JPS63197652A - Ink jet recording head and its preparation - Google Patents

Abstract

PURPOSE:To facilitate the formation of a fine valve and that of a fine flow passage and to solve the limit of the miniaturization or multiplication of an ink jet recording head as observed in a conventional example, by forming an integrally formed valve by utilizing a part of a substrate in a flow passage. CONSTITUTION:With due regard to the formation of a valve or durability as a substrate, for example, the substrate 1 consisting of a SiO2 layer 3, a polysilicon layer 4 and a SiO2 layer 5 is used on a silicon wafer 2. Next, a heat generator 6 composed of HfB2 and an electrode 14 are formed on the substrate 1. Subsequently, a heat generator and the SiO2 layer 7 becoming the protective layer of the electrode are formed in a thickness of about 2mum by a sputtering method. The formed SiO2 layer 7 and SiO2 layer 5 are treated with a photolithographic technique to form SiO2 patterns 15 on the polysilicon layer 4. By itching the polysilicon layer 4 by immersing the same in an etching liquid, the SiO2 layer 5 being a part of the layer constitution of the substrate is utilized to obtain a valve 8. A part 16 of the flow passage communicating with a liquid chamber is simultaneously formed. After a flow passage wall 10 is formed on a substrate 1, the cover plate 9 of the flow passage is laminated to form a flow passage 12 to complete a recording head.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an inkjet recording head that performs recording by ejecting a recording liquid generally called ink, which has high-speed response and excellent ejection stability. The present invention relates to an inkjet recording head and a manufacturing method thereof.

(Prior Art) Inkjet recording methods have been known in which recording is performed by ejecting and flying a recording liquid. This method has excellent features such as high-speed printing, low noise, high recording quality, easy color image recording, and the ability to record on plain paper.

In such inkjet recording methods, recording is performed using inkjet recording heads based on various droplet ejection principles, but pressure energy generation means such as electromechanical transducers are used as ejection energy generation means for ejecting droplets. It is common to use thermal energy generating means such as an electrothermal converter as disclosed in Japanese Patent Laid-Open No. 53-101189.

For example, in the inkjet recording head disclosed in Japanese Patent Application Laid-Open No. 53-101189, a pulse current is applied to an electrothermal converter attached in a flow path to cause a bubbling phenomenon in the recording liquid in contact with the converter. Recording is performed by ejecting the recording liquid from the ejection port by utilizing the pressure exerted on the recording liquid in the flow path by the rapid volumetric expansion accompanying the generation of bubbles. Regardless of which principle is used, in order to obtain practical performance as a recording device, it is required to be able to eject droplets repeatedly at a high speed of 1 kHz to 10 kHz.

By the way, in order to repeatedly eject droplets with such an inkjet recording head, it is necessary to replenish the amount of liquid lost during ejection before the next ejection. A typical method for this purpose is to use the surface tension of the liquid to guide the liquid to the discharge port by capillary action.

Therefore, in order to perform high-speed recording by driving the ejection energy generating means at a high frequency, it is necessary to have a structure that makes it easy to replenish the ejection port with liquid, that is, to enlarge the flow path.

However, if the flow path is made larger, the ejection energy will be lost toward the rear of the flow path when ejection energy is generated, which will inhibit the effective contribution of ejection energy to droplet ejection, and the droplet ejection speed will slow down. This led to a decline in print quality.

As a method for solving this problem, it has been proposed to provide a valve in the flow path to effectively utilize the discharge energy. For example, Japanese Patent Application Laid-open No. 80-245558, Japanese Patent Application Laid-open No. 60-230865, etc. In addition, Utility Model Application Publication No. 61-78638 and Japanese Patent Application Publication No. 59-68
The shape of the valve and its manufacturing method are proposed in Japanese Patent No. 251 and the like.

[Problem that the invention seeks to solve]

However, conventional inkjet recording heads having such valves have the following drawbacks.

That is, l) it is difficult to form fine valves, so it is not easy to make the flow path fine; therefore, a fully multi-type inkjet recording head in which multiple ejection ports are arranged over the entire width of the recording paper, especially a special This method cannot be adequately applied to an inkjet recording head that can easily be fully multi-layered as disclosed in Japanese Patent Publication No. 53-101189.

2) Since valves are attached using adhesives, etc., not only does the number of assembly steps increase, which increases costs, but it is also difficult to miniaturize the valves.Furthermore, the accuracy of the attachment may reduce reliability and result in unstable discharge. etc. were also occurring.

Conventional inkjet recording heads that use valves have limitations in miniaturization and full multiplication.
There were various problems such as poor economic efficiency and reliability.

SUMMARY OF THE INVENTION An object of the present invention is to provide an inkjet recording head that solves the problems of conventional inkjet recording heads, and a method for manufacturing the same.

(Means for Solving the Problems) The above objects of the present invention are achieved by the following present invention.

That is, the first invention is an inkjet recording head that includes a flow path on a substrate that communicates with an ejection port for ejecting recording liquid, and a valve that is integrally formed in the flow path using a part of the substrate. An inkjet recording head characterized by having:

The second invention uses a multi-layered or single-layered substrate; (1) creating a valve integrated with the substrate using the layered structure of the substrate or the substrate itself; and (2) making the valve a part of the structure. A method of manufacturing an inkjet recording head is characterized by comprising a step of forming a flow path.

(Function) In the present invention, there is no need to create a separate valve as in the past.
Since the valve is integrated with the substrate formed using a part of the substrate, it is not only easy to miniaturize the recording head and make it fully multifunctional, but also stabilizes ejection, ensuring stable high-speed and high-quality recording. This makes it possible to provide an inkjet recording head that can be mass-produced efficiently and economically. Furthermore, when forming such valves, it is possible to use photolithography, which facilitates the formation of fine patterns, so that fine valves can be easily formed integrally with the substrate, and furthermore, many valves can be formed at once. Therefore, full multiplication is easy.

Here, as the substrate in the present invention, a multilayer structure in which various layers are provided on a desired base material is preferably used for various purposes such as improving durability and insulation. Of course, a single-layer substrate without any of these layers can also be used, and the material thereof is not particularly limited.

〔Example〕

Hereinafter, the present invention will be explained in detail using the drawings.

Note that although a multi-array type inkjet recording head having a plurality of ejection ports will be mainly described below, the present invention can also be applied to a single-array type inkjet recording head having one ejection port.

FIG. 1(a), FIG. 1(b), and FIG. 2 show one embodiment of the inkjet recording head of the present invention, and FIG. 1(a) also shows a schematic perspective view of the head. Figure 1 (b
) is a schematic perspective view of the head in the state shown in FIG. 1(a) with the cover plate 9 removed, and FIG. 2 is a schematic perspective view of the head in the state shown in FIG. A schematic perspective view of the head is shown.

This recording head includes a substrate 1, a plurality of ejection ports 1 arranged on the substrate 1, and a flow path 12 communicating with the ejection ports 11.
A heating element 6 as an ejection energy generating means is provided in a part of the flow path 12, and a liquid chamber 13 is provided for supplying recording liquid to the flow path 12. This flow path 12 is provided with a valve 8 that is integrally formed with the substrate 1 using a part of the substrate 1. In addition, Fig. 1(b)
The arrow shown inside is.

This shows the direction in which the recording liquid is replenished from the liquid chamber 13 to the flow path 12, and the reference numeral 14 in FIG. 2 is an electrode for applying a recording signal to the heating element 6.

The recording using the inkjet recording head of the present invention is not particularly different from that of the conventional example. This is done by applying it to the body 6.

Here, during recording in which droplets are ejected by applying electric pulses to the heating element 6, the valve 8 causes the flow of the recording liquid toward the liquid chamber, which is generated separately from the flow toward the ejection port, to the substrate. It bends in one direction, and as a result closes the flow path to prevent loss of ejection energy that does not contribute to droplet ejection. On the other hand, when replenishing the recording liquid after ejecting droplets, the valve 8 bends toward the cover plate 9 due to the flow of the recording liquid toward the ejection port and opens the flow path, so that the valve 8 is quickly refilled without creating any resistance. The recording liquid is replenished. Due to the action of the valve 8, the inkjet recording head of the present invention achieves high-speed and stable recording.

Note that the ejection energy generating means may be one that supplies energy by utilizing the bubbling phenomenon caused by heat supply to the recording liquid, such as the heating element described above, or one that supplies energy to the recording liquid by utilizing volume deformation, such as a piezoelectric element. Well-known means such as those that can be used can be used without particular limitation.

Next, an example of a method for manufacturing an inkjet recording head of the present invention having the valves as described above will be described with reference to FIG. 3, focusing in particular on the process of forming the valves. Furthermore, this third
The figure shows a schematic cross section taken along the line XI-Yi in FIG. 2.

First, as shown in FIG. 3(a), a desired substrate 1 is prepared. In this example, in consideration of the formation of valves to be carried out in the later process and the durability of the substrate, five
A substrate 1 having a multilayer structure in which an i02 layer 3, a polysilicon layer 4, and a 5i02 layer 5 are sequentially laminated was used. Each of these layers was created as follows.

That is, 5i0 is deposited on the silicon wafer 2 by thermal oxidation.
Two layers 3 were first formed to a thickness of 1 μm.

Next, three polysilicon layers 4 are formed on this by CVD method.
It was formed to have a thickness of 0μ. At this time, the raw material gas is SiH4
Using BH3 and BH3, the gas ratio at the time of forming the polysilicon layer was adjusted so that boron was doped to about +O to lO/clI2.

Next, on this polysilicon layer 4, a third layer, which will be described in detail later, is formed.
A pattern 5i02 with openings corresponding to the portions indicated by reference numeral 401 which were not etched in the step of FIG. 3(e) was formed by photolithography.

Next, the patterned silicon wafer is subjected to BH
3Put it in a diffusion furnace with gas flowing through it! Boron was diffused into the openings at a temperature of about 0.000°C. The portion to be diffused was limited to the 5f02 layer 3, and the diffusion was continued until at least about 10 7 cm 2 of boron was doped. Thereafter, after removing the pattern made of 5i02 by etching, a SiO□ layer 5 having a thickness of approximately 3 μm is formed on the polysilicon layer 4 by sputtering, thereby forming the multilayered substrate 1 shown in FIG. 3(a). Obtained.

Next, HfB as shown in FIG. 3(b) is placed on this substrate 1.
A heating element 6 consisting of , and the electrode opening shown in FIG. 2 described above were formed. This heating element 6 is made of 1 liter by sputtering method.
After forming a layer of fB2 on substrate i, this layer was obtained by patterning using 7-otolithography technique. Further, the electrode 14 was obtained by depositing AI on the substrate 1 using an electron beam evaporation method after forming the heating element, and then patterning the deposited layer of An using a photolithography technique.

Next, on the substrate 1 on which the heating elements and electrodes were formed, a 5f02 layer 7, which was to serve as a protective layer for the heating elements and electrodes, was formed by sputtering to a thickness of about 2 μm as shown in FIG. 3(C).

Next, prior to performing the etching process shown in FIG. 3(e), the 5f02 layer 7 formed as described above and the 5f02 layer 5 of the substrate 1 described above are patterned by photolithography. 5i02 shown in Figure 3(d)
A pattern I5 was formed on the polysilicon layer 4.

Next, the substrate 1 that has been patterned as described above is
3.3% by weight water, 23.4% by weight OH and 13% by weight
．． By etching the polysilicon layer 4 by immersing it in an etching solution consisting of a mixed solution of 3% by weight of isopropyl alcohol, 5f02, which is part of the layer structure of the substrate, is etched.
The exemplary valve 8 of FIG. 3(e) formed using layer 5 was obtained. At this time, a portion 16 of the flow path communicating with the liquid chamber is also formed at the same time. In order to make the explanation easier to understand, FIG. 4 shows a schematic cross-sectional view of the substrate on which the valve is formed, taken along the line X2-Y2 in FIG. 2.

Here, the above-mentioned etching solution has the property that it acts effectively as an etching solution for a polysilicon layer doped with a small amount of boron, but does not act as an etching solution for a polysilicon layer doped with a large amount of boron or a 5f02 layer. Therefore, the polysilicon layer in the region 402 where the amount of boron doped is as small as about 10 to 10/cm is approximately 1 p/w.
It is etched at a speed of in. On the other hand, the region 401 has a high boron doping amount of about 10”/cm.
Since the polysilicon layer is not etched and the 5f02 layer is not etched, a valve integrated with the substrate as shown in FIGS. 3(e) and 4 above can be formed.

Finally, after forming a channel wall lO as shown in FIG. 1(b) on the base 41il according to a conventional method, a channel cover plate 9 as shown in FIG. The channel 12 is formed to complete the inkjet recording head.

Although not specifically described above, the valve material is not particularly limited to the above-mentioned 5f02, and may be other inorganic insulators, metals, or organic materials such as polyimide. Further, the valve may be coated with Ta or the like to improve durability.

〔Effect of the invention〕

The effects brought about by the present invention described above include those listed below.

I) The use of photolithography technology, which leads to miniaturization, has made it possible to miniaturize valves. For this reason, it has become possible to provide an inkjet recording head that is smaller than before.

2) Since the valve is integrally formed with the substrate, there is no need to attach the valve, improving reliability.

3) It is possible to form a large number of valves at once with high precision, making it possible to fully support full multiplication.

4) Due to such miniaturization of valves and improved reliability, it has become possible to provide inkjet recording heads that can stably perform high-speed, high-quality recording with good mass production efficiency and at an economical cost.

[Brief explanation of the drawing]

1 and 2 are diagrams for explaining an example of an inkjet recording head of the present invention, and FIGS. 3 and 4 are diagrams for explaining an example of a method for manufacturing an inkjet recording head of the present invention. 2.-Silicon wafer 3.5.
7-5i02 layer 4-Polysilicon layer 6-・Heating element
8-Valve 9-Cover plate l〇-Flow path wall 11-Discharge port 12-Flow path 13-・Liquid chamber 731 diagram (a)

Claims (1)

[Scope of Claims] 1. In an inkjet recording head provided with a flow path on a substrate that communicates with an ejection port for ejecting recording liquid, a valve is integrally formed in the flow path using a part of the substrate. An inkjet recording head comprising: 2. Using a multi-layered or single-layered substrate, (1) using the layered structure of the substrate or the substrate itself to create a valve integrated with the substrate; (2) making the valve a part of the structure; 1. A method for manufacturing an inkjet recording head, comprising the step of forming a flow path.