Paper feeding roller and paper feeding device

Abstract

The present invention provides a paper feeding roller in which paper transport failure due to eccentric wear is less likely to occur even when used for a long time in a cantilever support configuration, and a paper feeding device provided with the paper feeding roller. The paper feeding roller (50) has a cantilever configuration in which a shaft body (51) is supported at one end, an elastomer layer (52) has support ends (53) and free ends (54) at both ends along the rotation axis 5A, the outer diameter of a cross section orthogonal to the rotation axis 5A is larger at the free ends (54) than at the support ends (53), and the region including the free ends (54) has a tip expansion portion (57) that expands in a straight line or convex shape toward the free ends (54) along the rotation axis 5A. In addition, the paper feeding device is provided with a feeding roller that is driven to rotate and transport paper, and a blocking roller that is in pressure contact with the feeding roller and suppresses paper jamming by having a torque limiter installed. At least one of the feeding roller and the blocking roller is configured as the above-described paper feeding roller (50).

Description

Technical Field

[0001] The present invention relates to a paper feed roller suitable for use as a component of a paper feed device in an image forming apparatus such as a copier, printer, or fax machine, and a paper feed device having such a paper feed roller. Background Technology

[0002] In image forming devices such as copiers, printers, and fax machines that use electrophotography, the paper feeding device includes a paper feeding roller. The paper feeding roller is generally formed into a cylindrical shape from an elastic material such as a cross-linked rubber, with its circumferential surface serving as the contact surface with the paper. When handling paper, this type of paper feeding roller often rotates under pressure from other components, resulting in surface pressure (clamping pressure). During repeated paper handling, the surface of the paper feeding roller is prone to wear.

[0003] For example, in an electrophotographic image forming apparatus, a paper feeding device is used that comprises a feed roller (paper delivery roller) that is driven to rotate, and a stop roller (separation roller) for which a torque limiter is mounted and presses against the feed roller, thus enabling the suppression of paper stacking. In this case, the feed roller and the stop roller rotate in a state of mutual pressing, which easily leads to wear on the surface of either or both rollers. Thus, if the surface of the feed roller wears, the contact area between the outer peripheral surface and the paper decreases, the coefficient of friction decreases, and even if the feed roller is not used for a long period, poor paper handling will occur.

[0004] As a means of suppressing poor handling caused by wear on the surface of the paper feed roller, sometimes a high coefficient of friction is maintained over a long period by giving the surface of the paper feed roller a raised or recessed pattern. For example, Patent Document 1 describes a method in which multiple raised strips and grooves are formed parallel to the axial direction of the paper feed roller. In addition, as another means of suppressing poor handling, efforts have been made related to the support structure of the roller shaft, as described in Patent Document 2.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2017-065907

[0008] Patent Document 2: Japanese Patent Application Publication No. 10-212044 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] As in Patent Document 1, measures such as forming a predetermined uneven shape on the surface of the paper feed roller can effectively suppress the decrease in the coefficient of friction. However, assuming the paper feed roller is used under conditions where surface wear is likely to occur, it is desirable to further effectively suppress the decrease in the coefficient of friction. For example, in recent years, low-quality papers with high ash content and low prices, as well as inferior papers containing a lot of filler materials, have become rampant. When these papers with high ash content and filler materials are used, paper dust and dirt are generated during feeding. This paper dust, dirt, and aliphatic components contained in the filler materials easily adhere to the surface of the paper feed roller. This is related to the decrease in the coefficient of friction between the paper feed roller and the paper, and can easily lead to poor paper handling.

[0011] When using low-quality paper, the adhesion of paper dust and dirt can be suppressed to some extent by creating an uneven surface on the paper feed roller. However, if the surface pressure is not applied evenly to the entire roller, wear will begin from the area with higher surface pressure (uneven wear), resulting in a worn finish from the uneven surface. This reduces the effectiveness of suppressing paper dust and dirt adhesion through the uneven surface, and also cannot prevent a decrease in the surface friction coefficient. Consequently, poor paper handling is more likely to occur.

[0012] As described in Patent Document 2, when the paper feed roller is configured with a cantilever support structure, the paper feed roller is prone to deflection due to the load during paper handling. This leads to uneven contact between the circumferential surface of the paper feed roller and the paper, resulting in uneven wear where one end of the roller's circumferential surface wears first. Therefore, in cantilevered paper feed rollers, a decrease in the coefficient of friction due to uneven wear is particularly likely to occur, resulting in poor paper handling even without prolonged use.

[0013] Therefore, the problem to be solved by the present invention is to provide a paper feed roller that is unlikely to cause poor paper handling due to uneven wear even after long-term use with a cantilever support structure, and a paper feed device having such a paper feed roller.

[0014] means for solving problems

[0015] To solve the above problems, the paper feeding roller of the present invention has a shaft and an elastomer layer formed on the outer periphery of the shaft. It is a paper feeding roller that rotates about a rotation axis and is provided in a paper feeding device. The paper feeding roller has a cantilever support structure that supports the shaft at one end to the paper feeding device. The elastomer layer has two ends along the rotation axis: a support end, which is the end on the side where the shaft is supported by the paper feeding device; and a free end, which is the end on the side where the shaft is not supported by the paper feeding device. The outer diameter of the cross section of the elastomer layer orthogonal to the rotation axis is larger at the free end than at the support end. The paper feeding roller has an end extension portion in the region including the free end, which is formed by the outer diameter becoming more linear or convex towards the free end along the rotation axis.

[0016] Here, it is preferable that the end extension is formed to include at least a region extending from the center between the support end and the free end along the rotation axis to the free end. Additionally, it is preferable that the elastomer layer has a straight cylindrical portion, in a position closer to the support end along the rotation axis than the end extension, in a manner continuous with the end extension, with a smaller change in outer diameter along the rotation axis than the end extension. Preferably, the outer diameter of the cross-section of the elastomer layer orthogonal to the rotation axis is set as D1 at the support end, D2 at the center between the support end and the free end along the rotation axis, and D3 at the free end; then |D2-D1|≤0.05mm, and 0.05mm<D3-D2≤0.50mm. Preferably, the JIS-A hardness of the surface of the elastomer layer is 30 degrees or more and 80 degrees or less.

[0017] The paper feeding device according to the present invention comprises: a supply roller driven to rotate and transport paper; and a stop roller pressed against the supply roller and for which a torque limiter is mounted to suppress the stacking of the paper, wherein at least one of the supply roller and the stop roller constitutes the paper feeding roller according to the present invention.

[0018] Here, it is preferable that both the supply roller and the retaining roller are configured as paper feeding rollers according to the present invention. Furthermore, it is preferable that the JIS-A hardness of the surface of the elastomer layer in both the supply roller and the retaining roller is 30 degrees or more and 80 degrees or less. Preferably, the surface hardness of the elastomer layer of the retaining roller, measured in JIS-A hardness, is at least 5 degrees greater than the surface hardness of the elastomer layer of the supply roller.

[0019] Invention Effects

[0020] The paper feed roller described above has a cantilever support structure, and the elastomer layer has an end extension in the region including the free end that is not supported by the paper feed device. Generally, in paper feed rollers employing a cantilever support structure, when pressed against other components, a larger surface pressure acts on the support end side (which is cantilevered) than on the free end side, making the surface of the elastomer layer prone to wear. However, in the paper feed roller of this invention, by having an end extension structure on the free end side, the difference in surface pressure between the support end side and the free end side is less likely to increase when pressed against other components. Therefore, uneven wear on the support end side is less likely to occur, and even with long-term use, poor paper handling due to uneven wear is less likely to occur.

[0021] Here, when an end extension is formed along the rotation axis, including at least a region extending from the center between the support end and the free end to the free end, and the elastomer layer has a straight cylindrical portion with a smaller change in outer diameter along the rotation axis than the end extension on the support end side, in a manner continuous with the end extension, it is possible to effectively mitigate the concentration of surface pressure towards the support end side.

[0022] When the outer diameter of the cross section of the elastic layer orthogonal to the rotation axis is D1 at the support end, D2 at the center between the support end and the free end along the rotation axis, and D3 at the free end, and |D2-D1|≤0.05mm, and 0.05mm<D3-D2≤0.50mm, it is particularly effective in homogenizing the surface pressure and suppressing the resulting uneven wear.

[0023] When the JIS-A hardness of the elastomer layer surface is above 30 degrees and below 80 degrees, it can effectively suppress the wear of the paper feed roller surface and easily avoid damage to the paper caused by paper scraping, etc.

[0024] In the paper feeding device according to the above invention, at least one of the feed roller and the deflector roller, which are pressed against each other, is cantilevered, and the elastomer layer has an end extension on the free end side, thus constituting the paper feeding roller according to the present invention. Therefore, uneven wear caused by the uneven distribution of the surface pressing against the support end side is suppressed in the roller with the end extension and the other roller. As a result, the paper feeding device can be used continuously for a long time while avoiding poor paper handling caused by uneven wear.

[0025] Here, when both the supply roller and the deflector roller are configured as the paper feeding rollers described above in this invention, both the supply roller and the deflector roller can effectively suppress uneven wear and can continuously supply paper while suppressing poor paper handling over a long period of time.

[0026] In addition, when the JIS-A hardness of the elastomer layer surface is above 30 degrees and below 80 degrees for both the supply roller and the deflector roller, both the supply roller and the deflector roller can effectively suppress surface wear and easily prevent damage to the paper caused by paper scraping.

[0027] When the surface hardness of the elastomeric layer of the retardation roll, measured by JIS-A hardness, is more than 5 degrees greater than the surface hardness of the elastomeric layer of the feed roll, the coefficient of friction between the retardation roll and the feed roll increases, making it easier to achieve higher handling performance in the paper feeding device. Attached Figure Description

[0028] Figure 1 This is a schematic diagram illustrating a paper feeding device according to one embodiment of the present invention. It shows the state as observed from the free end side of the feed roller and the stop roller.

[0029] Figure 2 It is aimed at Figure 1 The paper feeding device shown is a schematic diagram illustrating the structure around the feed roller and the stop roller. The diagram shows the state as viewed from the front of the circumference of the feed roller and the stop roller.

[0030] Figure 3 It means Figure 1 The diagram shows the paper feeding action of the paper feeding device. Figure 3 (a) in the text represents the state of a sheet of paper before it reaches the rollers. Figure 3 (b) in the text represents the action when a piece of paper arrives at the roller.

[0031] Figure 4 It means Figure 1 The diagram shows the paper feeding action of the paper feeding device. Figure 4 (a) in the text represents the state of the two sheets of paper before they reach the rollers. Figure 4 (b) in the text represents the action when the two sheets of paper arrive at the rollers.

[0032] Figure 5 This is a schematic diagram showing the shape of a paper feed roller according to one embodiment of the present invention. It shows the state as viewed from the front of the circumferential surface.

[0033] Figure 6 This is a schematic diagram showing a paper feeding device that has conventional paper feeding rollers as both a supply roller and a deceleration roller.

[0034] Figure 7 It is a graph that shows the results of changing the shape of the roller and evaluating the distribution of the surface pressure and the durability of the roller in tabular form.

[0035] Figure 8 This is a graph showing an example of the measurement results of the surface pressure distribution on the roller surface. Figure 8In the diagram, (a) represents the case where the distribution is relatively uniform. Figure 8 (b) in the diagram represents the case where the distribution uniformity is low. Detailed Implementation

[0036] Hereinafter, the paper feeding roller and paper feeding device according to embodiments of the present invention will be described in detail. The paper feeding device according to embodiments of the present invention can be constructed using the paper feeding roller according to embodiments of the present invention. The specific type and application of the paper feeding roller according to embodiments of the present invention are not limited as long as it is included in a paper feeding device. Hereinafter, the description will focus on a configuration where the feed roller and the deflection roller included in the paper feeding device of an image forming apparatus are used as the paper feeding roller according to embodiments of the present invention. First, after a general overview of the paper feeding device as a whole, details of the paper feeding roller will be described.

[0037] Paper feeding device

[0038] First, a general outline of a paper feeding device according to one embodiment of the present invention will be described.

[0039] One embodiment of the present invention relates to a paper feeding device 1 provided in an image forming apparatus such as an electrophotographic copier, printer, or fax machine. Figure 1 , 2 As shown, the paper feeding device 1 includes a feed roller 10 (paper delivery roller) and a stop roller 20 (separation roller). The feed roller 10 and the stop roller 20 are each formed as cylindrical components and are arranged side by side. In this specification, the direction along the rotation axes 1A and 2A of the feed roller 10 and the stop roller 20 is defined as the axial direction (direction a).

[0040] The supply roller 10 has a shaft 11 and an elastic layer 12 formed on the outer periphery of the shaft 11. The retaining roller 20 has a shaft 21 and an elastic layer 22 formed on the outer periphery of the shaft 21. The supply roller 10 is driven to rotate and transport paper P by receiving power from a drive source (motor) not shown. The retaining roller 20 is pressed against the supply roller 10 by a force-applying member 29, such as a spring, under a predetermined pressure. In addition, a torque limiter (not shown) is built into the retaining roller 20, configured to apply braking torque in the opposite direction to the transport direction of paper P (direction of arrow p1). The retaining roller 20 has the function of suppressing the stacking of paper P, in other words, suppressing the phenomenon of feeding multiple sheets of paper P in an overlapping manner.

[0041] like Figure 2As shown, in the paper feeding device 1 according to this embodiment, both the supply roller 10 and the deceleration roller 20 have a cantilever support structure, with the shafts 11 and 21 supported by the paper feeding device 1 at one end along the axial direction a. Furthermore, the elastomer layers 12 and 22 have support ends 13 and 23 and free ends 14 and 24 at both ends. The support ends 13 and 23 are the ends of the shafts 11 and 21 supported by the paper feeding device 1, and the free ends 14 and 24 are the ends of the shafts 11 and 21 not supported by the paper feeding device 1. In addition, the supply roller 10 and the deceleration roller 20 each have end extensions 17 and 27, respectively, whose outer diameters are larger at the free ends 14 and 24 than at the support ends 13 and 23, and which further extend along the axial direction a towards the free ends 14 and 24. The structure of this paper feeding roller according to the embodiment of the present invention, which has end extensions at the free ends, will be described in detail later. In the paper feeding device 1, the retaining roller 20 is pressed against the feed roller 10, but in Figure 2 The structure of the end extensions 17 and 27 is shown in detail, and the elastic deformation of the supply roller 10 and the blocking roller 20 caused by the pressing is removed.

[0042] In the paper feeding device 1, the paper P being transported is stacked inside the paper feed cassette 30. The surface of the guide roller 40 (paper feed roller) is configured to make frictional contact with the upper surface of the stacked paper P, and the paper P is sequentially output from the paper feed cassette 30 toward the feed roller 10 via the guide roller 40. The guide roller 40 has a shaft 41 and an elastic layer 42 formed on the outer periphery of the shaft 41. The guide roller 40 is configured to rotate in conjunction with the drive of the feed roller 10 via a connecting component (gear, timing belt, etc., not shown).

[0043] As the supply roller 10 rotates, the guide roller 40 rotates, and sheets of paper P are successively output from the paper tray 30 toward the supply roller 10. Figure 3 As shown in (a), the supply roller 10 is driven to rotate before the paper P arrives. The stop roller 20, which is pressed against the supply roller 10, rotates along with the supply roller 10, overcoming the braking torque through the friction between the supply roller 10 and the stop roller 20 (between the rollers). If a sheet of paper P is successively output and arrives between the rollers, then... Figure 3 As shown in (b), the paper P is carried out through the rollers.

[0044] When two sheets of paper P are successively output from the paper feed box 30 toward the feed roller 10, as Figure 4 As shown in (a), before the sheets P1 and P2 arrive, the supply roller 10 rotates, and the resistance roller 20 rotates along with the supply roller 10, overcoming the braking torque. If two sheets of paper P1 and P2 arrive between the rollers in succession, then as shown in (a), the resistance roller 20 rotates. Figure 4As shown in (b), the stop roller 20 is in contact with the supply roller 10 via two sheets of paper P1 and P2. Because the frictional force acting between the two sheets of paper P1 and P2 is small, the stop roller 20 stops rotating due to the braking torque and does not follow the rotation of the supply roller 10. Therefore, the sheet P1 in contact with the supply roller 10 is carried out through the rollers as the supply roller 10 rotates, while the sheet P2 in contact with the stop roller 20 is not carried out. This suppresses the stacking of the sheets P.

[0045] As described above, in this paper feeding device 1, both the supply roller 10 and the stop roller 20 employ a cantilever support structure and have end extensions 17 and 27. However, it is not necessary for both to have end extensions; it is sufficient that at least one of the supply roller 10 and the stop roller 20 employs a cantilever support structure and has an end extension. If only one of the cantilevered rollers has an end extension, the other roller can employ a cantilever support structure or a double-support structure that supports both axial ends to the paper feeding device 1. Furthermore, the shape of this other roller can be any shape, preferably as shown below. Figure 6 The rollers 91 and 92 shown have a shape with a constant straight outer diameter along the axial direction a.

[0046] [Paper feed roller with end extension]

[0047] Next, a paper feeding roller 50 (hereinafter, sometimes simply referred to as a roller) having an end extension according to an embodiment of the present invention will be described in detail. In the paper feeding device 1 described above, the feed roller 10 and the deflection roller 20 are each configured as the paper feeding roller 50 according to an embodiment of the present invention.

[0048] In one embodiment of the present invention, the paper feeding roller 50 is used as a component of a paper feeding device and is formed as a cylindrical component that rotates about a rotation axis 5A. Figure 5 As shown, the paper feeding roller 50 has a shaft 51 and an elastomer layer 52 formed on the outer periphery of the shaft 51. The following description relating to the shape of the roller 50 refers to the shape of the elastomer layer 52.

[0049] One end of the roller 50 is a support end 53, and the other end is a free end 54. On the support end 53 side, the roller 50's shaft 51 is directly or indirectly supported by the paper feeding device 1. On the free end 54 side, the shaft 51 is not supported by the paper feeding device 1 and remains in an open state. In other words, the roller 50 has a cantilever support structure.

[0050] Roller 50 has a cylindrical shape, but not a straight cylindrical shape, and has a distribution along the axial direction a on its outer diameter. In other words, at various locations along the axial direction a, the cross-section orthogonal to the axis of rotation 5A is circular, but the outer diameter of this circle varies along the axial direction a, at least in a portion of the region.

[0051] Specifically, in roller 50, the outer diameter of the cross-section orthogonal to the axial direction a is larger at the free end 54 than at the support end 53. Furthermore, roller 50 has an end extension 57 in the region along axial direction a that includes the free end 54. The end extension 57 has an end extension shape (diameter expansion shape) where the outer diameter of roller 50, in other words, the outer diameter of the cross-section orthogonal to the rotation axis 5A, increases as it moves towards the free end 54 along axial direction a. More specifically, the end extension shape in the end extension 57 is trumpet-shaped. In other words, the outer diameter of roller 50 expands more linearly or convexly towards the free end 54. This trumpet-shaped end extension shape, as... Figure 5 As shown, the circumferential profile of the roller 50 can be easily identified when viewed from the front of the circumferential surface, or in a cross-section along the axial direction a.

[0052] In roller 50, if an end extension 57 is formed along the axial direction a in the region containing the free end 54, then the size of the region occupied by the end extension 57 and the shape of the region other than the end extension 57 are not specifically specified. Figure 5 In the roller 50 shown, an end extension 57 is formed only in a region occupying a portion of the free end 54 side along the axial direction a, and a straight cylindrical portion 56 with a flat shape is formed on the support end 53 side. The end extension 57 and the straight cylindrical portion 56 are smoothly continuous along the axial direction a.

[0053] Figure 6 In a conventional paper feeding device 9, as shown by the feed roller 91 and the deflector roller 92, the conventional paper feeding rollers are generally formed into a straight shape, or in other words, a straight cylindrical shape. If such straight-shaped paper feeding rollers 91 and 92 are cantilevered and contact pressure is applied from one direction on their circumference, a larger surface pressure (clamping pressure) acts along the axial direction a on the support ends 91a and 92a, while the surface pressure decreases towards the free ends 91b and 92b. Under such uneven surface pressure, if the rollers 91 and 92 rotate, surface wear occurs sharply on the support ends 91a and 92a compared to the free ends 91b and 92b, resulting in uneven wear. If the wear of rollers 91 and 92 continues, the uneven surface texture of the rollers 91 and 92 is easily abraded, and paper dust and dirt adhere to them, making it impossible to maintain a sufficient coefficient of friction with the paper P being transported. Therefore, uneven wear occurs, easily leading to poor handling of the paper P.

[0054] On the other hand, such as Figure 5As shown, in the paper feeding roller 50 of this embodiment, the outer diameter is larger at the free end 54 than at the support end 53, and it has an end extension portion 57 that extends the outer diameter toward the free end 54. Therefore, even when cantilevered and contact pressure is applied from one direction along the circumferential surface, the surface pressure is unlikely to concentrate in the area on the support end 53 side along the support axis a. Compared to a flat shape, the surface pressure is distributed along the axial direction a, resulting in higher uniformity of surface pressure from the support end 53 side to the free end 54 side. Therefore, even with long-term continuous use of the roller 50, uneven wear is unlikely to occur. Thus, it is easy to maintain the initial state of the roller 50, with its surface irregularities and other features designed to increase the coefficient of friction with the paper P, for a long period. As a result, it is possible to maintain a high coefficient of friction between the roller 50 and the paper P for a long time, making it difficult for poor paper P handling due to uneven wear to occur.

[0055] In the paper feeding device 1 described above, at least one of the supply roller 10 and the stop roller 20 may be the paper feeding roller 50 according to this embodiment, which has an end extension portion 57 (17, 27). Even when only one of the supply roller 10 and the stop roller 20 has an end extension portion 57, the uniformity of the surface pressure acting between the supply roller 10 and the stop roller 20 is improved by the help of the end extension portion 57, thus suppressing uneven wear on the surfaces of both the supply roller 10 and the stop roller 20. However, if both the supply roller 10 and the stop roller 20 are configured as rollers 50 according to this embodiment with end extension portions 57 (17, 27), the effect of suppressing uneven wear due to the improved surface pressure uniformity is further enhanced in both the supply roller 10 and the stop roller 20, which is preferable. In particular, when both the supply roller 10 and the deflection roller 20 are cantilevered, by configuring these two rollers as the roller 50 of this embodiment with end extensions 57 (17, 27), it is possible to improve the effect of suppressing the uneven distribution of surface pressure and uneven wear caused by the cantilever support.

[0056] In the paper feed roller 50 according to this embodiment, if an end extension portion 57 is provided on the free end 54 side, there are no particular limitations on the specific shape of the end extension portion 57 or the area where the end extension portion 57 is provided. As described above, the end extension shape of the end extension portion 57 can be a straight diameter expansion along the axial direction a toward the free end 54, or it can be an inwardly convex diameter expansion shape. However, from the viewpoint of improving the uniformity of surface pressure based on the end extension shape, an inwardly convex shape is preferred. Furthermore, an inwardly convex shape refers to a smooth, curved shape that convexes toward the inside of the paper feed roller 50, and does not include a step-like discontinuous change in the outer diameter along the axial direction a in the middle of the end extension portion 57, or a region that partially includes a region where the outer diameter does not change or a region that changes in an outwardly convex shape.

[0057] It was found that near the free end 54, the larger the outer diameter of the roller 50, the better the effect of homogenizing the surface pressure resulting from setting the end extension 57 on the roller 50. From the viewpoint that a larger variation in the outer diameter of the end extension 57 easily contributes to homogenizing the surface pressure, ... Figure 5 The arrangement shown preferably includes at least a region extending along axial direction a from the central portion 55, located at the center between the support end 53 and the free end 54, to the free end 54, forming an end extension 57. On the other hand, even if the end extension 57 is made too large, extending to the support end 53 side of the roller 50, the effect of increasing surface pressure homogenization may saturate, and further, the effect of dispersing surface pressure acting on the support end 53 side may actually decrease. From the viewpoint of avoiding such saturation and reduction of the surface pressure dispersion effect, it is preferable to limit the end extension 57 to a region extending along axial direction a from the central portion 55, or from a position closer to the free end 54 than the central portion 55, to the free end 54. The region where the end extension 57 is provided along axial direction a can be selected based on the desired degree of surface pressure homogenization, the specific size and material of the roller 50, etc. Furthermore, from the viewpoint of avoiding saturation and reduction of the surface pressure dispersion effect, such as... Figure 5 As shown, it is preferable to provide an end extension 57 along the axial direction a in the region on the free end 54 side, and on the other hand, to construct the roller 50 with a straight cylindrical portion 56 provided on the support end 53 side, and the end extension 57 and the straight cylindrical portion 56 smoothly joined together. Here, the straight cylindrical portion 56 is not limited to a completely straight cylindrical shape, as long as the change in outer diameter along the axial direction a is smaller than that of the end extension 57. When both the end extension 57 and the straight cylindrical portion 56 are provided on the roller 50, the end extension 57 is provided in the region on the free end 54 side, and the region closer to the support end 53 side is provided as the straight cylindrical portion 56. The region closer to the support end 53 side than the end extension 57 is preferably in a reverse convex shape (see reference). Figure 7 It does not extend toward the support end 53 in that way.

[0058] There is no particular limitation on the degree of variation in the outer diameter of the roller 50 in the end extension 57, and the following methods are preferred. Here, let the outer diameter of the section of the roller 50 orthogonal to the axial direction a be D1 at the support end 53, D2 at the central part 55, and D3 at the free end 54.

[0059] First, the difference (D3-D2) between the outer diameter D3 of the free end 54 and the outer diameter D2 of the central portion will be explained. When L1 < D3-D2, the lower limit L1 is preferably 0.05 mm. This means that the variation in the outer diameter of the end extension 57 is sufficiently large to effectively alleviate the localized surface pressure towards the support end 53 caused by providing the end extension 57 on the free end 54 side. A lower limit L1 of 0.075 mm or 0.10 mm is further preferred.

[0060] On the other hand, when D3-D2≤L2, the upper limit value L2 is preferably 0.50mm. This easily avoids the situation where the outer diameter of the end extension 57 changes too much, causing the surface pressure on the free end 54 side to become higher than that on the support end 53 side. It is even more preferable if the upper limit value L2 is 0.40mm or 0.30mm.

[0061] Next, the absolute value (|D2-D1|) of the difference between the outer diameter D2 of the central portion and the outer diameter D1 of the support end 53 will be explained. When |D2-D1| ≤ L3, the upper limit of the absolute value L3 is preferably 0.05 mm. This means that the variation in the outer diameter along the axial direction a is minimized at the support end 53 side of the roller 50, and the region on the support end 53 side of the roller 50 becomes a straight cylindrical portion 56 or a shape similar to it. In this way, the roller 50 excels at reducing the surface pressure acting on the region on the support end 53 side, thus achieving a uniform surface pressure. It is further preferred if the upper limit L3 is 0.04 mm or 0.03 mm. Because the smaller the difference between D2 and D1, the greater the help in uniformizing surface pressure, a lower limit is not set for the value of |D2-D1|. The most preferred configuration is D1 = D2; in other words, the straight cylindrical portion 56 is a straight cylinder.

[0062] The surface hardness of the roller 50, or in other words, the outer peripheral surface of the elastomer layer 52, according to JIS-A hardness measurement, is preferably 30 degrees or more. More preferably, it is 40 degrees or more, or 50 degrees or more. This easily suppresses wear on the surface of the roller 50. On the other hand, the surface hardness of the roller 50 is preferably 80 degrees or less according to JIS-A hardness measurement. More preferably, it is 70 degrees or less, or 65 degrees or less. This easily suppresses damage to the paper P caused by contact with the roller 50, such as scratching, and minimizes image quality degradation. The hardness of the roller 50 can be adjusted by the material composition of the elastomer layer 52, the thickness of the elastomer layer 52, etc.

[0063] In the paper feeding device 1, if only one of the supply roller 10 and the stop roller 20 is configured as the roller 50 of this embodiment with an end extension 57, or if both rollers 50 are configured as such, it is preferable that both the supply roller 10 and the stop roller 20 have a hardness within the aforementioned range. Furthermore, it is preferable that there is a difference between the surface hardness of the supply roller 10 and the surface hardness of the stop roller 20. If there is a difference in hardness, the surface of one roller will embed into the surface of the other roller, thereby easily increasing the coefficient of friction between the supply roller 10 and the stop roller 20. This improves the handling performance of the paper P (the pushing force in the handling direction p1 of the paper P). Preferably, the surface hardness of the stop roller 20 is higher than that of the supply roller 10. From the viewpoint of improving handling performance, the difference in surface hardness is preferably 5 degrees or more, measured in JIS-A hardness, and more preferably 10 degrees or more, or 15 degrees or more. On the other hand, from the viewpoint of easily suppressing the wear of the supply roller 10 and the retardation roller 20, the difference in surface hardness is preferably 50 degrees or less, and more preferably 40 degrees or less.

[0064] There are no particular limitations on the constituent materials of the roller 50 involved in this embodiment. For example, the elastomer layer 52 is preferably made of an elastomer containing polyurethane. The elastomer layer 52 contains polyurethane, thus providing excellent wear resistance during long-term use. The elastomer layer 52 may contain conductive agents and various additives. There are no particular limitations on the thickness of the elastomer layer 52, and it can be appropriately set within the range of 0.1 to 10 mm. The elastomer layer 52 preferably has surface irregularities on its outer peripheral surface. The surface irregularities can improve the coefficient of friction of the surface. The roller 50 has an end extension 57, which makes it difficult for surface irregularities caused by uneven wear to occur, and the resulting decrease in the coefficient of friction, thus maintaining a state in which the coefficient of friction is improved by the surface irregularities for a long time.

[0065] The elastomer layer 52 of the roller 50 can be formed using a polyurethane composition through molding based on a molding die. For example, by coaxially placing a shaft in the hollow portion of a roller forming die, injecting an uncrosslinked polyurethane composition, heating, curing (crosslinking), and demolding, an elastomer layer 52 is formed on the outer periphery of the shaft. As the molding die, the end extension 57 can be formed on the roller 50 by using a molding die having a shape on its inner circumferential surface corresponding to the end extension 57. In addition, the surface of the elastomer layer 52 can be provided with irregularities by pre-forming an irregular shape on the inner circumferential surface of the molding die.

[0066] Example

[0067] The present invention will now be described in detail using examples and comparative examples. Here, feed rollers and deflector rollers of various shapes were manufactured, and their surface pressure distribution and durability were evaluated.

[0068] [Sample Preparation]

[0069] Rollers of various shapes were fabricated as feed rollers and deceleration rollers. The shapes of the feed rollers and deceleration rollers are as follows: Figure 7 As shown, the rollers are designed with extended end shapes, flat shapes, raised shapes, and reverse raised shapes. For rollers with extended end shapes, multiple rollers with different outer diameters D1, D2, and D3 at the support end, central part, and free end are prepared.

[0070] When manufacturing the feed roller and the retaining roller, the mandrel (outer diameter) is... A through-hole is coaxially disposed in a mold having various predetermined shapes and an inner circumferential surface with an uneven structure. The openings at both ends are closed with cap-type bolts. After filling the molding space with an uncrosslinked thermosetting polyurethane polymer as the forming material for the elastomer layer, the molding mold is placed in an oven to complete crosslinking (150°C × 60 minutes). Then, an elastomer composed of a crosslinked and cured thermosetting polyurethane polymer is formed on the outer circumferential surface of the core mold. Afterward, the mold is demolded, and the elastomer is pulled out of the core mold and cut into 25mm lengths. The resulting elastomer is tubular (outer diameter as shown in Tables 1 and 2, inner diameter...). A 25mm long shaft was formed on its surface with irregularities. Next, a 27mm long, 10mm outer diameter shaft made of polyacetal (POM) was prepared. Then, the shaft was pressed into the hollow portion of the tubular elastomer. Through these operations, a supply roller and a retaining roller were manufactured. The surface hardness of the supply roller and the retaining roller was adjusted by the amount of plasticizer added to the polyurethane polymer.

[0071] [Evaluation Method]

[0072] (1) Evaluation of surface pressure distribution

[0073] With the above-prepared feed roller and retaining roller assembled via cantilever support in a commercially available copier with an FRR (Free-Rate Response) paper feeding system, the distribution of surface pressure acting between the feed roller and the retaining roller was measured. A pressure sensor plate was clamped between the feed roller and the retaining roller as a surface pressure measuring device, and the pressure was measured for every 1 mm. 2 A square grid is used to measure the surface pressure, thus evaluating the distribution of surface pressure. The pressure sensor sheet consists of rows and columns of electrodes arranged intersecting within a sheet approximately 1 mm thick. When pressure is applied to the sheet, the resistance changes. This change in resistance is converted into a pressure value and output.

[0074] In the obtained surface pressure distribution, for the row containing the maximum surface pressure in all measured data, the ratio was calculated by dividing the difference between the maximum and minimum surface pressure in that row by the load. A ratio below 3% was rated "A", above 3% but below 6% was rated "B", above 6% but below 10% was rated "C", above 10% but below 15% was rated "D", and above 15% was rated "E". Ratings of A, B, and C indicate sufficiently high uniformity in surface pressure distribution, while ratings of D and E indicate non-uniform surface pressure distribution.

[0075] Figure 8 The figure shows an example of evaluating surface pressure using the method described above. In the figure, the distribution of the measured surface pressure is represented by a darker grayscale color, indicating higher surface pressure. The horizontal axis of the figure represents the axial direction of the roller, showing the entire area of ​​the roller. Figure 8 In (a) of the figure, the distribution of surface pressure can be seen in the longitudinal direction, but no significant non-uniformity is observed in the transverse direction. This indicates that the surface pressure with higher uniformity acts along the axial direction of the roller. Correspondingly, the evaluation result for the uniformity of the surface pressure distribution is A, which is relatively high. On the other hand, in Figure 8 In (b) of the figure, the surface pressure exhibits a significant non-uniform distribution along the transverse direction. Specifically, a larger surface pressure is observed on the left side of the figure (support end side) than on the right side (free end side). In particular, the non-uniformity of the surface pressure along the transverse direction increases in the region from the middle left and right of the longitudinal direction to the bottom. Thus, in Figure 8 In (b), the surface pressure acting on the roller becomes uneven along the axial direction. Correspondingly, the evaluation result for the uniformity of the surface pressure distribution is also a D rating, which is low.

[0076] (2) Durability evaluation

[0077] The feed roller and deceleration roller manufactured above were assembled via cantilever support into a commercially available copier with an FRR (Free-Rate Flow) paper feeding system, and paper feeding performance was evaluated. Commercially available PPC paper was used, and 500,000 sheets were fed to determine the number of paper jams. The following categorization was used: zero paper jams ("A"), one to three paper jams ("B"), four to six paper jams ("C"), seven to ten paper jams ("D"), and eleven or more paper jams ("E"). Results of A, B, and C indicate sufficiently high durability, while results of D and E indicate relatively low durability.

[0078] [Evaluation Results]

[0079] Figure 7In this study, various shapes of paper feed rollers were used, and the evaluation results of roller shape (both the feed roller and the deflector roller were the same), surface pressure distribution, and durability were shown for Example 20 and Comparative Examples 1 to 3. In the shape diagram, the left side of the diagram is shown as the support end, and the right side is shown as the free end. In any shape, the JIS-A surface hardness is 60 degrees for the feed roller and 70 degrees for the deflector roller. Furthermore, in Tables 1 and 2, the shape, outer diameters D1, D2, and D3 of each roller, their correlation, surface hardness, and the evaluation results of surface pressure distribution and durability are summarized for all examples and comparative examples.

[0080] [Table 1]

[0081]

[0082] [Table 2]

[0083]

[0084] like Figure 7 As shown, in Comparative Example 1, where the supply roller and the retaining roller have a conventionally straight shape, the surface pressure exhibits an uneven distribution (Evaluation D). As a form of surface pressure distribution, the surface pressure is lower at the free end and higher at the support end, with a bias towards the support end. In contrast, in Example 20, where the supply roller and the retaining roller have an end-extended shape, the uniformity of the surface pressure distribution is higher (Evaluation A). As a form of surface pressure distribution, the bias towards the support end is mitigated, and the surface pressure gradually decreases from the support end towards the free end, resulting in improved uniformity of the surface pressure distribution along the axial direction compared to the straight shape. Corresponding to this improved uniformity of surface pressure distribution, the durability evaluation result is D (low) in the straight shape of Comparative Example 1, while it is A (high) in the end-extended shape of Example 20. Therefore, by forming an end extension on the free end side of the cantilevered paper feed roll, the surface pressure is dispersed and the uniformity of surface pressure distribution is improved compared to conventional paper feed rolls that are generally flat in shape. As a result, the durability of the paper feed roll is improved. This improvement in durability can be attributed to the suppression of uneven wear.

[0085] In the case of the raised shape in Comparative Example 2 and the reverse raised shape in Comparative Example 3, the uniformity of the surface pressure distribution further decreased compared to the flat shape (E rating). Regarding the surface pressure distribution pattern, in the case of the raised shape in Comparative Example 2, compared to the flat shape in Comparative Example 1, the area where the surface pressure is heavily distributed shifts towards the central part in the axial direction. In the case of the reverse raised shape in Comparative Example 3, the surface pressure decreases along the axial direction from the support end towards the vicinity of the central part. On the other hand, a complex surface pressure distribution is presented, where the surface pressure increases further towards the free end from the vicinity of the central part. However, in either case, the overall non-uniformity of the surface pressure distribution is higher than in the flat shape. Correspondingly, in either of Comparative Examples 2 and 3, the durability evaluation result is E rating, which is lower. Therefore, it can be said that even when the paper feed roller forms a raised shape or a reverse raised shape, unlike the case of forming an end-expanded shape, it does not have the effect of improving the uniformity of the surface pressure distribution and the resulting improvement in durability; on the contrary, the durability further decreases.

[0086] Furthermore, in the embodiments summarized in Tables 1 and 2, evaluation results of the uniformity and durability of the surface pressure distribution are shown for the combination of the shapes of the supply roller and the resisting roller, and for various variations in the outer diameter (D1, D2, D3) and hardness of each part. In any embodiment, at least one of the supply roller and the resisting roller has an end-extended shape. Moreover, in any embodiment, a high uniformity and durability of the surface pressure distribution, rated C or higher, is obtained.

[0087] First, regarding the combination of the shapes of the supply roller and the resisting roller, in Examples 1, 6-19, and 28-30, only the resisting roller has an extended end shape, while the supply roller has a straight shape. In Examples 2-5, conversely, only the supply roller has an extended end shape, while the resisting roller has a straight shape. In Examples 20-27, both the supply roller and the resisting roller have extended end shapes. For these three combinations, comparing cases where the outer diameters (D1, D2, D3) of each part of the roller with the extended end shape are the same and the hardness of the two rollers is the same (for example, comparing Examples 2, 6, and 21), the surface pressure distribution and durability all yielded almost identical evaluation results. Therefore, it can be said that if at least one of the supply roller and the resisting roller is pre-set to have an extended end shape, high surface pressure uniformity and durability can be obtained even if either one has an extended end shape.

[0088] In Examples 1, 6-12, Examples 2-5, and Examples 20-23, the outer diameter difference D3-D2 and the value of |D2-D1| of the rollers with extended end shapes are all different. Comparing the evaluation results of these groups, Examples 1-9 and 20-23, where |D2-D1|≤0.05mm and 0.05mm<D3-D2≤0.50mm, tend to achieve higher uniformity and durability of surface pressure. In particular, Examples 1 and 20, where |D2-D1|≤0.00mm, in other words, D1=D2, and D3-D2≤0.40mm, achieve excellent uniformity and durability of surface pressure, receiving an A rating.

[0089] Compared with Example 1, Examples 28-30 have different absolute values ​​of outer diameters (D1, D2, D3), while the diameter differences |D2-D1| and D3-D1 are the same. In each of these Examples 28-30, the same A-level uniformity and durability of surface pressure as in Example 1 are obtained. Based on this result, it can be said that as long as at least one of the supply roller and the deflection roller is designed with an extended end shape, and the roller with the extended end shape is pre-designed in a manner that satisfies |D2-D1|≤0.05mm and 0.05mm<D3-D2≤0.50mm regardless of the absolute value of the outer diameter of each roller, high uniformity and durability of surface pressure can be obtained.

[0090] In Examples 1, 13-19, and Examples 20, 24-27, the surface hardness of the supply roller and / or the resistive roller is different. In these examples, the hardness of both the supply roller and the resistive roller, measured by JIS-A hardness, is in the range of 30 degrees or more and 80 degrees or less, and a high uniformity and durability of surface pressure distribution with a rating of C or higher is obtained. Among them, in Examples 1, 13, 16, 17, 20, 24, and 27, where the hardness of the resistive roller is higher than that of the supply roller, and the difference is 5 degrees or more when measured by JIS-A hardness, a high uniformity of surface pressure distribution with a rating of B or higher and excellent durability with a rating of A are obtained.

[0091] The embodiments and examples of the present invention have been described above. However, the present invention is not limited to the above embodiments and examples, and various changes can be made without departing from the spirit of the present invention.

Claims

1. A paper feeding roller (50) having a shaft (51) and an elastomer layer (52) formed on the outer periphery of the shaft (51), wherein the paper feeding roller (50) of the paper feeding device (1) rotates about a rotating shaft (5A), wherein, The paper feeding roller (50) has a cantilever support structure that allows the shaft (51) to be supported at one end by the paper feeding device (1). The elastomer layer (52) has at both ends along the rotation axis (5A): a support end (53), which is the end on the side where the shaft (51) is supported by the paper feeding device (1); and a free end (54), which is the end on the side where the shaft (51) is not supported by the paper feeding device (1). The outer diameter of the cross section of the elastomer layer (52) orthogonal to the rotation axis (5A) is larger at the free end (54) than at the support end (53). The paper feeding roller (50) has an end extension (57) in the region including the free end (54), which is formed by the outer diameter becoming more linear or convex as it extends along the rotation axis (5A) toward the free end (54).

2. The paper feeding roller (50) according to claim 1, wherein, The end extension (57) is formed along the rotation axis (5A) and includes at least a region extending from the center between the support end (53) and the free end (54) to the free end (54).

3. The paper feeding roller (50) according to claim 1 or 2, wherein, The elastomer layer (52) has a straight cylindrical portion (56) at a position relative to the support end (53) along the rotation axis (5A) and in a continuous manner with respect to the end extension (57), with a smaller change in the outer diameter along the rotation axis (5A) than that of the end extension (57).

4. The paper feeding roller (50) according to claim 1 or 2, wherein, Let the outer diameter of the cross section of the elastomer layer (52) orthogonal to the rotation axis (5A) be D1 at the support end (53), D2 at the center position between the support end (53) and the free end (54) along the rotation axis (5A), and D3 at the free end (54). Then |D2-D1|≤0.05mm, and 0.05mm < D3 - D2 ≤ 0.50mm.

5. The paper feeding roller (50) according to claim 1 or 2, wherein, The JIS-A hardness of the surface of the elastomer layer (52) is above 30 degrees and below 80 degrees.

6. A paper feeding device (1), wherein, The paper feeding device (1) includes: The supply roller (10) is driven to rotate and transport the paper (P); and A deceleration roller (20) is pressed against the feed roller (10) and is provided for mounting a torque limiter to suppress the stacking of the paper (P). At least one of the supply roller (10) and the deceleration roller (20) is configured as a paper feeding roller (50) according to any one of claims 1 to 5.

7. The paper feeding device (1) according to claim 6, wherein, Both the supply roller (10) and the deceleration roller (20) are configured as the paper supply roller (50) according to any one of claims 1 to 5.

8. The paper feeding device (1) according to claim 6 or 7, wherein, In both the supply roller (10) and the retardation roller (20), the JIS-A hardness of the surface of the elastomer layer is above 30 degrees and below 80 degrees.

9. The paper feeding device (1) according to claim 6 or 7, wherein, The surface hardness of the elastomeric layer of the retardation roller (20), measured by JIS-A hardness, is at least 5 degrees greater than the surface hardness of the elastomeric layer of the supply roller (10).

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