Recorders – Markers and/or driving means therefor – With ink supply to marker
Reexamination Certificate
2000-09-06
2003-03-04
Pham, Hai (Department: 2853)
Recorders
Markers and/or driving means therefor
With ink supply to marker
C347S101000, C347S104000, C347S106000
Reexamination Certificate
active
06529220
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image forming method and apparatus for generating an image recording liquid having a predetermined density and/or a predetermined color by changing a mixing proportion of plural coating liquids based on an image signal, and leading the image recording liquid as a continuous flow to an image receiving medium to form an image.
2. Description of Related Art
U.S. Pat. No. 4,109,282 discloses a printing device, in which a valve called a flap valve is disposed in a flow path for leading two types of liquid, that is, clear ink and black ink into an image forming substrate. The flow path for each ink is opened/closed by displacing this valve so that the two types of liquid are mixed by a kept/fixed total amount in a desired density to be transferred onto the substrate. This enables printout of an image having gray scale information which is the same as that of the image information displayed on a TV screen.
This patent discloses that a voltage is applied between the flap valve and an electrode provided on an surface opposite to the flap valve and the valve itself is mechanically deformed by an electrostatic attracting force to displace the valve. Furthermore, the ink is absorbed in paper by a capillary action which acts on the ink between a tip end of the flap valve and fibers of a print paper.
Unexamined Japanese Patent Publication (KOKAI) No. 291663/1988 discloses a coating method, in which two types of thick (dark) and thin (light) liquid are mixed in a coating head to be continuously extruded from a slot-opening opposed to a running web. Thus, the mixed liquid is consecutively coated on the web. In this coating method, the mixed liquid is coated over the entire coating width with a uniform coating membrane pressure without forming residue deposit, and the coating liquid having a density graduation in time course is, continuously applied with respect to a traveling direction of the web. In addition, this method enables coating with a uniform thickness with respect to the width direction.
According to the method disclosed in the U.S. Pat. No. 4,109,282, the ink extruded from the nozzle is directly applied on the paper. Therefore, when the paper has a large thickness or irregularity on a surface, it is difficult to reproduce an image on the paper with fidelity with respect to the electric signal. Accordingly, this method has not been practically used yet. Further, since the ink to be used is restricted to two types, a color image cannot be recorded.
Furthermore, since the ink is drawn out by the capillary action between the ink and the fibers of the paper in this mode, the ink tends to be affected by paper quality and a change in the paper quality involves a change in an image quality. Moreover, the image cannot be truly reproduced due to the partial irregularity of the fiber structure even if the paper with the same quality is used.
According to the method disclosed in the Unexamined Japanese Patent Publication (KOKAI) No. 291663/1988, although the image having the density graduation along the traveling direction of the web which is a coating target can be formed, the image cannot have a density graduation along a width direction of the web (a direction perpendicular to the traveling direction). Consequently, application of the coating liquid whose color or density changes for each pixel in accordance with an image signal is impossible.
Therefore, the present applicant has proposed an image forming method (continuous coating method) of changing a mixing proportion of a plurality of coating liquids based on an image signal to extrude a continuous flow from a plurality of coating liquid extruding ports, and continuously coating an image receiving medium with the continuous flow of the image recording liquid (Japanese Patent Application No. 374662/1998;
U.S. patent application Ser. No. 09/472,977). Moreover, when the image receiving medium is continuously coated with the image recording liquid, distortion of a stream line of image recording liquid occurs in a bead formed on an upstream side of a coating portion, and the image quality is deteriorated. In order to prevent this stream line distortion, the present applicant has also proposed a method of applying a clear undercoating liquid between the image recording liquid and the image receiving medium (Japanese Patent Application No. 374663/1998; U.S. patent application Ser. No. 09/472,974).
However, in these continuous coating methods, on both edges of an image forming width the image recording liquid is raised and thickened, or spread over and thinned in a width direction. Therefore, an image density rises or decreases particularly in the vicinity of both edges of the image forming width and an image quality is deteriorated by the, distorted stream line of the image recording liquid.
Moreover, in these continuous coating methods, in a front edge (edge of the image receiving medium in a moving direction) or a rear edge (edge in a direction reverse to the moving direction) of an image forming area, the image recording liquid becomes thick as compared with a central portion of the image forming area, or is spread on the front edge or the rear edge and thinned. Moreover, a position of the image recording liquid may change. Therefore, the thickness of the image recording liquid is distorted particularly in the vicinity of the front edge or the rear edge of the image forming area, resulting in that no desired image quality or density can be obtained.
SUMMARY OF THE INVENTION
The present invention has been accomplished under the aforementioned circumstances, and a first object thereof is to provide an image forming method by which a thickness or a stream line of an image recording liquid can be prevented from being distorted in the vicinity of both edges of an image forming width in a continuous coating method, and a stable and good-quality image can be formed. A second object is to provide an image forming apparatus for direct use in implementing the method.
Moreover, a third object of the present invention is to provide an image forming method by which a thickness or a position of an image recording liquid can be prevented from changing in the vicinity of a front edge and/or a rear edge of an image forming area in a continuous coating method, and a stable and good-quality image can be formed. A fourth object is to provide an image forming apparatus for direct use in implementing the method.
According to the present invention the first object is attained by an image forming method for forming an image on an image receiving medium with an image recording liquid, comprising steps of:
a) combining a plurality of recording liquids to form said image recording liquid, a mixing ratio of the plurality of recording liquids being varied based on an image signal;
b) extruding said image recording liquid from an image recording liquid extruding port to the image receiving medium as a continuous flow while the image receiving medium is moved relatively to the extruding port, so that said image recording liquid is continuously transferred to the image receiving medium to form the image; and
c) extruding a dummy liquid for forming no image from a dummy liquid extruding port to the image receiving medium;
wherein to said image receiving medium, the image recording liquid is transferred in an image forming width, and a dummy liquid for forming no image is transferred to the outside of said image forming width.
In the present invention, the dummy liquid for forming substantially no image is applied outside the image forming width. This prevents both edges of the image recording liquid from being raised and thickened on the image receiving medium or being spread out in a width direction, prevents an image density from rising or lowering in the edge of the image and can prevent a stream line of the image recording liquid from being distorted. Therefore, an image quality can be enhanced.
The image recording liquid within the image forming width and the dummy liquid outsi
Pham Hai
Stewart Jr. Charles W.
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