Incremental printing of symbolic information – Ink jet – Controller
Reexamination Certificate
1999-12-28
2003-02-11
Nguyen, Lamson (Department: 2861)
Incremental printing of symbolic information
Ink jet
Controller
C347S043000
Reexamination Certificate
active
06517178
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image forming method and apparatus for generating a fluid having a predetermined density and/or a predetermined color by changing a mixture proportion of a plurality of inks based on an image signal and leading the thus obtained fluid to an image receiving medium to form an image. Further, the present invention relates to a recording head for use in this image forming apparatus.
2. Description of the Prior Art
U.S. Pat. No. 4,109,282 (which will be referred to as a prior art reference 1, hereinafter) 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 gray scale information which is the same as that of the image information displayed on a TV screen. In this reference is disclosed that a voltage is applied between the flap valve and an electrode provided on a surface opposed to the flap valve and the valve itself is mechanically deformed by the electrostatic attracting force to cause displacement of the valve. Further, the ink is absorbed in paper by a capillary phenomenon between fibers of the print paper.
U.S. Pat. No. 4,614,953 (which will be referred to as a prior art reference 2, hereinafter) discloses a printer head apparatus by which only a desired amount of multiple types of ink having different colors and solvent is led to a third chamber to be mixed therein. In this reference is disclosed that 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 utilized.
Unexamined Japanese Patent Publication (KOKAI) No. 201024/1993 (which will be referred to as a prior art reference 3, hereinafter) discloses an ink jet print head including: a liquid chamber in which a carrier liquid is filled; ink jet driving means provided 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. In this reference is also disclosed that adjusting means for adjusting an amount of mixture of ink to a desired value is provided.
Similarly, Unexamined Japanese Patent Publication (KOKAI) No. 125259/1995 (which will be referred to as a prior art reference 4, hereinafter) discloses an ink jet recording head including: first and second supplying means for supplying inks having first and second densities, respectively; and controlling means which controls an amount of supply of the second ink by the second supplying means so that a desired ink density can be obtained.
In this reference 4, employment of a micro-pump which has an exclusive heating device and is driven by its heat energy is disclosed. As this micro-pump, there is disclosed an example such that the heat energy is generated by the heating device and a pressure obtained by the nucleate boiling caused due to the heat energy is used to drive, e.g., a piston-type valve or a cantilever-like valve. Further, this reference 4 describes that an inflow of ink can be effectively controlled in an area where an inflow is particularly small by adopting an actuator consisting of shape memory alloy to this valve.
Unexamined Japanese Patent Publication (KOKAI) No. 207664/1991 (which will be referred to as a prior art reference 5, hereinafter) discloses a structure which is similar to that in the prior art reference 2 but does not use a third chamber for mixing a plurality of types of ink.
Unexamined Japanese Patent Publication (KOKAI) No. 156131/1997 (which will be referred to as a prior art reference 6, hereinafter) 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 to obtain 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 the multiple printer heads when all-white image data, that is, data representing that amount of mixture of ink is too small to realize a clear printing density, is input. 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.
Unexamined Japanese Patent Publication (KOKAI) No. 264372/1998 (which will be referred to as a prior art reference 7, hereinafter) discloses employment of a plurality of line heads in which ink ejection nozzles are linearly aligned. In this example, when the respective line heads are biased and arranged in a direction for feeding print paper and positions of nozzles in the respective line heads are biased relatively to a direction of the width of the print paper, the pixel density can be enhanced. Further, ink having a single color is ejected from each nozzle, and ink droplets having different colors are combined by ejecting ink having different colors in accordance with the line heads, thereby representing predetermined colors on the print paper.
In the prior art disclosed in the prior art reference 1, the ejection ports for two types of liquid are separately formed directly on the print paper, and the respective types of liquid are separately attracted on the print paper by the capillary phenomenon immediately after ejection. Therefore, a quantity of attraction of each liquid on the paper readily fluctuates under the influence of the paper quality of the print paper, which results in the unstable image quality or difficulty of formation of an image having high fidelity to the image signal.
In any of the prior arts disclosed in the prior art references 2 to 6, a plurality of inks are previously mixed or caused to be confluent, and thereafter the mixed liquid (including the confluent liquid) is led onto the print paper. A plurality of the inks are brought into contact with each other in the mixing portion (the confluence portion), and each ink is ejected by a predetermined amount to be mixed. Namely, the ejection port for each ink is formed and assembled in the mixing portion. Each ink can not therefore prevent from being naturally diffused with each other.
For example, even if a given ink is not ejected into a mixing chamber in accordance with the image signal, this ink is naturally diffused in the mixing chamber. Thus, the density and/or color of the finally mixed ink liquid differs from the image signal, and an image which is true to the image signal can not be formed. When the distortion of the contact interface occurs due to a vibration in the mixing portion or any other disturbance even though the natural diffusion of the ink is small, the undesired mixing of ink is facilitated and the above-described problem becomes more prominent.
Since the ink having a single color is ejected from one nozzle in the prior art disclosed in the prior art reference 7, one pixel is formed by multiple (three, four or more colors) ink droplets. Therefore, the pixel density is hard to be enhanced, and improvement of the image quality is also restricted.
In the prior art reference 3 is disclosed that adjusting means functioning as a check valve is provided in the vicinity of the opening of the ink channel formed in the mixing portion in order to mainly prevent the inks from being naturally diffused with each other. However, provision of the adjusting means having the check valve structure complicates the print head configuration and leads to problems such as difficulty in manufacturing, reduction in productivity or increase in the manufacturing cost.
Further, although in the prior art reference 6 is disclosed that the colorless diluent continues to flow in case of all-white image data in order to avoid
Matsumoto Nobuo
Yamamoto Ryoichi
Fuji Photo Film Co. , Ltd.
Nguyen Lamson
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