JPH10139195A - Sheet feeder, image forming device and image reading device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the durability of a nip part by composing a separation pad of an abrasion member contacting a rotation feeding means and forming the nip part and an elastic member arranged at a position opposite to the means through the abrasion means interposed therebetween, and forming the abrasion member of material formed of a basic material added with particles. SOLUTION: A sheet feeding device 10 is provided with a feed roller 11, a lifter 9 being an elevation member, and a separation pad 1, as its main parts. The separation pad 1 is composed of a mount 2 generated from a moldable material such as resin, a sponge member 3 made of such as foaming urethane or foaming rubber having independent or continous air bubbles, an abrasion sheet 7 made of such as urethane rubber having a mirror-like surface and pigment added thereto, and an inlet sheet 5 made of low u material such as Teflon tape. The separation pad 1 is energized to the side of feed roller 11 by a pressing means 4 such as coil spring and thus a nip part is formed between the roller 11 and the means 4 to ensure the separation of sheets.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a laser beam printer, an ink jet printer, a facsimile, and a sheet feeding apparatus in an image reading apparatus, and more particularly to such a sheet feeding apparatus. The present invention relates to a separation pad used for the above.

[0002]

2. Description of the Related Art As a conventional sheet feeding apparatus of this type,
FIG. 7 is a sectional view of a separation pad type sheet feeding apparatus used in an image forming apparatus such as a copying machine.

This sheet feeding apparatus includes a feeding roller 1011 rotatable in the direction of arrow R, an elevating member 1009 capable of moving up and down in the directions of arrows F1 and F2, and a sheet feeding surface on the surface of the feeding roller 1011. Separation pad 1001 forming separation nip N '(rubber 100
3 is affixed).

Prior to the feeding of the sheet material, first, a sheet bundle S composed of a plurality of stacked sheets is fed to a sheet feeding tray 10.
13, and the leading end thereof is inserted between the feeding surface of the feeding roller 1011 and the elevating member 1009. By raising the elevating member 1009 in the F1 direction, the sheet bundle S is nipped between the inserted leading end and the feeding roller 1011 and the feeding roller 1011 is rotated in the direction of arrow R. Thereby, based on the frictional force acting between the feeding roller 1011 and the sheet bundle S, the uppermost sheet S1 is moved to the arrow K1.
In addition to feeding in the direction, the sheet is passed through the separation nip portion N ′ to prevent double feeding. Sheet S after separation and feeding
When the leading end of the roller 1 reaches a pair of conveying rollers (not shown), a conveying force is applied by the pair of conveying rollers. At this time, if the elevating member 1009 is at the pressing position, the conveyance of the sheet S1 by the conveyance roller pair is hindered.
The elevating member 1009 is moved down to the retreat position below in the arrow F2 direction.

[0005] The sheet feeding apparatus having the above-described structure is configured to perform good separation and feeding by utilizing a delicate difference in frictional force between the feeding roller 1011, the friction pad 1001, and the sheet material. Have been.

[0006]

However, in the above-mentioned conventional example, since the hardness of the separation pad is high, the feeding roller 1 is hardened.
Since the nip N ′ formed between 011 and the separation pad 1001 is narrow in the sheet feeding direction (the direction of the arrow R), in other words, the area of the nip is small. And the effect of preventing double feed is apt to decrease.

[0007] Further, even if the nip area is simply increased by forming a roller with a soft material or the like, these are generally not durable and have a high surface friction coefficient. Sufficient quality could not be obtained for the feeding device.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a separation pad which improves the durability of a nip portion and has an excellent double feed prevention effect and excellent durability. An object of the present invention is to provide a sheet feeding apparatus using the same, an image forming apparatus and an image reading apparatus using the same.

[0009]

According to the present invention, in order to achieve the above object, there is provided a rotary feeding means, and a separation pad which is pressed against the rotary feeding means. In a sheet feeding apparatus for sequentially separating and feeding sheets one by one from a sheet bundle by passing the sheet between the sheet feeding means and the separation pad, the separation pad contacts the rotary feeding means to form a nip. A friction member having flexibility higher than the friction member, and an elastic member disposed at a position facing the rotary feeding means with the friction member interposed therebetween;
Wherein the friction member is configured by adding particles to a base material, and the frictional force with the rotary feeding means is adjusted by the amount of the particles added.

This makes it possible to widen the contact surface between the separation pad and the rotary feed (hereinafter, such a contact surface is referred to as a wide area nip), and in that case, the frictional force becomes too large. It is easy to adjust so that there is no
It is possible to provide a sheet feeding device excellent in sustainability in which the contact area does not change due to abrasion while maintaining the double feed prevention effect.

[0011] A separation pad includes a mount for supporting the elastic member, and a hard member disposed at a position facing the rotary feeding means and downstream of the elastic member with the friction member interposed therebetween. A pressurizing means for engaging the mount to urge the elastic member toward the rotary feeding means.

Thus, the elastic member can be urged toward the rotary feeding means in a stable state, and the adjustment of the amount of deformation of the elastic member is facilitated by the hard member. Further, the sheet feeding is not hindered by being provided on the downstream side. The hard member is formed integrally with the mount.

As a result, the number of parts and the number of assembling steps are reduced, and the productivity is improved.

The friction member has a particle diameter of 0.1 to 1 in urethane rubber.
It is characterized by being formed by adding 0 μm particles.

[0015] This makes it possible to form a wide nip without contacting the rotary feeding means, and to form a smooth surface.

[0016] The particles are also preferably pigments.

Since the pigment is not soluble in water or a solvent,
Since the compounding ratio is directly reflected in the frictional force, the frictional force can be easily adjusted.

The particles are pigments, and are characterized in that the compounding ratio is 10 to 40% by weight.

As a result, a friction member having an optimum friction coefficient is formed, and a high-quality friction member having good sheet pull-out force characteristics can be provided.

It is preferred that the pigment is white.

[0021] This makes it possible to particularly prevent contamination of papers. That is, it is possible to prevent the color from being caused by the adhesion.

The surface of the friction member on the side of the rotary feeding means is a mirror surface.

As a result, the wear on the friction sheet surface can be suppressed, and the durability can be improved.

An image forming apparatus comprising: the sheet feeding device; and image forming means for forming an image on a sheet fed from the sheet feeding device.

An image reading apparatus comprising: the sheet feeding device; and reading means for reading a document sheet sent from the sheet feeding device.

[0026]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the dimensions of the components described in this embodiment,
The material, shape, relative arrangement, and the like are not intended to limit the scope of the present invention only to them unless otherwise specified. (Embodiment 1) First, an outline of an image forming apparatus provided with a sheet feeding apparatus according to the present invention will be briefly described as a first embodiment with reference to FIG. The image forming apparatus 21 includes an optical system 22 for irradiating a laser beam according to image information, a photosensitive drum 25 as an image carrier, a primary charger 26 as a corona discharger, a developing device 27, and a cleaner 28. The image forming unit 23 feeds and conveys the sheet,
And a sheet transport unit for discharging. In the image forming section 23, the photosensitive drum 25 having the photosensitive layer is uniformly charged by rotating the surface thereof while applying a voltage by the primary charger 26, and the surface of the photosensitive drum 25 is transmitted from the optical system 22 based on the image information. The light image irradiated through the exposure unit forms a latent image on the photosensitive drum 25 charged in advance by the primary charger 26 in advance, and forms an image of a developer (hereinafter, referred to as toner) by the developing unit 27. I do. On the other hand, in synchronism with the formation of the toner image, the sheet is separated and fed from the sheet bundle S on the tray 29 by the feeding roller 11 and the separation pad 1 of the sheet feeding device 10 and is conveyed by the conveying roller pair 24 and the like. 23
To reach. The toner image is transferred to the sheet conveyed to the image forming unit 23 by the transfer roller 30 to which a voltage having a polarity opposite to that of the toner image is applied. The image forming unit 23 removes the toner remaining on the photosensitive drum by the cleaner 28 to prepare for the next image formation. The sheet on which the toner image has been transferred is delivered to a fixing roller 31 having a built-in heater, where the transferred toner image is fixed. Thereafter, the sheet is conveyed to the discharge roller 32 and discharged to the tray 33. Next, a sheet feeding apparatus using the separation pad according to the present invention will be described in detail with reference to FIG.

The sheet feeding device 10 includes a feeding roller 11,
The lifting member (lifter) 9 and the separation pad 1 are configured as main members. At the time of sheet feeding, a plurality of sheets are stacked to form a sheet bundle (hereinafter, referred to as a “sheet bundle”) S, stacked on the stacking tray 13, and the uppermost sheet S1 is fed in the direction of arrow K1. I do.

At this time, the feeding roller 11 is driven and rotated in the direction of arrow E at a predetermined timing, and the elevating member 9 is moved up and down in the directions of arrows F1 and F2 at a predetermined timing (9a is a rising position, 9b is a lowering position). Further, by performing a predetermined separating and feeding operation on the sheet S1 by passing the sheet S1 between the feeding roller 11 and the separation pad 2, that is,
Only the top sheet S1 is separated from the subsequent sheets and fed.

Next, the separation pad 1 which is a feature of the present invention will be described in detail.

The separation pad 1 includes a mount 2 made of a moldable material such as a resin and a sponge 3 made of an elastic material such as urethane foam or foam rubber having independent or open cells.
A friction sheet 7 as a friction member made of urethane rubber having a thickness of 0.2 mm and having a mirror-like surface and pigment added as particles, and an inlet sheet 5 made of a low μ material such as Teflon tape. , And is urged to the feed roller 11 by a pressing means 4 made of a coil spring or the like.

The mount 2 includes a support 2a, an entrance 2b,
The recess 2c, the outlet 2d, and the outlet 2d
And a contact portion 2e, which is the top portion extending toward 1.

After the sponge 3 is inserted into the concave portion 2c of the mount 2, the friction sheet 7 covers the upper portion of the sponge 3 and the abutting portion 2e from the inlet 2b of the mount 2, and the upper portion of the separating portion 1d has the outlet 2d. It is configured so as to cover up to the side surface.

The mount 2 is supported by its support portion 2a about the shaft 8 as the center of rotation, and is urged by the urging means 4 toward the feed roller 11.

On the other hand, the feeding roller 11 is fixed in position, driven by a driving means (not shown), and rotates in the direction E. The roller 12 and the transport roller pairs 14a and 14b transport the separated sheet.

Next, the wide area nip, which is a feature of the present invention, formed between the feed roller 11 and the separation pad 1 will be described.

When the separation pad 1 is pressed in the direction of the feed roller 11, an N nip width is formed in the sheet conveying direction as shown in FIG. Nip N is a member for supporting the friction sheet 1 has a first area N _s composed of soft sponge 3, the second region N _h composed of abutting portions 2e For a hard mount 2 2 Consists of two areas.

When the separation pad 1 is urged by the urging means 4, the soft sponge portion first comes into contact with the roller, and is elastically deformed according to the shape of the feeding roller 11. Thereafter, the abutting portion 2e of the mount abuts on the roller via the sheet S1, and the elastic deformation thereof is stopped. As a result, a wide area nip N formed by the nip N _h and N _s are formed.

During the separating operation, the uppermost sheet S1
Are sequentially separated and fed one by one in the wide area nip N.

The reason why the surface of the friction sheet 7 is formed into a mirror-like surface is that the leading end of the sheet is caught and a feeding error occurs or the leading end is caught in comparison with the case where the rubber surface is a so-called uneven surface or a knurled surface. This is because breakage does not occur.

Further, the rubber surface is delicately shaved by rubbing with the sheet, and μ of the surface of the friction sheet is reduced and the separation performance is deteriorated. Mirror surfaces are much less, and are therefore more durable.

Next, the friction performance of the separation pad 1 will be described. The friction performance of the separation pad 1 greatly affects the separation performance. In order to manage the friction performance of the separation pad 1, a strip paper 20 is sandwiched between the feeding roller 11 and the separation pad 1 as shown in FIG. 3 and pulled out in the feeding direction by a digital tension gauge (not shown). An experiment is performed to confirm that the pulling force is within a predetermined range.

Here, the feeding roller diameter is 32 mm, the roller hardness is 25 ° C., the material is E251 (Sumitomo Rubber Industries, Ltd.), the spring pressure is 350 g, the feeding speed is 82 mm / s, and the separating angle is 30.
° system, when the pull-out force value is 60 to 220 g,
It has been found to have a stable feeding capability. If the pulling force exceeds 220 g, feeding mistake and vibration will occur, and 60 g
If it is below, double feed occurs. The initial value of the pull-out force is high.
And a tendency to decrease due to adhesion of paper powder, toner and the like.

Specifically, under such conditions, optimization is performed by changing the pigment content of the friction sheet of the separation pad according to the present invention.

Here, a separation pad 1 using a urethane rubber friction sheet 7 having a thickness of 0.2 mm and a mirror-finished surface and a sponge 3 made of urethane foam having a thickness of 3 mm is used.

First, if the friction sheet 1 is made of pure urethane rubber only, the pulling force greatly exceeds 250 g, and does not conform to the above-mentioned stable feeding range. Further, it is difficult to finely adjust μ with pure urethane rubber. Therefore, in the present invention, compared to a particle-free urethane rubber having a mirror-finished surface, the rubber surface to which particles such as pigments are added,
Focusing on the fact that the friction coefficient is slightly reduced by the particles of the surface layer, a method of finely adjusting μ by adding a pigment or carbon particle having a particle size of 0.1 to 10 μm without blade generation was proposed, and an experiment was performed. Was. However, 8
A predetermined paper of 0 g / m ² was used.

According to the experiment conducted under the above conditions, when the weight ratio of the pigment to the friction sheet is less than 10%, the effect of adding the pigment is weak, and the pulling force becomes higher than the stable feeding range. I will.

Conversely, if it exceeds 50%, the pigment will outperform the properties of the rubber, and the predetermined withdrawal force properties cannot be obtained.

In the end, when 10% to 40%, that is, when the friction sheet 1 is used by mixing and molding the urethane rubber 10 at a weight ratio of the pigment 3 and forming the mirror surface, the pulling force is Is initially 2 as shown in FIG.
It calms down around 00g, and it becomes around 100g even after durability,
It was found that the system could maintain stable feeding ability. However, in FIG. 4, the graphs are, in order from the top, H / H: high temperature and high humidity (30 ° C./80%), J / J: normal temperature and normal humidity (20 to 25 ° C./30 to 60%), N / L: Results under normal temperature and low humidity (23 ° C / 5%). The meanings of the symbols on the graph in the present embodiment are described below. A: Poor paper feed and squealing area B: Double feed generating area a: 0 sheets b: 10000 sheets c: 50,000 sheets d: 100000 sheets i: 100 g j: 200 g Further, the diameter, hardness, material and feeding of the feeding roller When the system such as the speed is changed, the pulling force corresponding to the stable feeding ability naturally changes.
It is possible to cope by adjusting it between ４０40%.

Further, if a pigment having no bleed component is used, a trouble of a decrease in μ due to blooming can be prevented until the end of the life of the main body of the feeding apparatus, and a long-term stable feeding ability can be maintained. In addition, using a white pigment has an effect of preventing contamination of paper sheets.

The thickness of the friction sheet 1 is 0.1 to 0.5.
At 5 mm, the pressure and the sponge portion are balanced as described above, and a wide area nip N is formed between the feed roller 11 and the friction sheet 1. The wide area nip reduces the nip pressure, and thus greatly contributes to improvement of durability, prevention of sheet double feeding, and prevention of vibration.

However, the thickness of the friction sheet 1 is 0.5 m
If it exceeds m, the friction sheet itself becomes hard, the balance with the sponge layer is lost, and the nip area is reduced. When the thickness is less than 0.1 mm, the friction sheet has no strength and is difficult to manufacture.

In addition, as shown in FIG. 5, as a sheet feeding apparatus having a wide area nip, it is conceivable that the shape of the friction member 42 is adjusted to the outer diameter of the feeding roller 41 to secure a wide area nip. There is a disadvantage that the sheet processing cost is expensive and that alignment with the feeding roller is difficult and that there is a high possibility of one-sided contact, that is, a wide area nip does not result.

Although a sheet feeding device having a pad formed of a highly flexible material, for example, a foamed elastic material, can secure a wide area nip, it has disadvantages such as an increase in sheet front-end jams against bubbles and abrasion resistance. There are disadvantages such as non-uniformity and disadvantage.

(Embodiment 2) As a second embodiment of the present invention, an image reading apparatus provided with a sheet feeding apparatus according to the present invention will be described with reference to FIG.

The image reading device 100 is a platen glass 10
A reading unit 101 that reads an image of a document placed on the document 1a
And a document feeder 200 for feeding a document to the platen glass 101a. The document feeder 200 includes a sheet feeding device 10 according to the present application, a conveying roller 202 for conveying a sheet after feeding, a drive and a driven Conveyor belt 203 moved in the direction of arrow K2 by each roller of tension
And a document tray 70.

The original S1 as a sheet separated and fed by the sheet feeding device 10 according to the present invention
02 is transported toward the platen glass 101a by the transport belt 203, and the platen glass 101a is transported by the transport belt 203.
It is arranged at a predetermined position above. Here, after the image is read, the sheet is transported again by the transport belt 203 and discharged onto the document tray 70.

When the image forming apparatus is formed integrally with the image forming apparatus as in the present embodiment, the image read by the reading unit 101 is emitted from the exposure unit 102 as a beam. Then, corresponding to the beam, the charger 103
a, a developing device 103b, etc., to form a toner image on the photosensitive drum 103d, transfer the image to a sheet by a transfer device 103c, convey the image to a fixing device 105 by a conveyance device, fix the image on the sheet, and discharge the image. .

(Other Embodiments) In the above embodiment, pigments having no bleed component were used as particles.
Other than pigments, the particle size is about 0.1 to 10 μm,
Any material can be used as long as it satisfies compatibility with rubber, stability as a mixture, and resistance to vulcanization (temperature).

[0059]

According to the present invention, in order to achieve the above object, the separation pad is provided with a friction member which contacts the rotary feeding means to form a nip, and has a higher flexibility than the friction member. An elastic member disposed at a position opposed to the rotary feeding means, and the friction member is configured by adding particles to a base material, and the rotary feeding means is formed by adding the particles. By adjusting the frictional force of the sheet feeding device, it is possible to provide a sheet feeding device excellent in sustainability, in which the contact area does not change due to abrasion while maintaining the effect of preventing double feeding.

The separation pad includes a mount for supporting the elastic member, and a hard member disposed at a position facing the rotary feeding means with the friction member interposed therebetween and disposed downstream of the elastic member. Since the pressurizing means for engaging and urging the elastic member toward the rotation feeding means is provided, the elastic member can be urged to the rotation feeding means in a stable state, and the hard member This facilitates adjustment of the amount of deformation of the elastic member. Further, the sheet feeding is not hindered by being provided on the downstream side.

Since the hard member is formed integrally with the mount, the number of parts and the number of assembling steps are reduced, and the productivity is improved.

When the friction member has a particle size of 0.1 to 1
Since it is molded by adding particles of 0 μm, it has elasticity enough to form a wide area nip without contacting with the rotary feeding means, and the surface can be formed into a smooth surface. The frictional force with the feeding means can be finely adjusted.

When the particles are pigments, they do not dissolve in water or a solvent, and the blending ratio is directly reflected in the frictional force, so that the frictional force can be easily adjusted.

When the particles are pigments, and the compounding ratio is 10 to 40% by weight, a friction member having an optimum friction coefficient is formed, and a high-quality friction member having good sheet pull-out force characteristics is obtained. Can be provided.

When the pigment is white, it is possible to particularly prevent contamination of papers. That is, it is possible to prevent the color from being caused by the adhesion.

Since the surface of the friction sheet on the side of the rotary feeding means is a mirror surface, abrasion of the friction sheet surface can be suppressed and durability can be improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a schematic configuration of a sheet feeding device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a schematic configuration of the image forming apparatus according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating a schematic configuration of a separation pad optimization experiment apparatus of the sheet feeding apparatus according to the first embodiment of the present invention.

FIG. 4 is a waveform diagram showing a relationship between a pulling-out force and the number of endurable sheets in the sheet feeding apparatus according to the first embodiment of the present invention.

FIG. 5 is a cross-sectional view illustrating a schematic configuration of a sheet feeding apparatus in a case where a separation member is formed in accordance with a feeding roller.

FIG. 6 is a cross-sectional view illustrating a schematic configuration of an image reading device according to a second embodiment of the present invention.

FIG. 7 is a sectional view showing a schematic configuration of a conventional feeding device.

[Explanation of symbols]

 1,1001 ... Separation pad 2,1002 ... Mount 3,1003 ... Elastic member 4 ... Pressurizing means 5 ... Inlet sheet 7 ... Friction sheet 8 ... Shaft 9,1009 ... Elevating member 10 ... Sheet feeding device 11,41,1011 ... Feeding roller 12 ... Roller 13,1013 ... Loading tray 14 ... Transport roller pair 21 ... Image formation Device 22 Optical system 23 Image forming unit 24 Conveying roller pair 25 Photoconductor drum 26 Primary charging device 27 Developing device 28 Cleaner 29 Tray 30 ... Transfer roller 31 ... Fixing roller 32 ... Ejection roller 33 ... Tray 42 ... Friction member 70 ... Document tray 100 ... Image reading device 101 ... Reading unit 101a ... Platens Lath 102 Exposure unit 103 Image forming unit 103a Charging device 103b Developing device 103c Transfer device 103d Photosensitive drum 105 Fixing device 200 Automatic document Feeding device 203: transport belt S: sheet bundle S1: sheet, document

Claims (10)

[Claims] 1. A rotary feeder for feeding a sheet, and a separation pad pressed against the rotary feeder, wherein the sheet is passed between the rotary feeder and the separation pad. In the sheet feeding apparatus that separates and feeds the sheets one by one, the separation pad includes a friction member that contacts the rotary feeding unit to form a nip; An elastic member disposed at a position opposed to the rotation feeding means with a member interposed therebetween, wherein the friction member is configured by adding particles to a base material, and the rotation feeding is performed according to the amount of the particles added. A sheet feeding device for adjusting a frictional force with feeding means. 2. A separation pad, comprising: a mount for supporting the elastic member; and a position opposed to the rotary feeding means with the friction member interposed therebetween, the downstream of the elastic member in the feeding direction. 2. A sheet feeding device according to claim 1, further comprising: a pressure member that engages with the mount and urges the elastic member toward the rotation feeding device. apparatus. 3. The sheet feeding device according to claim 2, wherein said hard member is formed integrally with said mount. 4. The urethane rubber has a particle diameter of 0.1.
4. The sheet feeding apparatus according to claim 1, wherein the sheet feeding apparatus is formed by adding particles of 10 to 10 [mu] m. 5. A sheet feeding apparatus according to claim 1, wherein said particles are pigments. 6. A sheet feeding apparatus according to claim 4, wherein said particles are pigments, and the compounding ratio thereof is 10 to 40% by weight. 7. The sheet feeding device according to claim 5, wherein the pigment is white. 8. The sheet feeding device according to claim 1, wherein a surface of the friction member on the side of the rotary feeding means is a mirror surface. 9. A sheet feeding device according to claim 1, further comprising: an image forming means for forming an image on a sheet fed from the sheet feeding device. Image forming apparatus. 10. A sheet feeding apparatus according to claim 1, further comprising: reading means for reading an image of a document sheet sent from said sheet feeding apparatus. Image reading device.