JPH0580270B2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to piezoelectric fluid ejection nozzles.

(Prior art) Piezoelectric bimorph plates are bonded together so that electric fields are applied in opposite directions relative to the polarization direction. When an electric field is applied, one plate stretches.
Since the other side contracts, it can be easily deformed into a curved state. If the electric field applied at this time is applied with an alternating current voltage, the direction of this curvature changes alternately, and if this is supported by a part, it becomes a sounding body.
By using this kind of transformation, you can not only change the sounding body, but also
By moving the contacts, it can be used as a relay or actuator, and many devices related to these have been devised.

One of these applications is to attach the piezoelectric bimorph diaphragm to a part of the outer wall of the fluid path, and install check valves near the fluid supply port and fluid jet port at both ends of the fluid path to drive a motor, etc. It is possible to create a fluid ejecting nozzle that does not require mechanical parts like the one used in this invention, and can be used in the heads of inkjet printers, etc.

(Problem to be Solved by the Invention) In such a fluid ejecting nozzle, even if a diaphragm is simply formed on one side of the fluid path, the volume change of the fluid path caused by the deformation of the diaphragm is caused by the diaphragm. , the fluid in the fluid path also moves uniformly. For this reason, as shown in FIG. 6, the diaphragm 61 is deformed and the discharged fluid also comes out from the supply port. Furthermore, when the diaphragm returns to its original deformation, air is sucked in not only from the supply port but also from the jet port. In order to eliminate such drawbacks, it is necessary to install valves to prevent backflow at each of the supply port and the jet port. However, such check valves must be configured to allow flow in only one direction. For this reason, there is a limit to miniaturization; for example, it is difficult to install this check valve in a fluid path of several millimeters or less, and even if a check valve is installed, it is impossible to spray fluid straight. Become. Furthermore, even if one considers integrating ceramics for miniaturization, it is not possible to form such a check valve.

An object of the present invention is to provide a piezoelectric fluid ejection nozzle that solves these conventional problems.

(Means for Solving the Problems) That is, the present invention has at least one fluid supply port and one or more fluid jet ports each having a fluid path formed therein, and the fluid supply port and the fluid jet port are displaced in a certain direction. There are at least two or more bimorph forming parts that are partially fixed in the fluid path so as to produce a It is made of a laminate of a material that becomes a piezoelectric body when sintered and a material that becomes a conductor when sintered.

(Function) The piezoelectric fluid ejecting nozzle of the present invention is configured as a bimorph-type laminate in which two vibrating parts that move independently in a fluid path form three electrode layers, and a part of this is formed in a fluid path. It is fixed to a part of the wall and has a fluid path and two independent bimorph parts so that a fluid supply port and a fluid jet port are formed at the positions on the displacing side of this bimorph part, respectively. . Therefore, the bimorph on the supply port side and the bimorph on the ejection port side can be driven independently, and a time difference can be provided between them. If the bimorph in the fluid path is first deformed at the fluid supply port, fluid will be blown out from the fluid jet port, and then the bimorph on the fluid outlet side will be deformed while the bimorph on the fluid supply port side remains deformed. If the fluid supply port side is returned to its original position, fluid will be supplied from the fluid supply port. Furthermore, even when the bimorph on the fluid spout side is returned to its original state, the direction of the fluid is deformed to the direction in which the fluid is supplied from the fluid supply port, so there is a possibility that the fluid will flow backwards during one cycle from the fluid spout to the supply. There is no problem, and a piezoelectric fluid ejecting nozzle integrally made of ceramic can be obtained.

(Example) Next, a piezoelectric fluid ejection nozzle of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of a piezoelectric fluid ejection nozzle showing one embodiment of the present invention.

First, in the fluid path 11, there are two independent bimorphs 13 and 14 each having three layers of electrodes 12, and a fluid supply port 1 is located on the displacing side of the bimorph.
5 and a fluid spout 16. Further, the two bimorphs 13 and 14 are fixed at one end to the wall of the fluid path. At this time, the positional relationship between the fixed bimorph and the fluid supply port and fluid jet port is such that when no voltage is applied to the bimorph (that is, the bimorph is not deformed), the fluid supply port and fluid jet port are Configure it so that it is at the height of the top. Furthermore, this fluid supply port has a fluid supply path 1.
7 is connected.

FIG. 2 is a plan view showing an example of a pattern formed in a piezoelectric material green sheet and an example of a hole punching state for obtaining a piezoelectric fluid ejecting nozzle of the present invention. Laminated.

In the configuration shown in FIG. 2, first, a is a green sheet that forms the uppermost fluid path wall surface, and b is a green sheet that has a cut portion 21 that forms a space above the bimorph forming portion. Next, c is a green sheet for insulating the uppermost electrode from the fluid, and has a cut part 22 having a shape that matches the bimorph forming part, and below this is an electrode 23 forming the bimorph and the bimorph part. There are green sheets of bimorph forming parts d, e, and f, which have a cut part 24 for making them in a free state and an extraction electrode 25 for taking out each electrode to the outside. Furthermore, g is a green sheet having a cut portion 26 for forming a space for allowing the bimorph to deform, and h is a green sheet having a cut portion 27 for forming a fluid path and a supply port and a spout of the fluid path. i is a green sheet having a cut portion 28 for forming a fluid path, and finally j is a green sheet forming the lowest layer fluid path wall surface. In the explanation in FIG. 2, the pattern and shape of one piezoelectric fluid ejecting nozzle are shown, so although the green sheet h is divided into two, in reality, there are multiple patterns. A single green sheet is formed, and a pattern for each layer can be obtained by cutting after lamination. Also, if the cut portions of each green sheet in Figure 2 are laminated and pressed as they are, they will be crushed, so after cutting each sheet, cut carbon green sheets or carbon paste that matches the pattern of the cut portion. All you have to do is fill it with a material that burns and gasifies during the firing process, forming a cavity.

The 10 piezoelectric green sheets thus obtained are stacked in a press mold, heated at a temperature of around 100°C, and pressed under a pressure of around 250 kg/cm ² to obtain a laminate. Next, this laminate is subjected to a binder removal process and then sintered to obtain a piezoelectric fluid ejecting nozzle having the cross-sectional structure shown in FIG.

In addition, in the laminated structure shown in this example, the sheets forming the upper and lower fluid path walls are shown as one layer, but if reinforcement is required due to the thickness of the green sheet, multiple green sheets of each may be used. It is clear that the structure can provide reinforcement and protect the internal bimorph forming part. Further, the shape of the bimorph forming section is not limited to this type, and can be freely designed according to the shape of the fluid path, and the number and size of the fluid supply ports and fluid jet ports are also not limited. On the other hand, although the fluid supply port and the fluid discharge port are arranged to face each other with respect to the two bimorph forming parts, if the fluid supply port and the fluid ejection port are provided in the part where the bimorph is displaced, a third As shown in the figure, two bimorph forming parts 31 are lined up in the same direction, and a partition part 3
The pattern of each green sheet may be configured such that the green sheet 2 and the fluid path 33 are formed.

The piezoelectric material green sheet used here is made by dispersing electrostrictive material powder whose main components are magnesium lead niobate Pb (Mg1/3 Nb2/3) O ₃ in a solvent together with an organic binder. do. This is made into a ceramic raw sheet having a uniform thickness of 20 μm to 200 μm by slip casting using a doctor blade.

This raw ceramic sheet is punched out to a specified size, and holes for forming each cut portion are formed using a punch and a die. Next, an electrode paste is printed on the processed green sheet of the bimorph forming part including the holes using a screen printer. Furthermore, these green sheets are set in a press mold, and at the same time, each green sheet is stacked and heated at a temperature of around 100℃ while embedding a carbon green sheet corresponding to each cut part.
A laminate is obtained by pressure bonding at a pressure of approximately Kg/cm ² . Next, after cutting this laminate into predetermined dimensions as necessary, organic matter present in the cavity pattern and ceramic green sheets is first heated slowly in an oxidizing atmosphere in a debinding process to decompose and decompose the organic matter.
make it disappear Usually these organic substances are 500℃~600℃
However, if the temperature is suddenly raised to the decomposition temperature, the laminate will be damaged.
The temperature is raised at a rate of 0.degree. C./hour or at a slower temperature increase rate and maintained at 500.degree. C. to 600.degree. C. for a sufficiently long period of time to completely eliminate the organic matter.

After this, by firing at a temperature of 900℃ to 1200℃,
A piezoelectric fluid ejection nozzle as described above is obtained. Note that since the electrode pattern as the extraction terminal extends to the end face of the laminate, silver paste or the like may be baked there as an external electrode.

In the piezoelectric micropump obtained as described above, first, a voltage of about 100 to 200 V is applied to the electrodes of the bimorph forming part for about 1 minute in order to perform a polarization process.

Next, the electrodes of these two bimorph forming parts are connected in parallel so as to be connected in opposite directions with respect to the polarization direction, and are taken out as terminals of bimorph 1 and bimorph 2.

In this way, two drive circuits are connected to the extracted terminals so that the voltage waveform as shown in FIG. 4 is obtained. 5A to 5E are cross-sectional views of the movement of the piezoelectric fluid ejection nozzle of the present invention when driven by this drive waveform.

First, a is a state in which no voltage is applied to either bimorph, and the fluid path is filled with fluid. b is a state in which a voltage is applied to the bimorph on the fluid supply port side, and this bimorph is deformed, and the fluid moves toward the fluid discharge port, and at the same time, the fluid is blown out from the fluid ejection port. In c, the bimorph at the other fluid jetting port is also deformed by applying voltage, and at this time, the fluid jetting from the fluid jetting port is cut off. d is a state in which the voltage of the bimorph on the fluid supply port side is cut off and returned to its original state by the operation of the discharge circuit, and when this returns, fluid is supplied from the fluid supply port into the fluid path. In e, the voltage of the bimorph on the fluid ejection side is cut off, and it is returned to its original state by the operation of the discharge circuit. At this time, fluid is supplied from the fluid supply port into the fluid path, and the state in a is returned. It means that it has passed. Similarly, b
By repeating steps .about.e, a fluid ejection nozzle that can continuously eject fluid is formed. At this time, the bimorphs that deform independently on the fluid supply port side and the fluid jet port side operate at different times, so this operation itself exerts the effect of a check valve.
There will be no air inhalation.

(Effects of the Invention) As is clear from the above description, according to the present invention, by forming independent bimorphs in the fluid path that deform respectively to the fluid supply port side and the fluid jet port side, this independent bimorph It is a pump that allows fluid to flow in a fixed direction by driving two bimorphs at different times, and the two bimorphs that operate at this time work to prevent backflow. Therefore, a valve for preventing backflow is completely unnecessary, and no matter the size of the fluid path, it is sufficient to form two bimorphs in the fluid path, and an ultra-small fluid ejecting nozzle can be obtained. Furthermore, the piezoelectric fluid ejecting nozzle of the present invention is obtained only by laminating and sintering piezoelectric ceramics, and does not require any external parts or other assemblies. becomes.

In the embodiment of the present invention, the piezoelectric ceramic green sheet is constructed using the lamination technology, but if miniaturization is not particularly required, only the bimorph plate can be obtained using the ceramic lamination technology. It is obvious that the same effect can be obtained by assembling the fluid passage into a fluid path having a fluid supply port and a fluid jet port made of a material such as stainless steel. or,
If the fluid supply port is matched to the diameter of a fluid conveying hose, for example, and ink is used as the fluid, an ink jet head of a printer can be created. Furthermore, if a fluid path and a fluid supply port are formed above the bimorph forming part, and the drive voltage is set to AC voltage and the phase is the same as the drive waveform shown in Fig. 4, the amount of deformation of the bimorph part becomes large, and the upper and lower parts Since the fluid in the fluid path can be moved alternately, the amount of fluid ejected from the fluid ejecting nozzle and the force of ejecting the fluid are increased, and a high-performance piezoelectric fluid ejecting nozzle can be obtained.

On the other hand, the method of forming internal pores is not limited to carbon green sheets or carbon paste.
-243218 and No. 60-243219, a piezoelectric fluid ejecting nozzle with the same effect can be obtained by exposing a photosensitive resin to light and pressing a patterned film onto a green sheet during lamination.

The piezoelectric fluid ejection nozzle of the present invention uses the fluid ejection port as the fluid discharge port to the fluid path, so that when driven by continuous waves, the fluid continuously flows out from the fluid discharge port, for example to the engine, etc. It is clear that it can be used as a micropump for transporting fuel or as a microdispenser for transporting highly viscous substances.

In addition, by aligning the fluid ejection ports with the dot pitch of the dot printer, and forming a pattern with a material that is burnt out during the firing process, a narrow fluid path can be easily formed between the fluid ejection ports at this pitch and the fluid path containing a plurality of piezoelectric bimorphs of the present invention. An inkjet dot printer can be configured.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of one embodiment of the present invention, FIG. 2 is a diagram of the shape of a green sheet and its pattern showing one embodiment of the present invention, and FIG. 3 is an internal bimorph diagram showing another embodiment of the present invention. Perspective plan view of the forming part, 4th
The figure shows the drive waveform for driving two bimorphs and the drive circuit diagram. Figure 5 is a cross-sectional view of the structure shown in Figure 1 when it is driven in the state shown in Figure 4. Figure 6 is a piezoelectric FIG. 3 is a cross-sectional view of the mold ink jet head. In the figure, 11...fluid path, 12... electrode,
13... Bimorph on the fluid supply side, 14... Bimorph on the fluid jet port side, 15... Fluid supply port, 1
6...Fluid spout, 17...Fluid supply path, 21...
...A cut portion forming a space above the bimorph forming portion, 22...A cut portion forming the shape of a bimorph forming portion for insulating the uppermost electrode of the bimorph forming portion, 23...An electrode forming a bimorph, 24 ...Cut part for making the bimorph part free state, 25... Extraction electrode, 26...
A cut portion for forming a space for making the bimorph deformable, 27...a cut portion for forming a fluid path, a fluid supply port, and a fluid jet port;
28...Cut portion forming a fluid path, 31...Bimorph forming portion, 32...Partition wall, 33...Fluid path, _V1 ...Drive waveform on the fluid supply port side, _V2 ...
... Drive waveform on the fluid jet port side, 61 ... Vibration plate.

Claims (1)

[Scope of Claims] 1. There is at least one fluid supply port and one or more fluid jet ports each having a fluid path formed therein, and the fluid path is arranged such that displacement occurs in a certain direction of the fluid supply port and the fluid jet port. 1. A voltage type fluid ejecting nozzle characterized in that there are at least two or more bimorph forming parts that are partially fixed, and a drive circuit is connected to each bimorph. 2. The piezoelectric fluid ejecting nozzle according to claim 1, wherein the bimorph forming portion is a laminate of a material that becomes a piezoelectric body when sintered and a material that becomes a conductor when sintered.