Patent Publication Number: US-2023135510-A1

Title: Image forming apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This patent application is based on and claims priority pursuant to 35 U.S.C. § 119(a) to Japanese Patent Application No. 2021-179749, filed on Nov. 2, 2021, in the Japan Patent Office, the entire disclosure of which is hereby incorporated by reference herein. 
     BACKGROUND 
     Technical Field 
     The present disclosure relates to an image forming apparatus that causes particles each containing an insoluble substance to adhere to a base material to form an uneven image. 
     Discussion of the Background Art 
     A typical electrophotographic image forming apparatus is difficult to form an uneven image (dot) having a height of several hundred μm like a Braille character because the particle diameter of toner for use is too small (several μm). Therefore, it has been proposed to form an uneven image (dot) having a height of about sub mm by adding a foaming agent to the toner and foaming the foaming agent with a fixing device. 
     SUMMARY 
     In an embodiment of the present disclosure, an image forming apparatus includes a latent image forming device and a visualizing device. The latent image forming device forms a latent image with an adhesive on a base material. The visualizing device causes particles to adhere to the latent image to visualize the latent image as an uneven image. The particles each contains an insoluble substance. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1 A  is a schematic configuration view of an image former according to an embodiment of the present disclosure; 
         FIG.  1 B  is a schematic configuration view of an image former according to an embodiment of the present disclosure; 
         FIG.  1 C  is a schematic configuration view of an image former according to an embodiment of the present disclosure; 
         FIGS.  2 A,  2 B, and  2 C  illustrate a process of forming a plurality of particle layers on a sheet; 
         FIG.  3    illustrates a process of stabilizing a particle layer on the sheet: 
         FIG.  4 A  illustrates a process of securing the particle layer on the sheet; 
         FIG.  4 B  illustrates a process of securing the particle layer on the sheet; 
         FIG.  5 A  illustrates the configuration of a particle; 
         FIGS.  5 BA and  5 BB  illustrate the configuration of a particle; 
         FIGS.  5 CA and  5 CB  illustrate the configuration of a particle; 
         FIG.  5 D  illustrates the configuration of a particle; 
         FIG.  6    is a cross-sectional view of a particle bearer: 
         FIG.  7    illustrates a coated state of a release agent; 
         FIG.  8 A  is a schematic view of a nozzle portion; 
         FIG.  8 B  is an exploded perspective view of the nozzle portion; 
         FIG.  8 C  is a cross-sectional view taken along line A-A of  FIG.  8 A ; 
         FIG.  8 D  is a cross-sectional view taken along line B-B of  FIG.  8 A ; 
         FIG.  9    illustrates a coated state of a coating agent; 
         FIG.  10    is a schematic configuration view of an image former including an ultraviolet (UV) fixing device; 
         FIG.  11 A  is a schematic configuration view of an electrophotographic image forming device; 
         FIG.  11 B  is an enlarged configuration view of a process unit; 
         FIG.  11 C  is a schematic configuration view of a hybrid image forming apparatus in which the image former of  FIG.  1 A  is incorporated in an electrophotographic image forming device: 
         FIG.  11 D  is a view in which the image forming apparatus of  FIG.  1 A  is incorporated immediately before a fixing device; 
         FIG.  12    is a schematic configuration view of an inkjet image forming device; 
         FIG.  13    illustrates a toner image and a particle layer formed on a sheet by the image former of  FIG.  11 C : 
         FIG.  14    is a view illustrating the image former of  FIG.  1 A  incorporated upstream a photoconductor drum; 
         FIG.  15    illustrates a toner image and a particle layer formed on a sheet by the image former of  FIG.  14   ; 
         FIG.  16    is an enlarged view of ink for use for an inkjet printer: 
         FIG.  17 A  is an enlarged cross-sectional view of a Braille character: 
         FIG.  17 B  illustrates a particle layer before melting; and 
         FIG.  17 C  illustrates the particle layer after melting. 
     
    
    
     DETAILED DESCRIPTION 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. 
     In describing embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this specification is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that have a similar function, operate in a similar manner, and achieve a similar result. 
     Hereinafter, embodiments are described with reference to the accompanying drawings. In order to facilitate understanding of the description, the same components in the drawings are denoted by the same reference numerals as much as possible, and redundant description is omitted. 
     As described above, a typical electrophotographic image forming apparatus may be difficult to form an uneven image (dot) having a height of several hundred μm like a Braille character because the particle diameter of toner for use is too small (several μm). Therefore, it has been proposed to form an uneven image (dot) having a height of about sub mm by adding a foaming agent to the toner and foaming the foaming agent with a fixing device. However, it may be difficult to set the foaming agent, the fixing pressure, and the fixing temperature in a well-balanced manner. In addition, it may be difficult to ensure the strength of the dot because a void is formed in the dot, and it may be also difficult to ensure the wear resistance because the toner density in the dot decreases. 
     On the other hand, in order to satisfy the height and strength of a dot, a technique of forming an uneven image (dot) with particles having an insoluble substance as a core has also been proposed. However, when the particle diameter to be used is small, several tens of toner layers may be laminated in order to form an uneven image (dot) having a height of about sub mm. When the toner layer is multi-layered, it may be difficult to obtain a sufficient strength of the uneven image (dot). 
     As described below, according to an embodiment of the present disclosure, an uneven image having sufficient height and strength can be easily formed. 
     Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.  FIGS.  1 A to  1 C  each illustrate an image former  100  according to an embodiment of the present disclosure. The image former  100  is a combination of large-diameter particle layer formation using a conventional electrophotography and adhesive-agent layer formation using a conventional inkjetting. 
     Large diameter particles G are larger in diameter than toner for use in conventional electrographic image formation systems. Thus, an uneven image having a thickness of several hundred μm or more can be formed on a sheet P. The uneven image can obtain image stability corresponding to the image stability of an electrophotographic image, and can be developed to a field such as Braille-character formation requiring unevenness of about several hundred μm. 
     Basic Configuration of Image Former 
       FIG.  1 A  illustrates the basic configuration of the image former  100 . The image former  100  includes a particle tank  110  storing particles and an adhesive agent tank  120  storing an adhesive agent AD as an adhesive. The particle tank  110  and the adhesive agent tank  120  are disposed in this order from the upstream side in the conveyance direction along a conveyance path for a sheet P as a base material. 
     Particles each having a particle diameter of 20 μm or more are stored in the particle tank  110 . A drum-shaped particle bearer  130  is disposed rotatably at the bottom of the particle tank  110 . The rotation axis of the particle bearer  130  is disposed perpendicular and horizontally to the conveyance path for the sheet P. For the particle bearer  130 , a technique of a developing roller for use in the electrophotographic type can be used. 
     A regulation blade  111  is disposed so as to be in contact with the outer peripheral face on the downstream side in the rotational direction of the particle bearer  130 . The regulation blade  111  regulates the thickness of a particle layer borne on the outer peripheral face of the particle bearer  130  to a constant thickness. 
     A nozzle portion  121  is disposed at the bottom of the adhesive agent tank  120 . A latent image is formed on the sheet P with the adhesive agent AD dropped from the nozzle portion  121  by inkjetting. That is, the adhesive agent tank  120  and the nozzle portion  121  are included in a latent image forming device. Here, a “latent image” refers to an image formed with some method so as to be invisible or difficult to see with a naked eye. 
     The particle bearer  130  of the particle tank  110  disposed downstream the adhesive agent tank  120  rotates in a close contact with the sheet P, so that the particles G adhere to the latent image formed with the adhesive agent AD on the sheet P and an uneven image with the particles G is formed. That is, the particle tank  110 , the regulation blade  111 , and the particle bearer  130  are included in a visualizing device for visualizing the latent image with the adhesive agent AD. Here, a “visualized image” refers to an image (shape) having unevenness, and is not necessarily limited to an image (shape) recognized visually. For example, even a colorless and transparent uneven shape is included in the “visualized image”. 
     The particles G each having a spherical shape and a single diameter are used and a single particle layer is basically formed on the outer peripheral face of the particle bearer  130 , so that charging of the particle layer can be made uniform. Further, a single particle is developed for a latent image of one dot to form a uniform dot particle image. As a result, achieved can be stabilization of image quality due to application of frequency modulation (FM) screening, cost reduction of color images due to arrangement of a plurality of colors without superimposition, and resource saving/miniaturization due to no cleaner. Even if a portion where two particle layers partially overlapping each other are formed on the outer peripheral face of the particle bearer  130 , there is no significant influence on charging uniformity of such a particle layer or uniform-dot particle image formation. Note that the particles G are not limited to toner and can be developed to other application fields. 
     Formation of Multiple Particle Layers 
     Two sets of the particle tank  110  and the adhesive agent tank  120  can be disposed in series as illustrated in  FIG.  1 B . That is, two particle tanks  110  and two adhesive agent tanks  120  are alternately disposed from the upstream side along the conveyance path for the sheet P. This arrangement enables the particles to be stacked in two layers in the thickness direction on the sheet P. In order to stack three or more particle layers on the sheet P, the configuration of  FIG.  1 B  can be further added by a desired number of layers such as three sets in series or four sets in series along the conveyance path for the sheet P. As a result, a plurality of layers can be formed in one pass by a high-speed machine. An intermediate transfer medium instead of the sheet P can be used to collectively transfer the multiple particle layers formed on the intermediate transfer medium onto the sheet P. 
     It is also possible to increase the number of layers of the large-diameter particles G to two or more by increasing the number of the particle tanks  110  and the adhesive agent tanks  120  disposed in series. Adoption of such a technique facilitates adjustment in the thickness direction, which is conventionally difficult to control. 
     As illustrated in  FIG.  1 C , use of an intermediate bearer  140  facilitates formation multiple layers of two or more layers. In  FIG.  1 B , direct coating of the adhesive agent AD onto the sheet P causes attraction of the large-diameter particles G. In order to form a plurality of large-diameter particle layers, an adhesive-agent application device (adhesive agent tank  120 ) and a large-diameter particle supply device (particle tank  110 ) corresponding to the number of layers are provided. Use of the intermediate bearer  140  facilitates formation of an optional number of large-diameter particle layers due to rotation of the intermediate bearer  140  by the number of layers. 
     The intermediate bearer  140  is larger in diameter than the particle bearer  130 , and has a diameter of about twice to three times in the illustrated example. The rotation axis of the intermediate bearer  140  is disposed perpendicular and horizontally to the conveyance path for the sheet P. 
     The adhesive agent tank  120  is disposed directly above the intermediate bearer  140 . The particle tank  110  is disposed closer to the downstream of the rotational direction of intermediate bearer  140  than the adhesive agent tank  120  is, and disposed substantially directly beside the intermediate bearer  140 . The outer peripheral face of the particle bearer  130  exposed outside the particle tank  110  faces the outer peripheral face of the intermediate bearer  140 . 
     Due to rotation of the intermediate bearer  140  in the arrow direction for a plurality of times (by the number of layers), the particles G supplied from the particle bearer  130  are repeatedly supplied to the same portion of the latent image with the adhesive agent AD on the outer peripheral face of the intermediate bearer  140 . As a result, multiple particle layers of the optional number of two or more layers are formed on the outer peripheral face of the intermediate bearer  140 . The multiple particle layers formed in such a manner can be collectively transferred onto the sheet P by bringing the outer peripheral face of the intermediate bearer  140  close to the sheet P. 
       FIG.  1 C  illustrates a columnar medium as the intermediate bearer  140 . A belt type intermediate transfer medium, however, may be provided as the intermediate bearer  140 . Further, the sheet P can be wound around the intermediate bearer  140  serving as a holder for the sheet P and a large-diameter particle layer can be directly formed on the sheet P. 
     Formation of Multiple Particle Layers by Reciprocation 
       FIGS.  2 A to  2 C  illustrate a process of forming multiple particle layers on a sheet P by reciprocating the sheet P. That is, a first particle layer is formed in the step of  FIG.  2 A  as in  FIG.  1 A . As illustrated in  FIG.  2 B , the sheet P on which the first particle layer formed is retracted in the arrow direction and once returned to the original position. 
     As illustrated in  FIG.  2 C , the sheet P is advanced again in the arrow direction, and the adhesive agent is applied onto the first particle layer to form a second particle layer. Repetition of this step facilitates formation of multiple particle layers even having two or more layers. 
     Fixing Device 
       FIG.  3    illustrates the image former  100  described with reference to  FIGS.  1 A to  2 C  to which a fixing device  150  is added. The large-diameter particle layer formed by the method of  FIGS.  1 A to  2 C  is in a state of being temporarily fixed on the sheet P by the adhesive agent AD. Therefore, in order to stabilize an uneven image with the large-diameter particle layer, the corresponding surface layers of the large-diameter particles G are melted by the heat of the fixing device  150 . 
     The fixing device  150  includes a pair of upper and lower heating rolls  151  and  152  in each of which a heating source is incorporated, and passes the sheet P having the formed particle layer between the heating rolls  151  and  152 . Solidification of the adhesive agent AD by the heat of the heating rolls  151  and  152  increases the bonding force between the particles and increases the bonding force of the particle layer to the sheet P. 
     As a result, the large-diameter particle layer with which the uneven image is formed can be firmly fixed onto the sheet P. In  FIG.  3   , the heating rolls  151  and  152  of the fixing device  150  sandwich the sheet P from above and below. Alternatively, a fixing device including a heating belt instead of the heating rolls  151  and  152  may be provided. 
     Adhesive Agent Containing Thermosetting Agent 
       FIG.  4 A  illustrates the case of using an adhesive agent AD containing a thermosetting agent. That is, a thermosetting agent to be cured by heat of 100° C. or more is added to a liquid or a gel adhesive agent AD for attracting large-diameter particles G. 
     When the sheet P on which the large-diameter particles G are attracted passes the fixing device  150 , the large-diameter particles G are pressurized on the sheet P and the thermosetting agent added to the adhesive agent AD is cured by heat. As a result, the adhesive agent AD cured by the heat is secured while containing the large-diameter particles G, so that the large-diameter particles G can be firmly fixed onto the sheet P. 
       FIG.  4 B  illustrates the case where a foaming agent is also added to the adhesive agent AD in addition to the thermosetting agent. Basically, obtained can be the effect similar to effect of the adhesive agent AD to which the thermosetting agent is added in  FIG.  4 A . In  FIG.  4 B , the bonding force of particles to a sheet P can be further strengthened. 
     That is, when the large-diameter particles G pass the fixing device  150 , the foaming agent foams in a state of the large-diameter particles G pressed against the sheet P by the heating roll  151 , and the adhesive agent AD grows so as to cover the large-diameter particles G. As a result, the adhesive agent AD cured by the heat of the heating roll  151  does not solidify the large-diameter particles G on the contact face with the sheet P, but solidifies so as to contain the large-diameter particles G. Therefore, the large-diameter particles G are less likely to be detached from the sheet P in comparison with the case of  FIG.  4 A . Moreover, when trying to increase the height of an uneven image with a foamed toner, the height tends to vary due to the influence of the foaming ratio. The height of the uneven image, however, can be stabilized by using the large-diameter particles G as illustrated in  FIG.  4 A . 
     As the foaming agent, for example, used can be a foaming agent containing a substance that generates gas by thermal decomposition as a main raw material. Specifically, a bicarbonate such as sodium bicarbonate that generates carbon dioxide gas by thermal decomposition, a mixture of NaNO2 and NH4Cl that generates nitrogen gas, an azo compound such as azobisilovyronitrile or diazoaminobenzene, a peroxide that generates oxygen can be used. 
     A microcapsule-type foaming agent is preferable because of the high foaming properties. It is preferable that a low-boiling-point substance contained in the microcapsule be vaporized at least at a temperature lower than the heat fixing temperature. The low-boiling-point substance is specifically a substance that is vaporized at 100° C. or lower, preferably 50° C. or lower, and more preferably 25° C. or lower. 
     However, the thermal responsiveness of the microcapsule-type foaming agent depends not only on the boiling point of the low-boiling-point substance as the core material but also on the softening point of the wall material. Thus, the preferred boiling point range of the low-boiling-point substance is not limited to the above range. Examples of the low-boiling-point substance include neopentane, neohexane, isopentane, isobutylene, and isobutane. Among the examples, isobutane stable to the wall material of the microcapsule and having a high thermal expansion coefficient is preferable. 
     Configuration of Large-Diameter Particle 
       FIGS.  5 A to  5 D  illustrate a plurality of configuration examples of such a large-diameter particle G as described above. A large-diameter particle G illustrated in  FIG.  5 A  has a particle diameter several times to several hundred times (particle diameter of 20 μm or more) larger than the particle diameter of toner (particle diameter of 7 to 8 μm) used for the conventional electrophotography. When the particle diameter is too large, it is difficult to secure the particle to a sheet P and to make multiple large-diameter particle layers. Thus, the particle diameter is desirably 20 μm or more and 500 μm or less. 
     The large-diameter particle G basically has a two-layer structure of a central portion and an outer peripheral covering portion. That is, the center portion contains a heat-resistant particle Ga, and the outer periphery of the heat-resistant particle Ga is covered with a binder resin BR. 
     The heat-resistant particle Ga contains an insoluble substance hardly melted by heat when heat fixing is performed. The binder resin BR has a melting property of binding to a sheet P and the large-diameter particle G in the periphery by melting due to application of heat and pressure from the outside of the large-diameter particle G. 
     Therefore, it is desirable that the heat-resistant particle Ga and the binder resin BR be different in melting temperature by 10° C. or more. Further, as an example of the heat-resistant temperature of the heat-resistant particle Ga at that time, the heat-resistant temperature of the particle is desirably 120° C. or higher when the fixing temperature is 100° C. 
       FIG.  5 BA  illustrates a large-diameter particle G containing a heat-resistant particle Gain the center portion similarly to the large-diameter particle G illustrated in  FIG.  5 A . The heat-resistant particle Ga has an outer peripheral covering portion having a coating layer CM mixed with a coloring material. 
     The coloring material containing a white pigment is added to the coating layer CM. As the white pigment, titanium dioxide, ultrafine titanium dioxide, zinc white, or lithopone can be used. 
     Due to the addition of the coloring material containing the white pigment to the coating layer CM, the color tone of the heat-resistant particle Ga in the central portion is less noticeable in appearance. Further, because the heat-resistant particle Ga has the surface having the coating layer CM, the shape of the heat-resistant particle Ga is not limited to be spherical and thus a heat-resistant particle Ga having an irregular shape can be used. Such a spherical heat-resistant particle Ga typically tends to be higher in cost than an irregular heat-resistant particle Ga. Thus, use of the irregular heat-resistant particle Ga can reduce the cost of uneven image formation. 
     The irregular shape may be, for example, an uneven shape as illustrated in  FIG.  5 BB . The irregular shape can bring an effect that the heat-resistant particle Ga is easily bound to the sheet P and the large-diameter particle G in the periphery. 
     A large-diameter particle G in  FIGS.  5 CA and  5 CB  is basically the same as the large-diameter particle G in  FIGS.  5 BA and  5 BB , but is different in that magnetic particles MP are added to the contained heat-resistant particle Ga. The addition of the magnetic particles MP in such a manner enables formation of an uneven image that reacts with a magnetic sensor or the like. As a result, for example, a recording medium on which an uneven image is formed can be easily classified, arranged, and searched by magnetism. 
     A large-diameter particle G in  FIG.  5 D  is basically the same as the large-diameter particle G in  FIG.  5 A , but is different in that the large-diameter particle G contains transparent heat-resistant particles TP and is covered with a transparent binder resin TR having a transparent surface. The use of the transparent binder resin TR in such a manner enables printing without affecting a planar image with an uneven image such as a Braille character formed as a lower layer. 
     Particle Bearer Having Magnetically Attractive Property 
       FIG.  6    illustrates the configuration of the particle bearer  130  having a magnetically attractive property. The particle bearer  130  has a shaft  131  serving as the rotary shaft magnetized to the S pole and the N pole. The outer periphery of the magnetized shaft  131  is covered with a hollow sleeve  132 . The outer periphery of the sleeve  132  is covered with a low-hardness rubber layer  133 . 
     In order to form an uneven image with large-diameter particles G (particle diameter of 20 to 100 μm) much larger than the particle diameter of the conventional toner (particle diameter of 5 to 13 μm), the particle bearer  130  having a surface roughness Rz of about several μm is difficult to reliably bear the large-diameter particles G on the surface of the particle bearer  130  and reliably supply the large-diameter particles G to the surface of an adhesive agent AD. Therefore, as illustrated in  FIG.  5 CA , the magnetic particles MP are added to the heat-resistant particles Ga and the particle bearer  130  is made to have a magnetically attracting property. 
     As the low-hardness rubber layer  133 , a low-hardness rubber having a hardness of 40 or less in terms of rubber hardness JIS-A can be used. In order to decrease the rubber hardness of the low-hardness rubber layer  133 , a similar effect can be expected even if foamed rubber or foamed rubber with a surface layer is used instead of solid rubber. 
     Note that use of a low-hardness rubber layer having a lower hardness, foamed rubber without a surface layer, or a brush roller for the surface of the particle bearer  130  can enhance the surface bearing property of the particle bearer  130 . As a result, without magnetic attraction, such large-diameter particles G not containing the magnetic particles MP as illustrated in  FIGS.  5 A and  5 BA  can be reliably borne on the surface of the particle bearer  130  and can be supplied to the surface of the adhesive agent AD. 
     Addition of Release Agent to Adhesive Agent 
       FIG.  7    illustrates that large-diameter particles G are secured with an adhesive agent AD 1  to which a release agent is added. The addition of the release agent prevents adhesion of the large-diameter particles G or the adhesive agent AD 1  to the upper heating roll  151  at the time of fixing by heat of the fixing device  150 . 
     This release agent has a property of collecting on the surface layer of an adhesive agent when the adhesive agent is applied onto a sheet P. The release agent collected on the surface layer of the adhesive agent AD 1  can prevent adhesion of the adhesive agent AD 1  to the heating roll  151 . 
     Part of the release agent is volatilized by the heat of the fixing device  150 . The volatilized release agent adheres to the outer peripheral face of the heating roll  151  to form a thin film of the release agent. The thin film of the release agent can prevent adhesion of the large-diameter particles G and the adhesive agent AD 1  to the outer peripheral face of the heating roll  151 . The adhesive agent AD 1  becomes an adhesive agent AD 2  solidified after passing the heating roll  151 , and secures the large-diameter particles G to the sheet P. 
     Nozzle Portion for Adhesive Agent 
       FIG.  8 A  is a perspective view of an exemplary discharge head used for the nozzle portion  121  at the bottom of the adhesive agent tank  120 .  FIG.  8 B  is an exploded perspective view of the discharge head.  FIG.  8 C  is a cross-sectional view taken along line A-A of the discharge head of  FIG.  8 A .  FIG.  8 D  is a cross-sectional view taken along line B-B of the discharge head of  FIG.  8 A . For this discharge head, an inkjet discharge system corresponding to application of a high-viscosity liquid can be used. 
     The discharge head includes a frame member  1210 , a vibration plate  1220 , a path plate  1230  (i.e., a flow-path forming member including a pressurized liquid chamber), and a nozzle plate  1240  (i.e., a flow-path forming member having a nozzle hole) are layered and joined in this order. The frame member  1210  is formed by, for example, injection molding of epoxy-based resin or polyphenylene sulfite. 
     The frame member  1210  is joined to a base substrate  1213  formed of a high-rigidity material such as metal or ceramics. On the base substrate  1213 , formed is a piezoelectric element  1214  (layered piezoelectric element, electromechanical transfer element) serving as a pressure generator for pressurizing liquid (e.g., ink) in a pressurized liquid chamber  1231  that the path plate  1230  is provided with. Inside the frame member  1210 , formed are a recess to be a common liquid chamber  1211  communicating with the pressurized liquid chamber  1231  and an ink supply hole  1212  for supplying ink to the common liquid chamber  1211  from the outside. 
     The piezoelectric element  1214  includes piezoelectric layers of lead zirconate titanate (PZT) having a thickness of 10 to 50 μm/i layer and internal electrode layers of silver/palladium (AgPd) having a thickness of several μm/l layer layered alternately. The internal electrodes are alternately electrically connected to an individual electrode and a common electrode as end face electrodes (external electrodes) on the end face, and a drive signal is supplied to these electrodes through a flexible flat cable (FPC)  1217 . 
     The piezoelectric element  1214  has one face joined to the base substrate  1213  and the other face joined to the vibration plate  1220 . When the piezoelectric element  1214  is recharged due to application of a drive signal, the piezoelectric element  1214  extends. When the charges recharged in the piezoelectric element  1214  is discharged, the piezoelectric element  1214  contracts in the opposite direction. The vibration plate  1220  curves due to this extension and contraction of the piezoelectric element  1214 , so that the corresponding pressurized liquid chamber  1231  is contracted and expanded. 
     A support column portion  1215  is provided between such piezoelectric elements  1214  as described above, corresponding to a partition wall  1231 A between such pressurized liquid chambers  1231  as described above. Here, a piezoelectric element member is slit by half-cut dicing to be divided into comb teeth, and each piezoelectric element  1214  and each support column portion  1215  are formed. The support column portion  1215  is the same in configuration as the piezoelectric element  1214 . The support column portion  1215 , however, simply functions as a support column because no drive voltage is applied. 
     The vibration plate  1220  has an outer peripheral portion  1220 A bonded to the frame member  1210  with an adhesive. The vibration plate  1220  includes an ink supply port  1221  that communicates with the pressurized liquid chamber  1231  and supplies ink from the common liquid chamber  1211  of the frame member  1210  to the corresponding pressurized liquid chamber  1231 . The vibration plate  1220  is formed in, for example, a metal plate shape of nickel having a three-layer structure, and is fabricated by, for example, electroforming. However, a different metal plate or resin plate, a layered member of a metal and a resin plate, or a layered member of a metal and another metal can also be used. 
     The path plate  1230  is formed by molding a stainless steel material into a plate shape. The pressurized liquid chamber  1231  and an ink supply path  1233  are formed by a pressing method. A damper chamber  1232  is formed shallower than the pressurized liquid chamber  1231  resulting from half etching by a wet etching method. Alternatively, for example, used can be a path plate in which a path pattern such as a pressurized liquid chamber  1231  is formed by anisotropically etching a single crystal silicon substrate having the crystal plane orientation ( 110 ) (not limited to single crystal silicon) with an alkaline etching solution such as an aqueous potassium hydroxide solution (KOH). 
     The damper chamber  1232  forms a rectangular space with the nozzle plate  1240  and the vibration plate  1220 , and communicates with the atmosphere through an atmosphere communication pipe  1222  provided in the vibration plate  1220  to have an air damper effect. 
     The nozzle plate  1240  has a nozzle hole  1241  corresponding to each pressurized liquid chamber  1231 . Hereinafter, the nozzle plate  1240  will be described in detail. 
     The nozzle hole  1241  is formed in the nozzle plate  1240  by pressing and polishing. The nozzle plate  1240  is formed of, for example, a stainless steel material (SUS) in a plate shape. 
     Use of such a SUS-based metal member for the nozzle plate  1240  enables coping with various liquids and forming a nozzle plate that enables reduction of a material cost and support of an elongate shape. Note that the material of the nozzle plate  1240  is not limited to stainless steel and thus other metal materials may be used. 
     The inner shape of the nozzle hole  1241  is straight, tapered, or straight-tapered in combination of the two shapes. The hole diameter of the nozzle hole  1241  is, for example, about 10 to 35 μm in diameter on the ink-droplet outlet side, and the nozzle pitch of each row is 150 dpi. 
     A water-repellent treatment layer subjected to a water-repellent surface treatment is provided on a nozzle face  1240 A (a liquid discharge face as an outer face in the discharge direction) of the nozzle plate  1240 . The water-repellent treatment layer is formed by a treatment selected in accordance with the physical properties of ink from, for example, polytetrafluoroethylene (PTFE)-Ni eutectoid plating, electrodeposition of fluororesin, vapor deposition coating of evaporative fluororesin (e.g., fluorinated pitch), firing after coating of a solution of silicon-based resin or fluorine-based resin. Due to the provision of the water-repellent treatment layer, the shape and flying properties of ink droplet are stabilized to provide high-quality images. 
     Application of Coating Agent 
       FIG.  9    illustrates an uneven-image former  100  that a coating agent is applied onto particles in order to stabilize the particles after the particles area visualized on a sheet P. That is, a coating-agent application device for applying a coating agent onto the surface of a large-diameter particle layer is provided between the large-diameter-particle supply device and the fixing device. 
     This coating-agent application device is basically achievable with an application system corresponding to the inkjet system. Alternatively, spraying in a vaporized state like a diffuser is applicable. An adhesive for securing the large-diameter particles G to an image forming medium and a release agent for improving releasability from a fixing roller of the fixing device are also added to the coating agent. 
     Ultraviolet (UV) Fixing device 
       FIG.  10    illustrates the uneven-image former of  FIG.  9    to which a UV fixing device  170  serving as a UV light irradiator is added between the particle tank  110  and the fixing device  150 . A UV-curable agent is added in advance to an adhesive agent AD in the adhesive agent tank  120 . The UV-curable agent contains a resin component that is cured by UV light. 
     Before the sheet P on which an uneven image is formed enters the fixing device  150 , the UV fixing device  170  irradiates the uneven image with UV light. As a result, the adhesive agent AD covering the large-diameter particles G on the uneven image is cured, resulting in prevention of detachment of the large-diameter particles G. 
     In a case where a planar image is not necessary or a planar image is formed with ink to which a UV-curable resin is added, the fixing device  150  is not provided and both the uneven image with the large-diameter particles G and the planar image can be fixed by the UV fixing device  170 . This arrangement enables significant power reduction in comparison with the fixing device. 
     Electrophotographic Image Forming Device 
     The above image former  100  can be a hybrid type as illustrated in  FIG.  11 C  described later in combination with a conventional electrophotographic image forming device. The electrophotographic image forming device may be a monochrome printer or a color printer including a multifunction peripheral (MFP). 
     The conventional electrophotographic image forming device will be described below with reference to  FIGS.  11 A and  11 B .  FIG.  11 A  is a schematic configuration view of a printer serving as the electrophotographic image forming device. FIG. JI B is an enlarged configuration view of a process unit for K of the printer. 
     The printer includes four process units  1 Y,  1 M,  1 C, and  1 K for forming toner images of yellow, magenta, cyan, and black (hereinafter, referred to as Y, M, C, and K, respectively). The process units  1 Y,  1 M,  1 C, and  1 K use, respectively. Y, M, C, and K toners different in color as an image forming substance, but are similar in configuration except the toners. The process units  1 Y,  1 M,  1 C, and  1 K are each replaced at the end of the service life. 
     As illustrated in  FIG.  11 B , the exemplary process unit  1 K for forming a K toner image includes a drum-shaped photoconductor  2 K serving as a latent image bearer, a drum cleaning device  3 K, a static eliminator, a charging device  4 K, and a developing device  5 K. The process unit  1 K serving as an image forming unit is detachably attachable to the main body of the printer, and the consumable parts of the process unit  1 K can be replaced at one time. 
     The charging device  4 K uniformly charges the surface of the photoconductor  2 K rotated clockwise in the figure by a driving device. The surface of the photoconductor  2 K charged uniformly is exposed and scanned with laser light L so as to bear an electrostatic static latent image for K. 
     The electrostatic latent image for K is developed into a K toner image by the developing device  5 K with K toner. Then, the toner image is primarily transferred onto an intermediate transfer belt  16 . The drum cleaning device  3 K removes transfer residual toner adhering on the surface of the photoconductor  2 K after the primary transfer process. 
     The static eliminator eliminates residual charges of the photoconductor  2 K after the cleaning. Due to this elimination, the surface of the photoconductor  2 K is initialized, so that the photoconductor  2 K prepares for a subsequent image formation. With each process unit ( 1 Y,  1 M, or  1 C) different in color, a toner image (Y, M, or C) is similarly formed on the corresponding photoconductor ( 2 Y,  2 M, or  2 C) and is intermediately transferred onto the intermediate transfer belt  16  described later. 
     The photoconductor  2 K has a cylindrical drum portion with the front surface of a hollow aluminum element tube covered with an organic photoconductive layer. The drum portion of the photoconductor  2 K has one end and the other end in the axial direction of the drum portion. A flange having a drum shaft is attached to each of the one end and the other end. 
     The developing device  5 K serving as a developing device includes a vertically-long hopper portion  6 K storing K toner and a developing portion  7 K. In the hopper portion  6 K, disposed are an agitator  8 K rotationally driven by a driving device, a stirring paddle  9 K rotationally driven by a driving device vertically below the agitator  8 K, a toner supply roller  10 K rotationally driven by a driving device in the vertical direction of the stirring paddle  9 K, and others. 
     The K toner in the hopper portion  6 K moves toward the toner supply roller  10 K due to the own weight of the K toner while being stirred by the rotational drive of the agitator  8 K and the stirring paddle  9 K. The toner supply roller  10 K includes a metal core and a roller portion made of a foamed resin or the like covering the surface of the core metal, and rotates while causing the K toner in the hopper portion  6 K to adhere to the surface of the roller portion. 
     In the developing portion  7 K of the developing device  5 K, disposed are a developing roller  11 K that rotates while being in contact with the photoconductor  2 K and the toner supply roller  10 K, a thinning blade  12 K that brings the leading end of the thinning blade  12 K into contact with the surface of the developing roller  11 K, and others. The K toner adhered to the toner supply roller  10 K in the hopper portion  6 K is supplied to the surface of the developing roller  11 K at the contact portion between the developing roller  11 K and the toner supply roller  10 K. 
     When passing the contact position between the roller and the thinning blade  12 K along with the rotation of the developing roller  11 K, the layer thickness of the supplied K toner on the surface of the roller is regulated. Then, the K toner after the regulation of the layer thickness adheres to an electrostatic latent image for K on the surface of the photoconductor  2 K in a development region as the contact portion between the developing roller  11 K and the photoconductor  2 K. As a result, the electrostatic latent image for K is developed to a K toner image. 
     The process unit for K has been described with reference to  FIG.  11 B . At the process units  1 Y,  1 M, and  1 C for Y, M, and C, a Y toner image, an M toner image, and a C toner image are, respectively, formed on the surface of the photoconductor  2 Y, the surface of the photoconductor  2 M, and the surface of the photoconductor  2 C by a similar process. 
     In  FIG.  11 A  illustrated above, an optical writing unit  70  is disposed vertically above the process units  1 Y,  1 M,  1 C, and  1 K. The optical writing unit  70  serving as a latent-image writing device optically scans the photoconductors  2 Y,  2 M,  2 C, and  2 K of the process units  1 Y,  1 M,  1 C, and  1 K with laser light L emitted from a laser diode on the basis of image information. 
     This optical scanning results in formation of respective electrostatic latent images for Y, M, C, and K on the photoconductors  2 Y,  2 M,  2 C, and  2 K. In such a configuration, the optical writing unit  70  and the process units  1 Y,  1 M,  1 C, and  1 K function as an image formation device that forms Y. M, C, and K toner images as visible images different in color on three or more latent image bearers. 
     Note that the optical writing unit  70  irradiates a photoconductor with the laser light (L) emitted from a light source through a plurality of optical lenses and mirrors while polarizing the laser light (L) in the main scanning direction with a polygon mirror rotationally driven by a polygon motor. Adopted can be a device that including a light-emitting diode (LED) array having a plurality of LEDs that emits LED light to perform optically writing with the LED light. 
     A transfer unit  15  that endlessly moves the endless intermediate transfer belt  16  counterclockwise while suspending the intermediate transfer belt  16  is disposed vertically below the process units  1 Y,  1 M,  1 C, and  1 K. In addition to the intermediate transfer belt  16 , the transfer unit  15  serving as a transfer device includes a driving roller  17 , a driven roller  18 , four primary transfer rollers  19 Y,  19 M,  19 C, and  19 K, a secondary transfer roller  20 , a belt cleaning device  21 , a cleaning backup roller  22 . 
     The intermediate transfer belt  16  is stretched over the driving roller  17 , the driven roller  18 , the cleaning backup roller  22 , and the four primary transfer rollers  19 Y,  19 M,  19 C, and  19 K disposed inside the loop. Due to the rotational force of the driving roller  17  rotationally driven counterclockwise in the figure by a driving device, the intermediate transfer belt  16  is endlessly moved in the same direction. 
     The intermediate transfer belt  16  endlessly moved in such a manner is sandwiched between the four primary transfer rollers  19 Y,  19 M,  19 C, and  19 K and the photoconductors  2 Y,  2 M,  2 C, and  2 K. As a result, respective primary transfer nips for Y, M, C, and K at which the front face of the intermediate transfer belt  16  contacts with the photoconductors  2 Y,  2 M,  2 C, and  2 K are formed. 
     A primary transfer bias is applied to each of the primary transfer rollers  19 Y,  19 M,  19 C, and  19 K by a transfer bias power supply. Due to the application, a transfer electric field is formed between the electrostatic latent images of the photoconductors  2 Y,  2 M,  2 C, and  2 K and the primary transfer rollers  19 Y,  19 M,  19 C, and  19 K. Note that instead of the primary transfer rollers  19 Y,  19 M,  19 C, and  19 K, a transfer charger, a transfer brush, or the like may be adopted. 
     When the Y toner formed on the surface of the photoconductor  2 Y of the process unit  1 Y for Y enters the above primary transfer nip for Y with the rotation of the photoconductor  2 Y, the Y toner is primarily transferred from the photoconductor  2 Y onto the intermediate transfer belt  16  due to the action of the transfer electric field and the nip pressure. When the intermediate transfer belt  16  on which the Y toner image is primarily transferred passes through the primary transfer nips for M, C, and K along with the endless movement of the intermediate transfer belt  16 , the M, C, and K toner images on the photoconductors  2 M,  2 C, and  2 K are sequentially superimposed and primarily transferred onto the Y toner image. As a result, four color toner images are formed on the intermediate transfer belt  16 . 
     The secondary transfer roller  20  of the transfer unit  15  is disposed outside the loop of the intermediate transfer belt  16 , and the intermediate transfer belt  16  is sandwiched between the secondary transfer roller  20  and the driven roller  18  inside the loop. As a result, a secondary transfer nip at which the front face of the intermediate transfer belt  16  and the secondary transfer roller  20  contact with each other is formed. 
     A secondary transfer bias is applied to the secondary transfer roller  20  by a transfer bias power supply. Due to the application, a secondary transfer electric field is formed between the secondary transfer roller  20  and the driven roller connected to the ground. 
     Vertically below the transfer unit  15 , a sheet feeding cassette  30  accommodating a plurality of recording sheets P in a sheet bundle state is disposed slidably attachably detachable from the housing of the printer. The sheet feeding cassette  30  includes a sheet feeding roller  30   a  in contact with the uppermost recording sheet P of the sheet bundle, and rotates the sheet feeding roller  30   a  counterclockwise in the figure at a predetermined timing to send the recording sheet P toward a sheet feeding path  31 . 
     A pair of registration rollers  32  is disposed near the end of the sheet feeding path  31 . The pair of registration rollers  32  stops the rotation of both rollers immediately after sandwiching, between the rollers, the recording sheet P sent from the sheet feeding cassette  30 . Then, the rotation drive is resumed at a timing at which the sandwiched recording sheet P can be synchronized with the four color toner images on the intermediate transfer belt  16  at the secondary transfer nip, and the recording sheet P is sent toward the secondary transfer nip. 
     The four color toner images on the intermediate transfer belt  16  brought into close contact with the recording sheet P at the secondary transfer nip is collectively secondarily transferred onto the recording sheet P under the influence of the secondary transfer electric field and the nip pressure, and become a full-color toner image together with the white color of the recording sheet P. When the recording sheet P with the full-color toner image formed on the surface in such a manner passes through the secondary transfer nip, the recording sheet P is curvature-separated from the secondary transfer roller  20  and the intermediate transfer belt  16 . Then, the recording sheet P is sent to a fixing device  34  described later through a post-transfer conveyance path  33 . 
     The transfer residual toner that has not been transferred onto the recording sheet P adheres to the intermediate transfer belt  16  after passing the secondary transfer nip. The transfer residual toner is cleaned from the surface of the intermediate transfer belt  16  by the belt cleaning device  21  in contact with the front face of the intermediate transfer belt  16 . The cleaning backup roller  22  disposed inside the loop of the intermediate transfer belt  16  backs up, from the inside of the loop, the belt cleaning device  21  to clean the intermediate transfer belt  16 . 
     The fixing device  34  forms a fixing nip between a fixing roller  34   a  including a heat source such as a halogen lamp and a pressure roller  34   b  that rotates while being in contact with the fixing roller  34   a  at a predetermined pressure. The recording sheet P sent into the fixing device  34  is held by the fixing nip such that the unfixed-toner-image bearing face is brought into close contact with the fixing roller  34   a . Then, the toner in the unfixed toner image melts due to application of the heat and the pressure, so that a full-color toner image is fixed onto the recording sheet P. 
     The recording sheet P ejected from the fixing device  34  passes the post-fixing conveyance path  35  and then reaches the branch point between a sheet ejection path  36  and a pre-reverse conveyance path  41 . On the side of the post-fixing conveyance path  35 , a switching claw  42  rotationally driven about a pivot  42   a  is disposed, and the vicinity of the end of the post-fixing conveyance path  35  is closed or opened by the pivoting. 
     At the timing at which the recording sheet P is sent from the fixing device  34 , the switching claw  42  stops at the pivotal position indicated by the solid line in the figure, and the vicinity of the end of the post-fixing conveyance path  35  is opened. Thus, the recording sheet P enters the sheet ejection path  36  from the post-fixing conveyance path  35  and is sandwiched between a pair of sheet ejection rollers  37 . 
     In a case where the single-sided print mode is set by, for example, an input operation to an operation device including a numeric keypad or a control signal sent from a personal computer, the recording sheet P sandwiched between the pair of sheet ejection rollers  37  is ejected outside the printer as the recording sheet P is. Then, the ejected recording sheet P is stacked on a stack portion as the upper face of an upper cover  50  of the housing. 
     On the other hand, in a case where the duplex print mode is set, when the rear end side of the recording sheet P conveyed in the sheet ejection path  36  while the front end side is sandwiched between the pair of sheet ejection rollers  37  passes the post-fixing conveyance path  35 , the switching claw  42  rotates to the position of the one-dot chain line in the figure and the vicinity of the end of the post-fixing conveyance path  35  is closed. At substantially the same time, the pair of sheet ejection rollers  37  starts reverse rotation. Then, the recording sheet P is conveyed while the rear end side is directed to the head, and enters the pre-reverse conveyance path  41 . 
     A right end portion of the printer in  FIG.  11 A  serves as a reversing unit  40  that can be opened and closed with respect to the housing body by pivoting about a pivot  40   a . When the pairs of sheet ejection rollers  37  rotates reversely, the recording sheet P enters the pre-reverse conveyance path  41  of the reversing unit  40  and is conveyed vertically from the upper side to the lower side. 
     Then, after passing between a pair of reverse conveyance rollers  43 , the recording sheet P enters a reverse conveyance path  44  curved semicircularly. Further, while the upper and lower faces are reversed along with the conveyance along the curved shape, the traveling direction from the vertically upper side to the vertically lower side is reversed and the recording sheet P is conveyed vertically from the lower side to the upper side. 
     After the conveyance, the recording sheet P reenters the secondary transfer nip through the above sheet feeding path  31 . Then, after the full-color image is collectively secondarily transferred onto the other face, the recording sheet P sequentially passes the post-transfer conveyance path  33 , the fixing device  34 , the post-fixing conveyance path  35 , the sheet ejection path  36 , and the pair of sheet ejection rollers  37 . The recording sheet is ejected outside the printer. 
     The above reversing unit  40  includes an external cover  45  and a swing body  46 . Specifically, the external cover  45  of the reversing unit  40  is supported so as to pivot about the pivot  40   a  provided that the housing of the printer body is provide with. This pivoting allows the external cover  45  to be opened and closed with respect to the housing together with the swing body  46  held inside the external cover  45 . 
     As indicated by the dotted line in the figure, when the external cover  45  is opened together with the swing body  46  inside the external cover  45 , the sheet feeding path  31 , the secondary transfer nip, the post-transfer conveyance path  33 , the fixing nip, the post-fixing conveyance path  35 , and the sheet ejection path  36  between the reversing unit  40  and the printer main body side are vertically divided into two and exposed outside. This exposure facilitates removal of a jammed sheet in the sheet feeding path  31 , at the secondary transfer nip, in the post-transfer conveyance path  33 , at the fixing nip, in the post-fixing conveyance path  35 , or in the sheet ejection path  36 . 
     With the external cover  45  opened, the swing body  46  is supported by the external cover  45  so as to rotate about a swing shaft that the external cover  45  is provided with. When the swing body  46  is opened with respect to the external cover  45  by this rotation, the pre-reverse conveyance path  41  and the reverse conveyance path  44  are vertically divided into two and exposed outside. This exposure facilitates removal of a jammed sheet in the pre-reverse conveyance path  41  or the reverse conveyance path  44 . 
     The upper cover  50  of the housing of the printer is supported so as to be pivotable about a pivotal member  51  as indicated by the arrow in the figure, and pivots counterclockwise in the figure to be opened with respect to the housing. Then, the upper opening of the housing is exposed largely. 
     An optical sensor unit  29  is disposed on the left of the intermediate transfer belt  16  in the figure. The optical sensor unit  29  faces a portion of the intermediate transfer belt  16  wound around the driving roller  17  from the front face side through a predetermined gap. The optical sensor unit  29  detects a patch image (rectangular solid toner image) in a shift-detection image (to be described later) formed on the intermediate transfer belt  16 . 
     Hybrid Printer 
       FIGS.  11 C and  11 D  are schematic configuration views of a hybrid printer in which the uneven-image former according to the embodiments of the present disclosure is incorporated in such a conventional electrophotographic image forming device as in  FIGS.  11 A and  11 B  described above. This hybrid printer includes at least the particle tank  110  and the adhesive agent tank  120  of the uneven-image former  100  according to the embodiments of the present disclosure disposed between the photoconductor  2 K and the fixing device  34 . 
     Alternatively, can be provided a hybrid printer in which the image former according to the embodiments of the present disclosure is incorporated in such a conventional inkjet image forming device  200  as illustrated in  FIG.  12   . With such a hybrid printer, as illustrated in  FIG.  13   , can be additionally formed an uneven image with large-diameter particles G by sequentially superimposing an adhesive agent AD and the particles G on a planar image (toner image T) on a sheet P by the conventional image forming device. 
     The inkjet image forming device  200  includes a printing mechanism  203  and others housed in the main body of the inkjet image forming device  200 , and a sheet feeding cassette (or sheet feeding tray)  204  on which a large number of recording sheets  230  can be stacked from the front side is detachably attached to a lower portion of the main body. The inkjet image forming device  200  further includes a manual sheet feeding tray  205  that is opened for manually feeding such a recording sheet  230  as described above. The recording sheet  230  fed from the sheet feeding cassette  204  or the manual sheet feeding tray  205  is taken in, and a desired image is recorded by the printing mechanism  203 . Then, the recording sheet  230  is ejected to a sheet ejection tray  206  attached to the rear face side. 
     The printing mechanism  203  includes a carriage  201  movable in the main scanning direction, a discharge head mounted on the carriage  201 , and an ink cartridge  202  that supplies ink to the discharge head. The printing mechanism  203  further includes a main guide rod  207  as a guide member and a sub-guide rod  208  laterally bridged on left and right side plates. The main guide rod  207  and the sub-guide rod  208  hold the carriage  201  slidably in the main scanning direction. 
     The carriage  201  includes such discharge heads as described above that discharge ink droplets of respective colors of yellow (Y), cyan (C), magenta (M), and black (Bk). The discharge heads each have a plurality of ink discharge ports (nozzles) arranged in a direction intersecting the main scanning direction. The plurality of ink discharge ports (nozzles) faces downward. Further, such ink cartridges  202  as described above for each supplying ink of corresponding color to the corresponding discharge head are replaceably attached to the carriage  201 . 
     The ink cartridges  202  are each provided with an atmosphere port communicating with the atmosphere on the upper side, and a supply port for supplying ink to the corresponding discharge head on the lower side. The ink cartridges  202  each have a porous body filled with the ink inside the ink cartridge  202 , and the capillary force of the porous body maintains the ink supplied to the corresponding discharge head at a slight negative pressure. The discharge head of each color is used as the discharge head; however, a single discharge head having a nozzle that discharges ink droplet of each color may be provided. 
     Here, the carriage  201  is slidably fitted to the main guide rod  207  on the rear side (downstream side in the sheet conveyance direction), and slidably placed on the sub-guide rod  208  on the front side (upstream side in the sheet conveyance direction). In order to cause the carriage  201  to move and scan in the main scanning direction, a timing belt  212  is stretched between a driving pulley  210  and a driven pulley  211  that are rotationally driven by a main scanning motor  209   a , and the timing belt  212  is secured to the carriage  201 . With this arrangement, the carriage  201  is reciprocated in a direction perpendicular to the sheet face of  FIG.  12    by forward and reverse rotation of the main scanning motor  209   a.    
     In order to convey a recording sheet  230  set in the sheet feeding cassette  204  toward the lower side of the discharge heads, provided are a sheet feeding roller  213  and a friction pad  214  that separate and feed the recording sheet  230  from the sheet feeding cassette  204  and a guide member  215  that guides the recording sheet  230 . Further, provided are a conveyance roller  216  that reverses and conveys the fed recording sheet  230 , a conveyance rolling member  217  that is pressed against a peripheral face of the conveyance roller  216 , and a leading-end rolling member  218  that defines the sending angle of the recording sheet  230  from the conveyance roller  216 . The conveyance roller  216  is rotationally driven by a sub-scanning motor through a gear train. 
     A print receiving member  219  as a sheet guide member is provided in order to guide the recording sheet  230  sent from the conveyance roller  216  on the lower side of the discharge heads in accordance with the movement range of the carriage  201  in the main scanning direction. On the downstream side in the sheet conveyance direction of the print receiving member  219 , a conveyance rolling member  220  and a spur  221  that are rotationally driven to send the recording sheet  230  in the sheet ejection direction. Further, disposed are a sheet ejection roller  223  and a spur  224  that send the recording sheet  230  to the sheet ejection tray  206  and guide members  225  and  226  that form a sheet ejection path. 
     At the time of recording by the image forming device  200 , due to driving of a discharge head according to an image signal while the carriage  201  is moved, ink is discharged onto the stopped recording sheet  230  to record one row. After the recording, the recording sheet  230  is conveyed by a predetermined amount, and then recording for the next row is performed. When a recording end signal or a signal indicating that the rear end of the recording sheet  230  has reached the recording area is received, the recording operation is ended and the recording sheet  230  is ejected. Note that improved can be the fixability by incorporating the UV fixing device  170  of  FIG.  10    into the hybrid type combined with an inkjet system and controlling the amount of UV irradiation during the operation of the carriage  201  (at the time of stopping sheet feeding). 
     Improvement in Visual Recognition of Planar Image 
     As illustrated in  FIGS.  11 C and  11 D , when an uneven image with large-diameter particles G is additionally formed on a planar image by the conventional image forming device, the planar image (toner image T) is hidden below the uneven image with the large-diameter particles G as illustrated in  FIG.  13   . As a result, the visual recognition of the planar image (toner image T) may deteriorate. 
       FIG.  14    illustrates that the formation order of a planar image (toner image T) and an uneven image is rearranged. That is, an uneven image with large-diameter particles G is formed at a stage before a planar image (toner image T) is formed on a sheet P by the conventional image forming device. 
     After the formation of the uneven image with the large-diameter particles G, the planar image (toner image T) is formed by the conventional image forming device. According to this image forming method, the visual recognition can be ensured because the planar image (toner image T) is formed on the surface of the uneven image as illustrated in  FIG.  15   . 
     Ink for Forming Planar Image 
     Next, ink for forming a planar image will be described with reference to  FIG.  16   . Each ink used in the image forming device  200  of  FIG.  12    contains fine particles containing a coloring material and a binder resin corresponding to the coloring material and the binder resin of the corresponding toner. 
     The fine particles are floating in a colloidal form in the ink liquid. Due to incorporation of the fixing device  150  of  FIGS.  4 A and  4 B  in the image forming device  200 , the image stability corresponding to the image stability in an electrophotographic system can be obtained even in an inkjet system. 
     Particle Diameter of Large-Diameter Particle G 
       FIGS.  17 A to  17 D  illustrate the particle diameter of a large-diameter particle G.  FIG.  17 A  illustrates the cross-section of a Braille character BRa. Typically, the diameter A of the Braille character BRa is 1.4 to 1.5 mm, the diameter B of the top flat face is 0.6 to 1.0 mm, and the height C is 0.3 to 0.5 mm. 
     Therefore, in order to express the Braille character BRa as an uneven image with a large-diameter particle layer, a thickness of 0.3 to 0.5 mm is preferable for the Braille character BRa In order to form an uneven image with one or two large-diameter particle layers, the particle diameter D of each large-diameter particle G is desirably 300 to 500 μm. 
     Although the present disclosure has been specifically described on the basis of the embodiments, it is needless to say that the present invention is not limited to the embodiments and thus various modifications can be made within the scope of the technical idea described in the claims.