JP3496191B2 - Piezo device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric device using a piezoelectric vibrator, and more particularly to a piezoelectric device having electrodes on only one of the upper and lower surfaces of a piezoelectric vibrator plate for facilitating extraction of electrical signals. The present invention relates to piezoelectric devices such as vibrators, piezoelectric transformers, and piezoelectric filters.

[0002]

2. Description of the Related Art Piezoelectric devices such as piezoelectric transformers and piezoelectric filters are known as devices to which piezoelectric vibrators are applied. At present, ceramics and lithium niobate single crystals are often used as vibrators for such piezoelectric devices. Has been done. As a general structure of such a piezoelectric device, an input electrode for inputting an electric signal is provided on one of the upper and lower surfaces of the piezoelectric vibrator, and the other upper and lower surfaces different from the surface having the input electrode are electrically grounded. A ground electrode is formed. Further, in the piezoelectric transformer, as shown in FIGS. 4 and 5, an input electrode 42 and an output electrode 43 capable of inputting and outputting an electric signal are respectively provided on one of upper and lower surfaces of a square plate 41 made of a piezoelectric vibrator. The input electrode 42,
Ground electrodes 44 and 45 capable of being electrically grounded are formed on the other upper and lower surfaces different from the surface having the output electrode 43.

In the actual manufacturing process, electrodes are formed on one surface of the upper and lower surfaces, and then electrodes on the other surface different from the surface are formed to manufacture a piezoelectric device.

[0004]

Generally, piezoelectric devices have been extremely miniaturized in recent years along with miniaturization of peripheral devices. As shown in FIGS. 4 and 5, a conventional piezoelectric device such as a piezoelectric filter or a piezoelectric transformer has an input electrode 42 and an output electrode capable of inputting, outputting, and grounding an electric signal to at least two opposing surfaces of a piezoelectric vibrator. 43,
Since the ground electrodes 44 and 45 are provided, at the time of extracting an electric signal from each of the input electrode 42, the output electrode 43, and the ground electrodes 44 and 45, at least two lead wires or the like from the upper and lower surfaces of the square plate 41 are used. Even if the piezoelectric vibrator is downsized in order to extract an electric signal, it is very difficult to make the piezoelectric device smaller and taller than ever before. Further, this is a general technique for downsizing electronic devices and the like, and even in the surface mounting in which only one surface of the device is electrically connected to the outside, in the conventional piezoelectric device, the upper and lower surfaces of the square plate 41 are used. Surface mounting was also very difficult because the lead wires for taking out two electric signals from the surface of the were pulled out.

Furthermore, in an actual manufacturing process, since an electrode is formed on one surface and then an electrode is formed again on the surface and the other surface by using the same process, a process time which is twice as long as one surface is required. Was needed.

As described above, in the conventional piezoelectric device, the lead wire or the like for taking out an electric signal from the electrodes on at least two upper and lower surfaces of the piezoelectric vibrator plate is required,
There was a fatal structural problem in miniaturization and accompanying surface mounting.

An object of the present invention is to make it possible to take out all electrical signals from only one of the upper and lower surfaces of the piezoelectric vibrator plate, to achieve miniaturization and sufficient surface mounting, and to shorten the process time. It is to provide a piezoelectric device that can be shortened.

[0008]

According to the present invention, an input electrode for inputting an electric signal is provided on either one of the upper and lower surfaces of a piezoelectric vibrator plate and an earth electrode for electrically grounding. And niobium having the spontaneous polarization axis as the Z axis
In the lithium oxide single crystal, the coordinate axis is 1 around the X axis.
The coordinate system (X, Y ', Z') rotated by 20 to 170 degrees is
Furthermore, the seat rotated by -20 to 20 degrees around its Z'axis
In the standard system (X ', Y ", Z'), the lithium niobate is used.
Cut the plate surface of the um single crystal so that it is parallel to the X'axis and Z'axis.
Using the projected piezoelectric vibrator plate,
The piezoelectric vibrator plate cut out from the crystal is square with four corners.
A piezoelectric vibrator using Lame mode vibration, which is a node of vibration,
It is possible to obtain a piezoelectric device having a shape in which one or more than one is arranged in rows and columns .

Further, according to the present invention, an input electrode for inputting one or a plurality of electric signals to one of the upper and lower surfaces of the piezoelectric vibrator plate, and an output for outputting an electric signal. Niobate having a grounding electrode that can be electrically grounded to the working electrode and having the spontaneous polarization axis as the Z axis
In the single crystal of titanium, the coordinate axis is 120 around the X axis.
The coordinate system (X, Y ', Z') rotated by ~ 170 ° is
The coordinate system rotated by -20 to 20 degrees around its Z'axis
(X ′, Y ″, Z ′), the lithium niobate
Cut so that the plate surface of the single crystal is parallel to the X'axis and Z'axis
Using the piezoelectric vibrator plate described above, the lithium niobate single crystal
Piezoelectric vibrator plate cut out from is square, and the four corners vibrate.
One piezoelectric vibrator using Lame mode vibration that becomes the node of
Alternatively, it is possible to obtain a piezoelectric device having a shape in which a plurality of two or more are arranged vertically and horizontally .

[0010]

[0011]

[0012]

[0013]

[0014]

In the present invention, since a plurality of electrodes for extracting an electric signal are provided on only one surface of the upper and lower surfaces of the piezoelectric vibrator plate used for the piezoelectric device, a lead wire for extracting the electric signal is provided on one surface of the piezoelectric device. Can be easily configured, and further downsizing and height reduction can be achieved. Moreover, since the electric terminals can be formed only on one surface of the piezoelectric device, surface mounting can be easily performed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, as a piezoelectric device according to an embodiment of the present invention, an embodiment of a piezoelectric transformer will be described in detail with reference to the drawings.

FIG. 1 is a perspective view showing an example of the structure of the piezoelectric transformer according to this embodiment, and FIG. 2 is a sectional view taken along the line aa 'in FIG. As shown in FIG. 1, the piezoelectric transformer has an aspect ratio of 1: when cut out from a lithium niobate single crystal.
1 and a square plate 11, and an input electrode 12 composed of four-divided electrodes formed on one of the upper and lower surfaces of the square plate 11.
a and an input ground electrode 12b, an output electrode 12c and an output ground electrode 12d.

FIG. 3 is a perspective view showing the structure of the package of the piezoelectric transformer of FIG. 1 according to the present embodiment, which is composed of four divided electrodes on the square plate 11 and the input electrodes 12a,
Lead wires 33a, 33 for extracting electric signals from the input ground electrode 12b, the output electrode 12c, and the output ground electrode 12d.
electrode terminals 35a, 35b, 35c for external connection formed on the package 34 with b, 33c, 33d,
It is configured by connecting to 35d, and can be sufficiently adapted to surface mounting.

A specific example of the method for manufacturing the piezoelectric transformer according to this embodiment will be described below. Using a commercially available lithium niobate single crystal, the spontaneous polarization axis (Z axis) is rotated by 155 ° about the X axis, and further rotated by 5 ° about the Z ′ axis orthogonal to the X axis. A square plate 11 having a size of 20 × 20 mm and a thickness of 0.5 mm was cut out. Aluminum is vapor-deposited on one surface of the square plate 11 to form four divided electrodes 12a, 12
b, 12c and 12d were formed. Then these electrodes 1
Square plate 11 formed with 2a, 12b, 12c and 12d
Is fixed to the package 34, and the lead wires 33a, 33b,
Electrode terminals 35a, 35b, 35c, 35d for external connection were connected via 33c, 33d to form a piezoelectric transformer. Table 1 shows the measurement results of the input voltage and the output voltage and the step-up ratio in this piezoelectric transformer. At this time,
The load resistance is 100 MΩ.

[0019]

[Table 1] As shown in Table 1, it was confirmed that the step-up ratio was substantially constant even when the input voltage changed.

[0020]

As described above, according to the present invention,
Since the electrodes are formed only on one of the upper and lower surfaces of the piezoelectric vibrator, it is possible to further reduce the size and height.

Further, since the electric terminals can be formed on only one surface of the piezoelectric device, surface mounting can be easily performed, the manufacturing process can be sufficiently simplified, and a piezoelectric device having excellent characteristics and reliability can be provided. .

That is, according to the piezoelectric device of the present invention ,
It is possible to further reduce the size and height of the piezoelectric device and improve workability.

According to the piezoelectric device of the present invention ,
In addition to downsizing, height reduction, and improvement in workability, since input / output electrodes can be formed on the surface, a device having three or more terminals such as a piezoelectric transformer can be configured.

According to the piezoelectric device of the present invention ,
Since the electrodes are provided in addition to the input / output section, a complicated electrode structure such as a return electrode can be formed on one surface, so that lead wires can be drawn out very easily.

According to the piezoelectric device of the present invention ,
The lead wire can be drawn out on one surface, and the characteristics can be further improved. Furthermore, by having an electrode on the back surface,
Since the electric field distribution stands in the direction perpendicular to the electrodes, a more efficient piezoelectric device can be constructed.

According to the piezoelectric device of the present invention ,
By using a lithium niobate single crystal for the piezoelectric vibrator, it is possible to improve the characteristics due to high Q. Further, it is possible to configure a small-sized and low-profile piezoelectric device that has excellent characteristics with little heat generation at a large amplitude.

Further, according to the piezoelectric device of the present invention ,
Due to the Lame mode vibration, the four corners of the vibrator can be supported, and the lead wire is drawn out only on one surface, which facilitates surface mounting.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a configuration of a piezoelectric transformer according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along the line aa ′ of the piezoelectric transformer shown in FIG.

3 is a perspective view showing a configuration of a package of the piezoelectric transformer shown in FIG.

FIG. 4 is a diagram showing a configuration example of a conventional piezoelectric transformer.

5 is a sectional view taken along line bb 'of the conventional piezoelectric transformer shown in FIG.

[Explanation of symbols]

11 square plates 12a input electrode 12b Input ground electrode 12c output electrode 12d output ground electrode 33a, 33b, 33c, 33d Lead wire 34 packages 35a, 35b, 35c, 35d electrode terminals 41 square plate 42 Input electrode 43 Output electrode 44, 45 Ground electrode

─────────────────────────────────────────────────── --Continued from the front page (56) References JP-A-5-259528 (JP, A) JP-A-5-335648 (JP, A) JP-A-6-97527 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H01L 41/107 G01P 9/04 H01L 41/09 H03H 9/02 G01C 19/56

Claims (2)

(57) [Claims] [Claim 1] have a input electrode and the electrically grounded earth ground electrodes for inputting respective electrical signal to either one of the upper and lower surfaces of the piezoelectric vibrator plate, a spontaneous polarization axis Z
Coordinates in a lithium niobate single crystal having an axis
A coordinate system in which the axis is rotated 120 to 170 degrees around the X axis.
(X, Y ', Z') around the Z'-axis
In the coordinate system (X ', Y ", Z') rotated by 20 to 20 degrees
The plate surface of the lithium niobate single crystal has the X ′ axis Z ′.
Using a piezoelectric vibrator plate cut out so as to be parallel to the axis,
Piezoelectric vibrator cut out from the lithium niobate single crystal
The plate is square, and the Lame mode vibration with four corners is the node of vibration.
1 or 2 or more piezoelectric vibrators using dynamics
A piezoelectric device characterized by being arranged in a line . 2. An input electrode for inputting one or a plurality of electric signals to either one of the upper and lower surfaces of the piezoelectric vibrator plate, and an output electrode for outputting an electric signal electrically. Has a grounding electrode that can be grounded, and has a spontaneous polarization axis
In a lithium niobate single crystal having Z as an axis,
Coordinates obtained by rotating the coordinate axes by 120 to 170 ° around the X axis
The system (X, Y ', Z') around its Z'axis
In the coordinate system (X ', Y ", Z') rotated by -20 to 20 degrees
The plate surface of the lithium niobate single crystal has an X ′ axis.
Use a piezoelectric vibrator plate that is cut out so that it is parallel to the Z'axis.
Piezoelectric vibration cut out from the lithium niobate single crystal
The pendulum plate is square and the four corners are vibration nodes.
One or more piezoelectric vibrators using vibration
A piezoelectric device characterized in that a plurality of piezoelectric devices are arranged .