JPS61238624A - Double feed preventive mechanism in paper feeder - Google Patents

Abstract

PURPOSE:To prevent copying paper from being fed double, by making a part of width of a paper feed roller smaller to some extent and forming a part small in frictional force, while giving moderate friction force to a separation roller, in case of a double-feed preventive mechanism of a paper feeder for an electrostatic process copying machine of the like. CONSTITUTION:A part large in frictional force and another part small in that both are formed in the circumference of a paper feed roller 303. That is to say, in a paper feed roller 350, a narrow roller part 351 is installed in a notch part 3222 of a roller circumferential part. Thus, a roller part 352 large in frictional force at the time of feeding paper and the roller part 351 small in the force both are formed in this paper feed roller 350. These parts are provided with a pair of paper feed rollers 308 and a separation roller shaft 309 each and applied to such a paper feeder that the total of both radii of the paper feed roller 303 and a separation roller 304 is somewhat smaller than a shaft-to- shaft distance between them and plural paper feed rollers 303 and the separation roller 304 are alternately set up in zigzag form.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a double-feed prevention mechanism for sheet feeding devices such as electrostatic copying machines and printing machines.

Generally, in paper feeding devices such as copying machines, various measures are taken to prevent double feeding of paper. Utility Model Application Publication No. 19842 (Japanese Unexamined Utility Model Publication No. 19842) and a feed roller with a cutout provided in a part of the feed roller that the applicant has already applied for (
Japanese Patent Application No. 181618/1983) is known.

The present invention relates to an improvement of the double-feed prevention mechanism in which the feed roller is provided with a notch. First, a schematic cross-sectional view of an electrostatic copying machine to which the present invention is applied is shown in FIG. Explain the relationship between

1 indicates the housing of the entire copying machine, and the upper surface of this housing 1 is provided with a document placement table 2 to be copied, and documents are fed and ejected by a paper feeder 3 of an ADF (automatic document supply bag W). It is now possible to do so.

Inside the housing l, a moving optical system 4 for exposure and a photosensitive drum 5 are provided.

The originals 16 stacked on the original stocker 301 are sent out from the top original by a sending roller 302.
The sheet is fed to the registration rollers 305 while being prevented from double feeding by the feed roller 303 and separation roller 304, and after a temporary standby, it is conveyed onto the transparent document table by the drive belt 306 and set at a predetermined position.

Then, the lamp 401, condensing reflector 402, and first mirror 403 of the moving optical system 4 for exposure move from the position shown by the solid line.
The second mirror 404 and the third mirror 405 move at a speed of ■ to the position indicated by the two-dot chain line to the right in the figure.
Scanning exposure is performed by moving at a speed of 1/2V to the position indicated by the dotted chain line.

At this time, the reflected light from the original 16 irradiated by the original irradiation lamp 401 is reflected in the order of the first mirror 403, the second mirror 404, and the third mirror 405, and is reflected by the lens 40.
6, and is imaged onto the photosensitive drum 5 by the fourth mirror 407.

When the scanning exposure is completed as described above, the moving optical system 4 returns to the initial position, and the originals 16 are also sequentially ejected onto the original ejection table 15 by the ADF ejection path 14.

On the other hand, the photosensitive drum 5 rotating in the direction of the arrow is uniformly charged to a specific polarity by a charging corona discharger 501, and an electrostatic latent image is formed on the drum surface by the formation of the reflected light image of the original. is formed.

This latent image is visualized by a well-known magnetic brush developing device 9, and the copy paper sent from the paper feed cassette 7 or 8 is transferred to a transfer corona discharger 502, a separation corona discharger 503, and a drum 5. The toner image is transferred to the copy paper while passing through the gap, and is sent by the ejection belt 10. The toner image transferred to the copy paper is heated and fixed by the fixing roller 11 of the fixing device, and then transferred from the ejection roller 12 onto the ejection tray 13. It is discharged.

A cleaning device 16 cleans residual toner on the photosensitive drum 5 after the toner image is transferred to the copy paper.

In addition, from the paper stocker 6, postcards and
It supplies special paper such as OHP film and tracing paper. In this case as well, the same paper feeder N3 as that used to feed originals on the stocker 301 described above is used, but the paper feeder N3 shown in FIG. The rollers 601 and 602 are simply feed rollers, and the registration rollers 605 adjust the timing with respect to the original 16.

The main part of the document feeder 3 of the ADF (automatic document feeder) of the electrostatic copying machine shown in FIG. 3 has a mechanism as shown in the perspective view of FIG. 4.

Power gear 30 rotates via a power transmission device (not shown)
7, the drive shaft of the paper feed roller 303 (paper feed roller shaft)
308 and the drive shaft (separation roller shaft) 309 of the separation roller 304 for preventing double feeding.

The drive shaft 308 of the paper feed roller 303 has a bell l-311 that transmits power to the drive shaft 310 of the feed roller 302.
A gear train 3 is provided between the drive shaft 30B and the rotating shaft 313 of a fan-shaped timing cam 312 for setting the timing of the feed roller 302.
14.315.316 are provided.

Drive shaft 308 of paper feed roller 303 and timing cam 31
The second drive shaft 313 is configured to rotate at the same gear ratio.

Further, the drive shaft 308 of the paper feed roller 303 has at its tip a roller support arm 318 that supports the drive shaft 310 of the feed roller 302, a balance weight 317, and a locking arm 319 by a timing cam 312. A swing lever 320 of the feed roller 302 is loosely fitted.

A timing cam 312 is provided at the tip of the locking arm 319.
A locking step portion 321 is formed to engage with.

The paper feed roller 303 is made of a material such as rubber that has a relatively large coefficient of friction, and the separation roller 304 is made of a material such as synthetic resin that has a relatively small coefficient of friction compared to the paper feed roller.

As clearly shown in FIG. 6, the paper feed roller 303 and separation roller 304 are designed so that the distance between their axes is slightly smaller than the sum of their radii, and during normal paper feeding, , the document 16 is fed while being curved in a wave-like manner.

A notch 322 is formed in a part of the outer circumference of the paper feed roller 303, so that the document 16 can be transferred to the registration roller 3.
05 and has the effect of reducing the resistance force while the document is fed downstream in the conveying direction. At this time, the document 16 is in a flat state, and the paper feed roller 303 and separation roller 304
(See Figure 7).

Next, the operation of the document feeder W3 of the ADF in the electrostatic copying machine described above will be explained with reference to FIG.

Figures (a) to (d) in Figure 5 are schematic explanatory diagrams showing the operating sequence of the document feeder 3 of the ADF.

Reference numeral 16 indicates the original sheets stacked on the stocker 301, and the same applies to the copy sheets stacked on the paper trays 1 to 6.
It's called "paper".

Figure (a) does not show the initial state, and the stocker 301''-
A feed roller 302 provided at the tip of a swing lever 320 locked by a timing cam 312 is lifted above the paper 16 .

When paper feeding is started from this state, the fan-shaped timing cam 312 starts turning to the right and releases the locking of the swing lever 320, so that the feed roller 302 falls onto the paper 16 on the stocker 301 and the topmost paper 16 to paper feed roller 3
03 [state shown in figure (b)].

The paper feed roller 303 separates the paper 1 from the paper feed roller 303 by a separation roller 304 which is located in the opposite direction and rotates in the opposite direction to the paper feeding direction.
The paper 16 is fed toward the pair of registration rollers 305 while preventing double feeding of the paper 16 [state shown in Figure (C)].

This state is as shown in FIG. 6 described above when viewed from the width direction of the paper, and acts to strengthen the frictional force of the paper feed roller 303 against the paper 16.

Eventually, when the paper feed roller 303 rotates once, the leading edge of the paper 16 comes into contact with the registration roller 305, takes up some deflection for inclination correction, and then stops.

At this time, the swing lever 320 is pushed up again by the timing cam 312, and the feed roller 302 is pulled up from above the paper 16 on the stocker 301 [the state shown in FIG. 3(d)].

When the paper inclination correction and timing adjustment are completed, the paper 16 starts to be sent downstream in the paper conveyance direction by the registration rollers, and at this time, the paper 16 starts to be fed downstream in the paper transport direction.
The cutout portion 322 provided in the paper feed roller 303 in the state is oriented toward the separation roller 304, and acts to reduce the load on the paper 16 that is sandwiched and fed between them.

That is, as shown in FIG. 7, when viewed from the paper feed width direction, the paper is completely flat, and there is no resistance to the paper flow.
This has the effect that the paper is sent downstream in the paper conveyance direction by the registration roller 305 during rapid feeding.

However, when using the paper feed roller 303 having such a notch 322, the paper can be quickly fed downstream from the registration roller 305 with a light load, but the separation roller 304 double-feeds the paper. This causes another disadvantage in that the load on the paper is also lost, and the separation effect of the double-feed paper becomes uncertain.

The present invention solves the above-mentioned drawback of the paper feed roller having a notch on the outer periphery of the roller, and when feeding the paper downstream in the paper conveyance direction by registration rollers, etc., the paper feed roller and the By applying an appropriate frictional force to the combined rollers separated by 11 degrees,
It is an object of the present invention to provide a double-feed prevention mechanism in a paper feed device that can maintain the double-feed prevention function without excessively increasing the load on paper feed.

□Sono n point) Fragment 1 Sotomo Sap Means The present invention forms a portion with a large frictional force and a portion with a small frictional force on the outer periphery of a paper feed roller, and a pair of paper feed roller shafts parallel to each other. It has a separation roller axis, the sum of the radius of the paper feed i-ra and the radius of the separation roller is comfortably smaller than the distance between the two axes, and the plurality of paper feed rollers and separation rollers are arranged alternately in a staggered manner. The present invention is applied to a paper feed device arranged in the paper feed device, and by reducing part of the width of the paper feed roller as a portion with a small frictional force, a paper feed roller with a specific low load is obtained.

Hereinafter, the present invention will be specifically explained with reference to examples, but the copying machine and paper feeder to which the present invention is applied are the same as those shown in FIGS. 3 and 4 described in the prior art. ,
Since the only difference is the structure of the paper feed roller, the same components are given the same reference numerals, and the description of the structures that have already been described will be omitted to avoid duplication.

FIG. 1 is a perspective view of the paper feed roller 350 of the double feed prevention mechanism of the present invention, and FIG. 2 is a comparison of the paper feed roller 303 of the double feed prevention mechanism of the prior art described above with the roller 350. FIG.

The paper feed roller 350 in FIG. 1 is replaced by the paper feed roller 303 in FIG.
The difference is that, as is clear from the figure, in the former, 11 small roller parts 351 are provided in the notch 322 on the outer circumference of the roller, whereas in the latter, none are provided. There are only points.

With this configuration, the paper feed roller 350 has a roller portion 352 with a large contact area and a large frictional force when feeding the paper around the outer periphery of the roller, and a roller portion 351 with a small contact area and a small frictional force. It's going to happen.

This paper feed roller 350 has a roller portion 35 with low frictional force.
1, as shown in the figure, reduces the width to reduce the contact area and, as a result, reduces the frictional force.

The protruding amount of this part can be made somewhat smaller to reduce the pressing force against the paper, or the roller part 351 can be used as a comb.
In design, the radius of curvature may be increased to form a partially flat surface, or even only this portion may be made of synthetic resin.

Next, a double feed prevention mechanism of the present invention using the paper feed roller 350 shown in FIG. 1 will be explained.

As mentioned above, the double feed prevention mechanism of the present invention is as shown in FIGS. 3 and 4.
The feed roller 350 shown in FIG. 1 is the same as that shown in FIG.
The operations shown in FIG. 5 (a) to (C) are exactly the same as those described above.

In this case, the paper feed roller 350 has a roller portion 3 with a small frictional force.
51, the load during paper feeding is not completely eliminated compared to when paper feeding roller 303 is used. The load can be reduced depending on the width of the roller portion 351.

Moreover, in the case of the present invention, the state of the sheet viewed from the inside in FIG. 5(d) is not the state of FIG. 7 but close to the state of FIG.
It is being forced upon us.

That is, although the frictional resistance of the paper 16 against the paper feed roller 303 has become smaller, the frictional resistance against the separation roller 304 has not become much smaller.

Therefore, when the registration rollers 305 feed the sheets downstream in the paper conveyance direction, the separation rollers 304 can sufficiently perform their functions to reliably prevent double feeding.

According to the present invention, when paper is fed downstream in the paper conveyance direction by registration rollers, etc., the paper feed load is kept as low as possible, and at the same time, the separation roller combined with the paper feed roller is Therefore, by applying an appropriate frictional force, double feeding of copy sheets can be prevented without impairing the function of the separation roller.

In addition, by appropriately selecting the width of the portion of the paper feed roller that has a small frictional force, it is possible to adjust the frictional force applied to the separation roller and obtain an excellent effect of preventing double feeding.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a paper feed roller in the present invention, FIG. 2 is a perspective view of a paper feed roller in the prior art, FIG. 3 is a schematic sectional view of an electrostatic copying machine to which the present invention is applied, and FIG. 4 is a perspective view of a paper feed roller in the present invention. FIG. 3 is a perspective view of the main parts of the document feeding device, and FIG. 5 is an explanatory diagram of the operation of the document feeding device of the ADF shown in FIG.
d) is an explanatory schematic diagram showing the operating sequence, and FIG. 6 is a view taken from the middle direction of the paper in FIG. 5 (C). FIG. 7 is a state diagram seen from the inside of the paper in FIG. 5 (d). 308...Paper feed roller drive shaft (paper feed roller shaft) 309
...Separation roller drive shaft (separation roller shaft) 303...
Paper feed roller 304...separation roller

Claims (2)

[Claims] (1) It has a pair of parallel paper feed roller shafts and separation roller shafts, the sum of the radius of the paper feed roller and the radius of the separation roller is comfortably smaller than the distance between the two axes, and A paper feeding device in which paper rollers and separation rollers are arranged alternately in a staggered manner, and the outer periphery of the paper feeding roller is composed of a roller portion with a large frictional force and a roller portion with a small frictional force. Double feed prevention mechanism for paper feeding devices. (2) A double feeding prevention mechanism in a paper feeding device according to claim 1, wherein the width of the roller is reduced in the portion of the paper feeding roller where the frictional force is small.