JPH01184149A - Liquid jet recording method - Google Patents

Abstract

PURPOSE:To prevent not only the dripping of a recording liquid but also the generation of a satellite droplet, in a bubble jet type liquid jet recording method, by satisfying specific relation between an average air bubble growing speed Vb and an average ink emitting speed Vi. CONSTITUTION:Ink 31 is heated by the heating resistor 32 in an ink flow passage to generate an air bubble 33. When the length from the center line of the air bubble 33 to the end thereof is set to (r), the average value Vb of an air bubble growing speed becomes Vb=rmax/t. This speed Vb is changed by pulse voltage, a pulse width, a pulse waveform, the material quality of a heat generator, heat capacity, the specific heat of ink or the like. An ink emitting speed Vi is the speed at the center axis of an ink column and, as the factors determining Vi, there are ink viscosity, surface tension, ink temp., flow passage fluid resistance, emitting orifice fluid resistance or the like. The ink does not become a satellite droplet and is not scattered in a mist like form and the dripping thereof from an emitting orifice is prevented. The optimum emission is limited at the time when a condition of 3m/s<Vi<Vb is satisfied.

Description

DETAILED DESCRIPTION OF THE INVENTION 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 device.

Conventional non-impact recording methods have recently attracted attention because the noise generated during recording is so small that it can be ignored. Among them, high-speed recording is possible,
However, the so-called inkjet recording method, which allows recording on plain paper without the need for special fixing treatment, is an extremely powerful recording method, and various methods have been proposed, improved, and commercialized. Some have been developed, and efforts are still being made to put them into practical use.

In this type of inkjet recording method, recording is performed by causing droplets of a recording liquid called ink to fly and adhere to a recording member. There are several types of methods depending on the control method used to control the flight direction of the generated recording liquid droplets.

First, the first method is the one disclosed in USP 3060429 (Tale type method), in which /JN droplets of recording liquid are generated by electrostatic absorption, and the generated recording liquid droplets are recorded. Recording is performed by controlling an electric field in accordance with a signal to selectively attach recording liquid droplets onto a recording member.

To explain this in more detail, an electric field is applied between the nozzle and the accelerating electrode to eject a negatively charged recording liquid droplet from the nozzle, and the ejected recording liquid droplet is converted into a recording signal. Accordingly, the droplet is caused to fly between x and y deflection electrodes configured to be electrically controllable, and the droplet is selectively deposited on the recording member by changing the intensity of the electric field to perform recording.

The second method is described, for example, in USP 3596275, U
The method disclosed in SP 3298030 etc. (Swe
et method), in which droplets of recording liquid with a controlled amount of charge are generated by a continuous vibration generation method, and a --like electric field is applied to the generated droplets with a controlled amount of charge. Recording is performed on a recording member by flying between deflection electrodes.

Specifically, the orifice (discharge port) of a nozzle, which is a part of the recording head to which the piezo vibrating element is attached.
A charged electrode configured to have a recording signal applied thereto is arranged at a predetermined distance in front of the piezo vibrating element, and an electric signal of a constant frequency is applied to the piezo vibrating element to mechanically vibrate the piezo vibrating element, A small droplet of recording liquid is ejected from the ejection port. At this time, charges are electrostatically induced in the recording liquid droplet discharged by the charging electrode, and the droplet is charged with an amount of charge corresponding to the recording signal. When a droplet of recording liquid with a controlled amount of charge flies between deflection electrodes to which a constant electric field is uniformly applied, it is deflected according to the amount of charge applied.
Only the droplets carrying the recording signal are allowed to deposit on the recording member.

The third method is, for example, the method disclosed in U.S.P. 34'16153 (Hertz method), in which an electric field is applied between a nozzle and a ring-shaped charging electrode, and small droplets of recording liquid are generated by a continuous vibration generation method. This is a method that generates atomized light and records it. That is, in this method, the atomization state of droplets is controlled by modulating the electric field intensity applied between the nozzle and the charging electrode in accordance with the recording signal, and the gradation of the recorded image is produced.

The fourth method is a method (Stemme method) disclosed in, for example, USP 3,747,120, and this method is fundamentally different in principle from the above three methods.

That is, in all three methods, the droplets of recording liquid ejected from the nozzle are electrically controlled while they are in flight, and the droplets carrying the recording signal are selectively attached to the recording member. In contrast, this Stemme method
Recording is performed by ejecting small droplets of recording liquid from an ejection port in response to a recording signal.

In other words, the Stemme method applies an electrical recording signal to a piezo vibrating element attached to a recording head that has an ejection port for discharging recording liquid, and converts this electrical recording signal into mechanical vibration of the piezo vibrating element. In this method, recording is performed by ejecting small droplets of recording liquid from the ejection opening according to the mechanical vibrations and adhering them to the recording member.

These four conventional methods each have their own advantages, but there are also points that can be solved in the other method.

That is, in the first to third methods, the direct energy for generating droplets of the recording liquid is electrical energy, and the deflection control of the droplets is also electric field control.

Therefore, although the first method is simple in structure, it requires a high voltage to generate droplets, and it is difficult to use a multi-nozzle recording head, making it unsuitable for high-speed recording.

The second method allows the recording head to have multiple nozzles and is suitable for high-speed recording, but it has a complicated structure, and the electrical control of recording liquid droplets is sophisticated and difficult, and satellite dots are placed on the recording member. There are problems such as easy occurrence of.

The third method has the advantage of being able to record images with excellent gradation by atomizing recording liquid droplets, but on the other hand, it is difficult to control the atomization state and fog occurs in the recorded image. In addition, it is difficult to create a multi-nozzle recording head.
There are various problems such as being unsuitable for high-speed recording.

The fourth method has relatively many advantages compared to the first to third methods. In other words, the structure is simple, and since recording is performed by ejecting recording liquid from the ejection opening of the nozzle on-demand, it is possible to reduce the number of small droplets that fly as in the first to third methods. Second, it is not necessary to collect droplets that are not needed to record an image, and unlike the first and second methods, there is no need to use a conductive recording liquid, and the material of the recording liquid is It has great advantages such as a high degree of freedom. On the other hand, on the other hand, it is difficult to make a recording head with multiple nozzles due to problems in processing the recording head, and it is extremely difficult to miniaturize a piezoelectric vibrating element having a desired resonance number. This method has disadvantages such as that it is not suitable for high-speed recording because the recording liquid droplets are ejected into flight using the mechanical energy of the mechanical vibration of the piezoelectric vibrating element.

Furthermore, Japanese Patent Application Laid-Open No. 48-9622 (the above-mentioned US P3
No. 747120) discloses, as a modification, the use of thermal energy instead of the mechanical vibration energy provided by means such as the piezo vibration element.

That is, the above-mentioned publication describes the use of a heating coil that directly heats a liquid as a pressure increasing means in place of the piezo vibrating element in order to generate steam that causes a pressure increase.

However, in the above publication, the liquid ink in the bag-shaped ink chamber (liquid chamber), which has only one opening through which liquid ink can go in and out, is directly heated and vaporized by energizing the heating coil as a pressure increasing means. However, when discharging liquid continuously and repeatedly, it is not clear how to heat it.
There is nothing to suggest. In addition, the heating coil is located at the deepest part of the bag-shaped liquid chamber far from the liquid ink supply path, which makes the head structure complicated and requires continuous high-speed printing. For repeated use,
It is not suitable.

Moreover, with the technical content described in the above-mentioned publication, it is not possible to quickly prepare for the next liquid discharge after discharging the liquid using the generated heat, which is important in practice.

As described above, conventional methods have advantages and disadvantages in terms of structure, high-speed recording, multi-nozzle recording heads, generation of satellite dots, and fogging of recorded images. There was a restriction that it could only be applied.

Furthermore, Japanese Patent Application Laid-Open No. 55-161665 discloses that in a bubble jet liquid jet recording head, the ejection performance can be improved by setting the particle size to 5ee-1 or more.

FIG. 28 is a diagram for explaining an example of the bubble jet liquid jet recording head disclosed in the above-mentioned Japanese Unexamined Patent Publication No. 55-161665, and FIG. 28(a) is a front view of the recording head as seen from the orifice side. Partial view, FIG. 28(b) is the second
FIG. 8 is a partial cross-sectional view taken along a section indicated by a dashed line XX in FIG. 8(a).

The recording head 11 shown in the figure has a predetermined number of grooves of a predetermined width and depth at a predetermined linear density on the surface of a substrate 13 on which an electrothermal converter 12 is provided. The orifice 15 can be connected by covering it with the attached plate 14.
It has a structure in which a liquid discharge part 16 is formed.

The liquid discharge section 16 has an orifice 15 at its end for discharging droplets, and thermal energy generated by the electrothermal converter 12 acts on the liquid to generate bubbles, which expand and contract in volume. It has a heat acting part 17 which is a place that causes a rapid state change.

The heat acting part 17 is located above the heat generating part 18 of the electrothermal converter 12, and has a heat acting surface 1 in contact with the liquid of the heat generating part 18.
9 is its base.

The heat generating section 18 is a lower layer 20. provided on the substrate 13.
A heating resistance layer 21 provided on the lower layer 20. The heating resistance layer 21 is provided with electrodes 23 and 24 on its surface for supplying electricity to the core layer 21 in order to generate heat. The electrode 23 is an electrode common to the heat generating section of each liquid discharging section, and the electrode 24 is a selection electrode for selectively generating heat in the heat generating section of each liquid discharging section. It is located along the road.

The upper layer 22 isolates the heating resistance layer 21 from the liquid in the liquid discharge part 16 in order to chemically and physically protect the heating resistance layer 21 from the liquid used, and also connects the electrodes 23 and 24 through the liquid. The heating resistor layer 21 has a protective function of preventing short circuits.

The upper layer 22 has the above-mentioned functions, but
If the heat generating resistor layer 21 is liquid resistant and there is no fear that the electrodes 23 and 24 will be electrically shorted through the liquid, it is not necessary to provide the heat generating resistor layer 21 and the liquid may be directly applied to the surface of the heat generating resistor layer 21. It may also be designed as an electrothermal transducer with a structure in which the two contact with each other.

The lower layer 20 mainly has a heat flow control function.

That is, when discharging droplets, the proportion of heat generated in the heat generating resistor layer 21 being conducted to the heat acting section 17 side is as high as possible, rather than being conducted to the substrate 13 side. rear,
After the power supply to the clogged heat generating resistor layer 21 is turned off, the heat in the heat acting section 17 and the heat generating section 18 is quickly transferred to the substrate 1.
3 side to rapidly cool the liquid and generated air bubbles in the heat acting part 17.

In this way, when discharging droplets, the proportion of the heat flow towards the heat acting section 17 side is as large as possible, and when the electricity to the heat generating resistor layer 21 is turned off, the heat flow towards the substrate 13 side is as large as possible. In order to increase the ratio of In order to stabilize the droplet ejection direction, equalize the droplet ejection speed, and improve the fidelity and reliability of the response to the recording signal, it is necessary to establish the above relationship in the bubble volume change curve. All you have to do is set it and record it.

FIG. 29 shows the electrothermal transducer 12 provided in the recording head.
2 shows the change in volume of bubbles generated in the heat acting section 17 when an electrical signal with a pulse waveform indicated by symbol P is input. Now, 0N is applied to the electrothermal converter 12 at time 1o and time tf.
- When the pulse-like electric signal P is inputted to the OFF state, bubbles are generated in the heat acting part 17 at time ti, and the volume Vv of this bubble starts to increase from time ti, and reaches a maximum at time tp. Volume Vvp is reached. When the electric signal P is turned off at time tf, the volume Vv of the bubble starts to decrease after time tp.

The speed at which the bubble volume Vv decreases when the electric signal P is turned off depends on the rate of change in the bubble volume Vv over time τ□.

That is, when the electric signal P is turned off by creating a bubble volume change curve such that the average value Vv (a, / vvp) of the time rate of change during heating is 5 x 10"5 ec-1 or more. It is possible to effectively steepen the attenuation curve of the bubble volume Vv without using any special cooling means, thereby improving the discharge performance.

However, in the above-mentioned Japanese Patent Application Laid-Open No. 55-161665, only air bubbles are focused as a factor that improves ejection performance, but in reality, fluid resistance in the flow path, fluid resistance at the ejection port, ink viscosity , surface-12= There are many factors to consider, such as tension. It is not sufficient to take only air bubbles as a factor and determine conditions for improving discharge performance based on that.

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

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 liquid chamber, and the thermal energy action in the recording liquid is caused by the thermal energy action. In the liquid jet recording method, in which air bubbles are generated in the area, and the recording liquid is ejected in the form of droplets from an ejection orifice using the acting force as the volume of the air bubbles increases, and the recording liquid is attached to the recording surface to perform recording, the generation of the air bubbles is performed. ~ The average value of the growth rate until the bubble becomes the maximum due to growth ■ b The meniscus of the recording liquid in the ejection orifice portion grows into a recording liquid column, and the center of the recording liquid column until just before it becomes a recording droplet. It is characterized by satisfying the following relational expression: 3 m/s<Vi<Vb, where Vi is the average value of the growth rate of the part. Hereinafter, the present invention will be explained based on examples.

FIG. 1 is a state diagram of main parts for explaining one embodiment of the present invention, FIG. 2(a) is a diagram showing the relationship between the radius of a bubble and time, and FIG. 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. In order to determine the ejection conditions, we found the optimal conditions by repeating careful experiments in terms 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. It is something that

In the bubble jet recording head, the ink 31 is heated by the heating resistor 32 in the ink flow path to generate bubbles 33 in the ink flow path, and the increase in the volume of the bubbles 33 causes the ink 31 to be drawn from the orifice portion 34. This is what makes it spray.

The radius r of the bubble 33 is the length from the center line of the bubble to the edge of the bubble, as shown in FIG. 2(b).

vb is the average value of the bubble growth rate and is defined as vb=-. Note that vb can take different values depending on the pulse voltage applied to the heating resistor 32, pulse width, pulse waveform, material of the heating element, heat capacity, specific heat of the ink, etc. As is clear from FIG. 1, the ink ejection speed Vi is the speed at the central axis of the ink column. Factors that determine Vi include ink physical properties (viscosity 1 surface tension), ink temperature, channel fluid resistance, ejection port fluid resistance, and the like.

Bubble jet technology requires ink droplets to be ejected without satellite droplets and without scattering in the form of mist. Also, it must not be possible for the liquid to drip from the discharge port (orifice) without being discharged. The inventor is
By repeating careful experiments, it was discovered that optimal discharge without the above-mentioned problems can be obtained when the following conditions are met.

3 m/s < Vi < Vb To conduct an experiment to find such conditions, make a prototype transparent head (preferably glass such as Pyrex), synchronize the growth of bubbles with a strobe, and observe the growth by changing the phase. This can be done by

Accordingly, in the present invention, as a factor for determining the optimum ejection conditions, the conditions are determined together with Vi, which has the greatest influence on the ejection conditions, and the head is driven with this condition set. By doing so, stable ejection can be obtained.

FIG. 3 is a diagram for explaining the operation of a bubble jet head as an example of an ink jet head to which the present invention is applied, FIG. 4 is a perspective view showing an example of a bubble jet head, and FIG. Figure 6 is a perspective view when the head shown in Figure 4 is disassembled into a lid substrate (Figure 5 (a)) and a heating element substrate (Figure 5 (b)), and Figure 6 is a perspective view of Figure 5 (a). 41 is a perspective view of the lid substrate shown in FIG.
42 is a heating element substrate, 43 is a recording liquid inlet, 44 is an orifice, 45 is a channel, 46 is a region for forming a liquid chamber, 47 is an individual (independent) electrode, and 48 is a common electrode.

49 is a heating element (heater), 50 is ink, 51 is a bubble,
Reference numeral 52 denotes flying ink droplets, and the present invention can also be applied to such a bubble jet type liquid jet recording head.

First, ink jetting by a bubble jet will be described with reference to FIG. 3. (a) is a steady state, in which 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 until the surface temperature of the heater 49 rises rapidly and boiling development occurs in the adjacent ink layer, and microbubbles 51 are scattered.

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

(d) shows a state in which the bubbles have grown to their maximum, and ink 50 corresponding to the volume of the bubbles is pushed out from the orifice surface. At this time, no current is flowing through the heater 49, and the surface temperature of the heater 49 is decreasing. The maximum value of the volume of the bubble 51 is slightly delayed from the timing of applying the electric pulse.

(e) shows a state in which the bubbles 51 are cooled by ink or the like and begin to contract. At the tip of the ink column, it moves forward while maintaining the extruded speed, and at the rear end, the ink flows backward from the orifice surface into the nozzle due to the decrease in nozzle internal pressure as the bubbles contract, creating a constriction in the ink column. .

In (f), the air bubbles 51 are further contracted, and the ink comes into contact with the heater surface, causing the heater surface to be cooled even more rapidly. At the orifice surface, the external pressure is higher than the nozzle internal pressure, so the meniscus is largely moving into the nozzle. The tip of the ink column becomes a droplet and drops 5 to 1 droplets toward the recording paper.
It is flying at a speed of 0 m/see.

In (g), the air bubbles have completely disappeared in the process of refilling the orifice with ink by capillary action and returning to the state of (a).

FIG. 7 is a detailed diagram for explaining the structure of a bubble generating means using a heating resistor, in which 61 is a heating resistor, 62
63 is an electrode, 63 is a protective layer, and 64 is a power supply device. Useful materials for forming the heating resistor 61 include, for example, tantalum-3iO□ mixture, tantalum nitride, nichrome, silver-palladium alloy, Examples include silicon semiconductors and borides of metals such as hafnium, lanthanum, zirconium, titanium, tantalum, tungsten, molybdenum, niobium, chromium, and vanadium.

Among the materials constituting these heating resistors 61, metal borides are particularly excellent, and among them, hafnium boride has the most excellent properties.
This is followed by zirconium boride, lanthanum boride, tantalum boride, vanadium boride, and niobium boride.

The heating resistor 61 can be formed using the above-mentioned materials using techniques such as electron beam evaporation and sputtering. The film thickness of the heating resistor 61 is determined according to its area, material, shape and size of the heat-acting part, and actual power consumption, etc. so that the amount of heat generated per unit time is as desired. However, in the normal case, o, ooi
~5 μm, preferably 0.01 to 1 μm.

As the material constituting the electrode 62, many commonly used electrode materials can be effectively used, and specifically,
For example, Afl, Ag, An, Pt.

Examples include Cu, and these materials are used to provide a predetermined size, shape, and thickness at a predetermined location by a method such as vapor deposition.

The characteristics required of the protective layer 63 are to protect the heat generating resistor 61 from the recording liquid without preventing the heat generated by the heat generating resistor 61 from being effectively transferred 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, and zirconium oxide. It can be formed by The thickness of the protective layer 63 is usually 0.01 to 1101 L, preferably 0.1 to 5 μm, and most preferably 0.1 to 3 μm.

The recording head created as described above is supplied with recording liquid at a pressure such that the recording liquid will not be ejected from the ejection port when the heating resistor does not generate heat, and at the same time supplying the recording liquid in pulses to the electric/thermal converter according to the image signal. When a voltage was applied and recording was performed, a clear image was obtained.

FIG. 8 is a block diagram showing an example of the heating element drive circuit at that time. Reference numeral 71 denotes a known optical incoming gas sensor unit for reading, which is composed of a photodiode or the like. The image signal is processed by a processing circuit 72 consisting of a circuit such as a comparator, and then input to a 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 input image signal is discriminated between black and white in the processing circuit 72 and input to the drive circuit 73. In the drive circuit 73, the pulse width and pulse amplitude for obtaining an appropriate droplet diameter and the repetition frequency for obtaining a desired recording droplet density are converted into controlled signals to drive the recording head 74.

In addition, as another recording method that takes gradation into consideration, one is to perform recording by changing the droplet diameter, and the other is to perform recording by changing the number of recording droplets as follows. You can also do it.

First, in the recording method of changing the droplet diameter, an image signal inputted to the optical angler cuff sensor unit 71 is outputted as a drive signal with a pulse width and a pulse amplitude of each level determined to obtain the desired droplet diameter. Drive circuit 7 having multiple circuits for
The processing circuit 72 determines which of the three signal levels should be used for outputting the signal and processes the signal. In addition, in the method of changing the number of recorded droplets, the optical angler's cuff sensor section 7
The input signal to 1 is A/D converted and outputted in the processing circuit 72, and according to the output signal, the drive circuit 73 controls the recording head so that recording is performed by changing the number of ejected droplets per one input signal. Outputs a signal to drive 74.

Alternatively, a similar device may be used to supply the recording liquid to the recording head 74 at a pressure higher than the pressure at which the recording liquid overflows from the ejection port without the heating resistor generating heat, while performing electrothermal conversion. When recording was performed by applying a voltage to the body in the form of continuous repeated pulses, it was confirmed that droplets of a number corresponding to the applied frequency were ejected stably and with a uniform diameter.

From this point of view, it has been found that the recording head 74 is extremely effectively applied to continuous ejection at high frequencies.

Further, since the recording head, which is the 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. 9 is a diagram for explaining another means for generating bubbles in the recording liquid, in which 81 is a laser beam oscillator, 82 is a light modulation drive circuit, 83 is a light modulator, and 84 is a scanner. , 85 is a condenser lens, and the laser beam generated by the laser oscillator 81 is pulse-modulated in the optical modulator 82 according to the image information signal that is input to the optical modulator drive circuit 82, electrically processed, and output. be done. The pulse-modulated laser light passes through a scanner 84 and is focused by a condensing lens 85 on the outer wall of the thermal energy acting section, heating the outer wall 86 of the recording head and causing the inner recording liquid 87 to be heated. to generate air bubbles. Alternatively, the wall 86 of the thermal energy application section is made of a material that is transparent to the laser beam, and the laser beam is focused by the condensing lens 85 on the recording liquid 87 inside to directly heat the recording liquid. Bubbles may be generated by

FIG. 10 is a diagram for explaining an example of a printer using a laser beam as described above. An example is shown in which the entire area (width) is covered = 24-.

Laser light emitted from the laser oscillator 81 is guided to the entrance aperture of the optical modulator 83. In the optical modulator 83, the laser beam undergoes intensity modulation according to the image information input signal to the optical modulator 83. The modulated laser beam is reflected by a reflecting mirror 8.
8 bends its optical path toward the beam expander 89 and enters the beam expander 89 . The beam expander 89 expands the beam diameter while remaining parallel light. Next, the laser beam with expanded beam diameter is
The light is incident on a rotating polygon mirror 90 that rotates at a constant high speed. The laser beam swept by the rotating polygon mirror 90 is imaged by a condensing lens 85 on the outer wall 86 of the thermal energy acting part of the drop generator or on the recording liquid inside. As a result, air bubbles are generated in each thermal energy applying portion, and recording droplets are ejected to perform recording on the recording paper 92.

FIG. 11 is a diagram showing yet another bubble generating means. In this example, a pair of discharge electrodes 100 arranged on the inner wall side of the thermal energy application section receives high voltage pulses from a discharge device 1. This device causes an electric discharge in the water, and the heat generated by the electric discharge instantly forms bubbles.

12 to 19 are diagrams showing specific examples of the discharge electrode shown in FIG. 11, respectively. In the example shown in FIG. 12, the electrode 100 is made into a needle shape to concentrate the electric field and efficiently (
It is designed to cause a discharge (with low energy).

The example shown in FIG.

Two flat plate electrodes are used to stably generate air bubbles between the electrodes. The position of generated bubbles is more stable than needle-shaped electrodes.

The example shown in FIG. 14 is one in which the electrode has a substantially coaxial hole. The holes in the two electrodes serve as guides, making the position of the bubbles even more stable.

The example shown in FIG. 15 has a ring-shaped electrode, and is basically the same as the example shown in FIG. 14, and is a modified example thereof.

In the example shown in FIG. 16, one side is a ring-shaped electrode and the other side is a needle-shaped electrode. The ring-shaped electrode aims to stabilize the generated bubbles, and the needle-shaped electrode aims to improve efficiency by concentrating the electric field.

In the example shown in FIG. 17, one ring-shaped electrode is formed on the wall surface of the thermal energy application section. In addition to the effects of the example shown in FIG. 16, this is aimed at ease of manufacturing by forming electrodes in a two-dimensional manner on the substrate. A plurality of such planar electrodes can be easily manufactured with high density by vapor deposition (or sputtering) or photoetching techniques. Particularly effective for multi-arrays.

In the example shown in FIG. 18, the ring-shaped electrode forming portion of the example shown in FIG. 17 is shaped along the outer periphery of the electrode and is raised one step higher than the surroundings. Again, this is aimed at the stability of the generated bubbles, and is more stable than the one shown in FIG. 16 by adding a three-dimensional guide.

The example shown in FIG. 19, contrary to the example shown in FIG. 18, has a structure in which the ring-shaped electrode forming part is sunk downward from the periphery.
The generated bubbles are stably formed.

FIGS. 20 to 27 are diagrams for explaining the control mechanism when the recording head is incorporated into a recording apparatus to actually perform recording. First, referring to FIGS. 20 to 23, Each electric/thermal converter 110□, 11 according to an external signal
0□, . . . 1107 are controlled simultaneously to each discharge port 1111, 1112. . . . An example will be described in which liquid is discharged simultaneously from 111□ in accordance with an external signal. First, FIG. 20 is an overall block diagram, in which input signals from computer keyboard operations are input from an interface circuit 121 to a data generator 122. Next, a desired character in the character generator 123 is selected, and the data signals are arranged in the data generator 122 in a form that is easy to print. The data arranged in the data generator 122 is once stored in the buffer circuit 124, and is sequentially sent to the driver circuits 1251-1257 for each converter.
101° 110□, . . . 1107 are driven to eject droplets. The control circuit 126 is a circuit that controls the input/output timing of each circuit and outputs a signal instructing the operation of each circuit.

FIG. 21 shows the buffer circuit 124 shown in FIG.
In this timing chart, the buffer circuit 124 is connected to the data generator 1 as shown in FIG.
The data signals 5102 arranged in 22 are connected to a character clock 510 generated by a character generator.
1, and output signals are sequentially provided to drive circuits 1251 to 1257 at the other timing. In the example shown in Figure 20, input/output was performed using one buffer circuit, but control using multiple buffer circuits,
So-called double buffering may also be performed. That is, when one buffer circuit is inputting, the other buffer circuit outputs, and at the next timing, each buffer circuit performs the opposite operation. When double buffering is used, droplets can be ejected continuously.

In this way, seven conversion bodies 1101, 110□ are created.

...11o7 are simultaneously controlled according to the droplet ejection timing chart shown in FIG. 22, for example, and as a result, the droplets are printed from the seven ejection ports as shown by the circle in FIG. 23. This can be done by discharging. Note that each of the signals 5111 to A117 is transmitted through seven converters 110.
,,1102. . . . is a signal applied to each of 1107.

24 to 27 are diagrams for explaining an example of a control mechanism that sequentially controls each electric/thermal converter according to an external signal to sequentially discharge droplets from each discharge port. A block diagram of the entire device is shown. In FIG. 24, external signals 5130 pass through interface circuit 131 and are arranged by data generator 132 in an order convenient for printing. In the example shown in FIG. 24, in which data is printed column by column, data is read out from the character generator 133 for each column and temporarily stored in the column buffer circuit 134. Then, at the timing when column data is read from the character generator 133 and input to the column buffer circuit 1342, another data is output from the column buffer circuit 1341, and the drive circuit 135 is operated.

FIG. 25 shows a timing chart explaining the operation of the buffer circuit 134. The column data signal output from the drive circuit 135 is transmitted to each converter 110□, 1102 . . . controlled by a gate circuit 137.・・・・・・
1107 are sequentially driven. A timing chart at that time is shown in FIG. In the figure, 5141 is a character clock, 5142 is a column buffer circuit 134.
5143 is the input signal to the column buffer circuit 134□
5144 is the input signal to the column buffer circuit 1341
The signal 5145 is output from column buffer circuit 1.
The signal output from 34□ is shown. As a result, for example, according to the droplet ejection timing as shown in FIG.
Droplets are sequentially ejected from the seven ejection ports, and as shown in FIG.
The characters shown by the marks are printed. In addition, signal 5151
~5157 each has seven transformers 1101°110,
, . . . shows signals applied to each of 110□.

Although the control mechanism has been explained using an example of character printing, the same method is used when obtaining a copy image or the like.

Further, in this example, an example using a print head having seven ejection ports has been described, but it is also possible to perform printing in a similar manner when a full-line multi-orifice type print head is used.

The recording liquid used in the present invention is different from the recording liquid used in conventional recording methods, in addition to the selection of materials and the ratio of composition components so that it has the thermophysical properties and other physical properties described below. In addition to being chemically and physically stable, it also has excellent responsiveness, fidelity, and thread-forming ability, does not solidify in the liquid path, especially at the discharge port, and flows through the flow path at a speed that corresponds to the recording speed. The physical properties are adjusted so as to provide properties such as being able to do a good job, quickly fixing to the recording member after recording, having sufficient recording density, and having a good shelf life.

The recording liquid used in the present invention is composed of a liquid medium, a recording agent that forms a recorded image, and additives added to obtain desired characteristics. By selecting the type and composition ratio, it is possible to obtain any of aqueous, non-aqueous, soluble, conductive, and insulating properties.

Liquid media are broadly classified into aqueous media and non-aqueous media, but the liquid media used are those that are combined with other selected constituents so that the recorded recording liquid has the above-mentioned physical properties. The combination is selected from the following.

Such non-aqueous media include, for example, methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, 5ec-butyl alcohol, tert-butyl alcohol, isobutyl alcohol, pentyl alcohol, hexyl alcohol, heptyl alcohol. , C1-C10 alkyl alcohols such as octyl alcohol, nonyl alcohol, and decyl alcohol; For example, hydrocarbon solvents such as hexane, octane, cyclopentane, benzene, toluene, and quidylol; For example, carbon tetrachloride, trichloroethylene, and tetrachloride; Halogenated hydrocarbon solvents such as chloroethane and dichlorobenzene; Ether solvents such as ethyl ether, butyl ether, ethylene glycol diethyl ether, and ethylene glycol monoethyl ether; For example, 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, and ethylene glycol monoethyl ether acetate; alcohol solvents such as diacetone alcohol;
Examples include petroleum-based hydrocarbon solvents.

These enumerated liquid media are appropriately selected and used so as to satisfy the compatibility with the recording agent and additives used and the various properties described below as a recording liquid. Two or more types may be mixed and used as appropriate within the range in which a recording liquid having the characteristics can be prepared. Moreover, these non-aqueous media and water may be mixed and used within the above conditions.

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

In addition to ensuring that the recording liquid to be prepared has the above-mentioned physical properties, the recording agent is also used to prevent sedimentation and agglomeration in liquid channels and recording liquid supply tanks due to long-term storage, as well as transport pipes and liquid channels. It is necessary to select and use materials in relation to the liquid medium and additives so as not to cause clogging. 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 poorly soluble in the liquid medium, the particles of the recording agent when dispersed in the liquid medium are It can be used if the diameter is made sufficiently small.

The recording material that can be used is appropriately selected depending on the recording member so as to fully suit the recording conditions. Recording agents include dyes and pigments.

The dye that can be effectively used is one that satisfies the properties described below for the prepared recording liquid, and examples of suitable dyes include direct dyes as water-soluble dyes, basic dyes, and acidic dyes. In addition to dyes, soluble vat dyes, acidic mordant dyes, mordant dyes, sulfur dyes as water-insoluble dyes, vat dyes, alcoholic dyes, oil-soluble dyes, disperse dyes, thren dyes, naphthol dyes, and reactive dyes. The dye is selected from 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, Resolin Lil Blue PRL, Resolin Yellow PCG, Resolin Pink PRR, Resolin Green PB (manufactured by Bayer), and Sumikaron Blue 5.
-BG, Sumikaron Red E-EBL, Sumikalon Yellow E-40L, Sumikalon Brilliant Blue 5-B
L (manufactured by Sumitomo Chemical), Diamond Mirror Yellow -HG-
8E, Diamond Thread BN-8E, (manufactured by Mitsubishi Kasei), Kayalon Polyester Light Flavin 4GL,
Kayalon Polyester Blue 3R-8F, Kayalon Polyester Yellow YL-8E, Kaya Set Turquis Blue 776, Kaya Set Yellow 902, Kaya Set Red 026, Prodion Red H-2B, Prodion Blue H-3R (Japanese version) underside of leaves), Rebafix Golden Yellow P-R, Rebafix Pril Red P-
B, Revafix Pril Orange P-GR (manufactured by Buyer), Sumifix Yellow GR8, Sumifix B, Sumifix Pril Red BS, Sumifix Pril Blue PB, Direct Black 40 (manufactured by Jumin Chemical), Diamirror Brown 3G , Diamirror Yellow G, Diamirror Blue 3R, Diamirror Prill Blue B, Diamirror Prill Red BB' (manufactured by Mitsubishi Kasei), Remazol Red B, Remazol Blue 3R, Remazol Yellow GNL, Remazol Prill Green 6B (manufactured by Hoechst), Cibacron Pril Yellow, Cibacron Pril Red 40E (manufactured by Ciba Geigy), Indico, Direct Tape Black E-Ex, Diamine Black BH, Congo Red,
Serious Black BH, Orange ■, Amido Black I
OB, Orange R○, Metaneal Yellow, Pictoria Scarlet, Nigrosine, Diamozide Black PB
B (manufactured by Ege), Diacit Blue 3G, Diacit Fast Green GW, Diacit Milling Navy Blue R, Indanthrene (manufactured by Mitsubishi Kasei), Zapon dye (manufactured by BASF), Orazole dye (q
IBA), Lanasin dye (Mitsubishi Kasei), Diacrylic Orange RL-E, Diacrylic Brilliant Blue 2B-E, Diacrylic Turquis Blue BG-E (Mitsubishi Kasei), etc. Those given to the recording liquid to be prepared can be preferably used.

These dyes are appropriately selected as desired and used after being dissolved or dispersed in the liquid medium used.

As pigments that can be effectively used, many of inorganic pigments and organic pigments are suitably 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, Guinée green, titanium white, zinc white, and zinc white. Handle, chromium oxide green, red lead, cobalt oxide, 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.

Most of the organic pigments are classified as dyes and often overlap with dyes, but specifically, the following are preferably used.

(a) Insoluble azo type (naphthol type) Brilliant Carmine BS, Lake Carmine FB, Brilliant Fast Scarlet, Lake Red 4R, Rose Red, Permanent Red R, Fast Red FG
R, Lake Bordeaux 5B, Vermilion N001, Vermilion N082, Toluidine Maroon.

(b) Insoluble azo type (anilide type) Diazo Yellow, Fast Yellow G, Fast Yellow 10G, Diazo Orange, Palkan Orange, Balazolone Red.

(c) Soluble Azo Lake Orange, Brilliant Carmine 3B, Brilliant Carmino 6B, Brilliant Scarlet G, Lake Red C, Lake Red D, Lake Red R, Watching Red, Lake Bordeaux 10B, Bon Maroon L
, Bonmaroon M0 (d) Phthalocyanine-based Phthalocyanine Blue, Fast Sky Blue, Phthalocyanine Green.

(e) Dyeing Lake Yellow Lake, Eosin Lake, Rose Lake, Violet Lake, Blue Lake, Green Lake, Sepia Lake.

(f) Mordant system Alizarin Lake, Madakamine.

(g) Vat-dyed type Indanlene series, Fast Blue Lake (GGS).

(h) Basic dye lake system 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 determined based on conditions such as clogging of the liquid path, drying of the recording liquid in the liquid path, bleeding when applied to the recording member, and drying speed in addition to the formulation. The recording agent is usually 1 to 50 parts by weight, preferably 3 parts by weight, based on 100 parts of the liquid medium.
~30 parts, optimally 5 to 10 parts.

When the recording liquid is a dispersion system (a system in which the recording agent is dispersed in a liquid medium), the particle size of the dispersed recording agent depends on the type of recording agent, recording conditions, inner diameter of the liquid path, ejection opening diameter, and recording member. It is determined as desired depending on the type of recording agent, but if the particle size is too large, sedimentation of the recording agent particles may occur during storage, resulting in uneven density or clogging of the liquid path. This is undesirable because it may cause density unevenness in the recorded image.

Taking this into consideration, the particle size of the recording agent used as a dispersion recording liquid is usually 0.01 to 30μ, preferably 0.01 to 20μ, and optimally 0.01 to 8μ. It is desirable to Furthermore, the particle size distribution of the dispersed recording agent is preferably as narrow as possible, and is usually D±3μ,
A preferable value is D±1.5μ (where D represents the average particle size).

Examples of the additives used include viscosity modifiers, surface tension modifiers, PH modifiers, resistivity modifiers, wetting agents, infrared absorbing exothermic agents, and the like.

In addition to obtaining the above-mentioned physical property values, the viscosity modifier and surface tension modifier must also be able to flow through the liquid path at a sufficient flow rate depending on the recording speed, and prevent the recording liquid from going around at the discharge port of the liquid path. It is added for the purpose of preventing bleeding (spreading of the spot diameter) when applied to a recording member.

The viscosity modifier and surface tension modifier are selected from commonly known agents as long as they are effective and do not adversely affect the liquid medium and recording material used, so as to satisfy the desired properties. used.

Specifically, viscosity modifiers include 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 suitable examples.

Surface tension modifiers that are suitably selected and used as desired include anionic, cationic, and nonionic surfactants, and specifically, as anionic surfactants, polyethylene glycol ether sulfate, polyethylene glycol ether sulfate, Ester salts, cationic types such as poly2-vinylpyridine derivatives, poly4-vinylpyridine derivatives, etc., nonionic types such as polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl ester, polyoxyethylene sorbitan monoalkyl Examples include ester, polyoxyethylene alkylamine, and the like.

In addition to these surfactants, amine acids such as jetanolamine, propatoolamine, and morpholinic acid, basic substances such as ammonium hydroxide and sodium hydroxide, and substituted pyrrolidones such as N-methyl-2-pyrrolidone. etc. can also be used effectively.

These surface tension modifiers do not adversely affect each other or other constituents, and provide the above-mentioned physical properties to the recording liquid being formulated, so that a recording liquid having a desired value of surface tension is formulated. If necessary, two or more types may be mixed and used within the range specified above.

The amount of these surface tension adjusters to be added is determined as appropriate depending on the type, other constituent components of the recording liquid to be prepared, and the desired recording properties. , usually 0.0001 to 0.1
Parts by weight, preferably 0.001 to 0.01 parts by weight.

The pH adjuster is used to maintain a predetermined pH value in order to maintain the chemical stability of the prepared recording liquid, for example, to prevent changes in physical properties due to long-term storage and to prevent sedimentation and aggregation of the recording agent and other components. It is added at the right time and in an appropriate amount within the range that does not deviate from the various characteristic values.

As the pH adjuster suitably used in the present invention,
Almost any pH can be used as long as it can control the pH value to a desired level without adversely affecting the recording liquid being prepared.

Specific examples of such pH adjusters include lower alkanolamines, monovalent hydroxides such as alkali metal hydroxides, and ammonium hydroxide.

These pH adjusters are added in a necessary amount so that the recording liquid to be prepared has a desired pH value within a range that does not deviate from the above-mentioned physical property values.

The lubricant to be used is one that is more effective than those commonly known in the technical field related to the present invention, especially one that is thermally stable, as long as the recording liquid to be prepared does not deviate from the various physical properties listed below. are preferably used. Specific examples of such lubricants include polyalkylene glycols such as polyethylene glycol and polypropylene glycol; alkylene glycols in which the alkylene group has 2 to 6 carbon atoms such as butylene gellicol and hexylene glycol; for example, ethylene Lower alkyl ethers of diethylene glycol such as glycol methyl ether, diethylene glycol methyl ether, and diethylene glycol ethyl ether; Glycerin; Lower alcohol oxytriglycols such as methoxytriglycol and ethoxytriglycol; N-vinyl-2-
Examples include pyrrolidone oligomer; and the like.

These lubricants are added in the required amount as desired so that the recording liquid satisfies the desired characteristics.
The amount added is usually 0.1-1 based on the total weight of the recording liquid.
0 wt%, preferably 0.1-8 wt%, optimally 0.2
It is desirable that the content be ~7wt%.

In addition to being used alone, the above lubricants may be used in combination of two or more types provided that they do not adversely affect each other.

In the recording liquid used in the present invention, the above-mentioned additives are added in necessary amounts as desired, and in addition, additives that have excellent formation properties and film strength of a recording liquid film when attached to a recording member are used. For example, resin polymers such as alkyd resins, acrylic resins, acrylamide resins, polyvinyl alcohol, and polyvinylpyrrolidone may be added.

The recording liquid used in the present invention has specific heat, coefficient of thermal expansion, thermal conductivity, viscosity,
When recording using surface tension, pH, and charged recording droplets, it is desirable that the composition be prepared so that characteristic values such as surface tension, pH, and specific resistance fall within the range of characteristic conditions.

That is, these characteristics have important relationships with the stability of stringing phenomenon, responsiveness to thermal energy action, fidelity, image density, chemical stability, fluidity in liquid channels, etc. Therefore, in the present invention, it is necessary to pay sufficient attention to these matters when preparing the recording liquid.

It is desirable that the above-mentioned properties of the recording liquid that can be effectively used in the present invention be as shown in Table 1 below, and all of the listed physical properties are shown in Table 1. It is not necessary to satisfy such numerical conditions; it is sufficient that some of these physical properties take values that satisfy the conditions in Table 1, depending on the required recording characteristics. It is desirable that the specific heat, thermal expansion coefficient, thermal conductivity, viscosity, and surface tension be defined by the values shown in Table 1. Of course, it goes without saying that the more of the above-mentioned properties of the prepared recording liquid that satisfy the values shown in Table 1, the better the recording will be.

Effects in Table 1 As is clear from the above explanation, according to the present invention, the average value of the growth rate from bubble generation to bubble growth to the maximum bubble is Vi is the average growth rate of the center of the recording liquid column until it grows into a recording liquid column and just before it becomes a recording droplet.
When 3 m/s'< Vi < V
Since the head is driven under conditions such that the relational expression b is satisfied, the recording liquid can be stably ejected.

[Brief explanation of the drawing]

1 and 2 are main part configuration diagrams for explaining an embodiment of the present invention, and FIG. 3 is an explanation of the operation of a bubble jet head as an example of an inkjet head to which the present invention is applied. Figure 4 is a perspective view showing an example of the bubble jet head, Figure 5 is an exploded perspective view, Figure 6 is a view of the lid substrate from the back, and Figure 7 is a diagram showing the heating resistor. 8 is a block diagram illustrating an example of a heating element drive circuit, and FIG. 9 is a diagram illustrating an example of a bubble generating means using laser light. FIG. 10 is a diagram for explaining an example of a printer, FIG. 11 is a diagram for explaining an example of a bubble generating means using electric discharge, and FIGS. 11 to 19 are diagrams for explaining an example of a printer. , FIGS. 20 to 23, and 24 to 27 are diagrams showing specific examples of the discharge electrodes shown in FIG. 10, respectively,
FIGS. 28 and 29 are diagrams for explaining a control example when a recording head is incorporated into a recording apparatus to perform recording, respectively, and FIGS. 28 and 29 are diagrams for explaining the prior art. 31... Recording liquid, 32... Heating element, 33... Bubbles, 34 Orifice, 35... Recording liquid about to be discharged. Total of 4 helmets (false) Seikiri Hani Wagiri (Q) X Co28 Figure 29

Claims (1)

[Scope of Claims] 1. A means for generating thermal energy for applying thermal energy to the recording liquid in the liquid chamber, and generating bubbles in the thermal energy acting portion of the recording liquid by the action of the thermal energy; In the liquid jet recording method, in which the recording liquid is ejected as a droplet from an ejection orifice by the acting force associated with the increase in the volume of the bubble, and is attached to the recording surface to perform recording, the bubbles are generated and grown until they become the largest bubble. The average value of the growth rate of the recording liquid in the ejection orifice portion is Vb, and the average value of the growth rate of the center of the recording liquid column until just before the meniscus of the recording liquid grows into a recording liquid column and becomes a recording droplet is Vb.
A liquid jet recording method characterized by satisfying the following relational expression, where i is 3 m/s<Vi<Vb.