Printing apparatus and printing method

Abstract

A printing apparatus has an ink ejection device, a drying device, and a fusing device. The ink ejection device causes ink to adhere to a printed object. The ink includes a medium and a fixer polymer. The drying device promotes evaporation of the medium by heating the printed object. The fusing device heats the ink adhering to the printed object by irradiating ultraviolet rays to the ink, thereby fusing the fixer polymer to fix the ink on the printed object.

Description

Technical Field

[0001] This invention relates to a printing apparatus. Background Technology

[0002] In printing apparatuses equipped with inkjet heads, various techniques have been proposed for fixing ink adhering to the printed material in a short time (e.g., Patent Documents 1-3).

[0003] In Patent Document 1, ultraviolet light (hereinafter, sometimes simply referred to as "UV") is irradiated onto ink adhering to the printed material. The UV light is absorbed by the colorant containing the ink, thereby raising the temperature of the ink. As a result, the evaporation of the solvent contained in the ink is promoted, which in turn promotes the fixing of the ink (colorant).

[0004] Patent Document 2 discloses heaters for heating the pre-printing portion of a strip-shaped printed material supplied from a roll, heaters for heating the printing portion of the printed material, and heaters for heating the post-printing portion of the printed material. Furthermore, Patent Document 2 also discloses a UV light source for irradiating a printed material with UV light to cure ink containing a polymeric substance that polymerizes under ultraviolet light.

[0005] Patent Document 3 discloses a printing apparatus in which ink is applied to a transfer belt via an inkjet head, and the transfer belt is then bonded to the workpiece to adhere the ink to the workpiece. Patent Document 3 also discloses techniques for curing the polymer contained in the ink using UV light and for melting the binder resin contained in the ink using a heater.

[0006] Prior art literature

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2017-30359

[0009] Patent Document 2: Japanese Patent Application Publication No. 2014-117921

[0010] Patent Document 3: Japanese Patent Application Publication No. 2014-233864 Summary of the Invention

[0011] One aspect of the printing apparatus of the present invention includes an ink ejection device, a drying device, and a melting device. The ink ejection device adheres ink to a workpiece. The ink comprises a medium and a fixing polymer. The drying device promotes the evaporation of the medium by heating the workpiece. The melting device heats the ink adhered to the workpiece by irradiating it with ultraviolet light, thereby melting the fixing polymer and fixing the ink onto the workpiece. Attached Figure Description

[0012] Figure 1 This is a side view of the printing apparatus according to the first embodiment.

[0013] Figure 2 yes Figure 1 A top view of the printing apparatus.

[0014] Figure 3A Viewed from above Figure 1 A three-dimensional view of the inkjet head of a printing device.

[0015] Figure 3B Viewed from below Figure 3A A 3D view of the inkjet head.

[0016] Figure 3C Viewed from above Figure 3A A three-dimensional view of the main body of the inkjet head.

[0017] Figure 3D yes Figure 3C A magnified view of region IIId.

[0018] Figure 4 It is shown Figure 1 A block diagram of the signal processing system structure of the printing apparatus.

[0019] Figure 5 This means that in Figure 1 A conceptual diagram of a method for fixing ink in a printing apparatus.

[0020] Figure 6 This is a graph showing the estimated time required for the ink medium to evaporate.

[0021] Figure 7 It is shown Figure 1 A graph showing the estimated temperature distribution of the printed material in the printing apparatus.

[0022] Figure 8A This is a graph showing the estimated temperature change of the resin in the ink heated by UV light.

[0023] Figure 8B This is a graph showing the estimated temperature changes of water within ink heated by UV light.

[0024] Figure 9 This is a side view of the printing apparatus according to the second embodiment.

[0025] Figure 10 This is a side view of the printing apparatus according to the third embodiment.

[0026] Figure 11 This is a side view of the printing apparatus according to the fourth embodiment.

[0027] Figure 12A This is a graph showing the light absorption characteristics of the ink assembly according to the embodiment.

[0028] Figure 12B This is a schematic diagram illustrating the ink assembly used to explain the modified example.

[0029] Figure 13A This is a diagram showing the light absorption characteristics of the UV absorber contained in the modified ink assembly.

[0030] Figure 13B This is a graph showing the light absorption characteristics of a modified ink assembly. Detailed Implementation

[0031] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the following drawings are schematic diagrams. Therefore, details are sometimes omitted. Furthermore, the size ratios may not necessarily match reality. The size ratios of multiple drawings may also not be consistent with each other. Sometimes specific dimensions are shown as larger than actual dimensions, and specific shapes, etc., are exaggerated.

[0032] In the second embodiment and the following description, the parts that differ from the embodiments described above will be described in detail. For matters not specifically mentioned, they may be the same as those described above, or deduced by analogy from those embodiments. Furthermore, among the various embodiments, corresponding structures are sometimes labeled with the same reference numerals, even if the details differ.

[0033] The term "medium" can refer to a solvent (or medium) that dissolves other substances (solutes), or a dispersion medium that disperses other substances (dispersed phases). The term "dispersion medium" is generally used in both a narrow and a broad sense. The narrow sense refers to a medium in which particles (dispersed phases) of a certain size (e.g., a particle size of 1 nm or larger) are dispersed. The broad sense includes solvents in addition to the narrow sense of dispersion medium. In this invention, the term is used in its narrow sense.

[0034] As is well known, the "particles" as the dispersed phase are not limited to solids, but can also be liquids or gases. However, in this invention, unless otherwise specified, the term "particles" refers not to particles as the dispersed phase, but to particles of a solid.

[0035] The term "glass" is generally used, for example, in a narrow sense and in a broad sense. The narrow sense refers to a substance whose main component is silicate, while the broad sense refers to a substance that becomes an amorphous solid exhibiting a glass transition upon heating. In this invention, the term is used in the broad sense. Therefore, when referring to glass or glass components in this invention, they are not limited to having silicate as the main component; for example, they may also have polymer as the main component.

[0036] As is well known, the "glass transition temperature" (glass transition point) is the temperature at which the glass transition occurs. Hereinafter, the glass transition temperature is sometimes simply referred to as "Tg". Tg can be measured according to standards such as JIS (Japanese Industrial Standard) K7121. When further stringency is required, Tg can be, for example, the midpoint glass transition temperature among the extrapolated glass transition onset temperature, intermediate glass transition temperature, and extrapolated glass transition end temperature defined in the aforementioned standards. However, it is also possible to refer to the extrapolated glass transition onset temperature when maintaining a state below Tg, and to refer to the extrapolated glass transition end temperature when maintaining a state above Tg.

[0037] <First Implementation>

[0038] (The overall structure of the printing apparatus)

[0039] Figure 1 This is a side view of the printing apparatus 1 according to the first embodiment of the present invention. Figure 2 This is a top view of printing apparatus 1.

[0040] In these figures, for convenience, a fixed orthogonal coordinate system D1-D2-D3 is labeled in space. The printing apparatus 1 can set any direction as the vertical direction. However, in the description of the embodiment, for convenience, the +D3 side is referred to as the vertical top. Unless otherwise specified, the terms "top view" or "top perspective" refer to viewing along the D3 axis.

[0041] The printing apparatus 1, for example, conveys the printed material 101 from the supply roller 3A to the return roller 3B. The supply roller 3A, the return roller 3B, and various rollers described later constitute the conveying device 5 for conveying the printed material 101. The printing apparatus 1 has various devices along the conveying path of the printed material 101. For example, the printing apparatus 1 has: an ink ejection device 7 that ejects droplets of ink onto the printed material 101; and multiple devices (e.g., 9, 11, and 13) that facilitate the fixing of the ink ejected by the ink ejection device 7 onto the printed material 101. In addition, the printing apparatus 1 has a control device 15 that controls the various devices described above. Figure 1 ).

[0042] The printing apparatus 1 may also have a structure other than those described above. For example, the printing apparatus 1 may also have a coating machine (not shown) between the supply roller 3A and the ink ejection device 7, which uniformly applies the coating agent (described later) to the workpiece 101. In addition, for example, the printing apparatus 1 may also have a cleaning section for cleaning the head 21 (described later) of the ink ejection device 7.

[0043] (Printed material)

[0044] The printed object 101 is, for example, in the form of a strip or sheet. Before printing, the printed object 101 is wound around the supply roller 3A. The printed object 101 is fed from the supply roller 3A, passes under the ink ejection device 7, and is wound around the recovery roller 3B for recycling. The dimensions of the printed object 101, such as its material, width, length, and thickness, can be appropriately set. For example, the material of the printed object 101 can be paper, resin, or cloth. The thickness of the resin film (e.g., PET: polyethylene terephthalate) used as the printed object 101 can be appropriately set. As an example of a thickness range, it is 5 μm or more and 20 μm or less. In the following description, the side of the printed object 101 with ink adhering to it is sometimes referred to as the front surface (front side), and the opposite side is referred to as the back surface.

[0045] (Ink)

[0046] The ink ejected by the ink ejection device 7 contains, for example, a medium (solvent and / or dispersion medium), a colorant, and one or more polymers. The polymers include at least a fixing polymer. After the ink is ejected and falls onto the substrate 101, the medium in the ink evaporates. Additionally, the fixing polymer is melted by heating (e.g., becoming a glassy state) and then solidified. Through this process, the colorant is fixed onto the substrate 101.

[0047] It should be noted that, as understood from the above description, the ink of this embodiment is, for example, not a UV-curable ink. UV-curable inks contain a synthetic resin (i.e., a UV-curable resin) that reacts with the energy of ultraviolet light to chemically change from a liquid to a solid state, and is fixed onto the printed material 101 by the curing action of the UV-curable resin. The ink of this embodiment does not substantially contain such a UV-curable resin (polymer). However, the ink of this embodiment may contain a small amount of UV-curable resin, to a degree that would not qualify as a UV-curable ink.

[0048] The medium is, for example, the component with the highest mass percentage in the ink (before it is ejected). The mass percentage of the medium can be appropriately set; it can be less than 50% by mass or more than 50% by mass, for example, more than 50% by mass and less than 70% by mass. The medium can be water or an aqueous solvent, or it can be an organic substance (e.g., an organic solvent). In the description of this embodiment, the case where the medium is water is mainly used as an example.

[0049] Colorants can be pigments insoluble in the medium, dyes soluble in the medium (solvent), or a combination of both. Pigments and dyes can be any known substance and substances in which they are applied. For example, a pigment can be a surface-coated pigment to inhibit agglomeration (so-called self-dispersing pigment), or it can be a pigment without such coating. The percentage of colorant by mass in the ink before ejection can be appropriately set. As an example of such a range, it is 1% to 10% by mass.

[0050] In this embodiment, as understood from the above-described function, the fixer polymer exists as particles (solids) in the ink at least before ejection. Therefore, the fixer polymer does not have the property of being soluble in the medium (e.g., water-soluble) and has a glass transition temperature (Tg) higher than the temperature of the ink before ejection. Furthermore, the fixer polymer has the property of remaining as a solid component after the ink is heated to fix the colorant. It should be noted that the fixer polymer can also perform functions other than fixing the colorant.

[0051] The Tg of the fixer polymer can be an appropriate value. For example, in a solution containing polymers other than the fixer polymer, it can be higher than the Tg of some or all of the polymers. However, the Tg of the fixer polymer can also be lower than the Tg of all other polymers. If an example of a range for the Tg of the fixer polymer is shown, it is above 70°C and below 120°C (or below 110°C).

[0052] The mass percentage of the fixer polymer can be appropriately set. For example, in an ink solution containing more than one polymer besides the fixer polymer, the mass percentage of the fixer polymer can be greater than the mass percentage of any type of polymer, or greater than the total mass percentage of the aforementioned one or more polymers. In this case, for example, the effect obtained by evaporating the medium before the fixer polymer melts (described later) is improved. Of course, the mass percentage of the fixer polymer can also be smaller than the above. As an example of the range of the mass percentage of the fixer polymer in the ink solution before ejection, it is 1% or more and 40% or less.

[0053] It should be noted that one or more polymers other than the fixer polymer may sometimes decompose and evaporate due to heat after the ink is ejected. In such cases, the aforementioned relationship between the mass percentage of the fixer polymer and the mass percentage of the aforementioned one or more polymers may be established, for example, before the ink is ejected (before evaporation occurs). Furthermore, in the description of the embodiments, unless otherwise specified, the mass percentage of each polymer can be understood as the mass percentage in a manner that does not result in polymer evaporation, or the mass percentage before polymer evaporation occurs.

[0054] The specific composition and / or components of the fixing polymer can be appropriate. For example, the fixing polymer can be an acrylic polymer, a styrene polymer, a vinyl chloride polymer, or a methacrylic polymer. It should be noted that the Tg of these polymers can be in the temperature range of 70°C or higher and 120°C as described above.

[0055] In the case where the ink contains polymers other than the fixer polymer, the physical properties and functions of these other polymers can be appropriate. For example, the other polymers may or may not have the property of being soluble in the medium (solvent) (e.g., water solubility). Furthermore, the other polymers can be liquids or solids before the ink is ejected. Additionally, the other polymers can be dispersant polymers used to disperse pigments (or, from another perspective, to inhibit agglomeration), or rub-resistant polymers used to improve the wiping strength of the ink. The mass percentage of the other polymers can be appropriately set.

[0056] As mentioned above, the Tg of at least one of the other polymers may be lower than that of the fixer polymer. For example, the Tg of the dispersant polymer and / or the Tg of the rub-resistant polymer may be lower than that of the fixer polymer. Specific values ​​for the Tg of polymers having a Tg lower than that of the fixer polymer can be appropriate values. One example of such a range is above 50°C and below 70°C.

[0057] The structure of the dispersant polymer can be a known structure or a suitable structure. For example, the dispersant polymer can be a linear polymer. However, the dispersant polymer can also be particulate. Additionally, for example, the dispersant polymer has a portion adsorbed onto the pigment and a portion exhibiting dispersibility. Dispersibility is manifested, for example, through steric hindrance, electrostatic repulsion, and / or conduction inhibition. The dispersant polymer is generally undesirable when the pigment is a self-dispersing pigment, but it can be added to inks containing self-dispersing pigments. The dispersant polymer can, for example, be a polymer containing styrene and butyl acrylate in a 70:30 ratio. In this case, the Tg of the dispersant polymer can be a temperature in the range of 50°C or higher and less than 70°C.

[0058] The structure of the abrasion-resistant polymer can be a known structure or a suitable structure. For example, the abrasion-resistant polymer can be a polyester resin. In this case, the Tg of the abrasion-resistant polymer can be a temperature in the range of 50°C or higher and less than 70°C.

[0059] In addition to the polymers mentioned above, inks may also contain suitable ingredients. For example, inks may contain surfactants (in addition to dispersant polymers), humectants, surface tension modifiers, pH adjusters, and / or gloss enhancers. These additives may be composed of polymers.

[0060] (Conveying device)

[0061] The conveying device 5 has multiple rollers (e.g., 3A, 3B, 17A, 17B, 19A-19D) along the conveying path of the printed material 101. Each roller is a cylindrical or cylindrical component, arranged axially orthogonal to the conveying direction of the printed material 101, such that its outer peripheral surface abuts against the surface or back of the printed material 101 across its entire width. Furthermore, at least one roller, including the recovery roller 3B, is rotated about its axis by a motor, thereby conveying the printed material 101. It should be noted that, although this embodiment exemplifies the roller being rotated by a motor, the roller can also be rotated by other drive sources or manually.

[0062] The number of rollers, their position relative to the conveying path, and their diameter can be appropriately set. In the illustrated example, in addition to the supply roller 3A and the return roller 3B, the conveying device 5 also includes, sequentially from the supply roller 3A side to the return roller 3B side, a first tension roller 19A, a second tension roller 19B, a first heating roller 17A, a second heating roller 17B, a third tension roller 19C, and a fourth tension roller 19D. Each roller except the return roller 3B can be driven to rotate by a motor or the like, or it can be passively rotated solely by the frictional force from the printed material 101.

[0063] The first heating roller 17A and the second heating roller 17B also serve as devices for promoting the fixing of ink onto the printed material 101, as described in detail later, and have the function of heating the printed material 101. The first tension roller 19A to the fourth tension roller 19D help to apply tension to the printed material 101. In addition, in the illustrated example, the first tension roller 19A to the fourth tension roller 19D also help to ensure close contact between the printed material 101 and the first heating roller 17A and the second heating roller 17B, thereby improving the heating efficiency.

[0064] More specifically, for example, the first heating roller 17A abuts against the back side of the workpiece 101 upstream of the ink ejection device 7. The second tension roller 19B is located upstream of the first heating roller 17A without any other rollers sandwiched between it and the first heating roller 17A, and abuts against the surface of the workpiece 101 (in other words, the side opposite to the side abutting the first heating roller 17A). The first tension roller 19A is located upstream of the second tension roller 19B without any other rollers sandwiched between it and the second tension roller 19B, and abuts against the back side of the workpiece 101 (in other words, the side opposite to the side abutting the second tension roller 19B). At least one of the first tension roller 19A and the second tension roller 19B is subjected to force on the workpiece 101 by a force-applying component (e.g., a spring and / or actuator, not shown). Thus, tension is applied to the workpiece 101, and the workpiece 101 is in close contact with the first heating roller 17A.

[0065] Additionally, for example, the second heating roller 17B abuts against the back side of the printed object 101 at a location downstream of the ink ejection device 7. The third tension roller 19C is located downstream of the second heating roller 17B without any other rollers sandwiched between it and the second heating roller 17B, and abuts against the surface of the printed object 101 (in other words, the side opposite to the side abutting the second heating roller 17B). The fourth tension roller 19D is located downstream of the third tension roller 19C without any other rollers sandwiched between it and the third tension roller 19C, and abuts against the back side of the printed object 101 (in other words, the side opposite to the side abutting the third tension roller 19C). At least one of the third tension roller 19C and the fourth tension roller 19D is subjected to force on the printed object 101 by a force-applying component (e.g., a spring and / or actuator, not shown). Thus, tension is applied to the printed object 101, and the printed object 101 is in close contact with the second heating roller 17B.

[0066] The first heating roller 17A and / or the second heating roller 17B have, for example, larger diameters. This increases the contact area between these heating rollers and the printed material 101, improving heating efficiency. For example, the diameter of the first heating roller 17A is larger than the diameter of the first tension roller 19A and / or the diameter of the second tension roller 19B. Similarly, the diameter of the second heating roller 17B is larger than the diameter of the third tension roller 19C and / or the fourth tension roller 19D. The diameter of the first heating roller 17A and / or the diameter of the second heating roller 17B may also be larger than the diameters of all other rollers included in the conveying device 5.

[0067] When viewed from the side, the straight line formed by the printed object 101 between the second tension roller 19B and the first heating roller 17A can be inclined relative to the straight line formed between the printed object 101 and the first heating roller 17A and the next roller (the second heating roller 17B in the illustrated example), and the inclination angle can be relatively large. Therefore, the range of angles around the axis of the printed object 101 relative to the first heating roller 17A, which is in close contact with it, becomes larger. For example, the inclination angle can be 45° or more, 70° or more, or 90° or more. The same applies to the straight line formed by the printed object 101 between the third tension roller 19C and the second heating roller 17B and the straight line formed between the printed object 101 and the second heating roller 17B and the previous roller (the first heating roller 17A in the illustrated example).

[0068] The roller configuration can also be various other than those described above. For example, the surfaces of the workpiece 101 that the first heating roller 17A, the first tension roller 19A, and the second tension roller 19B abut against can be opposite to the example shown. The first tension roller 19A can be omitted, and the second tension roller 19B can be provided instead. The fourth tension roller 19D can be omitted, and the third tension roller 19C can be provided instead. The first tension rollers 19A to the fourth tension rollers 19D can also be omitted. Rollers other than those shown in the example can also be provided. For example, multiple rollers can be provided between the first heating roller 17A and the second heating roller 17B, arranged on a curve with the upper side as the convex side when viewed from the side, and abutting against the back of the workpiece 101.

[0069] The movement of the printed material 101 can be appropriately set according to the method of the ink ejection device 7, etc. For example, the conveying device 5 can make the printed material 101 move continuously or intermittently. In addition, when the printed material 101 moves continuously, the conveying speed of the printed material 101 can be constant or variable. It should be noted that, from another perspective, intermittent movement is movement accompanied by speed variation. The specific value of the conveying speed of the printed material 101 can be appropriately set. If we give examples of the range of conveying speed (for example, average speed when the speed varies), it is 50 m / min or more and 300 m / min or less, or 100 m / min or more and 200 m / min or less.

[0070] (Ink ejection device)

[0071] The ink ejection device 7 has at least one (20 in the illustrated example) head 21 that is opposite to the printed object 101 and directly undertakes the ejection of ink.

[0072] It should be noted that, in the description of the location of the ink ejection device 7 in this invention, reference may also be made to the location of the head 21, the location of the ejection surface 21a (described later), or the location of the arrangement area of ​​the plurality of nozzles 21b (described later). In other words, in the description of the location of the ink ejection device 7, the term "ink ejection device 7" may be appropriately replaced with the terms "head 21," "ejection surface 21a," or "arrangement area of ​​the plurality of nozzles 21b."

[0073] In this embodiment, the head 21 is substantially fixed in a direction intersecting the transport direction of the printed material 101, and the printing apparatus 1 is called a line printer. However, the printing apparatus may also be a so-called serial printer that alternately performs the action of ejecting droplets while moving the head 21 in a direction intersecting (e.g., approximately orthogonal) the transport direction of the printed material 101 and transporting the printed material 101.

[0074] The head 21 is held by a component not shown, such that the ejection surface 21a (the lower surface in the illustrated example) of the ink ejection is positioned substantially parallel to the workpiece 101. The distance between the ejection surface 21a and the workpiece 101 can be appropriately set. For example, this distance is 0.5 mm or more and 20 mm or less, or 0.5 mm or more and 2 mm or less. The shape of the head 21 in top view (the shape of the ejection surface 21a) can be an appropriate shape, such as an elongated shape (more specifically, a roughly rectangular shape) in the direction intersecting the transport direction of the workpiece 101. The direction intersecting the transport direction is, for example, a direction substantially orthogonal to the transport direction, and is sometimes also referred to as the width direction of the workpiece 101 (hereinafter, the same applies).

[0075] For example, Figure 2 As shown, multiple heads 21 are arranged to form at least one (four in the illustrated example) head group 23. Each head group 23 includes multiple (five in the illustrated example) heads 21. The multiple heads 21 included in each head group 23 are configured such that the printable areas of the heads 21 are connected to each other or their ends overlap in the width direction of the printable material 101. Thus, gapless printing in the width direction of the printable material 101 is possible.

[0076] In the illustrated example, more specifically, in each head group 23, three of the five heads 21 are arranged in the width direction of the printed material 101. The remaining two heads 21 are arranged in the width direction of the printed material 101 at a position offset from the aforementioned three heads 21 in the transport direction, and are respectively located between the aforementioned three heads 21 in the width direction of the printed material 101. Alternatively, in each head group 23, the plurality of heads 21 are arranged in an alternating pattern.

[0077] Four head assemblies 23 are arranged along the transport direction of the printed material 101. From ink reservoir 25 ( Figure 1 Ink is supplied to each head 21. Since the same color of ink is supplied to the heads 21 belonging to the same head group 23, four colors of ink can be printed from the four head groups 23. The colors of the ink ejected from each head group 23 are, for example, magenta (M), yellow (Y), cyan (C), and black (K). By applying such ink to the workpiece 101, a color image can be printed.

[0078] The number of printing heads 21 mounted on the printing apparatus 1 can be one, as long as it is a single color and prints on an area that can be printed by one head 21. The number of heads 21 included in the head group 23, and the number of head groups 23, can be appropriately changed according to the printing method of the workpiece 101 and the printing conditions. For example, the number of head groups 23 can be increased to further perform multi-color printing. In addition, if multiple head groups 23 printing with the same color are arranged and printed alternately in the transport direction, the transport speed can be increased even if heads 21 with the same performance are used. As a result, the printing area per unit time can be increased. In addition, multiple head groups 23 printing with the same color can be prepared and staggered in the direction intersecting with the transport direction to improve the resolution in the width direction of the workpiece 101.

[0079] Furthermore, in addition to printing colored ink, liquids such as coating agents can also be uniformly or patternedly printed using the head 21 for surface treatment of the printed object 101. As a coating agent, for example, if the printed object 101 is a substrate where liquid is difficult to penetrate, a coating liquid forming a liquid receiving layer can be used to facilitate ink fixing. Alternatively, if the printed object 101 is a substrate where liquid easily penetrates, a coating agent forming a liquid penetration inhibiting layer can be used to prevent excessive bleeding of the liquid or minimal mixing with other adjacent liquids. It should be noted that the coating agent can also be applied using a coating machine (not shown) instead of printing based on the head 21.

[0080] Although not specifically illustrated, multiple heads 21 can be housed in the head chamber. The head chamber is essentially configured as a space isolated from the outside. Furthermore, the head chamber has an inlet allowing the printed material 101, conveyed by the transport device 5, to enter, and an outlet allowing the printed material 101, conveyed by the transport device 5, to exit. The printed material 101 is coated with ink within the head chamber by the heads 21. Within the head chamber, compared to the outside, variations in factors affecting ink adhesion are more easily reduced. Such factors include, for example, temperature, humidity, and air pressure. At least one of these various factors within the head chamber can also be actively controlled by appropriate units.

[0081] The way in which the ink droplets are ejected from the head 21 can be appropriate. For example, the head 21 can be a piezoelectric head that ejects droplets by applying pressure to the ink inside the head 21 using a piezoelectric actuator. Alternatively, the head 21 can be a thermosensitive head that heats the ink to generate bubbles and ejects droplets by the pressure accompanying the generation of the bubbles.

[0082] (A device for fixing ink onto the printed material)

[0083] As described above, the printing apparatus 1 has multiple devices that facilitate the fixing of ink ejected from the ink ejection device 7 onto the printable material 101. These multiple devices include, for example, a drying device 9, a melting device 11, and an auxiliary melting device 13. Generally, these devices promote ink fixing by heating the ink. However, the specific structure, heating amount, and / or location of these devices differ. Consequently, these devices exert different effects on the ink, and / or their effects influence each other.

[0084] (Drying device)

[0085] The drying apparatus 9 promotes the evaporation of the ink medium by heating the printed material 101, for example. The heating of the printed material 101 by the drying apparatus 9 can be performed before the ink adheres to the printed material 101, after the ink adheres to the printed material 101, or both before and after adhesion. When the drying apparatus 9 heats the printed material 101 after the ink has adhered, it can heat the printed material 101 from the back side (or without directly heating the ink), or it can heat the printed material 101 from the surface side (or directly heat the ink together with the printed material 101), or it can heat the printed material 101 from both the back side and the surface side.

[0086] From another perspective, the drying device 9, in the transport direction of the printed material 101, may have a portion located upstream of the ink ejection device 7, a portion located at the same position as the ink ejection device 7, a portion located downstream of the ink ejection device 7, or portions integrally or dispersedly located at two or more of the above three positions. Furthermore, the drying device 9, relative to the printed material 101, may have a portion located on the surface side, a portion located on the back side, or both. It should be noted that, in order to suppress turbulence generated in the space at the same position as the ink ejection device 7, thereby reducing the ink ejection stability, and to heat the printed material 101 and the ink, the drying device 9 may not be located at the same position as the ink ejection device 7, but may have a portion located upstream of the ink ejection device 7.

[0087] It should be noted that, in the description of the location of the drying device 9 in this invention, reference may be made to the location of the portion of the drying device 9 that directly contributes to the heating of the printed material 101 (e.g., the outer peripheral surface of the heating roller or the air outlet for delivering warm air), or the location of the portion of the printed material 101 that is heated by the drying device 9 (e.g., the portion where the roller abuts or the portion from which warm air is blown). In other words, in the description of the location of the drying device 9, the term "drying device 9" may be appropriately replaced with the term "part that directly contributes to heating" or "the portion of the printed material 101 that is heated."

[0088] The drying device 9 heats the printed material 101 approximately uniformly in the width direction (the heating amount is constant in the width direction). Consequently, the temperature distribution in the width direction of the printed material 101 is approximately the same. However, the heating amount of the drying device 9 in the width direction of the printed material 101 can also be different. For example, the heating amount can be relatively increased on both sides of the width direction where heat dissipation is easier. The length of the printed material 101 that the drying device 9 can simultaneously heat in the transport direction can be arbitrarily set.

[0089] The drying apparatus 9 can have various structures. In this embodiment, the drying apparatus 9 has a first heating roller 17A. As described above, the first heating roller 17A abuts against the back of the workpiece 101 at a location upstream of the ink ejection device 7.

[0090] More specifically, the first heating roller 17A contacts the printed material 101 only a portion of its outer circumferential surface around its axis. Furthermore, the first heating roller 17A does not slide relative to the printed material 101, but rather rotates actively or passively as the printed material 101 moves. Therefore, it can be understood that the first heating roller 17A has a first portion 17a and a second portion 17b at mutually different positions around its axis that heat the printed material 101, such that the first portion 17a and the second portion 17b alternately contact the printed material 101.

[0091] The specific structure of the first heating roller 17A can be various, such as a known structure or a structure that applies such a structure. For example, although not specifically illustrated, the first heating roller 17A can also be configured to have an internal heating wire, which heats up according to Joule's law by flowing current through the heating wire. Alternatively, for example, the first heating roller 17A can also be configured to have an internal induction coil, which heats up through induction heating. Furthermore, for example, the first heating roller 17A can also be configured to have a flow path for supplying a heat-generating medium from the outside. The cylindrical or cylindrical substrate of the first heating roller 17A can be made of suitable materials such as ceramic and / or metal.

[0092] (Melting apparatus)

[0093] The melting device 11 heats the ink adhering to the substrate 101 by irradiating it with UV light. Through this heating, as described above, the fixer polymer (which, from another perspective, is a glass component) within the ink melts. Then, by solidifying the molten fixer polymer, the colorant within the ink is fixed onto the substrate 101. It should be noted that UV light can irradiate the substrate 101 at locations where the ink is not disposed, or it can partially penetrate the ink to irradiate the substrate 101. The material of the substrate 101 can be a material that allows substantial UV transmission, or a material that absorbs at least a portion of the UV light and generates heat.

[0094] The melting device 11 is located downstream of the ink ejection device 7 in the transport direction of the printed material 101, for example, and is located on the surface side of the printed material 101 and opposite to that surface. Thus, the melting device 11 can irradiate the ink with UV light. It should be noted that if the material of the printed material 101 is a UV-transmitting material, unlike the illustrated example, the melting device 11 may be located on the back side of the printed material 101 and opposite to the back side of the printed material 101. In the following description, unless otherwise specified, the illustrated example will be used. The relative positions (distances) of the ink ejection device 7 and the melting device 11 in the transport direction of the printed material 101 can be appropriately set. For example, they can be arranged with a gap between them, or they can be arranged adjacent to each other with (almost) no gap between them.

[0095] It should be noted that, in the description of the location of the melting device 11 in this invention, reference may be made to the location of the UV outlet (the foremost part of the optical system) in the melting device 11, or the location of the area in the printed material 101 irradiated with UV. In other words, in the description of the location of the melting device 11, the term "melting device 11" may also be appropriately replaced with the term "UV outlet" or "area in the printed material 101 irradiated with UV".

[0096] UV irradiation by the melting device 11 can begin, for example, after the heating of the printed material 101 by the drying device 9 is completed. Alternatively, from another perspective, the melting of the fixer polymer in the ink can begin during or after the evaporation of the medium in the ink. It should be noted that even if the medium has completely evaporated, trace amounts of medium may remain in practical applications. For example, even if the ink about to undergo UV irradiation contains less than 5% by mass of medium, it can be understood that the medium has completely evaporated. It should be noted that the aforementioned less than 5% by mass can be either a percentage by mass of the ink about to undergo UV irradiation or a percentage by mass of the ink before ejection.

[0097] Furthermore, from another perspective, in the conveying direction of the printed material 101, the melting device 11 can be located downstream of the drying device 9. In this case, the relative positions (distances) of the drying device 9 and the melting device 11 in the conveying direction of the printed material 101 can be appropriately set. For example, they can be arranged apart from each other, or they can be arranged adjacent to each other without any gap.

[0098] The melting device 11, for example, is capable of irradiating UV light across the entire width of the area that can be printed by the ink ejection device 7. For example, the melting device 11 has a length that covers the entire width of the printable material 101 or the entire width of the printable area, and simultaneously irradiates UV light within that width. However, the melting device 11 may also differ from the illustrated example and irradiate UV light across the entire width of the printable area by moving it in the width direction of the printable material 101.

[0099] The melting device 11 irradiates UV light substantially uniformly along the width of the printable material 101. In other words, the energy of the UV light irradiating the printable material 101 (and the ink) per unit time is substantially constant along the width of the printable material 101. It should be noted that the amount of UV absorption by the printable material 101 (and the ink) is affected by the distribution of the ink along the width. Therefore, the amount of heating based on UV light is not necessarily uniform along the width. It should also be noted that the melting device 11 may differ from the above, with varying amounts of UV irradiation along the width of the printable material 101.

[0100] In the printed material 101, the shape of the UV-irradiated area is, for example, a rectangle with sides parallel to both the transport direction and the width direction of the printed material 101. It should be noted that the UV-irradiated area can also be a shape other than a rectangle. In the width direction of the printed material 101, the length of the UV-irradiated area is, as described above, the entire width of the area that the ink ejection device 7 can print. Furthermore, in the transport direction of the printed material 101, the length of the UV-irradiated area can be appropriately set.

[0101] The specific structure of the melting device 11 can be any suitable structure. For example, the melting device 11 may have at least a light source 11a that generates UV light. Furthermore, the melting device 11 may also have a reflector that reflects UV light leaking from the light source 11a to the side opposite to the printed material 101, an aperture with an opening that adjusts the shape of the cross-section of the UV light from the light source 11a, and / or a lens that focuses the UV light. Even with such elements, the light source 11a can be defined simply as the melting device 11. The light source 11a may be composed of suitable elements such as an LED (light emitting diode), an incandescent bulb, a fluorescent lamp, or a mercury lamp. The light source 11a may have only one of the aforementioned elements or may have multiple of the aforementioned elements. It may also be a surface light source composed of multiple elements (e.g., LEDs).

[0102] As is known, UV light is light with a wavelength shorter than visible light, for example, 10 nm or more and 400 nm or less. The UV emitted by the melting device 11 can be near-ultraviolet or far-ultraviolet. Near-ultraviolet light can be any of the so-called UV-A, UV-B, and UV-C. In other words, the wavelength of the UV emitted by the melting device 11 can be appropriately set. The UV emitted by the melting device 11 can be a narrow-band UV with an energy distribution like laser light, or a wide-band UV. In the description of wavelength in this invention, for example, the wavelength at which the energy peaks (the highest peak in the case of multiple peaks) can be referred to.

[0103] The intensity of the UV light irradiating the printing material 101 (and the ink) by the melting device 11 can be appropriately set. It should be noted that, in this invention, the UV intensity is the energy of the UV light irradiating a unit area of ​​the printing material 101 per unit time. The UV intensity can, for example, be higher than the intensity of the UV light irradiating the printing material to cure a UV-curable ink. For example, the intensity of the UV light used to cure a UV-curable ink is typically less than 10 W / cm². 2 In contrast, the intensity of the UV from the melting device 11 can be 10 W / cm². 2 Above, 20W / cm 2 Above or 30W / cm 2 That's all. However, unlike the above, the intensity of the UV from the melting device 11 may be lower than the intensity of the UV used to cure the UV-curable ink.

[0104] The cumulative amount of UV light irradiated by the melting device 11 onto the printed material 101 (and the ink) can be appropriately set. It should be noted that the cumulative amount of light is a value obtained by integrating the intensity over time. For example, the cumulative amount of UV light can be greater than the cumulative amount of UV light irradiated onto the printed material to cure UV-curable ink. For instance, the cumulative amount of UV light irradiated onto the printed material to cure UV-curable ink is typically less than 500 mJ / cm². 2 In contrast, the cumulative UV light intensity irradiated by the melting device 11 onto the printed material 101 can be 500 mJ / cm². 2 Above, 1000mJ / cm 2 Above, 1500mJ / cm 2 Above 5000mJ / cm 2 Above or 10000 mJ / cm 2 That's all. However, it is also possible that, unlike the above, the cumulative amount of UV light irradiated by the melting device 11 onto the printed object 101 is less than the cumulative amount of UV light irradiated onto the printed object to cure the UV-curable ink.

[0105] (Auxiliary melting device)

[0106] The auxiliary melting device 13 is located on the opposite side of the melting device 11 relative to the printed object 101, and assists in melting the fixer polymer by heating the back side of the printed object 101. Since the auxiliary melting device 13 assists in melting the fixer polymer, the position of the printed object 101 in the transport direction can be referenced from the description of the position of the melting device 11. For example, the auxiliary melting device 13 can be positioned downstream of the ink ejection device 7 and the drying device 9.

[0107] It should be noted that, similar to the drying apparatus 9, in the description of the location of the auxiliary melting apparatus 13, reference may be made to, for example, the location of the portion of the auxiliary melting apparatus 13 that directly contributes to the heating of the printed material 101, or the location of the portion of the printed material 101 that is heated by the auxiliary melting apparatus 13. In other words, in the description of the location of the auxiliary melting apparatus 13, the term "auxiliary melting apparatus 13" can be appropriately replaced with the term "part that directly contributes to heating," or "the portion of the printed material 101 that is heated."

[0108] In a top-view perspective view of the printed material 101, at least a portion of the area in the printed material 101 heated by the auxiliary melting device 13 overlaps with at least a portion of the area in the printed material 101 irradiated with UV by the melting device 11. These two areas may be substantially identical or not. For example, the entire area irradiated with UV may overlap with a portion or all of the area heated by the auxiliary melting device 13. In this case, as will be understood from the effects described later, the energy of the UV can be effectively used for melting the fixing polymer.

[0109] The auxiliary melting device 13 heats the printable 101 approximately uniformly in the width direction (the heating amount is constant in the width direction). However, the heating amount of the auxiliary melting device 13 in the width direction of the printable 101 can also be different. For example, the heating amount can be relatively increased on both sides of the width direction where heat dissipation is easier. The length of the printable 101 that the auxiliary melting device 13 can heat simultaneously in the transport direction of the printable 101 can be arbitrarily set.

[0110] The auxiliary melting device 13 can have various structures. In this embodiment, the auxiliary melting device 13 has the previously described second heating roller 17B. The structure of the second heating roller 17B can be the same as that of the first heating roller 17A, or it can be different. In short, the descriptions already given regarding the structure of the first heating roller 17A (which may include a first part and a second part, or may include heating wires, induction coils, or flow paths, etc.) can be appropriately applied to the second heating roller 17B.

[0111] (Head of the ink ejection device)

[0112] The basic structure of the head 21 of the ink ejection device 7 can be a known structure or a structure that incorporates such a structure, or various other structures. Additionally, in this embodiment, the head 21 may also have a heater for heating the ink before ejection. By preheating the ink before ejection, for example, the time required for the evaporation of the medium and / or the melting of the fixer polymer in the ejected ink can be reduced. The structure of the heater in the head 21 can be any suitable structure. An example of a heater provided in the head 21 is shown below.

[0113] Figure 3A This is a perspective view of the head 21 viewed from above (on the side opposite to the printed object 101). Figure 3B This is a perspective view of the head 21 viewed from below (the side of the printed object 101). Figure 3C This is a three-dimensional view of a portion of the head 21 (head body 27) viewed from above.

[0114] The head 21, for example, has a head body 27 and a back member 29 fixed above the head body 27. The head body 27 has an ejection surface 21a opposite to the printed material 101. A plurality of nozzles 21b for ejecting ink droplets open at the ejection surface 21a. The head body 27 can be considered the component directly related to the ejection of the droplets. On the other hand, the back member 29, for example, facilitates the mediation of the head body 27 with other components (e.g., the ink reservoir 25 and the control device 15). In addition to the above, the head 21 may also have suitable components (e.g., a frame covering the back member 29).

[0115] Although not specifically illustrated, the head body 27, for example, has multiple independent flow paths that are each connected to multiple nozzles 21b, and a common flow path that is connected to the multiple independent flow paths and extends along the ejection surface 21a. On the side of the head body 27 opposite to the ejection surface 21a, for example, one or more openings 27a are provided that are connected to the ends of one or more common flow paths, respectively or jointly. In the case where the head 21 is piezoelectric, an actuator substrate 30 can be provided on the side of the head body 27 opposite to the ejection surface 21a. This actuator substrate 30 includes multiple piezoelectric actuators that individually apply pressure to the multiple individual flow paths.

[0116] The back component 29 has, for example, one or more openings 29a communicating with the ink tank 25 via a tube (not shown), and a flow path (not shown) connecting the openings 29a and the opening 27a of the head body 27. In addition, although not specifically shown, the back component 29 houses a driver that supplies power to the head body 27 (e.g., actuator substrate 30) and a circuit board on which the driver is mounted.

[0117] Figure 3D yes Figure 3C A magnified view of region IIId.

[0118] The head body 27 has multiple plates 31 stacked on top of each other. A nozzle 21b and a flow path communicating with the nozzle 21b are formed by forming through holes or the like in the multiple plates 31. The plates 31 are made of, for example, metal or resin.

[0119] In the head 21 of such a structure, for example, as Figure 3A As shown, a heater 33A can be provided on the upper surface of the back member 29. The heater 33A can be, for example, a sheet-like heater (thin-film heater). The heater 33A is constructed, for example, by sandwiching a heating wire that extends appropriately in a plane between a sheet-like insulator. The planar shape and size of the heater 33A can be appropriately set.

[0120] Additionally, for example, in addition to heater 33A, or instead of heater 33A, such as Figure 3DAs shown, a sheet-like heater 33B can also be sandwiched between multiple plates 31. Like heater 33A, heater 33B is constructed, for example, by sandwiching a heating wire that extends appropriately within a plane within a sheet-like insulator. The planar shape and dimensions of heater 33B can be appropriately set. For example, heater 33B can have a width that covers all nozzles 21b in a top view.

[0121] Although not specifically illustrated, heaters may be provided on the sides of the head 21 (the surfaces intersecting the D1 or D2 directions), inside the back member 29, and / or between the head body 27 and the back member 29, in addition to the upper surface of the back member 29 and / or the interior of the head body 27, or alternatively. The heaters are not limited to sheet-like heaters; for example, they may be heaters with a thickness that cannot be conceptually categorized as sheet-like. Furthermore, the head 21 may have a flow path for the heating medium, in addition to or instead of a heater.

[0122] (Control device)

[0123] Although not specifically illustrated, control device 15 ( Figure 1 For example, it may be configured to include a CPU (central processing unit), ROM (read-only memory), RAM (random access memory), and external storage devices. In other words, the control device 15 may be configured to include a computer. The CPU constructs the various functional units described later by executing programs stored in ROM and / or external storage devices. In addition, the control device 15 may include logic circuits that only perform certain actions, or it may be conceptualized as including drivers that supply power to various elements.

[0124] The control device 15 can also be appropriately distributed in hardware. For example, the control device 15 can also be configured to include: a plurality of lower control devices respectively provided in the conveying device 5, the ink ejection device 7, the drying device 9, the melting device 11 and the auxiliary melting device 13; and a higher control device that controls the plurality of lower control devices (e.g., to achieve synchronization) by sending and receiving signals with the plurality of lower control devices.

[0125] (Structure of a signal processing system)

[0126] Figure 4 This is a block diagram showing the structure of the signal processing system of the printing apparatus 1.

[0127] The control device 15 has various functional units (e.g., 35, 37, 39, 41, 43, and 45) constructed by executing programs via a CPU. The head control unit 35 controls the head 21. The conveying speed control unit 37 controls the conveying device 5. The first temperature control unit 39 controls the drying device 9 (in other words, the first heating roller 17A). The head temperature control unit 41 controls the head heaters 33 (33A and / or 33B) provided on the head 21. The second temperature control unit 43 controls the auxiliary melting device 13 (in other words, the second heating roller 17B). The UV control unit 45 controls the melting device 11. More specifically, for example, as described below.

[0128] (Head control unit)

[0129] The head control unit 35 generates information corresponding to the size of the droplets that should be ejected by each nozzle 21b during the ejection period that arrives at a predetermined cycle, based on data including information containing images (text is also a type of image), and outputs this information to a driver (not shown) of the head 21. The driver (not shown) inputs a voltage corresponding to the input information to the driving element (e.g., a piezoelectric actuator) of each nozzle 21b. It should be noted that the head control unit 35 can also be conceptualized as including a driver. The ejection cycle can be a constant value set by the manufacturer of the printing apparatus 1, or it can be a value set by the head control unit 35 based on predetermined information. The predetermined information mentioned above is, for example, the resolution in the transport direction of the printed material 101 set by the manufacturer or user, and / or the transport speed of the printed material 101 set by the manufacturer or user. For example, when printing on the printed material 101 transported at a speed of 100 m / min using a 1200 dpi head 21, it is possible to operate at a drive frequency of 78.74 kHz to control the ejection of ink.

[0130] (Conveyor Speed ​​Control Department)

[0131] The transport speed control unit 37 controls the transport device 5, for example, to maintain the transport speed of the printed material 101 at a target value. The target value is, for example, substantially constant during the operation of the printing apparatus 1 (or, from another perspective, during printing; the same applies hereinafter). Furthermore, the target value can be a constant value set by the manufacturer of the printing apparatus 1, a value set by the user, or a value set by the transport speed control unit 37 based on specified information. The specified information may include, for example, the resolution in the transport direction of the printed material 101 set by the manufacturer or the user, and / or the droplet ejection cycle set by the manufacturer or the user.

[0132] The conveying speed control unit 37 can perform feedback control based on the detection value of the speed sensor 47 that detects the speed of the printed material 101 (as illustrated in the example), or it can perform open-loop control without feedback. The speed sensor 47 can detect the speed of the printed material 101 itself, or it can detect the speed of the element driving the printed material 101. For the former, for example, a device that detects speed based on image recognition, such as an optical mouse, can be cited. For the latter, a sensor (such as an encoder or rotary transformer) that detects the rotation of the rollers of the conveying device 5 or the motor driving the rollers can be cited. By using these, it is possible to achieve synchronization between the speed of the printed material 101 and the ejection timing from the head 21.

[0133] The conveying speed control unit 37 supplies power, for example, to at least one motor that rotates at least one roller of the conveying device 5 via a driver (not shown). It should be noted that the conveying speed control unit 37 can also be conceptually designed to include a driver. The driver can perform feedback control of the motor (a lower-level feedback control than the aforementioned feedback control) or open-loop control of the motor.

[0134] (First Temperature Control Unit)

[0135] The first temperature control unit 39 controls the drying apparatus 9, for example, to maintain the temperature of a predetermined area of ​​the printed material 101 at a target value. The predetermined area is, for example, the temperature of a region in the printed material 101 heated by the drying apparatus 9. However, the predetermined area could also be other areas in the printed material 101, and areas whose temperature changes are governed by the heating of the drying apparatus 9. For example, the predetermined area could also be a region downstream of the region heated by the drying apparatus 9, and a region not heated by other devices (e.g., in...). Figure 1 (The area opposite the ink ejection device 7 in the example).

[0136] The target temperature value is, for example, substantially constant during the operation of the printing apparatus 1. Furthermore, the target value can be a fixed value set by the manufacturer of the printing apparatus 1, a value set by the user, or a value set by the first temperature control unit 39 based on specified information. This specified information may include, for example, ink-related information input by the manufacturer or user (e.g., information that can determine the Tg of a specified polymer), the transport speed of the printed material 101 set by the manufacturer or user, and / or the relative position (distance) of the drying device 9 to other devices (e.g., 7, 11, and / or 13) input by the manufacturer or user.

[0137] The first temperature control unit 39 can perform feedback control based on the detection value of the first temperature sensor 49, which detects the temperature of a predetermined area of ​​the printed material 101 (as illustrated in the example), or it can perform open-loop control without feedback. The first temperature sensor 49 can detect the temperature of the printed material 101 itself, the ambient temperature near the printed material 101, or the temperature of an appropriate part of the drying apparatus 9 (e.g., the surface or interior of the first heating roller 17A). In either case, the first temperature sensor 49 can be a non-contact temperature sensor or a contact temperature sensor. Examples of non-contact temperature sensors include radiation thermometers and thermal imagers. Examples of contact temperature sensors include thermocouples, thermistors, and resistive temperature sensors. The detected temperature can be directly compared to a target value, or it can be compared to a target value after appropriate correction (e.g., conversion to a temperature at a location different from the sensor's position).

[0138] Specifically, the control of the drying apparatus 9 is, for example, the control of the power supplied to the heat-generating element (e.g., heating wire or induction coil) via a driver (not shown). More specifically, the voltage, current, and / or frequency (in the case of AC) can be controlled according to the type of the heat-generating element. It should be noted that the first temperature control unit 39 can also be conceptually included as including a driver. Alternatively, the control of the drying apparatus 9 can be other than the above-described control methods. For example, in a structure that supplies a heat medium to the first heating roller 17A, the flow rate of the heat medium can also be controlled.

[0139] (Head temperature control unit)

[0140] The head temperature control unit 41 controls the head heater 33, for example, to maintain the temperature of the ink held at a predetermined location on the head 21 as a target value. The predetermined location can be either the head body 27 or the back member 29, or any location within these members (in other words, any flow path). However, if the predetermined location is within or near the nozzle 21b, the accuracy of the ink 103's control over the fixing of the printed material 101 is improved.

[0141] The target temperature value is kept substantially constant during the operation of the printing apparatus 1. Alternatively, the target value can be a fixed value set by the manufacturer of the printing apparatus 1, a value set by the user, or a value set by the head temperature control unit 41 based on specified information. This specified information may be, for example, ink-related information input by the manufacturer or user (e.g., information that can determine the Tg of a specified polymer).

[0142] The head temperature control unit 41 can perform feedback control based on the detection value of the head temperature sensor 51 (as illustrated in the example), or it can perform open-loop control without feedback. The head temperature sensor 51 can be exposed within the flow path to detect the temperature of the ink itself, or it can be concealed within the flow path to detect the temperature of the head 21. In the former case, a contact temperature sensor can be used, for example. In the latter case, a contact or non-contact temperature sensor can be used, for example. Specific examples of contact or non-contact temperature sensors are described above. The detected temperature can be directly compared to a target value, or it can be compared to a target value after appropriate correction (e.g., conversion to a temperature at a location different from the sensor's position).

[0143] Specifically, the head heater 33 is controlled, for example, by controlling the power supplied to the head heater 33 via a driver (not shown). More specifically, the voltage, current, and / or frequency (in the case of AC) can be controlled depending on the specific structure of the head heater 33. It should be noted that the head temperature control unit 41 can also be conceptually designed to include a driver.

[0144] (Second Temperature Control Unit)

[0145] The second temperature control unit 43 controls the auxiliary melting device 13, for example, to maintain the temperature of a designated area of ​​the printed material 101 at a target value. The designated area is, for example, the temperature of the region in the printed material 101 heated by the auxiliary melting device 13.

[0146] The target temperature value is kept substantially constant during the operation of the printing apparatus 1, for example. Alternatively, the target value can be a fixed value set by the manufacturer of the printing apparatus 1, a value set by the user, or a value set by the second temperature control unit 43 based on specified information. This specified information may be, for example, ink-related information input by the manufacturer or user (e.g., information that can determine the Tg of a specified polymer).

[0147] The second temperature control unit 43 can perform feedback control based on the detection value of the second temperature sensor 53, which detects the temperature of a predetermined area of ​​the printed material 101 (as illustrated in the example), or it can perform open-loop control without feedback. The second temperature sensor 53 can detect the temperature of the printed material 101 itself, the ambient temperature near the printed material 101, or the temperature of an appropriate part of the auxiliary melting device 13 (e.g., the surface or interior of the second heating roller 17B). In any case, the second temperature sensor 53 can be a non-contact temperature sensor or a contact temperature sensor. Specific examples of contact and non-contact temperature sensors are described above. The detected temperature can be directly compared to a target value, or it can be compared to a target value after appropriate correction (e.g., conversion to a temperature at a location different from the sensor's position).

[0148] The auxiliary melting device 13 may be intended to raise the temperature of the printed object 101 (and the ink) to a predetermined temperature (e.g., a temperature above and below the Tg of the polymer other than the fixer polymer). Alternatively, the melting device 11 may be intended to raise the temperature of the ink to a temperature higher than the aforementioned predetermined temperature (e.g., a temperature above the Tg of the fixer polymer) by UV irradiation. When such an operation is intended, and the heating of the ink by the melting device 11 has a significant impact on the temperature of the printed object 101, the temperature of an appropriate portion of the auxiliary melting device 13 may be detected instead of the temperature of the printed object 101 itself for feedback control.

[0149] Specifically, the control of the auxiliary melting device 13 is, for example, the control of the electricity supplied to the heat-generating element (e.g., heating wire or induction coil) via a driver (not shown). More specifically, the voltage, current, and / or frequency (in the case of AC) can be controlled according to the type of the heat-generating element. It should be noted that the second temperature control unit 43 can also be conceptually included as a driver. Furthermore, the control of the auxiliary melting device 13 can also be other than the above-described control. For example, in a structure that supplies a heat medium to the second heating roller 17B, the flow rate of the heat medium can also be controlled.

[0150] (UV Control Department)

[0151] The UV control unit 45 controls the melting device 11, for example, in a manner that maintains the intensity of the UV irradiated onto the workpiece 101 at a target value while the working distance from the melting device 11 to the workpiece 101 is constant.

[0152] The target intensity value is, for example, substantially constant during the operation of the printing apparatus 1. Furthermore, the target value can be a constant value set by the manufacturer of the printing apparatus 1, a value set by the user, or a value set by the UV control unit 45 based on prescribed information. The prescribed information may include, for example, ink-related information input by the manufacturer or user (e.g., information that can determine the Tg of a specified polymer), and / or the temperature of the area in the printed material 101 assuming no UV irradiation. The temperature assuming no UV irradiation can be a value input by the manufacturer or user, or a value calculated by the UV control unit 45 based on the prescribed information. The prescribed information may include, for example, the target temperature values ​​(or heating amounts) of the elements used for heating (9 (17A), 21 (33), and / or 13 (17B)), and the relative positions (distances) of these elements to the melting device 11.

[0153] The UV control unit 45 performs, for example, open-loop control of the UV intensity without feedback. Additionally, the UV control unit 45 controls the power supplied to the UV-generating light source 11a via a driver (not shown). More specifically, the voltage, current, and / or frequency (in the case of AC) can be controlled according to the configuration of the light source 11a. The driver can also perform power feedback control. The UV control unit 45 can also be conceptualized as including a driver.

[0154] (The fixing effect of ink)

[0155] Figure 5 This is a conceptual diagram illustrating the function of ink in printing apparatus 1 in fixing the printed object 101.

[0156] Figure 5 The up, down, left, and right directions and Figure 1 The up, down, left, and right directions correspond. In Figure 5 The image shows a cross-section of a portion of the printed material 101. The printed material 101 is conveyed from the left side of the paper to the right side. A cross-section of a portion of the head 21 is shown enlarged in the upper left corner of the paper. As the ink 103 is ejected as droplets from the head 21 and adheres to the surface (upper surface) of the printed material 101, it moves along with the printed material 101 while changing the ratio and state of the components (glass state, etc.). Figure 5 This can be understood as a graph showing the change in the state of the same droplet (ink 103) over time, or as a graph showing multiple different droplets simultaneously. It should be noted that in the following description, even if the ratio and state of the components of ink 103 change, the same reference numeral (103) will be used for the ink.

[0157] exist Figure 5In the process, the state of ink 103 (the ratio and state of the components) is conceptualized as five states, from the first state S1 to the fifth state S5.

[0158] The first state S1 is the state of the ink 103 when it is held by the head 21 (in other words, before it is ejected). The ink 103 in the first state S1 contains, for example, a medium 105 (solvent and / or dispersion medium), a colorant 107, and one or more polymers (109 and 111). The one or more polymers include at least the fixing polymer 109. In the illustrated example, the one or more polymers also include a first polymer 111. As mentioned above, the ink may contain other components (including polymers). However, for ease of illustration, in... Figure 5 Illustrations of other components are omitted. The description of the first polymer 111 herein can also be applied to other polymers.

[0159] For ease of illustration, colorant 107 is depicted as particles dispersed in medium 105 (or, from another perspective, pigment). Additionally, fixer polymer 109 exists as particles (in other words, a solid) in the first state S1. Polymers other than fixer polymer 109, as described above in the first state S1, can be solutes or dispersions, and can be liquids or solids. The first polymer 111 illustrated is depicted as a linear dispersant polymer. As stated above, the accompanying drawings of this invention are schematic, and the diameter and density of particles within ink 103 do not reflect actual conditions.

[0160] The second state S2 is the state of the ink 103 when it flies from the head 21 toward the printed object 101 (in other words, after it is ejected and before it lands). The second state S2 (the ratio and state of the components) is basically the same as the first state S1.

[0161] The third state S3 is the state of the ink 103 from the time it adheres to the printed object 101 until a certain period of time has elapsed. In this state, the medium 105 gradually evaporates. At this time, the ink 103 is preheated by the head heater 33, thereby promoting the evaporation of the medium 105. In addition, the printed object 101 is heated by the drying device 9, and this heat is transferred to the ink 103, thereby promoting the evaporation of the medium 105.

[0162] Furthermore, although not specifically illustrated, polymers other than fixer polymer 109, i.e., polymers that are particles in the first state S1 and the second state S2, may also partially or completely become glassy in the third state S3. Additionally, any one or more of the other polymers may evaporate through thermal decomposition. Additives other than polymers contained in the ink may remain or evaporate.

[0163] The fourth state, S4, is the state of the ink 103 about to be irradiated with UV light by the melting device 11. In this state, compared to the third state, S3, the evaporation of the medium 105 proceeds further. For example, the evaporation of the medium 105 can be completed. Through the evaporation of the medium 105, the solute dissolved in the medium 105 or the dispersed matter (excluding the evaporated substances mentioned above) condenses and remains. Figure 5 The image shows the state in which the colorant 107 and the fixer polymer 109 have condensed.

[0164] Polymers other than fixer polymer 109 (e.g., first polymer 111) may remain or decompose and evaporate. In the case of residue, they may or may not be in a glassy state. For example, all polymers remaining besides fixer polymer 109 may be in a glassy state. It should be noted that... Figure 5 In order to simplify the illustration, the ink 103 in the fourth state S4 and the fifth state S5, regardless of the presence or absence of the first polymer 111, is omitted from the illustration.

[0165] The fifth state S5 is the state of the ink 103 when irradiated with UV light by the melting device 11. In this state, the colorant 107 absorbs UV light and generates heat, and the fixer polymer 109 melts due to this heat (becoming in a glassy state). Then, although not specifically illustrated, when the UV irradiation ends and the temperature of the ink 103 decreases, the fixer polymer 109 solidifies, and the colorant 107 is fixed onto the printed material 101. Although not illustrated, if the ink 103 contains other polymers (such as the first polymer 111), these other polymers also solidify (or remain in a solid state).

[0166] As described above, a portion or all of the medium 105 can be evaporated before the fixer polymer 109 melts. In this case, for example, the possibility of the fixer polymer 109 in a glassy state forming a coating and suppressing the evaporation of the medium 105 can be reduced. As a result, the medium 105 can be evaporated effectively. The amount of evaporation of the medium 105 before the fixer polymer 109 melts (or, from another perspective, before being heated by UV) can be, for example, based on the first state S1, 30% or more by mass, 50% or more by mass, 70% or more by mass, or all (95% or more by mass or 100% by mass).

[0167] Heating the ink 103 by irradiating it with UV light can, for example, rapidly heat the ink 103 to melt the fixer polymer 109. However, heat generation primarily occurs in the colorant 107, resulting in localized heating. Consequently, if the ink 103 is heated solely by UV light, excessive temperature rises occur locally, potentially degrading the quality of the ink 103 and / or the printed material 101. Heating the printed material 101 using the drying device 9 and / or the auxiliary melting device 13 can, for example, mitigate localized heating and shorten the heating time.

[0168] Fixer polymer 109 is hypothetical, but it may not be a component of the product. Instead, it can be determined whether it is a fixer polymer based on the presence or absence of the aforementioned effects. That is, it can also be defined as: fixer polymer 109 is one of the polymers contained in ink 103 that exists in a solid (particulate) state before being heated by UV irradiation, melts (becomes in a glassy state) by UV irradiation, and then remains as a solid component in ink 103.

[0169] (Target temperature of the head heater)

[0170] For example, as described above, the head 21 may have a head heater 33 that maintains the temperature of the ink 103 in the first state S1 at a predetermined target temperature. Furthermore, the first state S1 (the state of the component ratio and components) can be substantially the same as the state of the ink 103 at room temperature (e.g., 20°C). Therefore, for example, the target temperature of the head heater 33 can be set to a temperature lower than the Tg of any or all types of polymers that are not desired to be in a glassy state at room temperature. Conversely, the ink 103 may be configured such that the Tg of any or all types of polymers is higher than the target temperature of the head heater 33. By setting the target temperature and / or Tg as described above, the possibility of molten polymer adhering to the inner surface of the nozzle 21b is reduced, for example.

[0171] Furthermore, the target temperature of the head heater 33 can be made as high as possible within a range lower than the Tg of any or all of the aforementioned polymers. Conversely, the ink 103 can be configured such that the Tg of any or all of the aforementioned polymers is as low as possible within a range higher than the target temperature of the head heater 33. By setting the target temperature and / or Tg in this way, for example, the time from when the ink 103 falls onto the printable substrate 101 to when it is fixed on the printable substrate 101 can be shortened. In addition, for example, the possibility of unwanted diffusion of droplets after falling onto the printable substrate 101 can be reduced (conformity retention can be improved). It should be noted that the inventors have observed through experiments that if the temperature of the ink 103 is increased (for example, preset to 45°C or higher), the conformity retention of the ink 103 is improved.

[0172] Specific examples of the Tg of any or all of the above-mentioned polymers and the target temperature of the head heater 33 are given. The Tg of the polymer can be 50°C or higher. On the other hand, the target temperature range of the head heater 33 can be 40°C or higher and less than 50°C, or 40°C or higher and less than 45°C. In addition, from another point of view, for example, the difference between the target temperature of the head 21 and the Tg of a specific type of polymer (e.g., dispersant polymer or rub-resistant polymer) contained in the ink 103 can be 1°C or higher and less than 10°C, or 1°C or higher and less than 5°C, provided that the former is lower than the latter.

[0173] In the second state S2, the temperature of the ejected ink 103 (droplet) decreases due to its flight. This temperature change is linear with respect to the flight distance (time elapsed). Furthermore, the amount of temperature decrease is relatively small. Examples of estimation are shown below. Assume a 2 pL droplet travels 1 mm in an atmosphere at 25°C with an initial velocity of 10 m / s. In this case, if the initial temperature of the droplet is 40°C, the temperature decreases to 38.0°C. If the initial temperature of the droplet is 50°C, the temperature decreases to 46.6°C. Assume a 10 pL droplet travels 1 mm in an atmosphere at 25°C with an initial velocity of 10 m / s. In this case, if the initial temperature of the droplet is 40.0°C, the temperature decreases to 39.3°C. If the initial temperature of the droplet is 50°C, the initial temperature decreases to 48.8°C. When setting the target temperature of the head heater 33 and / or the target temperature of the drying device 9 described below, the temperature difference may or may not be taken into account.

[0174] (Target temperature of the drying device)

[0175] As described above, the drying apparatus 9 can maintain the temperature of the printed object 101 at the target temperature. It can be considered that the temperature of the printed object 101 is approximately the same as the temperature of the ink 103 in the third state S3. The target temperature of the drying apparatus 9 (which, from another perspective, is the temperature of the ink 103 in the third state S3, as in this and the next paragraph) can be lower than the Tg of the fixer polymer 109. Conversely, the ink 103 can be configured such that the Tg of the fixer polymer 109 is higher than the target temperature of the drying apparatus 9. By setting the target temperature and / or Tg in this way, for example, as described above, the possibility of inhibiting the evaporation of the medium 105 due to the coating of the molten fixer polymer 109 is reduced.

[0176] The target temperature of the drying apparatus 9 can be as high as possible within a range below the Tg of the fixer polymer 109. For example, the target temperature of the drying apparatus 9 can be set such that the temperature of the printed object 101 when the ink 103 falls onto the printed object 101 is higher than the temperature of the ink 103. In this case, for example, the effect of promoting the evaporation of the medium 105 is improved. From the opposite perspective, the ink 103 can be selected such that the Tg of the fixer polymer 109 is as low as possible within a range higher than the target temperature of the drying apparatus 9. In this case, for example, the time for the fixer polymer 109 to melt can be shortened.

[0177] In setting the target temperature of the drying device 9, the time required for the medium 105 to evaporate can also be taken into account.

[0178] Figure 6 This is a graph showing the estimated time required for the evaporation of medium 105. In this graph, the horizontal axis shows the surface temperature T (°C) of the ink droplets 103. The vertical axis shows the time t (s) for the evaporation of ink 103 in medium 105 to be completed.

[0179] In this estimation, instead of assuming ink droplets of 103, we assume water droplets. Additionally, we assume a droplet size of approximately 3.8 × 10⁻⁶. －10 m 2 The condition of a hemispherical water droplet with a surface area exposed to an atmosphere at 25°C.

[0180] As shown in the figure, time t shortens sharply when temperature T is higher than the temperature of the atmosphere, and then remains roughly constant before the boiling point (approximately 70°C). Although in Figure 6 It is not specified, but when the temperature T is the same as the ambient temperature (25°C), the time t is approximately 4000 s. Based on this result, for example, the target temperature of the drying device 9 can be set to 70°C.

[0181] Specific examples are given regarding the Tg of the fixer polymer 109 and the target temperature of the drying device 9 (which, from another perspective, is the temperature of the ink 103 in the third state S3. The same applies in this paragraph). The Tg of the fixer polymer can be 70°C or higher and 120°C or lower. On the other hand, the target temperature of the drying device 9, provided it is lower than the Tg of the fixer polymer 109, can be 50°C or higher and less than 120°C, 60°C or higher and less than 120°C, or 70°C or higher and less than 120°C. Furthermore, from another perspective, provided the difference between the Tg of the fixer polymer 109 and the target temperature of the drying device 9 is higher than the former, it can be 1°C or higher and less than 50°C, 1°C or higher and less than 30°C, or 1°C or higher and less than 10°C. These specific examples can be combined with the specific examples of the Tg of polymers other than the fixer polymer 109 and the target temperature of the head heater 33, provided they do not cause contradictions.

[0182] In this embodiment, the drying device 9 is implemented by the first heating roller 17A. The temperature of the printed material 101 decreases as it moves away from the first heating roller 17A. In this way, the aforementioned target temperature can be, for example, a target value of the temperature at a predetermined position from the position of the first heating roller 17A to the position where the ink 103 is about to fall (the position of the ink ejection device 7). For example, the predetermined position can be the position of the first heating roller 17A or the position immediately in front of the ink ejection device 7. The target value of the temperature at the predetermined position can be set such that the temperature of the printed material 101 is controlled within the aforementioned target temperature range over the entire area from the position of the first heating roller 17A to the position immediately in front of the ink ejection device 7.

[0183] The following is an example of the results of estimating the temperature distribution of the printed object 101.

[0184] The estimation conditions (assumptions) are as follows. The temperature of the first heating roller 17A is assumed to be 50°C, 60°C, and 70°C. The temperature of the second heating roller 17B is 70°C. The effect of the melting device 11 is not considered. The temperature of the ambient atmosphere around the printed object 101 is 25°C. The conveying speed of the printed object 101 is 100 m / min. The printed object 101 is PET with a thickness of 12 μm.

[0185] Figure 7 This is a graph showing the estimation results. In this graph, the horizontal axis shows the position x (m) in the D1 direction. The vertical axis shows the temperature T (°C) of the printed material 101. Position x1 shows the position of the first heating roller 17A. Position x2 shows the position of the second heating roller 17B. Lines LT50, LT60, and LT70 show the estimation results when the temperature of the first heating roller 17A is 50°C, 60°C, and 70°C, respectively.

[0186] As shown in the figure, the temperature of the printed object 101 decreases approximately linearly. Therefore, based on, for example, the temperature (or heating amount) of the drying device 9 (in this embodiment, the first heating roller 17A), the relative position (distance) of the drying device 9 to other devices (e.g., the ink ejection device 7 or the melting device 11), and the transport speed of the printed object 101, the temperature of the printed object 101 (ink 103) in the other devices (7 or 11) can be easily estimated. It should be noted that distance and transport speed can be understood as the transport time from the drying device 9 to the other devices.

[0187] From another perspective, by setting the values ​​(target values) of the aforementioned parameters (heating amount, distance, and conveying speed, etc.), any temperature can be achieved at any location, thereby obtaining the various effects described above. For example, the temperature of the portion of the printed material 101 that will be opposite the ink ejection device 7 can be set to a temperature higher than the Tg of the first polymer 111 and lower than the Tg of the fixer polymer 109. In the region from immediately behind the drying device 9 (in this embodiment, the first heating roller 17A) to immediately in front of the portion opposite the melting device 11, the temperature of the printed material 101 can be set to a temperature higher than the Tg of the first polymer 111 and lower than the Tg of the fixer polymer 109. Furthermore, evaporation can be completed before the fixer polymer 109 is melted by the melting device 11.

[0188] exist Figure 7 The diagram shows that when the temperature of the first heating roller 17A is set to 60°C or higher (and further, 70°C or higher), the temperature is maintained at approximately 40°C or higher even at a distance of 1.5m downstream. Thus, by maintaining a higher temperature over a longer distance (or, from another perspective, for a longer time), it is easy to achieve, for example, the effect of reducing the likelihood of temperature drop in the ink 103 falling on the printed material 101, thereby ensuring the shape retention of the ink 103, and / or the effect of heating the ink 103 to promote evaporation.

[0189] (Target temperature of the auxiliary melting device)

[0190] As described above, the auxiliary melting device 13 can maintain the temperature of the printed object 101 at the target temperature. As described above, the auxiliary melting device 13 is intended to raise the temperature of the printed object 101 to a predetermined temperature lower than the Tg of the fixer polymer 109. When the heating of the melting device 11 has a significant impact on the temperature of the printed object 101, the target temperature here may not be the temperature of the printed object 101 itself, but rather the target value of the temperature of a predetermined portion of the auxiliary melting device 13.

[0191] Regarding the target temperature of the auxiliary melting device 13, the description of the target temperature of the drying device 9 can be appropriately referenced. For example, the target temperature of the auxiliary melting device 13 can be lower than the Tg of the fixing polymer 109, or it can be as high as possible within a range lower than the Tg of the fixing polymer 109. As specific values, the range of the target temperature of the auxiliary melting device 13, provided that it is lower than the Tg of the fixing polymer 109, can be 50°C or higher but less than 120°C, 60°C or higher but less than 120°C, or 70°C or higher but less than 120°C. Alternatively, from another perspective, provided that the difference between the Tg of the fixing polymer 109 and the target temperature of the auxiliary melting device 13 is higher than the former, it can be 1°C or higher but less than 50°C, 1°C or higher but less than 30°C, or 1°C or higher but less than 10°C.

[0192] (UV irradiation by the melting device)

[0193] As described above, the temperature of the printed object 101 (or ink 103 from another viewpoint) when it is about to reach the melting device 11 and / or the temperature of the printed object 101 (or ink 103 from another viewpoint) after being heated by the auxiliary melting device 13 can be appropriately set. Furthermore, the intensity of the UV irradiated by the melting device 11 and the irradiation time (or irradiation length in the D1 direction from another viewpoint) can be appropriately set to make the fixing polymer 109 have a Tg of or higher.

[0194] Below are examples of estimated results for the temperature rise caused by UV irradiation.

[0195] First, the temperature rise of the resin containing carbon black (pigment) as colorant 107 is estimated. The estimation conditions (assumptions) are as follows: The particle shape of colorant 107 is a cube with a particle size of 70 nm. The density of colorant 107 is 2200 kg / m³. 3 The specific heat of colorant 107 is 691 J / kgK. 5200 particles of the above-mentioned colorant 107 are present in 0.8 pL of resin. The density of the resin is 1060 kg / m³. 3 The specific heat of the resin is 1340 J / kgK. Assume the UV intensity is 352 kW / m². 2 Of this, 80% is converted into heat. It is assumed that the heat does not diffuse to the outside of the resin. Assume two initial temperatures before UV irradiation: 25°C and 50°C.

[0196] Figure 8A This graph shows the temperature change of 0.8 pL of resin under the above conditions. The horizontal axis represents the UV irradiation time t (μs). The vertical axis represents the temperature T °C. The dashed line represents the case with an initial temperature of 25 °C, and the solid line represents the case with an initial temperature of 50 °C.

[0197] As shown in the figure, the temperature of the resin containing colorant 107 rises to a temperature above the Tg of the fixer polymer 109 within a relatively short time. Specifically, for example, the temperature of the resin rises from 50°C to 120°C in about 0.01 seconds.

[0198] Next, the temperature rise of the water containing the aforementioned resin was estimated. The estimation conditions (assumed) are as follows: 1.2 pL of water and 0.8 pL of the aforementioned resin (containing 5200 colorant 107 molecules) are mixed to form the ink. The density of water is 1000 kg / m³. 3 The specific heat of water is 4180 J / kgK. Assume that heat will not diffuse to the outside of the ink. Assume two initial temperatures before UV irradiation: 25℃ and 50℃.

[0199] Figure 8B This is a graph showing the temperature change of water (or, from another perspective, the ink as a whole) under the conditions described above. The horizontal axis represents the UV irradiation time t (μs). The vertical axis represents the temperature T °C. The dashed line indicates the case with an initial temperature of 25 °C, and the solid line indicates the case with an initial temperature of 50 °C.

[0200] As shown in the figure, the temperature of the ink rises to a temperature above the Tg of the fixer polymer 109 within a relatively short period of time. Specifically, for example, the temperature of the ink rises from 50°C to 120°C in approximately 0.05 seconds.

[0201] As described above, the temperature of the ink can be estimated based on the intensity of the UV and the irradiation time. This means, for example, that the intensity of the UV and the irradiation time (irradiation length in the D1 direction) can be set so that the temperature of the ink 103 in the fifth state S5 rises from the temperature of the ink 103 after being heated by the drying device 9 and / or the auxiliary melting device 13 (e.g., a temperature lower than the Tg of the fixer polymer 109) to the desired temperature (e.g., a temperature higher than the Tg of the fixer polymer 109).

[0202] Furthermore, the above estimation example demonstrates that the temperature of ink 103 can be raised to any temperature in a relatively short time (e.g., less than 0.05 s) by UV irradiation.

[0203] In the above estimation example, the time for ink 103 to rise to 120°C is approximately 0.05 s, while the time for the resin containing colorant 107 to rise to 120°C is approximately 0.01 s. This indicates that UV irradiation causes a localized temperature rise. From another perspective, it is shown that the temperature of ink 103 is not raised solely by the melting device 11, but rather by the drying device 9 and / or the auxiliary melting device 13, thereby mitigating the localized temperature rise.

[0204] (An example of the device's dimensions)

[0205] The various dimensions of the printing apparatus 1, the various dimensions of the various devices within it, and the relative positions (distances) of the devices to each other can be appropriately set. In this embodiment, since the ink 103 is effectively dried and fixed onto the printed object 101, it is easy to shorten the overall length of the printing apparatus 1 (especially the length from the ink ejection device 7 to the recovery roller 3B). Examples of size ranges are shown below. The ranges shown below are merely examples, and the various sizes may also be outside the ranges shown below.

[0206] In the conveying direction (D1 direction) of the printed object 101, the total length of the printing apparatus 1 can be 1m or more and 5m or less. The distance parallel to the D1 direction from the axis of the supply roller 3A to the axis of the first heating roller 17A can be 200mm or more and 600mm or less. The diameter of the first heating roller 17A (and the second heating roller 17B) can be 20mm or more and 100mm or less. The distance parallel to the D1 direction from the axis of the first heating roller 17A to the front end of the ink ejection device 7 can be 200mm or more and 600mm or less. The length parallel to the D1 direction from the front end to the rear end of the ink ejection device 7 can be 300mm or more and 900mm or less. The length parallel to the D1 direction from the rear end of the ink ejection device 7 to the front end of the melting device 11 or the axis of the second heating roller 17B can be 200mm or more and 600mm or less. The length parallel to the D1 direction from the front end to the rear end of the melting device 11 can be 5mm or more and 30mm or less. When a cooling device (not shown) is provided to cool the printed material 101 (ink 103), the length parallel to the D1 direction from the rear end of the melting device 11 to the axis of the recovery roller 3B can be 300 mm or more and 900 mm or less. The above dimensions can be combined with a conveying speed of the printed material 101 of 50 mm / min or more and 300 mm / min or less.

[0207] As described above, in this embodiment, the printing apparatus 1 includes an ink ejection device 7, a drying device 9, and a melting device 11. The ink ejection device 7 causes ink 103 to adhere to the workpiece 101. The ink 103 includes a medium 105 and a fixing polymer 109. The drying device 9 heats the workpiece 101 to promote the evaporation of the medium 105. The melting device 11 irradiates the ink 103 adhered to the workpiece 101 with ultraviolet light to heat the ink 103, thereby melting the fixing polymer 109 and fixing the ink 103 (colorant 107) onto the workpiece 101.

[0208] Therefore, for example, the evaporation of the medium 105 and the melting of the fixer polymer 109 can be performed in different devices. As a result, for example, it is possible to achieve faster fixing of the ink 103, more efficient fixing of the ink 103, and / or improved quality of the ink 103, etc. Specifically, for example, since the drying device 9 heats the printed object 101, by preheating the temperature of the printed object 101 before the ink 103 falls, the temperature of the ink 103 can be raised immediately after the ink 103 falls, thus initiating the evaporation of the medium 105. In addition, for example, the melting device 11 raises the temperature of the colorant 107 by UV irradiation, thereby heating the fixer polymer 109. Therefore, the fixer polymer 109 can be heated before heat diffuses to the printed object 101, improving thermal efficiency. Furthermore, for example, the ink 103 is heated not only by UV irradiation but also by the drying device 9, thus reducing the possibility of deterioration in the quality of the ink 103 and / or the printed material 101 due to localized overheating. For example, the possibility of wrinkles and / or deformation occurring on the printed material 101 due to localized heating is reduced. It should be noted that the inventors' observation that localized heating can cause wrinkles and / or deformation is based on experimental findings.

[0209] The melting device 11 can be located downstream of the drying device 9 in the conveying direction of the printed material 101. From another perspective, the melting device 11 can melt the fixing polymer 109 after the drying device 9 has evaporated the medium 105.

[0210] In this case, for example, after at least a portion of the medium 105 has evaporated, the melting of the fixing polymer 109 is initiated by the melting device 11. As a result, as described above, the possibility that the film formed by the molten fixing polymer 109 will hinder the evaporation of the medium 105 is reduced. Consequently, the ink 103 can be dried and fixed in a short time.

[0211] The amount of heat applied to the printable 101 by the drying device 9 (or, from another perspective, the target temperature), the relative position of the drying device 9 and the melting device 11 (or, from another perspective, the distance) and the conveying speed of the printable 101 can be determined by the evaporation of the medium 105 by the drying device 9 before the melting of the fixing polymer 109 by the melting device 11 begins.

[0212] In this case, for example, the effect of reducing the possibility that the evaporation of the medium 105 is hindered by the coating of the fixer polymer 109 is improved. Furthermore, for example, since the possibility of the evaporating medium 105 generating bubbles within the fixer polymer 109 is also reduced, the quality of the fixed ink 103 is improved. Specifically, for example, the reduction in gloss caused by bubbles is reduced.

[0213] The printing apparatus 1 may also have an auxiliary melting device 13. The auxiliary melting device 13 is located on the opposite side of the printing object 101 from the melting device 11, and can heat the printing object 101 from the back side of the side (surface) where the ink 103 is attached to assist in the melting of the fixer polymer 109.

[0214] In this case, the printable 101 is heated from the surface by UV irradiation and from the back side by the auxiliary melting device 13. As a result, for example, the printable 101 can be heated in a short time. In addition, compared with the method of melting the fixer polymer 109 by UV irradiation alone (which can also be included in the technology of the present invention), local overheating within the ink 103 is suppressed, reducing the possibility of deterioration in the quality of the ink 103 and / or the printable 101.

[0215] The auxiliary melting device 13 may also have a heating surface (the outer peripheral surface of the second heating roller 17B), which is controlled to maintain a predetermined temperature while contacting the back side of the printed material 101. In other words, the auxiliary melting device 13 can heat the printed material 101 in a manner that brings the temperature of the printed material 101 to a predetermined temperature. The melting device 11 can heat the ink adhering to the printed material 101 to a temperature higher than the aforementioned predetermined temperature.

[0216] In this case, for example, since the temperature of the printed object 101 is brought to a predetermined temperature by the auxiliary melting device 13, the possibility of localized overheating mentioned above is easily reduced. Furthermore, even if the temperature of the atmosphere surrounding the printed object 101 changes, the heating amount corresponding to that change can be adjusted by the auxiliary melting device 13, thus eliminating the need to adjust the UV intensity or irradiation time. That is, the structure for irradiating UV by causing the temperature of the ink 103 to exceed the Tg of the fixer polymer 109 is simplified (from another perspective, this is control).

[0217] The drying device 9 can make the first part 17a and the second part 17b of the heated printing material 101 alternately and repeatedly contact the printing material 101.

[0218] In this case, for example, compared to a plate-like arrangement where the heater slides relative to the printed material 101 (continuously abutting against the printed material 101) (which can also be included in the technology of the present invention), the temperature of the first portion 17a or the second portion 17b, which decreases due to contact with the printed material 101, can rise during periods when it is not in contact with the printed material 101. As a result, for example, the heat generated per unit volume of the heating element such as the heating wire can be reduced, and the rate of heating the printed material 101 can be maintained. Furthermore, the burden on the heating element is reduced.

[0219] The drying device 9 can heat the printed material 101 to a temperature lower than the glass transition temperature (Tg) of the fixer polymer 109. The melting device 11 can heat the ink 103 adhering to the printed material 101 to a temperature higher than the Tg of the fixer polymer 109.

[0220] In this case, for example, the possibility of the fixer polymer 109 melting due to heating by the drying device 9 is low, or even if it melts, the amount is small. On the other hand, the fixer polymer 109 can be reliably melted by the melting device 11. As a result, the effect of reducing the possibility that the evaporation of the medium 105 is hindered by the coating of the fixer polymer 109 is improved.

[0221] The ink 103 may contain a first polymer 111 that is different from the fixer polymer 109. The drying apparatus 9 may heat the printed material 101 to a temperature above the glass transition temperature (Tg) of the first polymer 111 but below the glass transition temperature (Tg) of the fixer polymer 109.

[0222] In this case, for example, it can be said that the ink 103 reaches a relatively high temperature within a temperature range lower than the Tg of the fixer polymer 109 by passing through the drying device 9. Therefore, for example, as described above, the effect of the drying device 9 in promoting the evaporation of the medium 105 is improved.

[0223] The drying device 9 may include a first drying device (in this embodiment, a first heating roller 17A) located upstream of the ink ejection device 7 in the transport direction (D1 direction) of the printed material 101. The heating amount of the first drying device, the relative position of the first drying device and the ink ejection device 7, and the transport speed of the printed material 101 may be determined by the manufacturer, the user, and / or the control device 15 in such a way that the temperature of the portion of the printed material 101 that will be in contact with the ink ejection device 7 is above the Tg of the first polymer 111 and below the Tg of the fixer polymer 109.

[0224] In this case, for example, since the temperature of the printed material 101 immediately in front of the ink ejection device 7 is lower than the Tg of the fixer polymer 109, the likelihood that the temperature of the subsequently falling ink 103 will reach the Tg of the fixer polymer 109 is reduced. Furthermore, this easily reduces the likelihood that the coating of the fixer polymer 109 will hinder the evaporation of the medium 105. On the other hand, it can be said that the temperature of the printed material 101 immediately in front of the ink ejection device 7 is relatively high, thus enabling the temperature of the subsequently falling ink 103 to rise in a short time, thereby promoting the evaporation of the medium 105.

[0225] The drying device 9 can be located upstream of the melting device 11 in the transport direction of the printed material 101. The heating amount of the drying device 9 (or, from another perspective, the target temperature), the relative position of the drying device 9 and the melting device 11 (or, from another perspective, the distance) of the drying device 9 to the melting device 11 can be determined by the manufacturer, the user, and / or the control device 15 in such a way that the temperature of the printed material 101 in the region from immediately behind the drying device 9 to immediately in front of the portion opposite to the melting device 11 is above the Tg of the first polymer 111 and below the Tg of the fixer polymer 109.

[0226] In this case, for example, in the region immediately behind the drying device 9 and immediately in front of the melting device 11, since the temperature of the printed material 101 is lower than the Tg of the fixing polymer 109, the likelihood of forming a film of the fixing polymer 109 in this region is reduced. Furthermore, the possibility that the evaporation of the medium 105 is hindered by this film is reduced. On the other hand, it can be said that the temperature of the printed material 101 is relatively high in the aforementioned region, thus improving the effect of promoting the evaporation of the medium 105.

[0227] The first polymer 111 can be a dispersant polymer.

[0228] In this case, for example, if the dispersant polymer is dispersed in the medium 105 before the evaporation of the medium 105 is complete, it is difficult to form a coating. Therefore, for example, even if the temperature of the ink 103 is raised to a temperature higher than the Tg of the dispersant polymer by the drying device 9, the likelihood of the coating hindering the evaporation of the medium 105 is lower compared to raising the temperature of the ink 103 to a temperature higher than the Tg of the fixer polymer by the drying device 9. As a result, for example, raising the temperature of the ink 103 before the formation of the fixer polymer 109 coating improves the effect of effectively evaporating the medium 105.

[0229] Among the polymers contained in ink 103, the fixer polymer 109 has the highest glass transition temperature.

[0230] In this case, for example, it can be said that the Tg of the fixer polymer 109 is relatively high. Therefore, the drying device 9 is able to keep the temperature of the ink 103 relatively high within a temperature range lower than the Tg of the fixer polymer. As a result, the effect of promoting the evaporation of the medium 105 is improved before the film of the fixer polymer 109 is formed.

[0231] <Second Implementation>

[0232] Figure 9 This is a side view showing the structure of the printing apparatus 201 according to the second embodiment, compared with the first embodiment. Figure 1 correspond.

[0233] In the printing apparatus 201, the melting device 11 is located downstream of the second heating roller 17B in the conveying direction of the printed material 101. In other words, the printing apparatus 201 does not have an auxiliary melting device 13 opposite the melting device 11 across the printed material 101. The second heating roller 17B, together with the first heating roller 17A, constitutes a drying device 209 located upstream of the melting device 11. That is, the drying device 209 can be said to have a first drying device composed of the first heating roller 17A and a second drying device composed of the second heating roller 17B.

[0234] Regarding the control and target temperature of the first heating roller 17A (first drying device), the description of the control and target temperature of the first heating roller 17A (drying device 9) in the first embodiment can be used as long as there is no contradiction. In this case, the term "drying device 9" can be replaced with the term "drying device 209" or the term "first drying device" as long as there is no contradiction.

[0235] Regarding the control and target temperature of the second heating roller 17B (second drying device), the description of the control and target temperature of the first heating roller 17A (drying device 9) in the first embodiment can be used, provided there is no contradiction. In this case, the terminology of drying device 9 or first heating roller 17A can be replaced with the terminology of second drying device or second heating roller 17B, provided there is no contradiction. And / or, the description of the control and target temperature of the second heating roller 17B (auxiliary melting device 13) in the first embodiment can also be used. In this case, the terminology of auxiliary melting device 13 can be replaced with the terminology of second drying device, provided there is no contradiction.

[0236] For example, the amount of heat applied to the printable material 101 by the drying device 209 or the second heating roller 17B (the second drying device), the relative position of the drying device 209 or the second heating roller 17B to the melting device 11, and the conveying speed of the printable material 101 can be determined in such a way that the evaporation of the medium 105 by the drying device 209 or the second heating roller 17B is completed before the melting of the fixer polymer 109 by the melting device 11 begins, as well as the conveying speed of the printable material 101. The amount of heat applied to the printing device 209 or the second drying device, the relative position of the second drying device to the melting device 11, and the conveying speed of the printable material 101 can be determined in such a way that the temperature of the printable material 101 is above the Tg of the first polymer 111 and below the Tg of the fixer polymer 109 in the region immediately behind the drying device 209 (or, from another viewpoint, immediately behind the second drying device) to immediately in front of the portion opposite the melting device 11.

[0237] As described above, in this embodiment, the printing apparatus 1 also includes an ink ejection device 7, a drying device 209, and a melting device 11. The ink ejection device 7 causes ink 103 to adhere to the workpiece 101. The ink 103 includes a medium 105 and a fixing polymer 109. The drying device 209 promotes the evaporation of the medium 105 by heating the workpiece 101. The melting device 11 irradiates the ink 103 adhered to the workpiece 101 with ultraviolet light to heat the ink 103, thereby melting the fixing polymer 109 and fixing the ink 103 (colorant 107) onto the workpiece 101.

[0238] Therefore, for example, the same effects as in the first embodiment can be achieved. Specifically, for example, the evaporation of the medium 105 and the melting of the fixer polymer 109 can be carried out in different devices. As a result, for example, it is possible to achieve high-speed fixing of the ink 103, high-efficiency fixing of the ink 103, and / or improved quality of the ink 103, etc.

[0239] As in this embodiment, the drying apparatus 209 may also include a first drying device (first heating roller 17A) disposed upstream of the ink ejection device 7 in the conveying direction of the printed material 101, and a second drying device (second heating roller 17B) disposed downstream of the ink ejection device 7. The melting device 11 may be located downstream of the second drying device.

[0240] In this case, for example, by preheating the temperature of the printed material 101 by the first heating roller 17A before the ink 103 falls, the temperature of the ink 103 after falling can be raised as quickly as possible. Furthermore, for example, the ink 103 after falling can be heated by the second heating roller 17B to cause the medium 105 to evaporate quickly. Therefore, the evaporation of the medium 105 can be easily completed before UV irradiation using the melting device 11.

[0241] It should be noted that, compared to the second embodiment, the second heating roller 17B facilitates raising the temperature of the fixer polymer 109 above its Tg, thereby reducing the burden on the melting device 11. Furthermore, for example, due to limitations in the mechanism design, if the distance from the ink ejection device 7 to the axis of the second heating roller 17B is the same in both the first and second embodiments, the first embodiment can easily shorten the overall length of the printing apparatus 1.

[0242] <Third Implementation Method>

[0243] Figure 10 This is a side view showing the structure of the printing apparatus 301 according to the third embodiment, compared with the first embodiment. Figure 1 correspond.

[0244] The printing apparatus 301 has multiple (three in the illustrated example) melting devices 11A, 11B, and 11C. The melting devices 11A, 11B, and 11C are, for example, substantially the same as the melting device 11 of the first embodiment (except for specific design details such as size). Hereinafter, A to C will sometimes be omitted without distinguishing between the melting devices 11A to 11C. It should be noted that these three melting devices 11 can also be understood as a single melting device.

[0245] Multiple melting devices 11 may be positioned differently in the transport direction of the printed material 101. In the printed material 101, the areas irradiated with UV by the multiple melting devices 11 may be separated from each other in the transport direction, or may be substantially adjacent to each other without gaps, or may overlap each other.

[0246] Multiple melting devices 11 are arranged, for example, along a portion of the printed material 101 that is curved toward the surface side due to the second heating roller 17B. Each melting device 11 irradiates the curved portion of the printed material 101 with UV light in a direction approximately normal to that portion. In other words, the curved portion of the printed material 101 is irradiated with UV light from multiple normal directions. It should be noted that in Figure 10 The example shown illustrates UV irradiation of a curved portion of the printed material 101 from three melting devices 11A, 11B, and 11C. However, by further increasing the distance between each melting device 11 and the printed material 101, more melting devices 11 can be configured, allowing UV irradiation from more melting devices 11 onto the curved portion of the printed material 101. Thus, by irradiating the convexly curved portion of the printed material 101 with UV, a specific area of ​​the printed material 101 can be irradiated with UV from multiple melting devices 11 at a near-vertical angle. This increases the energy density of the irradiated UV, enabling the fusing polymer 109 to melt in a short time.

[0247] Alternatively, unlike the illustrated example, multiple melting devices 11 may be arranged along a linearly extending portion of the printed material 101, irradiating the linearly extending portion with UV light. Furthermore, the portion irradiated with UV light that is bent in a manner protruding towards the surface of the printed material 101 may be composed of rollers other than the second heating roller 17B, or it may be composed of two or more rollers.

[0248] Although not specifically illustrated, the curved portion of the printed material 101 can also be irradiated with UV light from multiple normal directions by methods other than multiple melting devices 11. For example, a single melting device 11 can be configured along the curved portion of the printed material 101. Specifically, for example, multiple light sources 11a can be arranged along the curved portion of the printed material 101, and shared reflectors, apertures, and / or power circuits can be provided for the multiple light sources 11a. The reflectors and / or apertures can have a shape along the curved portion of the printed material 101. However, this can also be understood as defining a melting device 11 for each light source 11a, and sharing reflectors, apertures, and / or power circuits among multiple melting devices 11. Alternatively, for example, a curved surface light source (also an example of a light source 11a) with multiple LEDs (an example of a light source 11a) arranged along the curved portion of the printed material 101 can be provided as a melting device 11.

[0249] The wavelength of UV light, the intensity of UV light, and / or the length of the transport direction of the UV-irradiated area in the printed material 101 of the multiple melting devices 11 can be the same or different from each other.

[0250] For example, the UV wavelengths of multiple (partial or all) melting devices 11 can be identical. In this case, for example, the length of the area irradiated by UV in the transport direction of the printed material 101 can be longer than the length that a single melting device 11 can irradiate. As a result, for example, it is possible to ensure the irradiation time of the same position on the printed material 101 required for melting the fixer polymer 109 while increasing the transport speed of the printed material 101. From another perspective, the design freedom of the melting device 11 for ensuring the irradiation distance (time) required for melting the fixer polymer 109 is increased.

[0251] Furthermore, the wavelengths of UV light emitted by multiple (part or all) melting devices 11 can be different from each other. As explained later in the modified example of ink, the wavelength of UV light that increases the absorption of UV light by the ink (heat generated by UV light) varies depending on the color of the ink 103 (the type of colorant 107). Therefore, for example, in the case where the printing apparatus 1 is a color printer, by setting melting devices 11 that irradiate UV light with wavelengths that increase heat generation for each color, multiple colors of ink 103 can be heated evenly.

[0252] It should be noted that, similar to the melting device that irradiates UV onto the curved portion of the printed material 101, multiple melting devices 11 (which, from another perspective, are multiple light sources 11a) that irradiate UV with different wavelengths can also be a structure that shares a reflector, aperture, and / or power circuit, and can be understood as a single melting device. Multiple LEDs (example of light source 11a) that irradiate UV with different wavelengths can also be arranged in a mixed state to form a surface light source (this is also an example of light source 11a).

[0253] As described above, in this embodiment, the printing apparatus 301 also includes an ink ejection device 7, a drying device 9, and a melting device 11. Therefore, it can achieve the same effects as the first embodiment, for example. Specifically, for example, the evaporation of the medium 105 and the melting of the fixer polymer 109 can be performed in different devices. As a result, for example, it is possible to achieve high-speed fixing of the ink 103, high-efficiency fixing of the ink 103, and / or improved quality of the ink 103, etc.

[0254] The printing apparatus 301 may have a conveying device 5 that conveys the printable 101 while bending at least a portion of the printable 101 to make the surface with ink 103 protrude. One or more melting devices 11 may irradiate the bent portion of the printable 101 by the conveying device 5 (more specifically, the second heating roller 17B) with UV light.

[0255] In this case, for example, since the outer peripheral side is wider than the inner peripheral side, the area where one or more melting devices 11 are arranged can be relatively expanded relative to the area of ​​the printed object 101 irradiated with UV. As a result, for example, by irradiating the relatively narrow area of ​​the printed object 101 with UV from multiple normal directions, the energy density is increased, and the temperature of the ink 103 can be raised in a short time. In addition, for example, since the length of the area irradiated with UV can be ensured in directions other than the D1 direction, the printing device 1 can be shortened.

[0256] The printing apparatus 301 may have multiple light sources 11a, which constitute one or more melting devices 11 and irradiate UV with different wavelengths.

[0257] In this case, for example, as described above, when the printing apparatus 301 is a color printer, by setting a light source 11a that irradiates UV light with a wavelength that generates more heat for each color, it is possible to heat the inks 103 of multiple colors equally. As a result, the possibility of overheating or underheating in a particular color of ink 103 is reduced. Consequently, the quality of the ink 103 and / or the printed matter 101 is improved. From another perspective, the function of melting the fixer polymer 109 is less dependent on the color of the ink 103. In other words, the structure for melting can be applied to various printing apparatuses, including monochrome printers and color printers.

[0258] <Fourth Implementation>

[0259] Figure 11 This is a side view showing the structure of the printing apparatus 401 according to the fourth embodiment, compared with the first embodiment. Figure 1 correspond.

[0260] The drying apparatus 409 of the printing apparatus 401, like the drying apparatus 209 of the second embodiment, has a first drying apparatus (first heating roller 17A) located upstream of the ink ejection apparatus 7, and a second drying apparatus 410 located between the ink ejection apparatus 7 and the melting apparatus 11. However, the structure of the second drying apparatus 410 is different from that of the second drying apparatus (second heating roller 17B) of the second embodiment.

[0261] Specifically, the second drying device 410 can be a warm air dryer that blows warm air onto the printed material 101. In the illustrated example, the second drying device 410 has a surface dryer 455A that blows warm air onto the surface of the printed material 101, and a back dryer 455B that blows warm air onto the back of the printed material 101 (hereinafter, both are sometimes referred to simply as dryer 455). It should be noted that the second drying device 410 may also have only one of the surface dryer 455A and the back dryer 455B.

[0262] For example, although not specifically illustrated, each dryer 455 has a heat source and a blower for discharging gas around the heat source. The heat source may be, for example, the same heat source illustrated in the first heating roller 17A (heating wire, induction coil, or flow path for the hot medium). The blower may, for example, have a fan and a motor for rotating the fan. Each dryer 455 may also have a conduit for guiding the gas discharged by the fan to the printable material 101. Alternatively, unlike the illustrated example, gas from a heat source may be guided through a conduit to both the surface and back surface of the printable material 101. The gas discharged to the printable material 101 is, for example, air.

[0263] Regarding the control or target temperature of the drying device 409 or the second drying device 410, the descriptions of the drying device 9 (first heating roller 17A) of the first embodiment and / or the second drying device (second heating roller 17B) of the second embodiment can be used as long as there is no contradiction.

[0264] For example, the amount of heat applied to the printable material 101 by the drying unit 409 or the second drying unit 410, the relative position of the drying unit 409 or the second drying unit 410 to the melting unit 11, and the conveying speed of the printable material 101 can be determined in such a way that the evaporation of the medium 105 by the drying unit 409 or the second drying unit 410 is completed before the melting of the fixing polymer 109 by the melting unit 11. The amount of heat applied to the printable material 101 by the drying unit 409 or the second drying unit 410, the relative position of the second drying unit 410 to the melting unit 11, and the conveying speed of the printable material 101 can be determined in such a way that the temperature of the printable material 101 is above the Tg of the first polymer 111 and below the Tg of the fixing polymer 109 in the region immediately behind the drying unit 409 (or immediately behind the second drying unit 410 from another viewpoint) to immediately in front of the portion opposite the melting unit 11.

[0265] Furthermore, for example, the control of the second drying device 410, like other drying devices, can be either open-loop control or feedback control. In the latter case, the temperature sensor that detects the temperature of the printed object 101 can detect the temperature of the printed object 101 itself, the ambient air temperature near the printed object 101, and the temperature of a suitable location within the second drying device 410. In the second drying device 410, which is composed of a warm air drying mechanism, the temperature sensor can also detect the temperature of the gas supplied to the printed object 101.

[0266] Additionally, for example, the control of the second drying unit 410, like that of other drying units, can be the control of the electricity supply to the heat source. In the second drying unit 410, which is composed of a warm air drying mechanism, the control of the air supply volume can be performed instead of the control of the electricity supply to the heat source, or based on the control of the electricity supply to the heat source.

[0267] As described above, in this embodiment, the printing apparatus 401 also includes an ink ejection device 7, a drying device 409, and a melting device 11. Therefore, for example, the same effects as in the first embodiment can be achieved. Specifically, for example, the evaporation of the medium 105 and the melting of the fixer polymer 109 can be performed in different devices. As a result, for example, it is possible to achieve high-speed fixing of the ink 103, high-efficiency fixing of the ink 103, and / or improved quality of the ink 103, etc.

[0268] The drying apparatus 409 (second drying apparatus 410) can be configured as a warm air dryer that delivers heated gas. In this case, for example, the structure of the second drying apparatus is simpler compared to the second drying apparatus configured with the second heating roller 17B as in the second embodiment. It should be noted that, compared to this embodiment, the second embodiment, for example, does not allow heat to diffuse more easily to the surroundings of the printed material 101, thus resulting in higher energy efficiency.

[0269] (A variation of the ink group)

[0270] The ink set of the modified example described below includes inks 103 of different colors, and it is assumed that the inks 103 of different colors are irradiated with UV light of the same wavelength. That is, it is assumed that the ink set of the modified example is applied to a color printer in which the UV light emitted by more than one melting device 11 (or, from another viewpoint, more than one light source 11a) has the same wavelength. However, the ink set of the modified example can also be applied to a color printer capable of emitting UV light of different wavelengths.

[0271] Figure 12A This is a schematic diagram illustrating an example of the light absorption characteristics of inks 103 of different colors. The ink 103 in this diagram is, for example, the ink 103 of the embodiment, and not the ink 103 of the modified embodiment.

[0272] In this graph, the horizontal axis represents wavelength λ (nm). The vertical axis represents absorbance Abs (dimensionless). Range RU represents the wavelength range of UV light. Range RV represents the wavelength range of visible light. Range RI represents the wavelength range of infrared light. Line LY represents the characteristics of yellow ink 103. Line LM represents the characteristics of magenta ink 103. Line LC represents the characteristics of cyan ink 103. Line LK represents the characteristics of black ink 103. The lengths of the optical paths are the same for all four colors.

[0273] Absorbance is, for example, the common logarithm of the ratio of incident light intensity to emitted light intensity (incident light intensity / emitted light intensity) (logarithm of incident light intensity / emitted light intensity to the base 10). Absorbance can include the effects of reflection and scattering, or it can exclude the effects of reflection and scattering. For convenience, the effects of reflection and scattering on absorbance are ignored in the following explanation.

[0274] As shown in the figure, the absorbance of ink 103 varies with the wavelength of light. In other words, the heat generated by ink 103 when irradiated with light (e.g., UV) varies with the wavelength of light. Furthermore, this variation occurs differently depending on the color of ink 103. From another perspective, the difference in color of ink 103 is due to differences in the material and / or content (mass %) of colorant 107. Therefore, inks 103 with different materials and / or contents of colorant 107 will generate different amounts of heat when irradiated with the same wavelength of UV. In the illustrated example, for UV at wavelength λ1, black has the highest absorbance, followed by cyan, while yellow and magenta have lower absorbance. As a result, there is a possibility that black may be overheated, or conversely, yellow and magenta may be underheated.

[0275] Therefore, a UV absorber different from the colorant 107 is added to at least one ink 103 in the ink group so that the heat generated by UV (UV of a specified wavelength from another viewpoint) from the melting device 11 is equal among the various inks 103 with different colors. For example, in at least two of the various inks 103, the content of the UV absorber different from the colorant 107 can also be different (one ink 103 may also not contain a UV absorber). With such a structure, by adjusting the content of the UV absorber, it is possible to make the heat generated by UV from the melting device 11 approximate among the various inks 103.

[0276] Alternatively, in at least two of the various inks 103, one ink 103 may contain a lower absorption rate of colorant 107 for UV light from the melting device 11 compared to the other ink 103, and one ink 103 may contain a higher concentration of UV absorber than the other ink 103. In this case, the other ink 103 may not contain any UV absorber. The relationship of the absorption rates of colorant 107 can be considered as the relationship of the molecular absorptivity (molar absorptivity) of colorant 107. Furthermore, the relationship of the absorption rates of colorant 107 can be considered as the relationship of the absorbance of solutions of the same concentration in a solvent (e.g., water) containing colorant 107. The molecular absorptivity is an inherent value of colorant 107, and the concentration of colorant 107 in the ink 103 does not vary significantly. Therefore, when the ink assembly has the structure described above, the heat generated by the UV from the melting device 11 can be made more similar among the various inks 103.

[0277] Alternatively, among various inks 103, the ink 103 with a lower absorption rate of colorant for UV from the melting device 11 can have its UV absorber content increased. In other words, when considering two inks 103, one ink 103 has a lower absorption rate of colorant 107 for UV from the melting device 11 compared to the other ink 103, and one ink 103 has a higher UV absorber content compared to the other ink 103. In this case, the other ink 103 may also contain no UV absorber at all. The absorption rate can be, for example, absorbance, or a value obtained by dividing absorbance by the length of the UV-incident sample (ink) (absorption coefficient). The UV absorption rate of the colorant 107 in ink 103 can be, for example, the absorption rate of a sample containing colorant 107 at the same content as the colorant 107 in ink 103, where the remainder (e.g., medium 105) substantially does not absorb UV, or the UV absorption rate of ink 103 in a modified example where the UV absorber is replaced by the same mass of medium 105. The absorption rate can be determined using a known spectrophotometer. When the ink group has the structure described above, the heat generated by UV from the melting device 11 can be made more similar among various inks 103.

[0278] It should be noted that when the wavelength range of the UV emitted by the melting device 11 is relatively wide, the "UV from the melting device 11" when comparing the absorptivity of UV as described above can be, for example, a UV with a representative wavelength within the aforementioned wavelength range. An appropriate wavelength can be used as the representative wavelength. For example, for the UV emitted by the melting device 11, consider a spectrum with wavelength on the horizontal axis and energy on the vertical axis. In this case, the representative wavelength can be the center wavelength of the wavelength range where a meaningful energy level is obtained (the center between the lower and upper limit wavelengths), the wavelength where the peak energy is obtained, or the wavelength whose integral value is divided into a short-wavelength side and a long-wavelength side when integrating the energy over the wavelength range where a meaningful energy level is obtained.

[0279] Figure 12B This is a schematic diagram showing an ink assembly containing ink 103 with added UV absorber as described above.

[0280] To simplify the illustration, only the medium 105, colorant 107, and UV absorber 113 are shown in the composition of ink 103; the fixing polymer 109 and other components are omitted. In the diagram, K, C, Y, and M correspond to black, cyan, yellow, and magenta, respectively.

[0281] The illustrated example assumes the use of Figure 12AThe UV light has a wavelength λ1. Furthermore, the black ink 103, which generates the most heat at wavelength λ1, does not contain UV absorber 113. On the other hand, the cyan ink 103 contains UV absorber 113. Additionally, the yellow and magenta inks 103, which generate the least heat at wavelength λ1, contain more UV absorber 113 than the cyan ink 103.

[0282] Figure 13A This is a schematic diagram illustrating an example of the light absorption characteristics of UV absorber 113. The horizontal and vertical axes of this diagram are aligned with... Figure 12A The horizontal and vertical axes are the same.

[0283] As shown in the figure, the UV absorber 113, for example, has a peak where the absorbance increases. This peak converges approximately within the range RU. That is, the UV absorber 113 generates more heat from UV, while having less impact on visible light (visual confirmation of ink 103). For example, the absorbance in the range RV (e.g., its maximum value) is less than 10% or less, or less than 5%, relative to the peak absorbance or the absorbance at the wavelength (wavelength λ1) of the UV light from the melting device 11.

[0284] Figure 13B This is a schematic diagram illustrating an example of the light absorption characteristics of a modified ink 103 (ink 103 with added UV absorber 113). The horizontal and vertical axes of this diagram are parallel to... Figure 12A The horizontal and vertical axes are the same. Additionally, lines LY, LM, LC, and LK are... Figure 12A Similarly, it corresponds to the four colors.

[0285] In this diagram, as shown in the reference Figure 12B As explained, by adding with Figure 13A The UV absorber 113, as shown, ensures that the absorbance (or absorptivity) of the melting device 11 at the UV wavelength (wavelength λ1) is equal across multiple colors. For example, at wavelength λ1, the difference in absorptivity among all colors (the difference between the highest and lowest absorptivity) is less than 50%, less than 20%, or less than 10% of the highest absorptivity. It should be noted that in modified ink sets, the difference in absorptivity at wavelength λ1 can be reduced to some extent by adding the UV absorber 113 between at least two colors of ink 103. That is, it can also be as follows... Figure 13B As in the example, the absorption rate of wavelength λ1 is not equal for all colors.

[0286] The structure of UV absorber 113 can be suitable. For example, UV absorber 113 can be used to protect polymers or colorants, or in cosmetics. Examples of such UV absorbers include dihydroxybenzophenone compounds, benzotriazole compounds, hydroxyphenyltriazine compounds, and cyanoacrylate compounds.

[0287] As described in the description of the first embodiment, the ink ejection device 7 can eject two inks 103 containing different colorants 107. Moreover, as described in this modified example, among the two inks 103, one ink 103 (e.g., Y or M) can reduce the absorption rate of the colorant 107 of UV (UV with wavelength λ1) from the melting device 11 compared to the other ink (e.g., C or K), and can increase the mass of the UV absorber 113 that is different from the colorant 107.

[0288] In this case, for example, when irradiated with UV light of a specified wavelength λ1, the deviation in the amount of heat generated per unit time between the colors of the ink 103 is reduced. Furthermore, the possibility of overheating or underheating occurs in the ink 103 of a particular color is reduced. As a result, fixing of the ink 103 onto the printed object 101 is performed stably, for example, regardless of the content (color scheme) of the image on the printed object 101.

[0289] The technology of the present invention is not limited to the above-described embodiments, and can be implemented in various ways.

[0290] The printed material is not limited to a long strip, nor is it limited to being conveyed by rollers. For example, the printing apparatus may also convey the material to be printed by placing it on a conveyor belt. In this case, the printed material may be, for example, a sheet of paper, a cut piece of cloth, wood, or tile.

[0291] Printing apparatus is not limited to having a conveying device that moves the printed material. In other words, the concepts of "the conveying direction of the printed material," "upstream in the conveying direction," and "downstream in the conveying direction" may not apply. For example, the printing apparatus can move various devices (drying devices, ink ejection devices, melting devices, and / or auxiliary melting devices) while the printed material is stationary. Specifically, for example, printing can be performed while a robot moves the ink ejection device along the surface of the printed material. Moreover, the medium can be evaporated by a warm air dryer equipped with or transported by a robot before the ink ejection device approaches the printed material or after the ink ejection device retracts. The fixing polymer can also be melted by a robot bringing the melting device close to the surface of the printed material after the ink ejection device retracts. In this manner, for example, not only two-dimensional printing can be performed, but three-dimensional printing can also be performed by moving the ink ejection device along the surface of the printed material, which has a three-dimensional shape. In addition, the conveying of the printed material and the movement of various devices can be combined. According to the implementation method, the "conveying direction of the printed material" can also be replaced by the "relative movement direction" between the printed material and various devices.

[0292] The drying apparatus is not limited to heated rollers and warm air dryers. For example, the drying apparatus may also heat the printed material by irradiating it with infrared rays. As mentioned in the description of the embodiments, the drying apparatus is not limited to the upstream and downstream side of the ink ejection device in the conveying direction of the printed material, and may also be located at the same position as the ink ejection device. For example, the drying apparatus may have a plate-shaped heater that is positioned opposite the ink ejection device across the printed material and abuts against the back of the printed material.

[0293] In this embodiment, a second drying device is selectively provided between the ink ejection device and the melting device. Figure 9 17B and Figure 11 455A and 455B), and an auxiliary melting device positioned opposite the melting device across the printed material ( Figure 1 17B and Figure 10 (17B). However, a second drying device and an auxiliary melting device can also be provided on both sides.

[0294] Explanation of reference numerals in the attached figures:

[0295] 1... Printing apparatus; 7... Ink ejection apparatus; 9... Drying apparatus; 11... Melting apparatus; 101... Printed material; 103... Ink; 105... Medium; 109... Fixing polymer.

Claims

1. A printing apparatus, wherein, The printing apparatus has: An ink ejection device that causes ink containing a medium and a fixing polymer to adhere to the printed material; A drying apparatus that promotes the evaporation of the medium by heating the printed material; and A melting device that heats the ink adhering to the printed material by irradiating it with ultraviolet light, thereby melting the fixer polymer and fixing the ink onto the printed material. The drying apparatus heats the printed material to a temperature lower than the glass transition temperature of the fixer polymer. The melting device heats the ink adhering to the printed material to a temperature above the glass transition temperature of the fixer polymer. The ink contains a first polymer that is different from the fixer polymer. The drying apparatus heats the printed material to a temperature above the glass transition temperature of the first polymer but below the glass transition temperature of the fixer polymer.

2. The printing apparatus according to claim 1, wherein, The melting device is located downstream of the drying device in the conveying direction of the printed material.

3. The printing apparatus according to claim 1, wherein, The melting device melts the fixing polymer after the drying device evaporates the medium.

4. The printing apparatus according to claim 1, wherein, The amount of heat applied to the printed material by the drying device, the relative position of the drying device and the melting device, and the conveying speed of the printed material are determined in such a manner that the evaporation of the medium by the drying device is completed before the melting of the fixing polymer by the melting device begins.

5. The printing apparatus according to claim 1, wherein, The printing apparatus has an auxiliary melting device located on the opposite side of the printable material, which heats the printable material from the back side of the side with the ink attached to assist in the melting of the fixer polymer.

6. The printing apparatus according to claim 5, wherein, The auxiliary melting device has a heating surface that is controlled to maintain a predetermined temperature while contacting the back side of the workpiece to be printed. The melting device heats the ink adhering to the printed material to a temperature higher than the specified temperature.

7. The printing apparatus according to claim 1, wherein, The drying apparatus includes: a first drying device disposed upstream of the ink ejection device in the transport direction of the printed material; and a second drying device disposed downstream of the ink ejection device in the transport direction of the printed material. The melting device is located downstream of the second drying device.

8. The printing apparatus according to claim 1, wherein, The printing apparatus includes a conveying device that conveys the printable material while bending at least a portion of it so that the surface with the ink adhering to it protrudes. The melting device irradiates the portion of the printed material that is bent by the conveying device with ultraviolet light.

9. The printing apparatus according to claim 1, wherein, The printing apparatus has multiple light sources, which constitute one or more of the melting devices, and irradiate ultraviolet light of different wavelengths.

10. The printing apparatus according to claim 1, wherein, The drying device causes the first and second portions of the printed material to alternately and repeatedly come into contact with the printed material.

11. The printing apparatus according to claim 1, wherein, The drying apparatus includes a first drying device, which is located upstream of the ink ejection device in the conveying direction of the printed material. The heating amount of the first drying device, the relative position of the first drying device and the ink ejection device, and the conveying speed of the printed material are determined by the temperature of the portion of the printed material that will be opposite the ink ejection device being above the glass transition temperature of the first polymer and below the glass transition temperature of the fixer polymer.

12. The printing apparatus according to claim 1, wherein, The drying device is located upstream of the melting device in the conveying direction of the printed material. The heating amount of the drying device, the relative position of the drying device and the melting device, and the conveying speed of the printed object are determined in such a way that the temperature of the printed object is above the glass transition temperature of the first polymer and below the glass transition temperature of the fixer polymer in the region from immediately behind the drying device to immediately in front of the portion opposite the melting device.

13. The printing apparatus according to claim 1, wherein, The first polymer is a dispersant polymer.

14. The printing apparatus according to any one of claims 1 to 13, wherein, Of the polymers contained in the ink, the fixer polymer has the highest glass transition temperature.

15. The printing apparatus according to claim 1, wherein, The ink ejection device ejects at least two inks containing different colorants. In the two inks, the content of ultraviolet absorbers, which are different from the colorants, is different.

16. The printing apparatus according to claim 15, wherein, In the two inks, the colorant contained in one ink has a lower absorption rate of ultraviolet light from the melting device compared to the colorant contained in the other ink, and the ultraviolet absorber content in one ink is higher than that in the other ink.

17. The printing apparatus according to claim 15, wherein, In the two inks, the colorant in one ink has a lower absorption rate of ultraviolet light from the melting device compared to the other ink, and the ultraviolet absorber content in one ink is higher than that in the other ink.

18. A printing method, comprising: This allows the ink, containing the medium and fixer polymer, to adhere to the printed material. The evaporation of the medium is promoted by heating the printed material; as well as The ink adhering to the printed material is heated by irradiating it with ultraviolet light, thereby melting the fixer polymer and fixing the ink onto the printed material. The printed material is heated to a temperature lower than the glass transition temperature of the fixer polymer. The ink adhering to the printed material is heated to a temperature above the glass transition temperature of the fixer polymer. The ink contains a first polymer that is different from the fixer polymer. The printed material is heated to a temperature above the glass transition temperature of the first polymer but below the glass transition temperature of the fixer polymer.

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