JP2004088137A - Small-sized high frequency vibrator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small-sized high frequency vibrator whereby stable desired principal vibration without production of spurious radiation is produced by the vibrator that makes AT-cut fundamental wave thickness share vibration with a frequency of 100 MHz or over and is integrally formed with a vibration section of a crystal raw thin plate and a reinforcement section made of a crystal raw thick plate surrounding the surrounding part of the vibration section. <P>SOLUTION: An energy confinement coefficient of the vibrator is selected to be 3.5 or over and a length of a vibration plane is selected to be a multiple of 1.4 to 2.0 with respect to a length of an electrode plane to attain the purpose above in the vibrator that makes the AT-cut fundamental wave thickness share vibration with a frequency of 100 MHz or over and is integrally formed with the vibration section of the crystal raw thin plate and the reinforcement section made of the crystal raw thick plate surrounding the surrounding part of the vibration section. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a small high-frequency vibrator that belongs to a crystal device and mainly performs an AT-cut fundamental-wave thickness-slip vibration of 100 MHz or more and is used for a crystal oscillator mainly used in a transmission system device in the communication field.
[0002]
[Prior art]
In the case of a vibrator that performs an AT-cut fundamental wave thickness-slip vibration with a frequency of 100 MHz or more, in which a vibrating portion of a conventional quartz thin plate and a reinforcing portion of a thick quartz plate surrounding the periphery are integrally formed, In order to avoid the generation of unnecessary spurious vibrations, it is common to adopt a shape in which the size of the vibrating surface is made as large as possible, as shown in FIG. 5, for example, as shown in FIG.
[0003]
On the other hand, in recent trends, there has been a demand for a reduction in size and height as well as a reduction in weight and a reduction in price from a very rapid market for components mounted on a transmission system device in the communication field as a core.
[0004]
[Problems to be solved by the invention]
However, since the vibrating part of the vibrator is a thin plate, it is easily affected by slight mechanical distortion around the vibrating part of the vibrator, and the mechanical distortion changes the thickness of the thin plate of the vibrating part. As a result, there has been a problem that many unnecessary spurious vibrations other than the main vibration are generated.
[0005]
In addition, in order to avoid the influence of mechanical strain applied to the thin plate-shaped vibrating portion, conventionally, the thin plate-shaped vibrating portion needs to have a distance of at least 1 mm or more from the supporting portion of the vibrator. There is a problem that the size reduction of the whole vibrator element plate is significantly restricted.
[0006]
The present invention has been made under the above-mentioned technical background, and accordingly, the object thereof is to provide a vibrating portion of a thin quartz plate and a reinforcing portion of a thick quartz plate surrounding the vibrating portion. An object of the present invention is to provide a small-sized high-frequency vibrator capable of obtaining a stable desired main vibration without generation of spurious in a vibrator having an AT-cut fundamental wave thickness-slip vibration having a frequency of 100 MHz or more and having an integrated shape. .
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides an AT-cut fundamental wave thickness-slip vibration having a frequency of 100 MHz or more, in which a vibrating portion of a thin quartz plate and a reinforcing portion of a thick quartz plate surrounding the vibrating portion are integrated. Wherein the energy confinement coefficient of the vibrator is 3.5 or more, and the vibrating surface length is 1.4 to 2.0 times the electrode surface length of the vibrator. I do.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below with reference to the drawings.
Note that the same reference numerals in each drawing indicate the same objects.
[0009]
FIG. 1 is a schematic sectional view of a small high-frequency vibrator according to the present invention. As shown in FIG. 1, the vibrating surface 6 of the vibrator 3 is in a direction parallel to the X axis or Z ′ axis of the crystal and perpendicular to the Y ′ axis. FIG. 1 shows a connection electrode 7 for outputting a vibration frequency to the outside.
[0010]
FIG. 2 is a schematic cross-sectional view of the small high-frequency vibrator according to the present invention as viewed from the Z′-axis direction. In FIG. 2, only the vibration surface electrode 8 is shown, and the connection electrode 7 for outputting the vibration frequency to the outside is omitted.
[0011]
FIG. 3 is a schematic sectional view of the small high-frequency vibrator according to the present invention as viewed from the X-axis direction. In FIG. 3, only the vibration surface electrode 8 is shown, and the connection electrode 7 for outputting the vibration frequency to the outside is omitted.
[0012]
FIG. 5 is a schematic sectional view of a conventional small high-frequency vibrator. In FIG. 5, only the vibration surface electrode 9 is shown, and the connection electrode 7 for outputting the vibration frequency to the outside is omitted. As shown in FIG. 5, in the conventional fundamental thickness-shear vibration of 100 MHz or more, the vibrating surface 6 is affected by the end surface 12 of the quartz crystal plate 11 by making the vibrating surface length 5 larger than the electrode surface length 4. This prevents spurious emissions.
FIG. 6 is a schematic perspective view of a conventional small high-frequency vibrator. Note that, in FIG. 6, the X axis and the Z ′ axis may be interchanged as in FIG.
[0013]
Conventionally, the following equation is known as an equation of the energy confinement coefficient.
Energy confinement factor = (Δ ^1/2 ) ×  (L / H)
Here, Δ is the plate back amount, L is the electrode surface length 4 of the vibrator, and H is the thickness of the vibrating portion of the quartz crystal plate 11.
Here, the plate back amount is a change amount of the frequency of the quartz crystal plate, and therefore, the plate back amount is expressed as follows.
Amount of plate back Δ = (frequency determined by quartz plate thickness−frequency when vibrator electrode is attached to quartz plate) / frequency determined by quartz plate thickness
FIG. 4 is a diagram showing a normalized displacement distribution of the vibration mode in the present invention. In FIG. 4, the solid line indicates the main vibration mode (S0), and the dotted line indicates the harmonic mode (S1). As shown in FIG. 4, when the vibration surface length 5 is 1.4 times or more the electrode surface length 4 and the normalized displacement of the main vibration mode (S0) is 0.1 or less, and when the vibration surface length is 2.0 times, the main vibration mode It can be seen that the normalized displacement becomes substantially zero not only for (S0) but also for the third harmonic mode (S1).
[0015]
According to the energy confinement effect, the inventor increased the vibration surface length 5 from 1.4 to 2.0 times the electrode surface length 4 of the vibrator when the above-described energy confinement coefficient was 3.5 or more as shown in FIG. In this case, not only the main vibration and the main vibration shown in FIG. 4 but also the vibration displacement of the higher harmonic modes up to the fourth order are sufficiently attenuated. As a result, even if the vibration surface length 5 is reduced, unnecessary spurious It has been found that generation can be avoided and the influence of the end face 12 of the vibrating surface 6 can be made very small, and the present invention has been created.
【The invention's effect】
[0016]
According to the present invention, it is possible to obtain a small-sized high-frequency vibrator having a reduced vibration surface length having a frequency of 100 MHz or more.
[0017]
Further, according to the present invention, unnecessary spurious generation due to the influence of the end face of the vibrating surface is eliminated, and as a result, the yield of the vibrator is remarkably improved, and the manufacturing cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view of a small high-frequency vibrator according to the present invention.
FIG. 2 is a schematic cross-sectional view of a small high-frequency vibrator viewed from a Z′-axis direction according to the present invention.
FIG. 3 is a schematic cross-sectional view of a small high-frequency vibrator viewed from the X-axis direction according to the present invention.
FIG. 4 is a diagram showing a normalized displacement distribution of a vibration mode when the confinement coefficient is 3.5 in the present invention.
FIG. 5 is a schematic sectional view of a conventional small high-frequency vibrator.
FIG. 6 is a schematic perspective view of a conventional small high-frequency vibrator.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Vibration part of thin quartz plate 2 Reinforcement part of thick quartz plate 3 Vibrator 4 Electrode surface length 5 Vibration surface length 6 Vibration surface

Claims (1)

Energy confinement coefficient of vibrator for AT-cut fundamental wave thickness-slip vibration with frequency 100MHz or more, in which vibrating part of thin quartz plate and reinforcing part of thick quartz plate surrounding it are integrated Is 3.5 or more, and the vibrating surface length is 1.4 to 2.0 times the electrode surface length of the vibrator.

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