Incremental printing of symbolic information – Ink jet – Medium and processing means
Reexamination Certificate
2002-02-25
2003-05-20
Gordon, Raquel Yvette (Department: 2853)
Incremental printing of symbolic information
Ink jet
Medium and processing means
Reexamination Certificate
active
06565204
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an image-forming method using a print medium and a transfer sheet film, for thermally transferring an image printed by using a sublimable dye ink from the transfer sheet film onto the print medium, to thereby form the image on the print medium, and the transfer sheet film used therefor, as well as to an image-forming apparatus.
2. Prior Art
Conventionally, an image-forming method is known which transfers an image printed on a transfer paper by using a sublimable dye ink by one of various printing methods from the transfer paper to a print medium. This image-forming method overlays a printing surface of the transfer paper to a transfer surface of the print medium, heating the transfer paper and the print medium while applying pressure thereto e.g. by using a thermal press, thereby causing the sublimable dye ink held in the transfer paper to permeate from the printing surface of the transfer paper in a direction of thickness thereof into the transfer surface of the print medium through evaporation/diffusion to effect image transfer. Then, after completion of the image transfer, the transfer paper is peeled off the print medium.
In general, to transfer a high-quality image printed on a transfer paper onto a print medium while maintaining the high quality of the image, it is essential to press the transfer paper and the print medium against each other for intimate contact there between during the image transfer operation. However, the transfer paper has too coarse a printing surface to achieve complete and intimate contact with the print medium, so that minute gaps are produced between the transfer paper and the print medium, resulting in a transferred image with color irregularity. On the other hand, if a transfer sheet having a smooth and solid surface is used to overcome the problem, since the transfer sheet has no elasticity differently from the transfer paper described above, it is difficult to cause air to be expelled from between the surfaces of the transfer sheet and a print medium held in intimate contact with each other. Therefore, in this case as well, it is expected to produce a transferred image with color irregularity.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an image-forming method which is capable of improving image quality of a transfer image, and a transfer sheet film therefor, as well as an image-forming apparatus.
To attain the above object, according to a first aspect of the invention, there is provided an image-forming method comprising the steps of:
printing an image on a printing surface of at least one sheet of a transfer sheet film prepared in a manner associated with at least one surface of a print medium, by using a sublimable dye ink, thereby causing the sublimable dye ink to be held in the at least one sheet of the transfer sheet film;
overlaying the at least one sheet of the transfer sheet film to the print medium such that the printing surface of the at least one sheet of the transfer sheet film faces the at least one surface of the print medium;
transferring the image by heating the at least one sheet of the transfer sheet film and the print medium overlaid to each other while applying pressure thereto, thereby causing diffusion of the sublimable dye ink held in the at least one sheet of the transfer sheet film into the at least one surface of the print medium for color development; and
removing the at least one sheet of the transfer sheet film from the print medium having the image formed thereon,
wherein the transfer sheet film is formed of a water-soluble and soft resin material, and the printing surface is formed to be a smooth surface.
According to the image-forming method, when an image is printed on the transfer sheet film, the sublimable dye ink is impregnated into the transfer sheet film and held in the same. Then, the transfer sheet film and the print medium are overlaid to each other such that the printing surface of the transfer sheet film faces the surface of the print medium, and then heated in this state, whereby the sublimable dye ink is transferred from the transfer sheet film deep into the surface layer of the print medium as migration particles having sizes at a molecular level and develops color to form an image thereon. Then, simply by removing the transfer sheet film from the print medium thereafter, the print medium having the image easily formed on the surface thereof is prepared.
In the present image-forming method, since the transfer sheet film formed of a water-soluble resin material is employed as a transfer medium, it is possible to maintain excellent ink absorbency during the printing process, which enables the sublimable dye ink to be stably impregnated into the transfer sheet film and held therein without being diffused. Therefore, when the transfer sheet film is heated in a state overlaid to the print medium with its printing surface facing the same, the sublimable dye ink is transferred directly onto the surface of the print medium without passing through the transfer sheet film or being hindered by air or the like trapped between the transfer sheet film and the print medium, so that the print image can be transferred faithfully. Further, since the printing surface of the transfer sheet film has smoothness, and the transfer sheet film is formed of a soft resin, when the transfer sheet film is pressed against the print medium, air trapped between the transfer sheet film and the print medium can be expelled easily, which ensures as intimate contact as possible between the transfer sheet film and the print medium. This makes it possible to form a clear and sharp transfer image without color irregularity on the print medium. It should be noted that the transfer sheet film is preferably formed of a material composed of a main component of PVA (polyvinyl alcohol) and an additive which exhibits slight tackiness when heated.
Preferably, the printing step includes printing images on respective printing surfaces of two sheets of the transfer sheet film prepared in a manner associated with front and back surfaces of the print medium, by using the sublimable dye ink, thereby causing the sublimable dye ink to be held in the two sheets of the transfer sheet film, the overlaying step including overlaying the two sheets of the transfer sheet film to the print medium such that the printing surfaces of the two sheets of the transfer sheet film face the front and back surfaces of the print medium, respectively, the transferring step including transferring the images by heating the two sheets of the transfer sheet film and the print medium overlaid to each other while applying pressure thereto, thereby causing diffusion of the sublimable dye ink held in the two sheets of the transfer sheet film into the front and back surfaces of the print medium for color development, and the removing step including removing the two sheets of the transfer sheet film from the print medium having the images formed thereon.
According to this preferred embodiment, an image is printed on each sheet of the transfer sheet film, whereby the sublimable dye ink is impregnated into the sheet of the transfer sheet film and held in the same. Then, the two sheets of the transfer sheet film and the print medium are overlaid to each other such that the respective printing surfaces of the two sheets of the transfer sheet film face the front and back surfaces of the print medium, and then heated in this state, whereby the sublimable dye ink is transferred from the sheets of the transfer sheet film deep into each surface layer of the print medium as migration particles having sizes at a molecular level and develop color to form an image thereon. Then, simply by removing the transfer sheet film from the print medium, the print medium having the images easily formed on the front and back surface thereof is prepared.
Therefore, this preferred embodiment provides the same advantageous effects as described above, and is capable of forming clear and sharp transferred
Matsuhashi Kunihiko
Ogawa Ayao
Gordon Raquel Yvette
Hogan & Hartson LLP
Seiko Epson Corporation
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