JP3815228B2 - Piezoelectric inkjet printer head - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a configuration of a piezoelectric ink jet printer head.
[0002]
[Prior art]
In the prior art on-demand type piezoelectric inkjet printer head, as described in JP-A-9-141856, a plurality of nozzles, pressure chambers (ink cavities) for the respective nozzles, and pressure chambers are provided. An energy generating unit such as a piezoelectric element for selectively driving corresponding to the pressure chamber portion via a diaphragm serving as a diaphragm on the back surface of a manifold plate having an ink manifold that communicates and supplies ink An ink jet printer head having a cover plate having a fixed structure is disclosed.
[0003]
When the piezoelectric element is driven and vibrated, the pressure chamber is selectively pressurized through the diaphragm, the pressure is transmitted to the corresponding nozzle hole, and printing is performed by ejecting ink droplets. . At this time, the pressure wave acting on the pressure chamber has not only a forward component toward the nozzle hole but also a backward component toward the ink manifold. Because of the backward component, so-called crosstalk occurs, so that the backward component is intended to be absorbed and relaxed in the damper chamber formed in the cover plate.
[0004]
In the meantime, in the Japanese Patent Application No. 2000-62106, the applicant of the present invention laminated two manifold plates each having a manifold on a base plate having a pressure chamber, and a nozzle plate on the lower surface of the lower manifold plate. The cavity plate unit is configured by laminating and fixing each of the plates via an adhesive, and the piezoelectric plate is placed on the upper surface of the base plate in the cavity plate unit so as to face the position corresponding to the location of each pressure chamber. A plate-like piezoelectric actuator incorporating an element was proposed.
[0005]
With this configuration, there is an effect that the ink jet head can be made compact because the pressure chamber and the manifold can be arranged at positions where they overlap in the area of the cavity plate unit in plan view.
[0006]
[Problems to be solved by the invention]
However, in the above-described configuration, the cavity plate unit is formed by laminating a plurality of plates made of a highly rigid metal plate or the like. Therefore, when the piezoelectric element is selectively driven, the active portion of the displacement by the piezoelectric element is piezoelectric. The cavity plate unit bonded to the piezoelectric actuator is also elastically deformed as it is elastically deformed so as to bend the plane of the plate portion of the actuator, but it is not necessary if the plate of the cavity plate unit has high rigidity ( The pressure chamber (not selected) is affected by the elastic deformation, and the so-called cross talk phenomenon that affects the ejection of ink from the pressure chamber occurs. There were problems such as splashing.
[0007]
It is a technical object of the present invention to provide an ink jet printer head that solves such problems.
[0008]
[Means for Solving the Problems]
In order to achieve this technical problem, the invention described in claim 1 includes a cavity plate having a plurality of nozzles and pressure chambers for each nozzle arranged in a row in a first direction, and each pressure chamber. In the piezoelectric ink jet printer head, which is formed by laminating a piezoelectric actuator having an active part that can be selectively driven and ejecting ink, the cavity plate unit includes a base plate provided with the pressure chamber, and an ink supply source. A manifold plate provided with a manifold chamber for replenishing each pressure chamber after the ink from the ink is stored, a spacer plate interposed between the manifold plate and the base plate, and a nozzle communicating with the pressure chamber. The nozzle plate is laminated, and the manifold chamber is formed in the manifold plate. While it formed so as to extend in the arrangement direction of the serial plurality of pressure chambers, the spacer plate, the open recess in the manifold chamber side leaving a thin portion over substantially the entire length of the manifold chamber, and said column It is formed so as to straddle all of the plurality of pressure chambers arranged in a shape .
[0009]
According to a second aspect of the present invention, in the ink jet printer head according to the first aspect, the recess is formed to have substantially the same size as the manifold chamber.
[0010]
According to a third aspect of the present invention, in the inkjet printer head according to the first aspect, the longitudinal direction of the manifold chamber is arranged in parallel with the arrangement direction of the plurality of pressure chambers, and the recess is formed by the manifold. It is formed in the shape of a long groove extending over almost the entire length of the chamber and over all of the plurality of pressure chambers.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 7 show a piezoelectric ink jet printer head of the present invention. In these drawings, a flexible flat cable 40 is laminated and bonded to the upper surface of a plate-type piezoelectric actuator 20 to be bonded to the cavity plate unit 10 with an adhesive for connection to an external device. It is assumed that ink is ejected downward from the nozzle 54 opened on the lower surface side of the cavity plate unit 10.
[0012]
The cavity plate unit 10 according to the first embodiment is configured as shown in FIGS. That is, it is a structure in which five thin plates of the nozzle plate 43, the lower layer plate 11, the manifold plate 12, the spacer plate 13, and the base plate 14 are laminated by bonding and laminated. In the embodiment, each of the plates 11, 12, 13, 14 excluding the nozzle plate 43 is made of 42% nickel alloy steel plate and has a thickness of about 50 μm to 150 μm. The nozzle plate 43 is provided with nozzles 54 for ejecting ink with a small diameter along a first direction (long side direction) of the nozzle plate 43 in a two-row staggered arrangement. That is, a large number of nozzles 54 are formed in a staggered arrangement at intervals of a minute pitch P along two reference lines 43a and 43b parallel to the first direction of the nozzle plate 43.
[0013]
The pressure chambers 16 to be described later corresponding to the nozzles 54 and the active portions of the piezoelectric elements in the piezoelectric actuator 20 to be described later are arranged so as to overlap and correspond to each other in plan view of each plate. The pressure chambers 16 are formed so as to extend in a direction intersecting (orthogonal) with the first direction, and the row of pressure chambers 16 extends along the first direction. In the manifold plate 12, a pair of manifold chambers 12a and 12a serving as ink passages are formed so as to extend along both sides of the row of the nozzles 54. In this case, each manifold chamber 12a extends so as to overlap the row of pressure chambers 16 and straddle each pressure chamber 16 in plan view of the plate (see FIGS. 3 and 4).
[0014]
Each manifold chamber 12a in the manifold plate 12 is sandwiched between the lower layer plate 11 and the upper spacer plate 13 and has a structure in which the manifold chamber 12a is sealed by being laminated.
[0015]
The base plate 14 is provided with a plurality of narrow pressure chambers 16 extending in a second direction (short side direction) perpendicular to the center line along the long side (first direction). Has been. And when the parallel longitudinal reference lines 14a, 14b are set on both the left and right sides with the center line in between, the tip 16a of the pressure chamber 16 on the left side of the center line is located on the left reference line 14a, Conversely, the tip 16a of the pressure chamber 16 on the right side of the longitudinal center line is positioned on the right reference line 14b on the right side, and the tips 16a of the left and right pressure chambers 16 are alternately arranged. The pressure chambers 16 are alternately arranged so as to extend in opposite directions to each other (see FIG. 4).
[0016]
The tip 16a of each pressure chamber 16 has a small diameter formed in the staggered nozzles 54 of the nozzle plate 43 in the staggered arrangement in the spacer plate 13, the manifold plate 12 and the lower layer plate 11 as well. The through holes 17 and 17 communicate with each other. On the other hand, the other end 16 b of each pressure chamber 16 communicates with the manifold chamber 12 a in the manifold plate 12 through through holes 18 drilled in the left and right side portions of the spacer plate 13. As shown in FIG. 4, the other end 16b is recessed so as to open only on the lower surface side of the base plate. Further, a filter 29 for removing dust in the ink supplied from the ink tank thereabove is stretched on the upper surface of the supply hole 19a formed in one end portion of the uppermost base plate.
[0017]
As a result, the ink that has flowed into the left and right manifold chambers 12a and 12a from the ink supply source (ink tank) (not shown) through the supply holes 19a and 19b drilled in one end of the base plate 14 and the spacer plate 13 is obtained. After being distributed from the ink passages 12 a through the through holes 18 into the pressure chambers 16, the nozzles corresponding to the pressure chambers 16 are passed from the pressure chambers 16 through the through holes 17. 54 (see FIGS. 3 and 6).
[0018]
A thin-walled recess opened to the manifold chamber 12 a side is formed on the lower surface of the spacer plate 13 so as to straddle at least the plurality of pressure chambers 16. In the first embodiment, as shown in FIGS. 4 and 7, the longitudinal direction (extending direction) of each manifold chamber 12 a extends in parallel to the arrangement direction (first direction) of the plurality of pressure chambers 16. The thin-walled recess (groove) 55 is formed in a long groove shape that extends over substantially the entire length of the manifold chamber 12a and spans all of the plurality of pressure chambers 16 in each row. It is what. In the embodiment, two rows of recesses 55 are formed for each manifold chamber 12a.
[0019]
In another embodiment, as shown in FIG. 8, the thin-walled recess 56 is formed to have substantially the same size as the manifold chamber 12a and the shape in plan view.
[0020]
These thin-walled recesses 55 (56) are designed to slightly lower the rigidity so that the elastic deformation of the portion of the spacer plate 13 corresponding to the active portion of the piezoelectric element is appropriately performed as will be described later. is there.
[0021]
On the other hand, as shown in FIGS. 2 and 5, the piezoelectric actuator 20 has a structure in which nine piezoelectric sheets 21a, 21b, 21c, 21d, 21e, 21f, 21g, 22, 23 are laminated, Of the lowermost piezoelectric sheet 22 and the upper surfaces (wide surfaces) of the odd-numbered piezoelectric sheets 21b, 21d, and 21f counted upward from the lower piezoelectric sheet 22 are narrow for each location of each pressure chamber 16 in the cavity plate unit 10. The individual electrodes 24 are formed in a row along a first direction (long side direction), and each individual electrode 24 has a long side of each piezoelectric sheet along a second direction orthogonal to the first direction. It extends to the vicinity of the edge. A common electrode 25 common to the plurality of pressure chambers 16 is formed on the upper surfaces (wide surfaces) of the even-numbered piezoelectric sheets 21a, 21c, 21e, and 21g from the bottom.
[0022]
In the embodiment, the width of each individual electrode 24 is set slightly narrower than the wide portion of the corresponding pressure chamber 16 in plan view.
[0023]
On the other hand, since the pressure chambers 16 are arranged in two rows along the first direction (long side) on the short side central portion side of the base plate 14, the common electrodes 25 are arranged in two rows. The pressure chambers 16 and 16 are integrally formed to have a substantially rectangular shape in plan view extending along the long side at the center in the short side direction of the even-numbered piezoelectric sheets 21a, 21c, 21e and 21g. In the vicinity of the end edges of the pair of short sides of the even-numbered piezoelectric sheets 21a, 21c, 21e, 21g, lead portions 25a, 25a extending substantially over the entire length of the end edges are integrally formed.
[0024]
The individual electrodes 24 are disposed on the surface of the even-stage piezoelectric sheets 21a, 21c, 21e, and 21g near the edge of the long side where the common electrode 25 is not formed. The dummy individual electrodes 26 having the same width as the individual electrodes 24 and a short length are formed at the same vertical position (corresponding position). In this case, as shown in FIG. 5, the end of each dummy individual electrode 26 seems to have a gap with an appropriate gap dimension with respect to the side edge of the common electrode 25 in the first direction (the direction along the long side). Separated. The length of every other layer of the dummy individual electrode 26 is set to be long and short like L2 and L3 (<L2), and the pattern breaks between the end of the dummy individual electrode 26 and the side edge of the common electrode 25 are cut. The position may be shifted in the second direction (short-side direction) of the piezoelectric sheet every other stacked piezoelectric sheet. In the embodiment, the length L2 of the dummy individual electrode 26 in the second layer (piezoelectric sheet 21a) and the sixth layer (piezoelectric sheet 21e) from the bottom is set to the fourth layer (piezoelectric sheet 21c) and the eighth layer. The gap is set to be longer than the length L3 of the dummy individual electrode 26 in the layer (piezoelectric sheet 21g).
[0025]
On the other hand, on the upper surface (wide surface) of the lowermost piezoelectric sheet 22 and the odd-numbered piezoelectric sheets 21b, 21d, 21f counted upward (positions corresponding to the leading portions 25a, 25a (the same vertical position, piezoelectric sheet) The dummy common electrode 27 is formed in the vicinity of the edge of the short side of the pair.
[0026]
On the upper surface of the uppermost top sheet 23, a surface electrode 30 for each of the individual electrodes 24 and a surface electrode 31 for the common electrode 25 are provided along the edge of the long side. (See FIG. 2).
[0027]
Further, except for the lowermost piezoelectric sheet 22, all the other piezoelectric sheets 21a, 21b, 21c, 21d, 21e, 21f, and 21g and the top sheet 23 have the surface electrodes 30 and the corresponding ones. A through hole 32 is formed so that the individual electrode 24 and the dummy individual electrode 26 at the same position (the same vertical position) communicate with each other. Similarly, the at least one surface electrode 31 (in the embodiment, the surface electrode 31 at the four corners of the top sheet 23) and the corresponding common electrode 25 or the lead portion 25a at the corresponding position (the same vertical position) are provided. Through holes 33 are formed so as to communicate with each other, and the individual electrodes 24 of each layer and the surface electrodes 30 corresponding to the layers are electrically connected to each other through the conductive material filled in the through holes 32 and 33. In the same manner, the common electrodes 25 of each layer and the surface electrode 31 at the corresponding position are electrically connected to each other.
[0028]
As a result, the plurality of piezoelectric sheets 21 and the top sheet that are stacked one above the other are electrically connected to the location of the surface electrode 30 with the individual electrodes 24 and the dummy individual electrodes 26 at the same upper and lower positions. The common electrode 25 and the dummy common electrode 27 are electrically connected to the surface electrode 31 (see FIG. 6).
[0029]
Then, an adhesive sheet 41 made of an ink non-permeable synthetic resin material as an adhesive layer is pasted in advance on the entire lower surface (the wide surface facing the pressure chamber 16) of the plate-type piezoelectric actuator 20 having such a configuration. Next, each individual electrode 24 in the piezoelectric actuator 20 is bonded and fixed to the cavity plate unit 10 so as to correspond to each pressure chamber 16 in the cavity plate unit 10 (FIG. 7, (See FIG. 8). Further, when the flexible flat cable 40 is pressed against the upper surface of the piezoelectric actuator 20, various wiring patterns (not shown) in the flexible flat cable 40 become the surface electrodes 30, 31. Electrically joined to the
[0030]
The material of the adhesive layer such as the adhesive sheet 41 is at least ink impermeable and has electrical insulation, and is mainly composed of a nylon or dimer acid based polyamide resin. Polyamide-based hot-melt adhesives or polyester-based hot-melt adhesives may be used. However, after applying a polyolefin-based hot-melt adhesive to the wide surface of the piezoelectric actuator 20, Alternatively, the cavity plate unit 10 may be bonded and fixed. The thickness of the adhesive layer is about 1 μm.
[0031]
In this configuration, by applying a voltage between any individual electrode 24 among the individual electrodes 24 in the piezoelectric actuator 20 and the common electrode 25, the individual electrode 24 to which the voltage is applied in the piezoelectric sheet 21 is applied. It becomes an active part of the piezoelectric element in which distortion in the stacking direction due to piezoelectricity occurs in the corresponding part. The active portion of the piezoelectric element in the piezoelectric actuator 20 and the pressure chamber 16 for each nozzle 54 overlap each other in plan view of each plate.
[0032]
Then, the internal volume of the pressure chamber 16 corresponding to each individual electrode 24 is reduced by the distortion of the active portion, so that the ink in the pressure chamber 16 is ejected from the nozzle 54 in the form of droplets, Predetermined printing is performed (see FIG. 8).
[0033]
As described above, the adhesive layer is interposed between the piezoelectric actuator 20 and the cavity plate unit 10 so as to cover all the pressure chambers 16, so that the adhesive layer does not allow ink to permeate. The piezoelectric actuator 20 and the cavity plate unit 10 can be firmly fixed at the same time. And since it is an adhesive agent, the thickness of the layer can be formed extremely thin compared with the conventional diaphragm plate, and there exists an effect that an inkjet printer head can be manufactured at low cost. Further, since the piezoelectric actuator 20 is configured by laminating the piezoelectric sheets 21 and 22 extending over the plurality of pressure chambers 16, the rigidity of the entire piezoelectric actuator 20 is increased, and vibration like a conventional diaphragm plate may occur. In addition, it is possible to drive at a high frequency.
[0034]
When the active portion in the piezoelectric actuator 20 is selectively driven, the cavity plate bonded to the piezoelectric actuator is elastically deformed so that the active portion curves the plane of the plate portion of the piezoelectric actuator 20. Although the unit 10 is also elastically deformed, in the present invention, the spacer plate 13 in the cavity plate unit 10 is provided with a concave groove 55 so as to straddle the plurality of pressure chambers 16, thereby providing spacers at locations corresponding to the pressure chambers 16. When the thickness of the plate 13 is partially reduced and the rigidity is partially reduced, the elastic deformation is reduced with respect to the pressure chamber 16 that is not necessary (not selected), and the ink from the pressure chamber 16 is reduced. The so-called cross talk phenomenon that affects the ejection of ink occurs, and the ink droplets to be ejected are splashed. An effect which can be eliminated phenomenon becomes.
[0035]
In the above embodiments, one or a plurality of long grooves 55 were formed so as to extend in a direction perpendicular to the arrangement direction of the pressure chamber 16 (see FIG. 7), as shown in FIG. 8, manifold a recess 56 of substantially the same plan view shape as the plan view shape of the chamber 12a, may be formed on the lower surface of the spacer plate 13 (the side facing the manifold chamber 12a).
[0036]
[Operation and effect of the invention]
As described above, the invention according to claim 1 selects a plurality of nozzles and a cavity plate in which the pressure chambers for each nozzle are arranged in a row in the first direction, and each pressure chamber. In the piezoelectric ink jet printer head formed by laminating a piezoelectric actuator having an active portion that can be driven in an ink and ejecting ink, the cavity plate unit is connected to a base plate provided with the pressure chamber and an ink supply source. A manifold plate provided with a manifold chamber for replenishing each pressure chamber after storing ink, a spacer plate interposed between the manifold plate and the base plate, and a nozzle communicating with the pressure chamber were provided. And a plurality of manifold chambers in the manifold plate. While formed so as to extend in the arrangement direction of the pressure chamber, said spacer plate, the open recess in the manifold chamber side leaving a thin portion over substantially the entire length of the manifold chamber, and arranged in said rows It is formed so as to straddle all of the plurality of pressure chambers .
[0037]
Although it is possible to reduce the overall thickness of each plate constituting the cavity plate unit to reduce the rigidity of the cavity plate unit as a whole, in order to secure the capacity of the pressure chamber and the manifold chamber, It is necessary to ensure the thickness of the manifold plate, and if the plate thickness of the plates on both sides is too thin, there is a problem that the rigidity of the entire cavity plate unit becomes too low. Therefore, as in the present invention, only a part of the spacer plate is thinned, and corresponds to the active portion of the piezoelectric actuator, and the spacer facing the manifold chamber is a position that does not affect the capacity of the pressure chamber. It was decided to place a recess on one side of the plate. Since the thin recesses are formed so as to extend over all of the plurality of pressure chambers arranged in the row , the presence of these recesses hinders the flow of ink in the manifold chambers. In addition, the rigidity in the direction of elastic deformation so that the active portion is curved can be reduced.
[0038]
Further, the invention according to claim 2 is the ink jet printer head according to claim 1, wherein the recess is formed to have substantially the same size as the manifold chamber. As a result, the effect of preventing the flow of ink in the manifold chamber is increased.
[0039]
According to a third aspect of the present invention, in the inkjet printer head according to the first aspect, the longitudinal direction of the manifold chamber is arranged in parallel with the arrangement direction of the plurality of pressure chambers, and the recess is formed by the manifold. Since it is formed in a long groove shape over almost the entire length of the chamber and over all of the plurality of pressure chambers , the presence of this recess does not hinder the flow of ink in the manifold chamber, and The effect that the rigidity in the direction of elastic deformation so that the active portion is curved can be further improved can be improved.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view showing a piezoelectric inkjet printer head according to an embodiment of the present invention.
FIG. 2 is an enlarged perspective view showing one end portions of a cavity plate unit and a piezoelectric actuator.
FIG. 3 is an exploded perspective view of a cavity plate unit.
FIG. 4 is a partially enlarged perspective view of a cavity plate unit.
FIG. 5 is an exploded perspective view of a piezoelectric actuator.
6 is an enlarged side sectional view of the piezoelectric ink jet printer head taken along line VI-VI in FIG.
FIG. 7 is a plan view showing a positional relationship among the concave grooves, the manifold chambers, and the pressure chambers in the first embodiment.
FIG. 8 is a partially cutaway perspective view showing an arrangement relationship among a recessed groove, a manifold chamber, and a pressure chamber in the second embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Cavity plate unit 11 Lower layer plate 12 Manifold plate 12a Manifold chamber 13 Spacer plate 14 Base plate 16 Pressure chamber 20 Piezoelectric actuator 21a, 21b, 21c, 21d, 21e, 21f, 21g, 22 Piezoelectric sheet 23 Top sheet 24 Individual electrode 25 Common electrode 26 Dummy Individual Electrode 27 Dummy Common Electrode 30, 31 Surface Electrode 32, 33 Through Hole 55 Concave Groove 56 Concave 43 Nozzle Plate 54 Nozzle

Claims (3)

Cavity plate having a plurality of nozzles and pressure chambers for each nozzle arranged in a row in a first direction, and a piezoelectric actuator having an active portion that can be selectively driven for each pressure chamber and ejecting ink In the piezoelectric inkjet printer head formed by laminating
The cavity plate unit includes a base plate provided with the pressure chamber, a manifold plate provided with a manifold chamber for replenishing each pressure chamber after storing ink from an ink supply source, the manifold plate and the base plate, And a spacer plate interposed between the pressure chambers and a nozzle plate provided with a nozzle communicating with the pressure chamber, and the manifold chamber extends on the manifold plate in the arrangement direction of the plurality of pressure chambers. On the other hand, the spacer plate is provided with a recess opened to the manifold chamber side, leaving a thin portion, over almost the entire length of the manifold chamber and in all of the plurality of pressure chambers arranged in a row. An ink jet printer head formed so as to straddle. The inkjet printer head according to claim 1, wherein the recess is formed to have substantially the same size as the manifold chamber. The longitudinal direction of the manifold chamber is arranged in parallel with the arrangement direction of the plurality of pressure chambers, and the recess extends over almost the entire length of the manifold chamber and spans all of the plurality of pressure chambers in each row. 2. The ink jet printer head according to claim 1, wherein the ink jet printer head is formed in such a long groove shape.

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