JPH0322305B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention generally involves ejecting and flying a recording liquid called ink as small droplets from a fine orifice.
The present invention relates to a recording head that performs recording by adhering small droplets to a recording surface, and in particular to an inkjet recording head based on a novel and unprecedented ink ejection principle. 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 does not require special fixing treatment on plain paper. The so-called inkjet recording method, which can perform recording on images, 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. The inkjet recording method is a method in which droplets of a recording liquid called ink are ejected using various principles of operation, and the droplets are attached to a recording material such as paper to perform recording. The present applicant has also already proposed a new system related to such an inkjet recording method. This new method has been proposed in Japanese Patent Application No. 118798/1982, and its basic principle is as outlined below. In other words, this new in-jet recording method applies a thermal pulse as an information signal to the recording liquid introduced into an action chamber that can contain the recording liquid, causing the liquid to change its state. In this method, the liquid is ejected and flown as small droplets from an orifice attached to the previous chamber according to the generated acting force, and the liquid is 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 it can be easily adapted to high-speed recording by forming a multi-array configuration, but on the other hand, the durability of the implementation device is quite high. The disadvantage of not having one was acknowledged. That is, since this implementation device employs a heating element as a means for inputting thermal pulses to the recording head, it is oxidized and degraded during repeated use in contact with the recording liquid. Inconveniences were often observed, such as the recording liquid burning on the heating element, and when using a conductive recording liquid, it was electrolyzed, interfering with the intended ejection of droplets. . Therefore, the main object of the present invention is to provide a recording head that has a long service life and an ink jet recording apparatus using the recording head. Another object of the present invention is to provide a recording head that is structurally simple and ensures stable ejection of recording droplets over a long period of time due to thermal action, and an ink jet recording apparatus using the same. The purpose of
A first invention includes a heating resistor, an electrode for energizing the heating resistor, and a protective layer for protecting the heating resistor and the electrode, and the heating resistor is provided in a liquid path communicating with a discharge part. A recording head that causes a state change due to heat in the liquid supplied into a liquid path and ejects the liquid based on the state change, the recording head comprising a plurality of the heating resistors and the electrode as the electrode. A common electrode common to a plurality of heating resistors and a selection electrode for selectively driving the plurality of heating resistors are provided on the same substrate, and the protective layer has a common electrode common to the plurality of heating resistors, a common electrode, and a selection electrode of the substrate. It is formed by laminating it on the surface where the electrode is, and has a specific resistance of 5×10 ⁵ Ω・
cm or more, and has a thickness of 0.1 μm to 5 μm, and has a wall portion on the protective layer that partitions the plurality of heat generating resistors and forms a liquid path corresponding to each of the plurality of heat generating resistors. The second invention provides a plurality of heat generating resistors, a common electrode common to the plurality of heat generating resistors as electrodes, and a selection electrode for selectively driving the plurality of heat generating resistors on the same substrate. The specific resistance formed by laminating multiple heating resistors, common electrodes, and selective electrodes on the surface is 5×10 ⁵ Ω・
cm or more, with a thickness of 0.1 μm to 5 μm, and a wall portion on the protective layer that partitions the plurality of heat generating resistors and forms a liquid path corresponding to each of the plurality of heat generating resistors. a head, and the heating resistor using the common electrode and selection electrode of the recording head;
means for supplying a voltage pulse that generates thermal energy and causes the ink to change its state due to heat; This is an ink jet recording device that performs recording by depositing ink. In other words, in the recording head of the present invention, the electric/thermal converter (heating resistor) as a means for applying an acting force to the recording liquid and the outer surface of its lead electrode have a specific resistance of 5.
By coating with a thin film of ×10 ⁵ Ω・cm or more so that it comes into direct contact with the recording liquid, or by electrically insulating it and the recording liquid, its usage durability can be improved. The performance and printing stability have been sufficiently improved. Hereinafter, the present invention will be described in detail with reference to illustrations and specific examples. FIG. 1 shows an outline of the main parts of the recording apparatus of the present invention. That is, the heat generating part 2 is provided on the surface of the heat generating element installation board 1. Further, as the material of the substrate 3, glass, ceramics, heat-resistant plastic, etc. are used. The substrate 3 is pre-formed with a chamber 4' that accommodates ink before ejection and a long groove 4 that constitutes an ejection orifice 5. After aligning the
They are joined and integrated with adhesive. Next, the liquid ejection principle related to this illustrated device will be briefly described. FIG. 2 is a cross-sectional view of the groove 4 along the axis. 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 of the chamber 4', the 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 10. Recording is then performed by the droplets 10 adhering to an arbitrary recording material such as paper (not shown). In FIG. 2, the detailed structure of the heating element installation board 1 is illustrated, and this heating part 2 includes a heat storage layer 7, a heating resistor 11, and an electrode 8 in this order on a substrate 6 made of alumina or the like. After the heating resistor 11 and the electrode 8 are laminated using a thin film forming technique and patterned into a predetermined shape, a protective layer 9 is further laminated. This heat generating part 2 has a groove 4.
The structure is such that the inside is exposed. In the heating element installation substrate 1, the protective layer 9 is in direct contact with the ink (that is, the surface of the heating element installation substrate 1 that is the ink contact area is covered with a protective layer). This prevents the heat generating resistor 11 and the electrode 8 from being oxidized by contact with the ink, and conversely from insulating them and preventing the ink from being electrolyzed. This prevents the ink from being electrolyzed. On this protective layer, a wall for forming an ink liquid path, which will be described later, will be placed to separate multiple heat generating parts, but since the protective layer covers the entire surface, it will make the thermal characteristics uniform. It is possible to bring about an effect in the direction of Also,
Overall stabilization is achieved since the areas where the walls are located are all protective layers. Specifically, in the present invention, the protective layer 9 has a specific resistance of 5×10 ⁵ Ω·cm.
A thin film having a thickness of about 0.1 μm to 5 μm is formed. Note that the thickness of the protective layer 9 influences the thermal response of ink droplet ejection or the quality of energy efficiency, so it is desirable that it be as thin as possible. Considering this and the quality of the insulation effect, it is estimated that 0.2μ
A thin film with a thickness of m to 3 μm is more preferable. With the protective layer having the above structure, it is possible to provide a recording head that has excellent overall ejection response and further improves the effective use of thermal energy. Further, the details of the protective layer 9 will be explained, but in the present invention, various materials listed below are formed using known film forming techniques. That is, in the present invention, the protective layer 9 may include titanium oxide, vanadium oxide, niobium oxide, molybdenum oxide, tantalum oxide, tungsten oxide, chromium oxide, zirconium oxide, hafnium oxide, lanthanum oxide, yttrium oxide, manganese oxide, etc. transition metal oxides,
Furthermore, metal oxides such as aluminum oxide, calcium oxide, strontium oxide, barium oxide, 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 even semiconductors such as amorphous silicon and amorphous selenium, which have low resistance in bulk, can be sputtered, Thin films that become highly resistive during manufacturing processes such as CVD, vapor deposition, gas phase reaction, and liquid coating are generally 0.1 μm to 5 μm thick, preferably
A film is formed to a thickness of 0.2 μm to 3 μm. In addition, other characteristics include good film formation properties, a dense structure with few pinholes, no swelling or dissolution in the ink used, good insulation properties when formed, and high heat resistance. Resins with physical properties, such as silicone resins, fluororesins, aromatic polyamides, addition polymerization polyimides, polybenzimidazole, metal chelate polymers, titanate esters, epoxy resins, phthalate resins, thermosetting phenolic resins, P-vinylphenol resin, Zylock resin, triazine resin,
The protective layer 9 can also be formed by forming a film of BT resin (triazine resin and bismaleimide addition polymer resin) or the like. In addition to this, there is also a method of forming a film using a polyxylylene resin and its derivatives by vapor deposition. Furthermore, various organic compound monomers such as thiourea, thioacetamide, vinylferrocene,
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-tri The protective layer 9 can also be formed by forming a film of chlorobenzene or propane by a plasma polymerization method. The effects of the present invention will be more clearly understood from the Examples and Comparative Examples detailed below. Examples 1 to 19 First, heating element installation boards corresponding to the following Examples and Comparative Examples were created in the following manner. FIG. 3a shows an enlarged perspective view of the substrate. SiO ₂ heat storage layer 13 (thickness
After forming the ZrB ₂ heating resistor layer 14 (thickness: 800 Å) and the aluminum electrode layer 15 (thickness: 5000 Å), selective etching was performed to form a pattern with a width of 40 μm and a length of 40 μm.
A heating resistor 14' of 200 μm was formed. In addition, the selection electrode 15a and the common electrode 15b are etched.
was formed. Furthermore, as shown in FIG. 3b, the electrode 1
5a, 15b and the heating resistor 14', a protective layer 16 as shown in Table 1 below was laminated on the substrate as described in FIG. In addition, apart from these, a plurality of grooves 18 (width 40 μm, depth
A grooved plate 20 was also created by cutting a groove (40 μm) and a groove to become the common ink chamber 19 using a micro cutter. Each heating element installation board and grooved plate created in this way are joined together after aligning the heating elements and the grooves, and then ink is supplied from an ink supply section (not shown) to the common ink chamber 19. An ink introduction tube 21 for introducing the ink was also connected to complete a recording head block 22 as shown in FIG. 5 in an integrated manner. Furthermore, this block 22 includes the aforementioned selection electrode,
A lead board having electrode leads (a common electrode lead and a selection electrode lead) connected to the common electrode was attached. Next, as a discharge experiment condition, a rectangular voltage pulse of 40 V was applied to the heating resistor portion through the electrode lead with a pulse width of 10 μsec (short pulse width) and a pulse input period of 200 μsec. Incidentally, the composition of the ink used was 70 parts by weight of water, 29 parts of diethylene glycol, and 1 part of black dye. When an ink droplet ejection experiment was conducted using the above ejection test conditions and ink, excellent results in terms of durability were obtained as shown in Table 1 below. It was also excellent in recording performance. The durability of these Examples and Comparative Examples was evaluated based on the number of times electric pulses could be repeatedly applied, as follows. Durability evaluation criteria A...10 ⁹ times or more B...10 ⁸ to 10 ⁹ times C...10 ⁵ times or less

【table】

【table】

[Table] From the above examples, by interposing the protective layer,
It can be seen that the durability of the recording head is significantly improved. Incidentally, the heating element shown in the above explanation is conventionally a thermal printing head (that is, a thermal head) widely used in the field of thermal recording.
can be applied. They are: how to create;
The head is classified into thick film heads, thin film heads, and semiconductor heads depending on the heat generating resistor, but all of them can be used in the present invention. However, especially when performing high speed, high resolution recording, it is currently desirable to utilize thin film heads. Further, the recording ink used in the present invention includes water,
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 alcohol such as ethanol or toluene. In order to avoid clogging the ejection orifice, it is effective to filter the ink after it is produced or to provide a filter in the ink flow path, as in the case of existing inkjet recording methods. As described above in detail, the present invention provides a high-performance recording head that always performs stable ink discharge and produces high-quality recorded images at high speed, and an ink jet recording apparatus using the same. I can do it.

[Brief explanation of drawings]

1 and 2 are schematic diagrams depicting only the main parts of a droplet jet recording device, and FIGS. 5 are schematic diagrams for explaining other embodiments of the present invention, respectively. In the figure, 1 is the heating element installation board, 2 is the heating element,
4' is a chamber, 5 is a discharge orifice, 8, 15, 15
a, 15b are electrodes, 9, 16 are protective layers, 11, 1
4 and 14' are heating resistors, 18 is a groove, 19 is a common ink chamber, 20 is a grooved plate, and 22 is a recording head block.

Claims (1)

[Scope of Claims] 1. A heating resistor, an electrode for energizing the heating resistor, and a protective layer for protecting the heating resistor and the electrode, and a liquid path communicating with the discharge part. A recording head which causes the heating resistors to correspond to each other, causes a state change due to heat in the liquid supplied into the liquid path, and ejects the liquid based on the state change, the plurality of the heating resistors and the above recording head. The protective layer has a common electrode common to the plurality of heat generating resistors as an electrode, and a selection electrode for selectively driving the plurality of heat generating resistors on the same substrate, and the protective layer includes a plurality of heat generating resistors of the substrate, The specific resistance formed by laminating on the surface with the common electrode and the selection electrode is 5 × 10 ⁵ Ω・cm or more,
A wall portion having a thickness of 0.1 μm to 5 μm and partitioning the plurality of heating resistors and forming a liquid path corresponding to each of the plurality of heating resistors is provided on the protective layer. Record head. 2. A plurality of heating resistors, a common electrode common to the plurality of heating resistors as electrodes, and a selection electrode for selectively driving the plurality of heating resistors are provided on the same substrate, and the plurality of heating resistors of the substrate are common. a protective layer which is laminated on the surface of the electrode and the selection electrode and has a specific resistance of 5×10 ⁵ Ω·cm or more and a thickness of 0.1 μm to 5 μm; and a protective layer that partitions the plurality of heat generating resistors. A recording head is provided with a wall portion on the protective layer that forms a liquid path corresponding to each body, and the common electrode and selection electrode of the recording head are used to generate thermal energy in the heating resistor. means for supplying a voltage pulse that causes the ink to change its state due to heat, and performs recording by attaching ink droplets ejected from the ejection part of the recording head to the recording medium in accordance with the state change. Ink jet recording device.