JP2007069584A - Intermediate transfer rotary drum and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an impact interference or a feathering phenomenon by persistent thermal effect or satellite at the time of impact from occurring, and enhance the transfer efficiency to acquire a high-quality image by reducing the coloring material residue at transfer. <P>SOLUTION: The intermediate transfer rotary drum has numerous depressions with liquid repellent surface in the outer peripheral surface of the drum at a prescribed interval complying with recording resolution. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an intermediate transfer rotary drum and a method for manufacturing the intermediate transfer drum, and in particular, ejects ink as droplets from an ink jet head to form an image on the intermediate transfer rotary drum, and transfers the image onto a recording medium. The present invention relates to an intermediate transfer rotary drum capable of forming a high-quality image and a method for manufacturing the intermediate transfer rotary drum.

  2. Description of the Related Art Conventionally, an image forming apparatus has an inkjet head (droplet ejection head) in which a large number of nozzles (ejection ports) are arranged, and recording is performed from nozzles while relatively moving the inkjet head and a recording medium. 2. Related Art Inkjet printers (inkjet recording apparatuses) that record images on a recording medium by ejecting ink droplets toward the medium are known.

  Such an ink jet recording apparatus normally performs image recording by ejecting ink droplets directly onto a recording medium such as paper (recording paper). When the recording medium is bent, there is a problem that the diameter of the ink dots that land on the recording medium is not stable and high-quality image recording cannot be realized.

  In contrast, for example, using an intermediate transfer rotary drum (intermediate transfer member), ink droplets are temporarily ejected onto the intermediate transfer rotary drum to form an image, and this image is transferred to a recording medium to record an image. In this case, it is easy to maintain a constant distance between the inkjet head and the intermediate transfer rotary drum, and various images can be obtained by transferring the image formed on the intermediate transfer rotary drum to a recording medium. High-quality image recording can be performed on the recording medium.

  Conventionally, in an image recording apparatus using such an intermediate transfer member, various proposals have been made to further improve the quality of the transferred image by devising the surface shape of the intermediate transfer member, for example.

  For example, by setting the surface roughness of the intermediate transfer member within a predetermined range, the surface of the intermediate transfer member is provided with fine irregularities, thereby improving the wettability of the ink droplets on the intermediate transfer member and the transfer image recording quality. Are known (see, for example, Patent Document 1).

  In addition, for example, by providing a fine water-repellent part on the surface of the intermediate transfer member, the image formed on the intermediate transfer member is accurately formed and maintained without being disturbed until it is transferred to the recording medium. In addition, there has been known one that attempts to achieve high image quality of recording by efficiently transferring to a recording medium (see, for example, Patent Document 2).

  Similarly, the surface of the intermediate transfer member is provided by providing a water-repellent portion on the intermediate transfer member and transferring a reversal image formed by ink droplets attached to portions other than the water-repellent portion of the intermediate transfer member to a recording medium. There is known an attempt to record a high-definition image with a photographic tone by suppressing the movement of the ink droplet (see, for example, Patent Document 3).

In addition, for example, a solvent is infiltrated into the absorption layer provided on the surface of the intermediate transfer roller, and the concentrated ink is transferred to the recording paper, and the transfer drum is regenerated by absorbing and evaporating it with a cleaning unit provided below the transfer unit. Those which are used repeatedly are known (see, for example, Patent Document 4).
Japanese Patent Laid-Open No. 7-17030 JP 2004-42454 A JP 2004-50449 A JP-A-5-200999

  However, in the above-described prior art, in ink jet recording using an intermediate transfer member, a fine uneven portion or the like is provided to stabilize the landing position or interference, or a solvent absorption layer is provided to prevent bleeding during transfer or contamination of the recording medium. Although trying to prevent these problems, there is a problem that even if these functions are combined or these functions are combined, image quality deterioration due to tailing or satellite at the time of landing or problems such as color material remaining at the time of transfer are likely to occur.

  For example, the one described in Patent Document 1 has a surface roughness of the intermediate transfer member within a predetermined range, but due to the uniform rough surface properties, landing interference and droplet ejection shape are likely to occur. There is a problem that it is difficult to dry in the case of high-speed printing alone.

  Further, the one described in Patent Document 2 is intended to prevent landing interference and stabilize the landing position. However, since it is difficult to remove the solvent on the transfer body, bleeding at the time of transfer and drying of the recording medium are prevented. It is a problem.

  Similarly, the one described in Patent Document 3 is also intended to prevent landing interference and stabilize the landing position. However, since it is difficult to remove the solvent on the transfer body, bleeding at the time of transfer and recording medium Drying is a problem. Furthermore, since the surface area of the non-water-repellent part is large, colorant residue or the like is likely to occur at the time of transfer, and in the examples, the water-repellent part is formed at equal intervals. There is also a problem that misalignment tends to occur.

  Furthermore, although the thing of the said patent document 4 is effective for solvent removal, there exists a problem that a landing position and a landing shape are not stabilized and a coloring material residue is easy to produce.

  The present invention has been made in view of such circumstances, and prevents tailing at the time of landing and landing interference and blurring due to satellites, and also reduces the remaining coloring material at the time of transfer to increase transfer efficiency and achieve high image quality. An object of the present invention is to provide an intermediate transfer rotating drum capable of forming an image and a method of manufacturing the same.

  In order to achieve the above object, the invention according to claim 1 is characterized in that a number of recesses having a liquid repellent surface are formed on the outer peripheral surface thereof at a predetermined pitch substantially corresponding to the recording resolution. An intermediate transfer rotating drum is provided.

  As a result, it is possible to prevent image defects such as landing interference and bleeding due to the fine liquid repellent structure.

  According to a second aspect of the present invention, the hollow shape is narrower on the inner peripheral side than on the outer peripheral side of the intermediate transfer rotary drum.

  As a result, it is possible to reduce the surface area of the non-liquid-repellent portion that contacts the liquid droplets while ensuring the opening size on the outer peripheral side, and the colorant residue is improved.

  According to a third aspect of the present invention, the hollow shape is different in cross-sectional shape when viewed from the drum end surface side of the upstream and downstream opposing portions in the rotation direction of the intermediate transfer rotary drum, and the hollow shape. The slope on the upstream side in the rotational direction of the shape is formed with a gentler slope.

  As a result, the landing position of the droplet can be offset in the rotation direction of the intermediate transfer rotary drum, so that the droplet can be reliably trapped even when tailing or satellite occurs.

  Moreover, as shown in Claim 4, it is an intermediate transfer rotary drum in any one of Claims 1-3, Furthermore, the solvent absorption part which permeate | transmits a solvent was provided in a part of said hollow shape. Features.

  As a result, the surface area of the non-liquid-repellent part in contact with the liquid droplets can be reduced, so that there is little color material remaining and the solvent can be moved from the absorbing member during transfer, so that it can be efficiently transferred to the transfer medium. . Further, the step of removing the solvent from the recording medium after the transfer can be omitted or the load of removing the solvent can be greatly reduced.

  According to a fifth aspect of the present invention, the position at which the depression is formed is determined from a measurement result of a landing position of a droplet discharged to the intermediate transfer rotary drum.

  As a result, it is possible to reliably land the droplet on the recessed portion and to prevent image defects such as landing interference and bleeding.

  According to a sixth aspect of the present invention, the intermediate transfer rotary drum according to any one of the first to fifth aspects further includes a temperature adjusting means.

  As a result, the landing position is stable against changes in the environmental temperature.For example, when the intermediate transfer rotary drum is set to a high temperature during standby, when the solvent remains in the intermediate transfer rotary drum due to a large amount of printing, etc. But it can be discharged reliably.

  Similarly, in order to achieve the above object, the invention according to claim 7 includes a step of sintering a fine metal powder to form a solvent absorption layer, and a porous film provided to form a solvent absorption layer. A step of forming a solvent-permeable layer thereon, a step of applying a liquid repellent and forming a liquid-repellent layer on the solvent-permeable layer, and a laser at a predetermined pitch corresponding to the recording resolution. And a step of forming a number of depressions in the layer. A method of manufacturing an intermediate transfer rotary drum is provided.

  This makes it possible to manufacture an intermediate transfer rotating drum that can easily prevent image defects such as landing interference and bleeding.

  As described above, according to the present invention, it is possible to prevent image defects such as landing interference and bleeding by a fine liquid repellent structure.

  Hereinafter, an intermediate transfer rotary drum and a method for manufacturing the same according to the present invention will be described in detail with reference to the accompanying drawings. The present invention provides a liquid repellent part having a fine hollow shape on the surface of an intermediate transfer rotating drum (intermediate transfer member) and an absorbing part having solvent permeability in a part thereof, thereby causing problems such as landing interference and bleeding. Is realized, and image recording with high transfer efficiency and little color material remaining is realized.

  FIG. 1 is an overall configuration diagram showing an outline of an ink jet recording apparatus as an embodiment of an image forming apparatus having an intermediate transfer rotating drum according to the present invention.

  As shown in FIG. 1, the inkjet recording apparatus 10 of the present embodiment includes a plurality of print heads (droplet discharge heads) 50 (50Y, 50M, 50C, and 50K) that discharge droplets provided for each color of ink. ), An intermediate transfer drum (intermediate transfer rotating drum) 32 on which a transfer image is formed, and a paper feeding unit 18 for supplying the recording paper 16 on which the transfer image is transferred from the intermediate transfer drum 32 and recorded. And a paper discharge unit 26 for discharging the recording paper 16 after recording.

  As shown in FIG. 1, along the rotation direction of the intermediate transfer drum 32 (the direction indicated by the arrow in the figure), yellow (Y), magenta (M), cyan (C), and black (K) in this order from the upstream side. A print head 50 (50Y, 50M, 50C, 50K) corresponding to each color ink is arranged. Each print head 50 is provided with a cap 30 formed of a flexible member such as rubber so as to surround the side surface.

  While the intermediate transfer drum 32 is rotated, ink of each color is discharged from each print head 50 (50Y, 50M, 50C, 50K), whereby a transfer image is formed on the surface of the intermediate transfer drum 32.

  In addition, the droplet ejection sensor 24 is disposed downstream of the print head 50 in the rotation direction of the intermediate transfer drum 32. The droplet ejection sensor 24 is a reflection type sensor that reads the result of droplet ejection on the intermediate transfer drum 32 and checks for nozzle clogging and other ejection failures. Further, a suction part 34 for sucking ink in the print head 50 during maintenance of the print head 50 and a wiper 36 for cleaning the nozzle surface of the print head 50 are provided on a part of the side surface of the intermediate transfer drum 32. . These will be described in detail later.

  Further, a suction roller 40 and suction for cleaning the surface of the intermediate transfer drum 32 after the transfer image is transferred to the recording paper 16 on the upstream side of the print head 50 along the rotation direction of the intermediate transfer drum 32. A removal roller 42 is disposed. The suction roller 40 includes cleaning water and has water absorption, and cleans the surface of the intermediate transfer drum 32 while wetting it. The suction removal roller 42 has water drops, dust, etc. on the surface of the intermediate transfer drum 32. The foreign matter is sucked and removed.

  Further, the intermediate transfer drum 32 is provided with a temperature control means (for example, a heater) 60. For example, it is preferable to set the intermediate transfer drum 32 at a high temperature during standby.

  As illustrated in FIG. 1, a roll paper (continuous paper) magazine (a container loaded with roll paper) may be used as an example of the paper supply unit 18, and in addition, a plurality of paper widths, paper qualities, and the like are different. A magazine may be added. Further, instead of the roll paper magazine or in combination with this, the paper may be supplied by a cassette in which cut sheets are stacked and loaded.

  In the present embodiment, since a transfer image is once formed on the intermediate transfer drum 32 and transferred to the recording paper, various types of recording paper can be used, and usable recording paper. The degree of freedom increases. Further, as will be described in detail later, the intermediate transfer drum is provided with a fine water-repellent portion, and the non-water-repellent portion has the permeability of the ink solvent. Bleeding and stickiness are reduced.

  The recording paper 16 delivered from the paper supply unit 18 retains curl due to having been loaded in the magazine as roll paper. In order to remove the curl, a decurling unit 20 is provided on the downstream side of the sheet feeding unit 18. The decurling unit 20 applies heat to the recording paper 16 with a heating drum in a direction opposite to the direction of the curl of the magazine. At this time, it is more preferable to control the heating temperature so that the printed surface is slightly curled outward.

  When roll paper is used, a cutter 28 is provided on the downstream side of the decurling unit 20 as shown in FIG. 1, and the roll paper is cut into a desired size by the cutter 28. The cut recording paper 16 is conveyed so that the printing surface is on the upper side of the drawing, and the transfer image formed on the intermediate transfer drum 32 is transferred at the transfer position on the conveyance roller 38. Note that the cutter 28 is not necessary when cut paper is used.

  Each of the print heads 50 (50Y, 50M, 50C, 50K) is a line type head having a length corresponding to the maximum image formable width in the axial direction of the intermediate transfer drum 32. This is a line type head arranged in parallel. That is, in other words, the longitudinal direction of the print head 50 is arranged in a direction substantially orthogonal to the rotational direction of the intermediate transfer drum 32. As will be described in detail later, a large number of nozzles are arranged in a two-dimensional matrix at high density on the ink ejection surface (nozzle surface).

  In the example shown in FIG. 1, the configuration of KCMY standard colors (four colors) is shown, but the combination of ink colors and the number of colors is not limited to the present embodiment, and light ink, Dark ink may be added. For example, a configuration in which a print head that discharges light ink such as light cyan or light magenta may be added.

  Although not shown, an ink tank for storing ink of a color corresponding to each print head 50 (50Y, 50M, 50C, 50K) is provided, and each print head is also passed through an ink conduit not shown. Ink is supplied to 50 (50Y, 50M, 50C, 50K). In addition, an ink storage / loading unit (not shown) having an ink tank is provided to prevent informing means such as a display means or a warning sound generating means for notifying that when the remaining amount of ink is low, or erroneous loading between colors. It is preferable that the mechanism is provided.

  Next, the structure of the print head 50 (50Y, 50M, 50C, 50K) will be described. Since the structure of each print head 50 (50Y, 50M, 50C, 50K) provided for each ink color is common, the following description will be made simply as the print head 50.

  FIG. 2 is a perspective view showing the positional relationship between one print head 50 and the intermediate transfer drum 32. In FIG. 2, the print head 50 is shown in a large size for easy understanding of the outline of the print head 50, and the ratio of the sizes of the print head 50 and the intermediate transfer drum 32 is not accurate. The cap 30 installed around the print head 50 is also not shown.

  As shown in FIG. 2, the print head 50 is arranged so that the nozzle surface (ink ejection surface) 50 </ b> A faces the side surface of the intermediate transfer drum 32 and the longitudinal direction thereof is parallel to the axial direction of the intermediate transfer drum 32. In addition, the short side direction of the nozzle surface 50 </ b> A has a curved shape according to the outer periphery of the intermediate transfer drum 32. Although not shown in FIG. 2, a plurality of nozzles for ejecting ink are formed on the nozzle surface 50A.

  FIG. 3 shows a plan perspective view of the print head 50 of FIG. 2 as seen from the direction of the arrow in the figure. As shown in FIG. 3, the print head 50 includes a nozzle 51 that ejects ink as droplets, a pressure chamber (pressure generating chamber) 52 that applies pressure to the ink when ejecting the ink, and FIG. The pressure chamber units 54 including ink supply ports 53 for supplying ink from the omitted common flow path to the pressure chamber 52 are arranged in a staggered two-dimensional matrix, and the nozzles 51 are densified. Yes.

  In the example shown in FIG. 3, when each pressure chamber 52 is viewed from above, the planar shape thereof is a substantially parallelogram shape, but the planar shape of the pressure chamber 52 is such a parallelogram shape. It is not limited. In the pressure chamber 52, as shown in FIG. 3, a nozzle 51 is formed at one end of the diagonal line, and an ink supply port 53 is provided at the other end.

  FIG. 3 is a view for explaining the arrangement of the pressure chambers 52 and the nozzles 51, and the illustration of the cap 30 displayed in FIG. 1 is omitted here.

  In this embodiment, in order to prevent problems such as landing interference and bleeding, and to realize image recording with high transfer efficiency and a small amount of color material remaining, the surface of the intermediate transfer drum 32 has a fine dent shape. A liquid part and an absorbing part having solvent permeability are provided in a part of the liquid part, which will be described below.

  FIG. 4 is a sectional view showing the structure of the intermediate transfer (rotating) drum 32 of the present embodiment.

  4, the intermediate transfer drum 32 has a solvent absorbing layer 62 formed on the innermost side, a solvent permeable layer 64 formed on the outer side, and a liquid repellent layer 66 formed on the outermost side. Yes.

  The solvent absorbing layer 62 is non-liquid repellent and is formed, for example, by sintering fine stainless steel powder, has a gap of 0.1 to 0.5 μm, and absorbs an ink solvent such as pigment ink. It is configured. Further, the solvent permeable layer 64 is formed by, for example, winding a porous film such as a polyimide porous film around the solvent absorbing layer 62, and has a non-liquid-repellent gap of 0.01 to 0.3 μm. And is configured to allow ink solvent to pass therethrough.

  The outermost liquid repellent layer 66 is formed by coating a fluorine-based resin and heat-curing, and a large number of fine recesses 68 are formed at positions where ink dots are formed. The recess 68 is formed in a wedge shape as a hole penetrating the liquid repellent layer 66, and the solvent permeable layer 64 is exposed on the bottom surface of the recess 68. When the ink droplets 70 ejected from the print head 50 land on the recesses 68, the ink droplets 70 pass through the solvent permeable layer 64 exposed at the bottom of the recesses 68 and are absorbed by the solvent absorption layer 62 therebelow. It has become so.

  When the solvent is absorbed in this way, the ink droplet 70 that has landed in the depression 68 becomes as indicated by a broken line 72 in the figure.

  Further, as shown in FIG. 4, the slopes 68a and 68b of the recess 68 are tapered so that the inner diameter W2 is smaller than the outer diameter W1, and W1> W2. . As described above, since the recess 68 is formed so that the outer side is wider than the inner side, the surface area of the non-liquid-repellent part with which the ink droplets ejected from the print head 50 come into contact can be reduced. The remaining material is improved.

  By forming such inclined portions (inclined surfaces 68a and 68b) in accordance with the landing positions of the ink droplets, the landing of the ink droplets on the inclined portions can be ensured even with a long head.

  However, since the intermediate transfer drum 32 actually rotates during printing, it is more reliable to make the ink droplet landing by making the inclined portion of the recess 68 asymmetrical with respect to the rotational direction than by making it symmetrical. can do.

  Therefore, it is more preferable that the recess 68 is wedge-shaped or the like and is formed asymmetrically in the rotation direction of the intermediate transfer drum 32 (discharged medium conveyance direction), thereby further reducing the influence of tailing and satellite.

  FIG. 5 is a sectional view of the intermediate transfer drum 32 in which the recess 68 (inclined portion) is formed asymmetrically in the rotational direction of the intermediate transfer drum 32 in this manner.

  As shown in FIG. 5, in the recess 68 provided in the liquid-repellent layer 66 of the intermediate transfer drum 32, the slope 68a on the upstream side with respect to the rotation direction of the intermediate transfer drum 32 indicated by the arrow in the drawing is downstream. The slope is gentler than the side slope 69b (that is, the angle θ with respect to the normal line of the outer peripheral surface of the intermediate transfer drum 32 is large).

  Considering the actual landing state of the ink droplet 70, the main (main part) landing of the ink droplet 70 is made straight toward the bottom of the recess 68 as shown by the arrow A in the figure. Since the intermediate transfer drum 32 is rotated in the direction of the arrow in the drawing and the landing of the satellite, the landing is made as shown by the arrow B with a slight deviation from the main landing in the upstream in the rotation direction.

  However, by forming the slope 68a on the upstream side in the rotational direction of the recess 68 to be loose, it is possible to absorb such a deviation in the landing position, and to reliably receive the ink droplet 70 in the recess 68. it can. As a result, it is possible to prevent problems such as landing interference and bleeding.

  FIG. 6 shows a state in which the ink dots formed on the intermediate transfer drum 32 are transferred onto the recording paper 16.

  As shown in FIG. 6, the recording paper 16 conveyed from the right side to the left side of the figure is conveyed so that the printing surface is on the upper side of the figure, and is pressed against the intermediate transfer drum 32 side by the conveyance roller 38 to be intermediate. The ink droplets 70 held in the recesses 68 formed in the outermost liquid repellent layer 66 of the transfer drum 32 are transferred to the printing surface of the recording paper 16.

  At this time, since the recess 68 for holding the ink droplet 70 is formed in a wedge shape such that the outer side of the intermediate rotating drum 32 is wider than the inner side, the ink droplet 70 is easily separated from the recess 68. Good transfer efficiency. In particular, as described above, when the inclined portion of the recess 68 is formed asymmetrically with respect to the rotation direction, a shearing force also acts on the inclined surface 68b on the downstream side of the rotation as shown in the figure. The ink droplet 70 should be separated.

  Furthermore, if the solvent is supplied to the recess 68 from the solvent permeable layer 64 side on the bottom surface side of the recess 68, it is possible to prevent a vacuum from being generated between the ink droplet 70 and the bottom surface of the recess 68. Transfer efficiency can be increased. At this time, if the inside of the intermediate transfer drum 32 is pressurized, the effect can be further enhanced.

  Next, a method for manufacturing the intermediate transfer drum will be described.

  FIG. 7 shows a manufacturing process of the intermediate transfer drum in the present embodiment.

  First, in step S100 of FIG. 7, a fine metal powder, for example, a fine stainless steel powder is sintered, the surface is finished, and the solvent absorption layer 62 is formed. At this time, it forms so that the space | gap of 0.1-0.5 micrometer may be included inside so that a solvent can be absorbed.

  Next, in step S110, a porous film such as a polyimide porous film having a gap of 0.01 to 0.3 μm, for example, is wound around the surface of the solvent absorbing layer 62 to form the solvent permeable layer 64.

  Next, in step S120, the outside of the solvent permeable layer 64 (the outermost layer of the intermediate transfer drum 32) is coated with, for example, a fluorine-based liquid repellent to a thickness of 5 to 10 μm, and subjected to heat curing treatment to perform the liquid repellent layer. 66 is formed.

  Next, in step S130, a recess 68 is formed in the liquid repellent layer 66 by tilting such as excimer laser or UV-YAG laser or gradation mask processing.

  For example, as shown in FIG. 8A, the tilting process is performed by irradiating the laser beam with an angle θ from the outer periphery of the intermediate transfer drum 32 to thereby irradiate the intermediate transfer drum 32 as shown in FIG. A wedge-shaped depression 68 is formed in the outermost liquid-repellent layer 66.

  In the gradation mask processing, for example, as shown in FIG. 9, laser light is transmitted through a gradation mask 80 and an imaging lens 82 in which a pattern is formed asymmetrically with respect to the intermediate transfer drum 32 in the rotational direction of the intermediate transfer drum 32. By irradiating, a wedge-shaped depression 68 is formed. The laser light irradiation may be performed so as to remove a part of the solvent permeable layer 64 in order to reliably remove the liquid contact layer 66.

  The depressions 68 are formed at a predetermined pitch corresponding to the recording resolution. As an example of the dimension of the depression 68 to be formed, for example, if the resolution of the image is 600 to 1200 npi (nozzle per inch), the pitch is 20 to 40 μm, and the drop amount for this is preferably 1 to 3 pl (picoliter). The ink diameter at this time is about 10 to 15 μm. When three color (YMC) ink is applied, the ink diameter is about 10 to 30 μm, and it is necessary to quickly absorb the solvent corresponding to the ink diameter of 10 to 20 μm. Is formed.

  Note that the position where the depression 68 is formed is determined from the measurement result of the ink landing position, and the misalignment is made to correspond by correcting the droplet amount and the number of droplets. Further, the processing position of the recess 68 may be determined for each print head to be mounted, or may be determined based on variations such as a manufacturing lot. In the case of tilt processing, the position of a galvanometer mirror or the like that scans the laser beam is corrected, and in the case of gradation mask processing, the position of the mask or the like with respect to the intermediate transfer drum 32 is corrected.

  Finally, in step S140, the solvent permeable layer 64 and the solvent absorbing layer 62 may be impregnated with a weak liquid repellent. This is effective in preventing coloring material adhesion.

  Next, the cap 30 will be described. As described above, the cap 30 is attached to the print head 50 so as to be in close contact with the side surface of the print head 50 and surround the periphery.

  FIG. 10A is a perspective view showing the cap 30 attached to the print head 50, and FIG. 10B is a cross-sectional view taken along the line 10B-10B '.

  As shown in FIG. 10A, the cap 30 is a rectangular frame-shaped member that surrounds the print head 50, and can be moved up and down along the side surface of the print head 50 while closely contacting the side surface of the print head 50. It is installed like that. At the time of ink suction, when the intermediate transfer drum 32 rotates until the suction portion 34 provided on the side surface of the intermediate transfer drum 32 is positioned below the print head 50, the cap 30 moves downward, and the lower portion of the cap 30 is moved downward. It is in close contact with the side surface of the intermediate transfer drum 32.

  Therefore, the lower portion of the cap 30 has a curved shape in accordance with the curvature of the side surface in the circumferential direction of the intermediate transfer drum 32. As described above, the cap 30 is formed of a flexible member such as rubber because it needs to be in close contact with the side surface of the print head 50 and the side surface (circumferential surface) of the intermediate transfer drum 32 during ink suction.

  FIG. 10B shows a state during ink suction. As shown in FIG. 10B, at the time of ink suction, the cap 30 moves downward (on the side surface side of the intermediate transfer drum 32), and the lower portion of the cap 30 comes into close contact with the side surface of the intermediate transfer drum 32, thereby 34 is included therein, and the space between the suction portion 34 and the nozzle surface 50A of the print head 50 is sealed. In this state, a pump (not shown) communicating with the suction unit 34 is driven to suck the ink in the print head 50 into the suction unit 34.

  Next, the wiper 36 will be described. FIG. 11A is a perspective view of the wiper 36 provided on the intermediate transfer drum 32.

  In the example shown in FIG. 11A, the wiper 36 has a length corresponding to the longitudinal direction of the print head 50 (not shown) in the suction portion 34 along the axial direction of the intermediate transfer drum 32. It is rotatably attached around the shaft 36a.

  FIG. 11B is a side cross-sectional view showing a state in which the wiper 36 is driven (wiping). As shown in FIG. 11 (b), the wiper 36 has, for example, an oval cross section, and a shaft 36a is disposed on the side close to one end thereof. At the time of wiping, the wiper 36 rotates around the shaft 36a as indicated by an arrow in the drawing, and the other end contacts the nozzle surface 50A of the print head 50. As the intermediate transfer drum 32 rotates in the direction indicated by the arrow in the drawing, the ink 35 and the like adhering to the nozzle surface 50A is scraped off.

  As described above, the wiper 36 moves while contacting the nozzle surface 50A of the print head 50 and scrapes the ink 35. Therefore, in order to increase the degree of adhesion to the nozzle surface 50A, at least the contact portion of the wiper 36 with the nozzle surface 50A. Is preferably made of a flexible member such as rubber.

  The attachment position of the wiper 36 is not limited to the inside of the suction part 34 as described above. When the wiper 36 is attached to the suction part 34 and becomes obstructive when sucking ink, as shown in FIG. A gap 37 may be provided. In this case, it is preferable to provide a passage 37 a that connects the gap portion 37 and the suction portion 34 so that the ink scraped off by the wiper 36 flows into the suction portion 34 and is collected.

  When water pigment ink is used, if the humidifying function is added to the suction portion 34 of the intermediate transfer drum 32, the nozzle 51 is prevented from drying even if the solvent absorption of the intermediate transfer drum 32 increases. Can be effective.

  Also, by providing temperature control means for both the print head 50 and the intermediate transfer drum 32, the landing position can be stabilized against changes in the environmental temperature, and the temperature control means is set to a high temperature especially during standby. If the inside of the intermediate transfer drum 32 is pressurized, it is effective when the solvent remains inside the intermediate transfer drum 32 due to mass printing or the like.

As described above, according to this embodiment, a liquid-repellent layer having a fine depression is provided on the surface of the intermediate transfer drum (intermediate transfer member), and at least a part of the liquid-repellent layer has solvent permeability. Since the absorbing portion is provided, image defects such as landing interference and bleeding can be prevented by the fine liquid repellent structure and the solvent absorbing structure. Further, since the surface area of the non- liquid -repellent part in contact with the ink is small, there is little color material remaining, and the solvent can be moved from the absorbing member at the time of transfer.

  Further, since the recess has a shape that is narrower on the inner surface side than the outer surface of the intermediate transfer drum, the surface area of the non-liquid-repellent portion that comes into contact with the ink can be further reduced, so that the remaining colorant is further improved and ink droplets are retained. Trap position accuracy is further stabilized. Since there is a solvent absorbing layer, stable landing can be maintained even if the surface area of the non-liquid repellent part is small.

  In addition, the landing position can be offset in the rotational direction by forming the recess asymmetrically with respect to the rotation direction of the intermediate transfer drum, and in particular by loosening the inclined surface of the recess on the upstream side in the rotation direction. The ink droplet trapping effect is improved. This is particularly effective for a system in which the clearance between the print head and the intermediate transfer drum is narrowed to improve the landing position accuracy. Furthermore, by making the recess into a wedge shape, a shearing force is applied during transfer, and reliable peeling transfer is possible even with highly viscous ink.

Further, as described above, the dents are formed at a predetermined pitch corresponding to a substantially recording resolution, and the position where the dents are formed is determined from the measurement result of the ink landing position. Further, the processing position of the dent is determined from the variation of each mounting head or manufacturing lot. Thereby, since the ink can be landed reliably in the depressed portion, the above-described effect can be realized with certainty. Since the droplet ejection position is stable, the positional deviation can be easily corrected by the droplet amount and the number of droplets.

  In addition, since the cleaning unit has a suction function, it can be efficiently removed together with the solvent remaining in the absorbing member even when the color material remains in the depression. Further, since the temperature control function is given to the print head and the intermediate transfer drum, the landing position is stabilized against the environmental temperature change. Further, by setting the temperature control means of the intermediate transfer drum to a high temperature during standby, even if the solvent remains in the intermediate transfer drum due to a large amount of printing or the like, it can be reliably discharged. It is more effective to put the intermediate transfer drum inside in a pressurized state during standby.

  In the above embodiment, the print heads corresponding to the four colors of ink are arranged on one intermediate transfer drum to form a transfer image at a time, and the image is transferred. The present invention can also be suitably applied to a tandem type system in which an intermediate transfer drum is arranged for each print head corresponding to ink and a single color is transferred to recording paper and arranged in series. is there.

  The intermediate transfer rotating drum and the manufacturing method thereof according to the present invention have been described in detail above. However, the present invention is not limited to the above examples, and various improvements and modifications can be made without departing from the gist of the present invention. Of course.

1 is an overall configuration diagram showing an outline of an ink jet recording apparatus as an embodiment of an image forming apparatus having an intermediate transfer drum according to the present invention. FIG. 4 is a perspective view showing a positional relationship between one print head and an intermediate transfer drum. FIG. 3 is a plan perspective view of the print head of FIG. 2 as viewed from the direction of the arrow in the drawing. FIG. 3 is a cross-sectional view illustrating a structure of an intermediate transfer drum according to the present embodiment. FIG. 6 is a cross-sectional view showing the structure of another example of the intermediate transfer drum of the present embodiment. FIG. 4 is a cross-sectional view illustrating a state in which an image is transferred from an intermediate transfer drum to a recording medium. 5 is a flowchart showing a manufacturing process of the intermediate transfer drum of the present embodiment. (A), (b) is explanatory drawing which shows a mode that a hollow is formed with a laser. It is explanatory drawing which shows the mode of the other example which forms a hollow with a laser. (A) is a perspective view which shows a mode that the cap was attached to the print head, (b) is sectional drawing along the 10B-10B 'line. (A) is a perspective view which shows a wiper, (b) is the sectional drawing, (c) is sectional drawing which shows another wiper.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Inkjet recording device, 16 ... Recording paper, 18 ... Paper feed part, 20 ... Decal processing part, 24 ... Droplet detection sensor, 26 ... Paper discharge part, 28 ... Cutter, 30 ... Cap, 32 ... Intermediate transfer drum, 34 ... Suction unit, 36 ... Wiper, 38 ... Conveying roller, 40 ... Suction roller, 42 ... Suction removal roller, 50 ... Print head, 50A ... Nozzle surface, 51 ... Nozzle, 52 ... Pressure chamber, 53 ... Ink supply port, 54 ... pressure chamber unit, 60 ... heater, 62 ... solvent absorbing layer, 64 ... solvent permeable layer, 66 ... liquid repellent layer, 68 ... depression, 70 ... ink droplet

Claims (7)

  An intermediate transfer rotary drum characterized in that a number of recesses having a liquid-repellent surface are formed on the outer peripheral surface thereof at a predetermined pitch substantially corresponding to the recording resolution.   The intermediate transfer rotary drum according to claim 1, wherein the hollow shape is narrower on an inner peripheral side than on an outer peripheral side of the intermediate transfer rotary drum.   The recess shape has a different cross-sectional shape as viewed from the drum end surface side of the upstream and downstream facing portions in the rotation direction of the intermediate transfer rotating drum, and the recess shape has an inclined surface on the upstream side in the rotation direction. The intermediate transfer rotary drum according to claim 1, wherein the inclined side is formed to have a gentler inclination.   The intermediate transfer rotary drum according to any one of claims 1 to 3, further comprising a solvent absorbing portion that allows a solvent to pass through a part of the hollow shape.   5. The intermediate transfer rotation according to claim 1, wherein the position at which the depression is formed is determined from a measurement result of a landing position of a droplet discharged to the intermediate transfer rotary drum. drum.   The intermediate transfer rotary drum according to claim 1, further comprising a temperature control unit. Sintering fine metal powder to form a solvent absorption layer;
Providing a porous film to form a solvent permeable layer on the solvent absorbing layer;
Applying a liquid repellent and forming a liquid repellent layer on the solvent permeable layer;
Forming a plurality of depression shapes in the liquid repellent layer with a laser at a predetermined pitch according to the recording resolution;
A process for producing an intermediate transfer rotary drum, comprising:

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