JP3330757B2 - Ink jet head and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet head and a method of manufacturing the same, and more particularly, to an on-demand type ink jet head and a method of manufacturing the same.

[0002]

2. Description of the Related Art The ink jet recording system has attracted attention because it can record without contacting a head on recording paper, and has a very simple recording process and is suitable for color recording. Conventionally, various methods have been proposed as the ink jet recording method, but at present, the so-called drop-on-demand (DOD) method in which ink is ejected only when a recording signal is input has become mainstream. Among the DOD methods, there are a so-called thermal method (Japanese Patent Publication No. 61-59913 and the like) utilizing bubbles generated in ink by thermal energy and a piezo actuator method using a piezoelectric element (Japanese Patent Publication No.
No. 0-8953).

As the latter piezo actuator system,
For example, as described in JP-A-3-10846, a wall constituting the pressurized liquid chamber has a deformable structure, a piezoelectric element is provided outside the deformable wall, and the piezoelectric element is used. There is a method in which the wall surface of the pressurized liquid chamber is deformed to change its internal volume, thereby applying pressure to the ink to form droplets and fly from the nozzles. In the piezo actuator method, a pulse-like pressure increase in the nozzle region or the pressurized liquid chamber on the front surface of the piezoelectric element is required,
The voltage waveform applied to the piezoelectric element is several μsec to several tens μsec.
And the ink is supplied by returning the displacement of the piezoelectric element to the original.

[0004]

In a conventional piezo-actuator type ink jet head in which the above-mentioned conventional pressurized liquid chamber is provided and a deformable wall surface of the pressurized liquid chamber is deformed by a piezoelectric element, the piezoelectric element is Without direct contact with the ink,
Furthermore, since the heat generated by the piezoelectric element can be neglected, there is an advantage that there is no restriction on the type of ink used. On the other hand, on the other hand, when multi-channeling (here, “channel” means a portion composed of one piezoelectric element, a pressurized liquid chamber, and a nozzle), the piezoelectric element and the pressurized liquid are used. It is difficult to miniaturize the chamber and the like, to reduce the driving voltage, and to obtain an inkjet head with high integration array density, high efficiency, high reliability, and easy assembly.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has a high integration arrangement density, a compact size, a low profile, a small number of parts, easy assembling, high efficiency and high reliability. It is an object of the present invention to provide a manufacturing method thereof.

[0006]

According to a first aspect of the present invention, there is provided a method of manufacturing an ink-jet head, wherein each of the pressurized liquid chambers is pressurized by a plurality of piezoelectric elements arranged in a row. In a method of manufacturing an ink jet head for ejecting ink droplets from each nozzle communicating with a pressurized liquid chamber, the ink jet head is formed on an insulating substrate by slit processing for individual electrodes.
After forming a common groove deeper than the groove to be formed, forming an electrode pattern on the insulating substrate and joining the laminated piezoelectric element, slit processing is integrally performed on the laminated piezoelectric element and the surface of the substrate. The multi-layer piezoelectric element and the electrode pattern are divided into a plurality of multi-layer piezoelectric elements and individual electrodes corresponding to the respective multi-layer piezoelectric elements, and a direction in which the plurality of multi-layer piezoelectric elements are arranged on the substrate. On an actuator unit in which a frame member having substantially the same height as the multilayer piezoelectric element is joined to at least one side in a direction orthogonal to the above, a deformed portion that is deformed by displacement of each multilayer piezoelectric element of the actuator unit is formed. A vibrating plate, a pressurized liquid chamber corresponding to a deformed portion of the vibrating plate, and a liquid chamber flow path forming member that forms a common ink flow path communicating with the pressurized liquid chamber; and before communicating with the pressurized liquid chamber. Obtaining an inkjet head liquid chamber unit formed by laminating joining the nozzle plate forming the nozzle by adhesive bonding.

The ink jet head according to claim 2, wherein each of the pressurized liquid chambers is pressurized by a plurality of piezoelectric elements arranged in a row, thereby ejecting ink droplets from each nozzle communicating with each of the pressurized liquid chambers. In this ink-jet head, a liquid chamber unit is laminated and joined on an actuator unit, and the actuator unit includes an electrode pattern and a laminated piezoelectric element provided on an insulating substrate, and the laminated piezoelectric element and the substrate. The surface part is integrally slit and divided into a plurality of laminated piezoelectric elements and individual electrodes corresponding to each laminated piezoelectric element, and is formed on an insulating substrate by slit processing for individual electrodes.
A frame member having a common groove deeper than the groove to be formed, and having a height substantially equal to that of the multilayer piezoelectric element on at least one side in a direction orthogonal to a direction in which the plurality of multilayer piezoelectric elements are arranged on the substrate. The liquid chamber unit includes a diaphragm having a deformed portion deformed by displacement of each of the stacked piezoelectric elements of the actuator unit, a pressurized liquid chamber corresponding to the deformed portion of the vibrating plate, and a pressurized liquid chamber. A liquid chamber flow path forming member that forms a common ink flow path that communicates with the pressurized liquid chamber, and a nozzle plate that has the nozzle that communicates with the pressurized liquid chamber are laminated and joined.

[0021]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an external perspective view of an inkjet head showing one embodiment of the present invention, FIG. 2 is an exploded perspective view of FIG.
1 is a sectional view taken along the line AA of FIG. 1, and FIG. 4 is a sectional view taken along the line BB of FIG.

This ink jet head comprises an actuator unit 1 and a liquid chamber unit 2 joined on the actuator unit 1. The actuator unit 1 includes two rows of piezoelectric element rows 4 and 4 in which a plurality of stacked piezoelectric elements are arranged (arranged) in a row on a substrate 3 and the periphery of the two rows of piezoelectric element rows 4 and 4. The surrounding frame member 5 is joined by an adhesive 6. Piezoelectric element row 4
Is composed of a plurality of piezoelectric elements to which a driving pulse is applied to make ink droplets fly.
That. ), A plurality of piezoelectric elements which are located between the drive unit piezoelectric elements 7 and 7 and serve merely as a liquid chamber unit fixing member without being supplied with a drive pulse (this is referred to as a “fixed unit piezoelectric element”). 8, 8... Are arranged alternately.

The liquid chamber unit 2 is composed of a liquid film made of a photosensitive resin film (dry film resist) for forming a pressurized liquid chamber, a common ink flow path, etc., on a diaphragm 12 having a diaphragm portion 11 as a deformable portion. The chamber flow path forming member 13 is bonded, and a nozzle plate 16 having a plurality of nozzles 15 formed thereon is bonded to the liquid chamber flow path forming member 13. The vibration plate 12, the liquid chamber flow path forming member 13, and the nozzle Plate 1
6, the driving piezoelectric elements 7, 7.
A plurality of substantially independent pressurized liquid chambers 17 each having a diaphragm portion 11 opposed to the nozzles 15 and 1 are formed.
5 are arranged so as to face the respective drive unit piezoelectric elements 7 of the piezoelectric element row 4. The diaphragm 12 of the liquid chamber unit 2 is joined to the actuator unit 1 with high rigidity by an adhesive 18.

The substrate 3 of the actuator unit 1 has a thickness of about 0.5 to 5 mm and is made of a material similar to a piezoelectric element, and can be cut together with the piezoelectric element by, for example, a diamond grindstone. Is preferred.

At both ends of the substrate 3 in the direction orthogonal to the direction in which the piezoelectric elements are arranged, the end faces of the piezoelectric element rows 4 and 4 where the driving piezoelectric elements 7 and the fixed piezoelectric elements 8 are not opposed to each other. Are formed as electrode patterns divided by the slit grooves 21 to be connected, and a direction perpendicular to the slit grooves 21 between the piezoelectric element rows 4 and 4 (the direction in which the piezoelectric elements are arranged) ), A common groove 23 deeper than the slit groove 21 is formed. In the common groove 23, the opposing end faces of the individual driving piezoelectric elements 7 and the fixed piezoelectric elements 8 of the piezoelectric element rows 4 and 4 are formed. A common electrode 24 to be connected is formed. An ink supply pipe 25 is connected to an ink supply hole 3a formed at an end of the substrate 3.

The driving piezoelectric element 7 constituting the piezoelectric element array 4
As the fixed portion piezoelectric element 8, a laminated piezoelectric element having ten or more layers is used. As shown in FIG. 3, for example, this laminated piezoelectric element has a PZT thickness of 20 to 50 μm / 1 layer.
(= Pb (Zr.Ti) O3) 26 and internal electrodes 27 made of silver / palladium (AgPd) having a thickness of several μm / 1 layer are alternately laminated. A drive voltage can be reduced by using a laminated type having a thickness of 20 to 50 μm / 1 layer, and for example, an electric field strength of 1000 V / mm of the piezoelectric element can be obtained with a pulse voltage of 20 to 50 V. The material used for the piezoelectric element is not limited to the above, and BaTiO3, PbTiO3 generally used as the piezoelectric element material is used.
3, a ferroelectric material such as (NaK) NbO3 may be used.

End electrodes (external electrodes) 2 made of AgPd in which a large number of internal electrodes 27, 27 are alternately connected every other layer are provided on both end surfaces of the driving piezoelectric element 7 of each piezoelectric element row 4.
8 and 29, and the end face electrodes 28, 28,.
Are connected to the upper common electrode 24 via a conductive material 31, and the end face electrodes 29, 29.
, 22 are connected via a conductive material 32. An FPC cable 33 is connected to each of the individual electrodes 22, 22,... And the common electrode 24. When a driving voltage is applied, an electric field is generated in the stacking direction. Is caused. In the manufacturing process, the fixed-part piezoelectric element 8 is also provided with electrodes in the same manner as the driving-part piezoelectric element 7, but has a configuration in which no driving pulse is applied (a configuration in which only the driving-part piezoelectric element 7 is selectively driven). Has become.

As shown in FIG. 2, the frame member 5 has through holes 5a, 5b corresponding to the piezoelectric element rows 4, 4 in a plate-like member.
Are formed on one side in a direction orthogonal to the direction in which the driving piezoelectric elements 7, 7,... Of the piezoelectric element rows 4, 4 are arranged, and the two piezoelectric element rows are formed. A fixed portion 37 is also formed at the central portion, which is the other side of 4, 4,
The fixing portions 35 to 37 are provided with bridging portions 38 at both ends of the driving portion piezoelectric elements 7, 7.
38 is a frame-shaped member. The frame member 5
An ink supply hole 5c corresponding to the ink supply hole 3a of the substrate 3 is formed in one of the bridge portions 38.

The material of the frame member 5 is preferably one that has excellent dimensional stability and does not affect the image quality even when the operating environment of the head is shaken within a range of several tens of degrees. Metals and the like can be used, but ceramics similar to those used for the piezoelectric element 7 and the substrate 3 for the driving section are particularly preferable. When a resin is used for the frame member 5, a resin mixed with a filler that reduces the coefficient of thermal expansion, for example, polyphenylene sulfide,
It is preferable to use a resin obtained by mixing a filler such as titanium, alumina, glass filler, carbon, silica, etc. into an engineer plastic resin such as polyethersulfone or polyimide. In this way, by using a resin mixed with a filler that reduces the coefficient of thermal expansion, the coefficient of thermal expansion is equivalent to that of the driving portion piezoelectric element 7 of the piezoelectric element row 4 and the fixed portion piezoelectric element 8 serving as a liquid chamber fixing member. And the cost of parts can be reduced.

Further, the shape of the frame member 5 is not limited to the above-described one, and the central fixed portion 3 between the two rows of piezoelectric elements 4 and 4 is not limited to the above.
Alternatively, it is also possible to use a single plate in which a central frame 37 is removed by removing the fixing portions 36, 36 on both sides. Further, a columnar member (the shape is not limited to this) may be attached to the four corners of the substrate 3.

Next, as shown in FIG. 3, the diaphragm 12 of the liquid chamber unit 2 has a flat surface on the lower liquid chamber flow path forming member 13 side and a diaphragm region 12a having a different thickness on the piezoelectric element row 4 side. , A joining area 12b and a relief area 12c, and a diaphragm section 11 corresponding to the driving piezoelectric elements 7, 7,... Of the piezoelectric element row 4. The diaphragm 12 is made of a Ni (nickel) metal plate.
It is manufactured by an electroforming method.

Here, the diaphragm region 12a is the thinnest region, and the diaphragm region of the diaphragm portion 11 having a thickness of about 3 to 10 μm (an elastic portion which is deformed in accordance with the displacement of the driving portion piezoelectric element 7). ). By setting the thickness of the diaphragm region 12a to 10 μm or less, the displacement of the drive unit piezoelectric element 7 can be efficiently transmitted to the pressurized liquid chamber 17. The joining region 12b is a region having the largest thickness, and is a joining region between the driving portion piezoelectric element 7 and the fixed portion piezoelectric element 8 of the piezoelectric element row 4 and the frame 5 as the second liquid chamber fixing member. For example, it is formed to a thickness of about 20 μm or more. Furthermore, the escape area 12c is
This is an area having an intermediate thickness, and is an escape area for avoiding contact with the drive unit piezoelectric element 7. Note that the diaphragm 12 also has an ink supply hole 12d.

The liquid chamber flow path forming member 13 is located between the upper surface of the vibration plate 12 and the nozzle plate 16 to form a flow path of the pressurized liquid chamber 17 and the like. It comprises a chamber flow path forming member 40 and an upper liquid chamber flow path forming member 41.

The lower liquid chamber flow path forming member 40 is
.. Made of a photosensitive resin film adhered to the upper surface, together with the upper liquid chamber flow path forming member 41, as shown in FIG. A number of inner partition walls 43 which form independent flow paths of the pressurized liquid chamber 17 and also form a fluid resistance portion 42 which also serves as an ink supply path to each pressurized liquid chamber 17; 17 and an outer peripheral partition wall 45 forming a common ink flow path 44. The inner partition 43 has two piezoelectric element rows 4 and 4.
Two rows are formed corresponding to the rows being formed, and the common ink flow path 44 is provided between the rows. Here, the common ink flow path 44 is formed so as to be arranged at a position corresponding to the upper surface of each of the fixing portions 35 to 37 of the frame member 5.
The upper liquid chamber flow path forming member 41 is connected to the lower liquid chamber flow path forming member 4.
0, but the lower liquid chamber flow path forming member 40
In that there is no portion corresponding to the fluid resistance portion 42 of FIG.

The nozzle plate 16 is provided with a number of nozzles 15 which are fine holes for causing ink droplets to fly. The diameter of the nozzles 15 is 3 at the ink droplet outlet side.
The nozzle 15 is provided at a position corresponding to the vicinity of the center of the pressurized liquid chamber 17. The nozzle plate 16 is also made of a Ni (nickel) metal plate like the diaphragm 12, and is manufactured by an electroforming method.

Next, the manufacturing process of the ink jet head will be described. This ink jet head is manufactured by separately assembling the actuator unit 1 and the liquid chamber unit 2 in advance, and then bonding and bonding the units 1 and 2 to each other. By adopting such a manufacturing process,
A non-defective product of the two units 1 and 2 can be selected and assembled, thereby improving the yield, and also having an actuator unit 1 in which dust is likely to be generated in the processing and assembling process, and a liquid chamber unit 2 in which dust should be completely prevented from adhering. Can be assembled in separate steps, so that the quality itself of the completed inkjet head is improved. Hereinafter, a specific description will be given.

First, the processing and assembling steps of the actuator unit 1 are as follows. That is, FIG.
As shown in FIGS. 5 and 6, ink supply holes 3a are formed in advance on a substrate 3 formed of an electrically insulating material such as ceramics or high-rigidity resin, and a central portion is formed along the direction in which the stacked piezoelectric elements are arranged. The common groove 23 is formed. This common groove 2
3 is formed deeper than a slit groove 21 which is a cut groove at the time of slitting a piezoelectric element plate or the like described later. In addition, positioning holes 3b and 3c are provided near both ends of the common groove 23.
Is formed.

Then, individual electrode patterns 51 and 52 made of a conductive material for forming the individual electrodes 22 are formed on both sides of the substrate 3, as well as in and near the common groove 23 and the individual electrode patterns 51. , 52 are formed to form a common electrode pattern 53 made of a conductive material so as to face both ends of the substrate 3, bypassing the individual electrode patterns 51.
And the common electrode pattern 53 and between the individual electrode pattern 52 and the common electrode pattern 53 are piezoelectric element bonding regions 54 and 55. Each of these electrode patterns 5
1 to 53 are, for example, metal deposition of Ni, Au, Cu, or the like, or electrolysis of the same metal, electroless plating, or AgPd, Ag
It is formed by a method such as printing of a thick film conductor paste such as a Pt or Au paste and adhered to the surface of the substrate 3.

The common electrode can be separately formed of a conductive paste or the like after cutting a piezoelectric element plate and individual electrode patterns 51 and 52, which will be described later. The groove 23 and the common electrode pattern 53 become unnecessary, and the minimum required electrode patterns are the individual electrode patterns 51 and 52.

Then, as shown in FIG. 7, a laminated piezoelectric element is used in the piezoelectric element bonding regions 54 and 55 on the substrate 3 in a plate shape (not limited to a plate shape, but is used in a sense including a square pillar shape and the like). The piezoelectric element plates 56, 56 formed as described above are bonded by using an adhesive 6 (see FIG. 3). At this time, the positional relationship between the piezoelectric element plates 56, 56 and the individual electrode patterns 51, 52 and the common electrode pattern 53 is such that the piezoelectric element plates 56, 56 correspond to the individual electrode patterns 51, 52 and the common electrode pattern 53. The joints should be slightly stuck or, preferably, slightly spaced. In this case, when the piezoelectric element plates 56, 56 are joined so as to be mounted on the individual electrode patterns 51, 52 and the common electrode pattern 53 in a large amount (with a large area), the thickness and error of the electrode patterns 51 to 53 are reduced. This undesirably affects the joining quality of the plate 56 and thus the piezoelectric elements 7 and 8 after cutting, that is, the uniformity of joining and the plane parallel accuracy after joining.

The direction in which the piezoelectric element plates 56 are stacked is the same as the direction in which the piezoelectric element plates 56 are joined to the substrate 3 as described above (see FIGS. 2 to 4). As the adhesive 6 used for bonding the piezoelectric element plate 56 to the substrate 3, a heat-curable epoxy-based adhesive is used, and among them, those having a high Young's modulus are suitable. As the form of the adhesive, any of a one-liquid type, a two-liquid mixed type, a film type and the like can be used.

Then, these piezoelectric element plates 56,
56, the end face electrode (external electrode) 2
End electrodes 57 and 58 for forming the electrodes 8 and 29 are formed, and after bonding and bonding to the substrate 3, the end electrodes 57 and 58 on the opposite sides of the two piezoelectric element plates 56 and 56 are formed.
57 are electrically connected to the common electrode pattern 53 on the substrate 3 by the conductive material 31, and the non-opposing end electrodes 58, 58 of the two piezoelectric element plates 56, 56 are connected to the individual electrodes on the substrate 3. Conductive pattern 3
2 for electrical connection. The conductive materials 31 and 32 are applied and cured using, for example, a conductive adhesive.

Next, two piezoelectric element plates 56, 56 are set by a dicer or the like on which a diamond grindstone is set.
Then, the surface portion of the substrate 3 is cut (slitted) at a predetermined pitch in a direction (short side direction) orthogonal to the end surface electrodes 57 and 58 to become the driving portion piezoelectric element 7 and the fixed portion piezoelectric element 8. At the same time as forming a plurality of laminated piezoelectric elements by division, the end face electrodes 57 and 58 are divided into end face electrodes 28 and 29 corresponding to the plurality of laminated piezoelectric elements (the driving piezoelectric element 7 and the fixed piezoelectric element 8). At this time, the driving piezoelectric element 7 and the fixed piezoelectric element 8 are completely separated from each other by cutting the substrate 3 to a predetermined depth and cutting the slit grooves 21 to cut the individual electrode patterns on the substrate 3. 5
7 and 58 are individual electrodes 22, 22 corresponding to a plurality of laminated piezoelectric elements (driving section piezoelectric element 7 and fixed section piezoelectric element 8).
Divided into The divided individual electrodes 22, 22,... Are end face electrodes 29 on the end face side of the divided multi-layer piezoelectric elements (the driving piezoelectric element 7 and the fixed piezoelectric element 8) which are not opposed to each other.
29 ... remain connected. The slit pitch, that is, the cutting pitch (the pitch in the longitudinal direction of the piezoelectric element plate 56) is, for example, the pitch at which the piezoelectric elements 7 and 8 having a width of about 100 μm per pitch are formed.

The common electrode pattern 53 on the substrate 3
Are partially divided corresponding to the individual driving piezoelectric elements 7 (and the fixed piezoelectric elements 8), but the common grooves 23 of the substrate 3
Since the slit groove 21 does not reach the position, the pattern 53 for the common electrode is formed through the common groove 23 and all the end face electrodes on the opposite end face side of the driving piezoelectric elements 7 of the two piezoelectric element rows 4 and 4 after the slit processing. , 28, 28... Thereby, the common electrode 24 connected to the opposed end face electrodes 28 of the two piezoelectric element rows 4 and 4 can be easily obtained.
Can be secured.

As described above, here, the individual electrode patterns 51 and 52 are formed on the substrate 3 in advance, and the common groove 23 having a depth which is not divided at the time of slitting is previously formed between the piezoelectric element plates to be joined. Then, a common electrode pattern 53 is formed so as to be included in the common groove 23, and two piezoelectric element plates 56, 56 having end face electrodes 57, 58 formed on both end surfaces on the substrate 3, respectively, are independently arranged in parallel. Then, these two piezoelectric element plates 56, 56
And the individual electrode patterns 51, 52 on the substrate 3 are simultaneously cut at a predetermined pitch to form two piezoelectric element plates 56, 56 into a plurality of laminated piezoelectric elements constituting the respective piezoelectric element rows 4, 4. At the same time, the individual electrode patterns 51, 52 on the substrate 3 are divided into individual electrodes 22, 22,... Corresponding to the individualized laminated piezoelectric elements. Try not to be split.

In this manner, it is particularly easy to take out the electrodes from each piezoelectric element (driving unit piezoelectric element 7), which is a laminated piezoelectric element, and the opposite end electrodes of the two rows of piezoelectric elements are connected to each other. By connecting to a common electrode,
It is easy to take out individual electrodes for connection to the drive circuit, and by providing a common electrode pattern that is not divided by cutting, it is possible to secure a common electrode before performing fine mechanical cutting, The individual piezoelectric elements formed by the cutting process are not destroyed or damaged in a later process, and the process can be simplified and the yield can be further improved. Further, the number of cutting steps is reduced as compared with a method in which one piezoelectric element plate is used to divide the piezoelectric element plate into two, and each row of the piezoelectric element plates is further divided into individual piezoelectric elements.

Thus, the piezoelectric element plate 56,
The frame member 5 is adhesively bonded to the substrate 3 having undergone the cutting process (slit process) such as 56 using an adhesive 6. Here, the upper surfaces of the frame members 5 and the upper surfaces of the piezoelectric element rows 4 and 4 after the frame members 5 are joined need to be accurately and coplanar. This is because, as described later, the diaphragm 12 of the liquid chamber unit 2 is joined to this portion, so that a deformed portion (diaphragm portion 11) that is not adhered to when the surface accuracy is poor occurs.

In this case, in order to make the upper surface of the frame member 5 and the upper surface of each of the piezoelectric elements 7 and 8 of the piezoelectric element rows 4 and 4 coplanar, the bonding step is devised and the surfaces are fixed at the time of bonding and cured. However, the dimensional accuracy of both parts and the difficulty of the bonding method increase. Then, after bonding the frame member 5 slightly higher than the height of the piezoelectric element rows 4 and 4, the surface is ground, and the upper surfaces of the piezoelectric elements 7 and 8 of the piezoelectric element rows 4 and 4 are slightly shaved. By performing the grinding until the surfaces become the same plane, the dimensional accuracy of both parts and the difficulty of the bonding method can be eliminated.

Thereafter, the FPC cable 33 is bonded to the individual electrodes 22 and 22 and the common electrode 24 of the substrate 3 by applying heat and pressure to complete the actuator unit 1. Note that FP
The C cable 33 has a pattern that can selectively drive the driving piezoelectric elements 7, 7,... In the piezoelectric element rows 4, 4, and the joints thereof are plated in advance with solder.

On the other hand, the process of assembling and assembling the liquid chamber unit 2 will be described. The photosensitive resin for forming the lower liquid chamber flow path forming member 40 on the flat surface of the diaphragm 12 has a thickness of 20 mm. A dry film resist having a thickness of about 50 μm is laminated by heat and pressure, and is exposed to ultraviolet light using a mask corresponding to a flow path pattern to cure the exposed portion. Then, using a solvent capable of removing the unexposed portion, the unexposed portion is removed and developed to form a liquid chamber pattern of the lower liquid chamber flow path forming member 40 as shown in FIG. After that, the main curing is performed again by ultraviolet exposure and heat.

A dry film resist having a thickness of about 40 to 100 μm, which is a photosensitive resin for forming the upper liquid chamber flow path forming member 41, is also laminated on the nozzle plate 16 by heat and pressure. Exposure to UV using a mask according to the, the exposed part is cured,
The unexposed portion is developed to form a liquid chamber pattern of the upper liquid chamber flow path forming member 41 (there is no fluid resistance portion 42 as described above).
Is formed, washed with water, dried, and then hardened again by UV exposure and heat.

Then, the corresponding surfaces of the lower liquid chamber flow path forming member 41 and the upper liquid chamber flow path forming member 41 made of the dry film resist formed on the vibration plate 12 and the nozzle plate 16 are joined. I do. This joining is performed using a positioning jig, and pressure and heating at a higher temperature than in the main curing are performed.

The actuator unit 1 and the liquid chamber unit 2 completed as described above are assembled. That is, first, as described above, epoxy-based bonding is performed on the upper surfaces of the piezoelectric elements 7..., 8. The actuator unit 1 is fixed to a bonding jig that can be positioned by applying an adhesive 18 such as an adhesive, and the two chambers 1 are aligned while the liquid chamber unit 2 is positioned with the diaphragm 12 side (bonding surface) downward. ,
2 are joined to obtain an ink jet head. In this case, the epoxy adhesive is left under a pressure of several kg / cm2 while the epoxy adhesive reacts and cures. In the screen printing, it is preferable to use a pattern mask so that the adhesive 18 is not applied to an unnecessary portion. The adhesive may be instantaneously joined by using an acrylic two-pack non-mixing type adhesive or a cyanoacrylate adhesive.
Finally, the ink supply pipe 25 is inserted into the ink supply hole 3a of the substrate 3, and an adhesive is applied and cured to fix it.

Next, the operation of the ink jet head constructed as described above will be described. A drive pulse of 20 to 50 V is selectively applied to the drive piezoelectric elements 7, 7... Of the piezoelectric element rows 4, 4 in accordance with a recording signal. When the voltage is applied, the driving piezoelectric element 7 to which the pulse voltage is applied is displaced, and the corresponding diaphragm 11 of the diaphragm 12 is moved to the nozzle 1.
The ink is deformed in five directions, and the ink in the pressurized liquid chamber 17 is pressurized by a change in the volume (volume) of the pressurized liquid chamber 17, and the ink is ejected as droplets from the nozzles 15 of the nozzle plate 16 to perform recording. be able to.

Then, the ink pressure in the pressurized liquid chamber 17 decreases as the ink droplets are ejected, and a slight negative pressure is generated in the pressurized liquid chamber 17 due to the inertia of the ink flow at this time. In this state, by turning off the application of the voltage to the drive unit piezoelectric element 7, the diaphragm portion 11 of the diaphragm 12 returns to the original position, and the pressurized liquid chamber 17 becomes the original shape. , Further negative pressure is generated.

At this time, the ink that has entered from the ink supply pipe 25 that leads to the ink tank (not shown) is filled into the pressurized liquid chamber 17 from the fluid resistance section 42 through the common ink flow path 44. Then, after the vibration of the ink meniscus surface of the nozzle 15 is attenuated and stabilized, a pulse voltage is applied to the driving unit piezoelectric element 7 for discharging the next ink droplet.

In this case, by forming the deformed portion of the diaphragm 12 as the diaphragm portion 11, the displacement generated by the piezoelectric element 7 in the driving portion can be efficiently transmitted to the pressurized liquid chamber 17, and the displacement can be increased. Vibration propagation to portions other than the pressurized liquid chamber 17 is reduced. Further, at the time of ink ejection, an ink flow is generated in a flow direction from the pressurized liquid chamber 17 to the common ink flow path 44, and this flow path is formed as a fluid resistance portion 42 having a smaller cross-sectional area than the other. Therefore, the backflow from the pressurized liquid chamber 17 to the common ink flow path 44 is extremely reduced, and the drop in the ink droplet ejection efficiency is prevented.

In this ink jet head, each driving piezoelectric element 7 of the piezoelectric element row 4 is joined to the diaphragm 11 of the liquid chamber unit 2 and the substrate 3
On the upper part, the fixed part piezoelectric elements 8, 8 are arranged between the driving part piezoelectric elements 7, 7.
Are provided in a bi-pitch structure, the fixed portion piezoelectric element 8 and the pressurized liquid chambers 17 of the liquid chamber unit 2 are joined to fix the liquid chamber unit 2 to the substrate 3, so that the adjacent channel The mechanical stiffness of the first piezoelectric element 7 is increased, and the propagation of vibration to another piezoelectric element 7 of the driving section when one driving section piezoelectric element 7 is driven is suppressed, the mutual interference is reduced, and the ink ejection performance is stabilized.

On the substrate 3, fixed portions 35 to 37 are provided on the outer periphery of the piezoelectric element rows 4 and 4 in a direction orthogonal to the nozzle arrangement direction.
And a frame member 5 having
And the liquid chamber unit 2 are joined to each other, so that the vibration propagation to the adjacent channel which occurs at the time of single channel driving is also suppressed here, and when the plurality of channels are driven simultaneously, the entire liquid chamber unit 2 is lifted. No more.

Further, a laminated piezoelectric element is used as the driving section piezoelectric element 7, and the laminating direction (d3
(3 directions), the pressure in the pressurized liquid chamber 17 is increased by the drive of the drive unit piezoelectric element 7 because the pressurized liquid chamber 17 is pressurized by the displacement in the three directions). Displacement occurs without a time delay corresponding to the voltage waveform. Since the displacement in the d33 direction is used, the thickness of the driving unit piezoelectric element 7 in the displacement direction can be reduced,
The mechanical resonance point is also in a high frequency band (500 KHz or more) so that there is no practical problem, and the influence of resonance is almost eliminated even when driven with a rise time of several μs.

Further, as shown in FIG. 3, since the common ink flow path 44 of the liquid chamber unit 2 is formed at a position corresponding to the upper surface of the frame member 5, the piezoelectric element 7 is formed.
The liquid chamber unit 2 can be fixed at a position as close as possible to..., 8, so that the vibration characteristics of the diaphragm 11 of the diaphragm 12 are stabilized. In this case, it is preferable to obtain the above-described operation and effect by setting the area of at least half of the common ink flow path 44 of the liquid chamber unit 2 to a positional relationship corresponding to the upper surface of the frame member 5.

Since this ink jet head employs a piezo actuator system using a pressurized liquid chamber, the piezoelectric element as an actuator is not immersed in ink, so that there is no problem of liquid contact, and the piezoelectric element is self-contained. Since there is no heat generation problem, there is no restriction on the ink used, and since the optimal piezoelectric element drive waveform for ink liquid discharge can be set, microdroplets (satellite) are unlikely to occur, image (printing) quality is high, and the actuator unit and liquid Since the chamber units are assembled separately, the yield of the head and the assembly quality are improved.

In the above-described embodiment, as described above, the piezoelectric element plate 56 is joined to the substrate 3 and slit processing is performed at a predetermined pitch, so that a plurality of driving section piezoelectric elements 7 and fixed section piezoelectric elements 8 are formed. Is formed, the frame member 5 is joined to the substrate 3. In this case, when the grinding process is performed to align the upper surfaces of the frame member 5 and the plurality of drive unit piezoelectric elements 7 and the fixed unit piezoelectric elements 8, the processed plurality of drive unit piezoelectric elements 7 and the fixed unit piezoelectric elements are processed. 8
However, there may be a case where a joining failure or the like occurs due to an impact at the time of grinding. Further, when cutting the piezoelectric element plate 56 and the electrode patterns 51 and 52, the electrode pattern is cut (slit) at a small pitch, so that the adhesion strength of the electrode pattern cannot withstand the peeling force during the processing. It may be peeled off from the substrate 3.

Therefore, as shown in FIG. 8, a piezoelectric element plate 56 (see FIG. 7) is bonded to the substrate 3 by bonding.
After the frame member 5 is also bonded and joined, first, the upper surfaces of the piezoelectric element plate 56 and the frame member 5 are ground to adjust the surface height, and then the piezoelectric element plate 56 and the frame member 5 are connected to each other by a dicing saw or the like. It is also possible to perform cutting at the same time so as to integrally form the slit grooves 60. This prevents the drive unit piezoelectric element 7 and the fixed unit piezoelectric element 8 from falling down due to the processing force at the time of grinding processing or groove processing (cutting processing), and the frame member 5 presses the electrode pattern on the substrate 3 from above. Therefore, peeling of the electrode pattern can be prevented.

In the above-described embodiment, the thickness of one layer of the driving portion piezoelectric element 7 and the fixed portion piezoelectric element 8 is 25 as described above.
When cutting the drive unit piezoelectric element 7, the fixed unit piezoelectric element 8, and the frame member 5, the drive unit piezoelectric element 7 and the fixed unit depend on the flatness accuracy and thickness accuracy of both parts. In some cases, the uppermost layer of the piezoelectric element 8 is entirely shaved and the internal electrode 27 is exposed. In addition,
Here, it is needless to say that the driving unit piezoelectric element 7 particularly poses a problem.

Therefore, as shown in FIG. 9, the outermost PZTs 26a and 26b of the driving piezoelectric element 7 (also the piezoelectric element 8), which is a laminated piezoelectric element, are formed to be thicker than the other layers of PZT 26. By doing so, the drive unit piezoelectric element 7
In addition, when the fixed portion piezoelectric element 8 and the frame member 5 are face-to-face, the internal electrodes 27 are exposed even when the amount of grinding of the outermost PZTs 26a and 26b is increased due to insufficient planar accuracy of the parts. Can be prevented. The outermost PZTs 26a and 26b are provided with an internal electrode 27 on one side (outer surface).
Is not provided, so that it is an inactive layer that does not displace even when a voltage is applied, so that even if the thickness changes, the characteristics are not affected.

Since the thickness of each PZT 26 serving as an active layer must be reduced in order to reduce the applied voltage as much as possible, it is not appropriate to increase the thickness of the PZT 26 itself. Further, by making the thickness of the outermost layers (uppermost layer and lowermost layer) PZTs 26a and 26b on both the upper and lower sides larger than the PZT 26 of the other layers, either of the upper and lower sides can be made upper when the piezoelectric element plate is joined. And joining work becomes easy. However, the outermost layer of PZT26 on both upper and lower sides
The problem that the internal electrodes are exposed during cutting can be solved even if only one of the layers a and 26b is thickened.

The present invention is not limited to the ink jet head using displacement of the laminated piezoelectric element in the laminating direction (displacement in the direction d33 in the same direction as the electric field direction), but also displacement in the direction perpendicular to the laminating direction (displacement in the electric field direction). The present invention can also be applied to an ink jet head using (a displacement in the direction d31 in a direction orthogonal to). Further, in the above-described embodiment, an example in which the opening direction of the nozzle is applied to a side shooter type ink jet head coaxial with the displacement direction of the piezoelectric element has been described, but the opening direction of the nozzle is orthogonal to the displacement direction of the piezoelectric element. The invention can also be applied to an ink jet head of an edge shooter type which is oriented. Further, in the above-described embodiment, the bi-pitch structure in which the drive unit piezoelectric elements and the fixed unit piezoelectric elements are alternately arranged is described. However, a normal pitch structure in which all the piezoelectric elements are the drive units may be employed.

[0069]

As described above, according to the ink jet head manufacturing method of the first aspect or the ink jet head of the second aspect, an electrode pattern and a laminated piezoelectric element are provided on an insulating substrate, and the laminated piezoelectric element is formed. Slits are integrally formed on the surface of the piezoelectric element and the substrate to divide it into a plurality of laminated piezoelectric elements and individual electrodes corresponding to each laminated piezoelectric element, and a row of a plurality of laminated piezoelectric elements on the substrate. On an actuator unit in which a frame member having substantially the same height as the stacked piezoelectric element is joined to at least one side in a direction orthogonal to the installation direction, a deformed portion deformed by displacement of each stacked piezoelectric element of the actuator unit A pressurized liquid chamber corresponding to a deformed portion of the vibrating plate, a liquid chamber flow path forming member forming a common ink flow path communicating with the pressurized liquid chamber, and a pressurized liquid chamber. Since the liquid chamber unit and a nozzle plate formed with nozzles formed by joining laminated to be adhesively bonded are an inkjet head, a compact with a high integration density, thin, reduced number of parts, easy to assemble, extraction electrode In addition, it is possible to obtain a highly efficient and highly reliable inkjet head.

[Brief description of the drawings]

FIG. 1 is an external perspective view of an inkjet head showing one embodiment of the present invention.

FIG. 2 is an exploded perspective view of FIG. 1;

FIG. 3 is a sectional view taken along the line AA in FIG. 1;

FIG. 4 is a sectional view taken along the line BB of FIG. 1;

FIG. 5 is a plan view of a substrate used for explaining processing and assembly steps of the actuator unit.

FIG. 6 is a perspective view of the same.

FIG. 7 is a perspective view showing a state in which a piezoelectric element plate is joined to a substrate used for explaining the same process.

FIG. 8 is a perspective view for explaining another embodiment of the actuator unit.

FIG. 9 is a schematic explanatory view for explaining still another embodiment of the actuator unit.

[Explanation of symbols]

1. Actuator unit, 2. Liquid chamber unit, 3.
Substrate, 4 ... piezoelectric element row, 5 ... frame member, 6 ... adhesive, 7 ... driving section piezoelectric element, 8 ... fixed section piezoelectric element, 11 ...
Diaphragm part (displacement part), 12: diaphragm, 13: liquid chamber flow path forming member, 15: nozzle, 16: nozzle plate,
17 ... pressurized liquid chamber, 21 ... slit groove, 22 ... individual electrode,
23 common groove, 24 common electrode, 27 internal electrode, 2
8, 29: End electrode, 51, 52: Pattern for individual electrode, 53: Pattern for common electrode, 56: Piezoelectric element plate, 57, 58: End electrode.

────────────────────────────────────────────────── ─── Continuation of the front page Examiner Katsumi Enari (56) References JP-A-6-238895 (JP, A) JP-A-4-125158 (JP, A) JP-A-6-198877 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B41J 2/16 B41J 2/045 B41J 2/055

Claims (2)

(57) [Claims] 1. A method of manufacturing an ink jet head which ejects ink droplets from the nozzles communicating with each pressurized liquid chamber by pressurizing the pressurized liquid chamber by a plurality of piezoelectric elements arranged in a row, insulated Slip for individual electrodes on a flexible substrate
After forming a common groove deeper than the groove formed by the process, forming an electrode pattern on the insulating substrate and joining the multilayer piezoelectric element, the integrated piezoelectric element is integrated with the surface of the multilayer piezoelectric element and the substrate. The multi-layer piezoelectric element and the electrode pattern are divided into a plurality of multi-layer piezoelectric elements and individual electrodes corresponding to the respective multi-layer piezoelectric elements by slitting, and the plurality of multi-layer piezoelectric elements are formed on the substrate. Deformation due to displacement of each laminated piezoelectric element of this actuator unit on an actuator unit having a frame member having substantially the same height as the laminated piezoelectric element joined to at least one side in a direction orthogonal to the direction in which the elements are arranged A vibrating plate having a deformed portion, a pressurized liquid chamber corresponding to the deformed portion of the vibrating plate, and a liquid chamber flow path forming member forming a common ink flow path communicating with the pressurized liquid chamber; A method of manufacturing an ink jet head, characterized in that the adhesive bonding the liquid chamber unit formed by joining laminating a nozzle plate forming the nozzle communicating with. 2. An ink jet head for jetting ink droplets from each nozzle communicating with each pressurized liquid chamber by pressurizing each pressurized liquid chamber with a plurality of piezoelectric elements arranged in a row. A liquid chamber unit is laminated and joined on an actuator unit, and the actuator unit includes an electrode pattern provided on an insulating substrate and a laminated piezoelectric element integrally formed on the laminated piezoelectric element and the substrate surface. The multi-layer piezoelectric element is slit and divided into a plurality of multilayer piezoelectric elements and individual electrodes corresponding to the respective multilayer piezoelectric elements, and individual electrodes are formed on the insulating substrate.
Create a common groove deeper than the groove formed by slit processing for the pole.
Has the result plurality of laminated type the multilayer piezoelectric element and the frame member substantially the same height on at least one side in the direction orthogonal to the row arrangement direction of the piezoelectric element is bonded to the substrate, the liquid chamber unit A diaphragm having a deformable portion deformed by displacement of each of the stacked piezoelectric elements of the actuator unit; a pressurized liquid chamber corresponding to the deformed portion of the vibrating plate; and a common ink flow path communicating with the pressurized liquid chamber. An ink jet head comprising: a liquid chamber flow path forming member that forms a nozzle; and a nozzle plate having the nozzles that communicate with the pressurized liquid chamber.