JPH04263955A - Manufacture of ink jet head - Google Patents

Abstract

PURPOSE:To enhance the printing quality as a printer by performing high density dot printing by the densification of a groove pitch due to adhesion. CONSTITUTION:An insulating ceramic substrate 3a and PZT sheets 4a,4b are baked and bonded through metallized layers 9a, 9b, 9c being conductive films due to silver paste. A negative electrode 200 is connected to the metallized layers 9a, 9c and a positive electrode is connected to the metallized layer 9b and predetermined high voltage is applied across the electrodes to polarize the metallized layers. Then, grooves 20-24 and partition walls 21a-24a, 21b-24b becoming ink flow passages also serving as ink chambers are formed. After the vapor deposition of an insulating membrane 60, the upper surfaces of the partition walls are masked to perform the vapor deposition of electrodes 20c-24c. An insulating ceramic substrate 3b is bonded to the grooves through an adhesive layer 5 to form the ink flow passages also serving as ink chambers.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a drop-on-demand (DOD) type ink jet head.

0002

[Prior Art] Among the non-impact printers whose market is expanding significantly today, the principle is the simplest.
Inkjet printers are also suitable for color printing. Historically, the continuous injection type appeared first,
The so-called DOD type, in which ink droplets are ejected only when forming dots, has become the mainstream to this day.

[0003] As for the DOD type, the special public interest code Sho 53-12138
Kaiser type disclosed in No.
A typical example of this method is the thermal jet type disclosed in Japanese Patent No. 59914. Of these, the former is difficult to miniaturize, and the latter applies high heat to the ink, causing the ink to burn, each of which has extremely difficult problems.

[0004] A new method for solving the above-mentioned defects at the same time was proposed in Japanese Patent Application Laid-Open No. 63-252750.
It is a shear mode type disclosed in No. In order to facilitate understanding of the present invention, the above-mentioned shear mode type conventional example will be explained in detail. The structure and operating principle are shown in Figure 11. Figure 1
1 is a partial cross-sectional structural diagram showing partition walls 90a to 94a, 90b to 9 on an insulating substrate 1a made of glass or ceramics, etc.
4b etc. are adhered at equal intervals and in parallel by the adhesive layer 8,
A plurality of elongated grooves 90 to 94 serving as ink chambers and ink flow paths are formed. Ink can be supplied from a common ink reservoir to one end of the plurality of grooves, and a nozzle plate having small nozzle holes 90n to 94n is bonded to the other end. Further, the partition wall is bonded to a lid 1b made of glass or ceramics. Here, for example, a piezoelectric material such as PZT (lead zirconate titanate) is used as the partition wall, and before forming the partition wall, it is made in the state of the material in such a way that the material is oriented in opposite directions as shown by arrows 7a and 7b. Align the direction and polarize. Further, electrodes 90c to 94c, etc. are formed on the entire wall surface of the partition wall. Here, for example, if a sufficiently large positive potential is applied to the electrode 92c with respect to the electrodes 91c and 93c, the partition walls 92a, 92b, 93a,
93b causes shear mode deformation as shown by the dotted line in the figure. The cross-sectional area of the groove 92 serving as the ink chamber and ink flow path decreases from the initial state as shown by the dotted line. In other words, if the groove is filled with ink, the pressure of the ink will increase instantaneously due to the volume reduction of the groove, and the ink drop will flow into the nozzle hole 92n.
It pops out more.

[0005] If the interval between the grooves is made sufficiently small, it is easy to downsize to the same level as the thermal jet type, and, like the Kaiser type, there is no problem due to high heat. For example, by setting the groove spacing to 120 microns, a dot density of about 200 dots/inch can be achieved. FIG. 12 is an exploded perspective view of the inkjet head constructed in this way, and FIG.
3 is an external view, which is disclosed in Japanese Patent Application Laid-Open No. 63-252750. Here, 101 is an insulating substrate (corresponding to 1a in FIG. 11), 102 is an elongated groove serving as an ink chamber and ink flow path (corresponding to 90 to 94 in FIG. 11), and 105 is a partition wall made of piezoelectric material (corresponding to 1a in FIG. 11 91a-94
100 is a nozzle plate, 103 is a nozzle hole (corresponds to 90n to 94n in FIG. 11), and 104 is an ink droplet. Further, 8 is an adhesive layer on which an insulating substrate and a piezoelectric material are laminated.

[0006] Here, the partition walls 90a to 94a, 90b
~94b was formed as follows. That is, as shown in FIG. 8, a process of bonding polarized piezoelectric members (PZT sheets) 2a and 2b to upper and lower insulating ceramic substrates 1a and 1b using an adhesive layer 8, respectively, and a process of attaching partition walls using a diamond wheel as shown in FIG. 91a-94a, 91b-94
The process consists of a process of forming grooves leaving the area b, a vapor deposition process of electrodes 90c to 94c by masking as shown in FIG. 10, and a process of forming grooves 90 to 94 in FIG. 11 by bonding both the upper and lower members. , the final cross-sectional structure shown in FIG. 11 is obtained.

[0007]

[Problems to be Solved by the Invention] Electromechanical conversion efficiency can be increased by stacking piezoelectric members so that their polarization directions are symmetrical, but reliability decreases due to the increase in bonded parts. Bonding at relatively high temperatures is desirable to improve bonding reliability. However, since piezoelectric materials with good characteristics have a low temperature (Cucurie point) at which their polarization characteristics deteriorate, reliability must be sacrificed. Furthermore, in order to achieve high printing quality, it is necessary to make the groove pitch fine, but since the area of the adhesive layer cannot be secured in a sufficient amount in terms of strength, there is a limit to how fine the groove pitch can be made. Furthermore, the difficulty of preventing adhesive from spilling out or flowing out increases as the groove pitch becomes finer.
Decrease product yield. The present invention aims to solve the manufacturing problems of such conventional heads and provide an inkjet head with high print quality.

[0008]

[Means for Solving the Problems] In order to solve the above-mentioned problems, a method for manufacturing a shear mode inkjet head according to the present invention includes the steps of laminating and bonding a plurality of piezoelectric members on a substrate via a conductive film; a step of polarizing the piezoelectric member by applying a voltage to the conductive film; a step of forming grooves separated by partition walls in the laminated piezoelectric member; and a step of forming an insulating thin film on the inner surface of the groove and then forming an electrode. and a step of bonding an insulating substrate over the groove to form an ink flow path.

[0009]

[Function] For laminated bonding before polarization, the sintering temperature of PZT must be 1
High-temperature bonding up to 100 degrees is possible, and since polarization occurs after bonding, the bonding results in no deterioration of polarization characteristics.

0010

Embodiments Hereinafter, embodiments of the present invention will be explained based on the drawings. 1 to 5 show a first embodiment of a method for manufacturing a shear mode inkjet head according to the present invention. FIG. 1 is a partial cross-sectional view showing the PZT sheet adhesion process, in which an insulating ceramic substrate 3a, a PZT sheet 4a,
4b is a metallized layer 9a which is a conductive film made of silver paste.
, 9b, 9c, and FIG. 2 is a partial cross-sectional view showing the polarization step, in which the negative electrode of a power source 200 is connected to the metallized layers 9a and 9c, and the positive electrode is connected to the metalized layer 9b, and a predetermined high voltage is applied. The process of applying voltage and polarizing as shown by arrows 201 and 202, FIG. 3 shows the groove 20 that serves as an ink chamber and an ink flow path.
24 and the partition walls 21a to 24a, 21b to 24b, FIG. 4 shows a step of depositing the insulating thin film 60, then masking the top surface of the partition and depositing the electrodes 20c to 24c, and FIG. The process of bonding the ceramic substrate 3b via the adhesive layer 5 is shown. Through the above steps, the ink chamber/ink channel is completed. The assembly form and function of the inkjet head with the nozzle plate, ink inlet, etc. attached are the same as the inkjet head described above as a conventional example, that is, the one shown in FIG.
1a to 24a, 21b to 24b as partition walls 91a to 94a,
91b to 94b, grooves 20 to 24 to grooves 90 to 94, electrodes 20c to 24c to electrodes 90c to 94c, and insulating ceramic substrates 3a and 3b to insulating substrates 1a and 1b for easy analogy. Since it is possible, I will omit the detailed explanation.

FIG. 6 is an explanatory view of a second embodiment of the method for manufacturing a shear mode ink jet head according to the present invention, and shows a partial cross-sectional structure showing the operation status of the print head. When joining the PZT sheets 4a and 4b in Fig. 1, bonding is performed by sandwiching silicon nitride, an insulating ceramic with low specific gravity and stable, and groove processing, assembly, etc. are performed in the same manner as in the first embodiment. . The upper stage 34b of the partition wall made of polarized PZT, the middle stage 33c of the partition wall made of silicon nitride, the lower stage 34a of the partition wall made of polarized PZT, and the insulating ceramic substrate 33a are connected to the conductive films 39a, 3
They are joined by 9b and 39c. A conductive film 39d, which becomes an electrode during polarization, is metallized and bonded to the upper surface of the upper stage 34b of the partition wall. After forming the insulating layer 50 and the electrodes 40a to 44a in this order, they are bonded to the insulating ceramic substrate 33b using adhesive layers 80 to 83 to form the grooves 40 to 44. By providing the nozzles 40n to 44n, ink can be ejected in the same manner as the inkjet head described above. The inkjet head constructed by the manufacturing method of this embodiment differs from the first embodiment in that the operation of the partition walls in the shear mode can be made to perform the displacement as shown by the dotted line, and the portion of maximum displacement is made of silicon nitride, which has a low specific gravity. Since the structure is configured as follows, the discharge efficiency becomes more advantageous.

FIG. 7 is a partial cross-sectional structural diagram showing the operation status of a print head according to a third embodiment of the method for manufacturing a shear mode type ink jet head according to the present invention, in which the thickness of the PZT sheet 4a of FIG. 1 is increased. , omitting the insulating ceramic substrate 3a, using a silver paste that does not burn the conductive films 9a and 9c for polarization, and wiping them with a solvent after polarization.
This was achieved through such efforts as A conductive film 69b formed by baking and bonding two PZT sheets with silver paste, and a PZT70b forming part of a partition wall by baking bonding → polarization → groove processing.
~73b, PZT sheet 64a having sufficient thickness to form the partition wall and the bottom of the groove, insulating layer 80, electrodes 70c~74c
, an insulating ceramic substrate 63a bonded with an adhesive layer 65,
It is composed of grooves 70 to 74 that serve as ink flow paths. Other structures and operations as an inkjet head are the same as in the previous embodiments.

[0013]

As described above, according to the structure of the present invention, the reliability of adhesion, which was one of the important issues in shear mode inkjet heads, can be significantly improved. This enables high-density dot printing, and as a result, the printing quality of the printer can be greatly improved.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view showing a bonding process of a first embodiment of an inkjet head of the present invention.

FIG. 2 is a partial cross-sectional view showing the polarization process of the first embodiment of the inkjet head of the present invention.

FIG. 3 is a partial cross-sectional view showing the groove forming process of the first embodiment of the inkjet head of the present invention.

FIG. 4 is a partial cross-sectional view showing the electrode forming process of the first embodiment of the inkjet head of the present invention.

FIG. 5 is a partial cross-sectional view showing the insulating substrate bonding process of the first embodiment of the inkjet head of the present invention.

FIG. 6 is a partial cross-sectional view showing a second embodiment of the inkjet head of the present invention.

FIG. 7 is a partial cross-sectional view showing a third embodiment of the inkjet head of the present invention.

FIG. 8 is a partial cross-sectional view showing a PZT sheet adhesion process in a conventional manufacturing method.

FIG. 9 is a partial cross-sectional view showing a conventional groove machining process.

FIG. 10 is a partial cross-sectional view showing a conventional electrode film formation process.

FIG. 11 is a partial cross-sectional structural diagram showing an inkjet head manufactured by a conventional manufacturing method.

12 is an exploded perspective view of the inkjet head of FIG. 11. FIG.

13 is an external view of the inkjet head shown in FIG. 11. FIG.

[Explanation of symbols]

3a Insulated ceramic substrate 3b Insulated ceramic substrate 4a PZT sheet 4b PZT sheet 5 Adhesive layer 9a Conductive film (metallized layer) 9b Conductive film (metallized layer) 9c Conductive film (metallized layer) 20 groove 21 Groove 22 Groove 23 Groove 24 groove 21a Partition wall 22a Partition wall 23a Partition wall 24a Partition wall 21b Partition wall 22b Partition wall 23b Partition wall 24b Partition wall 20c electrode 21c Electrode 22c Electrode 23c Electrode 24c Electrode 40n nozzle hole 41n nozzle hole 42n nozzle hole 43n nozzle hole 44n nozzle hole 60 Insulating layer

Claims (3)

[Claims] 1. A step of laminating and bonding a plurality of piezoelectric members on a substrate via a conductive film, a step of polarizing the piezoelectric member by applying a voltage to the conductive film, and a step of attaching a partition wall to the laminated piezoelectric member. a step of forming an electrode after forming an insulating thin film on the inner surface of the groove; and a step of bonding an insulating substrate over the groove to form an ink flow path. A method for manufacturing a shear mode inkjet head, characterized by: 2. The method of manufacturing an ink jet head according to claim 1, wherein the piezoelectric members are laminated and bonded with an insulating ceramic interposed between them. 3. The inkjet according to claim 1, wherein a piezoelectric member is used as the substrate, and after polarization, the conductive film on the outer surface of the laminated piezoelectric member is wiped off with a solvent, and grooves are also formed on the substrate. Head manufacturing method.