JP2003326704A - Liquid drop ejector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid drop ejector in which energy efficiency is enhanced by reducing the occupation area of a pressure generating part, and pulling ejection can be effected by applying a voltage only at the time of driving. <P>SOLUTION: A diaphragm 29a interposed between a piezoelectric actuator 20 and a cavity plate 10 has a first deformable part 29b and a second deformable part 29c, on the opposite sides of a protrusion 29e facing the pressure generating part 28a of the piezoelectric actuator 20. When the pressure generating part 28a elongates upon application of a voltage, the first deformable part 29b is pushed to displace the second deformable part 29c around a fulcrum part 29e in the direction for enlarging a pressure chamber 16. Consequently, a pressure variation takes place in ink in the pressure chamber 16 and the second deformable part 29c is reset by releasing application of the voltage to apply a pressure to the ink which is thereby ejected. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a droplet ejection device such as an inkjet head of an inkjet printer.

[0002]

2. Description of the Related Art Conventionally, a print head utilizing a piezoelectric type droplet ejecting device has been proposed. This is to change the volume of the liquid chamber by the dimensional displacement of the piezoelectric actuator so that the liquid (ink) in the liquid chamber is ejected from the nozzle when the volume decreases and the ink is introduced into the liquid chamber when the volume increases. Is. Then, a large number of such droplet ejecting devices are arranged close to each other, and ink is ejected from the droplet ejecting device at a predetermined position,
The desired character or image is formed.

As an ink jet print head using a conventional piezoelectric type liquid droplet ejecting apparatus, there is one shown in FIG. 16, for example. FIG. 16 is an enlarged sectional view of a conventional piezoelectric inkjet head. This piezoelectric ink jet head has nozzles 15 that open to the outside, pressure chambers 16 for supplying ink to the nozzles 15, and ink from an ink supply source (not shown) to a plurality of pressure chambers 16 via ink supply holes 18. The common ink chamber 12a to be distributed and the actuator including the pressure generating portion 28a for applying the pressure for ejecting the ink to the pressure chamber 16 are provided.

The pressure generating portion 28a is a portion of the piezoelectric actuator 20 in which the drive electrode 24 and the common electrode 25 sandwich the piezoelectric sheet 22 of the piezoelectric actuator 20, and is polarized in the direction from the drive electrode 24 to the common electrode 25. Is being processed. Drive electrode 24 and common electrode 25
When an electric field that matches the direction in which the polarization process is performed is applied between the pressure generating portion 28a and the piezoelectric actuator 2
It is stretched and displaced in the thickness direction of 0. Due to this displacement, the volume of the pressure chamber 16 is reduced, the ink in the pressure chamber 16 is pushed out, and ink droplets are ejected from the nozzle 15 communicating with the pressure chamber 16.

And more efficiently, that is, at low voltage,
In order to eject the ink droplets having the required ejection velocity and volume, the pressure generating portion 28a is arranged over almost the entire pressure chamber 16.

[0006]

However, in the conventional ink jet print head as described above, since the pressure generating portion is arranged over almost the entire pressure chamber, the capacitance proportional to the area of the pressure generating portion increases. However, there is a problem that the energy efficiency is poor and the cost of the power supply system for driving increases.

Further, in the ink jet print head as described above, it is suitable for so-called pushing, that is, the volume of the pressure chamber is reduced when a driving voltage is applied, and ink droplets are ejected. Therefore, there is a problem that the ink cannot be supplied in time and the driving frequency cannot be increased so much. Further, this method has a problem that the volume of the ink droplet cannot be made too large.

Therefore, as a method for increasing the driving frequency or increasing the volume of the droplet, the volume of the pressure chamber is first increased, and then the volume of the pressure chamber is changed from negative to positive. In the case of trying to perform so-called knock-out, that is, to restore the original, it is necessary to always apply a voltage to keep the volume of the pressure chamber small and to interrupt the voltage application only at the time of injection, Energy efficiency becomes worse.

At this time, in order to increase the volume of the ink chamber, it is conceivable to apply a reverse electric field, but in that case,
Only a low electric field that prevents polarization reversal can be applied, and sufficient ink droplets cannot be ejected.

The present invention has been made in order to solve the above-mentioned problems, and reduces the arrangement area of the pressure generating portion to improve energy efficiency, and at the same time, a voltage is applied during driving to cause a strike-out. It is an object of the present invention to provide a liquid droplet ejecting apparatus that can be used.

[0011]

In order to achieve the above object, a liquid droplet ejecting apparatus according to a first aspect of the present invention is provided with a nozzle that opens to the outside and a pressure for supplying liquid to each of the nozzles. A droplet ejecting apparatus comprising: a chamber, a pressure generating unit that applies a pressure for ejecting a liquid from the nozzle to the pressure chamber, and a vibration plate that is arranged between the pressure chamber and the pressure generating unit. The diaphragm has a first portion and a second portion that are displaced in opposite relation to each other with a fulcrum portion interposed therebetween, and the pressure generating portion is arranged to face the first portion, and at least The second portion is arranged so as to face the pressure chamber, and the first portion is displaced by the pressure from the pressure generating portion, so that the second portion is opposite to the first portion with the fulcrum portion interposed therebetween. The second portion of the volume in the first portion Than-position of the size and wherein the displacing only in a large volume.

In the liquid droplet ejecting apparatus having this structure, when pressure is applied from the pressure generating portion to the first portion to displace the first portion, the second portion moves to the opposite side of the first portion to the first portion. It is displaced by a larger volume than the part. Therefore, even if the area of the pressure generating portion that applies pressure to the first portion is small, a large volume change can be given to the second portion with a small energy.

According to a second aspect of the invention, in addition to the structure of the first aspect, the first portion and the second portion are arranged in the longitudinal direction of the pressure chamber. And the second portion is longer than the first portion in the longitudinal direction.

In the liquid drop ejecting apparatus having this structure, in addition to the function of the liquid drop ejecting apparatus according to the first aspect, the second portion is longer than the first portion in the longitudinal direction, so that the first portion is When pressure is applied to displace the first portion, the second portion is displaced on the side opposite to the first portion by a larger volume than the first portion due to the principle of leverage. Therefore, even if the area of the pressure generating portion that applies pressure to the first portion is small, a large volume change can be given to the second portion.

According to a third aspect of the present invention, in addition to the configuration of the first or second aspect of the liquid droplet ejecting device, the pressure generating portion is located opposite to the piezoelectric material in the polarization direction thereof. An electrode, wherein the piezoelectric material is expanded by applying a voltage to the electrode, and the first material according to the expansion
The second portion is displaced in a direction opposite to the displacement of the portion so as to expand the pressure chamber.

In the liquid drop ejecting device having this structure, in addition to the function of the liquid drop ejecting device according to the first or second aspect, when a voltage is applied to the electrode of the pressure generating part, the piezoelectric material expands to cause the first part to expand. Displace, the fulcrum part is a lever and the second part is the first
It is displaced so as to expand the pressure chamber on the side opposite to the part. Therefore, even if the area of the pressure generating portion is small, the pressure chamber is greatly expanded due to the lever principle, so that the capacitance of the pressure generating portion can be reduced and the voltage can be suppressed low. Also, when a voltage is applied, the second portion is displaced and the pressure chamber is expanded, so that it is possible to apply a voltage during ejection and to perform a strike-out. The cost of the power supply system can be reduced as compared with the method of shutting off.

According to a fourth aspect of the present invention, there is provided a liquid droplet ejecting apparatus, a nozzle opening to the outside, a pressure chamber for supplying the liquid to the nozzle, and a pressure for ejecting the liquid from the nozzle at the pressure. In a liquid droplet ejecting apparatus including a pressure generating section applied to a chamber and a vibrating plate arranged between the pressure chamber and the pressure generating section, the pressure generating section faces the piezoelectric material in the polarization direction thereof. A piezoelectric material is extended by applying a voltage to the electrode, wherein the vibrating plate has a first portion and a first portion that are displaced in cooperation with each other with a fulcrum portion interposed therebetween. Two parts, the pressure generating part is arranged to face the first part, and at least the second part is arranged to face the pressure chamber. By displacing the part of 1, the fulcrum part Sandwiched therebetween and the first part of the second portion of the opposite side, characterized in that for displacing in a direction to expand the pressure chamber.

In the liquid droplet ejecting apparatus having this structure, when a voltage is applied to the electrode of the pressure generating portion, the piezoelectric material expands and displaces the first portion, and the fulcrum portion becomes a lever and the second portion becomes the first portion.
It is displaced so as to expand the pressure chamber on the side opposite to the part. Therefore, even if the area of the pressure generating portion is small, the pressure chamber is greatly expanded due to the lever principle, so that the capacitance of the pressure generating portion can be reduced and the voltage can be suppressed low. Also, when a voltage is applied, the second portion is displaced and the pressure chamber is expanded, so that it is possible to apply a voltage during ejection and to perform a strike-out. The cost of the power supply system can be reduced as compared with the method of shutting off.

According to a fifth aspect of the invention, in addition to the configuration of the third or fourth aspect of the liquid droplet ejecting apparatus, the pressure generating unit includes the vibration plate in an actuator unit that covers the entire pressure chamber. Of the diaphragm, the diaphragm abuts on the pressure generating portion in the first portion, and forms a space between the second portion and the actuator unit. It is characterized by having done.

In addition to the operation of the liquid droplet ejecting apparatus according to the third or fourth aspect of the present invention, when a voltage is applied to the electrode of the pressure generating unit, the liquid droplet ejecting apparatus of the present invention has a diaphragm plate facing the pressure generating unit. The first portion is displaced, and the second portion is displaced around the fulcrum portion into the space between the fulcrum portion and the actuator unit, thereby expanding the volume of the pressure chamber.

According to a sixth aspect of the invention, in addition to the configuration of the fifth aspect, the nozzle and the pressure chamber are plural, and the actuator unit and the vibration plate are plural. In the actuator unit, there are a plurality of pressure generating portions corresponding to the pressure chambers.

In the liquid drop ejecting apparatus having this structure, in addition to the operation of the liquid drop ejecting apparatus according to the fifth aspect, since one actuator unit and the vibration plate are used across a plurality of nozzles and pressure chambers, a large number of them are used. The injection mechanism can be integrated to improve the resolution.

According to a seventh aspect of the invention, in addition to the configuration of the fifth or sixth aspect of the liquid droplet ejecting device, the vibrating plate is provided between the first portion and the second portion. And has a protruding portion that comes into contact with the actuator unit, and the vicinity of the protruding portion is displaced as the fulcrum portion.

In addition to the function of the droplet ejecting device according to the fifth or sixth aspect, the droplet ejecting device having this structure has a fulcrum for making the vibrating plate move like a lever by forming a protrusion on the vibrating plate. Can be easily formed without requiring a special member.

According to an eighth aspect of the present invention, in addition to the configuration of the first to sixth aspects, the first portion of the diaphragm is located outside the pressure chamber. The diaphragm is displaced between the first portion and the second portion with the vicinity of the portion of the diaphragm that abuts the outer wall of the pressure chamber as the fulcrum portion.

In the liquid drop ejecting apparatus having this structure, in addition to the function of the liquid drop ejecting apparatus according to any one of claims 1 to 6, the first portion is not displaced into the pressure chamber, and the pressure is applied by the second portion. Since the entire chamber is deformed in the same direction, the volume of the pressure chamber does not decrease, and the volume of the pressure chamber can be efficiently expanded.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments in which the droplet jetting device of the present invention is applied to an ink jet head will be described below with reference to the accompanying drawings. FIG. 1 is a perspective view showing the outline of a color inkjet printer equipped with the inkjet head of the present invention. As shown in FIG. 1, the inkjet printer 100 includes, for example, an ink cartridge 61 filled with four color inks of cyan, magenta, yellow, and black, and a paper 62 conveyed in the direction of arrow B in the figure. A head unit 63 provided with the piezoelectric inkjet head 6 for printing, a carriage 64 on which the ink cartridge 61 and the head unit 63 are mounted, and a drive for reciprocating the carriage 64 in a direction orthogonal to the conveyance direction of the paper 62. Unit 65
And a platen roller 6 that extends in the reciprocating direction of the carriage 64 and is arranged to face the piezoelectric inkjet head 6.
6 and a purging device 67.

The drive unit 65 has a carriage shaft 71 extending in parallel with the platen roller 66 arranged at the lower end of the carriage 64, a guide plate 72 arranged at the upper end of the carriage 64 extending in parallel with the carriage shaft 71, and its guide plate 72. Two pulleys 73 arranged between the carriage shaft 71 and the guide plate 72 at both ends of the carriage shaft 71,
74 and an endless belt 75 stretched between these pulleys 73, 74. When one of the pulleys 73 is rotated forward and backward by the drive of the motor 76,
With the forward and reverse rotation of the pulley 73, the carriage 64 joined to the endless belt 75 is linearly reciprocated along the carriage shaft 71 and the guide plate 72.

The paper 62 is fed from a paper feed cassette (not shown) provided on the side of the color ink jet printer 100, introduced between the piezoelectric ink jet head 6 and the platen roller 66, and the piezoelectric ink jet head. Predetermined printing is performed with the ink ejected from 6, and then the paper is ejected. In FIG. 1, the paper feed mechanism and the paper discharge mechanism for the paper 62 are not shown.

The purging device 67 is provided on the side of the platen roller 66 and is arranged so as to face the piezoelectric ink jet head 6 when the head unit 63 is in the reset position. The purging device 67 includes a cap 81 that abuts against an opening surface of a plurality of nozzles 15 of the piezoelectric inkjet head 6 described later, a pump 82, a cam 83, and an ink storage portion 84. . Then, when the head unit 63 is at the reset position, the nozzles 15 of the piezoelectric inkjet head 6 are covered with the cap 81, and defective ink containing bubbles and the like accumulated inside the piezoelectric inkjet head 6 is driven by the driving of the cam 83. When the pump 82 sucks the ink, the piezoelectric ink jet head 6 is recovered. As a result, it is possible to prevent ejection failure and the like due to the retention of ink and the growth of bubbles during the initial introduction of ink. The sucked defective ink is stored in the ink storage portion 84.

Next, the structure of the head unit 63 will be described with reference to FIGS. FIG. 2 is a perspective view of the head unit 63 in an inverted state. Figure 3
FIG. 3 is an exploded perspective view of the head unit 63 of FIG. 2. Figure 4
FIG. 6 is an exploded perspective view of the head unit 63 as seen from above. FIG. 5 is a bottom view of the head unit 63.

As shown in FIGS. 2 to 5, the head unit 63 mounted on the carriage 64 that runs along the paper 62 is formed in a substantially box-like shape with its upper surface opened, and four ink cartridges are provided from above. There is a cartridge mounting portion 3 to which the ink cartridge 61 can be detachably mounted, and one side portion 3a of the cartridge mounting portion 3 has each ink cartridge 6
Ink supply paths 4a, 4b, 4c, and 4d connectable to one ink discharge portion (not shown) communicate with the lower surface of the bottom plate 5 of the head unit 63. A packing (not shown) made of rubber or the like is arranged on the upper surface of the one side portion 3a of the cartridge mounting portion 3 so as to be in close contact with the ink discharge portion (not shown) of each ink cartridge 61. There is.

The bottom plate 5 is formed horizontally so as to project downward from the cartridge mounting portion 3 by one step. As shown in FIGS. 3 and 5, a piezoelectric ink jet head 6 is provided on the lower surface side of the bottom plate 5. Two support portions 8 for arranging two in parallel are formed in a stepped shape. Each supporting portion 8 has a plurality of cavities 9a, 9 for fixing with UV adhesive.
b is formed so as to penetrate vertically.

An ink supply path 4a is provided at one end of each support portion 8.
Communication portions 46a, 46b, 46c, and 46d that communicate with the ink cartridge 61 via the through 4d are provided.
A fitting groove 48 having a figure-eight shape or the like in a plan view is provided on the outer periphery of the communication portions 46a to 46d. A ring-shaped packing 47 made of rubber or the like is inserted into the fitting groove 48. When the piezoelectric inkjet head 6 is adhesively fixed to the support portion 8, the tip of the packing 47 is a piezoelectric inkjet described later. Ink supply port 19a of head 6
The ink supply port 19 is pressed against the outer periphery (see FIG. 8).
The contact point with a is sealed.

A protective cover 44 for protecting the piezoelectric ink jet head 6 fixed by adhesion is attached so as to cover the fixed bottom plate 5 of the piezoelectric ink jet head 6. The protective cover 44 is provided with two elliptical openings along the longitudinal direction of the protective cover 44 so that the nozzles 15 of the piezoelectric inkjet head 6 are exposed. Further, both ends in the longitudinal direction are bent in a substantially U-shape, and when the protective cover 44 is fixed, the flexible flat cable 40 of the piezoelectric inkjet head 6 is head unit so as to follow the fold line. It is adapted to be bent and fixed above 63.

Next, the structure of the piezoelectric ink jet head 6 will be described with reference to FIGS. 6 to 10. Figure 6
FIG. 3 is an exploded perspective view of the piezoelectric inkjet head 6. FIG. 7 is a side sectional view of the piezoelectric inkjet head 6. FIG. 8 is an exploded perspective view of the cavity plate 10. FIG. 9 is an exploded perspective view in which a main part of the cavity plate 10 is enlarged. FIG. 10 is an exploded perspective view in which a main part of the piezoelectric actuator 20 is enlarged.

As shown in FIGS. 6 and 7, the piezoelectric ink jet head 6 includes a plurality of laminated cavity plates 10 and a diaphragm 2 for the cavity plates 10.
A plate-type piezoelectric actuator 20, which is adhered and laminated via an adhesive or an adhesive sheet with 9a sandwiched between it, and a flexible flat cable 40 for electrical connection with an external device, is lap-bonded on the upper surface thereof with an adhesive. Ink is ejected downward from the nozzles 15 that are opened on the lower surface side of the lowermost cavity plate 10.

Next, as shown in FIG. 8, the cavity plate 10 comprises five thin metal plates, that is, a nozzle plate 11, two manifold plates 12, a spacer plate 13 and a base plate 14, which are respectively bonded with adhesive. It is a structure that is laminated and laminated. In the present embodiment, each of these plates 11 to 14 includes a 42% nickel alloy steel plate (42
Alloy) and has a thickness of about 50 μm to 150 μm. The plates 11 to 14 are not limited to metal and may be formed of resin, for example.

Further, as shown in FIG. 9, a plurality of narrow pressure chambers 16 extending in a direction orthogonal to the longitudinal centerlines 14a and 14b are formed in the base plate 14 in a staggered arrangement. There is. Corresponding to each pressure chamber 16, ink supply holes 16b are respectively formed at positions on both ends in the lateral direction of the base plate 14 with respect to the respective pressure chambers 16, and a narrowed portion recessed between the ink supply holes 16b. Each pressure chamber 16 and each ink supply hole 16b are connected by 16d. Each ink supply hole 16b communicates with the common ink chamber 12a in the manifold plate 12 via each ink supply hole 18 formed at both left and right sides of the spacer plate 13 in the lateral direction.
Here, the cross-sectional area of each throttle portion 16d in the direction orthogonal to the ink flowing direction is smaller than the cross-sectional area of each pressure chamber 16 in the same direction. This is to increase the flow path resistance for the ink that flows back toward the ink supply hole 16b during ejection. Further, one end portion 16a of each pressure chamber 16 has a minute diameter through hole formed in the staggered array of nozzles 15 in the nozzle plate 11, the spacer plate 13 and the two manifold plates 12 in the staggered array. It communicates through 17.

As shown in FIG. 8, the ink supply holes 1 for supplying the ink from the ink cartridge 61 to the common ink chamber 12a in the manifold plate 12 are formed in the base plate 14 and the spacer plate 13.
9a and 19b are respectively drilled. In addition, the nozzle plate 1 is attached to the two manifold plates 12.
Two common ink chambers 12a and 12b are provided along the longitudinal direction so as to sandwich the row formed by the plurality of nozzles 15 in one. The common ink chambers 12a and 12b are formed as openings penetrating each manifold plate 12, and the openings that are vertically overlapped form one common ink chamber, and one common ink chamber 12a communicates with the pressure chamber of one row. However, the other common ink chamber 12b communicates with the pressure chambers in the other row (see FIG. 9). The common ink chambers 12a and 12b are
A plurality of nozzles 15 are located in a plane parallel to the plane of the plurality of pressure chambers 16 of the base plate 14 and closer to the opening surface side of the plurality of nozzles 15 of the nozzle plate 11 than the plurality of pressure chambers 16. It extends long in the row direction.

Further, the common ink chambers 12a and 12b are separated from the ink supply holes 19a and 19b at the ends (C portions) in the direction away from the ink supply holes 19a and 19b.
The shape is such that its cross-sectional area decreases at a constant rate. this is,
This is for facilitating the discharge of residual bubbles that tend to accumulate at the ends (C portions) of the common ink chambers 12a and 12b. The common ink chambers 12a and 12b have a structure in which the nozzle plate 11 and the spacer plate 13 are stacked on the two manifold plates 12 to be hermetically sealed.

A plurality of nozzles 15 for ejecting ink having a minute diameter (about 25 μm in this embodiment) are arranged on the nozzle plate 11 along the longitudinal center lines 11a and 11b of the nozzle plate 11 at a minute pitch P. The holes are arranged in a staggered arrangement at intervals of. Each nozzle 15 corresponds to each through hole 17 of the manifold plate 12.

With the configuration of the cavity plate 10 described above, the ink supply holes 19a and 19b formed at one end of the base plate 14 and the spacer plate 13 are provided,
From the ink cartridge 61 to the common ink chambers 12a, 12
The ink that has flowed into b is supplied from the common ink chamber 12a to the ink supply holes 18, the ink supply holes 16b, and the throttle portion 16d.
Through which the pressure chambers 16 are distributed. Then, the ink flows in the direction of the one end portion 16a of each pressure chamber 16, and each through hole 1
7 to reach the nozzle 15 corresponding to each pressure chamber 16.

Next, as shown in FIG. 10, the piezoelectric actuator 20 has a structure in which two piezoelectric sheets 21 and 22 and one insulating sheet 23 are laminated. On the upper surface of the lowermost piezoelectric sheet 21, a plurality of drive electrodes 24 having a narrow width corresponding to each pressure chamber 16 in the cavity plate 10.
Are provided in a staggered arrangement. In addition, one end 24a of each drive electrode 24 is formed so as to be exposed on the left and right side surfaces 20c of the piezoelectric actuator 20 which are orthogonal to the front and back surfaces 20a and 20b.

A common electrode 25 common to the plurality of pressure chambers 16 is provided on the upper surface of the next-stage piezoelectric sheet 22. One end 25a of the common electrode 25 is also connected to each drive electrode 2
Similar to the one end portion 24a of No. 4, it is formed so as to be exposed on the left and right side surfaces 20c. Each drive electrode 24 and common electrode 25
The respective regions of the piezoelectric sheet 22 sandwiched between and serve as pressure generating portions 28a corresponding to the respective pressure chambers 16. The pressure generator 28a is polarized in the direction P from the drive electrode 24 toward the common electrode 25. In the present embodiment, the area occupied by the pressure generating portion 28a is configured to be about 10% of the area of the pressure chamber 16.

On the upper surface of the uppermost insulating sheet 23, a surface electrode 26 for each drive electrode 24 and a surface electrode 27 for the common electrode 25 are provided side by side along the left and right side surfaces 20c. In addition, on the left and right side surfaces 20c, the first recessed groove 30 is formed in the one end portion 24a of each drive electrode 24.
However, the second recessed groove 31 is formed in the one end 25a of the common electrode 25.
Are provided so as to extend in the stacking direction.
As shown in FIG. 7, side electrodes 32 that electrically connect the drive electrodes 24 and the surface electrodes 26 are provided in the first recessed grooves 30, and common side electrodes are provided in the second recessed grooves 31. Side electrodes 33 that electrically connect the electrodes 25 and the surface electrodes 27 are formed. Note that the electrodes 28 and 29 are electrodes having a discarded pattern.

Next, FIG. 11 is an enlarged sectional view of the piezoelectric ink jet head 6 of FIG. FIG. 11 shows a state in which the common ink chamber 12a and the pressure chamber 16 are filled with ink. As shown in FIG. 11, a vibration plate 29 is provided between the piezoelectric actuator 20 and the cavity plate 10.
a is arranged. The vibrating plate 29a has three space portions 29d, 29f, and 29g formed on the side in contact with the piezoelectric actuator 20 in the longitudinal direction of the pressure chamber 16 as concave portions by half etching or the like. Space 29
The protrusion 29e between g and 29d is abutted and fixed to the piezoelectric actuator 20 and serves as a fulcrum when the diaphragm 29a is displaced as described later. The diaphragm 29a corresponding to the spaces 29g to 29f on one side of the protrusion 29e.
Is the first deformable portion 29b, and the diaphragm 29 is sandwiched between the space 29d on the other side of the protrusion 29e and the pressure chamber 16.
The portion a is a second deformable portion 29c. The first deformable portion 29b is connected to the piezoelectric actuator 2 via the protrusion 29h.
It is in contact with a position facing the zero pressure generating portion 28a.
The first deforming portion 29b and the second deforming portion 29c are located corresponding to the pressure chamber 16, and the tip of the second deforming portion 29c does not reach the throttle portion 16d. The length of the first deforming portion 29b in the longitudinal direction of the pressure chamber 16 is shorter than the length of the second deforming portion 29c in the longitudinal direction of the pressure chamber 16. The spaces 29d, 29f, and 29g may be formed so that the first deformable portion 29b, the second deformable portion 29c, and the protrusion 29e can be secured, and are not limited to half etching.
The plate with holes may be arranged on the piezoelectric actuator 20, and the plate without holes may be arranged on the pressure chamber 16 side and laminated.

Next, the printing operation of the ink jet printer 100 will be described with reference to FIGS. As shown in FIG. 12, each drive electrode 24 of the piezoelectric actuator 20 in the piezoelectric inkjet head 6 is
When a positive voltage is applied to any of the drive electrodes 24 and the common electrode 25 is connected to the ground, an electric field E in a direction matching the polarization direction P is generated between the electrodes. The portion of the drive electrode 24 to which a voltage is applied, that is, the pressure generating portion 28a of the piezoelectric sheet 22 extends in the stacking direction due to the piezoelectric vertical effect.

This extension pushes the protrusion 29h to deform the first deforming portion 29b of the diaphragm 29a toward the pressure chamber 16 side. As a result, the second deformation portion 29c of the vibration plate 29a is deformed in the opposite direction, that is, inside the space portion 29d on the piezoelectric actuator 20 side, with the protrusion 29e serving as a fulcrum, and the volume of the pressure chamber 16 is increased. At this time, the first deforming portion 29b
The length in the longitudinal direction of the pressure chamber 16 of the second deformation portion 2
Since the length of the pressure chamber 16 is smaller than that of the pressure chamber 16 in the longitudinal direction of 9c, the amount by which the second deforming portion 29c increases the volume of the pressure chamber 16 is the first deforming portion 29b according to the lever principle.
Is much larger than the amount that reduces the volume on the pressure chamber 16 side, and as a result, the pressure chamber 1 corresponding to each drive electrode 24
The volume of 6 is greatly expanded, and the pressure in the pressure chamber 16 is reduced.

When the volume inside the pressure chamber 16 is expanded, the one-way propagation time T of the pressure wave generated at this time in the pressure chamber 16 is shown.
Just keep. Then, during that time, ink of the increased volume of the pressure chamber 16 is supplied from the common ink chamber 12a through the ink supply hole 18, the ink supply hole 16, and the throttle portion 16d.

The one-way propagation time T is the time required for the pressure wave in the pressure chamber 16 to propagate in the longitudinal direction of the pressure chamber 16 (left-right direction on the paper surface in the drawing). T = L / a is determined by the length L and the sound velocity a in the ink inside the pressure chamber 16. According to the theory of pressure wave propagation, the pressure in the pressure chamber 16 reverses after about T time from the application of the above voltage, and the pressure changes to a positive pressure. When the application of the voltage to the drive electrode 24 is released at this timing,
As shown in, the pressure generator 28a returns to its original state,
Since the second deforming portion 29c restores the volume of the pressure chamber 16 to the original,
Pressure is applied to the ink in the pressure chamber 16. then,
The positively turned pressure and the pressure generated by the return of the second deforming portion 29c are added, and a relatively high pressure is generated in the pressure chamber 1.
6 is generated in the vicinity of the nozzle 15 that communicates with the nozzle 6, and the ink droplet 90 is ejected from the nozzle 15 more efficiently than by simple push ejection.

As described above, in the piezoelectric ink jet head 6 according to this embodiment, the vibration plate 29a is
A first deformable portion 29b that is displaced toward the pressure chamber 16 side with the protrusion 29e that is a fulcrum portion interposed therebetween, and a second deformable portion that is displaced according to the displacement of the first deformable portion 29b into a space portion 29d on the opposite side of the pressure chamber 16. 29c are arranged side by side in the longitudinal direction of the pressure chamber 16, and the first deforming portion 29b faces the pressure generating portion 28a that is expanded and displaced by application of a voltage. Therefore, when the voltage is applied, the expansion of the pressure generating portion 28a is caused by the first deforming portion 29
Although b is displaced toward the pressure chamber 16 side to reduce the volume of the pressure chamber 16, the second deformable portion 29c is displaced into the space 29d with the protrusion 29e as a fulcrum to expand the volume of the pressure chamber 16.
Therefore, a high driving frequency and a pulling stroke advantageous for large volume injection can be easily achieved by applying a voltage during the injection. In addition, the length of the first deforming portion 29b in the longitudinal direction of the pressure chamber 16 is shorter than the length of the second deforming portion 29c in the longitudinal direction of the pressure chamber 16, so that the second deforming portion 29b has The amount by which the deforming portion 29c expands the volume of the pressure chamber 16 is larger than the amount by which the first deforming portion 29b decreases the volume on the pressure chamber 16 side, so that the pressure chamber 16 has a pressure for obtaining a desired volume change. The area of the generator 28a can be reduced, the electrostatic capacity of the pressure generator 28a can be reduced, and the pressure generator 28a can be driven at a lower voltage. Further, in the present embodiment, the spaces 29f, 29g, and 29d are provided by half etching or the like, so that the space between the projections 2 is formed.
9e, the fulcrum part is formed without using a special member,
The effect of the present invention is realized without complicating the configuration.

The present invention is not limited to the above embodiment, and various improvements and modifications can be made without departing from the spirit of the present invention. For example, FIG. 14 is an enlarged cross-sectional view illustrating the operation of the piezoelectric inkjet head according to another embodiment. As shown in FIG. 14, regarding the positional relationship between the first deforming portion and the second deforming portion, the first deforming portion 29b may be arranged on the ink supply hole 18 side to the pressure chamber 16. Similarly to the above-described embodiment, when a voltage is applied, as shown in FIG. 14, expansion in the stacking direction occurs due to the piezoelectric vertical effect in the pressure generating part 28a, and this expansion causes the first deforming part 29b of the diaphragm 29a. Are deformed to the pressure chamber 16 side, and the volume of the pressure chamber 16 is reduced. As a result, the second deformable portion 29c is deformed into the space 29d with the protrusion 29e as a fulcrum, and the volume of the pressure chamber 16 is increased.

FIG. 15 is an enlarged sectional view of a piezoelectric ink jet head of still another embodiment. In this embodiment, the first deformable portion 29b is not deformed into the pressure chamber 16, but the space 29g is provided outside the pressure chamber 16 at a portion facing the first deformable portion 29b. Also, the diaphragm 29a
A fulcrum portion is not provided above, and a fulcrum portion 29i is provided between the pressure chamber 16 and the space portion 29g. Space part 29g and fulcrum part 29
i is formed on the base plate 14 side by side with the pressure chamber 16. When a voltage is applied, expansion in the stacking direction occurs in the pressure generating portion 28a due to the piezoelectric vertical effect, and this expansion deforms the first deforming portion 29b into the space portion 29g. Space part 2
Since 9 g is outside the pressure chamber 16, the volume of the pressure chamber 16 does not decrease at all. Then, the second deformable portion 29c is deformed into the space 29d with the fulcrum portion 29i as a fulcrum, and the volume of the pressure chamber 16 is increased by the total volume of the deformation of the second deformable portion 29c. Therefore, the volume of the pressure chamber 16 can be expanded more efficiently.

[0055]

As is apparent from the above description, claim 1
According to the liquid droplet ejecting apparatus described in (1), when the pressure is applied to the first part from the pressure generating part to displace the first part, the second part is located on the side opposite to the first part. It is displaced by a larger volume than. Therefore, even if the area of the pressure generating portion that applies pressure to the first portion is small, that is, a large volume change can be given to the second portion with a small energy.

According to the liquid droplet ejecting apparatus of the second aspect,
In addition to the effect of the liquid droplet ejecting apparatus according to claim 1, since the second portion is longer than the first portion in the longitudinal direction, when the first portion is applied with pressure to displace the first portion. , The second portion is displaced by the lever principle to the side opposite to the first portion by a volume larger than that of the first portion. Therefore, even if the area of the pressure generating portion that applies pressure to the first portion is small, a large volume change can be given to the second portion.

According to the liquid droplet ejecting apparatus of the third aspect,
In addition to the effect of the droplet jetting device according to claim 1 or 2,
When a voltage is applied to the electrode of the pressure generating part, the piezoelectric material expands and displaces the first part, so that the fulcrum part becomes a lever and the second part expands the pressure chamber on the opposite side to the first part. Is displaced to. Therefore, even if the area of the pressure generating portion is small, the pressure chamber is greatly expanded due to the lever principle, so that the capacitance of the pressure generating portion can be reduced and the voltage can be suppressed low. Also, when a voltage is applied, the second portion is displaced and the pressure chamber is expanded, so that it is possible to apply a voltage during ejection and to perform a strike-out. The cost of the power supply system can be reduced as compared with the method of shutting off.

According to the droplet ejection device of the fourth aspect,
When a voltage is applied to the electrode of the pressure generating part, the piezoelectric material expands and displaces the first part, so that the fulcrum part becomes a lever and the second part expands the pressure chamber on the opposite side to the first part. Is displaced to. Therefore, even if the area of the pressure generating portion is small, the pressure chamber is greatly expanded due to the lever principle, so that the capacitance of the pressure generating portion can be reduced and the voltage can be suppressed low. Also, when a voltage is applied, the second portion is displaced and the pressure chamber is expanded, so that it is possible to apply a voltage during ejection and to perform a strike-out. The cost of the power supply system can be reduced as compared with the method of shutting off.

According to the droplet ejection device of the fifth aspect,
In addition to the effect of the liquid droplet ejecting apparatus according to claim 3 or 4,
When a voltage is applied to the electrode of the pressure generating portion, the first portion of the diaphragm facing the pressure generating portion is displaced, and the second portion around the fulcrum portion is displaced into the space between the actuator unit and the second portion. , Expand the volume of the pressure chamber.

According to the droplet ejection device of the sixth aspect,
In addition to the effect of the liquid droplet ejecting apparatus according to the fifth aspect, since one actuator unit and the diaphragm are used across a plurality of nozzles and pressure chambers, a large number of ejecting mechanisms can be integrated to improve the resolution. .

According to the liquid droplet ejecting apparatus of the seventh aspect,
In addition to the effects of the liquid droplet ejecting apparatus according to claim 5 or 6,
By forming a protrusion on the diaphragm, a fulcrum for the diaphragm to move like a lever can be easily formed without requiring a special member.

According to the liquid droplet ejecting apparatus of the eighth aspect,
In addition to the effect of the liquid droplet ejecting apparatus according to any one of claims 1 to 6, the first portion does not displace into the pressure chamber, and the second portion deforms the entire pressure chamber in the same direction. The volume of the pressure chamber does not decrease, and the volume of the pressure chamber can be efficiently expanded.

[Brief description of drawings]

FIG. 1 is a perspective view showing an outline of an inkjet printer 100 equipped with a piezoelectric inkjet head 6 of the present embodiment.

FIG. 2 is a perspective view of a head unit 63 in an inverted state.

FIG. 3 is an exploded perspective view of the head unit 63 of FIG.

FIG. 4 is an exploded perspective view of a head unit 63 seen from above.

5 is a bottom view of the head unit 63. FIG.

FIG. 6 is an exploded perspective view of the piezoelectric inkjet head 6.

FIG. 7 is a side sectional view of the piezoelectric inkjet head 6.

8 is an exploded perspective view of the cavity plate 10. FIG.

9 is an exploded perspective view showing an enlarged main part of a cavity plate 10. FIG.

FIG. 10 is an exploded perspective view showing an enlarged main part of the piezoelectric actuator 20.

11 is an enlarged cross-sectional view of the piezoelectric inkjet head 6 of FIG.

FIG. 12 is an enlarged cross-sectional view illustrating the operation of the piezoelectric inkjet head 6.

FIG. 13 is an enlarged cross-sectional view illustrating a state where ink droplets are ejected by the piezoelectric inkjet head 6.

FIG. 14 is an enlarged cross-sectional view illustrating the operation of the piezoelectric inkjet head according to another embodiment.

FIG. 15 is an enlarged cross-sectional view of a piezoelectric inkjet head according to another embodiment.

FIG. 16 is an enlarged cross-sectional view of a conventional piezoelectric inkjet head.

[Explanation of symbols]

6 Piezoelectric inkjet head 15 nozzles 16 Pressure chamber 20 Piezoelectric actuator 24 Drive electrode 25 common electrode 28a Pressure generator 29a diaphragm 29b First deformation part 29c Second deformation part 29d Space section 29e protrusion 29i Support point

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2C057 AF38 AF54 AF55 AF93 AG15                       AG33 AG44 AG47 AG52 AG53                       AG55 AG56 AG59 AG93 AG94                       AN01 AP02 AP14 AP25 AP31                       AQ06 BA04 BA14

Claims (8)

[Claims] 1. A nozzle opening to the outside, a pressure chamber for supplying a liquid to each of the nozzles, and a pressure generator for applying a pressure for discharging a liquid from the nozzle to the pressure chamber. In a liquid droplet ejecting apparatus including a vibrating plate arranged between the pressure chamber and the pressure generating section, the vibrating plate is a first portion that is displaced in cooperation with each other with a fulcrum portion interposed therebetween. And a second portion, and the pressure generating portion is arranged to face the first portion, and at least the second portion is provided.
Is disposed opposite to the pressure chamber, and by displacing the first portion by the pressure from the pressure generating portion, the first portion on the side opposite to the first portion with the fulcrum portion interposed therebetween is disposed. 2. A liquid droplet ejecting apparatus, wherein the second portion is displaced by a volume larger than the volume displacement of the first portion. 2. The first part and the second part are located side by side in the longitudinal direction of the pressure chamber, and the second part is longer than the first part in the longitudinal direction. The liquid droplet ejecting apparatus according to claim 1. 3. The pressure generating part comprises a piezoelectric material and electrodes positioned opposite to each other in a polarization direction thereof, and the piezoelectric material is expanded by applying a voltage to the electrode, and the piezoelectric material is expanded in accordance with the expansion. The liquid droplet ejecting apparatus according to claim 1, wherein the second portion is displaced in a direction opposite to the displacement of the first portion so as to expand the pressure chamber. 4. A nozzle opening to the outside, a pressure chamber for supplying a liquid to the nozzle, a pressure generator for applying a pressure for ejecting a liquid from the nozzle to the pressure chamber, and the pressure. In a liquid droplet ejecting apparatus including a chamber and a vibrating plate arranged between the pressure generating unit, the pressure generating unit includes a piezoelectric material and an electrode positioned opposite to a polarization direction of the piezoelectric material. Applying a voltage to the piezoelectric material to extend the piezoelectric material, wherein the diaphragm has a first portion and a second portion that are displaced in cooperation with each other with a fulcrum portion interposed therebetween. The generating portion is arranged to face the first portion, and at least the second portion is disposed.
Is disposed opposite to the pressure chamber, and by displacing the first portion by the pressure from the pressure generating portion, the first portion on the side opposite to the first portion with the fulcrum portion interposed therebetween is disposed. A droplet ejecting device, wherein the second portion is displaced in a direction in which the pressure chamber is expanded. 5. The pressure generating section is located opposite to a first portion of the diaphragm in an actuator unit that covers the entire pressure chamber, and the diaphragm is the pressure generating section in the first portion. The liquid droplet ejecting apparatus according to claim 3 or 4, wherein the liquid droplet ejecting apparatus is arranged so as to abut against the first unit and form a space between the second portion and the actuator unit. 6. The plurality of nozzles and pressure chambers,
The liquid according to claim 5, wherein the actuator unit and the vibration plate extend over a plurality of pressure chambers, and the pressure generating unit is provided in a plurality in the actuator unit corresponding to the pressure chambers. Drop ejector. 7. The vibrating plate has a protruding portion that abuts the actuator unit between the first portion and the second portion, and the vibrating plate is displaced near the protruding portion as the fulcrum portion. The droplet ejection device according to claim 5 or 6. 8. A portion of the diaphragm, wherein the first portion of the diaphragm is located outside the pressure chamber and abuts an outer wall of the pressure chamber between the first portion and the second portion. 7. The liquid droplet ejecting apparatus according to claim 1, wherein the vibrating plate is displaced with the vicinity being the fulcrum portion.