JP2006306080A - Image forming apparatus and ink jet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus and an ink jet recorder which prevent deterioration in image quality such as an image failure by suppressing adhesion of an image forming body such as an ink color material to a means getting in contact with a medium such as a liquid removing means for removing a liquid on the medium and a pressing means for pressing ink on the medium, or an image on the medium. <P>SOLUTION: A liquid removing part (25) with an absorbing roll (100) which removes the liquid on a recording medium (16) is set at the rear stage of a printing part (12). Surface properties of the absorbing roll (100) relative to the recording medium (16) are specified. The surface properties of the absorbing roll (100) include at least one of a surface roughness, a surface energy and a contact angle. For example, the surface roughness of the absorbing roll (100) is specified to be larger than a surface roughness of the recording medium (16). Moreover, preferably, the surface roughness of the absorbing roll (100) is twice or more of the surface roughness of the recording medium (16). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus and an ink jet recording apparatus, and more particularly to an ink jet recording apparatus and other image forming apparatuses that form an image on a medium using an image forming body such as ink.

  In an image forming apparatus such as an ink jet recording apparatus, an image is formed on a medium using a liquid ink in which a color material or an additive is mixed with a solvent such as water or alcohol. Liquid (ink solvent) remains on the surface of the medium on which the image is formed, and the liquid remaining on the medium causes image deterioration (image failure), set-off, cockling, and the like. In an ink jet recording apparatus, it is necessary to quickly remove the liquid remaining on such a medium, and various devices have been made for that purpose. In particular, in a method in which the treatment liquid and ink react on the media to insolubilize the color material contained in the ink, or the color material is aggregated to promote ink fixing, the amount of liquid adhering to the media increases. The need for liquid removal is increasing.

  Further, when the ink coloring material is mainly fixed on the surface of the medium, a relief feeling may be generated in the image formed on the medium depending on the three-dimensional shape (height) of the dots formed on the medium. By flattening (smoothing) the dots constituting the image, it is possible to eliminate the relief between the images.

  In the ink absorber described in Patent Document 1 and the image forming apparatus and method using the ink absorber, the liquid solvent absorber and at least a part of the surface thereof are covered and have a releasability from the ink colorant. And a release member that transmits the ink solvent. When the ink adheres to the sheet, the liquid solvent absorber is brought close to the portion with the release member interposed therebetween, and the liquid is passed through the release member. The solvent is absorbed by the liquid solvent absorber, and the liquid ink is configured such that the colorant and the liquid solvent are separated on the sheet. Further, a liquid level sensor for detecting the liquid level in the polymer absorbent body is provided, and the throttle mechanism is activated when the sensor value reaches a predetermined value.

In the surplus developer removing apparatus described in Patent Document 2, the liquid absorbing material that removes the surplus developer adhering to the drum after wet developing the electrostatic latent image has a surface free energy of 25 mJ / m in the outermost layer. ^It has a breathable surface layer made of ² or less materials and an elastic porous layer formed on the lower layer side of the surface layer.
JP 2001-179959 A Japanese Patent Laid-Open No. 9-15981

  However, if an absorbing medium used for liquid removal or a pressing medium used for flattening dots is brought into contact with the medium (ink coloring material on the surface of the medium) or pressed with a predetermined pressure, the ink coloring material is absorbed from the surface of the medium to the absorbing medium or pressing. The image may be transferred to a medium, and the image quality may be significantly deteriorated. Further, if the ink coloring material adheres to the absorbing medium or the pressing medium, maintenance such as cleaning or replacement of the absorbing medium or the pressing medium is necessary, and there is a concern that the production efficiency may be decreased and the durability of the absorbing medium or the pressing medium may be decreased. .

In the ink absorber and the image forming apparatus / method using the ink absorber described in Patent Document 1, materials having releasability used for the ink absorber are specifically disclosed. Since the physical property values are not quantified, depending on the type of media, ink may easily adhere to the absorber. In particular, if there is insufficient liquid removal on the media due to dirt or deterioration of the absorber, moisture will remain between the colorant and the absorber, and this will affect the adhesion between the absorber and the ink. There is a risk of affecting.

  Further, in the surplus developer removing device described in Patent Document 2, the surface free energy of the liquid absorbing liquid is defined, but other conditions such as the surface roughness of the liquid absorbing liquid are not defined, and depending on the type of media. May cause the ink coloring material to adhere to the liquid absorption.

  Further, in the inventions disclosed in Patent Document 1 and Patent Document 2, since the relative magnitude relationship between the adhesion force of the ink coloring material to the medium and the adhesion force to the absorber (liquid absorption) is not disclosed, Depending on the type and surface properties, the ink color material on the medium may adhere to the absorber (liquid absorption), and the selection range of the medium is expected to be narrow.

  The present invention has been made in view of such circumstances, and ink for a medium that contacts an image on the medium or the medium, such as a liquid removal medium for removing the liquid on the medium or a pressing medium for pressing the ink on the medium. An object of the present invention is to provide an image forming apparatus and an ink jet recording apparatus that suppress adhesion of an image forming body such as a color material and prevent deterioration of image quality such as an image failure.

  In order to achieve the above object, an image forming apparatus according to a first aspect of the present invention relates to an ejection head that ejects a liquid onto a recording medium to form a desired image, and the recording medium and the ejection head are arranged relative to each other. And a contact means that is provided on the downstream side in the transport direction of the recording medium with respect to the ejection head and that contacts the liquid on the recording medium, the contact means having a surface thereof At least one of a condition that the surface roughness is larger than the surface roughness of the recording medium, a condition that the surface free energy is smaller than the surface free energy of the recording medium, and a condition that the contact angle is smaller than the contact angle of the recording medium. Any one of the conditions is satisfied.

  According to the present invention, the surface property of the contact means that contacts the liquid on the recording medium is defined by the surface roughness, the surface free energy, and the contact angle of the contacting liquid, and the surface roughness is larger than that of the recording medium. Since at least one of the conditions where the free energy is smaller than that of the recording medium and the condition where the contact angle is smaller than that of the recording medium is satisfied, even if the contact means is brought into contact with the liquid on the recording medium, the contact on the contact means side Since the liquid does not adhere or remain on the surface and the liquid does not adhere from the contact means on the recording medium, a preferable image is formed.

  The contact means includes a pressing means for pressing and smoothing (flattening) a liquid (image forming body contained in the liquid) and a liquid removing means for removing the liquid (solvent) on the recording medium. When the liquid (image forming body) is flattened, the relief of the recorded image is suppressed. Further, when the liquid on the recording medium is removed, it is possible to prevent cockling from occurring on the recording medium.

  Examples of the liquid ejected from the ejection head include ink containing an ink color material as an image forming body, and a masking material such as a resist.

  The ejection head includes a line-type head having an ejection hole array having a length corresponding to the entire width of the recording medium (image forming width of the recording medium), and a short length having an ejection hole array having a length less than the entire width of the recording medium. There is a serial type head that scans the head in the width direction of the recording medium.

  The line-type ejection head has a length corresponding to the entire width of the recording medium by arranging short heads having short ejection hole arrays that are less than the length corresponding to the entire width of the recording medium and connecting them in a staggered manner. Also good.

  The recording medium is a medium (medium) that is ejected from the image forming body by the ejection head, and is not limited to a continuous sheet, a cut sheet, a seal sheet, a resin sheet such as an OHP sheet, a film, a cloth, and other materials and shapes. Includes media.

  According to a second aspect of the present invention, there is provided the image forming apparatus according to the first aspect, wherein the contact unit includes a liquid removing unit that contacts the liquid on the recording medium and removes the liquid. And

  For liquid removal by the liquid removing means, a mode in which the liquid is absorbed and removed by using an absorbent member such as a porous member or a polymer in a portion in contact with the liquid, or a resin in which a large number of small holes are provided in the portion in contact with the liquid There is a mode in which liquid is sucked and removed by a suction device (pump) or the like through a small hole using a metal member.

  According to a third aspect of the present invention, there is provided the image forming apparatus according to the first or second aspect, wherein the contact means has a surface roughness that is twice or more the surface roughness of the recording medium. It has at least one of a surface free energy of 1/2 or less with respect to the surface free energy and a contact angle of 1/2 or less with respect to the contact angle of the recording medium.

  The surface roughness, surface free energy, and contact angle of the contact means are at least twice the surface roughness of the recording medium, 1/2 or less of the surface free energy of the recording medium, and 1/2 or less of the contact angle of the recording medium. Thus, a sufficient margin is obtained for the surface property of the contact means. If a sufficient margin is obtained for the surface property of the contact means in this way, the appropriate contact pressure (pressing) range of the contact means becomes wide, and an increase in processing efficiency can be expected.

  According to a fourth aspect of the present invention, there is provided the image forming apparatus according to the first, second, or third aspect, wherein the plurality of contact means are different in at least one physical property among a surface roughness, a surface free energy, and a contact angle. And switching means for selectively switching contact means for contacting the liquid on the recording medium among the plurality of contact means.

  By configuring the plurality of contact means having different physical property values (surface properties) to be selectively switchable, the contact means having the optimum surface property can be used.

  According to a fifth aspect of the present invention, there is provided the image forming apparatus according to the fourth aspect, wherein the recording medium judging means for judging the type of the recording medium, and the switching means based on the judgment result of the recording medium judging means. And a switching control means for controlling.

  Since the contact means is selectively switched according to the type of the recording medium, a preferable contact means corresponding to the recording medium is used.

  The mode of determining the type of the recording medium may be configured such that the user inputs the recording medium information via the user interface, or the recording medium is directly selected using a detection unit such as a sensor or an image sensor. The type of the recording medium may be determined from the reading result. The supply means for supplying the recording medium includes an information recording body (memory, IC tag, etc.) for storing information including the type of the recording medium, and the type of the recording medium (media type) is read from the information recording body. It may be configured.

  In order to achieve the above object, an ink jet recording apparatus according to claim 6, wherein an ejection head that ejects ink onto a recording medium to form a desired image, and the recording medium and the ejection head are relatively disposed. Conveying means for conveying, and contact means provided on the downstream side in the conveying direction of the recording medium with respect to the ejection head, and contacting the ink on the recording medium. At least one of a condition that the surface roughness is larger than the surface roughness of the recording medium, a condition that the surface free energy is smaller than the surface free energy of the recording medium, and a condition that the contact angle is smaller than the contact angle of the recording medium It is characterized by satisfying one condition.

  When image formation is performed using pigment-based ink, the ink solvent and the ink coloring material are separated to fix the ink coloring material on the recording medium, and the ink solvent is removed from the recording medium. For removing the ink solvent, a method in which an absorbing member such as a porous member is brought into contact with the ink solvent is often used. When the present invention is applied to this absorbing member, the absorbing member and the ink (ink color material) are in contact with each other. The ink coloring material can be prevented from adhering to the absorbing member. Further, when the present invention is applied to a pressing means for pressing the ink coloring material when the ink coloring material on the recording medium is pressed to flatten the ink coloring material, adhesion of the ink coloring material to the pressing means is prevented. it can. Therefore, the present invention can provide a great effect particularly when a pigment-based ink that fixes an ink coloring material on the surface of a recording medium is used.

  A seventh aspect of the invention relates to an aspect of the ink jet recording apparatus according to the sixth aspect of the invention, and a processing liquid that discharges a processing liquid that reacts with the ink and fixes a coloring material contained in the ink to the recording medium. A discharge head is provided.

  In a two-component ink jet recording apparatus that reacts treatment liquid and ink to promote ink fixation, unreacted ink (ink solvent) and excess treatment liquid are efficiently removed and ink colorant is removed. The preferred liquid removal is done without. In particular, in a two-component ink jet recording apparatus in which a large amount of liquid (solvent) is discharged onto a recording medium, a great effect can be obtained.

  According to the present invention, the contact means that comes into contact with the liquid forming the image on the recording medium has the condition that the surface roughness is larger than that of the recording medium, the surface free energy is smaller than that of the recording medium, and the contact angle is larger than that of the recording medium. Since any one of the small conditions is satisfied, the liquid does not adhere to the contact means even if the contact means comes into contact with the liquid, and the image formed on the recording medium does not fail or deteriorate. . The contact means includes a pressing means for pressing and flattening the liquid and a liquid removing means for absorbing and removing the liquid.

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

[First Embodiment, Overall Configuration of Inkjet Recording Apparatus]
FIG. 1 is an overall configuration diagram of an ink jet recording apparatus according to an embodiment of the present invention. As shown in the figure, the inkjet recording apparatus 10 includes a plurality of print heads 12K provided corresponding to black (K), cyan (C), magenta (M), and yellow (Y) inks. 12C, 12M, and 12Y, and the processing liquid discharge head 12S that reacts with these inks to promote ink fixation (hereinafter, the print heads 12K, 12C, 12M, and 12Y and the processing liquid discharge head 12S are collectively referred to as the head 12S, 12K, 12C, 12M, and 12Y), and a process corresponding to the print heads 12K, 12C, 12M, and 12Y corresponding to each color ink and the treatment liquid ejection head 12S. A storage / loading unit 14 for storing liquid, a paper feeding unit 18 for supplying a recording medium 16, and a medium for detecting the type of the recording medium (medium) 16. A detection unit 19, a decurling unit 20 that removes curl from the recording medium 16, and an ink ejection surface of the printing unit 12 are arranged opposite to each other, and the recording medium 16 is conveyed while maintaining the flatness of the recording medium 16. A suction belt conveyance unit 22, a print detection unit 24 for reading a print result by the print unit 12, a liquid removal unit 25 provided at a subsequent stage of the print detection unit 24 to remove the liquid (solvent) on the recording medium 16, and printed And a paper discharge unit 26 for discharging the recording medium 16 (printed material) to the outside.

  In FIG. 1, a magazine for rolled paper (continuous paper) is shown as an example of the paper supply unit 18, but a plurality of magazines having different paper widths, 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.

  In the case of an apparatus configuration that uses roll paper, a cutter (first cutter) 28 is provided as shown in FIG. 1, and the roll paper is cut into a desired size by the cutter 28. The cutter 28 includes a fixed blade 28A having a length equal to or greater than the conveyance path width of the recording medium 16, and a round blade 28B that moves along the fixed blade 28A. The fixed blade 28A is provided on the back side of the print. The round blade 28B is disposed on the printing surface side with the conveyance path interposed therebetween. Note that the cutter 28 is not necessary when cut paper is used.

  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.

  In addition, the inkjet recording apparatus 10 includes a media detection unit 19 that detects the type of the recording medium 16 on the upstream side of the printing unit 12. Although details will be described later (see FIG. 3), the media detection unit 19 includes a thickness sensor that detects the thickness of the recording medium 16 and a surface property sensor that detects the surface property (smoothness) of the recording medium 16. It is configured. A thickness sensor and a surface property sensor not shown in FIG. 1 are denoted by reference numerals 120 and 122 in FIG. 3, respectively. Note that the media detection unit 19 can be omitted when the information obtained by the media detection unit 19 such as the thickness information and surface property information of the recording medium 16 is stored in the information recording medium described above.

  The recording medium 16 delivered from the paper supply unit 18 retains curl due to having been loaded in the magazine. In order to remove this curl, heat is applied to the recording medium 16 by the heating drum 30 in the direction opposite to the curl direction of the magazine in the decurling unit 20. At this time, it is more preferable to control the heating temperature so that the printed surface is slightly curled outward.

  After the decurling process, the cut recording medium 16 is sent to the suction belt conveyance unit 22. The suction belt conveyance unit 22 has a structure in which an endless belt 33 is wound between rollers 31 and 32, and faces at least the ink (treatment liquid) discharge surface of the printing unit 12 and the sensor surface of the printing detection unit 24. The portion to be formed is a horizontal surface (flat surface).

  The belt 33 has a width that is greater than the width of the recording medium 16, and a plurality of suction holes (not shown) are formed on the belt surface. As shown in FIG. 1, a suction chamber 34 is provided at a position facing the nozzle surface of the print unit 12 and the sensor surface of the print detection unit 24 inside the belt 33 spanned between the rollers 31 and 32. Then, the suction chamber 34 is sucked by the fan 35 to make a negative pressure, whereby the recording medium 16 on the belt 33 is sucked and held.

  The power of the motor (not shown in FIG. 1, indicated by reference numeral 88 in FIG. 7) is transmitted to at least one of the rollers 31 and 32 around which the belt 33 is wound, so that the belt 33 rotates clockwise in FIG. The recording medium 16 driven in the direction and held on the belt 33 is conveyed from left to right in FIG.

  Since ink adheres to the belt 33 when a borderless print or the like is printed, the belt cleaning unit 36 is provided at a predetermined position outside the belt 33 (an appropriate position other than the print area). Although details of the configuration of the belt cleaning unit 36 are not shown, for example, there are a method of niping a brush roll, a water absorbing roll, etc., an air blow method of blowing clean air, or a combination thereof. In the case where the cleaning roll is nipped, the cleaning effect is great if the belt linear velocity and the roller linear velocity are changed.

  Although a mode using a roller / nip conveyance mechanism instead of the suction belt conveyance unit 22 is also conceivable, if the roller / nip conveyance is performed in the print area, the image easily spreads because the roller contacts the printing surface of the sheet immediately after printing. There is a problem. Accordingly, as in this example, the heads 12S, 12K, 12C, 12M, and 12Y face the recording medium 16, and the recording medium 16 contacts the image surface in the print area (ejection area) that receives droplets of processing liquid and ink. Adsorption belt conveyance that does not occur is preferable.

  A heating fan 40 is provided on the upstream side of the printing unit 12 on the paper conveyance path formed by the suction belt conveyance unit 22. The heating fan 40 heats the recording medium 16 by blowing heated air onto the recording medium 16 before printing. By heating the recording medium 16 immediately before printing, the ink becomes easy to dry after landing.

  The printing unit 12 is a so-called full line type head in which line type heads having a length corresponding to the maximum paper width are arranged in a direction orthogonal to the paper feed direction (see FIG. 2). Although a detailed structural example will be described later, each of the heads 12S, 12K, 12C, 12M, and 12Y exceeds at least one side of the maximum-size recording medium 16 that is the target of the inkjet recording apparatus 10, as shown in FIG. It is composed of a line type head in which a plurality of nozzles are arranged over the length.

  A processing liquid discharge head 12S corresponding to the processing liquid (S) from the upstream side along the feeding direction of the recording medium 16 (hereinafter referred to as a paper feeding direction), black (K), cyan (C), magenta (M), Print heads 12K, 12C, 12M, and 12Y corresponding to the respective color inks are arranged in the order of yellow (Y). The processing liquid is ejected from the processing liquid ejection head 12S while the recording medium 16 is being transported, and the colors are respectively output from the print heads 12K, 12C, 12M, and 12Y onto the recording medium 16 to which the processing liquid is adhered (on the processing liquid). A color image can be formed on the recording medium 16 by ejecting ink.

  In this way, according to the printing unit 12 in which the full line head covering the entire paper width is provided for each of the processing liquid and each color ink, the recording medium 16 and the printing unit 12 are relatively moved in the sub-scanning direction. An image can be formed on the entire surface of the recording medium 16 by performing the operation only once (that is, by one sub-scan). Thereby, high-speed printing is possible and productivity can be improved as compared with a shuttle type head in which the head reciprocates in the main scanning direction.

  In this example, the configuration of KCMY standard colors (four colors) is illustrated, but the combination of ink colors and the number of colors is not limited to this embodiment, and light ink and dark ink are added as necessary. May be. For example, it is possible to add a print head that discharges light ink such as light cyan and light magenta.

  As shown in FIG. 1, the storage / loading unit 14 includes a processing liquid tank 14S corresponding to the processing liquid discharge head 12S, and an ink supply tank 14K that stores inks of colors corresponding to the print heads 12K, 12C, 12M, and 12Y. , 14C, 14M, 14Y. Each tank communicates with each head 12S, 12K, 12C, 12M, 12Y via a required pipe line (not shown).

  The storage / loading unit 14 includes notifying means (display means, warning sound generating means) for notifying when the ink remaining amount is low, and prevents erroneous loading between the inks of each color and between the ink and the processing liquid. It has a mechanism for.

  The print detection unit 24 includes an image sensor for imaging the print result of the print unit 12, and functions as a unit for checking nozzle clogging and other ejection defects from an image read by the image sensor.

  The print detection unit 24 of this example is composed of a line sensor having a light receiving element array wider than at least the discharge width (printable width) of the processing liquid and ink by the heads 12S, 12K, 12C, 12M, and 12Y. . The line sensor includes an R sensor row in which photoelectric conversion elements (pixels) provided with red (R) color filters are arranged in a line, a G sensor row provided with green (G) color filters, The color separation line CCD sensor is composed of a B sensor array provided with a blue (B) color filter. Instead of the line sensor, an area sensor in which the light receiving elements are two-dimensionally arranged can be used.

  The print detection unit 24 reads test patterns printed by the heads 12S, 12K, 12C, 12M, and 12Y, and detects ejection of the heads 12S, 12K, 12C, 12M, and 12Y. The ejection determination includes the presence / absence of ejection, measurement of dot size, measurement of dot landing position, and the like.

  Liquid removal for removing the processing liquid remaining on the recording medium 16 (remaining without reacting) and the ink solvent remaining on the recording medium 16 at the subsequent stage (downstream in the paper feed direction) of the print detection unit 24. Part 25 is arranged. Details of the liquid removing unit 25 will be described later.

  A heating / pressurizing unit 44 is provided following the liquid removing unit 25. The heating / pressurizing unit 44 is a means for drying the recording medium 16 and controlling the glossiness of the image surface, and pressurizing with a pressure roller 45 having a predetermined surface irregularity shape while heating the image surface, The uneven shape is transferred to the image surface.

  When printing on porous paper with dye-based ink, the weather resistance of the image is improved by preventing contact with ozone or other things that cause dye molecules to break by pressurizing the paper holes with pressure. There is an effect to.

  The printed matter generated in this manner is outputted from the paper output unit 26. It is preferable to discharge the original image to be originally printed and the test print separately. The ink jet recording apparatus 10 is provided with a sorting means (not shown) that switches the paper discharge path so as to select the print product of the main image and the print product of the test print and send them to the discharge units 26A and 26B. Yes. Note that when the main image and the test print are simultaneously formed in parallel on a large sheet, the test print portion is separated by a cutter (second cutter) 48. The cutter 48 is provided immediately before the paper discharge unit 26, and cuts the main image and the test print unit when the test print is performed on the image margin. The structure of the cutter 48 is the same as that of the first cutter 28 described above, and includes a fixed blade 48A and a round blade 48B.

Although not shown in FIG. 1, the paper output unit 26A for the target prints is provided with a sorter for collecting prints according to print orders.
[Description of liquid removal unit]
Next, the liquid removal unit 25 will be described in detail with reference to FIG. FIG. 3 is a main part configuration diagram showing the configuration of the liquid removing unit 25.

  As shown in FIG. 3, the liquid removing unit 25 has a length corresponding to the width direction of the recording medium 16 in a direction substantially orthogonal to the paper feeding direction (a length substantially equal to or longer than the entire width of the recording medium 16. ) And a support member 101 connected to both ends of the absorbent roll 100 so that the distance between the absorbent roll 100 and the recording medium 16 can be varied (the absorbent roll 100 is The pressing arm 104 driven by the drive source 102 so as to move in a direction substantially perpendicular to the recording surface of the recording medium 16, and the liquid absorbed in the absorbing roll 100 (contained in the absorbing roll) via the tube 106. A suction device (pump) 108 for sucking in, a liquid receiver 110 for receiving the liquid sucked from the absorption roll 100 by the suction device 108, and the absorption roll 100. It includes a cleaning roller 112 for removing the ink color material and foreign matter adheres to the surface of the absorbing roller 100, the liquid or solid adhered to the surface of the absorbing roller 100 (foreign matter), the.

  In the absorbing roll 100, the liquid contact portion 100A that comes into contact with the liquid on the recording medium 16 is composed of a metal pipe having a large number of holes (suction holes) with a diameter of 100 μm. The upper liquid is removed by suction. In the aspect of sucking and removing the liquid on the recording medium 16 in this way, the negative pressure generated by the suction device 108 is varied to absorb water (for example, the amount of liquid removed by the absorbing roll 100 per unit time). Is controlled. The liquid contact portion 100A is constituted by a member having excellent liquid absorbability such as a hydrophilic porous member, a nonwoven fabric, polyvinyl alcohol (PVA), and a polyurethane material, and the liquid on the recording medium 16 (mainly ink solvent and treatment liquid). There is also an aspect in which the solvent) is absorbed and removed by the capillary force into the liquid contact part 100A. However, when a hydrophilic porous member or the like is applied to the liquid contact portion 100A of the absorption roll 100, it is necessary to pay attention to the water absorption capability (suction force). If a material having a large water absorption capability is selected, the ink color material may be peeled off from the recording medium 16 due to the flow of the liquid, and may adhere to the liquid contact portion 100A of the absorption roll 100. Therefore, the liquid contact part 100A of the absorbent roll 100 is preferably a non-water absorbent member or a weak water absorbent member, and it is preferable that the absorbent capacity can be finely controlled by a pump or the like connected to the outside.

  The absorbent roll 100 has a hollow structure, and the hollow portion is connected to the suction device 108 via the tube 106. By operating the suction device 108 to generate a predetermined negative pressure in the hollow portion, the liquid absorbed and removed from the recording medium 16 by the absorbing roll 100 is discharged to the liquid receiver 110.

  Further, the absorption roll 100 is configured to be rotatable about a support member 101 as a rotation axis by a rotation mechanism (not shown). That is, when performing the liquid removal, the absorbing roll 100 is brought into contact with the liquid (or the recording medium 16) on the recording medium 16 and the absorbing roll 100 is rotated.

  A motor (motion actuator) capable of position control (rotation amount control) such as a stepping motor or a servo motor is suitable for the drive source 102 that drives the pressing arm 104 that varies the position of the absorption roll 100 in the thickness direction of the recording medium 16. Used for. The drive signal applied to the drive source 102 is managed to control the movement amount of the pressing arm 104, and the distance (clearance) between the absorbing roll 100 and the recording medium 16 can be varied. For example, when the thickness of the recording medium 16 changes, the pressing arm 104 is operated to move the absorption roll 100 in the thickness direction of the recording medium 16. In this way, the pressing arm 104 is controlled so as to keep the distance between the absorbing roll 100 and the image forming surface of the recording medium 16 (or the pressing of the absorbing roll 100 against the recording medium 16) constant.

The cleaning roll 112 has substantially the same length as the absorption roll 100 in the width direction of the recording medium 16, and both ends thereof are supported by the pressing arm 104 via the support members 114. When a porous member or the like is used for the liquid contact portion 100A of the absorption roll 100, the cleaning roll 11
2 is a member (a member having a high water absorption capability) having better permeability than the liquid contact portion 100A.

  The cleaning roll 112 is configured to be movable between a cleaning position in contact with the absorption roll 100 and a retracted position in a non-contact state without contact with the absorption roll 100 by a moving mechanism (not shown). When the cleaning of the absorbing roll 100 is executed, the cleaning roll 112 is moved to the cleaning position, and when the cleaning of the absorbing roll 100 is not executed, the cleaning roll 112 is moved to the retracted position. Further, the cleaning roll 112 is configured to be rotatable (driven) with the support member 114 as a rotation axis.

  Note that a blade-like member may be used instead of the cleaning roll, and the blade may be slid on the liquid contact portion 100A to remove solids such as liquid and ink coloring material attached to the surface of the liquid contact portion 100A. Moreover, in the aspect which comprises the liquid contact part 100A of the absorption roll 100 with an absorption member, the aspect provided with the moisture meter which detects the moisture content contained in the absorption roll 100 (especially liquid contact part 100A) is preferable. The moisture amount detected by the moisture meter is configured to be stored in a storage medium such as a memory, and based on the moisture amount stored in the memory, the cleaning time or replacement time of the absorption roll 100 can be predicted. it can.

  A thickness sensor 120 that detects the thickness of the recording medium 16 and a surface property sensor 122 that detects the surface property of the recording medium 16 are provided on the upstream side of the absorption roll 100 in the paper feeding direction. The thickness sensor 120 and the surface property sensor 122 are included in the media detection unit 19 of FIG. A known technique can be applied to a method of detecting the thickness and surface property of the recording medium 16 (smoothness of the surface of the recording medium 16) by the thickness sensor 120 and the surface property sensor 122. For example, the surface property of the recording medium 16 is determined by using a sensor having a light emitting unit that irradiates the recording medium 16 with light and a light receiving unit that receives the reflected light, and the light amount and wavelength detected by the light receiving unit. There is an aspect in which the surface property of the recording medium 16 is determined from the information.

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

  4 (a) is a plan perspective view showing an example of the structure of the head 50, and FIG. 4 (b) is an enlarged view of a part thereof. 4C is a plan perspective view showing another example of the structure of the head 50, and FIG. 4 is a cross-sectional view showing the three-dimensional configuration of the ink chamber unit (5-5 in FIGS. 4A and 4B). It is sectional drawing which follows a line. In order to increase the dot pitch printed on the recording paper surface, it is necessary to increase the nozzle pitch in the head 50. As shown in FIGS. 4A to 4C and FIG. 4, the head 50 of this example includes a plurality of ink chambers including nozzles 51 from which ink droplets are ejected and pressure chambers 52 corresponding to the nozzles 51. The unit 53 has a structure in which the units 53 are arranged in a staggered matrix, thereby achieving an increase in the apparent nozzle pitch density.

  That is, as shown in FIGS. 4A and 4B, the head 50 according to the present embodiment has the entire width of the recording medium 16 (printable) in a direction in which a plurality of nozzles 51 that eject ink are substantially perpendicular to the paper feed direction. A full line head having one or more nozzle rows arranged over a length corresponding to (width).

  Further, as shown in FIG. 4 (c), short two-dimensionally arranged heads 50 'may be arranged in a staggered manner and connected to form a length corresponding to the entire width of the recording medium.

Note that the processing liquid is only required to adhere substantially uniformly (substantially) to the area where the ink is ejected on the recording medium 16, so that high-density dot formation is not required as compared with the ink. Therefore, the treatment liquid ejection head 12S can be configured to have a smaller number of nozzles (lower nozzle density) than the ink ejection head 50 (12K, 12C, 12M, 12Y). Further, a configuration in which the nozzle diameter of the treatment liquid ejection head 12S is larger than the nozzle diameter of the ink ejection head 50 is also possible.

  As shown in FIG. 5, the pressure chamber 52 provided corresponding to each nozzle 51 has a substantially square planar shape, and the nozzle 51 and the supply port 54 are provided at both corners on the diagonal line. ing. Each pressure chamber 52 communicates with a common flow channel 55 through a supply port 54.

  A piezoelectric element (piezoelectric actuator) 58 provided with individual electrodes 57 is joined to a pressure plate (vibrating plate) 56 constituting the top surface of the pressure chamber 52. When a drive signal is applied between the common electrode also used as the pressure plate 56 and the individual electrode 57, the piezoelectric element 58 is deformed and the volume of the pressure chamber 52 is changed. Is discharged. After ink discharge, new ink is supplied from the common channel 55 to the pressure chamber 52 through the supply port 54. Further, the structure of the ink chamber unit 53 shown in FIG. 5 is merely an example, and other structures may of course be applied.

  As shown in FIGS. 4A and 4B, the ink chamber unit 53 having such a structure has a main scanning direction which is the longitudinal direction of the head 50 and an oblique direction having a constant angle θ which is not orthogonal to the main scanning direction. Are arranged in a lattice pattern with a constant arrangement pattern. With a structure in which a plurality of ink chamber units 53 are arranged at a constant pitch d along a certain angle θ with respect to the main scanning direction, the pitch P of the nozzles projected so as to be aligned in the main scanning direction is d × cos θ. .

  That is, in the main scanning direction, each nozzle 51 can be handled equivalently as a linear arrangement with a constant pitch P. With such a configuration, it is possible to realize a high-density nozzle having 2400 nozzle rows per inch (2400 nozzles / inch, 2400 dpi) projected so as to be aligned in the main scanning direction. Hereinafter, for convenience of explanation, it is assumed that the nozzles 51 are linearly arranged at a constant interval (pitch P) along the main scanning direction. Here, the main scanning direction shown in FIGS. 4A and 4B is substantially parallel to the sensor scanning direction shown in FIG. 3, and the sub-scanning direction shown in FIG. The direction is substantially parallel to the paper feed direction shown.

  In the implementation of the present invention, the nozzle arrangement structure is not limited to the illustrated example. Further, in this embodiment, a method of ejecting ink droplets by deformation of the piezoelectric element 58 typified by a piezo element is adopted, but the method of ejecting ink is not particularly limited in the practice of the present invention, and the piezo jet method is adopted. Instead, various systems such as a thermal jet system in which ink is heated by a heating element such as a heater to generate bubbles and the ink is ejected by the pressure can be applied.

[Description of ink supply system and treatment liquid supply system (supply system)]
Next, a processing liquid supply system and an ink supply system of the inkjet recording apparatus 10 will be described. In this example, the treatment liquid supply system and the ink supply system have the same basic configuration, and will be described using the ink supply system shown in FIG. Hereinafter, the treatment liquid supply system and the ink supply system may be collectively referred to as a supply system.

  FIG. 6 shows a configuration of an ink supply system provided in the inkjet recording apparatus 10. The ink supply system shown in FIG. 6 corresponds to the storage / loading unit 14 described in FIG.

The ink supply system shown in FIG. 6 is provided with an ink supply tank (processing liquid supply tank) 60 which is a base tank for supplying ink (processing liquid). The ink supply tank 60 includes a system that replenishes ink from a replenishment port (not shown) and a cartridge system that replaces the entire tank when the ink remaining amount 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.

  Ink in the ink supply tank 60 is supplied to the head 50 via a filter 62 and a predetermined pipe (not shown) in order to remove foreign matters and bubbles. The filter mesh size of the filter 62 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 50.

  Further, the inkjet recording apparatus 10 is provided with a cap 64 as a means for preventing the nozzle 51 from drying or preventing an increase in the viscosity of ink and processing liquid in the vicinity of the nozzle, and a cleaning blade 66 as a means for cleaning the nozzle surface. It has been.

  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 is displaced up and down relatively with respect to the head 50 by an elevator mechanism (not shown). The cap 64 is raised 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 with the cap.

  During printing or standby, if the frequency of use of a specific nozzle 51 is low and ink and processing liquid are not ejected for a certain period of time, the ink solvent and processing liquid solvent near the nozzles evaporate, and ink viscosity and processing The liquid viscosity becomes high. In such a state, even if the piezoelectric element 58 operates, the ink and the processing liquid cannot be ejected from the nozzle 51.

  Before such a state is reached (that is, within the range of the viscosity that can be discharged by the operation of the piezoelectric element 58), the piezoelectric element 58 is operated, and the deteriorated ink and the deteriorated processing liquid (ink near the nozzle whose viscosity has increased). , Preliminary discharge (purge, idle discharge, spit discharge, dummy discharge) is performed toward the cap to discharge the processing liquid.

  Further, when air bubbles are mixed into the ink in the head 50 (in the pressure chamber 52), the ink cannot be ejected from the nozzle even if the piezoelectric element 58 is operated. In such a case, the cap is applied to the head 50, the ink S (ink in which bubbles are mixed) in the pressure chamber 52 is removed by suction with the suction pump 67, and the suctioned and removed ink is sent to the collection tank 68. .

  In this suction operation, the deteriorated ink with increased viscosity (solidified) is sucked out when the ink is initially loaded into the head or when the ink is used after being stopped for a long time. In addition, since the suction operation is performed with respect to the ink in the pressure chamber 52 and the entire processing liquid, the amount of ink consumption increases. Therefore, it is preferable to perform preliminary ejection when the increase in ink viscosity is small.

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 movement mechanism (wiper) (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. It should be noted that when the ink ejection surface is cleaned by the blade mechanism, preliminary ejection is performed in order to prevent foreign matter from being mixed into the nozzle 51 by the blade.

[Explanation of control system]
FIG. 7 is a principal block diagram showing the system configuration of the inkjet recording apparatus 10. The inkjet recording apparatus 10 includes a communication interface 70, a system controller 72, a memory 74, a motor driver 76, a heater driver 78, a print control unit 80, an image buffer memory 82, a head driver 84, a pressing control unit 85, a suction control unit 87, and the like. I have.

  The communication interface 70 is an interface unit that receives image data sent from the host computer 86. A serial interface such as USB (Universal Serial Bus), IEEE 1394, Ethernet (registered trademark), a wireless network, or a parallel interface such as Centronics can be applied to the communication interface 70. In this part, a buffer memory (not shown) for speeding up communication may be mounted. Image data sent from the host computer 86 is taken into the inkjet recording apparatus 10 via the communication interface 70 and temporarily stored in the memory 74.

  The memory 74 is a storage unit that temporarily stores an image input via the communication interface 70, and data is read and written through the system controller 72. The memory 74 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 72 includes a central processing unit (CPU) and its peripheral circuits, and functions as a control device that controls the entire inkjet recording apparatus 10 according to a predetermined program, and also functions as an arithmetic device that performs various calculations. . That is, the system controller 72 controls the communication interface 70, the memory 74, the motor driver 76, the heater driver 78, the pressing control unit 85, and the like, and performs communication control with the host computer 86, read / write control of the memory 74, and the like. At the same time, a control signal for controlling the motor 88 and the heater 89 of the transport system is generated.

  The motor driver 76 is a driver that drives the motor 88 in accordance with instructions from the system controller 72. The heater driver 78 is a driver that drives the heater 89 such as the heating fan 40 in accordance with an instruction from the system controller 72.

  Although only one motor 88 is shown in FIG. 7, actually, the drive motor (not shown) of the belt suction conveyance unit 22, the rotation mechanism of the absorbing roll 100, the motor of the moving mechanism (not shown), etc. Multiple motors (motion actuators) are included. Further, a plurality of motor drivers 76 for controlling the plurality of motors 88 are provided corresponding to each motor. Of course, some or all of the plurality of motor drivers may be integrated.

  The print control unit 80 has a signal processing function for performing various processes and corrections for generating a print control signal from the image data in the memory 74 in accordance with the control of the system controller 72. The generated print data Is a control unit that supplies the head driver 84 with Necessary signal processing is performed in the print controller 80, and the ejection amount and ejection timing of the ink droplets and processing liquid of the head 50 are controlled via the head driver 84.

The print control unit 80 includes an image buffer memory 82, and image data, parameters, and other data are temporarily stored in the image buffer memory 82 when image data is processed in the print control unit 80. In FIG. 7, the image buffer memory 82 is shown in a mode associated with the print control unit 80, but it can also be used as the memory 74. Also possible is an aspect in which the print controller 80 and the system controller 72 are integrated and configured with one processor.

  The head driver 84 generates a drive signal based on the print data supplied from the print control unit 80, and drives the piezoelectric elements of the heads 12S, 12K, 12C, 12M, and 12Y by this drive signal. The head driver 84 may include a feedback control system for keeping the head driving conditions constant.

  The pressing control unit 85 generates a driving signal (pulse signal) based on a command signal sent from the system controller 72, and drives the driving source 102 of the pressing arm 104 by this driving signal. That is, a position control type motor such as a stepping motor or servo motor is applied to the drive source 102, and the movement amount of the pressing arm 104 is managed by the number of pulses of the pulse signal (movement amount information of the drive signal).

  Data of an image to be printed is input from the outside (for example, the host computer 86) via the communication interface 70 and stored in the memory 74. At this stage, RGB image data is stored in the memory 74.

  The image data stored in the memory 74 is sent to the print controller 80 via the system controller 72, and is converted into dot data for each ink color by the print controller 80. That is, the print control unit 80 performs processing for converting the input RGB image data into dot data of four colors of KCMY. The dot data generated by the print controller 80 is stored in the image buffer memory 82.

  In this example, the memory 74 is shown as a storage unit associated with the system controller 72, but the memory 74 may be composed of a plurality of memories (storage media). Further, the system controller 72 may have a built-in memory. In addition to the RGB image data described above, the information stored in the memory 74 includes various setting information, system parameters, a threshold table used for condition determination, various data tables, correction coefficients used for various corrections, and the like. May be included.

  The suction control unit 87 controls on / off of the suction device 108, the number of rotations, the rotation frequency, and the like based on the control signal of the system controller 72. The driving force of the suction device 108 is controlled via the suction control unit 87 to vary the water absorption capacity of the absorption roll 100 shown in FIG.

  Various control programs are stored in the program storage unit 90, and the control programs are read and executed in accordance with instructions from the system controller 72. The program storage unit 90 may use a semiconductor memory such as a ROM or an EEPROM, or may use a magnetic disk or the like. An external interface may be provided and a memory card or PC card may be used. Of course, you may provide several recording media among these recording media.

  The program storage unit 90 may also be used as recording means (memory) (not shown) such as operation parameters (system parameters).

  As described with reference to FIG. 1, the print detection unit 24 is a block including a line sensor, reads an image printed on the recording medium 16, performs necessary signal processing, and the like to determine the discharge status (the presence / absence of discharge, droplet ejection). And the detection result is provided to the print control unit 80.

  The print controller 80 performs various corrections on the head 50 based on information obtained from the print detector 24 as necessary.

  The inkjet recording apparatus 10 includes a temperature detection unit 92 and a humidity detection unit 94 that detect the ambient temperature and ambient humidity of the recording medium 16 in the head 50 and the print region, and the temperature detected by the temperature detection unit 92 ( The temperature signal representing the temperature information) and the humidity signal representing the humidity (humidity information) detected by the humidity detector 94 are sent to the system controller 72. In the system controller 72, heaters (heating medium) shown in the heater 89 or a cooling fan (cooling medium) (not shown) so as to maintain a desired (set) temperature and humidity based on the temperature signal and the humidity signal. Control the temperature variable means.

  Further, the inkjet recording apparatus 10 includes a media determination unit 96 that determines the type of media to be used, and the distance between the absorbing roll 100 and the recording medium 16 according to the media type determined by the media determination unit 96, Various controls such as suction force of the suction device 108, discharge control of the processing liquid and ink, temperature control of the head 50, and humidity control are performed. That is, when the media type information determined by the media determination unit 96 is sent to the system controller 72, the system controller 72 is configured to control each unit based on the media type information.

  A mode in which the media type is determined by the media determination unit 96 is that the operator may input a desired type of recording medium via a user interface (man machine interface) such as a keyboard or a touch panel. Even if the type of paper to be used is automatically determined by reading the information of an information recording body such as a barcode or wireless tag on which the type information of the paper attached to the tray is recorded by a predetermined reading device. Good.

  On the other hand, the inkjet recording apparatus 10 can directly detect the type of the recording medium 16 to be used by using the media detection unit 19 and determine the media type from the detection result. The thickness information of the recording medium 16 and the surface property information of the recording medium 16 obtained from the thickness sensor 120 and the surface property sensor included in the media detection unit 19 are sent to the system controller 72. In the system controller 72, for example, the distance between the absorption roll 100 and the recording medium 16 shown in FIG. 3 is controlled based on the thickness information and surface property information of the recording medium 16.

[Description of surface properties of absorbent roll]
Next, the surface property of the absorption roll 100 used for the liquid removing unit 25 of the inkjet recording apparatus 10 will be described. In the two-component ink jet recording apparatus shown in this example, the ink and the treatment liquid are reacted on the recording medium 16 to insolubilize or aggregate the ink coloring material contained in the ink, and the ink coloring material is applied to the recording medium 16. Dots are formed by fixing.

  Also, if a predetermined amount or more of the ink solvent remaining on the recording medium permeates the recording medium 16, there is a risk that cockling will occur in the recording medium 16. Therefore, the ink solvent on the recording medium 16 is removed from the liquid removal unit. 25 to be removed within a predetermined time.

  When the ink color material comes into contact with the absorption roll 100 when removing the ink solvent, the ink color material may adhere to the surface of the absorption roll 100, and the ink color material may be removed from the image formed on the recording medium 16. By removing a part of the image quality, there is a risk that image quality such as a decrease in density may be reduced. Further, when the ink color material adhering to the absorbing roll 100 adheres to another image (a recording medium on which another image is formed), the quality of the other image is degraded or the recording medium on which the other image is formed is soiled. Such problems will occur.

In the ink jet recording apparatus 10 shown in this example, the ink coloring material does not adhere to the absorbing roll 100 even when the absorbing roll 100 and the recording medium 16 come into contact (even if the ink coloring material adheres to the absorbing roll 100, the amount of adhesion). The relative surface properties of the absorbing roll 100 and the recording medium 16 are specified so that the allowable surface is within a permissible range. In this example, surface roughness, surface free energy, and contact angle of ink that comes into contact (hereinafter simply referred to as contact angle) are defined as the surface properties described above.

  FIG. 8 shows the relationship between the surface roughness of the absorbing roll 100 and the recording medium 16 (medium), and FIGS. 9 and 10 show the relationship between the surface free energy and the contact angle with the absorbing roll 100 recording medium 16, respectively. Show. The surface property relationship between the absorbent roll 100 and the recording medium 16 shown in FIGS. 8 to 10 is obtained by the following experiment. The outline of the experiment is shown in FIG.

  As shown in FIG. 11 (a), a predetermined amount of ink 204 is attached to a range where the treatment liquid is previously attached to the ink attachment surface 202 that defines the surface property of the metal plate (SUS) 200. After that, as shown in FIG. 11 (b), the surface 212 defining the surface property of the metal plate (SUS) 210 is brought into contact with the ink adhering surface 202 of the metal plate 200 on which the ink 204 is adhered, and a predetermined pressure is applied. Pressurize with. In FIG. 11 (a), the range where the treatment liquid is attached is not shown, but this range may be the entire surface of the ink attachment surface 202 of the metal plate 200 or a part thereof.

  After a predetermined time has elapsed, as shown in FIG. 11C, the metal plate 200 and the metal plate 210 are peeled off, and the ink 204 adheres to the ink attachment surface 202 of the metal plate 200 and the surface 212 of the metal plate 210. Check the condition visually. Reference numeral 214 indicated by a broken line in FIG. 11C indicates ink attached to the surface 212 of the metal plate 210.

  For the surface properties defined by the metal plates 200 and 210, surface roughness, surface free energy, and contact angle are applied. As a mode of changing the surface roughness of each surface, a method of changing the surface roughness of each surface by exposing the ink adhering surface 202 of the metal plate 200 and the surface 212 of the metal plate 210 by sandblasting or the like is used.

  The surface free energy varies depending on the composition of the substance, the surface properties of the substance, the environmental conditions such as temperature and humidity, and the mode of changing the contact angle of each surface includes application of a liquid repellent (water repellent treatment) to each surface and An oxide film formation (hydrophilic treatment) on each surface by oxygen plasma or the like is applied.

  Here, the metal plate 200 in this experiment corresponds to the recording medium 16, and the ink adhering surface 202 of the metal plate 200 corresponds to the image forming surface of the recording medium 16. Further, the surface 212 of the metal plate 210 corresponds to the liquid contact part 100 </ b> A of the absorbing roll 100.

  In FIG. 8, the surface roughness (unit: μm) of the ink adhering surface 202 of the metal plate 200 and the surface 212 of the metal plate 210 is divided into four levels (3.00, 1.73, 0.99, 0.09). The experiment result when changing is shown. In FIG. 8, ◯ indicates that the ink 214 attached to the metal plate 210 is not visible, or that the ink 214 is slightly visible on the metal plate 210 (allowable ink 214 is visible), and Δ indicates that the ink adheres to the metal plate 200. This indicates that the amount of ink 204 to be applied and the amount of ink 214 attached to the metal plate 210 are substantially the same. Further, x indicates that the amount of ink 214 attached to the metal plate 210 is larger than the amount of ink 204 attached to the metal plate 200.

  As shown in FIG. 8, for example, when the surface roughness of the metal plate 200 is 1.73 μm and the surface roughness of the metal plate 210 is 3.00 μm (that is, the surface roughness of the metal plate 200 is the surface of the metal plate 210. In the case where the roughness is smaller than the roughness, it can be seen that the ink is not attached to the metal plate 210 or the amount of the ink 214 attached to the metal plate 210 is a very small amount (allowable ink amount).

  For example, when the surface roughness of the metal plate 200 and the metal plate 210 is 3.00 μm (that is, when the surface roughness of the metal plate 200 and the metal plate 210 is substantially the same), the ink 204 attached to the metal plate 200. The amount of ink 214 attached to the metal plate 210 is substantially the same. For example, when the surface roughness of the metal plate 200 is 3.00 μm and the surface roughness of the metal plate 210 is 0.99 μm ( That is, when the surface roughness of the metal plate 200 is larger than the surface roughness of the metal plate 210, the amount of ink 214 attached to the metal plate 210 is larger than the amount of ink 204 attached to the metal plate 200. I understand that.

  From the above experimental results, when the surface roughness of the metal plate 200 is smaller than the surface roughness of the metal plate 210, the ink attached to the metal plate 200 does not adhere to the metal plate 210 or does not adhere. Even if the recording medium 16 and the absorbing roll 100 satisfying the relationship of (the surface roughness of the recording medium) <(the surface roughness of the absorbing roll) are used, the absorbing roll 100 performs recording. Even if it contacts the ink on the medium 16, the ink does not adhere to the absorbing roll 100, or the amount of ink adhering to the absorbing roll 100 is very small and does not cause a problem.

  More preferably, for example, the surface roughness of the metal plate 200 is 0.99, and the surface roughness of the metal plate 210 is 3.00 (surface roughness of the recording medium) × 2 <(surface roughness of the absorbing roll). In this embodiment, the recording medium 16 and the absorption roll 100 satisfying the above relationship are used.

FIG. 9 shows experimental results when the surface free energy (unit: mJ / m ² ) of the ink adhering surface 202 of the metal plate 200 and the surface 212 of the metal plate 210 is changed. In FIG. 9, symbols ○, Δ, and × in the determination column represent the same meaning as in FIG. FIG. 9 shows the surface free energy per unit area measured by the Owens-Wendt method. FIG. 9 shows four types (3.00, 1.73, 0.99, 0.09). The experimental result about each of surface roughness is shown.

  As shown in FIG. 9, regardless of the surface roughness, the surface free energy of the metal plate 200 is smaller than the surface free energy of the metal plate 210 (the surface free energy of the metal plate 200 is 37.6, the metal plate 210 In the case where the surface free energy of the recording medium is 16.4), the ink adhered to the metal plate 200 does not adhere to the metal plate 210. This is because (the surface free energy of the recording medium)> (the surface of the absorbing roll 100). When the recording medium 16 and the absorbing roll 100 satisfying the relationship of free energy are used, the ink does not adhere to the absorbing roll 100 even when the absorbing roll 100 comes into contact with the ink on the recording medium 16, or adheres to the absorbing roll 100. This indicates that the amount of ink to be used is very small and does not cause a problem.

  More preferably, the recording medium 16 and the absorbing roll 100 satisfying the relationship of (surface free energy of the recording medium) / 2> (surface free energy of the absorbing roll) are used.

FIG. 10 shows the contact angle between the ink adhesion surface 202 of the metal plate 200 and the surface 212 of the metal plate 210.
The experiment result when changing (unit, degree) is shown. In FIG. 10, the symbols “O”, “Δ”, and “X” in the determination column represent the same meaning as in FIG.

  As shown in FIG. 10, when the contact angle of the metal plate 200 is approximately 70 degrees to approximately 90 degrees (medium), the contact angle of the metal plate 210 is approximately 100 degrees to approximately 120 degrees (large), and the contact angle of the metal plate 200 Is approximately 10 degrees to approximately 40 degrees (small), and the contact angle of the metal plate 210 is approximately 100 degrees to approximately 120 degrees (large), the amount of the ink 204 adhering to the metal plate 200 is more than the amount of ink 204 attached to the metal plate 210. The amount of adhering ink 214 is increased. Further, when the contact angle of the metal plate 200 is approximately 10 degrees to approximately 40 degrees (small) and the contact angle of the metal plate 210 is approximately 70 degrees to approximately 90 degrees (medium), the ink 204 that adheres to the metal plate 200. And the amount of ink 214 adhering to the metal plate 210 are substantially the same.

  Furthermore, when the contact angle of the metal plate 200 is approximately 70 to approximately 90 degrees (medium) and the contact angle of the metal plate 210 is approximately 10 to approximately 40 degrees (small), the ink 214 attached to the metal plate 210. Or the amount of ink 214 adhering to the metal plate 210 is a very small amount (allowable amount of ink). That is, when the contact angle of the metal plate 210 is larger than the contact angle of the metal plate 200, the ink attached to the metal plate 200 does not adhere to the metal plate 210 or is allowed to adhere. When the recording medium 16 and the absorbing roll 100 satisfying the relationship of (recording medium contact angle)> (absorbing roll contact angle) are used, the absorbing roll 100 contacts the ink on the recording medium 16. However, the ink does not adhere to the absorbing roll 100 or the amount of ink adhering to the absorbing roll 100 is very small, which indicates that there is no problem. An example of the contact angle between the recording medium 16 satisfying such conditions and the absorbent roll 100 is particularly effective when the contact angle of the absorbent roll 100 is 15 to 60 degrees with respect to art paper (contact angle 80 degrees). It has been proved by experiments.

  More preferably, the recording medium 16 and the absorbing roll 100 satisfy the relationship of (recording medium contact angle) / 2> (absorbing roll contact angle).

  Summarizing the above experimental results, the surface properties of the liquid contact portion 100A of the absorbing roll 100 are “surface roughness is rougher than the recording medium”, “surface free energy is smaller than the recording medium”, and “contact angle is recorded. It is smaller than the medium ”and“ any combination of the above conditions ”. By providing the absorption roll 100 with such characteristics, the ink color material is likely to adhere to the recording medium 16 and the ink color material is less likely to adhere to the absorption roll 100. Even if the absorbing roll 100 comes into contact with the ink (image) to be printed, the quality of the image formed on the recording medium 16 does not deteriorate.

  In the actual ink jet recording apparatus 10, the water absorption capability of the absorption roll 100 is controlled by the suction force of the suction device 108 shown in FIG. In the above-described experiment, an external force corresponding to the suction force of the suction device 108 is not applied, but the suction force of the suction device 108 is appropriately set so as to satisfy a condition that does not cause the ink coloring material on the recording medium 16 to peel off. It only has to be set.

  In addition, although one type of ink was used in the above-described experiment, the condition of the surface property of the absorbing roll 100 with respect to the recording medium 16 does not depend on the type of ink. Therefore, even if the type of ink changes, the recording medium 16 described above. What is necessary is just to satisfy the conditions of the surface property of the absorbing roll 100 against the above.

  In the ink jet recording apparatus 10 configured as described above, since the surface property of the absorbing roll 100 is defined by the relative relationship with the surface property of the recording medium 16, adhesion of the ink color material to the absorbing roll 100 is reduced, and recording is performed. The efficiency of removing the liquid on the medium 16 can be improved, and the maintenance of the liquid removing unit 25 can be reduced. In addition, it is possible to deal with media having different surface properties. The surface property referred to here includes at least one of surface roughness, surface free energy, and contact angle.

[Application example]
An application example of the above-described inkjet recording apparatus 10 will be described with reference to FIGS. FIG. 12 is a schematic configuration diagram of the ink jet recording apparatus according to this application example, and FIG. 13 is a configuration diagram showing details of the liquid removing unit 25 ′ of the ink jet recording apparatus shown in FIG. FIG. 14 is a block diagram (corresponding to FIG. 7) showing the main configuration of the control system of the ink jet recording apparatus.

The schematic configuration of the inkjet recording apparatus shown in FIG. 12 is the same as the schematic configuration of the inkjet recording apparatus 10 shown in FIG. 1, and the description thereof is omitted here, and the inkjet recording apparatus 10 and the inkjet recording apparatus shown in FIG. The differences will be described. That is, FIG.
The liquid removing unit 25 ′ (shown in FIG. 13) included in the inkjet recording apparatus shown in FIG. 13 has a configuration different from that of the liquid removing unit 25 included in the inkjet recording apparatus 10.

  FIG. 13 shows the configuration of the liquid removing unit 25 ′ included in the ink jet recording apparatus shown in FIG. 12. As shown in FIG. 13, the liquid removing unit 25 ′ has three absorbent rolls 300, 302, and 304 having different surface properties, and these absorbent rolls 300, 302, and 304 are selectively selected using a selection mechanism 308. Can be switched. The surface property referred to here includes at least one of surface roughness, surface free energy, and contact angle. The absorbing rolls 300, 302, and 304 correspond to recording media that are frequently used.

  In FIG. 13, each absorbing roll 300, 302, 304 is selected by rotating a support plate 312 that supports one end of three absorbing rolls 300, 302, 304 by a drive source (motor) 310. Although the selection mechanism 308 is shown, the configuration of the selection mechanism 308 is not limited to this, and other configurations may be applied.

  In addition, the liquid removing unit 25 ′ includes an up / down mechanism 314 that moves up and down the absorbing rolls 300, 302, and 304. The vertical mechanism 314 includes an eccentric cam 316, a motor 318 that is a drive source of the eccentric cam 316, and a guide member 322 that slides on the rail 320 in accordance with the rotation of the eccentric cam 316 and moves up and down. The vertical mechanism 314 is urged by an urging member 324 upward in FIG. 13 (the direction opposite to the direction in which the recording medium 16 is placed). That is, according to the configuration shown in FIG. 13, by rotating the motor 318 to rotate the eccentric cam 316 and pushing down the guide member 322, the selected absorption roll among the absorption rolls 300, 302, and 304 is turned on. It becomes a state.

  The system controller 72 shown in FIG. 14 sends a selection signal for the absorbing rolls 300, 302, and 304 to the absorbing roll selection control unit 400, and the absorbing roll selection control unit 400 selects the recording medium 16 from the absorbing rolls 300, 302, and 304. The drive source 310 is controlled so as to select an absorption roll corresponding to the type.

  In this way, when an absorption roll corresponding to the type of the recording medium 16 is selected, the system controller 72 controls the motor 318 via the pressing control unit 85 to control on / off of the absorption roll. In addition, as a mode for detecting the type of the recording medium 16, the media information preset by the media determination unit 96 may be used, or the type of the recording medium 16 may be determined according to the detection result of the surface property sensor 122. Also good.

  In this example, the surface properties of the recording medium 16 and the absorbing roll 100 that contacts the ink on the recording medium 16 have been described. However, the present invention can also be applied to members other than the absorbing roll 100. For example, in the belt cleaning unit 36 shown in FIG. 1, the relative relationship between the surface property of the cleaning member that contacts and removes the ink attached to the belt 33 and the surface property of the belt 33 is set so that the ink easily adheres to the cleaning member. You may prescribe.

  Further, the relative relationship between the surface property of the cleaning roll 112 and the surface property of the absorbing roll 100 shown in FIG. 3 may be defined so that ink (dirt) is likely to adhere to the cleaning roll 112.

Other Embodiment
In the above-described embodiment, one processing liquid discharge head 12S is disposed at the uppermost stream of the printing unit 12 (see FIG. 1). However, in the implementation of the present invention, the arrangement of the processing liquid discharge head is not limited to this example. A configuration in which a treatment liquid discharge head is added to at least one position between the color heads in the printing unit 12 is also possible.

  In the above-described embodiment, an ink jet type ejection head is used as means for applying the treatment liquid. Instead of this, or in combination with this, a recording medium using a member such as a roller, a brush, or a blade. It is also possible to use a means for applying a treatment liquid onto 16.

  In the above-described embodiment, the processing liquid discharge head 12S that discharges one type of processing liquid is shown. However, the processing liquid discharge head 12S may be composed of a plurality of heads, and two or more types of processing liquids are selectively used. You may have the structure which can discharge.

  In the above embodiment, an inkjet recording apparatus using a page-wide full-line head having a nozzle row having a length corresponding to the entire width of the recording medium 16 has been described. However, the scope of the present invention is not limited to this, The present invention can also be applied to an ink jet recording apparatus that uses a shuttle head that records an image while reciprocating a short recording head.

  In the above embodiment, the absorbent roll 100 (300, 302, 304) having a length corresponding to the width of the recording medium 16 in the longitudinal direction is shown. However, the absorbent roll 100 (300, 302, 304) is disposed in the longitudinal direction. You may have a structure divided | segmented and a solvent removal is possible independently for every divided | segmented absorption roll 100 (300,302,304). The absorption roll 100 (300, 302, 304) can be finely controlled in accordance with the solvent distribution on the recording medium 16, and improvement in maintainability of the absorption roll 100 (300, 302, 304) is expected.

  In the above embodiment, an ink jet recording apparatus that forms an image on the recording medium 16 by ejecting ink from nozzles provided in the print head has been described. However, the scope of the present invention is not limited to this, and other than ink such as resist. The present invention can be widely applied to an image forming apparatus that forms an image (three-dimensional shape) with a liquid, and a liquid ejecting apparatus such as a dispenser that ejects chemical liquid, water, and the like from a nozzle (ejection hole).

1 is an overall configuration diagram of an ink jet recording apparatus according to the present invention. FIG. 1 is a plan view of a main part around a printing unit of the ink jet recording apparatus shown in FIG. FIG. 1 is a main part configuration diagram of a liquid removing unit of the ink jet recording apparatus shown in FIG. Plane perspective view showing structural example of print head 4 (a) and 4 (b) are cross-sectional views along line 5-5 1 is a principal block diagram showing the configuration of the supply system of the ink jet recording apparatus shown in FIG. 1 is a principal block diagram showing the system configuration of the ink jet recording apparatus shown in FIG. The figure explaining the relationship of the surface roughness of a recording medium and an absorption roll The figure explaining the relationship of the surface free energy of a recording medium and an absorption roll The figure explaining the relationship of the contact angle of a recording medium and an absorption roll The figure explaining the experiment which calculates | requires the relationship of the surface property of a recording medium and an absorption roll 1 is an overall configuration diagram of an inkjet recording apparatus according to an application example of the invention FIG. 12 is a configuration diagram of a main part of a liquid removing unit of the ink jet recording apparatus shown in FIG. FIG. 12 is a principal block diagram showing the system configuration of the ink jet recording apparatus shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Inkjet recording device, 16 ... Recording medium, 22 ... Adsorption belt conveyance part, 25 ... Liquid removal part, 72 ... System controller, 74 ... Memory, 80 ... Print control part, 85 ... Press control part, 87 ... Suction control part , 90 ... Program storage unit, 96 ... Media determination unit, 100, 300, 302, 304 ... Absorption roll, 104 ... Pressing arm, 108 ... Suction device, 308 ... Selection mechanism, 314 ... Up / down mechanism

Claims (7)

An ejection head for ejecting liquid onto a recording medium to form a desired image;
Conveying means for relatively conveying the recording medium and the ejection head;
A contact means provided on the downstream side in the transport direction of the recording medium with respect to the ejection head, and in contact with the liquid on the recording medium;
With
The contact means has a surface condition that the surface roughness is larger than the surface roughness of the recording medium, the surface free energy is smaller than the surface free energy of the recording medium, and the contact angle is the contact angle of the recording medium. An image forming apparatus characterized in that at least one of the smaller conditions is satisfied.   The image forming apparatus according to claim 1, wherein the contact unit includes a liquid removing unit that contacts the liquid on the recording medium and removes the liquid.   The contact means has a surface roughness of at least twice the surface roughness of the recording medium, a surface free energy of 1/2 or less of the surface free energy of the recording medium, and a contact angle of the recording medium. The image forming apparatus according to claim 1, wherein the image forming apparatus has at least one of contact angles of 1/2 or less. A plurality of the contact means having different physical properties of at least one of surface roughness, surface free energy and contact angle;
Switching means for selectively switching contact means for contacting liquid on the recording medium among the plurality of contact means;
The image forming apparatus according to claim 1, 2 or 3. Recording medium determining means for determining the type of the recording medium;
Switching control means for controlling the switching means based on the determination result of the recording medium determining means;
The image forming apparatus according to claim 4, further comprising: An ejection head for ejecting ink onto a recording medium to form a desired image;
Conveying means for relatively conveying the recording medium and the ejection head;
A contact means provided on the downstream side in the transport direction of the recording medium relative to the ejection head, and in contact with the ink on the recording medium;
With
The contact means has a surface condition that the surface roughness is larger than the surface roughness of the recording medium, the surface free energy is smaller than the surface free energy of the recording medium, and the contact angle is the contact angle of the recording medium. An ink jet recording apparatus characterized by satisfying at least one of the smaller conditions. The inkjet recording apparatus according to claim 6, further comprising a processing liquid discharge head that discharges a processing liquid that reacts with the ink and fixes a color material contained in the ink to the recording medium.

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