JP2017058409A - Transfer roll and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transfer roll that suppresses the occurrence of filming compared with a configuration where the maximum height undulation Wz of a surface layer of a transfer roll is larger than 2.5 μm, and an image forming apparatus including the transfer roll.SOLUTION: A transfer roll 84 comprises: an elastic layer 112; and a surface layer 116 that is fixed to the outside of the elastic layer 112 with an adhesion part 114 therebetween and has a maximum height undulation Wz of 1 to 2.5 μm. The transfer roll 84 transfers a toner image on an intermediate transfer belt to a medium and has an attachment on the surface layer 116 scraped off by a cleaning member after the transfer.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a transfer roll and an image forming apparatus.

  The following Patent Document 1 discloses a configuration in which a first auxiliary member and a second auxiliary member made of a pad of urethane foam or the like for wiping each area are brought into contact with the axial center portion and both axial surfaces of a transfer roll. Has been. The central portion of the transfer roll in the axial direction is a region where a toner patch is formed. The first auxiliary member that is in contact with this region is pressed against the transfer roll with a pressure higher than that of the second auxiliary member. The hardness is set higher than the hardness of the second auxiliary member.

JP 2005-24692 A

  In the configuration in which the scraping member (blade) is brought into contact with the surface of the transfer roll instead of the pad, so-called filming in which the toner component is thinly adhered to the surface layer due to the undulation of the outer surface layer of the elastic layer of the transfer roll. May occur.

  An object of the present invention is to obtain a transfer roll and an image forming apparatus in which the occurrence of filming is suppressed as compared with a configuration in which the maximum height waviness Wz of the surface layer of the transfer roll is larger than 2.5 μm.

  The transfer roll according to the invention described in claim 1 includes an elastic layer, a surface layer fixed to the outside of the elastic layer via an adhesive portion, and a maximum height waviness Wz of 1 to 2.5 μm; The toner image on the image carrier is transferred to a medium, and the deposit on the surface layer is scraped off by a scraping member after the transfer.

  According to a second aspect of the present invention, in the transfer roll according to the first aspect, the surface layer is applied to a peripheral surface of the elastic layer via the adhesive portion in a state of receiving a tension toward both outer sides in the axial direction. It is fixed.

  According to a third aspect of the present invention, there is provided an image forming apparatus comprising the transfer roll according to the first or second aspect, a transfer unit that transfers a toner image on an image carrier to a medium, and the transfer roll. A scraping member for scraping off deposits on the surface layer; and a pulling mechanism for pulling the surface layer outward in the axial direction when the transfer roll is operated.

  According to a fourth aspect of the present invention, in the image forming apparatus according to the third aspect, a part of the toner image on the image holding member is transferred to a region including the edge of the medium by the transfer roll.

  According to a fifth aspect of the present invention, in the image forming apparatus according to the third or fourth aspect, the tension mechanism has protrusions provided at both ends in the width direction of the surface layer facing outward in the axial direction. It is set as the structure pressed against the inclined part which inclines.

  According to a sixth aspect of the present invention, in the image forming apparatus according to the third or fourth aspect, the tension mechanism includes an elastic member that pulls the surface layer outward in both axial directions.

  According to a seventh aspect of the present invention, in the image forming apparatus according to the third or fourth aspect, the tension mechanism is in contact with both end portions in the width direction of the surface layer and on the outer side in the axial direction of the transfer roll. A roller is provided that is inclined so that the part is positioned on the upstream side in the rotational direction with respect to the part on the inner side in the width direction.

  According to the first aspect of the present invention, the occurrence of filming is suppressed as compared with the configuration in which the maximum height waviness Wz of the surface layer of the transfer roll is larger than 2.5 μm.

  According to the second aspect of the present invention, the surface layer is simpler than the configuration in which the surface layer is fixed to the peripheral surface of the elastic layer via the adhesive portion without receiving a tension toward both axial outer sides. A transfer roll having a structure with a maximum height waviness Wz of the surface layer of 1 to 2.5 μm is obtained.

  According to the third aspect of the present invention, compared to a configuration in which a tension mechanism that pulls the surface layer of the transfer roll outward in the axial direction is not provided during the operation of the transfer roll, the occurrence of contamination of the medium is suppressed.

  According to the fourth aspect of the present invention, in a configuration in which toner tends to adhere to the transfer roll as compared with a configuration in which a part of the toner image on the image carrier is transferred to an area not including the edge of the medium, The toner adhering to the roll is scraped off by the scraping member.

  According to the fifth aspect of the present invention, compared to a configuration in which no tension mechanism is provided to pull the surface layer of the transfer roll outward in the axial direction during the operation of the transfer roll, the occurrence of contamination of the medium is suppressed.

  According to the sixth aspect of the present invention, compared to a configuration in which a tension mechanism that pulls the surface layer of the transfer roll outward in the axial direction is not provided during the operation of the transfer roll, the occurrence of contamination of the medium is suppressed.

  According to the seventh aspect of the present invention, compared to a configuration in which a tension mechanism that pulls the surface layer of the transfer roll outward in the axial direction is not provided during operation of the transfer roll, the occurrence of contamination of the medium is suppressed.

1 is a configuration diagram illustrating an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is a configuration diagram showing a transfer roll used in the image forming apparatus shown in FIG. 1 and a cleaning device for cleaning the surface of the transfer roll. FIG. 2 is a cross-sectional view showing a transfer roll used in the image forming apparatus shown in FIG. 1 in a direction orthogonal to the axial direction. FIG. 4 is a cross-sectional view in the axial direction of the transfer roll shown in FIG. 3, showing a state in which the surface layer is bonded to the elastic layer in a state where the surface layer is pulled outward in the axial direction. (A) is sectional drawing which shows the 1st example of the tension mechanism which pulls a surface layer to an axial direction both outer side at the time of operation | movement of a transfer roll, (B) is the front view which looked at the transfer roll from the direction orthogonal to an axial direction FIG. (A) is sectional drawing which shows the 2nd example of the tension mechanism which pulls a surface layer to an axial direction both outer side at the time of operation | movement of a transfer roll, (B) is the front view which looked at the transfer roll from the direction orthogonal to an axial direction FIG. (A) is sectional drawing which shows the 3rd example of the tension mechanism which pulls a surface layer to an axial direction both outer side at the time of operation | movement of a transfer roll, (B) is the front view which looked at the transfer roll from the direction orthogonal to an axial direction FIG. (A) is sectional drawing which shows the 4th example of the tension mechanism which pulls a surface layer to an axial direction both outer side at the time of operation | movement of a transfer roll, (B) is the front seen from the direction orthogonal to an axial direction FIG. (A) is sectional drawing which shows the 5th example of the tension mechanism which pulls a surface layer to an axial direction both outer side at the time of operation | movement of a transfer roll, (B) is the front view which looked at the transfer roll from the direction orthogonal to an axial direction FIG. FIG. 6 is a plan view showing a print pattern for transferring a part of a toner image on an intermediate transfer belt to a region including an edge of a recording medium. 6 is a table comparing the occurrence of filming on the surface of the transfer roll with and without a tension mechanism that pulls the surface layer outward in the axial direction during operation of the transfer roll. 6 is a graph showing the relationship between the maximum height waviness Wz of the surface layer of the transfer roll and the amount of toner slipping. It is a graph which shows the relationship between the maximum height wave | undulation Wz of the surface layer of a transfer roll, and the abrasion loss of a cleaning blade.

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

  FIG. 1 is a configuration diagram showing an image forming apparatus according to the first embodiment, and shows a so-called tandem type image forming apparatus 10.

  As shown in FIG. 1, the image forming apparatus 10 includes an image forming unit 22 (specifically, 22 a, 22 b, 22 c, and 22 d) of four colors of yellow, magenta, cyan, and black in a main body housing 21. Above that, a belt module 23 is provided along the arrangement direction of the image forming units 22. Further, the image forming apparatus 10 has a sheet or the like as a medium on the lower side of the main body housing 21. A cassette 24 in which a recording medium (not shown) is accommodated is provided, and a conveyance path 25 through which the recording medium is conveyed upward from the cassette 24 is provided.

  The image forming unit 22 forms, for example, toner images for yellow, magenta, cyan, and black (arrangement is not necessarily in this order) in order from the upstream side in the circulation direction of the intermediate transfer belt 80. Each photosensitive unit 30, each developing unit 33, and one common exposure unit 40 are provided. The photoreceptor unit 30 includes a photoreceptor drum 31, a charging roll 32 that charges the photoreceptor drum 31, and a cleaning device 34 that removes residual toner on the photoreceptor drum 31. The exposure unit 40 includes, for example, four semiconductor lasers (not shown), one polygon mirror 42, an imaging lens (not shown), and mirrors (not shown) corresponding to the respective photoreceptor units 30 in a unit case 41. ) Is stored. The developing unit 33 develops the electrostatic latent image formed on the photosensitive drum 31 by exposure by the exposure unit 40 with a corresponding color toner (for example, negative polarity). A toner cartridge 35 (specifically, 35a, 35b, 35c, and 35d) for replenishing each color component toner to each developing unit 33 is provided on the upper side of the main body housing 21.

  The belt module 23 is obtained by spanning an intermediate transfer belt 80 as an image holding member between a pair of support rolls (one is a drive roll) 81 and 82, and corresponds to the photosensitive drum 31 of each photosensitive unit 30. A primary transfer roll 51 is disposed on the back surface of the intermediate transfer belt 80. By applying a voltage having a polarity opposite to the charging polarity of the toner to the primary transfer roll 51, the toner image on the photosensitive drum 31 is electrostatically transferred to the intermediate transfer belt 80 side. Further, a secondary transfer device 52 constituting a transfer portion is disposed at a portion corresponding to the support roll 82 on the downstream side of the most downstream image forming unit 22 d of the intermediate transfer belt 80, and the toner on the intermediate transfer belt 80 is arranged. The image (primary transfer image) is secondarily transferred (collective transfer) to the recording medium.

  The secondary transfer device 52 includes a transfer roll (secondary transfer roll) 84 disposed in pressure contact with the toner image holding surface side of the intermediate transfer belt 80, and a counter electrode of the transfer roll 84 disposed on the back surface side of the intermediate transfer belt 80. And a back roll (in this example, the support roll 82 is also used). For example, the transfer roll 84 is grounded, and a bias having the same polarity as the charging polarity of the toner is applied to the back roll (support roll 82).

  A belt cleaning device 53 is disposed on the upstream side of the most upstream image forming unit 22 a of the intermediate transfer belt 80, and residual toner on the intermediate transfer belt 80 is removed by the cleaning blade 54.

  The cassette 24 is provided with a delivery roll 61 for delivering the recording medium. A transport roll 62 for conveying the recording medium is disposed immediately after the delivery roll 61 and a secondary transfer portion (transfer section). An alignment roll 63 for supplying the recording medium to the secondary transfer portion at a predetermined timing is disposed in the conveyance path 25 positioned immediately before the recording path. A fixing device 66 is provided in the conveyance path 25 on the downstream side of the secondary transfer site, and a discharge roll 67 is provided on the downstream side of the fixing device 66. By the discharge roll 67, the recording medium is discharged to the paper discharge unit 68 at the top of the main body housing 21.

  A manual feed device 71 is provided on the side of the main body housing 21, and the recording medium on the manual feed device 71 is transported toward the transport path 25 by the feed roll 72 and the transport roll 62. Furthermore, a double-sided recording unit 73 is attached to the main body housing 21. This double-sided recording unit 73 reverses the recording medium on which single-sided recording has been performed by the discharge roll 67 and takes it into the inside by the guide roll 74 before the entrance when selecting the double-sided mode in which image recording is performed on both sides of the recording medium. The recording medium is transported along the internal recording medium return transport path 76 by the transport roll 77 and is supplied again to the alignment roll 63 side.

  Next, the transfer roll 84 disposed in the image forming apparatus 10 and a cleaning device for cleaning the surface of the transfer roll 84 will be described.

  FIG. 2 shows a cleaning device 100 for cleaning the surface of the transfer roll 84 of the present embodiment. As shown in FIG. 2, the cleaning device 100 includes a housing 102 that opens to face the transfer roll 84. A cleaning member 104 serving as a scraping member that scrapes off deposits on the surface of the transfer roll 84 is attached to the attachment portion 102 </ b> A provided in the lower portion of the opening of the housing 102.

  The cleaning member 104 applies a pressure to the transfer roll 84 (in a state of being elastically deformed), contacts the cleaning roll 106 to scrape off deposits on the surface of the transfer roll 84, and a support portion 108 that supports the cleaning blade 106. I have. In the present embodiment, the support portion 108 is formed in an approximately L shape in a side sectional view, and the root portion 106 </ b> A of the cleaning blade 106 is fixed to one end portion of the support portion 108, and the other end portion of the support portion 108. Is fixed to the mounting portion 102A. The transfer roll 84 rotates in the direction of arrow A, and the front end portion 106B side of the cleaning blade 106 is supported by the support portion 108 and is arranged in a posture facing the upstream side in the rotation direction of the transfer roll 84.

  The cleaning blade 106 is constituted by, for example, a substantially rectangular two-layer blade, and includes a cleaning layer that contacts the transfer roll 84 and a back layer disposed on the back side of the cleaning layer. In the cleaning blade 106 of the present embodiment, the cleaning layer that contacts the transfer roll 84 is formed of a rubber material having a thickness of about 0.5 mm, and the back layer is a rubber material having a thickness of about 1.5 mm that is less hard than the cleaning layer. It is formed with. The cleaning blade 106 does not have to be two layers, and may be a single layer, for example.

  In the cleaning device 100, after the toner image (primary transfer image) on the intermediate transfer belt 80 is secondarily transferred to the recording medium by the transfer roll 84 at the secondary transfer portion (transfer portion) (see FIG. 1), the transfer is performed. Deposits such as residual toner on the surface of the roll 84 are scraped off by the cleaning member 104. In the image forming apparatus 10 of the present embodiment, for example, so-called borderless printing is performed in which a part of the toner image on the intermediate transfer belt 80 is transferred to a region including the edge of the recording medium by the transfer roll 84 (see FIG. 10). ). Not only borderless printing, but also normal printing in which the toner image on the intermediate transfer belt 80 is transferred to a region not including the edge of the recording medium by the transfer roll 84 may be performed.

  In FIG. 3, the transfer roll 84 of the present embodiment is shown in a sectional view in a direction orthogonal to the axial direction. As shown in FIG. 3, the transfer roll 84 includes a shaft portion 110 arranged along the longitudinal direction, an elastic layer 112 provided around the shaft portion 110, and an adhesive portion 114 outside the elastic layer 112. And a surface layer 116 bonded thereto. As described above, the transfer roll 84 transfers the toner image on the intermediate transfer belt 80 as an image holding member to a recording medium as a medium. The transfer roll 84 is configured such that the deposit on the surface layer 116 of the transfer roll 84 is scraped off by the cleaning member 104 (see FIG. 2) after the toner image is transferred.

  The axial length of the shaft portion 110 is set to be longer than the axial lengths of the elastic layer 112 and the surface layer 116 (see FIG. 4). Both end portions of the shaft portion 110 in the axial direction are supported by bearings (not shown), and the transfer roll 84 rotates in the direction of arrow A (see FIG. 2).

  The elastic layer 112 is formed of a material that is relatively softer than the shaft portion 110 and has a lower elastic modulus. For example, a foamed resin or the like is used. In the present embodiment, the elastic layer 112 is made of conductive foamed polyurethane, and has a thickness of about 4 mm, for example. In FIG. 3, the thickness of the elastic layer 112 is shown to be large, but actually, a core portion (not shown) made of a material harder than the elastic layer 112 is provided around the shaft portion 110. An elastic layer 112 is provided around the core. For example, the elastic layer 112 has an Asker C hardness of 30 to 40 °, preferably 35 °. The Asker C hardness was measured under the conditions of 22 ° C. and 55% RH by pressing a measuring needle of an Asker C-type hardness meter (manufactured by Kobunshi Keiki Co., Ltd.) on the surface of a 3 mm-thick measurement sheet. I went there.

  The surface layer 116 is formed of a material that is relatively harder and has a smoother surface than the elastic layer 112. The surface layer 116 is composed of a resin tube that covers the elastic layer 112. In the present embodiment, the surface layer 116 is made of, for example, conductive polyimide, and the thickness of the surface layer 116 is set to about 40 μm, for example.

  FIG. 4 shows the transfer roll 84 in a sectional view along the axial direction, and shows a state in which the surface layer 116 is bonded (fixed) to the elastic layer 112 by the bonding portion 114. Yes. As shown in FIG. 4, the axial length of the surface layer 116 is set longer than the axial length of the elastic layer 112. After applying the adhesive constituting the adhesive portion 114 to the peripheral surface of the elastic layer 112, the surface layer 116 made of a tube is pulled in the axially outer sides (both left and right sides in the axial direction) indicated by the arrow B, and the surface layer 116 is inflated with air or the like and inserted into the peripheral surface of the elastic layer 112 to shrink the surface layer 116. At that time, the surface layer 116 is bonded to the peripheral surface of the elastic layer 112 via the bonding portion 114 in a state where the surface layer 116 is pulled outwardly in the axial direction indicated by the arrow B (both left and right sides in the axial direction) and dried. . The transfer roll 84 is manufactured by such a manufacturing method.

  In this transfer roll 84, the surface layer 116 is bonded (fixed) to the peripheral surface of the elastic layer 112 via the bonding portion 114 in a state where it receives tension toward both outer sides in the axial direction. In the transfer roll 84, the occurrence of the undulation of the surface layer 116 is reduced as compared with the configuration in which the surface layer is bonded to the peripheral surface of the elastic layer without pulling the surface layer outward in the axial direction. In the present embodiment, the maximum height waviness Wz of the surface layer 116 is in the range of 1 to 2.5 μm. More specifically, the maximum height waviness Wz of the surface layer 116 is preferably 1 to 2.5 μm, more preferably 1.2 to 2.5 μm, and even more preferably 1.5 to 2.5 μm.

  Here, the maximum height waviness Wz is the maximum height of the waviness curve of the surface layer 116, and is the sum of the maximum peak height Zp and the maximum valley depth Zv of the contour curve at the reference length. The maximum height swell Wz is a value measured according to JIS-B0601′2001. In this embodiment, the surface roughness / contour shape measuring machine Surfcom (manufactured by Tokyo Seimitsu Co., Ltd.) is used to measure the filtering center waviness (filtering waviness curve) of the surface layer 116, and the measurement length is 40 mm. . The maximum height waviness Wz is measured for a plurality of portions of the surface layer 116, and an average value is calculated.

  For the bonding portion 114, an adhesive that firmly bonds the surface layer 116 and the elastic layer 112 is selected. For example, a urethane-based adhesive or the like is used as an adhesive that constitutes the adhesive portion 114.

  In the transfer roll 84 of the present embodiment, the cleaning performance by the cleaning member 104 is improved and the occurrence of filming is suppressed as compared with a configuration in which the maximum height waviness Wz of the surface layer of the transfer roll is larger than 2.5 μm. .

  Further, in the transfer roll 84, the surface layer 116 is bonded (fixed) to the peripheral surface of the elastic layer 112 via the bonding portion 114 in a state where it receives tension toward both outer sides in the axial direction. Thereby, in the present embodiment, the surface layer of the transfer roll is simpler than the configuration in which the surface layer is fixed to the peripheral surface of the elastic layer via the adhesive portion without receiving the tension toward both outer sides in the axial direction. A transfer roll 84 having a structure in which the maximum height waviness Wz of the surface layer 116 is 1 to 2.5 μm is obtained.

  Next, a tension mechanism that pulls the surface layer 116 outward in the axial direction when the transfer roll 84 operates will be described.

  FIG. 5 shows a first example of a pulling device 120 as a pulling mechanism that pulls the surface layer 116 outward in the axial direction when the transfer roll 84 operates. As shown in FIGS. 5A and 5B, the tension device 120 includes a collar 122 as a protrusion attached to both ends in the width direction (both ends in the axial direction) of the surface layer 116 of the transfer roll 84, and A contact body 124 against which each collar 122 is pressed. The collar 122 is composed of a disk-shaped member, and the outer diameter of the collar 122 is set larger than the outer diameter of the surface layer 116. The collar 122 is fixed to the surface layer 116 by adhesion in a state where the axial end portion 116A of the surface layer 116 is inserted into the hole in the radial intermediate portion of the collar 122. A through-hole 122 </ b> A through which the shaft portion 110 of the transfer roll 84 passes is formed at the center of the collar 122. The collar 122 is not bonded to the shaft portion 110.

  The contact body 124 is provided with an inclined portion 124 </ b> A that is inclined toward the outer side in the width direction (the outer side in the axial direction) at a position in contact with the collar 122. More specifically, the inclined portion 124A is inclined in the direction away from the shaft portion 110 of the transfer roll 84 toward the outer side in the width direction (outer side in the axial direction). As the transfer roll 84 is pushed toward the contact body 124 as indicated by an arrow C, the corner 122B on the inner side in the axial direction of the collar 122 is pressed against the inclined portion 124A. The corner 122B on the inner side in the axial direction of the collar 122 is pressed against the inclined portion 124A, whereby the surface layer 116 is pulled outward in the axial direction indicated by the arrow D. That is, the surface layer 116 is spread left and right in the axial direction.

  In the tension device 120, the surface layer 116 is pulled outward in the axial direction indicated by the arrow D when the transfer roll 84 is operated. For this reason, in the image forming apparatus 10 including the pulling device 120 of the present embodiment, the cleaning member 104 is compared with a configuration in which a pulling mechanism that pulls the surface layer of the transfer roll outward in the axial direction is not provided during the operation of the transfer roll. Occurrence of contamination of the recording medium (dirt on the back side) due to the deterioration of the cleaning performance (see FIG. 2) is suppressed. In the tension device 120 of this embodiment, the contact body 124 is provided on both sides in the axial direction of the transfer roll 84, but the contact body 124 may be provided on one side in the axial direction of the transfer roll 84.

  In the image forming apparatus 10 of the present embodiment, so-called borderless printing is performed in which a part of the toner image on the intermediate transfer belt 80 is transferred to a region including the edge of the recording medium by the transfer roll 84. Therefore, in the image forming apparatus 10, the transfer roll has a configuration in which toner easily adheres to the transfer roll 84 as compared with a configuration in which a part of the toner image on the intermediate transfer belt is transferred to an area not including the edge of the medium. The toner adhering to 84 is scraped off by the cleaning member 104 (see FIG. 2).

  FIG. 6 shows a second example of a pulling device 130 as a pulling mechanism that pulls the surface layer 116 outward in the axial direction when the transfer roll 84 operates. In addition, about the same member as the tension | pulling apparatus of a 1st example, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.

  As shown in FIGS. 6A and 6B, the tension device 130 includes ribs 132 as protrusions attached to both ends in the width direction (both ends in the axial direction) of the surface layer 116 of the transfer roll 84. And a contact body 124 against which each 132 is pressed. The rib 132 is formed of an annular body having an outer diameter larger than the outer diameter of the surface layer 116, and an opening 132 </ b> A into which the axial end portion 116 </ b> A of the surface layer 116 is inserted is provided inside the rib 132. With the end portion 116A of the surface layer 116 inserted into the opening 132A of the rib 132, the rib 132 is fixed to the surface layer 116 (surface side) by adhesion.

  In the tension device 130, the transfer roller 84 is pressed toward the contact body 124 as indicated by an arrow C, whereby the corner 132B on the inner side in the axial direction of the rib 132 is pressed against the inclined portion 124A. The corner portion 132B on the inner side in the axial direction of the rib 132 is pressed against the inclined portion 124A, whereby the surface layer 116 is pulled outward in the axial direction indicated by the arrow D. That is, the surface layer 116 is spread left and right in the axial direction. In this tensioning device 130, only a part in the circumferential direction of the ribs 132 on both sides in the axial direction of the surface layer 116 is widened. Therefore, the position where the ribs 132 are pushed up to the inclined portion 124A is the cleaning member in the rotation direction of the transfer roll 84. A position immediately before the contact position 104 (see FIG. 2) is preferable.

  In the tension device 130, the surface layer 116 is pulled outward in the axial direction indicated by the arrow D when the transfer roll 84 is operated. For this reason, in the image forming apparatus 10 including the pulling device 130 of the present embodiment, the cleaning member 104 is compared with a configuration in which a pulling mechanism that pulls the surface layer of the transfer roll outward in the axial direction is not provided during the operation of the transfer roll. Occurrence of contamination of the recording medium (dirt on the back side) due to the deterioration of the cleaning performance (see FIG. 2) is suppressed. In the tension device 130 of this embodiment, the contact body 124 is provided on both sides in the axial direction of the transfer roll 84, but the contact body 124 may be provided on one side in the axial direction of the transfer roll 84.

  FIG. 7 shows a third example of a pulling device 140 as a pulling mechanism that pulls the surface layer 116 outward in the axial direction when the transfer roll 84 operates. In addition, about the same member as the tension | pulling apparatus of a 1st example and a 2nd example, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.

  As shown in FIG. 7, the tension device 140 includes an elastic member 142 attached to both end portions in the width direction (both end portions in the axial direction) of the surface layer 116 of the transfer roll 84, and an outer side in the width direction (axial direction) of the elastic member 142. A pair of attachment portions 144 attached to the outer side. In the present embodiment, the elastic member 142 is formed of a cylindrical body that can expand and contract in the axial direction, and is fixed to an end portion on the outer side in the axial direction of the surface layer 116. In the present embodiment, rubber is used as the elastic member 142. As the elastic member 142, for example, a coil spring may be used instead of rubber.

  The attachment portion 144 is made of a disk-shaped member and includes an opening 144A into which the shaft portion 110 is inserted at the center. With the shaft portion 110 inserted into the opening 144A of the mounting portion 144, the shaft portion 110 and the mounting portion 144 are fixed by adhesion or the like.

  In the tension device 140, the elastic members 142 attached to both ends in the width direction of the surface layer 116 of the transfer roll 84 are attached to a pair of left and right attachment portions 144 on the outer side in the axial direction of the elastic member 142. At that time, the elastic member 142 is fixed to the pair of left and right mounting portions 144 in a state of being extended from the free state. As a result, in a state where the pair of left and right attachment portions 144 are fixed to the shaft portion 110, the elastic members 142 attached to both ends in the width direction of the surface layer 116 contract, and the surface layer 116 has both axial directions indicated by arrows D. Pulled outward.

  In the tension device 140, the surface layer 116 is pulled outward in the axial direction indicated by the arrow D when the transfer roll 84 is operated. For this reason, in the image forming apparatus 10 including the pulling device 140 of the present embodiment, the cleaning member 104 is compared with a configuration in which a pulling mechanism that pulls the surface layer of the transfer roll outward in the axial direction is not provided during the operation of the transfer roll. Occurrence of contamination of the recording medium (dirt on the back side) due to the deterioration of the cleaning performance (see FIG. 2) is suppressed. In the tension device 140 of this embodiment, the elastic member 142 is provided on both sides in the axial direction of the transfer roll 84, but the elastic member 142 may be provided on one side in the axial direction of the transfer roll 84.

  FIG. 8 shows a fourth example of a pulling device 150 as a pulling mechanism that pulls the surface layer 116 outward in the axial direction when the transfer roll 84 operates. In addition, about the same member as the tension | pulling apparatus of a 1st example-a 3rd example, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.

  As shown in FIGS. 8A and 8B, the tensioning device 150 includes a pair of left and right rollers 152 that come into contact with both ends in the width direction of the surface layer 116 of the transfer roll 84. The roller 152 includes a shaft portion 152A and a peripheral surface portion 152B provided outside the shaft portion 152A. The roller 152 is inclined so that the portion on the outer side in the axial direction of the transfer roll 84 is located on the upstream side in the rotation direction indicated by the arrow A with respect to the portion on the inner side in the width direction. In this embodiment, the roller 152 is configured to rotate following the transfer roll 84 by the rotation of the transfer roll 84 indicated by arrow A at the contact portion with the transfer roll 84. The roller 152 may be configured to be rotationally driven around the shaft portion 152A.

  In the tension device 150, the roller 152 rotates at a contact portion with the transfer roll 84 in a direction intersecting with the transfer roll 84 indicated by an arrow A (a direction outward in the axial direction), whereby the surface layer 116 of the transfer roll 84. Is pulled outward in the axial direction indicated by arrow D. For this reason, in the image forming apparatus 10 provided with the pulling device 150 of the present embodiment, the cleaning member 104 is compared with a configuration in which a pulling mechanism that pulls the surface layer of the transfer roll outward in the axial direction is not provided during the operation of the transfer roll. Occurrence of contamination of the recording medium (dirt on the back side) due to the deterioration of the cleaning performance (see FIG. 2) is suppressed. In the tension device 150 of this embodiment, the rollers 152 are provided on both sides in the axial direction of the transfer roll 84, but the rollers 152 may be provided on one side in the axial direction of the transfer roll 84.

  FIG. 9 shows a fifth example of a tension device 160 as a tension mechanism that pulls the surface layer 116 outward in the axial direction when the transfer roll 84 operates. In addition, about the same member as the tension | pulling apparatus of a 1st example-a 4th example, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.

  As shown in FIGS. 9A and 9B, the tension device 160 includes a collar 122 attached to both ends in the width direction (both ends in the axial direction) of the surface layer 116 of the transfer roll 84, and the respective collars 122. And a support 162 for supporting the above. The support 162 includes a groove 162A into which a part of the collar 122 in the circumferential direction is inserted. The position of the groove 162A of the support 162 is disposed at a position where the surface layer 116 is inserted into the groove 162A in a state where the surface layer 116 is pulled outward in the axial direction indicated by the arrow D.

  In the tensioning device 150, the surface layer 116 is inserted into the groove 162 </ b> A of the support 162 in a state where the surface layer 116 is pulled outward in the axial direction indicated by the arrow D. As a result, the surface layer 116 is pulled outward in the axial direction indicated by the arrow D during the operation of the transfer roll 84. That is, the surface layer 116 is spread left and right in the axial direction.

  For this reason, in the image forming apparatus 10 including the pulling device 160 of the present embodiment, the cleaning member 104 is compared with a configuration in which a pulling mechanism that pulls the surface layer of the transfer roll outward in the axial direction is not provided during the operation of the transfer roll. Occurrence of contamination of the recording medium (dirt on the back side) due to the deterioration of the cleaning performance (see FIG. 2) is suppressed. In the tension device 160 of the present embodiment, the supports 162 are provided on both sides of the transfer roll 84 in the axial direction. However, the support 162 may be provided on one side of the transfer roll 84 in the axial direction.

  Although the present invention has been described in detail with respect to specific embodiments, the present invention is not limited to such embodiments, and various other embodiments are possible within the scope of the present invention. It is clear to the contractor.

  In the above-described embodiment, the toner image on the intermediate transfer belt 80 is secondarily transferred to a recording medium by the transfer roll 84, but the present invention is not limited to this configuration. For example, the present invention can be applied to a case where a toner image on a photosensitive drum is transferred to a medium such as a recording medium.

  Next, using the image forming apparatus 10 of this embodiment, after printing 10,000 sheets of A4 recording medium P with the print pattern shown in FIG. 10, the surface of the transfer roll 84 is observed to check the filming state. The experiment that was performed will be described.

  As shown in FIG. 10, in this embodiment, a substantially L-shaped toner image T is formed on the intermediate transfer belt 80 (see FIG. 1), and a part T1 of the toner image T on the intermediate transfer belt 80 is formed. The image is transferred to an area including the edge of the recording medium (paper in this embodiment) P by the transfer roll 84 (edgeless printing). The toner image T2 protrudes from the recording medium P, and the protruded toner image T2 adheres to the transfer roll 84.

  As a cleaning member 104 (see FIG. 2) for cleaning the surface of the transfer roll 84, a cleaning blade 106 composed of a two-layer blade is used. As for the cleaning blade 106, the cleaning layer in contact with the transfer roll 84 is formed of a rubber material having a thickness of about 0.5 mm, and the back layer is formed of a rubber material having a thickness of about 1.5 mm and less hardness than the cleaning layer. ing.

  In the transfer roll 84 of this embodiment, the maximum height waviness Wz of the surface layer 116 in front of the cleaning member 104 in the rotation direction of the transfer roll 84 is set to 1.0 μm. The maximum height swell Wz is a value measured according to JIS-B0601′2001.

  Furthermore, in this embodiment, a tension device 120 (see FIG. 5) is provided that pulls the surface layer 116 outward in the axial direction when the transfer roll 84 is operated. With this image forming apparatus 10, borderless printing was performed under the above printing conditions, and the occurrence of filming on the surface of the transfer roll 84 was confirmed.

  In the comparative example, an image forming apparatus that does not include a pulling device that pulls the surface layer during the operation of the transfer roll is used. In the transfer roll of the comparative example, the maximum height waviness Wz of the surface layer is set to 4.32 μm. Using this image forming apparatus, borderless printing was performed under the same printing conditions as in this example, and the occurrence of filming on the surface of the transfer roll was confirmed.

  FIG. 11 shows the occurrence of filming on the surface of the transfer roll 84 in the present example and the comparative example. The portion “There is an image of the paper passing portion” is a portion where a part T1 of the toner image T shown in FIG. The “non-sheet passing portion image exists” portion is a portion where the toner image T2 protrudes from the recording medium P shown in FIG. The state of occurrence of filming was evaluated in six stages from G0 to G5 in the order of no filming on the surface of the transfer roll 84 to a small state and a large state.

  As shown in FIG. 11, in the image forming apparatus of this example, it was confirmed that the occurrence of filming on the surface of the transfer roll 84 is G0, which is good (◯ in FIG. 11). On the other hand, in the image forming apparatus of the comparative example, the filming occurrence state on the surface of the transfer roll 84 is G5, and the filming occurrence state is deteriorated (× in FIG. 11) as compared with the present example. It was confirmed that

  Next, the maximum height waviness Wz of the surface layer 116 of the transfer roll 84 was changed, and the amount of toner slipping through the cleaning member 104 was investigated. As the toner, a toner having an average volume particle diameter of 5 μm was used. In addition, the solid image is transferred by the transfer roll 84, and the image forming apparatus is stopped at the timing when the cleaning blade 106 is passed in the first round of transfer by the transfer roll 84, and the surface of the transfer roll 84 after passing the cleaning blade 106 is observed. Observed.

  Further, in the tension device 120 (see FIG. 5), the angle of the inclined portion 124A with respect to the axial direction of the transfer roll 84 is changed, and the maximum height waviness Wz of the surface layer 116 of the transfer roll 84 is changed.

FIG. 12 is a graph showing the relationship between the maximum height waviness Wz (μm) of the surface layer 116 of the transfer roll 84 and the toner slip-through amount (pieces / cm ² ). As shown in FIG. 12, when the maximum height waviness Wz of the surface layer 116 of the transfer roll 84 is 2.5 μm or less, toner slipping from the cleaning member 104 on the surface of the transfer roll 84 is suppressed. I understand. The maximum height waviness Wz of the surface layer 116 is a value that is about ½ or less of the average particle diameter of the toner, and about 80% of the toner slipping amount before the measure of this embodiment is suppressed. Further, when the maximum height waviness Wz of the surface layer 116 is up to 2.5 μm, the toner slip-through amount is equivalent to the maximum height waviness Wz of 1.0 μm when the filming does not occur.

  Next, the maximum height waviness Wz of the surface layer 116 of the transfer roll 84 was changed, and the amount of wear of the cleaning blade 106 was investigated. In the image forming apparatus 10, continuous printing was performed under conditions of various maximum height waviness Wz of the surface layer 116. The amount of wear of the cleaning blade 106 was measured by measuring the amount of wear of the cleaning blade 106 with respect to the number of rotations of the transfer roll 84.

FIG. 13 is a graph showing the relationship between the maximum height waviness Wz (μm) of the surface layer 116 of the transfer roll 84 and the wear amount (μm ² / kcycle) of the cleaning blade 106. As shown in FIG. 13, when the maximum height waviness Wz of the surface layer 116 of the transfer roll 84 becomes smaller than 1.0 μm, the amount of wear of the cleaning blade 106 increases rapidly. In a range where the cleaning blade 106 is abruptly worn, there is a possibility that the cleaning performance is deteriorated as compared with the case where the maximum height waviness Wz of the surface layer 116 is 1.0 μm or more. For this reason, the maximum height waviness Wz of the surface layer 116 of the transfer roll 84 is preferably 1.0 μm or more.

10 Image forming apparatus 80 Intermediate transfer belt (image carrier)
84 Transfer roll 104 Cleaning member (scraping member)
106 Cleaning blade (scraping member)
112 Elastic layer 114 Adhesive part 116 Surface layer 120 Tensioner (tension mechanism)
122 Color (projection)
124A Inclined part 130 Tensioning device (Tensioning mechanism)
132 Ribs (protrusions)
140 Tensioner (Tensile mechanism)
142 Elastic member 150 Tensioning device (Tensioning mechanism)
152 Roller 160 Tensioning device (Tensioning mechanism)
P Recording medium (medium)
T Toner image

Claims (7)

An elastic layer;
A surface layer fixed to the outside of the elastic layer via an adhesive portion, and having a maximum height waviness Wz of 1 to 2.5 μm,
A transfer roll configured to transfer a toner image on an image holding member to a medium and to scrape off deposits on the surface layer by a scraping member after transfer.   2. The transfer roll according to claim 1, wherein the surface layer is fixed to a peripheral surface of the elastic layer through the adhesive portion in a state of receiving tension toward both outer sides in the axial direction. A transfer unit comprising the transfer roll according to claim 1 or 2, and transferring a toner image on an image carrier to a medium;
A scraping member for scraping off deposits on the surface layer of the transfer roll;
A pulling mechanism for pulling the surface layer outward in the axial direction during operation of the transfer roll;
An image forming apparatus.   The image forming apparatus according to claim 3, wherein a part of the toner image on the image holding member is transferred to an area including an edge of the medium by the transfer roll.   5. The image according to claim 3, wherein the tension mechanism is configured to press protrusions provided at both ends in the width direction of the surface layer against inclined portions that are inclined toward both outer sides in the axial direction. Forming equipment.   The image forming apparatus according to claim 3, wherein the tension mechanism includes an elastic member that pulls the surface layer outward in the axial direction.   The pulling mechanism includes rollers that are in contact with both end portions in the width direction of the surface layer and inclined so that a portion on the outer side in the axial direction of the transfer roll is positioned on the upstream side in the rotation direction with respect to a portion on the inner side in the width direction. The image forming apparatus according to claim 3 or 4 provided.

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