JPH09309204A - Ink jet recording head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve the stabilized shape and scattering of ink by providing a section for attenuating the vibration transmitted from a piezoelectric actuator to an ink nozzle. SOLUTION: In an ink jet recording head provided with a nozzle plate 30 having an ink cavity 14 for storing ink 40 and an ink nozzle 22 for jetting the ink from the ink cavity and a piezoelectric actuator 24 for transmitting the vibration to the ink and jetting the ink in the ink cavity from the ink nozzle based on the vibration of the piezoelectric actuator, a channel 28 for attenuating the vibration transmitted from the piezoelectric actuator to the ink nozzle between the piezoelectric actuator and the ink nozzle is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording head used in an ink jet recording apparatus for ejecting ink.

[0002]

2. Description of the Related Art Conventionally, an ink cavity for containing ink, a nozzle plate having ink nozzles for ejecting ink from the ink cavity, and a piezoelectric actuator for propagating vibration to the ink are provided. There is known an inkjet recording head that ejects ink in an ink cavity from an ink nozzle based on the vibration of the ink. An inkjet recording head using such a piezoelectric actuator has been proposed which ejects ink in a direction perpendicular to the vibration direction of the piezoelectric actuator. Such an arrangement has an advantage over the one in which ink is ejected in the vibration direction of the piezoelectric actuator, in that the nozzles can be arranged at a high density even when the piezoelectric actuator is elongated and the contact area with the ink is elongated. In the above ink jet recording head, an ink cavity is formed by a piezoelectric member provided on a substrate and a top plate having a groove, and a nozzle plate having ink nozzles is attached and fixed on the front surface of the ink cavity. There is.

[0003]

However, in the above-mentioned ink jet recording head, although the end portion of the piezoelectric member is not polarized or the voltage is not applied, the nozzle plate is prevented from vibrating, but the nozzle plate is not vibrated. The vibration of the piezoelectric actuator propagates through this non-vibration portion, the shape of the nozzle plate is slightly deformed, and the ink ejection direction changes, resulting in an unstable ink droplet diameter and ejection direction. It was.

[0004]

SUMMARY OF THE INVENTION Therefore, the present invention has been made to solve the above-mentioned problems, and includes an ink cavity for containing ink, a piezoelectric member for transmitting vibration to the ink in the ink cavity, and An ink ejection member having an ink ejection port for ejecting ink in a direction perpendicular to the vibration direction of the piezoelectric member is provided, and a shock absorbing portion for absorbing vibration is provided between the ink ejection member and the piezoelectric member. It has a feature. The buffer section may be an empty room, or the empty room may be filled with a filler.

[0005]

In the above ink jet recording head, the vibration propagating from the piezoelectric actuator toward the ink ejecting member is attenuated by the buffer portion, and the propagation of the vibration to the ink ejecting member is greatly reduced. Therefore, deformation of the nozzle plate is prevented, the ink ejection direction is stable, and ink droplets of a constant size can be stably ejected in a constant direction.

[0006]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows an inkjet recording head 10 which is an embodiment of the present invention. The recording head 10 includes a rectangular plate-shaped top plate 12. On the bottom of the top plate 12, a plurality of grooves (ink cavities) 14 filled with ink to be ejected are provided at equal intervals. A partition 16 is attached to the bottom of the top plate 12, and the bottom opening of the ink cavity 14 is located at the partition 1.
6 is covered. Below the partition wall 16 is provided a piezoelectric vibrating member 18 obtained by processing a plate material made of a piezoelectric material into a comb shape. The piezoelectric vibrating member 18 is fixed on a rectangular plate-shaped substrate 20 made of a non-piezoelectric material.

As shown in FIG. 2, the piezoelectric vibrating member 18 has support portions 22 for supporting the top plate 12 at both ends thereof, and the comb-shaped portions formed between the support portions 22 are respectively formed. The piezoelectric actuators 24 and the partition walls 26 that face the ink cavities 14 are alternately provided. The width of the piezoelectric actuator 24 is equal to that of the ink cavity 1.
The width is smaller than the width of No. 4, and as shown in FIG. 1, a buffer portion or groove 2 extending in the width direction (that is, the left-right direction in FIG. 2) is provided on the upper portion of the portion spaced from the tip portion by a predetermined distance.
8 are formed. Electrodes are provided on the upper surface and the lower surface of the piezoelectric actuator 24 from the groove 28 toward the rear end (right side in FIG. 1), and a predetermined range from the groove 28 toward the rear end is polarized. As a result, when a voltage is applied between the electrodes, the polarized portion of the piezoelectric actuator 24 is deformed, and, for example, as shown by the dotted line in FIG.
Transform.

A nozzle plate 30 is provided at the tip (left side in FIG. 1) of the recording head 10 so as to close the tip opening of the ink cavity 14. Nozzle plate 3
At 0, an ink nozzle 32 facing each ink cavity 14 is formed. An ink tank 34 is arranged at the rear of the recording head 10, an ink chamber 36 in the ink tank 34 is connected to the ink cavity 14, and the ink 40 in the ink tank 34 corresponds to each ink cavity 1
4.

In the ink jet recording head 10 having the above structure, when a signal voltage is applied between the electrodes facing each other based on print information, the piezoelectric actuator 24 is deformed, that is, vibrates vertically in FIG. Further, following the deformation of the piezoelectric actuator 24, the partition wall 16 in contact therewith
Is deformed as shown by the dotted line in FIG. 1, for example. As a result, the ink 40 in the ink cavity 14 is pressurized and ejected from the ink nozzle 32 in the left direction of FIG. 1, that is, in the direction perpendicular to the vibration direction of the piezoelectric actuator 24. When the signal voltage is turned off, the piezoelectric actuator 24 returns to the original state. As a result, the partition 16 also returns to the original state. As a result, a negative pressure is generated in the ink cavity 14, and the ink 4 flows from the ink chamber 36 to the ink cavity 14.
0 is replenished.

As described above, the deformation of the piezoelectric actuator 24 is transmitted to the ink 40 through the partition wall 16. However, the presence of the buffer portion, that is, the groove 28 causes the piezoelectric actuator 2 to move.
The vibration of No. 4 is prevented from propagating to the nozzle plate 30. Therefore, the size and flight direction of the ink droplets ejected from the ink nozzle 32 are always constant. The groove 28
It is sufficient that the length in the ink ejection direction is about 0.1 to 2 mm.

Further, in the above-described embodiment, the groove 28 which is the buffer portion does not completely divide the piezoelectric actuator 24 before and after the groove 28, but as shown in FIG. 3, the groove 28 does not divide the piezoelectric actuator 24. It may be divided into front and back. In any of the above-described embodiments, the end portion of the piezoelectric actuator 24 serves as a rigid block body that contacts the inner wall of the nozzle plate 30 and the substrate 20, and prevents deformation of the nozzle plate 30 due to vibration of the piezoelectric actuator 24. In the former embodiment, there is an advantage in manufacturing such that a plate material made of a piezoelectric material can be bonded to a substrate and then processed for groove formation. The latter embodiment has an advantage that the vibration transmissibility from the piezoelectric actuator 24 to the nozzle plate 30 is further reduced. It is also possible to employ a member other than the piezoelectric material as the block body. It is more preferable that the gap becomes smaller as the groove becomes lower. Further, the groove 28 may be filled with a filler so that the filler absorbs vibration. FIG. 4 shows an example in which the groove 28 is provided with a step in the depth direction and further filled with the filler 42. The filler has, for example, an elastic modulus of about 30.
It is preferable to select one having 0 kgf / mm ² or less. When the filling material 42 is filled in the groove 28, the filling material 42
Has an advantage of being an oxidation protection layer or a moisture protection layer of the piezoelectric actuator 24, and is also advantageous in adopting a configuration in which no partition wall is provided.

It is also possible to employ a configuration in which the block body is not provided. For example, as shown in FIG. 5, a gap is provided between the end of the piezoelectric actuator 24 and the nozzle plate 30, and the filler 42 is provided therein. Can be adopted. Furthermore, as the piezoelectric actuator 24, as shown in FIG.
24 may be used. In this case, as shown in the figure, one electrode 126 can be connected by the groove 28 on the front end side, and the other electrode 128 can be connected by the rear end portion of the piezoelectric actuator 24.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an inkjet recording head.

FIG. 2 is a partial cross-sectional view taken along the line II-II of FIG.

FIG. 3 is a partial enlarged view of an ink jet recording head showing another embodiment of the buffer section.

FIG. 4 is a partial enlarged view of an ink jet recording head showing another embodiment of the buffer section.

FIG. 5 is a partially enlarged view showing another embodiment of the inkjet recording head.

FIG. 6 is a sectional view showing an example in which the present invention is applied to a laminated piezoelectric actuator.

[Explanation of symbols]

10 ... inkjet recording head, 12 ... top plate, 14 ...
Ink cavity, 16 ... Partition wall, 18 ... Piezoelectric vibrating member,
20 ... Substrate, 24 ... Piezoelectric actuator, 28 ... Groove (buffer section), 30 ... Nozzle plate, 32 ... Ink nozzle,
40 ... Ink, 42 ... Filler.

Claims (8)

[Claims] An ink cavity containing ink;
The piezoelectric member includes a piezoelectric member that transmits vibration to the ink in the ink cavity, and an ink discharging member having an ink discharging port that discharges ink in a direction perpendicular to the vibration direction of the piezoelectric member. An ink jet recording head, characterized in that a shock absorbing portion for absorbing vibration is provided between and. 2. The ink jet recording head according to claim 1, wherein the buffer section is an empty chamber. 3. The ink jet recording head according to claim 2, wherein the vacant chamber is filled with a filling material. 4. The substrate further includes a substrate that contacts and supports the piezoelectric member and the ink ejecting member, and a rigid body that contacts the substrate and the inner wall of the ink ejecting member, and the buffer portion is the rigid body. The inkjet recording head according to claim 1, which is provided between the piezoelectric member and the piezoelectric member. 5. The rigid body and the piezoelectric member are made of the same piezoelectric material, the rigid body is an unpolarized body or a non-vibrating body to which no voltage is applied, and the piezoelectric member is polarized and to which a voltage is applied. The ink jet recording head according to claim 4, which is a vibrating body. 6. The ink jet recording head according to claim 5, wherein the rigid body and the piezoelectric member are manufactured by providing a piezoelectric plate made of a piezoelectric material with a cutout portion serving as the buffer portion. 7. The ink jet recording head according to claim 6, wherein the cutout portion is provided at a bottom portion of the cutout portion so as to leave a predetermined thickness on a piezoelectric plate near the cutout portion. 8. The ink jet recording head according to claim 1, wherein the length of the buffer portion in the ink ejection direction is 0.1 to 2 mm.