CN111867949A

CN111867949A - Paper feeding roller

Info

Publication number: CN111867949A
Application number: CN201980018523.XA
Authority: CN
Inventors: 山口和志
Original assignee: Sumitomo Riko Co Ltd
Current assignee: Sumitomo Riko Co Ltd
Priority date: 2018-04-27
Filing date: 2019-04-15
Publication date: 2020-10-30
Anticipated expiration: 2039-04-15
Also published as: CN111867949B; JP6956678B2; WO2019208296A1; JP2019189420A; US20200399084A1

Abstract

The invention provides a paper feed roller which can restrain the poor paper transportation for a long time. The paper feed roller 10 comprises a shaft body 12 and an elastic body layer 14 formed on the periphery of the shaft body 12, wherein a plurality of convex parts 16 forming surface unevenness are arranged on the periphery surface of the elastic body layer 14, and the contact area of the whole part contacting with the glass surface when the glass plate is pressed on the periphery surface of the paper feed roller 10 by a load of 0.5-2.3N per 1cm of axial length is 1.0-15% of the nip area of the glass surface.

Description

Paper feeding roller

Technical Field

The present invention relates to a paper feed roller suitable for use in electrophotographic apparatuses such as copiers, printers, and facsimile machines that employ an electrophotographic system.

Background

The paper feed roller is formed in a cylindrical shape from an elastic material such as a crosslinked rubber, and the peripheral surface thereof is a contact surface with the paper. Paper dust generated from paper may adhere to the peripheral surface of the paper feed roller. Further, paper dust may accumulate on the circumferential surface of the paper feed roller during repeated contact with the paper. When paper dust accumulates, the contact area of the peripheral surface with respect to the paper decreases, and the friction coefficient of the contact surface with respect to the paper decreases. As a result, a conveyance failure of the paper may occur.

In order to suppress a paper conveyance failure, a paper feed roller having a concave-convex portion formed on the circumferential surface thereof is known (patent document 1). For example, patent document 1 discloses a paper feed roller in which a plurality of ridges and grooves are formed parallel to the axial direction of the paper feed roller.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2017-65907

Disclosure of Invention

Problems to be solved by the invention

The conventional paper feed roller is not sufficient in maintaining a good friction coefficient for a long period of time from the initial stage of use. In particular, among the paper sheets used in recent years, there are low-quality paper sheets, and paper dust is likely to be generated in the low-quality paper sheets, and a paper sheet conveyance failure is likely to be generated in an early stage.

The invention provides a paper feed roller which can restrain poor paper feeding for a long time.

Means for solving the problems

In order to solve the above problems, a paper feed roller according to the present invention is a paper feed roller for an electrophotographic apparatus including a shaft body and an elastic layer formed on an outer periphery of the shaft body, wherein a plurality of convex portions forming surface irregularities are provided on a peripheral surface of the elastic layer, and a contact area of a whole portion contacting a glass surface when a glass plate is pressed against the peripheral surface of the paper feed roller with a load of 0.5 to 2.3N per 1cm axial length is 1.0 to 15% of a nip area of the glass surface.

In the paper feed roller according to the present invention, a ratio of a contact area of each convex portion in the entire portion in contact with the glass surface is preferably 0.02 to 10%. Preferably, the plurality of projections are regularly arranged on the circumferential surface of the elastomer layer. The plurality of projections may be formed of two kinds of projections having different heights. In this case, it is preferable that the height of the lower convex portion of the two kinds of convex portions having different heights is 70 to 80% of the height of the higher convex portion.

Effects of the invention

According to the paper feed roller of the present invention, the contact area of the entire portion in contact with the glass surface when the glass plate is pressed against the peripheral surface of the paper feed roller with a load of 0.5 to 2.3N per 1cm of axial length is 1.0 to 15% of the nip area with the glass surface, and by reducing the contact area with the glass surface, the contact area with the paper when the paper is conveyed is reduced, so that the generation amount of paper dust due to cutting of the paper can be suppressed. Further, by reducing the contact area with the paper, paper dust generated when the paper is conveyed moves from the convex portion to the concave portion on the roller surface immediately, and a decrease in the friction coefficient due to the paper dust staying and adhering to the contact portion with the paper can be suppressed. This can suppress a paper conveyance failure for a long period of time.

Further, if the ratio of the contact area per convex portion in the entire portion in contact with the glass surface is 0.02 to 10%, the contact area per convex portion with the paper when the paper is conveyed is also small, and therefore the amount of paper dust generated by cutting the paper and the reduction in the friction coefficient can be further suppressed. Further, when the plurality of convex portions are regularly arranged on the peripheral surface of the elastic body layer, a groove of the concave portion is formed continuously in the arrangement direction, and the groove serves as a discharge path of paper dust generated when the paper is conveyed and easily discharges the paper dust to the outside of the roller. Further, if the plurality of convex portions are formed of two kinds of convex portions having different heights, the load (load) of the entire roller is received mainly by the high convex portions, and therefore the load (load) for the low convex portions can be reduced, and the contact area with the paper sheet of the entire roller can be easily reduced. Further, the low convex portion contributes to the conveyance of the sheet even if the contact load is small, and therefore, the conveyance force of the sheet is easily secured, and the conveyance failure of the sheet is suppressed.

Drawings

Fig. 1 is an external view schematically showing a paper feed roller according to an embodiment of the present invention.

Fig. 2 shows an example of the shape of a plurality of projections provided on the circumferential surface of the elastic layer of the paper feed roller.

Fig. 3 shows an example of arrangement of a plurality of convex portions provided on the circumferential surface of the elastic layer of the paper feed roller.

Fig. 4 is a diagram showing a method of determining an area ratio of an actual contact portion when a glass plate is pressed against the peripheral surface of a paper feed roller.

FIG. 5 is a photograph showing the nip portion when the glass plate is pressed against the peripheral surface of the paper feed roller in example 1.

Detailed Description

The paper feed roller according to the present invention (hereinafter, may be simply referred to as a paper feed roller) will be described in detail. Fig. 1 is an external view schematically showing a paper feed roller according to an embodiment of the present invention.

The paper feed roller 10 according to one embodiment of the present invention includes a shaft 12 and an elastic body layer 14 formed on the outer periphery of the shaft 12. The elastic body layer 14 becomes a layer (outermost layer) appearing on the surface of the paper feed roller 10. The elastomer layer 14 is tubular (cylindrical). A plurality of protrusions 16 having surface irregularities are provided on the circumferential surface of the elastomer layer 14. Between the convex portions 16, concave portions lower than the convex portions 16 are formed, and the convex portions 16 provide concave and convex portions on the circumferential surface of the elastomer layer 14.

In order to reduce the contact area with the paper sheet when the paper sheet is conveyed in the paper feed roller 10, the contact area (total area of actual contact portions) of the entire portion that contacts the glass surface when the glass sheet is pressed against the circumferential surface of the paper feed roller 10 (here, the circumferential surface of the elastic body layer 14) with a load of 0.5 to 2.3N per 1cm of axial length is 1.0 to 15% of the nip area with the glass surface. The nip area is the area of the entire nip portion, which is a region recessed when the glass sheet is pressed against the circumferential surface of the sheet feed roller 10, and the contact area is the area of the entire portion of the nip portion that actually contacts the glass surface. By reducing the contact area with the glass surface, the contact area with the paper when the paper is conveyed is reduced, and therefore the amount of paper dust generated by cutting the paper can be suppressed. Further, since the contact area with the paper is small, paper dust generated when the paper is conveyed moves from the convex portion to the concave portion on the roller surface immediately, and a decrease in friction coefficient due to the paper dust staying and adhering to the contact portion with the paper can be suppressed. This can suppress a paper conveyance failure for a long period of time. The contact area is more preferably within a range of 3.0 to 12% of the nip area, and still more preferably within a range of 5.0 to 12% of the nip area.

The ratio of the contact area (the total area of the actual contact portions) can be determined by observing a predetermined range of the nip portion when the glass plate is pressed against the peripheral surface of the paper feed roller 10 with a predetermined load using a microscope. The ratio of the contact area (the total area of the actual contact portions) can be adjusted by the shape of the convex portions, the density of the convex portions, the elasticity (material) of the convex portions, and the like.

In the sheet feeding roller 10, the ratio of the contact area of each convex portion in the whole of the portion in contact with the glass surface is preferably small. Since the contact area with the paper sheet is reduced for each convex portion when the paper sheet is conveyed, the amount of paper dust generated by cutting the paper sheet and the reduction in the friction coefficient can be further suppressed. From this viewpoint, the ratio of the contact area per convex portion is preferably 0.02 to 10%. More preferably 0.1 to 5%. The ratio of the contact area of each convex portion (the area of the actual contact portion) can be determined by observing a predetermined range of the nip portion where the glass plate is pressed against the peripheral surface of the paper feed roller 10 with a predetermined load by a microscope.

The plurality of projections 16 may be formed of projections having the same height, or may be formed of projections having different heights. When the plurality of convex portions 16 are formed of two kinds of convex portions having different heights, the load (load) of the entire roller is mainly received by the high convex portions, and therefore the load (load) for the low convex portions can be reduced, and the contact area with the paper sheet of the entire roller can be easily reduced. Further, the low convex portion contributes to the conveyance of the sheet even if the contact load is small, and therefore, the conveyance force of the sheet is easily secured, and the conveyance failure of the sheet is suppressed. In this case, the height of the lower one of the two kinds of projections having different heights may be 70 to 80% of the height of the upper one.

The height of the projection 16 is not particularly limited, but is preferably in the range of 0.02 to 0.40 mm. If the height of the projection 16 is 0.02mm or more, the volume of the recess between the projection 16 and the projection 16 becomes large, and the generated paper dust is less likely to clog the recess. From this viewpoint, the height of the projection 16 is more preferably 0.05mm or more. When the height of the convex portion 16 is 0.40mm or less, the diameter of the lower bottom of the convex portion 16 is appropriately suppressed to be small, and therefore, the dispersibility of the convex portion 16 is improved, and the effect of pressure dispersion with respect to the paper is improved. This makes it easy to suppress the generation of paper dust. From this viewpoint, the height of the convex portion 16 is more preferably 0.30mm or less.

In fig. 1, the convex portion 16 is a hemispherical convex portion. The spherical shape means a substantially spherical shape, and may be a shape close to a spherical shape having a curved surface. The spherical shape includes a regular spherical shape and an elliptical spherical shape. The hemispherical shape also includes a hemispherical shape of a half of a ball cut by a face passing through the center of the ball, a hemispherical shape of a shape larger than the half of the ball cut by a face not passing through the center of the ball, and a hemispherical shape of a shape smaller than the half of the ball.

In fig. 1, the plurality of projections 16 are uniformly distributed and arranged on the circumferential surface of the elastomer layer 14. The plurality of protrusions 16 may be randomly arranged on the circumferential surface of the elastomer layer 14, or may be arranged in a row.

In fig. 1, the plurality of protrusions 16 are arranged on the circumferential surface of the elastomer layer 14 so as to be aligned in the axial direction and the circumferential direction. The rows of the convex portions 16 arranged in the circumferential direction form a continuous groove of the concave portion. Further, the rows of the convex portions 16 arranged in the axial direction also form continuous grooves of the concave portions. Since the grooves of the concave portion that are continuous in the circumferential direction are formed in the rotation direction of the paper feed roller 10, paper dust that moves from the convex portion 16 into the grooves of the concave portion is easily discharged from the grooves to the outside of the roller with the rotation of the roller rather than staying in the grooves. That is, since the groove serves as a discharge path for paper dust generated during paper conveyance and easily discharges the paper dust to the outside of the roller, it is easy to suppress a decrease in the friction coefficient due to accumulation of the paper dust.

The shape of the plurality of convex portions provided on the circumferential surface of the elastomer layer 14 is not limited to the hemispherical convex portion 16 shown in fig. 1, and may be convex portions of various shapes. Examples of the shape of the convex portion include an irregular shape, a cylinder, a cone, a table, and a wedge. Examples of the columnar body include a cylindrical body, an elliptical body, a prismatic body (e.g., a quadrangular prism or a pentagonal prism), a fan-shaped columnar body, a D-shaped columnar body, and a gear-shaped columnar body. The head of the cylinder may be a truncated cylinder (truncated cylinder, truncated prism, etc.) having a shape such as an inclined surface or a curved surface. Examples of the cone include a cone, an elliptical cone, and a pyramid (e.g., a quadrangular pyramid and a pentagonal pyramid). The head of the cone may be a truncated cone (truncated cone, truncated pyramid, etc.) having a shape such as a flat surface (frustum), an inclined surface, or a curved surface. The table is a solid in the shape of a sphere cut by two parallel planes. When the spherical surface intersects with two parallel planes, the part of the spherical surface clamped by the two planes is a spherical belt, and a solid surrounded by the spherical belt and the two planes is a table. One of the two planes of the table may be a plane passing through the center of the ball, or both of the two planes of the table may be planes not passing through the center of the ball. The two flat surfaces of the table may be any surfaces close to a flat surface, and may be curved surfaces having a radius of curvature larger than that of the ball belt, for example. In addition, each upper base (upper side plane) of the cylinder, the elliptic cylinder, the prism, the fan-shaped cylinder, the D-shaped cylinder, the gear-shaped cylinder, the frustum and the spherical table may be a grinding surface. The abrasive surface may be formed by abrading each upper sole.

Fig. 2 shows an example of the shape of a plurality of projections provided on the circumferential surface of the elastomer layer 14. Fig. 2 (a) shows a convex portion 161 having a conical head portion cut out by a plane parallel to the bottom surface (truncated cone shape). Fig. 2 (b) shows the hemispherical convex portion 16 shown in fig. 1. In fig. 2, (c) shows a cylindrical projection 162. In fig. 2, (d) shows a quadrangular prism-shaped projection 163. Fig. 2 (e) shows a projection 164 having a shape (truncated quadrangular pyramid shape) in which the head of a quadrangular pyramid is cut out by a plane parallel to the bottom surface.

The plurality of protrusions provided on the circumferential surface of the elastomer layer 14 may be constituted by only one of the above-described various protrusions, or may be constituted by combining two or more kinds thereof. For example, the circumferential surface of the elastic layer 14 of one paper feed roller 10 may include hemispherical convex portions 16 and truncated cone-shaped convex portions 161.

The plurality of protrusions provided on the circumferential surface of the elastomer layer 14 may be arranged in an arrangement other than the arrangement shown in fig. 1. Fig. 3 shows another arrangement of a plurality of projections.

In the paper feed roller 20 shown in fig. 3 (a), a plurality of convex portions 16 are arranged in a zigzag pattern on the peripheral surface of the elastic layer 14. Specifically, the convex portions 16 in the second row are arranged between the convex portions 16 and the convex portions 16 in the first row, the convex portions 16 in the third row are arranged between the convex portions 16 and the convex portions 16 in the second row, the convex portions 16 in the fourth row are arranged between the convex portions 16 and the convex portions 16 in the third row, and the convex portions 16 are arranged so as to be shifted from each other. In the paper feed roller 20 of fig. 3 (a), the plurality of convex portions 16 are particularly uniformly arranged on the circumferential surface of the elastic body layer 14. Therefore, the contact with the sheet becomes particularly uniform when the sheet is conveyed.

In the paper feed roller 30 shown in fig. 3 (b), the convex portions 16 are arranged in a direction (direction of an arrow) at a predetermined angle of less than 45 ° with respect to the axial direction (a direction inclined toward the axial direction) on the peripheral surface of the elastic layer 14. The paper feed roller 30 shown in fig. 3 (b) has a configuration in which a plurality of rows of the convex portions 16 are arranged in a direction of a predetermined angle. In the paper feed roller 30 shown in fig. 3 (b), since the grooves of the concave portions between the rows of the convex portions 16 are formed in the direction of a predetermined angle smaller than 45 ° with respect to the axial direction (the direction inclined closer to the axial direction), paper dust generated when a sheet is conveyed easily moves from the convex portions 16 on the roller surface to the grooves of the concave portions, the paper dust is less likely to stay and be fixed to a portion in contact with the sheet, and a decrease in the friction coefficient due to the movement is easily suppressed.

In the paper feed roller 40 of fig. 3 (c), the convex portions 16 are arranged along a predetermined angular direction (an oblique direction closer to the circumferential direction) exceeding 45 ° with respect to the axial direction on the circumferential surface of the elastic body layer 14. In the paper feed roller 40 of fig. 3 (c), a plurality of rows of the convex portions 16 that are wound in a direction of a predetermined angle are arranged on the circumferential surface of the elastic body layer 14 (not in a spiral shape). In the paper feed roller 40 of fig. 3 (c), since the grooves of the concave portions between the rows of the convex portions 16 are formed in the direction (the inclined direction closer to the circumferential direction) exceeding a predetermined angle of 45 ° with respect to the axial direction, the paper dust moving from the convex portions 16 to the grooves of the concave portions tends to be discharged from the grooves to the outside of the roller without staying in the grooves as the roller rotates, like the grooves of the concave portions continuing in the circumferential direction of fig. 1. That is, since the groove serves as a discharge path for paper dust generated during paper conveyance and easily discharges the paper dust to the outside of the roller, it is easy to suppress a decrease in the friction coefficient due to accumulation of the paper dust.

In the paper feed roller 50 shown in fig. 3 (d), the convex portions 16 are arranged on the circumferential surface of the elastic layer 14 in a direction (inclined direction toward the circumferential direction) at a predetermined angle exceeding 45 ° with respect to the axial direction. In the paper feed roller 50 shown in fig. 3 (d), the convex portions 16 are spirally arranged in a direction of a predetermined angle on the peripheral surface of the elastic body layer 14. In the paper feed roller 50 of fig. 3 (d), the convex portions 16 are arranged on the side opposite to the paper surface as indicated by the broken lines. Like the paper feed roller 40 of fig. 3 (c), paper dust moving from the convex portion 16 into the groove of the concave portion is easily discharged from the groove to the outside of the roller with the rotation of the roller rather than staying in the groove.

Next, a material structure of the paper feed roller according to the present invention will be described.

As the shaft body 12, a metal mandrel composed of a solid body made of metal, a metal cylindrical body having a hollow interior, or the like is used. Examples of the material include stainless steel, aluminum, and a material obtained by plating iron. Further, an adhesive, a primer, or the like may be applied to the shaft body 12 as necessary, or the adhesive, the primer, or the like may be electrically conductive as necessary.

The elastomer layer 14 is formed of an elastic material such as a crosslinked rubber. The material is not particularly limited as long as it is a rubber-like elastic material. For example, a known rubber material such as urethane rubber, chlorohydrin rubber, and silicone rubber can be used.

The elastomer layer 14 preferably has electrical conductivity or electrical conductivity. Specifically, the volume resistivity of the elastomer layer 14 is preferably 10²～10¹⁰Ω·cm、10³～10⁹Ω·cm、10⁴～10⁸Range of Ω · cm. When the elastic layer 14 has conductivity or semiconductivity, the residual charge on the surface of the elastic layer 14 is easily reduced, and the adhesion of paper powder is easily suppressed.

The elastomer layer 14 may contain a conductive agent from the viewpoint of lowering the resistance. Examples of the conductive agent include an electron conductive agent and an ion conductive agent. Examples of the electron conductive agent include carbon black, graphite, and c-TiO₂、c-ZnO、c-SnO₂(c-means conductivity), and the like. Examples of the ion conductive agent include quaternary ammonium salts, borates, and surfactants.

The elastomer layer 14 may be added with various additives as needed. Examples of the additives include lubricants, vulcanization accelerators, antioxidants, light stabilizers, viscosity modifiers, processing aids, flame retardants, plasticizers, fillers, dispersants, defoaming agents, pigments, and mold release agents.

The thickness of the elastomer layer 14 is not particularly limited, and may be set as appropriate within a range of 0.1 to 10 mm.

The elastomer layer 14 may be formed by molding or the like based on a molding die using a rubber composition. For example, the elastic body layer 14 can be formed on the outer periphery of the shaft body 12 by disposing the shaft body 12 coaxially in the hollow portion of a roll forming mold, injecting an uncrosslinked rubber composition, heating, curing (crosslinking), and then releasing the mold. As the forming mold, a mold having a concave portion formed on its inner peripheral surface in a shape corresponding to the convex portion 16 may be used. For example, the convex portions 16 of the elastomer layer 14 can be formed by mold transfer using a molding die.

The concave portion on the inner peripheral surface of the forming die can be formed by various concave portion forming methods such as electric discharge machining, etching, shot blasting, polishing, co-precipitation plating, and a combination thereof. In the co-precipitation plating, a uniform resin particle is contained in the plating solution, the resin particle is precipitated on the inner peripheral surface of the molding die together with the plating metal, and the resin particle appearing on the plating surface is removed, whereby a concave portion can be formed on the inner peripheral surface of the molding die.

While the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the present invention.

For example, in the above embodiment, the paper feed roller 10 has a structure including the shaft body 12 and the elastic layer 14 formed on the outer periphery of the shaft body 12, and the outermost layer is the elastic layer 14, but a surface layer may be provided outside the elastic layer 14. In this case, the surface layer becomes the outermost layer, and the elastomer layer 14 is disposed inside the surface layer. The convex portions 16 may be formed on the peripheral surface of the elastomer layer 14, and the surface layer may be formed to have a thickness that ensures surface irregularities formed by the plurality of convex portions 16. Alternatively, surface modification treatment may be performed instead of forming the surface layer.

Examples

The present invention will be described in detail below with reference to examples and comparative examples.

(examples 1 to 17, comparative examples 1 to 4)

An elastomer layer (thickness: 3mm) of a urethane rubber composition was formed on the outer periphery of a core material (made of SUS304, Φ 6) using a cylindrical mold having a plurality of predetermined recesses on the inner peripheral surface. Thus, a paper feed roller having a plurality of predetermined convex portions on the peripheral surface of the elastic layer is obtained. The shape of the projections, the arrangement of the projections, and the height of the projections are shown in tables 2 to 4. The correspondence between the shape of the projections and the figure number and the correspondence between the arrangement of the projections and the figure number are shown in table 1 below. The irregular convex portion shape is formed by using a cylindrical forming die whose inner peripheral surface is subjected to electric discharge machining. In addition, a corrugated convex portion shape is formed by using a cylindrical forming die with a polished inner circumferential surface. Therefore, the arrangement of irregular-shaped convex portions is arbitrary, and the arrangement of wavy convex portions is also arbitrary.

TABLE 1

Convex part shape	Drawing number	Convex part arrangement	Drawing number
				Irregular shape	-	Is free of	-
Wave shape	-	Longitudinal and transverse	FIG. 1 shows a schematic view of a
				Conical table	In FIG. 2 (a)	Saw tooth	In FIG. 3 (a)
Hemisphere (sphere)	In FIG. 2 (b)	Oblique (axle)	In FIG. 3 (b)
				Cylinder	In FIG. 2 (c)	Oblique (week)	In FIG. 3 (c)
Prism	In FIG. 2 (d)	Screw thread	In FIG. 3 (d)
				Pyramid platform	In FIG. 2 (e)

As shown in fig. 4, the peripheral surface of the obtained paper feed roller 1 was pressed with a glass plate (50mm × 20mm × 2mm) under the load described in tables 2 to 4, and the contact portion between the paper feed roller 1 and the glass plate 2 was observed with a microscope ("laser microscope VK 9500" manufactured by KEYENCE corporation). The observation range was set to 500. mu. m.times.300. mu.m, and the area ratio of the actual contact portion in the area was calculated. Further, the ratio of the contact area of each convex portion in the entire actual contact portion is calculated. FIG. 5 is a photograph showing the nip portion when the glass plate is pressed against the peripheral surface of the paper feed roller in example 1. The darker colored portion is the actual contact portion and the lighter colored portion is the non-contact portion.

(evaluation of durability)

The paper feed roller was set in a commercially available copying machine having an FRR paper feed system, and the paper feed performance was evaluated. The paper was passed through 30 ten thousand (300K) sheets of commercially available PPC paper, and the number of occurrences of paper jams due to paper dust was measured. The case where the number of occurrences of the jam is 1 or less is described as "excellent", the case where the number of occurrences of the jam is 2 or more and 5 or less is described as "o", the case where the number of occurrences of the jam is 6 or more and 10 or less is described as "x", and the case where the number of occurrences of the jam is 11 is described as "xxx". When 11 times of paper jam occurred, the evaluation of durability was suspended.

TABLE 2

TABLE 3

TABLE 4

According to the examples and comparative examples, it is understood that a conveyance failure of paper can be suppressed for a long period of time by setting the entire contact area of the portion in contact with the glass surface when the glass plate is pressed against the peripheral surface of the paper feed roller with a load of 0.5 to 2.3N per 1cm of axial length to 1.0 to 15% of the nip area with the glass surface. In comparative example 1, the shape of the convex portion was adjusted so that the area ratio of the actual contact portion was 0.8%, but when the glass plate was pressed by a load of 0.5 to 2.3N per 1cm of the axial length, the convex portion was crushed and could not be adjusted to a range exceeding 1.0%. In comparative examples 2 to 4, the area ratio of the actual contact portion was in the range exceeding 15%, and therefore, there was a large amount of paper jam, and the conveyance failure of the paper could not be suppressed.

The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments at all, and various changes can be made without departing from the scope of the present invention.

Claims

1. A paper feed roller for an electrophotographic apparatus, comprising a shaft body and an elastic body layer formed on the outer periphery of the shaft body,

a plurality of convex parts forming surface unevenness are provided on the peripheral surface of the elastomer layer,

The contact area of the whole part contacting with the glass surface when the glass plate is pressed on the peripheral surface of the paper feeding roller by a load of 0.5-2.3N per 1cm of axial length is 1.0-15% of the nip area of the glass surface.

2. The paper feeding roller according to claim 1, wherein a ratio of a contact area of each convex portion in the entire portion in contact with the glass surface is 0.02 to 10%.

3. The paper feeding roller as claimed in claim 1 or 2, wherein the plurality of protrusions are regularly arranged on the circumferential surface of the elastic body layer.

4. The paper feeding roller according to any one of claims 1 to 3, wherein the plurality of projections are constituted by two kinds of projections having different heights.

5. The paper feeding roller as claimed in claim 4, wherein the height of the lower one of the two kinds of projections having different heights is 70 to 80% of the height of the higher one.