JP2011014794A - Piezoelectric actuator, droplet discharge head, and image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a piezoelectric actuator achieving increase of integration and reduction of cost by improving a displacement amount; a droplet discharge head using the same; and an image formation device.SOLUTION: The piezoelectric actuator includes a substrate 10 arranged to have, on a surface of an elastic body 21a with piezoelectric elements 21 arranged thereon, a predetermined space between the piezoelectric elements 21 and itself. The piezoelectric element 21 is composed by laminating, sequentially from the elastic body side: a first common electrode 21b with a voltage applied thereto in common among the respective piezoelectric elements; a piezoelectric film 21c; and an individual electrode 21d with a voltage applied thereto individually among the piezoelectric elements. The substrate 10 has a second common electrode 12 corresponding to each of the piezoelectric elements on a surface facing the piezoelectric elements.

Description

  The present invention relates to a piezoelectric actuator, and more particularly to a piezoelectric actuator using a thin piezoelectric film as a piezoelectric element, a droplet discharge head using the same, and an image forming apparatus.

Actuators using piezoelectric elements are widely used as pressure generating elements for droplet discharge heads. In particular, one using a flexural vibration mode actuator is said to be advantageous in terms of high integration. In addition to the merit of miniaturizing the chip on which the actuator was created by integrating the actuator highly, such an actuator has a chip size after a large number of chips are built on a substrate of a certain size. Since the number of chips that can be taken from a single substrate is increased by reducing the chip size, the cost reduction effect is great. Further, for example, when used as a pressure generating element of a head of an image forming apparatus, there is an advantage that a high-definition image can be easily created.
However, in order to achieve high integration, an improvement in the amount of displacement is required to ensure not only the machined surface but also the deformation volume. And many proposals, such as prescribing the shape of a vibration part (patent documents 3 and 4) which prescribe a piezoelectric material (patent documents 1) and electrode material (patent documents 2), etc. are made to this demand, for example. ing.
Even in these configurations, it is possible to improve the displacement amount of the actuator, but it is desirable that the displacement amount of the actuator is as large as possible, and further improvement of the displacement amount is required.

  In view of the present situation, an object of the present invention is to provide a piezoelectric actuator that achieves high integration and low cost by improving the amount of displacement, a droplet discharge head using the same, and an image forming apparatus. .

In order to solve the above problems, the invention of claim 1 includes a plurality of piezoelectric elements provided on one surface of an elastic body, and a voltage is applied to the piezoelectric elements to cause flexural vibration, whereby the elastic A piezoelectric actuator for displacing a body in the bending direction, comprising a substrate provided on the surface of the elastic body on which the piezoelectric element is provided so as to have a predetermined gap from the piezoelectric element. A first common electrode to which a voltage is commonly applied between the piezoelectric elements, a piezoelectric film, and an individual electrode to which a voltage is individually applied between the piezoelectric elements are sequentially stacked from the elastic body side. The substrate is characterized by a piezoelectric actuator having a second common electrode corresponding to each of the piezoelectric elements on a surface facing the piezoelectric element.
According to a second aspect of the present invention, the piezoelectric actuator according to the first aspect, the substrate, a plurality of pressurized liquid chambers corresponding to the plurality of piezoelectric elements, and the pressurized liquid chambers communicate with each other. A droplet discharge head having a nozzle plate having a plurality of nozzle holes is characterized.
According to a third aspect of the present invention, in the liquid droplet ejection head according to the second aspect, a constant voltage is applied to the second common electrode to move the plurality of piezoelectric elements to the second common electrode side. When the droplet is ejected from any of the plurality of nozzle holes, the same voltage as the second common electrode is applied to the individual electrode of the piezoelectric element corresponding to the nozzle hole to be ejected, A droplet discharge head is characterized in that the piezoelectric element is bent in the direction of the pressurized liquid chamber by a potential difference between the individual electrode and the first common electrode.

According to a fourth aspect of the present invention, in the liquid droplet ejection head according to the second aspect, a voltage larger than a driving voltage of the individual electrode is applied to the second common electrode to thereby apply the plurality of piezoelectric elements. The voltage applied to the second common electrode while applying the drive voltage to the individual electrode when the liquid droplet is ejected from any of the plurality of nozzle holes, deflected to the second common electrode side. A droplet discharge head that changes the voltage to the same voltage as the drive voltage and deflects the piezoelectric element in the direction of the pressurized liquid chamber due to a potential difference between the individual electrode and the first common electrode. To do.
According to a fifth aspect of the present invention, in the image forming apparatus equipped with the liquid droplet ejection head for ejecting liquid droplets, the liquid droplet ejection head is the liquid droplet ejection head according to any one of claims 2 to 4. It is characterized by being.

  As described above, according to the actuator device of the present invention, the actuator device includes a plurality of piezoelectric elements including the common electrode, the piezoelectric layer, and the individual electrodes provided on one surface of the elastic body, and is disposed individually and via a gap. By providing a fixed electrode common to a plurality of piezoelectric elements, it is possible to improve the amount of actuator displacement, so that high integration and cost reduction of the actuator can be achieved.

FIG. 3 is an exploded perspective view showing an example of the configuration of a droplet discharge head using the piezoelectric actuator of the present invention as pressure generating means. FIG. 2 is a plan layout view of a configuration of a droplet discharge head according to the present embodiment. Sectional drawing in the X1-X1 'line | wire of FIG. Sectional drawing in the X2-X2 'line | wire of FIG. Sectional drawing in the Y1-Y1 'line | wire of FIG. Sectional drawing in the Y2-Y2 'line | wire of FIG. The figure which shows the example of a drive of the conventional piezoelectric element. The figure which shows the 1st drive example of the piezoelectric element of this invention. The figure which shows the 2nd drive example of the piezoelectric element of this invention. The figure which shows the droplet cartridge concerning this invention. 1 is a diagram illustrating an example of a mechanism of an ink jet recording apparatus according to the present invention. 1 is a diagram illustrating an example of a mechanism of an ink jet recording apparatus according to the present invention.

Embodiments of the present invention will be described below in detail with reference to the drawings.
FIG. 1 is an exploded perspective view showing an example of the configuration of a droplet discharge head using the piezoelectric actuator of the present invention as pressure generating means. FIG. 2 is a plan layout view of the configuration of the droplet discharge head of this embodiment. 3 is a cross-sectional view taken along line X1-X1 ′ of FIG. 4 is a cross-sectional view taken along line X2-X2 ′ of FIG. FIG. 5 is a cross-sectional view taken along line Y1-Y1 ′ of FIG. 6 is a cross-sectional view taken along line Y2-Y2 ′ of FIG.
In each of these drawings, only a part is shown for convenience, but in reality, a larger number of nozzle rows of, for example, 100 nozzles or more per row are often arranged. In addition, the figure is deformed, the scale is not unified, and detailed portions are omitted.

The configuration of a droplet discharge head using the piezoelectric actuator of the present invention will be described with reference to FIGS.
As shown in FIG. 1, the droplet discharge head of this embodiment includes a first substrate 10 as an actuator substrate, a nozzle plate 40 in which a plurality of nozzle holes 41 for discharging droplets are formed, and each nozzle hole (channel). 41 is mainly composed of a pressurized liquid chamber 33 communicated with 41 and a second substrate (liquid chamber substrate) 20 on which a piezoelectric element 21 for generating a pressure is generated in each pressurized liquid chamber. It functions as a droplet cartridge by having a frame, FPC (Flexible Printed Circuit), and driver IC.
As the first substrate 10, it is preferable to use a material that does not greatly differ from the second substrate 20 in thermal expansion coefficient. In this embodiment, the first substrate 10 is formed using a glass substrate. Further, a liquid supply path 17 for supplying a liquid such as ink (not shown) was formed on the first substrate 10 by sandblasting. This can be performed by laser processing or the like, or can be performed by machining or etching depending on the material of the substrate.
Further, on the second substrate side of the first substrate 10, the fixed electrode 12 corresponding to each of the pressurized liquid chambers 33 of the second substrate and the convex portion 11 shown in FIG. 3 are formed.

As shown in FIGS. 5 and 6, the fixed electrode 12 is formed with a wiring 13, and the fixed electrode is supplied from an external power source through an FPC (not shown) connected to the electrode terminal portion 14 of the wiring 13. A voltage is applied to 12. An adhesive layer 15 that also serves as a spacer is formed between the second substrate 20 and the second substrate 20. Further, the gap between the second substrate 20 and the first substrate 10 is sealed with a sealant 16.
The protrusion 11 was formed by etching the other part of the first substrate by about 0.15 μm. The fixed electrode 12 was formed of a conductor layer having a thickness of about 0.05 μm. Furthermore, the wiring 13 and the electrode terminal portion 14 formed integrally therewith were formed of, for example, aluminum (Al) having a thickness of about 0.5 μm. The adhesive layer 15 was made of polyimide adjusted to have a thickness of about 0.2 μm after adhesion (after pressure bonding).

Next, on the second substrate 20, a common liquid chamber 31 corresponding to and communicating with the liquid supply path 17 is formed, and further, a pressure for ejecting liquid droplets from the plurality of fluid resistance portions 32 and the nozzle holes 41 is generated. The pressurized liquid chamber 33 is integrally formed (FIG. 5).
The second substrate 20 is made of a silicon single crystal substrate, and silicon dioxide (SiO ₂ ) and tetrasilicon nitride (Si ₃ N ₄ ) formed, for example, by thermal oxidation or the like are formed on the surface of the first substrate 10 side. An elastic film 21a as a diaphragm having a thickness of about 1.0 μm is formed.
Further, as shown in FIG. 3, a lower electrode film 21b that is a common electrode, a piezoelectric layer (piezoelectric film) 21c, and an upper electrode film 21d that is an individual electrode are laminated on the elastic film 21a. The pressure chambers 33 are separated to form the piezoelectric element 21. An insulating film 22 is formed so as to cover at least the side surfaces of the lower electrode 21b, the piezoelectric layer 21c, and the upper electrode film 21d.
A wiring layer 23 is connected to the lower electrode film 21b and the upper electrode film 21d, and voltage is applied to the lower electrode film 21b and the upper electrode film 21d through the wiring layer 23 from the electrode terminal portion 24 (FIGS. 4 and 5). (In detail, a voltage is applied to the lower electrode film 21b, which is a common electrode, by the wiring 23a shown in FIG. 1, and a voltage is applied to the upper electrode film 21d, which is an individual electrode, by the wiring 23b. ).
A voltage is applied to the lower electrode film 21b and the upper electrode film 21a, and the elastic film 21a is also bent due to the piezoelectric film 21b being bent by the potential between them, thereby generating pressure in the pressurized liquid chamber 33. Let

The fixed electrode 12 formed on the first substrate 10 and the piezoelectric element 21 and the pressurized liquid chamber 33 formed on the second substrate 20 are arranged with their positions aligned. The lower electrode film 21b is made of, for example, a material having a relatively high conductivity such as platinum (Pt) or iridium (Ir) having a thickness of about 0.1 μm. The piezoelectric layer 21c is made of, for example, lead zirconate titanate (PZT) having a thickness of about 1.0 μm. The upper electrode film 21d is made of, for example, platinum (Pt), iridium (Ir), or the like having a thickness of 0.05 to 0.1 μm. These thicknesses are desirably adjusted as appropriate according to the material used, the target specifications of the actuator, and the like. The insulating film 22 is made of, for example, alumina (Al ₂ O ₃ ) or silicon tetranitride (Si ₃ N ₄ ) having a thickness of about 0.2 μm with little moisture permeation and absorption. In such a configuration, the distance between the fixed electrode 12 and the upper electrode film 21d is about 0.35 μm, and the distance between the upper electrode and the convex portion 11 is 0.25 μm.
Further, as shown in FIG. 3, in the first substrate, the protrusion 11 is formed to protrude 0.1 μm to the upper electrode film 21d side from the fixed electrode 12, so that the fixed electrode 12 and the upper electrode film 21d are formed. Prevents contact. This interval can be adjusted according to the thickness and configuration of each layer mentioned above, and is preferably adjusted to a desirable interval for the characteristics of the actuator.
Next, as known, for example, glass ceramics, a silicon single crystal substrate, stainless steel or the like can be used for the nozzle plate 40. In this embodiment, after a nozzle hole 41 is opened by press working on stainless steel having a thickness of 30 μm, a fluorine-based resin is deposited on the surface on the liquid outlet side by vapor deposition as a liquid repellent film. Further, the second substrate 20 is bonded with an adhesive.
As described above, the piezoelectric actuator used in the liquid ejection head of the present invention has the lower electrode (common electrode) 21b, the piezoelectric layer 21c, and the upper electrode (lower electrode) 21a provided on one surface of the diaphragm. And a fixed electrode 12 that is common to the plurality of piezoelectric elements arranged through the gap with the upper electrode 21a.

The driving characteristics of the piezoelectric actuator having such a configuration will be described below.
FIG. 7 is a diagram showing a driving method of a conventional piezoelectric actuator that does not have a fixed electrode in the present embodiment, and FIG. 8 is a diagram showing a first driving method of the piezoelectric actuator of the present embodiment.
A first driving example of this embodiment will be described in comparison with a driving example having a conventional configuration (FIG. 7).
In both the conventional configuration and the configuration of the present invention, the discharge nozzle (the nozzle that discharges the liquid) and the non-discharge nozzle (the nozzle that does not discharge the liquid) are the respective upper electrode films that are individual electrodes corresponding to each nozzle of the piezoelectric actuator. It is selected by the driver IC connected to 21d.
That is, as shown in FIG. 7A, a pulse voltage of, for example, voltage 0 → Vp → 0 is applied to the upper electrode film corresponding to the discharge timing, as shown in FIG. A certain lower electrode is always kept at 0 V (reference voltage).
On the other hand, for the non-ejection nozzles, as shown in FIG. 7B, both electrodes remain at 0 V (reference voltage).
On the other hand, in the configuration of the present invention, as shown in FIG. 8, the lower electrode film 21b is the first common electrode, and is always kept at 0V (reference voltage), and the fixed electrode 12 is the second common electrode. Is kept at the voltage Vp.

In the case of the discharge nozzle shown in FIG. 8A, a pulse voltage such as voltage 0 → Vp → 0 is applied to the upper electrode film 21d corresponding to the discharge timing, and the non-shown state shown in FIG. In the case of a discharge nozzle, the upper electrode 21d is kept at 0V (reference voltage).
At this time, in the conventional configuration, as shown in FIG. 7A, the actuator of the discharge nozzle has a flexure of 0 when t <t0 and a voltage Vp is applied when t0 <t <t1. Due to the force generated in the pressure chamber, δ1 is deflected toward the pressurized liquid chamber, and at this time, the liquid droplet in the pressurized liquid chamber is pressurized and the liquid droplet is ejected from the nozzle hole. Further, when t1 <t, the deflection becomes 0 and the initial state is restored. Further, in the non-ejecting nozzle, the deflection amount is kept at 0, and the liquid is not ejected.
On the other hand, in this embodiment, the actuator of the discharge nozzle is bent by δ2 toward the fixed electrode due to electrostatic attraction caused by the voltage Vp between the fixed electrode 12 and the upper electrode film 21d at t <t0 as shown in FIG. Mu
Since the voltage between the fixed electrode 12 and the upper electrode film 21d is 0 at t0 <t <t1, no electrostatic attractive force acts between them, and the piezoelectric body between the upper electrode film 21d and the lower electrode film 21b does not work. Only the force works, and δ1 bends toward the pressurized liquid chamber 33 side just like the conventional configuration. At t1 <t, similarly to t <t0, δ2 bends to the fixed electrode side due to electrostatic attraction by the voltage Vp between the fixed electrode 12 and the upper electrode film 21d. That is, for the discharge nozzle, the amount of displacement of the actuator increases by the amount of deflection δ2 due to electrostatic attraction.

For the non-ejection nozzle, as shown in FIG. 8A, the voltage between the fixed electrode 12 and the upper electrode film 21d is kept at Vp, and the voltage between the lower electrode film 21b and the upper electrode film 21d is 0. Since it is maintained, the amount of deflection of the actuator is kept constant at δ2, so that no liquid is discharged.
In addition, the voltage applied to the fixed electrode 12 at this time is common to all actuators, and is a constant voltage, and the voltage is also equal to the magnitude of the voltage applied to the piezoelectric body 21, so that the voltage is applied to the second common electrode 12. There is almost no increase in the cost of the drive circuit and the like caused by the above. Therefore, the merit of cost reduction due to the integration of the actuator can be almost received as it is.
In addition, here, as a driving example, a description has been given of so-called “pushing” in which liquid is discharged by reducing the volume of the pressurized liquid chamber at the time of discharge, but “pulling” ( Once the volume of the pressurized liquid chamber is increased and the meniscus is drawn from the nozzle surface, the liquid is discharged by returning the volume of the pressurized liquid chamber to the original in accordance with the timing of the pressure wave generated in the pressurized liquid chamber. Method).

FIG. 9 is a diagram showing a second driving method of the piezoelectric actuator of the present embodiment.
In the first driving method shown in FIG. 8, a fixed voltage Vp is applied to the fixed electrode 12 which is the second common electrode. However, in the second driving method, Vp2, t0 <when t <t0. A voltage is applied such that Vp when t <t1 and Vp2 (Vp2> Vp) when t1 <t.
At this time, as shown in FIG. 9A, in the discharge nozzle, when t <t0 and t1 <t, a large voltage is applied between the fixed electrode 12 and the upper electrode film 21d, so that the actuator moves in the direction of the fixed electrode 12. To be larger (δ3). Further, when t0 <t <t1, no voltage is applied between the fixed electrode 12 and the upper electrode film 21d, so that the pressure liquid chamber 33 is bent by δ1 as in the conventional configuration and the first driving method.
That is, at t <t0 and t1 <t, the amount of displacement of the actuator is increased by the amount (δ3-δ2) that is largely deflected toward the fixed electrode 12 than in the first driving method.

On the other hand, as shown in FIG. 9B, in the non-ejection nozzle, when t <t0 and t1 <t, an electrostatic force is generated by the voltage Vp2 between the fixed electrode 12 and the upper electrode film 21d (a voltage is applied to the piezoelectric layer 21c). The amount of bending of the actuator is δ3, and at t0 <t <t1, the force is not applied to the piezoelectric layer 21c due to the electrostatic force due to the voltage Vp between the fixed electrode 12 and the upper electrode film 21d. (Does not occur) The amount of deflection of the actuator is δ2, and some (δ3-δ2) vibration is generated, but by adjusting the magnitudes of the applied voltages Vp and Vp2, it is vibrated but the liquid is not discharged. can do. As a result, it is possible to obtain a larger displacement amount of the actuator than in the first driving method. On the other hand, by applying a step voltage instead of a constant voltage to the fixed electrode 12 that is the second common electrode, a slight increase in the cost of the drive circuit occurs.
However, since it is a common electrode, only one new drive waveform is applied to all the actuators, so it is possible to reduce the total cost together with the cost reduction by integrating the actuators.

Next, a liquid cartridge to which the droplet discharge head of the present invention is applied will be described with reference to FIG.
The ink cartridge integrated head 95 includes an ink jet head 61 that is a droplet discharge head according to any of the above embodiments having the nozzle holes 41 and the like, and an ink tank 62 that supplies ink to the ink jet head 61. It is an integrated one.
Thus, by integrating the ink tank (liquid tank) that supplies ink to the droplet discharge head according to the present invention, there is little variation in the droplet discharge characteristics, and a liquid that integrates a highly reliable droplet discharge head. A cartridge (ink tank integrated head) can be obtained at low cost.
The droplet discharge heads of these embodiments constitute a part of a recording head unit having an ink flow path communicating with an ink cartridge and the like, and are mounted on an ink jet recording apparatus.
While the embodiments of the present invention have been described above, the basic configuration of the ink jet recording head is not limited to that described above.

Next, an example of the mechanism of an ink jet recording apparatus equipped with an ink jet head which is a droplet discharge head according to the present invention will be described with reference to FIGS.
This ink jet recording apparatus includes a carriage movable in the main scanning direction inside the recording apparatus main body 81, a recording head comprising the ink jet head according to the present invention mounted on the carriage, an ink cartridge for supplying ink to the recording head, and the like. A paper feed cassette (or a paper feed tray) 84 on which a large number of sheets 83 can be stacked from the front side is detachably attached to the lower part of the apparatus main body 81. The manual feed tray 85 for manually feeding the paper 83 can be opened, the paper 83 fed from the paper feed cassette 84 or the manual feed tray 85 is taken in, and the printing mechanism unit 82 takes After the image is recorded, it is discharged onto a discharge tray 86 mounted on the rear side.
The printing mechanism unit 82 holds the carriage 93 slidably in the main scanning direction (perpendicular to the paper surface) by a main guide rod 91 and a sub guide rod 92 which are guide members horizontally mounted on left and right side plates (not shown). The carriage 93 is provided with a plurality of heads 94 composed of inkjet heads, which are droplet ejection heads according to the present invention, which eject ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (Bk). The ink discharge ports are arranged in a direction crossing the main scanning direction, and are mounted with the ink droplet discharge direction facing downward. In addition, each ink cartridge 95 for supplying ink of each color to the head 94 is replaceably mounted on the carriage 93. The ink cartridge according to the present invention can be mounted.

The ink cartridge 95 has an air port that communicates with the atmosphere upward, a supply port that supplies ink to the inkjet head below, and a porous body filled with ink inside, and the capillary force of the porous body. Thus, the ink supplied to the inkjet head is maintained at a slight negative pressure.
Further, although the heads 94 of the respective colors are used here as the recording heads, a single head having nozzles for ejecting ink droplets of the respective colors may be used.
Here, the carriage 93 is slidably fitted to the main guide rod 91 on the rear side (downstream side in the paper conveyance direction), and is slidably mounted on the sub guide rod 92 on the front side (upstream side in the paper conveyance direction). is doing. In order to move and scan the carriage 93 in the main scanning direction, a timing belt 118 is stretched between a driving pulley 98 and a driven pulley 99 that are rotationally driven by a main scanning motor 97. The carriage 93 is driven to reciprocate by forward and reverse rotation of the main scanning motor 97.

On the other hand, in order to convey the paper 83 set in the paper feed cassette 84 to the lower side of the head 94, the paper feed roller 101 and the friction pad 102 for separating and feeding the paper 83 from the paper feed cassette 84 and the paper 83 are guided. A guide member 103, a transport roller 104 that reverses and transports the fed paper 83, a transport roller 105 that is pressed against the peripheral surface of the transport roller 104, and a leading end that defines a feed angle of the paper 83 from the transport roller 104 A roller 106 is provided. The transport roller 104 is rotationally driven by a sub-scanning motor 107 through a gear train.
A printing receiving member 100 is provided as a paper guide member that guides the paper 83 fed from the transport roller 104 below the recording head 94 in accordance with the movement range of the carriage 93 in the main scanning direction. A conveyance roller 111 and a spur 112 that are rotationally driven to send the paper 83 in the paper discharge direction are provided on the downstream side of the printing receiving member 100 in the paper conveyance direction, and the paper 83 is further delivered to the paper discharge tray 86. A roller 113 and a spur 114, and guide members 115 and 116 that form a paper discharge path are disposed.
At the time of recording, the recording head 94 is driven according to the image signal while moving the carriage 93, thereby ejecting ink onto the stopped sheet 83 to record one line. Record the line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 83 has reached the recording area, the recording operation is terminated and the paper 83 is discharged.

Further, a recovery device 117 for recovering defective ejection of the head 94 is disposed at a position outside the recording area on the right end side in the movement direction of the carriage 93. The recovery device 117 includes a cap unit, a suction unit, and a cleaning unit. The carriage 93 is moved to the recovery device 117 side during printing standby and the head 94 is capped by the capping means, and the ejection port portion is kept in a wet state to prevent ejection failure due to ink drying. Further, by ejecting ink that is not related to recording during recording or the like, the ink viscosity of all the ejection ports is made constant and stable ejection performance is maintained.
When a discharge failure occurs, the discharge port (nozzle) of the head 94 is sealed with a capping unit, and bubbles and the like are sucked out from the discharge port with the suction unit through the tube. Is removed by the cleaning means to recover the ejection failure. Further, the sucked ink is discharged to a waste ink reservoir (not shown) installed at the lower part of the main body and absorbed and held by an ink absorber inside the waste ink reservoir.
In such an image recording apparatus, the performance of the head is directly linked to the performance of the image recording apparatus. In this image recording apparatus, a low-cost and high-definition image recording apparatus can be provided by using a droplet discharge head using the low-cost and high-nozzle density actuator obtained by the present invention as pressure generating means.

DESCRIPTION OF SYMBOLS 10 1st board | substrate, 11 convex part, 12 fixed electrode, 13 wiring, 14 electrode terminal part, 15 adhesive layer, 17 liquid supply path, 20 2nd board | substrate, 21 piezoelectric element, 21a elastic film, 21b lower electrode film, 21c Piezoelectric layer, 21d Upper electrode film, 22 Insulating film, 23 Wiring layer, 24 Electrode terminal portion, 31 Common liquid chamber, 32 Fluid resistance section, 33 Pressurized liquid chamber, 40 Nozzle plate, 41 Nozzle hole, 61 Inkjet head , 62 Ink tank, 81 Recording device main body, 82 Printing mechanism, 83 Paper, 84 Paper feed cassette, 85 Tray, 86 Paper discharge tray, 91 Main guide rod, 92 Secondary guide rod, 93 Carriage, 94 Recording head, 95 Ink Cartridge, 97 main scanning motor, 98 driving pulley, 99 driven pulley, 100 printing receiving member, 101 paper feeding roller 102 friction pad, 103 guide member, 104 transport roller, 105 transport roller, 106 tip roller, 107 sub-scanning motor, 111 transport roller, 112 spur, 113 discharge roller, 114 spur, 115 guide member, 117 recovery device, 118 timing belt

JP 2006-186259 A JP 2007-149858 A Japanese Patent No. 3610811 JP 2004-066652 A

Claims (5)

A piezoelectric actuator comprising a plurality of piezoelectric elements provided on one surface of an elastic body, and applying a voltage to the piezoelectric elements to cause bending vibration, thereby displacing the elastic body in the bending direction,
On the surface of the elastic body where the piezoelectric element is provided, the piezoelectric element is provided with a substrate provided so as to have a predetermined gap,
The piezoelectric element includes, from the elastic body side, a first common electrode to which a voltage is commonly applied between the piezoelectric elements, a piezoelectric film, and an individual electrode to which a voltage is individually applied between the piezoelectric elements. It is constructed by stacking sequentially.
The piezoelectric actuator having a second common electrode corresponding to each of the piezoelectric elements on a surface of the substrate facing the piezoelectric element.   The piezoelectric actuator according to claim 1, the substrate, a plurality of pressurized liquid chambers corresponding to the plurality of piezoelectric elements, and a nozzle plate having a plurality of nozzle holes communicating with the pressurized liquid chambers, A droplet discharge head comprising: The droplet discharge head according to claim 2,
When applying a certain voltage to the second common electrode to bend the plurality of piezoelectric elements toward the second common electrode, and ejecting droplets from any of the plurality of nozzle holes, The same voltage as that of the second common electrode is applied to the individual electrode of the piezoelectric element corresponding to the nozzle hole to be ejected, and the piezoelectric element is caused by the potential difference between the individual electrode and the first common electrode. A droplet discharge head characterized by bending in the direction of the pressurized liquid chamber. The droplet discharge head according to claim 2,
A voltage larger than the drive voltage of the individual electrode is applied to the second common electrode to bend the plurality of piezoelectric elements toward the second common electrode,
When ejecting droplets from any of the plurality of nozzle holes, the drive voltage is applied to the individual electrodes and the voltage applied to the second common electrode is changed to the same voltage as the drive voltage, and the individual A droplet discharge head, wherein the piezoelectric element is bent in the direction of the pressurized liquid chamber by a potential difference between an electrode and the first common electrode.   An image forming apparatus equipped with a droplet discharge head for discharging droplets, wherein the droplet discharge head is the droplet discharge head according to any one of claims 2 to 4. .

Images