JPH03172249A - Paper feeder - Google Patents

Abstract

PURPOSE:To surely separate paper forms by providing the first reverse roller, which is rotated in a direction equal to that of a conveying roller, opposedly to roller surfaces of the conveying roller. CONSTITUTION:Double-fed paper forms are fed between nips of a conveying roller 30 and reverse rollers 31, 32. Here because of a small coefficient of friction between papers forms, paper returning force by a torque limiter 40 overcomes friction force between the paper forms, and the torque limiter 40 is plated in an engaging condition. In this way, the reverse rollers 31, 32 are rotated in a direction equal to that of a shaft 22. Accordingly, now in addition to a reverse roller 25 always rotated in a direction equal to that of the shaft 22, also by the reverse rollers 31, 32 the double fed paper forms are press- returned to the side of a paper feed cassette 4. Thus, the double fed paper forms can be surely separated. Accordingly, the paper form can be surely separated even in the case of high speed specification.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a paper feeding device, and particularly to a paper feeding device for feeding sheets one by one from a paper storing section to a paper receiving section while preventing double feeding of sheets. Regarding a paper feeding device.

[Conventional technology]

For example, an image processing apparatus such as a copying machine or a laser printer is provided with a paper feeding device for feeding paper to an image forming section. As this paper feeding device, Japanese Patent Application Laid-Open No. 60-2424
The paper feeding device shown in No. 77 is shown in FIGS. 4A and 4B.

In FIG. 4A, shafts 100 and 101 are arranged vertically opposite each other. The shafts 100 and 101 are each rotated in the direction of the arrow by a drive mechanism (not shown). A conveyance roller 102 is fixed on the shaft 100 for conveying the paper in the paper storage section to the image forming section. On the shaft 101, a reverse roller 103 and a driven roller 10 are arranged opposite to the roller surface of the conveying roller 102.
4 are provided.

The attachment of each of these rollers will be explained using FIG. 4B (longitudinal sectional view). In FIG. 4B, a core material 107 is attached to the shaft 101 via a one-way clutch 10B. A driven roller 104 is rotatably provided in the center of this core material 107 via a sliding ring 105. A pair of reverse rollers 103 are fixed on both sides of the driven roller 104 on the core material 107 .

In such a conventional device, the paper 110 is
When the paper 110 is fed in the direction of arrow F, the driven roller 104 rotates following the conveyance roller 102, and the sheet 110 is conveyed to the image forming unit side through the nip between the conveyance roller 102 and the driven roller 104. In addition, during double feeding of paper, the double fed paper 111 is transferred to the conveyance roller 10 along with the paper 110.
2 and the driven roller 104. Then, a returning force from the reverse roller 103 acts on the paper 111. This return force is greater than the frictional force between the sheets 110 and 111, so that the conveyance of the sheet 111 is stopped. On the other hand, the conveyance roller 10
A feeding force of 2 is applied, and the paper 110 is thereby transported to the image forming section side.

[Problem to be solved by the invention]

In the conventional configuration, the reverse roller 103 always rotates in the same direction as the conveyance roller 102 when conveying paper. When double feeding occurs, this reverse roller effectively works to return the double fed sheets.

At this time, the driven roller 10/I rotates in the opposite direction according to the movement of the double-fed sheets.

However, when high-speed processing is required, the conveyance roller 102 and the driven roller 104 rotate at high speed during sheet conveyance. Therefore, a problem arises in that the driven roller 104 cannot be quickly reversed during double feeding. For this reason,
When multiple sheets are fed, it may not be possible to push back the double-fed sheets sufficiently, and the sheets may not actually be separated.

SUMMARY OF THE INVENTION An object of the present invention is to provide a paper feeding device that can reliably separate sheets of paper that are multi-fed during multi-feeding of paper.

[Means to solve the problem]

A paper feeding device according to the present invention is a paper feeding device that feeds sheets one by one from a paper storage section to a paper receiving section while preventing double feeding of sheets, and includes a conveying roller and a first reverse roller. and a second reverse roller.

The conveyance roller conveys the paper in the paper storage section to the paper receiving section. The first reverse roller is
It is provided to face the roller surface of the conveyance roller and rotates in the same direction as the conveyance roller. The second reverse roller is provided opposite to the roller surface of the transport roller, and is provided with a torque limiter so that it rotates following the transport roller during normal paper transport and rotates in the same direction as the transport roller during double paper transport. It is.

[Effect]

In the paper feeding device according to the present invention, when paper is transported, the transport roller rotates, and the second reverse roller rotates as a result of the transport roller. As a result, the paper in the paper storage section is conveyed to the paper receiving section through the nip between the conveyance roller and the second reverse roller.

Furthermore, during double feeding of sheets, in addition to the first reverse roller rotating in the same direction as the conveyance roller, the second reverse roller also rotates in the same direction as the conveyance roller. Therefore, the double-fed sheets are moved in the opposite direction to the paper conveyance direction by the first and second reverse rollers, and the double-fed sheets are separated.

In this way, when paper is double-fed, not only the first reverse roller but also the second reverse roller exerts a force that pushes back the multi-fed paper in the opposite direction to the conveyance direction, thereby ensuring that the paper is separated. be able to.

[Embodiment] FIG. 2 shows the overall configuration of a copying machine in which an embodiment of the present invention is adopted. The copying machine main body 1 is composed of an upper main body 1a and a lower main body 1b.

The main body upper part 1a can be opened and closed around a hinge part 18. On the top of the copying machine body l, there is a document table 2.
is fixed, and a document presser 3 is attached to the upper part of the document table 2 so as to be openable and closable. ? A paper feed cassette 4 is removably attached to the left side of the 10,000 machine main body l. Also,
A paper discharge tray 6 from which copied sheets are discharged is mounted on the right side.

Inside the copying machine main body 1, an optical system 7 for reading image information of a document is provided on the upper side la of the main body. The optical system 7 includes a light source, a mirror lens, and the like. Further, a photosensitive drum 8 on which an electrostatic latent image is formed on the surface of the photosensitive drum 8 is arranged at the center inside the lower part 1b of the main body. Around the photoreceptor drum 8, there are a charging device 9 that charges the photoreceptor drum 8 to a predetermined charge, a developing device 10 that develops the electrostatic latent image, and a transfer device 1 that transfers the toner image onto paper.
1. A paper separating device 12 for separating paper from the photosensitive drum 8 and a cleaning device E13 for removing toner on the photosensitive drum 8 are arranged in this order. A paper feed conveyance path 14 for conveying paper is provided between the paper feed cassette 4 and an image forming section constituted by the photosensitive drum 8 and the like. Further, a paper discharge transport path 15 is provided downstream of the image forming section in the paper transport direction. Paper discharge conveyance path 15
A fixing device ff16 that fixes the toner image on the ejected paper and a paper ejection roller 17 are provided between the paper ejection tray 6 and the paper ejection tray 6.

A paper feed device 20 according to an embodiment of the present invention is provided between the paper feed cassette 4 and the paper feed conveyance path 14. This paper feed device 20 feeds paper from the paper feed cassette 4 to a paper feed conveyance path 14.
A conveyance roller 30 for conveying to the side and a conveyance roller 30
It has a reverse roller 31 which is arranged opposite to the reverse roller 31 to prevent double feeding of sheets.

In FIGS. 1A and 1B showing details of the paper feeding device 20, horizontally extending shafts 21 and 22 are arranged at a predetermined interval. Each of the shafts 21 and 22 is rotated in the direction of the arrow by a drive mechanism (not shown). A conveyance roller 30 is provided on the shaft 21 via a one-way clutch 23. On the other hand, a reverse roller 31 is disposed on the shaft 22, facing the conveyance roller 30.
32 are provided at predetermined intervals. The reverse rollers 31 and 32 are rotatably supported on the shaft 22 via bearings 24, respectively. Reverse roller 31
, 32, a torque limiter 40 is attached to each side.

A schematic configuration of this torque limiter 40 is shown in FIG. 3. Each torque limiter 40 has a similar configuration, and here, the torque limiter 40 on the reverse roller 31 side is
I will explain about it. In FIG. 3, the counterclockwise arrow points in the direction of rotation of the shaft 22. The reverse roller 31 has a roller portion 31a and a protrusion 31b formed on the side thereof. A limiter spring 41 is fitted into this protrusion 31b. This limiter spring 41 is formed from a wire rod twisted in the direction shown in the drawing. A limiter boss 42 is attached to the limiter spring 41 from the side. The limiter boss 42 has a boss portion 44 that fits into the limiter spring 41, and a pin 45 that can engage with one end 41a of the wire of the limiter spring 41.

The inside of the limiter collar 43 covers the limiter spring 41 from the outside. Further, the limiter boss 42 is fixed to the shaft 22 (FIG. 1).

A reversing roller 25 is fixed on the shaft 22 between the reversing rollers 31 and 32. In addition, the reverse roller 31
, 32 are made of a material having a larger coefficient of friction than the reversing roller 25.

Further, a spacer 26 having a small Fjm coefficient is arranged between the reverse rollers 31 and 32 and the reverse roller 25.

Next, the operation will be explained.

When the print key on the main body of the copying machine is pressed, the paper feeder 2
0 drive system is driven, and the shafts 21, 22 (FIG. 1) rotate in the directions of the arrows. The rotation of the shaft 21 causes the conveyance roller 30 to rotate via the one-way clutch 23. On the other hand, due to the rotation of the shaft 22, the reverse rollers 31 and 32 try to rotate in the same direction as the shaft 22 via the torque limiter 40. However, the roller surfaces of the reverse rollers 31 and 32 are in pressure contact with the roller surface of the conveyance roller 30,
A large load is acting on the reverse rollers 31, 32. Therefore, the torque limiter 40 slips, and the reverse rollers 31 and 32 rotate following the conveyance roller 30.

Next, the paper taken out from the paper feed cassette 4 (FIG. 2) is fed between the nip between the transport roller 30 and the reverse rollers 31 and 32. At this time, the torque limiter 40
The paper returning force is set to be lower than the paper feeding force F (FIG. 3) produced by the transport roller 30. Therefore, the torque limiter 40 slips as described above, and the reverse rollers 31 and 32 rotate as a result of the conveyance roller 30.

Then, the paper is transferred to the transport roller 30 and the reverse roller 3.
The paper feed conveyance path 14 passes between the nips 1 and 32 (Fig. 2).
transported to the side. Note that during this paper conveyance, the reversing roller 25 is rotating together with the shaft 22. For this reason,
A resistance force in the opposite direction to the transport direction acts on the lower surface of the paper being transported, but this resistance force is smaller than the paper feeding force due to the difference in the coefficient of friction with the transport roller 30.

Therefore, this reversing roller 25 does not interfere with the paper feeding operation.

Next, a case will be described in which a plurality of sheets of paper are sent out from the paper feed cassette 4 during paper conveyance. A zero-fold-feeded sheet is sent between the nip between the conveyance roller 30 and reverse rollers 31 and 32.

In this case, since the coefficient of friction between the sheets is small, the sheet returning force by the torque limiter 40 overcomes the frictional force between the sheets, and the torque limiter 40 enters the holding state. As a result, the reverse roller 31 rotates in the same direction as the shaft 22.

Therefore, in this case, in addition to the reverse roller 25 constantly rotating in the same direction as the shaft 22, the reverse roller 31
, 32, the paper that has been fed in duplicate is placed in the paper cassette 4.
pushed back to the side. In this way, multiple feeds can be used.

Note that since the reverse rollers 31 and 32 are rotated by the conveyance roller 30 during paper conveyance, the surface of the reverse rollers 31 and 32 is hardly worn that day. According to
Double-fed sheets can be reliably separated.

[Other Examples]

(a) In the embodiment described above, the reverse rollers 31 and 32 are arranged on both sides of the reverse rotation 1j-roller 25, but the present invention is not limited to this.

For example, by arranging a reverse roller in the center of the shaft 22,
It is also possible to arrange reversing rollers on both sides of the
In this case as well, the same effects as in the embodiment described above can be achieved.

The torque limiter 40 attached to the reverse rollers 31 and 32 does not need to be of the coil spring type shown in the above embodiment; for example, it may be a powder type type using magnetic powder as a medium. [Effects of the Invention] According to the paper feeding device of the present invention, since the first and second reverse rollers rotate in the same direction as the conveyance roller when paper is double fed, the paper can be reliably separated by these T-rollers. It is also possible to meet high-speed specifications.

[Brief explanation of the drawing]

FIG. 1A is a perspective partial view of a paper feeding device according to an embodiment of the present invention, FIG. 1B is a schematic cross-sectional configuration diagram thereof, and FIG. 2 is a schematic vertical cross-sectional diagram of a copying machine employing an embodiment of the present invention. , FIG. 3 is an exploded perspective view showing the internal structure of the torque limiter, and FIGS. 4A and 4B are views corresponding to FIGS. 1A and 1B of the conventional device. 4...Paper feed cassette, 20...Paper feed device, 21,2
2... Axis, 25... Reverse roller, 30... Conveyance roller, 31.32... Reverse r-1-ra, 40
...Torque limiter.

Claims (1)

[Claims] (1) A paper feeding device for feeding paper one sheet at a time from a paper storage section to a paper supplying section while preventing double feeding of paper, the paper feeding device conveying the paper from the paper storage section to the paper supplying section. a first reverse roller, which is provided opposite to the roller surface of the transport roller and rotates in the same direction as the transport roller; A paper feeding device comprising: a second reverse roller that rotates as a result of the transport roller and is provided with a torque limiter so as to rotate in the same direction as the transport roller during double feeding of sheets.