Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1999-08-25
2002-01-08
Nguyen, Thinh (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S086000
Reexamination Certificate
active
06336704
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a printer with a head that is recordable a plurality of different inks on a printing medium, as well as to a corresponding method of printing, an ink cartridge used for such a printer, and a program product utilized by such a printer.
2. Description of the Related Art
Color printers with a head that records a plurality of different color inks on a printing medium are widely used as an output device of a computer, which prints an image processed by the computer in a multi-color, multi-tone manner. There are a variety of known methods to record ink on the printing medium: a thermal transfer mechanism that fuses ink on an ink ribbon and transfers the fused ink to printing paper; an ink jet mechanism that ejects color ink drops onto printing paper; and an electrophotographic mechanism that generates a latent image on a photosensitive material by means of laser and transfers one or plural color toners corresponding to the generated latent image. In any of such mechanisms, a plurality of different color inks are mixed to reproduce colors in a predetermined range of hues. Three primary color inks, cyan (C), magenta (M), and yellow (Y) are typically used for full-color printing. A black ink is provided in addition to these three primary color inks CMY, in order to ensure high-speed printing of letters (generally in black) and reduce the total quantity of inks used for printing by the under color removal.
A variety of techniques, such as the dither method and the error diffusion method may be applied to print a multi-color, multi-tone image with a plurality of different inks. In any of these applicable techniques, the printer carries out printing with dots of a specific size corresponding to a preset printing resolution. The printers generally have the printing density or printing resolution in the range of 300 dpi to 720 dpi and the particle diameter of several tens microns. Even the newly developed high-resolution printers have the printing resolution of about 1440 dpi. This is, however, significantly lower than the expression power of silver films (generally having the resolution of several thousands dpi). The printer accordingly has the problem that dots are visually observable to cause granularity in a resulting printed image. Some techniques have been proposed, in order to solve this problem. The proposed technique provides inks of different densities or applies the mechanism of varying the dot diameter to carry out printing with low-density dots or with small-diametral dots.
In the configuration of printing an image by dots, dots created by a black ink having the highest density causes the highest degree of granularity. The conventionally known technique accordingly does not use the real black ink but expresses a black color (generally referred to as the composite black) with three primary color inks in the case of high-quality printing of an image.
The known composite black technique that expresses the black color with three primary color inks, however, requires dots of all the three primary colors to express a single black dot. This triples the required number of dots. The following problems arise due to an increase in number of dots required for expressing an achromatic color of a specific density:
(1) In an ink jet printer that provides an ink prepared by dissolving a pigment or a dye in a solvent and causes the ink to be ejected as ink droplets on printing paper, the total quantity of inks ejected per unit area is restricted by the ink duty of the printing paper, that is, the quantity of ink that can be absorbed by the printing paper. The total quantity of inks to express the black color by the composite black may exceed the restriction of the ink duty in the event that the printing paper used has a relatively low ink duty.
(2) The composite black technique expresses the black color with three primary color inks. There is accordingly insufficiency of the required density as the black color and may give certain unclearness to the whole image. In the event that the three primary colors have high dot densities, the overlap of the respective color dots created in a certain sequence may cause color mismatch. Especially in the case of non-liquid inks, such as thermally fusible inks, the overlap of the respective dots may give the impression of coating the different inks one after another. It is accordingly difficult to attain the dot density of or over a certain level as the black color.
(3) At the boundary where the dots of the composite black are gradually replaced by the dots of the real black ink, the state filled with the dots of the three different color inks to express the black color is changed to the state filled with the dots of only one black ink to express the black color. The blotting condition may change over the boundary when the printing paper is readily affected by the blot. In this case, the resulting printed image may not have a uniform picture quality.
A variety of techniques have thus been proposed to partly replace dots of the real black ink with dots of the composite black in an allowable range specified by the ink duty and the restriction of the dot density. In any of such known techniques, dots of the real black ink are created at or over a predetermined density. This undesirably worsens the granularity at the boundary that starts creation of dots by the real black ink.
SUMMARY OF THE INVENTION
The object of the present invention is thus to adjust hues of at least two different inks and satisfy a predetermined ink duty of a printing medium and other required conditions without lowering the picture quality of a resulting recorded image in a printer with a head that is capable of recording a plurality of different inks on the printing medium.
At least part of the above and the other related objects is attained by a printer with a head that is capable of recording a plurality of different inks on a printing medium. Two among the plurality of different inks are a specific chromatic color ink having a predetermined hue and a particular ink having a certain hue that is mixed with the specific chromatic color ink at a predetermined rate to express a black color. The printer includes a black color recording unit that causes the head to record the specific chromatic color ink and the particular ink at the predetermined rate on the printing medium, so as to express the black color.
The present invention is also directed to a method of printing, which corresponds to the above printer. The method causes a printer to print an image with a head that is capable of recording a plurality of different inks on a printing medium. The method includes the steps of: providing a specific chromatic color ink having a predetermined hue and a particular ink having a certain hue that is mixed with the specific chromatic color ink at a predetermined rate to express a black color, as two among the plurality of different inks; and causing the head to record the two inks at the predetermined rate on the printing medium, so as to express the black color.
The printer or the printing method corresponding thereto of the present invention provides the specific chromatic color ink having a predetermined hue and the particular ink having a certain hue that is mixed with the specific chromatic color ink at a predetermined rate to express a black color, as two among the plurality of different inks used for printing. The head is made to record the specific chromatic color ink and the particular ink at the predetermined rate on the printing medium, so as to express the black color. In order to record an achromatic multi-tone image, black dots are not created solely by real black ink but are created by the specific chromatic color ink and the particular ink that expresses the black color in combination with the specific chromatic color ink. Compared with the case in which black dots are created solely by the real black ink, this arrangement of the present invention enables printing with less granularity.
From th
Nguyen Thinh
Seiko Epson Corporation
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