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Abstract

The present invention provides a paper feed roller that can suppress paper conveying defects for a long time. The paper feed roller (10) is a paper feed roller (10) having a shaft (12) and an elastic layer (14) formed on the outer periphery of the shaft (12), and is configured in the following shape: a plurality of convex portions (16) forming surface convexities are provided on the circumferential surface of the elastic layer (14), and for each of the plurality of convex portions (16), a position (X) of a portion on the front end side thereof that is closer to the front in a direction opposite to the paper feed direction is closer to the front in a direction opposite to the paper feed direction than a position (Y) of a portion on the base end side thereof that is closer to the front in a direction opposite to the paper feed direction.

Description

Technical Field

[0001] The present invention relates to a paper feed roller suitable for use in electronic photographic equipment such as a copying machine, a printer, a fax machine, etc. that adopts an electronic photographic method. Background Art

[0002] The paper feed roller is formed into a cylindrical shape by elastic materials such as cross-linked rubber, and its peripheral surface becomes the contact surface with the paper. Sometimes, paper dust generated from the paper adheres to the peripheral surface of the paper feed roller. In addition, when the paper is repeatedly in contact with the paper, sometimes paper dust accumulates on the peripheral surface of the paper feed roller. If paper dust accumulates, the contact area with the peripheral surface of the paper decreases, and the friction coefficient of the contact surface with the paper decreases. As a result, sometimes the paper is not properly transported.

[0003] In order to prevent paper conveyance failure, a technique of forming projections and depressions on the circumferential surface of a paper feed roller is known (Patent Document 1). For example, Patent Document 1 describes a technique of forming a plurality of projections and depressions parallel to the axial direction of the paper feed roller.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2017-65907 Summary of the invention

[0007] Problems to be solved by the invention

[0008] Conventional paper feed rollers are not ideal in maintaining a good friction coefficient for a long time from the initial stage of use. In particular, low-quality paper exists in the paper used in recent years, and low-quality paper is prone to paper dust, which is prone to poor paper conveyance at an early stage.

[0009] An object of the present invention is to provide a paper feed roller that can suppress paper conveyance failure over a long period of time.

[0010] Means used to solve problems

[0011] In order to solve the above-mentioned problem, the paper feed roller involved in the present invention is a paper feed roller of an electronic photographic device having a shaft body and an elastic layer formed on the outer periphery of the shaft body. The key point is that a plurality of convex portions forming surface convexities are provided on the peripheral surface of the elastic layer, and with respect to the plurality of convex portions, the position of the portion on the front end side thereof that is closer to the front in the direction opposite to the paper feed direction is closer to the front in the direction opposite to the paper feed direction than the position of the portion on the base end side thereof that is closer to the front in the direction opposite to the paper feed direction.

[0012] The plurality of protrusions preferably have a linear inclination from the base end toward the front end in the direction opposite to the paper feeding direction on the side forward in the direction opposite to the paper feeding direction. At this time, the inclination angle relative to the direction opposite to the paper feeding direction is preferably an obtuse angle. In addition, the inclination angle relative to the direction opposite to the paper feeding direction is preferably 95° to 140°. The plurality of protrusions preferably consist of an inclined column or an inclined frustum whose front end side is forward in the direction opposite to the paper feeding direction than the base end side. At this time, the area of ​​the upper base is preferably less than the area of ​​the lower base. The height of the plurality of protrusions preferably is 30 to 500 μm. The plurality of protrusions preferably are regularly arranged on the peripheral surface of the elastomer layer.

[0013] Effects of the Invention

[0014] According to the paper feed roller of the present invention, the front end side of the plurality of convex portions provided on the circumferential surface of the elastic layer is positioned forward in the direction opposite to the paper feed direction compared to the front end side of the portion positioned forward in the direction opposite to the paper feed direction, so that the convex portions contacting the paper are easily collapsed in the direction opposite to the paper feed direction during paper conveyance, and the restoring force of the collapsed convex portions is easily exerted in the paper feed direction, thereby improving the paper conveyance force. Thus, poor paper conveyance is suppressed for a long time.

[0015] Furthermore, if a plurality of convex portions have a linear inclination from the base end toward the front end in the direction opposite to the paper feeding direction on one side in the direction opposite to the paper feeding direction, the convex portion in contact with the paper is likely to fall in the direction opposite to the paper feeding direction when the paper is transported. Furthermore, if the inclination angle relative to the direction opposite to the paper feeding direction is an obtuse angle, the convex portion in contact with the paper is likely to fall in the direction opposite to the paper feeding direction when the paper is transported. Furthermore, if the inclination angle relative to the direction opposite to the paper feeding direction is 95° to 140°, the convex portion in contact with the paper is likely to fall in the direction opposite to the paper feeding direction when the paper is transported, and it is easy to increase the restoring force of the fallen convex portion.

[0016] Furthermore, if the plurality of convex portions are formed of an inclined column or an inclined frustum whose front end side is forward of the base end side in the direction opposite to the paper feeding direction, the convex portion in contact with the paper is likely to fall in the direction opposite to the paper feeding direction when the paper is conveyed. At this time, if the area of ​​the upper base is smaller than the area of ​​the lower base, it is easy to increase the restoring force of the fallen convex portion. In addition, if the height of the plurality of convex portions is 30 to 500 μm, the convex portion in contact with the paper is likely to fall in the direction opposite to the paper feeding direction when the paper is conveyed, and it is easy to increase the restoring force of the convex portion.

[0017] Moreover, if multiple protrusions are regularly arranged on the peripheral surface of the elastomer layer, a groove of a continuous concave portion is formed along the arrangement direction. The groove becomes a discharge path for paper dust generated when the paper is conveyed and easily discharges the paper dust to the outside of the roller, thereby suppressing the reduction in the friction coefficient caused by the accumulation of paper dust. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the appearance of a paper feed roller according to one embodiment of the present invention.

[0019] Figure 2 yes Figure 1 Enlarged view of part A.

[0020] Figure 3 yes Figure 2 Enlarged view of part B.

[0021] Figure 4 This is a schematic diagram for explaining the effects of the paper feed roller according to one embodiment of the present invention.

[0022] Figure 5 It is a figure which shows the example of the shape of a some convex part. Figure 5 (a) in the figure shows the shapes of styles 1 to 8. Figure 5 (b) in the figure shows the shapes of Patterns 9 to 16.

[0023] Figure 6 It is a figure which shows the arrangement form of a plurality of convex parts. Figure 6 (a) in the formula indicates Figure 1 FIG. 1 is a diagram showing an arrangement of a plurality of convex portions of a paper feed roller. Figure 6 (b) to (d) are diagrams showing other arrangement forms of the plurality of protrusions. DETAILED DESCRIPTION

[0024] The paper feed roller (hereinafter, sometimes simply referred to as the paper feed roller) according to the present invention will be described in detail. Figure 1 It is a schematic diagram of the appearance of a paper feed roller according to one embodiment of the present invention. Figure 2 yes Figure 1 Enlarged view of part A. Figure 3 yes Figure 2 Enlarged view of part B. Figure 4 Schematic diagram for explaining the effect of the paper feed roller according to one embodiment of the present invention. Figure 1 , Figure 3 , Figure 4 In the example, the rotation direction of the paper feed roller is set to the R direction, and the paper feed direction is set to the F direction. Figure 3 As shown, the radial direction of the paper feed roller is set as the x direction, the circumferential direction of the paper feed roller is set as the y direction, and the axial direction of the paper feed roller is set as the z direction.

[0025] A paper feed roller 10 according to one embodiment of the present invention includes a shaft body 12 and an elastomer layer 14 formed on the outer periphery of the shaft body 12. The elastomer layer 14 is formed as a layer (outermost layer) present on the surface of the paper feed roller 10. The elastomer layer 14 is tubular (cylindrical). A plurality of convex portions 16 forming surface irregularities are provided on the circumferential surface of the elastomer layer 14. Concave portions lower than the convex portions 16 are formed between the convex portions 16, and irregularities are provided on the circumferential surface of the elastomer layer 14 by the plurality of convex portions 16.

[0026] Each of the plurality of convex portions 16 (convex portion 16) is formed of an oblique cylinder whose front end side is forward in the direction opposite to the paper feed direction than the base end side (located in a position advancing in the direction opposite to the paper feed direction). An oblique cylinder is a cylinder whose bottom surface and side surface are not orthogonal. In addition, a cylinder whose bottom surface and side surface are orthogonal is a right cylinder. The convex portion 16 formed of an oblique cylinder has a linear inclination L from the base end toward the front end in the direction opposite to the paper feed direction on the side forward in the direction opposite to the paper feed direction. The inclination angle θ relative to the direction opposite to the paper feed direction (the angle θ between the vector from the upper base 16a side of the convex portion 16 toward the lower base 16b side and the vector toward the direction opposite to the paper feed direction along the inclination L) is an obtuse angle. The upper base 16a and the lower base 16b of the convex portion 16 formed of an oblique cylinder are parallel, and the upper base 16a and the lower base 16b are the same circle and have the same area. The convex portion 16 formed of an oblique circular column has its front end side portion located forward in the direction opposite to the paper feed direction at position X, which is further forward than its base end side portion located forward in the direction opposite to the paper feed direction at position Y.

[0027] In the paper feed roller 10 of such a configuration, Figure 4 As shown, when the paper P is conveyed, the plurality of convex portions 16 start from a state not in contact with the paper P as the convex portion 161, and then contact with the paper P as the convex portion 162, and then fall down in the opposite direction to the paper feeding direction due to the pressure from the paper P as the convex portion 163, and then recover from the fallen state in the paper feeding direction as the convex portion 164, and then the paper P is fed in the paper feeding direction by the restoring force of the fallen convex portion as the convex portion 165, and then separate from the paper P as the convex portion 166. In this way, when the paper P is conveyed, the convex portion 16 in contact with the paper P is likely to fall down in the opposite direction to the paper feeding direction, and the restoring force of the fallen convex portion 16 is likely to act in the paper feeding direction, thereby improving the conveying force of the paper P. Thus, poor conveying of the paper P is suppressed for a long time.

[0028] Furthermore, since the plurality of protrusions 16 have a linear inclination L from the base end toward the front end in the direction opposite to the paper feeding direction on the side in the direction opposite to the paper feeding direction, the protrusions 163 are easily toppled in the direction opposite to the paper feeding direction by the pressure from the paper P. Furthermore, since the inclination angle θ with respect to the direction opposite to the paper feeding direction is an obtuse angle, the protrusions 163 are easily toppled in the direction opposite to the paper feeding direction by the pressure from the paper P. Furthermore, since the plurality of protrusions 16 are composed of an inclined cylinder whose front end side is forward in the direction opposite to the paper feeding direction than the base end side, the protrusions 163 are easily toppled in the direction opposite to the paper feeding direction by the pressure from the paper P.

[0029] The inclination angle θ relative to the direction opposite to the paper feeding direction is not limited as long as it is an obtuse angle, and 95° to 140° is preferred. When the inclination angle θ is 95° or more, it is easy for the convex portion 163 to fall down in the direction opposite to the paper feeding direction due to the pressure from the paper P. In addition, from this point of view, it is more preferred that the inclination angle θ is 100° or more. In addition, when the inclination angle θ is 140° or less, it is easy for the convex portion 164 to recover from the fallen state in the paper feeding direction. In addition, from this point of view, it is more preferred that the inclination angle θ is 130° or less, and it is further preferred that the inclination angle θ is 120° or less.

[0030] The height of the protrusion 16 is not particularly limited, and is preferably in the range of 30 to 500 μm. When the height of the protrusion 16 is 30 μm or more, it is easy to fall down in the direction opposite to the paper feeding direction due to the pressure from the paper P, like the protrusion 163. In addition, from this point of view, the height of the protrusion 16 is preferably 50 μm or more, and more preferably 100 μm or more. In addition, when the height of the protrusion 16 is 500 μm or less, it is easy to recover from the fallen state to the paper feeding direction, like the protrusion 164. In addition, from this point of view, the height of the protrusion 16 is more preferably 400 μm or less, and more preferably 300 μm or less. In addition, the height of the protrusion 16 refers to the size of the protrusion 16 along the radial direction of the roller.

[0031] The diameter of the oblique cylindrical projection 16 (the circumferential length and the axial length of the paper feed roller 10) can be appropriately set according to the height of the projection 16. The diameter of the projection 16 can be set within a range of 10 to 500 μm, for example.

[0032] exist Figure 1 In the embodiment, the plurality of protrusions 16 are evenly distributed / arranged on the peripheral surface of the elastic layer 14. The plurality of protrusions 16 may be randomly arranged on the peripheral surface of the elastic layer 14, or may be arranged in an array.

[0033] exist Figure 1In the embodiment, a plurality of protrusions 16 are arranged on the circumferential surface of the elastomer layer 14 in an axial and circumferential arrangement. Grooves of continuous concave portions are formed between the rows of protrusions 16 arranged in the circumferential direction. In addition, grooves of continuous concave portions are also formed between the rows of protrusions 16 arranged in the axial direction. Since the grooves of the concave portions that are continuous in the circumferential direction are formed in the rotation direction of the paper feed roller 10, the paper dust that moves from the protrusions 16 to the grooves of the concave portions does not stay in the grooves as the roller rotates, but is easily discharged from the grooves to the outside of the roller. That is, the grooves form a discharge path for the paper dust generated when the paper is transported, and the paper dust is easily discharged to the outside of the roller, so that the reduction in the coefficient of friction caused by the accumulation of paper dust is easily suppressed.

[0034] The shape of the plurality of protrusions provided on the peripheral surface of the elastic layer 14 is not limited to Figure 3 The oblique cylindrical protrusion 16 shown in the figure may be in various shapes. Figure 5 In FIG. 1 , a plurality of preferred examples of the shapes of the convex portions are shown as the plurality of convex portions provided on the peripheral surface of the elastic layer 14. Figure 5 In FIG. 1 , the shape of the convex portion is shown by observing the convex portion from the radial direction (x direction) of the paper feed roller, observing the convex portion from the circumferential direction (y direction) of the paper feed roller, and observing the convex portion from the axial direction (z direction) of the paper feed roller. Figure 5 In (a), the shapes of styles 1 to 8 are shown. Figure 5 In (b), the shapes of Patterns 9 to 16 are shown.

[0035] The convex part of pattern 1 is Figure 3 The oblique cylindrical protrusion 16 shown. The protrusion of pattern 1 is composed of an oblique cylindrical column whose upper and lower bases are both perfect circles of the same size. The lower base of the protrusions of patterns 2 and 3 is composed of a perfect circle, but the upper base is composed of an oblique cylindrical column that is elliptical and elongated in the circumferential direction or axial direction of the paper feed roller.

[0036] An oblique cylinder is a type of oblique cylinder. As an oblique cylinder, an oblique prism can be cited in addition to an oblique cylinder. The bottom surface of an oblique prism is composed of a polygon such as a triangle, a quadrilateral, or a pentagon. An oblique prism is a cylinder whose bottom surface and side surface are not orthogonal to each other, like an oblique cylinder. A plurality of convex portions can also be composed of other oblique cylinders other than an oblique cylinder.

[0037] The convex portion of pattern 5 is composed of an oblique quadrangular prism whose upper and lower bases are both regular quadrilaterals of the same size and whose side faces are forward in the direction opposite to the paper feeding direction. The convex portions of patterns 6 and 7 are composed of an oblique quadrangular prism whose lower base is composed of a regular quadrangle, whose upper base is a quadrilateral elongated in the circumferential direction or axial direction of the paper feeding roller, and whose side faces are forward in the direction opposite to the paper feeding direction. The convex portion of pattern 9 is composed of an oblique quadrangular prism whose upper and lower bases are both regular quadrilaterals of the same size and whose side faces are forward in the direction opposite to the paper feeding direction. The convex portions of patterns 10 and 11 are composed of an oblique quadrangular prism whose lower base is composed of a regular quadrangle but whose upper base is an oblique quadrangular prism elongated in the circumferential direction or axial direction of the paper feeding roller and whose side faces are forward in the direction opposite to the paper feeding direction. In addition, as the oblique quadrangular prism constituting multiple convex portions, the upper and lower bases may not be regular quadrilaterals but rectangles, rhombuses, parallelograms, trapezoids, etc.

[0038] The convex part of pattern 13 is composed of an oblique triangular prism whose upper and lower bases are both equilateral triangles of the same size and whose edges are forward in the direction opposite to the paper feeding direction. The convex parts of patterns 14 and 15 are composed of an oblique triangular prism whose lower base is composed of an equilateral triangle but whose upper base is a triangle elongated in the circumferential direction or axial direction of the paper feeding roller and whose edges are forward in the direction opposite to the paper feeding direction. In addition, as an oblique triangular prism constituting a plurality of convex parts, the upper and lower bases may not be equilateral triangles but may be isosceles triangles, scalene triangles, etc.

[0039] In the case of the convex portion formed by the inclined column, the front end side thereof is positioned forward of the base end side thereof in the direction opposite to the paper feed direction. In addition, the convex portion formed by the inclined column has a linear inclination from the base end toward the front end in the direction opposite to the paper feed direction on the side positioned forward of the direction opposite to the paper feed direction. Moreover, the inclination angle θ relative to the direction opposite to the paper feed direction is an obtuse angle. The upper base and the lower base of the convex portion formed by the inclined column are parallel. In the case of the convex portion formed by the inclined column, the position of the portion of the front end side thereof positioned forward of the direction opposite to the paper feed direction is positioned forward of the portion of the base end side thereof positioned forward of the direction opposite to the paper feed direction.

[0040] For the convex portion formed by the inclined column, the size of the area of ​​the upper base is preferably less than the size of the area of ​​the lower base. If the size of the area of ​​the upper base is less than the size of the area of ​​the lower base, it is easy to ensure the force of the multiple convex portions pressing the paper in the direction opposite to the paper feeding direction when the paper is transported. Among the convex portions formed by the inclined column, the size of the area of ​​the upper base and the lower base of the convex portions of patterns 1, 5, 9, and 13 is the same. Among the convex portions formed by the inclined column, the size of the area of ​​the upper base of the convex portions of patterns 2, 3, 6, 7, 10, 11, 14, and 15 is smaller than the size of the area of ​​the lower base.

[0041] The plurality of convex portions may also be formed by an oblique cone whose front end side is forward of the base end side in the direction opposite to the paper feeding direction among the oblique columns whose upper base area is smaller than the lower base area as described above. An oblique cone is a truncated oblique cone whose head is cut into a plane shape. An oblique cone is a cone whose foot of a perpendicular line dropped from the apex of the cone does not coincide with the center of gravity of the base surface. In addition, a cone whose foot of a perpendicular line dropped from the apex of the cone coincides with the center of gravity of the base surface is a straight cone. The front end side of the convex portion formed by the oblique cone is forward of the base end side in the direction opposite to the paper feeding direction. In addition, the convex portion formed by the oblique cone has a linear inclination from the base end toward the front end in the direction opposite to the paper feeding direction on the side forward of the direction opposite to the paper feeding direction. The inclination angle relative to the direction opposite to the paper feeding direction is an obtuse angle. The upper base and the lower base of the convex portion formed by the oblique cone may be parallel or non-parallel. In the convex portion formed by the oblique frustum, the position of the front end side portion thereof in the direction opposite to the paper feeding direction is positioned forward of the position of the base end side portion thereof in the direction opposite to the paper feeding direction. The area of ​​the upper base of the convex portion formed by the oblique frustum is smaller than the area of ​​the lower base.

[0042] Examples of the oblique truncated pyramid constituting the plurality of convex portions include an oblique circular truncated pyramid with a circular upper and lower base, an oblique truncated pyramid with a polygonal upper and lower base, etc. Examples of the polygon include a triangle, a quadrilateral, a pentagon, etc. Examples of the triangle include an equilateral triangle, an isosceles triangle, an unequal-skinned triangle, etc. Examples of the quadrilateral include a regular quadrilateral, a rectangle, a rhombus, a parallelogram, a trapezoid, etc.

[0043] The convex part of pattern 4 is an oblique circular truncated pyramid whose upper and lower bases are both formed by perfect circles and whose curved surface is forward in the direction opposite to the paper feeding direction. The convex part of pattern 8 is an oblique quadrangular truncated pyramid whose upper and lower bases are both formed by regular quadrilaterals and whose flat surface is forward in the direction opposite to the paper feeding direction. The convex part of pattern 12 is an oblique quadrangular truncated pyramid whose upper and lower bases are both formed by regular quadrilaterals and whose edge is forward in the direction opposite to the paper feeding direction. The convex part of pattern 16 is an oblique triangular truncated pyramid whose upper and lower bases are both formed by regular triangles and whose edge is forward in the direction opposite to the paper feeding direction.

[0044] The shapes of the multiple protrusions may be other shapes as long as the position of the front end side portion in the direction opposite to the paper feeding direction is closer to the front than the position of the base end side portion in the direction opposite to the paper feeding direction. Other shapes include irregular shapes, elliptical cylinders, fan-shaped cylinders, D-shaped cylinders, gear-shaped cylinders, truncated cylinders whose heads are cut into bevels or curved shapes, truncated cones whose heads are cut into bevels or curved shapes, etc. In addition, the shape may be that the top and bottom of the truncated cone are opposite (the area of ​​the upper base is larger than the area of ​​the lower base). Each upper base may also be a ground surface. The ground surface can be formed by grinding each upper base.

[0045] The multiple protrusions provided on the circumferential surface of the elastomer layer 14 may be composed of only one of these various protrusions, or may be composed of a combination of two or more. For example, the circumferential surface of the elastomer layer 14 of a paper feed roller 10 may include oblique cylindrical protrusions and oblique prism-shaped protrusions. In addition, protrusions of the same shape but different sizes and inclination angles may be combined. For example, the circumferential surface of the elastomer layer 14 of a paper feed roller 10 may include oblique cylindrical protrusions with an inclination angle of 95° and oblique cylindrical protrusions with an inclination angle of 100°. In addition, the circumferential surface of the elastomer layer 14 of a paper feed roller 10 may include oblique cylindrical protrusions with an inclination angle of 95° and oblique prism-shaped protrusions with an inclination angle of 100°.

[0046] The plurality of convex portions provided on the circumferential surface of the elastic layer 14 may also be Figure 1 Arrange in an arrangement other than the arrangement shown. Figure 6 In (a), it is shown Figure 1 The arrangement of the plurality of convex portions of the paper feed roller 10 is shown. Figure 6 (b) to (d) show other arrangement forms of the plurality of protrusions.

[0047] exist Figure 6 In the paper feed roller 10 of (a), a plurality of convex portions 16 are arranged in the axial direction and the circumferential direction on the peripheral surface of the elastic layer 14. The plurality of convex portions 16 are evenly arranged on the peripheral surface of the elastic layer 14. Therefore, the contact with the paper during the conveyance of the paper becomes even.

[0048] exist Figure 6 In the paper feed roller 20 of (b), a plurality of protrusions 16 are arranged in a staggered manner on the peripheral surface of the elastic layer 14. Specifically, the protrusions 16 of the second row are arranged between the protrusions 16 of the first row, the protrusions 16 of the third row are arranged between the protrusions 16 of the second row, and the protrusions 16 of the fourth row are arranged between the protrusions 16 of the third row, and the protrusions 16 of the fourth row are arranged in a staggered manner. Figure 6In the paper feed roller 20 of (b), the plurality of convex portions 16 are evenly arranged on the peripheral surface of the elastic layer 14. Therefore, the contact with the paper during the conveyance of the paper becomes even.

[0049] exist Figure 6 In the paper feed roller 30 of (c), the convex portions 16 are arranged on the circumferential surface of the elastic layer 14 in a direction (inclined direction close to the circumferential direction) with respect to the axial direction at a predetermined angle exceeding 45°. Figure 6 In the paper feed roller 30 of (c), a structure is shown in which a plurality of rows of convex portions 16 are arranged in a direction of a predetermined angle on the peripheral surface of the elastic layer 14 (not in a spiral shape). Figure 6 In the paper feed roller 30 of (c), grooves of concave portions are formed between the rows of convex portions 16 in a direction (inclined direction close to the circumferential direction) with respect to the axial direction at a predetermined angle exceeding 45°, so that Figure 6 As shown in (a) of the figure, the paper dust moving from the convex portion 16 to the concave portion groove does not stay in the groove as the roller rotates, but is easily discharged from the groove to the outside of the roller. That is, the groove becomes a discharge path for the paper dust generated when the paper is conveyed, and the paper dust is easily discharged to the outside of the roller, so it is easy to suppress the reduction of the friction coefficient caused by the accumulation of paper dust.

[0050] exist Figure 6 In the paper feed roller 40 of (d), on the peripheral surface of the elastic layer 14, the protrusions 16 are arranged in a direction (in the direction of the arrow) at a predetermined angle less than 45° relative to the axial direction (in an inclined direction close to the axial direction). Figure 6 In the paper feed roller 40 of (d) in FIG. 1 , a structure is shown in which a plurality of rows of convex portions 16 in a direction of a predetermined angle are arranged in parallel. Figure 6 In the paper feed roller 40 in (d), grooves of concave portions are formed between rows of convex portions 16 in a direction at a specified angle less than 45° relative to the axial direction (in an inclined direction close to the axial direction). Therefore, paper dust generated when the paper is transported can easily move from the convex portions 16 on the roller surface to the grooves of the concave portions, and the paper dust is difficult to stay / stick to the contact portion with the paper, so the reduction in the friction coefficient caused by this can be easily suppressed.

[0051] Next, the material structure of the paper feed roller according to the present invention will be described.

[0052] Examples of the material of the shaft 12 include synthetic resins such as polyacetal (POM), acrylonitrile-butadiene-styrene copolymer (ABS), polycarbonate, and nylon, and metal materials such as iron, stainless steel, and aluminum. The shaft 12a may be hollow or solid.

[0053] The elastic layer 14 is formed of an elastic material such as a cross-linked 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 polyurethane rubber, epichlorohydrin rubber, silicone rubber, etc. can be used.

[0054] The elastic layer 14 may be conductive or semi-conductive, or may not be conductive or semi-conductive. The volume resistivity of the conductive or semi-conductive elastic layer 14 is 10 2 ~10 10 Ω·cm, 10 3 ~10 9 Ω·cm, 10 4 ~10 8 If the elastic layer 14 has conductivity or semi-conductivity, the residual charge on the surface of the elastic layer 14 can be suppressed to a low level, and adhesion of paper dust can be easily suppressed.

[0055] The elastomer layer 14 may also contain a conductive agent from the viewpoint of reducing resistance. Examples of the conductive agent include electronic conductive agents and ion conductive agents. Examples of electronic conductive agents include carbon black, graphite, c-TiO2, c-ZnO, c-SnO2 (c- means conductivity), etc. Examples of ion conductive agents include quaternary ammonium salts, borates, surfactants, etc.

[0056] Various additives may be added to the elastic layer 14 as needed. Examples of additives include lubricants, vulcanization accelerators, antioxidants, light stabilizers, viscosity modifiers, processing aids, flame retardants, plasticizers, fillers, dispersants, defoamers, pigments, and mold release agents.

[0057] The thickness of the elastic layer 14 is not particularly limited and may be appropriately set within a range of 0.1 to 10 mm.

[0058] The elastic body layer 14 can be formed by molding using a forming mold using a rubber composition. For example, the shaft body 12 can be coaxially arranged in the hollow part of a roll forming mold, an uncrosslinked rubber composition can be injected, and after heating / curing (crosslinking), the elastic body layer 14 can be formed on the outer periphery of the shaft body 12 by demolding. The forming mold can use a mold having a concave portion having a shape corresponding to the convex portion 16 formed on its inner circumferential surface. The convex portion 16 of the elastic body layer 14 can be formed by mold transfer using a forming mold, for example.

[0059] The recessed portion on the inner peripheral surface of the forming mold can be formed by various recessed portion forming methods such as electrical discharge machining, etching, shot blasting, grinding, eutectoid plating, or a combination thereof. In eutectoid plating, uniform resin particles are included in the plating solution, and the resin particles are precipitated on the inner peripheral surface of the forming mold together with the electroplating metal, and the resin particles present on the plating surface are removed, thereby forming the recessed portion on the inner peripheral surface of the forming mold.

[0060] As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment at all, Various changes can be made within the range which does not deviate from the summary of this invention.

[0061] For example, in the above-mentioned embodiment, the paper feed roller 10 is a structure including a shaft body 12 and an elastic body layer 14 formed on the outer periphery of the shaft body 12, and the outermost layer is the elastic body layer 14, but a surface layer may be provided on the outer side of the elastic body layer 14. In this case, the surface layer is the outermost layer, and the elastic body layer 14 is arranged on the inner side of the surface layer. The convex portion 16 is formed on the circumferential surface of the elastic body layer 14, and the surface layer is formed to a thickness that ensures the surface unevenness formed by the plurality of convex portions 16. In addition, a surface modification treatment may be performed instead of forming a surface layer.

[0062] [Example]

[0063] Hereinafter, the present invention will be described in detail using Examples and Comparative Examples.

[0064] (Manufacture of paper feed rollers)

[0065] A cylindrical forming die having a plurality of predetermined recessed portions on the inner circumference is used to form a core material ( An elastic layer (3 mm thick) of a polyurethane rubber composition is formed on the outer periphery of the elastic layer. Thus, a paper feed roller having a plurality of predetermined convex portions on the circumference of the elastic layer is obtained. The convex shape is Figure 5 The various styles shown. Multiple convex portions such as Figure 6 As shown in (a), the convex portions are arranged on the circumferential surface of the elastic layer in the axial direction of the roller and in the circumferential direction of the roller. The length of the upper bottom of each convex portion in the circumferential direction of the roller, the length of the upper bottom of each convex portion in the axial direction of the roller, the length of the lower bottom of each convex portion in the circumferential direction of the roller, the length of the lower bottom of each convex portion in the axial direction of the roller, the inclination angle (convex angle θ) in the direction opposite to the paper feeding direction, and the height (convex height) are shown in Tables 1 to 4.

[0066] (Durability Evaluation)

[0067] The paper feed roller was installed in a commercially available copier with an FRR paper feed system, and the paper feed performance was evaluated. Commercially available PPC paper was used as the paper, and 500,000 sheets (500K sheets) of paper were fed, and the number of paper jams caused by paper dust was measured. The number of paper jams that occurred was set to "A" if it was less than one time, "B" if it was more than two times but less than five times, "C" if it was more than six times but less than ten times, and "D" if it was eleven times. In addition, the durability evaluation was terminated when the paper jam occurred eleven times.

[0068] [Table 1]

[0069]

[0070] [Table 2]

[0071]

[0072] [Table 3]

[0073]

[0074] [Table 4]

[0075]

[0076] The convex portion of the elastomer layer of each embodiment is composed of an oblique cylinder (oblique circular cylinder, oblique quadrangular prism or oblique triangular prism) or an oblique cone (oblique circular cone, oblique quadrangular cone or oblique triangular cone). On the other hand, the convex portion of the elastomer layer of each comparative example is composed of a right cylinder (straight circular cylinder or right quadrangular prism) or a right cone (straight circular cone or right quadrangular cone). The front end side of the convex portion of the elastomer layer of each embodiment is closer to the front than the base end side in the direction opposite to the paper feed direction, and the position of the portion of the front end side closer to the front in the direction opposite to the paper feed direction is closer to the front than the position of the portion of the base end side closer to the front in the direction opposite to the paper feed direction. In contrast, the position of the portion of the front end side of the convex portion of the elastomer layer of each comparative example closer to the front in the direction opposite to the paper feed direction is not closer to the front than the position of the portion of the base end side closer to the front in the direction opposite to the paper feed direction. According to each embodiment, even when the paper feed is 500,000 sheets, the paper conveying failure is suppressed. According to each comparative example, when the paper feed is 500,000 sheets, the paper jam is frequent and the paper conveying failure is not suppressed. Therefore, it can be understood that the position of the front end side of the convex part of the elastic body layer in the direction opposite to the paper feeding direction is forward than the position of the base end side in the direction opposite to the paper feeding direction, thereby suppressing the paper conveying failure for a long time.

[0077] Furthermore, according to the comparison of Examples 1 to 8 or Examples 9 to 16, when the inclination angle relative to the direction opposite to the paper feeding direction is 95° to 140°, the effect of suppressing the poor paper conveying is particularly excellent. In addition, when the height of the convex portion is 30 to 500 μm, the effect of suppressing the poor paper conveying is particularly excellent.

[0078] As mentioned above, although the embodiment of the present invention was described, the present invention is not limited to the above-mentioned embodiment at all, and various changes can be made within the scope not departing from the gist of the present invention.

[0079] Description of Reference Numerals

[0080] 10: Paper feeding roller;

[0081] 12: Axis;

[0082] 14: Elastomer layer;

[0083] 16: Convex part.

Claims

1. A paper feed roller (10, 20, 30, 40) of an electronic photographic device, comprising a shaft (12) and an elastic layer (14) formed on the outer periphery of the shaft (12), characterized in that: A plurality of convex portions (16) forming surface irregularities are provided on the peripheral surface of the elastic layer (14). The plurality of convex portions (16) have a position (X) of a portion on the front end side thereof that is forward in a direction opposite to the paper feeding direction (F) that is forward of a portion on the base end side thereof that is forward of a portion on the ... direction opposite to the paper feeding direction (F) that is forward of a portion on the base end side thereof that is forward of The plurality of protrusions (16) have a linear inclination (L) on the front side in the direction opposite to the paper feeding direction (F) from the base end toward the front end in the direction opposite to the paper feeding direction (F), The plurality of protrusions (16) are regularly arranged on the peripheral surface of the elastomer layer (14). The plurality of convex portions (16) do not include a state in which a plurality of convex stripes and concave grooves are formed parallel to the axial direction of the paper feed rollers (10, 20, 30, 40).

2. The paper feed roller (10, 20, 30, 40) according to claim 1, characterized in that: The inclination angle (θ) with respect to the direction opposite to the paper feeding direction (F) is an obtuse angle.

3. The paper feed roller (10, 20, 30, 40) according to claim 2, characterized in that: The inclination angle (θ) with respect to the direction opposite to the paper feeding direction (F) is 95° to 140°.

4. The paper feed roller (10, 20, 30, 40) according to any one of claims 1 to 3, characterized in that: The plurality of protrusions (16) are composed of an inclined column or an inclined frustum whose front end side is located forward of the base end side in a direction opposite to the paper feeding direction (F).

5. The paper feed roller (10, 20, 30, 40) according to claim 4, characterized in that: Regarding the plurality of protrusions (16), the area of ​​the upper base (16a) thereof is smaller than the area of ​​the lower base (16b) thereof.

6. The paper feed roller (10, 20, 30, 40) according to any one of claims 1 to 3, characterized in that: The height of the plurality of protrusions (16) is 30 to 500 μm.

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