JPH05212861A - Ink jet printing head - Google Patents

Abstract

PURPOSE:To provide an inexpensive ink jet printing head enhanced in yield. CONSTITUTION:The end surface of a piezoelectric element 6 is cut or ground and ridges 16,17,18,19 are chamferred by cutting or grinding. Next, the surface of the piezoelectric element 6 is metallized by sputtering, vapor deposition or plating so as not to cover the chamferred ridges 16,19 to form surface electrodes 7,8. Especially, internal electrode groups 9a,9b are respectively exposed to end surfaces 15a,15b to be connected to the surface electrodes 7,8. Thereafter, the piezoelectric element 6 is bonded to a fixing stand 10 and also bonded to the end surface 15a and an elastomer 4 by an adhesive 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a print head used in an ink jet printer.

[0002]

2. Description of the Related Art A conventional ink jet print head is
As shown in Japanese Examined Patent Publication No. 60-8953, a plurality of nozzle openings are formed on the wall surface of a container that constitutes an ink tank, and piezoelectric elements are arranged so that the expansion and contraction directions are aligned so as to face each nozzle opening. Is configured. This print head applies a drive signal to a piezoelectric element to expand and contract the piezoelectric element, and the dynamic pressure of ink generated at this time causes ink droplets to be ejected from nozzle openings to form dots on printing paper.

In a print head of this type,
It is desirable that droplet formation efficiency and flight force are large. However, since the unit length of the piezoelectric element and the expansion / contraction rate per unit voltage are extremely small, it is necessary to apply a high voltage in order to obtain the flying force required for printing, which complicates the drive circuit and electrical insulation measures. The problem is that

In order to solve such a problem, Japanese Unexamined Patent Publication No.
As disclosed in JP-A-3-295269, there has been proposed a piezoelectric element for an inkjet print head in which electrodes and piezoelectric materials are alternately laminated in a sandwich form and simultaneously sintered. With this piezoelectric element, the distance between the electrodes can be made as small as possible, so that there is an effect that the voltage of the drive signal can be lowered.

Since the end face of such a piezoelectric element is flat, when the surface electrode connected to the internal electrode extends over two planes, electrode breakage easily occurs at the ridge portion. Therefore, in the above-mentioned JP-A-63-295269, a method of chamfering the ridge of the end face on the side connected to the internal electrode is used.

[0006]

However, Japanese Patent Application Laid-Open No. 63-295269 does not describe a concrete example of an ink jet print head using this piezoelectric element. Further, in JP-A-63-295269, only one edge of the surface connected to the internal electrode is chamfered. Therefore, when a print head is constructed by using this piezoelectric element, the end surface of the piezoelectric element and other members, for example, When using an adhesive to bond to the container that constitutes the ink tank, the adhesive will protrude from the ridges that are not chamfered, and the adhesive that sticks out will adhere to the container that constitutes the ink tank and reduce the dynamic pressure applied to the ink. , Significantly deteriorates the ink flight characteristics,
This was a factor that deteriorated the print quality.

[0007] Further, a ridge that is not chamfered is liable to be chipped, and a small amount of powder produced by the chipping is processed with high precision.
In an ink jet type print head which requires assembly and joining, deterioration of flight characteristics and reduction of fractionation are likely to occur as in the case where dust and dust are mixed.

The present invention has been made in view of such problems, and an object thereof is to realize stable flying characteristics, realize high printing quality, and improve the fractionation at low cost. To provide an ink jet type print head.

[0009]

In order to solve the above problems, in an ink jet type print head according to the present invention, a piezoelectric element is arranged corresponding to a nozzle opening, and ink is ejected from the nozzle by a drive signal to the piezoelectric element. It is an ink jet type print head adapted to be discharged to the outside from an opening, wherein the piezoelectric element is a prism element, and the piezoelectric element is formed by chamfering opposite edges of arbitrary end faces at one location or at a plurality of locations. Is characterized by.

Further, the piezoelectric element is characterized in that the ridge of an end face joined to a structural member constituting the print head is chamfered.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view of an embodiment of an ink jet type print head according to the present invention. 1 is the nozzle plate,
2 is a nozzle, 3 is an ink chamber, 4 is an elastic body that is a structural member, 5 is an adhesive, 6 is a piezoelectric element, 7 and 8 are surface electrodes, and 9 is a surface electrode.
Reference numerals a and 9b are internal electrode groups, 10 is a fixing base, 11 is a lead wire of the front surface electrode 7, 12 is a lead wire of the front surface electrode 8, 13 is a head frame, and 14 is a thin metal plate.

2 to 5 are piezoelectric elements 6 of the embodiment of FIG.
FIG. 4 is a diagram showing a process until the is fixed to the fixing base 10,
Description will be added based on the drawings. FIG. 2 shows the end face 1 of the piezoelectric element 6.
It is the figure which showed the state which 5a was cut or grind | polished, and the ridges 16, 17, 18, 19 are acute angles. Next, the edges 16, 17, 18, 19 are cut or chamfered by polishing (FIG. 3).
The surface of the piezoelectric element 6 is metallized by sputtering, vapor deposition, plating or the like so as not to cover 19 and the surface electrodes 7 and 8 are formed. (Fig. 4) Especially the end faces 15a, 15
Since the internal electrode groups 9a and 9b are exposed at b, respectively, the surface electrodes 7 and 8 can be metalized to conduct electricity. After that, the fixing table 10 is joined. (FIG. 5) As shown in FIG. 1, the piezoelectric element 6 bonded to the fixing base 10 is bonded to the end surface 15a and the elastic body 4 with the adhesive 5, as shown in FIG.
In order to make this joined state easier to understand, FIG.
The enlarged joint portion of the piezoelectric element 6 and the elastic body 4 is shown in FIG. When the end face 15a of the piezoelectric element 6 and the joint portion of the elastic body 4 are joined by the adhesive 5, the meniscus 20 is formed at the chamfered ridge 17 or at the chamfered ridge 16 (not shown in FIG. 6). Thus, the adhesive 5 is prevented from protruding.

In the print head of FIG. 1 thus constructed, the piezoelectric element 6 shrinks when a voltage is applied between the surface electrodes 7 and 8 by a driving means (not shown). The expansion and contraction of the piezoelectric element 6 bends the metal thin film 14 through the elastic plate 4 and expands the ink chamber 3. Then the surface electrode 7,
By reducing the voltage across 8, the piezoelectric element 6 is expanded to press the ink in the ink chamber 3, and the pressed ink is discharged from the nozzle 1
As a result, they fly as ink drops and are printed on the image receiving paper facing the nozzle plate 2 to form characters, figures and the like.

In this embodiment, an epoxy type adhesive is used as the adhesive 5, and the chamfering amount for preventing the protrusion is 5 to 40 μm, and the meniscus is formed to obtain a sufficient effect. When using other adhesives, the optimum amount varies depending on its viscosity and surface tension.

Further, in this embodiment, the chamfering was more effective in the case of the low-viscosity adhesive than in the case of the high-viscosity adhesive, since the amount of the adhesive protruding was reduced.

Further, in this embodiment, the chamfering is performed by the edge 1 in FIG.
6, 17, 18 and 19 have been described, and the ridges 16 and 17 are effective for preventing the adhesive from squeezing out. However, by chamfering the ridges 18 and 19, the formation of the surface electrodes 7 and 8 and the piezoelectric element. In the joining of 6 and the fixing base 10 and the joining of the piezoelectric element 6 and the elastic plate 4, chipping of the ridge during the work was significantly reduced. Further, in this embodiment, the end surface 15a of the piezoelectric element 6 is
The ridges other than the ridges 16 and 17 were sufficiently effective in preventing the adhesive from squeezing out without chamfering the ridges. The effect can be obtained by chamfering other ridges when the amount of displacement is extremely small compared to the present embodiment). Further, by chamfering the ridges other than those described above, the chipping of the ridge portion was further reduced.

Further, the print head of this embodiment has been described as a print head having one nozzle, but actually, a plurality of print heads shown in FIG. 1 are arranged in parallel to form a print head having a plurality of nozzles. .. Specifically, a plurality of the piezoelectric elements 6 shown in FIG. 4 are bonded to the fixed base 10 shown in FIG. 5 at regular intervals so as not to contact the adjacent piezoelectric elements, and the piezoelectric elements 6 are arranged in the same number as the piezoelectric elements and at the same intervals. The elastic plate 4 (however, the elastic plate 4 has the corresponding nozzle 1 and ink chamber 3 respectively) is joined.

A print head having a plurality of nozzles can also be constructed by making a plurality of cuts in one piezoelectric element. 7 to 11 are diagrams showing the process, and description will be added based on the diagrams.

FIG. 7 is a view showing a state where the end face 103a of the piezoelectric element 101 is cut or polished, and the ridge 10
4, 105, 106 and 107 are acute angles. Next, the edges 104, 105, 106, 107 are chamfered by cutting or polishing. (FIG. 8) Further, the surface of the piezoelectric element 101 is metallized by sputtering, vapor deposition, plating or the like so as not to cover the chamfered edges 104 and 107, and surface electrodes 108 and 109 are formed.
(FIG. 9) In particular, the internal electrode groups 102a and 102b are exposed on the end faces 103a and 103b, respectively, and metalization of the surface electrodes 108 and 109 enables electrical conduction.
Then, it is joined to the fixed base 110. (FIG. 10) The piezoelectric element 101 bonded to the fixed base 110 is cut by a peripheral edge of fixed abrasive grains, a cutting method using free abrasive grains, or the like. (FIG. 11) The number of the cut piezoelectric elements 101 is equal to the number of the piezoelectric elements divided by the cut, and the elastic plates 4 are arranged side by side at the same intervals as shown in FIG. 1 and the ink chamber 3) are bonded to each other with an adhesive. Thus, also in the print head having a plurality of nozzles, the meniscus of the adhesive is formed by the chamfered edge of the piezoelectric element, and the protrusion of the adhesive is prevented.

FIG. 12 is a sectional view showing another embodiment of the ink jet type print head of the present invention. 201 is a nozzle plate, 202 is a nozzle, 203 is an ink chamber,
Reference numeral 204 is an elastic body that is a structural member, 205 is an adhesive, and 20
6 is a piezoelectric element, 207 and 208 are surface electrodes, 209a,
209b is an internal electrode group, 210 is a fixed base, 211 is a head frame, 212 is a thin metal plate, 213 is a surface electrode 20.
7 is a lead wire, and 214 is a lead wire for the surface electrode 208. Since the method of constructing the print head of FIG. 12 is the same as that of the print head described above, a detailed description thereof will be omitted here. However, surface electrodes are particularly formed on the end surface of the piezoelectric element 206 bonded to the elastic plate 204 and the end surface facing the end surface. do not have to.
In the print head of FIG. 12, when a voltage is applied between the surface electrodes 207 and 108 by a driving unit (not shown), the piezoelectric element 206 expands, presses the ink in the ink chamber 203, and the pressed ink ejects the nozzle 201. As a result, the ink droplets fly and are printed on the image receiving paper facing the nozzle plate 202 to form characters, figures, and the like. Even in such a head, chipping can be prevented by chamfering each ridge. Further, by chamfering the ridges of the end faces of the piezoelectric element 206 bonded to the elastic plate 204 and the adhesive 205, a meniscus of the adhesive 205 is formed, and the adhesive 2
Prevent the protrusion of 05. Furthermore, by chamfering the ridge of the end face of the piezoelectric element 206 joined to the fixing plate 210 and the adhesive agent 205 to prevent the adhesive agent 205 from protruding, the lead wires 213 and 214 of the surface electrodes 207 and 208.
Poor connection has been reduced.

Although the embodiment of the ink jet type print head of the present invention has been described above, the piezoelectric element used in the embodiment is not particularly limited to the laminated vibrator, and the same effect can be obtained with a single-layer vibrator. It was

[0022]

According to the present invention, by chamfering the edges of the piezoelectric element, the piezoelectric element is prevented from being chipped, and in the process of assembling the print head, the piezoelectric element is prevented from being mixed or the flight characteristic is not defective due to the chipping. In addition, a low-cost inkjet type print head with high yield is provided. Further, by chamfering the ridge of the adhesive surface with each part, the flying characteristic defect due to the protrusion of the adhesive is eliminated, and an ink jet type print head with high printing quality is provided. Further, it is possible to provide a low-cost inkjet print head with high yield without losing the effect of preventing disconnection of the surface electrode at the ridge portion as shown in the conventional example. Further, by using the present invention in a print head having a plurality of nozzles, there is a great effect in improving fractionation, and further, variation in flight characteristics of ink droplets ejected from each nozzle is reduced and high print quality is achieved. To provide a print head having

[Brief description of drawings]

FIG. 1 is a sectional view showing the structure of an embodiment of an ink jet print head of the present invention.

FIG. 2 is a diagram showing a manufacturing process of the inkjet print head of the present invention.

FIG. 3 is a diagram showing a manufacturing process of the ink jet print head of the present invention.

FIG. 4 is a diagram showing a manufacturing process of the inkjet print head of the present invention.

FIG. 5 is a diagram showing a manufacturing process of the inkjet print head of the present invention.

FIG. 6 is an enlarged view of an adhesive portion of the inkjet print head of the present invention.

FIG. 7 is a diagram showing a manufacturing process of an ink jet type print head having a plurality of nozzles of the present invention.

FIG. 8 is a diagram showing a manufacturing process of an ink jet type print head having a plurality of nozzles of the present invention.

FIG. 9 is a diagram showing a manufacturing process of an ink jet type print head having a plurality of nozzles of the present invention.

FIG. 10 is a diagram showing a manufacturing process of an inkjet printhead having a plurality of nozzles according to the present invention.

FIG. 11 is a diagram showing a manufacturing process of an inkjet printhead having a plurality of nozzles according to the present invention.

FIG. 12 is a cross-sectional view showing the structure of another embodiment of the ink jet print head of the present invention.

[Explanation of symbols]

 1 Nozzle Plate 2 Nozzle 3 Ink Chamber 4 Elastic Plate 5 Adhesive 6 Piezoelectric Element 7 Surface Electrode 8 Surface Electrode 10 Fixing Stand 16-19 Edge

Claims (2)

[Claims] 1. An ink jet print head in which a piezoelectric element is arranged corresponding to a nozzle opening, and ink is discharged from the nozzle opening to the outside by a drive signal to the piezoelectric element, wherein the piezoelectric element has a prismatic shape. None, an ink jet type print head, characterized in that it is a piezoelectric element having chamfered ridges at opposite ends of an arbitrary end face at one location or at a plurality of locations. 2. The ink jet print head according to claim 1, wherein the ink jet print head is a piezoelectric element having a chamfered ridge on an end face to be joined to a structural member constituting the print head.