JPH0653415B2 - Liquid jet recording method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a liquid jet recording method, and more particularly to a recording method using a bubble jet type liquid jet recording apparatus.

Prior Art The non-impact recording method has recently attracted interest in that noise generation during recording is negligibly small. Among them, high-speed recording is possible,
The so-called inkjet recording method, which can record on plain paper without requiring a special fixing process, is an extremely powerful recording method. Various methods have been proposed and commercialized with improvements. Some have been made, while others are still trying to be put into practical use.

Such an inkjet recording method is one in which droplets of a recording liquid, so-called ink, are ejected and adhered to a recording member to perform recording. The method is roughly classified into several methods according to a control method for controlling the flight direction of the generated recording liquid droplets.

First, the first method is disclosed in, for example, U.S. Pat. No. 30,60429 (Tele type method), in which droplets of a recording liquid are electrostatically attracted to generate a recording liquid droplet. The electric field is controlled according to the recording signal, and the recording liquid droplets are selectively deposited on the recording member to perform recording.

This will be described in more detail. An electric field is applied between the nozzle and the acceleration electrode to eject uniformly charged droplets of the recording liquid from the nozzle, and the ejected droplets of the recording liquid are used as recording signals. Accordingly, recording is performed by flying between xy deflection electrodes configured to be electrically controllable, and selectively depositing small droplets on the recording member according to changes in the electric field strength.

The second method is disclosed in, for example, US Pat. No. 3,596,275, US Pat.
(t method), a droplet of the recording liquid whose charge amount is controlled is generated by the continuous vibration generation method, and the generated droplet whose charge amount is controlled is applied with a uniform electric field. Recording is performed on the recording member by flying between the deflection electrodes.

Specifically, a nozzle orifice (ejection port) which is a part of a recording head provided with a piezoelectric vibration element.
The charging electrodes configured so that the recording signal is applied in front of are arranged a predetermined distance apart, and the piezoelectric vibrating element is mechanically vibrated by applying an electric signal of a constant frequency to the piezoelectric vibrating element, A small droplet of recording liquid is ejected from the ejection port. At this time, electric charges are electrostatically induced in the recording liquid droplets ejected by the charging electrodes, and the droplets are charged with an electric charge amount corresponding to the recording signal. The droplets of the recording liquid of which the charge amount is controlled are deflected according to the added charge amount when flying between the deflection electrodes to which a constant electric field is uniformly applied,
Only the droplets carrying the recording signal can be deposited on the recording member.

A third method is a method (Hertz method) disclosed in, for example, US Pat. No. 3,416,153, in which an electric field is applied between a nozzle and a ring-shaped charging electrode to generate a small amount of recording liquid by a continuous vibration generation method. It is a method of recording by generating and atomizing drops. That is, in this method, the atomization state of the small droplet is controlled by modulating the electric field strength applied between the nozzle and the charging electrode according to the recording signal, and the gradation of the recorded image is produced and recording is performed.

The fourth method is a method (Stemme method) disclosed in, for example, U.S. Pat. No. 3,747,120, and this method is fundamentally different in principle from the above three methods.

That is, in all of the three methods, the droplets of the recording liquid ejected from the nozzles are electrically controlled during the flight, and the droplets carrying the recording signal are selectively deposited on the recording member. On the other hand, the Stemme method is used to perform recording by ejecting and ejecting a small droplet of recording liquid from an ejection port according to a recording signal.

In other words, the Stemme method applies an electrical recording signal to a piezoelectric vibrating element attached to a recording head having a discharge port for ejecting a recording liquid, and converts this electrical recording signal into mechanical vibration of the piezoelectric vibrating element. Instead, recording is performed by ejecting and ejecting a small droplet of the recording liquid from the ejection port according to the mechanical vibration and adhering it to the recording member.

These four conventional methods have their respective characteristics, but there are some points that can be solved in the other.

That is, in the first to third methods, the direct energy for generating the droplet of the recording liquid is electric energy, and the deflection control of the droplet is electric field control. Therefore, the first method is simple in construction, but it requires high voltage to generate small droplets, and it is difficult to form the recording head with multiple nozzles. Therefore, the first method is not suitable for high-speed recording.

The second method allows the recording head to have multiple nozzles and is suitable for high-speed recording, but it is complicated in structure, and it is difficult and difficult to electrically control the recording liquid droplets. There is a problem that dots are likely to occur.

The third method has the feature that an image with excellent gradation can be recorded by atomizing recording liquid droplets, but on the other hand, it is difficult to control the atomized state, and fog occurs in the recorded image. And it is difficult to make the recording head multi-nozzle,
There are various problems such as being unsuitable for high-speed recording.

The fourth method has relatively many advantages as compared with the first to third methods. That is, the structure is simple, and since the recording liquid is discharged from the discharge port of the nozzle on-demand to perform recording, the droplets ejected and ejected as in the first to third methods are ejected. Medium, there is no need to collect small droplets that were not needed for image recording, and there is no need to use a conductive recording liquid as in the first and second methods, and it is not necessary to use a recording liquid substance. It has great advantages such as a high degree of freedom. On the other hand, on the other hand, it is difficult to form a multi-nozzle recording head because of problems in processing the recording head, miniaturization of a piezoelectric vibrating element having a desired resonance number, and the like. However, since the recording liquid droplets are ejected and ejected by the mechanical energy of mechanical vibration of the piezoelectric vibrating element, it is not suitable for high-speed recording.

As described above, the conventional method has advantages and disadvantages in terms of configuration, high-speed recording, multi-nozzle recording head, occurrence of satellite dots and occurrence of fog in recorded images. There was a constraint that it could only be applied.

Further, in Japanese Patent Laid-Open No. 55-161665, a bubble jet type liquid jet recording head, a volume change rate of bubbles is disclosed. It is disclosed that the discharge performance is improved by setting the value of 5 × 10 ³ sec ¹ or more.

FIG. 21 is a view for explaining an example of the Babjet liquid jet recording head disclosed in the above-mentioned JP-A-55-161665, and FIG. 21A is a front view seen from the orifice side of the recording head. FIG. 21 (b) is a partial view.
FIG. 7A is a partial cross-sectional view of a section taken along a dashed line XX in FIG.

The recording head 11 shown in the figure is provided with a groove having a predetermined number of grooves of a predetermined width and depth with a predetermined linear density on the surface of a substrate 13 on which the electrothermal converter 12 is provided. The orifice 15 is formed by joining so as to cover with the plate 14.
And the liquid discharge part 16 are formed.

The liquid ejecting section 16 has an orifice 15 for ejecting liquid droplets at the end thereof, and thermal energy generated by the electrothermal converter 12 acts on the liquid to generate bubbles, which depends on expansion and contraction of the volume. The thermal action part 17 is a process that causes a rapid change in state.

The heat acting portion 17 is located above the heat generating portion 18 of the electrothermal converter 12 and is in contact with the liquid of the heat generating portion 18.
9 is the bottom surface.

The heat generating portion 18 includes a lower layer 20 provided on the substrate 13,
The heating resistor layer 21 provided on the lower layer 20 and the heating resistor layer 21 are provided with electrodes 23 and 24 on their surfaces for supplying electricity to the layer 21 to generate heat. The electrode 23 is an electrode common to the heat generating portion of each liquid ejecting portion, and the electrode 24 is a selection electrode for selecting the heat generating portion of each liquid ejecting portion to generate heat. It is located along the road.

The upper layer 22 isolates the heat generating resistance layer 21 from the liquid in the liquid discharge part 16 in order to chemically and physically protect the heat generating resistance layer 21 from the liquid used, and through the liquid, between the electrodes 23 and 24. Has a protective function of the heat-generating resistance layer 21 for preventing short circuit.

The upper layer 22 has the function as described above,
If the heat-generating resistance layer 21 is liquid-resistant and there is no fear of electrical short circuit between the electrodes 23 and 24 through the liquid, it is not always necessary to provide the liquid, and the liquid may be directly provided on the surface of the heat-generating resistance layer 21. It may be designed as an electrothermal converter having a structure of contacting with each other.

The lower layer 20 mainly has a heat flow rate control function. That is, when the droplets are ejected, the heat generated in the heating resistance layer 21 is applied to the substrate 1
The ratio of conduction to the heat acting portion 17 side is as large as possible rather than to the heat acting portion 3 side, and the heat acting portion is turned off after the energization of the clogging heat resistance layer 21 is turned off after the droplet discharge. 1
7 is provided so that the heat in the heat generating section 18 and the heat generating section 18 are quickly released to the substrate 13 side, and the liquid and the generated bubbles in the heat acting section 17 are rapidly cooled.

As described above, the ratio of the heat flow rate to the heat acting portion 17 side is as large as possible during the droplet discharge, and the heat flow rate to the substrate 13 side when the power supply to the heating resistance layer 21 is turned off. By increasing the ratio of the droplet discharge energy as much as possible, the efficiency of droplet discharge energy is improved, the thermal response is improved, the droplet discharge frequency is improved continuously, the droplet discharge frequency is improved, and the discharged droplet amount is made uniform. In order to stabilize the droplet discharge direction, make the droplet discharge speed uniform, and improve the fidelity and certainty of the response to the recording signal, the above-mentioned relationship is established in the bubble volume change curve. Recording should be executed in this manner.

FIG. 22 shows the electrothermal converter 12 provided in the recording head.
3 shows a change in the volume of bubbles generated in the heat acting portion 17 when an electric signal having a pulse waveform indicated by the symbol P is input.
Now, the electrothermal converter 12 is turned on at time t ₀ and time tf.
When the pulse-shaped electric signal P is turned off, a bubble is generated in the heat acting portion 17 at the time ti, and the volume Vv of the bubble starts to increase from the time ti and reaches the maximum at the time tp. The volume Vvp is reached. At time tf, the electrical signal P is O
When FF is performed, the bubble volume Vv begins to decrease after time tp.

The rate of decrease of the volume Vv of the bubble when the electric signal P is turned off depends on the temporal change rate of the volume Vv of the bubble at time τ ₁ .

That is, the average value of the temporal change rate during heating Is set to be 5 × 10 ³ sec ¹ or more so that the attenuation curve of the bubble volume Vv when the electric signal P is turned off can be effectively steep without using any cooling means. It is possible to improve the ejection performance.

In the technique disclosed in Japanese Patent Laid-Open No. 55-161665, the pattern size of the heating resistor is 80 μm × 200 μm and the size of the groove serving as an orifice is 80 μm × width as described in the specification. This is a technique applied to an inkjet recording apparatus having a very large orifice as compared with a normal inkjet recording apparatus, such as a depth of 80 μm.

However, in recent years, higher-definition printing quality has been required, and it has become necessary to use a very fine orifice having a cross-sectional area of 800 μm ² or less for an inkjet recording apparatus. The ink droplets ejected from such a minute orifice are larger in size than the conventional ink droplets ejected from a large orifice as described in JP-A-55-161665. Since the size is as small as 1/10 to 1/100, the conditions for ejecting ink droplets must be determined more strictly.

For example, in the above-mentioned Japanese Patent Laid-Open No. 55-161665, only bubbles are focused as a factor for improving the ejection performance, but in order to eject a large ink droplet from a large orifice, it has the largest contribution rate. Even if it is possible to set the approximate conditions by defining the volume change curve by focusing only on the bubbles, in order to eject the minute ink droplets from the minute orifice, in addition to the bubbles, It is also necessary to consider other factors that contribute to the ejection conditions. Specifically, there are many factors to be considered, such as the fluid resistance of the flow path, the fluid resistance at the ejection port, the ink viscosity, and the surface tension. Then, as the aggregation of many of these factors, the growth rate of the ink column growing from the orifice can be raised.

The present invention was made in view of the above-mentioned actual circumstances,
Particularly, in a bubble jet type liquid ejecting head having a fine orifice, the purpose is to provide a sharp ejection condition such that the recording liquid does not drip at the ejection port or generate a satellite droplet. Is.

In order to achieve the above object, the present invention has a thermal energy generating means for applying thermal energy to the recording liquid in the discharge orifice liquid chamber, and the thermal energy action in the recording liquid is caused by the thermal energy effect. Create bubbles in the area,
In a liquid jet recording method in which the recording liquid is ejected as droplets from an ejection orifice by an action force due to an increase in the volume of the bubbles and adheres to a recording surface to perform recording, an opening area of the ejection orifice is 800 μm ² or less. Yes, the average value of the growth rate until the maximum bubble is generated by the generation and growth of the bubble is Vb, and the meniscus of the recording liquid at the ejection orifice portion grows to become the recording liquid column and immediately before becoming the recording droplet. When the average value of the growth rate of the central portion of the recording liquid column is Vi, the relational expression of 5 m / s <Vb <Vi is satisfied. Hereinafter, it demonstrates based on the Example of this invention.

FIG. 1 is a state diagram of essential parts for explaining an embodiment of the present invention, FIG. 2 (a) is a diagram showing a relationship between a radius of a bubble and time, and FIG. 2 (b) is a bubble. In the figure, 31 is ink, 32 is a heating resistor, 33 is a bubble, 34 is an ejection orifice, and 35 is an ejected ink droplet that is about to be ejected. INDUSTRIAL APPLICABILITY The present invention is an ink jet having an ejection orifice having an opening area of 800 μ ² or less, which forms extremely minute ink droplets that have never been seen before.
Since high-definition printing is performed, the objective can be achieved only by considering all factors considered to contribute to ink droplet formation. Therefore, in order to determine the optimum ejection conditions, it is necessary to repeat careful experiments from the aspects of recording liquid (ink) column growth rate and bubble growth rate, which are determined by all parameters such as ink fluid resistance and ink viscosity. The conditions have been found.

In the bubble jet recording head, the heating resistor 32 heats the ink 31 in the ink flow path to generate a bubble 33 in the ink flow path, and the volume of the bubble 33 increases so that the ink 31 is discharged from the orifice portion 34. It is what makes it jet.

The radius r of the bubble 33 is the length from the center line of the bubble to the end of the bubble, as shown in FIG. Vb is the average value of bubble growth rate, Is defined by Note that Vb can take different values depending on the pulse voltage applied to the heating resistor 32, the pulse width, the pulse waveform, the material of the heating element, the heat capacity, the specific heat of the ink, and the like. The ink ejection speed Vi is the speed at the central axis of the ink column, as is apparent from FIG. Factors that determine Vi include ink physical properties (viscosity, surface tension), ink temperature, flow path fluid resistance, ejection port fluid resistance, and the like.

In the bubble jet technology for ejecting extremely minute ink droplets by using a minute ejection orifice which has not been used in the past, ink droplets are required to have no satellite droplets and do not scatter in mist form. Moreover, it is not allowed to drip from the discharge port (orifice) without discharging. The present inventor has found by repeating careful experiments that the optimum ejection free from the above problems can be obtained when the following conditions are satisfied.

5m / s <Vb <Vi An experiment to find such a condition is to make a transparent (a glass such as Pyrex is good) head as shown in FIG. Can be performed by observing while changing the phase. The liquid used here is a transparent vehicle liquid having a composition in which a dye component has been removed from the ink in order to make it easier to see bubbles and having the same physical properties as the ink. Thus, the present invention determines the condition by including Vi that most affects the discharge condition as a factor for determining the optimum discharge condition, and drives the head by setting this condition. By doing so, stable ejection can be obtained.

Table 1 shows an example of the study results. The ejection performance in Table 1 is the ejection performance when continuously driven at 5 KHz, and the liquid used is a transparent vehicle liquid.

FIG. 4 is a diagram for explaining the operation of a bubble jet head as an example of an inkjet head to which the present invention is applied, FIG. 5 is a perspective view showing an example of a bubble jet head, and FIG. FIG. 6 is a perspective view of the lid substrate (FIG. 6 (a)) and the heating element substrate (FIG. 6 (b)) constituting the head shown in FIG. 5 when disassembled. 4 is a perspective view of the lid substrate shown in FIG. 2 from the back side, in which 41 is a lid substrate, 42 is a heating element substrate, 43 is a recording liquid inlet, 44 is an orifice, and 4 is an orifice.
5 is a flow path, 46 is a region for forming a liquid chamber, 47 is an individual (independent) electrode, 48 is a common electrode, 49 is a heating element (heater), 50 is ink, 51 is a bubble, and 52 is a flying ink droplet. The present invention is also applicable to such a bubble jet type liquid jet recording head. First, the ink jetting by the bubble jet will be described with reference to FIG. 4. (a) is a steady state, and the surface tension of the ink 50 and the external pressure are in equilibrium on the orifice surface.

In (b), the heater 49 is heated and heated until the surface temperature of the heater 49 rises rapidly and boiling development occurs in the adjacent ink layer, and the minute bubbles 51 are scattered.

(c) is a state in which the adjacent ink layer that is rapidly heated on the entire surface of the heater 49 is instantly vaporized to form a boiling film, and the bubble 51 is grown. At this time, the pressure in the nozzle rises by the amount of growth of the bubbles, the balance with the external pressure on the orifice surface is lost, and the ink column begins to grow from the orifice.

(d) is a state in which the bubbles have grown to the maximum, and the ink 50 corresponding to the volume of the bubbles is pushed out from the orifice surface. At this time, no current is flowing in the heater 49, and the surface temperature of the heater 49 is decreasing. Bubbles 5
The maximum value of the volume of 1 is slightly delayed from the timing of electric pulse application.

(e) shows a state in which the bubble 51 is cooled by ink or the like and starts to contract. At the tip of the ink column, the ink column moves forward while maintaining the pushed speed, and at the rear end, the ink flows backward from the orifice surface into the nozzle due to the decrease in the nozzle internal pressure due to the contraction of the bubbles, and the ink column becomes constricted. .

In (f), the bubble 51 further contracts, the ink contacts the heater surface, and the heater surface is further rapidly cooled. On the orifice surface, the external pressure is higher than the internal pressure of the nozzle, so that a large meniscus enters the nozzle.
The tip of the ink column becomes a droplet and flies toward the recording paper.

In (g), ink is supplied (refilled) to the orifice again by the capillary phenomenon and returns to the state of (a), and the bubbles are completely extinguished.

FIG. 8 is a detailed view for explaining the structure of the bubble generating means using a heating resistor, in which 61 is a heating resistor and 62 is a heating resistor.
Is an electrode, 63 is a protective layer, 64 is a power supply device, and useful materials for the heating resistor 61 include, for example, a mixture of tantalum-SiO ₂ , tantalum nitride, nichrome, silver-palladium alloy, Examples thereof include silicon semiconductors and borides of metals such as hafnium, lanthanum, zirconium, titanium, tantalum, tungsten, molybdenum, niobium, chromium and vanadium.

Among the materials forming the heating resistor 61, the metal boride can be mentioned as an especially excellent one, and hafnium boride has the most excellent characteristic among them.
The order is zirconium boride, lanthanum boride, tantalum boride, vanadium boride, and niobium boride.

The heating resistor 61 can be formed by using a method such as electron beam evaporation or sputtering using the above materials. The film thickness of the heating resistor 61 is determined according to the area, the material, the shape and size of the heat-acting portion, and the actual power consumption so that the amount of heat generated per unit time is as desired. However, in the normal case 0.001 to 5
μm, preferably 0.01 to 1 μm.

As the material for forming the electrode 62, many of the commonly used electrode materials are effectively used, and specifically,
For example, Al, Ag, Au, Pt, Cu, etc.
These are used to provide a predetermined size, shape, and thickness at a predetermined position by a method such as vapor deposition.

The characteristic required for the protective layer 63 is that the heat generating resistor 61 is protected from the recording liquid without hindering effective transfer of the heat generated by the heat generating resistor 61 to the recording liquid. Examples of useful materials for forming the protective layer 63 include silicon oxide, silicon nitride, magnesium oxide, aluminum oxide, tantalum oxide, zirconium oxide, and the like. Can be formed. The thickness of the protective layer 63 is usually 0.01 to 10 μm, preferably 0.
It is desirable that the thickness is 1 to 5 μm, optimally 0.1 to 3 μm.

The recording head prepared as described above is supplied with the recording liquid at a pressure that does not cause the recording liquid to be ejected from the ejection port when the heating resistor does not generate heat. When recording was performed by applying a voltage, a clear image was obtained.

FIG. 9 is a block diagram showing an example of a heating element drive circuit at that time, and 71 is a known optical input photosensor unit for reading which is composed of a photodiode or the like, and is connected to the optical input photosensor unit 71. The input image signal is processed by the processing circuit 72 including a circuit such as a comparator and input to the drive circuit 73. The drive circuit 73 drives the recording head 74 by controlling the pulse width, pulse amplitude, repetition frequency, etc. according to the input signal.

For example, in the simplest recording, the processing circuit 72 discriminates black and white from the input image signal and inputs it to the drive circuit 73. The drive circuit 73 converts the pulse width and pulse amplitude for obtaining an appropriate droplet diameter and the repetition frequency for obtaining a desired recording droplet density into a controlled signal to drive the recording head 74.

Further, as another recording method considering the gradation, one is to perform recording with a changed droplet diameter, and another is to perform recording with a changed number of recording droplets as follows. You can also

First, in the recording method of changing the droplet diameter, the image signal input by the optical input photosensor unit 71 is a drive signal with a pulse width and a pulse amplitude of each level determined to obtain a desired droplet diameter. Drive circuit 7 having a plurality of circuits for outputting
The processing circuit 72 discriminates which of the three levels of the signal output circuit should be used for processing. In addition, in the method of changing the number of recording droplets, the optical input photosensor unit 7 is used.
The input signal to 1 is A / D converted in the processing circuit 72 and output, and the drive circuit 73 changes the number of ejected liquid droplets per one input signal in accordance with the output signal so that printing is performed. A signal for driving 74 is output.

As another implementation method, a similar device is used to supply the recording liquid to the recording head 74 at a pressure higher than the recording liquid overflowing from the ejection port in a state where the heating resistor does not generate heat. When recording was performed by applying a voltage to the body with continuous repeated pulses, it was confirmed that a number of droplets according to the applied frequency were stably ejected and ejected with a uniform diameter.

From this point, it was found that the recording head 74 is very effectively applied to continuous ejection at high frequency.

Further, since the recording head, which is a main part of the recording apparatus, is minute, a plurality of recording heads can be easily arranged, and a high-density multi-orifice recording head is possible.

FIG. 10 is a view for explaining another means for generating bubbles in the recording liquid. In the figure, 81 is a laser oscillator, 82 is a light modulation drive circuit, 83 is a light modulator, 84 is a scanner, and 85.
Is a condenser lens, and the laser light generated from the laser oscillator 81 is transmitted to the optical modulator 82 by the optical modulator 82.
Is pulse-modulated according to the image information signal that is input to, electrically processed, and output. The pulse-modulated laser light passes through the scanner 84 and is condensed by the condenser lens 85 so as to be focused on the outer wall of the thermal energy acting portion, heats the outer wall 86 of the recording head, and the inside of the recording liquid 87. To generate bubbles. Alternatively, the wall 86 of the heat energy acting part
May be made of a material that is transparent to laser light, and condensed by the condenser lens 85 so that the recording liquid 87 therein is focused, and bubbles may be generated by directly heating the recording liquid. .

FIG. 11 is a diagram for explaining an example of the printer using the laser light as described above, in which the nozzle portion 91 has a high density (for example, 16 nozzles / mm or more), and the paper width of the paper 91.
(For example, A4 width) The integrated example is shown so as to cover the entire width.

The laser light emitted from the laser oscillator 81 is guided to the entrance opening of the optical modulator 83. In the optical modulator 83, the laser light undergoes strong and weak modulation according to the image information input signal to the optical modulator 83. The modulated laser light is reflected by the reflecting mirror 8.
The optical path is bent in the direction of the beam expander 89 by 8 and enters the beam expander 89. The beam expander 89 expands the beam diameter as it is as a flat light. Next, the laser beam with the expanded beam diameter is
It is incident on the rotary polygon mirror 90 that rotates at a constant speed at a high speed. The laser light swept by the rotary polygon mirror 90 is focused by the condenser lens 85 on the outer wall 86 of the thermal energy acting portion of the drop generator or the recording liquid inside. As a result, bubbles are generated in each thermal energy acting portion, and recording liquid droplets are ejected, and recording is performed on the recording paper 92.

FIG. 2 is a view showing still another bubble generating means. In this example, a pair of discharge electrodes 100 arranged on the inner wall side of the thermal energy acting part receives a high voltage pulse from the discharge device 101, A discharge is generated in the recording liquid, and bubbles are instantaneously formed by the heat generated by the discharge.

FIGS. 13 to 20 are views showing specific examples of the discharge electrode shown in FIG. 12, respectively. In the example shown in FIG. 13, the electrode 100 is formed into a needle shape to concentrate an electric field and efficiently.
It is designed to cause a discharge (at low energy).

In the example shown in FIG. 14, two flat plate electrodes are used so that bubbles can be stably generated between the electrodes. The position of the generated bubble is more stable than the needle-shaped electrode.

In the example shown in FIG. 15, the electrode is provided with a substantially coaxial hole. Both holes of the two electrodes serve as guides to further stabilize the position of the generated bubbles.

The example shown in FIG. 16 is a ring-shaped electrode, which is basically the same as the example shown in FIG. 15 and is a modified example thereof.

In the example shown in FIG. 17, one is a ring electrode and the other is a needle electrode. The ring-shaped electrode aims at the stability of the generated bubbles, and the needle-shaped electrode aims at the efficiency by concentrating the electric field.

The example shown in FIG. 18 is one in which one ring-shaped electrode is formed on the wall surface of the thermal energy acting portion. This aims at the manufacturing ease of forming the electrodes in a plane on the substrate in addition to the effect of the example shown in FIG. A plurality of such high-density electrodes can be easily manufactured by a technique such as vapor deposition (or sputtering) or photoetching. Especially useful for multi-arrays.

In the example shown in FIG. 19, the ring-shaped electrode forming portion of the example shown in FIG. 18 has a shape along the outer circumference of the electrode and is raised from the surroundings by one step. Again, this is aimed at the stability of the generated bubbles, and is more stable than that shown in FIG. 17 by the addition of a three-dimensional guide.

Contrary to the example shown in FIG. 19, the example shown in FIG. 20 has a structure in which the ring-shaped electrode forming portion is dropped downward from the surroundings, and again, bubbles generated stably are formed. To be done.

The recording liquid used in the present invention is the recording liquid used in the conventional recording method in addition to the selection of materials and the ratio of composition components so as to have the thermophysical property values and other physical property values described later. Similarly, it is chemically and physically stable, has excellent responsiveness, fidelity, and spinnability, does not solidify in the liquid path, especially at the discharge port, and flows at a speed according to the recording speed in the flow path. The physical properties are adjusted so that the following properties can be obtained: that after recording, fixing on the recording member is fast, recording density is sufficient, and storage life is good.

The recording liquid used in the present invention is composed of a recording agent that forms a recording image with a liquid medium and an additive that is added to obtain desired characteristics. Any of aqueous, non-aqueous, soluble, conductive, and insulating can be obtained by selecting the type and composition ratio of.

The liquid medium is roughly classified into an aqueous medium and a non-aqueous medium, and the liquid medium used is a combination with other selected constituents as the recording liquid having the above-mentioned physical property values has. Is selected in consideration of the above.

Examples of such a non-aqueous medium include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, isobutyl alcohol, pentyl alcohol, hexyl alcohol,
C1-C10 alkyl alcohols such as heptyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol; hydrocarbon solvents such as hexane, octane, cyclopentane, benzene, toluene, xylol; carbon tetrachloride, trichloro, etc. Ethylene,
Halogenated hydrocarbon solvents such as tetrachloroethane and dichlorobenzene; ether solvents such as ethyl ether, butyl ether, ethylene glycol diethyl ether, ethylene glycol monoethyl ether; and acetone, methyl ethyl ketone, methyl propyl ketone, methyl amyl ketone , Ketone solvents such as cyclohexanone; ester solvents such as ethyl formate, methyl acetate, propyl acetate, phenyl acetate, ethylene glycol monoethyl ether acetate; alcohol solvents such as diacetone alcohol; petroleum hydrocarbon solvents and the like. To be

The liquid mediums listed above are appropriately selected and used so as to satisfy the affinity with recording agents and additives to be used and the various properties described below as recording liquids. Within the range in which a recording liquid having characteristics can be prepared, two or more kinds may be appropriately mixed and used as necessary. Further, these non-aqueous media may be mixed with water under the above conditions.

Among the above-mentioned liquid media, water or water / alcohol-based liquid media are preferable in consideration of pollution, availability, preparation, and the like.

As the recording agent, the recording liquid to be prepared is made to have the above-mentioned physical properties, and in addition, sedimentation and aggregation in the liquid channel and the recording liquid supply tank due to being left for a long time, and further in the transport pipe and the liquid channel. It is necessary to select and use the material in relation to the liquid medium and the additive so as not to cause clogging of the material. From this point of view, it is preferable to use a recording agent that is soluble in the liquid medium, but even if the recording agent is dispersible or hardly soluble in the liquid medium, the particles of the recording agent when dispersed in the liquid medium are used. It can be used if the diameter is made sufficiently small.

The recording agent that can be used is appropriately selected depending on the recording member so as to sufficiently meet the recording conditions. Examples of recording agents include dyes and pigments. The dye that is effectively used is one that can satisfy the various characteristics of the prepared recording liquid described below, and preferably used are, for example, a direct dye, a basic dye, and an acidic dye as a water-soluble dye. Dyes, soluble vat dyes, acidic mordant dyes, mordant dyes, sulfur dyes as water-insoluble dyes, vat dyes, sake-soluble dyes, oil-soluble dyes,
In addition to disperse dyes and the like, it is selected from slene dyes, naphthol dyes, reactive dyes, chromium dyes, 1: 2 type complex salt dyes, 1: 1 type complex salt dyes, azoic dyes, cationic dyes and the like.

Specifically, for example, resoring ril blue PRL, resoring yellow PCG, resoring pink PRR, resoring green PB (above manufactured by Buyer), Sumikaron blue S
-BG, Sumikaron Red E-EBL, Sumikaron Yellow E-4GL, Sumikaron Brilliant Blue SB
L (Made by Sumitomo Chemical Co., Ltd.), Dianics Yellow-HG
-SE, Dianic Thread BN-SE (all manufactured by Mitsubishi Kasei), Kayaron Polyester Light Flavin 4GL,
Kayaron Polyester Blue 3R-SF, Kayaron Polyester Yellow YL-SE, Kayaset Turkis Blue 776, Kayaset Yellow 902, Kayaset Red 026, Procion Red H-2B, Procion Blue H-3R (Nippon Kayaku ), Levafix Golden Yellow P-R, Levafix Brill Red P-
B, Levafix Brill Orange P-GR (manufactured by Buyer), Sumifix Yellow GRS, Sumifix B, Sumifix Brill Red BS, Sumifix Brill Blue PB, Direct Black 40 (manufactured by Sumitomo Chemical Co., Ltd.), Diamond Mirror Brown 3G , Diamond Mirror Yellow G, Diamond Mirror Blue 3G, Diamond Mirror Brill Blue B, Diamond Mirror Brill Red BB (all manufactured by Mitsubishi Kasei), Remazole Red B, Remazole Blue 3R, Remazole Yellow GNL, Remazole Brill Green 6B ( Above Hoechst), Cibacron Brill Yellow, Cibacron Brill Red 4GE (Ciba Geigy), Indico, Direct Tape Black E
Ex, Diamin Black BH, Congo Red, Serious Black BH, Orange II, Amido Black 10
B, Orange RO, Methanyl Yellow, Victoria Scarlet, Nigrosine, Diamond Black PBB
(Above made by EG), Diaside Blue 3G, Diaside Fast Green GW, Diaside Milling Navy Blue R, Indanthrene (above made by Mitsubishi Kasei), Zabone-dye (made by BASF), Orazole (CIB)
A), Lanacin-dye (manufactured by Mitsubishi Kasei), Die Acrylic Orange RL-E, Die Acrylic Brilliant Blue 2B
Among these, those given to the recording liquid having the above-mentioned various physical properties can be preferably used from among -E, diacryl Turkis Blue BG-E (manufactured by Mitsubishi Kasei) and the like.

These dyes are used by being dissolved or dispersed in a liquid medium which is appropriately selected and used as desired.

As an effectively used pigment, many of inorganic pigments and organic pigments are preferably used. Specific examples of such pigments include inorganic pigments such as cadmium sulfide, sulfur, selenium, zinc sulfide, cadmium sulfoselenide, yellow lead, zinc chromate, molybdenum red, Guinea Green, titanium white, zinc white, and valve. Handle, chrome oxide green, red lead, cobalt individual acid, barium titanate, titanium yellow, iron black, navy blue, litharge, cadmium red, silver sulfide, lead sulfate, barium sulfate, ultramarine blue, calcium carbonate, magnesium carbonate, lead white, Examples include cobalt violet, cobalt blue, emerald green and carbon black.

As organic pigments, most of them are classified as dyes and often overlap with dyes. Specifically, the following are preferably used.

(A) Insoluble azo type (naphthol type) Brilliant Carmine BS, Lake Carmine FB, Brilliant Fast Scarred, Lake Red 4R, Para Red, Permanent Red R, Fast Red FG
R, Rake Bordeaux 5B, Vermilion NO.1, Vermilion NO.2, Toluidine Maroon.

(B) Insoluble azo type (anilide type) diazo yellow, fast yellow G, fast yellow 10G, diazo orange, vulcan orange, parazolone red.

(C) Soluble azo lake orange, brilliant carmine 3B, brilliant carmine 6B, brilliant scarlet G, lake red C, lake red D, lake red R, watching red, lake bordeaux 10B, bon maroon L, bon maroon M.

(D) Phthalocyanine type Phthalocyanine blue, fast sky blue, and phthalocyanine green.

(E) Dyeing lake type Yellow lake, Eosin lake, Rose lake, Vio red lake, Blue lake, Green lake, Sepia lake.

(F) Mordant system Alizarin lake, Madakamin.

(G) Vat dye type Induslen type, fast blue rake (GGS).

(H) Basic dye lake type Rhodamine lake, malachite green lake.

(I) Acid dye lake type Fast sky blue, quinoline yellow lake, quinacridone type, dioxazine type.

The quantitative relationship between the liquid medium and the recording agent is based on conditions such as clogging of the liquid channel in addition to mixing, drying of the recording liquid in the liquid channel, bleeding when applied to the recording member and drying speed. The recording agent is usually used in an amount of 1 to 50 parts by weight, preferably 3 to 100 parts by weight of the liquid medium.
It is desirable that the amount is -30 parts, and optimally 5-10 parts.

When the recording liquid is a dispersed system (a system in which the recording agent is dispersed in a liquid medium), the particle diameter of the dispersed recording agent depends on the type of the recording agent, the recording conditions, the inner diameter of the liquid passage, the ejection port diameter, the recording member. The size of the recording agent particles is appropriately determined according to the desired type, but if the particle size is too large, the recording agent particles settle down during storage, resulting in non-uniform concentration and clogging of the liquid path. Or, it is not preferable because a density spot appears in the recorded image.

In consideration of the above, the particle size of the recording material when it is used as a dispersion type recording liquid is usually 0.01 to 30 μm, preferably 0.
It is desirable to set it to 01 to 20 μ, and optimally 0.01 to 8 μ. Furthermore, the particle size distribution of the dispersed recording material is preferably as narrow as possible, usually D ± 3μ, and preferably D
It is desirable to be ± 1.5μ (however, D represents the average particle size).

Examples of the additives to be used include a viscosity adjusting agent, a surface tension adjusting agent, a pH adjusting agent, a specific resistance adjusting agent, a wetting agent and an infrared absorbing exothermic agent.

In addition to obtaining the above-mentioned physical property values, the viscosity adjusting agent and the surface tension adjusting agent can flow in the liquid passage at a sufficient flow rate according to the recording speed, and can prevent the recording liquid from wrapping around at the ejection opening of the liquid passage. It is added for the purpose of preventing it, preventing bleeding (expansion of spot diameter) when applied to a recording member, and the like.

The viscosity adjusting agent and the surface tension adjusting agent are appropriately selected from the conventionally known ones as long as they are effective without adversely affecting the liquid medium and the recording agent used, so as to satisfy desired properties. Used.

Specifically, as the viscosity modifier, polyvinyl alcohol, hydroxypropyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose, water-soluble acrylic resin, polyvinyl pyrrolidone,
Gum arabic starch and the like can be exemplified as preferable ones.

The surface tension adjusting agent, which is appropriately selected and suitably used according to need, includes anionic, cationic and nonionic surfactants. Specifically, polyethylene glycol ether sulfuric acid as an anionic surfactant, Ester salts and the like, cation-based poly 2-vinyl pyridine derivatives, poly 4-vinyl pyridine derivatives and the like, nonionic polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene sorbitan monoalkyl Examples thereof include esters and polyoxyethylene alkylamines.

Other than these surfactants, diethanolamine, propanolamine, amine acids such as morpholinic acid, basic substances such as ammonium hydroxide and sodium hydroxide, and substituted pyrrolidones such as N-methyl-2-pyrrolidone are also effectively used. To be done.

These surface tension adjusting agents do not adversely affect each other or other components and give the above-mentioned physical properties to the recording liquid to be prepared so that the recording liquid having a desired value of surface tension is prepared. If necessary, two or more kinds may be mixed and used within the range.

The amount of these surface tension adjusting agents added is appropriately determined depending on the type, other constituent components of the recording liquid to be prepared, and desired recording characteristics. It is usually 0.0001 to 0.1 part by weight, preferably 0.001 to 0.01 part by weight.

The pH adjusting agent has a predetermined pH value in order to prevent the chemical stability of the prepared recording liquid, for example, the change of physical properties due to long-term storage and the precipitation or aggregation of the recording agent and other components. An appropriate amount is added in a timely manner within a range that does not deviate from the various characteristic values.

The pH adjusting agent preferably used in the present invention,
As long as it can be controlled to a desired pH value without adversely affecting the prepared recording liquid, most of them can be mentioned.

Specific examples of such a pH adjusting agent include lower alkanolamines, for example, monovalent hydroxides such as allylic metal hydroxide, ammonium hydroxide and the like.

These pH adjusting agents are added in necessary amounts so that the recording liquid to be prepared has a desired pH value within the range not deviating from the above-mentioned physical property values.

As the lubricant to be used, one which is more effective than the one generally known in the technical field of the present invention, particularly a thermally stable one, in which the recording liquid to be prepared does not deviate from the various physical properties described below. What is suitable is used. Specific examples of such a lubricant include polyalkylene glycols such as polyethylene glycol and polypropylene glycol, alkylene glycols such as butylene glycol and hexylene glycol having 2 to 6 carbon atoms; for example ethylene glycol. Lower alkyl ethers of diethylene glycol such as methyl ether, diethylene glycol methyl ether and diethylene glycol ethyl ether; glycerin; lower alcohol oxytriglycol such as metoxytriglycol and ethoxytriglycol; N-vinyl-2
-Pyrrolidone oligomer; and the like.

These lubricants are added in a necessary amount as desired so as to satisfy the properties desired for the recording liquid.
The amount added is usually 0.1 to 10 w with respect to the total weight of the recording liquid.
t%, preferably 0.1 to 8 wt%, optimally 0.2 to 7 wt% is desirable.

Further, the above lubricants may be used alone or in combination of two or more under the condition that they do not adversely affect each other.

The above-mentioned additives are added to the recording liquid used in the present invention in the necessary amounts as desired, and those having excellent formability and film strength of the recording liquid film when adhered to the recording member. In order to obtain the above, a resin polymer such as an alkyd resin, an acrylic resin, an acrylamide resin, polyvinyl alcohol or polyvinylpyrrolidone may be added.

The recording liquid used in the present invention has a specific heat, thermal expansion coefficient, thermal conductivity, viscosity, and
When recording is performed using surface tension, pH and charged recording droplets, it is desirable that the characteristic values such as specific resistance are blended so as to be within the characteristic condition range.

That is, these properties have important relationships with respect to the stability of the spinning phenomenon, the responsiveness and fidelity to the action of thermal energy, the image density, the chemical stability, the fluidity in the liquid channel, and the like. Therefore, in the present invention, it is necessary to pay sufficient attention to these when preparing the recording liquid.

It is desirable that the above-mentioned various properties of the recording liquid that can be effectively used in the present invention have the values shown in Table 2 below, but all the listed physical properties are shown in Table 2. It is not necessary to satisfy the numerical conditions as described above, and it suffices that some of these physical properties have values satisfying the conditions of Table 2 depending on the required recording characteristics. However, it is desirable that the specific heat, the coefficient of thermal expansion, the thermal conductivity, the viscosity, and the surface tension are defined by the values shown in Table 2. It goes without saying that the better the recording performance, the better the number of the various properties of the prepared recording liquid satisfying the values shown in Table 2.

Effect As is clear from the above description, according to the present invention, in order to stably form a very small ink droplet with an extremely fine ejection orifice having an opening area of 800 μm ² or less, Vb is the average value of the growth rate from generation to growth until the bubble becomes the maximum, and the meniscus of the recording liquid at the ejection orifice portion grows to become the recording liquid column, and the center of the recording liquid column until just before becoming the recording droplet. When the average value of the growth rate of the area is Vi, the conditions are set so that the relational expression of 5 m / s <Vb <Vi is satisfied, and the head is driven, so that the recording liquid is stably ejected. be able to.

[Brief description of drawings]

FIG. 1 and FIG. 2 are configuration diagrams of essential parts for explaining an embodiment of the present invention, FIG. 3 is an experimental apparatus used for finding conditions of the present invention, and FIG. For explaining the operation of a bubble jet head as an example of an inkjet head to which is applied, FIG. 5 is a perspective view showing an example of a bubble jet head, FIG. 6 is an exploded perspective view,
FIG. 7 is a view of the lid substrate viewed from the back side, and FIG. 8 is a view for explaining the structure of the bubble generating means using a heating resistor.
FIG. 9 is a block diagram for explaining an example of a heating element drive circuit, FIG. 10 is a diagram for explaining an example of a bubble generating means using laser light, and FIG. 11 is an example of a printer. FIG. 12 is an explanatory diagram, FIG. 12 is a diagram for explaining an example of a bubble generating means utilizing discharge, and FIGS. 13 to 20 are specific examples of the discharge electrode shown in FIG. FIG. 21, FIG. 21 and FIG. 22 are views for explaining the prior art. 31 ... Recording liquid, 32 ... Heating element, 33 ... Bubbles, 34
...... Orifice, 35 …… Recording liquid just before discharge.

Claims (1)

[Claims] 1. A thermal energy generating means for applying thermal energy to a recording liquid in a discharge orifice liquid chamber,
Bubbles are generated in the thermal energy acting portion of the recording liquid by the thermal energy action, and the recording liquid is ejected as droplets from the ejection orifice by the action force accompanying the volume increase of the bubbles and adheres to the recording surface. In the liquid jet recording method for recording, the opening area of the discharge orifice is 8
00μm ² or less, the average growth rate until the maximum bubble by the occurrence - the growth of the bubble Vb, the meniscus of the recording liquid in the discharge orifice portion is a growing recording liquid column, the recording liquid droplets When the average value of the growth rate of the central portion of the recording liquid column until just before is Vi, the liquid jet recording method is characterized by satisfying a relational expression of 5 m / s <Vb <Vi.