Patent Publication Number: US-10787003-B2

Title: Treatment-liquid application device, drying device, and liquid discharge apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application is based on and claims priority pursuant to 35 U.S.C. § 119(a) to Japanese Patent Application Nos. 2018-041191, filed on Mar. 7, 2018, and 2019-019535, filed on Feb. 6, 2019, in the Japan Patent Office, the entire disclosure of each of which is incorporated by reference herein. 
     BACKGROUND 
     Technical Field 
     Aspects of the present disclosure relate to a treatment-liquid application device, a drying device, and a liquid discharge apparatus. 
     Related Art 
     As a printing apparatus for applying a liquid to an application target object such as a sheet material to perform printing, there is an apparatus including a drying device to promote drying of the applied liquid. 
     For example, an inkjet recording apparatus is known that includes a dielectric heater as a heater and an apparatus are known that applies a pretreatment liquid containing an infrared absorbing agent and then emitting infrared rays to perform heating, and the like. 
     SUMMARY 
     In an aspect of the present disclosure, there is provided a treatment-liquid application device that includes a treatment liquid applicator to apply a treatment liquid to an application target object to which a black liquid and a color liquid other than the black liquid are applied. The treatment liquid applicator applies a greater amount of the treatment liquid per unit area to at least a region to which the color liquid is applied than a region to which the black liquid is applied. 
     In another aspect of the present disclosure, there is provided a treatment-liquid application device that includes a treatment liquid applicator to apply a treatment liquid to an application target object to which a first liquid and a second liquid are applied, the first liquid including carbon black, the second liquid including no carbon black or a smaller amount of carbon black than the first liquid. The treatment liquid applicator applies a greater amount of the treatment liquid per unit area to at least a region to which the second liquid is applied than a region to which the first liquid is applied. 
     In still another aspect of the present disclosure, there is provided a treatment-liquid application device that includes a treatment liquid applicator to apply a treatment liquid to an application target object to which a black liquid and a color liquid other than the black liquid are applied. The treatment liquid applicator applies a smaller amount of the treatment liquid per unit area to at least a region to which the color liquid is applied than a region to which the black liquid is applied. A drying efficiency of the treatment liquid is lower than a drying efficiency of the black liquid. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The aforementioned and other aspects, features, and advantages of the present disclosure would be better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: 
         FIG. 1  is a schematic explanatory view of a printing apparatus as a liquid discharge apparatus according to a first embodiment of the present disclosure; 
         FIG. 2  is an explanatory plan view of an example of a treatment-liquid head of a treatment-liquid application unit in the printing apparatus; 
         FIG. 3  is a block diagram of portions relating to control of application of a treatment liquid in the treatment-liquid application unit; 
         FIG. 4  is a schematic explanatory view for explaining an action in the first embodiment; 
         FIG. 5  is a schematic explanatory view for explaining an application state of a treatment liquid in a second embodiment of the present disclosure; 
         FIG. 6  is a schematic explanatory view of a printing apparatus as a liquid discharge apparatus according to a third embodiment of the present disclosure 
         FIG. 7  is a schematic explanatory view of a printing apparatus as a liquid discharge apparatus according to a fourth embodiment of the present disclosure; and 
         FIG. 8  is a schematic explanatory view for explaining an application state of a treatment liquid in a fifth embodiment of the present disclosure. 
     
    
    
     The accompanying drawings are intended to depict embodiments of the present disclosure and should not be interpreted to limit the scope thereof. The accompanying drawings are not to be considered as drawn to scale unless explicitly noted. 
     DETAILED DESCRIPTION 
     In describing embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this patent specification is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner and achieve similar results. 
     Although the embodiments are described with technical limitations with reference to the attached drawings, such description is not intended to limit the scope of the disclosure and all of the components or elements described in the embodiments of this disclosure are not necessarily indispensable. 
     Referring now to the drawings, embodiments of the present disclosure are described below. In the drawings for explaining the following embodiments, the same reference codes are allocated to elements (members or components) having the same function or shape and redundant descriptions thereof are omitted below. 
     Hereinafter, embodiments of the present disclosure will be described with reference to the attached drawings. First, a first embodiment of the present disclosure will be described with reference to  FIGS. 1 and 2 .  FIG. 1  is a schematic explanatory view of a printing apparatus as a liquid discharge apparatus according to the first embodiment.  FIG. 2  is an explanatory plan view of an example of a treatment-liquid head of a treatment-liquid application unit in the printing apparatus. 
     A printing apparatus  100  is an inkjet recording apparatus, and includes a printing device  101  for discharging an ink which is a liquid of a required color onto a continuous sheet  110  which is an application target object (a member to be conveyed, a heating target object, or a drying target object) to print an image. 
     In the printing device  101 , liquid discharge heads  111  ( 111 A to  111 D) which are full line type liquid dischargers for four colors are arranged from an upstream side in a conveying direction (arrow direction) of the continuous sheet  110 . The liquid discharge heads  111  discharge an ink of black K (black ink) which is a black liquid and inks of cyan C, magenta M, and yellow Y (color inks) which are color liquids onto the continuous sheet  110 . Note that the type and number of colors are not limited thereto. 
     In the present embodiment, black ink is a first liquid containing carbon black and color ink is a second liquid not containing carbon black. In some embodiments, the second liquid may be a liquid containing a smaller amount of carbon black than the second liquid. 
     Here, each of the inks contains propylene glycol or glycerin. 
     On the upstream side of the printing device  101  in the continuous sheet conveying direction (moving direction), a treatment-liquid application unit  106  constituted by a treatment-liquid application device for applying a treatment liquid to the continuous sheet  110  according to the present embodiment is disposed. The treatment-liquid application unit  106  includes a treatment-liquid head  112  for discharging and applying a treatment liquid to the continuous sheet  110 . 
     The treatment-liquid head  112  as an example of a treatment liquid applicator is constituted, for example, by a full line type head in which a plurality of liquid discharge heads  121  each having a nozzle row  122  for discharging a treatment liquid are arranged in a zigzag manner on a base member  123 . By controlling the discharge amount from the heads  121 , the application amount of the treatment liquid can be changed. 
     Incidentally, as a method for applying a treatment liquid, in addition to the above-described method using the treatment-liquid head  112 , a transfer method using a roller or the like may be used. In the transfer method, a treatment liquid is selectively applied to a roller or the like temporarily, then the roller is brought into contact with a medium, and the treatment liquid can be thereby selectively applied to the medium. 
     The treatment-liquid application unit  106  applies a treatment liquid to a region other than a region to which a black ink is applied by the printing device  101  in an amount larger than that in the region to which the black ink is applied. 
     Here, the treatment liquid contains a solvent for increasing a dielectric constant. The dielectric constant of a liquid can be measured by a coaxial resonance method. Examples of a solvent for increasing a dielectric constant include water, propylene glycol, and glycerin (an inclusion is not limited). 
     On a downstream side of the printing device  101  in the conveying direction, a drier  104  including a heater  114  as a dielectric heating device for heating the continuous sheet  110  to which the treatment liquid and ink have been applied is disposed. The heater  114  heats the continuous sheet  110  by high-frequency dielectric heating. 
     A conveyor  103  for conveying the continuous sheet  110  to the treatment-liquid application unit  106 , the printing device  101 , and the drier  104  is included. The conveyor  103  includes a conveying roller  132  for conveying the continuous sheet  110  fed out from a feeding roll  131 , a conveying guide member  133  for guiding the continuous sheet  110  conveyed in the opposite direction to the treatment-liquid application unit  106  and the printing device  101 , an eject roller  134  for ejecting the continuous sheet  110  toward a winding roll  135  on a downstream side of the drier  104 , and the like. 
     In the printing apparatus  100 , while the conveyor  103  conveys the continuous sheet  110  fed out from the feeding roll  131 , the treatment-liquid application unit  106  applies a treatment liquid to the continuous sheet  110 , the printing device  101  prints a required image on the continuous sheet  110 , the drier  104  dries the continuous sheet  110 , and the continuous sheet  110  is wound by the winding roll  135 . 
     Next, a portion related to control of application of a treatment liquid in the treatment-liquid application unit  106  will be described with reference to the block diagram of  FIG. 3 . 
     A region extractor  501  extracts a region to which a black ink is not to be applied from image data, in other words, a region to which color inks are applied. A discharge amount data creator  502  creates discharge amount data in which the application amount to be applied per unit area to a region to which a black ink is not applied is larger than the application amount per unit area in a region to which a black ink is applied from the extraction result of the region extractor  501 . 
     The head drive controller  503  drives the treatment-liquid head  112  in accordance with the discharge amount data created by the discharge amount data creator  502  to discharge the treatment liquid. At this time, the treatment-liquid application amount per unit area in a region to which a black ink is not applied, in other words, a region to which color inks are applied is larger than the treatment-liquid application amount per unit area in a region to which a black ink is applied. 
     Next, an action in the present embodiment will be described with reference to  FIG. 4 .  FIG. 4  is a schematic explanatory view used for the explanation. 
     In the present embodiment, as illustrated in  FIG. 4 , the treatment-liquid application unit  106  discharges and applies a treatment liquid  200  to a surface (printing surface) of the continuous sheet  110 . The treatment liquid  200  contains a solvent for increasing a dielectric constant as described above. 
     At this time, application control is performed such that the application amount of the treatment liquid  200  per unit area in a region other than a region to which a black ink  201  is applied (here, a region to which a color ink  202  is applied) is larger than the application amount of the treatment liquid  200  per unit area in the region to which the black ink  201  is applied. In other words, the application amount of the treatment liquid  200  per unit area that is applied by a treatment liquid applicator is larger in a region to which color liquid (the color ink  202 ) is applied than a region to which the black ink  201  is applied. 
     Then, the black ink  201  and the color ink  202  are discharged from the liquid discharge head  111  of the printing device  101  onto a printing surface of the continuous sheet  110  to which the treatment liquid  200  has been applied, and an image is printed. The black ink  201  contains carbon black to serve as a conductive ink, and the color ink  202  containing no carbon black serves as a non-conductive ink. Incidentally, in  FIG. 4 , the solvent  203  contained in the inks  201  and  202  is illustrated separately from the inks  201  and  202 . 
     Thereafter, the continuous sheet  110  that has passed through the printing device  101  passes through the drier  104  including the dielectric heater  114  to be heated by dielectric heating. 
     At this time, heating efficiency in the region to which the black ink  201  as a conductive ink has been applied is relatively higher than that in the region to which the color ink  202  has been applied. Therefore, if the application amount of the treatment liquid  200  is constant, in a case where dielectric heating is performed in accordance with the black ink  201 , the region to which the color ink  202  as a non-conductive ink has been applied is heated insufficiently. 
     Therefore, even when the application amount of the treatment liquid  200  containing a solvent for increasing a dielectric constant to be applied to the region to which the color ink  202 , in other words, a solvent having a higher dielectric constant than at least the dielectric constant of the color ink has been applied is increased, and dielectric heating is performed in accordance with the black ink  201 , the region to which the color ink  202  has been applied is also heated sufficiently. 
     This makes it possible to reduce heating unevenness in the region to which the black ink  201  has been applied and the region to which the color ink  202  has been applied. 
     In other words, in the present embodiment, when the treatment liquid  200  is applied to an application target object to which the first liquid containing carbon black and the second liquid not containing carbon black are applied, the treatment liquid  200  is applied with a larger application amount per unit area to at least a region to which the second liquid is applied than to a region to which the first liquid is applied. That is, the application amount of the treatment liquid  200  per unit area that is applied by the treatment liquid applicator is larger in a region to which the second liquid is applied than in a region to which the first liquid is applied. Such a configuration can reduce heating unevenness in the region to which the black ink  201  has been applied and the region to which the color ink  202  has been applied. 
     Next, a second embodiment of the present disclosure will be described with reference to  FIG. 5 .  FIG. 5  is a schematic explanatory view for explaining an application state of a treatment liquid in the second embodiment. 
     In the present embodiment, a treatment liquid  200  is not applied to a region to which a black ink  201  is applied, but the treatment liquid  200  is applied to a region to which a color ink  202  is applied. Also in this configuration, the application amount of the treatment liquid  200  in a region to which the color ink  202  is applied, other than a region to which the black ink  201  is applied, is larger than the application amount (zero) of the treatment liquid  200  in the region to which the black ink  201  is applied. 
     Therefore, as in the first embodiment, it is possible to reduce heating unevenness in the region to which the black ink  201  has been applied and the region to which the color ink  202  has been applied. 
     Next, a third embodiment of the present disclosure will be described with reference to  FIG. 6 .  FIG. 6  is a schematic explanatory view of a printing apparatus as a liquid discharge apparatus according to the third embodiment. 
     In the present embodiment, a treatment-liquid application unit  106  is disposed on a downstream side of a printing device  101  in a conveying direction. 
     Also with such a configuration, it is possible to obtain similar effects to those of the above-described embodiments. 
     Next, a fourth embodiment of the present disclosure will be described with reference to  FIG. 7 .  FIG. 7  is a schematic explanatory view of a printing apparatus as a liquid discharge apparatus according to the fourth embodiment. 
     In the present embodiment, a drier  104  as a drying device according to an embodiment of the present disclosure includes a treatment-liquid application unit  106  which is a treatment-liquid application device according to an embodiment of the present disclosure and a heater  114  which is a heating device. 
     Also with such a configuration, it is possible to obtain similar effects to those of the above-described embodiments. 
     Next, a fifth embodiment of the present disclosure is described with reference to  FIG. 8 .  FIG. 8  is a schematic explanatory view for explaining an application state of a treatment liquid in the fifth embodiment. 
     In the present embodiment, when there is an overlapping application area S 1  in which the color ink  202  and the black ink  201  are applied in an overlapping manner, the overlapping application area S 1  is determined as the region to which the color ink  202  is applied and the application amount of the treatment liquid  200  per unit area is set to be larger than in the region to which only the black ink  201  is applied. 
     In other words, the application amount of the treatment liquid  200  per unit area is set to be larger in the overlapping application area S 1 , to which the first liquid and the second liquid are applied in an overlapping manner, as the region to which the second liquid is applied than in the region to which the first liquid is applied. 
     That is, when no ignition or yellowing of the black ink  201  occurs until the drying of the color ink  202  ends, the treatment liquid  200  can be applied to even a region to which the black ink  201  is applied. In infrared irradiation, the difference from the drying efficiency of the black ink  201  is smaller than in high-frequency dielectric heating, the treatment liquid  200  can be applied to a region to which the black ink  201  is applied. 
     For example, assume that both the application amount of the treatment liquid  200  per unit area and the irradiation amount of energy to be applied per unit area are the same between the region (black region) to which the black ink  201  is applied and the region to which other color ink is applied. In such a case, for example, when the treatment liquid  200  is used in combination with an energy irradiator so that the ratio of drying time is 1:5 between black color and other colors, dot pattern data for applying the treatment liquid  200  is formed to control discharge of the solvent so that the content of the treatment liquid  200  is five times greater in other color region than in black region. 
     In the above-described embodiment, the treatment liquid contains a solvent that increases the dielectric constant. However, in some embodiments, the treatment liquid may contain a solvent that increases the conductivity. For example, water usually contains some kind of ions (although completely pure water has no conductivity) and as an example other than water, glycerin has conductivity although a low value. In high-frequency dielectric heating, conductivity strongly affects heat generation particularly at high frequencies (around 40 MHz), and not only conductivity but also dielectric constant affects heat generation in the band of microwave frequencies (2.45 GHz or more). 
     When the treatment liquid contains a solvent that increases the conductivity, the application amount of the treatment liquid is determined based on the ratio of the conductivity per unit area in the application region of black ink to the conductivity per unit area in the application region of cyan ink after application of the treatment liquid. For example, when the black ink conductivity is 0.06 S/m and the color ink conductivity (for example, cyan ink: 0.05 S/m), no treatment liquid is applied to the application region of black ink and the treatment liquid having a conductivity of 0.07 S/m is applied to the application region of cyan ink at the same amount as the application amount of the cyan ink. 
     The conductivity of the solvent used for the treatment liquid is preferably determined in accordance with the conductivity of a color ink having the lowest conductivity among the color inks. In such a case, the conductivity of the solvent can be appropriately adjusted by setting the amount of treatment liquid to be applied to the region of other color ink to be lower than the amount of treatment liquid applied to the region of the color ink having the lowest conductivity. 
     In addition, the treatment liquid can be determined in consideration of both conductivity and dielectric constant depending on the degree of influence on heat generation. For example, in the above-described band of microwave frequencies (2.45 GHz or higher), it is preferable to use a treatment liquid prepared in consideration of both electric conductivity and dielectric constant. 
     When the treatment liquid is not applied under the black ink, a solvent for increasing the drying efficiency of the color ink region (a solvent having at least one of a higher dielectric constant and a higher conductivity than a dielectric constant and a conductivity, respectively, of the color ink) is used. When the treatment liquid is applied under the black ink, a solvent for increasing the drying efficiency of the black ink region and the color ink region (a solvent having at least one of a higher dielectric constant and a higher conductivity than a dielectric constant and a conductivity, respectively, of each of the black ink and other color inks) is used. 
     Note that the above embodiments are described using an example in which the treatment liquid is a treatment liquid for increasing a dielectric constant, but the treatment liquid may be a treatment liquid for increasing infrared absorption efficiency. In other words, any treatment liquid may be used as long as drying efficiency is improved by energy application. 
     Even when the black ink and the color ink are very high in drying property, it is also conceivable that drying unevenness may occur due to too quick drying of the black ink. In such a case, a treatment liquid can be used that lowers at least one of dielectric constant and conductivity. 
     At this time, the treatment liquid is applied to the region to which the black ink is applied rather than the region where the color ink is applied. 
     When the treatment liquid is not applied under the black ink, a solvent for decreasing the drying efficiency of the color ink region (a solvent having at least one of a lower dielectric constant and a lower conductivity than a dielectric constant and a conductivity, respectively, of the color ink) is used. When the treatment liquid is applied under the black ink, a solvent for decreasing the drying efficiency of the black ink region and the color ink region (a solvent having at least one of a lower dielectric constant and a lower conductivity than a dielectric constant and a conductivity, respectively, of each of the black ink and other color inks) is used. 
     In addition, the above embodiments are described using an example in which the application target object is a continuous sheet, but the present disclosure is not limited thereto. The application target object is not particularly limited as long as being a member to which a treatment liquid is applied by a treatment-liquid application device according to an embodiment of the present disclosure. Examples of the application target object include a continuous body such as a continuous sheet, roll paper, or a web, a cut sheet material, wall paper, and an electronic circuit board sheet such as a prepreg. 
     In a case where a treatment-liquid application target object is subjected to printing, in addition to recording a character such as an ink and an image such as a graphic, an image having no meaning, such as a pattern, may be applied as a liquid such as an ink for the purpose of decoration or the like. 
     In the present application, a liquid to be applied is not particularly limited, but preferably has a viscosity of 30 mPa·s or less at ordinary temperature and ordinary pressure or by heating and cooling. More specific examples of the liquid include a solution, a suspension, and an emulsion containing a solvent such as water or an organic solvent, a colorant such as a dye or a pigment, a functionalizing material such as a polymerizable compound, a resin, or a surfactant, a biocompatible material such as deoxyribonucleic acid (DNA), an amino acid, a protein, or calcium, or an edible material such as a natural dye. These liquids can be used, for example, for an inkjet ink, a surface treatment liquid, a liquid for forming a constituent element of an electronic element or a light-emitting element or an electronic circuit resist pattern, or a three-dimensional modeling material liquid. 
     When a liquid discharge head is used as a treatment liquid applicator, examples of an energy generating source for discharging a liquid include those using a piezoelectric actuator (laminated piezoelectric element and thin film piezoelectric element), a thermal actuators using an electrothermal transducer such as a heat generating resistor, and an electrostatic actuator including a diaphragm and a counter electrode. 
     Incidentally, in printing in the present application, image formation, recording, letter printing, photograph printing, and the like are all synonymous. 
     Numerous additional modifications and variations are possible in light of the above teachings. It is therefore to be understood that, within the scope of the above teachings, the present disclosure may be practiced otherwise than as specifically described herein. With some embodiments having thus been described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the scope of the present disclosure and appended claims, and all such modifications are intended to be included within the scope of the present disclosure and appended claims. 
     Each of the functions of the described embodiments may be implemented by one or more processing circuits or circuitry. Processing circuitry includes a programmed processor, as a processor includes circuitry. A processing circuit also includes devices such as an application specific integrated circuit (ASIC), digital signal processor (DSP), field programmable gate array (FPGA), and conventional circuit components arranged to perform the recited functions.