JPH05345413A - Ink jet recording head - Google Patents

Abstract

PURPOSE:To prevent unnecessary ejection of ink (unnecessary discharge of dots) by a method wherein displacement in the direction other than that extends along the longitudinal axis of electromechanical transduction elements, namely unnecessary direction, induced by driving of the electromechanical transduction element of an adjoining channel is transmitted to the ink as pressure. CONSTITUTION:The title head is composed of head members 4-7, equipped with an orifice 9 and having ink chambers 10-13 to be filled with ink that is ejected through the orifice, electromechanical transduction members 1 mounted to the head members so that ends on one side thereof contacting with the ink in the ink chambers can be displaced freely in the ink chambers, and a sealing agent 14 filling a space between prepheral faces on the ends of the electromechanical transduction members 1 and wall surfaces of the ink chambers 10-13. Filling of the sealing agent 14 is made so that the end thereof contacting with the ink can be brought closely to the ends on one side of the electromechanical transduction members 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet recording head device, and more particularly to an inkjet recording head device used in an inkjet printing device.

[0002]

2. Description of the Related Art The structure of a general ink jet recording head device will be described.

In the general ink jet recording head device shown in FIGS. 4 to 7, 1 is an electromechanical conversion element (piezo element), 2 is a fixing plate for fixing the electromechanical conversion element 1 to a base plate 3, 4 Is an orifice plate, 5 is a nozzle plate, and 6 is PZT (lead, zirconate, titanate).
G) plate, 7 is a filter plate, 8 is an orifice portion, 9 is an orifice, 10 to 13 are ink chambers, 14 is silicone rubber, and 15 is a tip of the electromechanical transducer 1 so as to cover the tip thereof. The attached caps and 21 are head members, respectively.

The cap 15 attached to the tip of the electromechanical transducer 1 having a thickness of about 0.4 mm has a thickness of about 0.55 mm, and the tip is positioned about 0.1 mm away from the central axis 18 of the orifice 9. The tip of the electromechanical transducer 1 is located about 2.0 mm away from the central axis of the orifice 9. The tip of the electromechanical conversion element 1 is about 1.
The distance L ₁ between the end of the silicone rubber 14 in contact with the ink and the tip of the cap 15 is about 1 mm. Orifice plate 4 is about 0.2mm thick.
Nozzle plate 5 is about 1.0 mm, PZT plate 6 is about
0.63 mm, filter plate 7 is about 0.2 mm, base plate 3
Is about 1.5 mm.

The shapes of the orifice and the ink chamber are shown in FIGS. The upper diameter φ ₁ of the orifice provided in the filter plate 7 is about 36 μm, and the lower diameter φ ₂ is about 53 μm.
μm, height h1 is about 0.2 mm, upper diameter φ ₃ of nozzle plate 5 is about 0.1 mm, lower diameter φ ₄ is about 0.2 mm, distance
S is 0.1 mm and width W ₁ is 0.335 mm. Further, in FIG. 7, another orifice having an upper diameter φ ₅ of about 25 μm, a lower diameter φ ₆ of about 45 μm and a height h 2 of about 0.2 mm is shown in the filter plate 7.

In this apparatus, the electromechanical conversion element 1 is displaceable in the direction D of FIG. 4, that is, in the direction along the longitudinal axis of the electromechanical conversion element 1.
In a direction along the longitudinal axis of the electromechanical conversion element 1 so that the tip of the cap 15 in contact with the ink in the ink chamber pressurizes the ink in the ink chamber to eject the ink from the orifice.
Is displaced, from the left to the right in FIG. 4), the ink in the ink chambers 10 to 13 is pressurized, and an ink droplet is ejected from the orifice 9.

The displacement direction of the electromechanical conversion element 1 is the direction along the above-mentioned longitudinal axis, that is, the necessary direction and the unnecessary direction (the direction other than the above-mentioned direction along the longitudinal axis, which is the direction of the ink). There is an unsuitable direction for proper ejection).

In a structure in which the electromechanical conversion element 1 is partly attached to the main body, for example, one end is inserted and mounted in the ink chamber, in order to properly eject the ink, the ink is displaced when it is displaced in the aforementioned unnecessary direction. Although it is necessary to suppress the displacement so as not to eject the ink, generally, no suppression measure is taken.

Silicon rubber 1 with respect to the necessary direction described above
4 is the distance between the end portion 20 in contact with the ink in the ink chamber 12 and the tip of the electromechanical conversion element 1 inserted in the ink chamber (the tip of the cap when the cap is attached to the one end). (L _{1 in} FIG. 4) is relatively large with respect to the length of the ink chamber 12 in the direction along the longitudinal axis, and the end portion 20 of the silicone rubber 14 in contact with the ink is located at a great distance from the tip of the cap 15. ing.

Further, the electromechanical conversion element 1 or the cap 1
It was thought that if a rubber elastic body such as silicon rubber was present at the tip of No. 5, the pressure to be applied to the ink would be absorbed by the rubber elastic body and the ink ejection characteristics would deteriorate.

[0011]

In the multi-head, the electromechanical conversion element 1 is displaced by the above-mentioned displacement in the unnecessary direction, that is, in resonance with the drive frequency (usually several KHz) of the adjacent channel, which is unnecessary. A problem of ink ejection (ejection of unnecessary dots) occurs.

Further, regarding the method of filling the rubber elastic body, it is difficult to uniformly attach the rubber elastic body to one end of the electromechanical conversion element, and it is difficult to manufacture the electromechanical conversion element in which the rubber elastic body is evenly attached to one end. there were.

It is an object of the present invention to cause a displacement in the ink other than a direction along the longitudinal axis of the electromechanical conversion element, which is induced due to the driving of the electromechanical conversion element of the adjacent channel, that is, unnecessary displacement. An object of the present invention is to provide an inkjet recording head device which is transmitted as a pressure and can prevent unnecessary ink ejection (unnecessary dot ejection).

[0014]

SUMMARY OF THE INVENTION According to the present invention, there is provided a head member having an ink chamber which is provided with an orifice and is filled with ink to be ejected through the orifice, and one end in contact with ink in the ink chamber is provided in the ink chamber. An electromechanical conversion member attached to the head member so as to be freely displaceable,
A sealant is filled between the peripheral surface of one end of the electromechanical conversion member and the wall surface of the ink chamber, and the end of the sealant in contact with the ink is close to the tip of one end of the electromechanical conversion member. It is filled so as to

[0015]

Since the sealant is filled so that the end portion in contact with the ink is close to the tip of the one end of the electromechanical conversion member, displacement of the electromechanical conversion element in a direction other than one direction causes electromechanical conversion. It is possible to prevent the pressure induced in the element from being transmitted to the ink in the ink chamber. Further, it is possible to prevent unnecessary dots from being ejected by pressure induced by displacement in a direction other than one direction, and with such a configuration, an inkjet recording head device having advantages can be manufactured inexpensively and easily.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT In the embodiment of the apparatus of the present invention shown in FIG.

One end of the electromechanical conversion element 1, for example, a piezo element may be directly inserted into the ink chamber, or the tip of the piezo element may be covered with a molding seal rubber 16 (thickness L ₂ = 0.3 mm). Good.

1 and 3, the orifice plate 4, the nozzle plate 5, the PZT plate 6 and the filter plate 7 form a head member.

The electromechanical conversion element 1 is attached to the base plate 3 via the fixed plate 2 and is displaceable in the direction of the longitudinal axis of the electromechanical conversion element 1 (direction D in FIG. 1).

One end of the electromechanical conversion element 1 in contact with the ink in the ink chamber 12 is covered with a molding seal rubber 16, and the wall surface of the ink chamber corresponding to the peripheral surface of the seal rubber 16 and one end of the electromechanical conversion element 1. A sealant 14 made of, for example, silicon RTV (room temperature added) rubber is filled between the peripheral surface of the seal rubber 14 and the peripheral surface of the seal rubber 16. The end portion 22 of the sealant 14 that comes into contact with the ink filled in the ink chamber 12 and the seal
Distance L _{1 from} the tip of the top of the rubber rubber 16 (the tip of one end of the electromechanical conversion element 1 when the seal rubber 16 is not used)
When (Fig. 3) is 0.5 mm or less (in this case, the thickness W _{2 of the} piezo element is 0.36 mm), the electromechanical conversion element 1 is arranged along the longitudinal axis extending from the other end of the electromechanical conversion element 1 to one end. Even when displacement in a direction other than one direction (from left to right in FIGS. 1 and 3) is induced, the amount of energy transmitted to the ink in the ink chamber is very small, and unnecessary dots are not ejected from the orifice. .

For example, when the thickness of the piezo element is 0.36 mm and the amount of displacement in a direction other than the direction along the longitudinal axis is 0.1 μm,
When L ₁ is 0.5 mm or less, the displacement volume Δv is Δv
= 0.4 x 10 ^-3 x 0.5 x 10 ^-3 x 0.1 x 10 ^-6 = 2 x 10
^-14 m is ^3, which is the ink droplet volume 4π diameter 40μm
^{(20 x 10 -6) 3/} 3, i.e. smaller droplet ejection than about 3.2 x 10 ^-14 m ³ is not induced.

The method for attaching the sealant 14 to the electromechanical conversion element 1 is as follows.

As shown in FIG. 2, the electromechanical conversion element 1 and the sealant 14, for example, silicone RTV rubber are put in a molding die 17, and after the sealant 14 is cured, the electromechanical conversion element 1 and the sealant are sealed. The adhesive agent 14 is removed from the mold 17 and inserted into the ink chamber 12. At this time, even if a minute gap is generated, the liquid rubber is poured and sealed after the insertion.

The above L ₁ depends on the thickness of the piezo element. If the thickness of the piezo element is W ₂ , then L ₁ can be expressed as approximately 0.5 / (W ₂ /0.36).

In this embodiment, W ₂ = 0.36, and therefore L ₁ = 0.5 mm. Numeric 0.36 of W ₂ is a piezoelectric material
(PZT ceramic) mechanical strength, dimensions, processing means (dicing or wire saw processing) is practically selected and determined.

[0026]

Since the sealant is filled so that the end portion in contact with the ink is close to the tip of one end of the electromechanical conversion member, the electromechanical conversion element is electrically displaced by a displacement other than one direction. The pressure induced in the mechanical conversion element can be prevented from being transmitted to the ink in the ink chamber. Furthermore, it is possible to prevent unnecessary dots from being ejected by pressure induced by displacement in a direction other than one direction, and with such a configuration, an inkjet recording head device having advantages can be manufactured inexpensively and easily.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an embodiment of an inkjet recording head device of the present invention.

FIG. 2 is a diagram showing a method of attaching a rubber elastic body to the electromechanical conversion element.

FIG. 3 is an enlarged cross-sectional view of the head member of the embodiment of FIG.

FIG. 4 is a schematic cross-sectional view of a general inkjet recording head device.

FIG. 5 is a diagram illustrating the shape of an orifice in an orifice plate.

FIG. 6 is a diagram illustrating the shapes of ink chambers in a nozzle plate and a PZT plate.

FIG. 7 is a diagram illustrating a shape of a filter in a filter plate.

[Explanation of symbols]

 1 Electromechanical conversion element 4 Orifice plate 5 Nozzle plate 6 PZT plate 7 Filter plate 9 Orifice 10-13 Ink chamber

Claims (1)

[Claims] 1. A head member having an orifice and having an ink chamber filled with ink to be ejected through the orifice, and one end in contact with the ink in the ink chamber is displaceable in the ink chamber. An electromechanical conversion member mounted on the head member; and a sealant filled between a peripheral surface of the one end of the electromechanical conversion member and a wall surface of the ink chamber. The ink jet recording head device is characterized in that an end portion in contact with ink is filled so as to be close to a tip of the one end of the electromechanical conversion member.