JPH09174830A - Ink jet recording head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the image quality when ink droplets are simultaneously discharged from a plurality of adjacent nozzle holes. SOLUTION: The ink jet recording head comprises a piezoelectric element group 51 made of a plurality of piezoelectric elements 50, a diaphragm 12 having a plurality of vibrating protrusions 10 corresponding to the elements 50 and transmitting the vibrations generated from the elements 50 via the protrusions 10, and a base plate 16 having a plurality of nozzle holes 14 corresponding to the elements 50 and discharging ink droplets from the holes 14 in response to the vibrations of the elements 50 transmitted via the protrusions 10. The protrusions 10 are disposed in a zigzag state to be entirely disposed in one direction A and the adjacent protrusions 10 are disposed obliquely with respect to the one direction A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording head in an ink jet printer, and more particularly, to an ink jet recording head for discharging ink by a piezoelectric element.

[0002]

2. Description of the Related Art FIGS. 7 to 9 show a conventional ink jet recording head, FIG. 7 is a partially cutaway perspective view, and FIG.
8 is a vertical sectional view taken along the line VIII-VIII in FIG. 7, and FIG. 9 is a bottom view of the diaphragm and the vibrating convex portion with the piezoelectric element removed, as seen from an arrow IX in FIG. Hereinafter, description will be given with reference to these drawings.

The conventional ink jet recording head includes a piezoelectric element group 51 including a plurality of piezoelectric elements 50 and a piezoelectric element 5.
A vibration plate 54 having a plurality of vibration convex portions 52 corresponding to 0 and transmitting the vibration generated in the piezoelectric element 50 via the vibration convex portions 52, and a plurality of nozzle holes 56 corresponding to the piezoelectric element 50 and vibrating. A substrate 58 that ejects the ink droplets Id from each of the nozzle holes 56 according to the vibration of the piezoelectric element 50 transmitted via the convex portion 52.
The vibration convex portion 52 is entirely arranged in one direction A,
In addition, adjacent ones are also arranged in one direction A. The substrate 58 is the nozzle plate 6 having a plurality of nozzle holes 56.
0, and a flow path forming member 64 that forms a flow path 62 that communicates with the nozzle hole 56.

When a voltage is applied to the piezoelectric element 50, the tip surface of the piezoelectric element 50 is displaced in the thickness direction of the diaphragm 54.
This displacement changes the volume in the flow path 62 via the vibration protrusion 52. Then, the pressure in the flow path 62 increases, so that the ink droplet I is ejected from the nozzle hole 56 corresponding to the flow path 62.
d is ejected.

[0005]

In the conventional ink jet recording head, the vibration convex portions 52 are entirely arranged in one direction A, and adjacent ones are also arranged in one direction A. With such a structure, for example, when the ink droplets Id are simultaneously ejected from the three adjacent nozzle holes 56,
The flight speed of the ink droplet Id ejected from the central nozzle hole 56 is the same as that of the ink droplet I ejected from the nozzle holes 56 on both sides.
It is reduced compared to the flight speed of d. That is, since the flight speeds of the ink droplets Id simultaneously ejected from the three nozzles 56 are different between the center and both sides thereof, the landing positions of the ink droplets Id on the printing paper are deviated and the image quality is deteriorated.

[0006]

SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide an ink jet recording head capable of improving image quality when ink droplets are simultaneously ejected from a plurality of adjacent nozzle holes.

[0007]

Means for Solving the Problems The inventors of the present invention have made the following findings as a result of repeated studies on the cause of the difference in the flight speed of ink droplets when ink droplets are simultaneously ejected from a plurality of adjacent nozzle holes. It was That is, the reason is that when the ink droplets Id are simultaneously ejected from the three nozzle holes 56, the deformation of the central flow passage 62 is maximized due to the insufficient rigidity of the substrate 58, so that the flow of the central flow passage 62 is increased. This is because the volume reduction rate in the passage is lower than that of the flow passages 62 on both sides. The present invention has been made based on this finding.

An ink jet recording head according to the present invention has a piezoelectric element group composed of a plurality of piezoelectric elements and a plurality of vibrating convex portions corresponding to the plurality of piezoelectric elements, and vibrates the vibration generated by the piezoelectric elements. And a plurality of nozzle holes corresponding to the plurality of piezoelectric elements and an ink droplet from each of the nozzle holes according to the vibration of the piezoelectric element transmitted via the vibration convex portion. And a substrate for ejecting. The plurality of vibration convex portions are arranged in one direction as a whole, and adjacent ones are arranged obliquely with respect to the one direction. Further, the plurality of vibration convex portions may be arranged in a zigzag manner, and at least three pieces arranged in the diagonal direction as one unit are arranged continuously in the one direction. May be

When a voltage is applied to the piezoelectric element, the piezoelectric element is displaced. This displacement is transmitted to the substrate via the vibration protrusion corresponding to the piezoelectric element. Then, ink droplets are ejected from the nozzle holes corresponding to the vibrating protrusions. When a voltage is applied to a plurality of adjacent piezoelectric elements at the same time, these displacements are simultaneously transmitted to a plurality of adjacent vibrating convex portions. At this time, for example, the vibration convex portions arranged in a staggered pattern according to the present invention are less likely to be affected by the displacement of the adjacent vibration convex portions. Because
This is because the vibrating protrusions of the present invention can secure a sufficient distance between adjacent vibrating protrusions as compared with the conventional vibrating protrusions that are linearly arranged.

[0010]

1 to 3 show a first embodiment of an ink jet recording head according to the present invention, FIG. 1 is a partially cutaway perspective view, and FIG. 2 is a II-II line of FIG. FIG. 3 is a vertical cross-sectional view, and FIG. 3 is a bottom view of the vibrating plate and the vibrating convex portion with the piezoelectric element removed, as seen from the arrow III in FIG. Hereinafter, description will be given with reference to these drawings. However, the same portions as those in FIGS. 7 to 9 are denoted by the same reference numerals, and redundant description will be omitted.

The ink jet recording head of this embodiment has a piezoelectric element group 51 composed of a plurality of piezoelectric elements 50 and a plurality of vibrating convex portions 10 corresponding to the piezoelectric elements 50, and vibrates the vibration generated by the piezoelectric element 50. The vibrating plate 12 transmitted through the portion 10 and the plurality of nozzle holes 14 corresponding to the piezoelectric elements 50 are provided, and the nozzle holes 14 are transmitted from the respective nozzle holes 14 according to the vibration of the piezoelectric element 50 transmitted through the vibrating convex portion 10. And a substrate 16 for ejecting the ink droplets Id. The vibrating protrusions 10 are arranged in a zigzag pattern, so that the whole is arranged in one direction A, and adjacent ones are arranged obliquely with respect to the one direction A. The substrate 16 is composed of a nozzle plate 18 having a plurality of nozzle holes 14 formed therein, and a flow path forming member 22 forming a flow path 20 communicating with the nozzle holes 14.

The piezoelectric element 50 is made of, for example, ceramics, is formed with slits, and is formed in a comb shape.
Further, the piezoelectric element 50 is provided with an individual electrode and a common electrode (not shown) so that a voltage can be selectively applied from the piezoelectric element group 51. The vibration protrusion 10
For example, it is formed by processing the vibrating plate 12 by electrohoming, etching or the like, and is bonded to the tip surface of the piezoelectric element 50. The flow path forming member 22 is, for example, a dry film.

The nozzle holes 14 and the flow paths 20 are also arranged in a zigzag pattern in accordance with the vibration convex portions 10 arranged in a zigzag pattern. This is because the vibrating convex portion 10, the nozzle hole 14 and the flow path 20.
And the same positional relationship with
This is because the ejection characteristics of d are all the same. However, if the recording image quality is not affected, it is not necessary to arrange the nozzle holes 14 and the flow paths 20 in a zigzag pattern in accordance with the vibration convex portions 10.

When a voltage is applied to the piezoelectric element 50, the piezoelectric element 50 is displaced. This displacement is transmitted to the flow path 20 corresponding to the vibration protrusion 10 via the vibration protrusion 10 corresponding to the piezoelectric element 50. Then, the ink droplet Id is ejected from the nozzle hole 14 corresponding to the flow path 20. Further, when a voltage is applied to a plurality of adjacent piezoelectric elements 50 at the same time, these displacements are simultaneously transmitted to the plurality of adjacent vibrating convex portions 10. At this time, the vibration protrusions 10 arranged in a staggered pattern are less likely to be affected by the displacement of the adjacent vibration protrusions 10. This is because the vibration protrusions 10 are adjacent to the vibration protrusions 1 as compared with the conventional vibration protrusions 52 (FIGS. 7 to 9) arranged in a straight line.
This is because the distance between 0s can be sufficiently secured. Therefore, the ink droplets I are simultaneously ejected from the plurality of adjacent nozzle holes 14.
Even when ejecting d, the image quality does not deteriorate.

FIGS. 4 to 6 show second to fourth embodiments of the ink jet recording head according to the present invention. As in FIG. 3, the piezoelectric element is removed and the vibration plate and the vibration convex portion are viewed from the bottom. Is. Hereinafter, description will be given with reference to these drawings.

In the second embodiment shown in FIG. 4, the vibration convex portion 3
Zeros are arranged in a staggered manner on the diaphragm 32. Adjacent vibration protrusions 32 have portions that overlap in one direction A.

In the third embodiment shown in FIG. 5, the three vibrating convex portions 34 arranged in the diagonal direction B intersecting with the one direction A are set as one unit and continuously arranged on the vibrating plate 36 in the one direction A. It is installed in.

In the fourth embodiment shown in FIG. 6, a thick portion 40 is provided on the diaphragm 12 of the first embodiment shown in FIG. 3 so as to surround the vibrating convex portion 10. The thick portion 40 has a thickness sufficient to increase the rigidity of the diaphragm 12.
Further, it is preferable in view of manufacturing cost that the thick portion 40 is formed on the vibration plate 12 at the same time as the vibration convex portion 10 by etching or the like.

[0019]

According to the ink jet recording head of the present invention, a plurality of vibrating convex portions are arranged in one direction as a whole, and the vibrating convex portions adjacent to each other are arranged obliquely with respect to the one direction. By doing so, the distance between the adjacent vibration convex portions can be sufficiently secured as compared with the conventional vibration convex portions arranged in a straight line, so that the influence of the displacement of the adjacent vibration convex portions can be eliminated. Therefore, the image quality can be improved when ink droplets are simultaneously ejected from a plurality of adjacent nozzle holes. Further, even if the distance between the adjacent vibrating convex portions is shortened, the image quality equivalent to or better than the conventional one can be obtained, so that the nozzle holes can be arranged at a high density.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view showing a first embodiment of an inkjet recording head according to the present invention.

FIG. 2 is a vertical sectional view taken along line II-II of FIG.

3 is a bottom view of the vibrating plate from which the piezoelectric element is removed and the vibrating convex portion as seen from an arrow III in FIG.

FIG. 4 is a bottom view showing the second embodiment of the ink jet recording head according to the present invention.

FIG. 5 is a bottom view showing the third embodiment of the inkjet recording head according to the present invention.

FIG. 6 is a bottom view showing the fourth embodiment of the inkjet recording head according to the present invention.

FIG. 7 is a partially cutaway perspective view showing a conventional inkjet recording head.

8 is a vertical cross-sectional view taken along the line VIII-VIII of FIG.

9 is a bottom view of the vibrating plate from which the piezoelectric element is removed and the vibrating convex portion as seen from an arrow IX in FIG.

[Explanation of symbols]

 10, 30, 34 Vibration convex portion 12, 32, 36 Vibration plate 14 Nozzle hole 16 Substrate 50 Piezoelectric element 51 Piezoelectric element group Id Ink droplet A One direction

Claims (3)

[Claims] 1. A piezoelectric element group comprising a plurality of piezoelectric elements,
A vibrating plate having a plurality of vibration convex portions corresponding to the plurality of piezoelectric elements and transmitting vibration generated in the piezoelectric elements via the vibration convex portions, and a plurality of nozzle holes corresponding to the plurality of piezoelectric elements. With an inkjet recording head including a substrate that ejects ink droplets from each of the nozzle holes according to the vibration of the piezoelectric element transmitted via the vibration convex portion, the plurality of vibration convex portions are An inkjet recording head, wherein the inkjet recording heads are arranged in one direction, and adjacent ones are arranged obliquely with respect to the one direction. 2. The ink jet recording head, wherein the plurality of vibration convex portions are arranged in a staggered pattern. 3. The ink jet recording head according to claim 1, wherein at least three of the plurality of vibration convex portions are arranged continuously in the one direction, with at least three of the vibration convex portions being arranged as one unit.