JPH0289737A - Roller-type paper feeding device - Google Patents

Abstract

PURPOSE:To stabilize the rotation of the driving group as well as the carrier speed of paper by forming the frictional surface of a friction pad such as to set the frictional force of the downstream side part in the paper carrier direction smaller than that of the upstream side part. CONSTITUTION:Even if a sheet of paper 15 closest to a paper feeding roller 25 is fed into a paper feeding device 22 being attached to the paper sheet conveyed following the rotation of the roller by frictional force, the paper sheet 15 is stopped by a friction pad 25, and conveyance does not take place. Accordingly, paper is conveyed sheet by sheet. Moreover, since the frictional surface of the friction pad 24 is made such that the frictional force of the downstream side part in the paper carrier direction is set smaller than that of the upstream side part, the load provided to the paper sheet 15 decreases gradually when the rear edge of the paper sheet slips out from between the paper feeding roller 25 and the pad, thereby generating no big load fluctuation. Accordingly, in this paper feeding device 22, both the rotation of the driving group and the carrier speed of the paper 15 are stabilized.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a roller type paper feeding device, particularly a roller type paper feeding device for feeding paper sheets one by one from a paper storage portion storing a large number of sheets of paper to a paper receiving portion. The present invention relates to a roller type paper feeding device.

[Prior Art] For example, Japanese Patent Application Laid-Open No. 57-13039 discloses a copying machine equipped with a paper feed roller disposed near the exit of a paper storage section and a friction pad having a friction surface in contact with the paper feed roller. A roller-type paper feeding device used in machines and the like is shown.

In this paper feeding device, paper is pulled out from a paper feeding table by rotating a paper feeding roller. At that time, the sheet of paper closest to the paper feed roller is 1? The friction force follows the rotation of the roller and is conveyed to the transfer device. On the other hand, even if other sheets of paper are attached to the paper that is being conveyed to the transfer device side and are fed to the paper feed device! ? It is stopped by a scrubbing pad and no conveyance takes place. As a result, the sheets are fed one by one to the transfer device.

The paper supplied to the transfer device side is first stopped by a cyst []-ra, and then sent to the transfer device at a predetermined timing. At this time, the transfer roller of the paper feeding device is in a driven state and applies a load in a tensile direction to the paper.

[Problem to be solved by the invention]

In the conventional paper feeding device, the friction surface of the friction pad has a friction coefficient sufficient to stop sheets other than the necessary sheets, and the surface is uniformly formed. Therefore, even after the paper feed roller of the paper feed device is in the driven state, the friction pad continues to press the paper with strong frictional force and continue to apply a load to the paper. As a result, when the trailing edge of the paper comes out from between the roller and the pad, the large load that has been applied to the paper is removed all at once, resulting in large load fluctuations.

As a result, in the conventional paper feeding device, the rotation of the drive system becomes unstable, the speed at which the paper is conveyed by the registration rollers fluctuates, and the image transferred to the paper by the transfer device becomes distorted. .

An object of the present invention is to prevent large load fluctuations when the trailing edge of paper passes between the roller and the band in a paper feeding device using a paper feeding roller and a friction pad.
The goal is to stabilize the rotation of the drive system and stabilize the paper conveyance speed.

[Means to solve the problem]

A roller type paper feeding device according to the present invention is a paper feeding device that feeds sheets of paper one by one from a paper storage section storing a large number of sheets to a paper receiving section. This paper feeding device includes a rotatable paper feeding roller disposed near the exit of a paper storage section, and a friction pad that extends along the outer peripheral surface of the paper feeding roller and has a friction surface that elastically presses against the roller. We are prepared. Further, the frictional force of the friction surface is set to be smaller in a downstream portion than in an upstream portion in the paper conveyance direction.

[Effect]

In the roller type paper feeding device according to the present invention, paper is taken out from the paper storage section by rotating the paper feeding roller.

At this time, the sheet of paper closest to the paper feed roller is conveyed by following the rotation of the roller due to frictional force. On the other hand, even if the other paper adheres to the paper being conveyed and is supplied to the paper feeder, it is stopped by the friction pad,
No transportation will take place. As a result, the sheets are conveyed one by one.

Here, the frictional force of the friction surface of the friction pad is set to be smaller on the downstream side than on the upstream side in the paper transport direction, so when the trailing edge of the paper leaves between the paper feed roller and the band, In this case, the load applied to the paper gradually decreases and no large load fluctuations occur. Therefore, in the paper feeding device according to the present invention, the rotation of the drive system is stabilized, and the paper conveyance speed is stabilized.

〔Example〕

FIG. 1 is a schematic partial view of a copying machine incorporating a roller type paper feeding device according to the present invention. In FIG. 1, copying machine 1
A photosensitive drum 12 disposed inside the photoreceptor drum 1 is a cylindrical member on which a latent image based on a document (not shown) is formed, and a developed image is formed by a developing device (not shown). A transfer device 13 is arranged at the lower end of the photoreceptor drum 12 .

A paper feed cassette 14 is arranged below the photosensitive drum 12. The paper feed cassette 14 is a box-shaped member, and a large number of sheets of paper 15 are stacked and stored inside. The tip of the pressing lever 16 is in contact with the lower surface of the mounting plate of the paper feed cassette 14. The pressing lever 16 is the fulcrum 1
The paper feed cassette 14 is always elastically pressed upward by a spring 18.

Between the transfer device 13 and the paper feed cassette 14, a transport path 19 is provided which is bent into an approximately L-shape.

The conveyance path 19 includes two parallel paths arranged at a slight interval.
It is composed of a pair of flat plates, between which the paper 15 can pass. The transfer device 1 in the conveyance path 19
3, a registration roller 20 consisting of a pair of rollers is provided. The registration rollers 20 are driven at predetermined timing and at a predetermined speed in order to timely supply the transported paper 15 to the transfer device 13 side. On the upstream side of the registration rollers 20, a feed roller 21 consisting of a pair of rollers is arranged in the conveyance path 19.

A paper feed device 22 is arranged between the upstream end of the conveyance path 19 and the outlet of the paper feed cassette 14 . Paper feed device 2
2 mainly includes a paper feed roller 25 and a friction pad 24 arranged along the outer periphery of the paper feed roller 25.

The paper feed roller 25 is driven to rotate in the direction of arrow X at a predetermined timing and at a predetermined speed.

More specifically, the friction pad 24 is constructed as shown in FIG. In addition, in FIG. 2, arrow Y indicates paper 1
5 (FIG. 1).

In the friction pad 24, the pad body 26 is made of, for example, CR.
It is a rubber member and has a curved surface 27 that curves along the paper feed roller 25. Further, on the side opposite to the curved surface 27, three grooves 28 extending in the direction of the rotation center line of the paper feed roller 25 are formed in the pad body 26. A flat pressure plate 29 is fitted into each groove 28, respectively.

One end of an arm 32 is rotatably connected to the lower part of each pressure plate 29 via a pin.

Each arm 32 projects left and right alternately, and its intermediate portion is rotatably connected via a pin to the upper end portion of a bracket 33 rising from below. The bracket 33 is fixed to a support base 31 fixed to the main body of the copying machine. The lower part of each bracket 33 and each arm 32
A spring 34 is compressed between the pad body 26 and the other end, and the pad body 26 is always elastically urged toward the paper feed roller 25 side. That is, as a result, the curved surface 27 is always pressed against the paper feed roller 25. Here, the three springs 34 are set so that the spring constants become smaller in order from the upstream side in the paper conveyance direction. Therefore, the pressing force of the pressure plate 29 based on the spring 34 is set to become weaker in order from the upstream side in the sheet conveyance direction.

Next, the action will be explained.

In response to the copy command, the paper feed roller 25 in FIG. 1 starts rotating in the X direction. As a result, the topmost sheet of the sheets 15 in the paper feed cassette 14 is caught between the paper feed roller 25 and the pad body 26 by the frictional force of the paper feed roller 25. At this time, the paper 15 below may also move toward the friction pad 24 along with the top paper 15;
The sheet of paper 15 underneath is moved by the frictional force of the pad body 26.
It is stopped at the friction pad 24. The uppermost sheet 15 is conveyed within the conveyance path 19 as the paper feed roller 25 rotates, and is also conveyed and driven within the conveyance path 19 by the feed rollers 21 . Once the leading edge of the paper 15 comes into contact with the registration roller 20, the paper 15 enters a standby state.

At that point, the driving of the paper feed roller 25 and the feed roller 21 is stopped, and the paper feed roller 25 and the feed roller 21 are in a driven state.

On the other hand, the photosensitive drum 12 starts rotating, and a latent image based on a document (not shown) is formed thereon, and a developed image is formed by a developing device (not shown). And photosensitive drum 1
Registration roller 2 at a predetermined timing with respect to the rotation of 2.
0 starts rotating, the paper 15 is conveyed to the transfer device 13 side, and an image corresponding to the original is transferred onto the paper 15. When the paper 15 is conveyed by the registration rollers 20, the paper feed roller 25 is in a driven state, and the paper 15 remains sandwiched between the paper feed roller 25 and the pad body 26.
It slides on the pad body 26. This sliding action applies a tensile load to the paper 15. and,
Eventually, the rear end of the paper 15 comes out from between the paper feed roller 25 and the pad body 26.

By the way, since the tensile force of the spring 34 that defines the pressing force of the pad body 26 is arranged to become weaker as it goes downstream, the curved surface 27 of the pad body 26 has a lower part on the downstream side than the upstream part. The frictional force of the parts is reduced. Therefore, when the rear end of the paper 15 comes out from between the paper feed roller 25 and the pad body 26, the load applied to the paper 15 gradually decreases, and no large load fluctuation occurs. Therefore, in this paper feeding device, the rotation of the drive system is stabilized, and the conveyance speed of the paper 15 is stabilized. Therefore, even when the rear end of the paper 15 slips out from between the feeding roller 25 and the pad body 26, the transferred image will not be misaligned.

The paper 15 that has been transferred by the transfer device 13 is conveyed to a fixing device (not shown), where the image is fixed.
It is ejected outside the copier.

[Other Examples]

(a) In the above embodiment, by changing the strength of the spring 34, Fj! Although the I force was adjusted, it can also be adjusted by changing the fulcrum position of the arm 32.

(b) Instead of the friction pad 24 shown in FIG. 2, the configuration shown in FIG. 3 may be adopted.

In FIG. 3, the friction pad 24 has a regular pressure plate 41 that curves along the paper feed roller 25. As shown in FIG. Pressure +
Three types of pad main bodies 42 are attached to the surface of the ff 141 on the paper feed roller 25 side, and the coefficients of friction are set to decrease in order from the upstream side in the paper conveyance direction. The three types of pad bodies 42 are each made of different materials such as rubber and cork. Moreover, by changing the mixing ratio of two or more types of materials, three types of pad bodies 42 having different coefficients of friction can be obtained. Moreover, the types of pad bodies 42 are not limited to three types, and may be two types or four or more types.

The downstream end of the pressure plate 41 in the paper conveyance direction is connected to the paper feed roller 2.
It is rotatably supported by a pair of brackets 43 via a pin parallel to the center of rotation of 5.

The bracket 43 is a member fixed to the main body of the copying machine. On the other hand, the upstream end of the pressure plate 41 in the paper conveyance direction is always elastically pressed toward the paper feed roller 25 by a spring 44 .

With the configuration shown in FIG. 3 as well, it is possible to make the frictional force in the downstream part of the friction pad 24 smaller than in the upstream part, and it is possible to obtain the same effect as in the embodiment described above.

(C) In the embodiment described above, a configuration was adopted in which a plurality of types of pad main bodies 42 having different coefficients of friction were combined to reduce the frictional force in the downstream portion of the friction pad 24 than in the upstream portion. However, the present invention is not limited to this. Instead, it is also possible to adopt a configuration in which the frictional force is continuously changed by gradually changing the mixing ratio of two or more types of materials having different coefficients of friction, for example. Examples of materials to be mixed include:
Examples include rubber and cork, rubber and felt, etc.

〔Effect of the invention〕

According to the roller type paper feeding device according to the present invention, the frictional force of the friction surface of the friction pad is set to be smaller on the downstream side than on the upstream side in the paper conveyance direction, so that the trailing edge of the paper does not touch the belt. This eliminates the possibility of causing large load fluctuations when coming out from between the pad and the pad. Therefore, in the paper feeding position 'A' according to the present invention, the rotation of the drive system is stabilized, and the conveyance speed of the paper is stabilized.

[Brief explanation of the drawing]

FIG. 1 is a schematic front partial view of a copying machine that employs an embodiment of the paper feeder according to the present invention, FIG. 2 is a perspective view of an embodiment of the paper feeder according to the present invention, and FIG. FIG. 2 is a diagram corresponding to FIG. 2 of the embodiment. 13... Transfer device, 14... Paper feed cassette, 15.
... Paper, 22 ... Paper feed device, 24 ... Friction pad, 25 ... Paper feed roller.

Claims (1)

[Scope of Claims] A paper feeding device for feeding sheets of paper one by one from a paper storage section storing a large number of sheets to a paper feeding section, comprising: a rotatable device disposed near an exit of the paper storage section; a paper feed roller; and a friction pad having a friction surface that extends along the outer peripheral surface of the paper feed roller and comes into elastic pressure contact with the roller, the friction surface being located downstream of the upstream portion in the paper conveyance direction. A roller-type paper feeder with small frictional force on the sides.