JP2004322505A - Ink jet recording head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink jet recording head having a piezoelectric actuator in which high quality printing can be ensured by suppressing a variation in ejection speed or volume of an ink drop. <P>SOLUTION: The ink jet head comprises a plurality of piezoelectric actuators where the piezoelectric oscillator has one end secured to a supporting substrate and the other free end, and a pressure chamber communicating with a plurality of orifice openings and storing ink. Volume of the pressure chamber is inflated or contracted by the forward end of the piezoelectric actuator on the free end side and an ink drop is ejected from the orifice opening to the outside. The thickness of the supporting substrate is set thinner than the thickness of the piezoelectric oscillator. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ink jet recording apparatus that forms an ink image on a recording medium by causing ink droplets to fly by displacement generated by a piezoelectric actuator.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a piezoelectric vibrator-type inkjet head that changes the pressure of ink in a pressure chamber using a piezoelectric actuator and ejects ink droplets from an orifice has been known (for example, see Patent Document 1).
[0003]
Further, there is known an ink jet head using a laminated piezoelectric vibrator formed by alternately laminating a piezoelectric material and a conductive material in layers, respectively (for example, see Patent Document 2). FIG. 8 (perspective view) and FIG. 9 (partial sectional view) show an example of this conventional ink jet head.
The ink jet head includes an orifice plate 32 in which an orifice 31 is formed, a chamber plate 34 in which a pressure chamber 33 is formed, a restrictor plate 36 in which a restrictor 35 is formed, a diaphragm 37 and a filter section 38. A diaphragm 41, a housing 41 in which a common ink passage 40 is formed, and a piezoelectric actuator 43. The piezoelectric actuator 43 has one end face of the piezoelectric vibrator 44 joined to a support substrate 47 formed of a ceramic plate, and arranges the other end face of the piezoelectric vibrator 44 on the vibration plate 37 so as to face the orifice 31, respectively. The vibration plate 37 and the piezoelectric vibrator 44 are brought into contact with an adhesive 42. Further, the individual electrode 48 and the common electrode 49 are electrically connected to the external electrode 45 of the piezoelectric vibrator 44 via the conductive adhesive 46, respectively.
[0004]
The ink is supplied from an ink tank (not shown) to the common ink passage 40 via an ink introduction pipe 51.
[0005]
In order to eject ink droplets from the inkjet head, an external drive power supply (not shown) applies an electric signal to the individual electrode 48 and the common electrode 49 provided on the piezoelectric actuator 43 through the through hole 50, and the piezoelectric vibration is applied. The child 44 is displaced. The displacement of the piezoelectric vibrator 44 causes a change in the volume of the pressure chamber 33 via the vibration plate 37, and a change in the pressure of the ink filled in the pressure chamber 33. This pressure change causes the ink to be ejected from the orifice 31 as ink droplets.
[0006]
The ink jet head is formed by bonding or joining thin plates (orifice plate 32, chamber plate 34, restrictor plate 36, and diaphragm plate 39) in order to increase the density and miniaturization of orifices for discharging ink droplets. It is manufactured by combining an ink flow path member 52 and a piezoelectric actuator 43 in which piezoelectric vibrators 44 diced according to the arrangement of the orifices 31 are arranged in a row. Since the piezoelectric actuator 43 is in contact with the vibration plate 37, it is inserted into the opening 53 of the housing 41.
[0007]
In the above-described configuration of the ink jet head, in order to ensure stable driving of the piezoelectric actuator 43, electrical connection between the external electrode 45 of the piezoelectric vibrator 44 and the individual electrodes 48 and the common electrode 49 of the support substrate is ensured. It is very important. However, since the above-described piezoelectric actuator 43 has the piezoelectric vibrator 44 adhered to the end surface of the support substrate 47, a large amount of conductive material is required for the electrical connection between the external electrode 45 and the individual electrodes 48 and the common electrode 49 of the support substrate. It is necessary to apply the adhesive 46, and it is difficult to maintain conduction. As a method to solve this, when bonding the piezoelectric vibrator to the end surface of the support substrate, the piezoelectric vibrator and one surface of the support substrate are bonded so that the surface perpendicular to the bonding surface is continuous, and the electrode is attached to the continuous surface. It has been proposed to form it (see, for example, Patent Document 3).
[0008]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 1-115638 (page 2, FIG. 2)
[Patent Document 2]
JP-A-2002-96464 (page 5, FIGS. 1 and 2)
[Patent Document 3]
Patent No. 3206214 (page 7, FIG. 7)
[0009]
[Problems to be solved by the invention]
However, when a method of bonding the piezoelectric vibrator and one surface of the support substrate so as to be continuous and forming an electrode on the continuous surface is adopted, in addition to the thickness of the piezoelectric vibrator 44 and the support substrate 47, The width of the conductive adhesive 46 for electrically connecting the electrodes 45 and the electrodes (48, 49) of the support substrate 47 becomes excessively large by the thickness of the conductive adhesive 46. As a result, the entire width of the piezoelectric actuator 43 becomes large. Therefore, the opening 53 of the housing 41 is in contact with the housing when the piezoelectric actuator 43 is inserted into the housing 41, and further, the housing 41 after the piezoelectric actuator 43 is incorporated in the housing and the electrodes (45, 48, 49, ) And the conductive adhesive 46, the frontage of the opening 53 of the housing 41 (the width A shown in FIG. 9) must be formed as wide as possible. However, when the opening 53 is widened, the rigidity of the ink flow path member 52 that forms the flow path, such as the orifice plate 32, the chamber plate 34, and the restrictor plate 36, at the position facing the opening 53 becomes weak, and the piezoelectric vibrator When the plate 44 is displaced, these plates are deformed, and the displacement of the piezoelectric vibrator 44 is not sufficiently transmitted to the pressure chamber 33, and further, the displacement of the piezoelectric vibrator is transmitted to the adjacent pressure chamber. A problem arises in that the amount differs for each orifice.
[0010]
When the width of the support substrate 47 (width B shown in FIG. 9) is larger than the width of the piezoelectric vibrator 44 of the piezoelectric actuator 43 (width C shown in FIG. 9), the piezoelectric vibrator 44 of the piezoelectric actuator 43 is supported. When applied to the end face of the support substrate 47 to adhere to the substrate 47, careless handling often causes chipping at corners. When a chip is generated in a part of the piezoelectric vibrator 44, the mass and the shape of the piezoelectric vibrator 44 at the part change, and the mechanical vibration mode in the displacement direction of the piezoelectric vibrator 44 changes. As a result, the speed and amount of ink droplets continuously ejected from the orifice 31 of the piezoelectric actuator 43 in which the chip is generated differ from the speed and amount of ink droplets ejected from the other normal orifices 31 and are different from those in the inkjet head. Causes the variation of Further, when the chip is generated, the external electrode 45 is peeled off, so that it is necessary to apply a larger amount of the conductive adhesive 46 in order to surely connect to the external electrode 45. For this reason, there has been a problem that the entire width of the piezoelectric actuator 43 is further increased.
[0011]
The present invention solves such a problem, and an object of the present invention is to reduce a change in the ejection speed and the amount of ink droplets ejected for each orifice of an inkjet head in an inkjet head having a piezoelectric actuator. It is an object of the present invention to provide an ink jet recording head that can perform the above.
[0012]
[Means for Solving the Problems]
In order to solve the above problems, the invention according to claim 1 of the present invention provides a plurality of piezoelectric actuators having one end of a piezoelectric vibrator fixed to a support substrate and the other end being a free end, a plurality of orifices, and the plurality of orifices. A flow path member having a pressure chamber for storing ink provided corresponding to each of the orifices; and a housing for holding the flow path member; In the ink jet head having the free ends of the vibrators, the width of the support substrate is smaller than the width of the piezoelectric vibrator.
[0013]
According to a second aspect of the present invention, there is provided the laminated piezoelectric vibrator according to the first aspect, wherein the piezoelectric vibrator is formed by alternately laminating a piezoelectric material and an internal electrode material in layers. When the width of the active portion of the laminated piezoelectric vibrator is Wa and the width of the inactive portion is Wn, the width T of the support substrate is configured to satisfy Wa ≦ T <Wa + 2 × Wn. It is characterized by.
[0014]
According to a third aspect of the present invention, in the first aspect of the present invention, a step is provided near the fixed portion of the piezoelectric vibrator to the support substrate so as to have a width substantially equal to the width of the support substrate. It is characterized by the following.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an example of the present invention will be described with reference to the drawings.
FIG. 1 is an exploded perspective view for explaining the structure of the main part of the ink jet head of the present invention. In the figure, reference numeral 2 denotes an orifice plate on which a plurality of orifices 1 are formed. The processing accuracy of the opening shape of the orifice 1 greatly affects the ink ejection characteristics of the ink jet head. In order to keep these orifice accuracy variations low among a plurality of orifices 1, the method of manufacturing the orifice plate 2 requires high processing accuracy. For this reason, the orifice plate 2 is formed by a precision press method of stainless steel, a laser processing method, electroforming of nickel, or the like.
[0016]
A chamber plate 4 in which a pressure chamber 3 is formed in the orifice plate 2, and a restrictor plate 6 in which an ink supply path 10 and the pressure chamber 3 are connected to form a restrictor 5 for controlling the flow of ink into the pressure chamber 3. Are positioned and joined.
[0017]
Further, a vibration plate 7 serving as an elastic wall for efficiently transmitting the pressure of the piezoelectric actuator 13 to the pressure chamber, and a filter unit 8 for removing dust and the like in the ink flowing into the restrictor 5 from the common ink passage 10 are formed. The diaphragm plate 9 having elasticity and the housing 11 in which the common ink passage 10 is formed are similarly positioned and joined.
[0018]
The chamber plate 4, restrictor plate 6, and diaphragm plate 9 are made by a stainless steel etching method or a nickel material electroforming method.
[0019]
The housing 11 is formed by cutting a stainless steel material or the like, and is joined to an ink introduction pipe 21 for leading ink to the common ink passage 10.
[0020]
A piezoelectric actuator 13 including a plurality of piezoelectric vibrators 14 and a support substrate 17 for fixing the piezoelectric vibrators 14 is inserted through an opening 23 of the housing 11 and joined.
[0021]
Here, in the present invention, the thickness of the support substrate 17 of the piezoelectric actuator 13 is made smaller than the thickness of the piezoelectric vibrator 14, and the overall width is made smaller. A piezoelectric vibrator 14 is arranged on an end face of the support substrate 17 so as to correspond to each of the pressure chambers 3, and individual electrodes 18 and a common electrode 19 are pattern-printed on a side surface of the support substrate 17. The common electrode 19 is wired to the opposite side of the support substrate 17 by a through hole 20 provided in the support substrate 17. Therefore, the external electrodes 15 of the piezoelectric vibrator 14 can be wired such that the individual electrodes 18 and the common electrodes 19 of the support substrate 14 are paired from both sides. Further, the individual electrodes 18 and the common electrode 19 of the support substrate 17 and the external electrode 15 of the piezoelectric vibrator are electrically connected by a conductive adhesive 16. As a result, an electric signal independent of an external drive circuit (not shown) is sent from the electric wiring cable (not shown) to the individual electrodes 18 and the common electrode 19 of the support substrate 17, and further through the conductive adhesive 16. When a selective electric signal is applied to the piezoelectric vibrator 14 from an external drive circuit, the piezoelectric vibrator 14 is displaced. Since the piezoelectric vibrator 14 is joined to the rigid support base 17, the vibrating plate 7 is preferentially displaced, the pressure in the pressure chamber 3 is increased, and ink droplets are ejected from the orifice 1. The ink jet head described in this embodiment discharges ink from the orifice 1 based on such a principle to form an ink image on a recording medium.
[0022]
FIG. 2 is a partial sectional view of the inkjet head.
In the figure, a piezoelectric actuator 13 includes a support substrate 17 and a piezoelectric vibrator 14. The piezoelectric vibrator 14 is joined to the vibration plate 7 via the adhesive 12. Therefore, the pressure in the pressure chamber 3 fluctuates rapidly due to the deformation of the diaphragm 7. That is, when a selective electric signal is applied to the piezoelectric vibrator 14 from the external drive circuit, the piezoelectric vibrator 14 generates displacement in the direction toward the orifice 1. Due to this displacement, the vibration plate 7 is deformed via the adhesive 12, and the ink filled in the pressure chamber 3 is pressurized and ejected from the orifice 1 as ink droplets. Here, the opening 23 of the housing 11 is made as small as possible so as to increase the rigidity of the structural member forming the flow path in order to reduce the variation in the speed and amount of the ejected ink droplets. Therefore, the conductive adhesive 16 is applied as uniformly as possible.
[0023]
The piezoelectric actuator 13 of the present example is an example of using a plane orientation d ₃₃ type piezoelectric vibrator, the supporting substrate 17 that is shown here is a ceramic such as alumina or zirconia, electrically the It is an insulator. Individual electrodes 18 and common electrodes 19 for sending electric signals to the piezoelectric vibrators are pattern-printed on both surfaces of the support substrate.
[0024]
FIG. 3 is an enlarged sectional view of the above-described piezoelectric actuator of the present invention. The piezoelectric actuator uses a laminated piezoelectric vibrator formed by alternately laminating a piezoelectric material and an internal electrode material in layers, and a central portion of the support substrate 17 is an active portion where the internal electrodes of the piezoelectric vibrator 14 overlap. The joining is performed so as to coincide with the center line of the region Wa. The width T of the support substrate 13 is smaller than the total width of the active region Wa and the inactive regions Wn at both ends, that is, the width (Wa + 2Wn) of the piezoelectric vibrator. Thus, when the conductive adhesive 16 is applied, the conductive adhesive 16 can be adhered with an amount slightly protruding from the width of the piezoelectric vibrator 14, and the overall width of the piezoelectric actuator 13 can be reduced. By using the piezoelectric actuator manufactured in this manner, the opening 23 of the piezoelectric actuator 13 of the housing 19 can be narrowed, and the ink flow forming the flow path of the orifice plate 2, the chamber plate 4, the restrictor plate 6, and the like can be reduced. The rigidity of the road member can be kept high, and the effect of the displacement of the adjacent piezoelectric vibrator, that is, the effect of so-called crosstalk, can be reduced. As a result, the displacement of the piezoelectric vibrator can be efficiently transmitted to the pressure chamber. Can be. As a result, the ink speed and amount of the ejected ink droplets can be made constant, and an ink jet recording head capable of performing high quality printing can be obtained.
[0025]
When an electric signal is applied to the individual electrode 18 and the common electrode 19 of the piezoelectric actuator 13 from an external drive circuit, the piezoelectric vibrator 14 is displaced around the active region Wa as shown in FIG. In order to efficiently generate the displacement of the piezoelectric vibrator 14 and use it for ejecting ink droplets, the support area between the piezoelectric vibrator 14 and the support substrate 17 is important. When the support region is smaller than the active region Wa, the displacement of the piezoelectric vibrator 14 occurs not only in the direction of the vibration plate 7 but also in the direction of the support substrate 17, and the displacement efficiency is reduced. Therefore, in order to transmit the displacement of the piezoelectric actuator 13 to the diaphragm 7 efficiently, it is preferable that the width of the piezoelectric actuator 13 is at least equal to or greater than the active area width Wa.
Therefore, the width T of the support substrate 17 is Wa ≦ T <Wa + 2 × Wn
If it is in the range, it is good.
[0026]
If the support substrate 17 has a small mass and the support substrate 17 and the piezoelectric vibrator 14 are loosely fixed, the piezoelectric actuator 13 starts to be displaced to the opposite side of the pressure chamber 3 due to the displacement of the piezoelectric vibrator 14, and the piezoelectric vibration The displacement of the element 14 cannot be transmitted to the diaphragm 7 effectively. Therefore, in order to increase the mass of the support substrate 17, it is desirable that the mass of the support substrate 17 and the Young's modulus of the material used as the support substrate 17 be larger than the mass and the Young's modulus of the piezoelectric vibrator.
[0027]
Next, a cross-sectional view of a piezoelectric actuator when using face orientation d ₃₁ direction of displacement of the piezoelectric vibrator in Fig. Even with surface orientation d ₃₁ direction of the piezoelectric actuator, the support area of the piezoelectric vibrator that is, by determining the width of the piezoelectric vibrator 14 of the supporting substrate 27 and Wa ≦ T <Wa + 2 × Wn, the piezoelectric actuator The displacement can be efficiently transmitted to the diaphragm.
[0028]
FIG. 6 is an enlarged sectional view of a piezoelectric actuator showing another example of the present invention. This embodiment is characterized in that a portion of the piezoelectric vibrator 64 that has been joined to the support substrate 67 is previously chamfered using a dicing saw or the like so that a portion of the piezoelectric vibrator 64 has a width substantially equal to the width of the support substrate 65. And bonding to the support substrate 67. Since the width of a part of the piezoelectric vibrator 64 and the width of the support substrate 67 are smaller than the width of the piezoelectric vibrator 64, the conductive adhesive 66 is applied to make the external electrode 65 conductive with the common electrode 69 and the individual electrode 68. Can be adhered in such an amount as to slightly protrude from the width of the piezoelectric vibrator, and the width of the entire piezoelectric actuator can be reduced. Further, in this shape, since a step is provided in the supporting portion of the piezoelectric vibrator 64 with the support substrate 67, the conductive adhesive can be applied to the corners of the piezoelectric vibrator. And the reliability of the electrical connection can be maintained.
[0029]
FIG. 6 is an enlarged sectional view of a piezoelectric actuator showing another example of the present invention. The feature of this example is that a step on the C-plane is provided in advance at the joint portion of the piezoelectric vibrator 74 with the support substrate 77 and then the piezoelectric vibrator 74 is bonded to the support substrate 77. The corners of the piezoelectric vibrator 74 may be damaged depending on handling and the like at the time of bonding the piezoelectric vibrator 74 and the support substrate 77. Therefore, by adopting this shape, the contact with the corners is reduced, the chip of the piezoelectric vibrator 74 can be reduced, and a highly reliable piezoelectric actuator can be provided. Further, in this shape, since a step is provided in the supporting portion of the piezoelectric vibrator 74 with the support substrate 77, the conductive adhesive can be applied to the corners of the piezoelectric vibrator. And the reliability of the electrical connection can be maintained.
[0030]
【The invention's effect】
By making the thickness smaller than the width of the piezoelectric vibrator while keeping the shape of the support substrate of the piezoelectric actuator as a flat plate, a highly reliable piezoelectric actuator can be provided. In addition, since the rigidity of the structural member forming the flow path can be increased, changes in the ejection speed and amount of the ejected ink droplets are reduced, and an ink jet recording head capable of high quality printing can be provided. Further, in the present invention, since the thickness of the support substrate is made smaller than that of the piezoelectric vibrator, the corners are less likely to come into contact with the abutting surface when the support substrate and the piezoelectric vibrator are brought into contact with each other and adhered to each other. Can be prevented.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of an ink jet head as an example of the present invention.
FIG. 2 is a vertical partial cross-sectional view of an inkjet head as an example of the present invention.
Figure 3 is an enlarged sectional view of a d ₃₃ type piezoelectric actuator of the present invention.
Enlarged cross-sectional view showing a displacement state of d ₃₃ type piezoelectric actuator of the present invention; FIG.
Figure 5 is an enlarged sectional view of a d ₃₁ type piezoelectric actuator of the present invention.
FIG. 6 is an enlarged sectional view of a piezoelectric actuator according to another example of the present invention.
FIG. 7 is an enlarged sectional view of a piezoelectric actuator according to another example of the present invention.
FIG. 8 is an exploded perspective view of an inkjet head as an example of a conventional configuration.
FIG. 9 is a vertical partial cross-sectional view of an inkjet head as an example of a conventional configuration.
[Explanation of symbols]
1 is an orifice, 2 is an orifice plate, 3 is a pressure chamber, 4 is a chamber plate, 5 is a restrictor, 6 is a restrictor plate, 7 is a diaphragm, 8 is a filter section, 9 is a diaphragm plate, and 10 is a common ink passage. , 11 is a housing, 12 is an adhesive, 13 is a piezoelectric actuator, 14 is a piezoelectric vibrator, 15 is an external electrode, 16 is a conductive member, 17 is a support substrate, 18 is an individual electrode, 19 is a common electrode, and 20 is a through electrode. The hole 21 is an ink introduction pipe.

Claims (3)

One end of the piezoelectric vibrator is fixed to the support substrate, the other end is a free end, a plurality of piezoelectric actuators, a plurality of orifices, and pressure chambers for storing ink provided corresponding to the plurality of orifices respectively. A flow path member having a housing that holds the flow path member, wherein an ink jet head having a free end of the piezoelectric vibrator in contact with a part of a pressure chamber of the flow path member;
An ink jet recording head, wherein the width of the support substrate is smaller than the width of the piezoelectric vibrator. The piezoelectric vibrator is a laminated piezoelectric vibrator formed by alternately laminating a piezoelectric material and an internal electrode material in layers, respectively, wherein the width of the active portion of the laminated piezoelectric vibrator is Wa, and the width of the inactive portion is 2. The ink jet recording head according to claim 1, wherein each of the widths is Wn, and the width T of the support substrate is configured to satisfy Wa ≦ T <Wa + 2 × Wn. 2. The ink jet recording head according to claim 1, wherein a step is provided in the vicinity of a portion of the piezoelectric vibrator fixed to the support substrate so as to have a width substantially equal to the width of the support substrate.

Images