Incremental printing of symbolic information – Ink jet – Controller
Reexamination Certificate
1997-11-13
2001-11-27
Lee, Susan S. Y. (Department: 2852)
Incremental printing of symbolic information
Ink jet
Controller
C347S012000, C347S060000
Reexamination Certificate
active
06322183
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a recording apparatus in which recording is performed by ejecting ink to fly in the form of small droplets through ejection ports (orifices) and depositing the small droplets on the surface of a recording material, as well as a method of controlling the recording apparatus.
2. Description of the Related Art
Heretofore, as ink for ink jet recording, water-based ink has been primarily employed from the standpoints of, e.g., ensuring safety and eliminating a bad odor. There are known many types of ink prepared by dissolving or dispersing various water-soluble dyes or pigments in water or a mixture of water and a water-soluble organic solvent, and if necessary adding a moisture retaining agent, a dye dissolving aid, a fungicide, etc. Ink jet recording made using such ink has been rapidly developed in these years because of many advantages of, e.g., enabling high-speed recording to be easily realized as several thousands or more ink droplets can be ejected per second, generating less noise, ensuring easy production of a color image, providing a high resolution, and permitting an image to be printed on plain paper.
Further, with a recent trend toward the lower price, higher performance, and standardization of the GUI (Graphical User Interface) environment in the field of personal computers, there is increasing demand for better color development, higher quality, higher durability, higher resolution and higher speed in image recording using printers or the like. To meet such a demand, technical concepts have been proposed with an aim at holding down feathering, bleeding (color mixing) and other unfavorable properties by leaving color components as much as possible on the.paper surface and making the edges of recording dots sharper.
As the first example, Japanese Patent Laid-Open No. 58-13675 discloses a method of controlling absorption of ink and spread of recording dots into and over paper by addition of polyvinyl pyrrolidone into the ink. As the second example, Japanese Patent Laid-Open No. 3-172362 discloses a method of controlling absorption of ink and spread of recording dots into and over paper by addition of a specific micro-emulsion into the ink.
As the third example utilizing a sol-gel transition phenomenon of ink, Japanese Patent Laid-Open No. 62-181372, and No. 1-272623, as well as others disclose that ink can be prevented from permeating into paper by using an ink which is in the gel form at room temperature and transitions to the sol form upon heating, and recording an image with the ink applied in the sol state to a recording material, because the ink restores to the gel state upon cooling.
As the more recent fourth example, Japanese Patent Laid-Open No. 6-49399 discloses an ink which is added with a compound having a characteristic of thermally gelling in a reversible manner, thereby realizing good color development and fixing property, showing less feathering, and being superior in preservation and reliability of prints, as well as an ink jet recording method and apparatus both using the ink. The technical background of this related art is based on a phenomenon that as a solution of a particular water-soluble high molecule is gradually heated, water solubility of the high molecule is reduced and the solution becomes cloudy at a specific temperature (that is called a clouding point). Typical examples of such a high molecule include, for example, N-isopropyl acrylic amide, polyvinyl methyl ether, polyethylene oxide, and hydroxypropyl cellulose. Because these high molecules show solubility having a negative temperature coefficient, they are separated and precipitated from the solution at temperatures not less than the clouding point. In the precipitating state, viscosity of the solution is lowered due to generation of hydrophobic microgel. After being recorded on a recording material in the precipitating state, the solution restores its original viscosity with a temperature effect developed on the surface of the recording material. Thus, the increased viscosity holds down the ink from permeating into paper.
Meanwhile, as the fifth example, M. Croucher et al. point out the problems of conventional homogeneous ink and propose, as inkjet ink in future, an inhomogeneous ink utilizing latex (see M. D. Croucher and M. L. Hair; Ind. Eng. Chem. Res. 1989, 28, 1712-1718, “Design Criteria and Future Direction in Inkjet Ink Technology”). In addition, U.S. Pat. No. 4,246,154 discloses an ink wherein fine particles of a vinyl polymer colored with dyes are stabilized in the anionic form. U.S. Pat. No. 4,680,332 discloses an inhomogeneous ink containing an oil-soluble dye wherein a water-soluble polymer coupled to a non-ionic stabilizer is dispersed a liquid medium. Also, U.S. Pat. No. 5,100,471 proposes a water-based ink consisted of a solvent and colored particles each made up of a polymer core and a silica shell covalently bonded to a dye. This proposed ink has features of enabling colors to develop more sharply on paper, being stable against temperature, and providing high water-resistance.
Further, as the sixth example, Japanese Patent Laid-Open No. 3-240586 proposes a non-water-based ink wherein colored particles covered by a resin swelling with a dispersion medium, such as kerosene, are dispersed in the dispersion medium. It is suggested that this proposed ink is effective particularly in preventing feathering of ink images and clogging of nozzles for ejecting liquid droplets.
The above-stated first and second examples have a problem in fixing property because the ink is prevented from permeating into paper and is to left stand on the paper for a long time without undergoing permeation. Another problem is that there occurs mixing between different colors (i.e., bleeding).
The sol-gel transition ink shown as the third example has a problem that a recorded image may suffer from bleeding and transfer fouling because changes in preservation temperature of prints cause the ink to have fluidity and to flow out.
The ink added with a compound having a characteristic of thermally gelling in a reversible manner, shown as the fourth example, is not suitable for a method of recording an image at such a high speed of not more than 10 msec per pixel as required in ink jet recording, because a rise in viscosity with a temperature drop is too slow as a result of employing water-soluble cellulose ethers. Also, when used in ink jet recording, ink is required to have an upper limit of viscosity not more than 20 mPa·s at the time of ink ejection. The ink must be therefore employed with a low concentration enough to satisfy the above requirement, which makes it hard for the ink to produce the effect of increasing viscosity sufficiently.
On the other hand, of the fifth example group, the ink containing vinyl polymer fine particles stabilized in the anionic form has a problem that a pH range in which the ink can disperse stably is narrow and a selectable range of dyes is small consequently. Another drawback is that spread of recording dots on paper is too small to provide a satisfactory value of optical density (O.D.). Further, the ink is less effective in shortening a fixing time, though this effect is essential for high-speed recording, because a fixing mechanism of the ink depends on only evaporation and permeation as with conventional image forming means.
Another ink of the fifth example group, which contains an oil-soluble dye and in which a water-soluble polymer coupled to a non-ionic stabilizer is dispersed a liquid medium, has an enlarged selectable range of dyes, but is also less effective in shortening a fixing time because a fixing mechanism of the ink depends on only evaporation and permeation as with the above ink. In addition, this ink is disadvantageous in preventing mixing between different colors (i.e., bleeding) because it takes time until adjacent dots are fixed into a stable state.
Still another disperse ink having the polymer-core/silica-shell structure is superior in stability of pigment dispe
Kimura Isao
Kubota Hidemi
Maeda Hiroyuki
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Lee Susan S. Y.
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