JP2003039669A - Ink jet recording head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording head which is highly reliable by surely bonding piezoelectric vibrators and islands, and has stable ink jet characteristics by uniforming compliances of pressure generation chambers as much as possible. SOLUTION: In the ink jet recording head for jetting ink drops from nozzle openings by directly deforming a diaphragm by the expansion and contraction of piezoelectric vibrators, the diaphragm is made an island part having at least one or more recessed parts formed by etching to islands formed by etching a metal thin film. When the piezoelectric vibrators are bonded to the islands, a necessary or larger amount of an adhesive escapes to grooves as the recessed parts set on the islands and is prevented from flowing out to the diaphragm. Compliances of pressuring regions of the pressure generation chambers can be uniformed accordingly.

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 forming characters and images on a recording medium such as recording paper by ejecting ink droplets according to a print signal. More specifically, the present invention relates to a configuration of a diaphragm that forms one wall surface of a pressure generating chamber for ejecting ink droplets and transmits expansion and contraction of a piezoelectric vibrator to the pressure generating chamber.

[0002]

2. Description of the Related Art In recent years, in order to improve the recording density of recording heads, there is a tendency to reduce the pitch of nozzle opening rows. For this reason, a silicon single crystal wafer is anisotropically etched, and a nozzle plate or diaphragm manufactured by another method is fixed to this with an adhesive to form a flow path unit. Is transmitted to generate pressure, and ink droplets are ejected from the nozzle openings. When the arrangement density of the pressure generating chambers becomes large, the width of the pressure generating chambers becomes extremely small. Therefore, in order to efficiently deform the entire length direction of the pressure generating chambers, the diaphragm formed of an elastically deformable thin plate, A convex portion extending in the longitudinal direction of the pressure generating chamber, that is, a so-called island portion is formed, and the displacement of the piezoelectric transducer is transmitted to the diaphragm through the island portion.

As such a vibrating plate, a polymer material layer is formed on one surface of a metal thin plate by a roll coating method, a spray method or the like, and the metal thin plate is etched to form an island portion. It has been proposed to use a polymer material layer exposed by etching as a diaphragm portion.

However, at the time of the bonding work step for forming the ink flow path, the flatness of the island portion on the contact surface of the oscillator causes variations in the thickness of the diaphragm, and when forming the flow path unit or the head. It is deformed by about 0 to 10 μm due to an adhesive hardening strain or the like that occurs when it is adhesively fixed to the housing. On the other hand, the tip of the piezoelectric vibrator also deforms when firing the piezoelectric material and the electrode. As a measure to prevent the deformation during firing, as disclosed in Japanese Patent No. 2987944, it is possible to improve the deformation by providing a dummy electrode. However, the warp of the tip is suppressed to 0 to 5 μm or less. Things are difficult. In order to suppress the variation, a process such as polishing the tip of the piezoelectric vibrator is required, which increases the cost. Even in such a state, the gap between the island portion and the tip of the piezoelectric vibrator varies from 0 to 15 μm in terms of component accuracy. For this reason, if the amount of adhesive applied is small, the adhesive may not be adhered at the maximum gap, or the adhesive may peel off during continuous printing and the displacement of the piezoelectric vibrator cannot be transmitted. In the worst case, ink ejection failure will occur and the reliability of the head will be impaired. Therefore, in order to ensure the bonding with the island even if the maximum gap as described above occurs,
It is possible to apply a large amount of adhesive to the tip of the piezoelectric vibrator. However, at the portion where the gap is narrow, a part of the adhesive evenly applied to the tip of the piezoelectric vibrator flows along the side surface of the island and flows out to the diaphragm portion. The amount of adhesive that flows out to the diaphragm also changes due to the gap variation, and the adhesive that flows out hardens on the diaphragm, so the compliance that is the softness of the diaphragm varies, and as a result, the compliance of each pressure generation chamber is changed. There is a problem that variations occur and the ejection performance of ink drops is changed.

[0005]

In order to solve such a problem, the height of the island is increased so that the side wall of the island absorbs the adhesive that flows out at the time of bonding, and the outflow to the diaphragm is prevented as much as possible. Is being done. Therefore, it is necessary to increase the height of the island by 30 μm or more. Along with this, the thickness to be etched becomes 30 μm or more, and the dimensional difference between the long side and the short side of the island becomes large. Therefore, etching a height of 30 to 50 μm or more ensures dimensional accuracy due to problems such as overetching. Very difficult to do.

On the other hand, in order to minimize the gap,
It is costly to improve the flatness of the tip end portion of the piezoelectric vibrator and to prevent island warpage by assembling the ink flow path by adhering work, resulting in poor mass productivity and consequently head cost or product cost. It will be up.

The present invention solves such a problem, and an object of the present invention is to provide a highly reliable ink jet recording head in which the piezoelectric vibrator and the island are securely bonded. A second object of the present invention is to provide an ink jet recording head having a stable ink ejection characteristic by making the compliance of the pressure generating chamber as uniform as possible.

[0008]

In order to solve such a problem, in the present invention, a nozzle plate having a plurality of nozzle openings, a pressure generating chamber having one end communicating with the nozzle opening, and the pressure A chamber member including an ink supply port that communicates with the other end of the generation chamber and a common ink chamber that communicates with the ink supply port, and a thin film plywood in which a metal thin film and a polymer stretched film are adhered or pressure-contacted are etched. A flow path unit configured by joining a diaphragm having an island portion facing the pressure generating chamber to each other, and the other end of the piezoelectric vibrator having one end fixed to a base via an adhesive agent on the island. In the ink jet recording head, which is configured to abut against each other and which directly deforms the vibrating plate by expansion and contraction of the piezoelectric vibrator to eject ink droplets from the nozzle openings, The islands formed by etching, characterized in that at least one or more recesses are formed etched.

Further, the recess formed in the island of the diaphragm is formed substantially parallel to the long side of the island with which the piezoelectric vibrator contacts.

Further, the concave portion formed in the island of the diaphragm is larger than 0 ° and is larger than 0 ° with respect to the long side of the island.
It is characterized in that at least one place is arranged with an inclination of less than 0 °.

Further, the concave portion provided on the island is formed at least in a range larger than the longitudinal dimension of the piezoelectric vibrator.

Further, the recesses formed on the island of the diaphragm are characterized in that they are arranged substantially at right angles to the long side of the island, and at least two or more locations are arranged substantially parallel and at equal pitch.

Further, the range in which the recesses arranged in parallel are formed is equal to or smaller than at least the longitudinal dimension range of the piezoelectric vibrator.

Further, the total void volume V of the recesses (grooves) provided on the island is the maximum value δmax, the minimum value δmin, and the projected area of the island of the gap between islands and the piezoelectric vibrators of the same nozzle row. Is Ai, V
It is characterized in that ≧ (δmax−δmin) × Ai.

Further, a nozzle plate provided with a plurality of nozzle openings, a pressure generating chamber whose one end communicates with the nozzle opening, an ink supply port communicating with the other end of the pressure generation chamber, and a communication with the ink supply port. A chamber member composed of a common ink chamber, and a thin film plywood in which a metal thin film and a polymer stretched film are adhered or pressure-bonded to each other, and a diaphragm having an island portion facing the pressure generation chamber is joined. And the other end of the piezoelectric vibrator whose one end is fixed to the base is abutted on the island via an adhesive, and the vibration plate is directly expanded and contracted by expansion and contraction of the piezoelectric vibrator. In an ink jet recording head that deforms and ejects ink droplets from a nozzle opening, an island provided on the vibrating plate has a polymer having a width on the short side in contact with the piezoelectric vibrator. It is so large than the short side dimension of the extension film side, and being greater than the width of the short side of the piezoelectric vibrator.

Further, the end portion in the longitudinal direction of the island is characterized in that it is formed on an inverted umbrella with substantially the same size toward the piezoelectric vibrator side.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The details of the present invention will be described below based on illustrated examples.

FIG. 1 is a partial perspective view showing an example of an ink jet recording head of the present invention, FIG. 2 is a partial sectional view thereof, and 1 is a nozzle plate having a plurality of nozzle openings 2, 2, ... 3 is a chamber plate, which is a pressure generating chamber 4
And a member for partitioning the ink supply port 5 and the common ink chamber 6. 7 is a vibrating plate, which is made of a resin thin portion 7a and a metal thin film 7
It is a plate composed of a laminated body in which b is integrated by pressure welding or adhesion. By etching the metal thin film 7b side of the vibrating plate 7, a thin diaphragm 10 made of resin and a masked island part 11 are formed, and the vibrating plate 7 and the nozzle plate 1 form a chamber plate 3 The ink flow path unit is configured by stacking the both sides so as to be sealed and adhering to each other.

The island portion 11 has a length that is substantially the same as or shorter than the length direction of the pressure generating chamber 4, and the width thereof is about 1/2 or less of the width of the pressure generating chamber 4. The piezoelectric vibrator 20 is dimensioned so that the displacement of the piezoelectric vibrator 20 can be transmitted to the entire pressure generating chamber 4.

The piezoelectric vibrator 20, as shown in FIG.
An electrode 21 serving as one pole and an electrode 22 serving as the other pole are laminated in a sandwich shape with a piezoelectric material 23 interposed therebetween, and are bonded and fixed to a fixed substrate 30 and then cut in a comb shape at a constant pitch. It In this case, handling and workability are better if the piezoelectric vibrator 20 is bonded and fixed to the fixed substrate 30 in a flat plate state, and then is diced into a comb shape or wire-cut.

Then, the piezoelectric vibrator 20 is fixed to the head housing 40 via the fixed substrate 30 with its tip abutting on the island portion 11.

Next, the diaphragm 7 will be described with reference to FIGS. 3A and 3B showing an example of the present invention.

Since the diaphragm 10 directly contacts the ink, the thickness 10 to 30 is durable against the ink.
For example, polyimide, aramid, polyphenylene sulfide resin, or the like is used as a thin plate of μm. The island portion 11 is made of an etchable stainless steel sheet or the like, and two of them are laminated and pressure-bonded or bonded.

In this state, using a mask having a pattern to be etched on the stainless steel portion, a groove which is a concave portion on the substantially center line of the diaphragm portion 10 and the island portion 11 in the longitudinal direction is formed by etching. That a
The cross-sectional shape of -a is shown in FIG. Further, the depth can be controlled by the pattern width to be etched, or after forming the island 11, the mask may be masked again to etch only the groove portion. There is no problem if the cross-sectional shape of the recess formed by etching is not rectangular but U-shaped or V-shaped.

The flow path unit having the vibrating plate 7 constructed in this manner is fixed to the plane fixing portion of the head housing 40, and an adhesive is applied to the tip of the piezoelectric vibrator 20 of the vibrator unit to make the head. The piezoelectric vibrator 20 is inserted from an elongated hole provided in the housing 40, and the tip of the piezoelectric vibrator 20 abuts on the island portion 11 of the vibration plate 7 forming the flow path unit via an adhesive.

FIG. 5 shows an island 11 according to the prior art.
3 illustrates a bonding state between the piezoelectric vibrator 20 and the piezoelectric vibrator 20. Island part 1
1 shows an example in which the gap between the piezoelectric vibrator 20 and the piezoelectric vibrator 20 is different, (b) is a gap of 0, (c) is the maximum gap, for example, about 15 μm, and (a) is a medium gap of (b) and (c). There is a gap. When the gap is 0 (b), the adhesive 50 is transmitted to the island 11 side and the diaphragm portion 1
It flows to 0.

FIG. 4 shows an island 1 which is an example of the present invention.
1 shows a bonded state between the piezoelectric vibrator 20 and the piezoelectric vibrator 20. Since there is a groove that becomes a concave portion between the island portion 11 and the piezoelectric vibrator 20 even if the gap varies, the concave portion absorbs the adhesive flowing out to the diaphragm portion 10, and the adhesive 50 to the diaphragm portion 10 is absorbed. Since it is possible to prevent the flow out of the island 10, the height of the island 10 is not increased more than necessary, and the height is sufficient as long as it can withstand the rigidity when the piezoelectric vibrator 20 is displaced. The processing cost is reduced by shortening the etching time.

Further, the length of the recess formed on the island 11 is preferably longer than the dimension of the long side of the piezoelectric vibrator 20 with which it abuts. That is, by making the recesses longer, the air in the recesses can easily escape when the piezoelectric vibrator 20 is bonded, so that the adhesive 50 easily flows into the recesses. In the example shown in FIG. 4, the piezoelectric vibrator 2
Although only the position variation on the 0 side is shown, the contact surface of the island 11 with the piezoelectric vibrator 20 is warped or deformed, or both the piezoelectric vibrator 20 and the contact surface of the island 11 are bonded due to deformation or dimensional variation. It goes without saying that similar effects can be obtained even if the gap varies.

FIG. 6 shows a modification of the example of the present invention. In this example, the groove portion (halftone dot portion in the figure) formed in the island portion 11 has a length with which the piezoelectric vibrator 20 abuts. The groove may be inclined with respect to the center line of the side, and more specifically, it may be greater than 0 ° and 90 ° or less with respect to the long side, and even when the angle approaches 90 °, the groove portion has the piezoelectric vibrator 20.
It suffices if it is formed within the adhesion range (the two-dot chain line in the figure indicates the projection surface of the piezoelectric vibrator 20). At this time, if the angle becomes large and the piezoelectric vibrator 20 is formed within the bonding range of the piezoelectric vibrator 20, a plurality of concave portions may be formed, and the details thereof will be described below.

FIG. 7 shows a modified example in which a plurality of recessed grooves (halftone dots in the drawing) are arranged at substantially equal pitches on the short side of the island 11. The number of the recessed grooves may be one, but it is desirable that there be at least two. That is, at least three contact points between the piezoelectric vibrator 20 and the island portion 11 are ensured, and at least one contact point is the island 1.
Since the piezoelectric element 20 is provided at a position located at the center of the position 1, the displacement of the piezoelectric element 20 can be reliably transmitted to the pressure generating chamber 4. In addition, if the concave portion is formed over the entire short side width of the island 11, it is sufficient for air escape during bonding. At this time, since the recesses are arranged at an equal pitch, the amount of adhesive protruding is substantially equal in each recess, and it is possible to suppress the adhesive from flowing out to the diaphragm, and as a result, the compliance of the diaphragm is reduced. Can be uniform. In addition, more effectively, the range in which the recesses arranged in parallel are formed is at least equal to or smaller than the range of the longitudinal size of the piezoelectric vibrator while suppressing the flow of the adhesive. Also makes it possible to displace the diaphragm effectively.

Further, by providing a plurality of islands 11 in the direction of the short side width as in this example, it is possible to easily manufacture even if the pitch of the nozzle openings 2 becomes small, that is, the short side width of the island becomes narrow. Therefore, the change in compliance of the diaphragm 10 due to the adhesive 50 flowing out can be summarized without lowering the reliability of the head.

The void volume V of the concave portion formed on the island 11 is δmax, the minimum value is δmax, and the minimum value is δmin between the piezoelectric vibrator 20 and the island 11 in the same nozzle row, and the island 11 and the piezoelectric vibrator 20. When the projected area of the adhesive surface with is Ai, V ≧ (δmax−δmi
It is desirable that n) × Ai. In other words, it is preferable that most of the adhesive 50 protruding at the minimum gap has a sufficient volume even if it flows into the recess.

FIG. 8 shows another example of the present invention, in which the width W2 of the island portion 11 is the width W of the piezoelectric vibrator 20.
It is configured to be larger than 1. With this structure, the adhesive 50 can be prevented from flowing out from the island portion 11. Further, although not shown, both ends of the long side of the island 11 are configured to be inclined toward the piezoelectric vibrator 20 side, so that the adhesive 50 can be reliably prevented from flowing out.

[0034]

As described above, in the present invention, a nozzle plate having a plurality of nozzle openings,
A chamber member including a pressure generating chamber having one end communicating with the nozzle opening, an ink supply port communicating with the other end of the pressure generating chamber, and a common ink chamber communicating with the ink supply port, and a metal thin film and a polymer stretch A thin film plywood to which a film is adhered or pressure-contacted is etched, and a flow path unit configured by joining a diaphragm having an island portion facing the pressure generating chamber and one end fixed to a base In an ink jet recording head configured such that the other end of the piezoelectric vibrator is in contact with the island via an adhesive, the vibration plate is directly deformed by the expansion and contraction of the piezoelectric vibrator to eject ink droplets from a nozzle opening. The islands formed by etching the metal thin film of the plate are configured so that at least one recess is formed in each island by etching. When the piezoelectric vibrator is bonded to the island, it is possible to prevent unnecessary adhesive from escaping into the groove, which is a recess provided on the island, to prevent it from flowing out to the diaphragm, and to pressurize the pressure generating chamber. Compliance can be made uniform.

[Brief description of drawings]

FIG. 1 is a partial perspective view showing the configuration of an inkjet recording head of the present invention.

FIG. 2 is a partial cross-sectional view of the inkjet recording head of the present invention.

3A and 3B are a plan view and a cross-sectional view showing an example of an island shape of a diaphragm according to the present invention.

FIG. 4 is a diagram showing a state where the island of the diaphragm according to the present invention and the piezoelectric vibrator are bonded.

FIG. 5 is an adhesive diagram of a diaphragm and a piezoelectric vibrator according to a conventional technique.

FIG. 6 is a plan view showing a modified example of the island shape of the diaphragm according to the present invention.

FIG. 7 is a second island-shaped diaphragm of the present invention.
It is the top view and sectional view which showed the modification.

FIG. 8 is a partial cross-sectional view showing an island shape of a diaphragm according to another example of the present invention.

[Explanation of symbols]

1 is a nozzle plate, 2 is a nozzle opening, 3 is a chamber plate, 4 is a pressure generating chamber, 7 is a vibrating plate, 10 is a diaphragm, 11 is an island, and 20 is a piezoelectric vibrator.

Claims (9)

[Claims] 1. A nozzle plate having a plurality of nozzle openings, a pressure generating chamber having one end communicating with the nozzle openings,
A chamber member including an ink supply port communicating with the other end of the pressure generating chamber and a common ink chamber communicating with the ink supply port, and a thin film plywood in which a metal thin film and a polymer stretched film are adhered or pressure-contacted are etched. And a flow path unit configured by joining a diaphragm having an island portion formed at a position facing the pressure generating chamber, one end fixed to a base, and the other end abutted on the island. In an inkjet recording head that deforms a vibration plate by expansion and contraction of a piezoelectric vibrator to eject ink droplets from a nozzle opening, at least 1 is provided on an island formed on the vibration plate.
An ink jet recording head, wherein one or more recesses are formed. 2. The ink jet recording head according to claim 1, wherein the recess formed in the island of the diaphragm is formed substantially parallel to the long side of the island with which the piezoelectric vibrator contacts. 3. The recess formed in the island of the diaphragm is arranged at least at one or more locations with an inclination of more than 0 ° and less than 90 ° with respect to the long side of the island. The inkjet recording head described. 4. The ink jet recording apparatus according to claim 1, wherein the range of the recesses arranged on the island is at least larger than the range of the dimension of the piezoelectric vibrator in the longitudinal direction. 5. The at least two recesses formed in the island of the diaphragm are formed, and the respective protrusions are arranged substantially at right angles to the long sides of the island at equal pitches. It is provided, The claim 1 characterized by the above-mentioned.
The inkjet recording head described. 6. The ink jet recording apparatus according to claim 5, wherein the range in which the recesses arranged in parallel are formed is at least equal to or smaller than the range of the longitudinal dimension of the piezoelectric vibrator. 7. When the maximum value of the gap between islands and the piezoelectric vibrators of the same nozzle row is δmax, the minimum value is δmin, and the projected area of the island is Ai, the total volume of the voids of the recesses provided on the island is set. 7. The inkjet recording apparatus according to claim 1, wherein V is V ≧ (δmax−δmin) × Ai. 8. A nozzle plate having a plurality of nozzle openings, a pressure generating chamber having one end communicating with the nozzle openings,
A chamber member including an ink supply port communicating with the other end of the pressure generating chamber and a common ink chamber communicating with the ink supply port, and a thin film plywood in which a metal thin film and a polymer stretched film are adhered or pressure-contacted are etched. And a flow path unit configured by joining a diaphragm having an island portion formed at a position facing the pressure generating chamber, one end fixed to a base, and the other end abutted on the island. In an ink jet recording head that deforms a vibration plate by expansion and contraction of a piezoelectric vibrator to eject ink droplets from a nozzle opening, a short side of an island provided on the vibration plate is a polymer stretched surface that is in contact with the piezoelectric vibrator. An ink jet recording head, characterized in that it is larger than the short side dimension on the film side and larger than the width of the short side of the piezoelectric vibrator. 9. The ink jet recording apparatus according to claim 8, wherein an end portion of the island in the longitudinal direction is formed on an inverted umbrella with substantially the same size toward the piezoelectric vibrator side.