JP3673915B2 - Double feed prevention mechanism in paper feeder - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multifeed prevention mechanism in a paper feeding device used for, for example, a copying machine, a facsimile machine, and a printer.
[0002]
[Prior art]
Conventionally, as an example of a double feed prevention mechanism in a paper feeder, the one shown in FIG. 4 is known. In this double feed prevention mechanism, the paper (P) is fed from the cassette (42) by the pick-up roller (41) supported by the swing arm (40) and moved up and down each time the paper is fed. ) And a separating pad (44) biased toward the separating roller (43) (see FIG. 4 (a)).
[0003]
[Problems to be solved by the invention]
However, the conventional double feed prevention mechanism has the following problems. That is, depending on the remaining amount of paper in the cassette (42), the paper (P) can be inserted into the separation pad (44) at various angles, so that a plurality of paper (P ) Is fed out from the cassette (42), only the bottom sheet (P) is stopped, and the other sheet (P) can be transported by the rotational force of the separating roller (43) in an overlapping state. Yes (see FIGS. 4 (b) and (c)).
[0004]
SUMMARY OF THE INVENTION An object of the present invention is to provide a double feed prevention mechanism in a paper feeding device that solves the above-described problems and can reliably prevent multiple paper feeds.
[0005]
[Means for Solving the Problems]
In the multifeed prevention mechanism in the paper feeding device according to the present invention, the paper is fed from the paper stacking portion between the separation roller and the separation pad by the pickup roller that is supported by the swing arm and moves up and down. A multi-feed prevention mechanism in a paper feeding device, wherein a paper guide guide is provided on a swinging arm that supports the pickup roller, and the paper guide guide is disposed between a separation surface of the separation pad and a required surface when the pickup roller is lowered. A guide surface is provided which forms an angle and guides the sheet fed from the sheet stacking portion toward the separating surface and abuts the leading end of the sheet against the separating surface. Since the leading edge of the sheet is brought into contact with the separating surface by the guide surface, only the uppermost sheet is separated from the separating sheet. It is conveyed through between La and said separating pad, in which the rest of the sheet is adapted to be stopped by frictional resistance between the separating surface.
[0006]
In the double feed prevention mechanism in the paper feeding device of the present invention, it is preferable that an angle formed by the guide surface of the paper guide and the separation surface of the separation pad when the pickup roller is lowered is 25 to 60 degrees.
[0007]
Further, in the double feed prevention mechanism in the paper feeding device of the present invention, a lower paper guide guide for guiding the paper fed from the paper stacking unit toward a guide surface of the paper guide guide is provided below the paper guide guide. In some cases, the upper end of the lower sheet guide is located above the lower end of the separation pad.
[0008]
It is preferable that the guide surface of the lower paper guide is formed of a highly durable material having slidability, for example, polyethylene glycol terephthalate.
Further, the lower paper guide may be provided with a separating surface.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, the present invention is applied to a copying machine.
[0010]
FIG. 1 shows the overall configuration of the copying machine, FIG. 2 shows the configuration of the main part thereof, and FIG. 3 shows the operation of the double feed prevention mechanism. In the following description, the left and right of each drawing are referred to as the left and right respectively.
[0011]
In FIG. 1, the image forming apparatus includes an apparatus main body (1) that occupies most of the lower side thereof, and a document reading section (2) positioned at the top.
[0012]
The document reading unit (2) has a document placing table (3) made of transparent glass or the like on the upper surface, and a scanner optical system (4) is disposed below the document placing table (3). The document table (3) is covered with an openable / closable cover (5). The scanner optical system (4) includes an exposure light source (7), a plurality of reflecting mirrors (8), (9) and (10), an imaging lens (11), and a CCD (12) as a photoelectric conversion element.
[0013]
The left side portion of the apparatus main body (1) below the document reading unit (2) is largely removed except for the lower portion, and this portion is a paper discharge unit (13).
[0014]
The apparatus main body (1) is provided with an image forming unit (14), a paper feeding device (15), a control device (not shown) for controlling the image forming apparatus, and the like.
[0015]
The image forming unit (14) includes a photosensitive drum (16), a charger (17) for charging the photosensitive drum (16) to a predetermined potential, and an electrostatic latent image on the surface of the charged photosensitive drum (16). A laser beam irradiation device (18) for forming the image, a developing device (19) for developing the electrostatic latent image on the surface of the photosensitive drum (16) into a visible image with toner, and recording a toner image on the photosensitive drum (16) A transfer charger (20) for transferring to the paper (P) and a cleaning device (21) for removing residual toner on the surface of the photosensitive drum (16) are provided.
[0016]
The paper feeding device (15) includes a cassette (22) (paper stacking unit) mounted in the device main body (1) below the paper discharge unit (13) and storing a plurality of recording papers (P) in a stacked state. A pickup roller (23) for feeding the recording paper (P) out of the cassette (22), a double feed prevention mechanism (24) disposed at the tip of the cassette (22), and a downstream side of the cassette (22) And a pair of fixing rollers arranged on the downstream side of the image forming unit (14) and a registration roller (25) for aligning the toner image on the photosensitive drum (16) and the recording paper (P). A roller (26) and a pair of paper discharge rollers (27) disposed on the upper right side of the paper discharge section (13) of the apparatus main body (1) are provided. The pickup roller (23) is supported on the left end of a swing arm (28) that swings up and down around the right end, and is rotationally driven by a drive source (not shown). The pickup roller (23) is moved up and down by the swinging of the swinging arm (28) .The pickup roller (23) is lowered during paper feeding and the leading edge of the recording paper (P) has passed the double feed prevention mechanism (24). When it is detected, it rises.
[0017]
As shown in FIG. 2, the double feed preventing mechanism (24) is configured as follows.
[0018]
A separating roller (29) is rotatably supported at the right end of the swing arm (28), and a separating pad (30) is disposed below the separating roller (29) with the separating surface (30a) facing diagonally upward to the left. Has been. The separating roller (29) is rotatably supported around the swing center axis of the swing arm (28) and is driven to rotate by a drive source (not shown). The separating pad (30) is urged diagonally to the left by the compression coil spring (31) so that the separating surface (30a) is pressed against the peripheral surface of the separating roller (29). A paper guide (32) is provided at the right end of the swing arm (28) so as to be positioned upstream of the contact portion between the separating roller (29) and the separating pad (30). When the pickup roller (23) is lowered, the paper guide (32) guides the recording paper (P) that forms a required angle with the separating surface (30a) of the separating pad (30) and is sent out from the cassette (22). A guide surface (32a) is provided. The guide surface (32a) is located upstream of the contact portion between the separation roller (29) and the separation pad (30).
[0019]
The angle θ between the separation surface (30a) of the separation pad (30) and the guide surface (32a) of the paper guide (32) when the pickup roller (23) is lowered is in the range of 25 to 60 degrees. Yes. This range is obtained based on the results of experiments conducted by changing the angle θ in the range of 0 to 90 degrees. If the angle θ is less than 25 degrees, double feeding may occur and exceeds 60 degrees. May cause paper jams.
[0020]
A lower paper guide that guides the recording paper (P) fed from the paper cassette (22) toward the guide surface (32a) of the paper guide guide (32) below the separating roller (29) and the paper guide guide (32). A guide (33) is arranged. The upper end portion of the lower paper guide guide (33) is bent upward and diagonally to the right, and the bent portion serves as the guide portion (34), and the left side surface of the paper guide guide (34a) is inclined upward and diagonally to the right. ). The upper end of the guide part (34) is located above the lower end of the judgment pad (30). The surface of at least the guide part (34) of the lower paper guide guide (33) is covered with a polyethylene glycol terephthalate film such as “Mylar” (trade name, manufactured by DuPont) having excellent sliding properties and high durability. .
[0021]
In such a configuration, when the recording paper (P) is fed, the swing arm (28) is swung downward and the recording paper in the cassette (22) is picked up by the pickup roller (23) which has come to the lowered position. (P) is sent out. Here, when one recording sheet (P) is sent out, the recording sheet (P) is sent through between the separating roller (29) and the separating pad (30).
[0022]
When a plurality of recording sheets (P) are sent out from the cassette (22) by the pickup roller (23), double feed is prevented by the action of the double feed prevention mechanism (24). The operation of the double feed prevention mechanism (24) at this time will be described with reference to FIG.
[0023]
The plurality of recording papers (P) sent out by the pickup roller (23) first come into contact with the separation surface (34a) of the lower paper guide guide (33), and the recording paper (P) is subjected to front separation. (See FIG. 3A). Next, the recording paper (P) is guided diagonally right upward toward the guide surface (32a) of the paper guide (32) by the guide portion (34), and further, the separation pad (30) is separated by the guide surface (32a). It is guided obliquely downward to the right toward the surface (30a), and its tip abuts against the separating surface (30a) (see FIG. 3 (b)). Then, only the uppermost recording sheet (P) is fed by the rotational force of the separating roller (29) and is conveyed between the separating roller (29) and the separating pad (30), and the remaining recording sheets ( P) is stopped by the frictional resistance with the separation surface (30a) (see FIG. 3 (c)). In this way, double feeding of the recording paper (P) is prevented.
[0024]
In the above-described embodiment, the present invention is applied to the recording paper (P) paper feeding device (15) in the copying machine. However, the present invention is not limited to this, and the present invention is not limited to this. The present invention can also be applied to a recording paper feeding device in two or more composite image forming apparatuses of a printer and a facsimile machine. The present invention is also applicable to a document sheet feeding device to the document reading unit of these image forming apparatuses and a document sheet feeding device to the document reading unit of the scanner.
[0025]
【The invention's effect】
According to the double feed prevention mechanism in the paper feeding device of the present invention, the paper guide is provided on the swing arm that supports the pickup roller so as to be positioned on the upstream side of the separating roller. Since the guide surface forms a required angle with the separation surface of the separation pad when descending and guides the sheet fed from the sheet stacking portion toward the separation surface, a plurality of sheets are fed by the pickup roller. Even when the paper is fed out from the cassette, the leading ends of all the papers are guided by the guide surface of the paper guide and are fed into the separation surface of the separation pad at a required angle. Therefore, only the uppermost sheet is transported by the rotation force of the separating roller, and the sheets other than the uppermost sheet are stopped by the frictional resistance with the separating surface, thus preventing multiple sheets from being fed multiple times. can do. In addition, since the paper guide is provided on the swing arm that supports the pickup roller, the paper guide guide contacts the paper only when the paper is fed by the pickup roller during paper feeding, and the leading edge of the paper is detected. After passing between the roller and the separation pad, the paper guide also rises by the swing of the swing arm for lifting the pickup roller, so that the guide surface of the paper guide does not come into contact with the paper. Therefore, in this case, it is possible to reduce the load of paper conveyance and to prevent the guide surface from being worn. In addition, when a paper jam occurs, it can be easily solved by swinging the swing arm upward.
[0026]
In the double feed prevention mechanism in the paper feeding device of the present invention, when the angle between the guide surface of the paper guide and the separating surface of the separating pad when the pickup roller is lowered is 25 to 60 degrees, a plurality of sheets Can be more reliably prevented.
[0027]
In the double feed prevention mechanism in the paper feeding device of the present invention, a lower paper guide guide for guiding the paper fed from the paper stacking unit toward the guide surface of the paper guide guide is disposed below the paper guide guide. When the upper end of the lower sheet guide guide is positioned above the lower end of the separation pad, the sheet fed by the pickup roller is fed obliquely upward by one end by the lower sheet guide guide, and its leading end is Since it abuts against the guide surface of the paper guide and is sent further diagonally downward, it abuts against the separation surface of the separation pad, so that the paper entry angle to the separation surface of the separation pad is surely set to the required angle. This makes it possible to more reliably prevent multiple feeding of a plurality of sheets.
[0028]
In the multifeed prevention mechanism in the paper feeding device of the present invention, when the guide portion surface of the lower paper guide is formed of a highly durable material having slidability, the guide portion of the lower paper guide that is in sliding contact with the paper Thus, the sliding performance of the guide portion is maintained over a long period of time.
[0029]
In the multifeed prevention mechanism in the paper feeding device of the present invention, if the lower paper guide guide has a separating surface, a plurality of sheets fed from the cassette by the lower paper guide guide are subjected to front separation by the separating surface. Therefore, it is possible to more reliably prevent a plurality of sheets from being double-fed.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an overall configuration of a copying machine to which the present invention is applied.
FIG. 2 is a partially enlarged view of FIG. 1 showing the double feed prevention mechanism of the present invention.
FIG. 3 is a diagram showing the operation of the double feed prevention mechanism of the present invention.
FIG. 4 is a view corresponding to FIG. 3 showing the operation of the conventional double feed prevention mechanism.
[Explanation of symbols]
(22): Cassette (paper stacking section)
(23): Pickup roller
(24): Double feed prevention mechanism
(28): Swing arm
(29) ： Sabaki Roller
(30): judgment pad
(30a): judgment surface
(32): Paper guide
(32a): Guide surface
(33): Lower paper guide
(34): Guide section
(34a): judgment surface
(P): Recording paper

Claims (5)

A double feed prevention mechanism in a paper feeding device configured to feed paper between a separation roller and a separation pad from a paper stacking portion by a pickup roller supported by a swing arm and moving up and down, A paper guide is provided on a swing arm that supports the pickup roller, and the paper guide guide forms a required angle with a separation surface of the separation pad when the pickup roller is lowered, and is sent out from the paper stacking unit. A guide surface that guides the sheet toward the separating surface and abuts the leading end of the sheet against the separating surface, and the leading ends of the plurality of sheets fed from the sheet stacking portion are separated by the guide surface. By being brought into contact with the surface, only the uppermost sheet passes between the separating roller and the separating pad and is conveyed. , Multi-feed preventing mechanism in the sheet feeding apparatus remaining paper is adapted to be stopped by frictional resistance between the separating surface.   The multifeed prevention mechanism in the sheet feeding device according to claim 1, wherein an angle formed between the guide surface of the sheet guide and the separating surface of the separating pad when the pickup roller is lowered is 25 to 60 degrees.   A lower sheet guide guide for guiding the sheet fed from the sheet stacking unit toward the guide surface of the sheet guide guide is disposed below the sheet guide guide, and the upper end of the lower sheet guide guide The double feed prevention mechanism in the paper feeding device according to claim 1, wherein the mechanism is located above the lower end of the pad.   The double feed prevention mechanism in the paper feeding device according to claim 3, wherein a surface of the lower paper guide guide is formed of a highly durable material having sliding properties.   The multi-feed preventing mechanism in the paper feeding device according to claim 3 or 4, wherein the lower paper guide is provided with a separating surface.

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