Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
2000-09-20
2002-01-29
Le, N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
C347S015000
Reexamination Certificate
active
06341852
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image forming method and apparatus for producing a fluid having a predetermined density and/or a predetermined color by changing a mixture proportion of a plurality of recording liquids (inks) based on an image signal and leading the fluid to an image receiving medium to form an image.
2. Description of the Prior Art
Unexamined Japanese Patent Publication (KOKAI) No. 232440/1995 (corresponding to U.S. Pat. No. 5,841,448) discloses an ink-jet recording head, in which an optical sensor is disposed in the recording head, and ink non-ejection or defective printing is prevented by detecting presence/absence of an ink in an ink channel. This also discloses that two electrodes are disposed in an ink tank, and the presence/absence of the ink in the ink tank is detected from a change of electric resistance between the electrodes.
Moreover, a method of changing a mixture proportion of a plurality of inks to change density or color, and forming an image has already been proposed. For example, U.S. Pat. No. 4,109,282 discloses a printer in which a valve called a flap valve is disposed in a flow channel for leading two liquids, that is, clear ink and black ink onto a substrate for forming an image. The flow channel of each ink is opened/closed by displacing this valve so that two liquids are mixed in a desired density and transported 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 disposed 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 a print paper.
U.S. Pat. No. 4,614,953 discloses an ink-jet printer head apparatus by which only a desired amount of a plurality of inks having different colors and solvent is led to a third chamber and 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 the 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 provided in the liquid chamber; a nozzle connected to the liquid chamber; and a mixer for mixing the carrier liquid in this nozzle with the ink. In this reference is also disclosed that adjusting means for adjusting a mixture amount of ink to provide a desired value is provided.
Similarly, Unexamined Japanese Patent Publication (KOKAI) No. 125259/1995 discloses an ink jet recording head including: first and second supply means for supplying inks having first and second densities, respectively; and control means for controlling a supply amount of the second ink by the second supply means so that a desired ink density can be obtained.
In this reference, a micro-pump which has an exclusive heating device and is driven by its heat energy is disclosed as the control 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. Further, this reference describes that an ink inflow can effectively be controlled in an area where the inflow is particularly small by adopting an actuator consisting of shape memory alloy for use in this valve.
Unexamined Japanese Patent Publication (KOKAI) No. 207664/1991 discloses an ink jet printer having a structure similar to that in the above-mentioned U.S. Pat. No. 4,614,953, but does not use a third chamber for mixing a plurality of inks.
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 mixture ratio to obtain a diluent 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 plurality of printer heads when all-white image data, that is, data representing that 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 tone change (a tone jump) is prevented and the additional consumption of the diluent is suppressed to improve drying characteristics.
As described above, various systems of mixing a plurality of recording liquids (inks) have been proposed, but in this case ejection amounts of respective recording liquids is are strongly influenced by a viscosity change with a temperature change, an atmospheric pressure change, and the like. Therefore, it has been difficult to accurately obtain target values of density and color of the mixed liquid. In the apparatus disclosed in the above mentioned U.S. Pat. No. 5,841,448, it is possible to detect non-ejection or printing defect from the presence/absence of each recording liquid or the mixed liquid. However, there is a problem that only the presence/absence of the respective recording liquids is detected and that a subtle fluctuation in the mixture proportion of the respective recording liquids cannot be detected.
SUMMARY OF THE INVENTION
The present invention has been accomplished under the aforementioned circumstances, and a first object of the present invention is to provide an image forming method of mixing a plurality of recording liquids to generate a mixed liquid with a desired density and/or color, and transporting the mixed liquid to an image receiving medium to form an image, so that a mixture proportion is prevented from fluctuating by influences of recording liquid temperature, atmospheric pressure, and the like and image quality can be enhanced. A second object is to provide an image forming apparatus for direct use in carrying out the method.
According to the present invention, the first object is attained by an image forming method for ejecting a mixed liquid constituted by a plurality of recording liquids from an ejection port while changing supply amounts of the respective recording liquids based on an image signal, and transporting the mixed liquid to an image receiving medium to form an image, said method comprising steps of:
determining a target value of a mixture proportion of said plurality of recording liquids based on said image signal;
controlling the supply amounts of the respective recording liquids in such a manner that the mixture proportion of the recording liquids agrees with the target value;
detecting an actual value of the mixture proportion in the vicinity of a confluent position of said plurality of recording liquids; and
comparing the detected actual value with said target value to perform a feedback control of the supply amounts of the respective recording liquids in such a manner that there is no difference between both values.
In this case, the actual value of the mixture proportion can be detected in the vicinity of a position where the recording liquids are combined (confluent point or position), for example, in the vicinity of a right downstream portion. Specifically, the actual value is detected in a range of a channel length of the mixed liquid capacity for one pixel to a downstream side from the confluent point. The recording liquid can usually be regarded as a non-compressive fluid. Therefore, by detecting the mixture proportion from the confluent point until each recording liquid for one pixel is completely supplied, the supply amount of each recording liquid for one pixel can be fed back in real time. Therefore, the actual mixture proportion for eac
Fuji Photo Film Co. , Ltd.
Le N.
Nghiem Michael
Sughure Mion, PLLC
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