JP3871021B2 - Separating paper feeder and image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a separation sheet feeding device and an image forming apparatus using the separation sheet feeding device.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer, an FRR (feed reverse roller) type separation feeding is used as a device for separating and feeding sheets stacked one by one on a sheet stacking unit. The device is widely adopted.
[0003]
Such an FRR type separation sheet feeding apparatus will be described with reference to FIGS. An FRR-type separation sheet feeding device 101 is disposed on one end side of the sheet stacking unit 100 on which a large number of sheets S are stacked and in the direction in which the sheet S is fed. , A transport roller 102, a return roller 103, a drive motor (not shown) for rotating the transport roller 102 and the return roller 103, and the like. A pickup roller 104 is disposed above the paper stacking unit 100 to feed the stacked paper S toward the nip between the transport roller 102 and the return roller 103.
[0004]
The conveyance roller 102 includes a rotation shaft 102a connected to a drive motor, a conveyance roller main body 102b formed in a cylindrical shape and fixed to the rotation shaft 102a, and the like. The driving force from the drive motor acts in a direction in which the transport roller 102 is rotationally driven in a direction in which the paper S is fed from the paper stacking unit 100 (clockwise direction indicated by an arrow). The transport roller main body 102b is formed of an elastic body such as vulcanized rubber, elastomer, or foamed resin.
[0005]
The return roller 103 includes a rotation shaft 103a connected to a drive motor, a return roller main body 103b formed in a cylindrical shape and attached to the outer peripheral portion of the rotation shaft 103a via a torque limiter 105, and the like. Driving force is transmitted from the driving motor to the return roller 103 via a driving shaft 106 connected to the driving motor, a gear 107 fixed to the driving shaft 106, and a gear 108 fixed to the rotating shaft 103a and meshing with the gear 107. Done. The return roller main body 103b is formed of an elastic body such as vulcanized rubber, elastomer, or foamed resin.
[0006]
When the driving force from the drive motor is transmitted to the return roller 103, the return roller 103 is rotationally driven in the direction of returning the paper S to the paper stacking unit 100 (clockwise direction indicated by the solid line arrow). When the return roller 103 is rotated in the paper S feeding direction (counterclockwise direction indicated by the broken arrow) by the transport roller 102, slip occurs in the torque limiter 105, and only the return roller main body 103b. Is rotated in the paper feeding direction.
[0007]
One end of the rotating shaft 103 a of the return roller 103 is supported by a slide bearing 109. The slide bearing 109 is biased by a spring 110, and the return roller 103 is pressed against the conveying roller 102 by the biasing force of the spring 110.
[0008]
The pickup roller 104 is provided so as to freely move up and down between a lowered position indicated by a solid line and an elevated position indicated by a broken line. When the pickup roller 104 moves to the lowered position and comes into contact with the uppermost sheet S, the sheet feeding direction (indicated by an arrow). By being driven to rotate in the clockwise direction, the paper S is sent out toward the nip portion between the transport roller 102 and the return roller 103.
[0009]
According to the separation sheet feeding device 101, when the sheet S is not sent between the conveyance roller 102 and the return roller 103, the conveyance roller 102 and the return roller 103 are in direct contact with each other. Then, when the conveyance roller 102 and the return roller 103 are in direct contact with each other and the paper feed drive motor is driven, a torque of a predetermined value or more is transmitted from the conveyance roller 102 to the return roller 103, and the return roller main body portion. 103b is rotated in the paper feeding direction (counterclockwise direction indicated by a broken arrow).
[0010]
When the sheet S is sent between the transport roller 102 and the return roller 103 being rotated in this way, and the number of the sheets S is two or more, only the uppermost sheet S is transported. Is fed (rotation in the clockwise direction). Further, the return roller 103 is rotated and driven in a direction to return the paper S to the paper stacking unit 100, and the second and subsequent sheets S from the top are returned to the paper stacking unit 100, and the paper S is double-fed. Is prevented.
[0011]
When there is one sheet S sent between the transport roller 102 and the return roller 103, or the second sheet or less from the top of the sheets S sent in two or more sheets to the sheet stacking unit 100. When one sheet S remains between the transport roller 102 and the return roller 103 after returning, a torque of a predetermined value or more is transmitted from the transport roller 102 to the return roller 103 via the sheet S. Then, the return roller main body 103b is rotated in the paper feeding direction (counterclockwise direction indicated by the broken line of the arrow), and the paper S is fed.
[0012]
[Problems to be solved by the invention]
According to the sheet separating and feeding apparatus shown in FIGS. 8 and 9, the conveyance roller main body portion 102b and the return roller main body portion 103b, which are formed of an elastic body such as rubber, are liable to wear and have a reduced coefficient of friction. The frictional force decreases with time, and the non-feeding of the paper S and the double feeding of the paper S are likely to occur gradually.
[0013]
In recent image forming apparatuses, the number of types of paper S to be used is increased, and coated paper, surface glossy paper, and polymer films are frequently used to form high-quality images. These coated papers, surface glossy papers, and polymer films have extremely low air permeability as compared with plain papers, so when trying to separate the stacked papers S, they become airtight, and the adsorption power increases, resulting in more non-feeding. There is a problem that double feeding is likely to occur.
[0014]
An object of the present invention is to provide a separation sheet feeding device and an image forming apparatus capable of improving the sheet feeding performance of a conveying roller and the returning performance of a return roller and preventing non-feeding and double feeding of sheets.
[0015]
[Means for Solving the Problems]
According to the first aspect of the present invention, in the FRR-type separation sheet feeding device having a conveyance roller and a return roller, the conveyance roller includes a conveyance roller main body formed in a columnar shape and a number of conveyance roller protrusions that pierce the paper. A plurality of conveying roller protrusion bands provided in a ring shape along the circumferential direction on the outer peripheral portion of the conveying roller main body portion, and the outer peripheral portion of the conveying roller main body portion along the circumferential direction. Conveying roller relief grooves provided in a ring shape alternately with the conveying roller protrusion band, a conveying roller inter-axis maintaining portion provided in a ring shape along the circumferential direction of the outer peripheral portion of the conveying roller main body, and the conveying A conveying roller follower provided in a ring shape along the circumferential direction on the outer peripheral portion of the roller body, and the conveying roller protrusion is formed to protrude from the outer peripheral portion of the conveying roller inter-axis maintaining portion. The return roller has a return roller main body formed in a columnar shape and a number of return roller protrusions that pierce the paper, and is provided in a ring shape along the circumferential direction of the outer periphery of the return roller main body. A plurality of return roller protrusion bands, return roller escape grooves provided in a ring shape alternately with the return roller protrusion bands along the circumferential direction of the return roller main body section, and the return roller main body section. A return roller shaft maintaining portion provided in a ring shape along the circumferential direction of the outer peripheral portion of the return roller, and a return roller follower portion provided in a ring shape along the circumferential direction of the outer peripheral portion of the return roller main body portion The return roller protrusion is formed to protrude from the outer peripheral portion of the return roller inter-axis maintaining portion, and when the transport roller and the return roller are in direct contact with each other, The return roller inter-shaft maintaining portion is brought into contact, the carrying roller follower portion and the return roller follower portion are brought into contact, and the tip end portion of the carry roller protrusion is brought into contact with the bottom surface of the return roller escape groove. The transport roller protrusion band is opposed to the return roller escape groove, and the return roller protrusion band is not in contact with the bottom surface of the transport roller escape groove and the return roller protrusion band is opposed to the transport roller escape groove. Has been.
[0016]
Here, the case where the conveyance roller protrusion or the return roller protrusion pierces the paper includes both the case where the paper is punched and inserted, and the case where the paper is recessed and bites into the indented portion.
[0017]
Further, in order for the conveyance roller protrusion or the return roller protrusion to pierce the sheet, it is required that the longitudinal elastic modulus (Young's modulus) is 0.1 GPa (giga-pascal) or more. Examples of satisfying this condition include metals, plastics, ceramics, and glass. Specifically, titanium (116 GPa), steel (100 to 210 GPa), alumina (3800 Pa), aluminum (70.3 GPa), glass (71 GPa), glass fiber-containing polycarbonate (10.8 to 3.1 GPa), alumina ( 3800 GPa), 95% alumina ceramic (30000 GPa), and the like.
[0018]
Therefore, when the paper is fed between the transport roller and the return roller and the paper is fed or returned to the paper stacking unit, the transport roller protrusion and the return roller protrusion are pierced into the paper. In addition, no slip occurs between the conveyance roller or the return roller and the paper, and the paper feeding performance and return performance are improved, thereby preventing the occurrence of paper non-feed and double feed.
[0019]
When the conveyance roller and the return roller are in direct contact with each other, the conveyance roller inter-axis maintaining unit and the return roller inter-axis maintaining unit are in contact with each other, so that the axis between the conveyance roller and the return roller is maintained at a predetermined value. Is done. At this time, the conveyance roller rotation portion and the return roller rotation portion come into contact with each other to drive the conveyance roller, whereby the return roller is rotated in the paper feeding direction by the conveyance roller. Further, the transport roller inter-shaft maintaining portion and the return roller inter-shaft maintaining portion are brought into contact with each other to maintain the inter-shaft between the transport roller and the return roller at a predetermined value, so that the front end portion of the transport roller protrusion is moved away from the return roller. The state where the groove is not in contact with the bottom surface of the groove is maintained, and the tip end portion of the return roller protrusion is maintained in the state where it is not in contact with the bottom surface of the conveying roller escape groove. For this reason, abrasion of the conveyance roller protrusion and the return roller protrusion hardly occurs, and the paper feeding performance and return performance of the paper can be maintained in a good state for a long period.
[0020]
According to a second aspect of the present invention, in the separation paper feeding device according to the first aspect, the conveyance roller inter-axis maintaining section is provided at both ends of the conveying roller, and the return roller inter-axis maintaining section is disposed at both ends of the return roller. Provided in the department.
[0021]
Therefore, when the conveyance roller and the return roller are in direct contact with each other, the conveyance roller inter-axis maintaining portion and the return roller inter-axis maintaining portion are in contact with each other at both ends of the conveyance roller and the return roller. The shaft between the return roller can be maintained with high accuracy.
[0022]
According to a third aspect of the present invention, in the separation paper feeding device according to the second aspect, at least one set of the conveying roller inter-axis maintaining unit and the return roller inter-axis maintaining unit that are in contact with each other is the conveying roller rotation unit. And the return roller rotation portion.
[0023]
Therefore, at least a part of the transport roller inter-axis maintaining unit and the transport roller follower and the return roller inter-shaft maintainer and the return roller follower can be shared, and the structure is simplified.
[0024]
According to a fourth aspect of the present invention, in the separation sheet feeding device according to any one of the first to third aspects, the conveyance roller rotation portion and the return roller rotation portion are each formed in a gear shape.
[0025]
Here, the gear shape does not mean only the gear, but the periodic unevenness is repeated on the outer periphery of the disc body, and the two facing each other have a function of rotating in mesh with each other. Means that.
[0026]
Therefore, the conveyance roller and the return roller rotation portion meshed with each other, and the conveyance roller and the return roller can be reliably rotated.
[0027]
According to a fifth aspect of the present invention, in the separation paper feeding device according to the fourth aspect, the outer diameter dimensions of the conveyance roller rotation portion and the return roller rotation portion formed in a gear shape are respectively the conveyance roller protrusions. Is smaller than the outer diameter size of the root portion or the outer diameter size of the root portion of the return roller projection.
[0028]
Accordingly, when the paper is fed between the transport roller and the return roller, and the transport roller protrusion or the return roller protrusion is pierced into the paper and separated paper feeding is performed, the transport roller follower portion and the return portion formed in a gear shape are returned. The roller follower is not pressed against the paper, and the paper is not crushed and damaged by the transport roller follower and the return roller follower formed in a gear shape.
[0029]
According to a sixth aspect of the present invention, in the separation paper feeding device according to any one of the first to fifth aspects, the transport roller main body, the transport roller protrusion band, the transport roller escape groove, and the transport roller shaft The interval maintaining portion and the conveyance roller follower portion are integrally formed.
[0030]
Therefore, the number of parts and the number of manufacturing steps necessary for manufacturing the transport roller are reduced, and the manufacturing cost is also reduced.
[0031]
According to a seventh aspect of the present invention, there is provided the separation paper feeding device according to any one of the first to sixth aspects, wherein the return roller main body, the return roller protrusion band, the return roller escape groove, and the return roller shaft. The interval maintaining portion and the return roller rotation portion are integrally formed.
[0032]
Therefore, the number of parts and the number of manufacturing steps necessary for manufacturing the return roller are reduced, and the manufacturing cost is also reduced.
[0033]
According to an eighth aspect of the present invention, in the separation paper feeding device according to any one of the first to seventh aspects, a ring-shaped elastic member is provided in the conveyance roller escape groove and the return roller escape groove.
[0034]
Therefore, when the paper is fed between the transport roller and the return roller and separated and fed, the portion of the paper that contacts the transport roller protrusion band enters the return roller escape groove, and the portion that contacts the return roller protrusion band is the transport roller. Although it tends to enter the escape groove and become wavy, the provision of the ring-shaped elastic member prevents the paper from entering the conveyance roller escape groove and the return roller escape groove, and the paper is wrinkled. It is prevented.
[0035]
9. The image forming apparatus according to claim 9, wherein the sheet stacking unit on which sheets are stacked and the sheets stacked on the sheet stacking unit are separated and fed one by one. A separation feeding device; and an image forming unit that forms an image on the separated and fed paper.
[0036]
Therefore, this image forming apparatus can achieve the same operations and effects as the first to eighth aspects of the invention.
[0037]
DETAILED DESCRIPTION OF THE INVENTION
A first embodiment of the present invention will be described with reference to FIGS. 1 is a longitudinal front view showing a digital copying machine as an image forming apparatus, FIG. 2 is a front view showing a separation sheet feeding apparatus as a part thereof, FIG. 3 is a perspective view showing the separation sheet feeding apparatus, and FIG. FIG. 5 is a longitudinal side view showing a state in which one sheet is sandwiched between the transport roller and the return roller.
[0038]
In the main body case 2 of the digital copying machine 1, a scanner unit 3 is disposed at the top and an image forming unit 4 is disposed below the scanner unit 3. Below the image forming unit 4, two sheet stacking units 5 on which sheets S of different sizes are stacked, and an FRR-type separation supply as a mechanism for feeding the sheets S from each sheet stacking unit 5 A paper device 6 and a pickup roller 7 are arranged. On one side of the main body case 2, a paper discharge unit 8 for discharging the paper S on which image formation has been performed is provided.
[0039]
The scanner unit 3 includes a contact glass 9 on which a document is placed, a first traveling body 12 on which a lamp 10 and a first mirror 11 are mounted, and a second traveling on which a second mirror 13 and a third mirror 14 are mounted. The body 15, the imaging lens 16, the CCD 17, etc. The first traveling body 12 and the second traveling body 15 travel in the same direction (sub-scanning direction) in parallel with the contact glass 9 at a 2-to-1 speed. At this time, the light emitted from the lamp 10 is contact glass 9. The upper document is irradiated, and the reflected light is reflected by the first, second, and third mirrors 11, 13, and 14, and is imaged on the CCD 17 through the imaging lens 16.
[0040]
The image forming unit 4 includes a photoconductor 18, a charging roller 19 that uniformly charges the photoconductor 18, and light that is optically written on the outer peripheral surface of the uniformly charged photoconductor 18 according to the image read by the scanner unit 3. Writing device 20, developing device 21 that forms a toner image by attaching toner to the electrostatic latent image on photoconductor 18, transfer device 22 that transfers the developed toner image onto a sheet, outer peripheral surface of photoconductor 18 A cleaning device 23 that removes residual toner adhering to the sheet S, a fixing device 24 that fixes a toner image transferred onto the sheet S, and a sheet S fed from the sheet stacking unit 5 And a sheet conveying belt 25 that conveys the sheet to the fixing device 24.
[0041]
The FRR separation sheet feeding device 6 includes a conveyance roller 26, a return roller 27, a drive motor (not shown) that rotationally drives the conveyance roller 26 and the return roller 27, and the like.
[0042]
The conveyance roller 26 includes a rotation shaft 28 that is connected to a drive motor and is driven to rotate, a conveyance roller main body 29 that is formed in a cylindrical shape and is fixed to the rotation shaft 28, and a large number of conveyance roller protrusions 30. A plurality of conveying roller protrusion bands 31 formed in a ring shape along the circumferential direction on the outer peripheral portion of the main body portion 29, and alternately with the conveying roller protrusion bands 31 along the circumferential direction on the outer peripheral portion of the conveying roller main body portion 29. Conveying roller clearance groove 32 formed in a ring shape, and a conveying roller abutting ring which is a conveying roller axis maintaining portion formed in a ring shape along the circumferential direction on one end side of the outer peripheral portion of conveying roller main body 29 33, on the other end side of the outer peripheral portion of the transport roller main body 29, the transport roller gear 34, which is a transport roller inter-axis maintaining portion formed in a ring shape along the circumferential direction, and also a transport roller rotating portion, etc. It is configured Ri. The transport roller main body 29, the transport roller protrusion 30, the transport roller abutment ring 33, and the transport roller gear 34 are integrally formed by a rigid body of a conductive member and grounded, and the transport roller protrusion 30 has a hardness and shape that pierces the paper S. have.
[0043]
The protrusion dimension of the conveyance roller protrusion 30 (height dimension from the outer peripheral surface of the conveyance roller protrusion band 31) is 20 to 100 μm. Further, the transport roller protrusion 30 includes an outer peripheral portion of the transport roller contact ring 33 and a pitch circle of the transport roller gear 34. ) Is more prominent. Further, the outer diameter dimension of the conveying roller gear 34 is formed smaller than the outer diameter dimension of the root portion of the conveying roller protrusion 30 (the outer peripheral surface of the conveying roller protrusion band 31).
[0044]
The return roller 27 includes a rotary shaft 35 that is connected to a drive motor and is driven to rotate, a return roller main body portion 37 that is formed in a cylindrical shape and attached to the outer peripheral portion of the rotary shaft 35 via a torque limiter 36, and a large number of return rollers 27. A plurality of return roller protrusion bands 39 formed in a ring shape along the circumferential direction on the outer peripheral portion of the return roller main body portion 37 having the roller protrusions 38 and the outer peripheral portion of the return roller main body portion 37 in the peripheral direction thereof. A return roller relief groove 40 formed in a ring shape alternately with the return roller protrusion band 39, and between the return roller shafts formed in a ring shape along the circumferential direction on one end side of the outer peripheral portion of the return roller main body portion 37 The return roller abutment ring 41, which is a maintenance portion, and a return roller shaft maintenance portion formed in a ring shape along the circumferential direction on the other end side of the outer peripheral portion of the return roller main body portion 37 and the return roller link Is constituted by roller gear 42 and the like return is also around part. The return roller main body 37, the return roller projection 38, the return roller abutment ring 41, and the return roller gear 42 are integrally formed by a rigid body of a conductive member and grounded, and the return roller projection 38 is hard and shaped to pierce the paper S. And have.
[0045]
The protruding dimension of the return roller protrusion 38 (height dimension from the outer peripheral surface of the return roller protrusion band 39) is 20 to 100 μm. The return roller protrusion 38 includes an outer peripheral portion of the return roller contact ring 41 and a pitch circle of the return roller gear 42 (a portion exhibiting an inter-axis maintaining function, and an outer peripheral portion serving as a return roller inter-axis maintaining portion. ) Is more prominent. The outer diameter of the return roller gear 42 is smaller than the outer diameter of the root portion of the return roller protrusion 38 (the outer peripheral surface of the return roller protrusion band 39).
[0046]
The driving force is transmitted from the driving motor to the return roller 27 through a driving shaft 43 connected to the driving motor, a gear 44 fixed to the driving shaft 43, and a gear 45 fixed to the rotating shaft 35 and meshed with the gear 44. Done. One end of the rotating shaft 35 of the return roller 27 is supported by a slide bearing 46. The slide bearing 46 is biased by a spring 47, and the return roller 27 is pressed toward the transport roller 26 by the biasing force of the spring 47.
[0047]
As shown in FIGS. 4 and 5, the conveyance roller 26 and the return roller 27 are opposed to the conveyance roller protrusion band 31 and the return roller escape groove 40, and are opposed to the return roller protrusion band 39 and the conveyance roller escape groove 32. Are arranged to be. Further, the transport roller contact ring 33 and the return roller contact ring 41 are disposed so as to face each other, and the transport roller gear 34 and the return roller gear 42 are disposed to face each other.
[0048]
When the transport roller 26 and the return roller 27 are in direct contact with each other, as shown in FIG. 4, the transport roller contact ring 33 and the return roller contact ring 41 are in contact, and the transport roller gear 34 and the return roller gear 42 are in contact with each other. Mesh. Further, the state where the leading end of the transport roller protrusion 30 does not contact the bottom surface of the return roller escape groove 40 is maintained, the transport roller protrusion band 31 enters the return roller escape groove 40, and the front end of the return roller protrusion 38 is the transport roller escape. The return roller protrusion band 39 enters the conveying roller escape groove 32 while maintaining a state where it does not contact the bottom surface of the groove 32.
[0049]
As described above, the transport roller main body 29, the transport roller protrusion 30, the transport roller contact ring 33, the transport roller gear 34, the return roller main body 37, the return roller protrusion 38, the return roller contact ring 41, and the return roller gear 42. Are integrally formed of a rigid body of a conductive member. Here, the rigid body means one having a longitudinal elastic modulus (Young's modulus) of 0.1 GPa or more, for example, steel having a longitudinal elastic modulus of 100 to 210 GPa, and having a sharpened tip. Can be inserted into the paper S.
[0050]
The conductive member has a volume resistivity of 2 × 10 ^-6 The member is preferably Ωm or less.
[0051]
As a method of integrally forming the transport roller main body 29, the transport roller protrusion 30, the transport roller abutment ring 33, and the transport roller gear 34, the outer periphery of the metal transport roller main body 29 is machined to perform the transport roller. A method of forming the protrusion 30, the conveyance roller contact ring 33, and the conveyance roller gear 34 is exemplified. The method of integrally forming the return roller main body 37, the return roller projection 38, the return roller contact ring 41, and the return roller gear 42 is the same.
[0052]
In such a configuration, when the transport roller 26 and the return roller 27 are in direct contact with each other and are driven to rotate, the transport roller contact ring 33 and the return roller contact ring 41 contact each other as shown in FIG. When the conveyance roller gear 34 and the return roller gear 42 are brought into contact with each other, the dimension between the axes of the conveyance roller 26 and the return roller 27 is maintained at a predetermined dimension. Then, when the transport roller 26 is rotated in the paper feeding direction of the paper S in a state where the transport roller gear 34 and the return roller gear 42 are engaged, the return roller 27 slips at the torque limiter 36, and the return roller 27 The main body 37 is rotated in the paper feeding direction.
[0053]
During the rotation of the conveyance roller 26 and the return roller 27, the conveyance roller protrusion band 31 enters the return roller escape groove 40, and the conveyance roller protrusion 30 is maintained in a state of not contacting the bottom surface of the return roller escape groove 40. Yes. Further, the return roller protrusion band 39 enters the conveyance roller escape groove 32, and the return roller protrusion 38 is maintained in a state of not contacting the bottom surface of the conveyance roller escape groove 32. For this reason, the conveyance roller protrusion 30 and the return roller protrusion 38 do not wear during the rotation of the conveyance roller 26 and the return roller 27, and the conveyance roller protrusion 30 and the return roller protrusion 38 are formed on the sheet S as described later. The paper feeding performance and return performance of the paper S that is pierced can be maintained in a good state over a long period of time.
[0054]
Further, when the sheet S is fed between the conveyance roller 26 and the return roller 27 during the rotation of the conveyance roller 26 and the return roller 27, as shown in FIG. The transport roller 26 and the return roller 27 are moved slightly away from each other due to the paper thickness, the transport roller contact ring 33 and the return roller contact ring 41 are separated, and the transport roller gear 34 and the return roller gear 42 Is released.
[0055]
Then, the conveyance roller protrusion 30 and the return roller protrusion 38 pierce the sheet S fed between the conveyance roller 26 and the return roller 27, and the conveyance force from the conveyance roller 26 that is rotationally driven in the paper feeding direction. The paper S is conveyed in the paper feeding direction. Further, when a torque of a predetermined value or more is transmitted from the conveying roller 26 to the return roller 27 via the paper S, the return roller main body 37 is rotated in the paper feeding direction.
[0056]
In this manner, the conveyance roller protrusion 30 and the return roller protrusion 38 are pierced on both sides of the sheet S and rotate in the sheet feeding direction of the sheet S. Thus, slip does not occur, the paper feeding performance of the paper S is improved, and the occurrence of non-feed can be prevented.
[0057]
When two or more sheets S are fed between the transport roller 26 and the return roller 27 that are being rotated, the transport roller protrusion 30 pierces the upper sheet S so that the transport roller 26 feeds in the paper feeding direction. The return roller 27 is rotationally driven in a direction to return the paper S to the paper stacking unit 5 with the return roller protrusion 38 stuck in the lower paper S. Accordingly, no slip occurs between the transport roller 26 and the uppermost sheet S, and no slip occurs between the return roller 27 and the second or lower sheet S from the top, so that the uppermost sheet. S can be reliably fed and the second and subsequent sheets S from the top can be reliably returned to the paper stacking unit 5, and the paper feeding performance and return performance of the paper S can be improved. The occurrence of sending can be prevented.
[0058]
Further, since the outer diameter dimension of the transport roller gear 34 and the return roller gear 42 is smaller than the outer diameter dimension of the root portion of the transport roller protrusion 30 or the outer diameter dimension of the root portion of the return roller protrusion 38, the transport roller 26 and the return roller gear 42. 27, when the sheet S is fed into and separated and fed, the conveyance roller gear 34 and the return roller gear 42 are not pressed against the sheet S, and the conveyance roller gear 34 and the return roller gear 42 are applied to the sheet S. It does not occur that the paper S is bitten and damaged.
[0059]
In this embodiment, the transport roller main body 29, the transport roller protrusion 30, the transport roller contact ring 33, the transport roller gear 34, the return roller main body 37, the return roller protrusion 38, and the return roller contact ring 41 Since both of the return roller gears 42 are formed of a conductive member and are grounded, static electricity generated by the separation feeding is released through the ground portion, and the transport roller 26 and the return roller 27 are not charged. For this reason, static electricity is no longer charged with respect to the separately fed paper S, and it is possible to prevent the occurrence of a jam that causes the static electricity to be charged on the paper S. In an image forming apparatus that performs image formation by an electrostatic photography method, it is possible to prevent image quality from being deteriorated due to the influence of static electricity.
[0060]
In addition, the transport roller 26 of the present embodiment includes the transport roller main body 29, the transport roller protrusion 30, the transport roller abutment ring 33, and the transport roller gear 34, so that the transport roller 26 is manufactured. The number of parts and the number of manufacturing processes required for the manufacturing process are reduced, and the manufacturing cost is also reduced. Similarly, in the return roller 27, the return roller main body portion 37, the return roller protrusion 38, the return roller contact ring 41, and the return roller gear 42 are integrally formed, so that it is necessary to manufacture the return roller 27. The number of parts and the number of manufacturing processes are reduced, and the manufacturing cost is also reduced.
[0061]
Furthermore, in the present embodiment, the case where steel that is a conductive member is used as a rigid body has been described as an example. However, other members such as plastic, ceramics, glass, and the like can be used as the rigid body. When such a non-conductive member is used, electrostatic charging can be prevented by subjecting the surface to a surface treatment with a conductive material such as plating or conductive coating.
[0062]
Next, a second embodiment of the present invention will be described with reference to FIGS. The same parts as those in the first embodiment described with reference to FIGS. 1 to 5 are denoted by the same reference numerals, and the description thereof is also omitted.
[0063]
The basic structure of the present embodiment is the same as that of the first embodiment, and includes an FRR-type separation sheet feeding device 50. The separation sheet feeding device 50 includes a transport roller 51, a return roller 52, and the like. The drive roller (not shown) etc. which rotationally drive the conveyance roller 51 and the return roller 52 of this are comprised.
[0064]
The basic structure of the conveyance roller 51 is the same as that of the conveyance roller 26 of the first embodiment, and a plurality of conveyance roller protrusion bands 31 having a rotation shaft 28, a conveyance roller body 29, and a large number of conveyance roller protrusions 30, A conveyance roller relief groove 32 formed alternately with the conveyance roller protrusion band 31, a conveyance roller contact ring 33, a conveyance roller gear 34, and the like are provided. The difference between the conveyance roller 51 and the conveyance roller 26 is that the depth dimension of the conveyance roller escape groove 32 is formed deep, and a ring-shaped elastic member 53 is provided in the conveyance roller relief groove 32.
[0065]
The ring-shaped elastic member 53 is made of a compressible material such as rubber or foamed resin, and the outer diameter dimension when not compressed is set to be substantially the same as the cutting edge circle dimension of the conveying roller protrusion 30. Yes.
[0066]
The basic structure of the return roller 52 is the same as that of the return roller 27 of the first embodiment, and a plurality of return rollers having a rotating shaft 35, a torque limiter 36, a return roller main body 37, and a large number of return roller protrusions 38. A protrusion roller 39, a return roller protrusion groove 39, a return roller escape groove 40 formed in a ring shape, a return roller contact ring 41, a return roller gear 42, and the like are provided. The difference between the return roller 52 and the return roller 27 is that the depth dimension of the return roller escape groove 40 is deep, and a ring-shaped elastic member 54 is provided in the return roller escape groove 40.
[0067]
The ring-shaped elastic member 54 is formed of a compressible material such as rubber or sponge, and the outer diameter dimension when not compressed is set to be substantially the same as the cutting edge circle dimension of the return roller protrusion 38. .
[0068]
In such a configuration, when the transport roller 51 and the return roller 52 are in direct contact with each other and are driven to rotate, the transport roller contact ring 33 and the return roller contact ring 41 contact each other as shown in FIG. When the conveyance roller gear 34 and the return roller gear 42 are brought into contact with each other, the dimension between the axes of the conveyance roller 51 and the return roller 52 is maintained at a predetermined dimension. Then, when the transport roller 51 is rotated in the paper feeding direction of the sheet S in a state where the transport roller gear 34 and the return roller gear 42 are engaged, the return roller 52 slips at the torque limiter 36, and the return roller The main body 37 is rotated in the paper feeding direction.
[0069]
During the rotation of the transport roller 26 and the return roller 27, the transport roller protrusion band 31 enters the return roller escape groove 40, and the transport roller protrusion 30 contacts the ring-shaped elastic member 54 to cause the ring-shaped elastic member 54 to move. Although it compresses, it maintains in the state which does not contact the bottom face of the return roller escape groove 40. FIG. Further, the return roller protrusion band 39 enters the conveyance roller escape groove 32, and the return roller protrusion 38 contacts the ring-shaped elastic member 53 to compress the ring-shaped elastic member 53, but on the bottom surface of the conveyance roller escape groove 32. Are kept out of contact. For this reason, abrasion of the transport roller protrusion 30 and the return roller protrusion 38 is unlikely to occur, and the paper feeding performance and return performance of the paper S performed by piercing the paper S with the transport roller protrusion 30 and the return roller protrusion 38 over a long period of time. It can be maintained in a good state.
[0070]
When the paper S is sent between the transport roller 51 and the return roller 52 being rotated, the transport roller protrusion 30 and the return roller protrusion 38 pierce the paper S and prevent slippage with the paper S as described above. As a result, the paper feeding performance and the paper feeding performance are improved, and non-feeding and double feeding can be prevented.
[0071]
Further, when the paper S is sent between the transport roller 51 and the return roller 52 that are being rotated and the paper S is separated and fed, as shown in FIG. The ring-shaped elastic member 54 abuts on the back side of the portion where the band 31 abuts, and the ring-shaped elastic member 53 abuts on the back side of the portion where the return roller protrusion band 39 of the paper S abuts. For this reason, it is possible to prevent the portion of the paper S that contacts the conveyance roller protrusion band 31 from entering the return roller escape groove 40 and deform into a wavy state, and the portion of the sheet S that contacts the return roller protrusion band 39 to convey. It is prevented that the roller escape groove 32 enters and is deformed into a wavy state. Therefore, the wrinkled wrinkle does not occur on the paper S on which image formation has been performed, and the finished state of image formation can be enhanced.
[0072]
【The invention's effect】
According to the separation sheet feeding device of the first aspect, when the sheet is fed between the conveyance roller and the return roller and the sheet is separated and fed, the conveyance roller protrusion and the return roller protrusion are not formed. Separation feeding is performed while piercing the paper, so slip does not occur between the transport roller or return roller and the paper, improving the paper feeding performance and return performance, paper non-feeding and double feeding Can be prevented. In addition, when the transport roller and the return roller are in direct contact, the transport roller inter-axis maintaining portion and the return roller inter-shaft maintaining portion are in contact, and the tip of the transport roller protrusion does not contact the bottom surface of the return roller escape groove, The tip of the return roller protrusion is maintained in a state not in contact with the bottom surface of the conveyance roller escape groove, and the conveyance roller and the return roller are rotated by the contact between the conveyance roller rotation portion and the return roller rotation portion. Therefore, wear of the conveyance roller protrusion and the return roller protrusion is less likely to occur, and the paper feeding performance and return performance of the paper can be maintained in a good state for a long period.
[0073]
According to a second aspect of the present invention, in the separation paper feeding device according to the first aspect, the transport roller inter-axis maintaining section is provided at both ends of the transport roller, and the return roller inter-axis maintaining section is disposed at both ends of the return roller. Since it is provided, the maintenance unit between the conveyance roller shaft and the maintenance unit between the return roller shafts are brought into contact with each other at both ends of the conveyance roller and the return roller, so that the maintenance between the shafts between the conveyance roller and the return roller is maintained. Can be performed with high accuracy.
[0074]
According to a third aspect of the present invention, in the separation paper feeding device according to the second aspect, at least one set of the conveying roller inter-axis maintaining unit and the return roller inter-axis maintaining unit that are in contact with each other includes the conveying roller rotating unit and Since it also serves as the return roller rotation portion, it is possible to share at least a part of the conveyance roller shaft maintenance portion and the conveyance roller rotation portion, and the return roller shaft maintenance portion and the return roller rotation portion. And the structure can be simplified.
[0075]
According to the invention described in claim 4, in the separation sheet feeding device according to any one of claims 1 to 3, the conveyance roller follower and the return roller follower are each formed in a gear shape. The conveyance roller rotation portion and the return roller rotation portion formed in a gear shape mesh with each other, so that the conveyance roller and the return roller can be reliably rotated.
[0076]
According to the fifth aspect of the present invention, in the separation paper feeding device according to the fourth aspect, the outer diameter dimensions of the conveyance roller rotation portion and the return roller rotation portion formed in a gear shape are respectively the conveyance roller protrusions. Since the outer diameter size of the root portion or the outer diameter size of the root portion of the return roller projection is smaller than that, the conveyance roller formed in a gear shape when the paper is fed between the conveyance roller and the return roller and separated and fed. It is possible to prevent the paper from being crushed and damaged by the follower and the return roller follower.
[0077]
According to a sixth aspect of the present invention, in the separation and paper feeding device according to any one of the first to fifth aspects, the conveyance roller main body, the conveyance roller protrusion band, the conveyance roller escape groove, and the conveyance roller shaft-maintenance are maintained. Since the part and the conveyance roller rotation part are integrally formed, the number of parts and the number of production steps necessary for producing the conveyance roller can be reduced, and the production cost can be reduced.
[0078]
According to the seventh aspect of the present invention, in the separation paper feeding device according to any one of the first to sixth aspects, the return roller main body, the return roller protrusion band, the return roller escape groove, and the return roller shaft distance maintenance. Since the part and the return roller rotation part are integrally formed, the number of parts and the number of manufacturing steps necessary for manufacturing the return roller can be reduced, and the manufacturing cost can be reduced.
[0079]
According to the eighth aspect of the invention, in the separation paper feeding device according to any one of the first to seventh aspects, the ring-shaped elastic member is provided in the conveyance roller escape groove and the return roller escape groove. When the paper is fed between the conveyance roller and the return roller and separated and fed, the back side of the portion of the paper that hits the conveyance roller protrusion band enters the return roller escape groove, causing wavy wrinkles, In addition, it is possible to prevent the back surface side of the portion of the paper that has come into contact with the return roller protrusion band from entering the conveying roller escape groove and causing wrinkles in the wavy state, and the finished state of the image can be improved.
[0080]
According to an image forming apparatus of a ninth aspect of the present invention, the sheet stacking unit on which sheets are stacked and the sheets stacked on the sheet stacking unit are separated and fed one by one. The image forming apparatus has the same operation and effect as those of the first to eighth aspects of the present invention. Can do.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional front view showing a digital copying machine which is an image forming apparatus according to a first embodiment of the present invention.
FIG. 2 is a front view showing a separation sheet feeding device that is a part thereof;
FIG. 3 is a perspective view showing the separation sheet feeding device.
FIG. 4 is a longitudinal side view showing a state where a conveyance roller and a return roller are in direct contact with each other.
FIG. 5 is a longitudinal side view showing a state in which one sheet is sandwiched between a conveyance roller and a return roller.
FIG. 6 is a longitudinal side view illustrating a state in which a conveyance roller and a return roller are in direct contact with each other in a separation sheet feeding device according to a second embodiment of the present invention.
FIG. 7 is a longitudinal side view illustrating a state in which one sheet is sandwiched between a conveyance roller and a return roller.
FIG. 8 is a front view showing a conventional separation sheet feeding device.
FIG. 9 is a perspective view thereof.
[Explanation of symbols]
4 Image forming unit
5 Paper stacking section
6,50 Separating paper feeder
26, 51 Transport roller
27, 52 Return roller
29 Conveyor roller body
30 Conveyance roller protrusion
31 Conveying roller protrusion band
32 Conveyor roller groove
33 Conveyor roller axis maintenance unit
34 Conveying roller axis maintaining part, Conveying roller rotation part
37 Return roller body
38 Return roller protrusion
39 Return roller protrusion band
40 Return roller clearance groove
41 Maintaining part between return roller shafts
42 Return roller inter-shaft maintenance section, return roller rotation section
53, 54 Ring-shaped elastic member
S paper

Claims (9)

In an FRR-type separation and feeding device having a transport roller and a return roller,
The transport roller is
A conveyance roller body formed in a cylindrical shape;
A plurality of conveying roller protrusion bands provided in a ring shape along the circumferential direction on the outer peripheral portion of the conveying roller main body portion, having a plurality of conveying roller protrusions that pierce the paper;
A conveyance roller escape groove provided in a ring shape alternately with the conveyance roller protrusion band along the circumferential direction of the outer periphery of the conveyance roller main body;
A transport roller inter-axis maintaining unit provided in a ring shape along the circumferential direction of the outer periphery of the transport roller main body;
A transport roller follower provided in a ring shape along the circumferential direction of the outer periphery of the transport roller body;
Have
The transport roller protrusion is formed to protrude from the outer peripheral portion of the transport roller inter-axis maintaining portion,
The return roller is
A return roller body formed in a cylindrical shape;
A plurality of return roller protrusion bands provided in a ring shape along the circumferential direction of the return roller main body portion having a plurality of return roller protrusions that pierce the paper;
A return roller escape groove provided in a ring shape alternately with the return roller protrusion band along the circumferential direction of the outer periphery of the return roller main body;
A return roller inter-axis maintaining portion provided in a ring shape along the circumferential direction of the outer periphery of the return roller main body;
A return roller follower provided in a ring shape along the circumferential direction of the outer periphery of the return roller body;
Have
The return roller protrusion is formed so as to protrude from the outer peripheral portion of the return roller shaft maintaining portion,
When the transport roller and the return roller are in direct contact,
The conveyance roller axis maintaining part and the return roller axis maintaining part are in contact with each other,
The conveyance roller rotation portion and the return roller rotation portion are brought into contact with each other,
The conveyance roller protrusion band is opposed to the return roller escape groove without the tip of the conveyance roller protrusion being in contact with the bottom surface of the return roller escape groove,
The return roller projection band is opposed to the conveyance roller escape groove without the tip of the return roller projection contacting the bottom surface of the conveyance roller escape groove,
Separation paper feeding device characterized by that. 2. The separation sheet feeding according to claim 1, wherein the transport roller inter-axis maintaining section is provided at both ends of the transport roller, and the return roller inter-axis maintaining section is provided at both ends of the return roller. apparatus. The at least one pair of the transport roller inter-axis maintaining portion and the return roller inter-axis maintaining portion that are in contact with each other serves as both the transport roller revolving portion and the return roller revolving portion. Item 3. The sheet feeding device according to Item 2. 4. The separation sheet feeding device according to claim 1, wherein each of the conveyance roller rotation portion and the return roller rotation portion is formed in a gear shape. 5. The outer diameter dimension of the conveyance roller rotation part and the return roller rotation part formed in a gear shape is the outer diameter dimension of the root part of the conveyance roller protrusion or the outer diameter dimension of the root part of the return roller protrusion, respectively. The separation sheet feeding device according to claim 4, wherein the separation sheet feeding device is smaller. The conveyance roller main body, the conveyance roller protrusion band, the conveyance roller escape groove, the conveyance roller inter-axis maintaining unit, and the conveyance roller rotation unit are integrally formed. Item 6. The separation sheet feeding device according to any one of Items 1 to 5. The return roller main body, the return roller protrusion band, the return roller escape groove, the return roller inter-axis maintaining portion, and the return roller rotation portion are integrally formed. Item 7. The separation sheet feeding device according to any one of Items 1 to 6. The separation sheet feeding device according to any one of claims 1 to 7, wherein a ring-shaped elastic member is provided in the conveyance roller escape groove and the return roller escape groove. A paper stacking unit on which paper is loaded;
The separation sheet feeding device according to any one of claims 1 to 8, wherein the sheets stacked on the sheet stacking unit are separated and fed one by one.
An image forming unit for forming an image on a separately fed sheet;
An image forming apparatus comprising:

Images