System to determine integrated nucleation probability in ink...

Incremental printing of symbolic information – Ink jet – Controller

Reexamination Certificate

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C702S181000

Reexamination Certificate

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06189994

ABSTRACT:

FIELD OF THE INVENTION AND RELATED ART
The present invention relates to an analyzing method and system for bubble generation phenomenon in an ink jet recording apparatus using thermal energy, more particularly, to such a method and a system in an ink jet recording method and apparatus wherein liquid is heated to form a bubble, and the rapid volume change resulting from the bubble formation is used to eject the liquid to effect the recording.
The ink jet recording method is particularly noted these days since it is convenient to use a reduced-size recording apparatus, since it is suitable for high resolution recording and since it is suitable for high speed recording.
In such an ink jet recording apparatus, the thermal energy is applied to the liquid to form a bubble therein, and the formation of the bubble causes rapid volumetric change which makes the liquid to eject onto a recording material (recording sheet) to effect the recording.
It is very important in making an efficient design and accomplishing stabilized ink ejection in the apparatus to know the bubble formation phenomenon.
The bubble formation (nucleation) conditions in the ink jet recording method using the thermal energy can be dealt with as a problem of the initial nucleation in the boiling mechanism in liquid. It has been analyzed, heretofore, by the following two methods:
(1) method on the basis of the cavity theory;
(2) method on the basis of the spontaneous nucleation theory;
The first method (1) is based on the assumption that fine bubbles are trapped on the heating surface, and the investigation is made as to the conditions for the growth of bubbles. Typical examples of this method are disclosed in Y. Y. Hsu: Trans. ASME, J. Heat Transfer 84 (1962) pp. 207-216, for a general boiling phenomenon, and R. R. Allen, J. D. Meyer and W. R. Knight: Hewlett-Packard J. 36(1985) No. 5, pp. 21-27 for the bubble jet printer.
The second method (2) is to investigate the conditions for spontaneous formation of vapor bubble in the liquid by the ink molecular movement by heat. Typical examples of this method are disclosed in V. P. Skripov: Metastable Liquids, John Wiley & Sons, New York (1974), for a general boiling phenomenon, and Japanese Laid-open Patent Application Publication No. 206474/1984 for a jet printer.
However, the bubble formation or the nucleation of the ink in the ink jet printer using the thermal energy involves stochastic aspects. The conventional analysis may not be enough to describe the stochastic aspects.
More particularly, the conventional analysis is based on the assumption that the bubble formation starts when the temperature distribution satisfies predetermined conditions. Further particularly, in the method (1), the bubble formation start is deemed as the ink temperature distribution contacting a discrimination curve corresponding to the unstable equilibrium of the bubble: in the method (2), the bubble formation start is deemed as the temperature of the ink in contact with the heating surface reaching the superheat critical temperature.
The inventor's investigations have revealed that the bubble generation start in an ink jet process using the thermal energy is not of such a one point value nature, but it is of the stochastic nature. Even if the same temperature distribution is given, the bubble generation sometimes occurs, and sometimes not. The bubble generation mechanism may not be understood without introduction of the stochastic aspects. In the conventional designing of the ink jet printer using the thermal energy and the evaluation thereof, the trial and error method has to be used due to the uncertainty of the bubble generation phenomenon, and in order to avoid incomplete bubble generation, the design has to include much more than enough margins.
SUMMARY OF THE INVENTION
It is a principal object of the present invention to provide an analyzing method and a system for bubble generation phenomenon in an ink jet recording apparatus using thermal energy, by which the stochastic characteristics can be quantitatively provided.
It is another object of the present invention to provide an analyzing method and system for allowing easier designing of an ink jet recording head, so that a good ink jet recording head can be quickly designed.
It is a further object of the present invention to provide an analyzing method and system by which an ink jet recording head having necessary and sufficient performance can be easily designed when design conditions are given.
According to an aspect of the present invention, there is provided a method for determining an integrated nucleation probability in a jet recording method using thermal energy, wherein a nucleation rate dependent on a temperature of ink is integrated with time from the start of heating of the ink in a predetermined region on a heater for heating the ink.
Accoording to another aspect of the present invention, there is provided a jet recording method using thermal energy to generate a bubble to eject ink to effect recording, wherein an integrated nucleation probability of the bubble generation is determined by integrating a nucleation rate dependent on a temperature of the ink with time from a start of heating of the ink in a predetermined region on the heater, and the method is designed using the thus determined integrated nucleation probability.
According to a further aspect of the present invention, there is provided, an ink jet recording apparatus, comprising: means for retaining ink; an outlet through which the ink is discharged; a heater for heating the ink through the outlet; wherein said apparatus is designed using an integrated nucleation probability determined by integrating a nucleation rate dependent on a temperature of the ink with time from start of heating of the ink in a predetermined region on the heater.
According to a yet further aspect of the present invention, there is provided a system for analyzing a bubble generation phenomenon in an ink jet recording method using thermal energy, comprising: a data input port; memory means for storing a homogeneous nucleation rate; memory means for storing a heterogeneous nucleation rate; memory means for storing an integrated nucleation probability; a program for calculating the integrated nucleation probability in accordance with data from said input port; a central processing unit for controlling said memory means and execution of said program; and a data output port for results of calculation.


REFERENCES:
patent: 4219877 (1980-08-01), Vladimirov
patent: 4241406 (1980-12-01), Kennedy
patent: 4321688 (1982-03-01), Sado
patent: 4723129 (1988-02-01), Endo
patent: 4734869 (1988-03-01), Mickowski
patent: 4872028 (1989-10-01), Lloyd
patent: 11170 (1983-01-01), None
Allen et al; Thermodynanics and Hydrodynamics of Thermal Ink Jets; Hewlett-Packard Journal, vol. 36, May 1985, No. 5, Table of Contents and pp. 21-27.
Hsu, “On the Size Range of Active Nucleation Cavities on a Heating Surface”, Journal of Heat Transfer, Aug. 1962, pp. 207-216.
Ward et al., “On the Thermodynamics of Nucleation in Weak Gas-Liquid Solutions”, Journal of Basic Engineering, Dec. 1970, pp. 695-704.
Bender et al., “Advanced Mathematical Methods for Scientists and Engineers”, McGraw-Hill 1978, Table of Contents and pp. 484-543.

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