Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1999-10-22
2002-01-08
Le, N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S015000, C347S100000
Reexamination Certificate
active
06336705
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink jet recording method and an ink jet recording apparatus for recording a color image or a monochromatic image by the simultaneous use of pigment ink and dye ink, a control method of such an apparatus, and a machine-readable storing medium.
2. Description of the Related Art
The ink jet recording method comprise the steps of producing ink droplets by the application of any of various ink discharge processes such as the electrostatic sucking process based on application of a high voltage, a process of imparting a mechanical vibration or a displacement to the ink (coloring ink) by the use of a piezo-electric element, or a process using the pressure causing bubbling of the ink upon heating it, causing such droplets to fly to adhere to a recording medium such as a sheet of paper, and forming ink dots, thereby accomplishing recording. This method is advantageous in inconspicuous generation of noise during recording, and availability of a high-resolution recorded image at a high speed by using a high-integration head.
For the ink jet recording method as described above, it has been the conventional practice to use dye ink prepared by dissolving various water-soluble dyes in water or in a mixed solution of water and an organic solvent. However, an image recorded with dye ink has often been defective in durability such as light fastness and water resistance. Particularly regarding black popularly used in public documents, a particularly high durability has been demanded as compared with the other colors.
On the other hand, pigment ink prepared by dissolving a pigment dispersion solution made by dispersing a pigment in a polymer dispersant into a water-soluble solvent is disclosed in Japanese Patent Laid-Open No. 56-147859 and Japanese Patent Laid-Open No. 56-147860. Because pigment ink has more excellent properties than those of dye ink in water resistance as well as in light fastness, various kinds of pigment ink have so far been studied, and more recently, there is known an ink jet printer having particularly a printing quality improved by using pigment ink.
The reason of the improvement of printing quality brought about by using pigment ink will be briefly described. Particles of the coloring agent in a pigment are larger in size than those of a dye, resulting in difficulty to penetrate into depth of texture of plain paper or the like, and in stagnation near the surface. As a result, the printing density is high, with slighter penetration into areas surrounding the print, thus boundaries are clearly and distinctly printed.
Under the present circumstances, however, it is very difficult to materialize pigment ink for colors other than black in terms of coloring. Many of the ink jet printers adopting pigment ink therefore use pigment ink only for black ink and employ dye ink as color ink (generally, cyan, magenta and yellow).
Recording media onto which recording is possible by an ink-jet printer include, apart from plain paper, ink-jet recording paper, a postcard, cloth, glossy paper, a glossy film made of plastics, a transparent sheet used for projecting with a projector (hereinafter referred to as an “OHP sheet”), a back-printed film having an ink receiving layer provided on a side of a substrate, to be viewed from a side opposite to the surface having the ink receiving layer, and a transfer medium used for transferring a recorded surface onto cloth or a sheet, and these media are used for various applications. Among others, each of the ink-jet recording paper, the glossy paper, the glossy film, the OHP sheet, the back-printed film and the transfer medium has generally an ink receiving layer for absorbing the ink on the substrate.
In the case of dye ink, in which coloring is accomplished by a dye staining the recording medium, the surface condition of the recording medium exerts only a slight effect on the image density. In the case of pigment ink, in contrast, in which the pigment aggregate near the surface of the recording medium and solidify there, the surface condition of the recording medium exerts an important effect on the image density. The pigment ink tends to have a rough recorded surface after fixing because particles of the coloring agent and large in size as described above as a result of properties thereof.
Inconveniences have therefore been encountered for the pigment ink in a serious deterioration of the image density and a lower image quality, depending upon the kind of the recording medium.
For example, recording on a recording medium having originally a rough surface such a plain paper poses no problem. However, recording on a special glossy medium such as glossy paper or a glossy film leads to loss of the original glossy of the medium, thus resulting in an undesirable dots quality. Particularly when recording simultaneously with dye color ink, non-glossy dots are locally produced in dark portions of the image which gives a strong feeling of strangeness. This problem is not limited to glossy media, but the same problem, although to a smaller extent, is encountered in a coated sheet of paper having an ink receiving layer provided on the substrate such as special glossy ink-jet paper. This attributable to the fact that, since the ink receiving layer smoothens irregularities of the paper surface, roughness of pigment ink particles is serious, though not so much as in a glossy medium.
In the case of a recording medium, having an ink receiving layer on a side of the substrate as described above, to be viewed from a side opposite to the surface having the ink receiving layer (such as a back-printed film), recording even with pigment ink results in a hardly visible image, and a sufficient print density is unavailable. The pigment ink does not sufficiently penetrate into the ink receiving layer and remains near the surface, thus making it difficult for the pigment ink to penetrate and reach the side opposite to the recorded surface.
When recording an image on a plastic sheet having an ink receiving layer with pigment ink, cracks may occur on the recorded surface after fixing, depending upon the kind of the pigment, the ink composition, and the material and structure of the ink receiving layer. Particularly in an OHP sheet, which is projected in an enlarged size by an overhead projector, cracks are clearly visible. Such cracks lead to a lower image quality.
Causes of cracking will now be briefly described. In general, the ink receiving layer on the surface of an OHP sheet for ink-jet printer has a mechanism of absorbing the ink by swelling. On the other hand, the pigment ink is not absorbed as much, from its nature, by the ink receiving layer because of the large particle size of the coloring agent, and stays on the surface of the receiving layer. As a result, pigment particles combine together and form a layer on the surface, and then dried. The ink receiving layer swelling by sucking the ink solvent pushes up this layer, and this is considered to cause cracking.
Further, the pigment ink is inferior in frictional wear resistance to the dye ink because the pigment ink is fixed near the surface of the medium, and tends to come off by frictions. A medium usually recorded on the both sides such as a postcard is loaded on a auto-sheet feeder after recording a side for recording on the other side, at this point, the pigment ink recorded on the back of the postcard may adhere to the next sheet of paper.
SUMMARY OF THE INVENTION
To solve the aforementioned problems, the present invention has an object to provide a method of recording a high-quality image to any of a various types of recording medium, an apparatus therefore, a control method of the apparatus and a machine-readable storing medium.
Another object of the invention is to provide a method of recording an image having a sufficient print density and excellent in durability by making full use of properties of pigment ink, an apparatus therefor, a control method of the apparatus and machine-readable storing medium.
For the purpose o
Le N.
Nguyen Lamson D.
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