JPH02277645A - Liquid jet recording head - Google Patents

Abstract

PURPOSE:To prolong the durability of a heating element and to prevent failure of insulation of an electrode from occurring by a method wherein volume resistivity of a thermal resistor layer and volume resistivity of a protective layer conform to a specific relation. CONSTITUTION:A liquid jet recording head is driven at a higher speed than 5KHz in continuous driven response frequency. A heat energy operation part has a thermal resistor layer 39 and at least a pair of electrodes 37, 38 connected electrically to the thermal resistor layer, and a protective layer 44 provided on the thermal resistor layer for bringing the thermal resistor layer in no contact with a recording liquid material 40. A pattern width of the thermal resistor 39 and a pattern width of an electrode connected thereto are a fine pattern of 25mum or under at its connection part. Where volume resistivity of the thermal resistor layer 39 is taken as rhoh and volume resistivity of the protective layer 44 is taken as rhohi, the relation of the formula (1) is satisfied. Thus, durability of the heating element part of the recording head is improved, and its life can be increased to 10<9> pulse or over. Further, a heat accumulating layer 43, the thermal resistor protective layer 44, and an electrode protective layer 45 are established, and improvement of durability to failure of insulation of the heating element part is achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid jet recording head, and more particularly to protection of a heat generating part or an electrode part of a bubble jet type ink jet head.

The plate rice non-impact recording method has 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.

Such an inkjet recording method performs recording 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 method of generating recording liquid droplets and the control method for controlling the flying direction of the generated recording liquid droplets.

First, the first method is disclosed in, for example, US Pat. No. 3,060,429 (Tele type method).
The generation of small droplets of recording liquid is carried out by electrostatic attraction,
The generated recording liquid droplet is controlled by an electric field according to the recording signal,
Recording is performed by selectively depositing 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 a method (Swast method) disclosed in, for example, U.S. Pat. No. 3,596,275, U.S. Pat. Recording is performed on a recording member by generating droplets of liquid and flying the generated droplets with a controlled amount of charge between deflection electrodes to which a negative electric field is applied. .

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 the method (Hertz method) disclosed, for example, in U.S. Pat. This method records by generating and atomizing droplets. 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 US Pat. No. 3,747,120 (Steams 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, in the 5teIllIe method, recording is performed by ejecting a small amount of recording liquid from an ejection port in response to a recording signal.

In other words, in the Stemma method, an electrical recording signal is applied to a piezoelectric vibrating element attached to a recording head that has an ejection port for discharging recording liquid, and this electrical recording signal is applied to the mechanical vibration of the piezoelectric vibrating element. Change 1. Recording is performed by ejecting small droplets of recording liquid from the ejection opening in accordance with the mechanical vibration 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 method 1-1 is simple in structure,
It is not suitable for high-speed recording because it requires a high voltage to generate droplets and it is difficult to form a recording head with multiple nozzles.

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.

As described above, the conventional method has advantages and disadvantages in terms of structure, high-speed recording, multi-nozzle recording head, generation of satellite dots, generation of recorded image Q-cubes, etc., and there are applications that take advantage of these advantages. There was a restriction that it could only be applied to

Furthermore, Japanese Patent Application Laid-Open No. 55-128468 discloses that a heating element is protected by a thin film having a specific resistance of 5×10'Ω·1 or more.

FIG. 7 is a diagram for explaining an example of a liquid jet recording head disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 55-128468. 1 A heat generating section 2 is provided on the surface of a heat generating element installed substrate 1. As shown in FIG. Further, as the material of the substrate 3, glass, ceramics, heat-resistant plastic, etc. are used. On the substrate 3, a chamber 4' for accommodating ink before ejection and a long groove 4 constituting an ejection orifice 5 are formed in advance. After alignment, they are joined and integrated with adhesive.

FIG. 8 is a sectional view taken along the axis of the groove 4, and the recording ink is supplied into the chamber 4' as indicated by the arrow in the figure. Now, when a signal is applied from the outside to the heat generating part 2 attached to a part within the chamber 4', the first heat generating part 2 generates heat and gives thermal energy to the ink in the vicinity thereof. The ink that has received thermal energy undergoes a change in state such as volumetric expansion or generation of bubbles, resulting in a pressure change, and this pressure change is transmitted in the direction of the ejection orifice 5, and the ink is ejected in the form of small droplets. Then, recording is performed by attaching these droplets to an arbitrary recording material such as paper (not shown).

FIG. 8 shows the detailed structure of the heating element installation board 1, and the heating unit 2 is constructed by sequentially forming a heat storage layer 71, a heating resistor 10, and an electrode 8 on a substrate 6 made of alumina or the like using a thin film forming technique. After the heating resistor 10 and the electrode 8 are patterned into a predetermined shape, a protective layer N9 is further layered. The heat generating portion 2 is configured to discharge heat into the groove 4. In the heating element installation board 1, the protective layer 9 is in direct contact with the ink, but this protective layer 9 prevents the heating resistor 10 and the electrode 8 from coming into contact with the ink and being oxidized, or conversely insulating them. It prevents the ink from being electrolyzed, and specifically, the protective layer 9 has a specific resistance of 5
A thin film having a thickness of about 0.1 μm to 5 μm and having a resistance of 10′Ω·1 or more is formed.

However, in the liquid jet recording head as described above, when considering the protection of the heating element section, the specific resistance of the thin film is one of the important factors, but more precisely, it should be discussed in relation to the heating resistor layer. There must be.

Furthermore, JP-A-59-143650 discloses altering the electrode surface to form a protective layer made of an inorganic insulating material.

Figures 9 and 10 are from the above-mentioned Japanese Patent Application Laid-Open No. 59-143650.
FIG. 9 is a partial front view as seen from the orifice side, and FIG. 10 is a diagram showing an example of the liquid jet recording head disclosed in the publication, and FIG. A partial cross-sectional view is shown in which the liquid jet recording head shown in the figure is a liquid jet recording head that is provided with a desired number of electrothermal converters 11 and utilizes heat for liquid ejection.
The main parts thereof include a substrate 12 for thermal inkjet (abbreviated as T/J) and a grooved plate 13 having a desired number of grooves corresponding to the electrothermal transducers 11.

The T/J board 12 and the grooved plate 13 are joined at predetermined locations with an adhesive or the like, so that the electrothermal converter 11 of the T/J board 12
A liquid flow path 14 is formed by the portion where the grooved plate 83 is provided and the groove portion of the grooved plate 83, and the liquid flow path 14 has a heat acting portion 15 as a part of its structure.

The T/J substrate 12 includes a support 16 made of silicon, glass, ceramics, etc., and a silicon substrate on the support 16.
It has a lower layer 17, a heat generating resistor layer 18, etc. where O□, etc. are formed, and on both sides of the surface of the heat generating resistor layer 18, electrodes 19, 20 and electrodes of the heat generating resistor layer 18 are arranged along the liquid flow path 14. A protective layer (upper layer) 21 made of an inorganic material is provided to cover the uncovered portion and the electrode portions 19 and 20.

The electrothermal converter 11 has a heat generating section 22 as its main part, and the heat generating section 22 has a lower layer 17, a heating resistance layer 18, and an upper layer 21 formed on the support 16 in this order from the support 16 side. It is composed of layers.

The surface (thermal action surface) 23 of the upper layer 21 is in direct contact with the liquid filling the liquid flow path 14. In order to further increase the mechanical strength, it has a double layer structure with layers 26 and 27, and one layer 26 is made of a relatively electrically insulating material such as an inorganic oxide such as Sin or an inorganic nitride such as 513N4. The layer 27 is made of an inorganic material with excellent properties, thermal conductivity, and heat resistance. io
, it is made of a metal material such as Ta.

By constructing the surface layer of the upper layer 21 from an inorganic material such as metal that is relatively sticky and has mechanical strength, the heat-active surface 23 is protected from the cavitation effect that occurs when liquid is discharged. Shocks can be sufficiently absorbed and the life of the electrothermal converter 11 can be significantly extended. The liquid jet recording head is characterized in that a protective layer 24 made of an inorganic insulating material is provided on the surfaces of the electrodes 19 and 20 by altering the electrode surface, and the protective layer 24 is not shown. is also provided at least at the bottom portion of the common liquid chamber provided upstream of the liquid flow path 14 as an extension of the electrode 20 .

The protective layer 24 is provided on the surface of the electrode portion, and its main role is to prevent liquid penetration and provide liquid resistance. Furthermore, by covering the electrode wiring part behind the common liquid chamber, it is possible to prevent the electrode wiring part from being scratched or disconnected during the manufacturing process. .

Therefore, in the liquid jet recording head, the above-mentioned
In order to protect the electrode, the relationship between the volume resistivity of the electrode and its protective layer is important. However, the above-mentioned JP-A-59-
Publication No. 143650 only mentions "inorganic insulating material" but does not specifically state how much insulation should be used.

Further, the insulation must be determined not only by the protective layer but also by the relationship with the electrode.

Furthermore, in JP-A-55-128468, the size of the heater is 200 μm x 40 μm;
In Publication No. 9-143650, it is 150 μm x 30 μm.
These technologies seem to be applied to relatively large heaters, for example, when the pattern width of the heater is 25 μm or less, and the manufacturing yield or durability of long-term use becomes an issue. For heads with very fine heater patterns such as this, it was not always possible to obtain good results by simply using the technology disclosed in JP-A-55-128468 or JP-A-59-143650. .

This is a problem that did not occur with relatively large heater patterns (or electrode patterns) as in JP-A-55-128468 or JP-A-59-143650 (heating layer, electrode pattern). This is because minute defects in materials such as layers, protective layers, etc., or pattern defects caused by particles, etc.) have also become problems in the manufacturing process or design because the pattern width is small. In addition, for heads that are driven continuously at very high speeds (for example, faster than 5KHz),
Because the number of heat cycles is extremely large, a part of the heater is exposed to extremely harsh conditions (heat cycle cavitation effect, corrosion by ink, etc.). It must be considered more strictly than when the frequency is not so fast.

■-1 The present invention was made in view of the above-mentioned circumstances.
In particular, it has a fine heater size and a fine electrode pattern, is arranged at a very high density (for example, 16 wires/I or more), and is driven at a very high speed (with a continuous drive response frequency of 5
In a bubble jet type liquid jet recording device that operates at a speed higher than KHz.

This was done to (1) protect the heat generating part and (2) improve the durability of the electrode part.

In order to achieve the above object (1), in other words, in order to protect the heat generating part, the present invention has a method of accommodating the recording liquid to be introduced and generating bubbles in the recording liquid by heat. a flow path provided with a thermal energy action section that generates an action force as the volume of the bubble increases, and an orifice that communicates with the flow path and causes the recording liquid to be ejected as a droplet by the action force; A liquid jet recording head comprising a liquid chamber for communicating with the flow path and introducing the recording liquid into the flow path, and a means for introducing the recording liquid into the liquid chamber, the liquid jet recording head having a continuous Driven at a drive response frequency higher than 5 KHz, the thermal energy applying section includes a heating resistor layer, at least one pair of electrodes electrically connected to the heating resistor layer, and provided on the heating resistor layer. and a protective layer for preventing the heat generating resistor layer from coming into contact with the recording liquid, and the pattern width of the heat generating resistor and the pattern width of the electrode connected thereto are a fine pattern of 25 μm or less at the connecting portion. Yes, when the volume resistivity of the heating resistor layer is ρh and the volume resistivity of the protective layer is ρhi, 10xs<JLj! ↓ ρh, and in order to achieve the above objective (2), in other words,
In order to improve the durability of the electrode section, a thermal energy generating section is attached that accommodates the recording liquid introduced, generates bubbles in the recording liquid by heat, and generates an acting force as the volume of the bubbles increases. an orifice that communicates with the flow path and causes the recording liquid to be ejected as droplets by the acting force; and a liquid that communicates with the flow path and introduces the recording liquid into the flow path. In a liquid jet recording head comprising a chamber and a means for introducing the recording liquid into the liquid chamber, the liquid jet recording head is driven at a continuous drive response frequency higher than 5 KHz, and the thermal energy application section includes a heating resistor. a body layer, at least one pair of electrodes electrically connected to the heating resistor layer, and an electrode protective layer provided to cover the electrodes to prevent the electrodes from coming into contact with the recording liquid; The pattern width of the heating resistor and the pattern width of the electrode connected thereto are fine patterns of 25 μm or less in the vicinity of the connection portion, the volume resistivity of the electrode is ρe, and the volume resistivity of the electrode protective layer is ρai. It is characterized in that it satisfies the relationship 101"kuJ"↓ ρe. An explanation will be given below based on one embodiment of the present invention.

FIG. 1 is a configuration diagram of a main part for explaining an example of a liquid jet recording head designed to improve the durability of the heating element part (1), that is, the above objective (2), and FIG. )
That is, 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. 5 is a perspective view showing an example of a bubble jet head.

The lid substrate that constitutes the head shown in Fig. 4 (Fig. 5 (a)
) and a heating element board (Fig. 5(b)), and Fig. 6 is a perspective view of the lid board shown in Fig. 5(a) seen from the back side. is a lid substrate, 32 is a heating element substrate,
33 is a recording liquid inlet, 34 is an orifice, 35 is a channel, 36 is a region for forming a liquid chamber, 37 is an individual (independent) electrode, 38 is a common electrode, 39 is a heating element (heater), 4
0 is ink, 41 is a bubble, and 42 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 a bubble jet will be described with reference to FIG. 3. (a) is a steady state, in which the surface tension of the ink 40 and the external pressure are in equilibrium on the orifice surface.

In (b), the heater 39 is heated until the surface temperature of the heater 39 rises rapidly and boiling development occurs in the adjacent ink layer, and microbubbles 41 are scattered.

(Q) shows a state in which the adjacent ink layer is rapidly heated on the entire surface of the heater 39 and instantaneously vaporizes, forming a boiling film, and the bubbles 41 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 40 corresponding to the volume of the bubbles is pushed out from the ori-rice surface. At this time, no current is flowing through the heater 39, and the surface temperature of the heater 39 is decreasing. The maximum value of the volume of the bubble 41 is slightly delayed from the timing of electric pulse application.

(e) shows a state in which the bubbles 41 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 41 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/sec.

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).

In the embodiment shown in FIG. 1, 43 is a heat storage layer, 44 is a heating resistor protective layer, and 45 is an electrode protective layer, and this embodiment is designed to improve the durability against insulation damage of the heating element. It was made for measuring purposes.

This figure shows a cross-sectional view of the thermal energy application section, and as shown, the heating resistor layer 39 heats the recording liquid (ink) 40 via the protective layer 44. In this part, bubbles are repeatedly generated, contracted, and disappeared, and the heat cycle is constantly repeated. Moreover, this repetition is repeated more than 5,000 times per second at the maximum, and the shock due to the heat cycle or the cavitation effect of bubble disappearance occurs in a very minute area, that is, in the pattern width.
Since it acts concentratedly on a region of 5 μm or less, it is subjected to very severe conditions from the viewpoint of durability. Moreover,
Dielectric breakdown in this area is one of the most important issues for bubble jet technology, since the surrounding conditions are very severe, including a corrosive recording liquid. In order to solve this problem, it is not enough to simply determine the specific resistance of the protective layer 44;
It is necessary to suppress the relationship with the heating resistor layer 39 that generates heat.The present inventor changed the volume resistivity of each of the heating resistor layer 39 and the protective layer 44 (this can be done by changing the material itself or , the film quality of each layer can be changed by changing the formation conditions) We prototyped a bubble jet type liquid jet recording head, conducted a jetting durability test, and found that the recording head was The durability of the heating element (thermal energy acting part) has been improved, extending its lifespan by 101%.
I discovered that it can do more than pulses.

10xi<JL! ! ↓ ρh However, ρhi: Volume resistivity of the protective layer 44 ρh: Volume resistivity of the heating resistor layer 39 Useful materials for forming the heating resistor layer 39 include tantalum nitride and nichrome, for example.

Silver-palladium alloy, silicon semiconductor, or hafnium, lanthanum, zirconium, titanium.

Examples include borides of metals such as tantalum, tungsten, molybdenum, niobium, chromium, and vanadium. Among the materials constituting these heating resistor layers, metal borides are particularly excellent, and among these, hafnium boride has the best properties, followed by zirconium boride. , lanthanum boride, tantalum boride, vanadium boride.

Niobium boride follows in this order.

The heat generating resistor layer can be formed using the above-mentioned materials using methods such as electron beam evaporation and sputtering. It is determined according to the area, material, shape and size of the heat-acting part, as well as actual power consumption, etc., but in normal cases, it is O, OO1 to 5μ.
The thickness is preferably 0.01 to 1 μm.

Examples of useful materials for forming the protective layer include silicon oxide, silicon nitride, magnesium oxide, aluminum oxide, tantalum oxide, and zirconium oxide, which can be prepared using methods such as electron beam evaporation and sputtering. can be formed. The thickness of the protective layer is usually

It is desirable that the diameter is 0.01 to 10 μm, preferably 0.1 to 3 μm.

As the material for forming the electrode, many commonly used electrode materials can be effectively used, specifically, for example, AQ, Ag, Au, and 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 embodiment shown in Figure 2 was designed to improve the durability against dielectric breakdown of the electrode parts 37 and 38 that come into contact with the recording liquid (ink), and the figure is an enlarged view of one heating element substrate. The shaded area 46 in the figure is the electrode protective layer.

Note that the pattern of this electrode protective layer is just an example, and it may be formed independently for each electrode instead of covering the entire surface as shown in the figure. This is provided to prevent contact with ink). One condition is that the electrode protective layer itself is not only in contact with the recording liquid, but also that the heating resistor layer (thermal energy acting part) in the vicinity repeats the heat cycle more than 5000 times per second at most. They are in a very difficult situation. Moreover, the electrode pattern width is 2
Heat cycle is applied to extremely fine areas of 5 μm or less.
In terms of durability, it can be said that it is exposed to very severe conditions because of the effects of corrosion or dielectric breakdown caused by the ink. The role of the electrode protective layer is to protect the electrode from dielectric breakdown under such conditions. Therefore, when forming an electrode protective layer, it is necessary to determine not only the material itself but also the relationship with the electrode material.

The present inventor has developed a bubble-jet liquid injection method in which the volume resistivity of the electrode and the electrode protective layer are changed (this can be done by changing the material itself or by changing the production conditions to change the film quality of each layer). A recording head was prototyped, a jetting durability test was conducted, and it was found that dielectric breakdown of the electrodes is less likely to occur when the configuration satisfies the following relationship.

10xi<L ridge However, ρei: Volume resistivity of the heat-generating protective layer ρe: Volume resistivity of the electrode Many of the commonly used electrode materials can be effectively used as the material constituting the electrode. The first
As in the case of the embodiment shown in the figure, Affi, Ag, Au
, Pt, Cu, etc., and are provided at a predetermined position with a predetermined size, shape, and thickness by a method such as vapor deposition.

Examples of materials constituting the electrode protective layer include:

Organic materials such as epoxy resin, Teflon resin, and polyethylene resin are used. As an inorganic material, silicon oxide, silicon nitride, etc. can be formed using a technique such as sputtering.

Examples of materials useful for forming the heating resistor layer include tantalum nitride, nichrome, silver-palladium alloy, silicon semiconductor, hafnium, lanthanum, zirconium, titanium, tantalum, Examples include borides of metals such as tungsten, molybdenum, niobium, chromium, and vanadium. Among the materials constituting these heating resistor layers, metal borides are particularly excellent, and among these, hafnium boride has the best properties, followed by zirconium boride. , lanthanum boride.

The order is tantalum boride, vanadium boride, and niobium boride.

The heat generating resistor layer can be formed using the above-mentioned materials using methods such as electron beam evaporation and sputtering. It is determined according to the area, material, shape and size of the heat-acting part, as well as actual power consumption, etc. (1) Normally, it is 0.001 to 5μ.
The thickness is preferably 0.01 to 1 μm.

Examples of useful materials for forming the protective layer include silicon oxide, silicon nitride, magnesium oxide, aluminum oxide, tantalum oxide, and zirconium oxide, which can be prepared using methods such as electron beam evaporation and sputtering. can be formed. The thickness of the protective layer is usually

It is desirable that the thickness be 0.01 to 10μ, preferably 0.1 to 3μ.

Nu1j12 Heating element protective layer electrode Tantalum nitride Size 25*mX100μ Thickness 0.
3Pm silicon oxide Thickness 1#■ Aluminum Pattern width 25μ■ Thickness 1-■ Electrode protective layer Polyimide Thickness 3#11
Large Example Heating Element Hafnium Boride Size 20JIIX90
J11 Thickness 0.2 J11 electrode gold
Pattern width: 20#11 Thickness: 0.9 Thickness: Epoxy Electrode protective layer: Epoxy thickness: 2 mm The results are as follows.
0' It functioned normally without any disconnection even after being driven one or more times.

As is clear from the above description, according to the present invention, in a bubble jet liquid jet recording head, the durability of the heating element portion is significantly improved, and the dielectric breakdown of the electrodes is made less likely to occur. , durability can be significantly improved.

[Brief explanation of drawings]

1 and 2 are main part configuration diagrams for explaining the present invention in detail, and FIGS. 3 to 6 are for explaining an example of a liquid jet recording head to which the present invention is applied. diagram,
FIGS. 7 to 10 are diagrams for explaining examples of conventional liquid jet recording heads. 32...Heating element substrate, 37.38...Electrode, 39.
... Heating element, 44... Heating element protective layer, 45... Electrode protective layer. Figure Figure Figure Figure Figure

Claims (1)

[Scope of Claims] 1. A flow channel that contains a recording liquid to be introduced, generates bubbles in the recording liquid by heat, and is provided with a thermal energy acting section that generates an acting force as the volume of the bubbles increases. , an orifice that communicates with the flow path and causes the recording liquid to be ejected as droplets by the acting force; a liquid chamber that communicates with the flow path and introduces the recording liquid into the flow path; In a liquid jet recording head comprising means for introducing the recording liquid into a liquid chamber, the liquid jet recording head is driven at a continuous drive response frequency higher than 5 KHz,
The thermal energy applying section includes a heating resistor layer, at least one pair of electrodes electrically connected to the heating resistor layer, and is provided on the heating resistor layer to apply the heating resistor layer to the recording liquid. The pattern width of the heating resistor and the pattern width of the electrode connected thereto are fine patterns of 25 μm or less at the connecting portion, and the volume resistivity of the heating resistor layer is When ρh is the volume resistivity of the protective layer, ρhi is 10^1^
A liquid jet recording head characterized in that it satisfies the relationship: 5<ρhi/ρh. 2. A flow channel connected to the flow channel that accommodates the recording liquid to be introduced and is provided with a thermal energy acting section that generates bubbles in the recording liquid by heat and generates an acting force as the volume of the bubbles increases. an orifice for ejecting the recording liquid as droplets by the acting force; a liquid chamber for communicating with the flow path and introducing the recording liquid into the flow path; and a liquid chamber for introducing the recording liquid into the flow path; In the liquid jet recording head, the liquid jet recording head is driven at a continuous drive response frequency higher than 5 KHz, and the thermal energy application section includes a heat generating resistor layer and a heat generating resistor layer. at least one pair of electrically connected electrodes;
and an electrode protective layer provided to cover the electrode to prevent the electrode from coming into contact with the recording liquid, and the pattern width of the heating resistor and the pattern width of the electrode connected thereto are set in the vicinity of the connection portion thereof. is a fine pattern of 25 μm or less, and when the volume resistivity of the electrode is ρe and the volume resistivity of the electrode protective layer is ρei, 10^1^7<
A liquid jet recording head characterized in that it satisfies the relationship ρei/ρe.