Incremental printing of symbolic information – Thermal marking apparatus or processes – Having an intermediate medium for transferring ink
Reexamination Certificate
2003-03-10
2004-10-12
Tran, Huan (Department: 2861)
Incremental printing of symbolic information
Thermal marking apparatus or processes
Having an intermediate medium for transferring ink
C347S217000, C428S032790
Reexamination Certificate
active
06803936
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a thermal transfer sheet, a method for image formation, a method for image-formed object formation, and an image-formed object. According to the present invention, an intermediate transfer recording medium comprising a substrate film and a transfer part, comprising at least a receptive layer, provided separably on the substrate film is used, and, at the time of the transfer of the transfer part in the intermediate transfer recording medium onto an object, the transfer of the transfer part onto the object in its nontransfer region, onto which the transfer part should not be transferred, can be avoided without installing any special ancillary tool on an image forming apparatus.
BACKGROUND ART
A thermal transfer method has become extensively used as a simple printing method. In the thermal transfer method, a thermal transfer sheet, comprising a colorant layer provided on one side of a substrate sheet, is put on top of a thermal transfer image-receiving sheet optionally provided with an image-receptive layer. The backside of the thermal transfer sheet is heated image-wise by heating means such as a thermal head to selectively transfer the colorant contained in the colorant layer to form an image on the thermal transfer image-receiving sheet.
Thermal transfer methods are classified into thermal ink transfer (hot melt-type thermal transfer) and thermal dye sublimation transfer (sublimation-type thermal transfer). Image formation by the thermal transfer method is carried out as follows. A thermal transfer sheet comprising a substrate sheet, such as a PET film, and, supported on the substrate sheet, a heat-fusion ink layer, formed of a dispersion of a colorant, such as a pigment, in a binder, such as a hot-melt wax or resin, is first provided. Energy according to image information is then applied to heating means such as a thermal head to transfer the colorant together with the binder onto a thermal transfer image-receiving sheet such as paper or plastic sheets. Images produced by the thermal ink transfer have high density and possess high sharpness and are suitable for recording binary images of characters or the like.
On the other hand, the thermal dye sublimation transfer is a method for image formation which is carried out as follows. A thermal transfer sheet comprising a substrate sheet, such as a PET film, and, supported on the substrate sheet, a dye layer formed of a dye, which is mainly thermally transferred by sublimation and has been dissolved or dispersed in a resin binder, is first provided. Energy according to image information is then applied to heating means such as a thermal head to transfer only the dye onto a thermal transfer image-receiving sheet comprising a substrate sheet, such as paper or a plastic, optionally provided with a dye-receptive layer. The thermal dye sublimation transfer can regulate the amount of the dye transferred according to the quantity of energy applied and thus can form gradation images of which the image density has been regulated dot by dot of the thermal head. Further, since the colorant used is a dye, the formed image is transparent, and the reproduction of intermediate colors produced by superimposing different color dyes on top of each other or one another is excellent. Accordingly, high-quality photograph-like full color images can be formed with faithful reproduction of intermediate colors by transferring different color dyes, such as yellow, magenta, cyan, and black, onto a thermal transfer image-receiving sheet, so as to superimpose the color dyes on top of each other or one another, from a thermal transfer sheet of the different colors.
Thermal transfer image-receiving sheets used with these thermal transfer methods have a wide variety of practical applications. Representative examples of applications include proof sheets, and recording sheets for output images, output plans or designs drawn by CAD/CAM or the like, or images output from a variety of medical analyzers or measuring instruments such as CT scanners and endoscopic cameras. They can also be used as the alternative of instant photographs, and as paper for producing identity certifications, ID cards, credit cards, and other cards on which facial photographs or the like are printed, or for producing synthetic or memorial photographs which are taken at amusement facilities such as recreation parks, game centers, museums, aquariums and the like. The diversification of the applications has led to an increasing demand for the formation of a thermally transferred image on a desired object. A method has been proposed as one method for meeting this demand. In this method, a colorant such as a dye or a pigment is transferred, from a thermal transfer sheet comprising a dye layer or a heat-fusion ink layer, onto a receptive layer in an intermediate transfer recording medium comprising the receptive layer separably provided on a substrate to form an image on the receptive layer. Thereafter, the intermediate transfer recording medium is heated to transfer the receptive layer, with the image formed thereon, onto an object (Japanese Patent Laid-Open No. 238791/1987 or the like).
Since the intermediate transfer recording medium can transfer the receptive layer onto an object, this method is preferably used, for example, for objects, onto which a colorant is less likely to be transferred, making it impossible to form high-quality images directly on them. Further, this method is preferably used for objects which are likely to be fused to the colorant layer at the time of thermal transfer. Therefore, the intermediate transfer recording medium can be advantageously used for the preparation of passports or other identity certifications, credit cards/ID cards, or other prints.
For some cards, an IC chip part, a magnetic stripe part, an antenna part for transmission/reception, a signature part or the like exists on an identical surface on which the receptive layer is to be transferred. These parts are a region where covering with the receptive layer transferred from the intermediate transfer recording medium adversely affects the function of this region.
On the other hand, for example, Japanese Patent Laid-Open Nos. 272849/1998 and 143831/1994 disclose a method and apparatus for image formation wherein a releasable ink is previously transferred onto an intermediate transfer recording medium to allow a receptive layer (an image layer) to lose its adhesion and thus to prevent the transfer of the image layer onto an object in its nontransfer region.
In the above method for image formation, however, the transfer of the receptive layer (image layer) onto an object in its nontransfer region (for example, an IC chip part or a signature part) cannot be fully prevented without difficulties. To overcome this drawback, for example, a sticking-and-removing mechanism for removing an unnecessary receptive layer adhered to the object has been installing on an image forming apparatus.
Unlike the conventional image forming apparatus, however, an apparatus for the sticking-and-removing mechanism or the like is a special apparatus, and the provision of this apparatus disadvantageously incurs very high cost.
Accordingly, it is an object of the present invention is to solve the above problems of the prior art and to provide a method for image formation and a thermal transfer sheet for use in said method, wherein an intermediate transfer recording medium comprising a substrate film and a transfer part, comprising at least a receptive layer, provided separably on the substrate film is provided, and, at the time of the transfer of the transfer part in the intermediate transfer recording medium onto an object, the transfer of the transfer part onto the object in its nontransfer region, onto which the transfer part should not be transferred, can be avoided without installing any special ancillary tool on an image forming apparatus.
SUMMARY OF THE INVENTION
The above object of the present invention can be attained by a thermal transfer sheet adapted for the formation of a
Kita Tatsuya
Masuda Kazuhiro
Odaka Tsuaki
Oshima Katsuyuki
Sakamoto Kenji
Dai Nippon Printing Co. Ltd.
Parkhurst & Wendel L.L.P.
Tran Huan
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