JPH0521074B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an ink jet recording head that ejects a recording liquid generally called ink as small droplets from a fine orifice and performs recording by simulating the adhesion of these droplets to a recording surface. The present invention relates to an ink jet recording head having a configuration. Among the various recording methods currently known, it is a non-impact recording method that generates almost no noise during recording, is capable of high-speed recording, and can record on plain paper without requiring any special fixing process. The so-called inkjet recording method (droplet jet recording method) is
It is recognized as an extremely useful recording method.
Various methods have been proposed for this inkjet recording method, some have been improved and commercialized, and others are still being worked on to put them into practical use. be. In the inkjet recording method, recording is performed by ejecting small droplets of recording liquid called ink using various principles of operation and adhering them to a recording medium such as paper. The present applicant has also already proposed a new system related to such an inkjet recording method. This new method was proposed in Japanese Patent Application No. 118798/1982, and its basic principle is as outlined below. In other words, this new inkjet recording method is
A thermal pulse is applied as an information signal to the recording liquid introduced into a fine liquid chamber that can contain the recording liquid, and an acting force such as a pressure wave is generated when the recording liquid causes a state change. Accordingly, in this method, the recording liquid is ejected and flown as small droplets from an orifice attached to the liquid chamber, and the droplets are attached to the recording member to perform recording. By the way, this new method has the great advantage that the configuration of the implementation device is simpler than the conventional one, and that the ejection orifice can be configured in a multi-array to easily adapt to high-speed recording.However, on the other hand, the durability of the implementation device is There was an issue that needed to be resolved, namely that the quality was not that high. That is, since this implementation device employs a heating resistor and its lead electrodes as a means for inputting thermal pulses to the recording liquid, these are repeatedly used in contact with the recording liquid. During this time, there was a risk that oxidation and corrosion would cause functional deterioration, or in some cases, the equipment would become inoperable. In addition, there is a risk that insoluble components may be mixed in the recording liquid due to electrolysis of the recording liquid or corrosion of the lead electrodes, thereby interfering with the intended ejection of droplets. Therefore, in the present invention, the above-mentioned patent application No. 52-118798
This paper proposes an inkjet recording head with a new configuration that completely eliminates the problems that need to be solved in the inkjet recording method disclosed in the No. 2003, and which is further improved. That is, the main object of the present invention is to propose an ink jet recording head that has a long service life. Another object of the present invention is to provide an ink jet recording head which is structurally simple and which ensures stable ejection of recording droplets over a long period of time due to thermal action. In addition, another object of the present invention is to provide a multi-array type ink jet recording head that guarantees excellent durability in use and high-speed recording. The present invention that achieves these objects includes an ejection port for ejecting ink, an ink path communicating with the ejection port, and an ink path provided corresponding to the ink path and used for ejecting ink from the ejection port. A heat generating part that generates thermal energy, an electrode for applying an electric signal to the heat generating part, a common liquid chamber for supplying ink to the ink path, and a baking-treated An ink jet recording head characterized by having an inorganic coating. EMBODIMENT OF THE INVENTION Hereinafter, the present invention will be explained in detail according to illustrated examples. First, a specific example of an ink jet recording head, which is a main part of an ink jet recording apparatus according to the present invention, and a liquid jet principle will be described with reference to FIGS. 1 and 2. FIG. 1 shows an outline of an ink jet recording head, which is the main part of an ink jet recording apparatus. That is, the heat generating part 2 is provided on the surface of the heat generating element installation board 1. Further, as the material for the substrate 3, glass, ceramic, heat-resistant plastic, or the like is used. A long groove 4 constituting a chamber 4' for consuming ink before ejection and an ejection orifice 5 is formed in advance on the substrate 3, and this substrate 3 and the heating element installation substrate 1 are connected to the heating element 2. After aligning the grooves 4 and 4, they are joined and integrated with adhesive. Next, the principle of ink ejection related to this illustrated device will be briefly described. FIG. 2 is a cross-sectional view of the groove 4 along the axis. The recording ink IK is supplied into the chamber 4' as indicated by the arrow in the figure. Now, when an electric signal is applied from an external electric signal applying means to the heat generating part 2 attached to a part of the chamber 4', the heat generating part 2 generates heat and transfers thermal energy to the ink IK in the vicinity. give. The ink IK that has received thermal energy undergoes state changes such as volumetric expansion or the 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 IK is ejected as small droplets 10. . And this droplet 1
Recording is performed by attaching a 0 to an arbitrary recording material such as paper (not shown). In Figure 2,
The detailed structure of the heating element installation board 1 is also illustrated,
This heat generating section 2 is constructed by sequentially stacking an accumulation layer 7, a heat generating resistor 11, and an electrode 8 on a substrate 6 made of alumina or the like using a thin film forming technique.
After patterning into a predetermined shape, a protective layer 9 made of metal oxide is further laminated.
The heat generating portion 2 is configured to be exposed inside the chamber 4'. In the heat generating section 2, the ink IK comes into direct contact with the protective layer 9;
This prevents the heating resistor 11 from coming into direct contact with the ink IK and being oxidized, or conversely, preventing the ink IK from being electrolyzed. Specifically, the thickness of the protective layer 9 affects the thermal response of ink droplet ejection or the quality of energy efficiency, so it is desirable that it be as thin as possible. Next, the following is a schematic plan view of an example of the arrangement of the heat generating part and electrodes when the so-called single-orifice type droplet jet recording device is changed to a multi-orifice type device. Figure a and Figure 3b. In FIG. 3a, (lead) electrodes 21-1, . . . , 21-5 and 22 made of aluminum or the like are shown.
-1,...,22-5, and heating resistor pattern 23
A pattern consisting of -1, . In addition, in FIG. 3b, the (lead) electrode 24
, and 25-1, . . . , 25-5 and heating resistor patterns 26-1, . . . , 26-5. In the following explanation, this pattern will be abbreviated as S type. In each of the drawings, an ink flow path, that is, an ink path (hereinafter also referred to as a flow path) is provided in areas 27 and 28 surrounded by dotted lines. When recording operations are continued using such a multi-orifice type droplet jet recording device equipped with a plurality of heating resistor patterns and their (lead) electrodes, the following phenomenon has conventionally been frequently observed. That is, (1) As the number and density of heating resistor patterns increase, electrode corrosion tends to occur in the recording liquid flow path, resulting in poor recording droplet ejection conditions. (2) This kind of electrode corrosion is mostly caused by
In the illustrated example of FIG. 3b, it was observed that this phenomenon occurred in the area indicated by the crossing line, that is, in the recording liquid relay chamber. The above electrode corrosion is
It was also found that electrolysis occurs through the recording liquid based on the potential difference created between adjacent electrodes. Therefore, the inventor of the present invention realized that in order to prevent this electrode corrosion phenomenon, it is sufficient to keep the adjacent electrodes in a non-contact state with the recording liquid, and came to propose the present invention. That is, in addition to the protective film covering the heating resistor pattern, the specific measure of the present invention is to apply a baking treatment on the (lead) electrode to prevent the electrode from coming into contact with the recording liquid. It is to provide an inorganic coating. Note that it is preferable that this film not be provided on the heating resistor pattern. This is because if a protective film and this film are formed on the heating resistor pattern, the overall layer thickness will increase, which will reduce the heat transfer efficiency and, in turn, reduce the ejection efficiency of recording droplets. . In the present invention, the material for forming the film on the (lead) electrode must have good film formability;
A dense structure with few pinholes,
It is desirable to have physical properties such as not expanding or dissolving in the ink used, good adhesion to lower layers such as electrode layers, and high heat resistance.For example, silicone resin, fluororesin, aromatic polyamide, etc. , addition polymerized polyimide, polypenzimidazole, metal chelate polymer, titanate ester, epoxy resin, phthalic acid resin, thermosetting phenol resin, P-vinylphenol resin, Zylock resin, triazine resin, BT resin (with triazine resin) A resin such as bismaleimide addition polymer resin) is used. To form a film of these resins, the resin is diluted with a solvent and then applied by spin coating, spray coating, or dip coating onto the (lead) electrode (and in some cases, a protective film for the heating resistor). After coating using a method such as the above, it may be dried and hardened. In addition to this, it is also desirable to form a film using a polyxin rylene resin or a derivative thereof by vapor deposition. Furthermore, various organic compound monomers such as thiourea, thioacetamide, vinylfurocene,
1,3,5-trichlorobenzene, chlorobenzene, styrene, ferrocene, picoline, naphthalene, pentamethylbenzene, nitrotoluene, acrylonitrile, diphenylselenide, P-toluidine, P-xylene, N,N-dimethyl-P
-Toluidine, toluene, aniline, diphenylmercury, hexamethylbenzene, malononitrile, tetracyanoethylene, thiophene, benzeneselenol, tetrafluoroethylene, ethylene, N-nitrosodiphenylamine, acetylene, 1,2,4, - A film of trichlorobenzene or propane may be formed on the (lead) electrode by plasma polymerization. Apart from these, an inorganic film can also be formed by performing a baking treatment as shown in Table 2 using a solution of butyl orthotitanate, ethyl silicate, or the like. In this way, by applying a solution and baking it, it is possible to obtain an even better protective film by forming an inorganic film that has better resistance to ink and other liquids than organic materials. can. In the present invention, the thickness of the above-mentioned film is usually 0.01 μm to 10 μm, preferably 0.01 μm to 10 μm after drying.
0.1 μm to 5 μm, optimally 0.1 μm to 3 μm. In the present invention, there are two preferred methods of installing the coating as shown below. These are shown in schematic plan views in FIGS. 4 and 5. That is, FIG. 4 schematically shows the recording head portion on which the aforementioned U-shaped pattern is formed, and in this case, the above-mentioned coating is formed only in the area divided by the intersecting lines. In the recording liquid flow path outside this area, one (lead) electrode 21-1,..., 21-5
Since the electrode 2 does not come into contact with the recording liquid, the other electrode 2
Even if 2-1, . . . , 22-5 come into contact with the temporary recording liquid, no corrosion occurs. Next, FIG. 5 schematically shows the recording head portion in which the aforementioned S-shaped pattern is formed, and in this case, the electrodes 24 and 25-1, . . . exposed to the recording liquid flow path are shown in FIG. , 25-5 is completely covered with the above-mentioned coating over the entire area divided by the intersecting lines in the figure. In addition, in FIGS. 4 and 5, the same symbols as those in FIGS. 3a and 3b are given. The respective explanations also adopt the explanations related to FIGS. 3a and 3b. Hereinafter, the present invention will be explained in more detail with reference to Examples. Examples 1 to 11, Comparative Examples First, the fourth example corresponds to the following Examples and Comparative Examples.
A heating element installation board as shown in the figure was created in the following manner. _SiO2 vaporized layer (5 μm thick) on alumina substrate,
After successively forming a ZrB ₂ heating resistor layer (thickness: 800 Å) and an aluminum electrode layer (thickness: 5000 Å), heating resistor patterns 23-1,..., 23-5 with a width of 40 μm and a length of 200 μm are formed by selective etching. Formed. In addition, lead electrodes 21 of the same width are etched.
-1,...,21-5 and 22-1,...,22-5
was formed. In addition to the above operations, heating resistor pattern 23-
A SiO ₂ protective film (thickness: 1 μm) was provided in the vicinity of 1, . . . , 23-5 by sputtering. In Fig. 4 (the area corresponding to the relay chamber for ink supply indicated by the cross line is shown in the table below)
The coatings shown in Table 1 and Table 2 below were laminated. Also, apart from these, a glass plate (thickness 1mm)
As shown in Fig. 6, there are grooves 30 (width 40 μm, depth 40 μm) with the same number and pitch as the heating resistor pattern.
A grooved plate 32 is formed by cutting and forming a groove that will become an ink relay chamber 31 using a micro cutter.
It was created. Each heating element installation board and grooved plate created in this way are bonded after aligning each heating resistor pattern with the groove, and further, an ink relay chamber from an ink supply section (not shown) is connected. An ink introduction pipe 33 for introducing ink was also connected to the recording head block 31 to integrally complete a recording head block 34 as shown in FIG. Furthermore, this block 34 has the aforementioned electrodes, 21
-1,...,21-5 and 22-1,...,22-5
A lead board was attached that had electrode leads connected to it. Next, as a discharge experiment condition, a heating resistor pattern is connected to the heating resistor pattern through the electrode lead.
With a pulse width of 10μsec and a pulse input period of 200μsec
A rectangular voltage pulse of 40V was applied. Incidentally, the composition of the ink used was 70 parts by weight of water, 29 parts by weight of diethylene glycol, and 1 part by weight of black dye. When an ink ejection experiment was conducted using the above ejection test conditions and ink, the results were shown in Tables 1 and 2 below.
As shown in Figure 2, the examples obtained superior results in the durability of the recording head compared to the comparative examples. It was also excellent in recording performance. The durability of these Examples and Comparative Examples was evaluated based on the number of times an electric pulse to which ink ejection responded could be repeatedly applied, as follows. A...10 ⁹ times or more Durability evaluation criteria B...10 ⁸ to 10 ⁹ times C...10 ⁵ times or less

【table】

[Table] (Note) In the comparative example, no prescribed film formation was performed.

[Table] It can be seen from the above examples that the durability of the recording head is significantly improved by the presence of the coating on the electrodes. Incidentally, as the heating element shown in the above explanation, one that is almost the same as a thermal printing head (that is, a thermal head) conventionally widely used in the field of thermal recording may be applied depending on the conditions. can. They are classified into thick film heads, thin film heads, and semiconductor heads depending on the manufacturing method, heating resistor, etc., but all of them can be used in the present invention. However, it is currently desirable to utilize thin film heads, especially when performing high speed, high resolution recording. Furthermore, the recording ink used in the present invention is
It is prepared by dissolving or dispersing a wetting agent such as ethylene glycol, a surfactant, various dyes, etc. in a main solvent such as water, alcohol such as ethanol, or toluene. Note that in order to avoid clogging the ejection ports, it is effective to filter the ink after formation or to provide a filter in the ink flow path, as in the case of existing inkjet recording methods. As explained in detail above, in the present invention, a baked inorganic film that is denser and has excellent ink resistance and heat resistance is disposed to cover the electrode, so that the ink ejection performance is improved over a long period of time. It is possible to provide a high-performance ink jet recording head that is stable, can withstand high-speed use, and can obtain recorded images of good quality.

[Brief explanation of the drawing]

1 and 2 are schematic diagrams for explaining a specific example of an ink jet recording device according to the present invention and its ink jet principle, and FIGS. 3 a and 3 b are diagrams showing a heat generating section according to the present invention, respectively. FIG. 4 and FIG. 5 are both schematic plan views illustrating an example of arrangement with electrodes, and FIGS. 6 and 7 are schematic plan views illustrating one embodiment of the present invention, respectively. It is a schematic diagram for explaining an example. In the figure, 2 is a heat generating part, 4' is a chamber, 5 is a discharge orifice, 8, 21-1,..., 21-5, 22-
1,...,22-5,24,25-1,...,25-
5 is an electrode, 9 is a protective layer, 11 is a heating resistor layer, 2
3-1..., 23-5, 26-1,..., 26-5 are heating resistor patterns, 27 and 28 are ink flow paths,
30 and 31 are grooves, and IK is ink.

Claims (1)

[Scope of Claims] 1. An ejection port for ejecting ink, an ink path communicating with the ejection port, and thermal energy provided corresponding to the ink path and used to eject ink from the ejection port. a heat-generating part that generates an electric current; an electrode for applying an electric signal to the heat-generating part; a common liquid chamber for supplying ink to the ink path; An ink jet recording head comprising: a coating;