JPH01184150A - Liquid jet recording head - Google Patents

Abstract

PURPOSE:To generate a stable air bubble, in a bubble jet type liquid jet recording head, by forming a heat energy generating means for generating the air bubble on a substrate having at least a double-layer structure and specifying the heat conductivity ratio of two layers constituting the substrate. CONSTITUTION:A heat generator 12, electrodes 13, 14 and a protective film 15 are formed on a substrate 11 consisting of layers (a), (b). Immediately after a pulse signal is applied to the heat generator 12, the layer (a) gives heat toward a recording liquid as much as possible to instantaneously generate an air bubble. Immediately thereafter, the heat of the layer (a) is conducted to the layer (b) and the air bubble generating part is desirably cooled instantaneously. That is, when the heat conductivity of the layer (a) is set to A and that of the layer (b) is set to B, good emitting capacity is obtained when a condition of 5<=B/A is satisfied and, further, it is desirable to set 8<=B/A. As a material satisfying this condition, for example, a metal material such as Zn or Al, a ceramics material such as alumina or a semiconductive material such as Si or Ge is pref. as the layer (b). As the layer (a), a glass film or a SiO2 film is pref.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid jet recording head, and more particularly to a bubble jet type liquid jet recording head.

The non-impact recording method has recently attracted attention because it generates negligible noise during recording. 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, for example, USP 3060429 (Tele type method), in which droplets of recording green liquid are generated by electrostatic absorption, and the generated droplets of recording liquid 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 the 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. 3416153 (Hertz method), in which an electric field is applied between a nozzle and a ring-shaped charged electrode, and small droplets of recording liquid are generated by a continuous vibration generation method. This method records by atomizing 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, for example, the method disclosed in USP 3747120 (Stemme method), 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, it is difficult to make the recording head multi-nozzle because there are problems in processing the recording head, and it is extremely difficult to miniaturize the piezoelectric vibrating element having the desired resonance number. This method has drawbacks such as that it is not suitable for high-speed recording because the recording liquid droplets are ejected and ejected in 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 USP
No. 3,747,120) describes, 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 a so-called bubble jet liquid jet recording device that uses a heating coil that directly heats liquid as a pressure increasing means instead of a piezo vibrating element to generate steam that causes a pressure increase. There is.

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.

Further, Japanese Patent Application Laid-Open No. 55-123478 proposes providing a thermal energy generating means in a so-called bubble jet liquid jet recording device on a substrate having a thin film of low thermal conductivity.

FIG. 28 is a diagram for explaining in detail the thermal energy invention disclosed in the above-mentioned Japanese Unexamined Patent Publication No. 55-123478. A heating element layer 4 and an electrode layer 5 for applying a signal from the outside are further laminated. In the figure, the part H is the heat generating part. Further, 6 is a protective film, which is used for the purpose of protecting the heating element layer, electrodes, etc., or for insulation when the recording medium liquid comes into direct contact with the nuclear heating resistor.
Established as necessary. Examples of the material of the substrate 2 include metals such as A Q g Cu and ceramics such as AQ2○3. The material for the thin film to be laminated on the substrate must not be subject to thermal deterioration within the elevated temperature range near the heating element layer, and must be able to form a uniform layer.
0.1-10μ for improving responsiveness, energy efficiency, etc.
The material is required to be able to easily form a layer of about m, and to have sufficient adhesion to other layers (heat generating layer, substrate, etc.) in a laminated state. Further, those having a thermal conductivity value of 0.6 kcal/mhr°C or less, preferably 0,05-0,4 kcal/mhr°C at a temperature around room temperature are used.

Furthermore, the material satisfying the above conditions is usually 0.1 to 10 μm, preferably 0.3 to 10 μm, considering the amount of signal energy applied to the heating resistor, the interval of signal application time, etc.
It is desirable to form the layer to a thickness in the range of 1 to 6 μm, optimally in the range of 1 to 6 μm.

The material used may be any type of material, such as inorganic or organic materials, or in some cases, a composite material made of these materials or a plurality of laminated materials, as long as these conditions are satisfied. In particular, heat-resistant organic polymer materials having a softening point or melting point of 150° C. or higher, particularly 200° C. or higher, are preferably used.

The reasons why organic materials are effective as materials for thin films with low thermal conductivity are that they can be easily formed into thin films, that it is easy to obtain layers with high adhesion to other layers when stacked, and that they have good thermal conductivity. The reason for this is that the degree value is sufficiently low.

Although the above-mentioned Japanese Unexamined Patent Publication No. 55-123478 describes in detail the thin film with low thermal conductivity, it does not provide much explanation about the substrate on which it is placed. However, in bubble jet technology, the generation and disappearance of bubbles are repeated, and the transfer of heat from the substrate (heat storage to heat radiation) is an important issue. Good ejection performance can only be obtained by thoroughly considering the difference in conductivity.

Purpose The present invention was made in view of the above-mentioned circumstances.
The purpose of this invention is to provide a configuration of a heating element part that can generate stable bubbles in order to improve the ejection performance of a bubble jet liquid ejecting head.

Structure In order to achieve the above-mentioned object, the present invention has a thermal energy generating means for applying thermal energy to the recording liquid in the liquid chamber, and by the action of the thermal energy, the thermal energy acting part in the recording liquid is In a liquid jet recording head that performs recording by generating air bubbles and causing the recording liquid to fly in the form of droplets from an ejection orifice and adhere to a surface to be recorded by the acting force accompanying the increase in the volume of the air bubbles, the thermal energy generating means comprises: formed on a substrate having at least a two-layer structure,
When the thermal conductivity of the side (or layer) of the substrate in contact with the thermal energy generating means is A, and the thermal conductivity of the substrate (or layer) below it is B, the following relational expression is satisfied. That is. Hereinafter, the present invention will be explained based on examples.

FIG. 1 is an enlarged view of the main part (thermal energy generating part) of the liquid jet recording head according to the present invention, in which 11 is a substrate;
2 is a heating element, 13 is an independent electrode provided corresponding to each heating element, 14 is a common electrode provided in common to each heating element, 15 is a protective film, 16 is a recording liquid, and 17 is a bubble. In the generating section, as shown in the figure, a heating element 12, electrodes 13 and 14, a protective film 15, etc. are formed on a substrate 11 consisting of an a layer and a b layer.

In the bubble jet technology, it is necessary that the thermal energy generated by the heating element 12 is effectively transferred to the recording liquid 16 located above the heating element 12 to generate bubbles. Therefore, the role of the a-layer is to ensure that the heat from the heating element 12 does not go too much to the b-layer side and is effectively transmitted to the recording liquid.

In other words, the a-layer acts as a heat storage layer. Therefore, it is preferable that the thermal conductivity of the a-layer is lower. On the other hand, the b-layer has the role of dissipating the heat accumulated in the a-layer while bubbles are repeatedly generated and extinguished. Therefore, it is preferable that the b-layer has a high thermal conductivity. In summary, immediately after a pulse signal is applied to the heating element, the a layer acts to transfer as much heat as possible to the recording liquid side, instantly generating bubbles, and then immediately
It is desired that the heat of the layer escapes to the b-layer side and the bubble generation area is instantly cooled.

Therefore, the most important thing in bubble jet technology is to optimize the balance between the speeds of heat transfer between the a-layer and the b-layer. The inventor of the present invention quickly focused on this point, and found that bubbles are generated most efficiently and stably when a material is selected in which the heat transfer coefficient of layer a and layer b satisfies the following relational expression. Therefore, it has been found that good ejection performance can be obtained. (Note that good ejection performance here refers to ejection with good sharpness, no satellite droplets, no mist-like ejection, and strong frequency response.) In other words, the heat conduction of the a layer When the thermal conductivity of layer b is A and the thermal conductivity of layer b is B, good ejection performance satisfying the condition of 5≦□ was obtained. Furthermore, as for the optimum conditions, the materials that can be used are limited, but the following is most desirable.

Materials that meet these conditions include, for example, five layers of zinc, aluminum, antimony, and iridium.

Indium, brass, cadmium, steel, tin, tungsten, iron, copper, nickel, beryllium.

Metal materials such as gunmetal, and Ceramic materials such as alumina, silicon carbide, etc.

Examples include semiconductor materials such as silicon and germanium.

On the other hand, the a layer includes glass (soda, lead, pyrex)9 quartz glass, C
Examples include a SiO2 film formed by VD or sputtering.

As described above, according to the present invention, heat storage and heat dissipation in the bubble generating section are effectively performed, so that generation and disappearance of bubbles are stabilized, and good recording liquid ejection performance can be obtained.

FIG. 2 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. 3 is a perspective view showing an example of the bubble jet head, and FIG. Figure 5 is a perspective view when the head shown in Figure 3 is disassembled into the lid substrate (Figure 4 (a)) and the heating element substrate (Figure 4 (b)), and Figure 5 is Figure 4 (a). 21 is a perspective view of the lid substrate shown in FIG.
22 is a heating element substrate, 23 is a recording liquid inlet, 24 is an orifice, 25 is a channel, 26 is a region for forming a liquid chamber, 27 is an individual (independent) electrode, 28 is a common electrode, and 29 is a heating element (heater), 30 is ink, 31 is a bubble, and 32 is a flying ink droplet, and the present invention is applied to such a bubble jet type liquid jet recording head.

First, ink ejection by the bubble jets 1 to 1 will be described with reference to FIG. 3. (a) is a steady state, in which the surface tension of the ink 10 and the external pressure are in equilibrium on the orifice surface.

In (b), the heater 29 is heated until the surface temperature of the heater 29 rises rapidly and boiling development occurs in the adjacent ink layer, and microbubbles 31 are scattered.

(c) shows a state in which the adjacent ink layer that is rapidly heated on the entire surface of the heater 29 is instantaneously vaporized to form a boiling film, and the bubbles 31 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 bubble has grown to its maximum, and ink 30 corresponding to the volume of the bubble is pushed out from the orifice surface. At this time, no current is flowing through the heater 29, and the surface temperature of the heater 29 is decreasing. The maximum value of the volume of the bubble 31 is slightly delayed from the timing of electric pulse application.

(e) shows a state in which the bubbles 31 are cooled by ink or the like and begin to contract. At the tip of the ink column, the ink moves forward while maintaining the extruded speed, and at the rear end, as the air bubbles contract, the nozzle internal pressure decreases, causing the ink to flow backward from the refill chair surface into the nozzle, creating a constriction in the ink column. There is.

In (f), the air bubbles 31 are further contracted, the ink comes into contact with the heater surface, and the heater surface is 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. 6 is a diagram showing a typical example for explaining the configuration of the main parts of the liquid jet recording head as described above, and FIG.
FIG. 6(b), which is a detailed front partial view of the bubble jet recording head seen from the orifice side, is a partial cross-sectional view taken along the line indicated by the dashed line XX in FIG. 6(a). .

The recording head 41 shown in these figures has a predetermined number of grooves of a predetermined width and depth at a predetermined linear density on a substrate 43 on which an electrothermal transducer 42 is provided on the back surface. By bonding the grooved plate 44 so as to cover the substrate 43, a liquid discharge portion 46 including an orifice 45 for ejecting liquid is formed. Liquid discharge part 46
has an orifice 45 and a heat acting part 47 where thermal energy generated by the electrothermal converter 42 acts on the liquid to generate bubbles and cause rapid changes in state due to expansion and contraction of the volume.

The heat acting part 47 is located above the heat generating part 48 of the electrothermal converter 42, and has a heat acting surface 49, which is a surface of the heat generating part 48 that comes into contact with the liquid, as its lower surface. The heat generating section 48 is
It is composed of a lower layer 50 provided on the base 43, a heating resistance layer 51 provided on the lower layer 50, and an upper layer 52 provided on the heating resistance layer 51.

The heating resistance layer 51 is provided with electrodes 53 and 54 on its surface for supplying electricity to the core layer 51 in order to generate heat, and the heating resistance layer between these electrodes allows the heat generating portion 4
8 is formed.

The electrode 53 is an electrode common to the heat generating section of each liquid discharging section, and the electrode 54 is a selection electrode for selectively generating heat in the heat generating section of each liquid discharging section. It is provided along the flow path.

The protective layer 52 is a heat generating resistor layer 51 in the heat generating section 48.
In order to chemically and physically protect the liquid from the liquid used, the heating resistor layer 51 and the liquid filling the liquid flow path of the liquid discharge part 46 are separated, and the electrodes 53 and 54 are connected through the liquid.
It has the role of preventing short circuits between adjacent electrodes and further preventing electrical leakage between adjacent electrodes.

The liquid flow paths provided in each liquid discharge part are communicated with each other via a common liquid chamber (not shown) that constitutes a part of the liquid flow path upstream of each liquid discharge part. Due to design considerations, the electrodes 53 and 54 connected to the electrothermal converter 42 provided in each liquid discharge section are protected by the upper layer and are connected to the bottom of the common liquid chamber on the upstream side of the heat acting section. It is set up to pass through.

In such a liquid jet recording head, conventionally, as shown in FIG. The heat generating section 48 consisting of the heat generating resistor layer connected between the pair of electrodes 53 and 54 (which is the common electrode 531 and the selection electrode 54) is arranged at a predetermined position on the substrate. It was formed by stacking them in such a way that Therefore, the common electrode 53 has a folded shape, and the common electrode 53 and the selection electrode 54 are arranged alternately, so that the plurality of heat generating parts are arranged with the common electrode sandwiched therebetween.

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-5in2 mixture, tantalum nitride, nichrome, silver-palladium alloy, and silicon. Examples include borides of semiconductors or 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, 0.001
~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, AQ, 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.

=22- The characteristics required of the protective layer 63 are to protect the heat generating resistor 61 from the recording liquid without hindering the effective transfer of the heat generated by the heat generating resistor 61 to the recording liquid. be. 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 normally 0.01 to 10 μm, 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 driving circuit at that time. Reference numeral 71 denotes a known optical angler's cuff sensor unit for reading, which is composed of a photodiode or the like, and the image signal inputted to the optical angler's cuff sensor unit 71. 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 of generating bubbles in the recording liquid with reference. In the figure, 81 is a laser oscillator, 82 is a light modulation drive circuit, 83 is a light modulator, and 84 is a scanning The laser beam generated by the laser oscillator 81 is inputted to the optical modulator drive circuit 82, electrically processed, and pulsed according to the image information signal outputted by the optical modulator 82. Modulated. 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. This example shows an example in which the entire area (width) is covered.

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 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 receive a high voltage pulse from a discharge device 101. This device generates an electrical discharge in water, and the heat generated by the electrical 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).

In the example shown in FIG. 13, two flat plate electrodes are used so that air bubbles are stably generated 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, the aim is to stabilize the generated bubbles, and the stability is greater than that shown in FIG. 16 by adding a three-dimensional guide.

In the example shown in FIG. 19, contrary to the example shown in FIG.
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 printing apparatus to actually perform printing. First, please refer to FIGS. 20 to 23. while each electric/thermal converter 1101.1 according to an external signal.
102. -----...1107 is controlled simultaneously to each discharge port 1111. An example in which liquid is simultaneously discharged from IIL, . . . 111□ according to an external signal will be described. 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 125□-125□ for each converter 1.
10j.

1.102. ...Drive 110□ and 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 is a timing chart illustrating the operation of the buffer circuit 124 shown in FIG.
A character clock 5101 generated by a character generator generates a data signal 5102 arranged in
At the other timing, output signals are sequentially provided to the drive circuits 1251 to 1257. In the example of FIG. 20, one buffer circuit performs input/output, but control may be performed using a plurality of buffer circuits, so-called double buffering. 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 transformers 110. ．． 1102°...
...110□ are simultaneously controlled according to the droplet ejection timing chart as shown in FIG. 22, for example, and as a result, printing as shown by the O mark in FIG. 23 is achieved by ejecting droplets from seven ejection ports. It can be done. In addition, the signal 51
Each of 11 to A117 has seven converters 110□, 11
This is a signal applied to each of 0□, . . . 110□.

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 sent to the column buffer circuit 134 once. Then, at the timing when column data is being read from the character generator 133 and input to the column buffer circuit 134□, another data is output from the column buffer circuit 134□, 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 1101, 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, and 5142 is a column buffer circuit 1341.
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.
342 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 a circle is shown in Fig. 27.
The characters shown by the marks are printed. In addition, signal 5151
Each of ~5157 is the seven converters 110□.

1102, . . . , signals applied to each of 11o7.

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 recording device according to the present invention is selected from materials and proportions of composition components so as to have M-thermophysical properties and other physical properties to be described later, as well as those used in conventional recording methods. In addition to being chemically and physically stable like the recording liquid that is used, it also has excellent responsiveness, fidelity, and threading ability, does not harden in the liquid path, especially at the discharge port, and maintains the recording speed in the flow path. The physical properties are adjusted to provide characteristics such as being able to circulate at a suitable speed, being quickly fixed on the recording material after recording, having sufficient recording density, and having a good shelf life. Ru.

The recording liquid used in the recording device according to the present invention is composed of a liquid medium, a recording agent for forming a recorded image, and an additive added to obtain desired characteristics. Depending on the type and composition ratio of additives, it is possible to obtain either aqueous, non-aqueous, soluble, electrically conductive, or 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, tart-butyl alcohol, isobutyl alcohol, pentyl alcohol, hexyl alcohol, heptyl alcohol. , octyl alcohol, nonyl alcohol, decyl alcohol, and other alkyl alcohols having 1 to 1 carbon atoms; 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, 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 X 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) Medicinal Zen), Revafix Golden Yellow PR, Revafix 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), Cibaclon Pril Yellow, Cibaclon Pril Red 40E (manufactured by Ciba Geigy), Indico, Direct Tape Black E
-Ex, Diamine Black BH, Congo Red, Serious Black BH, Orange ■, Amido Black IO
B, Orange RO, Metaneal Yellow, Pictoria Scarlet, Nigrosine, Diamond Black PBB
(manufactured by Egame), Diacit Blue 3G, Diacit Fast Green GW, Diacito Milling Navy Blue R, Indanthrene (manufactured by Mitsubishi Kasei)
, Zapon dye (manufactured by BASF), orazole dye (CI
(manufactured by B A), Lanasin Dye (manufactured by Mitsubishi Kasei), Diacrylic Orange RL-E, Diacrylic Brilliant Blue 2B-E, Diacrylic Turquoise Blue BG-E (
Among those manufactured by Mitsubishi Kasei Co., Ltd., those which provide the recording liquid with the above-mentioned physical properties 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 FO
R, Lake Bordeaux 5B, Vermilion No. 1, Vermilion N002, 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 Carmine 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 Industhrene 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, Quinatalydone 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 additives used include viscosity modifiers, surface tension modifiers, pH modifiers, resistivity modifiers, wetting agents, and infrared absorbing exothermic agents.

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, etc., 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, there are also amino 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. 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 used in combination within the range specified above.

The amount of these surface tension modifiers to be added is determined as appropriate depending on the type, other constituent components of the recording liquid to be prepared, and desired recording characteristics. Usually 0.0001 to 0.1 parts by weight, preferably 0.0001 to 0.1 parts by weight.
The amount is desirably 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 a range that does not deviate from the physical property values.

As the pH adjuster suitably used in the present invention,
to achieve the desired pH without adversely affecting the recording liquid being dispensed.
Most things can be mentioned as long as the value can be controlled.

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 glycol 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 ethoxy 1-lyglycol; N-vinyl-2
-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.
0tat%, preferably 0.1-8wt%, optimally 0.
It is desirable that the content be 2 to 7 tst%.

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.

The recording liquid used in the recording device of the present invention may be added with the above-mentioned additives in required amounts as desired. For example, alkyd resin,
Resin polymers such as acrylic resin, acrylamide resin, polyvinyl alcohol, and polyvinylpyrrolidone may be added.

The recording liquid used in the recording device of the present invention has specific heat, coefficient of thermal expansion, thermal conductivity, viscosity, surface tension, pH, and charged recording droplets so as to have the various recording properties described above. In the case of recording, it is desirable that the composition be prepared so that the characteristic values such as specific resistance are within the conditional range of the characteristic.

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

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

As is clear from the above explanation, according to the present invention, heat storage and heat dissipation in the bubble generating section are effectively performed, so bubble generation and disappearance are stabilized, and recording liquid is ejected well. Performance can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a main part configuration diagram for explaining an embodiment of the present invention, FIG. 2 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. 3 is a perspective view showing an example of a bubble jet recording head, FIG. 4 is an exploded perspective view, FIG. 5 is a view of the lid substrate from the back side, and FIG. 6 shows details of the bubble jet recording head. FIG. 7 is a diagram for explaining the structure of a bubble generating means using a heating resistor, FIG. 8 is a block diagram for explaining an example of a heating element drive circuit, and FIG. The figure is a diagram for explaining an example of a bubble generating means using laser light, FIG. 10 is a diagram for explaining an example of a printer, and FIG. 11 is an example of a bubble generating means using electric discharge. The diagrams for explanation, FIGS. 12 to 19, are diagrams showing specific examples of the discharge electrode shown in FIG. 11, and FIGS. 20 to 23, and FIGS. 24 to 27,
FIG. 28 is a diagram for explaining a control example when recording is performed by incorporating a recording head into a recording apparatus, and FIG. 28 is a diagram for explaining a conventional technique. 11... Substrate, 12... Heating element, 13.14...
Electrode, 15... Protective film, 16... Recording liquid, 17...
・Bubble generating part. Figure 1 2-G

Claims (1)

[Scope of Claims] 1. A thermal energy generating means for applying thermal energy to the recording liquid in the liquid chamber, and generating bubbles in the thermal energy acting part in the recording liquid by the action of the thermal energy, In a liquid jet recording head that performs recording by ejecting the recording liquid in the form of droplets from an ejection orifice and adhering it to a recording surface using the acting force associated with the increase in the volume of the bubbles,
The thermal energy generating means is formed on a substrate having at least a two-layer structure, and the thermal conductivity of the layer on the side of the substrate in contact with the thermal energy generating means is A, and the thermal conductivity of the layer below it is B. A liquid jet recording head characterized in that it satisfies the following relational expression: 5≦(B/A).