JP2005271418A - Image fixing apparatus and inkjet recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image fixing apparatus which enables the selection of a glossiness of an image to be fixed by a simple switching operation in one image fixing apparatus. <P>SOLUTION: The image fixing apparatus for fixing the image on a recording medium formed by using an ink comprising at least coloring material particles comprising a coloring material and a resin is equipped with a fixing unit having a plurality of fixing rolls adjacently arranged, wherein one of the fixing rolls is a heating roll, and thermally fixing the image on the recording medium by pinching and carrying the recording medium between a plurality of these fixing rolls, a fixing roll driving means for driving at least one of the fixing rolls, and a fixing unit moving means for moving the fixing unit so as to position a required fixing roll on an image recording face side of the recording medium, to solve the problem. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image fixing device, and more specifically, in fixing an image recorded on a recording medium using ink, liquid toner, dry toner, or the like containing color material particles containing a color material and a resin. The present invention relates to an image fixing apparatus and an ink jet recording apparatus capable of selecting glossiness to be imparted to an image.

  A thermal head method, an electromechanical transducer (piezo) method, an electrostatic drive method, or the like is used for an ink jet recording device (ink jet recording device). In general, the ink used in the inkjet printer includes a dye-based ink obtained by dissolving a dye in an aqueous or non-aqueous solvent, a pigment-based ink in which a pigment is dispersed in an aqueous or non-aqueous solvent, and a pigment. Ink or the like in which color material particles (colored particles) in which a color material such as a dye and a resin are combined is dispersed in a solvent is used.

  The fixing of the image after drawing with the dye-based ink and the pigment-based ink is performed by evaporation of the ink solvent or penetration into the recording medium. On the other hand, fixing an image after drawing with ink in which color material particles are dispersed in a solvent fixes the image by fusing a resin combined with the color material onto the recording medium by applying heat after drawing. This is performed by the heat fixing method. As a fixing device using a heat fixing method, it is effective to use a heating roll fixing device that fixes an image on a recording medium by contact heating because of good thermal efficiency, ease of handling, and ease of device configuration.

  In fixing processing by a heating roll fixing device, it is known that differences in fixing conditions such as the temperature and material of the heating roll, the conveyance speed of the recording medium by the heating roll, and the nipping force (nip force) affect the fixability. .

The heating roll fixing device is also used in an electrophotographic image forming apparatus. For example, Patent Document 1 discloses an image forming apparatus in which an unfixed toner image is formed on a recording sheet by electrophotographic recording, and then the unfixed toner image is fixed by a fixing device including a heating roller and a pressure roller. Describes an image forming apparatus that changes the control temperature of the heating roller, the nip width, and the conveyance speed of the recording paper according to the length of the recording paper, the paper thickness, and the surface property (rough or not). According to this image forming apparatus, it is easy to cause a drop in the temperature of the heating roller under the same fixing conditions as normal regular size copy, such as long paper, thick paper, paper with poor surface properties and poor fixability, It is said that the deterioration of image quality due to a drop in fixing temperature can be prevented even for recording paper that is liable to cause fixing failure.
Japanese Patent Laid-Open No. 8-220928

  By the way, since the ink jet recording apparatus is capable of high image quality and high speed recording due to recent technological advances, applications such as color proofing and full color on-demand printing are considered. In color proof, full-color on-demand printing, and the like, it is required to form an image with a texture that approximates an offset print. Of the factors that change the texture of an image, it is extremely important to reproduce glossiness.

  The glossiness of an image by offset printing differs depending on the type and nature of the recording medium, and basically becomes an image having a glossiness corresponding to the surface roughness of the recording medium. For example, if the recording medium is art paper with a small surface roughness, the glossiness of the image is high, and if the recording medium is a fine paper with a large surface roughness, the glossiness of the image is lower than that of the art paper. .

  On the other hand, the glossiness of an image formed by an ink jet recording apparatus is strongly influenced by the size of the particle component of the ink used and the fixing conditions. In particular, in the case of an ink jet recording apparatus in which an image recorded with ink in which color material particles are dispersed in a solvent is fixed by a heating roll fixing device, the surface of the heating roll is pressed against the color material particles or the like and deformed. Because the image is fixed, the surface roughness of the image after fixing changes depending on the hardness, surface roughness, or material of the heating roll, even within the range of fixing conditions where good fixability can be obtained. Sex changes. Therefore, in such an ink jet recording apparatus, even if an image is formed on different recording media such as art paper and high-quality paper, the glossiness of the obtained image does not necessarily correspond to the recording medium. There is a problem that it is difficult to obtain an image having an approximate texture.

  Further, the fixing device in the electrophotographic image forming apparatus described in Patent Document 1 described above is based on the surface properties (roughness or not) of the recording paper, and the like. The paper transport speed is changed to obtain good fixability, but even with such a fixing device, as long as fixing is performed with the same heating roller, the glossiness of the fixed image is clearly defined. It cannot be changed, and it is difficult to form an image having a texture similar to offset printing on each of art paper and high-quality paper.

  In order to give different glossiness corresponding to each of art paper and high-quality paper, it is conceivable to prepare a plurality of heating rolls having different hardness, surface roughness, or material. However, when the heating roll is replaced each time the recording medium is changed, there is a problem that the operation becomes complicated and the productivity is lowered.

  An object of the present invention is an image fixing apparatus that solves the above-mentioned problems of the prior art and fixes an image recorded on a recording medium using an ink containing color material particles containing a color material and a resin, It is an object of the present invention to provide an image fixing device capable of selecting the glossiness of an image to be fixed by a simple switching operation in one image fixing device, and in particular, art paper and glossiness are desired for the image after fixing. Fixing to two or more types of recording media that require different glossiness, such as high-quality paper that is not desired or matte, so that the glossiness of the image corresponds to the type of recording media. An object of the present invention is to provide an image fixing apparatus and an ink jet recording apparatus which can be used.

In order to solve the above problems, the present invention provides an image fixing device for fixing an image on a recording medium formed using an ink containing at least a color material particle containing a color material and a resin.
There are a plurality of fixing rolls arranged adjacent to each other, and one of the fixing rolls is a heating roll. The recording medium is sandwiched and conveyed between the plurality of fixing rolls to thermally fix the image on the recording medium. A fixing unit to
Fixing roll driving means for driving at least one of the fixing rolls;
An image fixing apparatus comprising: a fixing unit moving unit that moves the fixing unit so that a desired fixing roll is positioned on the image recording surface side of the recording medium.

Here, the fixing unit moving means preferably rotates and / or translates the fixing unit.
Further, the fixing unit includes a support member that pivotally supports the plurality of fixing rolls,
Preferably, the fixing unit moving means rotates and / or translates the support member so that a desired fixing roll is positioned on the image recording surface side of the recording medium.

The plurality of fixing rolls are preferably different in at least one of hardness, surface roughness and material of the surface layer.
Here, the material of the surface layer of the fixing roll includes surface properties including a surface shape pattern, physical properties of substances constituting the surface layer, and chemical properties such as oil amount and ink resistance due to the constituent components. .

  Further, it is preferable to have a clamping force adjusting means for adjusting the clamping force of the recording medium by the fixing roll, and it is preferable to have a temperature adjusting means for adjusting the roll surface temperature of the fixing roll.

The present invention also provides an ink jet recording apparatus comprising the ink jet recording means and any of the image fixing devices described above.
Here, it is preferable that the ink jet recording means perform image recording by ejecting, by electrostatic force, ink in which color material particles containing a charged color material and a resin are dispersed in at least a solvent.

  According to the image fixing device and the ink jet recording apparatus of the present invention, in fixing of an image recorded using an ink containing color material particles containing at least a color material and a resin, preferably the hardness, surface roughness and material of the surface layer Among the two or more fixing rolls, each of which is different from each other, a fixing roll suitable for obtaining a desired image glossiness is disposed at a position in contact with the image recording surface by a simple switching operation to perform the fixing process. It is possible to obtain images having different glossiness with one image fixing device.

  Such an image fixing device and an ink jet recording apparatus of the present invention use ink in which charged color material particles containing a color material and a resin are dispersed in a solvent, and eject ink by applying an electrostatic force to the ink. Thus, it is useful to use as an image fixing means in an electrostatic ink jet recording apparatus that records a high quality image. That is, the image fixing device and the ink jet recording apparatus of the present invention are provided in an electrostatic ink jet recording apparatus for color proofing or full color on-demand printing capable of high image quality recording, so that the image after fixing is desired to be glossy. Images are fixed to two or more types of recording media that require different glossiness, such as art paper and high-quality paper that does not require glossiness, so that the glossiness corresponds to the type of recording media. be able to. This makes it possible to change the gloss according to the paper quality in the calibration of the main paper in DDCP (Direct Digital Color Proofing). For example, it is possible to form an image that reproduces the desired glossiness on each of art paper and high-quality paper. And an inferior image can be obtained as a color proof or full color on-demand print.

  An image fixing apparatus according to the present invention will be described in detail below based on a preferred embodiment shown in the accompanying drawings.

1 to 3 are views showing an image fixing device 10 which is an embodiment of the image fixing device of the present invention.
The image fixing device 10 includes a pair of fixing rolls 12A and 12B arranged adjacent to each other, and moving side plates 14L and 14R as a pair of support members that pivotally support both shaft ends of the fixing rolls 12A and 12B. A fixing unit, fixing roller driving means including fixing roller driving mechanisms 20A and 20B for driving the fixing rollers 12A and 12B, and a pair of fixed side plates 16L and 16R for rotatably supporting the moving side plates 14L and 14R described above; Fixing unit moving means having a rotation mechanism 22 for rotating the moving side plates 14L, 14R described above via the fixed side plates 16L, 16R.
The image fixing apparatus 10 also guides the recording medium P to the fixing roll holding mechanisms 18L and 18R that fix both shaft ends of the fixing rolls 12A and 12B to the moving side plates 14L and 14R, and the fixing rolls 12A and 12B. The guide mechanism 24 (refer FIG. 2) which performs, and the movement side board positioning mechanism 26 attached to the movement side board 14R are provided.

  Although not shown in the drawings, in the vicinity of the image fixing device 10, a conveying unit that carries an image recording medium P (hereinafter simply referred to as recording medium P) into the image fixing device 10 and after the fixing process in the image fixing device 10. Conveying means for carrying out the recording medium P is provided close to the paper feed guide 70 (see FIG. 2) of the guide mechanism 24.

  The image fixing device 10 conveys a recording medium P on which an image is recorded and sent by a conveying means (not shown) while being sandwiched between a pair of fixing rolls 12A and 12B, which are heat rolls. Fix unfixed images. The image fixing apparatus 10 includes fixing rolls 12A and 12B having different surface hardness, surface roughness, and material, and the position of the fixing rolls 12A and 12B can be reversed with respect to the conveyance path of the recording medium P. Have. That is, the fixing roll contacting the image recording surface of the recording medium P can be selected from two fixing rolls 12A and 12B.

  As shown in FIG. 1, the fixing rolls 12A and 12B have cylindrical core members 30A and 30B made of a metal material at the body portions, and both ends thereof are closed with lids 36A and 36A; 36B and 36B. Yes. The lids 36A, 36A; 36B, 36B are provided with hollow rotating shafts 38A, 38A; 38B, 38B, which have the same axis as the cores 30A, 30B, and extend outward.

  Inside the fixing rolls 12A and 12B, a lamp heater 40 as a heating source passes through the core members 30A and 30B and the rotary shafts 38A and 38A; Yes. The lamp heater 40 is disposed so that its heat radiating portion extends over the entire width of the core members 30A and 30B, and both end portions thereof protrude from the rotary shafts 38A and 38A; 38B and 38B. It is fixed to ring gears 64L and 64R described later. That is, the lamp heater 40 is fixedly held by a member that holds the fixing rolls 12A and 12B independently of the fixing rolls 12A and 12B that rotate (spin). The lamp heater 40 has its heat generation adjusted by a temperature adjusting means (not shown) in order to adjust the surface temperature of the fixing rolls 12A and 12B to a predetermined temperature.

As the fixing rolls 12A and 12B, various types can be used as long as the body has a predetermined surface roughness and elasticity (easily deformable).
As an example, a roll having a single layer structure in which a core material (substrate) of the roll is covered with an elastic layer; a roll having a two-layer structure in which an elastic layer is further covered with a release layer; and between the elastic layer and the release layer, A three-layer roll having an intermediate layer is exemplified.

  Various roll core materials having sufficient strength against pressurization can be used, but those made of a material having good thermal conductivity are preferred. Specific examples include rolls of aluminum materials such as A5056, A5052, A5083, and A6063, and rolls of nonmagnetic stainless steel materials such as STKM11. In the illustrated example, since a heating source (lamp heater 40) is built in the fixing rolls 12A and 12B, a hollow cylindrical body is used. In addition, when it does not have a heating source, the heat conductivity of a core material does not necessarily need to be high.

The elastic layer may be formed of synthetic rubber such as silicone rubber or fluorine rubber. In particular, in the case of a single layer configuration, LTV (low temperature vulcanization type) silicone rubber that is excellent in releasability from the recording medium P after image recording is preferably exemplified.
Moreover, in order to improve the thermal conductivity at the time of heat-fixing, it is preferable that these synthetic rubbers contain 5 to 30% by weight of a metal oxide powder such as silica, alumina or magnesium oxide as a filler. For the same reason, conductive carbon black may be used as the filler. In this case, the electrical resistance of the elastic layer can be reduced to prevent charging. The elastic layer has a thickness of 1 to 8 mm. The rubber hardness is a value (hereinafter referred to as JIS A) measured using a type A durometer defined in JIS K 6253-1997, and is adjusted to a value suitable for the present invention.

  The release layer is for improving release properties from the recording medium P. The release layer may be formed, for example, by covering the elastic layer with a tube made of PFA (fluororesin), or by forming a fluororesin paint such as PTFE, PFA, FEP or the like on the surface of the elastic layer. Also good. The release layer has a thickness of 10 to 100 μm. The fluororesin is harder than synthetic rubber such as silicone rubber and fluororubber, and is suitable for crushing the color material particles.

In addition, an elastic layer and a release layer are formed by forming an intermediate layer formed by mixing fluororubber and a fluororesin on the surface of the elastic layer and forming the release layer on the intermediate layer. A fixing roll having a three-layer structure is also preferable in order to improve adhesion to the layer and prevent damage (such as generation of cracks) of the release layer due to the buffering action of the intermediate layer.
Further, an HTV (high temperature vulcanization type) silicone rubber having excellent heat resistance is used as the elastic layer, and a fluorine rubber layer for preventing swelling of the elastic layer is provided thereon as an intermediate layer, and a release layer is provided on the intermediate layer. A fixing roll having a three-layer structure in which an LTV silicone rubber layer is provided is also suitable. The surface roughness Ra of the outermost layer is adjusted in the range of 0.03 to 5 μm.

  In the illustrated example, the fixing roll 12A has a two-layer configuration in which an elastic layer 32A is provided on the surface of the core material 30A, and a release layer 34 is provided on the surface. The elastic layer 32A is made of silicone rubber having a rubber hardness of 20 JIS A and a thickness of 2 mm, and the release layer 34 is made of PFA having a thickness of 50 μm and a surface roughness Ra = 0.1 μm.

  The fixing roll 12B has a single-layer configuration in which an elastic layer 32B is provided on the surface of the core material 30B. The elastic layer 32B is made of a silicone rubber having a rubber hardness of 20 JIS A similar to the elastic layer 32A of the fixing roll 12A, and has a thickness of 3 mm and a surface roughness Ra = 0.3 μm. In order to improve the offset property, a release agent such as silicone oil can be applied on the fixing roll 12B.

  The fixing roll 12A and the fixing roll 12B are different in surface roughness, hardness and material of the surface layer. That is, in the surface layer of the fixing roll 12A (release layer 34 on the elastic layer 32A) and the surface layer of the fixing roll 12B (elastic layer 32B), the fixing roll 12A has higher hardness, lower elasticity, and surface roughness. Is getting smaller. Further, since the material is PFA, the fixing roll 12A has better ink releasability. Which of the fixing roll 12A and the fixing roll 12B is arranged so as to be in contact with the image surface of the recording medium P is selected according to the desired glossiness of the image after fixing.

Here, selection of the layer configuration of the printing paper and roll will be described.
In the present embodiment, for example, the fixing roll 12A is used for art paper and the fixing roll 12B is used for high-quality paper so that the gloss can be changed according to the paper quality of the recording medium P in the paper calibration. .
In art paper, it is preferable that the color material particles forming the image on the recording medium P are crushed and flattened to develop gloss. For this purpose, it is necessary to make the hardness of the outermost surface of the fixing roll 12A harder than the hardness of the colorant particles heated to the fixing temperature. The outermost surface of the roll (release layer 34) is made of fluororesin. Hardness is optimal. Furthermore, although art paper has a relatively small surface roughness and is flat, it still does not exhibit sufficient gloss unless the image color material particles formed in the concave portions of the paper are crushed. Therefore, the thickness of the PFA of the outermost layer (release layer 34) is reduced to 10 to 50 μm so that the surface of the PFA is deformed along the unevenness of the paper and reaches the colorant particles in the recesses so as to be crushed. The thinner the PFA layer (release layer 34), the better. However, if the thickness is 10 μm or less, the durability is lowered.
The elastic layer 32A is optimally an HTV (high temperature vulcanization type) silicone rubber having excellent heat resistance, and its hardness is preferably about 1 to 40, more preferably about 3 to 20 in JIS A. If the rubber hardness is 3 or less, the durability may be lowered.
The thickness of the elastic layer 32A is set to about 2 to 5 mm so that the nip width can be widened to increase the heating time. Further, since the surface of the PFA (release layer 34) is hard, the PFA surface is printed on the color material image surface when crushed, so the surface roughness Ra of the PFA is set to about 0.03 to 5 μm.

  Subsequently, in the case of high-quality paper, it is better not to develop gloss, so the hardness of the outermost surface of the fixing roll 12B is made softer than the hardness of the color material particles heated to the fixing temperature, In order to leave the granularity, it is preferable to provide a single rubber elastic layer 32B of rubber, particularly a silicone rubber having a hardness of JIS A 10-30. The thickness of the elastic layer 32B is preferably 1 to 3 mm. Even if the surface roughness Ra is large, the surface shape is not printed, so it may be 1 to 5 μm.

  In the present embodiment, the fixing rolls 12A and 12B have the same cores 30A and 30B, lids 36A and 36B, and rotary shafts 38A and 38B. The dimensions such as diameter, thickness, width, shaft diameter and length may not be the same between the fixing roll 12A and the fixing roll 12B, and may be appropriately designed.

  In particular, regarding the shape of the cross section in the axial direction of the fixing rolls 12A and 12B, the thicknesses of the cores 30A and 30B and the elastic layer are usually made constant. The thickness may be changed depending on the position, and a so-called crown shape or reverse crown shape may be used.

As the fixing rolls 12A and 12B, in addition to the above, the core materials 30A and 30B are covered with a sponge-like foam rubber layer using a foam material such as a silicone rubber layer, a fluorine rubber layer, or silicone rubber. The soft roll formed can be used suitably. Furthermore, a hard roll formed by coating the core materials 30A and 30B with a fluororesin such as PTFE, PFA, or FEP, a PFT tube, or the like can also be suitably used.
Various known rolls can be used as the fixing rolls 12A and 12B as long as they can withstand the pressing force for heat fixing. Needless to say, the roll containing the heat source is preferably formed of a material having high thermal conductivity.

  The fixing rolls 12A and 12B are arranged so that the axes of the fixing rolls 12A and 12B are in parallel with each other and the roll surface is in uniform contact with the entire roll width. The rotation shafts 38A, 38A and 38B, 38B of the fixing rolls 12A and 12B are held by moving side plates 14L and 14R arranged on both shaft end sides of the fixing rolls 12A and 12B by fixing roll holding mechanisms 18L and 18R described later. Has been.

  The moving side plates 14L and 14R are disk-shaped members having sufficient strength and area to hold the rotating shafts 38A and 38B, and the fixing rolls 12A on both sides (left and right sides in FIG. 1) of the fixing rolls 12A and 12B. And 12B are arranged so that their surfaces are perpendicular to the axial direction of the fixing rolls 12A and 12B and the surfaces are parallel to each other. The moving side plates 14L and 14R are provided with two holes into which bearings 48L and 48R, which are support members that rotatably support the rotating shafts 38A and 38B, are fitted. The movable side plates 14L and 14R are fitted and held in the fixed side plates 16L and 16R. The fixed side plate 16L and the fixed side plate 16R include a plurality of (four in the illustrated example) shafts 45, bolts, nuts, and the like. It is fixedly connected using a fastener (see FIGS. 2 and 3). The moving side plates 14L, 14R rotate together with respect to the fixed side plates 16L, 16R by the action of the rotation mechanism 22.

  The fixed side plates 16L and 16R are rectangular flat plates having a hole portion having a diameter slightly larger than the outer diameter of the moving side plates 14L and 14R. The fixed side plates 16L and 16R are arranged with their surfaces parallel to each other at a predetermined interval for arranging the fixing rolls 12A and 12B between them, and a plurality of them (four in the illustrated example). The shaft 46 and a fastener such as a bolt or nut are fixedly connected. The fixed side plates 16L and 16R support almost all members of the image fixing device 10, and the fixed side plates 16L and 16R themselves are fixed at predetermined positions by arbitrary fixing means.

  The movable side plates 14L and 14R are fitted in the respective holes of the fixed side plates 16L and 16R via the buffer members 44. The buffer member 44 is for reducing sliding friction when the moving side plates 14L, 14R rotate with respect to the fixed side plates 16L, 16R, and is provided substantially uniformly over the entire circumference of the moving side plates 14L, 14R. preferable. The buffer member 44 only needs to buffer the friction between the moving side plates 14L, 14R and the fixed side plates 16L, 16R, and may be provided with a lubricant such as a resin member or grease, or may be provided with rollers. A mechanical configuration may be provided. Alternatively, when the material of the moving side plates 14L and 14R and the fixed side plates 16L and 16R are selected and the friction of the sliding portion can be sufficiently reduced, and the force required to rotate the moving side plates 14L and 14R is not increased. The buffer member 44 may not be provided.

The ring gears 64L and 64R are disk-shaped members having a diameter larger than that of the moving side plates 14L and 14R, and gears are formed on the outer peripheral portions thereof. The ring gears 64L and 64R are also
Holes of the same shape are formed at positions corresponding to the holes for holding the rotating shafts 38A and 38B opened in the moving side plates 14L and 14R. The ring gears 64L and 64R are fixed to the outer surfaces (surfaces opposite to the fixing rolls 12A and 12B) of the moving side plates 14L and 14R, and are integrated with the moving side plates 14L and 14R. Of course, the ring gear 64L (64R) and the moving side plate 14L (14R) may be integrally formed.

  Since the ring gears 64L and 64R have a larger outer diameter than the holes of the fixed side plates 16L and 16R, the axial position of the fixing roll 12A (12B) is the outer surface of the fixed side plates 16L and 16R. It is determined at a position where it abuts. Thereby, the position toward the inner side (fixing rolls 12A, 12B side) in the axial direction of the moving side plates 14L, 14R integrated with the ring gears 64L, 64R is determined, and the inner side of the fixed side plates 16L, 16R is determined. There is no deviation. In order to reduce sliding friction between the ring gears 64L and 64R and the fixed side plates 16L and 16R when the moving side plates 14L and 14R rotate, at least a part between the ring gears 64L and 64R and the fixed side plates 16L and 16R. In the same manner as the buffer member 44, it is preferable to interpose a buffer member. The ring gears 64L and 64R constitute the rotation mechanism 22, and the operation as the rotation mechanism 22 will be described in detail later.

  The fixing roll holding mechanisms 18L and 18R hold the rotary shafts 38A, 38A and 38B and 38B on the both sides of the fixing rolls 12A and 12B on the moving side plates 14L and 14R, respectively. It comprises a catch 50 and nip pressure urging tools 52 and 52.

  First, the fixing roll holding mechanism 18L on the left side in FIG. 1 of the fixing roll 12A will be described. In FIG. 1, a left bearing (bearing holder) 48L for holding the fixing roll 12A is inserted from one side of the two holes provided in the fixed side plate 16L and the ring gear 64L from the outside (the side opposite to the fixing roll 12A). Thus, the left rotation shaft 38A is supported. The axial position of the bearing 48L is prevented from shifting inward (fixing roll 12A side) by a holder portion that is larger than the hole diameter of the ring gear 64L, and the bearing stopper 50 provided outside the bearing 48L. The outward displacement is prevented.

  A nip pressure urging tool 52 that presses the bearing 48L toward the fixing roll 12B is attached to the bearing 48L of the fixing roll 12A. The nip pressure urging tool 52 is a clamping force adjusting unit that adjusts the nip pressure (clamping force) of the recording medium P by the fixing rolls 12A and 12B. By pressing the bearing 48L, the fixing roll 12A held by the bearing 48L. Is pressed in the direction of the fixing roll 12B to urge the nip pressure (clamping pressure) of the recording medium P by the fixing rolls 12A and 12B. The nip pressure urging tool 52 is configured to compress a coil spring by tightening a bolt and obtain a pressing force of the bearing 48L by its repulsive force. The nip pressure urging tool 52 having such a configuration can obtain a predetermined pressing force by selecting a coil spring and adjusting a bolt tightening amount (coil spring compression amount) with an extremely simple configuration. In addition, as the nip pressure urging tool 52, other known pressing means such as an air cylinder can be used.

  The bearing 48L of the fixing roll 12A is non-rotatable when fitted in the holes of the moving side plate 14L and the ring gear 64L, and is in the direction of the opposing fixing roll 12B, that is, the nip by the nip pressure urging tool 52. The sliding movement is possible only in the pressing direction (vertical direction in the figure). Such a mechanism can be realized by the following configuration, for example. That is, as the bearing (holder) 48L, a bearing having a pair of parallel surfaces at the fitting portions into the holes of the moving side plate 14L and the ring gear 64L is used, and the bearings are provided in the holes of the moving side plate 14L and the ring gear 64L. A parallel wall corresponding to the parallel surface of 48L is formed in parallel with the nip pressure urging direction by the nip pressure urging tool 52 to be longer than the length of the fitting portion of the bearing 48L. As a result, the bearing 48L cannot rotate between the parallel walls and is slidable in the nip pressure urging direction while being guided by the parallel walls.

  In the holes of the fixed side plate 16L and the ring gear 64L, gaps 54a and 54b for moving the bearing 48L are provided above and below the bearing 48L, respectively. The gaps 54a and 54b are generated when the fixing rolls 12A and 12B are turned upside down by the amount of movement of the fixing roll 12A (bearing 48L) due to the magnitude of the nip pressure by the nip pressure urging tool 52 and the rotation of the moving side plate 14L. The optimum value is set with respect to the amount of movement of the fixing roll 12A (bearing 48L) due to the weight of the fixing rolls 12A and 12B. That is, the gap 54b on the fixing roll 12B side (fixing portion side) moves the fixing roll 12A (bearing 48L) so as not to hinder the movement of the fixing roll 12A due to the urging force from the nip pressure urging tool 52. The interval is set slightly wider than that. On the other hand, the gap 54a on the side opposite to the fixing roll 12B is set small, and the movement of the fixing roll 12A in the direction away from the fixing roll 12B is suppressed.

  In the image fixing device 10, when the fixing rolls 12A and 12B are turned upside down from the state shown in FIG. 1 and the fixing roll 12A is on the lower side, the bearing 48L of the fixing roll 12A has a roll weight of the fixing rolls 12A and 12B. However, by reducing the gap 54a on the side opposite to the fixing roll 12B, the amount of movement toward the gap 54a due to the roll weight can be minimized. Thereby, the fluctuation of the nip pressure when the fixing rolls 12A and 12B are turned upside down can be minimized.

The nip pressure urging tool 52 is also provided on the fixing roll holding mechanism 18R on the right side of the fixing roll 12A in FIG. 1, and by pressing the both sides of the fixing roll 12A evenly by the nip pressure urging tools 52, 52, The nip pressure is biased evenly in the axial direction of the fixing roll 12A.
Further, in the fixing roll holding mechanism 18R on the right side of the fixing roll 12A, the configuration of the fitting portion of the bearing 48R into the fixed side plate 16R and the ring gear 64R and the hole portion of the fixed side plate 16R and the ring gear 64R are also on the left side of the fixing roll 12A. The fixing roll holding mechanism 18L has the same configuration as that of the fixing roll holding mechanism 18L, and the fixing roll 12A can be slid in the nip pressure urging direction (parallel movement) while maintaining the axial direction.

  In the fixing roll holding mechanism 18R on the right side of the fixing roll 12A, the sprocket 56A prevents the bearing 48R from shifting to the outside in place of the bearing stopper 50 of the left fixing roll holding mechanism 18L. The sprocket 56A is attached in the vicinity of the end portion of the right rotation shaft 38A, and is fixed to the rotation shaft 38A by, for example, a squeezing screw. The sprocket 56A has a function as the fixing roll driving mechanism 20, which will be described later.

  The fixing roll holding mechanisms 18L and 18R of the fixing roll 12B have basically the same configuration as the fixing roll holding mechanisms 18L and 18R of the fixing roll 12A described above, except that the nip pressure biasing tool 52 is not provided. doing. That is, the bearings 48L, 48R are not rotatable when fitted in the holes of the moving side plate 14L and the ring gear 64L, and are slidable in the direction of the opposing fixing roll 12A (the vertical direction in the figure). In addition, since the gap 54a on the side opposite to the fixing roll 12A is set small, the movement of the fixing roll 12B in the direction away from the fixing roll 12A is suppressed.

  In the example of FIG. 1, the nip pressure urging tool 52 is not attached to the bearings 48L and 48R of the fixing roll 12B, but this is because the fixing rolls 12A and 12B are reversed and the fixing roll 12B is on the upper side. This is an example in which the nip pressure required at the fixing portion (the contact portion between the fixing rolls 12A and 12B) by the fixing rolls 12A and 12B is obtained by the weight of the fixing roll 12B itself. Of course, the nip pressure urging tool 52 may be attached to the bearings 48L and 48R of the fixing roll 12B as well as the fixing roll 12A.

  As shown in FIGS. 1 and 3, the fixing roll driving mechanism 20 includes a driving motor and speed reducers 60A and 60B for rotationally driving the fixing rolls 12A and 12B, and sprockets 62A and 60B attached to the driving motors 60A and 60B. 62B, sprockets 56A and 56B attached to the right rotation shafts 38A and 38B in FIG. 1 of the fixing rolls 12A and 12B, the drive motor side sprockets 62A and 62B, and the fixing roll side sprockets 56A and 56B, respectively. Chain 58A, 58B, and control means for drive motors 60A, 60B (not shown). Although not shown, a reduction gear is provided between the drive motors 60A and 60B and the sprockets 62A and 62B to adjust the transmission speed of the drive motors 60A and 60B.

  The drive motors 60A and 60B are attached to the outer surface of the right ring gear 64R (moving side plate 14R) in FIG. The drive motors 60A and 60B are controlled by control means (not shown). The members constituting the fixing roll driving mechanism 20 are all supported by the moving side plate 14R (ring gear 64R) except for the control means of the drive motors 60A and 60B. Therefore, even when the moving side plate 14R rotates, the fixing roll There is no difference in the configuration of the drive mechanism 20, and the drive of the fixing rolls 12A and 12B is not affected.

  When the sprocket 62A is rotated by the operation of the drive motor 60A, the chain 58A wound around the sprocket 62A is rotated, whereby the sprocket 56A is rotated and the fixing roll 12A is rotated. Similarly, when the sprocket 62B is rotated by the operation of the drive motor 60B, the chain 58B wound around the sprocket 62B is rotated, the sprocket 56B is rotated, and the fixing roll 12B is rotated. As the fixing roll 12A or the fixing roll 12B is rotationally driven in this way, the recording medium P conveyed between the fixing roll 12A and the fixing roll 12B is nipped and conveyed.

  The drive motors 60A and 60B rotate the fixing rolls 12A and 12B in the direction in which the recording medium P is conveyed. In the example of FIGS. 1, 2A and 3, the fixing roll 12B on the side in contact with the opposite side of the image recording surface (hereinafter simply referred to as the recording surface) of the recording medium P is driven. At this time, the sprocket 62B on the driving side of the fixing roll 12B is neutral, and the fixing roll 12B rotates with the recording medium P conveyed by the driving force of the fixing roll 12A. In this way, by driving the fixing roll on the recording surface side of the recording medium P, it is possible to suppress the occurrence of image rubbing (image flow, deviation) during fixing.

  In the image fixing device 10, the fixing roll contacting the recording surface of the recording medium P is replaced when the moving side plates 14 </ b> L and 14 </ b> R rotate 180 degrees. When the fixing roll 12B is arranged on the upper side in the drawing by the rotation of the moving side plates 14L and 14R and is on the recording surface side of the recording medium P, the fixing roll 12B is driven by the drive motor 60B and the fixing roll 12A is rotated. .

  When the roll to be driven is changed corresponding to the fixing roll arranged on the recording surface side as in the present embodiment, the rotation directions of the drive motors 60A and 60B are determined to be constant directions, and the drive motor 60A. , 60B to be driven is switched by control means of drive motors 60A, 60B (not shown).

  As for the driving of the fixing rolls 12A and 12B, the fixing roll having the higher friction coefficient with the recording medium P may be driven. By using a fixing roll having a higher friction coefficient with the recording medium P as a driving roll, the recording medium P can be conveyed with high accuracy. In this case, regardless of the arrangement on the recording surface side and the non-recording surface side, the fixing roller to be driven is determined to be one by the configuration of the surface layer of the fixing roller. 60B may be provided, but the rotation direction differs between when the drive roll is on the recording surface side (upper side in the figure) and when it is on the non-recording surface side (lower side in the figure). The rotation direction is switched by the control means 60B.

  Alternatively, both the drive motors 60A and 60B may be operated to drive both the fixing rolls 12A and 12B simultaneously. When both the fixing rolls 12A and 12B are driven, the peripheral speeds of the fixing rolls 12A and 12B are set to be the same in order not to apply a shearing stress or a surface friction force during the conveyance of the recording medium P. Thus, it is important to control the drive motors 60A and 60B. Further, when the moving side plates 14L and 14R are rotated and the positions of the fixing rolls 12A and 12B are reversed, the rotation directions of the fixing rolls 12A and 12B are reversed. Therefore, the rotation direction is controlled by the control means of the drive motors 60A and 60B. Is switched.

In the fixing roll driving mechanism 20, as a means for transmitting the power of the drive motors 60 </ b> A and 60 </ b> B to the fixing rolls 12 </ b> A and 12 </ b> B, well-known transmission means such as belt transmission can be used in addition to the above-described chain and sprocket. .
Further, depending on the characteristics of the color material, the color material may adhere to the roll surface. In that case, when the recording medium is not passed, the circumferential speed of the fixing rolls 12A and 12B is shifted by 0.1 to 3% to remove the color material attached by the roll itself.

  The rotation mechanism 22 includes ring gears 64L and 64R, a movable side plate rotation motor 66 fixed to the outside, a gear 68A, a gear 68B and a gear 68C that constitute a speed reduction mechanism of the movement side plate rotation motor 66, and a movement side plate rotation (not shown). It is comprised from the control means of the motor 66. FIG. 3 shows the rotation mechanism 22 on the moving side plate 14R (ring gear 64R) side (right side in FIG. 1). As shown in FIGS. 1 and 3, the moving side plate rotating motor 66 and the gears 68A and 68B are provided only on the moving side plate 14R (ring gear 64R) side.

  The gear 68C is provided on both outer sides of the moving side plates 14L and 14R so as to engage with the ring gears 64L and 64R (the gear 68C on the moving side plate 14L side is not shown), and both the gears 68C and 68C are Are connected by a shaft (not shown). Accordingly, the power transmitted to one 68C is also transmitted to the other 68C, and rotates both the moving side plates 14L and 14R by the same angle at the same timing.

  The rotation mechanism 22 rotates the ring gears 64L and 64R by sequentially transmitting the rotational power of the moving side plate rotation motor 66 to the gears 68A, 68B and 68C and 68C, and is integrated with the ring gears 64L and 64R. The moving side plates 14L and 14R are rotated to reverse the positions of the fixing rolls 12A and 12B. The moving side plate rotation motor 66 has sufficient power to rotate the moving side plates 14L and 14R together with the members such as the fixing rolls 12A and 12B and the fixing roll driving mechanism 20 supported by the moving side plates 14L and 14R. In addition, the rotation angle can be controlled. For example, a stepping motor or the like is used.

  The rotation mechanism 22 is controlled by the control means in accordance with the detection results of the movement side plates 14L and 14R obtained from the movement side plate positioning mechanism 26.

  The moving side plate positioning mechanism 26 includes limiters 76 and 76 fixed to two predetermined positions of the fixed side plate 16R, and a contact member 78 fixed to a predetermined position of the ring gear 64R. As shown in FIG. 3, the limiters 76, 76 are arranged on the outer side of the ring gear 64R on the fixed side plate 16R with a 180 degree separation in the rotational direction of the ring gear 64R. Further, the abutting member 78 is arranged on the outer peripheral portion on the ring gear 64R so that a part thereof protrudes from the outer periphery, and the protruding amount is set so as to push the limit switch of the limiter 76 at the position of the limiter 76. ing.

  In the movement side plate positioning mechanism 26, the contact member 78 moves by the rotation of the ring gear 64R and comes into contact with the limiter 76. When the limit switch of the limiter 76 is pushed in a predetermined amount, the movement side plates 14L and 14R reach a predetermined position. This is detected, and a signal is sent from the limiter 76 to the control means of the moving side plate rotation motor 66. When receiving the signal from the limiter 76, the control means of the movement side plate rotation motor 66 stops the rotation of the movement side plate rotation motor 66, thereby completing the rotation of the movement side plates 14L and 14R.

  Since the limiter 76 is disposed 180 degrees apart in the rotation direction of the moving side plate 14R (ring gear 64R), the moving side plates 14L and 14R are rotated by 180 degrees by the rotating mechanism 22 and the moving side plate positioning mechanism 26, respectively. The fixing rolls 12A and 12B attached to the moving side plates 14L and 14R are reversed.

  The moving side plate positioning mechanism 26 includes a light receiving unit, a light emitting unit, and the like in place of the limiter 76 and the abutting member 78 in addition to the mechanical ones as described above, and the moving side plates 14L and 14R are optically used. What detects the rotational position of may be used.

  The guide mechanism 24 includes a paper feed guide 70, a guide fulcrum 72, and guide pins 74 and 74. As shown in FIG. 2A, the guide mechanism 24 is provided symmetrically on the upstream side and the downstream side in the conveyance direction of the recording medium P of the fixing rolls 12A and 12B, and the recording carried into the image fixing device 10 is performed. The medium P is guided to a fixing portion (contact portion between the fixing rolls 12A and 12B) by the fixing rolls 12A and 12B, and the recording medium P that has passed through the fixing portions of the fixing rolls 12A and 12B is moved outside the image fixing apparatus 10. To guide.

  The guide fulcrum 72 is provided at a substantially equidistant position from the fixing rolls 12A and 12B, and the paper feed guide 70 is directed from the position of the guide fulcrum 72 toward the fixing portion of the recording medium P of the fixing rolls 12A and 12B. The guide surface extends and has a width substantially equal to the axial length of the fixing rolls 12A and 12B.

  The paper feed guide 70 is swingable about a guide fulcrum 72, and the swing width is regulated by a guide pin 74. In this way, by allowing the paper feed guide 70 to swing within a certain angle, the recording medium P can always easily enter the fixing portions of the fixing rolls 12A and 12B. Further, since the recording medium P moves flexibly when it abuts, the recording medium P is not damaged such as being bent.

  As shown in FIG. 2B, when the moving side plates 14L and 14R are rotated 180 degrees and the fixing rolls 12A and 12B are reversed, the paper feed guide 70 is shown in the drawing with the guide fulcrum 72 as a fulcrum by its own weight. The recording medium P moves to the lower side and reaches the position where the recording medium P is guided to the fixing unit on the upper surface of the paper feed guide 70 in the drawing, and the recording medium P is appropriately guided as in FIG.

Next, the operation of the image fixing device 10 will be described.
In the fixing of an image recorded using an ink containing color material particles containing a color material and a resin, when using art paper as the recording medium P, the hardness is high, the elasticity is small, the surface roughness is small, Fixing is performed by bringing the fixing roll 12A having good ink releasability into contact with the recording surface of the recording medium P. As shown in FIG. 2A, the moving side plates 14L and 14R of the image fixing device 10 are set in advance so that the fixing roll 12A is on the recording surface side (upper side in the figure).

  A recording medium P on which an image is recorded and has an unfixed image is carried into the image fixing device 10 with the recording surface facing up, and is positioned between the fixing rolls 12A and 12B by a paper feed guide 70 on the upstream side (right side in the figure). Guided to the fixing unit. Subsequently, the recording medium P is nipped and conveyed by the fixing rolls 12A and 12B, and heated and pressurized, whereby the image on the recording medium P is fixed.

  At this time, the fixing rolls 12A and 12B are heated to a predetermined temperature (for example, the surface temperature is 80 ° C.) by the lamp heater 40 and a temperature adjusting unit (not shown). The nip pressure (pressing force) by the fixing rolls 12A and 12B is set by the nip pressure urging tool 52. Further, the conveyance speed (fixing speed) of the recording medium P by the fixing rolls 12A and 12B, that is, the rotational speed of the fixing roll 12A is controlled by a drive motor 60A (the control means) for driving the fixing roll 12A.

  The recording medium P that has passed through the fixing rolls 12A and 12B is guided to the paper feed guide 70 on the downstream side (left side in the figure) and is carried out of the image fixing apparatus 10.

  The image fixed on the recording medium P exhibits a surface roughness corresponding to the fixing roll 12A in contact with the recording surface. That is, since the fixing roll 12A has a PFA layer with high hardness, small surface roughness, and good ink releasability on the surface layer, the color in the ink that forms an unfixed image on the recording medium P. The material particles are almost completely crushed and fixed on the surface of the fixing roll 12A at the time of heating and pressurizing the fixing rolls 12A and 12B. Therefore, it is possible to reduce the surface roughness of the image surface after fixing and obtain a smooth and glossy image.

  On the other hand, when high-quality paper is used as the recording medium P, fixing is performed by bringing the fixing roll 12B having low hardness, high elasticity, and large surface roughness as necessary into contact with the recording surface of the recording medium P. The moving side plates 14L and 14R of the image fixing device 10 are rotated 180 degrees from the state of FIG. 2A by the rotation mechanism 22, and the fixing roll 12B is moved to the recording surface side (upper side in the drawing) as shown in FIG. ).

  When rotation of the moving side plates 14L, 14R is instructed by an instruction input from the operator, the control means of the moving side plate rotating motor 66 operates the moving side plate rotating motor 66. The ring gears 64L and 64R and the movement side plates 14L and 14R are rotated by the rotation of the movement side plate rotation motor 66. When the limiter 76 detects that the ring gears 64L and 64R and the moving side plates 14L and 14R have reached predetermined positions by the contact member 78 attached to the ring gear 64R coming into contact with the limiter 76, the result is obtained. In response to this, the control means of the moving side plate rotating motor 66 stops the moving side plate rotating motor 66. As described above, the movable side plates 14L and 14R are rotated 180 degrees, and the fixing rolls 12A and 12B are reversed to be in the state of FIG.

  In the image fixing apparatus 10 in the state of FIG. 2B, the high-quality paper recording medium P having an unfixed image is heated by the fixing rolls 12A and 12B in the same manner as in the case of FIG. It is conveyed while being pressurized, the unfixed image on the recording medium P is fixed, and the recording medium P is discharged from the image fixing device 10. Here, the temperature, nip pressure, and fixing speed of the fixing rolls 12A and 12B are the same as in FIG. 1A, but the fixing roll 12B comes into contact with the recording surface of the recording medium P and fixing is performed. .

  The fixed image on the recording medium P obtained in this way exhibits a surface roughness corresponding to the fixing roll 12B in contact with the recording surface. That is, since the fixing roll 12B has a silicone rubber layer having a low hardness and a large surface roughness on the surface layer, the colorant particles in the ink that forms an unfixed image on the recording medium P are fixed on the fixing roll 12B. Even at the time of heating and pressurizing to 12A and 12B, the surface of the fixing roll 12B is hardly crushed, and although it is fused, it is fixed in a state where the graininess of the particles remains. Therefore, it is possible to obtain an image that does not exhibit gloss while maintaining the surface roughness of the image surface after fixing as large.

  As described above, the image forming apparatus includes the fixing roll 12A capable of obtaining an image expressing the desired gloss on the image on the art paper, and the fixing roll 12B capable of obtaining an image suppressing the desired gloss on the image on the high-quality paper, Depending on whether the recording medium P is art paper or high-quality paper, an appropriate fixing roll of the fixing roll 12A and the fixing roll 12B is arranged on the image recording surface side, and an appropriate fixing roll is recorded. By fixing in contact with the surface, an image having glossiness corresponding to the recording medium can be obtained.

  Therefore, an image recorded by an ink jet method or the like is fixed by an image fixing device 10 using an ink containing color material particles containing a color material and a resin, so that it can be applied to art paper in the same manner as an image by offset printing. Can record an image with high glossiness and an image with low glossiness on high-quality paper, and can satisfy the proofreading suitability of this paper for offset printing.

  In the above-described example, the image fixing device that fixes an image formed using an ink containing at least a color material particle containing a color material and a resin has been described. However, this is performed using liquid toner or dry toner. It is also possible to apply to an apparatus for fixing an image formed in this way.

  Further, in the above example, the fixing rolls 12A and 12B have two types of gloss desired for the image after fixing by using the surface layers having different hardness, surface roughness and material. However, if two fixing rolls having at least one of hardness, surface roughness, and material are used, the desired glossiness corresponding to the type of recording medium can be provided. Good.

  In the above example, the fixing conditions such as the heating temperature, pressure (nip pressure), and fixing speed of the fixing rolls 12A and 12B are used when either the fixing roll 12A or the fixing roll 12B is disposed on the image recording surface side. However, by selecting the fixing rolls 12A and 12B and setting the fixing conditions such as the heating temperature and the pressing force according to the type of the recording medium P, a wider variety of recording medium types (paper quality) Etc.), and the suitability for proofreading of the offset printing can be increased.

  For example, in the above example, the lamp heater 40 is provided in both the fixing rolls 12A and 12B. However, depending on the setting of the fixing conditions, the lamp heater 40 may be provided only in either the fixing roll 12A or 12B. Alternatively, the lamp heater 40 may be used or not used after being provided for both. The temperature of the lamp heater 40 may be different between the fixing rolls 12A and 12B.

  In addition, as described above, according to the type of the recording medium P, an image corresponding to offset printing can be obtained by bringing a fixing roll suitable for the recording medium P into contact with the image recording surface. However, in fixing images recorded on the same type of recording medium P, it is also possible to obtain images having different glossiness on the same type of recording medium P by switching the fixing roll 12A or 12B.

  In the above-described example, the fixing roll in contact with the recording surface of the recording medium P is changed by inverting the fixing rolls 12A and 12B with respect to the conveyance path of the recording medium P. This is because it is difficult to invert the recording medium P having an unfixed ink image without causing any defects such as image rubbing, image flow (image shift), or the like. This is because it is difficult to convey a landing ink image face down, and such a reversing device requires a plurality of pairs of rolls and guide plates, and is complicated.

  If the fixing rolls 12A and 12B are reversed as in this embodiment, the fixing roll for obtaining desired glossiness can be brought into contact with the image recording surface without inverting the front and back of the recording medium P. It is advantageous in that the apparatus can be made more compact and lower in cost than the form in which the recording medium P is reversed.

  However, the present invention is not limited to this, and if the image recording surface of the recording medium P and an appropriate fixing roll for obtaining an image desired for the recording medium P can be brought into contact with each other, the configuration is changed as appropriate. Alternatively, a means for inverting the recording medium P without affecting the image quality may be provided, and the fixing roll contacting the image recording surface may be selected by controlling the inverting means.

  Next, the ink used for image recording, which is the target of the image fixing device of the present invention, will be described. The image fixing device of the present invention is used as a fixing device of an image recorded using an ink containing color material particles containing a color material and a resin, thereby changing the surface roughness of the image after fixing, It exhibits a unique effect that the glossiness can be changed. Preferred examples of the ink containing the color material particles containing the color material and the resin include the following.

  That is, as the ink containing the color material particles containing the color material and the resin, the color material particles having a particle size of about 0.1 to 5 μm, preferably 0.5 to 2 μm, and more preferably 0.8 to 1.5 μm. Is obtained by dispersing in an aqueous solvent or a non-aqueous solvent. The color material particles contain a color material such as a pigment or a dye and a resin such as a dispersion resin for improving fixability. As a constitution of the color material particles, when a pigment is used as the color material, a method of coating the pigment with a resin material to obtain resin coated particles is generally used. When a dye is used, the dispersed resin particles are colored. A method of coloring with a material to form colored particles is common.

  As the coloring material, pigments and dyes that have been conventionally used in ink-jet ink compositions, printing (oil-based) ink compositions, or liquid developers for electrophotography (electrophotography) are used without particular limitation. The

  For example, as a pigment used as a color material, regardless of inorganic pigments or organic pigments, those generally used in the technical field of printing can be used. Specifically, for example, carbon black, cadmium red, molybdenum red, chrome yellow, cadmium yellow, titanium yellow, chromium oxide, viridian, cobalt green, ultramarine blue, Prussian blue, cobalt blue, azo pigment, phthalocyanine pigment And quinacridone pigments, isoindolinone pigments, dioxazine pigments, selenium pigments, perylene pigments, perinone pigments, thioindigo pigments, quinophthalone pigments, metal complex pigments, and the like.

  In addition, for example, dyes used as coloring materials include azo dyes, metal complex dyes, naphthol dyes, anthraquinone dyes, indigo dyes, carbonium dyes, quinoneimine dyes, xanthene dyes, aniline dyes, quinoline dyes, nitro dyes, nitroso dyes, and benzoquinones. Preferred examples include oil-soluble dyes such as dyes, naphthoquinone dyes, phthalocyanine dyes, and metal phthalocyanine dyes.

Examples of the dispersion resin include rosins, rosin-modified phenolic resins, alkyd resins, (meth) acrylic polymers, polyurethane, polyester, polyamide, polyethylene, polybutadiene, polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl alcohol, acetal-modified products of polycarbonate, polycarbonate Etc.
Among these, from the viewpoint of ease of particle formation, the weight average molecular weight is in the range of 2,000 to 1,000,000 and the polydispersity (weight average molecular weight / number average molecular weight) is 1.0 to 5 Polymers in the range of 0.0 are preferred. Furthermore, from the viewpoint of ease of fixing, a polymer having any one of a softening point, a glass transition point, and a melting point within a range of 40 ° C. to 120 ° C. is preferable.

Next, an embodiment of the ink jet recording apparatus of the present invention using the image fixing apparatus of the present invention will be described.
The image fixing device of the present invention is used as an image fixing unit in various image recording devices that record an image using ink containing at least color material particles containing a color material and a resin, or liquid toner or dry toner. Thus, an image having a desired glossiness can be formed. For example, the present invention can be applied to various types of ink jet recording apparatuses using the above-described ink and electrophotographic recording apparatuses using liquid toner or dry toner. In the following, as a suitable example, an electrostatic ink jet recording apparatus capable of recording high-quality images will be described.

  FIG. 4 is a schematic diagram showing a schematic configuration of an electrostatic ink jet recording apparatus 100 which is an embodiment of the ink jet recording apparatus of the present invention. The ink jet recording apparatus 100 shown in FIG. 1 controls electrostatic discharge of ink containing charged color material particles (charged fine particles) by electrostatic force, and performs four-color printing on a recording medium P to record a full color image. Recording medium holding means 102 for recording medium P, recording medium conveying means 104, recording means 106, image fixing device 10 of the present invention, solvent recovery means 108, and housing 110. I have.

  The recording medium holding unit 102 of the recording medium P includes a paper feed tray 114 that holds the recording medium P before recording, a pickup roll 116, and a paper discharge tray 118 that holds the recording medium P after recording.

  The paper feed tray 114 holds a plurality of recording media P to be used for recording, and is inserted into the housing 110 from the lower left side of the housing 110 in FIG. The pickup roll 116 is disposed in the vicinity of the front end portion (right end portion in the drawing) of the mounting portion of the paper feed tray 114. At the time of recording an image, the recording medium P is picked up one by one from the paper feed tray 114 by the pickup roll 116 and supplied to the recording medium conveying means 104 of the recording medium P. In the vicinity of the pickup roll 116, in order to easily separate the recording medium P stocked in layers, a neutralizing brush, a neutralizing roll, an air blowing blower, etc. for neutralizing the recording medium P are provided. Is preferred.

  The paper discharge tray 118 holds the recording medium P on which an image is formed, and is provided at the end of the transport path of the recording medium P inside the housing 110, and its front end (the front end in the transport direction of the recording medium P). Side) is located outside the housing 110. The recording medium P after recording is conveyed by the recording medium conveying means 104, discharged to the discharge tray 118, and sequentially stacked on the discharge tray 118 and stocked.

  The recording medium conveying unit 104 conveys the recording medium P along a predetermined path from the paper feed tray 114 to the paper discharge tray 118, and includes a conveyance roll pair 120, a conveyance belt 122, and belt rolls 124a and 124b. , 124c, a charger 126 and a static eliminator 128 for the recording medium P, a separation claw 130, and a guide 132.

  The conveyance roll pair 120 is provided at a position between the pickup roll 116 and the conveyance belt 122. The recording medium P taken out from the paper feed tray 114 by the pickup roll 116 is nipped and conveyed by the conveyance roll pair 120 and supplied to a predetermined position on the conveyance belt 122. It is preferable to use a soft nip roll as the pair of transport rolls 120, so that even when high speed paper feeding is performed, paper feeding can be performed with accurate positional accuracy.

  The charger 126 for the recording medium P includes a scorotron charger 134 and a negative high-voltage power source 136. The scorotron charger 134 is disposed on the conveyance path of the recording medium P between the conveyance roll pair 120 and the recording unit 106 so as to face the surface of the conveyance belt 122. The scorotron charger 134 is connected to the negative terminal of the negative high-voltage power supply 136, and the positive terminal of the negative high-voltage power supply 136 is grounded.

  The surface of the recording medium P is uniformly charged to a predetermined negative high potential by a scorotron charger 134 connected to a negative high-voltage power source 136, and a constant DC bias voltage (for example, about −1.5 kV required for recording). ) Is applied. Accordingly, the recording medium P is electrostatically adsorbed on the insulating surface of the transport belt 122.

  The conveyor belt 122 is a loop-like endless belt, and is stretched in a triangular shape by three belt rolls 124a, 124b, and 124c. At least one of the belt rolls 124a, 124b, and 124c is connected to a drive source (not shown), and is driven to rotate at a predetermined speed during recording. Accordingly, the conveyance belt 122 circulates in the direction of the arrow in the figure (counterclockwise in the figure), and conveys the recording medium P that is electrostatically attracted to the conveyance belt 122 at a predetermined speed.

  The conveyance belt 122 is such that the surface (front surface) on which the recording medium P is electrostatically attracted is insulative, and the surface (back surface) in contact with the belt rolls 124a, 124b, and 124c is conductive. One of the belt rolls 124a, 124b, and 124c (in the illustrated example, the belt roll 124b) is grounded, so that the conveyance belt 122 is used as a counter electrode of the inkjet head at a position facing the recording unit 106. Also works.

  The static eliminator 128 of the recording medium P includes a corotron static eliminator 138, an AC voltage source 140, and a high voltage power source 142. The corotron static eliminator 138 is disposed on the downstream side of the recording unit 106 in the recording medium P conveyance direction so as to face the surface of the conveyance belt 122. The corotron static eliminator 138 is connected to the high-voltage power supply 142 via the AC voltage source 140, and the other end of the high-voltage power supply 142 is grounded.

  The recording medium P after recording is neutralized by the corotron charger 52 and then separated from the conveying belt 122 by the separation claw 130 disposed downstream thereof. The recording medium P separated from the conveyance belt 122 is supplied to the image fixing device 10 along the guide 132, and is discharged to the paper discharge tray 118 through the fixing process in the image fixing device 10.

  The recording means 106 records the image according to the image data on the recording medium P by using the ink containing the charged color material particles and controlling the ejection of the ink by the electrostatic force according to the image data. Ink jet head 144, head driver 146, ink circulation mechanism 148, platen 150, and recording medium P position detector 152 are provided.

  In the inkjet head 144, the ink discharge portion is held on the surface of the conveyor belt 122 (held on the surface of the conveyor belt 122) at a position where the recording medium P is conveyed in a stable plane state on the conveyance path of the recording medium P by the conveyor belt 122. The recording medium P is disposed at a predetermined distance from the surface of the recording medium P to be recorded. In the illustrated example, the inkjet head 144 is disposed to face the conveyance belt 122 between the belt rolls 124b and 124c.

  Further, the platen 150 is disposed at a position facing the inkjet head 144 with the conveyance belt 122 interposed therebetween. That is, in the illustrated example, it is disposed between the belt rolls 124b and 124c. The platen 36 is also preferably arranged so as to protrude toward the inkjet head 144 side from a line connecting the outer circumferences of the belt rolls 124b and 124c. By arranging in this way, tension can be applied to the conveyor belt 122 and fluttering of the conveyor belt 122 can be suppressed.

  The inkjet head 144 is a line head capable of recording an image for one line at a time, and cyan (C), magenta (M), yellow (Y), and black (B) for recording a full color image. Four color discharge heads are provided. Since the discharge heads for the respective colors basically have the same configuration, the discharge head 160 for one color will be described below.

  FIG. 5 is a schematic diagram illustrating a specific structure of the discharge head 160 in the electrostatic inkjet head 144. FIG. 5A is a schematic cross-sectional view illustrating a part of the discharge head 160. FIG. FIG. 5B is a schematic cross-sectional view taken along line VV in FIG. The ejection head 160 is a multi-channel head having a plurality of nozzles two-dimensionally, but here, only two ejection sections are shown in order to clearly show the configuration.

  The ejection head 160 includes a head substrate 162, an ink guide 164, a nozzle substrate 166, an ejection electrode 168 that constitutes an ejection electrode, and a floating conductive plate 176. The ejection head 160 is disposed so that the tip of the ink guide 164 that is the ejection (flying) point of the ink droplet R faces the conveyance belt 122 that supports the recording medium P that is a counter electrode.

  The head substrate 162 and the nozzle substrate 166 are flat substrates common to all the nozzles of the ejection head 160, and are made of an insulating material. The head substrate 162 and the nozzle substrate 166 are arranged at a predetermined interval, and an ink flow path 178 is formed therebetween. The ink Q in the ink flow path 178 includes color material particles charged to the same polarity as the voltage applied to the ejection electrode 168, and at the time of recording, the ink circulation mechanism 148 (see FIG. 4) causes a predetermined direction, FIG. In the example shown in A), the ink is circulated in the ink flow path 178 from the right side to the left side (in the direction of arrow a in the drawing) at a predetermined speed (for example, an ink flow of 200 mm / s). Hereinafter, a case where the color material particles in the ink are positively charged will be described as an example.

  In the nozzle substrate 166, nozzles 174 serving as ejection openings for the ink Q are perforated, and a plurality of nozzles 174 are two-dimensionally arranged at a predetermined interval. In addition, an ink guide 164 for determining the discharge (flying) point of the ink Q is disposed at the center of the nozzle 174.

  The ink guide 164 is made of an insulating resin flat plate having a predetermined thickness with a projecting tip portion 164 a, and is disposed on the head substrate 162 at a position corresponding to each nozzle 174. The ink guide 164 has a base portion 164b common to a plurality of ink guides 164 arranged in the same row (left and right direction in FIG. 5A, vertical direction in FIG. 5B), and this base portion 164b. Is fixed on the head substrate 162 with the floating conductive plate 176 interposed therebetween.

  The leading end portion 164a of the ink guide 164 is disposed so as to protrude from the outermost surface of the ejection head 160 on the recording medium P (conveying belt 122) side. The shape and configuration of the tip portion 164a stabilizes the discharge point of the ink Q (ink droplet R), and the ink Q is sufficiently supplied at the tip portion 164a to concentrate the colorant particles in the ink Q to a preferable state. It is set so that it can be made. For example, in order to substantially increase the dielectric constant of the tip portion 84a, the tip portion 164a having a shape that is gradually narrowed in the ejection direction, the notch serving as an ink guide groove formed in the vertical direction in the figure, or the like. A material obtained by evaporating metal on the tip portion 164a is suitable.

  On the surface of the nozzle substrate 166 on the recording medium P side (the upper surface in the drawing), ejection electrodes 168 are arranged so as to surround each nozzle 174. Further, on the recording medium P side of the nozzle substrate 166, an insulating layer 170a covering the upper side (upper surface) of the discharge electrode 168, and a sheet-like guard electrode 172 disposed above the discharge electrode 168 via the insulating layer 170a, And an insulating layer 170b covering the upper surface of the guard electrode 172.

  The discharge electrode 168 is formed in a ring shape, that is, a circular electrode for each discharge portion on the upper side of the nozzle substrate 166 in the drawing, that is, on the surface on the recording medium P side so as to surround the periphery of the nozzle 174 opened in the nozzle substrate 166. Is arranged as. The electrode shape of the ejection electrode 168 is not limited to a circular electrode, and may be a substantially circular shape, a divided circular electrode, a parallel electrode, or a substantially parallel electrode.

  The ejection electrode 168 is controlled by the head driver 146, and a predetermined pulse voltage is applied according to the image data. As described above, the recording medium P charged to a voltage opposite in polarity to the charged color material particles in the ink is held by the conveyor belt 122 and conveyed at a constant speed at a position facing the ink guide 164. Is done. The recording medium P is charged with a negative high voltage (for example, −1500 V), and a predetermined electric field is formed between the ejection electrode 168 and the ink Q so as not to be ejected.

  When the discharge electrode 168 is in the discharge off state (discharge standby state), the pulse voltage is set to 0 V or a low voltage. In this state, the electric field strength of the ejection portion is the electric field strength due to the bias voltage (or the voltage obtained by superimposing the off-state pulse voltage on the bias voltage), which is lower than the strength necessary for ejecting the ink Q. Since it is set, the ink Q is not ejected. However, due to the low electric field in the discharge standby state, the color material particles in the ink are concentrated in the tip portion 176 a of the ink guide 164 inside the nozzle 174.

  When the ejection electrode 168 is in the ejection-on state, a pulse voltage is applied, and a high-voltage pulse voltage (for example, 400 to 600 V) is superimposed on the bias voltage. The ink Q is sufficiently strong and the ink Q concentrated on the tip portion 176a of the ink guide 164 flies as an ink droplet R. Since the size of the ink droplet R is extremely small, high-resolution and high-quality image recording can be performed.

  In this way, on / off of the ejection electrodes 168 of the ejection units arranged over the entire width of the recording medium P is controlled according to the image data, and the recording medium P conveyed at a predetermined speed has a predetermined value. By ejecting ink at the timing, a two-dimensional image is recorded on the recording medium P.

  The guard electrode 172 is disposed between the ejection electrodes 168 of the adjacent ejection units, and is for suppressing electric field interference generated between the ink guides 164 of the adjacent ejection units. The guard electrode 172 is a sheet-like electrode such as a metal plate that is common to all the discharge portions of the discharge head 160, and corresponds to the discharge electrode 168 formed around each nozzle 174 that is two-dimensionally arranged. Is perforated. By providing the guard electrode 172, even when the nozzles 174 are arranged at a high density, the influence of the electric field of the adjacent nozzles 174 can be minimized, and the dot size and the dot drawing position can always be kept stable.

  A floating conductive plate 176 is arranged on the surface of the head substrate 162 on the ink flow path 178 side. The floating conductive plate 176 is electrically insulated (high impedance state), generates an induced voltage in accordance with a voltage value applied to the ejection unit during image recording, and generates an ink flow path. In the ink Q in 178, the color material particles are migrated to the nozzle substrate 166 side. In addition, a coating film (not shown) that is electrically insulating is formed on the surface of the floating conductive plate 176 to prevent destabilization of the physical properties and components of the ink due to charge injection into the ink and the like. Has been. As this insulating coating film, one having corrosion resistance to ink is used.

  By providing the floating conductive plate 176, the color material particles in the ink Q in the ink flow path 178 migrate to the nozzle substrate 166 side, and the concentration of the color material particles in the ink Q that passes through the nozzle 174 of the nozzle substrate 166. Can be increased to a predetermined concentration, and the concentration of the colorant particles in the ink Q to be ejected as the ink droplet R can be stabilized at the predetermined concentration by being concentrated on the tip portion 84a of the ink guide 164.

  In the illustrated example, the discharge electrode has a single-layer electrode structure, but in addition to this, for example, a first discharge electrode connected in the column direction and a second discharge electrode connected in the row direction are provided. A two-layer electrode structure may be used, and the first discharge electrode and the second discharge electrode may be arranged in a matrix to perform matrix driving. According to such a matrix driving method, both high integration of ejection electrodes and simplification of driver wiring can be realized simultaneously.

  The ink circulation mechanism 148 includes an ink tank 154, a pump (not shown), and an ink supply path and a recovery path 156. The ink tank 154 is disposed on the bottom surface inside the housing 110 and is connected to the inkjet head 144 via an ink supply path and a recovery path 156.

  In the ink tank 154, four colors of ink including color material particles of each color and a dispersion solvent for dispersing the color material particles are held. The ink of each color in the ink tank 154 is supplied to the discharge head of each color of the inkjet head 144 via the ink supply path 156 by the pump. Further, the extra ink of each color that was not used for image recording is collected by the pump into the ink tank 154 of each color via the ink collection path 156.

  In the ink jet recording apparatus 100, the ink Q having the above-described configuration suitable for fixing in the image fixing device 10 and further having the following configuration is preferably used as the ink Q.

That is, as the ink Q, a material in which charged color material particles (colored charged particles) having a particle diameter of about 0.1 to 5 μm are dispersed in a solvent (carrier liquid) is used. In the ink, dispersed resin particles for improving the fixability of an image after printing may be appropriately contained together with the color material particles. The carrier liquid is a dielectric liquid (nonaqueous solvent) having a high electrical resistivity (10 ⁹ Ω · cm or more, preferably 10 ¹⁰ Ω · cm or more, and preferably 10 ¹⁶ Ω · cm or less). Is preferred. When a carrier liquid having a high electrical resistivity is used, the carrier liquid itself is less likely to receive charge injection due to the voltage applied by the discharge electrode, and the concentration of charged particles (charged fine particle component) can be increased. Can be concentrated. Further, the carrier liquid having a high electric resistivity can contribute to prevention of electrical conduction between adjacent recording electrodes. Further, when ink made of such an electric low-efficiency liquid is used, ink can be ejected satisfactorily even under a low electric field.

  The relative dielectric constant of the dielectric liquid used as the carrier liquid is preferably 5 or less, more preferably 4 or less, and still more preferably 3.5 or less. The lower limit value of the relative dielectric constant is desirably about 1.9. By setting the relative dielectric constant in such a range, an electric field is effectively applied to charged particles in the dielectric liquid, and migration easily occurs. Accordingly, the polarization of the solvent can be suppressed, the electric field can be prevented from being relaxed, and dots with good image density with less blur can be formed.

  The dielectric liquid is preferably a linear or branched aliphatic hydrocarbon, alicyclic hydrocarbon, or aromatic hydrocarbon, and halogen-substituted products of these hydrocarbons. For example, hexane, heptane, octane, isooctane, decane, isodecane, decalin, nonane, dodecane, isododecane, cyclohexane, cyclooctane, cyclodecane, benzene, toluene, xylene, mesitylene, Isopar C, Isopar E, Isopar G, Isopar H, Isopar L, Isopar M (isopar: trade name of Exxon), Shellsol 70, Shellsol 71 (shellsol: trade name of Shell Oil), Amsco OMS, Amsco 460 solvent (trade name of Amsco: Spirits), Silicone oil (for example, KF-96L manufactured by Shin-Etsu Silicone) or the like can be used alone or in combination.

  The content of the colorant particles dispersed in the ink (the total content of the colored particles and / or the resin particles) is a viewpoint of printing image density, formation of a uniform dispersion, and suppression of clogging of the ink at the ejection head. Therefore, it is preferably contained in the range of 0.5 to 30% by weight, more preferably 1.5 to 25% by weight, still more preferably 3 to 20% by weight based on the whole ink. Is desirable.

  The average particle diameter of the ink particles such as the colorant particles and / or resin particles dispersed in the dielectric solvent is preferably 0.1 μm to 5 μm, more preferably 0.2 μm to 1.5 μm, and further Preferably it is the range of 0.4 micrometer-1.0 micrometer. This particle size is determined by CAPA-500 (trade name, manufactured by Horiba, Ltd.).

The ink particles (dispersed resin particles and / or colored particles or colorant particles) in the ink are preferably positively charged or negatively charged detecting particles.
In order to impart electroanalytical properties to these ink particles, it can be achieved by appropriately using the technique of a developer for wet electrophotography. Specifically, “Recent development and practical use of electrophotographic development systems and toner materials”, pages 139-148, “Basics and Applications of Electrophotographic Technology” edited by Electrophotographic Society, pages 497-505 (published in Corona, 1988) Yuji Harasaki, “Electrophotography” 16 (No. 2), p. 44 (1977), and the like.

Further, the viscosity of the ink composition is preferably in the range of 0.5 to 5 mPa · sec, more preferably in the range of 0.6 to 3.0 mPa · sec, and still more preferably in the range of 0.7 to 2.0 mPa · sec. is there. The colored particles have a charge, and various charge control agents used in electrophotographic liquid developers can be used as necessary. The charge amount is desirably in the range of 5 to 200 μC / g, more preferably. It is 10 to 150 μC / g, more preferably 15 to 100 μC / g. In addition, the electrical resistance of the dielectric solvent may change due to the addition of the charge control agent, and the distribution ratio P defined below is 50% or more, more preferably 60% or more, and even more preferably 70% or more.
P = 100 × (σ1−σ2) / σ1
Here, σ1 is the electrical conductivity of the ink composition, and σ2 is the electrical conductivity of the supernatant obtained by subjecting the ink composition to a centrifuge. The electrical conductivity was measured using an LCR meter (AG-4311 manufactured by Ando Electric Co., Ltd.) and an electrode for liquid (LP-05 type manufactured by Kawaguchi Electric Manufacturing Co., Ltd.) under the conditions of an applied voltage of 5 V and a frequency of 1 kHz. This is the measured value. Centrifugation was performed for 30 minutes using a small high-speed cooling centrifuge (Tomy Seiko Co., Ltd. SRX-201) under conditions of a rotational speed of 14500 rpm and a temperature of 23 ° C.
By using the ink composition as described above, migration of charged particles is likely to occur and concentration is facilitated.

  On the other hand, the electrical conductivity σ1 of the ink composition is preferably in the range of 100 to 3000 pS / cm, more preferably in the range of 150 to 2500 pS / cm, and still more preferably in the range of 200 to 2000 pS / cm. By setting the electric conductivity in the above range, the voltage applied to the ejection electrode does not become extremely high, and there is no fear of causing electrical continuity between adjacent recording electrodes. The surface tension of the ink composition is preferably in the range of 15 to 50 mN / m, more preferably 15.5 to 45 mN / m, and still more preferably 16 to 40 mN / m. By setting the surface tension within this range, the voltage applied to the ejection electrode does not become extremely high, and the ink does not leak around the head and become contaminated.

  The position detector 152 of the recording medium P is a conventionally known position detecting means such as a photo sensor, and the recording medium P is located at a position between the charger 126 and the inkjet head 144 on the conveyance path of the recording medium P. It is arrange | positioned in the position facing the surface of the conveyance belt 122 conveyed. The position information of the recording medium P detected by the position detector 152 is supplied to the head driver 146.

  The head driver 146 is a driver for the inkjet head 144 and is connected to the inkjet head 144 via a drive signal cable. In the illustrated example, the head driver 146 is attached to the right side of the housing 110 in the drawing. Image data is input to the head driver 146 from an external device, and position information of the recording medium P is input from the position detector 152. Then, the head driver 146 controls the ejection timing of the ejection heads of the respective colors of the inkjet head 144 according to the position information of the recording medium P, and ejects the inks of the respective colors from the ejection heads of the respective colors according to the image data. On P, a full color image corresponding to the image data is recorded.

  The image fixing device 10 is an image fixing device according to the present invention, and the configuration thereof is as described in detail with reference to FIGS. That is, depending on the type of the recording medium P, one of the fixing rolls 12A and 12B is disposed on the image recording surface side of the recording medium P, and the recording medium P is nipped and conveyed while being heated and pressurized. The image on the recording medium P is fixed.

  Here, in the inkjet recording apparatus 100, the moving side plate rotation motor 66 and the drive motors 60A and 60B of the image fixing apparatus 10 are automatically controlled by a control unit (not shown) in response to an instruction input from the operator. That is, prior to the start of recording, when the operator inputs that the recording medium P is art paper, the control means operates the moving side plate rotation motor 66 so that the fixing roll 12A is placed on the recording medium P. The moving side plates 14L and 14R are rotated so as to be on the recording surface side. Then, the control unit operates the drive motor 60A to rotate the fixing roll 12A.

  On the other hand, when the operator inputs that the recording medium P is high-quality paper, the control means operates the moving side plate rotating motor 66 so that the fixing roll 12B is on the recording surface side of the recording medium P. The moving side plates 14L and 14R are rotated. Then, the control unit operates the drive motor 60B to rotate the fixing roll 12B.

  The solvent recovery means 108 recovers the dispersion solvent that evaporates from the ink ejected from the inkjet head 144 onto the recording medium P, the dispersion solvent that evaporates from the ink when fixing the image, and the like. 182. The activated carbon filter 180 is attached to the upper back surface of the housing 110 in the drawing, and the exhaust fan 182 is attached to the activated carbon filter 180.

  This is caused by the natural evaporation of the ink solvent from the ink ejected from the inkjet head 114, the natural evaporation of the ink solvent that forms an unfixed image on the recording medium P, and the evaporation of the ink solvent that occurs during fixing in the image fixing apparatus 10. The air containing the dispersed solvent component inside the casing 110 is collected by the exhaust fan 182 and passes through the activated carbon filter 180, so that the solvent component is adsorbed and removed by the activated carbon filter 180, and the removed air is removed. It is discharged outside the housing 110.

Hereinafter, the operation of the inkjet recording apparatus 100 will be described.
Prior to the start of recording, first, the operator inputs the type of the recording medium P to a control means (not shown), and the arrangement of the fixing rolls 12A and 12B of the image fixing apparatus 10 is set by the control means.

  At the start of recording, the recording medium P stored in the paper feed tray 114 is taken out one by one by the pickup roll 116, nipped and conveyed by the conveyance roll pair 120, and supplied to a predetermined position on the conveyance belt 122. The recording medium P supplied on the conveyance belt 122 is charged to a negative high potential by the charger 126 and electrostatically attracted to the surface of the conveyance belt 122.

  The recording medium P electrostatically attracted to the surface of the transport belt 122 is moved at a predetermined constant speed as the transport belt 122 moves, and an image corresponding to the image data is recorded on the surface of the recording medium P by the inkjet head 144.

  The recording medium P after image recording is neutralized by the static eliminator 128, separated from the conveying belt 122 by the separation claw 130, and supplied to the image fixing device 10 along the guide 132. In the image fixing device 10, the fixing roll 12 </ b> A or 12 </ b> B corresponding to the type of the recording medium P holds the recording medium P while being in contact with the image recording surface, and fixes the image by heating and pressing.

  The recording medium P on which the image is fixed is discharged from the image fixing device 10 and stocked in the paper discharge tray 118. The image on the recording medium P obtained in this way is an image that exhibits gloss corresponding to the type of the recording medium P and has the same texture as an image obtained by offset printing.

  Next, another embodiment of the image fixing device of the present invention will be described. In the above-described example, an image of the recording medium P is provided by having a fixing unit including two fixing rolls, that is, the fixing rolls 12A and 12B, and reversing the positions of the fixing rolls 12A and 12B with respect to the conveyance surface of the recording medium P. The fixing roll in contact with the recording surface is set to either the fixing roll 12A or the fixing roll 12B. However, in this embodiment, the fixing unit includes three fixing rolls, and the fixing unit is moved up and down with respect to the conveyance surface. By doing so, the fixing roll on the image recording surface side is set.

  6A and 6B are diagrams conceptually showing the configuration of a fixing unit (fixing roll portion) 82 of an image fixing device 80 which is another embodiment of the image fixing device of the present invention. The image fixing apparatus 80 includes a fixing roll 12C as a fixing unit 82 in addition to the fixing rolls 12A and 12B in the image fixing apparatus 10 of FIGS. The fixing rolls 12A, 12B, and 12C have their respective rotation axes in a direction perpendicular to the conveyance direction of the recording medium P (in the drawing, a direction perpendicular to the paper surface) and in a direction perpendicular to the conveyance surface of the recording medium P (in the drawing, (Up and down direction) are arranged adjacent to each other in order, and both end portions of each fixing roll are pivotally supported by a pair of moving side plates 14L and 14R. In addition, the image fixing device 80 includes a parallel movement mechanism (not shown) that translates the moving side plates 14L and 14R as a fixing unit moving unit that translates the fixing unit 82 in a direction orthogonal to the conveyance surface of the recording medium P. A pair of fixed side plates 16L (16R) is provided, and one or more of the fixing rolls 12A, 12B, and 12C are provided with fixing roll driving means similar to the above-described example.

The fixing rolls 12A and 12B are the same as the fixing rolls 12A and 12B in the image fixing apparatus 10, and are heat rolls having a lamp heater inside.
The fixing roll 12C is a heat roll having basically the same configuration as the fixing rolls 12A and 12B. However, since the fixing roll 12C does not contact the image recording surface of the recording medium P, its layer configuration is moderate. What is necessary is just to set suitably so that it may have hardness, elasticity, etc. For example, it may have the same layer structure as the fixing roll 12A or 12B, or may be different from both.

  In the fixing unit 82, between the fixing roll 12A and the fixing roll 12B and between the fixing roll 12B and the fixing roll 12C respectively function as a fixing unit. That is, the recording medium P conveyed with the image recording surface facing upward is sandwiched and conveyed between the fixing rolls 12A and 12B or between the fixing rolls 12B and 12C. The unfixed image is fixed.

  The fixing roll driving means for rotationally driving the fixing rolls 12A, 12B, and 12C is constituted by a driving motor for each fixing roll and a known transmission means for transmitting the power of the driving motor to the fixing roll, as in the example of FIG. Is done. Which of the fixing rolls 12A, 12B, and 12C is driven is determined by the method of driving the fixing roll on the side opposite to the recording surface or the one having the higher friction coefficient with the recording medium P, as in the above example. The fixing roller can be selected from a method for driving the fixing roller and a method for driving both of the two fixing rollers constituting the fixing unit.

  In particular, in the case of the present embodiment, only the fixing roll 12B rotates when fixing is performed between the fixing roll 12A and the fixing roll 12B and when fixing is performed between the fixing roll 12B and the fixing roll 12C. Therefore, for example, the fixing roll 12A and the fixing roll 12C may be provided with driving means for rotating in one direction so that the fixing roll 12B always rotates. In this case, since the forward / reverse rotation switching control is not necessary, the configuration of the driving means can be simplified. Alternatively, the driving means may be provided only on the fixing roll 12B, the rotation direction of the fixing roll 12B may be switched between forward and reverse, and the fixing roll 12A and the fixing roll 12C may be idle rolls. In this case, since only one drive means such as a drive motor is required, the apparatus can be reduced in size and weight.

  The moving unit of the fixing unit 82 is moved in accordance with an instruction from the operator or the like between the two fixing portions of the fixing unit 82, that is, between the fixing roll 12A and the fixing roll 12B and between the fixing roll 12B and the fixing roll 12C. The fixing unit 82 is translated in a direction (vertical direction in the figure) perpendicular to the conveyance surface of the recording medium P so that one of the two is positioned on the conveyance path of the recording medium P. As the moving means of the fixing unit 82, for example, a combination of a drive source such as a motor, an air cylinder, or a hydraulic cylinder and a slide mechanism such as a linear guide is used.

  The recording medium P is conveyed from right to left in the figure with the image recording surface facing up. When the fixing portion between the fixing rolls 12A and 12B of the fixing unit 82 is arranged on the transport path by the moving means of the fixing unit 82, the image on the recording medium P is fixed in contact with the fixing roll 12A. Is done. Therefore, the image after fixing has a surface roughness corresponding to the characteristics of the surface layer of the fixing roll 12A. On the other hand, when the fixing unit between the fixing rolls 12B and 12C is arranged on the conveyance path of the recording medium P by the moving unit of the fixing unit 82, the image recording surface on the recording medium P is the same as the fixing roll 12B. Since the image is fixed by contact, the image after fixing has a surface roughness corresponding to the surface layer characteristics of the fixing roll 12B.

  In the case of using art paper as the recording medium P in fixing an image recorded using ink containing color material particles containing a color material and a resin, as shown in FIG. Arranged on the image recording surface side. Since the fixing roll 12A has a surface layer with high hardness, low elasticity, low surface roughness, and good ink releasability, the surface of the image heated and fixed by the fixing rolls 12A and 12B is used. The roughness is reduced and an image with high gloss is obtained. Thereby, an image having an image quality (texture) equivalent to that of an image recorded on art paper by offset printing can be formed.

  Further, when using high-quality paper as the recording medium P, as shown in FIG. 6B, the fixing roll 12B is disposed on the image recording surface side. Since the surface of the fixing roll 12B has a low hardness, a high elasticity, and a large surface roughness, the surface roughness of the image heated and fixed by the fixing rolls 12B and 12C remains large. An image with low gloss can be obtained. As a result, an image having the same image quality (texture) as that of an image recorded on high-quality paper by offset printing can be formed.

  In the example of FIG. 6, the fixing rolls 12 </ b> A, 12 </ b> B, and 12 </ b> C are arranged on a straight line perpendicular to the conveyance surface of the recording medium P. By arranging in this way, the conveyance path of the recording medium P in the fixing unit is linear, the load on the recording medium P is minimized, and the expansion and breakage of the recording medium P during fixing, image rubbing, and the like are suppressed. It is preferable in that it can be performed. However, the present invention is not limited to this, and the shafts of the two fixing rolls constituting each fixing unit of the fixing unit 82 within a range that does not cause defects in the recording medium P and the image on the recording medium P during fixing. The fixing rolls may be arranged so that a line connecting the lines forms an obtuse or acute angle with respect to the conveyance surface of the recording medium P before and after the fixing unit. Also in this case, the fixing units are sequentially arranged in the direction perpendicular to the conveyance surface of the recording medium P (shifted in the conveyance direction), so that the moving unit of the fixing unit 82 is the same as the above. 82 may be translated in a direction perpendicular to the conveyance surface of the recording medium P.

  In addition, the fixing unit 82 includes four or more fixing rolls to form three or more fixing units, and the fixing unit 82 is moved in parallel by a moving unit of the fixing unit 82 so that three or more types of recording media are provided. Glossiness may be imparted corresponding to P, or three or more types of glossiness may be selected according to the image.

  In the image fixing device 80, the fixing unit 82 is moved in parallel so that either the fixing roll 12A or the fixing roll 12B of the three fixing rolls 12A, 12B, and 12C is brought into contact with the image recording surface. However, the fixing unit 82 is further provided with a means for rotating and fixing the fixing unit 82. By rotating the fixing unit 82 180 degrees with respect to the conveyance surface of the recording medium P, the fixing roll 12C is also provided. You may make it contact an image recording surface. In this case, the fixing roll 12C has a layer configuration different from that of the fixing rolls 12A and 12B. Of course, by combining the above methods, the fixing unit 82 may be provided with four or more fixing rolls, and may further be provided with a rotational movement means.

  As in the previous example, in addition to using a plurality of fixing rolls having different surface layer configurations, the fixing conditions such as the heating temperature, the pressing force (nip pressure), and the fixing speed of the fixing roll can be changed to further increase the abundance. It is also preferable to be compatible with various types of recording media.

  The image fixing apparatus according to the present invention has been described in detail above. However, the present invention is not limited to the various embodiments described above, and various improvements and modifications may be made without departing from the gist of the present invention. Of course.

1 is a diagram illustrating an image fixing device according to an embodiment of the present invention, and is a cross-sectional view in the axial direction of a fixing roll. 1A is a radial cross-sectional view of the fixing rolls 12A and 12B in FIG. 1 (cross-sectional view taken along the line II-II in FIG. 1), and FIG. 1B is a state in which the positions of the fixing rolls 12A and 12B are from the state of FIG. It is sectional drawing of the reversed state. FIG. 3 is a view for explaining a driving mechanism for fixing rolls 12A and 12B and a rotating mechanism for a moving side plate 14 in FIG. 1, corresponding to a cross-sectional view taken along line III-III in FIG. 1 is a schematic diagram illustrating an embodiment of an inkjet recording apparatus of the present invention. (A) is a schematic cross-sectional view showing a part of the ejection head 160, and (B) is a schematic cross-sectional view taken along line VV of (A). (A) and (B) are diagrams conceptually showing the structure of a fixing unit of another embodiment of the image fixing apparatus of the present invention.

Explanation of symbols

10, 80 Image fixing device 12A, 12B, 12C Fixing roll 14L, 14R Moving side plate 16L, 16R Fixed side plate 18L, 18R Fixing roll holding mechanism 20A, 20B Fixing roll driving mechanism 22 Rotating mechanism 24 Guide mechanism 26 Moving side plate positioning mechanism 30A, 30B Core material 32A, 32B Elastic layer 34 Release layer 36A, 36B Lid 38A, 38B Rotating shaft 40 Lamp heater 42 Heater holder 44 Buffer member 45, 46 Shaft 48L, 48R Bearing 50 Bearing stopper 52 Nip pressure biasing tool 54 Elasticity Material 56A, 56B Sprocket 58 Chain 60A, 60B Drive motor 62A, 62B Sprocket 64L, 64R Ring gear 66 Moving side plate rotation motor 68A, 68B, 64C Gear 70 Paper feed guide 72 Guide fulcrum 74 Guide Pin 76 Limiter 78 Contact material 82 Fixing unit 100 Inkjet recording apparatus 102 Recording medium holding means 104 Recording medium conveying means 106 Recording means 108 Solvent collecting means 110 Housing 114 Paper feed tray 116 Pickup roll 118 Paper discharge tray 120 Conveying roll pair 122 Conveyance Belt 124a, 124b, 124c Belt roll 126 Charger 128 Charger 130 Separation claw 132 Guide 134 Scorotron charger 136 Negative high voltage power supply 138 Corotron discharger 140 AC voltage source 142 High voltage power supply 144 Inkjet head 146 Head driver 148 Ink circulation mechanism 150 Platen 152 Position detector 154 Ink tank 156 Ink supply path and recovery path 160 Discharge head 162 Head substrate 164 Ink guide 164a Tip 1 64b Base 166 Nozzle substrate 168 Discharge electrode 170a, 170b Insulating layer 172 Guard electrode 174 Nozzle 176 Floating conductive plate 178 Ink channel 180 Activated carbon filter 182 Exhaust fan

Claims (8)

In an image fixing device for fixing an image on a recording medium formed using an ink containing at least a color material particle containing a color material and a resin,
There are a plurality of fixing rolls arranged adjacent to each other, and one of the fixing rolls is a heating roll. The recording medium is sandwiched and conveyed between the plurality of fixing rolls to thermally fix the image on the recording medium. A fixing unit to
Fixing roll driving means for driving at least one of the fixing rolls;
Fixing unit moving means for moving the fixing unit so that a desired fixing roll is positioned on the image recording surface side of the recording medium;
An image fixing apparatus comprising:   The image fixing apparatus according to claim 1, wherein the fixing unit moving unit rotates and / or translates the fixing unit. The fixing unit has a support member that pivotally supports the plurality of fixing rolls,
3. The fixing unit moving unit is configured to rotate and / or translate the support member so that a desired fixing roll is positioned on the image recording surface side of the recording medium. The image fixing device described.   4. The image fixing apparatus according to claim 1, wherein the plurality of fixing rolls are different in at least one of hardness, surface roughness, and material of a surface layer. 5.   5. The image fixing device according to claim 1, further comprising a clamping force adjusting unit that adjusts a clamping force of the recording medium by the fixing roll. 6.   6. The image fixing apparatus according to claim 1, further comprising a temperature adjusting unit that adjusts a roll surface temperature of the fixing roll.   An ink jet recording apparatus comprising: an ink jet recording unit; and the image fixing device according to any one of claims 1 to 6.   8. The ink jet recording apparatus according to claim 7, wherein the ink jet recording unit performs image recording by ejecting an ink in which color material particles containing a charged color material and a resin are dispersed in at least a solvent by electrostatic force.

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