JPH0417793B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention involves forming recording liquid, generally called ink, into small droplets using various methods, and performing recording by adhering these ink droplets to a recording surface. The present invention relates to an inkjet head and an inkjet device equipped with the same.

[Conventional technology]

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.

In short, the ink jet recording method performs recording by ejecting and flying droplets of a recording liquid called ink and making them adhere to a recording member such as paper. The inkjet recording method is roughly divided into several types depending on the method of generating ink droplets and the control method for controlling the flying direction of the generated ink droplets. Among them, one of the representative methods is the method disclosed in USP3596275 (Sweet method), USP3298030 (Lewis and Brown method), etc., which uses a continuous vibration generation method to reduce the amount of charge. By generating a controlled flow of ink droplets and flying the ink droplets with a controlled amount of charge between deflection electrodes to which a uniform electric field is applied, the trajectory of the droplets can be controlled while being applied to paper, etc. This is for recording on a recording member. This method is also generally referred to as a continuous method.

Other typical methods that can be compared with this are, for example,
This is the method (Stemme method) disclosed in USP3747120. This method applies an electrical recording signal to a piezo vibrating element attached to a recording head that has an orifice that ejects ink for recording, and converts this electrical recording signal into mechanical vibration of the piezo vibrating element. Recording is performed by ejecting ink droplets from the orifice and adhering them to the recording member whenever necessary according to the mechanical vibrations.

This is the so-called on-demand method.

Separately, a new recording method that differs in principle and idea from these methods has also been proposed in the applicant's earlier application (for example, Japanese Patent Application No. 118798/1983). One of these new methods boils down to:
A thermal pulse is applied to the ink introduced into the action chamber as an information signal, and the ink changes its state. This is a method in which ink is ejected into small droplets and made to fly, and the droplets are attached to a recording material such as paper to perform recording.

However, with respect to the various inkjet recording methods exemplified above, there still remain technical problems common to all of them that must be solved.

Among these, a particularly important issue is the establishment of multi-array recording heads and high-density integration technology for the purpose of higher-speed inkjet recording.

Moreover, in this case, it is important to construct an inkjet recording head in which the size of the ink droplets ejected from one ejection port, the ejection speed, and the ejection direction are always uniform, and which can be easily manufactured. Ru.

[Problem to be solved by the invention]

However, it is not easy to satisfy these conditions required for such a recording head, especially from the viewpoint of manufacturing technology.

In particular, it is not easy to obtain an inkjet recording head that is easy to manufacture and assemble and has high reliability regarding ink ejection.

Additionally, a single nozzle is originally made up of fine pores, and combining multiple nozzles to complete a multi-array recording head requires a high degree of technical skill as the holes are extremely minute. However, there is a natural limit to the ability to gather these pores at a high density (for example, about 8 pores/mm or more). It is even more difficult to obtain a highly reliable high-density multi-array recording head with a good yield.

SUMMARY OF THE INVENTION Therefore, the main object of the present invention is to provide an inkjet recording head and an inkjet recording apparatus equipped with the same that satisfy the above-mentioned technical problems. An object of the present invention is to provide an inkjet recording head with high performance and an inkjet recording apparatus equipped with the same.

Another object of the present invention is to provide an inkjet recording head whose working parts are highly integrated and which has high practical reliability, and an inkjet recording apparatus equipped with the same.

Still another object of the present invention is to provide an inkjet recording head of a new configuration that guarantees high-speed, high-resolution, high-quality recording over a long period of time, and an inkjet recording apparatus equipped with the same.

Another object of the present invention is to provide an inkjet recording head that is finely machined with high precision and an inkjet recording apparatus equipped with the same.

[Means to solve the problem]

Therefore, the present invention that achieves these objectives is as follows:
``A grooved substrate provided with a plurality of grooves for forming a path communicating with an ejection port for ejecting ink, and causing a state change in the ink in the path and ejecting ink from the ejection port based on the state change. a heat generating substrate provided with a plurality of thermal energy generating means for generating thermal energy used for
and a fixing member for joining and fixing the grooved substrate and the heat generating substrate with the plurality of grooves inside (hereinafter referred to as the first invention of the present application). ) and ``a grooved substrate provided with a plurality of grooves for forming a path communicating with an ejection port for ejecting ink, and a grooved substrate that causes a state change in the ink in the path to cause ink to flow from the ejection port based on the state change. a heat generating substrate provided with a plurality of thermal energy generating means for generating thermal energy used for discharging the heat energy, such that the plurality of grooves correspond to the thermal energy generating portions of the plurality of thermal energy generating means, respectively. , a fixing member for joining and fixing the grooved substrate and the heat generating substrate with the plurality of grooves inside; and a fixing member for bonding and fixing the grooved substrate and the heat generating substrate; An inkjet device (hereinafter referred to as the second invention of the present application) comprising: means for supplying ink to a generating means;

In the inkjet head of the first invention of the present application, a grooved substrate provided with a plurality of grooves and a heat generating substrate provided with a plurality of thermal energy generating means are fixed by fixing members such that the grooves and the thermal energy generating means correspond to each other. It is constructed by joining and fixing using.

Such an inkjet head of the present invention can be manufactured by a simpler method than ever before, in which the grooved substrate and the heat generating substrate are joined and fixed using a fixing member.

In addition, since it is only necessary to press the grooved substrate and the heat generating substrate to each other by sandwiching and tightening the grooved substrate with the fixing member, there is no need to use adhesive, so there is no possibility that the adhesive will protrude into the ink path. Therefore, the size and accuracy of the ink path can be further improved. Therefore, the size, ejection speed, and ejection direction of the ink droplets ejected from the ejection ports are uniform, and the overall reliability related to ink ejection can be further improved.

In particular, since the ink jet head of the present invention uses thermal energy generating means as the energy generating means used to eject ink from the ejection ports, the above-mentioned effects are even more pronounced. This is because, for example, when a piezo element is used as the energy generating means used to eject ink, the vibration of the piezo element itself for ejecting ink acts to loosen the fixation by the fixing member. This is because there are things.

A second invention of the present application is an invention of an inkjet device which, in addition to the configuration of the inkjet head of the first invention, includes means for supplying a signal corresponding to the generation of thermal energy to the thermal energy generating means.

By the way, in an ink jet head according to an embodiment of the present invention which will be described in detail later, an ejection port for recording ink and an acting part (a part that applies an ejection force to the ink) located in an ink flow path communicating with the ejection port are as follows. Both are arranged in a multi-array at high density (for example, 8 lines/mm or more).

For reference, conventionally, in this type of inkjet recording head, the ejection ports were
For example, it was thought that it would be possible to arrange them even at a density of about 8 lines/mm. However, the high-density arrangement of 8 or more wires/mm, which is made possible by the present invention, has not yet been achieved with regard to the action portions, mainly due to functional limitations.

Further, in the present invention, there are roughly two types of methods for carving the fine grooves.

One method is to use a micro cutter to cut a flat plate made of glass, quartz, ceramics, silicon wafer, plastic, metal, etc. to a width of several μm or more.
This is a method of cutting and forming grooves with a depth of approximately 10 μm to 250 μm at a pitch of approximately 10 μm or more.

Another method is to burn a desired pattern of fine grooves onto photosensitive glass (for example, photoceram, etc.), and then etch the exposed areas with a so-called etching solution. This method has the advantage that it does not leave any defects such as chipping or microclaps that are normally found in the cut part, and that the shape of the microgrooves is always uniform as long as the burning pattern is uniform. This method has advantages compared to the former method.

Also, when crimping and fixing the above grooved substrate and another flat plate, the surface roughness of the crimped surfaces should be approximately 1 μm.
It is desirable to have a smooth surface as shown below. this is,
This is done with the intention of making the crimping surface smooth and sufficiently increasing the adhesion between the two to prevent the force generated there from unnecessarily propagating from the resulting predetermined ink flow path to other flow paths. It is.

[Reference example]

Here, a reference example will be explained in detail along with the drawings. In this reference example, a description will be given of the assembly process of a multi-array recording head. In the ink jet head of this reference example, the ink flow path including the operating portion is constructed by a simpler method than ever before, in which another flat plate is adhered and fixed to a substrate in which fine grooves are carved.

In FIG. 1, two components A and B for forming the working chamber part of the recording head are depicted in a schematic perspective view. FIG. 1a depicts part A, and FIG. 1b depicts part B. Component A is created according to the following procedure.

First, alkali metal fluoride photosensitive glass (SiO ₂ , Li ₂ O, N ₂ O, K ₂ O, Al ₂ O ₃ , Au, AgCl,
A flat plate of a composition containing CeO ₂ was polished on both sides and then cut into a size of 100 mm x 100 mm (thickness: 2 mm). Commercial products of this kind of photosensitive glass include Photoceram, Photoform, (trade name;
(manufactured by Corning Inc.), and any of them may be used. Next, the photosensitive glass slope PG prepared in this way was exposed to an N ₂ laser (not shown) at 620 nm.
The coupled wave of the 310 nm dye laser beam excited by the laser beam was taken out, and interference fringes with a pitch of 100 μm and a width of 50 μm were burned out. Note that this interference fringe was uniform within a plane of 90 mm x 90 mm. Furthermore, the power of the above laser light source is 10W, and since the photosensitive glass has absorption of Ce ⁺⁺ at a wavelength of 310μm, selective exposure is performed with laser light of a wavelength corresponding to this absorption. Ta. After burning the interference fringes, the glass plate PG was heated at about 600° C. for 1 hour to crystallize it. In order to make the surface of this glass plate PG even smoother, after polishing it to a thickness of about 0.1 mm,
The surface opposite to this polished surface was coated with a resin, and the glass plate PG was immersed in an approximately 5% HF aqueous solution and etched while applying ultrasonic waves. Incidentally, in this etching, the etching rate of the crystallized part of the glass plate PG is sufficiently faster than that of the amorphous part, and in fact, there is a difference in etching rate of about 20:1. Ta.

Through the above processing, as shown in Figure 1a,
The glass plate PG has a long groove LV with a cross section of 50 μm x 50 μm.
A predetermined number of are formed. Note that this groove LV is not limited to the embodiments described above, but can be freely formed with a cross-sectional area of approximately 10 μm x 10 μm to 150 μm x 150 μm and a pitch of 30 μm to 200 μm by adjusting the exposure optical system etc. It is possible to do so.

Next, an epoxy resin as a bonding agent is applied to the grooved surface of the glass plate PG in which the long grooves LV have been carved in this manner by a dipping method. At this time, if the glass plate PG is pulled up in a direction parallel to the axis of the groove LV, a substantially uniform epoxy resin coating can be obtained along the wall surface of the formed groove LV. After that, this coating film was heated at 100℃ for about 5 minutes.
After preliminary drying and semi-curing, the glass plate PG was cut into a predetermined size to obtain Part A. Note that the bonding agent is not limited to the above-mentioned epoxy resin. The bonding agent used here is a material that produces a bonding effect when heated, such as epoxy resin adhesive, phenol resin adhesive, urethane resin adhesive, silicone resin adhesive, triazine resin, BT resin, etc. For example, organic compound adhesives, molten silver salts described in Japanese Patent Publication No. 38-20227,
These are inorganic compounds such as low-melting glasses. Among these, the latter inorganic compounds are often used in the form of powder rather than liquid. Separately, a component B as shown in FIG. 1b is also prepared. This part B is shown in FIG. 2 along the X-Y line in FIG.
As shown in the cross-sectional view along the line, a heat storage layer (SiO ₂ sputtered film 2 to 3 μm thick) is formed on one side of a substrate (thickness, approximately 0.6 mm) made of metal such as alumina, single crystal silicon, aluminum, iron, etc. ) 2. Heat generating low antibody layer (HfB ₂ sputtered film 500-1000 Å) 3. Electrode layer (aluminum evaporated layer 700-800 Å) 4. Protective layer (SiO ₂ sputtered film 1 μm) 5. Filler layer (parylene,
Spatter film of silicone, Ta ₂ O ₃ , etc.) 6 in sequence.
It is obtained by laminating and then cutting into a predetermined size.

At this time, the electrode layer 4 is etched into a predetermined pattern, and as schematically shown in a perspective view in FIG.
separated into At the same time, the heating resistor layer 3
is exposed in a predetermined pattern HT after a predetermined time. It is desirable that the width 1 of this heating resistor pattern HT is approximately the same as the width of the groove LV.

Moreover, the protective layer 5 and the sealing layer 6 shown in FIG.
In some cases, they are not laminated. After that, board 1
is cut into a predetermined size as part B.
Note that when configuring a recording head of a type in which signals are input from outside the groove LV, part B may be a mere flat plate. As shown in Fig. 3, the parts A and B created in this way are aligned so that the grooves LV and the heating resistor patterns HT are in corresponding positions, and then layered on each other. Ru. Next, these are heated at 100° C. for 10 minutes to further semi-cure the bonding agent layer (not shown), and once here, the presence or absence of positional deviation or clogging of the groove LV is checked. If this check is negative (NO), parts A and B are separated, and part B is cleaned and reused. In addition, part A
will be discarded. And if there are no defects (YES)
The bonding agent layer is completely cured by heating at 100°C for 50 minutes and at 180°C for 2 hours. Then the groove
Check again whether the LV is clogged, and if there is no defect (YES), move the assembled action block C to the next process.

In the next step, a relay chamber block D related to ink supply as shown in FIG. 4 is assembled.

First, a bonding agent having the composition shown below is applied to each of the side plate parts E and E', and after alignment with the action chamber block C as shown by the arrow in Fig. 4, the parts are heated at approximately 60°C for 1 minute. The adhesive is heated to semi-cure, and then it is checked to see if there is any misalignment or if the adhesive has flowed into other parts.

Bonding agent Epicoat #828 (manufactured by Ciel Chemical) Epomate B-002 (manufactured by Ajinomoto) 100 parts by weight 40 parts by weight If this check is NO, separate parts E and E' from block C, and then Clean and reuse. If there are no defects (YES), approx.
The bonding agent is cured by heating at 60°C for 30 minutes.

Next, after applying a bonding agent to the rear end part F and aligning it, the bonding agent is semi-hardened by heating at approximately 60°C for 1 minute, and the same confirmation as in the previous step is carried out.
If no (NO), clean as in the previous step, and if there are no defects (YES), heat at 60°C for 30 minutes to harden the bonding agent.

Next, after applying a bonding agent to the top plate part G and aligning it, the bonding agent is semi-cured by heating at approximately 60°C for 1 minute, and the same confirmation as in the previous step is carried out. If NO, clean as in the previous step.
If there are no defects (YES), heat at approximately 60℃ for 30 minutes.
Further, the bonding agent is completely cured by heating at 100℃ for 10 minutes.

Next, the tubular parts H and H' are inserted into the predetermined positions of the block assembled up to the above steps, and the space between them is filled with a bonding agent. In this case, it is necessary to cure the bonding agent slowly, so leave it at room temperature for 30 minutes. Next, it is confirmed whether or not the bonding agent has flowed into the parts H and H' or whether the ink has flowed into the relay chamber. If this check is negative (NO), wash and reuse as in the previous step. If there are no defects (YES)
For complete curing, heat at approximately 60°C for 30 minutes and then at 100°C for 10 minutes.

In this way, the connection of the relay chamber block D to the rear of the action section block C is completed. Thereafter, the end face OF of the action block C where the discharge orifice OR is installed is polished using abrasive sand (#1000 or higher) to form a smooth surface. Next, cleaning is performed to remove polishing sand and unnecessary materials that have entered the narrow groove LV from the orifice OR during polishing. Here, check whether the orifice installation end face OF is completely flat or not, and also check whether the narrow groove LV
Check whether the inside has been completely cleaned, and if polishing is incomplete, polish again and then clean. Confirmation is made in the same manner, and if no (NO), this process is repeated, and if there are no defects (YES), the combined assembly of blocks C and D is dried.

Furthermore, the completed head product is bonded to an aluminum plate,
Also, the lead electrodes are connected to the flexible wiring board.

Next, a specific example of inkjet recording performed using the recording head obtained above will be described with reference to the example shown in the fourth figure. In addition, in FIG. 4, each component block is illustrated in a separated state for convenience of explanation. However, in reality, as mentioned above, it goes without saying that each component and the blocks are integrated by joining.

That is, in this illustrated example, first, parts H,
Recording ink is introduced into each action chamber 4 through H'. Next, when an electric pulse signal is input to a heat generating antibody (not shown), a thermal pulse is generated there, and as a result, the state of the ink instantaneously changes. Due to this state change, a pressure wave (action force) is applied to the ink, and as a result, the ink flows through the discharge orifice OR provided in communication with the action chamber LV.
Recording is performed by ejecting and flying smaller droplets and depositing them on a recording member (not shown).

In fact, when we conducted ink ejection experiments using the recording head completed as described above using ink with the following composition under the experimental conditions below, stable ink droplets were ejected more than ¹⁰⁹ times. The dots were almost uniform. Signal pulse conditions Applied pulse width: 10 μsec Pulse frequency: 10 KHz Applied energy: 0.01 mJ/1 pulse (per heating element) Ink composition Water 70 parts by weight Diethylene glycol 29 〃 Black dye 1 〃 [Example] Next, implementation of the present invention Let me explain with an example. In this embodiment as well, a description will be given according to the assembly process of a multi-array recording head. In the ink jet head of this embodiment, the ink flow path including the action part is
It is constructed using an unprecedentedly simple method of mechanically press-fixing another flat plate to a substrate in which fine grooves have been carved.

In FIG. 5, two components I, J for forming the working chamber part of the recording head are depicted in a schematic perspective view. FIG. 5a depicts part I, and FIG. 5b depicts part J. Component I is created according to the following procedure.

First, a total of five silicon wafers were prepared, polished to a surface roughness of 0.5 μm or less, and each
A predetermined number of grooves LV were cut using a cutter for semiconductor chip scrubbers. At this time, grooves of different sizes were cut into each silicon wafer.

Specifically, a groove with a cross section of 10 μm is cut at a pitch of 20 μm, a groove of 20 μm square is cut with a pitch of 40 μm, a groove of 30 μm square is cut with a pitch of 60 μm, a groove of 40 μm square is cut with a pitch of 80 μm, a groove of 60 μm square is cut with a pitch of 120 μm. A plate consisting of a total of five silicon wafers, each cut by
SP was created. Then, each plate SP was cut into a predetermined size to obtain a part I [Fig. 5a].

Separately, component parts
Create. In addition, here, a total of five parts J are provided with heat generating low antibody patterns HT corresponding to the shapes and sizes of the grooves LV of the above-mentioned five types of plates SP.
(The roughness of this surface is approximately 1.0 μm or less.) was created.

Corresponding parts I and J obtained in this way are aligned so that each groove LV and the heating resistor pattern (thermal energy generating part) HT are in corresponding positions, as shown in FIG. After maturing, they are layered together. Thereafter, as shown in the figure, parts I and J are layered together as an arbitrary flat plate (fixing member) PP ₁ ,
By pinching and tightening from both sides with PP ₂ ,
Both parts are crimped and fixed. At this time, both parts are extremely thin and easily damaged, so apply tightening pressure as appropriate.
Care must be taken to make adjustments. In this way, 50Pel/mm, 25Pel/mm, 16.7pel/mm,
A total of five acting blocks K having grooves LV serving as ink flow paths were constructed with densities of 12.5 Pel/mm and 8.3 Pel/mm.

Thereafter, after assembling a recording head in a manner similar to that described in connection with the example shown in the fourth figure, an ink droplet ejection experiment was conducted using the recording head, and stable ink droplet ejection was continuously performed. .

In the inkjet head of the present invention, the information signal input means is not limited to the electric/thermal converter represented by the heat generating resistor as shown in the above illustration, but can be used to input thermal energy to the ink. You can use other means instead. As an example, a radiation irradiation means (not shown) can be employed in place of the electric/thermal converter. Among them,
In particular, it is preferable to employ a (semiconductor) laser irradiation means because of its advantages such as high heat conversion efficiency, easy transmission, supply, and control, and the ability to miniaturize the device.

In this type of system in which signals are applied to the ink by laser irradiation, this can be done from outside the ink flow path, which has the advantage that the internal structure of the head can be extremely simplified.

〔Effect of the invention〕

According to the present invention detailed above, as follows:
Great effects can be obtained.

That is, the inkjet head of the first invention of the present application includes a grooved substrate provided with a plurality of grooves and a heat generating substrate provided with a plurality of thermal energy generating means, such that the grooves and the thermal energy generating means correspond to each other. It is constructed by joining and fixing using a fixing member.

Such an inkjet head of the present invention can be manufactured by a simpler method than ever before, in which the grooved substrate and the heat generating substrate are joined and fixed using a fixing member.

In addition, since it is only necessary to press the grooved substrate and the heat generating substrate to each other by sandwiching and tightening the grooved substrate with the fixing member, there is no need to use adhesive, so there is no possibility that the adhesive will protrude into the ink path. Therefore, the size and accuracy of the ink path can be further improved. Therefore, the size, ejection speed, and ejection direction of the ink droplets ejected from the ejection ports are uniform, and the overall reliability related to ink ejection can be further improved.

In particular, since the ink jet head of the present invention uses thermal energy generating means as the energy generating means used to eject ink from the ejection ports, the above-mentioned effects are even more pronounced. This is because, for example, when a piezo element is used as the energy generating means used to eject ink, the vibration of the piezo element itself for ejecting ink acts to loosen the fixation by the fixing member. This is because there are things.

As described above, the present invention provides an ink jet recording head that has excellent ink ejection characteristics, that is, ink droplet generation efficiency, energy consumption rate, stability of ink droplet generation, uniformity of generated ink droplets, and responsiveness to input signals. Not only that, but precision processing can be easily performed, and an inkjet recording head with a high density multi-orifice structure can be obtained by a simple procedure.

Further, the inkjet recording head of the present invention is capable of forming extremely stable ink droplets during high-speed and continuous ejection.

A second invention of the present application is an invention of an inkjet device which, in addition to the configuration of the inkjet head of the first invention, includes means for supplying a signal corresponding to the generation of thermal energy to the thermal energy generating means.

[Brief explanation of drawings]

Figure 1a, Figure 1b, Figure 2, Figure 3, and Figure 4.
The figure is an explanatory diagram of a reference example along the ink jet head assembly process, and FIGS. 5a, 5b, and 6 are explanatory diagrams of an embodiment of the present invention. In these figures, 1 is the substrate, 3 is the heat generating low antibody layer, 4 is the electrode layer, PG is the photosensitive glass plate, HT is the heat generating resistor pattern, CE and PE are the lead electrodes,
LV is groove, OR is discharge orifice, SP is silicon wafer plate, PP ₁ , PP ₂ are flat plates, A, B, E,
E', F, G, H, H', I, J are component parts, C,
D and K are building blocks.

Claims (1)

[Scope of Claims] 1. A grooved substrate provided with a plurality of grooves for forming a path communicating with an ejection port for ejecting ink; a heat-generating substrate provided with a plurality of thermal energy generating means for generating thermal energy used for ejecting ink from the ejection ports; and a plurality of grooves and thermal energy generating portions of the plurality of thermal energy generating means, respectively. Correspondingly,
An inkjet head comprising: a fixing member for joining and fixing the grooved substrate and the heat generating substrate with the plurality of grooves facing inside. 2. The ink jet head according to claim 1, wherein the fixing member is a plurality of flat plates that press the grooved substrate and the heat generating substrate together by sandwiching and tightening the substrates. 3. The inkjet head according to claim 1, wherein the thermal energy generating means is an electrothermal converter. 4. A grooved substrate provided with a plurality of grooves for forming a path communicating with an ejection port for ejecting ink, and causing a state change in the ink in the path and ejecting ink from the ejection port based on the state change. a heat generating substrate provided with a plurality of thermal energy generating means for generating thermal energy used for an inkjet head having a fixing member for joining and fixing the grooved substrate and the heat generating substrate with a plurality of grooves inside; An inkjet device comprising: means for supplying ink to an inkjet inkjet device;