JP2019073383A - Sheet carrier device and image formation device - Google Patents

Abstract

To provide a sheet carrier device capable of efficiently realizing both reduction of driving torque and curl correction.SOLUTION: There is provided a sheet carrier device 60 including: an elastic roller 70 having elasticity and rotating around a rotation shaft, and a correction roller 80 that is pressed by the elastic roller 70 and has a hardness higher than that of the elastic roller 70. The correction roller 80 is provided with projections 83 projecting outward from a circumferential surface. The projections 83 are provided so that density is higher at both ends of the correction roller 80 than at a center in a width direction.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a sheet conveying apparatus and an image forming apparatus for conveying a sheet along a sheet conveyance path.

  In an image forming apparatus using an electrophotographic method, a sheet on which an unfixed toner image is formed is heated and pressed to fix the toner image on the sheet. The sheet may be curved (curled) due to the influence of heat or pressure from a roller, which may reduce the workability at the time of conveyance and loading. In order to solve this problem, it has been proposed to provide a mechanism for correcting the curl in the image forming apparatus (for example, Patent Document 1 and Patent Document 2).

Unexamined-Japanese-Patent No. 2006-21857 Unexamined-Japanese-Patent No. 2010-195572

  In the image forming apparatus described in Patent Document 1, the roller for conveying the sheet material (sheet) is a grooved roller having a groove portion extending in an oblique direction with respect to the circumferential direction formed on the outer peripheral surface.

  In the decurler device described in Patent Document 2, a first decurler roller in which a peak portion of a spiral is formed by winding a rod-like body around a cylindrical surface forming a valley and forming a spiral peak, and the first decurler roller. A pair of decurler rollers is constituted by the second decurler roller around which the rod-like body is wound.

  In Patent Document 1 and Patent Document 2, although the groove portions and the rod-like members are provided at uniform intervals, in the paper, the likelihood of occurrence of curling differs depending on the portion. That is, since curling occurs remarkably at the end of the sheet, it is desirable to focus on the portion where curling is likely to occur, but in the above-mentioned Patent Document 1 and Patent Document 2, the treatment for it is made Absent.

  Further, in the structure in which the sheet is nipped and conveyed by two rollers, there is a problem that the contact area becomes large and the driving torque becomes high when the roller uniformly presses the entire surface of the sheet. By providing grooves or projections on the roller, the contact area is reduced and the driving torque is reduced, but the portion to be corrected by pressing the sheet is reduced, so that the effect of correcting the curl is lost. However, in the image forming apparatus, it is required to take measures for both the reduction of the driving torque and the correction of the curl, and a method capable of efficiently realizing both is desired.

  The present invention has been made to solve the above-described problems, and it is an object of the present invention to provide a sheet conveying apparatus and an image forming apparatus capable of efficiently realizing both reduction of driving torque and curl correction. Do.

  The sheet conveying device according to the present invention is a sheet conveying device that conveys a sheet along a sheet conveying path, has elasticity, and is pressed by an elastic roller rotating around a rotation shaft, and the elastic roller And a correction roller having a hardness higher than that of the elastic roller, and when the direction parallel to the rotation axis of the elastic roller is taken as the width direction, the correction roller is provided with a projection projecting outward from the circumferential surface, The portions are provided such that the density is higher at both ends of the correction roller than at the center in the width direction.

  In the sheet conveying apparatus according to the present invention, the projection is spirally extended along the circumferential surface of the correction roller, and the direction in which the projection is drawn is the sheet conveyance direction. The configuration may be inclined.

  In the sheet conveying apparatus according to the present invention, the projection may be configured such that the angle inclined with respect to the conveyance direction becomes smaller as it goes from the center to the both ends in the width direction among the correction rollers.

  In the sheet conveying apparatus according to the present invention, the protrusion may have a multiple spiral shape at both end portions in the width direction of the correction roller.

  In the sheet conveying apparatus according to the present invention, the elastic roller may be formed to have a diameter larger than that of the correction roller.

  An image forming apparatus according to the present invention includes the sheet conveying apparatus according to the present invention.

  According to the present invention, by providing the protrusion on the correction roller, the contact area when holding the sheet can be reduced, and the driving torque for rotating the elastic roller and the correction roller can be reduced. In addition, since the sheet curls more easily at both ends than at the center, the projections can be efficiently corrected by providing the projections at a high density.

FIG. 1 is a schematic side view of an image forming apparatus according to a first embodiment of the present invention. FIG. 1 is a schematic side view showing a sheet conveying apparatus according to a first embodiment of the present invention. It is a schematic plan view of the correction roller shown in FIG. It is an expanded sectional view which expands and shows the projection part vicinity. It is a schematic plan view of the correction | amendment roller in the paper conveying apparatus which concerns on 2nd Embodiment of this invention. It is a schematic plan view of the correction | amendment roller in the paper conveying apparatus which concerns on 3rd Embodiment of this invention.

First Embodiment
Hereinafter, an image forming apparatus according to a first embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic side view of an image forming apparatus according to a first embodiment of the present invention.

  The image forming apparatus 100 is a multifunction peripheral having a scanner function, a copying function, a printer function, a facsimile function, and the like, and transmits an image of a document read by the image reading apparatus to the outside (corresponding to the scanner function) And forms an image of a read original or an image received from the outside on a sheet in color or single color (corresponding to a copying function, a printer function, and a facsimile function).

  A document transport unit 50 (ADF) supported openably and closably with respect to the image reading unit 41 is provided on the upper side of the image reading unit 41. When the document conveyance unit 50 is opened, the document placement table 44 above the image reading unit 41 is opened so that the document can be placed manually. Further, the document conveyance unit 50 automatically conveys the placed document onto the document passing unit 43 provided in the image reading unit 41. The image reading unit 41 reads the placed document or the document conveyed from the document conveyance unit 50 and generates image data.

  The image forming apparatus 100 includes an optical scanning device 1, a developing device 2, a photosensitive drum 3 (an example of a photosensitive member), a drum cleaning device 4, a charger 5, an intermediate transfer belt 7, a fixing unit 12, a sheet conveyance path S, A paper cassette 10, a loading tray 15 and the like are provided.

  In the image forming apparatus 100, image data corresponding to a color image using each color of black (K), cyan (C), magenta (M), and yellow (Y) or a monochrome image using a single color (for example, black) Is treated. The image transfer unit 20 of the image forming apparatus 100 is provided with four developing devices 2 for forming four types of toner images, four photosensitive drums 3, four drum cleaning devices 4 and five chargers 5, each of which is black. , Cyan, magenta, and yellow, and four image stations Pa, Pb, Pc, and Pd are configured.

  The drum cleaning device 4 removes and collects residual toner on the surface of the photosensitive drum 3. The charger 5 uniformly charges the surface of the photosensitive drum 3 to a predetermined potential. The light scanning device 1 exposes the surface of the photosensitive drum 3 to form an electrostatic latent image. The developing device 2 develops the electrostatic latent image on the surface of the photosensitive drum 3 to form a toner image on the surface of the photosensitive drum 3. A toner image of each color is formed on the surface of each photosensitive drum 3 by the above-described series of operations.

  An intermediate transfer roller 6 is disposed on the upper side of the photosensitive drum 3 via the intermediate transfer belt 7. The intermediate transfer belt 7 is stretched around the transfer driving roller 7 a and the transfer driven roller 7 b, rotates in the direction of the arrow C, removes and collects residual toner by the belt cleaning device 9, and the surface of each photosensitive drum 3 The toner images of the respective colors formed in the above are sequentially transferred and superimposed to form a color toner image on the surface of the intermediate transfer belt 7.

  The transfer roller 11 a of the secondary transfer unit 11 has a nip area (secondary transfer position) formed with the intermediate transfer belt 7, and the sheet conveyed through the sheet conveyance path S is nipped by the nip area. Transport When the sheet passes through the nip area, the toner image on the surface of the intermediate transfer belt 7 is transferred and conveyed to the fixing unit 12.

  The fixing unit 12 includes a fixing roller 31 and a pressure roller 32 which rotate with the sheet interposed therebetween. The fixing unit 12 sandwiches the sheet on which the toner image is transferred between the fixing roller 31 and the pressure roller 32, heats and presses the sheet, and fixes the toner image on the sheet.

  The sheet feeding cassette 10 is a cassette for storing sheets used for image formation, and is provided below the light scanning device 1. The sheet is pulled out of the sheet feeding cassette 10 by the sheet pickup roller 16, conveyed through the sheet conveyance path S, passes through the secondary transfer unit 11 and the fixing unit 12, and passes through the sheet discharge roller 17 to the stacking tray 15. It is carried out. In the sheet conveyance path S, the sheet is temporarily stopped and the leading end of the sheet is aligned, and then, the sheet is adjusted according to the transfer timing of the color toner image in the nip area between the intermediate transfer belt 7 and the transfer roller 11a. A sheet registration roller 14 for starting conveyance, a conveyance roller 13 for urging conveyance of a sheet, a sheet conveyance device 60, and a sheet discharge roller 17 are disposed.

  The sheet conveying device 60 is disposed between the fixing unit 12 and the sheet discharge roller 17. The sheet conveyance device 60 will be described in detail with reference to FIG. 2 described later.

  When image formation is performed not only on the front side but also on the back side of the sheet, the sheet is conveyed in the reverse direction from the sheet discharge roller 17 to the sheet reversing path Sr, the sheet is reversed, and the sheet is registered. The sheet is guided again to 14 and image formation is performed on the back side in the same manner as the front side, and the sheet is discharged to the stacking tray 15.

  FIG. 2 is a schematic side view showing the sheet conveying apparatus according to the first embodiment of the present invention.

  The sheet conveyance device 60 according to the first embodiment of the present invention includes an elastic roller 70 and a correction roller 80. The elastic roller 70 is in contact with the correction roller 80 via the sheet conveyance path S. That is, the sheet is conveyed in the conveyance direction H by the sheet being held between the elastic roller 70 and the correction roller 80 and the elastic roller 70 and the correction roller 80 being rotated.

  The elastic roller 70 is formed in a substantially cylindrical shape, and includes an elastic rotation shaft 71 with an end supported, and an elastic pressing portion 72 covering the circumferential surface of the elastic rotation shaft 71. A drive source (not shown) is connected to the elastic rotation shaft 71, and the elastic roller 70 is rotated by the force transmitted from the drive source. The elastic pressing portion 72 is formed of a material having elasticity, and in the present embodiment, is formed of a sponge, and the hardness measured with an Asker C-type hardness meter is 20 ° ± 5 °. . In the following, for the sake of explanation, the direction parallel to the elastic rotation shaft 71 may be referred to as the width direction W (see FIG. 3 described later).

  The correction roller 80 has a substantially cylindrical shape, and protrudes outward from the peripheral surface of the correction peripheral surface portion 82 covering the peripheral surface of the correction rotational shaft 81 whose end is supported, the peripheral surface of the correction rotational shaft 81, and The projection 83 is configured. The correction roller 80 is formed of a material having a hardness higher than that of the elastic roller 70 (in particular, the elastic pressing portion 72), and is formed of metal in the present embodiment. The correction roller 80 is driven to rotate by the rotation of the elastic roller 70 in contact. The present invention is not limited to this, and the correction roller 80 may rotate and the elastic roller 70 may follow, or a drive source may be connected to both the elastic roller 70 and the correction roller 80.

  Although only the outer periphery of the projection 83 is shown in FIG. 2 as contacting the elastic pressing portion 72, the present invention is not limited to this, and the force for pressing the elastic roller 70 and the correction roller 80 may be set appropriately. That is, a portion of the elastic pressing portion 72 in contact with the protrusion 83 may be deformed by a force that the protrusion 83 presses.

  The elastic roller 70 is formed to have a diameter larger than that of the correction roller 80. That is, by increasing the diameter of the elastic roller 70, the area in which the elastic roller 70 contacts the sheet can be increased, which is more effective in reducing the driving torque.

  Next, the detailed structure of the correction roller 80 will be described in conjunction with FIGS. 3 and 4.

  FIG. 3 is a schematic plan view of the correction roller shown in FIG. 2, and FIG. 4 is an enlarged cross-sectional view showing the vicinity of a protrusion in an enlarged manner. In FIG. 4, hatching is omitted in consideration of the viewability of the drawing.

  The protrusion 83 is extended around the axis of the correction rotation shaft 81, and has a ring shape that is slightly larger than the correction circumferential surface portion 82. The correction roller 80 is provided with a plurality of protrusions 83, and the plurality of protrusions 83 are arranged separately in the width direction W. The distance between the protrusions 83 is appropriately set depending on the position in the width direction W, and in the correction roller 80, both ends in the width direction W have a short distance (first width interval TW1), and the width direction W In the middle of the long interval (second width interval TW2). In the present embodiment, the distance between the protrusions 83 is set to be gradually longer from the both ends in the width direction W of the correction roller 80 toward the center, but is not limited to this. With regard to 80, a predetermined range based on the center in the width direction W may be set as a central area, and a range other than the central area may be set as an end area, and the distance between the protrusions 83 may be set. For example, in the central region, the spacing between the protrusions 83 may be arranged as the second width spacing TW2, and in the end region, the spacing between the protrusions 83 may be arranged as the first width spacing TW1.

  As described above, the protrusions 83 are provided such that the density is higher at both ends of the correction roller 80 than at the center in the width direction W. Therefore, by providing the projection 83 on the correction roller 80, the contact area when holding the sheet can be reduced, and the driving torque for rotating the elastic roller 70 and the correction roller 80 can be reduced. In addition, since the sheet curls more easily at the both ends than at the center, the projections 83 can be efficiently corrected by providing them with a high density.

  As shown in FIG. 4, the tip of the protrusion 83 is rounded. As a result, the area in contact with the nipped sheet is increased, so that it is possible to avoid application of pressure locally and to prevent marks such as lines from remaining in the pressed portion.

Second Embodiment
Next, a sheet conveyance device 60 according to a second embodiment of the present invention will be described with reference to the drawings. In addition, in 2nd Embodiment, since it has the general | schematic structure substantially the same as 1st Embodiment, the same code | symbol is attached | subjected and drawing and description are abbreviate | omitted.

  FIG. 5 is a schematic plan view of a correction roller in a sheet conveying apparatus according to a second embodiment of the present invention.

  In the second embodiment, the shape of the correction roller 80 (in particular, the protrusion 83) is different from that of the first embodiment. Specifically, the protrusion 83 is spirally extended along the circumferential surface (the circumferential surface 82) of the correction roller 80. That is, in the first embodiment, the plurality of projections 83 are arranged side by side in the width direction W, whereas in the second embodiment, one of the plurality of projections 83 connected from one end to the other end in the width direction W of the correction roller 80 A projection 83 is provided. Thus, by extending the protrusion 83 in a spiral shape, a plurality of locations in contact with the elastic pressing portion 72 are provided in the same manner as in the case where the plurality of protrusions 83 are provided while the protrusion 83 itself is continuous. . In the following, in the present embodiment, among the continuous projections 83, portions in contact with the elastic pressing portion 72 at the same timing are regarded as one projection 83, and the plurality of projections 83 separated in the width direction W are It may be described as having a configuration.

  As shown in FIG. 5, in the direction (stretching direction) in which the protrusions 83 are stretched, an angle (tilt angle) inclined with respect to the conveyance direction H depends on the position in the width direction W of the correction roller 80. It is different. Specifically, at both ends in the width direction W of the correction roller 80, the angle (end portion inclination angle θ1) formed between the extension direction of the protrusions 83 and the transport direction H is small, and the protrusion in the center in the width direction W The angle (central inclination angle θ2) formed between the extension direction of the portion 83 and the transport direction H is large. As described above, the protrusions 83 are stretched while changing the inclination angle, and the distance between the protrusions 83 is narrow at both ends in the width direction W of the correction roller 80, and the protrusion is in the center in the width direction W of the correction roller 80. The interval between the parts 83 is wide. By adjusting the inclination angle of the protrusion 83, it is possible to obtain a shape in which the density of the protrusion 83 differs between the center and the both ends of the correction roller 80. Further, in the projecting portion 83 drawn in a spiral shape, when the correction roller 80 rotates, the portion where the projecting portion 83 exists is displaced in the width direction W. As a result, the sheet can be corrected in both the longitudinal and lateral directions.

  In the present embodiment, the inclination angle of the protrusion 83 is set to gradually increase from the both ends in the width direction W of the correction roller 80 toward the center, but the invention is not limited thereto. The inclination angle may be increased at the end of the end area.

  In the present embodiment, one protrusion 83 connected from one end to the other end in the width direction W of the correction roller 80 is used, but the present invention is not limited thereto. For example, one end side and the other end side from the center in the width direction W And the drawing direction may be reversed. That is, although FIG. 5 shows a structure in which the projection 83 is inclined downward to the right with respect to the transport direction H, any one end side may be inclined downward to the left.

Third Embodiment
Next, a sheet conveyance device 60 according to a third embodiment of the present invention will be described with reference to the drawings. In the third embodiment, the general structure is substantially the same as that of the first embodiment and the second embodiment, so the same reference numerals are given and the drawings and the description are omitted.

  FIG. 6 is a schematic plan view of a correction roller in a sheet conveying apparatus according to a third embodiment of the present invention.

  The third embodiment differs from the second embodiment in that the protrusions 83 are provided in a double spiral shape. Specifically, in the third embodiment, the projection 83 is in the form of a spiral drawn at a uniform inclination angle, and is a first spiral connected from one end of the correction roller 80 in the width direction W to the other end. It is comprised by 83a and the 2nd spiral part 83b provided in the both ends of the width direction W of the correction roller 80. As shown in FIG. That is, the first spiral portion 83a is provided in the central region and the end region. The second spiral portion 83b is provided only in the end region, and is provided so as to shift the position in the width direction W with respect to the first spiral portion 83a. As a result, at both ends in the width direction W of the correction roller 80, the second spiral portion 83b exists between the first spiral portions 83a, and the distance between the protrusions 83 becomes narrow. Then, at the center of the correction roller 80 in the width direction W, only the first spiral portion 83a is provided, so the distance between the protrusions 83 is relatively wide.

  In the present embodiment, although the protrusion 83 has a double spiral shape, the present invention is not limited to this. A plurality of spiral protrusions 83 may be stacked to form a multiple spiral protrusion 83.

  Although FIG. 1 shows a structure in which the sheet conveying device 60 is disposed between the fixing unit 12 and the sheet discharge roller 17, the present invention is not limited to this. The conveyance device 60 can be appropriately disposed, and may be disposed in the document conveyance unit 50. The sheet conveying apparatus 60 according to the present invention is used as a post-processing apparatus that applies post-processing to sheets discharged from the image forming apparatus 100, and a relay apparatus that conveys the sheet to a downstream apparatus such as a post-processing apparatus. It may apply.

  The embodiment disclosed this time is an example in all points, and it is not a basis for a limited interpretation. Therefore, the technical scope of the present invention is not interpreted only by the above-mentioned embodiment, and is defined based on the statement of a claim. Moreover, all the changes within the meaning and range equivalent to a claim are included.

DESCRIPTION OF SYMBOLS 60 sheet conveying apparatus 70 elastic roller 71 elastic rotating shaft 72 elastic pressing portion 80 correction roller 81 correction rotating shaft 82 correction peripheral surface portion 83 projecting portion 83 a first spiral portion 83 b second spiral portion 100 image forming apparatus H conveyance direction S paper conveyance path W width direction

Claims (6)

A sheet conveying apparatus for conveying a sheet along a sheet conveyance path, comprising:
An elastic roller having elasticity and rotating about a rotation axis;
And a correction roller pressed by the elastic roller and having a hardness higher than that of the elastic roller.
When a direction parallel to the rotation axis of the elastic roller is taken as a width direction,
The correction roller is provided with a protrusion that protrudes outward from the circumferential surface,
The sheet conveying device according to claim 1, wherein the protrusions are provided such that the density is higher at both ends of the correction roller than at the center in the width direction. The sheet conveying apparatus according to claim 1, wherein
The protrusion is helically extended along the circumferential surface of the correction roller,
A sheet conveying apparatus, wherein a direction in which the projection is extended is inclined with respect to a sheet conveying direction. The sheet conveying apparatus according to claim 2, wherein
The sheet conveying apparatus according to claim 1, wherein the protrusion is inclined at an angle with respect to the conveyance direction as going from the center to the both ends in the width direction of the correction roller. The sheet conveying apparatus according to claim 2, wherein
The sheet conveying apparatus according to claim 1, wherein the projection is formed in a multiple spiral shape at both ends in the width direction of the correction roller. The sheet conveying apparatus according to any one of claims 1 to 4, wherein
The sheet conveying device, wherein the elastic roller is formed to have a diameter larger than that of the correction roller.   An image forming apparatus comprising the sheet conveyance device according to any one of claims 1 to 5.

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