Printing apparatus and printing method

Abstract

To suppress the risk of ink bleeding and thereby attain an improved printing quality, a printing apparatus is provided that carries out an inkjet printing operation for a medium. The printing apparatus includes inkjet heads that eject droplets of ink using inkjet technique; and ultraviolet light sources that radiate ultraviolet light. The ink ejected from the inkjet heads contains an ultraviolet absorbent that absorbs ultraviolet light, and a solvent that dissolves or disperses the ultraviolet absorbent. The ejected ink is adherable to the medium and fixable by evaporating the solvent. The ultraviolet light sources irradiate the ink adhered to the medium with ultraviolet light so as to volatilize and remove at least part of the solvent from the ink.

1 . A printing apparatus that carries out a printing operation for a medium by an inkjet scheme, the printing apparatus comprising:
 an inkjet head that ejects a droplet of an ink by the inkjet scheme; and   an ultraviolet light source that radiates an ultraviolet light,   wherein   the inkjet head adheres the ink onto the medium by discharging ink droplets of the ink containing an ultraviolet absorbent that absorbs ultraviolet light and generates heat and a solvent that dissolves or disperses the ultraviolet absorbent,   the ink is fixed to the medium by evaporating the solvent and contains a resin component, and the inkjet head comprises a plurality of inkjet heads that eject the ink comprises inks of a plurality of different colors,   wherein the ultraviolet light source irradiates the inks of the plurality of colors immediately after landing on the medium with the ultraviolet light to generate heat from the ultraviolet absorbent for volatilizing and removing at least a part of the solvent contained in the inks of the plurality of different colors.   
     
     
         2 . The printing apparatus as set forth in  claim 1 , wherein
 the ultraviolet light source irradiates the ink with the ultraviolet light that volatizes and removes the solvent until termination of ink bleeding in the inks of the plurality of different colors.   
     
     
         3 . The printing apparatus as set forth in  claim 1 , wherein
 the ultraviolet light source radiates the ultraviolet light toward the ink on outside of a region of the medium facing the inkjet head.   
     
     
         4 . The printing apparatus as set forth in  claim 1 , wherein
 the ultraviolet light source heats the ink by radiating the ultraviolet light so that a continuous irradiation time for a position on the medium is smaller than a thermal time constant of heat dissipation from the medium.   
     
     
         5 . The printing apparatus as set forth in  claim 1 , further comprising:
 a heater for heating the medium,   wherein the ultraviolet light source irradiates the ink on the medium heated by the heater with the ultraviolet light, and   the ultraviolet light source, in combination with the heater, volatilizes and removes at least part of the solvent included in the ink.   
     
     
         6 . The printing apparatus as set forth in  claim 1 , wherein the ink comprises 0.05 wt. % to 2 wt. % of the ultraviolet absorbent. 
     
     
         7 . The printing apparatus as set forth in  claim 1 , wherein
 the ultraviolet absorbent is one selected from benzotriazole-based ultraviolet absorbents, liquid ultraviolet absorbents, triazine-based ultraviolet absorbents, benzophenone-based ultraviolet absorbents, benzoate-based ultraviolet absorbents, and benzimidazole-based ultraviolet absorbents.   
     
     
         8 . The printing apparatus as set forth in  claim 1 , wherein
 the ultraviolet light source is a light source using a semiconductor that generates the ultraviolet light.   
     
     
         9 . The printing apparatus as set forth in  claim 1 , wherein
 the medium has absorbency for the ink before the solvent is volatilized and removed.   
     
     
         10 . The printing apparatus as set forth in  claim 1 , wherein
 the medium is a fabric medium, and   the printing apparatus carries out the printing operation for both surfaces of the medium.   
     
     
         11 . The printing apparatus as set forth in  claim 10 , wherein
 the ink comprises a pigment as colorant.   
     
     
         12 . The printing apparatus as set forth in  claim 10 , wherein
 the ink comprises a dye as colorant.   
     
     
         13 . The printing apparatus as set forth in  claim 12 , wherein
 the ink further comprises an auxiliary agent that assists color development of the dye.   
     
     
         14 . The printing apparatus as set forth in  claim 12 , further comprising:
 an inkjet head that ejects a droplet of an ink comprising an auxiliary agent that assists color development of the dye.   
     
     
         15 . A printing method for carrying out a printing operation for a medium by an inkjet scheme, the printing method comprising:
 using an inkjet head that ejects a droplet of an ink by the inkjet scheme; and   using an ultraviolet light source that radiates an ultraviolet light,   wherein   the ink comprises an ultraviolet absorbent that absorbs the ultraviolet light, and a solvent that dissolves or disperses the ultraviolet absorbent, the ink is adhered onto the medium,   the ink is fixed to the medium by evaporating the solvent and, the ink comprises a resin component,   wherein the ink comprises inks of a plurality of different colors discharged from the inkjet head,   wherein the ultraviolet light source irradiates the inks of the plurality of different colors immediately after landing on the medium with the ultraviolet light to generate heat from the ultraviolet absorbent for volatilizing and removing at least a part of the solvent contained in the inks of the plurality of different colors.