JP2005280245A - Image forming apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which smoothes ink on a recording medium while crack or separation of the ink surface is avoided by using an energy application curing type ink or a phase change type ink, and which can realize image fixation with a sense of gloss, and to provide an image formation method. <P>SOLUTION: Imaging is carried out by discharging the ink to the recording medium (20) from discharging heads (12K, 12M, 12C, 12Y and 12CL). The ink is cured by semi solidifying curing means (16A-16E) in a semi solid state of a viscosity level whereat color mixture is prevented even in a liquid contact state of the ink with the other color ink. The ink is pressured and smoothed by a smoothing means (17) in this soft ink state in which the ink is not completely cured. Thereafter, the ink in the semi solid state is cured and fixed by a main curing means (18) to a level whereat an image quality degradation by ink rubbing or the like is prevented even in transfer handling. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus and method, and more particularly to an image forming apparatus and an image forming method for forming an image on a recording medium by ejecting ink from an inkjet head.

Patent Document 1 discloses an ink jet printer that includes an image forming unit that ejects ink onto a sheet-like paper (printed material), and a pressurizing unit that pressurizes the printed material image formed by the image forming unit. ing. This printer is configured to give gloss to an image by pressurizing and flattening the surface irregularities of the ink of the image formed on the substrate by the image forming unit.
Japanese Patent Laid-Open No. 2001-1512

  However, Patent Document 1 is a technique that assumes that pigment ink or dye ink is used as drawing ink. On the other hand, a technique using an ultraviolet curable ink in an inkjet image forming apparatus is known. Use of the ultraviolet curable ink can form merits on various recording media and can select a wide variety of recording media. However, when ultraviolet curable ink is used within the scope of the technical content disclosed in Patent Document 1, problems such as cracking and peeling of the ink surface occur during pressure flattening.

  The present invention has been made in view of such circumstances, and uses an energy-added curable ink typified by an ultraviolet curable ink or a phase change ink typified by a solid ink to avoid cracking or peeling of the ink surface. However, an object of the present invention is to provide an image forming apparatus and method capable of realizing glossy image fixing and preventing image quality deterioration due to color mixture between different color inks during color image formation.

  In order to achieve the above object, an image forming apparatus according to a first aspect of the present invention includes an ejection head having a nozzle for ejecting ink, and transporting at least one of the ejection head and the recording medium. A transport unit that relatively moves the recording medium; and an ink that is disposed on the downstream side of the discharge head in the relative transport direction of the recording medium with respect to the discharge head, A semi-solid solution curing unit that cures to a semi-solid solution state having a viscosity that does not cause color mixing even in a liquid contact state, and a smoothing unit that is disposed downstream of the semi-solid solution curing unit and smoothes the ink on the recording medium Is disposed downstream of the smoothing means and the smoothing means, and does not cause image quality deterioration due to ink rubbing or the like even in transport handling of ink on the recording medium And curing means for curing fixing whenever, characterized by comprising a.

  According to the present invention, a semi-solution curing means and a main curing means are provided as means for curing the ink ejected from the ejection head, and the ink is gradually cured by these two curing means to control the progress of the curing. doing. Immediately after ink ejection by the ejection head, the ink is cured to a semi-solid solution state (a semi-cured state that is not completely cured, or a high viscosity state) by a semi-solid solution curing means downstream of the ejection head. Since the ink in the semi-solid solution state is relatively flexible and easily deformed, the smoothing means is acted in this semi-solid solution state to make the unevenness of the ink surface flat. After the smoothing process is completed, the ink is cured and fixed by the main curing means to such an extent that image quality deterioration due to ink rubbing or the like does not occur even in the transport handling. Thus, the ink surface can be surely smoothed, and the surface non-uniformity caused by the difference in the amount of ink overlap can be eliminated. In addition, since smoothing (surface uniformity) is possible in a soft ink state that is not fully cured, peeling and cracking of the ink surface can be prevented during pressure flattening.

  In the present invention, “handling” refers to [1] rubbing between a roller, a conveying guide or the like and an image surface in a downstream conveying step of the main curing means, [2] rubbing between prints in a print stacking unit, [3] It means rubbing by various objects when the finished print is actually handled, and “main curing” means a level at which the cured droplets are cured to such an extent that the image does not deteriorate even when the above handling is performed. . Therefore, “main curing” does not necessarily mean that the curing reaction is completed.

  In the case of forming a color image, it is preferable to repeat the ink ejection and the semi-solid solution curing process for each color using a plurality of colors of ink, and perform the smoothing process after the semi-solution process of the final color. . According to this aspect, since the ink of the next color is ejected when the ink of the previously ejected color is in a semi-solid solution state, color mixing is not performed when these different color inks are overlapped, and intercolor bleeding is performed. Image quality deterioration can be prevented. In addition, since the ink ejected onto the recording medium becomes a semi-solid solution state in a short time by the semi-solid solution curing means, there is also an effect of preventing bleeding even on a highly permeable recording medium.

  In the present invention, energy-applying curable ink typified by ultraviolet curable ink or phase change ink typified by solid ink can be suitably used as the drawing ink. The energy-applied curable ink is an ink having a property of being cured by applying energy by radiation such as electromagnetic waves including visible light and ultraviolet rays, X-rays, electron beams, etc., semi-solid solution curing means and main curing means The progress of curing is controlled by applying energy stepwise using.

  Solid ink is solid at room temperature and has the property of lowering viscosity upon heating. Therefore, when solid ink is used, a heating unit is used as the semi-solid solution curing unit, and a cooling unit is used as the main curing unit.

  As a configuration example of the ejection head, a full-line type inkjet head having a nozzle row in which a plurality of nozzles for ejecting ink are arranged over a length corresponding to the entire width of the recording medium can be used. In the case of forming a color image, there is a configuration in which a full-line inkjet head is arranged for each color of a plurality of colors.

  A full-line type inkjet head is usually arranged along a direction perpendicular to the relative feeding direction (relative conveyance direction) of the recording medium, but at a certain angle with respect to the direction perpendicular to the conveyance direction. There may also be a mode in which the ink jet is arranged along an oblique direction with the. Further, there is a mode in which a plurality of short recording head units having nozzle rows that are less than the length corresponding to the full width of the recording medium are combined to form a nozzle row corresponding to the full width of the recording medium as a whole of these units. obtain.

  The “recording medium” is a medium (which can be called a printing medium, an image forming medium, a recording medium, an image receiving medium, or the like) that receives an image recorded by the action of the ejection head, and is a continuous sheet, a cut sheet, a seal sheet, Various types of media are included regardless of the material and shape, such as a resin sheet such as an OHP sheet, a film, a cloth, a printed circuit board on which a wiring pattern is formed by a discharge head, and the like.

  The conveying means for relatively moving the recording medium and the ejection head is an aspect for conveying the recording medium to the stopped (fixed) ejection head, an aspect for moving the ejection head relative to the stopped recording medium, or Any of the modes in which both the ejection head and the recording medium are moved is included.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the smoothing unit includes a pressurizing unit that pressurizes the ink on the recording medium. To do.

  According to a third aspect of the present invention, there is provided the image forming apparatus according to the second aspect, wherein the smoothing unit further includes a heating unit that heats the ink on the recording medium. To do.

  According to the second aspect of the present invention, the smoothing can be performed only by the pressurizing unit that pressurizes the ink without using the heating unit. According to the third aspect of the present invention, according to the configuration in which the heating unit and the pressurizing unit are combined, smoothing can be performed more efficiently depending on the types of ink and recording medium. For example, in the case of using a kind of ink that is cured by heating, the curing reaction can be promoted while the planarization is advanced, and the energy applied to the main curing means can be reduced.

  A fourth aspect of the invention relates to an aspect of the image forming apparatus according to the first, second, or third aspect, and further includes an ink supply unit that supplies energy-applied curable ink to the ejection head.

  When using energy-applying curable ink for drawing ink, a relatively low energy that is less than the energy required for the main curing is applied by a semi-solid solution curing means, and color mixing occurs even when the ink is in contact with other color inks. It is hardened to a semi-solid solution state at a level where the viscosity is kept to such an extent that it does not cause odor. Then, a relatively high energy sufficient for the main curing is applied by the main curing means after the smoothing treatment to cure and fix the ink.

  According to a fifth aspect of the present invention, in the image forming apparatus according to the fourth aspect, the ejection head is provided for each of a plurality of colors of ink, and the plurality of ejection heads for each color are provided with energy. Are arranged from the upstream side in the order of the ink colors having a low curing sensitivity, and the semi-solid solution curing means are respectively arranged downstream of each ejection head.

  In an apparatus configuration for forming a color image using a plurality of colors of ink, there is an aspect in which an ejection head is provided for each color. There is a phenomenon in which the curing sensitivity varies depending on the color of the ink due to the difference in energy absorption efficiency. Therefore, as described in claim 5, by setting the discharge heads in order from the upstream side in the order of colors with low curing sensitivity and arranging the semi-solid solution curing means downstream of each discharge head, the curing sensitivity is set. As the ink becomes duller, the number of times it passes through the processing region of the semi-solid solution curing means increases.

  For this reason, as the image forming process by the discharge head for each color progresses sequentially, the curing of the ink is promoted according to the number of times of passage through the processing region of the semi-solid solution curing means, and the ink is disposed after the final semi-solution curing means. Further, the liquid state difference (semi-solid solution state) between colors during the smoothing process by the smoothing means can be leveled.

  A sixth aspect of the present invention relates to an aspect of the image forming apparatus according to any one of the first to fifth aspects, and is in accordance with at least one condition among the type of the recording medium, the type of ink, and the ink landing amount. And a control means for controlling at least one of the smoothing conditions of the smoothing means and the energy applied by the semi-solid solution hardening means.

  The “type of recording medium” can be identified from the viewpoint of material, size, thickness, reflectance, adhesion, permeability, and the like. The means for ascertaining the type of recording medium is not limited to the means for actually measuring the thickness and reflectance of the recording medium (detection means), and is organized by type by automatically determining the type of recording medium used. The configuration may be such that the characteristics of each recording medium are grasped by referring to the recorded data table or the like. In addition, a configuration in which the user inputs the paper type and thickness of the recording medium to be used by operating a predetermined input device or the like is also possible.

  As a means for acquiring the information indicating the “ink type”, for example, the shape of the ink tank cartridge (a specific shape that can identify the ink type), or a barcode or IC chip incorporated in the cartridge is used. A means for reading physical property information can be used. In addition, a configuration in which an operator inputs necessary information using a predetermined input device (user interface) is also possible.

  The “ink landing amount” can be grasped from the ink discharge amount information based on the image data to be printed. Based on these print-related conditions, by controlling various conditions so as to perform an appropriate smoothing process and / or semi-solid solution curing process, it is possible to prevent peeling and cracking of ink that occurs in an excessive smoothing process, Better image fixing is possible.

  A seventh aspect of the present invention relates to an aspect of the image forming apparatus according to the first, second, or third aspect. In the image forming apparatus according to the first aspect, the phase change ink is further supplied to the ejection head. Characterized in that the discharge head discharges the phase change ink in a high-temperature molten state, and the main curing unit performs main curing of the phase change ink by cooling.

  When phase change ink is used, it is held in a high-temperature molten state in the discharge head and discharged from the nozzle as liquid. The semi-solid solution curing means applies heat to the ink to the extent that the phase change ink ejected from the ejection head is maintained in a semi-solid solution state. The main curing unit cools the ink on the recording medium so that the semi-solid solution ink is cured and fixed to such an extent that image quality deterioration due to ink rubbing or the like does not occur even in transport handling.

  An eighth aspect of the invention relates to an aspect of the image forming apparatus according to any one of the first to seventh aspects, wherein an ejection head for ejecting clear ink is provided downstream of the ejection head for ejecting colored ink. It is characterized by being.

  A discharge head that discharges clear ink for leveling the surface is provided after the discharge head that discharges the color ink necessary for drawing a color image. A mode in which clear ink is ejected onto an area where the amount of ejected ink is smaller than other regions, the amount of ink ejected at each drawing point is made substantially uniform, and then smoothing processing is performed by a smoothing unit is preferable.

  A ninth aspect of the present invention relates to an aspect of the image forming apparatus according to any one of the first to eighth aspects of the present invention, wherein the retreating unit moves the smoothing unit from a predetermined smoothing processing position to a predetermined retreating position. A drive mechanism is provided.

  When the smoothing means is configured to be movable, and when it is not necessary to flatten the ink (gloss imparting), the smoothing means is moved to the retracted position and the smoothing process is omitted. As a result, curing and fixing are performed by the main curing means while leaving the unevenness of the ink surface. Thus, the structure which can select use / non-use of a smoothing means as needed is preferable.

  The invention according to claim 10 provides a method invention for achieving the object. That is, the invention according to claim 10 ejects ink from a discharge head having an ink discharge nozzle toward a recording medium, and conveys at least one of the discharge head and the recording medium to An image forming method for forming an image on the recording medium by relatively moving the recording medium, and discharging the energy-applied curable ink or phase change ink onto the recording medium by the discharge head; A semi-solid solution curing process for curing the ink ejected in the ejection process to a semi-solid solution state having a viscosity that does not cause color mixing even when in contact with other color inks; and a semi-solid solution state on the recording medium A smoothing process that pressurizes certain ink to smooth the ink, and the ink on the recording medium is transported and handled after the smoothing process. Characterized in that it also includes a main curing treatment step of curing the fixing to the extent that does not cause image quality deterioration due to ink rubbing or the like.

  According to the present invention, the ink is cured in a semi-solid solution state by a semi-solid solution curing unit disposed downstream of the discharge head, and after the process of smoothing the unevenness of the ink in this semi-solid solution state, the main curing is performed. Since the main curing is performed by the means, the surface non-uniformity caused by the difference in the amount of ink overlap can be eliminated. Further, since smoothing (surface uniformization) is possible in a soft ink state that is not fully cured, it is possible to prevent ink peeling and cracking during pressure flattening.

  Further, when forming a color image using a plurality of colors of ink in the present invention, when the ink of the previously ejected color is in a semi-solid solution state, the next color ink is sequentially superimposed and drawn, Image quality deterioration due to intercolor bleeding can be prevented.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[Overall configuration of inkjet recording apparatus]
FIG. 1 is an overall configuration diagram of an image forming apparatus according to an embodiment of the present invention. As shown in the figure, the image forming apparatus 10 is provided corresponding to each ink of black (K), magenta (M), cyan (C), yellow (Y), and clear (transparent; CL). In addition, a plurality of inkjet heads (hereinafter referred to as heads) 12K, 12M, 12C, 12Y, and 12CL, and ultraviolet curable ink (so-called UV ink) supplied to each head 12K, 12M, 12C, 12Y, and 12CL are stored. The ink storage / loading unit 14 to be placed, the semi-solid solution light sources 16A, 16B, 16C, 16D, and 16E arranged on the downstream side of each head, and the semi-solution light source 16E downstream of the final head (clear head 12CL) A pressure fixing unit 17 disposed in the pressure fixing unit 17, a main curing light source 18 disposed in a subsequent stage of the pressure fixing unit 17, a paper feeding unit 22 that supplies recording paper 20 as a recording medium, and The decurling unit 24 for removing the curl of the paper 20, the nozzle surfaces (ink ejection surfaces) of the heads 12K, 12M, 12C, 12Y, and 12CL, and the light emitting surfaces of the semi-solution light sources 16A to 16E are arranged to face each other. The suction belt transport unit 26 transports the recording paper 20 while maintaining the flatness of the recording paper 20, and the paper discharge unit 28 discharges the recorded recording paper (printed matter) to the outside. .

  The UV curable ink is an ink containing a component (UV curable component such as monomer, oligomer, low molecular weight homopolymer or copolymer) that is cured (polymerized) by application of UV energy and a polymerization initiator. When it receives light, it starts polymerization, thickens with the progress of polymerization, and eventually hardens.

  The ink storage / loading unit 14 includes ink tanks 14K, 14M, 14C, 14Y, and 14CL that store inks of colors (including transparent colors) corresponding to the heads 12K, 12M, 12C, 12Y, and 12CL. The tank communicates with the heads 12K, 12M, 12C, 12Y, and 12CL through a required pipe line 30. Further, the ink storage / loading unit 14 includes notifying means (display means, warning sound generating means) for notifying when the ink remaining amount is low, and has a mechanism for preventing erroneous loading between colors. ing. Note that the clear head 12CL does not give a coloring point in the formation of a color image, but considers the ink ejection amount of other colored inks (K, M, C, Y), and ink at each drawing point. Transparent ink is applied so as to make the droplet ejection amount substantially uniform.

  In FIG. 1, a roll paper (continuous paper) magazine 32 is shown as an example of the paper supply unit 22, but a plurality of magazines having different paper width, paper quality, and the like may be provided side by side. Further, instead of the roll paper magazine or in combination therewith, the paper may be supplied by a cassette in which cut papers are stacked and loaded.

  When multiple types of recording paper are used, an information recording body such as a barcode or wireless tag that records paper type information is attached to the magazine, and the information on the information recording body is read by a predetermined reader. Therefore, it is preferable to automatically determine the type of paper to be used and perform ink ejection control so as to realize appropriate ink ejection according to the type of paper.

  The recording paper 20 delivered from the paper supply unit 22 retains curl due to having been loaded in the magazine 32. In order to remove the curl, heat is applied to the recording paper 20 by the heating drum 34 in the direction opposite to the curl direction of the magazine 32 in the decurling unit 24. At this time, it is more preferable to control the heating temperature so that the printed surface is slightly curled outward.

  In the case of an apparatus configuration using roll paper, as shown in FIG. 1, a cutter 38 is provided, and the roll paper is cut into a desired size by the cutter 38. The cutter 38 includes a fixed blade 38A having a length equal to or greater than the conveyance path width of the recording paper 20, and a round blade 38B that moves along the fixed blade 38A. The fixed blade 38A is provided on the back side of the print. The round blade 38B is arranged on the print surface side with the conveyance path interposed therebetween. Note that the cutter 38 is not necessary when cut paper is used.

  After the decurling process, the cut recording paper 20 is sent to the suction belt conveyance unit 26. The suction belt conveyance unit 26 has a structure in which an endless belt 43 is wound between rollers 41 and 42, and at least a portion of each head 12K, 12M, 12C, 12Y, and 12CL facing the nozzle surface is a horizontal plane ( Flat surface).

  The belt 43 has a width that is greater than the width of the recording paper 20, and a plurality of suction holes (not shown) are formed on the belt surface. A suction chamber (not shown) is provided inside the belt 43 spanned between the rollers 41 and 42, and the recording paper 20 is placed on the belt 43 by sucking the suction chamber with a fan to make a negative pressure. Is adsorbed and retained.

  The power of the motor (not shown in FIG. 1, described as reference numeral 134 in FIG. 9) is transmitted to at least one of the rollers 41 and 42 around which the belt 43 is wound, so that the belt 43 rotates counterclockwise in FIG. The recording paper 20 driven in the direction and held on the belt 43 is conveyed from right to left in FIG.

  Each of the heads 12K, 12M, 12C, 12Y, and 12CL has a length corresponding to the maximum paper width of the recording paper 20 targeted by the image forming apparatus 10, and at least the maximum size recording paper 20 is provided on the nozzle surface. This is a full-line head in which a plurality of nozzles for ink ejection are arranged over a length exceeding one side (the full width of the drawable range).

  The heads 12K, 12M, 12C, 12Y, and 12CL are black (K), magenta (M), cyan (C), yellow (Y), and clear (CL) colors from the upstream side along the feeding direction of the recording paper 20. The heads 12 </ b> K, 12 </ b> M, 12 </ b> C, 12 </ b> Y, and 12 </ b> CL are fixedly installed so as to extend along a direction substantially orthogonal to the conveyance direction of the recording paper 20. This head arrangement order is arranged from the upstream side in the order of colors with low curing sensitivity.

  A color image can be formed on the recording paper 20 by discharging different color inks from the heads 12K, 12M, 12C, 12Y, and 12CL while conveying the recording paper 20 by the suction belt conveyance unit 26. Note that the clear ink is ejected to an area where the colored ink is not landed or an area where the amount of ejected colored ink is small in order to maintain the smoothness of the ink surface.

  As described above, according to the configuration in which the full-line heads 12K, 12M, 12C, 12Y, and 12CL having nozzle rows that cover the entire width of the paper are provided for each color, the recording paper 20 is placed in the paper feeding direction (sub-scanning direction). An image can be recorded on the entire surface of the recording paper 20 by performing the operation of moving relative to the heads 12K, 12M, 12C, and 12Y only once (that is, by one sub-scan). Such a single-pass image forming apparatus 10 can perform higher-speed printing than the shuttle scan method in which drawing is performed while reciprocating the recording head in the main scanning direction, and can improve print productivity.

  In this example, the configuration of the combination of KMCY standard colors (four colors) and clear (CL) ink is exemplified, but the combination of the ink color and the number of colors is not limited to the present embodiment. Dark ink may be added. For example, it is possible to add an ink jet head that discharges light ink such as light cyan and light magenta.

  The semi-solid solution light sources 16A to 16E arranged downstream of each head have a length corresponding to the maximum paper width of the recording paper 20 like the head, and extend in a direction substantially orthogonal to the conveyance direction of the recording paper 20. It is fixed to exist. As the semi-solid solution light sources 16 </ b> A to 16 </ b> E, LED elements or LD elements having a narrow emission wavelength region as compared with the main curing light source 18 are preferably used. However, the center wavelength and the emission wavelength region of the semi-solution light sources 16A to 16E and the main curing light source 18 are selected according to the design of the ink used.

  Each of the semi-solid-solubilized light sources 16A to 16E is in a semi-solid-solubilized state (not causing color mixing even in a liquid contact state with other color inks) by the upstream heads 12K, 12M, 12C, 12Y, and 12CL disposed adjacent to each other. UV light having an energy of a degree of (viscosity).

  That is, the semi-solid solution light sources 16A to 16E are in a flexible (easy to deform) ink state in which the ink ejected onto the recording paper 20 by the preceding heads 12K, 12M, 12C, 12Y or 12CL is not fully cured. In addition, the mixing of other color inks ejected from the following heads 12M, 12C, 12Y, and 12CL on the recording paper 20 is prevented from being mixed to prevent color bleeding. In addition, the ink on the recording paper 20 is semi-cured.

  Before the recording paper 20 passes through the upstream head and enters under the next head, light is irradiated from the semi-solid solution light sources 16A to 16E to make the ink on the recording paper 20 semi-cured, and the next stage. Dropping with a different color head is performed.

  In the example of FIG. 1, after droplet ejection by the black head 12K, the black ink is semi-solidified through light irradiation by the semi-solid solution light source 16A, and then droplet ejection by the magenta head 12M is performed. Similarly, after droplet ejection by the magenta head 12M, droplet ejection by the cyan head 12C is performed through light irradiation by the semi-solid solution light source 16B, and droplet ejection by the yellow head 12Y is performed by light irradiation by the latter half solution light source 16C. . After droplet ejection by the yellow head 12Y, light irradiation by the semi-solution light source 16D is performed, droplet ejection by the clear head 12CL is performed, and light irradiation is performed by the semi-solution light source 16E.

  The ink ejected from the head existing upstream in the conveyance direction of the recording paper 20 increases the number of times of passing through the semi-solid solution region, but as described above, the heads are arranged in the order of colors with low curing sensitivity. Therefore, the ink on the recording paper 20 is in a semi-solid solution state in which the difference in curing between colors is small and leveled when passing through the final semi-solution light source 16E.

  The pressure fixing unit 17 (smoothing means) provided at the subsequent stage of the final semi-solid solution light source 16E includes a roller 45 whose surface is coated with a highly peelable resin. The roller 45 has a hollow structure and is provided with a heater 46 such as a halogen lamp in the center to pressurize the image surface of the recording paper 20 while applying heat. The ink surface is heated and pressed by the pressure fixing unit 17 to flatten the unevenness of the ink surface. Moreover, when smoothing is possible only by pressurization without applying heat, it is not necessary to heat. In addition, when printing on porous paper with dye-based ink, the weather resistance of the image is prevented by closing the paper hole by pressurization and preventing contact with ozone or other substances that cause dye molecules to break. Has the effect of improving.

  The pressure fixing unit 17 has a mechanism (for example, a variable structure that applies a pressing force of the roller 45 by a spring load) that can adjust the pressure, and an appropriate pressure according to the thickness of the recording paper 20 and the amount of ink. Controlled by pressure.

  A main curing light source 18 is provided after the pressure fixing unit 17. The main curing light source 18 uses a metal halide lamp, a mercury lamp, or the like that has a wider emission wavelength range than the semi-solid solution light sources 16A to 16E and has a large irradiation light quantity.

  The recording paper 20 that has been smoothed by the pressure fixing unit 17 is irradiated with light sufficient to completely cure the ink by the main curing light source 18, and the main fixing is performed.

  Further, the roller 45 of the pressure fixing unit 17 is configured to be moved to a predetermined retreat position that does not contact the recording paper 20 by a moving mechanism (not shown). When performing the smoothing process of the ink surface, the pressure is applied by placing the roller 45 at a predetermined position (smoothing process position) where the roller 45 is brought into contact with the recording paper 20. On the other hand, when the flattening process of the ink surface is unnecessary, the roller 45 is retracted to the retracted position and cured and fixed by the main curing light source 18 without applying pressure. As a result, it is possible to perform drawing with the unevenness of the ink surface remaining.

  Note that the pressure fixing unit 17 may have a structure in which the pressure fixing unit 17 can be detached (removed) instead of the above-described retraction mechanism as means for switching between pressing / non-pressing. In other words, when the smoothing process is unnecessary, a mode in which the pressure fixing unit 17 (or a part thereof) is detached from the image forming apparatus 10 and the smoothing process is omitted is also possible.

  In this way, the printed matter generated through the main curing process by the main curing light source 18 (the process of curing and fixing to such an extent that the image quality is not deteriorated due to ink rubbing or the like in the transport handling) is discharged from the paper discharge unit 28. Although not shown in FIG. 1, the paper discharge unit 28 is provided with a sorter for collecting images according to orders.

[Head structure]
Next, the structure of the head will be described. Since the structures of the respective heads 12K, 12C, 12M, 12Y, and 12CL for each color are common, the heads are represented by reference numeral 50 in the following.

  FIG. 2 (a) is a plan perspective view showing an example of the structure of the head 50, and FIG. 2 (b) is an enlarged view of a part thereof. 3 is a perspective plan view showing another structural example of the head 50, and FIG. 4 is a cross-sectional view showing a three-dimensional configuration of one droplet discharge element (an ink chamber unit corresponding to one nozzle 51) (FIG. 2). It is sectional drawing in alignment with line 4-4 in the inside.

  In order to increase the dot pitch printed on the recording paper 20, it is necessary to increase the nozzle pitch in the head 50. As shown in FIGS. 2A and 2B, the head 50 of this example includes a plurality of ink chamber units each including a nozzle 51 serving as an ink droplet ejection port, a pressure chamber 52 corresponding to each nozzle 51, and the like. It has a structure in which (droplet discharge elements) 53 are arranged in a zigzag matrix (two-dimensionally), and is thereby projected so as to be arranged along the head longitudinal direction (direction perpendicular to the paper feed direction). High density of substantial nozzle interval (projection nozzle pitch) is achieved.

  The form in which one or more nozzle rows are formed over a length corresponding to the entire width of the recording paper 20 in a direction substantially orthogonal to the feeding direction of the recording paper 20 is not limited to this example. For example, instead of the configuration of FIG. 2 (a), as shown in FIG. 3, recording paper is formed by connecting short head units 50 'in which a plurality of nozzles 51 are two-dimensionally arranged in a staggered manner. You may comprise the line head which has a nozzle row of the length corresponding to the full width of 20.

  The pressure chamber 52 provided corresponding to each nozzle 51 has a substantially square planar shape (see FIGS. 2 (a) and 2 (b)), and is connected to the nozzle 51 at both corners on a diagonal line. An outlet and an inlet (supply port) 54 for supply ink are provided.

  As shown in FIG. 4, each pressure chamber 52 communicates with a common flow channel 55 through a supply port 54. The common channel 55 communicates with an ink tank (not shown in FIG. 4, not shown in FIG. 6 and indicated by reference numeral 60) serving as an ink supply source, and the ink supplied from the ink tank 60 passes through the common channel 55 in FIG. Then, it is distributed and supplied to each pressure chamber 52.

  An actuator 58 having an individual electrode 57 is joined to a pressure plate (vibration plate) 56 constituting the top surface of the pressure chamber 52. By applying a driving voltage to the individual electrode 57, the actuator 58 is deformed to change the volume of the pressure chamber 52, and ink is ejected from the nozzle 51 due to the pressure change accompanying this. For the actuator 58, a piezoelectric body such as a piezoelectric element is preferably used. After ink discharge, new ink is supplied from the common channel 55 to the pressure chamber 52 through the supply port 54.

As shown in FIG. 5, a large number of ink chamber units 53 having such a structure are arranged in a row direction along the main scanning direction and an oblique column direction having a constant angle θ that is not orthogonal to the main scanning direction. The structure is arranged in a lattice pattern. With a structure in which a plurality of ink chamber units 53 are arranged in the direction of the angle θ at a fixed pitch d in the main scanning direction, the pitch P _N of the nozzles projected to an alignment in the main scanning direction and the d × cos [theta] Become.

That is, the main For scanning direction, the nozzles 51 can be treated equivalently to those arranged linearly at a pitch P _N. With such a configuration, it is possible to realize a high-density nozzle configuration in which 2400 nozzle rows are projected per inch (2400 nozzles / inch) so as to be aligned in the main scanning direction.

  When the nozzles are driven by a full line head having a nozzle row having a length corresponding to the entire printable width, (1) all the nozzles are driven simultaneously, (2) the nozzles are sequentially moved from one side to the other. (3) The nozzles are divided into blocks, and each block is sequentially driven from one side to the other, etc., and one line or one in the sheet width direction (direction perpendicular to the sheet conveyance direction) Nozzle driving for printing individual strips is defined as main scanning.

  In particular, when driving the nozzles 51 arranged in a matrix as shown in FIG. 5, the main scanning as described in (3) above is preferable. That is, nozzles 51-11, 51-12, 51-13, 51-14, 51-15, 51-16 are made into one block (other nozzles 51-21,..., 51-26 are made into one block, Nozzles 51-31,..., 51-36 as one block,...), And the nozzles 51-11, 51-12,. One line is printed in the width direction of 20.

  On the other hand, repetitively moving the above-described full line head and the paper to repeatedly perform one line or one band-like printing formed by the above-described main scanning is defined as sub-scanning.

  In implementing the present invention, the nozzle arrangement structure is not limited to the illustrated example. In the present embodiment, a method of ejecting ink droplets by deformation of an actuator 58 typified by a piezo element (piezoelectric element) is adopted. However, in the practice of the present invention, the method of ejecting ink is not particularly limited. Instead of the piezo jet method, various methods such as a thermal jet method in which ink is heated by a heating element such as a heater to generate bubbles and ink droplets are ejected by the pressure can be applied.

[Configuration of ink supply system]
FIG. 6 is a schematic diagram showing the configuration of the ink supply system in the image forming apparatus 10. The ink tank 60 is a base tank that supplies ink to the head 50 and is installed in the ink storage / loading unit 14 described with reference to FIG. In the form of the ink tank 60, there are a system that replenishes ink from a replenishing port (not shown) and a cartridge system that replaces the entire tank when the remaining amount of ink is low. A cartridge system is suitable for changing the ink type according to the intended use. In this case, it is preferable that the ink type information is identified by a barcode or the like, and ejection control is performed according to the ink type. The ink tank 60 in FIG. 6 is equivalent to the ink storage / loading unit 14 in FIG. 1 described above.

  As shown in FIG. 6, a filter 62 is provided between the ink tank 60 and the head 50 in order to remove foreign matters and bubbles. The filter mesh size is preferably equal to or smaller than the nozzle diameter (generally about 20 μm). Although not shown in FIG. 6, a configuration in which a sub tank is provided in the vicinity of the head 50 or integrally with the head 50 is also preferable. The sub-tank has a function of improving a damper effect and refill that prevents fluctuations in the internal pressure of the head.

  Further, the image forming apparatus 10 is provided with a cap 64 as a means for preventing the nozzle 51 from drying or preventing an increase in ink viscosity near the nozzle, and a cleaning blade 66 as a means for cleaning the nozzle surface 50A. . The maintenance unit including the cap 64 and the cleaning blade 66 can be moved relative to the head 50 by a moving mechanism (not shown), and is moved from a predetermined retracted position to a maintenance position below the head 50 as necessary.

  The cap 64 is displaced up and down relatively with respect to the head 50 by an elevator mechanism (not shown). The cap 64 is lifted to a predetermined raised position when the power is turned off or during printing standby and is brought into close contact with the head 50, thereby covering the nozzle surface 50 </ b> A with the cap 64.

  The cleaning blade 66 is made of an elastic member such as rubber, and can slide on the ink discharge surface (nozzle plate surface) of the head 50 by a blade moving mechanism (not shown). When ink droplets or foreign substances adhere to the nozzle plate, the nozzle plate surface is wiped by sliding the cleaning blade 66 on the nozzle plate to clean the nozzle plate surface.

  During printing or standby, when a specific nozzle is used less frequently and the ink viscosity in the vicinity of the nozzle increases, preliminary discharge is performed toward the cap 64 to discharge the deteriorated ink.

  Further, when bubbles are mixed in the ink (pressure chamber) in the head 50, the cap 64 is applied to the head 50, and the ink (ink in which the bubbles are mixed) is removed by suction with the suction pump 67, and is removed by suction. Ink is fed to the collection tank 68. In this suction operation, the deteriorated ink that has increased in viscosity (solidified) is sucked out when the ink is initially loaded into the head 50 or when the ink is used after being stopped for a long time.

  If the head 50 is not ejected for a certain period of time, the ink solvent near the nozzles evaporates and the viscosity of the ink near the nozzles increases. Will not discharge. Therefore, before this state is reached (within the viscosity range in which ink can be discharged by the operation of the actuator 58), the actuator 58 is operated toward the ink receiver to discharge ink in the vicinity of the nozzle whose viscosity has increased. “Preliminary discharge” is performed. In addition, after the dirt on the surface of the nozzle plate is cleaned by a wiper such as a cleaning blade 66 provided as a cleaning means for the nozzle surface 50A, the foreign matter is prevented from entering the nozzle 51 by the wiper rubbing operation. Also, preliminary discharge is performed. Note that the preliminary discharge may be referred to as “empty discharge”, “purge”, “spitting”, or the like.

  In addition, if bubbles are mixed into the nozzle 51 or the pressure chamber 52 or if the viscosity increase of the ink in the nozzle 51 exceeds a certain level, ink cannot be ejected by the preliminary ejection, and the suction operation described below is performed.

  That is, when bubbles are mixed in the ink in the nozzle 51 or the pressure chamber 52, or when the ink viscosity in the nozzle 51 rises to a certain level or more, the ink can be ejected from the nozzle 51 even if the actuator 58 is operated. Disappear. In such a case, a suction means for sucking ink in the pressure chamber 52 with a pump or the like is brought into contact with the nozzle surface of the head 50 to suck ink mixed with bubbles or thickened ink.

  However, since the above suction operation is performed on the entire ink in the pressure chamber 52, the amount of ink consumption is large. Therefore, when the increase in viscosity is small, it is preferable to perform preliminary discharge as much as possible.

[Example of structure of semi-solid solution hardening part]
Here, the structural example of a semi-solution hardening part is demonstrated. In addition, since the structure of each semi-solution light source 16A-16E is common, these are represented with the code | symbol 16 on behalf of them. FIG. 7 is a partial cross-sectional view showing a detailed structure example of the semi-solid solution light source 16, and FIG. 8 is a cross-sectional view taken along the arrow 8A in FIG.

  As shown in these drawings, the semi-solid solution light source 16 includes a plurality of ultraviolet LED elements 72 arranged in a line along the longitudinal direction of the head 50 inside the light shielding enclosure 70, and these ultraviolet LED elements. A condensing cylindrical lens 84 is arranged below the 72 rows. Reference numeral 78 denotes a substrate on which the ultraviolet LED element 72 is supported.

  A slit-like opening 76 serving as a light exit is formed at the bottom of the light-shielding enclosure 70, and a light-shielding beak 86 convex in the light exit direction is provided around the opening 76. Further, an ultraviolet absorbing coding 88 is provided on the bottom surface of the light shielding enclosure 70 facing the recording paper 20.

  The divergent light emitted from the ultraviolet LED elements 72 is condensed in a line along a direction substantially orthogonal to the paper feeding direction by the action of the cylindrical lens 84 and is irradiated onto the recording paper 20. Instead of the cylindrical lens 84, it is also possible to use a lens group having at least one aspherical surface having a light refracting surface shape and having the same condensing power.

  A desired irradiation range and light intensity (intensity) distribution are realized for the ultraviolet irradiation area by selectively causing the ultraviolet LED elements 72 described in FIGS. 7 and 8 to emit light or controlling the light emission amount of each element. be able to.

  By appropriately controlling the light emission position and light emission amount of the ultraviolet LED element 72 according to the size of the recording paper 20, the droplet ejection range by the head 50, and the amount of ink, adverse effects on the head 50 ( Curing of ink in the nozzles 51) is suppressed as much as possible.

  The configuration of the semi-solution light source 16 is not limited to the configuration using the bullet-type ultraviolet LED elements 72 as shown in FIGS. 7 and 8, and the LED elements are arranged one-dimensionally on the substrate. Also good. Further, a configuration using an LD (laser diode) instead of the LED is also possible.

[Explanation of control system]
Next, the control system of the image forming apparatus 10 will be described.

  FIG. 9 is a principal block diagram showing the system configuration of the image forming apparatus 10. The image forming apparatus 10 includes a communication interface 110, a system controller 112, an image memory 114, a motor driver 116, a heater driver 118, a pressure driving unit 119, a print control unit 120, an image buffer memory 122, a head driver 124, and a media detection unit 126. And a light source control unit 128 and the like.

  The communication interface 110 is an interface unit that receives image data sent from the host computer 130. As the communication interface 110, a serial interface such as USB, IEEE1394, Ethernet, and wireless network, and a parallel interface such as Centronics can be applied. In this part, a buffer memory (not shown) for speeding up communication may be mounted. Image data sent from the host computer 130 is taken into the image forming apparatus 10 via the communication interface 110 and temporarily stored in the image memory 114. The image memory 114 is a storage unit that temporarily stores an image input via the communication interface 110, and data is read and written through the system controller 112. The image memory 114 is not limited to a memory made of a semiconductor element, and a magnetic medium such as a hard disk may be used.

  The system controller 112 is a control unit that controls the communication interface 110, the image memory 114, the motor driver 116, the heater driver 118, the pressure driving unit 119, and the like. The system controller 112 includes a central processing unit (CPU) and its peripheral circuits, and performs communication control with the host computer 130, read / write control of the image memory 114, and the like, as well as a transport system motor 134 and a heater 46. Then, a control signal for controlling the pressure mechanism 138 and the like of the pressure fixing unit 17 is generated.

  The motor driver 116 is a driver (drive circuit) that drives the motor 134 in accordance with instructions from the system controller 112. The heater driver 118 is a driver for driving the heater 46 and other heaters in the roller 45 of the pressure drum 17 and the pressure fixing unit 17 in accordance with instructions from the system controller 112.

  The pressurizing drive unit 119 is a unit that drives the pressurizing mechanism 138 in accordance with an instruction from the system controller 112 to vary the pressurizing pressure, and moves the pressurizing mechanism 138 between the retracted position and the smoothing processing position. .

  The print control unit 120 has a signal processing function for performing various processes and corrections for generating a print control signal from the image data in the image memory 114 under the control of the system controller 112, and the generated print A control unit that supplies a control signal (dot data) to the head driver 124. The print control unit 120 performs required signal processing, and controls the ink discharge amount and discharge timing of the head 50 for each color via the head driver 124 based on the image data. Thereby, a desired dot size and dot arrangement are realized.

  The print control unit 120 includes an image buffer memory 122, and image data, parameters, and other data are temporarily stored in the image buffer memory 122 when image data is processed in the print control unit 120. In FIG. 9, the image buffer memory 122 is shown in a mode accompanying the print control unit 120, but it can also be used as the image memory 114. Also possible is an aspect in which the print control unit 120 and the system controller 112 are integrated to form a single processor.

  The head driver 124 drives the ejection drive actuator 58 of each head 50 based on the dot data given from the print control unit 120. The head driver 124 may include a feedback control system for keeping the head driving condition constant.

  Image data to be printed is input from the outside via the communication interface 110 and stored in the image memory 114. At this stage, for example, RGB image data is stored in the image memory 114. The image data stored in the image memory 114 is sent to the print control unit 120 via the system controller 112, and the print control unit 120 converts it into dot data for each ink color using a known dither method, error diffusion method, or the like. Converted.

  In this way, the head 50 is driven and controlled based on the dot data generated by the print control unit 120, and ink is ejected from the head 50. An image is formed on the recording paper 20 by controlling ink ejection from the head 50 in synchronization with the conveyance speed of the recording paper 20.

  The media detection unit 126 is means for detecting the paper type and size of the recording paper 20. For example, means for reading information such as a bar code attached to the magazine 32 of the paper supply unit 22, sensors (paper width detection sensors, sensors for detecting the thickness of the paper, papers) disposed at appropriate locations in the paper conveyance path A sensor for detecting the reflectance of the light source is used, and an appropriate combination thereof is also possible. Further, instead of or in combination with these automatic detection means, it is possible to specify information such as paper type and size by inputting from a predetermined user interface.

  Information acquired by the media detection unit 126 is notified to the system controller 112 and / or the print control unit 120, and is used for ink ejection control, control of the semi-solid solution light source 16, control of the pressurization mechanism 138, and the like.

  The light source control unit 128 turns on (ON) / turns off (OFF) the semi-solid solution light source 16, turns on the semi-solid light source control circuit that controls the lighting position, the amount of light emission at the time of lighting, and the like. ) / Light extinction (OFF), and a main curing light source control circuit for controlling the light emission amount at the time of lighting. The light source control unit 128 controls the light emission of each light source (16, 18) according to a command from the print control unit 120.

[Control Example of Image Forming Apparatus 10]
Next, a control example of the image forming apparatus 10 configured as described above will be described. FIG. 10 is a flowchart illustrating an example of a control algorithm of the image forming apparatus 10. Here, an example is shown in which the semi-solid solution condition and the pressure heating condition are controlled based on information such as the type of paper (media) and the amount of ink landing.

  As shown in the figure, first, in the medium type determination process (step S10), the type of recording medium to be used is determined. For this determination method, for example, automatic detection by optical reflectance detection of the recording paper 20, magazine detection, menu designation by a user interface, or the like is used.

  Based on the media type determination result of step S10, a determination value = A corresponding to the media type to be used is determined (step S12). The image forming apparatus 10 includes an information storage unit (internal memory or external memory) that stores data of a media type table in which a media type and a determination value are associated with each other. It is determined.

  In parallel with or following the above-described media type determination process (step S10), a sheet thickness determination process (step S20) is performed. As the determination method, for example, automatic detection by detecting the thickness of the recording paper 20 or magazine detection is used. Based on the result of the paper thickness determination in step S20, a determination value = B corresponding to the paper thickness is determined (step S22).

  Further, the ink droplet amount is determined based on the data of the image to be printed (step S30), and the determination value = C corresponding to the droplet amount is determined in consideration of the type of ink to be used. (Step S32).

  The pressurizing pressure is determined using the determination values A, B, and C thus obtained. For example, in order to set the pressurizing pressure to an appropriate value, a predetermined weight is applied to the droplet amount and the paper thickness, and the droplet amount varies depending on the media type. The calculation is performed using a pressurized pressure determination expression such as the following expression [Expression 1] which is a conditional expression obtained by multiplying the term as a coefficient (step S40).

[Equation 1] (α1 × A) × (γ1 × C) + β1 × B
However, the coefficients α1, γ1, and β1 are predetermined constant values, respectively.

  The result of the pressurized pressure determination formula [Equation 1] is obtained, and the pressurized pressure adjustment value P corresponding to the result is determined (step S42).

  As described above, with respect to the method for controlling the pressure during the pressure fixing, for example, the pressure is applied by the spring load of the nip roller (45), and the pressure pressure adjustment value P obtained in step S42 is set. The spring can be expanded and contracted according to the value to adjust the pressure. In this way, it is possible to prevent ink peeling and cracking by not greatly changing the pressure condition applied to the ink (controlling the fluctuation range of the pressure condition within a certain range).

  Further, the heating temperature is determined using the determination values A, B, and C obtained in steps S12, S22, and S32. For example, in order to set the heating temperature to an appropriate value, the media type, the paper thickness, and the amount of droplets are weighted and are related to each other in an independent manner. (Step S50).

[Equation 2] α2 × A + β2 × B + γ2 × C
However, the coefficients α2, γ2, and β2 are predetermined constant values.

  The result of the heating temperature determination formula [Equation 2] is obtained, and the heating temperature adjustment value T corresponding to the result is determined (step S52).

  Regarding the method for controlling the heating temperature during pressure fixing, as described above, a heater 46 such as a halogen lamp is arranged at the center of the pressure fixing roller 45, and the heating temperature adjustment value T obtained in the above step S52. The temperature adjustment temperature of the heater 46 can be adjusted according to the value of.

  Further, the additional energy is determined using the determination values A, B, and C obtained in steps S12, S22, and S32. For example, since the effect of the paper thickness is almost not involved in determining the additional energy to an appropriate value, the media type and the droplet volume are roughly independent with a certain weighting, so the following equation [3] Calculation is performed using the energy determination formula (step S60).

[Equation 3] α3 × A + γ3 × C
However, the coefficients α3 and γ3 are predetermined constant values, respectively.

  The result of the added energy determination formula [Equation 3] is obtained, and the added energy adjustment value E corresponding to the result is determined (step S62).

  According to the value of the additional energy adjustment value E, the irradiation amount of the semi-solution light source 16 can be adjusted.

  As described above, by optimizing the pressure heating condition of the pressure fixing unit 17 and the irradiation energy condition of the semi-solid solution light source 16 based on information on the characteristics of the media and the amount of ink landing, stable fixing processing can be performed. Ink peeling and cracking can be prevented.

  In the above description, an example in which ultraviolet curable ink is used has been described. However, the present invention is not limited to photocurable ink, but is cured by irradiation with radiation such as an electron beam or X-ray or heating. Other energy imparting curable inks can be used, and a semi-solid solution curing part and a main curing part suitable for activating the curing agent (activating the polymerization) depending on the ink used. Provided.

  In implementing the present invention, not only ink having a property of being cured by polymerization, but also phase change ink typified by solid ink can be used. Since the solid ink is solid at room temperature and has a property of becoming low viscosity when heated, the conveying system is heated to such an extent that the ink landed on the recording paper 20 is not completely cured, and the solid ink is formed on the recording paper 20. The discharged ink is maintained in a high-viscosity liquid state and conveyed to the pressure fixing unit 17. And after performing a smoothing process in such a flexible liquid state, it sends to a main hardening part (main fixing part). In this case, a fixing unit including a cooling unit is installed in the main curing unit. The cooling means includes, for example, an air cooling method for forcibly cooling the recording medium by cooling air on the recording medium, or a water cooling method for cooling the surface of the recording medium by circulating cooling water around the recording medium such as a transport system. is there. Of course, various cooling methods other than this can be applied.

  FIG. 11 shows a configuration example of an image forming apparatus when phase change ink is used. In FIG. 11, members that are the same as or similar to those in FIG. In the image forming apparatus 10 ′ shown in FIG. 11, the heating unit 160 is disposed in the conveyance unit facing the nozzle surfaces of the heads 12 </ b> K, 12 </ b> M, 12 </ b> C, 12 </ b> Y, 12 </ b> CL, and downstream (downstream) of the pressure fixing unit 17. A cooling unit 180 is disposed as a main curing unit. Although not shown, each head 12K, 12M, 12C, 12Y, 12CL and each ink supply section (14K, 14M, 14C, 14Y, 14CL) are heaters (heating) for liquefying phase change ink. Means).

  The phase change ink is held in a high-temperature molten state in each of the heads 12K, 12M, 12C, 12Y, and 12CL, and is ejected as droplets from the heads 12K, 12M, 12C, 12Y, and 12CL by driving the actuator 58.

  The heating unit 160 includes a temperature-controllable heater, and maintains the ink ejected from the heads 12K, 12M, 12C, 12Y, and 12CL in a semi-solid solution state having a viscosity that does not cause color mixing with other color inks. The heat necessary for printing is applied to the ink on the recording paper 20.

  In other words, the ink that has landed on the recording paper 20 is semi-solidified by the heat from the heating unit 160 and is smoothed by the pressure fixing unit 17 in a state where the semi-solid solution state is maintained.

  The cooling unit 180 of this example is configured to include fans 181 and 182 that are vertically opposed to each other with the recording paper 20 interposed therebetween. By cooling with cooling air from the print surface side and the back surface side of the recording paper 20 by these fans 181 and 182, the ink on the recording paper 20 is solidified and fixed by phase change.

  FIG. 12 is a principal block diagram illustrating a system configuration of the image forming apparatus 10 ′ illustrated in FIG. 11. In FIG. 12, parts that are the same as or similar to those in FIG. 9 are given the same reference numerals, and descriptions thereof are omitted.

  Instead of the light source control unit 128, the semi-solution light source 16 and the main curing light source 18 of FIG. 9, the example of FIG. 12 includes a conveyance temperature control unit 129, a heating unit 160, and a cooling unit 180, respectively.

  The conveyance temperature control unit 129 controls the ON / OFF of the heating unit 160 and the heat generation amount (heating temperature), the ON / OFF of the fans 181 and 182 of the cooling unit 180, the rotation speed (air volume), and the like. A cooling control circuit for controlling the heating unit 160 and the cooling unit 180 in accordance with a command from the print control unit 120.

  FIG. 13 is a flowchart illustrating an example of a control algorithm of the image forming apparatus 10 ′ described with reference to FIGS. 11 and 12. In FIG. 13, steps that are the same as or similar to those in the flowchart of FIG.

  Instead of steps S60 and S62 of FIG. 10, the flowchart of FIG. 13 includes steps S60 'and S62', respectively.

  That is, in step S60 ', the transport temperature judgment formula of the following formula [Formula 4] is calculated using the judgment values A, B, and C obtained in steps S12, S22, and S32.

[Equation 4] α3 × A + γ3 × C
However, the coefficients α3 and γ3 are predetermined constant values, respectively.

  The result of the transfer temperature judgment formula [Equation 4] is obtained, and the transfer temperature adjustment value E 'corresponding to the result is determined (step S62'). Then, the heating temperature of the heating unit 160 is adjusted according to the value of the conveyance temperature adjustment value E ′.

  In the above embodiment, a configuration in which a plurality of full-line heads are arranged for each color has been described. However, when implementing the present invention, a head configuration in which nozzle rows are formed for each color in a multi-color integrated head is also possible. It is. Further, a shuttle scan type head that reciprocates a short head in the main scanning direction can be used instead of the full line type head.

1 is an overall configuration diagram of an image forming apparatus according to an embodiment of the present invention. Plane perspective view showing a structural example of a full line type ink jet head Plane perspective view showing another configuration example of a full-line inkjet head Sectional drawing which follows the 4-4 line in FIG. Enlarged view showing the nozzle arrangement of the head shown in FIG. Schematic diagram showing the configuration of an ink supply system in an image forming apparatus Partial sectional view showing a detailed structural example of a semi-solution source Partial sectional view seen from the direction of arrow 8A in FIG. Main block diagram showing the system configuration of the image forming apparatus of this example Flow chart showing an example of control of the image forming apparatus of this example The figure which shows the structural example of the image forming apparatus in the case of using a phase change type ink. FIG. 11 is a principal block diagram showing the system configuration of the image forming apparatus shown in FIG. 11 is a flowchart showing an example of control of the image forming apparatus shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Image forming apparatus, 12K, 12C, 12M, 12Y, 12CL ... Head, 14 ... Ink storage / loading part, 16, 16A, 16B, 16C, 16D, 16E ... Semi-solid solution light source, 17 ... Pressure fixing part, DESCRIPTION OF SYMBOLS 18 ... Main curing light source, 20 ... Recording paper, 22 ... Paper feeding part, 26 ... Adsorption belt conveyance part, 32 ... Magazine, 45 ... Roller, 46 ... Heater, 50 ... Head, 51 ... Nozzle, 52 ... Pressure chamber, 58 ... Actuator, 112 ... System controller, 119 ... Pressure drive unit, 120 ... Print control unit, 126 ... Media detection unit, 138 ... Pressure mechanism, 160 ... Heating unit, 180 ... Cooling unit

Claims (10)

An ejection head having a nozzle for ejecting ink;
Conveying means for conveying at least one of the ejection head and the recording medium to relatively move the ejection head and the recording medium;
The ink is disposed on the downstream side of the ejection head in the relative conveyance direction of the recording medium with respect to the ejection head, and does not cause color mixing even when the ink ejected from the ejection head on the upstream side is in contact with other color inks. A semi-solid solution curing means for curing to a semi-solid state of viscosity;
A smoothing means that is disposed downstream of the semi-solid solution curing means and smoothes the ink on the recording medium;
A main curing unit that is disposed downstream of the smoothing unit, and cures and fixes the ink on the recording medium to such an extent that image quality deterioration due to ink rubbing or the like does not occur even during transport handling;
An image forming apparatus comprising:   The image forming apparatus according to claim 1, wherein the smoothing unit includes a pressurizing unit that pressurizes the ink on the recording medium.   The image forming apparatus according to claim 2, wherein the smoothing unit further includes a heating unit that heats the ink on the recording medium.   4. The image forming apparatus according to claim 1, further comprising ink supply means for supplying energy-applied curable ink to the discharge head. The ejection head is provided for each color of a plurality of inks, and the plurality of ejection heads for each color are arranged from the upstream side in the order of ink colors with low curing sensitivity by energy application,
The image forming apparatus according to claim 4, wherein the semi-solid solution curing means is disposed on the downstream side of each ejection head.   Control means for controlling at least one of the smoothing condition of the smoothing means and the energy applied by the semi-solid solution hardening means according to at least one of the recording medium type, ink type and ink landing amount. The image forming apparatus according to claim 1, further comprising: Phase change ink supply means for supplying phase change ink to the ejection head;
The ejection head ejects the phase change ink in a high temperature melt state,
The image forming apparatus according to claim 1, wherein the main curing unit performs the main curing of the phase change ink by cooling.   The image forming apparatus according to claim 1, wherein an ejection head for ejecting clear ink is provided downstream of the ejection head for ejecting colored ink.   9. The image forming apparatus according to claim 1, further comprising a retraction drive mechanism that moves the smoothing unit from a predetermined smoothing processing position to a predetermined retraction position. Ink is ejected from a discharge head having an ink discharge nozzle toward a recording medium, and at least one of the discharge head and the recording medium is transported to move the discharge head and the recording medium relative to each other to perform the recording. An image forming method for forming an image on a medium,
A discharge step of discharging energy-applied curable ink or phase change ink onto the recording medium by the discharge head;
A semi-solid solution curing treatment step of curing the ink ejected in the ejection step to a semi-solid solution state having a viscosity that does not cause color mixing even in a liquid contact state with other color inks;
A smoothing treatment step of smoothing the ink by pressurizing the ink in a semi-solid solution state on the recording medium;
A main curing treatment step of curing and fixing the ink on the recording medium after the smoothing treatment step to such an extent that image quality deterioration due to ink rubbing or the like does not occur even in transport handling;
An image forming method comprising:

Images