JPH0613220B2 - Ink jet recording head - Google Patents

Description

The present invention relates to ink ejection (liquid ejection) for performing recording using flying droplets formed by ejecting liquid from ejection ports.
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording head, and particularly to an ink jet recording head that uses thermal energy.

There are various types of liquid jet recording apparatuses, and among them, for example, the liquid jet recording apparatuses of the systems disclosed in German Laid-Open Publications (OLS) 2843064, 2944005, and USP 4335389 are high-speed color recordings. Is easy. The recording head, which is the main part of the output section,
Since the ejection ports (orifices) for ejecting the recording liquid and forming the flying droplets can be arranged at a high density, a high resolution can be obtained and at the same time, the entire recording head can be obtained. Can be made compact and suitable for mass production, and it is easy to increase the length by fully utilizing the advantages of IC technology and microfabrication technology, in which technological advances and reliability are remarkably improved in the semiconductor field. Due to things such as these, they have recently received a lot of attention for their wealth.

An example of a recording head characteristic of the above liquid jet recording apparatus is provided with an electrothermal converter as a means for generating thermal energy for ejecting liquid from an orifice to form flying droplets. There is. The electrothermal converter, in order to efficiently apply the generated thermal energy to the liquid, to increase the ON-OFF response speed of the thermal action on the liquid,
For direct contact with the liquid, it is desirable that the structure be provided in a heat acting portion communicating with the orifice.

However, since the electrothermal converter is basically composed of a heating resistor that generates heat when energized, and a pair of electrodes for energizing the heating resistor, the heating resistor is When in direct contact with the liquid, electricity may flow through the liquid depending on the electric resistance value of the recording liquid, or the liquid itself may be electrolyzed by the flow of electricity through the liquid, or a heating resistor. When electricity is applied to the heating resistor, the heating resistor reacts with the liquid, causing a change in resistance value due to corrosion of the heating resistor itself, possibly causing damage or destruction of the heating resistor, and The surface of the heating resistor is damaged or a part of the heating resistor is cracked by a mechanical shock caused by a rapid state change of the liquid due to the generated heat action, preferably the generation of vapor bubbles. It will be destroyed by being caused If there is a.

Therefore, conventionally, alloys such as NiCr and ZrB have been used.
₂ , a heating resistor made of an inorganic material such as a metal boride such as HfB ₂ having a relatively excellent characteristic as a heating resistor material, and SiO ₂ on the heating resistor made of the material.
By providing a protective layer (upper layer) made of a material with excellent oxidation resistance such as, it is possible to prevent the heating resistor from coming into direct contact with the liquid, solve the above problems, and improve reliability. It has been proposed to try to improve the durability against repeated use.

However, the liquid jet recording apparatus having the recording head provided with the electrothermal converter having the above-described structure has a relatively low electric conductivity (for example, distilled water as a liquid medium) as a colored liquid for recording. Or using alcohol)
Is excellent in oxidation resistance and is sufficiently satisfactory in terms of repeated use durability, but since the content of Na ions and the like is high, a recording liquid or a liquid having a large electric conductivity is used. When an electrolyte liquid is used, it is insufficient in terms of repeated use durability and resistance to change over time. Therefore,
There is a restriction on the selection of the recording liquid to be used, which is an obstacle especially in the case of performing multicolor or natural color recording.

Further, even when the protective layer is provided on the heating resistor as described above, it is possible to substantially completely prevent the liquid from entering the heating resistor side due to a defect of the protective layer itself caused by layer formation. It is very difficult in terms of productivity and mass productivity. Furthermore, a liquid flow path (nozzle) having a large number of heat acting parts as a part of its configuration is provided with high density. In the case of so-called high-density multi-orifice, it is necessary to provide at least the electrothermal converters at the same time for the number of liquid flow paths. Therefore, the defect due to the defect in the protective layer has no influence on the manufacturing yield of the electrothermal converters. However, it is a big problem including the aspect of manufacturing cost.

The present invention has been made in view of the above points, and a main object of the present invention is to provide an excellent ink jet recording head capable of solving all of the above-mentioned problems in the related art.

Another object of the present invention is to provide an ink jet recording head which is excellent in liquid resistance, mechanical shock resistance, reusability, and electrochemical reaction resistance.

The ink jet recording head of the present invention comprises an electric heating device having a heating resistance layer that forms a heat acting surface for directly applying energy to ink and generates heat energy for forming bubbles in the ink on the heat acting surface by energization. In an ink jet recording head that includes a converter and ejects ink to perform recording,
A protective layer including a Ta layer forming the heat acting surface and a Si insulating layer between the Ta layer and the heating resistance layer is formed on the heating resistance layer of the electrothermal converter. And
The heating resistance layer of the electrothermal converter is Ta-Mo, Ta-W.
-Ni or Ta-Ni-Al alloy, and the Ta content of the alloy is 20 mol% or more.

Another ink jet recording head of the present invention is provided with a heat generating resistance layer which forms a heat acting surface for directly applying energy to the ink and generates heat energy for forming bubbles in the ink on the heat acting surface by energization. In an ink jet recording head that includes an electrothermal converter and performs recording by ejecting ink, a Ta layer that forms the heat acting surface and a Ta layer on the heating resistance layer of the electrothermal converter. A protective layer including a Si insulating layer between the heating resistance layer and the heating resistance layer is formed, and the heating resistance layer of the electrothermal converter is Ta-Mo-Ni.
It is composed of an alloy, and the Ta content of the alloy is 40 mol%
The above is characterized.

Yet another ink jet recording head of the present invention comprises a heat generating resistance layer which forms a heat acting surface for directly applying energy to the ink and generates heat energy for forming bubbles in the ink on the heat acting surface by energization. In an ink jet recording head that includes an electrothermal converter to perform recording by ejecting ink, on the heating resistance layer of the electrothermal converter,
A protective layer including a Ta layer forming the heat acting surface and a Si insulating layer between the Ta layer and the heating resistance layer is formed, and the heating resistance layer of the electrothermal converter is Ta. -W alloy, and the Ta content of the alloy is 50 mol% or more.

The ink jet recording head of the present invention configured as described above is excellent in repeated use resistance, liquid resistance, fidelity and certainty of response to a recording signal, and records a high resolution and high quality image at high speed. You can do it. In addition, since the selection range of the recording liquid is wide, it is possible to easily perform multicolor recording of desired colors and natural color recording.

In particular, by having a Ta layer forming the heat acting surface and a Si insulating layer interposed between the Ta layer and the heat generating resistance layer as the protective layer, stability of each effect described above as a whole Can be further improved.

When the electrothermal converter is configured so that the heating resistor directly contacts the recording liquid, the thermal energy generated by the heating resistor effectively acts on the recording liquid.
The threshold value of the driving voltage for driving the electrothermal converter is low, and the actual driving voltage for stably forming flying droplets is also low, and energy saving can be easily realized.

Hereinafter, the present invention will be described more specifically with reference to the drawings.

FIG. 1 (a) is a partial front view of the main part of the ink jet recording head of the present invention viewed from the orifice side, and FIG. 1 (b).
[Fig. 4] is a partial sectional view of a section taken along a dashed line XY in Fig. 1 (a).

The recording head 1 shown in the drawing is provided with a groove in which a predetermined number of grooves with a predetermined linear density and a predetermined width are provided on the surface of a substrate 3 on which the electrothermal converter 2 is provided. It has a structure in which the orifice 5 and the liquid discharge portion 6 are formed by joining them so as to cover with the plate 4. In the case of the ink jet recording head shown in the figure, it is shown as having a plurality of orifices 5. However, the present invention is not limited to this, and the invention can be applied to a recording head having a single orifice. It falls into the category of. The liquid discharge part 6 has an orifice 5 for discharging liquid at the end thereof to form flying droplets, and thermal energy generated by the electrothermal converter 2 acts on the liquid to generate vapor bubbles. It has a heat acting portion 7 which is a portion for causing a rapid state change due to expansion and contraction of the volume.

The heat acting portion 7 is located above the heat generating portion 8 of the electrothermal converter 2, and has a heat acting surface 9 that is in contact with the liquid of the heat generating portion 8 as its bottom surface.

The heat generating portion 8 includes a lower layer 10 provided on the substrate 3 and a heating resistance layer (heating resistor) 1 provided on the lower layer 10.
1. An upper layer 12 provided on the heat generating resistance layer 11 as needed. The heating resistance layer 11 is provided with electrodes 13 and 14 on its surface for supplying electricity to the layer 11 in order to generate heat. The electrode 13 is an electrode common to the heat generating portion of each liquid ejecting portion, and the electrode 14 is a selection electrode for selecting the heat generating portion of each liquid ejecting portion to generate heat. It is provided along the line.

The upper layer 12 serves to protect the heat generating resistance layer 11 chemically and physically from the liquid used, and the heat generating resistance layer 11 and the liquid discharge part 6
It isolates the liquid present in the
The heating resistor layer 11 has a protective function of preventing a short circuit between 3 and 14. The upper layer 12 has a function like vapor, but the heat generating resistance layer 11 in the ink jet recording head has the above-mentioned characteristics, and therefore the electrodes 13 and 14 are electrically short-circuited through the liquid. If you don't have to worry about
Further, even if there is the above-mentioned concern, it is not necessary to provide it on the heat-generating resistance layer 11, and the above-mentioned concern can be completely eliminated only by covering the surfaces of the electrodes 13 and 14.

The lower layer 10 mainly has a heat flow rate control function. That is, when the flying droplets are formed, the ratio of the heat generated in the heat generation resistance layer 11 to the heat acting portion 7 side is larger than that to the substrate 3 side. After the formation of the droplets and after the energization of the clogging heat resistance layer 11 is turned off, the heat in the heat acting portion 7 and the heat generating portion 8 is quickly released to the substrate 3 side, and the liquid in the heat acting portion 7 is discharged. Also, it is provided so that the generated bubbles are rapidly cooled.

The ink jet recording head of the present invention becomes more excellent by designing the lower layer 10 so that the above-described function can be sufficiently exerted in relation to the heating resistance layer 11 and the substrate 3. That is, the ratio of the heat flow rate to the heat acting portion 7 side is as large as possible during the formation of the flying droplets, and the heat to the substrate 3 side is generated when the heating resistance layer 11 is de-energized. By increasing the ratio of the flow rate as much as possible, the efficiency of droplet ejection energy is improved, the thermal response is improved, the droplet ejection frequency is improved continuously and repeatedly, the droplet formation frequency is improved, and the droplet amount is made uniform. It is possible to more effectively realize stabilization of the flight direction of the droplet, uniformization of the initial flight speed of the droplet, and improvement of fidelity and certainty of response to a recording signal.

Heat generating resistance layer 11 in the ink jet recording head of the present invention
Is provided as a thin layer of an alloy containing Ta and at least one element selected from transition metals, as described above. That is, in the present invention, Ta forming a Ta-containing alloy
The transition metal is effective as the other material. It may further contain Al (aluminum). Among the transition metals, Ni (nickel) is used particularly in the metal belonging to the fourth period of the periodic table, and Mo is contained in the metal belonging to the fifth period of the periodic table.
(Molybdenum), for metals belonging to Period 6 of the Periodic Table,
W (tungsten) can be mentioned as a preferable metal.

The metal that composes the Ta-containing alloy and that is the counterpart material of these Ta is not limited to one type, and two or more types may be used in order to obtain the desired characteristics to the maximum. That is, in the present invention, the Ta-containing alloy may be a binary system, a ternary system, a quaternary system or a multi-component system of more than that. When a ternary or higher multi-element system is used as the Ta-containing alloy, it is possible to obtain various physical properties by selecting a metal belonging to a different group depending on the purpose, rather than selecting a metal belonging to the same group of the periodic table. This is preferable because a metal can be obtained.

In the present invention, as a combination particularly preferably used as the Ta-containing alloy, a binary alloy such as Ta-Mo, Ta-W, Ta-Ni-Al, Ta-Mo-Ni, Ta- is used.
Examples include ternary alloys such as W-Ni.

In the present invention, the content rate of Ta contained in the Ta-containing alloy is as follows:
The content is determined according to the desired ratio so as to obtain the heat generating resistance layer 11 suitable for the purpose of the present invention, depending on the content ratio of the counterpart metals, but Ta-Mo, Ta-W-in mol%.
Ni, Ta-Ni-Al alloy is preferably 20 mol%
As described above, the Ta-Mo-Ni alloy is preferably 40 mol%
As described above, the Ta-W alloy is preferably 50 mol% or more, and the upper limit is less than 100 mol%.

In the present invention, the layer thickness of the heating resistance layer 11 depends on the characteristics of the constituent materials so that appropriate heat energy can be effectively generated.
It may be appropriately determined according to the type, content rate, flying droplet formation characteristics required for the apparatus itself, etc., but preferably 50Å to 5
μ, more preferably 100Å to 2μ, optimally 300Å
It is desirable to be set to ˜1 μ.

In the present invention, the heating resistance layer 11 made of a Ta-containing alloy
Is preferably formed by placing a mating metal piece of a desired Ta having a desired area on a Ta target and performing Co-Sputter (co-sputtering).

Next, an outline of the manufacturing method and the form of the ink jet recording head manufactured in the examples, reference examples, or comparative examples of the present invention described below will be described.

First, a heating resistor installation substrate was prepared in the following manner. After the heating resistor layer 11 and the aluminum electrode layer are formed on the lower layer 10 of the alumina substrate 3 which also serves as the lower layer 10, the heating resistors 11-1 to 11-3 having a width of 40 μm and a length of 200 μm are selectively etched. Was formed. Further, the selection electrode 14 and the common electrode 13 were formed by etching. Further, a protective layer (upper layer) 12 was laminated on the surface of each electrode and each heating resistor, if necessary.

Separately from these, a grooved plate formed by cutting and forming a plurality of grooves (for example, width 40 μm, depth 40 μm) and a groove serving as a common ink chamber (not shown) on a glass plate using a micro cutter. Also created 4.

The heating resistor installation substrate and the grooved plate prepared in this way are joined after aligning the heating resistor and the groove, and further liquid ink is introduced into the common ink chamber from an ink supply unit (not shown). An ink introducing tube (not shown) for connecting the recording head was also connected to complete the recording head integrally. Further, a lead substrate having lead electrodes (common lead electrode and selected lead electrode) connected to the above-mentioned selection electrode and common electrode was attached to this recording head.

In the ink jet recording head having the above structure, the upper layer 1
In the case where a thin layer of SiO _{2 having} a layer thickness of 1.0 μm and a thin layer of Ta having a layer thickness of 0.5 μm are laminated on each heating resistance layer 11 as the number 2, 1.5 to 1.9 times the expansion threshold voltage. A drive voltage margin was obtained. This indicates that the heat resistance is further improved by providing the upper layer 12 as compared with the case where the heating resistance layer 11 is exposed to the liquid.

In this case, the system without the upper layer 12 has a driving voltage margin of about 1.3 times the foaming threshold voltage, which is superior to the conventional one.

A silicon wafer is used as the substrate 3 in addition to the above alumina substrate, and a SiO ₂ layer of ₂ to 5 μm formed by thermally oxidizing the surface of the silicon wafer is used as the lower layer 10, and the same evaluation is performed. However, the same good result was obtained. Further, as the substrate 3, glass, ceramics, heat-resistant plastic, etc. can be used in addition to those used in the embodiments.

As the electrode material, in addition to Al, Al-Cu, Al-S
i or the like can be used, but when these materials are used, in order to isolate the electrode and the liquid, for example, a film formed by curing a photosensitive heat-resistant resin is used to remove the heat acting surface portion. It is preferable to cover the electrode and the periphery of the electrode.

Example An ink jet recording head (sample as described above)
NO.1-1 to 14-4) (100 liquid flow paths, one electrothermal converter per one flow path), 5 x per electrothermal converter
The reliability was measured by counting the number of faulty heating resistors when pulse driving was performed 10 ⁸ times. The results are shown in the table below. In the table, sample Nos. 4-1 to 3-1 and 5-1
~ 2, 6-1 to 3, 7-1 to 3, 8-1 to 3 are examples of the present invention, sample Nos. 1-1, 2-1 and 5-3 are comparative examples of the present invention Is a reference example.

[Brief description of drawings]

FIG. 1 (a) is a front partial view from one orifice side of a preferred embodiment of an ink jet recording head to which the present invention is applied, and FIG. 1 (b) is a dashed-dotted line in FIG. 1 (a). It is a cutting | disconnection partial view at the time of cutting | disconnecting in the part shown by XY. DESCRIPTION OF SYMBOLS 1 ... Ink jet recording head, 2 ... Electrothermal converter, 3 ... Substrate, 4 ... Grooved plate, 5 ... Orifice, 6 ... Liquid ejecting section, 7 ... Heat acting section, 8 ... Heat generating part, 9 ... Heat acting surface, 10 ... Lower layer, 11 ... Heating resistance layer, 12 ... Upper layer, 13 ... Common electrode, 14 ... Selection electrode.

Claims (15)

[Claims] 1. An electrothermal converter comprising a heat-acting surface for forming a heat-acting surface for directly applying energy to ink and generating heat energy for forming bubbles in the ink on the heat-acting surface by energization. In an ink jet recording head that ejects ink to perform recording, a Ta layer that forms the heat acting surface, and a Ta layer and the heating resistance layer are formed on the heating resistance layer of the electrothermal converter. And a Si insulating layer between the protective layer and the heat generating resistance layer of the electrothermal converter is Ta-Mo, Ta-W.
An ink jet recording head comprising an alloy of any one of -Ni and Ta-Ni-Al, wherein the content of Ta in the alloy is 20 mol% or more. 2. The ink jet recording head according to claim 1, wherein the heating resistance layer is formed by co-sputtering. 3. The ink jet recording head according to claim 1, wherein the heating resistance layer has a thickness of 50Å to 5 μm. 4. The ink jet recording head according to claim 3, wherein the heating resistance layer has a thickness of 100Å to 2 μm. 5. The ink jet recording head according to claim 4, wherein the heating resistance layer has a thickness of 300Å to 1 μm. 6. An electrothermal converter comprising a heating resistance layer for forming a heat acting surface for directly applying energy to the ink and generating heat energy for forming bubbles in the ink on the heat acting surface by energization. In an ink jet recording head that ejects ink to perform recording, a Ta layer that forms the heat acting surface, and a Ta layer and the heating resistance layer are formed on the heating resistance layer of the electrothermal converter. And a Si insulating layer between the protective layer and the heat generating resistance layer of the electrothermal converter is made of a Ta—Mo—Ni alloy, and the Ta content of the alloy is 40 mol% or more. An ink jet recording head characterized by being present. 7. The ink jet recording head according to claim 6, wherein the heating resistance layer is formed by co-sputtering. 8. The ink jet recording head according to claim 6, wherein the heating resistance layer has a thickness of 50Å to 5 μm. 9. The ink jet recording head according to claim 8, wherein the heating resistance layer has a thickness of 100Å to 2 μm. 10. The heating resistor layer has a thickness of 300Å to 1 μm.
The ink jet recording head according to claim 9, wherein 11. An electrothermal converter comprising: a heat-acting surface for directly applying energy to ink, and a heating resistance layer for generating heat energy for forming bubbles in the ink on the heat-acting surface by energization. In an ink jet recording head that ejects ink to perform recording, a Ta layer that forms the heat acting surface, and a Ta layer and the heating resistance layer are formed on the heating resistance layer of the electrothermal converter. And a Si insulating layer between the protective layer and the heating resistance layer of the electrothermal converter is made of a Ta-W alloy, and the Ta content of the alloy is 50 mol% or more. An ink jet recording head characterized by: 12. The ink jet recording head according to claim 11, wherein the heating resistance layer is formed by co-sputtering. 13. The ink jet recording head according to claim 11, wherein the heating resistance layer has a thickness of 50Å to 5 μm. 14. The heating resistance layer has a thickness of 100Å to 2 μm.
The ink jet recording head according to claim 13, wherein 15. The heating resistance layer has a thickness of 300Å to 1 μm.
The ink jet recording head according to claim 14, wherein