JPH05278214A - Ink jet head - Google Patents

Abstract

PURPOSE:To enhance the reliability of the lowering of the insulation resistance of a piezoelectric body due to the moisture transmission of ink from a nozzle part. CONSTITUTION:A piezoelectric body is bonded to a substrate 1 and a membrane member 9 is laminated on the poiezoelectric body to mount a passage plate 3. When a printing signal is sent to the piezoelectric body 10, the thickness of the piezoelectric body 10 is displaced corresponding to said signal to generate a volumetric change in the ink cavity of the passage plate 3 to injet ink from a nozzle 5. A protective plate 4 is bonded after the substrate and the piezoelectric body are bonded to be subjected to slit processing.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an inkjet head,
More specifically, the present invention relates to a head unit of an inkjet recording device.

[0002]

2. Description of the Related Art Since a drop-on-demand type ink jet has a simple structure, it is being developed as a low-priced printing apparatus. Although the ejection of ink is performed by the deformation of the piezoelectric element, it is difficult to achieve high density integration by increasing the number of nozzles, although there is an advantage that the driving voltage does not rise relatively. In order to solve this point, for example, an "ink jet head" has been proposed in JP-A-60-90770. The publication discloses a head provided with a rigid member that holds a piezoelectric body on a vibrating plate and holds it rigidly. That is, the vibration plate is interposed between the piezoelectric body and the ink cavity to prevent the moisture from permeating the ink.

Further, the previously proposed Japanese Patent Laid-Open No. 3-1629.
The "ink-jet recording device" of Japanese Patent Laid-Open No. 62-62 prevents damage caused during processing by joining a piezoelectric body and a protective plate before processing a slit (groove). It was preventing penetration. However, although it is possible to prevent electrode damage due to groove processing, since the slits are provided, it is not possible to prevent moisture permeation of the ink from here and there is a drawback that the insulation resistance of the piezoelectric body decreases.

As described above, conventionally, the measures against the insulation of the ink jet using the piezoelectric material are only related to the prevention of the moisture permeation from the ink cavity. However, in any of the above-mentioned publications, the piezoelectric material from the nozzle side is also used. The current situation is that it is not possible to prevent the permeation of ink into the ink.

[0005]

An object of the present invention is to provide an ink jet head which has been made in view of the above circumstances and is intended to improve reliability of a decrease in insulation resistance of a piezoelectric body due to moisture permeation of ink from a nozzle portion side. It was made for the purpose.

[0006]

In order to achieve the above object, the present invention provides (1)
The piezoelectric body is provided with slits, the convex portions formed between the slits are used as actuators, parallel flow paths are provided corresponding to the convex portions, and thickness displacement occurs in the direction perpendicular to the plane of the parallel flow paths. In the ink jet recording apparatus that ejects droplets from the nozzles by providing the above, a protective plate is provided on the front surface of the piezoelectric body on the ink droplet ejecting side so as to cover the slits,
Further, (2) the slit portion is filled with a filler,
The piezoelectric material is filled with a material having different elastic moduli in both the active portion and the inactive portion, and (3) a thin film member in which the end portion of the piezoelectric material is joined to the upper surface of the slit. It is characterized in that they are joined so as to be rolled in and a protective plate is provided at the joint. Hereinafter, description will be given based on examples of the present invention.

FIG. 1 is a perspective view for explaining an embodiment of an ink jet head according to the present invention, and FIG.
FIG. In the figure, 1 is a substrate, 2 is a piezoelectric body,
3 is a flow path plate, 4 is a protection plate, 5 is a nozzle, 6 is a wire bond part, 7 is a relay plate, 8 is an FPC (flexible printed circuit board), 9 is a thin film member, 10 is a driving piezoelectric body, and 11 is a filler. Is. The piezoelectric body 2 is bonded onto the substrate 1, the thin film member 9 is laminated thereon, and the flow path plate 3 is mounted. In the ejection, a print signal is sent to the driving piezoelectric body 10 via the FPC 8, and accordingly, the piezoelectric body 2 is displaced in thickness, causing a volume change in the ink cavity of the flow path plate 3. As a result, it is ejected from the nozzle 5.

As a method of manufacturing the head, the substrate 1 is replaced by the piezoelectric body 2.
Are joined, slit processing is performed with a dicing saw, and then the protective plate 4 is joined. Since flatness cannot be obtained if these are joined, grinding is performed to obtain flatness, and then the thin film member 9 is laminated and joined. After that, the filling material 11 is filled by vacuum filling from the side opposite to the nozzle portion. Next, the flow path plate 3 is joined and the members of the flow path plate 3 and the protective plate 4 are cut at the same time in order to uniformly form the nozzles 5. In the embodiment of the present invention, the nozzle 5 is provided at the tip of the flow path plate 3, but a separate member may be joined as the nozzle plate. Finally, the wire bond part 6, the relay plate 7, and the FPC
8 are connected to complete the head.

Here, as the material of the filler 11, a flexible soft material is used in order to secure the granulation characteristics of the head, so that the hygroscopicity and ink resistance are inferior. Therefore, when the member of the filler is exposed, ink permeates and the insulation resistance of the piezoelectric body is lowered over a long period of time, and further progresses, causing migration and short-circuiting. In order to prevent this, a flat plate like the protective plate 4 is joined to the front surface of the slit. In the embodiment of the present invention, the protective plate 4
Is directly bonded to the piezoelectric body 2, but the protective plate 4 may be provided on the protective member to be slit.

FIG. 3 is a sectional view showing another embodiment of the ink jet head according to the present invention, and FIG. 4 is a perspective view of FIG. In the figure, 11a and 11b are fillers, and other parts having the same functions as those in FIG. 1 are denoted by the same reference numerals. In the figure, A and A ′ are inactive portions, B is an active portion, and C is a slit depth. As a manufacturing method, the substrate 1 and the piezoelectric body 2 are bonded and then ground. At this time, in the above-mentioned process, since the grinding process was performed after the slit process, there was a concern that the thin piezoelectric body would be broken. However, in this process,
Since it is performed before slitting, there is no yield loss due to this. After that, slit processing is performed to laminate the thin film member 9. After that, the filler 11a is filled in the active portion B and the inactive portion A'shown in FIG. 3, and then the inactive portion A shown in FIG. 3 is filled with the filler 11b. The filling depth is C
Complete up to the area.

At this time, the inactive portions A and A'are both inactive portions of the piezoelectric body and are not driven. In particular, changing the filling material in the area A is to prevent the moisture permeation of the ink from the nozzle portion or the permeation of the ink from the slit when the ink drips. Further, as another required function, since the B region is an active part, it must be a soft filler so that it is easy to operate and does not affect the adjacent piezoelectric body. Further, as described above, in order to uniformly form the nozzle, the nozzle is cut at the D-D portion to form a flat surface. At this time, if the filling material is not completely cut and sticks out, it may penetrate into the nozzle 5. Therefore, in order to improve these problems, the filler 11b, which has a higher elastic modulus than the filler 11a and is excellent in adhesiveness and water absorption, is used.

As a concrete process, there is a method of filling and curing a putty-like filler and then vacuum filling the flexible filler. Further, as a simpler filling method, a filler which is UV-curable with a flexible filler is capillary-filled and cured. At this time, since it is an acrylic UV curable resin, the shrinkage rate is large, and even if the regions of the inactive portion A, the active portion B, and the inactive portion A ′ shown in FIG. Set up.
That is, by irradiating and curing the inactive portion A ′, and finally irradiating the A region, it is possible to bring the space region due to contraction into the A region. After that, the region A is vacuum-filled with the filling material 11b, so that it is possible to easily complete the filling without contaminating the portions of the wire bond portion 6 and the relay plate 7 where the electric extraction portion is present.

FIG. 5 is a sectional view showing still another embodiment of the ink jet head according to the present invention, and FIG. 6 is a perspective view of FIG. That is, the thin film member 9 provided between the piezoelectric body 2 and the flow path plate 3 is bent so as to wrap the piezoelectric body 2, and the protective plate 4 is further provided at the bent portion. The protective plate 4 not only prevents the moisture permeation from the nozzle portion, but also has a function as a cutting member for forming the nozzle. In the manufacturing process, the thin film member is laminated and bonded, and then bent and bonded to the piezoelectric body 2 and the filler 11. After that, the flexible filler is vacuum-filled.

[0014]

As is apparent from the above description, the present invention has the following effects. (1) By providing the protective plate so as to cover the slit portion of the voltage body, moisture permeation from the nozzle portion can be prevented, and the reliability of the piezoelectric body can be improved. (2) By forming the filler in two layers, reliability can be secured without impairing the ejection characteristics of the head. (3) By covering the slit end portion with a thin film member having excellent moisture absorption resistance and further providing a protective plate, it is possible to prevent penetration from the nozzle portion and dripping ink, and it is possible to improve the reliability of the piezoelectric body. ..

[Brief description of drawings]

FIG. 1 is a perspective view illustrating an embodiment of an inkjet head according to the present invention.

FIG. 2 is a cross-sectional view of FIG.

FIG. 3 is a sectional view showing another embodiment of the inkjet head according to the present invention.

4 is a perspective view of FIG. 3. FIG.

FIG. 5 is a sectional view showing still another embodiment of the inkjet head according to the present invention.

FIG. 6 is a perspective view of FIG.

[Explanation of symbols]

1 ... Substrate, 2 ... Piezoelectric body, 3 ... Flow path plate, 4 ... Protective plate, 5 ...
Nozzle, 6 ... Wire bond part, 7 ... Relay plate, 8 ... FPC
(Flexible printed circuit board), 9 ... Thin film member, 10 ...
Driving piezoelectric body, 11 ... Filling material.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshikazu Hirakawa 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd. (72) Yuichiro Ishii 1-3-6 Nakamagome, Ota-ku, Tokyo Shares Company Ricoh

Claims (3)

[Claims] 1. A piezoelectric body is provided with a slit, a convex portion formed between the slits is used as an actuator, a parallel flow path is provided corresponding to the convex portion, and a direction perpendicular to a plane of the parallel flow path. An ink jet recording apparatus for ejecting liquid droplets from a nozzle by causing a thickness displacement in the ink jet recording apparatus, wherein a protective plate is provided on the front surface of the piezoelectric body on the ink droplet ejection side so as to cover the slit. 2. The slit portion is filled with a filling material,
2. The ink jet head according to claim 1, wherein a filler having different elastic moduli is filled in both the active portion and the inactive portion of the piezoelectric body. 3. The ink jet head according to claim 1, wherein an end portion of the piezoelectric body is joined by turning around with a thin film member joined to the upper surface of the slit, and a protective plate is provided at the joint portion.