Record receiver having plural interactive leaves or a colorless – Having plural interactive leaves
Reexamination Certificate
1998-10-15
2002-04-02
Hess, Bruce H. (Department: 1774)
Record receiver having plural interactive leaves or a colorless
Having plural interactive leaves
C428S195100, C428S913000, C428S914000, C427S152000
Reexamination Certificate
active
06365546
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a thermal transfer image receiving sheet for use in a thermal transfer system wherein a thermal transfer image receiving sheet is superposed on a thermal transfer sheet and a colorant is thermally transferred from the thermal transfer sheet onto the thermal transfer image receiving sheet to form an image on the thermal transfer image receiving sheet, and a process for producing the same. More particularly, the present invention relates to a thermal transfer image receiving sheet capable of preventing misregistration which is likely to occur in the formation of an image on a thermal transfer image receiving sheet, and a process for producing the same.
Formation of letters or images on an object by a thermal transfer system has hitherto been carried out in the art. A thermal dye transfer system (a thermal sublimation transfer system) and a thermal ink transfer system (a hot melt transfer system) have been extensively used as the thermal transfer system. The thermal dye transfer system is such that a sublimable dye is used as a colorant, and the dye in a sublimable dye layer provided in a thermal transfer sheet is thermally transferred onto an object, such as a thermal transfer image receiving sheet, by means of a heating device, such as a thermal head, wherein generation of heat is regulated according to image information, thereby forming an image on the object.
In the thermal dye transfer system, the amount of the dye transferred can be regulated for each dot by heating in very short time. The image thus formed is very sharp, because the colorant used is a dye, and, at the same time, is highly transparent. Therefore, the image has excellent halftone reproduction and gradation, high definition, and high quality comparable to that of full-color photographic images using a silver salt.
By virtue of development of various hardwares and softwares associated with multimedia, the thermal transfer system has found an expanded market as a full color hard copy system of digital images, including computer graphics, still pictures by satellite communication, and CDROM, and analog images, such as video images.
Specific applications of the thermal transfer image receiving sheet in the thermal transfer system are various, and representative examples thereof include proof printing, output of an image, output of a design, such as CAD/CAM, output applications for various medical instruments for analysis, such as CT scan and endoscope cameras, output applications for measuring equipment, alternatives for instant photography, output of photograph of a face to identification (ID) cards, credit cards, and other cards, and applications in composite photographs, pictures for keepsake, and picture postcards in amusement facilities, such as pleasure grounds, game centers, museums, aquariums, and the like.
One of the methods for forming an image in the thermal transfer system is to superimpose colors on top of each other or one another side by side. In this method, a color image is formed for each image face. Therefore, the thermal transfer image receiving sheet is reciprocated, and an image is transferred one color by one color from the thermal transfer sheet being successively wound in one direction to put colors on top of each other or one another. According to this method, advantageously, image printing speed is high, and there is no overlapping between lines experienced in the serial process. Therefore, a good image can be formed so far as the positioning accuracy is high. This method, however, suffers from problems including that, due to the nature of reciprocation of the thermal transfer image receiving sheet, the paper positioning accuracy is so low that the so-called misregistration is likely to occur, and, in addition, it is difficult to realize a reduction in size and cost of the image printer.
The following several printers have hitherto been proposed for use in the above method.
For example, one of them is a printer wherein the thermal transfer image receiving sheet is fastened in its one end with a chuck and in this state is reciprocated. In this printer, since the thermal transfer image receiving sheet is reciprocated using an independent chuck, the carrying accuracy is high. The printer can easily form an image on a thermal transfer image receiving sheet having a relatively large size, for example, a thermal transfer image receiving sheet of A3 size or larger. This printer, however, is disadvantageous in that the mechanism is complicated and, hence, the size of the printer should be increased, it is difficult to form an image on a thermal transfer image receiving sheet of small size, and the price of the printer is high.
Another printer is one wherein one end of the thermal transfer image receiving sheet is fixed to and wound on a chuck provided on the surface of a platen roller and reciprocated by rotation of the platen roller. Before carrying accuracy is discussed, this type of printer has a drawback that, when the thermal transfer image receiving sheet is delivered, it is likely to be jammed within the printer.
Still another printer is one wherein the thermal transfer image receiving sheet is fastened with a grip roller comprising a rubber roller and a metallic roller and reciprocated by utilizing the rotation of the roller. By virtue of a simple structure of this type of printer, the size thereof can be reduced, and the price of the printer is low. For this reason, at the present time, this printer has been most extensively used in the art.
In this printer, the grip roller comprises: a rubber roller for preventing the sheet from being slipped; and a metallic roller having fine protrusions having a height of about 40 to 100 &mgr;m (hereinafter referred to as “spike”) formed thereon by etching that function to bite the thermal transfer image receiving sheet, thereby carrying the thermal transfer image receiving sheet with high accuracy. This grip roller, however, has originally been used mainly in monochrome printing apparatuses where the reciprocation of the thermal transfer image receiving sheet is not required, such as diazo copying of drawings and printers for drafting. Therefore, the carrying accuracy of a printer using this grip roller is not very good, and printing of an image while reciprocating the thermal transfer image receiving sheet has been likely to create misregistration. Increasing the pushing force of the rubber roller and the metallic roller can improve the carrying accuracy in the reciprocation of the thermal transfer image receiving sheet. In this case, however, the spike of the metallic roller bites the thermal transfer image receiving sheet, creating and leaving a trace of the spike. In particular, in the case of a thin thermal transfer image receiving sheet, the trace of the spike poses a serious problem. In some cases, the trace reaches the image receiving face on the surface of the thermal transfer image receiving sheet, resulting in deteriorated print quality.
In order to cope with the above problems, in view of properties of commercially available printers, for example, the carrying accuracy of the printer, the pushing force of the grip roller for improving the carrying accuracy, the degrees of the trace of spike created by increasing the pushing force of the grip roller and the like, thermal transfer image receiving sheets compatible with respective various printer types have hitherto been supplied. For example, the thickness of the thermal transfer image receiving sheet has been increased so that, even when the pushing force of the grip roller is increased to improve the carrying accuracy, the influence of the spike does not reach the image receiving face.
Supplying a wide variety of thermal transfer image receiving sheets compatible with respective various printers, however, results in remarkably increased development cost and production cost. Further, an increase in thickness of the thermal transfer image receiving sheet in order to reduce the influence of the spike limits the thickness and layer cons
Dai Nippon Printing Co. Ltd.
Hess Bruce H.
Parkhurst & Wendel L.L.P.
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