawn to the downstream side and come into contact with the wall surface on the downstream side. And since a wall surface inclines to the downstream side, the edge of the laminated | stacked sheet | seat will be in the state protruded to the downstream side, so that it becomes an upper layer along the inclined wall surface.
The air outlet from the downstream side of the sheet feeding direction is provided in a portion where the wall body is inclined to the downstream side, and an air flow is generated above the uppermost layer of the stacked sheets, and the downstream side as described above. The air flow is blown downward at the portion protruding to the surface, and lift is generated for each of the stacked sheets. Thereby, separation between sheets is promoted, and multi-feed is more reliably prevented.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus in which a sheet feeding apparatus according to the present invention is used.
The image forming apparatus includes a receiving unit 3 connected to an image reading device 1 and an external device 2 such as a personal computer via a communication line, and takes image information from the receiving unit 3 into an image recording control unit 4. The image recording unit 5 forms an image based on the image information and fixes the image on the recording sheet.
[0022]
The image recording unit 5 forms an image by electrophotography, and the photosensitive drum 11 on which a latent image due to a difference in electrostatic potential is formed on the peripheral surface and the peripheral surface of the photosensitive drum 11 are combined. In this way, the charging roller 12 that is charged in a similar manner, the image writing device 13 that irradiates the uniformly charged photosensitive drum 11 with image light, and forms an electrostatic latent image, and the latent image on the photosensitive drum 11 are filled with toner. A developing device 14 for visualizing the image by transfer, a transfer device 15 for transferring the toner image formed on the photosensitive drum 11 to the recording sheet, and a fixing image by heating and pressing the recording sheet to which the toner image is transferred. And a cleaner 17 for cleaning the photosensitive drum 11 after the image is transferred.
[0023]
Below the image recording unit 5, a sheet feeding device 6 is provided, and four sheet feeding devices are arranged vertically so as to accommodate sheets of different sizes or different types. Then, the sheet fed from the sheet feeding device 6 is fed to the image recording unit 5 through the conveyance path 7, and after the toner image on the photosensitive drum 11 is transferred by the transfer device 15, the fixing device 16 is passed through. It passes through and is discharged to the paper discharge tray 8.
[0024]
2 is a schematic perspective view of the sheet supply device 6, FIG. 3 is a cross-sectional view taken along line AA shown in FIG. 2, and FIG. 4 is a cross-sectional view taken along line BB shown in FIG. FIG. FIG. 5 is a plan sectional view.
The sheet supply device 6 includes a sheet tray 21 (sheet storage unit) that stores and stacks a plurality of sheets, a sheet feed roll group 22 (sheet delivery unit) that feeds the sheets one by one from the sheet tray 21, A sheet guide 23 for regulating the position of the sheet in the sheet tray, a bottom plate 24 for adjusting the upper surface of the stacked sheets S provided at the bottom of the sheet tray 21 to a supply position of a predetermined height, and a sheet A first air flow blowing device 25 that blows an air flow from the side to the end face of the sheet S stacked and accommodated in the tray 21 and a second air blowing device that blows an air flow from the downstream side in the sheet feeding direction. 26.
[0025]
The sheet S accommodated in the sheet tray 21 is positioned in contact with the downstream wall body 21a and the lateral wall body 21b in the feeding direction, and the side wall surface becomes a side register (side reference position). The sheet S is sent out along this wall surface. The sheet guides 23 are movably provided at positions facing these wall surfaces, and the positions of the sheet S of different sizes are restricted, and the downstream wall body 21a and the side wall bodies 21b are arranged. The end surfaces of the stacked sheets S are in contact with each other.
[0026]
The paper feed roll group 22 rotates in contact with the upper surface of the stacked sheets S, and a pickup roll 31 that feeds out the uppermost sheet S and a feed that is provided on the downstream side and driven in the feeding direction of the sheets S. It has a feeding roll 32 and a separation roll 33 that is in contact with the feeding roll 32 and is driven in a direction opposite to the sheet feeding direction via a torque limiter. When the sheet fed by the pick-up roll is fed to the contact portion between the feeding roll 32 and the separation roll 33 and the sheet is only one sheet, the sheet is fed by driving the feeding roll 31. Since the rotational driving force transmitted by the friction with the sheet exceeds the driving force transmission limit of the torque limiter, the separation roll 33 is fed out of the sheet against the driving force applied to the separation roll 33. Rotate in the direction. Further, when the sheet is fed into the contact portion between the feeding roll 32 and the separation roll 33 in a state where two or more sheets are overlapped, the driving force of the feeding roll 32 is transmitted to the uppermost sheet, but between the sheets. The lower sheet is separated from the upper sheet, and is conveyed in a direction opposite to the feeding direction by the driving force of the separation roll 33 and returns to the sheet tray 21.
[0027]
The first airflow spraying device 25 assists the double feed prevention mechanism by the paper feed roll group 22 as described above, and two units are provided on the side of the sheet tray 21 and are provided on the side wall surface. An air flow outlet 41 provided, a duct 42 communicating with the air outlet 41, a fan 43 for sending air into the duct 42, a shutter 44 for changing the opening range of the air outlet 41, and the shutter 44 being moved up and down. A driving device 45 that drives in the direction and a control device 46 that controls the operation of the driving device constitute a main part. And while separating the sheet | seat laminated | stacked by the said structure, the adhesive force between sheets is reduced and the double feeding of a sheet | seat is prevented.
[0028]
As shown in FIG. 2 or 5, the air flow outlet 41 is provided at two locations, a front portion and a rear portion on the side in the sheet feeding direction of the sheet tray 21, as shown in FIG. 3. Further, it is provided at a position where the airflow can be blown above the uppermost surface of the sheet S stacked in the sheet tray 21 and on the end surface of the stacked sheet. The front outlet is located at the position facing the end face of the stacked sheets even when the smallest size sheet, for example, a B5 size sheet is accommodated with the short side abutting against the side wall. It has become.
[0029]
The fan 43 sends air to the outlet 41 through the duct 42, and a sirocco fan can be used.
Note that the air taken in by the fan may be heated by a heater or the like. By blowing the heated air, the sheets are dried, and the adhesion between the sheets is reduced.
[0030]
The shutter 44 restricts the air flow passing through the duct 42 in the vicinity of each outlet 41 and is supported so as to be movable in the vertical direction as shown in FIG. Has become. Then, by appropriately controlling the operation of the shutter 44 by the control device 46, the air volume and the blowout range of the airflow blown from the blowout port 41 are changed with time, or the airflow is made steady by making the blowout range constant. The state can be arbitrarily set.
[0031]
The shutter driving device 45 drives the shutters 44 a and 44 b provided at the two outlets 41 independently, and drives the shutter 44 via the transmission mechanism 47. Based on the signal from the control device 46, the shutters 44a and 44b are controlled to perform independent operations.
[0032]
On the other hand, in the second air blowing device 26 provided on the downstream side in the sheet feeding direction, one unit is disposed on both sides of the position where the sheet feeding roll group 22 is provided. As shown in FIG. The air flow sent out from 53 is blown out from the blow-out port 51 through the duct 52, blown to the end surface on the feed-out side of the sheet S, and blown out from the uppermost sheet.
[0033]
In the fan 53 provided in the second air blowing device 26, the air volume or the air speed blown out from the blowout port is suppressed to about 1/3 to 1/2 of that of the first air blowing device 25.
[0034]
Further, in the second air blowing device 26, the duct 52 is not provided with a shutter, and the blowing range does not fluctuate and is constant. However, it is possible to change the air volume or the wind speed by changing the output of the fan 53.
[0035]
Next, the operation and action of the sheet feeding device 6 will be described.
The shutter 44 provided in the first air blowing device 25 can be operated as follows, for example.
Both the shutter 44a of the first outlet 41a provided on the downstream side in the sheet feeding direction and the shutter 44b of the second outlet 41b provided on the rear side are periodically reciprocated up and down at substantially the same speed. It is controlled to do. These are driven so as to cause a phase shift of one half of one cycle. That is, when the shutter 44a of the first outlet 41a is lowered and opening the outlet, the shutter 44b of the second outlet 41b is raised and moves in the direction of closing the outlet. The second outlet 41b is closed when the first outlet 41a is almost fully opened, and the second outlet 41b is opened when the first outlet 41a is being closed. It has become.
[0036]
By controlling the shutter 44 in this way, the sheet S stacked and accommodated in the sheet tray as shown in FIG. 7A has a blowing port at a portion facing the first blowing port 41a. By being opened, the stacked sheets S float and rise one after another. On the other hand, in the part facing the second blowing port 41b, the sheet S that has been lifted by closing the blowing port is gradually lowered and stacked by gravity. Also, as shown in FIG. 7B, when the first outlet 41a is being closed, the sheet floating at the facing portion gradually descends, and when the second outlet 41b is being opened, Sheets are levitated one after another at the facing part. As the shutter operates in this manner, the stacked sheets are deformed so as to wave, and the curvature of the sheet always varies. And a slight shift occurs between the sheets, and the separation is promoted.
[0037]
On the other hand, the air flow from the outlet 51 of the second air blowing device 26 is blown upward from the uppermost sheet, thereby generating a negative pressure above the uppermost sheet, and lift acts on the uppermost sheet. Levitating. Along with this, an air flow is generated on the lower side, and lift is similarly applied to the second sheet. In this way, levitation is performed sequentially, and separation between sheets and reduction of adhesion are performed.
[0038]
In addition, the air flow at this time is set to be weaker than the air flow from the side, and the uppermost sheet S1 drawn by the pickup roll 31 is fed to the feeding roll 32 and the separation roll 33 as shown in FIG. There is no hindrance to being sent between. If the air flow from the downstream side in the sheet feeding direction becomes excessive, the sheet S ′ is swung upward by the influence of the air flow as shown by the broken line in FIG. The air flow blown out by the second air blowing device 26 is set to have a smaller air volume or speed than the air flow from the first air blowing device 25, and the above situation is avoided.
[0039]
As described above, the second air blowing device 26 acts on the first air blowing device 25 in a subordinate manner, but the air flow flows between the sheets by blowing the air flow from two directions. Opportunities are increased and separation between sheets is more reliably performed. Further, even if the sheet is a large size by supplying the airflow from two directions, the airflow and the adhesion force are sufficiently reduced to the rear, and double feeding is effectively prevented.
[0040]
Further, each of the first air blowing device 25 and the second air blowing device 26 blows an air flow from a plurality of outlets, and when the size of the sheet is large, it is an opportunity to separate the sheets. It is easy to obtain the air flow, and the air flow can be surely sent to a wide range. And by providing each with an independent fan, it can blow with a small capacity fan, and can also suppress noise small.
[0041]
FIG. 9 is a partial cross-sectional view of a sheet feeding apparatus according to an embodiment of the invention described in claim 5 .
In the sheet supply device, the upper portion of the wall body is inclined downstream in the downstream direction in the sheet feeding direction of the sheet tray 61. And the blower outlet 71 of the 2nd air spraying apparatus 66 is provided in the position containing the inclination part of the said wall body. The configuration of the fan 73, the duct 72, etc. of the second air blowing device 66 is the same as that shown in FIG. Further, the side wall of the sheet tray, the sheet guide, the bottom plate 65 and the like are the same as those shown in FIGS. 2 to 5, and the first air blowing device 25 provided on the side of the sheet tray. Is the same as that shown in FIG.
[0042]
In such a sheet supply device, when the pickup roll 62 rotates to feed the sheets one by one from the uppermost layer, the upper layer sheet is pushed to the downstream side, and the upper layer sheet moves to the downstream side along the inclined wall surface. It will be overhanging. The air flow blown out from the blowout port 71 of the second air blowing device 66 is blown upward from the uppermost sheet, thereby generating a negative pressure above the uppermost sheet, and the uppermost sheet. Gives lift to the seat. At the same time, the air flow blown downward from the uppermost sheet acts on the lower surface of the protruding end of the upper layer sheet, thereby improving the effect of separating the sheet.
[0043]
In the embodiment described above, each of the first air blowing devices changes the state of the air flow, but may be one that blows the air flow in a steady state. Further, the second air blowing device may change the air flow.
[0044]
【The invention's effect】
As described above, in the sheet feeding apparatus according to the present invention, airflow is blown from the two directions of the sheet feeding direction downstream side and the side to the end surface of the sheets stacked and accommodated in the sheet accommodating means. In addition, the effect of separating sheets can be widely obtained, and an air flow is formed in a wide range even for a large size sheet, and the adhesion force is effectively reduced. Further, the air flow from the downstream side is set to have a lower wind pressure or air volume than the air flow from the side, and does not hinder the feeding of sheets one by one for recording an image.
Further, the front end of the sheet tray in the direction of feeding the sheet is inclined to the downstream side, and an air flow is blown to the end surface of the stacked sheets so as to project downstream along the inclined surface. The wind pressure acts so as to blow up from below, and separation between sheets is promoted. With such a configuration, it is possible to more reliably prevent the sheet from being double-fed and to smoothly supply the sheet.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus in which a sheet feeding apparatus according to the present invention is used.
FIG. 2 is a schematic perspective view of a sheet feeding device used in the image forming apparatus shown in FIG.
FIG. 3 is a cross-sectional view taken along line AA shown in FIG.
4 is a cross-sectional view taken along line BB shown in FIG.
FIG. 5 is a cross-sectional plan view of the sheet feeding apparatus shown in FIG.
FIG. 6 is a schematic cross-sectional view of a second air blowing device provided on the downstream side in the sheet feeding direction.
FIG. 7 is a schematic view showing the operation of the seat when the air flow is changed from the side.
FIG. 8 is a schematic diagram showing problems that occur when the wind pressure of the airflow blown from the downstream side in the sheet feeding direction is high.
FIG. 9 is a schematic cross-sectional view showing another example of the second air blowing device provided on the downstream side in the sheet feeding direction.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Image reader 2 External apparatus 3 Receiving part 4 Image recording control part 5 Image recording part 6 Sheet supply apparatus 7 Conveyance path 11 Photosensitive drum 12 Charging apparatus 13 Image writing apparatus 14 Developing apparatus 15 Transfer apparatus 16 Fixing apparatus 17 Cleaner 21, 61 Sheet tray 22 Paper feed roll group 23 Sheet guide 24, 65 Bottom plate 25 First air blowing device 26, 66 Second air blowing device 31, 62 Pickup roll 32, 63 Feeding roll 33, 64 Separating roll 41, 51, 71 Air outlets 42, 52, 72 Ducts 43, 53, 73 Fan 44 Shutter 45 Drive device 46 Control device

Claims (6)

Sheet storage means for stacking and storing sheets;
Sheet delivery means for delivering the sheets accommodated in the sheet accommodation means in order from the uppermost sheet;
A first air blowing unit that includes a blowing port facing a stacking end surface parallel to the feeding direction of the sheets stacked in the sheet storing unit, and blows an air flow from the blowing port to the stacked end surface of the sheet;
A second air blowing unit that includes a blowing port that is perpendicular to the feeding direction and opposed to the downstream stacking end surface of the sheets stacked in the sheet storage unit, and blows an air flow from the blowing port to the stacked end surface of the sheet. Means,
The sheet supply apparatus according to claim 1, wherein the second air blowing unit is set to have a small air volume or a low velocity blown from the first air blowing unit.     2. The sheet supply according to claim 1, wherein the second air blowing unit is restricted to have a small air volume or a low velocity so that sheets fed from the sheet storage unit one by one do not deviate from the conveyance path. apparatus. The first air blowing means has a plurality of blowing ports,
2. The sheet supply according to claim 1, wherein the blowout port on the most downstream side in the sheet feeding direction is provided at a position facing an end surface of the smallest size sheet that can be accommodated in the sheet accommodating portion. apparatus. The second air blowing means has a plurality of blowing holes,
The sheet feeding apparatus according to claim 1, wherein at least one outlet is provided at a position facing an end surface of the smallest sized sheet that can be accommodated in the sheet accommodating portion. The sheet storage means has a wall body that regulates the position of the stacked sheets on the downstream side in the sheet feeding direction,
The wall body is inclined downstream at a position facing at least the upper layer portion of the sheets stacked in the sheet accommodating means,
The sheet supply apparatus according to claim 1, wherein the outlet of the second air blowing unit is provided at a position including an inclined portion of the wall body. An image forming apparatus comprising the sheet feeding device according to claim 1 .

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