JP2948429B2 - Method of manufacturing inkjet head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an ink-jet head for performing recording by discharging ink droplets.

[0002] The ink jet recording system has features such as a simple structure, easy colorization, and no noise, and is expected as a mainstream of the recording system in the future.

[0003]

2. Description of the Related Art In order to discharge ink droplets from an ink jet head, a vibration plate provided facing a pressure chamber is vibrated to apply a discharge pressure to ink in the pressure chamber.

Generally, a piezoelectric element vibrates the vibration plate, and is provided in close contact with the surface of the vibration plate corresponding to the position of the pressure chamber. Conventionally, such a piezoelectric element is formed independently of the diaphragm in a size corresponding to the size of the pressure chamber and then adhered to the surface of the diaphragm one by one.

[0005]

However, since it is necessary to attach the same number of piezoelectric elements to the ink jet head as the number of ink discharge nozzles, it is very time-consuming to bond each piezoelectric element to the vibration plate. This increases the manufacturing cost of the head.

Further, in order to reduce the size of the head, the pressure chambers must be arranged at a high density. Therefore, the piezoelectric element must be formed small accordingly, and the thickness must be reduced accordingly. .

However, if the piezoelectric element is formed too small and thin (for example, 1 × 1 mm or less in size and 0.1 mm or less in thickness), it becomes difficult to handle at the time of assembly or the like. It could not be made too small, which was the bottleneck for miniaturizing the head.

[0008] Further, since the movement to be transmitted from the piezoelectric element to the vibrating plate is absorbed by the adhesive layer between the piezoelectric element and the vibrating plate, there is a functional problem that the energy efficiency is low.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of manufacturing an ink jet head which can greatly reduce the manufacturing cost of the head, is energy efficient, and can reduce the size of the head.

[0010]

In order to achieve the above object, a method of manufacturing an ink jet head according to the present invention uses a piezoelectric layer 9 as shown in FIG.
A piezoelectric paste containing a piezoelectric material is printed on the surface of the vibration plate 5 formed of a heat-resistant material that withstands the temperature at which the ink is fired, corresponding to the position of the pressure chamber 2 for applying the ejection pressure to the ink. Then, heating and firing are performed to form the piezoelectric layer 9.

The vibrating plate 5 is for forming a plurality of ink jet heads 4 on one sheet, and the piezoelectric layer 9 for forming the plurality of ink jet heads 4 is simultaneously printed on the vibrating plate 5. Heating and firing.

After the electrode layer 8 is formed on the surface of the vibration plate 5 in advance, the piezoelectric layer 9 and the electrode layer 10 are printed and fired on the electrode layer 8 corresponding to the position of the pressure chamber 2. May be.

[0013]

The piezoelectric layer 9 is printed on the surface of the vibration plate 5 corresponding to the position of the pressure chamber 2 and then heated, so that the piezoelectric layer 9 is directly fired on the surface of the vibration plate 5.

In this case, a plurality of ink jet heads 4
The piezoelectric layers 9 for forming the plurality of ink jet heads 4 can be simultaneously printed and baked on one vibration plate 5 for forming the ink jet head 4.

Before printing the piezoelectric layer 9, the diaphragm 5
By previously forming the electrode layer 8 on the surface of the substrate, a so-called lower electrode can be obtained.

[0016]

An embodiment will be described with reference to the drawings. 1 to 11 show a first embodiment of the present invention. First, as shown in FIG. 2, a silicon single crystal wafer 1 having a thickness of, for example, 0.5 mm is formed with a pressure chamber 2 by etching. Each of the ink flow paths 3 is formed at a predetermined depth.

FIG. 2 shows one pressure chamber 2, but as shown in FIG.
Is a size for forming a large number of inkjet heads 4 collectively, and as shown in FIG. 4 showing a portion A of one inkjet head 4, a large number (for example, 64) of pressures are applied to each inkjet head 4. Chambers 2 are arranged.

Next, as shown in FIG. 5, the silicon single crystal wafer 1 is ground to a thickness of, for example, 0.1 mm from the surface opposite to the side on which the pressure chamber 2 is formed. Thereby, the portion on the back side of the pressure chamber 2 has a predetermined thickness (for example, 0.
02 to 0.025 mm).

Next, as shown in FIG. 6, a nozzle plate 7 made of a silicon single crystal wafer having a nozzle hole 6 formed through etching is attached to the silicon single crystal wafer 1 so as to cover the surface of the pressure chamber 2. Join.

This bonding can be performed by so-called direct bonding in which the bonding surfaces are completely adhered to each other and heated in a vacuum at, for example, 1100 ° C. for 30 minutes to integrate the bonding surfaces.

The positional relationship between the nozzle hole 6 and the pressure chamber 2 is as shown in FIG. 7, and the silicon single crystal wafer 1 and the nozzle plate 7 are positioned so that the nozzle hole 6 is located near the end of each pressure chamber 2. Are combined.

Next, as shown in FIG. 8, the surface of the silicon single crystal wafer 1 on the side opposite to the pressure chamber 2, ie, the diaphragm 5
A conductive paste whose viscosity is adjusted to, for example, 2,000 cP by mixing, for example, silver and palladium powders, a binder for binding them, and an organic solvent, is printed to a thickness of 5 μm by, for example, a screen printing method, After drying, the lower electrode layer 8 is heated by heating at a high temperature of, for example, 1000 ° C. for 2 hours in an electric furnace.

Since the silicon single crystal wafer 1 is not melted up to a high temperature of about 1200 ° C. and does not generate distortion, it can sufficiently withstand the above-described heat treatment during firing.

Next, on the surface of the lower electrode layer 8, for example, a piezoelectric fine powder (PZT) made of, for example, lead oxide, zirconium oxide, and titanium oxide, a binder for binding these powders, and an organic solvent are mixed. 3000 cP viscosity
Is adjusted to a thickness of 30 μm by screen printing.

When the piezoelectric layer 9 is formed by screen printing, the thickness is suitably in the range of 5 to 100 μm, and the electrode layers 8 and 10 may be formed in the thickness of 1 to 10 μm. it can. The temperature at which the electrode layers 8, 10 and the piezoelectric layer 9 are fired varies depending on the material used.
A range of １1500 ° C. is used.

As a material for the piezoelectric paste, a material such as barium titanate ceramic, PMN-PT or PNN-PTPZ to which a compound having a perovskite structure is added can be used.

In the screen printing, as schematically shown in FIG. 9, a screen 21 on which a printing pattern is formed is arranged on the surface of the silicon single crystal wafer 1, and a conductive paste or a piezoelectric paste 22 is applied thereon. This is performed by moving the squeegee 23 while pressing it.

At this time, the printing of the piezoelectric paste 22 is performed as follows.
The pressure chamber 2 is adjusted in position and size. When the printed piezoelectric paste 22 is dried, the piezoelectric paste 22 is heated at a high temperature of, for example, 1000 ° C. for 2 hours in an electric furnace to evaporate an organic solvent or the like from the piezoelectric paste 22.

As a result, as shown in FIGS. 10 and 11, the piezoelectric layer 9 is fired on the surface of the vibration plate 5 so as to match the position and size of each pressure chamber 2. When the piezoelectric layer 9 is fired in this manner, finally, as shown in FIG.
Print and bake at μm. The material and firing conditions of the upper electrode layer 10 may be the same as those of the lower electrode layer 8.

As described above, in the present invention, the diaphragm 5
Since the electrode layer 8 and the piezoelectric layer 9 are formed on the surface of the substrate by direct printing, it is excellent in manufacturability, and a desired thickness, size, and shape can be formed with high reliability.

When the piezoelectric layer 9 and the upper and lower electrode layers 8 and 10 are formed on the surface of the vibration plate 5 in this manner, the whole is shown in FIG.
Is cut into individual inkjet heads 4 as shown in FIG.

In the ink jet head thus formed, the ink is supplied from the ink flow path 3 to the pressure chamber 2.
When the voltage is applied between the upper and lower electrodes 8 and 10, the piezoelectric layer 9 is deformed, whereby the vibration plate 5 vibrates and the ejection pressure is applied to the ink in the pressure chamber 2,
The ink in the pressure chamber 2 is ejected as ink droplets from the nozzle holes 6 to perform recording.

In the present invention, by controlling the thickness of the printing plate, the thickness of the piezoelectric layer 9 can be freely formed in the range of 2 to 200 μm. Therefore, by setting the thickness of the piezoelectric layer 9 to the most preferable thickness with respect to the thickness of the vibration plate 5, the particles can be ejected from the nozzle at a high particleization efficiency and a low driving voltage.

Further, since the diaphragm 5 and the electrode layer 8, and the electrode layer 8 and the piezoelectric layer 9 are directly joined by printing and baking, there is no adhesive layer as in the prior art, and the efficiency of particle formation is further improved. Can be.

FIGS. 12 and 13 show a second embodiment of the present invention, in which photosensitive glass is used as the nozzle plate 7 and the lower electrode layer 8 is formed by depositing platinum by sputtering. Things.

In this case, the photosensitive glass cannot withstand the sintering temperature of the piezoelectric layer 9, and therefore, as shown in FIG. 9 and the upper electrode layer 10 are printed and fired, and thereafter, as shown in FIG.
Is bonded to the silicon single crystal wafer 1.

FIGS. 14 to 16 show a third embodiment of the present invention. First, a single stainless steel substrate 3 is formed.
First, a pressure chamber 2 and an ink supply path 3 are formed by etching. The size of the pressure chamber 2 is, for example, 1 × 2 mm,
The diameter of the outlet of the nozzle hole 6 is 50 μm.

The diaphragm 5 is made of an austenitic stainless steel plate (SUS304) having a thickness of 50 μm, and the substrate 31 and the diaphragm 5 are joined by diffusion bonding.

A printing plate having an opening mesh of 1 × 2 mm was placed on the diaphragm 5, and an electrode material containing silver as a main component was mixed with an organic resin binder and an organic solvent, and the viscosity was set to 2000 c.
The paste adjusted to P is 5 μm thick with a squeegee.
To form a lower electrode 8 as shown in FIG.

Then, a paste containing a piezoelectric material is printed thereon with a thickness of 50 μm using a printing plate having the same shape, and a piezoelectric layer 9 is formed as shown in FIG. The piezoelectric material was prepared by mixing PZT into a powder and mixing an organic resin binder to adjust the viscosity to 3000 cP.

Further, the same material as the lower electrode layer 8 is printed on the piezoelectric layer 9 to a thickness of 3 μm to form the upper electrode 10 as shown in FIG. Then, the entire inkjet head thus configured is heated in a heating furnace at 100 ° C. for 10 minutes, and further heated in a heating furnace at 1000 ° C. for 1 minute.
Heat for hours.

The ink liquid is injected into the ink-jet head manufactured as described above, and a voltage of 50 V is applied to the electrodes 8 and 10. As a result, the ink droplet is stably ejected from the nozzle hole 6 at a speed of 7 m / s. I was able to.

For comparison, 1 × 2 mm,
As a result of examining the characteristics of a head manufactured by bonding a piezoelectric element having a thickness of 100 μm with an epoxy resin-based adhesive, a voltage of 120 V was required to obtain the same particle velocity.

In the same manner as in the third embodiment, the both electrodes 8 and 10 were each 2 μm thick and the piezoelectric layer 9 was 20 μm thick using heat-resistant glass having a thickness of 100 μm for the diaphragm 5.
The thickness of the ink jet head was printed by a screen printing method, heated at 100 ° C. for 10 minutes, and then baked at 900 ° C. for 1 hour, and a particle velocity of 7 m / s was obtained at an applied voltage of 60 V.

FIG. 17 shows a fourth embodiment of the present invention, in which the same head constituent material, electrode material and piezoelectric material as those of the third embodiment are applied to the diaphragm 5 by using a dispenser 40.
The electrode layer 8 (thickness 3 μm) and the piezoelectric layer 9 (25 μm thick)
m thickness) and the electrode layer 10 (thickness 3 μm) in order of radius 0.5
A head was prototyped by molding into a mm-shaped disk, followed by heating and firing.

At this time, the viscosity of the printing paste is 500
It was suitable to be about cP. As a result of examining the characteristics of the manufactured inkjet head, a particle velocity of 7 m / s was obtained at 40 V.

FIGS. 18 and 19 show a fifth embodiment of the present invention, in which a nozzle plate 7 having a plurality of nozzle holes 6 is provided.
In the multi-nozzle head constituted by the ink flow path plate 41 in which the pressure chambers 2 corresponding to the plurality of nozzle holes 6 are formed and the vibration plate 5, the piezoelectric layer 9 is provided in the portion of the vibration plate 5 corresponding to each pressure chamber 2. Is formed by printing.

In this embodiment, the number of nozzle holes 6 is 64, and 64 corresponding pressure chambers 2 are also arranged. The size of one pressure chamber 2 is 0.5 × 1.0
mm.

In manufacturing this, first, a screen printing plate having an opening mesh corresponding to the entirety of the 64 pressure chambers 2 on the vibration plate 5 is used, and the electrode material containing silver as a main component is changed to an organic material. Mix with resin binder and organic medium to increase viscosity to 2
The paste adjusted to 000 cP is printed with a squeegee to a thickness of 5 μm to form the lower electrode 8.

Next, using a printing plate having a plurality of opening meshes corresponding to the respective pressure chambers 2, the piezoelectric layer 9 is formed to a thickness of 40 μm.
Print with m. Further, the same electrode material as that of the lower electrode 8 is printed on each piezoelectric layer 9 at a thickness of 3 μm to form an upper electrode (not shown).

The head manufactured in this manner is
By heating at 10 ° C. for 10 minutes and firing at 1000 ° C. for 2 hours, an ink jet head is completed.
Then, ink was injected into the head, and a voltage pulse was applied to each electrode. As a result, ink particles were ejected from each nozzle hole 6 at an average speed of 7 m / s at a driving voltage of 40 V. The variation in the particle velocity of each nozzle hole 6 was ± 10% or less.

For comparison, 0.5% was obtained by the conventional manufacturing method.
A head was manufactured by bonding piezoelectric elements having a thickness of 1.0 mm and a thickness of 100 μm one by one with an epoxy adhesive, and the characteristics of the head were examined. And a particle velocity of 7 m / s. The variation in the speed of each nozzle was ± 30% or more.

FIG. 20 shows a sixth embodiment of the present invention, in which one ink jet head member 51 has a flow path formed by etching a single stainless steel base.

The size of the outlet of the nozzle hole 6 is 50 μm in diameter.
The size of the pressure chamber 2 is 0.5 × 1.0 mm.
The diaphragm 5 is made of a stainless steel plate (SUS304),
The thickness was 50 μm. The joining of the diaphragm 5 and the flow path substrate is performed as follows.
This was performed by diffusion bonding.

The ink-jet head material 51 thus formed is arranged on a head fixing jig 50 of 4 × 5 rows with the vibration plate 5 facing upward as shown in FIG. Although not shown in the drawing, openings for one head in which 64 0.5 × 1.0 mm opening meshes are arranged on the diaphragm 5 of these heads are further provided in a total of 20 rows in 4 rows and 5 rows. A printing plate 21 in which heads are arranged is overlapped, and an electrode material containing silver as a main component is mixed with an organic resin binder and an organic solvent, and a paste whose viscosity is adjusted to 2000 cP is printed with a squeegee 23 to a thickness of 5 μm. To form a lower electrode layer 8.

Further, a piezoelectric layer 22 was formed thereon by printing a piezoelectric paste 22 with a thickness of 30 μm using a printing plate 21 having the same shape. The piezoelectric paste 22 was prepared by mixing PZT into powder and mixing an organic resin binder to adjust the viscosity to 3000 cP.

Further, the same material as that of the lower electrode layer 8 was printed 3 μm on the piezoelectric layer 9 to form an upper electrode 10.
Then, the entire head fixing jig 50 was heated in a heating furnace at 100 ° C. for 10 minutes, and further baked in a heating furnace at 1000 ° C. for 1 hour.

The ink jet head 4 thus manufactured is taken out of the head fixing jig 50, ink is injected into these heads 4, and a voltage pulse is applied to each electrode. The ink particles were jetted at a speed of 6 to 7 m / s on average.

The variation in the particle velocity of each nozzle hole 6 is ± 1.
0% and the average flow velocity of the 20 heads is 7
The variation was within m / s ± 5%. For comparison, 0.5 × 1.0 mm, thickness 100 μm by the conventional manufacturing method
Of the piezoelectric elements one by one with an epoxy adhesive
As a result of manufacturing heads and examining the characteristics of the heads, a particle speed of 7 m / s was obtained as an average of all nozzles at a high driving voltage of 150 V, but the speed variation of each nozzle was ± 30% or more. The variation in the average speed of the 20 heads was ± 25% or more.

FIG. 21 shows a seventh embodiment of the present invention, in which 64 head constituent materials, electrode materials and piezoelectric materials similar to those of the sixth embodiment shown in FIG. 20 are arranged per head. In addition, a lower electrode layer (thickness: 3 μm) is formed on the diaphragm 5 by using a dispenser 60 having a plurality of nozzles in accordance with a pattern in which the heads are arranged in 4 × 5 rows.
A plurality of heads were manufactured simultaneously by heating and firing after forming a piezoelectric layer (thickness: 25 μm) and an upper electrode layer (thickness: 3 μm) in the order of 0.5 mm in radius.

At this time, the viscosity of the printing paste is 500
A cP level was suitable. As a result of examining the characteristics of the 20 prototype heads, the variation in the particle velocity was ± 20% or less.

It should be noted that the head constituent material to which the present invention is applicable can be applied not only to the materials described here but also to ceramics such as alumina, various metals, photosensitive glass, various crystalline materials, and the like. Nor. Also, various materials can be used for the electrode material and the material of the piezoelectric layer as well as the head constituent material.

The present invention is not limited to the above embodiments. For example, for printing, a letterpress, intaglio or any other printing method other than screen printing may be used.

[0064]

According to the method of manufacturing an ink jet head of the present invention, the piezoelectric layer is formed on the surface of the vibration plate by printing and firing, so that the number of assembling steps is reduced and a significant cost reduction is achieved. In addition, since the piezoelectric layer can be formed as small as possible and high in density to the limit of the printing technology, the size of the ink jet head can be significantly reduced.

Further, since the vibration plate and the piezoelectric layer are formed in direct contact with each other without an adhesive layer therebetween, the deformation of the piezoelectric layer is efficiently transmitted to the vibration plate, and the energy loss is extremely small. Efficient.

[Brief description of the drawings]

FIG. 1 is a front partial sectional view showing a manufacturing process of a first embodiment.

FIG. 2 is a partial front sectional view showing a manufacturing process of the first embodiment.

FIG. 3 is an overall plan view showing a manufacturing process of the first embodiment.

FIG. 4 is a plan sectional view showing the manufacturing process of the first embodiment.

FIG. 5 is a partial front sectional view showing the manufacturing process of the first embodiment.

FIG. 6 is a partial front sectional view showing the manufacturing process of the first embodiment.

FIG. 7 is a plan view showing the manufacturing process of the first embodiment.

FIG. 8 is a partial front sectional view showing the manufacturing process of the first embodiment.

FIG. 9 is a schematic side view showing the manufacturing process of the first embodiment.

FIG. 10 is a plan view showing the manufacturing process of the first embodiment.

FIG. 11 is a partial front sectional view showing the manufacturing process of the first embodiment.

FIG. 12 is a partial front sectional view showing a manufacturing process of the second embodiment.

FIG. 13 is a partial front sectional view showing a manufacturing process of the second embodiment.

FIG. 14 is a front sectional view showing the manufacturing process of the third embodiment.

FIG. 15 is a front sectional view showing the manufacturing process of the third embodiment.

FIG. 16 is a front sectional view showing the manufacturing process of the third embodiment.

FIG. 17 is a partial vertical sectional view showing a manufacturing process of the fourth embodiment.

FIG. 18 is a plan view showing a fifth embodiment.

FIG. 19 is a front sectional view showing a fifth embodiment.

FIG. 20 is a schematic front sectional view showing a manufacturing process of the sixth embodiment.

FIG. 21 is a schematic front view showing the manufacturing process of the seventh embodiment.

[Explanation of symbols]

 2 pressure chamber 5 diaphragm 9 piezoelectric layer

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Mineharu Tsukada 1015 Uedanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Inside Fujitsu Co., Ltd. (56) References JP-A-5-286131 (JP, A) JP-A-4-168052 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B41J 2/16 B41J 2 / 045 B41J 2/055

Claims (3)

(57) [Claims] A surface of a single diaphragm made of a heat-resistant material that withstands a temperature at which a piezoelectric layer is fired,
Corresponding to the positions of the plurality of pressure chambers for applying discharge pressure to the ink, plural piezoelectric paste containing a piezoelectric material 箇
After printing at the same time, heating and firing the piezoelectric layer,
After dividing the diaphragm into one inkjet head unit
A method for manufacturing an ink jet head. 2. The method of manufacturing an ink jet head according to claim 1, wherein the one ink jet head includes a plurality of pressure chambers and a plurality of piezoelectric layers corresponding to the plurality of pressure chambers. 3. A plurality of diaphragms formed of a heat-resistant material that withstands the temperature at which the piezoelectric layer is fired are attached to one head fixing jig, and the ejection pressure of ink is applied to each of the diaphragms. Corresponding to the positions of the plurality of pressure chambers for applying, after simultaneously printing the piezoelectric paste containing the piezoelectric material at a plurality of locations, heating and firing the piezoelectric layer,
A method for manufacturing an ink jet head, wherein each of the vibration plates is detached from the head fixing jig.