JPS5931941B2 - Droplet jet recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention generally relates to a droplet jet recording apparatus that ejects a recording liquid called ink as small droplets from a fine orifice and performs recording by adhering the droplets to a recording surface. , relates to a droplet jet recording device based on a novel ink jetting principle that has never existed before.

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
Recording is performed by causing droplets of a recording liquid called ink to fly based on various operating principles and making them adhere to a recording material such as paper.

The present applicant has also already proposed a new system related to such an inkjet recording method. This new system was proposed in Japanese Patent Application No. 118798/1982, and its basic principle is as outlined below. In other words, this new ic-jet recording method applies a thermal pulse as an information signal to the recording liquid introduced into a liquid chamber that can contain the recording liquid, and causes the liquid to change its state. In this method, the liquid is ejected and flown as small droplets from an orifice attached to the liquid chamber according to the acting force generated by the liquid chamber, and the liquid is attached to the recording member to perform recording. By the way, this new method has
The structure of the implementation device is simpler than the conventional one, and while it has the great advantage of being easily adaptable to high-speed recording with a multi-array configuration, it has been recognized as a disadvantage that the durability of the implementation device is not very high. .

That is, since this implementation device employs a heating element as a means for inputting thermal pulses to the recording liquid, it is possible that the heating element will be oxidized and deteriorated during repeated use in contact with the recording liquid. Inconveniences have often been observed, such as the recording liquid burning on the heating element, or the recording liquid being electrolyzed, which interferes with the intended ejection of droplets. Therefore, in the present invention, we completely eliminate the serious drawbacks found in the quick jet recording method disclosed in Japanese Patent Application No. 52-118798, and also provide a new structure for droplet jetting that is further improved. Suggest a recording device.

That is, the main object of the present invention is to provide a droplet jet recording device that has a long service life.

Another object of the present invention is to provide a droplet jet recording device that is structurally simple and that ensures stable ejection of recording liquid over a long period of time due to thermal action.

In short, the present invention achieves the above-mentioned objects by ejecting and flying a recording liquid introduced into a chamber communicating with an ejection orifice as a droplet from the orifice in accordance with an input signal, and causing the droplet to be covered. A droplet jet recording device that performs recording by adhering to a recording surface, which includes a heating resistor as a source of the acting force for ejecting the droplets, and a coating protection that prevents the heating resistor from coming into contact with the recording liquid. This is a droplet jet recording device characterized in that an electric/thermal converter consisting of a layer is provided inside at least a part of the chamber. 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 heating element 2 is provided on the surface of the heating 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' for accommodating the ink before ejection and a long groove 4 constituting the ejection orifice 5. After alignment, they are joined and integrated with adhesive. Next, the liquid ejection principle related to this illustrated device will be briefly described. Second
The figure is a sectional view taken along the axis of the groove 4. Recording ink is supplied into the chamber 41 as indicated by the arrow in the figure. Now, when a signal is applied from the outside to the heating element 2 attached to a part of the chamber 41, the heating element 2 generates heat and gives thermal energy to 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 2 is illustrated, and the heating element 2 consists of a heat storage layer 7, a heating resistor 11, an electrode 8, a protective layer 9 and a substrate 6 made of alumina or the like. They are laminated in the order of 9' using a thin film forming technique. And this heating element 2
is exposed in the groove 4. In the heating element installation substrate 1, the protective layer 9' is in direct contact with the ink, but both of these protective layers 9 and 9' prevent the heating resistor 11 and the electrode 8 from being oxidized or adversely affected by contact with the ink. This prevents the ink from being electrolyzed. In the present invention, thermal energy is transferred to the ink through the protective layers 9, 9', so their thickness has a large effect on the thermal responsiveness of inter-droplet ejection and the printing energy efficiency. In other words,
In the present invention, the thinner the protective layers 9, 9', the better the thermal conductivity, the better the thermal response, and the less printing energy required. However, as long as the protective thin film is formed by a vacuum evaporation method or a sputtering method, as is conventionally done in the manufacture of so-called thermal heads, the thinner the protective thin film is, the more difficult it is to connect the electrode 8 and the resistor 11. The step part is likely to be exposed, and the protective thin film itself is likely to have defects such as pinholes. Therefore,
Conventionally, it has been thought that the thickness needs to be such that the electrode 8 and the resistor 11 are not exposed even if the thermal conductivity is sacrificed to some extent. However, in the present invention, as a result of careful consideration and ingenuity, the electrode 8 and the heating resistor 11 that constitute the heating element 2 come into contact with the ink even though the thickness of the entire protective layer is extremely thin. can be completely prevented.

That is, in the present invention, after patterning the electrode 8 and the resistor 11 into a predetermined shape, the first protective layer 9 is further formed using beryllium oxide, silicon oxide, magnesium oxide, aluminum oxide, tantalum oxide, zirconium oxide, or the like. or carbides such as beryllium carbide, or nitrides such as tantalum nitride, aluminum nitride, and boron nitride, or borides such as beryllium boride, or lanthanum sulfide, praseodymium sulfide, and sulfide. Sulfides such as neodymium and yzterbium sulfide are deposited to a size of 0.01 μm or more using techniques such as electron beam evaporation and sputtering.
Laminated in a thin film of about 1 μm.

In addition to this, the first protective layer 9 may be made of silicone resin, fluorine resin, aromatic polyamide, addition polymerization type polyimide,
Polybenzimidazole, metal chelate polymer, titanate ester, epoxy resin, phthalate resin, thermosetting phenol resin, P-vinylphenol resin, Zylock resin, triazine resin, BT resin (triazine resin and bismaleimide addition polymer resin) A film of heat-resistant resins such as the above may be formed to a thickness of 0.01 μm to 1 μm using techniques such as spray coating, spin coating, and dip coating. In addition,
The first protective layer 9 is not limited to a single-layer structure, but may of course be formed into a multilayer structure by overcoating. In a thermal head applied to so-called heat-sensitive recording, the protective layer does not come into contact with liquid, so there was no need to consider the pinholes in the protective layer 9 described above. However, when the protective layer is in direct contact with the liquid as in the ic-jet recording method according to the present invention, measures to prevent pinholes in the first protective layer 9 become an important issue when considering the durability of the recording device. . Film defects such as pinholes that inevitably occur in the first protective layer 9 are covered with a second layer of various resins.
By laminating the protective layer 9' and filling it, almost complete coverage is achieved.

That is, the second protective layer 9' in the present invention functions as a so-called sealing layer for the first protective layer 9. Second
Resins that can be used in the present invention as the protective layer 9' include:
1. Good film forming properties, 2. Dense structure with few pinholes, 3. Does not swell or dissolve in the ink used, 4. Good adhesion with the first protective layer, 5. High heat resistance. For example, silicone resin, fluororesin, aromatic polyamide, addition polymerization type polyimide, polybenzimidazole, metal chelate polymer, titanate ester, epoxy resin, phthalate resin, thermosetting resin, etc. Most preferred are polyphenolic resins, P-vinylphenol resins, Zyloc resins, triazine resins, BT resins (triazine resins and bismaleimide addition polymer resins), and the like. In addition to this, it is also desirable to form a film using a polyxylylene resin or a derivative thereof by vapor deposition.

Furthermore, various organic compound monomers such as thiourea,
Thioacetamide, vinylferrocene, 1,3,5,1-trichlorobenzene, chlorobenzene, styrene, ferrocene, picoline, naphthalene, pentamethylbenzene, nitrotoluene, acrylonitrile, diphenylselenide, P-toluidine, P-xylene, N,N- Dimethyl-P-toluidine, toluene, aniline, diphenylmeryl, hexamethylbenzene, malononitrile, tetracyanoethylene, thiophene, benzene selenol, tetrafluoroethylene, ethylene, N-nitrosodiphenylamine, acetylene, 1,2 , 4,-tritalolobenzene, or propane may be formed as the second protective layer 9' by plasma polymerization. In order to form the above-mentioned heat-resistant resin as the second protective layer 9', the resin is diluted with a solvent, and then spin-coated on the first protective layer 9.
After applying using methods such as spray coating and dip coating,
Just let it dry and harden. The thickness of this heat-resistant resin influences the thermal response of ink ejection or the quality of energy efficiency, so it is desirable that it be thin.

In the present invention, the film thickness after drying is usually 0.01 μm to 10 μm.
μm Preferably 0.1 μm to 5 μm1 Optimally 0.1 μm
~3 μm. In addition, in the present invention, when applying a conductive ink using an aqueous solvent, the first protective layer 9,
Either or both of the second protective layers 9' have a specific resistance of 5.
X105Ω? It is desirable to form it so that it becomes the above.

The effects of the present invention are demonstrated by the examples detailed below.
will be more clearly understood.

Examples 1 to 9 First, a heating element installation board was created in the following manner.

FIG. 3a shows an enlarged perspective view of the substrate. On the alumina substrate 12, a SlO2 heat storage layer 13 (thickness of several μ), Z
After forming the rB2 heating resistor layer 14 (thickness 800λ) and the aluminum electrode layer 15 (thickness 5000mm), a heating resistor 14' having a width of 60 μm and a length of 75 μm was formed by selective etching. In addition, the selective electrode 15 is etched.
a and a common electrode 15b were formed. Furthermore, as shown in FIG. 3b, a SlO2 protective layer 16 (thickness 0.5 mm) is formed on the electrode layer 15.
01 μm) are laminated. Furthermore, this SiO2 protective layer 1
6, apply the heat-resistant resin shown in the table below in liquid form to the indicated film thickness, vacuum impregnate it, and then apply the resin shown in the table below.
The heating element installed substrates of Examples 1 to 9 were prepared by baking and drying under the same conditions as described in Section 1.

Separately, a plurality of grooves 18 (width: 70 μm, depth: 60 μm) and a groove that will become a common ink chamber 19 are formed by cutting the glass plate 17 using a microcutter, as shown in FIG. A grooved plate 20 was also created.

Each heating element installation board and grooved plate created in this way are joined 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 ink was also connected to complete a recording head block 22 as shown in FIG. 5.

Further, this block 22 was attached with a lead board having the aforementioned selection electrode and electrode leads (a common electrode lead and a selection electrode lead) connected to the common electrode.
As an example of an ejection experiment, an ink droplet ejection experiment was conducted using the ink composition and the above-mentioned ejection experimental conditions, and as shown in the table below, excellent results were obtained in terms of durability.

It was also excellent in recording performance. The durability of these Examples was evaluated based on the number of times electric pulses could be repeatedly applied, as follows.

Examples 10 to 23 The SlO2 protective layer 16 in Examples 1 to 9 was replaced with the material (film thickness) listed in Table 2 below, and the materials (film thickness) listed in Table 2 below were formed on the upper surface, respectively. After coating with heat-resistant resin,
Baking and drying was performed to produce heating element installed substrates of Examples 10 to 23 in the same manner as Examples 1 to 9.

Thereafter, an ink droplet ejection experiment was conducted in the same manner as in Examples 1 to 9 to evaluate the durability of the recording apparatus.

The evaluation criteria were the same as in Examples 1 to 9, and the results are summarized in Table 2. Incidentally, as the above-mentioned heating element, a thermal printing head (that is, a thermal head) widely used in the field of thermal recording can be used.

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, especially when performing high speed, high resolution recording, it is currently desirable to utilize thin film heads. Furthermore, the recording interface used in the present invention contains a main solvent such as water, alcohol such as ethanol, or toluene, a wetting agent such as ethylene glycol, a surfactant, and various dyes. It is created by dissolving or dispersing etc.

Note that in order to prevent clogging of the orifice, it is effective to pass the ink through a filter after preparation or to provide a filter in the ink flow path, as in the case of existing quick-jet recording methods. As described in detail above, according to the present invention, it is possible to provide a high-performance droplet jet recording device that always performs stable ink discharge and provides high-quality recorded images at high speed.

[Brief explanation of the drawing]

Both FIG. 1 and FIG. 2 are schematic diagrams depicting only the main parts of a droplet jet recording device in order to explain one embodiment of the present invention, FIG. 3 a1 FIG. 3 b1 FIG. 4 and 5 are schematic diagrams for explaining other embodiments of the present invention, respectively. In the figure, 1 is a heating element installation board, 2 is a heating element, 4/ is a chamber, 5 is a discharge orifice, 8, 15, 15a, 15b are electrodes, 9, 9', 16 are protective layers, 11, 14 , 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)

[Claims] 1. A recording liquid introduced into a chamber communicating with an ejection orifice is ejected as small droplets from the orifice in accordance with an input signal and caused to fly, and the droplets adhere to a recording surface. The droplet jet recording device performs recording, and as a source of the acting force for ejecting the droplets, an electrical conductor consisting of a heating resistor and a protective coating layer that prevents the heating resistor from coming into contact with the recording liquid is used. A droplet jet recording device characterized in that a heat converter is provided inside at least a small portion of the chamber. 2. The droplet jet recording apparatus according to claim 1, wherein the protective layer has a multilayer structure including, at least in part, a sealing layer that prevents penetration of recording liquid. 3 The specific resistance of at least one layer constituting the protective layer is 5.
The droplet jet recording device according to claim 2, wherein the droplet jet recording device has a resistance of 10^5 Ωcm or more. 4. The droplet jet recording device according to claim 2, wherein the sealing layer has a layer thickness of 0.01 to 10 μm.