JP3171958B2 - 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 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 has been formed 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, it is necessary to attach the same number of piezoelectric elements to the ink jet head as the number of nozzle holes for ejecting ink droplets. This is very time-consuming and 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 to be too small and thin (for example, 1 × 1 mm or less in size and 0.1 mm or less in thickness), it becomes very difficult to handle it during assembly or the like. The element cannot be made too small.

Further, as the piezoelectric elements are arranged smaller and denser, it becomes more difficult to accurately align the piezoelectric elements with the pressure chambers. As a result, the size of the ink droplet and the flying speed of each nozzle are reduced. Variations will degrade print quality.

In view of the above, the present invention provides an ink jet head in which a piezoelectric element can be arranged without displacement with respect to the position of a pressure chamber, and the size and flying speed of ink droplets do not vary from nozzle to nozzle. Aim.

[0010]

In order to achieve the above object, an ink jet head according to the present invention, as shown in FIG. 1 for describing an embodiment, has nozzle holes for ink contained therein. Pressure chamber 2 formed on one surface of the silicon single crystal wafer 1 so as to be in communication with the ink supply path 3 so as to apply pressure for causing the silicon single crystal wafer 1 to discharge as an ink droplet; On the other side,
A concave portion 4 which is concavely formed in alignment with the pressure chamber 2
And a piezoelectric element 9 fixed to the recess 4 for vibrating the vibration plate 5 formed by the wall of the silicon single crystal wafer 1 that separates the recess 4 from the pressure chamber 2. It is characterized by having been provided.

The piezoelectric element 9 may be formed by filling the concave portion 4 with a piezoelectric material 29. Further, the pressure chamber 2 and the concave portion 4 may be formed by etching on both surfaces of the silicon single crystal wafer 1 while being positioned.

[0012]

Since the piezoelectric element 9 is fixed to the recess 4 formed in alignment with the pressure chamber 2, the piezoelectric element 9 is arranged at a position where there is no displacement with respect to the pressure chamber 2.

In this case, the piezoelectric element 9 may be joined to the recess 4. However, if the piezoelectric element 9 is formed by filling the recess 4 with a piezoelectric material 29, the manufacture is easier. Such a pressure chamber 2 and the concave portion 4 are aligned with both surfaces of the silicon single crystal wafer 1 and subjected to an etching process.
It can be processed easily and accurately.

[0014]

An embodiment will be described with reference to the drawings. 1 to 7 show an ink jet head according to a first embodiment of the present invention and a manufacturing process thereof.

In FIG. 2, reference numeral 1 denotes a silicon single crystal wafer, and a pressure chamber 2 has an ink supply path 3 on one surface thereof.
And is formed to be concave. The pressure chamber 2 and the ink supply path 3 are formed by, for example, anisotropic etching.

On the other surface of the silicon single crystal wafer 1,
The recess 4 is formed to be substantially the same size as the pressure chamber 2 in alignment with the pressure chamber 2. The recess 4 is also formed by, for example, anisotropic etching.

At this time, for example, by using a mask eye liner or the like, a mask for etching is placed on the surface of the silicon single crystal wafer 1 with a positional accuracy of several μm and pressure chamber 2.
It can be formed corresponding to the mask on the side.

The wall of the silicon single crystal wafer 1 forming the partition wall between the pressure chamber 2 and the recess 4 thus formed becomes the vibration plate 5 vibrated by the piezoelectric element 9 described later.

FIG. 2 shows one pressure chamber 2, but as shown in FIG.
Is a size for forming a large number of inkjet heads 10 collectively.
4, a large number of pressure chambers 2 are formed in each ink jet head 10. As shown in FIG.

Next, as shown in FIG. 5, the entire surface of the silicon single crystal wafer 1 on which the concave portion 4 is formed,
For example, the aluminum electrode layer 6 is formed by vacuum evaporation. Further, as shown in FIG. 6, a piezoelectric element 9 having electrodes 9a and 9b formed on both front and back surfaces and having a size just fitted into the concave portion 4 is fitted into the concave portion 4 to form a conductive element. It is bonded and fixed to it with an adhesive having a certain property.

In this way, the lower electrodes 9a of all the piezoelectric elements 9 are
And the aluminum electrode layer 6 can be used as a common electrode.

Finally, as shown in FIG. 1, a nozzle plate 8 made of, for example, a photosensitive glass material and having a nozzle hole 7 formed on a surface of the silicon single crystal wafer 1 on which the pressure chamber 2 is formed. After bonding, the whole is divided and cut into individual inkjet heads 10 shown in FIG.

In the ink jet head 10 formed as described above, the voltage is applied to both the electrodes 9 a and 9 b to deform the piezoelectric element 9, whereby the vibration plate 5 vibrates and the ink in the pressure chamber 2 is pressurized. Is added, and the ink is ejected from the nozzle hole 7 as an ink droplet.

FIGS. 7 to 10 show an ink jet head according to a second embodiment of the present invention and the manufacturing process thereof. However, the initial part of the manufacturing process is the same as the state shown in FIGS. 2 to 4 of the first embodiment.

In this embodiment, as shown in FIG. 2, if the pressure chambers 2 and the recesses 4 are formed on both sides of the silicon single crystal wafer 1 while being aligned and recessed, as shown in FIG. Thus, a nozzle plate 28 made of a silicon single crystal wafer having a nozzle hole 27 formed by etching is joined to the surface of the silicon single crystal wafer 1 on which the pressure chamber 2 is formed. This bonding can be performed by so-called direct bonding, for example, by heating at 1100 ° C. for 30 minutes without using an adhesive or the like.

Then, as shown in FIG. 8, a platinum electrode layer 26 is formed on the entire surface of the silicon single crystal wafer 1 on the side where the recess 4 is formed, for example, by sputtering.
To form a lower electrode.

Next, as shown in FIG. 9, the concave portion 4 is filled with a piezoelectric paste 29, dried, and then heated at, for example, 1000 ° C. for 2 hours to fire the piezoelectric element 9. As the piezoelectric paste 29, for example, a piezoelectric fine powder (PZ) made of lead oxide, zirconium oxide, and titanium oxide is used.
A mixture of T), a binder for binding the powders together, and an organic solvent is used.

When the piezoelectric element 9 is formed in the recess 4 in this manner, for example, a silver paste is printed on the surface of the piezoelectric element 9 by screen printing or the like so as not to contact the lower electrode 26 as shown in FIG. Then, it is dried to form the upper electrode 30.

With the structure as in the second embodiment, the operation of forming and mounting the piezoelectric element 9 is greatly simplified, and the manufacturing cost can be reduced.

[0030]

According to the ink jet head of the present invention, the piezoelectric element is fixed to the concave portion formed in alignment with the pressure chamber, so that the piezoelectric element can be arranged without displacement with respect to the pressure chamber. Since the size and the flying speed of the ejected ink droplets do not vary from nozzle to nozzle, uniform and high-quality print quality can be obtained.

[Brief description of the drawings]

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

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

FIG. 9 is a partial front sectional view showing a manufacturing process of the second embodiment.

FIG. 10 is a partial front sectional view of the second embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 silicon single crystal wafer 2 pressure chamber 3 ink supply path 4 recess 5 vibration plate 9 piezoelectric element

──────────────────────────────────────────────────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-3-253346 (JP, A) JP-A-1-288453 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41J 2/045 B41J 2 / 055

Claims (4)

(57) [Claims] 1. A silicon single crystal wafer is formed so as to be recessed in communication with an ink supply path on one surface of a silicon single crystal wafer in order to apply pressure for discharging ink as ink droplets from a nozzle hole to ink contained therein. A pressure chamber, a recess formed by recessing the other surface of the silicon single crystal wafer in alignment with the pressure chamber, and a silicon single crystal wafer separating the recess and the pressure chamber. An ink jet head, comprising: a vibrating plate formed by a wall portion; and a piezoelectric element formed by filling the concave portion with a piezoelectric material . 2. A pressure is applied to ink contained in a pressure chamber.
As a result, the ink is discharged from the nozzle hole communicating with the pressure chamber.
In an ink jet head from which droplets are ejected, the pressure chamber is formed to be concave on one surface,
A recess is formed on the other surface in alignment with
The partition wall between the force chamber and the recess forms ink in the pressure chamber.
Silicon single crystal that functions as a diaphragm for applying the above pressure
Wafer and fixed in the recess to vibrate the diaphragm
Piezoelectric element and opening of pressure chamber formed in the silicon single crystal wafer
So that the one surface of the silicon single crystal wafer is closed
Is placed in close contact with the pressure chamber
A nozzle plate made of a plate-shaped member having a nozzle hole formed therethrough;
The ink jet head is characterized by comprising. 3. The piezoelectric element includes a piezoelectric material in the recess.
3. The ink jet according to claim 2, which is formed by filling.
head. 4. The pressure chamber is provided on the silicon single crystal wafer.
And a plurality of sets of said recesses are formed.
3. The inkjet head according to 3.