Incremental printing of symbolic information – Ink jet – Medium and processing means
Reexamination Certificate
2002-03-12
2003-05-13
Pham, Hai (Department: 2853)
Incremental printing of symbolic information
Ink jet
Medium and processing means
C347S103000, C347S102000, C347S100000, C347S105000
Reexamination Certificate
active
06561645
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image forming process, to which a thermal transfer method is applied, and an image forming apparatus.
2. Description of the Related Art
A method for forming an image on a transfer material, such as paper or a film, includes a thermal transfer method. In the thermal transfer method, a transfer body (transfer sheet), which contains a support and a transfer layer comprising a pigment based dye as a transfer material, is superposed on an image receiving body (an image receiving sheet) such as paper or a film. The superposed bodies are heated imagewisely from the side of the support of the transfer sheet with, for example, a thermal head or a laser head. Due to the heat, the pigment-based dye is transferred to the image receiving sheet to form an image on the image receiving sheet. In another embodiment of the thermal transfer method, a dye provided on a transfer body is transferred to an image receiving sheet due to sublimation of the dye caused by heating.
In the thermal transfer method, those using a thermal head for imagewise heating has such a problem that the distribution of a provided temperature is liable to be nonuniform due to variation of the resistance value of the head, and as a result, an image thus formed suffers unevenness. Further, because high temperature heating is locally carried out with the thermal head only on image portions, such a problem occurs that the support on the heated portions is deformed to get wrinkled. On the other hand, in order to improve uniformity of an image, heating in the thermal transfer method can be carried out with laser light. However, it has problems such that a device for irradiating a laser light or the like is very expensive, and materials such as a dye tend to be decomposed by instantaneous local heating by high temperatures to cause unevenness on an image thus formed.
In contrast to the aforementioned image forming methods, there is a non-contact type image forming method that exerts no influence on an image receiving sheet and a coloring material which forms an image. The method includes an ink-jet method, in which an ink is discharged as droplets to form an image. Type of the ink-jet method includes various types, such as a piezo type, a thermal type and a hertz type, which are described in detail in Journal of Imaging Science and Technology, vol. 42, No. 1 (1998), U.S.A. The piezo type method will be described herein after. In the piezo type ink-jet method, plural nozzle holes with ink heads arranged in parallel, independent discharge chambers interconnected with the nozzle holes and each having a diaphragm as a part of walls, piezoelectric elements attached on the diaphragms and a common ink cavity which supplies an ink to the discharge chambers are comprised. A pulse voltage is applied to the piezoelectric elements in accordance with image information to discharge ink droplets from the nozzle holes, whereby an image is formed on an image receiving sheet.
The ink-jet method dose not involves problems such as the deformation of the support and the deterioration of the coloring material as described above. However, in order to prevent clogging of the nozzle with the ink and form uniform ink droplets in a stable manner, a number of restrictions in property of ink liquid and materials used for forming an image are required. That is, the materials for forming an image cannot be freely selected. Therefore, in the case where a color image is required to be formed, it is necessary to select particular dyes or pigments to prevent clogging of nozzles. Consequently, the hue reproducibility in images is limited, and therefore the method cannot be applied to, for example, a printer for high precision proof printing, which is required to reproduce the same hue on an image receiving sheet as a ink pigment used for printing. Furthermore, the problem of nozzle clogging caused after neglect of a long period of time still remains even when particular image forming materials which are selected carefully are used. There is a further problem that an image thus formed by the ink-jet method is poor in light resistance and water resistance, and the dye is liable to be bled on the image receiving sheet.
Japanese Patent Application Laid-Open (JP-A) No.11-70633 discloses an example of an image forming method, to which the ink-jet method is applied. In this method, droplets of a crosslinking agent are imagewisely applied to a recording layer which is formed with a crosslinkable material by an ink-jet device. An applied portion of the recording layer is hardened by crosslinking, and a non-crosslinked portion of the crosslinkable material is then removed by washing to form an image portion. This method is a method to form a so-called screen printing plate by using the ink-jet, followed by forming an image by using a colored ink with the plate. It is completely different from the transfer method of the present invention since it contains two steps, plate making and printing. Further, the method involves a problem of processing of waste liquids after washing because a developing step is necessary upon plate making, whereby complicated steps are required.
Additionally, a transfer ink-jet system is proposed, for example, in JP-A No.5-42755, in which an image is formed on an image carrying member with a recording liquid which contains a liquid and a coloring agent by an ink-jet recording system, and the image is transferred to a transfer material. In this transfer ink-jet method, an image containing a coloring agent is once formed on an image carrying member on, for example, a drum by ordinary ink-jet method, and then the image is then transferred to the transfer material. Therefore, this method is different from the present invention and involves the same problems as in the ordinary ink-jet methods, i.e., the restriction of coloring materials and the clogging of nozzles. Furthermore, the method provides only an image that is liable to be bled and is of low resolution.
An image forming method utilizing an ink-jet method using a transfer medium is described in JP-A No.7-145576. In this method, an ink-jet ink is spotted imagewisely on a transfer medium having a liquid-reactive resin layer as an uppermost layer by an ink-jet recording device. Therefore, the transfer medium is closely attached to an image supporting body (such as cloth), and heat and pressure are applied thereto, so as to transfer image portions. It is such an image forming method that is particularly possible to textile-print on cloth. For example, in the case where the ink is an aqueous ink, the liquid-reactive resin layer is formed with a water soluble resin, and when an ink droplet is spotted thereon, the resin on the spotted portion is dissolved to have cohesiveness (adhesiveness). Owing to the cohesiveness, transfer occurs only on the spotted portion by the heat and pressure. Therefore, high precision image formation becomes possible on cloth by using the ink-jet method. However, this method particularly targets cloth as an image carrying member, and still uses the ink-jet method. Accordingly, it involves the same problems as in the ordinary ink-jet methods, i.e., the restriction of coloring materials and the clogging of nozzles. Furthermore, it also involves such a problem that transfer of the resin layer cannot be carried out uniformly to cause unevenness.
Moreover, JP-A No.62-117782 describes the following image forming method. In the method, a solvent is applied imagewisely to a surface of an image carrying member by an ink-jet discharge system, and then an ink layer is made in contact with the image carrying member, whereby only the part of the ink layer that has been contacted with the imagewise solvent is formed on the image carrying member. However, as described in the right upper column of page 4, lines 7 to 16, of the publication, selection of the solvent is difficult because such a solvent is required that has suitable cohesion and adherence. Furthermore, a synthetic resin film is disclosed
Fuji Photo Film Co. , Ltd.
Pham Hai
Shah Manish S.
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