Incremental printing of symbolic information – Thermal marking apparatus or processes – Gradational recording
Reexamination Certificate
1999-03-30
2001-05-01
Le, N. (Department: 2861)
Incremental printing of symbolic information
Thermal marking apparatus or processes
Gradational recording
Reexamination Certificate
active
06226021
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image forming method of a thermal transfer printer, and particularly to an image forming method of a thermal transfer printer in which a color image having multistage gradations is recorded by using resin-based inks.
2. Description of the Prior Art
In general, in a thermal transfer printer, a paper is supported in front of a platen, and a thermal head having a plurality of heating elements formed thereon is mounted on a carriage. Under the condition that an ink ribbon and the paper are sandwiched between the thermal head and the platen, the thermal head is reciprocated along the platen together with the carriage to supply the ink ribbon. The heating elements of the thermal head are selectively energized based on recording information to partly transfer inks of the ink ribbon onto a paper, thereby resulting in an image such as a desired character being recorded on the paper. Such thermal transfer printer is considerably widespread as an output apparatus for a computer, a word processor or the like because it is high in recording quality, low in noise, low in cost and is easy in maintenance.
As a conventional thermal transfer printer, there is known a thermal transfer printer in which an ink ribbon having a wax-based ink with fusion property coated on base such as a plastic film is used to record an image on a paper. Then, when an image having multistage gradations is recorded by using such wax-based ink, there is used a dither method or the like. Recently, in accordance with an increasing demand of a color image having a higher resolution, by controlling energy to energize heating elements of a thermal head to adjust heat energy applied to inks and controlling fused areas of inks in response to image information, an image having multistage gradations is recorded on a micro-porous paper in which a micro-porous layer, each pore having a diameter of 2 to 10 &mgr;m, is formed on the surface.
However, in the conventional thermal transfer printer, when an image is recorded by using the above-mentioned wax-based ink, since the ink itself is soft, if a recorded image is rubbed, then the recorded image is deteriorated.
Moreover, when the micro-porous paper is in use, the ink is permeated into the micro-porous layer so that a clear image cannot be obtained due to the influence of the surface characteristic of the micro-porous paper.
Moreover, it has been proposed that an image is recorded by using an ink ribbon having a resin-based single-layer ink layer. When an image is recorded by using this resin-based ink, although a problem in which a recorded image is deteriorated by rubbing can be solved and a clear image having an excellent fastness can be obtained, the resin-based ink is poor in transfer sensitivity as compared with the wax-based ink so that an accurate transfer cannot be obtained particularly in the low-density portion. As a result, a jaggy is produced in the recorded image due to a transfer failure or the like. There is then the problem that a clear recorded image cannot be obtained.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an image forming method of a thermal transfer printer in which an image can be accurately transferred even onto a low-density portion by using a resin-based ink having an excellent fastness and in which a clear image having multistage gradations can be recorded.
That is, in an image forming method of a thermal transfer printer in which a dither matrix comprised of a plurality of dots are used to record one pixel and a plurality of heating elements of a thermal head are selectively energized to change dot diameters to transfer resin-based inks onto a paper, thereby recording an image having multistage gradations, the image forming method of a thermal transfer printer is characterized in that a threshold value of the dither matrix in one pixel is arranged such that each dot is sequentially plotted in the scanning direction of the thermal head.
Then, it is another object of the present invention to provide an image forming method of a thermal transfer printer using the above-mentioned arrangement in which dots are continuously formed in one pixel and a clear image in which dots are satisfactorily made continuous can be recorded efficiently so that, even when the resin-based ink is used, a proper and clear image having multistage gradations can be recorded.
Further, in an image forming method of a thermal transfer printer according to the present invention, the order in which each dot between respective pixels is plotted is comprised of threshold values continuous in the scanning direction of the thermal head.
Then, it is a further object of the present invention to provide an image forming method of a thermal transfer printer in which dots can be continuously formed between the pixels so that a clear image in which respective pixels are satisfactorily made continuous can be recorded efficiently.
Further, in image forming method of a thermal transfer printer according to the present invention, a color image is recorded by resin-based inks of at least three colors of cyan, magenta and yellow.
Then, it is a still further object of the present invention to provide an image forming method of a thermal transfer printer in which a full color image can be properly recorded by the resin-based inks of at least three colors of cyan, magenta and yellow.
Further, in an image forming method of a thermal transfer printer in which a dither matrix comprised of a plurality of dots are used to record one pixel and a plurality of heating elements of a thermal head are selectively energized to change dot diameters to transfer resin-based inks onto a paper, thereby recording an image having multistage gradations, the image forming method of a thermal transfer printer is characterized in that an image is recorded in response to gradations without using a dither matrix of a threshold value in which an energization time of the thermal head becomes discontinuous.
Then, it is a still further object of the present invention to provide an image forming method of a thermal transfer printer in which gradations can be accurately expressed in proportion to an energization time of a thermal head and an image having multistage gradations can be recorded properly.
Furthermore, in image forming method of a thermal transfer printer according to the present invention, a color image is recorded by resin-based inks of at least three colors of cyan, magenta and yellow.
Then, it is a yet further object of the present invention to provide an image forming method of a thermal transfer printer in which a full color image can be properly recorded by the resin-based inks of three colors of cyan, magenta and yellow.
REFERENCES:
patent: 4805033 (1989-02-01), Nishikawa
patent: 4809063 (1989-02-01), Moriguchi et al.
patent: 5467120 (1995-11-01), Sadaki et al.
patent: 5721578 (1998-02-01), Nakai et al.
patent: 5982405 (1999-11-01), Sasaki et al.
patent: 6005596 (1999-12-01), Yoshida et al.
patent: 0304289 (1989-02-01), None
patent: 0517263 (1992-12-01), None
patent: 0660586 (1995-06-01), None
Kobayashi Hiroshi
Takahashi Hiromitsu
Zama Hiroyoshi
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Feggins K.
Le N.
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