Incremental printing of symbolic information – Ink jet – Controller
Reexamination Certificate
2001-02-20
2002-08-13
Gordon, Raquel Yvette (Department: 2853)
Incremental printing of symbolic information
Ink jet
Controller
Reexamination Certificate
active
06431671
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an ink jet recording method and apparatus for changing a mixture proportion of a plurality of types of ink based on an image signal to produce a fluid having a predetermined density and/or a predetermined color, and jetting this fluid to an image receiving medium to form an image.
BACKGROUND OF THE INVENTION
U.S. Pat. No. 4,109,282 (which will hereinafter be referred to as a prior art reference 1) discloses a printer having a structure such that a valve called a flap valve is disposed 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, it is disclosed that a voltage is applied between the flap valve and an electrode disposed on a surface opposite to the flap valve and the valve itself is mechanically deformed by the electrostatic attracting force to cause displacement of the valve. Furthermore, 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 hereinafter be referred to as a prior art reference 2) 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, it 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 hereinafter be referred to as a prior art reference 3) discloses an ink jet print head including: a liquid chamber in which a carrier liquid is filled; 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. In this reference, it 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 hereinafter be referred to as a prior art reference 4) discloses an ink jet recording head including: first and second supplying means for supplying types of ink having first and second densities, respectively; and controlling means for controlling 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 the controlling means. 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 nucleate boiling caused due to the heat energy is used to drive, for example, a piston-type valve or a cantilever-like valve. Furthermore, this reference 4 describes that an inflow of ink can be effectively controlled in an area where the 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 hereinafter be referred to as a prior art reference 5) discloses a structure which is similar to that in the prior art reference 2 but which does not use a third chamber for mixing a plurality of types of ink.
Unexamined Japanese Patent Publication (KOKAI) No. 156131/1997 (which will hereinafter be referred to as a prior art reference 6) 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 mixture proportion 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 hereinafter be referred to as a prior art reference 7) 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 width direction of the print paper, pixel density can be enhanced. Furthermore, 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 respective prior arts disclosed in the prior art references 1 to 6, the different types of ink are mixed in advance to be then ejected, and an amount of supply of at least one type of ink among the multiple types of ink to be mixed is controlled. Therefore, a quantity of flow of ink having a desired density or color after mixing, i.e., a volumetric flow rate per unit time varies in accordance with a change in density or color. It has been revealed that, when the volumetric flow rate (which is also referred to as a flow rate hereinafter) per unit time of the ink fluid after mixing fluctuates in accordance with a change in ratio of mixture due to density or color in this manner, the quality of a finally-formed image is prominently deteriorated.
That is, in the image forming technique adopting the conventional ink jet mode described above, a volume of droplets formed by one ejecting operation (the ejection volume) is substantially constant, whereas a liquid flow rate of the mixed ink which is newly successively supplied to an ejection port (a jet generating portion) fluctuates. For example, when a supplied flow rate of the mixed ink is large, the supplied amount of the ink exceeds a quantity of droplets which can be ejected by one ejection operation, and the liquid remaining in the ejection port is mixed in the droplets for the next pixel. Further, when a supplied flow rate of the mixed ink is small, a part of the droplets for the next pixel is disadvantageously incorporated. This adversely affects the image quality.
In the prior art disclosed in the prior art reference 7, since one nozzle ejects single-color ink, one pixel is formed by multiple (three or four or more colors) ink droplets. Therefore, it is difficult to enhance pixel density, and another problem is that improvement of the image quality is restricted.
Moreover, any one of the aforementioned conventional ink jet systems includes one ink droplet ejecting means and a driving circuit of the means, i.e., a driver circuit (hereinafter referred to as ejection driver) with respect to one ink ejection port. That is to say, each ink ejection port is separately provided with a heater and a diaphragm for imparting an ink droplet ejection energy to the port, and these components are separately driven by individual driver circuits.
As a result, the ink droplet ejecting means is set to be inoperative with respect to the ink ejection port which does not contribute to image formation even during the image formation, and it is therefore possible to selectively eject only the ink droplets necessary for the image formation. However, for this purpose, it is necessary to dispose the same number of driver circuits as the number of ink ejection
Fuji Photo Film Co. , Ltd.
Gordon Raquel Yvette
Sughrue & Mion, PLLC
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