JPH111004A - Ink discharge apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable good printing without oozing, permeation or the like even when a characteristic of a recording medium is changed variously, by performing printing to a part where printing dots formed by ink droplets of different discharge amounts from nozzle holes are in touch with each other, by means of a system carrying out the printing from ink droplets of a smaller discharge amount earlier. SOLUTION: A substrate 18 stored in a head base 25 having a common ink chamber 24 is sealed by a nozzle plate 20 having nozzle holes 21. A plurality of ink passages 15 communicating with the common ink chamber 24 are formed at regular intervals in the upper face of the substrate 18. A terminal end of the ink passage is made a pressure chamber 12. Each ink passage communicates with the nozzle hole 21. When ink droplets are discharged, it is manipulated so that dots of ink drops of at least two different discharge amounts are printing on a paper in the order from ones of a smaller discharge amount. Accordingly, mixture of ink colors is prevented and beautiful printing dots are obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink ejecting apparatus used in an ink jet printer, which prints by making ink droplets small and flying.

[0002]

2. Description of the Related Art In recent years, ink jet printers have been widely used as output printers for home and office computers because of their quietness, high speed, and easy colorization during recording. Such ink-jet printers print ink by making ink droplets fly in small droplets and attaching them to recording paper, and are roughly classified into a continuous system and an on-demand system according to the method of generating droplets and the method of controlling the flight direction. You.

The continuous system is, for example, a system described in US Pat. No. 3,060,429, in which ink droplets are reduced electrostatically by suction, and the generated droplets are recorded as recording signals. Is controlled by controlling the electrolysis according to the condition, and a small droplet is selectively adhered to the recording paper for recording. In this recording method, a high-quality image can be provided by expressing the density gradation by changing the dot area of the recorded matter. However, since a high voltage is required for the generation of small droplets, it is difficult to form a multi-nozzle, and thus it is not suitable for high-speed printing.

The on-demand system is a system disclosed in, for example, US Pat. No. 3,447,120. In this method, a piezo-vibration element is attached to a recording head having a nozzle hole for discharging a small droplet, and an electric recording signal is added to the piezo-vibration element to change the vibration into mechanical vibration of the piezo-vibration element.
According to this mechanical vibration, small droplets are ejected from the nozzle holes and adhere to recording paper. In this scheme,
Since recording is performed by discharging ink from the nozzle holes on demand, it is not necessary to collect small droplets that are not required for image recording among small droplets that are ejected and fly, unlike the continuous method. Configuration is possible. However, it is not suitable for high-speed recording because the processing of the recording head is difficult and the miniaturization of the piezo-vibration element is extremely difficult, so that it is difficult to form a multi-nozzle. It has been.

Further, Japanese Patent Publication No. 61-59911, Japanese Patent Publication No. 62-11035, and Japanese Patent Publication No. 61-5991
Japanese Patent Application Laid-Open No. 4 (1999) -1995 describes a method in which boiling is caused by a heating resistor to cause droplets to fly.

As another example of the on-demand system, the system described in US Pat. No. 3,179,042 uses heat energy instead of mechanical vibration energy by means such as a piezoelectric vibrating element. It is based on
According to this method, the energy conversion efficiency is higher than that of a method using mechanical vibration energy, and it is said that a multi-nozzle can be easily formed.

FIG. 10 is a sectional view showing a main part of the ink discharge device. In FIG. 10, an ink tank 3 in which an ink chamber 2 into which a conductive ink 1 is supplied is provided with a pair of electrodes 4 and 5 below the liquid surface of the conductive ink 1. , 5 can be operated by a switch 7 to apply a voltage from a voltage applying means 6. Also,
A nozzle 8 is provided at one end of the ink chamber 2 and on the downstream side of the electrodes 4 and 5, and the nozzle 8 can eject ink droplets 10 onto a sheet 9 as a recording medium.

In such an ink ejection apparatus, when a voltage is applied to the electrodes 4 and 5, a current flows through the conductive ink 1, and the Joule heat causes a portion of the conductive ink 1 between the tips of the electrodes 4 and 5. Evaporates. The vaporized conductive ink 1 expands until the nozzle 8 generates a pressure sufficient to cause the ink droplets 10 to be discharged onto the paper 9, whereby the conductive ink 1 is discharged toward the paper 9. You.

[0009]

However, in such a conventional configuration, the configuration of the print dots is not mentioned at all. That is, a print dot is defined as one in which at least one ink droplet of a desired amount of one or more color adheres or penetrates on a printing object. There is a disadvantage that the next dot is hit and the color is mixed before the ink of the dot hit is fixed. For this reason, with respect to printing on the paper 9, there is a possibility that a phenomenon called “bleeding” may occur where other colors are mixed together from the boundary of the color, so that details of the printed image cannot be realized, and the resolution is reduced. Have an unfavorable effect.

Also, as described in US Pat. No. 4,931,810 and Japanese Patent Publication No. 7-84089,
There is also a configuration in which printing is performed by determining an ink ejection amount per unit area. With such a configuration, bleeding can be avoided with special paper having a water absorption amount suitable for the discharge amount.

However, the paper 9 mainly used as a recording medium has various characteristics depending on the paper quality, thickness, and the like. Therefore, if the amount of ink ejected is uniquely determined in this way, when the amount of water absorbed by the paper is large, the dots become too large and it is difficult to express details, and the reflection density is low due to the deep ink penetration. Therefore, the color of the printed matter becomes light. On the other hand, when the amount of water absorbed by the paper is small, the ink droplets accumulate on the surface of the paper and become difficult to dry, so that they are easily mixed with the adjacent ink droplets, and other colors are diffused and the color boundaries are blurred. However, it is impossible to obtain an optimum printed matter.

The problem to be solved in the present invention is to provide an ink discharge apparatus capable of performing good printing without causing bleeding even if the characteristics of the recording medium are variously changed.

[0013]

According to the present invention, there are provided a plurality of nozzle holes for discharging ink, ink discharge force generating means provided in pressure chambers provided for each of these nozzles, Control means for controlling the ink ejection force of the generation means, wherein the control means can control the amount of ink ejected from each nozzle hole by the control means. In this system, printing is performed on portions where print dots formed by different ink droplets are in contact with each other, starting with ink droplets with a small ejection amount.

According to this configuration, the small amount of ink droplets printed earlier can be dried quickly and the portion overlapping with other colors can be reduced, so that an ink ejecting apparatus capable of obtaining a printed matter without bleeding can be provided. .

[0015]

According to the first aspect of the present invention, there are provided a plurality of nozzle holes for discharging ink, an ink discharge force generating means provided in a pressure chamber provided for each of these nozzles, A control means for controlling the discharge force of the ink by the discharge force generating means, wherein the discharge amount of the ink discharged from each nozzle hole can be controlled by the control means. This is a system that executes printing on portions where print dots formed by ink droplets of different amounts contact each other, starting with ink droplets with a small ejection amount, and small ink droplets printed first dry quickly. In addition, since a portion overlapping with another color can be further reduced, there is an effect that good printing without bleeding can be performed.

According to a second aspect of the present invention, a plurality of nozzle holes for ejecting one color ink of at least two colors,
Ink discharge force generating means provided in pressure chambers provided corresponding to each of the nozzle holes, and control means for controlling the discharge force of the discharge force generating means; An ink ejection device in which the ejection amount of the ink is operable by a control means, and has a printing portion in which four or more dots of the same color are formed on a printing medium without a gap,
In addition, when the printed portion is in contact with a color different from the color constituting the printed portion, at least one of the dots in the contacting portion is smaller in the portion where the two contacting colors are in contact than the dots in the non-contacting portion. This is characterized in that the dots are formed in an amount, and the printing on the boundary portion has a small ejection amount, and thus has an effect that the fixing of the ink can be accelerated.

According to a third aspect of the present invention, the ink is conductive, and the ejection force generating means comprises at least a pair of electrodes and voltage applying means for applying a voltage to these electrodes. And 2 have the same effects as those of the inventions.

A recording apparatus to which the ink ejection apparatus of the present invention can be applied has one or a plurality of recording heads mounted on a carriage and ejects ink from the recording head while reciprocating on the front surface of the recording material in the main scanning direction. However, even in a so-called serial type recording apparatus which performs recording by feeding a recording material by a predetermined amount in the sub-scanning direction, a recording head is provided over the entire width of the recording material in the main scanning direction, and the recording material is moved in the sub-scanning direction. And a so-called line-type recording apparatus that performs recording by being sent by a predetermined amount to the printer. Also, one or a plurality of recording heads are mounted on the carriage, and the entire surface of the recording material is moved in the main scanning direction.
Also, a so-called plotter type recording apparatus that discharges ink from the recording head while moving in the sub-scanning direction and performs recording may be used.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of an ink ejection device according to an embodiment of the present invention, FIG. 2 is a longitudinal sectional view of the ink ejection device of FIG. 1, and FIG. 3 is an exploded perspective view of the ink ejection device of FIG.

1, 2 and 3, a substrate 18 is accommodated in a head base 25 in which a common ink chamber 24 is formed, and the substrate 18 is sealed by a nozzle plate 20 having a nozzle hole 21 formed therein. I have. On the upper surface of the substrate 18, a plurality of ink flow paths 15 communicating with the common ink chamber 24 are formed at regular intervals in a groove shape.
Are terminated at the pressure chambers 12, and each of these pressure chambers 12 communicates with the nozzle hole 21. A pair of electrodes 13 and 14 connected to driving voltage applying means 19 provided as a power supply are incorporated in the pressure chamber 12 of the substrate 18.

In such an ink ejection apparatus, the conductive ink 11 supplied from the common ink chamber 24 to the pressure chamber 12 is supplied to the pair of electrodes 13 and 14 by applying a voltage to the boiling bubbles 23 as in the conventional example. After the nozzle hole 2
1 is ejected as an ink droplet 22.

FIG. 4 is a schematic view showing a structure for mounting the ink discharge device to the carriage. The ink tank 28 is connected to the carriage 27 and communicates with a supply port provided with an ink filter 29 opened at the bottom of the ink tank 28. The head base 25 can be mounted on the connected ink introduction path 30. Then, as shown in FIG. 5, the carriage 27 is movably mounted on a guide shaft 33 of the printer, and is capable of printing on the paper 9 fed by the platen roller 34.

In the above configuration, the driving voltage applying means 1
When a voltage is applied between the pair of electrodes 13 and 14 by 9, a current flows through the conductive ink 11 in the pressure chamber 12.
At this time, if I (t): a current value flowing between the conductive inks 11 that changes with the passage of time from the voltage application, R: electric resistance of the conductive ink 11, and t: time from the start of the voltage application, I A Joule loss of the current represented by the integral of (t) × R × Δt from 0 to t occurs, whereby the conductive ink in the portion where the current flows self-heats. Then, boiling starts from the hottest portion of the current passing portion of the conductive ink 11, and finally boiling bubbles 23 are generated.

With the expansion of the boiling bubble 23, the current value in the conductive ink 11 becomes small because the boiling bubble 23 is an insulator and the current cannot pass therethrough. Then, the pressure of the conductive ink 11 in the pressure chamber 12 rapidly increases due to the expansion of the boiling bubbles 23, and the high-pressure conductive ink 11 moves in the direction of the nozzle hole 21 and the ink flow path 15. The high-pressure conductive ink 11 tends to move in the direction of the nozzle hole 21 and the ink flow path 15, but a sudden flow of the conductive ink 11 due to a rapid pressure change has a fluid resistance, Road 15 is nozzle hole 2
Since it is larger than 1, the rapid flow of the conductive ink 11 due to the pressure change goes to the nozzle hole 21. Accordingly, ink droplets 22 are ejected from the nozzle holes 21 and dots are formed on the paper 9.

Here, the conductive ink 11 is placed in the pressure chamber 12.
After boiling, the heat of the boiling bubbles 23 is transferred to the conductive ink 1.
1 and the electrodes 13 and 14 deprive the boiling bubble 23 of a sudden contraction. With the disappearance of the boiling bubbles 23, the conductive ink 11 in the pressure chamber 12 is agitated by the negative pressure at the time of disappearance, and a heating time of several microseconds or more is required to start boiling again from the current passage portion. I do. By the time the boiling starts, the drive voltage applying means 19 is connected to the electrodes 13 and 1.
The application of the voltage between the four portions is stopped, and unnecessary flying of ink droplets due to double boiling of the conductive ink 11 is prevented.

FIG. 6 is a diagram showing the relationship between the ink ejection amount and the applied energy in the embodiment of the present invention.

As can be seen from this relationship diagram, the electrodes 13, 1
4 has a positive correlation between the energy applied to the conductive ink 11 in the pressure chamber 12 and the amount of the ink droplet 22. Therefore, the conductive ink 1 is applied from the electrodes 13 and 14.
If the amount of energy applied to 1 is controlled, the amount of the ink droplet 22 can be changed corresponding to this amount of applied energy.

By connecting a head base 25 in which a plurality of nozzle holes 21 capable of changing the amount of the ink droplets 22 are arranged to an ink tank 28 via an ink introduction path, a print image signal is generated. Printing on the paper 9 is possible, and an operation block diagram of this printing operation is shown in FIG.

As shown in FIG. 7, when a print image is sent from a computer or the like, the print image is separated into colors such as yellow, magenta, cyan, and black that the printer has as ink. Next, the image is converted into a dither image having at least two types of dots for each color. Then, a portion A having a predetermined amount of ink per unit area is extracted, and a boundary portion between the colors of the A portion is further extracted. When the amount of ink per unit area exceeds a certain level, the ink droplets do not immediately dry, and it is clear that color mixing occurs immediately when other colors come into contact with each other.

FIG. 8 is a schematic diagram for explaining the effect of preventing a color boundary portion from bleeding in the embodiment of the present invention.

In FIG. 8, for the printing area at the boundary between one color portion indicated by the darker density and another color portion indicated by the lighter density, the ink ejection amount during normal printing Is printed with the small dots 32 operated so as to reduce the amount so as to be in the range of about 25% to 80% per dot with respect to the large dots 31 printed with.

Such a reduced value of the ink discharge amount varies depending on the characteristics of the paper 9 to be printed, as shown in Table 1. For example, in the case of the special paper having the surface of the paper 9 coated with silica or the like, the fixability is low. Since the ink absorption amount is good and the amount of reduction is 7
It may be about 0 to 80%. Further, general high-quality paper has a large amount of ink bleeding and a small amount of ink absorption, so that a reduction rate of about 25 to 40% is required.

[0033]

[Table 1]

FIG. 9 is an explanatory diagram for showing a difference in effect depending on the printing order in the embodiment of the present invention.

In the ink droplet ejection operation, the ink droplets of dots having at least two types of ejection amounts are printed on the paper 9 in ascending order of the amount, so that the ink droplets as shown in FIG. Color mixing is prevented, and beautiful printed dots without color mixing are obtained as shown in FIG.

It goes without saying that the same effect can be obtained by performing these dot processes on the printer side or on the personal computer side. In response to the print signal, the carriage 2
7 reciprocates along the guide shaft 33, and the drive voltage applying means 19 applies a drive voltage between an arbitrary pair of electrodes 13 and 14 in accordance with the position of the carriage 27, and the ink droplets 22 are continuously generated. Is attached to the sheet 9 fed by the platen roller 34, and printing on the sheet 9 by dots can be performed.

Here, the recording liquid, that is, ink, which can be applied to the ink ejection apparatus of the present invention may be water-soluble or oil-soluble, but is preferably water-soluble in consideration of odor and safety. In the ink, a dye, alcohol as a wetting agent, a water-soluble organic solvent such as glycols, a surfactant, or a mixture thereof is added.
It is preferable for controlling bleeding, drying speed, boiling state, electrode life, preventing clogging of the nozzle hole 21 and the like.

Furthermore, it is preferable to add a preservative to the ink. Specific examples of the preservative include those described on page 177 of “Inkjet recording technology” of Trikeps Co., Ltd., and Tokuya Ota, Nikkei Electronics No. 3
03, 1982.11.8, The Journal of the Institute of Electrophotography, v
ol 124, 354 (1985), written by Akio Ohwatari
Proceedings of the Non-Impact Printing Technology Symposium ”, The Institute of Electrophotography, 93 (1987), Shinichi Hirasawa.
"Do" 89 (1987), Kenji Sawaki, Textile and Industry, v
ol 47, 212, (1991) and JP-A-63-15
Materials described in JP-A-79-79 and the like can be used.

Specific examples of the composition of the recording liquid, that is, the ink, which can be used in the ink ejection apparatus of the present invention are as follows.

That is, the composition of the ink is determined by the coloring material (this is a dye; azo dye, acid dye, basic dye, direct dye, pigment; carbon black, azo lake pigment, insoluble azo pigment, condensed azo pigment, chelate azo pigment, Phthalocyanine pigment, berylen pigment, verinone pigment, atraquinone pigment, quinacridone pigment, dioxazine pigment, thioindico pigment, isoindolinone pigment, quinophthalone pigment, basic dye lake, acid dye lake, nitro pigment, aniline black, fluorescent pigment, oxidation A solvent such as water, and a solvent (ethyl alcohol, methyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-
Butyl alcohol, tert-butyl alcohol, isobutyl alcohol, lower dialkyl ethers of polyhydric alcohols such as n-pentanol, diethylene glycol, etc.) and anti-drying agents (glycerin, urea, sorbitan,
Sorbitol, inositol, chelating agent, etc.), a viscosity adjusting agent (glycerin, etc.), a surface tension adjusting agent (dieanolamine, triethanolamine, anionic surfactant, nonionic surfactant), and a pH adjusting agent ( Potassium hydroxide (KOH), sodium hydroxide (NaOH),
Dianolamine, etc.) and dispersants (proteins, natural rubbers, cellulose derivatives, natural polymers, nonionic polymers, anionic surfactants, nonionic surfactants, etc.)
Blowing agent (isopropyl alcohol, polyhydric alcohol)
And antioxidants (vitamin C, sodium sulfite, hydroquinone, pyrazolidone, hydrazine, etc.) and preservatives (alcohol, formalin, omasine sodium, etc.).

The conductive ink 11 is disclosed in
In an ink for selective ink jet printers consisting of an aqueous mixture of dyes, as described in US Pat.
Consist of an amount of hydrolyzable salt that gives the ink a specific resistance of 0 ohms ". Further, Japanese Patent Application Laid-Open No. 5-1791
No. 82, "The aqueous ink composition for ink jet recording containing water and a colorant contains a salt comprising an alkanolamine or an ethylene oxide adduct and / or a propylene oxide adduct, and a hydrogen halide." You may.

Examples of the conductivity-imparting agent that can be used for the difference in ink ejection according to the present invention include alkali metal compound salts such as lithium (Li), inorganic salts such as ammonium sulfate, lithium chloride, sodium chloride and potassium chloride, and organic salts. However, a derivative of a quaternary organic ammonium salt can be preferably used. Specific examples of the compound include monoethanolamine sulfate, diethanolamine sulfate, triethanolamine sulfate, monoethanolamine nitrate, diethanolamine nitrate, triethanolamine nitrate, monoethanolamine phosphate, diethanolamine phosphate, Triethanolamine phosphate, dimethanolamine sulfate, trimethanolamine sulfate, diethylamine sulfate, triethylamine sulfate, dimethylamine sulfate, trimethylamine sulfate, monopropylamine sulfate, dipropylamine sulfate, tripropyl Amine sulfate, phenylamine sulfate, diphenylamine sulfate, dimethyleneamine sulfate, trimethyleneamine sulfate, diethyleneamine sulfate, triethyleneamine sulfate, dipropyleneamine Salt, tripropylene amine sulfate, pyridine sulfate,
Pyrrole sulfate and the like can be mentioned.

The humectant has a higher boiling point than water,
Used to prevent drying of the nozzle tip. Specific examples of the wetting agent include alkylene glycols having an alkylene group containing 2 to 6 carbon atoms, such as polyethylene glycol, polypropylene glycol, butylene glycol, and hexylene glycol, such as ethylene glycol ethyl ether, diethylene glycol methyl ether, and diethylene glycol. Lower alkyl ethers of diethylene glycol such as ethyl ether; glycerin; The polyhydric alcohol is contained in an amount of 0.1 to 10% by weight, preferably 0.5 to 3.0% by weight. As the polyhydric alcohol becomes less than 0.5% by weight, the nozzle tip tends to be clogged due to the drying of the ink, and as the polyhydric alcohol exceeds 3.0% by weight, the ink specific resistance tends to increase. And it was confirmed that each was not preferable.

As the solvent, water and an organic solvent miscible with water can be used. Examples of the organic solvent include alkyl alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, and isopropyl alcohol; ketones or keto alcohols such as acetone and diacetone alcohol; amides such as dimethylformamide and dimethylacetamide; tetrahydrofuran; and dioxane. And the like, ether alcohols such as ethylene glycol monomethyl ether and ethylene bricol monoethyl ether, and water-soluble polymer compounds.
Water used as a solvent is contained in an amount of 30 to 80% by weight, preferably 50 to 70% by weight. 50% water by weight
When the water content exceeds 70% by weight, the water permeability exceeds 70% by weight, and the paper permeability tends to decrease.

In some cases, a surfactant, a pH adjuster, a viscosity adjuster, and the like are added to the ink for ink jet in order to adjust physical properties of the liquid.

The surface tension adjuster is added to increase the quick drying property of the ink jet ink, and at the same time, prevents evaporation of the ink jet ink. As the adjuster, it is preferable to use a water-soluble organic solvent or a surfactant. The water-soluble organic solvent may be selected from the above solvents. Specific examples of the surfactant include fatty acid salts, higher alcohol sulfates, liquid fatty oil sulfates, fatty alcohol phosphates, sulfonates of dibasic fatty acid esters, fatty acid amide sulfonates, and alkylallyl sulfones. Acid salts, formalin-condensed naphthalene sulfonates, alkylpyridium salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl esters, sorbitan alkyl esters, polyoxyethylene sorbitan alkyl esters Can be mentioned.

The pH adjuster may be any as long as it can adjust the pH to a desired value without adversely affecting the ink jet ink to be prepared. Specifically, lower pH alkanolamine, alkali metal hydroxide and the like can be used. Monohydric hydroxide, ammonium hydroxide and the like.

The viscosity modifier adjusts the viscosity of the ink-jet ink. Specifically, polyvinyl alcohol, hydroxypropylcellulose, carboxymethylcellulose, hydroxyethylcellulose, methylcellulose, water-soluble acrylic resin, polyvinylpyrrolidone, gum arabic Starch and the like.

Further, in order to reinforce the strength of the ink film when it adheres to printing paper, alkyd resin, acrylic resin, acrylamide resin, polyvinyl alcohol,
A resin polymer such as polyvinylpyrrolidone may be added. Addition of an antifungal agent is advantageous from the viewpoint of ensuring reliability during long-term storage.

As the material of the substrate 18, an insulating material such as glass and ceramic, a semiconductor, a metal whose surface is coated with a high-resistance material, a metal alloy, an insulator, and a semiconductor can be used. Potassium lime glass, soda lime glass,
Borosilicate glass, crown glass, zinc crown glass,
Soda potash glass, barium borosilicate glass, 96% silicate glass, 99.5% silicate glass, phosphate glass, low melting glass, lithium silicate glass, zinc aluminum silicate glass, zirconium silicate glass, and the like can be used. As the ceramic substrate, aluminum oxide (alumina), titanium oxide (titania), MgO.SiO ₂ (steatite) 2
MgO.SiO ₂ (holsterite), BeO (beryllia), MgO.Al ₂ O ₃ (spinel) and the like can be used.
As the semiconductor substrate, silicon, silicon carbide, diamond, germanium, or the like can be used.

The materials of the electrodes 13 and 14 include Ti group metals (Ti, Zr, Hf) and platinum group metals (Pt, Ru, R).
h, Pd, Os, Ir), refractory metals (W, Ta, M)
o), other V, Cr, Fe, Co, Ni, Nb, A
single metal such as u, Ag, Al or alloys thereof (Ni-F
e, NiCr, TiCr, etc.). In addition, these oxides (titanium oxide, hafnium oxide, tin oxide, indium oxide, and the like), nitrides (titanium nitride, chromium nitride, and the like), carbides (titanium carbide, tungsten carbide, and the like), and borides can also be used.

[0052]

According to the first aspect of the present invention, a small amount of ink droplets previously printed can be dried quickly, and a portion overlapping with other colors can be reduced, so that good printing without bleeding can be achieved.

According to the second aspect of the present invention, the printing on the boundary portion is a printing with a small ejection amount, so that good printing without bleeding can be obtained.

According to the third aspect of the present invention, similar to the first and second aspects of the invention, good printing without bleeding can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an ink ejection device according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of the ink discharge device of FIG. 1;

FIG. 3 is an exploded perspective view of the ink ejection device of FIG. 1;

FIG. 4 is a schematic diagram showing a structure for attaching the ink ejection device to a carriage.

FIG. 5 is a partially cutaway schematic view of a printer provided with an ink ejection device.

FIG. 6 is a diagram illustrating a relationship between an ink ejection amount and an applied energy according to the embodiment of the present invention.

FIG. 7 is an operation block diagram of a printing operation.

FIG. 8 is a schematic diagram for explaining the effect of preventing a color boundary portion from bleeding in the embodiment of the present invention.

FIG. 9 is an explanatory diagram for illustrating a difference in effect depending on a printing order in the embodiment of the present invention.

FIG. 10 is a cross-sectional view illustrating a main part of the ink ejection apparatus.

[Explanation of symbols]

 Reference Signs List 1 conductive ink 2 ink chamber 3 ink tank 4, 5 electrode 6 voltage applying means 7 switch 8 nozzle 9 paper 10 ink drop 11 conductive ink 12 pressure chamber 13, 14 electrode 15 ink flow path 18 substrate 19 drive voltage applying means 20 Nozzle plate 21 Nozzle hole 22 Ink droplet 23 Boiling bubble 24 Common ink chamber 25 Head base 27 Carriage 28 Ink tank 29 Ink filter 30 Ink introduction path 33 Guide shaft 34 Platen roller

Claims (3)

[Claims] A plurality of nozzle holes for discharging ink, ink discharge force generating means provided in pressure chambers provided corresponding to each of the nozzles, and an ink discharge force generated by the discharge force generating means. A control means for controlling the discharge amount of ink discharged from each nozzle hole by the control means, wherein the discharge amount from the nozzle hole is formed by mutually different ink droplets. An ink ejection apparatus, wherein printing is performed on a portion where print dots are in contact with each other, starting with an ink droplet having a small ejection amount. 2. A plurality of nozzle holes for discharging one color ink of at least two color inks, ink discharge force generating means provided in pressure chambers provided corresponding to each of the nozzle holes, and A control means for controlling the discharge force of the discharge force generation means, wherein the control means controls the discharge amount of ink discharged from each nozzle hole, wherein four or more dots of the same color are covered. The printed portion has a printed portion formed without a gap, and, when the printed portion comes into contact with a color different from the color constituting the printed portion, the two contacting colors come into contact with each other in a portion of the contacting dot. An ink ejection apparatus, wherein at least one color is a dot formed with a smaller ejection amount than a dot in a non-contact portion. 3. The ink ejection apparatus according to claim 1, wherein the ink is conductive, and the ejection force generating means includes at least a pair of electrodes and a voltage applying means for applying a voltage to these electrodes. apparatus.