Record receiver having plural interactive leaves or a colorless – Having plural interactive leaves
Reexamination Certificate
2002-03-05
2004-03-02
Hess, Bruce H. (Department: 1774)
Record receiver having plural interactive leaves or a colorless
Having plural interactive leaves
C428S032390
Reexamination Certificate
active
06699817
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thermal transfer recording sheet. More particularly, the present invention relates to a thermal transfer recording sheet appropriate for thermal transfer printers and, especially, dye-thermal transfer printers, provided with a glossy surface, having a high resistance to roughening and denting due to nipping pressure of a recording sheet-transporting roller system of the printers, and capable of recording thereon thermally transferred images having high clarity and accuracy comparable to those of silver salt photograph.
2. Description of the Related Art
The dye-thermal transfer printer forms dye images on an image receiving layer of a thermal transfer recording sheet by superposing a dye ink sheet on the image receiving layer, comprising a dyeable polymeric material, of the recording sheet and applying heat imagewise to the superposed dye ink sheet on the ink receiving layer of the recording sheet through a thermal head to cause the dye in the dye ink sheet to be transferred imagewise, in an amount corresponding to the amount of the applied heat, onto the ink receiving layer.
For the dye thermal transfer printer, yellow-, magenta- and cyan-coloring ink sheets or the above-mentioned three color-coloring ink sheets and black-coloring ink sheets are employed. Full-colored images can be formed by superposing colored images transferred from the above-mentioned three or four color-coloring ink sheets on each other on the image receiving layer.
Currently, the development of the thermal transfer printers and the progress of digital image-treatment enable the quality of the recorded images to be significantly enhanced and the thermal transfer recording systems to be sold in an expanded field. Typically, the thermal transfer recording systems are utilized for outputting and proofing of prints and designs, image-outputting of endoscopes and CT-scanners, outputting of photographs of faces in the amusement field, calendar-printing and putting images on ID cards and credit cards. Also, due to the enhancement of the performance of the thermal heads and the progress of the temperature-control technology, an further enhancement of the printing speed of the thermal transfer recording system is required. Currently, a new type of printer capable of printing a A6 size sheet within a time of 30 seconds or less has appeared on the market. It is expected that a further development in the high speed printer will be strongly demanded.
The increase in the printing speed causes problems on gradation of the color density of images and accuracy of images and prevention of shear in printed colored images. To obtain good gradation of the color density of the printed images, it is necessary to produce the color density of the images in a broad range by applying energy. To produce, in a narrow range, a high color density of images even using low energy, the recording sheet must have a high heat insulation property. Also, to obtain high accuracy in the images, the recording sheet must be brought into close contact with the thermal head of the printer, and for this purpose, the recording sheet must have a good cushioning property.
Further, to prevent shearing in the printed colored images, the recording sheet is transported through a nipping roller system comprising a roller equipped with a spike and a rubber roller. When the printing is carried out at a high speed, the nipping pressure applied to the recording sheet between the spike roller and the rubber roller must be increased. In this case, the image receiving surface of the recording sheet is roughened or dented and/or spike marks are formed on the image receiving layer and thus the commercial value of the printed sheets is reduced.
In conventional printers equipped with a thermal head, a recording sheet comprising a substrate sheet, which comprises a core sheet and films having microvoid layers and laminated on the two surfaces of the core sheet, and an image receiving layer comprising, as a principal component, a dyeable resin and formed on a surface of the substrate sheet is commonly employed to obtain good printed images. For example, Japanese Patent Publication No. 2,565,866 discloses a substrate sheet for the recording sheet, comprising a core sheet and synthetic paper sheet layers, comprising as a principal component a propylene resin, laminated on the two surfaces of the core sheet. Also, Japanese Patent Publication No. 2,922,525 discloses a substrate sheet for the recording sheet, comprising a core paper sheet and oriented polyethylene terephthalate film layers, having a plurality of microvoids, laminated on the two surfaces of the core paper sheet.
The above-mentioned films having the microvoid layer are advantageous in that the films are uniform in thickness thereof and flexible and have a thermal conductivity lower than that of paper sheets made from cellulose fibers and, thus, thermally transferred images having a high uniformity and a high color density can be formed on the films. Generally, an increase in the number and size of the microvoids causes a decrease in density of the films and thus results in enhancement in the heat-insulation and thermal sensitivity of the film. However, the increase in the number and size of the microvoids of the films causes the mechanical strength of the films and the resistance of the films to roughening or denting by the sheet-transporting roller system to be reduced. When the resistance of the films to the roughening or denting by the sheet-transporting roller system is increased by increasing the density of the front surface side film, the thermal insulation of the film and the close contact of the films with the thermal head decreases, and thus the resultant recording sheet exhibits a degraded thermal sensitivity and the printed images exhibit an unsatisfactory quality.
Thus, to respond to the development of high speed printing, it is required to provide a new type of thermal transfer recording sheet having a good contact with the thermal heads of printers, a high thermal insulation and a high resistance to roughening and denting due to the high pressure of the sheet-transporting roller system of the printers.
Also, in the conventional thermal transfer recording sheet having a substrate sheet comprising a core sheet and films each having a microvoid layer and laminated on the two surfaces of the core sheet and an image receiving layer comprising, as a principal component, a dyeable resin and formed on a front surface of the substrate sheet, a phenomenon such that, when the recording sheet is printed by heating imagewise by a thermal head of the printer, the front film layer of the substrate sheet located below the image receiving layer is thermally shrunk to cause the recording sheet to be curled, apparently occurs. This phenomenon will be referred to as print curling phenomenon hereinafter. The print curling phenomenon causes the commercial value of the printed recording sheet to be significantly decreased.
It is known that, in the conventional thermal transfer recording sheet having a substrate sheet, which comprises a core sheet and films having a microvoid layer and laminated on the two surfaces of the core sheet, and an image receiving layer comprising, as a principal component, a dyeable resin and formed on a front surface of the substrate sheet, the print curling phenomenon can be rectified by differentiating in thickness and in thermal shrinkage between the front and back film layers of the substrate sheet. Namely, when the image receiving layer is formed on the front film layer surface of the substrate sheet by conventional coating and drying procedures, shrinkages of the front and back film layers occur due to the drying heat applied to the image receiving layer on the substrate sheet. The shrinking stresses generated in the front and back film layers are controlled by the above-mentioned means to rectify the print curling phenomenon on the recording sheet.
In this case, however, when the image receiving lay
Mizuhara Yoshio
Nagashima Shigeru
Shimizu Yoshihiro
Tachibana Kazuyuki
Tanaka Yoshimasa
Arent Fox Kintner Plotkin & Kahn
Hess Bruce H.
Oji Paper Co. Ltd.
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