JPH10157108A - Ink jet printer head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress warping or waving of a head body where a top plate is bonded to a substrate. SOLUTION: The ink jet printer head comprises a substrate 3 laminated with at least one piezoelectic member polarized in the thickness direction, a plurality of parallel grooves 4 and side walls 5 at least partially made of the piezoelectic member and arranged at a constant interval on the substrate 3, and a top plate 9 covering the upper part of the grooves 4 to form a plurality of ink chambers 11 wherein the top plate 9 is made of a material having a coefficient of thermal expansion equivalent to that of the piezoelectic member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an on-demand type ink jet printer head using a piezoelectric member.

[0002]

2. Description of the Related Art Conventionally, a nozzle plate having an ink discharge port is fixed to the tip of a large number of ink chambers connected in parallel and connected to an ink supply section. There is an ink-jet printer head which is designed to fly. As a method for increasing the ink pressure in the ink chamber in such an ink jet printer head, there is a technique disclosed in Japanese Patent Application Laid-Open No. 63-247051. That is, at least a part of the side wall arranged on both sides of the ink chamber is formed by a piezoelectric member, an electrode is formed on the side surface of the side wall, and the voltage is applied to the electrode to deform the side wall. By changing the deformation direction of the side wall according to the polarity of the voltage, the volume of the ink chamber is expanded to suck ink from the ink supply unit, or the volume of the ink chamber is reduced to discharge the ink inside from the ink discharge port. It is.

[0003]

SUMMARY OF THE INVENTION The aforementioned Japanese Patent Application Laid-Open No. 63-2
A head body of an ink jet printer head having a structure disclosed in Japanese Patent No. 47051 is used in which at least one is formed by bonding a top plate to a substrate including an upper substrate and a lower substrate formed of a piezoelectric member with an adhesive. Have been. In the case of an ink jet printer head of this type, even if the thickness of the substrate and the top plate are different, the material is different, or even if an adhesive having a different coefficient of thermal expansion is used, it is a narrow serial type. No particular problem has occurred since the change in the overall shape, that is, the degree of warpage or undulation is small. However, for the purpose of increasing the printing speed and the like, development of a line type ink jet printer head whose entire length has been adjusted to the width of the paper has been studied. In the ink jet printer head of this type, since the width dimension is considerably large, when the thickness of the substrate and the top plate is different, the material is different, or when an adhesive having a different coefficient of thermal expansion is used, As shown in FIG. 6, warpage or undulation generated in the step of heating and bonding the substrate and the top plate may reach as much as 100 μm, which is a serious problem in practical use.

[0004] It is an object of the present invention to reduce the occurrence of warpage or undulation when a substrate and a top plate are heated and bonded to form a substrate.

[0005]

According to the first aspect of the present invention,
A substrate is formed by laminating at least one or more piezoelectric members polarized in the thickness direction, and a plurality of grooves parallel to each other and at least a part of the side walls formed by the piezoelectric members separating these grooves are equally spaced. The electrodes for applying a voltage to the piezoelectric members forming the side walls and the wiring patterns connected to these electrodes are formed on the substrate, and the top plate covering the upper part of the groove and the front part of the groove are formed on the substrate. In an inkjet printer head having a plurality of ink chambers formed by attaching a covering nozzle plate, the top plate is formed of a material having a thermal expansion coefficient equivalent to that of a piezoelectric member. Therefore,
When the substrate and the top plate are heat-bonded to form the substrate, even if the thickness of the substrate and the top plate are different, the materials are different, or even if an adhesive having a different coefficient of thermal expansion is used, It is possible to provide a head main body with less warpage and undulation.

According to a second aspect of the present invention, a substrate is provided in which a lower substrate and an upper substrate are formed of a piezoelectric member, and a top plate is formed of the same piezoelectric member as the substrate. Therefore, since the substrate and the top plate are made of a material having the same coefficient of thermal expansion, a head body with little warpage or undulation can be obtained.

According to a third aspect of the present invention, the top plate is made of an alloy containing iron-nickel, and is set to have a nickel content having a thermal expansion coefficient equivalent to that of the piezoelectric member. Therefore, it is easy to form a top plate having the same coefficient of thermal expansion as the substrate.

According to a fourth aspect of the present invention, the top plate is formed of a resin having a thermal expansion coefficient in a flow direction at the time of molding that is equal to a thermal expansion coefficient of the piezoelectric member. Therefore, the top plate having the same coefficient of thermal expansion as the substrate can be formed of resin.

[0009]

FIG. 1 shows a first embodiment of the present invention.
A description will be given with reference to FIG. FIG. 1 shows the overall structure of an ink jet printer head, in which a lower substrate 1 and an upper substrate 2 each composed of two piezoelectric members polarized in the thickness direction.
Are bonded so that their polarization directions are opposite to each other.
To form That is, an adhesive such as a heat-curable one-part epoxy adhesive is applied to one surface of the lower substrate 1 by screen printing to a uniform thickness of about 10 to 30 μm, and the upper substrate 2 is bonded.

By subjecting the substrate 3 thus formed to groove processing, the lower substrate 1 is moved from the upper surface of the upper substrate 2 to the lower substrate 1.
Are formed in parallel with a large number of grooves 4 reaching the inside of the substrate and a plurality of side walls 5 separating the grooves 4. This groove processing is performed using a diamond wheel of a dicing saw used for cutting an IC wafer or the like. These grooves 4 are formed in a shape that opens on the front side of the substrate 3 and closes the back side.
The dimensions of the groove 4 are determined according to the specifications of the ink jet printer head. For example, the depth is 0.2 to 1 mm, the width is 20 to 200 μm, and the length is about 5 to 500 mm.

An electrode 6 is formed on the inner surface of the groove 4 by electroless nickel plating. At this time, the upper substrate 2
The wiring pattern 7 continuous with the electrode 6 is simultaneously formed on the upper surface of the substrate. When the aqueous ink is used, the insulating film 8 is formed on the electrode 6 and the wiring pattern 7 (partly) at least in a portion that comes into contact with the ink. FIG. 2 shows a cross section of the groove 4 after the insulating film 8 is formed. If an electrodeposition paint is used to form the insulating film 8, the insulating film 8 is uniformly formed on the electrode 6 up to the inside of the fine groove 4 by contact with the solution of the electrodeposition paint.

Here, an electrode 6 and a wiring pattern 7 are formed, and a top plate 9 is formed on the substrate 3 on which the insulating film 8 is formed.
Are bonded to each other to form a head body 10, and the top opening 9 of the groove 4 is covered with the bonded top plate 9 to form a large number of ink chambers 11. On the inner surface of the top plate 9, there is formed a common ink chamber 12 intersecting with the ink chamber 11 and communicating with all the ink chambers 11.
An ink supply port 13 communicating with 2 is formed. Thus, the material of the top plate 9, the thermal expansion coefficient of the piezoelectric member is 2~6 × 10 _~ ⁶ / ℃, and has a similar thermal expansion coefficient and the thermal expansion coefficient of the piezoelectric member It is desirable. That, 7 × 10 _~ ⁶ / ℃ must be a material of the following thermal expansion coefficient as the material of the top plate 9 are the same piezoelectric member as the lower substrate 1 and the upper substrate 2 is used.
Then, the substrate 3 in which the lower substrate 1, the upper substrate 2, and the top plate 9 are bonded is put into an autoclave (not shown), and heated under pressure (120 ° C. × 2H, 1 to 5 kgf / cm ² ).
And cure the adhesive. The substrate 3 is mechanically pressed and placed in an oven with the pressurized jig heated and cured (120 ° C x
2H). The head body 10 having the top plate 9 bonded to the substrate 3 as described above has the same top plate 9 made of the same material as the lower substrate 1 and the upper substrate 2 made of a piezoelectric member, and thus has a warp or undulation due to a difference in thermal expansion coefficient. Can be reduced. The size of the substrate 3 is 140 mm × 40
In the case of mm, the desired value was obtained in which the warpage over a length of 140 mm was 10 μm or less as an actually measured value, compared to the conventional case where the undulation was 100 μm or more in the state shown in FIG.

[0013] Either an organic adhesive or an inorganic adhesive may be used as long as the ink used in the ink jet printer head has resistance, and the method of applying the adhesive may be other methods such as spin coater, spray coating, and brush coating. It can be selected together.

The curing temperature also varies depending on the adhesive used, but is about 40 to 200 ° C. Note that this temperature is a temperature that does not affect the polarization of the piezoelectric member (attention must be paid because the deterioration of the polarization starts at 200 ° C. or higher).

Next, a nozzle plate 16 having an ink discharge port 15 is bonded to the head main body 10 so as to cover the opening surface 14 at the tip end of the ink chamber 11. However, in order to bond the nozzle plate 16, the opening surface 14 must be a flat surface as a whole. However, as shown in FIG. 3A, there is a step due to a slight displacement between the substrate 3 and the top plate 9, or FIG.
As shown in (2), if there is an edge or sagging on either the substrate 3 or the top plate 9, a dent may be formed at the boundary of the opening surface 14, and the nozzle plate 16 is adhered with a uniform adhesive layer. It is impossible. That is, if there is such a step or a dent, when bonding the nozzle plate 16, it causes a bonding failure. For example, when an adhesive is used, it is necessary to apply the adhesive very thinly so that the ink chamber 11 and the ink discharge port 15 are not blocked with the adhesive. Can be. Conversely, if this portion is to be bonded, the thickness of the adhesive becomes large, and the ink chamber 11 and the ink discharge port 15 are blocked. In order to eliminate such steps and depressions, the substrate 3 and the top plate 9 are bonded and then cut at the same time, or the opening surface 14 is polished and flattened as shown in FIG.

In such a configuration, the ink discharging operation is performed as follows. First, in a state where ink is supplied to the ink chamber 11 of the head main body 10, the side walls 5 located on both sides of the ink chamber 11 are curved by shear mode deformation between the lower substrate 1 and the upper substrate 2 whose polarization directions are opposite to each other, and are gradually separated. Then, the ink is rapidly returned to the initial position, and the ink in the ink chamber 11 is pressurized to discharge ink droplets from the ink discharge port 15. At this time, in order to prevent crosstalk, the side wall 5 acting as a pressure generating means is driven so as to press the even-numbered ink chambers 11 and the odd-numbered ink chambers 11 alternately. Further, the side wall 5 is gradually deformed when ink is sucked and filled in the ink chamber 11, and is sharply deformed when the ink filled in the ink chamber 11 is pressurized. In addition, as described above, the ink ejection port 1
5 is formed in a tapered shape so that the inside is expanded and the outside is reduced in diameter, so that the ink pressurized in the ink chamber 11 is efficiently discharged.

Thus, the top plate 9 bonded to the substrate 3 is
As described above, both have the same coefficient of thermal expansion, and the occurrence of warpage and undulation based on the difference in the coefficient of thermal expansion is reduced. Therefore, when formed as a line type ink jet printer head, it can be manufactured with a good yield without warping or undulation, and a cheap, simple and highly reliable ink jet printer head can be provided.

Next, an iron-nickel alloy is used as a material of the nozzle plate 16. By appropriately selecting the nickel composition of the iron-nickel alloy, an alloy having a thermal expansion coefficient almost equal to or smaller than that of the substrate 3 made of a piezoelectric material can be obtained. The coefficient of thermal expansion of a typical piezoelectric material, 2 to 5 × 10 since _to ^6. The composition of nickel iron nickel alloy of the nozzle plate 16 in accordance with the thermal expansion coefficient of the piezoelectric material used 20-45% Adjust between. By this composition adjustment, it is possible to form the nozzle plate 16 having a thermal expansion coefficient similar to or smaller than the thermal expansion coefficient of the substrate 3.

The thickness of the nozzle plate 16 is 100 μm.
The following is assumed. By using a plate having such a thickness, the processing of the ink discharge port 15 becomes easy, and the degree of hole formation can be improved. As the processing of the ink discharge port 15, laser processing or press processing is effective. Of course, other processing methods may be used as long as required accuracy can be obtained.

Next, a second embodiment of the present invention will be described. The structure is similar to that of the first embodiment shown in FIGS.
And the same parts are denoted by the same reference numerals and description thereof will be omitted. In the present embodiment, the top plate 9 is
An alloy containing iron-nickel having a thermal expansion coefficient equivalent to that of the lower substrate 1 and the upper substrate 2 (having a thickness of 0.1 to 0.1)
(2.5 mm). Therefore, for example, the main component is 42 nickel-iron alloy has a thermal expansion coefficient of a is ^{_{4~5 × 10 ~ 6 / ℃,}} 29 nickel, 17 cobalt-iron alloy has a thermal expansion coefficient of 4.5 to 5 × 10 _to ⁶ / ° C., which is equivalent _{to a} coefficient of thermal expansion of the piezoelectric member of 2 to 6 × 10 _to ⁶ / ° C.

Specifically, the upper substrate 2 made of a piezoelectric member
42 nickel-iron alloy with the same thickness as
A top plate 9 were machined 4.5 × 10 _~ ⁶ / ℃) to a predetermined size, by bonding it to the substrate 3, it is possible to reduce occurrence of warpage or waviness. When the size of the substrate 3 was 140 mm × 40 mm and the warp and undulation were measured at a length of 140 mm, the size was 10 μm by the measurement method of FIG.
The following and desired values were obtained.

Next, a third embodiment of the present invention will be described. 1 to 4 as in the first embodiment.
And the same parts are denoted by the same reference numerals and description thereof will be omitted. In the present embodiment, the top plate 9 is made of a liquid crystal polymer (LCP), a polyphenyl sulfide (PP).
Are those formed by resins S), etc., the thermal expansion coefficient in the flow direction during molding is of less similar 7 × 10 _~ ⁶ / ℃ and the piezoelectric member. Such a liquid crystal polymer (LCP),
In a resin such as polyphenyl sulfide (PPS), the coefficient of thermal expansion in the direction of flow during molding differs greatly from that in the direction perpendicular thereto. That is, the coefficient of thermal expansion in the flow direction at the time of molding is considerably smaller than the coefficient of thermal expansion in the direction orthogonal to the flow direction. For this reason, the top plate 9 adhered to the upper surface of the substrate 3 has a longitudinal direction which is a flow direction at the time of molding, and a width in a direction orthogonal to the longitudinal direction is smaller than the width of the substrate 3. Thereby, in the long side direction, a state without warpage or undulation is obtained, and in the direction orthogonal thereto,
Even if the coefficient of thermal expansion is large, its width is small, so that warpage and undulation are suppressed as a whole.

[0023] Increasing the specific example, manufactured by Sumitomo Chemical Co. liquid crystal polymer (E5008, flow ^{_{direction: 1 × 10 ~ 6 / ℃}} ,
Flow direction and perpendicular direction: using a 64 × 10 _~ ⁶ / ℃) those formed into a predetermined shape as the top plate 9, which board 3
Adhered to. Thereby, the size of the substrate 3 is 140 mm
When the warp and swell were measured at a length of 140 mm at a size of × 40 mm, a desired value of 10 μm or less was obtained by the measurement method of FIG.

The top plate 9 is made of a material such as liquid crystal polymer (LCP) or polyphenyl sulfide (P).
The resin is not limited to a resin such as PS).
A material adjusted to a range of 10 _to ⁶ / ° C. or less may be used.

[0025]

According to the first aspect of the present invention, a substrate is formed by laminating at least one or more piezoelectric members polarized in the thickness direction, and at least a plurality of grooves parallel to each other are separated from the substrate. Partially formed side walls made of the piezoelectric member are formed at equal intervals, electrodes for applying voltage to the piezoelectric members forming the side walls, and wiring patterns connected to these electrodes are formed on the substrate, and the groove is formed. An ink jet printer head in which a plurality of ink chambers are formed by attaching a top plate covering the upper part of the groove and a nozzle plate covering the front part of the groove,
Since the top plate is formed of a material having a thermal expansion coefficient equivalent to that of the piezoelectric member, when the substrate and the top plate are heat-bonded to form the substrate, the thickness of the substrate and the top plate may be different or the material may be different. However, even if an adhesive having a different thermal expansion coefficient is used, it is possible to obtain a head body with less warpage and undulation.

According to a second aspect of the present invention, a substrate is provided in which a lower substrate and an upper substrate are formed by a piezoelectric member, and the top plate is formed by the same piezoelectric member as the substrate. Since the material has a thermal expansion coefficient, it has an effect that a head main body with less warpage and undulation can be obtained.

According to the third aspect of the present invention, the top plate is made of an alloy containing iron-nickel and is set to have a nickel content having a thermal expansion coefficient equivalent to that of the piezoelectric member. This has an effect that it is easy to form a top plate having a thermal expansion coefficient.

According to a fourth aspect of the present invention, since the top plate is formed of a resin having a thermal expansion coefficient in the flow direction at the time of molding that is equal to the thermal expansion coefficient of the piezoelectric member, the top plate has the same thermal expansion coefficient as the substrate. Can be formed also by a resin.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view showing the entire structure of an ink jet printer head according to a first embodiment of the present invention.

FIG. 2 is a vertical sectional front view showing a state where an electrode and an insulating film are formed in a groove.

FIG. 3 shows a positional relationship between a substrate and a top plate.
(a) shows a state in which both are shifted, (b) shows a state in which a dent is generated between the two, and (c) shows a state in which the opening surface is finished flat.

FIG. 4 is an exploded perspective view of a substrate and a top plate.

FIG. 5 is a perspective view of a head body in which a top plate is bonded to a substrate.

FIG. 6 is an explanatory diagram showing a warped state of the head main body.

[Explanation of symbols]

 Reference Signs List 1 lower substrate 2 upper substrate 3 substrate 4 groove 5 side wall 6 electrode 7 wiring pattern 9 top plate 11 ink chamber 16 nozzle plate

Claims (4)

[Claims] A substrate is formed by laminating at least one or more piezoelectric members polarized in a plate thickness direction, and a plurality of grooves parallel to each other on the substrate and at least a part separating the grooves is formed of the piezoelectric member. Forming side walls at equal intervals, forming an electrode for applying a voltage to the piezoelectric member forming the side wall and a wiring pattern connected to these electrodes on the substrate;
In an ink jet printer head having a plurality of ink chambers formed by attaching a top plate covering the upper part of the groove and a nozzle plate covering a front part of the groove, the top plate is made of a material having a thermal expansion coefficient equivalent to that of a piezoelectric member. An ink jet printer head characterized by being formed. 2. The ink jet printer head according to claim 1, wherein a substrate in which a lower substrate and an upper substrate are formed by a piezoelectric member is provided, and a top plate is formed by the same piezoelectric member as the substrate. 3. The top plate is made of an alloy containing iron-nickel, and is set to have a nickel content having a thermal expansion coefficient equivalent to that of the piezoelectric member.
The ink jet printer head as described in the above. 4. The ink jet printer head according to claim 1, wherein the top plate is formed of a resin having a thermal expansion coefficient in a flow direction at the time of molding that is equal to a thermal expansion coefficient of the piezoelectric member.