JPH08230179A - Ink jet recording device - Google Patents

Abstract

PURPOSE: To heighten print quality by stable flying of ink by a device wherein a piezoelectric body is arranged in a plurality of grooves formed in a second non-piezoelectric member, the piezoelectric body is held being pinched by a partition and the bottom face of the grooves without fixing the piezoelectric body at least at an area corresponding to an ink chamber. CONSTITUTION: A piezoelectric body 26 is adhered to a groove bottom face 25a at a back area (s). The piezoelectric body 26 is not fixed with adhesive to a substrate 24 at least at an area (t), corresponding to an ink chamber 23 positioned in the front part of the adhesive section (s) and is held by a partition 22 and the groove bottom face 25a being pinched by them. On the top and bottom face of an acting section (t) of the piezoelectric body 26, a common electrode and an individual electrode 28 are formed respectively. At the adhesive section (s), only the individual electrode 28 is formed, not the common electrode. The acting section (t) of the piezoelectric body 26 which deforms almost uniformly works on the partition 22, and the partition 22 is pushed up sharply, so that the volume of the ink chamber 23 reduces and a pressed ink is discharged and flown from a nozzle hole 30a in liquid drops, and attached on a recording paper.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus having an ink jet head for ejecting ink droplets in accordance with an image signal and recording on a recording medium such as paper.

[0002]

2. Description of the Related Art Conventionally, an ink jet head for applying a voltage to a piezoelectric body according to an image signal, pressurizing the ink based on the deformation of the piezoelectric body to eject an ink droplet from a nozzle, and recording on a recording medium such as paper. Are used in recording devices such as printers.

As an ink jet head of this system,
For example, Japanese Patent Application Laid-Open No. 62-56150 discloses the one shown in FIG. This inkjet head 60
Has a piezoelectric member 62 in which a plurality of recesses 61 are formed and a cover plate 63 that covers the plurality of recesses 61, and an ink chamber 64 is formed inside the recess 61. Also,
A convex portion 65 is formed on the bottom surface of the plurality of concave portions 61,
Electrodes 66 and 67 are provided on the upper surface of the convex portion 65 and on the back surface of the piezoelectric member 62 at positions corresponding to the convex portion 65, respectively. In the inkjet head 60 configured as described above, a voltage is applied between the electrodes 66 and 67,
By deforming the convex portion 65 of the piezoelectric member 62, the volume of the ink chamber 64 is changed, and the ink with which the ink chamber 64 is filled is pressurized, so that an ink droplet is ejected from the nozzle.

[0004]

However, in the ink jet head 60, since the side wall of the concave portion 61 forming the ink chamber 64 is also made of a piezoelectric material, the electrodes 66 and 67 are formed.
The side wall is also deformed when the electric field between them goes around. Even if such a sneak of the electric field can be reduced, since the concave portions and the convex portions are integrally formed, the vibration of the convex portion 65 propagates to the side wall and the convex portion of the adjacent ink chamber. Interlocking displacement occurs. As a result, the adjacent ink chambers that do not want to be ejected are pressurized to eject ink droplets, or even if the ink droplets are not ejected, the flow of ink in the adjacent ink chambers is disturbed, and At that time, there is a problem that the diameter of the ink droplet becomes non-uniform, that is, mutual interference of ink ejection characteristics, which is so-called crosstalk, occurs, and the print quality becomes poor.

Further, since the convex portion 65 which is a piezoelectric material and the ink are in direct contact with each other, the ink penetrates into the convex portion 65 to lower the resistance and the effective voltage is not applied. As a result, the convex portion is not applied. There is a problem that the displacement amount of 65 decreases and the ink flying efficiency deteriorates. Further, since it is necessary to form a groove having a complicated shape on the piezoelectric member 62, there are problems that the manufacturing cost is high and it is difficult to increase the density.

Therefore, the present invention has been made to solve the above-mentioned problems, and realizes high quality printing by stable ink flight without crosstalk, prevention of reduction in ink flight efficiency, and high cost at low cost. It is an object of the present invention to provide an inkjet recording device capable of increasing the density.

[0007]

In order to achieve the above object, the present invention forms a plurality of groove-shaped recesses in a first non-piezoelectric member, covers each recess on the recess forming surface, and forms an ink inside the recess. A partition forming a chamber is provided, a second non-piezoelectric member is fixed to the first non-piezoelectric member via the partition, and a partition forming one wall of each ink chamber on the second non-piezoelectric member. An ink jet head having a plurality of piezoelectric bodies arranged to act on the piezoelectric body, and a voltage is applied to the piezoelectric body according to an image signal so that the piezoelectric body is caused to act to eject ink filled in an ink chamber under pressure. In an inkjet recording apparatus including a voltage applying unit, the piezoelectric body is arranged in a plurality of grooves formed in the second non-piezoelectric member, and the piezoelectric body is fixed at least in a region corresponding to the ink chamber. Without the above partition Serial and shall be held by being sandwiched between the groove bottom surface (claim 1).

Further, it is preferable that the piezoelectric body is a laminated type piezoelectric body (claim 2), and further, the piezoelectric body may be formed in a comb shape having a portion connecting the respective piezoelectric bodies (claim 2). 3).

[0009]

In the ink jet recording apparatus having the above-mentioned structure, when a voltage is applied to the piezoelectric body to form an electric field, the region of the piezoelectric body corresponding to the ink chamber is deformed and acts on the partition wall. The volume of the ink chamber is reduced by being pushed up, and the ink filled in the ink chamber is pressurized and ejected. On the other hand, when the voltage application to the piezoelectric body is released and the electric field is extinguished, the region of the piezoelectric body corresponding to the ink chamber returns to the original state. At this time, the partition wall follows and returns to the original state while being in contact with the returning piezoelectric body. This allows
The volume of the ink chamber increases, a negative pressure is generated inside, ink is replenished, and the next ink ejection is ready.

In this case, the region of the piezoelectric body corresponding to the ink chamber is not fixed to the second non-piezoelectric member, but the partition wall and the second non-piezoelectric member.
Since it is only sandwiched between the non-piezoelectric member and the bottom surface of the groove of the non-piezoelectric member, the vibration of the one piezoelectric member can propagate to the other piezoelectric member through the second non-piezoelectric member and be displaced in conjunction therewith. Without
Crosstalk does not occur. Further, since the partition wall is provided between the ink chamber and the piezoelectric body, the ink does not directly contact and permeate the piezoelectric body.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 schematically shows the overall configuration of an inkjet recording apparatus 1 which is a first embodiment of the present invention. The ink jet recording apparatus 1 is roughly classified into a power supply unit 2 having a connector 2a, a drive system 3, a mechanical controller 4, a memory 5, a controller 6, an ink supply unit 7, a scan carriage 8, and a paper feed unit. It is composed of a section 9, a case 10, and an operation panel 11. The scan carriage 8 is capable of scanning in a direction orthogonal to the paper passing direction (direction of arrow a) (front and back direction of the paper surface in FIG. 1), and inside the carriage 4 is provided for each color of black, cyan, magenta and yellow. The two inkjet heads 12 are arranged along the paper passing direction, and the ink discharge nozzles are directed downward.

As shown in FIG. 2, the ink jet head 12 has a top plate 20 which is a first non-piezoelectric member. The top plate 20 is composed of a plate made of a non-piezoelectric material such as alumina, and as shown in FIG. 3, a plurality of groove-shaped recesses 21 are formed on the lower surface by dicing or the like. These recesses 21 are formed at a predetermined pitch in the width direction of the top plate 20, and extend parallel to the longitudinal direction of the top plate 20, respectively. On the surface of the top plate 20 where the recess 21 is formed,
A partition wall 22 made of, for example, an aramid resin is provided, and is bonded at the contact surface with the top plate 20. An ink chamber 23 is formed inside each recess 21 covered with the partition wall 22.

A substrate 24, which is a second non-piezoelectric member, is provided on the surface of the top plate 20 where the recess 21 is formed, with a partition wall 22 interposed therebetween. The substrate 24 is composed of a plate made of a non-piezoelectric material, like the top plate 20. On the contact surface of the substrate 24 with the partition wall 22, a plurality of groove portions 25 having the same width as the concave portion 21 of the top plate 20 and having an equal pitch are formed by dicing or the like, and the groove portions 25 sandwich the partition wall 22 and the top plate is sandwiched. A substrate 24 is fixed to the top plate 20 so as to face each of the recesses 21 of the 20. As this fixing method, the contact surface with the partition wall 22 is adhered, the top plate 20 and the substrate 24 are clamped from above and below by using a fastener such as a bolt, or
For example, there is a resin molding around these parts.

A plurality of piezoelectric bodies 26 are arranged in the groove portion 25 of the substrate 24. The piezoelectric body 26 is, for example, PZ.
The ink chamber 23 is formed by cutting a plate made of T piezoelectric ceramic with a dicing saw and has a rectangular cross section.
It has a slender columnar body along the direction. Further, the piezoelectric body 26 is sandwiched and held between the partition wall 22 and the bottom surface 25a of the groove portion 25, and the upper portion thereof comes into contact with the partition wall 22 forming one wall of the ink chamber 23 to act.

The contact surface between the partition wall 22 and the piezoelectric body 26 may or may not be bonded, but if bonded, the partition wall 22 can reliably follow the vibration of the piezoelectric body 26 and the high frequency response is improved. There is. On the other hand, the contact surface between the piezoelectric body 26 and the bottom surface 25a of the groove 25 of the substrate 24 is not bonded at least in the region corresponding to the ink chamber 23, as described later. Further, in this embodiment, the height of the piezoelectric body 26 and the depth of the groove portion 25 of the substrate 24 are formed to be equal to each other, and the partition wall 22 is in contact with the piezoelectric body 26 while keeping the planar state.
As shown in FIG. 5, the piezoelectric body 26 is formed to have a slightly higher height, and the upper portion of the piezoelectric body 26 is shallowly fitted along the concave portion 21 of the top plate 20, and the partition wall 22 is pushed into the ink chamber 23. By doing so, the high frequency response is improved as in the case of the above-mentioned adhesion. Further, the distance between the piezoelectric body 26 and the side wall of the groove 25 is preferably 50 μm or less, and particularly preferably 20 μm or less. This is to prevent the partition wall 22 from being pushed by the pressure of the ink generated by the deformation of the piezoelectric body 26 to enter the groove portion 25 and cause a loss in the pressure for ejecting the ink.

As shown in FIG. 3, the partition wall 22 of the piezoelectric body 26 is formed.
A common electrode 27 is formed on the contact surface with. However, as will be described later, the common electrode 27 is not formed in the rear region of the piezoelectric body 26 corresponding to the bonded portion to the substrate 24. On the other hand, an individual electrode 28 is formed over the entire lower surface of the piezoelectric body 26 that is in contact with the bottom surface 25a of the groove 25 of the substrate 24. These electrodes 27 and 28 are formed by electroless plating.
It is formed of a u / Ni film or a sputtered film of Au / (Ni, Cr) and has a thickness of about 0.1 to 10 μm.
The piezoelectric body 26 is polarized in the direction from the individual electrode 28 to the common electrode 27 (direction of arrow P). In order to prevent a decrease in the amount of deformation when a voltage is applied to the surface of the piezoelectric body 26 due to the penetration of moisture in the atmosphere, for example, a polyimide resin is applied by spin coating, and the temperature is set to 180 ° C. for 1 hour. It is preferable to perform baking and overcoating, but a piezoelectric material having high humidity resistance is used as the piezoelectric body 26.
This process may be omitted when used for.

As shown in FIG. 5, the front end surface of the joined body of the top plate 20, the partition wall 22 and the substrate 24 has, for example, a thickness of 2 mm.
A nozzle plate 30 made of a polyimide film having a thickness of about 5 to 200 μm is adhered and fixed. A plurality of nozzle holes 30a are formed in the nozzle plate 30 by, for example, an excimer laser at the same pitch as the ink chamber 23, and the pitch is, for example, about 42.3 to 254 μm (pixel density: 600 to 100 dpi). .

Each ink chamber 2 is formed on the rear end surface of the top plate 20.
An orifice plate 31 having an ink supply port 31a corresponding to No. 3 is bonded. An ink distribution path is formed by adhering a U-shaped back plate 32 when viewed from above in FIG. 5 to the orifice plate 31, communicating with all the ink supply ports 31a between the orifice plate 31 and the upper side. 33 is formed. An ink manifold 34 that covers the ink distribution path 33 is fixed to the upper rear part of the top plate 20, and an ink tube 34a is projected from the upper part thereof.

As shown in FIG. 5, the piezoelectric body 26 is adhered to the bottom surface 25a of the groove 25 in the rear region (hereinafter referred to as "adhesive portion") s. The piezoelectric body 26 is not adhered and fixed to the substrate 24 at least in a region (hereinafter, referred to as “action portion”) t that is located in front of the adhesion portion s and corresponds to the ink chamber 23, and the partition wall 22 is formed.
And the bottom surface 25a of the groove 25. Further, although the common electrode 27 and the individual electrode 28 are formed on the upper and lower surfaces of the acting portion t of the piezoelectric body 26, only the individual electrode 28 is formed and the common electrode 27 is formed on the adhesive portion s. Absent.

The piezoelectric body 26 projects rearward from the back plate 32, and the individual electrode 28 on the lower surface of the projecting portion is supported by the lead wiring support member 35 and wire-bonded to the lead wiring 36 corresponding to each piezoelectric body 26. Are connected in each way. The lead-out wiring 36 is connected to a controller 6 (see FIG. 1) which is a voltage applying means via a driving IC (not shown), and the controller 6 applies a voltage to the piezoelectric body 26 according to an image signal.
On the other hand, the common electrode 27 on the upper surface of the piezoelectric body 26 is grounded. Although not shown in the figure, the connection to the ground is made by, for example, forming the partition wall 22 with conductive resin or metal, or by bonding the partition wall 22 and each piezoelectric body 26 with a conductive adhesive. An adhesive layer is formed so as to be electrically connected to the common electrode 27 of
Use a method such as grounding only at points.

Next, the ink discharge operation of the ink jet head 12 having the above-mentioned structure will be described. As shown in FIG. 5, the ink is supplied from the ink supply unit 7 (see FIG. 1) to the ink tube 34a, and the ink distribution path 33 is formed.
Each ink chamber 23 is filled via When a positive pulsed voltage as shown in FIG. 6A is applied to the individual electrode 27 of the piezoelectric body 26, as shown in FIG. An electric field is formed in the direction toward the arrow (direction of arrow E), that is, in parallel with the polarization direction (direction of arrow P), and the piezoelectric body 26 is deformed and vibrates in a so-called thickness direction vibration mode. At this time, when the entire surface of the piezoelectric body 26 including the acting portion t is adhesively fixed to the bottom surface 25a of the groove portion 25, as shown by the dotted line in FIG.
The upper surface of the piezoelectric body 26 deforms like a wavy mixture of an expanded portion and a contracted portion, and the piezoelectric body 26 as a whole largely loses the amount of deformation necessary for ink flight. There is a problem in that cross-talk occurs due to interlocking displacement occurring in another piezoelectric body 26 that is propagated through the other piezoelectric body 26 adjacent thereto.

When a part of the acting portion t is the adhesive portion s and the front end portion is not adhered, the adhesive layer and the piezoelectric body 2
6 forms a bimorph structure, the front end portion is flexed and deformed as shown by a dotted line in FIG. 9. However, since this deformation is not uniform, twisting may occur. There is a problem that the amount of pushing up the ink fluctuates, and the diameter of the flying ink droplet becomes non-uniform.

On the other hand, when the voltage is applied without adhering the piezoelectric body 26 at all, as shown by the dotted line in FIG.
In addition to expanding and deforming by Δy uniformly in the y direction, the x direction and the depth direction (direction perpendicular to the paper surface in FIG. 10)
Shrinks and deforms slightly. In this embodiment, since the common electrode 27 is not formed on the adhesive portion s of the piezoelectric body 26, no electric field is formed inside, and no deformation occurs in this portion. On the other hand, since the acting portion t of the piezoelectric body 26 is not adhesively fixed to the substrate 24, the deformation in the vicinity of the adhesive portion s can be suppressed, but almost all regions except this region are expanded and deformed by Δy uniformly in the y direction.

In this way, the piezoelectric body 2 that deforms substantially uniformly
As a result of the action part t of 6 acting on the partition wall 22,
As shown by the middle dotted line, the partition wall 22 is steeply pushed up and the volume of the ink chamber 23 is reduced, whereby the pressurized ink is ejected and ejected as droplets from the nozzle holes 30a, and recording (not shown) is performed. Adheres on paper.

When the voltage applied to the individual electrode 27 becomes zero, the piezoelectric body 26 returns to its original state. At this time, the partition wall 2
On the basis of its elasticity, 2 follows and follows the piezoelectric body 26 performing the restoring operation. As a result, the volume of the ink chamber 23 increases, ink is supplied to the ink chamber 23 via the manifold 34, the ink distribution passage 33, and the ink supply port 31a, and the next ink ejection is ready.

However, at the time of ink replenishment, as shown in FIG.
When the voltage is instantly set to zero and the piezoelectric body 26 is restored based on the elasticity of the piezoelectric body 26 and the volume of the ink chamber 23 is sharply increased as shown in Fig. 3, bubbles are sucked into the ink chamber 23 from the nozzle hole 30a and the next pulse is generated. When a voltage is applied, the bubbles may absorb the pressure and hinder the flight of the ink. Therefore, in FIG.
As shown in (b), the piezoelectric body 26 is provided with an inclination in the pulse shape of the voltage during the restoring operation, and the piezoelectric body 26 and the partition wall 2 are
This is prevented by allowing 2 to return the fastest in the range where suction of bubbles does not occur.

Further, by applying a pulse voltage having the same voltage but a different pulse width to that of FIG. 6A to adjust the deformation amount of the piezoelectric body 26, the flying ink droplet diameter can be changed.
As a result, the diameter of the dots adhering to the recording paper can be changed, and halftone reproduction is possible. For example, as shown in FIG. 6C, the dot diameter becomes smaller as the pulse width becomes smaller. The pulse voltage shown in FIG. 6 (d) is obtained by applying a rear pulse of a small voltage with a reverse polarity to the main pulse. When the pulse voltage having this waveform is applied to the piezoelectric body 26, the ink column extending from the nozzle hole 30a after the ink droplet is ejected by the main pulse is drawn into the ink chamber 23 by the sub pulse, so that the satellite noise can be reduced. The pulse voltage shown in FIG. 6 (e) applies a small-voltage front pulse having the same polarity as the main pulse, and the pulse voltage of this waveform can suppress the voltage value of the main pulse to a low level. As a result, the driver's burden is reduced and the driver cost can be reduced.

The above-described ink ejection operation is independently performed for each ink chamber 23 in accordance with the image signal, so that an image for one line is drawn, and this is repeated in synchronization with the movement of the recording paper. As a result, an image corresponding to the image signal is drawn on the recording paper.

As described above, in the ink jet head 12 of this embodiment, the partition wall 22 and the bottom surface 25a of the groove 25 formed in the substrate 24 are not bonded and fixed to the substrate 24 at all by the action portion t of the piezoelectric body 26. Since it is only sandwiched and held by the substrate 24, the vibration of the action part t when a voltage is applied is generated by the substrate 24.
Therefore, the interlocking displacement can be completely suppressed without propagating to the adjacent piezoelectric body 26 via the. For this reason, there is no unnecessary ink ejection due to crosstalk or disturbance of the ink flow in the ink chamber 32, and ink ejection can be performed very stably, and as a result, there is no variation between dots of ink droplets. The dot diameter is stable, and the printing quality can be significantly improved.

Further, unlike the case where the operating portion t of the piezoelectric body 26 is partially adhered to the substrate 24, there is no variation in the pushing amount of the partition wall 22, and the partition wall 22 is made uniform over almost the entire operating portion t. Since it is pushed up, the stability of ink flight is improved.

Furthermore, since there is no adhesive portion in the acting portion t of the piezoelectric body 26, the whole or a part of the acting portion t is covered by the substrate 2.
Unlike the case of bonding to No. 4, the bonding is not deteriorated due to the vibration of the acting portion t, and the piezoelectric body 26 is not separated from the substrate 24 to change the fixed state. Therefore, the life of the inkjet head can be extended, and the stable deformed state of the piezoelectric body 26 can be obtained for a long time, so that the reliability of ink flight is improved.

In addition, since the piezoelectric body 26 is separated from the ink chamber 23 by the partition wall 22 and does not come into direct contact with the ink,
The ink does not penetrate into the piezoelectric body 26 to reduce the resistance. Therefore, it is possible to prevent the amount of deformation of the piezoelectric body 26 from decreasing with the decrease in the effective voltage and the ink flying efficiency from decreasing, and as a result, the stability and reliability of the inkjet head 12 improve.

Further, according to the structure of the present embodiment, since the processing is relatively simple, it is possible to inexpensively achieve high density and multiple nozzles, and it is possible to increase the printing speed.

In this embodiment, FIGS. 6 (a) to 6 (e) are used.
Is applied to expand and deform the action portion t of the piezoelectric body 26, and the deformation causes the partition wall 22 to be pushed up to eject ink, so that the ink is replenished when the partition wall 22 is restored together with the piezoelectric body 26. However, on the contrary, the action portion t and the partition wall 22 are adhered to each other to form the piezoelectric body 26 on the piezoelectric body 26 as shown in FIG.
0 (f) or (g) is applied, and the acting portion t
After the ink is replenished by contracting and deforming the ink, the ink may be ejected when the partition 22 is restored together with the piezoelectric body 26. Here, the reason why the rising portion of the pulse in FIG. 10 (g) is inclined is the same as in the case of FIG. 10 (b).

The common electrode 2 is attached to the bonding portion s of the piezoelectric body 26.
Although no deformation is caused in this portion by not forming No. 7, no deformation may be caused in this portion even if an electric field is formed by not performing polarization treatment, or the adhesive portion is not formed. Even if the deformation occurs in s, the deformation is absorbed by using the adhesive having flexibility even after drying, so that the working portion t is not deformed flexurally and the ink flying is not affected. Good.

In the first embodiment, the single layer piezoelectric body 2 is used.
11, a laminated piezoelectric body in which piezoelectric materials are laminated in two or more layers by a known green sheet method, and individual electrodes and common electrodes also serving as adhesive layers are formed inside, as shown in FIG. If 37 is used, a large effective displacement can be obtained according to the number of stacked layers, so that the driving voltage can be lowered and the driver cost can be reduced.

Further, in the first embodiment, the piezoelectric material 26 having a flat plate shape is completely divided into the elongated columnar bodies by the dicing process, but as shown in FIG. 12, a so-called comb tooth shape is formed. The formed piezoelectric member 38 may be used. The piezoelectric member 38 includes an adhesive portion s and an acting portion t.
In, each piezoelectric body 39 is divided into elongated columnar bodies, but in the rear region (left side in FIG. 12) of the bonding portion s,
Each piezoelectric body 39 is connected by a connecting portion 42 having a surface 41 that is one step lower than the surface on which the individual electrode 40 is formed. The connecting portion 42 is formed by cutting the plate-shaped piezoelectric material into slits by dicing to reduce the cutting depth after the bonding portion s.

With this structure, each piezoelectric body 39
The structural strength of the inkjet head,
The reliability is improved, the processing / assembly surface is easily handled, and the assembly variation is reduced, so that the manufacturing cost can be reduced.

Next, the ink jet head in the ink jet recording apparatus of the second embodiment will be described with reference to FIGS.
However, the same members as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. Similarly to the first embodiment, a plurality of groove portions 45 are formed on the substrate 44 of the ink jet head of this embodiment so as to correspond to the recesses 21 formed on the top plate 20, but as shown in FIG. In addition, these groove portions 45 are closed grooves whose rear end portion (left side in FIG. 13) is closed.

The piezoelectric bodies 46 are elongated columnar bodies having a rectangular cross section, and are arranged in the groove portions 45, respectively, as in the first embodiment. However, in the present embodiment, the polarization process is performed in the direction from the rear end to the front end of the piezoelectric body 46 (direction of arrow P), and the individual electrode 48 is placed on the common electrode 47.
Is placed in the groove portion 45 with its bottom facing down, and its rear end portion 46a is brought into contact with the rear wall of the groove portion 45 without any gap and is fixed to the substrate 44 by the adhesive portion s. The individual electrode 48 is connected to the lead wire 49 by a method such as wire bonding, and is connected to the controller 6 (see FIG. 1) via the driving IC 50. On the other hand, the common electrode 47 is formed over the entire length of the piezoelectric body 46, and is grounded via a conductive adhesive layer (not shown) that conducts to the common electrode 47 of each piezoelectric body 46.

The individual electrode 48 of the piezoelectric body 46 is shown in FIG.
When a positive pulsed voltage as shown in (a) is applied, an electric field is formed inside the piezoelectric body 46 in a direction orthogonal to the polarization direction (direction of arrow E), and the piezoelectric body 46 operates in a so-called thickness-shear vibration mode. Slip deformation and vibration occur along the electrode formation surface. When the piezoelectric body 46 can be freely deformed, when the voltage is applied, as shown by the dotted line in FIG.
The side shape of the rectangle of is slip-deformed into a parallelogram.
However, in this embodiment, since the piezoelectric body 46 is fixed by the adhesive portion s and the rear end portion 46 is in contact with the piezoelectric body 46, free deformation is restricted, and as shown by the dotted line in FIG. In the action part t, the surface on which the individual electrode 48 is formed is curved and swells, and the surface on which the common electrode 47 is formed in the vicinity of the front end is also curved and lifted from the substrate 44, and the side surface shape of the piezoelectric body 46 as a whole is deformed into a substantially barrel shape. .

When the acting portion t of the piezoelectric body 46 that deforms as described above acts on the partition wall 22, the partition wall 22 is pushed up and the volume of the ink chamber 23 decreases as shown by the dotted line in FIG. The ink pressurized by the droplets flies in the form of droplets from the nozzle holes 30a. When the voltage application is released, the piezoelectric body 46 returns to the original state, and the ink is supplied to the ink chamber 23.

As described above, in the ink jet head of this embodiment, since the thickness shear vibration mode is used for the deformation and vibration of the piezoelectric body 46, the thickness direction vibration mode is used as in the first embodiment. Since shear shear stress is applied and the stress becomes stronger, the force generated at the time of deformation becomes large, and it becomes possible to drive at a low voltage. Therefore,
According to the present embodiment, in addition to the same effects as those of the first embodiment, the driver cost can be reduced and the ink can be ejected efficiently.

Next, materials and the like that can be used for the ink jet head of the above embodiment will be described. Material of Piezoelectric Material As the material of the piezoelectric materials 26, 37, 38, 46, the following piezoelectric materials can be used. (1) Piezoelectric crystal Quartz (SiO ₂ ), Rochelle salt (RS: NaKC ₄ H
₄ O ₆・ 4H ₂ O) Ethylenediamine tartrate (ETD: C ₆ H ₁₄ N ₂ O ₆ )
, Potassium tartrate (DKT: K ₂ C ₄ H ₄ O ₆ 1 / 2H
₂ O), diammonium phosphate (ADP: NH ₄ H ₂
PO ₄ ), perovskite crystals (ex. CaTi
O ₃ , BaTiO ₃ , PLZT), tungsten bronze-based crystal (ex. Na _x WO ₃ [0.1 <x <0.2
8]), sodium barium niobate (Ba ₂ NaN
b ₅ O ₁₅ ), potassium lead niobate (Pb ₂ KNb
₅ O ₁₅ ), lithium niobate (LiNbO ₃ ), lithium tantalate (LiTaO ₃ ), sodium chlorate (NaClO ₃ ), tourmaline (Tourmalin)
e), zinc blende (ZuS), lithium sulfate (LiS)
O ₄ H ₂ O), lithium metagallate (LiGa
O ₂ ), lithium iodate (LiIO ₃ ), glycine sulfate (TGS), bismuth germanate (Bi ₁₂ G)
eO ₂₀ ), lithium germanate (LiGeO ₃ )
, Barium titanate, germanium (Ba ₂ G
Crystals such as e ₂ TiO ₃ ).

(2) Piezoelectric semiconductor Wurtzite, BeO, ZnO, CdS, CdSe
, AlN. (3) Piezoelectric ceramics Barium titanate (BaTiO ₃ ), lead zirconate titanate (PbTiO ₃ · PbZrO ₃ ),
Titanium lead (PbTiO _3), niobate barium lead _{((Ba-Pb) Nb 2} O 6). (4) The above (1) piezoelectric crystal, (2) piezoelectric semiconductor,
(3) The powder of the piezoelectric ceramic material may be dispersed and molded in plastics. (5) piezoelectric polymer polyvinylidene fluoride _{PVDF (-CH 2 -CF 2 -)} n
, Polyvinylidene fluoride / PZT, rubber / PZT
, Copolymer of trifluoroethylene and vinylidene fluoride, copolymer of vinylidene cyanide and vinyl acetate,
Polyvinylidene, etc. The above-mentioned piezoelectric materials may be polarized and then processed as a piezoelectric body, or may be processed as a piezoelectric body and then polarized.

The overcoat process overcoat processing the piezoelectric 26,37,38,46 of the piezoelectric body can also be carried out by a method mentioned in the following (1) to (5). (1) Application of plastics Saturated polyester resin, polyamide resin, polyimide resin, acrylic resin, aramid resin, ethylene-vinyl acetate resin, ion-crosslinked olefin copolymer (ionomer), styrene-butadiene block copolymer, polyacetal, Thermoplastic resins such as polycarbonate, vinyl chloride-vinyl acetate copolymer, cellulose ester, polyimide and styrene resin.

Thermosetting resins such as epoxy resin, phenoxy resin, urethane resin, nylons, silicone resin, fluorosilicone resin, phenol resin, melamine resin, xylene resin, alkyd resin and thermosetting acrylic resin. Polyvinyl carpazole,
Photoconductive resins such as polyvinyl pyrene, polyvinyl anthracene, and polyvinylol.

These can be used alone or in combination. In addition, engineering plastics such as liquid crystal polymer, a mixture of plastics and powder, and whiskers may be used. Photosensitive resin, thick film photoresist resin, etc. can be used. Bakelite, fluorocarbon resin, glass / epoxy resin (glass filler mixed in epoxy) may be used. These are coating, dipping,
A known liquid application method such as a spray method may be used. Among the above, in particular, polyimide resin, aramid resin, epoxy resin, phenoxy resin, fluorosilicone resin,
The effect of fluororesin and glass / epoxy resin is excellent.

(2) Vapor Deposition of Oxidizing / Nitriding / Sulfide Metal Compounds Metal oxide compounds (SiO ₂ , SiO, CrO, Al ₂ O ₃
Etc.), metal nitride compounds (Si ₃ N ₄ , AlN, etc.), metal sulfide compounds (ZnS, etc.), or alloys thereof,
It is coated by vacuum deposition or sputtering. In addition, the above (1)
The above plastic may be applied by vapor deposition or parylene resin vapor deposition. Among the above, Al ₂ O ₃ , S
The effect of i ₃ N ₄ is excellent.

(3) Application of hydrocarbon compounds Hydrocarbons, oxygen-containing hydrocarbons, sulfur-containing hydrocarbons and other group IV element-containing hydrocarbons, nitrogen-containing hydrocarbons, silicon-containing hydrocarbons, fluorine-containing hydrocarbons, etc. Halogen-containing hydrocarbons, Group III element-containing hydrocarbons
-Apply by CVD (plasma CVD) and perform overcoat treatment. Alternatively, under these mixed gas phases, P-C
It may be applied by VD. Among the above, the effect of the fluorine-containing hydrocarbon is excellent. Note that these films need to be appropriately provided with an undercoat of a-Si (amorphous silicon), a-SiC, a-SiN, or the like according to the compatibility of the adhesiveness with the piezoelectric body. (4) Instead of coating the surface of the piezoelectric plate in the coating liquid state with the plastics of (1) above, the piezoelectric body forming portion is replaced and impregnated under reduced pressure for molding. (5) The surface of the piezoelectric plate is surface-treated with an ink repellent solvent.

When the overcoat films formed by the above methods (1) to (5) are compared, the following characteristics are observed (however, (3) has an undercoat). Strength: Strong (2), (3)> (1), (4)> (5) Weak smoothness: Good (1), (4)> (2), (3), (5) Poor adhesion ( Vibration resistance included: Strong (1), (4)> (2), (3)> (5) Weak durability (including ink resistance): Good (1), (4)> (2) , (3)> (5) Bad Others, the processing of (5) is simple and can be used as the post-processing of (1) to (4). In terms of cost, (1) and (4) are particularly inexpensive. The methods (1) to (5) described above may be appropriately combined and used depending on the piezoelectric body and the ink type.

Materials for Top Plate and Substrate Materials that can be used for the non-piezoelectric material forming the top plate 20 and the substrates 24 and 44 include the following (1) to (4). (1) Ceramics Al ₂ O ₃ , SiC, C, BaTiO ₃ , BiO ₃
.3SnO ₂ , Pb (Zr _x , Ti _1-x ) O ₃ , ZnO
, SiO ₂ , (1-x) Pb (Zr _x , Ti _1-x ) O ₃
+ (X) La ₂ O ₃ , Zn _1-x Mn _x Fe ₂ O ₃ , γ-F
e ₂ O ₃ , Sr · 6Fe ₂ O ₃ , La _1-x Ca _x CrO ₃
, SnO ₂ , transition metal oxides, ZnO-Bi ₂ O ₃
, Semiconductor BaTiO ₃ , β-Al ₂ O ₃ , stabilized zirconia, LaB ₆ , B ₄ C, diamond, Ti
N, TiC, Si ₃ N ₄ , Y ₂ O ₂ S: Eu, PL
_{ZT, ThO 2, -CaO · nSiO} 2, Ca
₅ (F, Cl) P ₃ O ₁₂ , TiO ₂ , K ₂ O.nAl ₂
O ₃ .

(2) Glasses Elemental glass = Si, Se, Te, As Hydrogen-bonded glass = HPO ₃ , H ₃ PO ₄ , SiO ₂ ,
_{B 2 O 2, P 2 O} 5, GeO 2, As 2 O 3 oxide glass _{= SbO 3, Bi 2 O 3} , P 2 O 3, V
₂ O ₅ , Sb ₂ O ₅ , As ₂ O ₃ , So ₃ , ZrO ₂ Fluoride glass = BeF ₂ , Chloride glass = ZnCl ₂ Sulfide glass = GeS ₂ , As ₂ S ₃ Carbonate glass = K ₂ CO ₃ , MgCO ₃ nitrate glass = NaNO ₃ , KNO ₃ , AgNO ₃ sulfate glass = Na ₂ S ₂ O ₃ , H ₂ O, Tl ₂ SO
_4, alum silicate glass = SiO ₂ silicate alkali glass _{= Na 2 O-CaO-SiO} 2 potash lime glass _{= K 2 O-CaO-SiO} 2 soda _{= Na 2 O-CaO-SiO} 2 lead glass, barium glass Borosilicate glass.

(3) Plastics Saturated polyester resin, polyamide resin, polyimide resin, aramid resin, acrylic resin, ethylene-vinyl acetate resin, ion-crosslinked olefin copolymer (ionomer), styrene-butadiene block copolymer, polyacetal , Polycarbonate, vinyl chloride-vinyl acetate copolymer, cellulose ester, polyimide, styrene resin and other thermoplastic resins.
Epoxy resin, urethane resin, nylon resin, silicone resin, phenol resin, melamine resin,
Thermosetting resins such as xylene resin, alkyd resin, and thermosetting acrylic resin. Photoconductive resins such as polyvinyl carpazole, polyvinyl pyrene, polyvinyl anthracene, and polyvinylol.

The above items (1) to (3) can be used alone or in combination. In addition, engineering plastics such as liquid crystal polymer, a mixture of plastics and powder, and whiskers may be used. A photosensitive resin, a thick film photoresist resin, or the like can also be used, and bakelite, a fluororesin, or a glass / epoxy resin (a glass filler mixed in epoxy) may be used.

(4) Others When the side surface in contact with the ink chamber is coated with an insulating film, all metals can be used. These non-piezoelectric materials are formed into a plate shape and then processed into the top plate 20, or molded,
The top plate 20 may be molded from the beginning using pattern etching, photo-curing, or the like.

Materials of Partition Wall As the material of the partition wall 22, the following materials can be used. (1) Thermosetting resins such as epoxy resin, phenoxy resin, urethane resin, nylons, silicone resin, fluorosilicone resin, phenol resin, melamine resin, xylene resin, alkyd resin, and thermosetting acrylic resin. Among the above, epoxy resin, phenoxy resin and fluorosilicone resin are preferably used.

(2) Polyester resin, polyamide resin, acrylic resin, aramid resin, ethylene-
Thermoplastics of vinyl acetate resin, ion-crosslinked olefin copolymer (ionomer), styrene-butadiene block copolymer, polyacetal, polyphenylene sulfide, polycarbonate, vinyl chloride-vinyl acetate copolymer, cellulose ester, polyimide, styrene resin, etc. resin. Among the above, aramid resin, polyimide resin, polyamide resin, and ethylene-vinyl acetate resin are preferably used.

(3) Liquid Crystal Polymer (4) Photosensitive Resin, Thick Film Photoresist Resin (5) Rubber, Synthetic Rubber (6) Thin Plate of Nickel, Stainless Steel, Titanium, Tungsten, etc. In addition, the above (1) to (5) The materials listed in () may be used alone or in combination.

Comparing the superiority and inferiority of the materials mentioned in (1) to (6) above, although it is almost the same in (1) to (3), excellent (1) to (3)>(4)>(6)> (5) Inferiority can be seen. Furthermore, the material thickness is 100μ
It is preferably m or less, and preferably 50 μm or less.

Adhesive Material As the adhesive used for assembling the ink jet head, the following adhesives (1) to (4) can be used. However, when the adhesive layer is used as a conductor when the common electrode is grounded, it naturally needs to have conductivity. (1) Thermosetting resin adhesives such as epoxy resin, phenol resin, phenoxy resin, acrylic resin, furan resin, polyurethane resin, polyimide resin, silicone resin. (2) Thermoplastic resin adhesives such as polyvinyl acetate, polyvinyl chloride, vinyl acetal, polyvinyl alcohol, and polyvinyl butyral. (3) UV curable resin adhesive. (4) Anaerobic curable adhesive.

[0062]

As is apparent from the above description, in the ink jet head of the ink jet recording apparatus of the present invention, at least in the region corresponding to the ink chamber, the piezoelectric member is not fixed to the second non-piezoelectric member and the partition wall and the second non-piezoelectric member are fixed. Since it is only sandwiched and held between the two non-piezoelectric members, even if the area of the piezoelectric body corresponding to the ink chamber vibrates, the vibration is transmitted to the adjacent piezoelectric body via the second non-piezoelectric member. It is possible to completely suppress the interlocking displacement without propagating. For this reason, there is no unnecessary ink ejection due to crosstalk or disturbance of the ink flow in the ink chamber, and it is possible to perform ink ejection very stably. As a result, there is no variation between dots of ink droplets and the dot diameter Is stable and the print quality can be improved.

Further, as in the case where the second non-piezoelectric member is partially bonded in the region of the piezoelectric body corresponding to the ink chamber,
The deflection deformation of the piezoelectric body is not twisted to cause variations in the pushing-up amount of the partition wall 22, and the partition wall is uniformly pushed up in almost the entire area of the piezoelectric body corresponding to the ink chamber, so that the stability of ink flight is improved. To do.

Further, since the piezoelectric body is separated from the ink chamber by the partition wall and does not come into direct contact with the ink, the ink does not permeate to lower the resistance. Therefore, it is possible to prevent the amount of deformation of the piezoelectric body from decreasing with a decrease in the effective voltage and the ink flying efficiency from decreasing, and as a result, the stability and reliability of the device are improved. In addition, according to the configuration of the present invention, since the processing of the inkjet head is relatively simple, it is possible to inexpensively increase the density and increase the number of nozzles, and it is possible to increase the printing speed.

According to the ink jet recording apparatus in which the piezoelectric body is a laminated piezoelectric body, a large effective displacement can be obtained according to the number of laminated layers, so that low voltage driving is possible and the driver cost can be reduced. Further, according to the inkjet recording device in which the piezoelectric body is formed in a so-called comb shape, the structural strength of each piezoelectric body is increased, the durability and reliability of the inkjet head are improved, and the handling of the processing / assembly surface is easy. As a result, variations in assembly are reduced, so that the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an inkjet recording apparatus that is a first embodiment of the present invention.

FIG. 2 is an overall perspective view of the ink jet head in the first embodiment.

FIG. 3 is a cross-sectional view in the width direction of the inkjet head according to the first embodiment.

FIG. 4 is a diagram showing a modified example of the inkjet head of FIG.

FIG. 5 is a longitudinal cross-sectional view of the inkjet head according to the first embodiment.

FIG. 6 is a diagram showing a pulse shape of a voltage applied to the piezoelectric body of the first embodiment.

FIG. 7 is a diagram showing a polarization direction and an electric field forming direction of the piezoelectric body of the first embodiment.

FIG. 8 is a diagram showing a deformed state when a piezoelectric body is entirely bonded.

FIG. 9 is a diagram showing a deformed state when a piezoelectric body is partially bonded.

FIG. 10 is a diagram showing a deformed state when the piezoelectric body is not bonded.

FIG. 11 is a side view of a laminated piezoelectric material applicable to the first embodiment.

FIG. 12 is a plan view and a side view of a comb-tooth-shaped piezoelectric member applicable to the first embodiment.

FIG. 13 is a longitudinal sectional view of an inkjet head in an inkjet recording apparatus according to a second embodiment of the present invention.

FIG. 14 is a diagram showing a deformed state of a non-bonding piezoelectric body in a thickness shear vibration mode.

FIG. 15 is a diagram showing a deformed state of the piezoelectric body of the second embodiment.

FIG. 16 is a partial cross-sectional view showing an example of a conventional inkjet head.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Inkjet recording device, 6 ... Controller (voltage application means), 12 ... Inkjet head, 20 ... Top plate (first non-piezoelectric member), 21 ... Recessed portion, 22 ... Partition wall, 23
... Ink chamber, 24 ... Substrate (second non-piezoelectric member), 25 ...
Groove portion, 26 ... Piezoelectric body, 27 ... Common electrode, 28 ... Individual electrode

Claims (3)

[Claims] 1. A first non-piezoelectric member, wherein a plurality of groove-shaped recesses are formed in the first non-piezoelectric member, and a partition wall is formed on the recess forming surface so as to form an ink chamber inside the recess. An inkjet head having a second non-piezoelectric member fixed thereto via the partition wall, and a plurality of piezoelectric bodies acting on the partition wall forming one wall of each ink chamber being disposed on the second non-piezoelectric member. An ink jet recording apparatus comprising: a voltage applying unit that applies a voltage to the piezoelectric body in response to an image signal so that the piezoelectric body is actuated to eject the ink filled in the ink chamber under pressure. The body is arranged in a plurality of grooves formed in the second non-piezoelectric member, and the piezoelectric body is sandwiched and held between the partition wall and the bottom surface of the groove portion without fixing the piezoelectric body in at least a region corresponding to the ink chamber. Characterized by An ink jet recording apparatus. 2. The ink jet recording apparatus according to claim 1, wherein the piezoelectric body is a laminated piezoelectric body. 3. The ink jet recording apparatus according to claim 1, wherein each of the piezoelectric bodies is formed in a comb-tooth shape having a connected portion.