JP2003321142A - Roller member, sheet conveyer using the same, and image processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate a rotation-directional distortion quantity of an elastomer layer in a roller member and axis-directional unevenness in a nip width, and to restrain skewing and wrikling in a sheet, change in a speed, and the like, by simple structure. <P>SOLUTION: This roller member for contacting with the sheet to separate or convey the sheet by frictional force has support parts 5 erected on an acting face with the sheet, and a plurality of protrusion members 4 constituted of a head part 6 contacting with the sheet formed in a tip of the each support part 5, and is constituted to make elastic force of the support part 5 small from the central part toward both end parts along a roller axis direction. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to contacting a sheet,
Regarding the roller member for conveying the sheet by its frictional force, especially for any size sheet, skewing of the sheet and change in conveying speed are minimized, and wrinkles are prevented from occurring on the sheet. The present invention relates to a roller member capable of conveying a sheet, a sheet conveying apparatus using the same, and an image processing apparatus such as an electrophotographic copying machine, a printer, a word processor, and a facsimile machine.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine or a laser beam printer, at least one of a pair of conveying rollers used for conveying a sheet or the like is generally a shaft having a high hardness such as metal (hereinafter referred to as "shaft"). It is composed of a composite roller on which an elastic layer such as rubber is formed.

The pair of conveying rollers are pressed against each other by the compressive force of a pressure spring or the like at both ends of the shaft, and a contact area called a nip is formed by the deformation of a low hardness material such as rubber. The sheet is sandwiched by both rollers in the nip region and conveyed by rotation of the pair of conveying rollers.

Here, the shaft of the conveying roller is bent by a compressive load applied to both ends of the roller, and the bending of the shaft is
Since both rollers are brought closer to each other in the end portion than in the central portion in the roller axial direction, the rubber or the like at the end portion is deformed more than in the central portion, and the nip width is made non-uniform in the axial direction. The non-uniformity of the nip width and the nip pressure causes the skew of the sheet,
It becomes a factor that increases wrinkles.

Therefore, in order to make the axial nip distribution of a pair of upper and lower rollers uniform, at least one of the pair of rollers has an outer diameter at the end portion rather than an outer diameter at the central portion in the axial direction. It was formed in a Tyco shape so that

Further, in the case of a mere Tyco roller, since the roller diameters in the axial direction are set to be different, the peripheral speeds of the respective parts of the roller are different, and the sheet is likely to be wrinkled.

Therefore, as shown in Japanese Patent Publication No. 6-2537, for example, a drum-shaped roller is used as the registration roller, and a pre-transfer roller provided between the photosensitive drum and the registration roller is provided at the center of the roller. Wrinkles are prevented by using an inverted Tyco-type roller whose end portion has a diameter larger than the outer diameter.

Alternatively, as shown in Japanese Unexamined Patent Publication No. 5-92837, an elastic material such as rubber which is divided into several pieces in the axial direction is attached to the shaft body, and the hardness of the elastic material at the center is set to the elasticity at the end. By making it harder than the body, and by providing a plastic collar member on the elastic body surface at the end, it is possible to reduce the change in the nip in the roller axial direction and make the force applied from the roller to the sheet uniform. Proposed.

Further, as disclosed in Japanese Patent Application Laid-Open No. 9-208077, the outer diameter of both end portions of the cored bar is made smaller than the outer diameter of the central portion so that the thickness of both end portions is made thicker than the central portion of the roller, so that A structure has been proposed in which the nip width is made uniform in the entire direction.

[0010]

The factors that determine the sheet conveyance state are the roller diameter when the roller pair is pressed against each other to form a nip, and the distortion in the rotational direction due to the rubber deformation in the cross section perpendicular to the axis. The amount, the nip width, etc. may be mentioned.

Each of the above factors has a different value in the roller axial direction due to the bending of the shaft body, which causes skewing and wrinkling.

In Japanese Patent Publication No. 6-2537 of the above-mentioned prior art, the roller diameter can be made uniform in the axial direction, but the amount of distortion in the rotation direction of the rubber and the nip width become non-uniform in the axial direction of the roller.
Both skew and wrinkles cannot be completely resolved.

Further, in Japanese Patent Laid-Open No. 5-92837, since an elastic member such as rubber is divided and mounted on the core metal, the entire surface in the axial direction of the roller does not come into contact with the sheet. It has the drawback of not being suitable for transportation.

Further, in Japanese Unexamined Patent Publication No. 9-208077, it is necessary to cut the core metal, resulting in an increase in processing time and cost.

The present invention has been made in view of the above problems, and an object thereof is to eliminate a strain amount in a rotation direction of an elastic layer of a roller member and an axial nonuniformity of a nip width with a simple structure. However, the present invention provides a roller member that suppresses skewing, wrinkling, and speed change of a sheet, and a sheet conveying apparatus and an image forming apparatus including the roller member at low cost.

[0016]

A typical constitution according to the present invention for achieving the above object is a roller member for contacting a sheet, conveying the sheet by frictional force, or separating the sheet, It has a support part standing upright on the working surface of the sheet, and a plurality of projecting members composed of a head formed at the tip of the support part and capable of contacting the sheet. It is characterized in that it is configured so as to become smaller from the central portion toward both ends in the direction.

In the above structure, even if the shaft body is slightly bent and a high compressive force is applied to the end portion, the support of the protruding member at the end portion is deformed with a lower pressure than the supporting portion of the protruding member on the surface of the central portion of the roller. By the portion, the compressive force is distributed to the central portion, and the roller outer diameter in the nip portion, the nip width, and the circumferential distortion in the nip portion can be made more uniform along the roller axial direction. Skewed sheet during transport,
It is possible to prevent conveyance defects such as wrinkles.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] A first embodiment of the present invention will be described below with reference to the drawings.

[Overall Structure] First, the schematic structure and operation of the image forming apparatus main body to which the sheet conveying apparatus of the present invention is applicable will be briefly described with reference to FIG.

A laser beam whose intensity is modulated by a laser scanner 18 provided in the main body 10 of the apparatus by an image signal sent from a host computer (not shown) is mirror 19.
The photosensitive drum 15 that has been charged in advance is irradiated with light through the above, and an electrostatic latent image is formed on the drum 15. Then, the electrostatic latent image is developed by a developing unit (not shown) to form a toner image.

On the other hand, the sheets S in the storage cassette 11 mounted on the lower part of the apparatus main body are separated and fed one by one by the feeding roller 14 and the separating pad 12, and pass through the conveying roller pairs 21 and 22 and then the registration roller pair 1. , 13, the skew is corrected,
Further, the conveyance timing is adjusted so as to be synchronized with the formation of the toner image. After that, the sheet S is conveyed to the image forming portion, the toner image on the photosensitive drum 15 is transferred onto the sheet S by the transfer means 16, and is conveyed to the fixing device 20 by the conveying belt 17. The fixing device 20 is a fixing roller 31 with a built-in heater.
The transfer roller is fixed by heating and pressing the sheet S by the pressure roller 32 that presses the sheet S against the fixing roller 31. Then, the sheet on which the image is fixed is paired with a conveyance roller.
The sheet is discharged to the discharging section 27 by the pair of discharging rollers 23 and 24 and the discharging rollers 25 and 26.

{Roller Structure of Sheet Conveying Device} Next, the sheet conveying device according to the present embodiment will be described with reference to FIGS. 1 to 3. 1A is a perspective view showing the details of the registration roller 1 as a conveyance device according to the present invention.
1B is a sectional view of the same, and FIG. 1C is a front view of the same. Figure 2 (a)-
3C is an enlarged view of the three-dimensional structure on the surface of the registration roller in the axial range W1 of the registration roller elastic layer, FIG.
(a) to (c), the axial range W of the resist roller elastic layer
FIG. 2 is an enlarged view of a three-dimensional structure on the surface of the registration roller at W3 and W3.

As shown in FIGS. 1 (a) and 1 (b), the registration roller 1 has a hardness of EPDM, CR rubber, silicon rubber, urethane rubber or the like on the outer periphery of a shaft body 2 made of metal or resin. Of the elastic material layer 3 which is formed of a low material, contacts the sheet S, and conveys the sheet S by a frictional force.

The elastic layer surface 3a of the registration roller 1 is finely processed. As shown in FIGS. 2 (a) and 2 (b),
A base portion 3b which is not finely processed and a three-dimensional structure 4 which is a protrusion member which is finely processed are formed.

As shown in FIGS. 2 (a) and 2 (b), the three-dimensional structure 4 has a spherical shape, a hemispherical shape, a disk shape, or a conical shape at the tip (a spherical shape having a diameter R in this embodiment). ) Head 6 and a shape such as a cylinder, a cylinder, an elliptic cylinder, a polygonal prism, a cone, an elliptic cone, or a polygonal pyramid that holds the head 6 and is built from the elastic body base portion 3b (a cylindrical shape in the present embodiment). It is formed into a mushroom shape by the supporting portion 5. The height (h + R) of the three-dimensional structure 4 is formed in the range of 1 to 500 μm.

Further, the registration roller is 1, and as shown in FIG. 1 (c), the total length in the axial direction of the elastic layer 3 is W, and the range W1 located at the central portion, the range W2 located on both sides thereof, and both ends thereof. Part W3.

Here, in the present embodiment, the range W1 = W2 =
Although W3 = W / 5 is configured, the range may be equally divided or unequal divided into any number.

The support portion 5 of the three-dimensional structure 4 in the range W1 located at the center in the axial direction of the elastic layer shown in FIG.
The diameter of the cylindrical portion is r, and the thickness of the supporting portion in the ranges W2 and W3 on both sides thereof is a cylindrical shape having a diameter r-Δr. If Δr in the range W2 is Δr2 and Δr in the range W3 is Δr3, r> r−Δr, respectively.
The relationship of 2> r-Δr3 and R>r> Δr3 is established. Here, the distance L between adjacent three-dimensional structures is the range W.
All of 1, 1, W2, and W3 have the same configuration.

{Sheet Conveying Operation} Next, the operation of the registration roller 1 having the above construction will be described with reference to FIGS.
4 is a diagram showing a contact state between the three-dimensional structure 4 and the sheet S when the registration rollers 1 are in the sheet conveying state, and FIG. 5 is when the registration roller pairs 1 and 13 are in the sheet conveying state. It is a conceptual perspective view of. Note that, in FIGS. 4 and 5, for convenience of description, the display is reversed upside down from the actual arrangement.

When the sheet S is conveyed by the registration roller 1, as shown in FIG. 4A, the registration roller 1 rotates in the direction of arrow A, and the sheet S contacts the spherical head 6 of the registration roller 1. It is conveyed in the direction of arrow A by the frictional force generated as a result. At this time, even if the paper dust 7 adheres to the sheet S, the paper dust 7 does not adhere to the head 6 because it falls on the base portion 3b, which affects the sheet conveying force of the three-dimensional structure 4. Do not give.

When the sheet is conveyed, the supporting portion 5 of the three-dimensional structure 4 in the registration roller nip region is shown in FIG.
As shown in (a), the sheet S is elastically deformed in a direction opposite to the conveying direction and is in a state of falling. Due to the elastic deformation of each of the three-dimensional structure supporting portions 5, the three-dimensional structure tip spherical portion 6 surely contacts the sheet S on any unevenness of the surface of the sheet S, so that the contact area in the entire nip portion is always maintained. It is kept constant and a stable conveying force can be obtained.

When the roller has a uniform rubber thickness in the axial direction and the shaft is bent, a compressive force P due to a pressure spring or the like is applied, so that a greater compressive force is applied to the end portion than to the central portion. In addition, the nip width at the end becomes larger than that at the center of the roller. For this reason, as shown in FIG. 5, there occurs a conveyance speed at which the sheet conveyance speed at the end portion of the registration roller 1 is higher than that at the center portion in the longitudinal direction.

However, in the present embodiment, as described above, compared with the diameter r of the three-dimensional structure supporting portion 5 in the range W1 located at the longitudinal center of the registration roller 1,
The diameter r−Δr of the supporting portion 5 in the range W2 located on the end side of the registration roller, and further in the range W3 is reduced,
The elastic force of is lower on the end side than on the central part. Therefore, the compressive force that is concentrated on the roller end is dispersed in the center, and the roller outer diameter at the nip, the nip width, and the circumferential distortion at the nip are uniform along the roller axial direction. Therefore, it is possible to prevent conveyance defects such as skewing and wrinkling of sheets of any size during the sheet conveyance.

Further, with the above structure, the compressive force P by the pressure springs applied to both ends of the shaft body 2 for obtaining the frictional force necessary for conveying the sheet at the nip portion of the pair of registration rollers can be set lower than before. . As a result, the flexure of the shaft body 2 of the registration roller 1 due to the compressive force P applied to both ends of the roller can be minimized.

Second Embodiment Next, a second embodiment of the roller having a three-dimensional structure will be described with reference to the drawings. FIG. 7 is a front view showing the registration roller 8 according to the second embodiment having a three-dimensional structure, and FIGS. 8A to 8C are three-dimensional views of the registration roller surface in the axial range W3 of the registration roller elastic layer. It is an enlarged view of a structure.

Members having the same functions as those in the above-described embodiment are designated by the same reference numerals. In addition, the present embodiment is configured in the same manner as the first embodiment except for the shape and arrangement of the three-dimensional structure in the ranges W2 and W3 of the resist roller elastic layer.

As shown in FIG. 7, the total length of the elastic layer in the registration roller 8 in the axial direction is W, and is composed of a range W1 located at the center, a range W2 located on both sides thereof, and W3 located at both ends. .

Here, W1 = W2 = W3 = W / 5 holds, but the present invention is not limited to this.
May be unequally divided into any number, as in the first embodiment described above.

Elastic layer axial range W1 to W3 shown in FIG.
In the support portion 5 of the three-dimensional structure 4 in FIG.
It has a cylindrical shape. However, the distance between adjacent three-dimensional structures is L in the range W1, and the range W on both sides thereof is W.
In 2 and W3, it is L + ΔL. Where Δ in W2
If L is ΔL2 and ΔL in W3 is ΔL3, then 0 <
The relationship of ΔL2 <ΔL3 is established.
That is, the number of the three-dimensional structures 4 per unit area decreases toward the roller axial end.

As a result, the elastic force per unit area on the elastic body surface of the registration roller 8 becomes lower at the end portion than at the central portion in the longitudinal direction, like the registration roller 1 of the first embodiment. As a result, the compressive force concentrated on the roller ends is dispersed in the central portion, and the roller outer diameter, the nip width, and the circumferential distortion in the nip portion are made uniform along the roller axial direction. Therefore, it is possible to prevent a conveyance failure such as skewing or wrinkling of a sheet of any size when the sheet is conveyed.

[Third Embodiment] In the above-described embodiment, the head 6 formed by each of the three-dimensional structures 4 formed on the elastic layer surface is formed in each of the ranges W1, W2, W3 in the elastic layer axial direction. Although the positional relationship is aligned in the axial direction and the sheet conveying direction orthogonal to the axial direction (see FIGS. 2C and 3C), this is not necessarily aligned in the axial direction and the sheet conveying direction. Even (see FIG. 9), the same effect can be obtained. If they are not aligned, the leading edge of the sheet does not easily slip between the leading edges of the three-dimensional structure 4, and the effect of preventing damage to the leading edge of the sheet can be obtained.

Since the sheet can be conveyed with a relatively low pressing force by having the three-dimensional structure 4 as described above, as shown in FIG. 9 (c), the elastic layer 3 is used as the shaft body. Even if the configuration is intermittently set to 2, the same effect can be obtained at low cost without damaging the sheet.

[Other Embodiments] In the above-described embodiments, the elastic force of the supporting portion 5 or the number of the projecting members per unit area is changed for each of the ranges W1, W2, W3. Instead of setting, the elastic force of the supporting portion 5 may be gradually reduced from the central portion in the roller axial direction, or the number of projecting members per unit area may be reduced.

In the above-described embodiment, the example in which the three-dimensional structure 4 is provided on the registration roller 1 has been described, but the roller as the sheet conveying device according to the present invention can be applied to other sheet conveying rollers including the above-mentioned registration roller pair. Applicable.

Further, not only the sheet conveying roller,
It is effective to provide the above-described three-dimensional structure 4 for the roller member for separating the sheets.

Further, in the above-described embodiment, an example in which the sheet conveying device is used for the image forming apparatus is shown, but the invention is not limited to the image forming apparatus, and a device having another sheet conveying mechanism, for example, a document is conveyed and its information is transmitted. It is naturally possible to use it for a reading device such as a scanner having an image reading means for reading the.

[0047]

As described above, according to the present invention, the nip portion and the nip portion are deformed even if the roller shaft bends and a high compressive force is applied to the end portion, which causes a difference in the peripheral speed of each portion in the roller axial direction. In the projecting member near the downstream side, the elastic reaction force by the supporting portion becomes weaker on the roller axial end side, so that an elastic reaction force in a direction that alleviates the adverse effect on the sheet conveyance due to the difference in peripheral speed is generated. It is possible to suppress skewing, wrinkling, etc. within an allowable value, and it is possible to inexpensively provide a sheet conveying apparatus and an image processing apparatus capable of accurately conveying a sheet.

[Brief description of drawings]

FIG. 1 is a configuration diagram illustrating a registration roller as a transport device according to a first embodiment.

FIG. 2 is an enlarged view showing a configuration of a three-dimensional structure in an axial range W1 of the registration roller elastic layer according to the first embodiment.

FIG. 3 is an enlarged view showing a configuration of a three-dimensional structure in axial ranges W2 and W3 of the registration roller elastic body layer according to the first embodiment.

FIG. 4 is a diagram showing operations of a three-dimensional structure and a sheet when the registration rollers according to the first embodiment are in a sheet conveying state.

FIG. 5 is a conceptual perspective view when a registration roller pair is in a sheet conveying state.

FIG. 6 is an overall configuration diagram of an image forming apparatus main body according to the first embodiment.

FIG. 7 is a diagram showing a registration roller as a conveyance device according to a second embodiment.

FIG. 8 is an enlarged view showing a configuration of a three-dimensional structure in axial ranges W2 and W3 of the registration roller elastic layer according to the second embodiment.

FIG. 9 is a configuration diagram showing a registration roller according to a third embodiment.

[Explanation of symbols]

S ... sheet 1,13 ... Registration roller 2 ... Shaft 3 ... Elastic layer 3a ... Elastic layer surface 3b ... the base 4… 3D structure 5 ... Support 6 ... Head 7… Paper dust 8 ... Registration roller 10… Device body 11… Storage cassette 12… Separation pad 14… Feeding roller 15… Photosensitive drum 16… Transfer means 17… Conveyor belt 18… Laser scanner 19… Mirror 20… Fixer 21, 22… Conveyor rollers 23, 24… Transport rollers 25, 26… Ejection roller 27… Ejector 31… Fixing roller 32… Pressure roller

Claims (10)

[Claims] 1. A roller member for coming into contact with a sheet and for conveying the sheet by frictional force or separating the sheet, wherein a support portion that stands up on a working surface of the sheet and a tip end of the support portion are formed. It has a plurality of projecting members composed of a head capable of contacting the sheet, and is configured such that the elastic force of the supporting portion is reduced from the central portion toward both ends in the roller axial direction. Roller member. 2. The roller shaft is divided into a plurality of ranges in the axial direction so that the elastic force of the supporting portion is the same within each range, and the elastic force becomes smaller from the central portion toward both ends in the roller axial direction. The roller member according to claim 1, wherein the elastic force is set for each range. 3. A roller member for coming into contact with a sheet and for conveying the sheet by frictional force or separating the sheet, the supporting portion being erected on a surface acting with the sheet, and formed at the tip of the supporting portion. It has a plurality of protrusion members composed of a head capable of contacting the sheet, and the number of the protrusion members per unit area is configured to decrease from near the central portion toward both ends in the roller axial direction. A roller member characterized by. 4. The roller member is divided into a plurality of ranges in the axial direction of the roller, and the number of the protruding member per unit area is the same within each range, and the protruding member of the protruding member is moved from the central portion toward both end portions in the roller axial direction. The roller member according to claim 3, wherein the number is set for each range so that the number per unit area is reduced. 5. The method according to claim 1, wherein the protrusion member is provided intermittently in a roller axial direction.
The roller member according to any one of 1. 6. The protrusion shape of the protrusion member has a height of 1 to 500.
2. A mushroom-like shape having a size of .mu.m.
The roller member according to claim 5. 7. The roller member according to claim 6, wherein the head portion of the protrusion member has a spherical shape, a disk shape, a conical shape, or an elliptical cone shape. 8. The roller member according to claim 7, wherein the support portion of the protrusion member is a cylinder, a cylinder, an elliptic cylinder, a polygonal prism, a cone, an elliptical cone, or a polygonal cone. 9. A sheet carrying device for carrying a sheet by a roller member, wherein the roller member has the roller member according to any one of claims 1 to 8. 10. An image forming means for forming an image on a sheet or an image reading means for reading an image of a sheet original,
An image processing apparatus comprising the sheet conveying device according to claim 9, which conveys a sheet to the image forming unit or the image reading unit.