JP3082802B2 - Inkjet recording head - Google Patents

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 for performing recording by discharging droplets, and more particularly to a structure for fixing a piezoelectric element and a flow path unit.

[0002]

2. Description of the Related Art An ink jet recording head that uses a longitudinal displacement of a piezoelectric element to displace a pressure chamber wall in the displacement direction to pressurize ink in the pressure chamber and eject ink droplets from nozzles is disclosed in It is disclosed in Japanese Patent No. 52625. In this recording head, as shown in FIG. 8, a pressure plate 104 forming a pressure wall is joined to a flow path substrate 103 joined to a nozzle plate 102 having an ink discharge port 101, and pressure is applied to a portion located in each pressure chamber. The legs 106 provided at the longitudinal end of the element 105 are connected by a viscoelastic member. Further, the piezoelectric elements 105 are fixed one by one,
08 and positioned and joined together, and electrical wiring is made by the circuit board 109.

[0003]

However, since the piezoelectric elements need to be bonded to the fixing plate one by one, it is time-consuming and difficult to mass-produce. In addition, the mounting position accuracy due to the variation is low, and the flow path substrate is difficult to be mounted. However, there is a problem that the accuracy of the joint position is low. SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and an object of the present invention is to provide an ink jet recording head capable of causing a piezoelectric element to contact a flow path unit with high accuracy.

[0004]

In order to solve such a problem, an ink jet recording head according to the present invention comprises a plurality of piezoelectric elements involved in the ejection of ink droplets and a dummy piezoelectric element not involved in the ejection of ink droplets. An element unit in which elements are fixed in a row on a holding substrate so as to be located on both sides of the piezoelectric element, and an ink flow path unit that ejects ink droplets in response to displacement of the piezoelectric element are positioned on a fixing member. In the ink jet recording head configured as described above, a window for exposing these piezoelectric elements is formed in the fixed member at a predetermined interval from the piezoelectric elements involved in the ejection of the ink droplets, and a window outside the dummy piezoelectric element is formed. Engaging grooves are formed on both sides of the window to engage with the front and back surfaces.

[0005]

Since the side surface of the dummy piezoelectric element and both sides in the thickness direction adjacent thereto are guided by the engagement grooves, the piezoelectric element is positioned at a predetermined position.

[0006]

1 and 2 show an embodiment of an ink jet recording head according to the present invention, in which a laminated piezoelectric element 1 is fixed to a holding substrate 2. FIG. This piezoelectric element 1 is obtained by fixing a piezoelectric element plate to a holding substrate 2 made of a ceramic substrate having electrodes formed on its surface by sputtering or plating, or a substrate obtained by laminating a copper foil on a glass epoxy substrate with an adhesive. As shown in FIG. 2, it is cut into a predetermined width w.

[0007] When the piezoelectric element plate is cut, a groove is formed in the holding substrate 2 to a certain depth to form an electrode pattern 2a. Thus, the piezoelectric element 1 is fixed to the holding substrate 2 as a plurality of aggregates to form a piezoelectric element unit, a signal line cable is connected to the electrode pattern, and the piezoelectric element 1 and the holding substrate 2 The connection line 11 establishes electrical continuity.

The piezoelectric element unit is fixed to the fixed plate 3 made of a resin material via a joint 4a between the piezoelectric element 1 and the flow path unit 12 via a joint 4a. The ink passage unit 12 includes a nozzle plate 7 having a nozzle portion 10.
A pressure chamber 8, a communication hole 9 communicating from the pressure chamber 8 to the nozzle 10, a flow path forming plate 6 forming an ink supply reservoir 13, and a pressure wall 5 for applying pressure to the pressure chamber 8. It is configured.

As shown in FIG. 7, the pressure wall 5 has a thick portion 5a which is joined to the piezoelectric element 1 by a joining member 4a such as an epoxy adhesive, and a thin portion which bends in a beam shape when the piezoelectric element 1 is displaced. 5b.

The piezoelectric element units 31 are arranged in a row on the holding substrate 2 as shown in FIG. 6, and dummy piezoelectric elements 14 are provided on both sides of the fixed piezoelectric element array in accordance with the piezoelectric element cutting process. The size of the dummy piezoelectric elements 14 formed at both ends up to the outside of the dummy piezoelectric elements 14 is managed to a predetermined size M.

On the other hand, as shown in FIG. 4, the fixed plate 3 is provided with a window 35 which does not hinder the vibration of the piezoelectric element 1, that is, exposes a certain gap 33, 34 between the front side and the back side.
Are formed. On both sides of the window 35, gaps 33, 34
And a small clearance with respect to the dimension M of the piezoelectric element unit 31, and the engagement grooves 32, 32 into which the dummy piezoelectric elements 14, 14 can be inserted are formed in the window 3.
5 is formed so as to be located substantially at the center in the width direction D.

In this embodiment, when the piezoelectric element unit 31 is inserted from below the fixing plate 3 as shown in FIG.
The two sides 14b and 14c in the thickness direction adjacent thereto are guided by the engagement groove 32, and the piezoelectric element 1 is positioned at a predetermined position of the window 35.

As described above, the dummy piezoelectric element 14 regulates not only the position of the piezoelectric element 1 in the direction in which the piezoelectric elements 1 are arranged but also the position of the piezoelectric element 1 in the thickness direction by the region 36, so that the holding substrate 2 and the fixed plate 3, the piezoelectric element 1 can be accurately positioned with respect to the pressure wall 5 of the flow path unit, as compared with the case where the position of the piezoelectric element 1 is regulated only by the position 3.

The fixing plate 3 may be made of ceramic, metal, resin or the like. However, it is desirable to injection-mold a resin mixed with an inorganic filler from the viewpoint of cost and accuracy.

Further, in the above-described embodiment, an example using a single piezoelectric element unit has been described.
It is clear that the same effect is achieved even when applied to a case where a plurality of piezoelectric element units are incorporated in the same fixed plate 3.

[0016]

As described above, according to the present invention, a predetermined interval is formed with respect to the piezoelectric elements involved in the ejection of ink droplets, and both sides of the window for exposing these piezoelectric elements are provided outside the dummy piezoelectric elements. And the front and rear surfaces are formed with the engagement grooves, so that the dummy grooves can regulate not only the position in the direction in which the piezoelectric elements are arranged but also the position in the thickness direction of the piezoelectric elements. Thus, the piezoelectric element can be accurately positioned with respect to the flow path unit as compared with the case where positioning is performed between the holding substrate and the fixing plate.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of an ink jet recording head of the present invention in a longitudinal sectional structure of one pressure chamber.

FIG. 2 is a diagram showing a cross-sectional structure of the same ink-jet recording head taken along line AA ′ in FIG. 1;

FIG. 3 is a perspective view showing the inkjet recording head with the flow path unit removed.

FIG. 4 is a plan view showing the inkjet recording head with the flow path unit removed.

FIG. 5 is a sectional view taken along line BB ′ in FIG. 2;

FIG. 6 is a diagram showing a dimensional relationship between an element unit and a fixing plate.

FIG. 7 is a perspective view showing one embodiment of a pressure plate.

FIG. 8 is a perspective view showing an example of an element unit used in a conventional ink jet recording head.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 laminated piezoelectric element 2 holding substrate 3 fixing plate 12 ink flow path unit 14 dummy piezoelectric element 31 piezoelectric element unit 32 engagement groove

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-247453 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41J 2/045 B41J 2/055 B41J 2 / 16

Claims (3)

(57) [Claims] 1. An element in which a plurality of piezoelectric elements involved in ejection of ink droplets and dummy piezoelectric elements not involved in ejection of ink droplets are fixed in a row on a holding substrate so as to be located on both sides of the piezoelectric element. Unit and an ink flow path unit that ejects ink droplets by receiving the displacement of the piezoelectric element, in an ink jet recording head configured to be positioned on a fixed member, wherein the piezoelectric element involved in the ejection of the ink droplet is fixed. An ink jet is formed by forming windows on the fixing member to form an interval to expose these piezoelectric elements, and forming engagement grooves on both sides of the windows to engage the outside and the front and back surfaces of the dummy piezoelectric elements. Recording head. 2. The ink jet recording head according to claim 1, wherein the engaging groove is formed at a center of the window in a thickness direction of the piezoelectric element. 3. The ink jet recording head according to claim 1, wherein the fixing member is made of a resin or a resin molded article mixed with an inorganic filler.