JPH10147449A - Sheet material feeding device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve those problems related to sheet material feeding such as slanted feeding or wrinkling of a sheet material to be fed by reducing the unevenness of each nip area in the axial direction caused by several rubber members provided on one roller member of a pair of feeding rollers. SOLUTION: In a sheet material. feeding device which is provided with a rubber roller 1 (first roller member) provided with multiple rubber members 6a to 6d (elastic externally contacted part) at specified positions in axial direction and a resin roller 2 (second roller member) which is provided with a shaft in parallel with the rubber roller 1 and brought in contact with the rubber members 6a to 6d and which feeds sheet materials holdingly to nip areas Na to Nd (non-contact areas), the form of the externally contacted part of the rubber members 6a to 6d of the rubber roller 1 is set spherical so that the contact width of the nip contact area form at the axial center part becomes maximum.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conveying device for conveying a sheet material in an image forming apparatus such as a copying machine, a laser beam printer, and the like. This is a technique that makes it possible to prevent wrinkles from occurring on the surface.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus such as a copying machine or a laser beam printer is provided with a conveying device for conveying a sheet material to an image forming unit. Then, as shown in FIG. 9, the transport device transports the sheet material by rotating the roller while nipping the sheet material in a contact area (referred to as a nip area) formed between the two rollers, as shown in FIG. Some use pairs 101.

The upper roller 10 of the transport roller pair 101
2 (this upper roller is modified by adding “upper” to distinguish the two rollers). A cylindrical shaft 111 made of a rubber-like elastic material is attached to a shaft 111 having a high hardness such as a metal serving as a core metal. Rubber rollers 112a, 112b having low hardness
The lower roller 103 is provided with an outer peripheral surface having a higher hardness than the rubber roller, and both ends of the upper roller 102 are biased toward the lower roller 103 by urging means (not shown) (for example, a member such as a spring). The sheet is pressed by the pressing load of F101 and F102 to form a nip area between which the sheet material is sandwiched.

[0004] The transport roller pair 10 having such a configuration is used.
For example, when the rigidity of the shaft 111 is low, the pressing load may cause a slight bending. Since the deflection of this shaft causes the two rollers to be closer to each other at the end than at the center in the axial direction of the roller, the rubber portions of the rubber rollers 112a and 112b in the axial direction are more greatly deformed than the center in the axial direction. The nip width and the nip pressure between the rubber roller and the rubber roller are made non-uniform in the axial direction.

A pressing load F applied to both ends of the shaft 111
Even if the sizes of 101 and F102 are set to be equal, actually the shaft is affected by the gear floating force and the like when a driving force is transmitted by a gear (not shown) meshed to drive the conveying roller pair 101. Non-uniformity of the pressing force may occur at the left and right ends of both ends of 111, which also makes the nip width non-uniform in the axial direction.

FIG. 10 schematically shows such a state.
The axially outer sides N101a and N102a of the left and right nip regions N101 and N102 are respectively the axially inner sides N101 and N102a.
101b and N102b. In addition, the nip pressure also differs due to the difference in the area of the nip region.

[0007]

Accordingly, the non-uniformity of the nip width and the nip pressure in the axial direction is a factor that hinders uniform conveyance in the conveying width direction when conveying the sheet material. Problems such as skewing and increasing wrinkles have occurred.

In order to solve this problem, in the prior art, for example, the bending rigidity of the shaft 111 is increased to reduce the amount of shaft deflection, thereby reducing the non-uniformity of the nip width in the axial direction, and the pressing load F101 on the left and right sides. , F102 are finely adjusted so as to be uniform in consideration of the influence of the gear levitation force described above, so that the left and right non-uniformity of the nip width is reduced, thereby solving the above-described problem in sheet conveyance. It was done.

However, according to this solution, the structure of the transfer device becomes complicated and adjustment work is required, so that the assembling manufacturability is lowered and the axial pressing load in the nip region due to the aging of the rubber roller is not uniform. It cannot be prevented.

Further, as shown in, for example, Japanese Patent Publication No. 6-2537, a roller in the form of a drum is used as a registration roller, and a roller at the center of the roller is used as a pre-transfer roller installed between the photosensitive drum and the registration roller. There has been proposed a structure in which wrinkles are prevented by using a reverse-type roller having a larger end diameter than that of the roller.

However, according to this conventional technique, the amount of rubber deformation and the nip width are still non-uniform in the roller axis direction when each roller pair is viewed alone, so that it is impossible to completely eliminate both skew and wrinkles. It is.

Further, the transport roller pair 1 having such a configuration
01 is provided with a plurality of rubber rollers in the axial direction, so that the front end of the sheet material conveyed from the upstream is abutted against the nip area to temporarily stop and bend the sheet material, so that the front end timing of the sheet material and It may be used as a registration unit that corrects the posture and then conveys the sheet material to the image forming unit in synchronization with the optical system timing.

FIG. 10 is a diagram schematically showing a state in which the sheet material P1 is abutted on the most protruding portions of the left and right nip regions N101 and N102. If there is a lateral inhomogeneity in the axial direction of the nip width as in this figure, in [Delta] d _n between the abutting position of the abutting position and the right nip region N102 left the nip region N101 as shown in FIG. 3 A difference 121 is generated, and the sheet material P1 is aligned by being inclined by an angle Δθ indicated by 122 in the drawing, so that the correcting operation at the time of registration of the sheet material P1 is not performed correctly.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art. It is an object of the present invention to eliminate the non-uniformity in the nip region in the axial direction with a simple structure. It is an object of the present invention to provide a conveying device capable of solving problems related to conveying a sheet material, such as skew, wrinkling, speed change, and the like.

[0015]

In order to achieve the above object, according to the present invention, a first roller member having a plurality of elastic outer peripheral contact portions at predetermined positions in an axial direction; A second roller member having an axis parallel to the first roller member and abutting on the outer peripheral contact portion, wherein the sheet conveys the sheet material by sandwiching the sheet material in a contact area between the first and second roller members In the material conveying device, the shape of the outer peripheral contact portion of the first roller member is set such that the contact width at the axial center of the shape of the contact region between each outer peripheral contact portion and the second roller member is maximum. Set to be.

According to this, the outer peripheral contact portion has a shape in which the central portion protrudes, the first roller member is bent, and the second roller contact portion is bent.
Even when the parallelism with the roller member is hindered, the change in the shape of the contact area is small, and the symmetry of the conveying force in each contact area when the sheet material is conveyed is maintained. Therefore, problems such as skew and wrinkling of the sheet material are reduced.

Further, in the case where the resist is performed by abutting the leading end of the sheet material on the contact area, a change in the contact width of the contact area of each outer peripheral contact portion at a predetermined position in the axial direction can be suppressed. The posture of the sheet material abutted on the contact area is stabilized, and accurate resist processing can be performed.

The outer peripheral contact portion of the first roller member may have a spherical shape.

The outer peripheral contact portion of the first roller member may have an elliptical spherical shape.

It is preferable that the plurality of outer peripheral contact portions have different outer peripheral diameters in accordance with the axial direction in which the outer peripheral contact portions are located.

According to this, when each outer peripheral contact portion comes into contact with the second roller with uneven pressing force in the axial direction, the size of the contact area is changed by changing the outer peripheral diameter of the outer peripheral contact portion. It can be uniform.

The positions of the plurality of outer peripheral contact portions in the axial direction may be irregularly spaced.

According to this configuration, when each outer peripheral contact portion comes into contact with the second roller with uneven pressing force in the axial direction, the position of the outer peripheral contact portion is appropriately set, whereby each outer peripheral contact portion is set. Is uniform, and the size of the contact area can be uniform.

Preferably, the plurality of outer peripheral contact portions are rubber-like elastic bodies.

It is also preferable that the image forming apparatus includes the above-described sheet material conveying device and an image forming section that forms an image on the sheet material conveyed by the sheet material conveying device.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) FIG. 1 is a view for explaining a first embodiment of the present invention. This drawing is a diagram for explaining a cross-sectional configuration of a transport roller pair R1 including a rubber roller 1 as a first roller member and a resin roller 2 as a second roller member. The transport roller pair R1 is provided in a sheet transport device in an image forming apparatus such as a copying machine, a laser beam printer, and a facsimile, and is configured to transport a sheet material to an image forming unit (not shown).

The pair of transport rollers R1 temporarily stops the pair of transport rollers R1 and contacts the rubber roller 1 and the resin roller 2 (hereinafter referred to as a nip area) by transport means (not shown) upstream of the pair of transport rollers R1. ), The sheet material is conveyed such that the leading end of the sheet material abuts, thereby correcting the skew of the sheet material being conveyed, and re-driving the conveying roller pair R1 at a predetermined timing according to the image forming timing of the image forming unit. This makes it possible to function as a registration unit that can set the sheet material conveyance timing.

The rubber roller 1 has a spherical rubber member 6 serving as an outer peripheral abutting portion on a shaft 5 made of a metallic material serving as a metal core.
A plurality (four in this figure) of a, 6b, 6c, and 6d are provided evenly in the left-right direction in the axial direction. And axis 5
Are biased in the direction in which they contact the resin roller 2 by biasing means (not shown) such as a spring. Arrows F1 and F2 in the figure indicate the urging force.

The resin roller 2 has a shaft 2a made of a metallic material serving as a metal core, and a resin material having a higher hardness than the rubber member 6, for example, a resin material (the kind of material does not necessarily have to be a resin material. Or a hard rubber). The rubber roller 1 and the resin roller 2 have parallel axes.

Accordingly, the rubber roller 1 and the resin roller 2 are in pressure contact with each other, and the contact area is defined as the nip area Na to
Nd. FIG. 2 is an enlarged view of a portion D1 in FIG. 1. FIG. 2A shows a state in which a rubber member 6a (representing the rubber members 6a to 6d) in a state where the shaft 5 is not bent comes into contact. 2B is a schematic diagram illustrating a state in which the rubber member 6a is in contact with the shaft 5 in a state where the shaft 5 is bent.

When the rubber member 6 is spherical, the contact between the rubber member 6a and the resin roller 2 is similar as shown in the figure even if the shaft 5 is bent, and the state of the nip Na 'is the nip width. Neither the pressure inside the nip nor the pressure inside the nip changes substantially as compared with the nip Na when the shaft 5 is not bent. The nip width refers to the rubber member 6 on the outer periphery perpendicular to the axial direction of the resin contact portion 2b.
The width a is elastically deformed and abuts.

If this phenomenon is explained theoretically, Helt
According to the theory of z (rule for giving a contact radius with the plane of a sphere made of an elastic material), the formula for calculating the nip b1 width when the rubber member 6a is spherical is given by the following equation 1, and the rubber member is cylindrical. The formula for calculating the nip width b2 in a certain case is given by the following formula 2.

[0033]

## EQU1 ## b1 = A ₁ √W

[0034]

[Number 2] b2 = A ₂ ³ √W However, A _1, A ₂ are constants determined from the material properties and size of the rubber member (radius) and the like, W is is the pressing force applied to each rubber member .

From the above equations (1) and (2), for example, when the pressing load changes twice, the change rate of each nip width becomes 1.41 times for the cylindrical rubber member, but for the spherical rubber member. Fits 1.26 times.

As described above, the spherical shape has a slower change in the nip size with respect to the pressure change than the cylindrical shape. For example, even when the pressing pressure is non-uniform in the left and right directions in the axial direction due to the gear floating force or the like. The resulting non-uniform nip width is smaller in the spherical rubber member 6a than in the cylindrical rubber member.

Incidentally, as shown in FIG. 10 in the section of the prior art, the nip area in the case where the cylindrical rubber member is provided is such that the axially outer sides N101a and N102a of the nip areas N101 and N102 respectively correspond to each other. Are wider than the axial inner sides N101b and N102b. In addition, the nip pressure also differs due to the difference in the area of the nip region.

This is shown in FIG. 3 again. The nip width L1 at the end is larger than the nip width L102 and L103 at the center.
01 and L104 are larger. Then, the nip areas Na to Na of the transport roller pair R1 to which the present invention is applied
The state of Nd is shown in FIG. 4 and compared with FIG. 3, even if the shaft 5 is bent and an uneven pressing force is applied to each rubber member in the axial direction, the center portion of the spherical rubber member is used for the above-described reason. Nip widths L2 and L3 and end side nip widths L1 and L2
And the difference in size is small.

Further, even when the left and right loads applied to the shaft 5 are non-uniform, the difference in nip width (L1-L4) at the left and right ends of the spherical rubber member is determined by the cylindrical rubber member. The difference between the nip widths at the left and right ends of the member (L101-L104) may be smaller.

In comparison with the case of a cylindrical rubber member,
In the case of a spherical rubber member, the nip area formed by one rubber member and the resin roller 2 is small, and the contact pressure is large. Therefore, if it is not desired to apply too much force to the sheet material, a structure may be employed in which the number of spherical rubber members is increased as necessary. Further, in the present embodiment, the rubber members 6a to 6d are independent, but may be integrally formed by a connecting portion having a smaller diameter than the outer diameter of the rubber member along the shaft 5. Absent.

By adopting such a rubber member configuration, the difference between the nip width at the center and the nip width at the end due to the bending of the shaft 5, and the rubber member due to the urging forces F1 and F2 in FIG. When the pressing load is uneven, the difference between the left and right nip widths can be made smaller than that of the cylindrical rubber member.

As a result, it becomes possible to reduce the skew and wrinkles during the conveyance of the sheet material and correct the posture of the sheet material at the time of performing the registration, so that the sheet material can be conveyed with high accuracy. .

(Embodiment 2) FIGS. 5 and 6 are views for explaining a second embodiment of the present invention, in which an elliptical sphere is used as a rubber member. 33 is a rubber roller,
34 is a resin roller, 35 is a shaft, and 36 is a rubber member.
FIG. 6 is a schematic view of the nip area at this time, and N2 in the figure is the nip area.

In this embodiment, the same effects as those of the first embodiment can be obtained, but in addition, the area of the nip area per one elliptical spherical rubber is larger than that in the case where a ball is used as the rubber member. This is effective when it is desired to reduce the pressure on the sheet material without increasing the number of members.

(Embodiment 3) FIG. 7 shows the structure of a rubber roller 41 according to a third embodiment. 42a-42 in the figure
f is a spherical rubber member, L11 to L16 are diameters of each rubber member, and 43 is a shaft for inserting each rubber member.

As described above, when a plurality of rubber members have the same spherical diameter, the shaft 43 is bent due to the bending of the shaft 43 or the like.
The nip area of the rubber member on the end side of 3 is slightly larger than the nip area of the rubber member at the center.

Therefore, in this embodiment, the diameter of the rubber member is set to L11 <L12 <L13, L16 <L15 <L1.
By making the diameter of the rubber member at the central portion appropriately larger than the diameter of the rubber member at the end portion as in 4, the size of the nip region with respect to the rubber balls at the end portion and the central portion can be made uniform. .

Even if the cylindrical rubber member is used, the nip area can be made uniform by changing the diameter of the cylinder in the axial direction. However, if the axial length of the cylindrical rubber member is long, the axial force is increased due to rubber distortion. Works on sheet material and causes wrinkling of sheet material.

On the other hand, if the structure of the present embodiment is made of a spherical rubber member, the axial force on the sheet material is small, paper wrinkles are not generated, and the size of the nip area in the axial direction is increased. It can be made uniform and, as in the first embodiment,
Problems in conveying the sheet material can be minimized.

(Embodiment 4) FIG. 8 shows the structure of a rubber roller 51 according to a fourth embodiment. 52a-52 in the figure
h is a spherical rubber member, L21 to L26 are intervals between the rubber members, and 53 is a shaft into which each rubber member is inserted.

The bending of the shaft 53 causes the rubber member 52 on the end portion side.
The pressing force applied to the a and 52h is larger than the pressing force applied to the rubber member on the central portion side. However, as in the present embodiment, the distance between the rubber members is set to L21 <L22 <L23, L26 <L25.
By setting <L24, the rubber member 52 on the end portion side is set.
a, 52h is applied to the rubber member 52 at the center.
It can be adjusted to be equal to the pressing force applied to d and 52e.

Therefore, if the interval between the members is appropriately adjusted,
Even when the shaft is bent, the pressing force applied to each rubber member can be made uniform, and the size of each nip region formed by each rubber member and the roller member that is in opposing contact is made uniform in the axial direction. It is possible.

[0053]

According to the present invention, the outer peripheral abutment portion has a shape in which the central portion protrudes, the first roller member is bent, and the outer peripheral abutment portion is parallelized with the second roller member. Is small, the change in the shape of the contact area is small, and the symmetry of the conveying force in each contact area when the sheet material is conveyed is maintained. Therefore, problems such as skew and wrinkling of the sheet material are reduced.

Further, when the resist is performed by abutting the leading end of the sheet material on the contact area, a change in the contact width of the contact area of each outer peripheral contact portion at a predetermined position in the axial direction can be suppressed. The posture of the sheet material abutted on the contact area is stabilized, and accurate resist processing can be performed.

By changing the outer diameter of the outer peripheral contact portion or appropriately setting the position of the outer peripheral contact portion, the pressing force of each outer peripheral contact portion can be made uniform, and the size of the contact area can be made uniform. It is possible to carry out the sheet material more favorably.

Further, since the sheet material is conveyed satisfactorily, the occurrence of wrinkles in the sheet material is prevented, a high-quality image is formed also in the image forming section, and the sheet material is inclined at the time of registration and at the time of conveyance. It is possible to form an image with few lines and no inclination.

[Brief description of the drawings]

FIG. 1 is a diagram of a transport roller pair according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of an end portion of a pair of conveying rollers.

FIG. 3 is a diagram showing a shape of a nip region of a cylindrical rubber member.

FIG. 4 is a diagram showing a shape of a nip region of a spherical rubber member.

FIG. 5 is a diagram of a pair of conveying rollers according to a second embodiment of the present invention.

FIG. 6 is a diagram showing a shape of a nip region according to a second embodiment of the present invention.

FIG. 7 is a view of a rubber roller according to a third embodiment of the present invention.

FIG. 8 is a diagram of a rubber roller according to a fourth embodiment of the present invention.

FIG. 9 is a diagram of a conventional conveying roller pair.

FIG. 10 is a diagram illustrating a nip region and a registration posture of a sheet material in a conventional conveying roller pair.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 rubber roller (first roller member) 2 resin roller (second roller member) 2a shaft 2b resin contact portion 5 shaft 6a to 6d rubber member F1, F2 biasing force Na to Nd nip region (contact region) R1 transport roller versus

Claims (7)

[Claims] 1. A first roller member having a plurality of outer peripheral contact portions having elasticity at predetermined positions in an axial direction, and a first roller member having an axis parallel to the first roller member and contacting the outer peripheral contact portion. A second roller member that is in contact with the first roller member, wherein the first and second roller members sandwich and convey the sheet material in a contact area between the first and second roller members; Wherein the contact width between the outer peripheral contact portion and the second roller member at the axially central portion of the shape of the contact area is maximized. 2. The sheet conveying apparatus according to claim 1, wherein the outer peripheral contact portion of the first roller member has a spherical shape. 3. The sheet conveying apparatus according to claim 1, wherein the outer peripheral contact portion of the first roller member has an elliptical spherical shape. 4. The sheet according to claim 1, wherein the plurality of outer peripheral contact portions have different outer peripheral diameters in an axial direction in which the outer peripheral contact portions are located. Material transfer device. 5. The sheet conveying apparatus according to claim 1, wherein axial positions of the plurality of outer peripheral contact portions are unequally spaced. 6. The sheet conveying apparatus according to claim 1, wherein the plurality of outer peripheral contact portions are rubber-like elastic bodies. 7. An image forming apparatus comprising: the sheet conveying apparatus according to claim 1; and an image forming unit that forms an image on a sheet conveyed by the sheet conveying apparatus. apparatus.