JPH0585457B2 - - Google Patents

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.

PRIOR TECHNOLOGY Generally, in paper feeding devices such as copying machines, various measures have been taken to prevent double feeding of paper. (Kokai No. 58-69842) is known. In addition, the applicant has also proposed a feed roller with a cutout in a part (Japanese Patent Application No. 1983-
181618).

The present invention relates to an improvement of the previously proposed 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. , the relationship between the present invention and the prior art will be explained.

Reference numeral 1 designates the housing of the entire copying machine. On the upper surface of this housing 1, a transparent document table 2 is provided on which a document to be copied is placed. is being supplied and discharged.

Inside the housing 1, there is a moving optical system 4 for exposure;
A photosensitive drum 5 is provided.

Originals 1 stacked on the original stocker 301
6 is fed out from the upper document by a feed roller 302, and is fed by a feed roller 3 which serves as a means for preventing double feeding.
03 and separation roller 304 to prevent double feeding, the document is sent to registration rollers 305 (constituting a conveyance means), and after a temporary standby, it is conveyed onto transparent document table 2 by drive belt 306 and set at a predetermined position. .

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

At this time, the reflected light from the original 16 irradiated by the original irradiation lamp 401 is reflected from the first mirror 4.
03, is reflected in the order of second mirror 404 and third mirror 405, and passes through lens 406 to fourth mirror 407.
An image is formed on the photoreceptor drum 5 by.

When the scanning exposure is completed as described above, the moving optical system 4 returns to the initial position, and the documents 16 are also sequentially discharged onto the document discharge table 15 through the ADF discharge 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 fed 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 paper is transferred to the copy paper while passing between the
0, and by the fixing roller 11 of the fixing device,
The toner image transferred to the copy paper is heated and fixed, and then discharged from the discharge roller 12 onto the discharge tray 13.

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

Note that the paper stocker 6 supplies special paper such as postcards, OHP film, and tracing paper as needed, and in this case, it is the same as that used for supplying originals on the stocker 301 described above. The paper feeding device 3 of FIG. 3 is used, but the rollers 601 and 602 in FIG. There is.

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.

A power gear 307 that rotates via a power transmission device (not shown) applies rotational force to the drive shaft (feed roller shaft) 308 of the paper feed roller 303 and the drive shaft (separation roller shaft) 309 of the separation roller 304 for preventing double feeding. is transmitted.

A belt 311 that transmits power to the drive shaft 310 of the feed roller 302 is wrapped around the drive shaft 308 of the paper feed roller 303, and a fan-shaped belt 311 that transmits power to the drive shaft 310 of the feed roller 302 is also connected to the drive shaft 308 and a fan-shaped belt for setting the timing of the feed roller 302. Between the timing cam 312 and the rotating shaft 313, there are gear trains 314, 315,
316 are provided.

The drive shaft 308 of the paper feed roller 303 and the rotation shaft 313 of the timing cam 312 are configured to rotate at the same gear ratio.

Further, the drive shaft 308 of the paper feed roller 303 includes
The drive shaft 31 of the feed roller 302 is attached to the tip end of the drive shaft 31 of the feed roller 302.
0, a balance weight, a roller support arm 318 that supports a balance weight 317, and a locking arm 319 by a timing cam 312.
Two swing levers 320 are loosely fitted.

A locking step portion 321 that engages with the timing cam 312 is formed at the tip of the locking arm 319 .

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

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 periphery of the paper feed roller 303, which reduces the resistance force while the original 16 comes into contact with the registration roller 305 and is fed downstream in the transport direction of the original. It has an effect. At this time, the document 16 is held between the paper feed roller 303 and the separation roller 304 in a flat state (see FIG. 7).

Next, the ADF in the electrostatic copying machine explained above
The operation of the original document feeding device 3 will be explained with reference to FIG.

Figures a to d in FIG. 5 are schematic diagrams for explaining the operating sequence of the document feeding device 3 of the ADF.

Reference numeral 16 indicates manuscript sheets stacked on the paper stocker 301.
The same applies to the copying sheets stacked on top, so hereinafter they will simply be referred to as "sheets."

Figure a shows the initial state, where the stocker 301
Above the upper paper 16 is a timing cam 312.
The feed roller 302 provided at the tip of the swing lever 320 that is locked at is lifted up.

When paper feeding starts from this state, the fan-shaped timing cam 312 starts to rotate to the right and the swing lever 32
0 is released, the feed roller 302
It falls onto the paper 16 on the stocker 301 and sends out the top paper 16 toward the paper feed roller 303 (the state shown in FIG. b).

The paper feed roller 303 is opposed to the separation roller 30 which rotates in the opposite direction to the paper feeding direction.
4, the paper 16 is sent toward the pair of registration rollers 305 while preventing double feeding of the paper 16 (the state shown in FIG. C).

In this state, when viewed from the width direction of the paper, it looks like the above-mentioned FIG.
This acts to strengthen the frictional force 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. d).

When the paper inclination correction and timing adjustment are completed, the registration rollers start feeding the paper 16 downstream in the paper transport direction, but at this time, the paper feed roller 303 in the state shown in FIG.
The cutout portion 322 provided in the separation roller 304 faces 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 the paper 1
6 has the effect of being rapidly sent downstream in the paper conveyance direction by the registration rollers 305 without any resistance.

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 3
The load on the double-feeding paper of 04 is also lost, and on the contrary, another drawback arises in that the separation effect of the double-feeding paper becomes uncertain.

Problems to be Solved by the Invention The present invention solves the above-mentioned drawbacks of the paper feed roller having a notch on the outer periphery of the roller, and improves the feed roller when feeding the paper downstream in the paper transport direction by a transport means such as registration rollers. Double feeding in a paper feeding device that maintains the double feeding prevention function without excessively increasing the paper feeding load by applying an appropriate frictional force to the separation roller combined with the paper roller. The purpose is to provide a prevention mechanism.

Means for Solving the Problems The present invention has a pair of parallel paper feed roller shafts and separation roller shafts, and the distance between the two axes is greater than the sum of the radius of the paper feed roller and the radius of the separation roller. A feeder that is somewhat small and equipped with a double-feed prevention means formed by alternately arranging a plurality of paper feed rollers and separation rollers in a staggered manner, and a conveyance means provided downstream of the double-feed prevention means. In the paper device, the outer periphery of the paper feed roller includes a first part and a second part that have different frictional forces with the paper, and the second part is made smaller in width than the first part. The contact area with the paper is reduced, and when the paper transported by the double-feed prevention means is further transported downstream by the transport means, the second contact area of the paper feed roller It is characterized in that the portion faces the separation roller.

Function: When the paper conveyed by the double-feed prevention means configured as described above is further conveyed downstream by the conveyance means, the second portion of the paper feed roller of the double-feed prevention means, that is, the frictional force Since the small roller portion faces the separation roller, the frictional force between the paper and the paper feed roller is not large. In addition, a moderate frictional force acts between the paper and the separation roller, and it is possible to reliably prevent the paper from passing through which is to be fed in duplicate.

EXAMPLES The present invention will be specifically explained below with reference to examples. However, the copying machine and paper feeding device 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.

As is clear from the figure, the paper feed roller 350 in FIG. 1 differs from the paper feed roller 303 in FIG.
22 is provided with a roller portion 351 having a small width, whereas the latter is not provided with any roller portion.

With this configuration, the paper feed roller 350 has a roller portion 352 that has a large contact area and a large frictional force when feeding the paper to the outer periphery of the roller, and a roller portion 351 that has a small contact area and a small frictional force.
This means that it has been formed.

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

The double feed prevention mechanism of the present invention is the same as that shown in FIGS. 3 and 4 as described above, and simply uses the paper feed roller 350 shown in FIG. 1 instead of the paper feed roller 303 used therein. which uses
The operations shown in FIGS. 5A to 5C are exactly the same as those described above.

However, in the state shown in FIG. 5d, the paper feed roller 350 is
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 seen from the width direction of the paper in FIG. 5d is not the state in FIG. 7 but close to the state in FIG. It is.

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.

Effects of the Invention According to the present invention, a pair of parallel paper feed roller shafts and separation roller shafts are provided, and the distance between the two axes is slightly smaller than the sum of the radius of the paper feed roller and the radius of the separation roller. Further, in a paper feeding device including a double feeding prevention means formed by alternately arranging a plurality of paper feeding rollers and separation rollers in a staggered manner, and a conveyance means provided on the downstream side of the double feeding prevention means. , the outer circumferential portion of the paper feed roller is made up of a first portion and a second portion that have different frictional forces with the paper, and the second portion is made smaller in width than the first portion to feed the paper. The second portion of the paper feed roller is configured to have a small contact area with the paper feed roller, and when the paper transported by the double feeding prevention means is further transported downstream by the transport means, the second portion of the paper feed roller is separated. Since it is characterized by facing the roller, it is possible to minimize the paper feeding load on the conveying means when feeding the paper from the conveying means to the downstream side, and the separation mechanism combined with the paper feeding roller By applying an appropriate frictional force to the rollers, double feeding of sheets can be prevented without impairing the function of the separation rollers.

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 the paper feed roller in the present invention;
FIG. 2 is a perspective view of a paper feed roller in the prior art;
3 is a schematic cross-sectional view of an electrostatic copying machine to which the present invention is applied, FIG. 4 is a perspective view of the main parts of the document feeding device in FIG. 3, and FIG. 5 is a document feeding device of the ADF shown in FIG. 4. Figures a to d are explanatory diagrams showing the operation order, Figure 6 is a state diagram seen from the width direction of the paper in Figure 5 in Figure 5, and Figure 7 is a diagram showing the state in Figure 5 as seen from the paper width direction. d is a state diagram seen from the width direction of the paper. 303...Paper feed roller, 304...Separation roller, 305...Registration roller (constituting the conveyance means), 308...Paper feed roller drive shaft (paper feed roller shaft), 309...Separation roller drive shaft (separation roller) roller shaft), 351...roller part with low frictional force,
352...Roller part with large frictional force.

Claims (1)

[Claims] 1. It has a pair of parallel paper feed roller shafts and separation roller shafts, the distance between the two axes is slightly smaller than the sum of the radius of the paper feed roller and the radius of the separation roller, and
A paper feeding device comprising a double feeding prevention means formed by alternately arranging a plurality of paper feeding rollers and separation rollers in a staggered manner, and a conveyance means provided on the downstream side of the double feeding prevention means. The outer periphery of the paper feed roller is made up of a first part and a second part that have different frictional forces with the paper, and the second part is made smaller in width than the first part to improve the friction with the paper. The contact area is configured to be small, and when the paper conveyed by the double feeding prevention means is further conveyed downstream by the conveyance means, the second portion of the paper feed roller contacts the separation roller. A paper feeding device characterized by facing each other.