JP4004864B2 - Sheet feeding apparatus, image forming apparatus including the same, and image reading apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sheet feeding apparatus, an image forming apparatus including the sheet feeding apparatus, and an image reading apparatus, and more particularly to a configuration for separating and conveying sheets into one sheet.
[0002]
[Prior art]
In recent years, image reading apparatuses, image forming apparatuses such as printers, copiers, facsimile machines, and multifunction machines having a plurality of functions are separated by separating sheets such as originals and recording sheets one by one. A sheet feeding device for feeding the sheet is provided. As such a sheet feeding device, a device that employs a retard separation system capable of separating a sheet with high reliability from a low speed to a high speed is widely used.
[0003]
Here, the retard separation system includes a feeding roller that rotates in the sheet feeding direction, and a separation roller that presses the feeding roller with a predetermined pressure and rotates in a direction opposite to the sheet feeding direction, in other words, in a direction to return the sheet. The sheet is separated and fed one by one by (retard roller).
[0004]
In addition, a torque limiter that generates slip at a predetermined torque value or more is provided in the drive transmission path of the separation roller, and a sheet is conveyed between the feed roller and the separation roller in a state where there is no sheet. In this state, the load composed of frictional force with the feed roller or the sheet exceeds a predetermined torque value of the torque limiter, and the torque limiter slips and the drive is not transmitted. Thus, one sheet can be reliably conveyed without damaging the sheet.
[0005]
In addition, when a plurality of overlapped sheets enter the pressure contact portion (hereinafter referred to as a nip portion) of the feed roller and the separation roller, the separation roller rotates backward without following rotation. The sheet in contact with the feeding roller is conveyed in the feeding direction by sliding between the sheets, and the sheet in contact with the separation roller is returned to the sheet support portion by reverse rotation of the separation roller.
[0006]
In order to satisfy the conveyance and separation conditions in the above-described configuration, it is necessary to satisfy the following expression.
F1>F3>F4> F2 (1)
F5> F4 (2)
here,
F1 = μ1 × N: the force that the feed roller advances the sheet F2 = μ2 × N: the force that the sheets move together F3 = μ3 × N: the force that the separation roller stops the sheet F4 = T ÷ r: the separation roller rotates Force F5 = μ4 × N: force with which the feed roller turns the separation roller μ1: friction coefficient between the feed roller and the sheet μ2: friction coefficient between the sheet and the sheet μ3: friction coefficient between the separation roller and the sheet μ4: feed roller Friction coefficient between the roller and the separation roller N: pressure applied to the separation roller r: radius of the separation roller T: idling torque of the torque limiter
By the way, conventionally, in order to ensure a more reliable separation performance, the separation roller 52 is made of an elastic body as shown in FIG. 7 and is moved in the vicinity of the separation roller 52 in the direction of the feed roller 51 by deformation of the elastic body. In some cases, a conveyance regulation guide 54 is provided so as to protrude.
[0008]
Here, the conveyance regulation guide 54 is formed such that the distance from the feed roller 52 becomes narrower as it approaches the nip portion between the feed roller 51 and the separation roller 52. Further, the conveyance regulation guide 54 is formed of a flexible member, and an uneven shape that abuts the feed roller 51 is formed on the surface on the feed roller side.
[0009]
In this way, the separation roller 52 is formed of an elastic body, and the conveyance regulation guide 54 that protrudes relatively in the direction of the feed roller 51 is provided, so that a stack of many sheets enters the nip portion. Even in this case, a part of the entering sheet bundle on the side of the separation roller can be received by the uneven shape of the conveyance restriction guide 54 without hindering the operation of the separation roller as shown in FIG. Only a small number of sheets that can be separated can enter the roller nip portion.
[0010]
Further, even when the leading edge of the sheet that has entered a plurality of sheets is caught by the uneven shape of the conveyance regulation guide 54, the separation roller 52 made of an elastic body pushes out the sheet as the number of sheets decreases due to the separation operation, thereby avoiding poor sheet feeding. can do.
[0011]
As another sheet separation method, there is a separation pad method that includes a feeding roller that rotates in the sheet feeding direction and a friction pad that presses the feeding roller with a predetermined pressure, and separates and feeds the sheets one by one.
[0012]
[Problems to be solved by the invention]
However, in the sheet feeding apparatus employing such a retard roller system, for example, in the case of a vertical sheet feeding mechanism in which the sheet is inclined and the sheet is caused to enter the nip by its own weight, the weight of the sheet S is also considered. Therefore, a sheet having a high friction coefficient may not be received by the conveyance regulation guide 54 and a plurality of sheets may enter as one sheet.
[0013]
In such a situation, the above F2 (the force with which the sheets are brought together) becomes higher and exceeds F4 (the force with which the separation rollers are turned), and the separation roller 52 is turned with the sheet bundle, The entered sheet bundle is fed as it is.
[0014]
Accordingly, the present invention has been made in view of such a current situation, and a sheet feeding device capable of reliably separating and feeding sheets one by one, an image forming apparatus including the sheet feeding device, and an image reading device. The object is to provide an apparatus.
[0015]
[Means for Solving the Problems]
The present invention provides a sheet feeding device that separates and feeds the sheets supported by the sheet support portion one by one, and is provided downstream of the sheet support portion, and a sheet feeding unit that feeds the sheet; Separation feeding that has separation means that is pressed against the sheet feeding means and is rotatable in the same direction as the sheet feeding means or in the opposite direction, and separates and feeds the sheets one by one. A feeding regulation guide provided in the vicinity of the separation means so as to protrude in the direction of the sheet feeding means and regulates the number of sheets entering the pressure contact portion between the sheet feeding means and the separation means; The conveyance regulation guide is formed of a flexible member, and is pressed by a sheet entering between the sheet feeding unit and the separation unit so as to be able to bend toward the separation unit side. Bends against the separating means It is characterized in that it has to be.
[0016]
In the present invention, a torque limiter is provided in the drive transmission means for transmitting the drive to the separation means, and when the load applied to the separation means from the sheet feeding means or the fed sheet exceeds a predetermined value, The transmission restriction is provided when the separation roller can be rotated by the sheet feeding means or the fed sheet by interrupting transmission of driving by a torque limiter, and the separation roller can be rotated by the torque limiter. The rotation of the separation roller is regulated by the contact of the guide with the separation means.
[0017]
In the invention, it is preferable that the separation unit is formed of an elastic body, and the conveyance regulation guide relatively protrudes toward the sheet feeding unit due to elastic deformation of the separation unit.
[0018]
Further, the present invention is characterized in that the force for restricting the rotation of the separation roller in the same direction as the sheet feeding means is increased in accordance with the amount of deflection of the conveyance regulating guide.
[0019]
Further, the present invention is characterized in that an engaging portion is provided for engaging the separating means and the conveyance regulation guide when the conveyance regulation guide is bent.
[0020]
According to the present invention, a one-way clutch is provided at a position of the separating unit that comes into contact with the conveyance regulation guide when the conveyance regulation guide is bent, and the sheet feeding unit of the separation roller via the one-way clutch. It is characterized by restricting rotation in the same direction.
[0021]
According to the present invention, an image forming apparatus includes an image forming unit and any one of the sheet feeding devices described above that feeds a sheet to the image forming unit.
[0022]
According to the present invention, an image reading apparatus includes an image reading unit and the sheet feeding device according to any one of the above that feeds a sheet to the image reading unit.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0024]
FIG. 2 is a diagram showing the configuration of the image reading apparatus according to the first embodiment of the present invention.
[0025]
In the figure, 100 is an image reading apparatus, 100A is an image reading apparatus main body, 100B is a sheet stacking section that is a sheet support section that stacks and supports sheets S in an inclined state, 102 and 103 are surfaces for reading images of sheets S, and A back image reading unit 100C is a sheet feeding device that feeds the sheet S supported by the sheet stacking unit 100B to the front and back image reading units 102 and 103.
[0026]
The sheet feeding apparatus 100C includes a feeding roller 1 that is a sheet feeding unit and a separation roller 2 that is a separation unit that is in pressure contact with the feeding roller 1. The sheet feeding device 100C is configured to store sheets S stacked on the sheet stacking unit 100B. A separation feeding unit 1A for separating sheets one by one is provided. Reference numeral 3 denotes a main motor for rotationally driving the feed roller 1 in the sheet conveying direction and reversely driving the separation roller 2 formed of an elastic body.
[0027]
Next, an image reading operation in the image reading apparatus 100 configured as described above will be described.
[0028]
When the image reading operation is started, the plurality of sheets S placed on the sheet stacking unit 100 </ b> B are separated into one sheet by the pressure roller 1 and the separation roller 2 that are in pressure contact with each other. Thereafter, the sheet passes through the platen rollers 102a and 103a in close contact with the front and back image reading units 102 and 103.
[0029]
The image formed on the front surface or the back surface of the sheet S is line-scanned by passing through the front and back image reading units 102 and 103 and output to the outside as an electric signal. Further, after the image is read in this way, the sheet S is discharged to the outside by the discharge roller pair 104 (discharge roller pair 104a, 104b).
[0030]
In the figure, reference numeral 101 denotes an upper unit that constitutes the sheet feeding apparatus main body including the separation roller 2, the back surface image reading unit 103, the upper paper discharge roller 104a, and the like. The upper unit 101 is normally closed as shown in FIG. 2A. However, for example, in the case of jam processing, cleaning and maintenance of rollers, the upper unit 101 is shown in FIG. ) Is opened upward as shown in FIG. By opening in this way, the separation roller 2 can be separated from the feed roller 1.
[0031]
FIG. 1 is a diagram illustrating the configuration of the sheet feeding apparatus 100 </ b> C, and 2 a is a shaft portion of the separation roller 2. The separation roller 2 includes a torque limiter (not shown) in its drive transmission path, and in the state where there is no sheet S or when one sheet is conveyed between the feed roller 1 and the separation roller 2, Since the load received by the separation roller 2 from the feed roller 1 or one sheet is larger than the torque value when the torque limiter slides, the drive is not transmitted, and the separation roller 2 rotates following the sheet conveyance direction (following rotation). It is supposed to be.
[0032]
Further, in a state where a plurality of stacked sheets S enter the nip portion of these rollers 1 and 2, the separation roller 2 rotates in the reverse direction without following rotation, whereby the sheet in contact with the feed roller 1 S is conveyed in the feeding direction by sliding between the sheets, and the sheet in contact with the separation roller 2 is returned to the sheet stacking unit 100B by the reverse rotation of the separation roller 2.
[0033]
In the figure, reference numeral 4 denotes a conveyance regulation guide. In the present embodiment, the conveyance regulation guide 4 causes the sheet S that has been overlapped more than specified to enter the nip portion between the feed roller 1 and the separation roller 2. I try not to. In the present embodiment, the conveyance regulation guide 4 is provided between the two separation rollers 2 as shown in FIG.
[0034]
Here, the conveyance regulation guide 4 is located on the inner side of the outer periphery of the separation roller 2, and the surface facing the feed roller 1 is formed with irregularities as shown in FIG. In this way, the separation roller 2 is formed of an elastic body, and the conveyance regulation guide 4 is provided, so that even if a bundle of a large number of sheets enters, a part of the entering sheet on the separation roller side is separated. It can be received by the concavo-convex shape of the conveyance regulation guide 4 without hindering the roller operation, and only a small number of sheets S that can be separated can enter the nip portion.
[0035]
By the way, the conveyance regulation guide 4 is formed of a flexible member, and as a result, when the number of sheets S entering the nip portion increases, the conveyance regulation guide 4 is pressed by the feed roller 1 through the sheet, and FIG. As shown in (b), the shaft portion 2a of the separation roller 2 comes into pressure contact with a large force.
[0036]
When the conveyance restriction guide 4 abuts on the shaft portion 2a of the separation roller 2 as described above, the rotational torque value of the separation roller 2 that rotates with the friction between the conveyance restriction guide 4 and the shaft portion 2a of the separation roller 2 is obtained. (Torque value when changing from the reverse rotation state to the revolving state) gradually increases, making it difficult for the separation roller 2 to revolve. That is, even if the torque limiter slips due to the load received from the sheet S that has entered the nip portion of the separation roller 2 and the separation roller 2 can be rotated, the conveyance restriction guide 4 and the shaft portion 2a of the separation roller 2 The separation roller 2 is not rotated by the frictional force, and the sheets are not sent out in a bundle.
[0037]
Thereby, for example, even if a plurality of sheets S having a high friction coefficient enter the nip portion in a state where the sheets S overlap with each other due to their own weight, the rotation of the separation roller 2 is inhibited. As a result, the force (F2) that the sheets move together does not exceed the torque value (F4) that starts the rotation of the separation roller 2, that is, the separation roller 2 does not rotate. Each sheet can be picked up and conveyed to the image processing unit.
[0038]
In this way, the conveyance regulation guide 4 is formed of a flexible member, and the conveyance regulation guide 4 is pressed by the sheet S entering the nip and bent toward the separation roller so as to contact the shaft portion 2a of the separation roller 2. By doing so, even if a plurality of sheets S having a high friction coefficient cannot be received by the conveyance regulation guide 4 and enter the nip portion as a single sheet, the rotation of the separation roller 2 can be stopped. Further, as the number of sheets S entering the nip portion increases, the force with which the conveyance regulation guide 4 comes into contact with the shaft portion 2a of the separation roller 2 increases, and it becomes difficult to rotate the sheet, so that the sheets are not sent out in a bundle. A reliable sheet separation is possible.
[0039]
Accordingly, it is possible to prevent the sheet in contact with the separation roller from entering, and even when a plurality of sheets having a high friction coefficient are set, the sheets can be reliably separated and conveyed one by one. As a result, it is possible to eliminate the situation where the sheet processing is delayed due to double feeding or the like, and it is possible to provide a highly reliable sheet feeding apparatus.
[0040]
For example, as shown in FIG. 5, by forming the engaging portion engaging with the contact portion of the shaft portion 2a of the separation roller 2 with the conveyance restriction guide 4, the conveyance restriction is achieved even when a plurality of sheets enter. The guide 4 is bent and the contact portion is engaged. As a result, the accompanying rotation of the separation roller 2 can be reliably stopped, and bundle feeding can be prevented.
[0041]
Further, as shown in FIG. 6, by providing the one-way clutch 5 on the same axis as the separation roller 2 and at the position where the conveyance regulation guide 4 abuts, the conveyance regulation guide 4 bends even when a plurality of sheets enter, and the one-way clutch As a result, the follow-up torque of the separation roller 2 changes to a high value, and bundle feeding can be prevented. The one-way clutch 5 is configured so that the rotation of the separation roller 2 in the return direction can be freely performed regardless of the contact of the conveyance regulation guide 4, so that sufficient separation performance can be secured.
[0042]
In the above embodiment, the rotation torque is changed by the conveyance regulation guide 4 coming into contact with the shaft portion 2a of the separation roller 2. However, in the present invention, the portion where the conveyance regulation guide 4 abuts is the shaft portion 2a. For example, a cylindrical member may be fixed on the same axis of the separation roller 2 and the conveyance regulating guide 4 may come into contact therewith. In other words, any configuration may be used as long as the conveyance regulation guide 4 is pressed by the sheet so as to contact the member on the separation roller side so that the rotational torque of the separation roller 2 can be changed.
[0043]
In the above description, the image reading apparatus has been described as an example. However, the sheet feeding apparatus according to the present invention includes an image forming unit, and a sheet is fed to the image forming unit by the sheet feeding apparatus. Needless to say, the present invention can also be applied to an image forming apparatus.
[0044]
【The invention's effect】
As described above, according to the present invention, the conveyance regulation guide that regulates the number of sheets entering the pressure contact portion between the sheet feeding unit and the separation unit is formed by the flexible member, and the conveyance regulation guide is formed on the pressure contact portion. By pressing the entering sheet and bending to the separating means side so as to come into contact with the separating means, even if a plurality of overlapping sheets enter, the sheets are surely separated one by one. Can be fed.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration of a sheet feeding device provided in an image reading apparatus according to a first embodiment of the present invention.
FIG. 2 is a diagram illustrating a configuration of the image reading apparatus.
FIG. 3 is a perspective view of a main part of a separation feeding unit of the sheet feeding apparatus.
FIG. 4 is an enlarged view of a main part of a separation feeding unit of the sheet feeding apparatus.
FIG. 5 is a diagram illustrating a configuration of a sheet feeding apparatus according to a second embodiment of the present invention.
FIG. 6 illustrates a configuration of a sheet feeding apparatus according to a third embodiment of the present invention.
FIG. 7 is a diagram illustrating a configuration of a conventional sheet feeding apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Feed roller 1A Separation feed part 2 Separation roller 3 Main motor 4 Conveying restriction guide 5 One-way clutch 100 Image reading apparatus 100A Image reading apparatus main body 100B Sheet stacking part 100C Sheet feeding apparatus 102 Front surface reading part 103 Back surface reading part 104 Paper discharge Part S Sheet

Claims (8)

In the sheet feeding device that separates and feeds the sheets supported by the sheet support unit one by one,
Provided downstream of the sheet support portion, and configured to be able to rotate in the same direction as or in the opposite direction to the sheet feeding means, and a sheet feeding means for feeding the sheet, and a pressure contact with the sheet feeding means Separating means for separating and feeding the sheets one by one, and
A conveyance regulating guide that is provided in the vicinity of the separating unit so as to protrude in the direction of the sheet feeding unit and regulates the number of sheets entering the pressure contact portion between the sheet feeding unit and the separating unit;
With
The conveyance regulation guide is formed of a flexible member, and is provided so as to be able to bend toward the separation means by being pressed by a sheet entering between the sheet feeding unit and the separation unit, and the conveyance regulation guide is bent and the separation is performed. A sheet feeding device characterized in that the sheet feeding device comes into contact with the means. A torque limiter is provided in the drive transmission means for transmitting the drive to the separation means, and when the load applied to the separation means from the sheet feeding means or the fed sheet exceeds a predetermined value, the torque limiter is driven by the torque limiter. The separation means of the conveyance regulating guide is provided so that the separation roller can be rotated by the sheet feeding means or the fed sheet with the transmission interrupted, and the separation roller can be rotated by the torque limiter. The sheet feeding device according to claim 1, wherein the rotation of the separation roller is regulated by contact with the sheet. 3. The sheet feeding according to claim 1, wherein the separation unit is formed of an elastic body, and the conveyance regulation guide relatively protrudes toward the sheet feeding unit due to elastic deformation of the separation unit. apparatus. 4. The force for restricting rotation of the separation roller in the same direction as the sheet feeding unit is increased in accordance with the amount of deflection of the conveyance regulation guide. 5. The sheet feeding apparatus according to item. 5. The sheet according to claim 1, further comprising an engaging portion that engages the separation unit and the conveyance regulation guide when the conveyance regulation guide is bent. Feeding device. A one-way clutch is provided at a position of the separating unit that contacts the conveyance regulating guide when the conveyance regulating guide is bent, and the separation roller rotates in the same direction as the sheet feeding unit via the one-way clutch. The sheet feeding apparatus according to any one of claims 1 to 4, wherein the sheet feeding device is regulated. An image forming apparatus comprising: an image forming unit; and the sheet feeding device according to claim 1 for feeding a sheet to the image forming unit. An image reading apparatus comprising: an image reading unit; and the sheet feeding device according to claim 1 for feeding a sheet to the image reading unit.

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