Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2000-08-28
2002-09-03
Yockey, David F. (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S101000, C347S100000, C347S098000
Reexamination Certificate
active
06443551
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates-to an image forming method for producing a recording liquid having a predetermined density and/or a predetermined color by changing a mixture proportion of an image non-forming liquid with one type or a plurality of types of image forming liquid based on an image signal and leading this recording liquid to an image receiving medium to form an image. The present invention further relates to an image forming apparatus by this method.
2. Description of the Prior Art
There has been proposed an image forming method, in which different colors of ink are mixed based on an image signal in advance and transferred to an image receiving medium such as a print paper (for example, U.S. Pat. Nos. 4,109,282 and 4,614,953, Unexamined Japanese Patent Publication (KOKAI) Nos. 201024/1993, 125259/1995, 207664/1991 and 156131/1997). Such method of using a fluid whose density/color is preset in response to the image signal to form an image is called a pre-mix mode. According to the mode, the density or the color can be adjusted for each pixel based on the image signal, an image quality can be enhanced.
U.S. Pat. No. 4,109,282 discloses a printer having a structure such that a valve called a flap valve is provided in a flow channel for leading two types of liquid, i.e., clear ink and black ink onto a substrate for forming an image. The flow channel for each ink is opened/closed by displacing this valve so that the two types of liquid are mixed in a desired density to be transferred onto the substrate. This enables printout of an image having the same gray scale information as that of image information displayed on a TV screen.
In this reference it is disclosed that a voltage is applied between the flap valve and an electrode provided on a surface opposite to the flap valve and the valve itself is mechanically deformed by an electrostatic attracting force to cause displacement of the valve. The ink is absorbed by a capillary phenomenon between fibers of the print paper. However, since this apparatus joins and mixes the two types of liquid on the substrate immediately after ejection, the system is exactly different from the aforementioned pre-mix mode.
U.S. Pat. No. 4,614,953 discloses an ink jet printer head apparatus in which only desired amounts of a plurality of types of ink having different colors and solvent are led to a third chamber to be mixed therein and flied as an ink droplet. In this reference, a chamber and a diaphragm-type piezoelectric effect device attached to this chamber are used as means for check-weighing a desired amount of ink and a pressure pulse obtained by driving this piezoelectric device is used.
Unexamined Japanese Patent Publication (KOKAI) No. 201024/1993 discloses an ink jet print head including: a liquid chamber filled with a carrier liquid; ink jet driving means disposed in the liquid chamber; a nozzle communicating with the liquid chamber; and a mixing portion for mixing ink to the carrier liquid in this nozzle. Here it is also disclosed that adjusting means for adjusting a mixture amount of ink to obtain a desired value is provided.
Similarly, Unexamined-Japanese Patent Publication (KOKAI) No. 125259/1995 discloses an ink jet recording head including: first and second supplying means for supplying ink having first and second densities, respectively; and controlling means which controls a supply amount of the second ink by the second supplying means so that a desired ink density can be obtained.
In this reference, employment of a micro-pump which has an exclusive heating device and is driven by its heat energy is disclosed as the controlling means. As this micro-pump, an example is disclosed in which the heat energy is generated by the heating-device and a pressure obtained by nucleate boiling caused due to the heat energy is used to drive, for example, a piston-type valve or a cantilever-like valve. Further, this reference describes that an inflow of ink can effectively be controlled in an area where the inflow is particularly small by adopting an actuator consisting of shape memory alloy with this valve.
Unexamined Japanese Patent Publication (KOKAI) No. 207664/1991 discloses an ink jet printer having a structure similar to that disclosed in the above mentioned U.S. Pat. No. 4,614,953, but a third chamber for mixing a plurality of types of ink is not used.
Unexamined Japanese Patent Publication (KOKAI) No. 156131/1997 discloses an ink jet printer comprising a plurality of printer heads for forming an image having multiple colors based on image data. Ink and diluent are mixed at a predetermined mixing ratio to obtain a diluted ink which is jetted from a nozzle so that a recording image is formed on a recording medium. The ink jet printer ejects the diluent from at least one printer head out of a plurality of printer heads when all-white image data, that is, data representing that the mixture amount of ink is too small to realize a clear printing density, is inputted to the plurality of printer heads. As a result, a rapid change in tone (a tone jump) is prevented and the additional consumption of the diluent is suppressed to improve drying characteristics.
The U.S. Pat. No. 4,109,282 discloses a technique of controlling the supply amount of one type of ink to be mixed, that is, black ink. Therefore, a liquid flow rate of the mixed ink having the desired density, that is, a volumetric flow rate per unit time varies in accordance with a change in density.
As a mode in place of an ink jet mode, the applicant and his collaborators have been examining a mode for continuously transferring the ink liquid to an image receiving medium as a continuous flow without making a liquid droplet (hereinafter referred to as a continuous coating mode). Even in this mode, the aforementioned change of the supply amount of the mixed ink results in a disordered and unstable liquid flow. It has been revealed that a fluctuation of a volumetric flow rate (also referred to simply as the flow rate, hereinafter) per unit time of the mixed ink liquid due to the change of the mixing ratio of the inks results in various problems such as remarkable deterioration of quality of a finally formed image. Also when the color is changed by mixing a plurality of types of ink, similar problems occur.
Specifically, it is desirable that the ink liquid is transferred to the image receiving medium as a steady laminar flow. If a disorder or a whirlpool occurs in this flow, the image quality is deteriorated. Moreover, a fluctuation of the supply amount of the liquid leads to formation of coating film having various thickness on the image receiving medium, but it is very difficult to steadily form the coating film having varied or fluctuated thickness depending on a structure of a liquid ejection port. Even if the formation of such coating film is possible, irregularity is generated on the surface of the image, and the transferred liquid having the irregular surface in a liquid state tends to spread and smoothen the irregular surface, which deteriorates the image quality.
Moreover, in the continuous coating mode an image recording liquid needs to be continuously supplied between the recording head and the image receiving medium. However, the recording liquid flows slow on a portion in contact with a surface of the recording head, due to viscosity of the recording liquid. This causes a problem that delay is generated in a recording liquid coating position and the image quality is deteriorated.
In order to avoid the disadvantage, it is proposed to interpose liquids which form substantially no image after image formation, such as a clear liquid (hereinafter referred to as an image non-forming liquid, or simply a clear ink) so that the recording liquid fails to directly contact the surface of the recording head. For this purpose, it is proposed that the recording head is provided with a clear liquid ejection port separately from a recording liquid ejection port, and that the clear liquid is supplied to the portion between the recording
Fuji Photo Film Co. , Ltd.
Shah Manish
Sughrue & Mion, PLLC
Yockey David F.
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