JPH1067104A - Piezoelectric member and ink jet head equipped therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to polarize a piezoelectric body in every layer to the direction different from the direction of electric field at driving the piezoelectric body by arranging an electrode for driving the piezoelectric body and other electrodes, each of which generates an electric field having the direction different from the application direction of voltage. SOLUTION: An ink jet head 2 consists of four layers 101-104 integrally formed by sintering. An actuator part 21 is equipped with a piezoelectric body 20, polarizing electrodes 22a, 22b and 22c, which are within the piezoelectric body 20 so as to polarize the piezoelectrid body 20 so as to polarize the piezoelectric body heated in advance by applying high voltage to the polarizing electrodes 22a-22c. To polarize, concretely, minus voltage is applied to the electrode 22b, while plus voltage is applied to the electrodes 22a and 22c respectively. Thus, the piezoelectric body 20 at the actuator part 21 pinched by the polarizing electrodes 22a-22c is polarized to the direction indicated with the arrows.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric member mainly used for an ink jet head of an ink jet printer, and more particularly to a piezoelectric member capable of using a shear mode. Further, the present invention relates to an inkjet head using the piezoelectric member.

[0002]

2. Description of the Related Art Conventionally, there has been known an ink jet printer in which ink is pressed by a piezoelectric member and discharged from a nozzle. The piezoelectric member of an ink jet head used in such an ink jet printer is formed by stacking thin ceramic green sheets serving as piezoelectric bodies while sandwiching an internal electrode, sintering, and then applying a high voltage to the internal electrode. It is manufactured by a procedure of performing a polarization process.

An ink jet head having a piezoelectric member manufactured as described above drives a piezoelectric member by applying a voltage to an internal electrode used for a polarization process to discharge ink.

[0004]

However, in the above-described conventional ink jet head, the direction of polarization of the piezoelectric body is parallel to the direction of the electric field generated by the voltage applied for driving. Therefore, can only drive using d ₃₃ thickness direction displacement is rigid substrate for supporting the displacement of the piezoelectric member is required to exert a pressing force to the ink, the head is such as to size issues there were.

It is an object of the present invention to provide a piezoelectric member of an ink jet head in which the direction of an electric field generated by a voltage applied for driving is different from the direction of polarization of a piezoelectric body.

[0006]

In order to achieve the above object, a piezoelectric member according to the present invention is a piezoelectric member and an electrode for generating an electric field in a first direction when a voltage is applied. And a second electrode that generates an electric field in a second direction different from the first direction when a voltage is applied.

[0007] Further, the ink jet head of the present invention comprises:
In an ink jet head that presses ink by a piezoelectric member and discharges the ink from a nozzle, the piezoelectric member is a piezoelectric body and an electrode for driving the piezoelectric body, and when a voltage is applied, an electric field is generated in a first direction. And a second electrode that generates an electric field in a second direction different from the first direction when a voltage is applied.

[0008]

FIG. 1 is a perspective view of an ink jet recording apparatus according to a first embodiment of the present invention.

Referring to the drawings, a recording sheet (recording medium) 1 such as a sheet of paper or a thin plastic sheet is fed into a printer unit by a paper feeding device such as a manual feed sheet or a cut sheet feeder, and is fed to a paper feed roller (not shown). By controlling the amount of rotation, the sheet is conveyed to a position facing the recording head 2 (a cueing position) and set to a recording start state.

A recording head 2 mounted on a carriage 3
Is an inkjet head using a piezoelectric member,
Due to the volume change of the channel (pressurized chamber) caused by the distortion generated by applying a voltage to the piezoelectric member,
The recording is performed by discharging ink from nozzles provided in the channel portion. A plurality of ejection ports (nozzles) are provided vertically on the front surface (ejection port forming surface) of the recording head 2.

The carriage 3 is supported by sliding shafts 4 and 5 so as to be able to reciprocate. You. This carriage 3
Is main-scanned in the digit direction of the recording sheet 1 (a direction traversing the recording sheet 1) to record an image for one line. Go.

At a position facing the recording head 2, a platen 9 serving as a guide plate for guiding the recording sheet 1 along the transport path is disposed. The platen 9 may also serve as a fixing device by attaching a heater wire (not shown) to a sheet metal to form a surface heater. The recording sheet 1 is located below the range (recording area) in which the recording head 2 performs main scanning, that is, at a portion close to the recording area on the upstream side in the paper feeding direction.
0 presses against the platen 9, thereby preventing the recording sheet 1 from floating. The recording sheet 1 that has passed through the recording section has a discharge roller 11 disposed downstream of the recording sheet and a spur roller 12 pressed against the discharge roller 11.
And it is discharged by.

On the other hand, at a position facing the recording head 2 and away from the platen 9, there is provided a recovery system 13 for recovering an ink ejection failure of the recording head 2 to a satisfactory state. At the end of the operation, the recording head 2 is moved to a position facing the recovery system 13 for cleaning.
The paper feed roller (conveyance roller) is provided with a paper feed knob 14 for manually conveying the recording sheet 1.

FIG. 2 is a sectional view for explaining the configuration of the recording head 2 of FIG. Referring to the drawing, the ink jet head 2 is formed of four layers 101 to 104, which are integrally sintered. 101 to 103 are flow path regions, and 104 is a piezoelectric member region. The piezoelectric member region 104 is made of, for example, lead zirconate titanate (PZ).
T) is formed by laminating a plurality of thin layers of a piezoelectric material.

A plurality of nozzles 25 for ejecting ink, a plurality of pressure chambers (channels) 31, and a plurality of ink inlets 26 for introducing ink are formed at predetermined positions of the flow path regions 101 to 103, respectively. Inlet 2
6, a common chamber 27 is formed. A connection pipe 28 is formed on the surface of the piezoelectric member region 104 at a position where the connection pipe 28 is connected to the common chamber 27. A tube 29 is connected to the connection tube 28. The tube 29 is connected to an ink tank (not shown).

An area of the piezoelectric member area 104 which is in contact with the channel 31 has a piezoelectric body which has been subjected to a polarization process described later, and is deformed by application of an electrode.
1, a common ground electrode 24 and a driving electrode 23 for driving the inkjet head are provided. The lead wire 30 is connected to the driving electrode 23. By applying a voltage to the lead wire 30, the actuator section 21 bends downward in FIG.
The volume of the pressure chamber 31 decreases. As the volume of the pressure chamber 31 decreases, ink is ejected from the nozzle 25.

The actuator section 21 includes a piezoelectric body 20 and
There are provided polarization electrodes 22a, 22b and 22c inside the piezoelectric body 20 for polarizing the piezoelectric body 20, and these polarization electrodes 22 are heated in advance.
Polarization processing is performed by applying a high voltage to a to 22c. When performing the polarization process, a negative voltage is applied to the electrode 22b, and a positive voltage is applied to each of the electrodes 22a and 22c. Thereby, the polarization electrodes 22a to 22a
The piezoelectric body of the actuator section 21 sandwiched between c is polarized in the direction of the arrow in the figure.

Thus, the direction of the electric field formed by the voltage applied when the head is driven is orthogonal to the direction of polarization of the piezoelectric body 20 of the actuator section 21. Therefore, (mode using a displacement constant d ₁₅₎ shear mode to drive the actuator unit 21 can be used. Since the displacement constant d _{15 in the} shear mode is 2.5 times or more larger than the displacement constant d _{33 in} the thickness direction, a large displacement can be obtained with a small energy.

The positions of the polarization electrode and the drive electrode are not limited to the example shown in FIG. In particular, by changing the position of the polarization electrode, the piezoelectric body can be polarized in a desired direction.

FIG. 3 is a cross-sectional view of the ink-jet head 2 of FIG. 2 cut in a direction perpendicular to the paper surface.

Referring to FIG. 1, the nozzles 25a and 25b are arranged at equal intervals to form an image of one line. Each nozzle is provided with a respective pressurizing chamber 31a, 31b and a driving electrode 23a, 2b.
3b. The ground electrode 24 serves as a common electrode for each nozzle. The polarization electrode 22 is inserted in the piezoelectric body 20 as shown in the figure.

The ink jet head shown in the first embodiment is manufactured by the following manufacturing steps.

First, green sheets of a ceramic material are laminated while being punched and formed in the flow path regions 101 to 103. The green sheet is obtained by dispersing a calcined powder of ceramics in a dispersion medium by adding a small amount of a binder, a plasticizer and the like to prepare a slurry, and then forming a film by a tape casting method or the like.

Next, after placing the piezoelectric member region 104, it is pressurized and fired. The piezoelectric member region 104 is formed by forming an electrode layer on a green sheet of a piezoelectric ceramic material by, for example, applying a metal paste by a printing method, and then stacking the green sheet of the piezoelectric ceramic material, and then forming an electrode for polarization. It can be produced by pattern printing the Ag-Pd paste to be used by known screen printing, stacking a green sheet of a piezoelectric ceramic material again, and forming an individual electrode layer on this upper surface. In addition, what is necessary is just to form the part used as a common chamber by punching similarly to the case of the flow-path area | region 101-103.

The channel regions 101 to 103 may be formed using a ceramic material such as zirconium oxide or aluminum oxide. In addition, it is also possible to use the same piezoelectric ceramic material as the piezoelectric member region 104 such as lead zirconate titanate. In this case, the polarization treatment may not be performed.

Next, the polarization processing of the piezoelectric body 20 is performed by using the polarization electrode 22. The polarization condition is
In the case of PZT, for example, while maintaining PZT at 120 ° C., a DC voltage of about 2 to 8 V / μm is applied for 10 minutes. If the distance between the electrode 22a for polarization, the electrode 22b, and the electrode 22c shown in FIG. 2 is 0.5 mm, a voltage of about 1.4 kV may be applied.

The electrodes for polarization are also subjected to pattern printing by a screen printing method or the like so as to have the shape shown in FIG.

FIGS. 4 and 5 are cross-sectional views of the ink jet head according to the second embodiment. Figures 4 and 5
Correspond to FIGS. 2 and 3, respectively.

Referring to the drawings, the ink jet head according to the second embodiment has a separate groove g provided between individual nozzles in addition to the configuration shown in FIGS. Such a separate groove g is formed by cutting the ink jet head with a dicing saw so as not to cut the polarizing electrode. This cutting is preferably performed after the piezoelectric member region and the ink flow path region are integrally sintered and polarized. The formation of the separate groove g can prevent interlocking deformation (crosstalk) between the adjacent pressure chambers.

FIG. 6 is a sectional view showing the structure of the actuator section in the piezoelectric member region of the ink jet head according to the third embodiment.

Referring to the drawings, in this embodiment,
The piezoelectric member region is characterized in that the actuator section 21 is formed in an N layer. Driving electrodes 23 and ground electrodes 24 are alternately arranged between the piezoelectric layers. Then, in each piezoelectric layer, the same polarization electrodes 22a to 22a as described in each of the above embodiments are used.
22c is formed.

With such a configuration, the piezoelectric body can be polarized in a direction different from the electric field direction at the time of driving for each layer.

Further, by appropriately setting the width and the interval of the electrodes of the polarization electrode 22, the function of a dummy electrode for preventing the thickness from being uneven when the piezoelectric bodies are laminated can be combined. In the case where such a laminated voltage member is manufactured, a method of alternately performing the stacking of the piezoelectric layers and the pattern printing of the electrode layers can be adopted as described above.

[Brief description of the drawings]

FIG. 1 is a perspective view of an ink jet recording apparatus.

FIG. 2 is a cross-sectional view for explaining a configuration of the inkjet head 2 according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view in a direction orthogonal to the cross-sectional view of FIG.

FIG. 4 is a cross-sectional view illustrating a configuration of an inkjet head according to a second embodiment.

FIG. 5 is a sectional view in a direction orthogonal to a fourth sectional view.

FIG. 6 is a cross-sectional view illustrating a piezoelectric member of an inkjet head according to a third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 20 Piezoelectric body 21 Actuator part 22a-22c Polarizing electrode 23 Driving electrode (individual electrode) 24 Earth electrode (common electrode) 25 Nozzle 31 Pressurized chamber (channel) 101-103 Channel area 104 Piezoelectric member area

Claims (3)

[Claims] 1. A piezoelectric body, an electrode for generating an electric field in a first direction when a voltage is applied, a first electrode for driving the piezoelectric body, and a first electrode for applying a voltage to the first direction. And a second electrode that generates an electric field in a different second direction. 2. The piezoelectric member according to claim 1, wherein said piezoelectric member is polarized using said second electrode. 3. An ink jet head that presses ink by a piezoelectric member and discharges the ink from a nozzle, wherein the piezoelectric member is a piezoelectric body and an electrode for driving the piezoelectric body, and when a voltage is applied, the piezoelectric member moves in a first direction. An ink jet head comprising: a first electrode for generating an electric field; and a second electrode for generating an electric field in a second direction different from the first direction when a voltage is applied.