JP4181966B2 - Feed roller and sheet separating member - Google Patents

Description

  The present invention relates to a feeding roller for feeding sheets and a sheet separating member that separates a plurality of sheets to be fed.

  Conventionally, various image forming apparatuses such as an electrophotographic copying machine, a printer, and a fax machine are provided with a feeding unit for feeding a sheet such as a sheet or a transparent sheet. The feeding unit has a wide configuration in which a sheet is nipped and fed by a feeding roller and a sheet support plate biased by the feeding roller, and a configuration in which the sheet is nipped between a pair of rollers rotating in the opposite direction and fed. It has been adopted.

  FIG. 17 shows an example of a feeding unit of a conventional image forming apparatus. FIG. 17A is a diagram illustrating a state in which a sheet (transfer material or the like) is not stored in the feeding unit, and FIG. 17B is a diagram illustrating a state in which the sheet is stored in the feeding unit.

  17A includes a feed roller 200, a feed cassette 201, a sheet support plate 202, a pressure spring 203, a separation member 204, a final sheet separation sheet 205, a sheet detection arm 206, and a photo interrupter. 207.

  In the sheet storage state shown in FIG. 17B, the sheet bundle stacked on the sheet support plate 202 of the feeding cassette 201 is pressed against the outer peripheral surface of the feeding roller 200 by the elastic biasing force of the pressure spring 203. Yes. Further, the sheet detection arm 206 is lifted with its free end in contact with the sheet to block the optical path of the photo interrupter 207. As a result, the photo interrupter 207 detects a state in which the sheet is stored in the feeding cassette 201.

  During the feeding operation, the feeding roller 200 rotates counterclockwise in the drawing, and the sheet bundle pressed against the feeding roller 200 on the sheet support plate 202 is taken out one by one from the uppermost sheet. Transport right. Here, when the upper two or more sheets are taken out together from the sheet bundle, the separating member 204 located on the downstream side of the nip portion between the feeding roller 200 and the sheet support plate 202 is taken out together. In addition, the lower surface of each of the plurality of sheets is frictionally engaged to suppress conveyance of the lower sheet. As a result, the sheets are reliably conveyed one by one. As a method for stopping the lower sheet when a plurality of sheets are taken out, a configuration in which a retard roller that rotates in the direction opposite to the conveying direction is installed on the downstream side of the feeding roller 200 is also known.

  In the above-described configuration, the feed roller 200 and the separation member 204 generally use a friction separation mechanism that uses a rubber material for each surface (friction surface). In this case, for example, when the friction coefficient between the sheets is 0.4 to 0.7, the friction coefficient between the surface of the separation member 204 and the sheet is 0.9 to 1.1, and between the outer peripheral surface of the feeding roller 200 and the sheet. The friction coefficient is set to a value of 1.5 or more.

  In the above-described configuration, the feed roller 200 and the separation member 204 generally use a friction separation mechanism that uses a rubber material for each surface (friction surface). In this case, for example, when the friction coefficient between the sheets is 0.4 to 0.7, the friction coefficient between the surface of the separation member 204 and the sheet is 0.9 to 1.1, and between the outer peripheral surface of the feeding roller 200 and the sheet. The friction coefficient is set to a value of 1.5 or more (see, for example, Patent Document 1).

JP 2001-163464 A

  However, the conventional feeding unit has the following problems.

First, when feeding thick paper with a weight of about 200 g / m ² , a large feed force is required, so the drive motor for the feed roller 200 needs to have a large capacity, and the friction against the separating member 204 is excessive. It becomes easy to generate an unusual sound called “squeal”. In addition, when the feeding force is set for a thick paper having a weight of about 200 g / m ² , if a thin paper having a weight of about 60 g / m ² is sent, a plurality of thin papers are sent together, and the separation member 204 A phenomenon of simultaneous feeding of a plurality of sheets called “multiple feeding” that is difficult to separate easily occurs.

  In addition, the rubber material on the surface of the feed roller 200 and the separation member 204 may be softened or hardened due to environmental fluctuations, or may be worn due to long-term use. Concerned. In addition, the driving source of the feeding roller 200 is required to set a driving force having a sufficient margin with respect to the required torque in consideration of application to cardboard and deterioration with time.

  Therefore, the present invention demonstrates a feed roller that can exhibit good feed performance over a long period of time regardless of the sheet thickness (weight) and type (OHT, glossy paper, etc.), and good separation performance. The object is to provide a sheet separating member to be obtained.

In order to solve the above-described problem, a typical configuration according to the present invention is a feeding roller in which an elastic body layer is formed on an outer periphery of a shaft body. The elastic body layer includes a base portion and a surface of the base portion. A plurality of fine projections each having a three-dimensional projecting shape, wherein the base portion and the projection portion are integrally formed of the same elastic material , and 3 of the plurality of projection portions. There are at least two kinds of dimensional projecting shapes, and the protrusions are brought into frictional contact with the sheet at their respective tips, and the sheet is fed by rotation of the shaft.

  As described above, according to the present invention, regardless of the thickness (weight) and type (OHT, glossy paper, etc.) of the sheet, It is possible to provide a sheet separating member that can exhibit good separation performance over time.

[First embodiment]
A first embodiment of a feeding roller and a sheet separating member according to the present invention will be described. First, the entire image forming apparatus will be described with reference to FIG. 16, and then the feeding roller according to the present embodiment will be described.

  FIG. 16 is a diagram illustrating the overall configuration of the image forming apparatus. In the image forming apparatus 100 shown in the drawing, the intensity of laser light from the laser scanner 101 is modulated based on an image signal sent from a host computer (not shown) during printing, and an electrostatic latent image is formed on the photosensitive drum 102. An image is formed. On the other hand, the sheets in the feeding cassette 2 are taken out one by one by the feeding roller 10 and the separating member 5 and then conveyed toward the photosensitive drum 102 by the conveying roller 103 and at the writing timing by the registration roller 104. Will be adjusted. Then, the toner image on the photosensitive drum 102 is transferred to the sheet by the transfer roller 105. After that, the toner image becomes a permanently fixed image on the sheet through the conveyance belt 106 and the fixing device 107, and is finally discharged onto the tray 109 outside the apparatus by the discharge roller 108 and stacked.

  Next, the feeding roller 10 will be described. FIG. 1 is a diagram for explaining the configuration of a feeding roller, FIG. 2 is a diagram for explaining a projection, FIG. 3 is a diagram for explaining the shape of the projection, and FIG. 4 is a diagram for explaining a state in which an adhesive layer is provided. 5 is a diagram illustrating the feeding unit, FIGS. 6 and 7 are diagrams illustrating the behavior of the protrusions of the feeding roller during the feeding operation, and FIG. 8 is a feeding during the feeding operation when durability is advanced. It is a figure explaining the behavior of the projection part of a roller.

  As shown in FIG. 1, the feeding roller 10 includes a shaft body 12 and an elastic body layer 14 provided on the outer periphery of the shaft body 12. The shaft body 12 has a cylindrical support portion 16 having a cylindrical outer peripheral surface 16a and a pair that extends integrally from both axial end surfaces of the support portion 16 in the axial direction and defines the rotation axis 12a of the shaft body 12. The shaft portion 18 is provided. The elastic body layer 14 is formed of an elastic member separate from the shaft body 12, and is attached to the outer peripheral surface 16a so as to follow the outer peripheral surface shape of the support portion 16 of the shaft body 12.

  The elastic body layer 14 includes a base portion 20 and a plurality of protrusion portions 22 that are finely processed on the surface 20a of the base portion 20 and each have a three-dimensional protruding shape. As shown in FIG. 2 in an enlarged manner, each of the protrusions 22 (microfabrication elements) includes leg portions 22a1 and 22a2 standing upright on the surface 20a of the base portion 20, and leg portions 22a1 and 22a2. It has a mushroom shape integrally provided with heads 22b1 and 22b2 bulging at the tip. In this case, the leg portions 22a1 and 22a2 of each projection 22 can have various shapes such as a column shape and a cone shape.

  The column shape here means a shape having a substantially constant cross section in the height (length) direction of the leg portion 22a. In addition, as shown in FIG. 3 (a), the pyramidal shape means a cross sectional area a1 of the leg 22a at a position close to the head 22b and a cross sectional area a2 of the leg 22a at a position away from the head 22b. Means a shape in which corresponding portions on the outer peripheral edge of the cross section at those positions are connected by a gentle curve or straight line. Further, the head portion 22b of each protrusion 22 is not limited to a mushroom shape such as a spherical shape, a hemispherical shape, or a disc shape (see FIG. 3B), and is disclosed in, for example, International Patent Publication No. 00/20210 pamphlet. Moreover, it can also be set as the upright pillar shape (refer FIG.3 (c)) which does not have a bulging head.

The plurality of protrusions 22 are provided on the surface 20a of the base portion 20 with a spatial arrangement density of 15.5 pieces / cm ² or more, and each protrusion 22 has a height H of 0.254 mm to 1.27 mm and a height of 0.076 mm to 0.76. It is advantageous to have a transverse maximum dimension D of mm under the condition of aspect ratio H / D ≧ 1.25. As an example, each protrusion 22 includes a columnar leg 22a1 having a diameter of 250 μm and a height of 480 μm, a columnar leg 22a2 having a diameter of 250 μm and a height of 280 μm, and a diameter D1 (D1 = D2) (that is, a transverse direction). (Maximum dimension) 300 μm hemispherical heads 22b1 and 22b2. Therefore, the height of H1 is 430 μm, and the height of H2 is 630 μm. In this case, the plurality of protrusions 22 are provided on the surface 20a of the base portion 20 with a spatial arrangement density of 465 / cm ² . Each protrusion 22 is installed so that the flat lower surface region of the heads 22b1 and 22b2 is substantially parallel to the base surface 20a of the elastic layer 14 in a state where the legs 22a1 and 22a2 are not bent. The In this embodiment, the leg portions 22a1 and 22a2 are set to an occupation ratio of 1: 1, but the spatial arrangement density in the area can be arbitrarily changed according to the above conditions. An example of the dimensions of an upright columnar projection having no bulging head is disclosed in International Patent Publication No. 00/20210 pamphlet.

  The base 20 and the plurality of protrusions 22 of the elastic layer 14 can be integrally formed from the same elastic material. The elastic body layer 14 can be composed of an elastic member made of a seamless (endless) hollow cylindrical member. In this case, the elastic body layer 14 can be fixed to the outer peripheral surface 16a of the support portion 16 of the shaft body 12 by the frictional force and the elastic restoring force of the elastic member itself. Alternatively, the elastic body layer 14 can be formed of an elastic member made of a plate-like member. In this case, the elastic body layer 14 can be fixed to the outer peripheral surface 16a of the support portion 16 of the shaft body 12 via the adhesive layer 24 (see FIG. 4). As the adhesive layer 24, an adhesive or a double-sided adhesive tape can be used.

  For example, the base portion 20 of the elastic body layer 14 is made of the same ether-based urethane rubber as the plurality of protrusions 22 and is made of a hollow cylindrical member or plate-like member having a thickness of 0.2 mm and a Shore A hardness of 70. The support portion 16 and the shaft portion 18 of the shaft body 12 are integrally molded from the same plastic material. The support portion 16 is a cylindrical body having a diameter of 25 mm and an axial length of 30 mm, and the shaft portion 18 is a cylinder having a diameter of 9 mm. Consists of the body. As materials used for the elastic layer 14, natural rubber, ethylene-propylene rubber (EPM), ethylene-propylene-diene rubber (EPDM), styrene-butadiene rubber (SBR), butyl rubber (IIR), silicon rubber, Examples thereof include urethane rubber.

  FIG. 5 is a schematic view showing a feeding unit equipped with the feeding roller 10 described above. The feeding unit shown in FIG. 5 includes a feeding roller 10, a feeding cassette 2, a sheet support plate 3, a pressure spring 4, a separation member 5, a final paper separation sheet 6, a sheet detection arm 7, and a photo interrupter 8. ing. FIG. 5 shows a state in which a plurality of sheets are stacked and mounted on the sheet support plate 3 of the feeding cassette 2.

  The feeding operation of the illustrated feeding unit will be described with specific numerical examples. For example, in accordance with an image forming signal output from a controller unit (not shown), the feeding roller 10 rotates at a peripheral speed of 120 mm / s in the counterclockwise direction shown in the drawing, and on the sheet support plate 3 pressed against the feeding roller 10. The top sheets of the sheet bundle are sequentially taken out one by one and fed in the right direction in the figure. At this time, the uppermost sheet on the sheet support plate 3 is pressed against the feeding roller 10 by the pressure spring 4 with a force of about 3N to 3.5N. The shaft body 12 rotates while the plurality of protrusions 22 (see FIG. 2) on the elastic layer 14 installed on the outer periphery of the feeding roller 10 are in frictional contact with the sheet at the heads 22b at the respective ends. To feed the sheet.

  Here, when the upper two or more sheets are taken out together from the sheet bundle, the separating member 5 located on the downstream side of the nip portion between the feeding roller 10 and the sheet support plate 3 is taken out together. The lower sheets are frictionally engaged with the lower ends of the plurality of sheets to suppress the conveyance of the lower sheets. As a result, the sheets are reliably conveyed one by one. The feeding roller 10 rotates until the sheet reaches the downstream conveying roller 11, and then the sheet is conveyed in a predetermined direction by the conveying roller 11 and a downstream mechanism (not shown).

6 and 7 show the behavior of the protrusion 22 of the feeding roller 10 during the feeding operation described above in relation to sheets having different thicknesses (sheets). The sheet P1 shown in FIG. 6 is a thin paper having a weight of 60 g / m ² as an example, and the friction coefficient between the two thin papers is μ1. Further, the sheet P2 shown in FIG. 7 is a thick paper having a weighing of 200 g / m ² as an example, and the friction coefficient between the two thick papers is set to μ2 larger than μ1.

  As the feed roller 10 rotates, the plurality of protrusions 22 on the elastic layer 14 move in the arrow α direction. At this time, the plurality of sheets are pressed against the plurality of protrusions 22 on the elastic body layer 14 by the spring biasing force F of the pressure spring 4, and these protrusions 22 are formed between the fibers of the sheets by the respective heads 22b1. Embedded at least partially.

  Regarding the sheet P1, the friction coefficient μ1 between the sheets P1 is about 0.5, and the frictional force between the heads 22b1 of the plurality of protrusions 22 and the sheet P1 easily and sufficiently exceeds the frictional force between the sheets P1. become. As a result, the plurality of projecting portions 22 are not substantially deformed by the leg portions 22a1, and the respective heads 22b1 are embedded between the fibers of the sheet P1 in the apex region thereof, and the upper end sheet P1. Is stably sent in the direction of arrow β (≈arrow α). Further, the short leg portion 22a2 and its head portion 22b2 do not contribute to the conveyance, and the leg portion 22a2 and the head portion 22b2 are not deformed.

  On the other hand, with respect to the sheet P2, the friction coefficient μ2 between the sheets P2 is as large as about 0.7, and the frictional force between the heads 22b1 of the plurality of protrusions 22 and the sheet P2 is somewhat the frictional force between the sheets P2. It will be higher. As a result, in each of the plurality of protrusions 22, the leg portion 22a1 is elastically bent, and each head portion 22b1 is embedded deeper between the fibers of the sheet P2 in the edge region. In this state, a sufficient frictional force is secured between the heads 22b1 of the plurality of protrusions 22 and the sheet P2, and the upper end sheet P2 is stably fed in the direction of arrow β (≈arrow α). Also in this case, the short leg portion 22a2 and its head portion 22b2 do not contribute to the conveyance, and the leg portion 22a2 and the head portion 22b2 are not deformed.

FIG. 8 shows the behavior of the protrusion 22 of the feeding roller 10 during the feeding operation when the durability is advanced (specifically, for example, after passing about 50,000 sheets). The sheet P3 shown in FIG. 8 is, for example, paper having a basis weight of 75 g / m ² , and the friction coefficient between the two thin papers is μ3, and the friction coefficient between the two papers is μ3.

  As the feed roller 10 rotates, the plurality of protrusions 22 on the elastic layer 14 move in the arrow α direction. At this time, the head portion 22b1 (not shown) of the leg portion 22a1 does not retain its original shape due to wear due to durability, and has a shape that leaves only the leg portion 22a1. On the other hand, the short leg portion 22a2 and its head portion 22b2 that were not involved in the conveying operation in the initial stage maintain a sufficient frictional force with the sheet P3, and the upper end sheet P3 is in the direction of arrow β (≈arrow α). Is sent out stably.

  In the above configuration, the shape, size, and hardness of each protrusion 22 corresponding to the physical properties such as thickness (weighing), type (OHT, glossy paper, etc.), friction coefficient, etc. of the sheets P1, P2, and P3 to be fed. By changing variously, it is possible to ensure an optimum frictional force for the sheets P1, P2, and P3 from the initial state of the feeding roller until reaching the set durable number. Therefore, according to the feeding roller 10, by appropriately adjusting the shape, size, hardness, and the like of the plurality of protrusions 22 formed on the elastic layer 14, the above-described “heavy load” caused by excessive feeding pressure on the thin paper is achieved. It is possible to effectively suppress the above-mentioned “squeaking” phenomenon caused by insufficient feeding force for cardboard, and the decrease in feeding force caused by scraping due to durability. Regardless of the physical properties such as the thickness (weight) of the (sheet), the type (OHT, glossy paper, etc.), the coefficient of friction, etc., it is possible to exhibit good feeding performance over a long period of time. In addition, by using a mechanism that appropriately controls the friction coefficient according to the elastic deformation characteristics of the plurality of protrusions 22 as described above, it is possible to control the clamping pressure and the feeding speed during sheet feeding, the physical properties of the feeding roller 10 and the separating member 5, and the like. However, it is possible to reduce the accuracy of the detailed setting that has been conventionally performed, and to reduce the production cost.

  The configuration of the feeding roller 10 described above is not limited to the application to the feeding roller of the feeding unit as in the illustrated embodiment, but can also be applied to the conveying roller of the sheet conveying mechanism.

[Second Embodiment]
A second embodiment of the feeding roller and the sheet separating member according to the present invention will be described. FIG. 9 is a diagram for explaining a feeding roller according to the present embodiment, FIG. 10 is a diagram for explaining a feeding unit, and FIG. 11 is a diagram for explaining another configuration of the feeding roller. The same reference numerals are given to the overlapping parts and the description will be omitted.

  The feeding roller 30 shown in FIG. 9 differs from the feeding roller 10 shown in the first embodiment mainly in the configuration of the shaft. The feeding roller 30 includes a shaft body 32 and an elastic body layer 14 provided on the outer periphery of the shaft body 32. The shaft body 32 has a cylindrical support portion 34 having a deformed outer peripheral surface 34a, and a pair of axially extending from both end surfaces in the axial direction of the support portion 34 to define the rotation axis 32a of the shaft body 32. And a shaft portion 36. The elastic body layer 14 is formed of an elastic member separate from the shaft body 32, and is attached to the outer peripheral surface 34a so as to follow the outer peripheral surface shape of the support portion 34 of the shaft body 32.

  The shaft body 32 has an outer peripheral surface 34a of the support portion 34 extending inside the virtual cylindrical surface including the main region 38 and the main region 38 extending in an arc shape over an arbitrary central angle around the rotation axis 32a. And a plurality of substantially flat sub-regions 40 connected to the main region 38. The elastic member forming the elastic layer 14 is attached to the entire deformed outer peripheral surface 34a of the shaft body 32 including the main region 38 and the plurality of sub-regions 40, and has a plurality of protrusions at positions corresponding to at least the main region 38. 22 is provided.

  As a preferred embodiment, the support portion 34 and the shaft portion 36 of the shaft body 32 are integrally molded from the same plastic material. The support portion 34 has a composite shape in which a semi-cylindrical body having a diameter of 25 mm, an axial length of 30 mm, and a central angle of 170 ° is combined with a quadrangular prism body having an isosceles trapezoidal cross section with a base of 25 mm. The shaft portion 36 is a cylindrical body having a diameter of 9 mm. In this configuration, the elastic member forming the elastic body layer 14 is preferably formed of a cylindrical member that can be in close contact with the entire deformed outer peripheral surface 34a of the shaft body 32 by its own elastic restoring force. Alternatively, when the elastic body layer 14 is formed of a plate-like member, it is preferable that the edge of the elastic body layer 14 is disposed at a position corresponding to the sub region 40 of the support portion 34 of the shaft body 32.

  FIG. 10 is a schematic view showing a feeding unit equipped with the feeding roller 30 described above. The feeding unit shown in FIG. 10 includes a feeding roller 30, a feeding cassette 2, a sheet support plate 3, a pressure spring 4, a separating member 5, a final paper separating sheet 6, a sheet detecting arm 7, and a photo interrupter 8. ing. FIG. 10 shows a state where a plurality of sheets are stacked and mounted on the sheet support plate 3 of the feeding cassette 2.

  The feeding operation of the illustrated feeding unit will be described with specific numerical examples. In this configuration, when the sheet is not being fed, the feeding roller 30 has a polygonal area (area corresponding to the plurality of sub-areas 40 on the outer circumferential surface 34a) of the elastic layer 14 installed on the outer periphery thereof. It is arranged at a rotational position facing the sheet bundle on the support plate 3. From this standby position, for example, according to an image forming signal output from a controller unit (not shown), the feeding roller 30 rotates once in the counterclockwise direction at a peripheral speed of 120 mm / s and stops. During this time, the sheet bundle on the sheet support plate 3 is added to the cylindrical region (the region corresponding to the main region 38 of the deformed outer peripheral surface 34a) of the elastic layer 14 installed on the outer periphery of the feeding roller 30 at a predetermined rotational position. It is pressed under the urging force of the pressure spring 4. Then, in the same manner as the operation described with reference to FIGS. 5 to 7, the uppermost sheet of the sheet bundle pressed against the feeding roller 30 is taken out and fed rightward in the drawing.

  Preferably, at least the front end portion of the sheet taken out from the sheet support plate 3 reaches the conveying roller 11 by the one rotation of the feeding roller 30. Thereafter, the sheet is conveyed in a predetermined direction by the conveyance roller 11 and a downstream mechanism (not shown). The feeding roller 30 is placed in a stopped state until the trailing edge of the fed sheet passes through the separation member 5. When a plurality of sheets are continuously fed, the feeding roller 30 rotates once again after the trailing end of the sheet has passed through the separating member 5.

  In the above configuration, since the elastic body layer 14 of the feeding roller 30 is in contact with the sheet only in its cylindrical region (the region corresponding to the main region 38 of the deformed outer peripheral surface 34a), the stress on the sheet surface can be reduced. There is an advantage that the rotational torque of the feeding roller 30 can be reduced.

  When the shaft body 32 having the support portion 34 having the above-described deformed outer peripheral surface 34a is used as a feeding roller, as shown in FIG. 11A, only the main region 38 of the support portion 34 has a plate shape. The elastic body layer 14 made of a member can be fixedly installed via the adhesive layer 24 (see FIG. 3). Further, as shown in FIG. 11B, the shaft body 44 having the odd-shaped support portion 42 composed of a plurality of main regions 46 is also composed of a plate-like member only in the plurality of main regions 46 of the support portion 42. The elastic layer 14 can be fixed individually. In any of the feeding rollers, the sheet feeding function is exhibited in the region of the elastic layer 14 having the plurality of protrusions 22.

[Third embodiment]
A third embodiment of the feeding roller and the sheet separating member according to the present invention will be described. FIG. 12 is a diagram for explaining the sheet separating member according to the present embodiment, FIG. 13 is an enlarged view for explaining the protruding portion, and FIG. 14 is a diagram for explaining the separation operation, which overlaps with the first embodiment. Parts are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 12, in this embodiment, the separation member 50 (sheet separation member) includes a support body 52 and an elastic body layer 54 provided on a substantially flat surface 52 a of the support body 52. The support 52 is integrally formed with, for example, an attachment portion 56 for mounting on the main body of the image forming apparatus, a spring receiving portion (not shown) for supporting the separation pressure spring, and the like. The elastic body layer 54 is formed of an elastic member separate from the support body 52, and is fixedly attached to the surface 52a of the support body 52 via, for example, an adhesive layer.

  As shown in FIG. 13, the elastic layer 54 includes a base portion 58 and a plurality of fine protrusions 60 formed on the surface 58a of the base portion 58, each having a three-dimensional protruding shape. Each of the protrusions 60 is integrally provided with leg portions 60a1 and 60a2 standing upright on the surface 58a of the base portion 58, and head portions 60b1 and 60b2 bulging at the tips of the leg portions. Has a mushroom shape. In this case, the leg portions 60a1 and 60a2 of each protrusion 60 can have various shapes such as a column shape and a cone shape. Further, the heads 60b1 and 60b2 of each protrusion 60 can have various shapes such as a spherical shape, a hemispherical shape, and a disc shape. However, the shape of each protrusion is not limited to the illustrated mushroom shape, and may be an upright column shape having no bulging head as disclosed in, for example, International Patent Publication No. 00/20210.

The plurality of protrusions 60 are provided on the surface 58a of the base 58 with a spatial arrangement density of 15.5 pieces / cm ² or more, and each protrusion 60 has a height H of 0.254 mm to 1.27 mm and a height of 0.076 mm to 0.76. It is advantageous to have a transverse maximum dimension D of mm under the condition of aspect ratio H / D ≧ 1.25. As an example, each protrusion 60 has two types of legs, ie, a cylindrical leg 60a1 having a diameter of 250 μm and a height of 480 μm, and a cylindrical leg 60a2 having a diameter of 250 μm and a height of 300 μm. (Maximum dimension in the transverse direction) Spherical heads 60b1 and 60b2 of 300 μm. In this case, the plurality of projecting portions 60 are provided on the surface 58a of the base portion 58 at a spatial arrangement density of 465 / cm ² . An example of the dimensions of an upright columnar projection having no bulging head is disclosed in International Patent Publication No. 00/20210 pamphlet.

  The base 58 and the plurality of protrusions 60 of the elastic layer 54 can be integrally formed from the same elastic material. For example, the base portion 58 of the elastic layer 54 is made of the same ether-based urethane rubber as the plurality of protrusions 60, and is made of a plate-like member having a thickness of 0.2 mm and a Shore A hardness of 90. The support body 52 is integrally molded from a plastic material as a whole. As materials used for the elastic layer 54, natural rubber, ethylene-propylene rubber (EPM), ethylene-propylene-diene rubber (EPDM), styrene-butadiene rubber (SBR), butyl rubber (IIR), silicon rubber, Examples thereof include urethane rubber.

  As an example, a sheet separating operation when the separating member 50 according to this embodiment is used instead of the separating member 204 of the feeding unit shown in FIG. 17 will be described with reference to FIG. When the upper two sheets (sheets) P4 and P5 are taken together from the sheet bundle by the feeding roller 10, the upper sheet P4 has a force corresponding to the friction coefficient μ4 with respect to the outer peripheral surface of the feeding roller 1. Are sent in the direction of arrow β. On the other hand, the lower sheet P5 is held on the separation member 50 with a force corresponding to the friction coefficient μ4 with respect to the head 60b1 of the plurality of protrusions 60 provided on the elastic body layer 54 of the separation member 50.

  Here, when the friction coefficient between the sheets P4 and P5 is larger than μ4, the lower sheet P5 tends to move in the arrow β direction together with the upper sheet P4. At this time, the front end of the sheet P5 collides with the heads 60b1 and 60b2 while receiving frictional resistance on the heads 60b1 and 60b2 of some protrusions 60. As a result, the sheet P5 receives a resistance force in the feeding direction by the protrusion 60, and as a result, is held on the separation member 50. At this time, in the initial durability state, the sheet P5 is separated due to the frictional resistance with the tall head 60b1 being dominant, but as the durability progresses, the tip of the head 60b1 wears out, and eventually the head 60b2 The frictional resistance is dominant and separated. When the heads 60b1 and 60b2 of the protrusion 60 are square, the resistance to the front end of the sheet becomes excessive, and a so-called “edge folding” phenomenon in which the front end portion of the sheet turns up or down with respect to the feeding direction occurs. There is a concern that it may occur or paper dust may adhere to the protrusion 60. Therefore, it is advantageous that the heads 60b1 and 60b2 of the protrusion 60 have a smooth outer surface shape.

  According to the separation member 50 having the above configuration, the sheet (sheet) to be fed has a thickness (weight), type (OHT, glossy paper, etc.), friction coefficient, based on the same principle as the feeding rollers 10 and 30 described above. Regardless of the physical properties such as the above, it is possible to exhibit good sheet separation performance over a long period of time.

  Note that the separation member 50 according to the present embodiment can also be used in combination with the feeding rollers 10 and 30 shown in the first and second embodiments. In any case, the feeding unit according to the present invention configured in this way has a friction coefficient between the friction feeding surface of the feeding roller and the sheet μa, and a friction coefficient between the friction braking surface of the sheet separating member and the sheet. Is μb, and the friction coefficient between two sheets is μc, the condition is that μa> μb> μc.

[Other Embodiments]
With reference to FIG. 15, another embodiment of the feeding roller and the sheet separating member according to the present invention will be described.

FIG. 15A is a view in which a conical protrusion 22c1 is further provided at the tip of the mushroom-shaped protrusion 22 shown in the first embodiment. The conical protrusion 22c1 has a bottom area of 4π μm ² and a height of 5 μm, and is located at the tip of the head 22b. The conical protrusion 22c1, the head portion 22b, and the leg portion 22a can be integrally formed from the same elastic material. The protrusion 70 shown in FIG. 15B has a shape in which a plurality of prisms are combined as a whole, and includes a prismatic leg 70a and a polygonal head 70b. Regardless of the configuration, the role of the conveyance system is to ensure that the conical protrusion 22c1 and the head 70b are physically resisted by the sheet in addition to the friction coefficient of the material, thereby ensuring a larger conveyance force. Is possible.

It is a figure explaining the structure of a feeding roller. It is a figure explaining a projection part. It is a figure explaining the shape of a projection part. It is a figure explaining the state which provided the contact bonding layer. It is a figure explaining a feeding part. It is a figure explaining the behavior of the projection part of a feeding roller during feeding operation. It is a figure explaining the behavior of the projection part of a feeding roller during feeding operation. It is a figure explaining the behavior of the projection part of a feeding roller during feeding operation when durability advanced. It is a figure explaining the feeding roller which concerns on 2nd embodiment. It is a figure explaining a feeding part. It is a figure explaining the other structure of a feeding roller. It is a figure explaining the sheet | seat separation member which concerns on 3rd embodiment. It is an enlarged view explaining a projection part. It is a figure explaining separation operation. It is a figure explaining other embodiment. 1 is a diagram illustrating an entire image forming apparatus. FIG. 10 is a diagram illustrating an example of a feeding unit of a conventional image forming apparatus.

Explanation of symbols

2 ... feed cassette 3 ... sheet support plate 4 ... pressure spring 5 ... separating member 6 ... final paper separating sheet 7 ... sheet detecting arm 8 ... photo interrupter
10 ... Feed roller
11… Conveyance roller
12 Shaft body
12a ... axis of rotation
14 ... Elastic layer
16… support part
16a ... Cylindrical outer peripheral surface
18 Shaft
20… Base
20a ... surface
22 Projection
22a, 22a1, 22a2 ... leg
22b, 22b1, 22b2 ... head
22c1… Conical protrusion
24… Adhesive layer
30 ... Feed roller
32… shaft body
32a ... axis of rotation
34… Support part
34a ... irregular outer peripheral surface
36… Shaft
38… Main area
40… Sub-region
42… support part
44… shaft body
46… Main area
50… Separation member
52… Support
52a ... surface
54… Elastic layer
56… Mounting part
58… Base
58a ... surface
60 ... Projection
60a1, 60a2 ... Leg
60b1, 60b2… head
70 ... Projection
70a ... Leg
70b ... head
100 ... Image forming apparatus
101… Laser scanner
102… Photosensitive drum
103… Conveying roller
104… Registration roller
105… Transfer roller
106… Conveyor belt
107… Fixer
108… discharge roller
109… Tray
200 ... Feed roller
201… feed cassette
202… Sheet support plate
203… Pressure spring
204… separation member
205… Final paper separation sheet
206… Seat detection arm
207… Photo interrupter

Claims (10)

In the feeding roller in which the elastic body layer is formed on the outer periphery of the shaft body,
The elastic layer includes a base and a plurality of fine protrusions formed on the surface of the base, each having a three-dimensional protruding shape,
The base and the protrusion are integrally formed from the same elastic material, and there are at least two types of three-dimensional protrusion shapes of the plurality of protrusions,
The feeding roller, wherein the protrusion is brought into frictional contact with the sheet at each tip, and the sheet is fed by rotation of the shaft. The plurality of protrusions are provided on the surface of the base portion with a spatial arrangement density of 15.5 pieces / cm ² or more,
Each of the plurality of projecting portions has a height H of 0.254 mm to 1.27 mm and a maximum transverse dimension D of 0.076 mm to 0.76 mm under the condition of an aspect ratio H / D ≧ 1.25. Item 2. The feeding roller according to Item 1. The three-dimensional protruding shape of the protrusion is
Columnar or pyramidal legs,
A head formed integrally with the tip of the leg,
The feeding roller according to claim 1, wherein the shape of the head is spherical, hemispherical, disc-shaped, polyhedral, cone-shaped, conical, or a combination thereof. The shaft body has a cylindrical support portion, and a shaft portion that extends in the axial direction from the support portion and defines a rotation axis of the shaft body,
The feeding roller according to claim 1, wherein the elastic layer is provided along an outer peripheral surface of the support portion. The outer peripheral surface of the support part is
A main region extending in an arc shape over an arbitrary center angle around the rotation axis;
Having at least one sub-region extending inside the virtual cylindrical surface including the main region and connected to the main region;
The feeding roller according to claim 4, wherein the plurality of protrusions are provided at least at a position corresponding to the main region.   The elastic layer is made of a plate-like elastic member, and is fixed to an outer peripheral surface of the support portion via an adhesive layer, and an edge of the elastic member is disposed at a position corresponding to the sub-region. The feeding roller according to claim 5.   The feeding roller according to claim 5, wherein the elastic member is an endless hollow cylindrical member, and is fixed to the outer peripheral surface of the support portion by a frictional force and an elastic restoring force of the elastic member itself. In the sheet separating member in which the elastic layer is formed on the surface of the support,
The elastic layer includes a base and a plurality of fine protrusions formed on the surface of the base, each having a three-dimensional protruding shape,
The base and the protrusion are integrally formed from the same elastic material, and there are at least two types of three-dimensional protrusion shapes of the plurality of protrusions,
The sheet separating member according to claim 1, wherein the protrusions are brought into frictional contact with the sheet at each tip to brake the sheet. The plurality of protrusions are provided on the surface of the base portion at a spatial arrangement density of 15.5 pieces / cm ² or more,
Each of the plurality of projecting portions has a height H of 0.254 mm to 1.27 mm and a maximum transverse dimension D of 0.076 mm to 0.76 mm under the condition of an aspect ratio H / D ≧ 1.25. Item 9. The sheet separating member according to Item 8. The three-dimensional protruding shape of the protrusion is
Columnar or pyramidal legs,
A head formed integrally with the tip of the leg,
9. The sheet separating member according to claim 8, wherein the shape of the head is spherical, hemispherical, disc-shaped, polyhedral, cone-shaped, conical, or a combination thereof.

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