JPS60203452A - Liquid jet recording head - Google Patents

Abstract

PURPOSE:To stably maintain good liquid droplets-forming characteristics for long periods of time by raising the comprehensive durability by designating the surface roughness of a base material with an energy generator to a given value. CONSTITUTION:A base plate 101 having the electric heat converter 104 of an energy generator for a liquid jet recording head 100 is made up of a supporting base plate 102 and the smooth layer 103 of the base material. The surface roughness of the smooth layer 103 is controlled to be Ra<=0.1mum, where Ra is the average roughness of central line. The recessed and projected portions of the base plate 102 are buried and covered with the layer 103 to practically smoothen and flaten the uneven surface, and they are further covered with an upper layer 114, etc., without damaging the covering characteristics. As a result, a liquid jet recording head capable of stably maintaining good liquid droplets-forming characteristics for long periods of time and having improved durability can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a liquid jet recording head that performs recording by jetting liquid and forming flying droplets.

[Prior art]

Liquid jet recording methods such as inkjet recording generate very little noise during recording, which can be ignored.
It has recently attracted attention because it is capable of high-speed recording and can record without the need for special processing such as fixing reeds and edges on plain paper.

Among them, for example, the liquid jet recording method described in Japanese Patent Application Laid-Open No. 54-51837 and German Opening Publication (DOLS) No. 2843064 applies thermal energy to the liquid to generate the driving force for ejecting droplets. This method has different characteristics from other liquid jet recording methods in terms of the amount of information obtained.

That is, in the recording method disclosed in the above-mentioned publication, the liquid subjected to the action of thermal energy undergoes a state change accompanied by a sudden increase in volume, and the acting force based on this state change causes the tip of the recording head to change. A liquid jet recording method in which liquid is ejected from an orifice and flying droplets formed at that time are attached to a recording member is a so-called drop-an method.
This is not a stupid idea that is very effectively applied to the demand recording method, but it is possible to easily realize a recording head with a full 1ine type recording head and a high density multi-orifice, so it is possible to produce high-resolution, high-quality images at high speed. It has the characteristic that it can be obtained.

The recording head section of the apparatus applied to this recording method consists of an orifice provided for ejecting liquid, and a part that communicates with the orifice and where thermal energy acts on the liquid to eject droplets. It is equipped with a liquid discharge part having a liquid flow path of which the action part is a part of the structure, and an electric heat unit as a means for generating thermal energy.

This electrothermal converter includes a pair of electrodes, and a heat generating resistor layer connected to these electrodes and having a heat generating portion in a heat generating region between these electrodes.

A typical example of the structure of such a liquid jet recording head is shown in the first example.
This is shown in Figure (6) and Figure 1 (B).

Here, 1 is a recording head for ejecting liquid, 2 is a substrate thereof, and 3 is a liquid passage hole for circulating recording liquid to the head. Furthermore, electrothermal converters 4 that generate thermal energy are arranged on the substrate 2 at predetermined intervals, and three sides of these electrothermal converters 4 are arranged in a zigzag shape as shown in FIG. 1(A). A liquid flow path portion 6 having a predetermined depth and width is surrounded by the surrounding wall member 5, and a liquid chamber portion 8 is formed by the surrounding wall member 5 and the peripheral wall member 7.

Reference numeral 9 denotes a liquid discharge hole, or orifice, which is bored at the position of the discharge plate 10 located directly above the upper surface of the electrothermal converter 4, that is, the heat acting surface 4A where the converter 4 maintains contact with the liquid. In the liquid flow path section 60 interposed between the working surface 4A and this orifice 9, bubbles are generated in the liquid that has been supplied with generated thermal energy from the electrothermal converter 4, and its volume is rapidly expanded. heat action area 6
A is configured.

Furthermore, as shown in FIG. 1(B), the electrothermal converter 4 includes a heat generating resistor layer 11 attached to the upper surface of the substrate 2, a common electrode 12 for energizing the heat generating resistor layer 11 to generate heat, and individual electrodes. and a selection electrode 13 for selectively generating heat in the electrothermal converter 4, where the common electrode 12 and the selection electrode 13 are connected to the liquid flow from the liquid chamber 8 formed on both sides of the member 5, respectively. It is arranged so as to straddle the road section 6.

In this way, the common electrode 12 and the individual selection electrodes 13 are electrically connected to the heating resistance layer 11, thereby forming the stain pyrothermal converter 4, and the electrothermal converter formed in this way Further, an upper layer 14 is formed on the upper surface of 4 and the upper surface of the electrode 12.13, and this upper layer 4 causes a heating resistance layer 11 to fill the liquid flow path section 6 including the heat action area 6A. This protects the electrodes 12 and 13 from causing a chemical or physical reaction when they come into contact with the liquid, and prevents the electrodes 12 and 13 from being short-circuited via the liquid. In the following description, the electric converter 4 and the upper layer 14 covering its upper surface are referred to as a heat generating section 24, and the heat acting area 6 and orifice 9 are also referred to as a liquid discharge section 25.

Furthermore, the upper layer 14u also has the role of preventing electrical leakage between adjacent electrodes, and in particular, preventing electrical leakage between each selection electrode 13 or each liquid flow path 6. It is important to prevent electrolytic corrosion that occurs when the underlying electrodes 12 and 13 come into contact with liquid for some reason and are energized, and for this reason, such a protective layer function is required. The upper layer 14 having the same structure is also provided on at least the electrodes 12 and 13 below the liquid flow path.

In particular, the liquid flow path section 6 provided in each liquid discharge section 25 is
Upstream of each liquid discharge part 25, each liquid discharge part 25 communicates with each other via a common liquid chamber part 8 that constitutes a part of the flow path.
An electrode 12 connected to an electrothermal converter 4 provided in
Due to design considerations, the electrodes 12 and 13 are disposed so as to pass under the common liquid chamber 8, which is the upstream side of the six heat-acting areas.
It was necessary to prevent the liquid from coming into contact with the liquid.

However, in the liquid jet recording head configured in this way, the characteristics required for the above-mentioned upper layer 14 differ depending on the location where it is provided.

That is, for example, the heat generating part 24 is required to have excellent properties such as heat resistance, liquid resistance, liquid permeation prevention property, thermal conductivity, antioxidant property, and tear resistance.
In areas other than 4, although they can be alleviated by thermal conditions, they are required to have enhanced liquid penetration prevention properties, liquid resistance, and puncture resistance.

By the way, at present, there is no material for forming the upper layer 14 that fully satisfies all of the above-mentioned characteristics as desired, and the material is currently used with some of these characteristics relaxed. .

That is, in the heat generating section 24, priority is given to heat resistance, thermal conductivity, and anti-oxidation properties, while on the other hand, in areas other than the heat generating section 24, for example, the electrode covering section, liquid resistance, liquid penetration prevention properties, and breakage resistance are prioritized. Vulnerability becomes a priority condition.

In addition, for one of the substrates 2, a substrate material such as ceramics is suitable because of its low cost, good workability, electrical insulation, and good thermal conductivity, but in the case of a ceramic substrate, Since fine irregularities are formed on the surface, it is difficult to maintain coverage of the upper layer 14 at the stepped portions.

That is, if the coverage of the upper layer 14 is poor with respect to the roughness of the substrate surface, liquid may penetrate from that portion, causing electrolytic corrosion or electrical breakdown.

Therefore, taking these things into consideration, the surface of the substrate 2 should include at least the electrodes 12 and 13 and the heating resistor layer 11.
However, in the conventional liquid jet recording head, the substrate 2 and the upper layer 14 are required to have a smoothness that does not impair the coverage of the upper layer 14 at the portions that come into contact with the liquid. There has been no excellent product that has layer 14 and can guarantee overall durability in use.

〔the purpose 〕

In view of the above-mentioned points, the object of the present invention is to provide a liquid jet that has excellent overall durability in frequent repeated use and long-term continuous use, and is capable of stably maintaining good initial droplet formation characteristics over a long period of time. The purpose is to provide a recording head.

Furthermore, another object of the present invention is to provide a liquid jet recording head that is highly reliable in manufacturing and processing.

Furthermore, it is an object of the present invention to provide a liquid jet recording head that has a high manufacturing yield even when it has multiple orifices.

〔composition〕

In order to achieve such an object, the present invention provides an orifice for ejecting liquid to form flying droplets, a liquid flow path communicating with the orifice, and a liquid flow path provided on a substrate along the liquid flow path. In a liquid jet recording head having an energy generating body that generates energy used to form the droplets, the surface roughness of the substrate on which the energy generating body is provided is JIS standard, and the center line average The roughness Ra is characterized in that Ra≦0.1 μm. [Example] The present invention will be described in detail below based on the drawings.

FIGS. 2(G) and 2(J3) show an embodiment of the present invention. In the liquid jet recording head 100 of this embodiment, the substrate 101 is composed of a support substrate 102 and a smooth layer 103. Therefore, the support substrate 102 may be formed of, for example, ceramics, a resin material, or metal, as in the conventional case, and the roughness of its upper surface may be rough.

A smooth layer 103 is formed on the upper surface of the supporting substrate 102 at least in a portion related to the recording liquid. This is provided to prevent the coating properties from being damaged during the process, and suitable materials include glass-based ceramics and organic resins, which will be described later. Therefore, the roughness required for such a smooth surface is determined by JIS.
It is desirable that the centerline average roughness is maintained at 0.1 μm or less as defined in . That is, by providing this smooth layer 103, it fills in the recesses on the support substrate 102 and also covers the convex parts to smooth out the irregularities.
A common electrode 12 is mounted on the upper surface of the heating resistance layer 111.
and selective electrodes 13 are disposed, and the upper layer 114 is completely coated on the portions of the resistive layer 111 not covered by these electrodes 12 and 13 and on the electrodes 12 and 13. I can do it.

Note that this smooth layer 103 also has the role of controlling the flow of heat generated from the heat generating section 124 toward the support substrate 102, and supplies thermal energy to the liquid in the heat action area 25 to act on it. In this case, the heat generated from the heat generating section 124 is guided as much as possible to the heat generating section 124 side, so that when the electricity to the electrothermal converter 104 is cut off, the heat remaining in the linear heat generating section 124 is removed. Supporting board 1
02 side has a function to quickly escape.

Therefore, smooth layer 1 suitable for exhibiting such functions
In addition to glass Sing, the constituent materials of 03 include inorganic materials typified by metal oxides such as zirconium oxide, tantalum oxide, magnesium oxide, and aluminum oxide.

Furthermore, organic materials such as organic insulators such as acrylic resins, cyclized butadiene rubbers, polyimide resins, and silicone 2 resins may also be used.

The manufacturing method can be a printing method, a sputtering method, a vapor deposition method, a CvD method, a gas phase reaction method, a liquid coating method, a thermal spraying method, etc., and the roughness is generally 0.1 μm or less in Ra. , preferably 0.03 μm in Ra
It is desirable that it is as follows.

Furthermore, in this example, in addition to the above-mentioned inorganic materials, materials constituting the upper layer 114 include titanium oxide, vanadium oxide, niobium oxide, molybdenum oxide, tantalum oxide, tungsten oxide, chromium oxide, zirconium oxide,
Transition metal oxides such as hafnium oxide, lanthanum oxide, yttrium oxide, and manganese oxide; metal oxides such as aluminum oxide, calcium oxide, strontium oxide, barium oxide, and silicon oxide; and complexes thereof;
High-resistance nitrides such as silicon nitride, aluminum nitride, boron nitride, tantalum nitride, composites of these oxides and nitrides, and semiconductors such as amorphous silicon and amorphous selenium can be processed using sputtering and CvD methods even if they have low resistance in bulk. Thin film materials that can be made highly resistive through manufacturing processes such as vapor deposition, vapor phase reaction, and liquid coating are listed below, and the layer thickness is generally 0.1 μm to 5 μm.
1, preferably 0.2 μm to 3 pm.

As the material constituting the heating resistance layer 111, almost any material can be used as long as it generates a desired amount of heat when energized.Therefore, as the material, for example, tantalum nitride, , nichrome, silver-palladium alloy, silicon semiconductor, Iha, hafnium, lanthanum, zirconium, titanium, tantalum,
Preferred examples include borides of metals such as tungsten, molybdenum, niobium, chromium, and vanadium.

Among these materials constituting the heating resistance layer 111, metal borides are particularly excellent. Among them, hafnium boride has the best properties, followed by zirconium boride, The order is lanthanum boride, tantalum boride, vanadium boride, and niobium boride.

The heat generating resistor layer 111 can be formed using the above-mentioned materials by techniques such as electron beam evaporation and sputtering/ring.

Furthermore, examples of the materials constituting the electrodes 12 and 13 include At, Ta, Ti, Mg, Hf, and Zr.

V, W, No, Nb, Si, etc. and their alloys can be mentioned, and these can be used for vapor deposition, sputtering, Cv
A method such as D is used to provide a predetermined size, shape, and thickness at a predetermined position.

Furthermore, the cover plate 10. The materials constituting the surrounding wall member 5 and the surrounding wall member 7 are those whose shape is not or hardly affected by heat during the production of the recording head or under the environment during use, and whose shape is not affected by heat or is hardly affected by the liquid during use. It is required that it be unaffected by, or hardly influenced by, Furthermore, if micro-precision machining can be easily applied, the desired surface accuracy can be easily obtained, and the liquid can be processed so that the liquid can flow smoothly through the flow path formed by them. , most of them are valid.

For example, they can be formed by photosensitive resin, photosensitive glass, plating, electroforming, screen printing, etc. Furthermore, the materials and molding methods of the discharge plate 10, the surrounding wall member 5, and the surrounding wall member 7 may be changed as necessary. Of course, the materials and methods described above may be selected.

〔Example〕

Next, one preferred procedure for manufacturing the liquid jet recording head of the present invention will be described as an example.

In this example, a 4 x 3 cIn alumina ceramic support substrate 102 was printed using a printing method, and a glaze layer was made into a smooth layer 103 and fired to a thickness of 30 μm in an area of 3 x 2 cm at the center of the substrate to form a substrate 101. Snow (boronized as heat generating resistance layer 111 by ivy) Funium HfB
, was formed to a thickness of 150 OA, and then a pTi layer of 50 A and an At layer of 5000 A were successively deposited by electron beam evaporation.

Next, what about the electrode layer and heating resistor layer?
(Turns are formed by sequential etching, with a thickness of 30 μm.
The width and side of the heat-active surface were 150 μm long, and the resistance including the At electrode resistance was 120 Ω.

Furthermore, silicon dioxide (SiO□) was deposited as an upper layer 114 to a thickness of 20 μm by high-rate sputtering to form the substrate 101 of the liquid jet recording head. Next, two liquid supply ports 3 with a diameter of 51 Vm were provided on the substrate 101 by laser machining, and then a permanent type/photosensitive resin with a thickness of 50 μm was laminated on the substrate 101. Thus, the desired shapes of the liquid flow path section 6 and the liquid chamber section 8 are etched from this photosensitive resin in 7 etching steps (flow path is 80 μm, liquid chamber width is 0.5 μm).
7wL), and a cover plate 10 is made of a Ni electroformed plate with a thickness of 30 μm, on which a discharge hole 9 with a diameter of 50 μm has been previously machined.
Then, the electrothermal transducer 104 was bonded so that the ejection holes 9 were located above it, thereby obtaining a liquid jet recording head 100.

In addition, in the above example, the smooth layer 103 may be a recording liquid, or it may be provided only in the portion that comes into contact with the liquid, for example, and not in the lower part of the surrounding wall member 5 or the surrounding wall member 7. Of course, similar effects can be obtained. Furthermore, if microfabrication similar to the electrode pattern is possible,
Further, in this embodiment, the discharge direction is perpendicular to the electrothermal converter 104, which is a so-called side shooter type, but the electric It goes without saying that similar effects can be obtained in a so-called edge shooter type liquid jet recording head in which the ejection direction is parallel to the heat converter 104.

Further, if necessary, an organic resin layer for protecting defective portions may be further provided on the upper layer 114, and a metal layer may be laminated to further improve cavitation resistance.

The present inventor, Hiro, conducted an experiment to apply a 30V rectangular voltage of 10μS to the electrothermal transducer 104 of the recording head created in this way.
It was confirmed that the liquid was ejected from the orifice in accordance with the applied signal and that flying droplets could be stably formed. In other words, in a conventional recording head using a substrate with poor planar smoothness, repeated formation of such droplets can cause electrolytic corrosion of the At electrode, HfB, and resistor, and increase the rate of change in resistance of the resistor. Generally speaking, disconnection due to dielectric breakdown between the electrodes and an increase in resistance value occur, causing ink to no longer be ejected, but in this example, such failures can be prevented and the number of repetitions, that is, the number of durability can be increased. be able to.

Furthermore, when such a conventional substrate with poor smoothness is used, the yield during manufacturing is also reduced. The main causes of this are irregularities in resistance values, short circuits between electrodes and resistors, and work errors that make it difficult to see the boundaries of patterns because they are not smooth.According to the present invention, however, it is possible to It also contributes to improving yield.

Table 1 below shows an example comparing the smoothness of the substrate surface, the yield rate, and the number of durability cycles.

Table 1 ◎ 90 inches or more Q 70% or more Δ 50% or more ×
As is clear from the results in Table 1, the head of the present invention provided with a smooth layer was able to stably achieve a durability of 109 times.

〔effect〕

As explained above, the smoothness of the substrate of a liquid jet recording head is very important in the liquid contact part, and according to the present invention, the center line average roughness Ra can be set to 0 on the surface of the supporting substrate having a rough surface. .By providing a smooth layer that can form a surface of 1 μm or less, it has excellent overall durability even after frequent repeated use and long-term continuous use, and maintains its initial good droplet formation properties over a long period of time. It has now become possible to provide a liquid jet recording head that can be stably maintained over a long period of time.

Furthermore, according to the present invention, it is possible to significantly improve the yield in manufacturing and processing as well as the reliability in use compared to the prior art.

It goes without saying that the application of the present invention is not limited to a recording head having a plurality of liquid ejecting orifices, but can also be applied to a recording head provided with a single orifice.

[Brief explanation of drawings]

FIG. 1(A) is a perspective view schematically showing an example of the configuration of a conventional liquid jet recording head, FIG. FIG. 2B is a perspective view schematically showing an example of the configuration of the liquid jet recording head according to the invention, and FIG. 2B is a cross-sectional view taken along the line Y-Y. 1, 100... Recording heads 2, 101, 102... Substrate 3... Distribution holes 4, 104... Electrothermal converter 4A... Heat acting surface 5... Surrounding wall member 6... Liquid Flow path section 6A... Heat action area 7... Surrounding wall member 8... Liquid chamber section 9... Orifice 10... Discharge plate 11.111... Heat generating resistance layer 12.13... Electrode 14. 114... Upper layer 24, 124... Heat generating section 25... Liquid discharge section.

Claims (1)

[Scope of Claims] An orifice for discharging a liquid to form flying droplets; a liquid flow path communicating with the orifice; In a liquid jet recording head having an energy generating body that generates energy used for forming the energy generating body, the surface roughness of the substrate on which the energy generating body is provided is JIS standard, and the center line average roughness Ra is Ra. A liquid jet recording head characterized in that the particle diameter is ≦0.1 μm. (Margin below)