JP3528623B2 - Piezoelectric vibrator unit and ink jet recording head using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric vibrator unit suitable for ejecting ink and an ink jet recording head using the piezoelectric vibrator unit.

[0002]

2. Description of the Related Art An ink jet recording head of this type (hereinafter referred to as a recording head) is, for example, a flow path unit having a pressure chamber and a reservoir, and is arranged on the back side of the flow path unit to reduce the volume of the pressure chamber. And a piezoelectric vibrator unit for changing. The flow channel unit includes a flow channel forming plate having through holes that serve as pressure chambers and reservoirs, a nozzle plate bonded to the front side of the flow channel forming plate and having a number of nozzle openings arranged in rows, and a flow channel. The piezoelectric vibrator unit is provided with a plurality of piezoelectric vibrators (hereinafter, referred to as vibrators) formed in a comb tooth shape and provided with an elastic sheet or the like that is bonded to the back side of the forming plate and has an island portion provided corresponding to the nozzle openings. Say) etc. Then, the piezoelectric vibrator unit is arranged such that the comb-teeth end of the vibrator is brought into contact with the island portion of the elastic sheet from the back side of the flow path unit.

When ink droplets are ejected by the recording head having such a configuration, a drive pulse is applied to expand and contract the vibrator to deform the elastic sheet and change the volume of the pressure chamber. For example, the pressure chamber is expanded by contracting the vibrator to allow the ink in the reservoir to flow into the pressure chamber, and then the vibrator is expanded to contract the pressure chamber. The contraction of the pressure chamber increases the ink pressure in the ink chamber, and the ink in the ink chamber is ejected from the nozzle opening.

One of the vibrators used in this recording head is a d31 mode vibrator. This d31 mode vibrator is a vibrator in which a plurality of layers of piezoelectric bodies and internal electrodes are stacked, and is displaced in a direction perpendicular to the stacking direction. The vibrator is characterized in that it can be vibrated at high speed and that it is easy to deal with high density of dots.

By the way, in the recording head using the d31 mode oscillator, since the electrostatic capacitance of the oscillator is large,
If the vibrator is expanded or contracted to the extent that ink can be ejected, the vibrator will generate an excessively strong force. In other words, this vibrator consumes electric energy more than necessary.

Therefore, a large amount of current is required to drive the vibrator, which may cause distortion of the drive pulse when ejecting multiple dots at the same time or cause excessive heat generation of the vibrator. .

[0007]

In view of this point, attempts have been made to suppress the consumption of electric energy by reducing the capacitance without changing the displacement amount of the vibrator. For example,
There is a type in which the capacitance of the vibrator is reduced by reducing the number of laminated internal electrodes and piezoelectric bodies, or by notching the side surface of the vibrator in a concave shape.

However, in the case where the number of laminated internal electrodes and piezoelectric bodies is reduced, the area of the end surface of the vibrator, that is,
The contact area between the oscillator and the island portion of the elastic sheet is reduced, and the island portion is locally pressed. For this reason,
There is a problem that the island portion is bent, the displacement of the vibrator cannot be efficiently transmitted to the elastic sheet, and it becomes difficult to eject ink accurately. Also, in the one with the oscillator cut out,
The contact area between the oscillator and the island can be made relatively large, but the notched and narrowed part presses the end of the tip head, which causes a bending moment, resulting in displacement of the oscillator. However, there is a problem in that the ink cannot be accurately ejected to the island portion of the elastic sheet and it is difficult to eject the ink accurately.

The present invention has been made in view of the above circumstances, and a piezoelectric vibrator unit capable of reducing the capacitance without changing the displacement amount of the vibrator and an elastic sheet for the displacement of the vibrator. An object of the present invention is to provide an ink jet recording head that can efficiently transmit.

[0010]

DISCLOSURE OF THE INVENTION The present invention has been proposed in order to achieve the above object. According to a first aspect of the present invention, common internal electrodes and individual internal electrodes are alternated with a piezoelectric body sandwiched therebetween. Vibrators formed by stacking the two in a comb shape and joined to a fixing plate while leaving the free ends of the vibrators, and the free ends of the vibrators are orthogonal to the stacking direction of the piezoelectric body. A piezoelectric vibrator unit capable of expanding and contracting in the longitudinal direction, wherein the vibrator
An opening having a hollow structure is formed at the free end of the opening in the direction in which the transducers are arranged, and within the area corresponding to the base end from the tip of the opening.
In the overlapping area of the common internal electrode and the individual internal electrode
The piezoelectric vibrator unit is characterized in that the piezoelectric vibrator unit is arranged so that the area is contained .

[0011]

[0012]

[0013]

Here, the "base end of the opening" means the end of the opening on the side of the fixed plate, and the "tip of the opening" also means the end on the tip side of the vibrator. means.

[0015]

[0016]

[0017]

[0018]

[0019]

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

[0028]

According to a twelfth aspect of the present invention, a pressure chamber defined by the piezoelectric vibrator unit according to any one of the first to seventeenth aspects, an elastic sheet and a nozzle plate having nozzle openings formed therein. An ink jet recording head comprising: an elastic sheet, wherein the elastic sheet is composed of an elastic film and an island portion provided corresponding to a nozzle opening, and a tip of a vibrator is brought into contact with the island portion. And an inkjet recording head.

[0030]

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. First, the overall configuration of the inkjet recording head 1 (hereinafter referred to as recording head 1) will be described. FIG. 1 is a diagram showing an example of a recording head 1 to which the present invention is applied, and is a sectional view showing an enlarged main part.

The recording head 1 is composed of a case 2, a flow path unit 3, a piezoelectric vibrator unit 4 and the like. In the description of the recording head 1, FIG.
The front side corresponding to the upper side of the above is referred to as the front side, and the base side corresponding to the lower side of FIG. 1 is referred to as the rear side.

The case 2 is a block-shaped member made of synthetic resin, which is provided with an accommodation space 5 whose both front and rear ends are open.
The flow path unit 3 is joined to the tip of the piezoelectric vibrator unit 4, and the piezoelectric vibrator unit 4 is housed and fixed in the accommodation space 5 with the comb-teeth end of the vibrator group 21 facing the front end side opening. In addition, an ink supply pipe 6 that communicates with the ink cartridge on the base end side is provided on the side of the accommodation space 5.

The flow channel unit 3 is roughly constructed by laminating the nozzle plate 8 and the elastic sheet 9 on both sides with the flow channel forming plate 7 interposed therebetween.

The nozzle plate 8 has a large number (for example, 96) of nozzle openings 1 at a pitch corresponding to the dot formation density.
It is a thin plate-shaped member in which 0 ... Is opened in rows and is made of, for example, a stainless plate.

A through hole is opened in the flow path forming plate 7 laminated on the nozzle plate 8. The through hole is provided in the reservoir 1 through which the ink supplied through the ink supply pipe 6 flows.
1. A pressure chamber 12 that generates an ink pressure necessary for ejecting ink from the nozzle opening 10, and ink supply ports 13 and 13 that connect the reservoir 11 and the pressure chamber 12 to each other.
Is a member for forming. In the present embodiment, the flow path forming plate 7 is formed by etching the silicon wafer.

In this embodiment, the elastic sheet 9 is made of PPS.
It has a double structure in which a polymer film such as (polyphenylene sulfite) is laminated on the stainless plate 15 as the elastic film 14. The stainless plate 15 is used as the reservoir 1.
The unnecessary portion such as the portion corresponding to 1 is removed by etching to form the island portion 16 (thick portion) with which the tip of the driving oscillator 29 of the oscillator group 21 abuts from the back side. The elastic portion 17 is configured by surrounding the elastic film 14 (thin portion) only. As with the nozzle openings 10, a large number of the island portions 16 are provided at a pitch corresponding to the dot formation density, the width corresponding to the nozzle arrangement direction is narrow, and the drive vibrator 2 is provided.
9 is formed in a block shape having a long length corresponding to the piezoelectric body stacking direction (described later).

The nozzle plate 8 is connected to the flow path forming plate 7
The flow passage unit 3 is formed by arranging the elastic sheet 9 on the front side and the elastic sheet 9 on the back side, and sandwiching the flow passage forming plate 7 between the nozzle plate 8 and the elastic sheet 9 and integrating them by adhesion or the like.

In this flow path unit 3, the pressure chamber 12 and the reservoir 11 are defined by the nozzle plate 8 and the elastic sheet 9. The pressure chamber 12 is located on the back side of the nozzle opening 10, and the elastic sheet 9 is placed on the back side of the pressure chamber 12.
The elastic part 17 is located. Further, a reservoir 11 is located on the side of the pressure chamber 12, and the reservoir 11 and the pressure chamber 12 are provided with two ink supply ports 13, 1 provided side by side in the front-rear direction.
It is connected by 3. Further, the ink from the ink cartridge is supplied to the reservoir 11 through the ink supply pipe 6.

The piezoelectric vibrator unit 4 is roughly constituted by a vibrator group 21 and a fixed plate 22. This transducer group 2
Reference numeral 1 denotes a comb-tooth-shaped vibrator group in which so-called d31 mode drive vibrators 29 are arranged in a comb-tooth shape so as to correspond to the nozzle openings 10. The d31 mode drive vibrator 29 expands and contracts (displaces) in the vibrator longitudinal direction, which is the direction perpendicular to the stacking direction of the piezoelectric body and the internal electrode, that is, in the front end direction or the base end direction when a drive pulse is applied. ) Do. The drive oscillator 29 and the dummy oscillator 28 (see FIG. 2) have openings 23 penetrating in the oscillator array direction on the side faces facing the adjacent oscillators, that is, on the adjacent oscillator side. It is opened on the side surface of the device, so that a part of the vibrator has a hollow structure. Further, the fixing plate 22 is fixed to the base end portion on one side surface side of the comb-shaped oscillator group 21 by adhesion or the like. The piezoelectric vibrator unit 4 will be described in detail later.

A flexible cable 24, which is a kind of wiring, is provided on the other side surface of the comb-shaped oscillator group 21.
Implement. Then, a drive pulse is supplied to each of the vibrators 28 and 29 through the flexible cable 24. By this drive pulse, the drive vibrator 29 expands and contracts toward the front end or the rear end, and the island portion 16 and the elastic film 14 forming the elastic portion 17 are deformed in the front-rear direction. With the movement of the elastic portion 17 in the front-rear direction, the pressure chamber 12 expands or contracts to change its volume.

When ink droplets are to be ejected from the nozzle openings 10, a drive signal is selectively applied to a predetermined drive vibrator 29, for example, the pressure chamber 12 is once expanded and then contracted. By doing so, the ink in the reservoir 11 flows into the pressure chamber 12 as the pressure chamber 12 expands, and the ink pressure in the pressure chamber 12 increases as the pressure chamber 12 contracts. Then, the ink pushed out from the nozzle opening 10 is ejected as an ink droplet.

Next, the piezoelectric vibrator unit 4 will be described in detail. Here, FIG. 2 is an external perspective view of the piezoelectric vibrator unit 4. 3A and 3B are views for explaining the piezoelectric vibrator unit 4, and FIG. 3A is a sectional view taken along line AA in FIG.
(B) is an enlarged cross-sectional view of the free end portion 29a of the drive vibrator 29, (c) is an enlarged cross-sectional view of the tip portion of the opening 23,
FIG. 7D is an enlarged cross-sectional view of the base end portion of the opening 23.

As shown in FIG. 2, the above-mentioned vibrator group 21 includes dummy vibrators 28 and 28 located at both ends in the row direction (arrangement direction) of the vibrators, and the dummy vibrators 28 and 28. A large number of drive vibrators 29 arranged between the ...
It consists of and. Here, the drive vibrator 29 is a vibrator that can expand and contract according to a drive signal and contribute to ink ejection. On the other hand, the dummy vibrator 28 does not contribute to ink ejection and is used when the piezoelectric vibrator unit 4 is positioned at a predetermined position of the case 2 or when the position of the vibrator group 21 in the case 2 is determined. It is a vibrator.

In the present embodiment, the dummy vibrator 28
Is set to be about 2 to 3 times wider than the width of the drive vibrator 29. Thereby, the mechanical strength of the dummy vibrator 28 can be increased and the positioning accuracy of the piezoelectric vibrator unit 4 can be improved. Further, since the area of the common electrode wiring portion 30 provided at the base end portion of the dummy vibrator 28 can be widened, the connection reliability with the flexible cable 24 can be improved and more current can be supplied. Can be drained.

Next, the structure of the vibrators 28 and 29 will be described. The drive vibrator 29 and the dummy vibrator 28 have basically the same structure although the widths of the vibrators are different. Therefore, the structure of the drive vibrator 29 will be described here, and the dummy vibrator 28 will be described. Is omitted.

As shown in FIG. 3B, the drive vibrator 29
Is composed of a laminated body 34 in which the common internal electrodes 32 and the individual internal electrodes 33 are alternately laminated with the piezoelectric body 31 sandwiched therebetween, and a spacer 35 for forming the opening 23. , 34 with a spacer 35 interposed between them, and they are integrally formed. The drive vibrator 29 is composed of the laminated bodies 34, 34 and the spacer 3 as will be described later.
5 and 5 are laminated and integrated to form a plate-shaped vibrator plate, which is cut into comb teeth. The divided drive vibrator 29 is formed in an elongated prismatic shape. As shown in FIG. 3A, a base end portion 29b extending from the base end to about half of the vibrator longitudinal direction is joined to the fixing plate 22. A free end portion 29 a extending from the tip to approximately half in the longitudinal direction of the vibrator extends in a direction projecting from the edge of the fixed plate 22. In short, this drive vibrator 29 is fixed plate 22 in a state like a so-called cantilever.
It is fixed to.

The tip of the drive vibrator 29 is brought into contact with the island portion 16 of the elastic sheet 9 from the back side. The free end portion 29a of the drive vibrator 29 functions as an active portion that can expand and contract when a drive signal is applied,
The base end portion 29b functions as an inactive portion that does not expand and contract.

Regarding the shape of the island portion 16 with which the tip of the drive vibrator 29 abuts, in the present embodiment, as shown in FIG. 3A, the width W of the abutment surface corresponding to the vibrator array direction is W. Is
The length L1 in the longitudinal direction is set to be equal to or slightly wider than the width of the tip of the drive oscillator 29, and the length L2 of the tip surface of the drive oscillator 29 (the length of the drive oscillator 29 of the drive oscillator 29 is set so that the island portion 16 does not bend). It is provided longer than (corresponding to the thickness in the piezoelectric body stacking direction) and protrudes from the drive vibrator 29. With this configuration, the displacement of the drive vibrator 29 can be efficiently transmitted to the island portion 16.

The spacer 35 described above is a member interposed between the laminated bodies 34, 34 to form the opening 23. For example, the same piezoelectric body as the piezoelectric body 31 of the laminated body 34 or zirconium oxide. Laminate 3 such as ceramics etc.
It is made of a material having a linear expansion coefficient substantially equal to the linear expansion coefficient of No. 4. This is to make the degree of thermal contraction of the laminated body 34 and the spacer 35 substantially the same in the firing process when manufacturing the piezoelectric vibrator unit 4. As a result, it is possible to prevent warpage and cracks in the vibrator plate after firing.

The free end portion 29 of this drive vibrator 29
As shown in FIG. 3B, an overlapping region (overlap portion) where the common internal electrode 32 and the individual internal electrode 33 are overlapped with each other is formed in a along the transducer longitudinal direction. This overlapping region is a region in which the laminated body 34 is strained and deformed according to the potential difference between the common internal electrode 32 and the individual internal electrode 33, and the free end portion 29a is contracted by the strained deformation of the laminated body 34 in this region. To do. The free end portion 29a is provided with an opening 23 that penetrates the drive oscillator 29 in the oscillator array direction.

In the present embodiment, as shown in FIG. 3C, the tip of this overlapping area is the tip 2 of the opening 23.
The two stacked bodies 3 are arranged so as to be located on the base end side of 3a.
The non-actuated portions of the tip end side of 4, 34 are joined by the bridge portion 35a. Here, the bridge portion 35a is a part of the spacer 35, and is a portion that joins the stacked bodies arranged in parallel and separated from each other at the free end portion of the vibrator.

Further, as shown in FIG. 3 (d), the base end of the overlapping region is provided so as to be located substantially the same as or slightly closer to the base end 23b of the opening 23. In other words,
The overlapping area is arranged to fit in the opening area corresponding to the area between the tip and the base of the opening 23. This is for efficiently deforming the laminated body 34. That is, the spacer 3 is formed even in the region where the stacked bodies 34, 34 are deformed.
If joined at 5, the spacer 35 will cause the spacers 35,
Therefore, it becomes difficult to efficiently expand and contract the drive vibrator 29 because the distortion of No. 4 is suppressed. Then, as in the present embodiment, when the overlapping region is set within the opening region, deformation of the stacked bodies 34, 34 is not suppressed, and the drive vibrator 29 can be efficiently expanded and contracted.

Next, the electrodes provided on the drive vibrator 29 will be described. The individual internal electrodes 33 described above are made of an electrode material such as a silver-palladium alloy and are provided up to the tip of the vibrator. Then, at the tip of this vibrator, the individual external electrode 3
6 electrically connected. The individual external electrode 36 is an electrode for applying a drive pulse to the drive vibrator 29, and is electrically insulated for each drive vibrator 29. The individual external electrode 36 is formed in an inverted L shape from the vibrator tip surface to the other side surface of the comb-tooth vibrator group 21 opposite to the bonding surface of the fixing plate 22. On the side surface, as shown in FIG. 2, the base end portion 29b of the drive vibrator 29 is formed. The individual external electrodes 36 are made of an electrode material such as gold, nickel, chromium, or copper, and are formed by vapor deposition, sputtering, or the like.

The common internal electrode 32 described above is also formed of an electrode material such as a silver-palladium alloy, and is provided up to the base end of the vibrator. Then, the base end of the vibrator is electrically connected to the common external electrode 37. This common external electrode 37
Is an electrode electrically connected to the common internal electrode 32 of each drive vibrator 29, and the comb-tooth vibrator group 21 from one side surface of the comb-tooth vibrator group 21 which is the bonding surface of the fixing plate 22. Is formed so as to extend around the base end portion of the other side surface in a substantially U-shape. At the base end portion of the other side surface of the comb-shaped oscillator group 21, as shown in FIG. 2, there is a gap between the individual external electrode 36 and the common external electrode 37 and the individual external electrode. It is electrically insulated from 36. The common external electrode 37 is also formed of an electrode material such as gold, nickel, chromium, or copper by using a method such as vapor deposition or sputtering.

The base end portion of the other side surface of the comb-shaped oscillator group 21 serves as a wiring mounting surface on which the flexible cable 24 is mounted. On this wiring mounting surface, as shown in FIG. 2, the common external electrodes 37 of the dummy vibrators 28, 28,
37 is a common electrode wiring portion 30, 30, and the base end portion of the drive vibrator 29 is an individual electrode wiring portion 38.
Therefore, the flexible cable 24 is connected to the comb-shaped oscillator 21.
Can be connected on the side surface of, that is, the other side surface opposite to the fixing plate joining surface, and the wiring work can be easily performed. Further, the common electrode wiring portion 30 and the individual electrode wiring portion 38 are formed so as to be offset in the vibrator longitudinal direction so as not to overlap each other. Therefore, when wiring the flexible cable 24, it is possible to reliably prevent the common electrode wiring portion 30 and the individual electrode wiring portion 38 from being short-circuited by the melted solder.

In the piezoelectric vibrator unit 4 configured as described above, the openings 23 are formed in the laminated surface of the vibrators 28 and 29 (that is, the side surfaces of the adjacent vibrators 28 and 29 facing each other). Since a part of each of the vibrators 28 and 29 has a hollow structure, the electrostatic capacity of the drive vibrator 29 can be reduced. As a result, an inexpensive circuit element having a small current capacity can be used as a circuit element for applying a drive pulse to the drive vibrator 29, for example, a transistor, and the cost can be reduced. Furthermore, the amount of heat generated by the vibrator itself can be reduced. In addition, since the difference in the amount of current based on the difference in the number of dots that are driven at the same time can be reduced, a drive pulse generation circuit (drive pulse generation means) that generates a drive pulse to be supplied to the piezoelectric vibrator unit 4 is provided to perform inkjet recording. When the device is constructed, the distortion of the drive pulse when a large number of drive vibrators 29 ... Are simultaneously driven is reduced. Therefore, the difference in image quality between the case where a large number of dots are recorded simultaneously and the case where a few dots are recorded can be extremely reduced.

Moreover, since a part of the driving vibrator 29 has a hollow structure, the external capacitance of the driving vibrator 29 can be reduced without changing its outer shape. As a result, even if the capacitance is reduced, the size of the tip surface of the drive vibrator 29 can be made equal to or larger than that of the conventional one, so that the island portion 16 of the elastic sheet 9 is pressed uniformly. can do. Therefore, the displacement of the drive vibrator 29 can be efficiently transmitted to the elastic sheet 9, and the ink can be accurately ejected. Further, since the surface area of the drive vibrator 29 is increased by opening the opening 23, the heat generated by the drive vibrator 29 can be efficiently released. For this reason,
The drive vibrator 29 can be prevented from being excessively heated, and the operation of the vibrator can be stabilized.

Next, a method of manufacturing the piezoelectric vibrator unit 4 having the above structure will be described with reference to FIG. To make the piezoelectric vibrator unit 4, first, the piezoelectric body 31, the internal electrode layer 32, the piezoelectric body 31, the internal electrode layer 3 are formed.
A large-sized vibrator plate is prepared from the large-sized laminated body 34 formed by laminating the piezoelectric material 31, the piezoelectric body 31, the internal electrode layer 32, and the like, and the large-sized spacer 35. Then, a small vibrator plate is cut out from this vibrator plate, and the cut vibrator plate is divided into comb teeth. Note that FIG. 4E shows the vibrator plate (the laminated body 34, the spacer 35) after being cut out.

First, a method of forming the large-sized laminated body 34 will be described. First, the large plate piezoelectric body 31 shown in FIG. 4A is set in the printing machine. Next, using the first mask pattern, each print region 41 ... On the surface of the plate-shaped piezoelectric body 31.
Then, an electrode layer to be the individual internal electrodes 33 as shown in FIG. 4B is printed. This electrode layer is provided from one long side of each print area 41 to the other long side up to about half the position of the short side. As described above, this electrode layer and the electrode layer that will be the common internal electrode 32 described later are formed of an electrode material such as a silver-palladium alloy.

After printing the electrode layer to be the individual internal electrode 33, a new plate-shaped piezoelectric body 31 is placed on the electrode layer and set. After setting the plate-shaped piezoelectric body 31,
Plate-shaped piezoelectric body 3 set using the second mask pattern
An electrode layer to be the common internal electrode 32 as shown in FIG. 4C is printed on the first print area 41. This electrode layer is provided along the short side direction from the other long side of the printing region 41 to the front of the one long side. After the electrode layer to be the common internal electrode 32 is printed, a new plate-shaped piezoelectric body 31 is set on the electrode layer, and the set plate-shaped piezoelectric body 31 is set.
An electrode layer to be the individual internal electrodes 33 is printed in the print area of. Thereafter, similar steps are repeated to form a large-sized laminated body 34.

After the large-sized laminated body 34 is prepared by the above procedure, firing is performed. In this firing process, large-sized laminated body 3
Two sheets of 4 and a piezoelectric body serving as the spacer 35 are prepared, and the piezoelectric bodies serving as the spacers 35 are stacked and fired to be integrated with the stacked bodies 34, 34. As a result, a large-sized vibrator plate is created. Here, as shown in FIG. 4D, the piezoelectric body serving as the spacer 35 is made to correspond to the portion serving as the opening 23, that is, the overlapping region of the individual internal electrode 33 and the common internal electrode 32. It is a piezoelectric body having holes 42 formed therein. The through hole 42 is opened by an arbitrary processing method such as press working. Here, since the spacer 35 is made of the same piezoelectric material as the piezoelectric material 31 of the laminated body 34, as described above, the degree of contraction of the laminated body 34 and the spacer 35 during firing becomes substantially equal, and the warpage of the vibrator plate Prevents the occurrence of cracks.

After the large-sized vibrator plate is prepared, the large-sized vibrator plate is cut along the above-mentioned printing area 41,
Cut into oval transducer plates. The cut oval vibrator plate is shaped by lapping the surface. Then, the individual external electrodes 36 and the common external electrode 37 are formed on the surface of the small-sized vibrator plate by vapor deposition, sputtering or the like.

Once the external electrode layers have been formed, FIG.
As shown in, the fixing plate 22 is bonded to one side surface of the oval vibrator plate. After the vibrator plate and the fixed plate 22 are bonded, the vibrator plate is cut using a dicing saw or the like to cut the vibrators 28 and 29 into comb teeth. In this cutting step, as shown by reference numeral B, cutting is performed so as to leave an uncut portion at the base end portion 29b. Specifically, on one side surface side, the individual external electrodes 36 are electrically connected to the individual internal electrodes 33 on the other side surface side from the tip end toward the base end side so as to leave the fixing plate attachment portion. A groove is formed in series from the front end to the base end so that the vibrators 28 and 29 are electrically insulated, and the vibrators 28 and 29 are cut by the groove. By forming the vibrators 28 and 29 in this manner, the common internal electrode 32 extends in the vibrator array direction in the uncut portion. And
The electric resistance value of the common external electrode 37 can be reduced by the uncut portion of the common internal electrode 32. Therefore, the loss of the drive pulse can be reduced.

It should be noted that, in this cutting step, the vibrators 28 and 29 may be completely cut without leaving any uncut portions. In other words, as shown by symbol C in FIG. 4 (e), the oscillator plate is divided into teeth by the groove that reaches the fixed plate 22 from the other side surface of the oscillator plate opposite to the adhesive surface of the fixed plate 22. The vibrators 28 and 29 may be formed by forming the vibrators 28 and 29. By doing so, it is possible to more reliably perform electrical insulation between adjacent vibrators. Then, in this case, the fixed plate 22 is made conductive, and the fixed plate 22 makes the common external electrodes 37 of the vibrators 28 and 29 conductive. For this conduction, for example, the fixed plate 22 itself may be made of a conductive material such as a stainless plate, or a conductive layer may be formed on the surface of the fixed plate 22.

By the way, in the above-described first embodiment, one opening 23 is provided for each transducer 28, 29, and the overlapping area of the individual internal electrode 33 and the common internal electrode 32 is formed in the opening 23. Although the one that is accommodated in the opening region has been described, the present invention is not limited to this configuration. Hereinafter, another embodiment of the present invention will be described.

First, the second embodiment will be described with reference to FIG. The second embodiment is characterized in that the overlapping region of the individual internal electrodes 33 and the common internal electrode 32 and the opening region of the opening 23 are aligned and substantially matched.

More specifically, on the tip side of the opening 23, the position of the tip 23a of the opening 23 in the longitudinal direction of the transducer (similar in the following description) and the position of the tip of the overlapping region are substantially the same. I am allowed. In other words, the laminated body 34
The bridge portion 35 of the spacer 35 is attached to the non-actuated portion of the tip of the spacer.
a is provided, and the laminated body 34 (3
4a, 34b) are joined together. In addition, the opening 23
At the base end side of, the position of the base end of the overlapping area and the fixing plate 2
The position of the tip end of 2 and the position of the base end 23b of the opening 23 are substantially aligned.

According to this structure, since the overlapping area where the laminated body 34 can be deformed by strain and the opening area where the opening 23 is formed coincide with each other, the laminated body 3 is formed by the spacer 35.
The strain deformation of No. 4 is not suppressed, and the laminated body 34 can be efficiently deformed. Further, the positions of the tip end of the fixing plate 22 and the base end 23b of the opening 23 are made to coincide with each other, and the positions in the vibrator longitudinal direction are aligned on the vibrator tip side as well. Since the first laminated body 34a directly bonded to the fixing plate 22 and the second laminated body 34b bonded to the first laminated body 34a via the spacer 35 The length of the obtained portion is the same in both laminated bodies 34a and 34b. That is, it has the same length as the opening area (overlapping area). As a result, the natural vibration period on the first laminated body 34a side when the drive vibrator 29 is expanded and contracted matches the natural vibration period on the second laminated body 34b side. Therefore, the first laminated body 34a and the second laminated body 34a
Since b and oscillate in the same cycle, it is possible to further stabilize the ink ejection.

Next, a third embodiment will be described with reference to FIG. In the third embodiment, three openings 23 are provided along the stacking direction of the piezoelectric bodies 31. As described above, the plurality of openings 23 are formed along the stacking direction of the piezoelectric body 31.
When a, 23b, and 23c are opened, since the laminated bodies 34 and the openings 23 are alternately present along the piezoelectric body laminating direction,
The lengths of the vibrators 28 and 29 in the piezoelectric body stacking direction can be further increased. Further, since the length of one opening 23 in the stacking direction can be shortened, the strength of the vibrators 28, 29 can be increased. Furthermore, the plurality of openings 23
Since the surface area of the vibrators 28 and 29 including the inner peripheral surface of the opening 23 can be increased by providing the above, the heat generated by the drive vibrator 29 can be radiated more efficiently.

In FIG. 6, the three openings 23a, 2a
Although the example in which 3b and 23c are provided is illustrated, the number of openings 23 can be appropriately changed. For example, it may be two or four. Further, in order to open a plurality of openings 23 along the stacking direction of the piezoelectric bodies 31, a piezoelectric body serving as a spacer 35 (piezoelectric sheet having the through holes 42) is sandwiched between the stacked bodies 34. Since it is only necessary to stack the layers, manufacturing is easy.

Next, a fourth embodiment will be described with reference to FIG. In the fourth embodiment, the opening 23 (23
Two d, 23e) are provided along the longitudinal direction of the transducers 28, 29. In other words, the bridge portion 35b is provided midway in the longitudinal direction of the opening 23. In this configuration, when the oscillator plate is cut to divide the oscillators 28 and 29 into comb teeth, the bridge portion 35b acts to prevent excessive bending of the laminated body 34 in the opening region. Therefore, breakage of the vibrators 28 and 29 at the time of cutting can be effectively prevented. In FIG. 7, the two openings 2
Although the example in which 3d and 23e are provided is illustrated, the number of the openings 23 can be appropriately changed also in this embodiment.
Further, the length of each opening 23 in the vibrator longitudinal direction (the position of the bridge portion 35b in the vibrator longitudinal direction) can be set arbitrarily.

Next, a fifth embodiment will be described with reference to FIG. In the fifth embodiment, an internal electrode is formed on the spacer 35 ′, and the opening 23 is defined by the common internal electrodes 32, 32.

More specifically, an individual spacer electrode 44 is provided at a non-actuated portion of the spacer 35 'substantially in the middle of the piezoelectric body stacking direction and closer to the tip than the opening 23. The individual spacer electrode 44 corresponds to the individual internal electrode 3
Similar to 3, it is formed of an electrode material such as a silver-palladium alloy, and is electrically connected to the individual external electrodes 36 at the tips of the vibrators 28 and 29. Similarly, a common spacer electrode 45 is provided in the portion closer to the base end than the opening 23. The common spacer electrode 45 is also made of a silver-palladium alloy and is electrically connected to the common external electrode 37 at the base ends of the vibrators 28 and 29.

Such a spacer 35 'can be formed by laminating piezoelectric bodies. That is, a large-sized spacer piezoelectric body having a through hole 42 to be the opening 23 is set in a printing machine, and an electrode material to be an individual spacer electrode 44 and a common spacer electrode 45 is printed on a printing area 41 of the piezoelectric body. To form electrodes. After the electrode layer is formed, a new spacer piezoelectric material is laminated so as to overlap the formed electrode layer to form the spacer 35 '. Then, the two large-sized laminated bodies 34, 34, which are separately prepared, are laminated with the spacer 35 'interposed therebetween. In addition,
An electrode layer to be the common internal electrode 32 is printed on the surface of the laminated body 34 on the side in contact with the spacer 35 '. Laminate 3
After laminating 4, 34 and the spacer 35 ', these laminated bodies 34, 34 and the spacer 35' are integrated by firing to form a large-sized vibrator plate. Then, a small vibrator plate is cut out from this vibrator plate, and the cut vibrator plate is divided into comb teeth.

Comb-shaped oscillator group 2 thus created
In 1, the common internal electrode 3 is formed in the part that defines the opening 23.
2 and 32 are formed in an exposed state, and internal electrodes 44 and 45 are also formed on the spacer 35 '. That is, also in the spacer 35 ′, similarly to the laminated body 34, the piezoelectric body and the internal electrode are alternately formed. Therefore, the linear expansion coefficient of the laminated body 34 and the linear expansion coefficient of the spacer 35 'can be made closer to each other, and the warpage and distortion of the vibrator plate generated during firing can be more effectively prevented.

In FIG. 8, the common internal electrodes 32, 32 are
Although the opening 23 is partitioned by the example, the opening 23 may be partitioned by the individual internal electrodes 33, 33. In addition, the internal electrodes 44, 45 provided on the spacer 35 '
Is not limited to one layer, and a plurality of layers may be provided.

Next, a sixth embodiment will be described with reference to FIG. In the sixth embodiment, the spacer 47 is
It is made of a conductive material and is electrically connected to only one of the common external electrode 37 or the individual external electrode 36. In this embodiment, the insulating layer 47a is provided at the tip of the spacer 47, and the spacer 47 is electrically connected only to the common external electrode 37.

In this structure, the spacer 47 itself exhibits the same function as the common internal electrode 32. Therefore, the laminated body 3
4 can efficiently apply an electric field to the oscillators 28, 2
The displacement efficiency of 9 can be improved. Although the spacer 47 is electrically connected only to the common external electrode 37 in FIG. 9, the spacer 47 may be electrically connected only to the individual external electrode 36.

[0080]

As described above, according to the present invention,
It has the following effects.

That is, according to the first aspect of the invention, since a part of the vibrator has a hollow structure by the opening formed at the free end of the vibrator, the vibration amount of the vibrator is not changed and the static amount is maintained. The electric capacity can be reduced. As a result, an inexpensive circuit element having a small current capacity can be used as a circuit element for applying a drive pulse to the vibrator, and the cost can be reduced. Further, the amount of heat generated by the vibrator itself can be reduced. In addition, the difference in the amount of current based on the difference in the number of dots that are driven simultaneously can be reduced, and the distortion of the drive pulse when driving a large number of transducers at the same time and when driving a small number of transducers, such as a few Can be reduced

Moreover, since a part of the vibrator has a hollow structure, the surface area of the vibrator can be increased. For this reason,
The heat generated by the vibrator can be efficiently released. Therefore, the vibrator can be prevented from being excessively heated, and the operation of the vibrator can be stabilized.

Furthermore, since the overlapping region of the common internal electrode and the individual internal electrode is provided in accordance with the opening region of the opening, the lengths of the bent portions of the laminated body divided by the opening can be made uniform. . Therefore, the natural vibration period of the bent portion can be made to match between the vibrators. For this reason,
The expansion and contraction operation of the entire vibrator can be further stabilized.

Further, according to the invention described in claim 5 , since a plurality of openings are formed along the stacking direction of the piezoelectric bodies, the capacitance can be increased while increasing the thickness of the vibrator in the stacking direction of the piezoelectric bodies. Can be reduced. Further, since the surface area of the vibrator can be further increased, a higher heat dissipation effect can be obtained, which can contribute to the further stable operation of the vibrator.

According to the sixth aspect of the invention, since a plurality of openings are opened along the longitudinal direction of the vibrator, the bridge portion existing between the openings joins the laminates. For this reason, the lack of rigidity due to the opening of the opening can be compensated for by the bridge portion, and damage to the vibrator at the time of cutting into comb teeth can be effectively prevented.

According to the invention described in claim 7 , since the opening is divided by at least one of the common internal electrode and the individual internal electrode, an electric field can be generated also in this opening. There are internal electrodes. Therefore, the vibrator can be efficiently expanded and contracted.

Further, according to the invention described in claim 8 to claim 10 , since it is possible to eliminate a large difference between the linear expansion coefficient of the laminate and the linear expansion coefficient of the spacer, it is possible to prevent Warpage and distortion can be prevented more effectively.

According to the invention described in claim 11 ,
Since the spacer is made of a conductive material and electrically connected to only one of the common external electrode or the individual external electrode,
The spacer itself performs the same function as the internal electrode. Therefore, an electric field can be efficiently applied to the piezoelectric body, and the displacement efficiency of the vibrator can be improved.

By the way , according to the invention of the present application , one side surface of the comb-shaped oscillator group is provided from the tip to the base end side so as to leave the fixing plate attachment portion, and the other side surface side is provided with the individual internal parts. Since the individual external electrodes that are electrically connected to the electrodes are electrically insulated for each vibrator, the vibrator plate is divided into teeth by the grooves that are provided in series from the tip to the base end so that each vibrator is provided. In the portion left uncut by the groove, the common internal electrode extends in the transducer array direction. Then, the electric resistance value of the common internal electrode can be lowered by the common internal electrode in the uncut portion. Therefore, the loss of the drive pulse can be reduced.

[0090] Furthermore, the vibrator plate by a groove that reaches the fixed plate from the other side opposite to the vibrator plate and the tooth breaking in a comb shape to form a comb-shaped resonator and the adhesive surface of the fixed plate Since this is done, electrical insulation between the vibrators can be performed more reliably.

Furthermore, since the side surface of the comb-shaped oscillator group is the wiring mounting surface for mounting the wiring means for supplying the drive pulse to the common internal electrodes and the individual internal electrodes, the flexible cable is used for the comb-shaped oscillator group. Connection can be made only on the side surface, and wiring work can be easily performed.

According to the invention described in claim 12 ,
Since the vibrator has a hollow structure due to the opening formed in the vibrator, the capacitance can be reduced without changing the outer shape of the vibrator. Therefore, the thickness of the vibrator in the piezoelectric body stacking direction can be increased, and the island portion of the elastic sheet can be pressed as a whole. Along with this, the displacement of the vibrator can be efficiently transmitted to the island portion, and the volume of the pressure chamber can also be efficiently changed. Therefore, the ink droplets can be efficiently ejected.

According to the invention described in claim 13 ,
Since both ends of the island portion are projected in the piezoelectric body stacking direction more than the tip of the vibrator, the displacement of the island portion can be efficiently converted into the volume change of the pressure chamber. Therefore, the ink droplets can be ejected more efficiently.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view showing a main part of a piezoelectric vibrator unit and an inkjet recording head according to the present invention.

FIG. 2 is an external perspective view of a piezoelectric vibrator unit.

3A and 3B are explanatory views of a drive vibrator, in which FIG. 3A is a sectional view taken along line AA in FIG. 2, FIG. 3B is an enlarged sectional view of a free end portion of the drive vibrator, and FIG. Enlarged sectional view of the part,
(D) is an enlarged sectional view of a base end portion of the opening.

FIG. 4 is a diagram illustrating a process of producing a piezoelectric vibrator unit, FIG. 4A is a diagram illustrating a large plate-shaped piezoelectric body,
(B) is a figure explaining the individual internal electrode printed on the printing area | region of the surface of a plate-shaped piezoelectric body, (c) is a figure explaining the common internal electrode printed on a printing area, (d) becomes a spacer FIG. 3 is a diagram for explaining the piezoelectric body, and FIG. 6 (e) is a diagram for explaining the tooth division of the vibrator.

FIG. 5 is a diagram illustrating a vibrator according to a second embodiment.

FIG. 6 is a diagram illustrating a vibrator according to a third embodiment.

FIG. 7 is a diagram illustrating a vibrator according to a fourth embodiment.

FIG. 8 is a diagram illustrating a vibrator according to a fifth embodiment.

FIG. 9 is a diagram illustrating a vibrator according to a sixth embodiment.

[Explanation of symbols]

1 recording head 2 cases 3 flow path unit 4 Piezoelectric vibrator unit 5 accommodation space 6 Ink supply pipe 7 Flow path forming plate 8 nozzle plate 9 Elastic sheet 10 nozzle openings 11 Reservoir 12 Pressure chamber 13 Ink supply port 14 Elastic membrane 15 stainless steel plate 16 islands 17 Elastic part 21 Transducer group 22 Fixed plate 23 opening 24 flexible cable 28 Dummy oscillator 29 Drive oscillator 30 Common electrode wiring part 31 Piezoelectric body 32 common internal electrode 33 Individual internal electrodes 34 laminate 35 Spacer 36 individual external electrodes 37 Common external electrode 38 Individual electrode wiring section 41 print area 42 through holes 44 Individual spacer electrode 45 common spacer electrode 47 spacer

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B41J 2/045 B41J 2/055 B41J 2/16

Claims (13)

(57) [Claims] 1. A vibrator comprising a common internal electrode and an individual internal electrode, which are alternately laminated with a piezoelectric body sandwiched therebetween, is arranged in a comb-tooth shape, and a fixing plate is provided while leaving a free end of the vibrator. A piezoelectric vibrator unit in which a free end of a vibrator is expandable / contractible in a vibrator longitudinal direction orthogonal to a stacking direction of piezoelectric bodies, in which a hollow structure is formed so that the free end of the vibrator penetrates in a vibrator array direction.
Opened an opening becomes, corresponding to the proximal end from the distal end of the opening
The weight of the common internal electrode and the individual internal electrode is
A piezoelectric vibrator unit characterized in that the piezoelectric vibrator unit is arranged so that the mating region fits . 2. The piezoelectric vibrator unit according to claim 1, wherein the fixing plate is bonded to one side surface of the comb-shaped vibrator group. 3. The vibrator includes a plurality of laminated bodies in which a common internal electrode and an individual internal electrode are alternately laminated with a piezoelectric body sandwiched therebetween, and a bridge portion which joins the laminated bodies arranged in parallel in a separated state. The piezoelectric vibrator unit according to claim 1 or 2 , wherein the piezoelectric vibrator unit is provided in a non-actuating portion at a tip portion of the vibrator. 4. Any of Claims 1 to 3, characterized in that bonding the fixing plate in a state of aligning the position of the tip of the fixing plate and the position of the proximal end of the opening in a comb-like transducer group The piezoelectric vibrator unit according to claim 1. Wherein the opening, the piezoelectric vibrator unit according to any one of claims 1 to 4, characterized in that a plurality opened along the stacking direction of the piezoelectric element. Wherein the opening, the piezoelectric vibrator unit according to any one of claims 1 to 5 along the longitudinal direction of the vibrator, characterized in that a plurality opened. Wherein said common inner electrode and the piezoelectric vibrator unit according to claim 1, characterized in that partitions the opening 6 of the at least one of the internal electrodes of the individual internal electrodes. 8. The vibrator includes a plurality of laminated bodies in which a common internal electrode and an individual internal electrode are alternately laminated with a piezoelectric body sandwiched between the laminated body, and the laminated body is interposed between the laminated bodies to form the opening. and a spacer, piezoelectric vibrator unit according to any one of claims 1 to 7, characterized in that the formation of the internal electrode to the spacer. 9. The vibrator includes a plurality of laminated bodies in which a common internal electrode and an individual internal electrode are alternately laminated with a piezoelectric body sandwiched between the laminated body and the laminated bodies to form the opening. The piezoelectric vibration according to any one of claims 1 to 8 , further comprising: a spacer, the spacer being made of a material having a linear expansion coefficient substantially equal to a linear expansion coefficient of the laminate. Child unit. 10. The piezoelectric vibrator unit according to claim 9 , wherein the spacer is made of the same piezoelectric material as the piezoelectric material forming the laminated body. 11. The vibrator includes a laminated body in which a common internal electrode and an individual internal electrode are alternately laminated with a piezoelectric body sandwiched therebetween, and a spacer interposed between the laminated bodies to form the opening. And the spacer is made of a conductive material and is electrically connected to only one of the common external electrode electrically connected to the common internal electrode or the individual external electrode electrically connected to the individual internal electrode. The piezoelectric vibrator unit according to any one of claims 1 to 6 and claim 9 , wherein the piezoelectric vibrator unit is connected. 12. A piezoelectric vibrator unit according to any one of claims 1 to 11, an ink jet head comprising a pressure chamber partitioned by the nozzle plate forming the elastic sheet and the nozzle opening An ink jet recording head, wherein the elastic sheet is composed of an elastic film and an island portion provided corresponding to a nozzle opening, and a tip of a vibrator is brought into contact with the island portion. 13. The both end portions of the island portion are projected in the piezoelectric body stacking direction from the tip of the vibrator.
12. The ink jet recording head according to item 12 .