JP3330102B2 - 3rd overtone type piezoelectric oscillator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tertiary overtone piezoelectric oscillator of an energy trap type applied to a resonator, a filter and the like.

[0002]

2. Description of the Related Art Conventionally, an energy trap type piezoelectric oscillator used for a resonator or a filter has a frequency of several MHz.
Used in the frequency band from to several tens of MHz.

For example, a tertiary overtone type piezoelectric oscillator of thickness longitudinal vibration used for a resonator or the like has a structure in which a vibration electrode is provided on a part of a single piezoelectric substrate polarized in the thickness direction. In addition, an AC electric field is applied in the same direction as the polarization direction to utilize the vibration in the thickness direction.

[0004] That is, conventionally, the thickness longitudinal vibration 3
The next overtone type piezoelectric oscillator has a vibrating electrode formed on a part of the opposing surface of a single piezoelectric substrate, and a vibrating portion of a third harmonic sandwiched between a pair of opposing vibrating electrodes; And the non-vibration part of

In such a third overtone type piezoelectric oscillator, the vibration caused by the third harmonic excited by applying an AC electric field to a pair of vibrating electrodes is confined in a vibrating portion between the vibrating electrodes. .

When a piezoelectric oscillator is used as a resonator for a reference signal oscillator of a microcomputer, it is used by being incorporated in, for example, a Colpitts oscillation circuit. FIG. 6 shows a Colpitts-type oscillation circuit. The Colpitts-type oscillation circuit includes capacitors 11 and 12, a resistor 13, an inverter 14, and an oscillator 15. Then, in order to generate an oscillation signal in the Colpitts oscillation circuit, it is necessary to satisfy the following oscillation conditions in relation to the loop gain and the phase shift amount.

The amplification factor in the amplifier circuit consisting of the resistor 13 and the inverter 14 is α, the phase shift amount is θ ₁ , the feedback ratio in the feedback circuit consisting of the oscillator 15 and the capacitors 11 and 12 is β, and the phase shift amount is When θ ₂ , the loop gain is α × β ≧ 1, and the phase shift amount is θ ₁ + θ ₂ = 360
Degree × n (where n = 1, 2, 3,...).

Here, the feedback ratio β is determined by the resonance impedance R ₀ and the anti-resonance impedance R
It is determined by the P / V value represented by _a.

Then, in the Colpitts type oscillation circuit,
In order to obtain stable oscillation with the third harmonic oscillation, the loop gain in the third harmonic oscillation must be larger than that in the fundamental oscillation. In particular, since the amplification factor α of the inverter decreases as the frequency increases, the P / V value for determining the gain of the feedback ratio β
The P / V value of the third harmonic vibration must be sufficiently larger than the value, and it is important to make the third harmonic vibration larger than the fundamental vibration as the loop gain.

Furthermore, in order to satisfy the condition of the amount of phase shift, it is important that there is no phase shift distortion due to spurious generation between and near the resonance frequency Fr and the anti-resonance frequency Fa in the third harmonic oscillation. In addition, it is important that spurious components are not superimposed near the resonance frequency Fr and the anti-resonance frequency Fa to reduce the P / V value.

Although the third harmonic is effectively confined in the vibrating portion, the fundamental wave is likely to leak out of the vibrating portion, and a plurality of standing waves on which the spurious vibrations are superimposed form an end face of the piezoelectric substrate. When the fundamental wave is generated in the non-vibrating portion of the plurality of standing waves, the P / V value of the fundamental wave is increased in the vibrating portion, and the fundamental wave is increased. Because of the problem of oscillation by waves, it is important to prevent oscillation by fundamental waves.

In order to prevent such oscillation due to the fundamental wave, conventionally, the P / V value of the fundamental wave has been reduced by optimizing the shape of the piezoelectric substrate and the dimensions of the electrodes. Further, as a method for positively reducing the P / V value of the fundamental wave, as disclosed in Japanese Patent Application Laid-Open No. H10-65480, an adhesive is applied to both sides of the piezoelectric substrate to areas other than the vibrating electrodes. The sealing substrate is fixed via the adhesive to reduce the P / V value of the fundamental wave.

Here, the fundamental wave vibration means an essential fundamental wave vibration (a frequency corresponding to one third of the frequency of the third harmonic vibration) near the frequency at which the fundamental wave vibration is formed. And spurious vibration are superimposed, and a plurality of vibration waveforms and P
/ V is formed. The vibration that forms the largest P / V value among them will be referred to as fundamental wave vibration. For example, FIG.
Since the impedance waveform indicated by L in the frequency band near the fundamental wave oscillation shown in (1) has a large P / V value and undergoes a phase shift and satisfies the oscillation conditions, there is a possibility of abnormal oscillation oscillating with the fundamental wave. . The vibration that forms the impedance waveform of L is abbreviated as fundamental wave vibration.

[0014]

However, in the conventional energy trapping type oscillator using the third harmonic oscillation, even if the shape of the piezoelectric substrate and the dimensions of the electrodes are optimized, the third harmonic oscillation can be prevented. Combined with an inverter that can secure only a difference of about 15 to 20 dB between the P / V value and the P / V value of the fundamental wave oscillation, and the gain of the amplification factor α decreases steeply as the frequency increases. Sometimes,
The fundamental wave has a loop gain larger than the third harmonic, and there is a problem of abnormal oscillation oscillating by the fundamental wave.

Further, as disclosed in Japanese Patent Application Laid-Open No. 10-65480, when a sealing substrate is fixed to an outer peripheral region other than the vibrating electrodes on both surfaces of a piezoelectric substrate using an adhesive made of an organic resin, Although the P / V value of the fundamental wave is reduced, since the organic resin is formed on the outer peripheral portion other than the vibrating electrode, there is a limit in reducing the size and size of the piezoelectric substrate, particularly in reducing the width.

Furthermore, since the sealing substrate is bonded by using an adhesive made of an organic polymer material to secure the sealing property, it is exposed to a wide temperature range from -40.degree. C. to + 150.degree. In this case, the piezoelectric substrate, the sealing substrate, and the organic polymer material formed between them have different linear expansion coefficients, and stress concentrates on the organic polymer material. There were problems such as peeling of the adhesive, loss of sealing properties, and an increase in the P / V value of the fundamental wave.

According to the present invention, the size and size of the piezoelectric substrate can be reduced, and particularly, the size in the width direction can be reduced.
It is an object of the present invention to provide a tertiary overtone type piezoelectric resonator which has high reliability even in use in a wide temperature range from ℃ to + 150 ° C., can suppress the P / V value of fundamental wave oscillation, and can obtain stable oscillation. Aim.

[0018]

A tertiary overtone type piezoelectric oscillator according to the present invention comprises: a piezoelectric substrate having both rectangular main surfaces;
A pair of opposing vibrating electrodes formed at the center of both main surfaces of the piezoelectric substrate, electrically connected to the vibrating electrodes, and drawn out toward short sides of both main surfaces of the piezoelectric substrate, respectively. A tertiary overtone type piezoelectric oscillator including an extraction electrode, wherein the length of the short side of the main surface of the piezoelectric substrate is W, and the length of the vibrating electrode in the short side direction of the piezoelectric substrate is B. , with satisfying 0.5 ≦ B / W ≦ 0.9, and the vibrating electrode, between the opposite side of the short side and the extraction direction of the extraction electrode on the main surface of the piezoelectric substrate, Yan
Density in an organic polymer material of 7 × 10 ¹⁰ Pa or less
Contains 20 to 60% by weight of Ag of 5 g / cm ³ or more.
A fundamental wave vibration suppressor is provided.

Here, between the vibrating electrode and a short side of the main surface of the piezoelectric substrate opposite to the drawing direction of the drawing electrode,
There are a plurality of abdominal parts of the fundamental wave at predetermined intervals,
It is preferable that a fundamental wave vibration suppressor is provided at least on the abdomen of the fundamental wave.

The distance between the vibrating electrode and the short side of the main surface of the piezoelectric substrate opposite to the direction in which the extraction electrode is pulled out is represented by x.
, The fundamental wave vibration suppressor moves x /
It is desirable to form it centering on the part 3 distance | distance.

[0021]

[0022]

In the tertiary overtone type piezoelectric oscillator, if the size of the piezoelectric substrate in the width direction is reduced to achieve miniaturization,
Although the second harmonic is effectively confined in the vibrating portion between the vibrating electrodes, the fundamental wave is drawn out of the vibrating portion in the longitudinal direction of the rectangular main surface of the piezoelectric substrate, that is, on the main surface of the piezoelectric substrate. It is easy to leak toward the short side opposite to the direction in which the electrodes are pulled out, and it is easy to form a standing wave at this portion. However, in the tertiary overtone type piezoelectric oscillator of the present invention, the vibration electrode and the piezoelectric substrate The fundamental wave vibration suppressor is provided between the rectangular main surface and the short side opposite to the extraction direction of the extraction electrode, so that the short side opposite to the extraction direction of the extraction electrode on the main surface of the piezoelectric substrate and the vibration The vibration of the fundamental wave between the electrode and the electrode can be suppressed, whereby the vibration of the fundamental wave in a portion other than the vibrating portion can be suppressed, and the P / V value of the third harmonic vibration can be increased. While maintaining the P / V value of the fundamental vibration It can be reduced to the width.

When the length of the short side of the main surface of the piezoelectric substrate is W and the length of the vibrating electrode in the short side direction of the piezoelectric substrate is B, 0.5 ≦ B / W ≦ 0.9 is satisfied. As a result, the width of the piezoelectric substrate can be reduced to reduce its size, and the third harmonic vibration is effectively confined in the vibrating electrode. Therefore, the spurious between the resonance of the third harmonic vibration and the anti-resonance frequency and in the vicinity thereof is reduced. This can increase the P / V value of the third harmonic.

Further, between the vibrating electrode and a short side of the main surface of the piezoelectric substrate opposite to the drawing direction of the drawing electrode,
There are a plurality of abdominal parts of the fundamental wave at predetermined intervals,
By providing the fundamental wave vibration suppressor at least in a portion where the antinode of the fundamental wave exists, the fundamental wave vibration in the non-vibrating portion can be effectively suppressed, and the P / V value of the third harmonic vibration can be increased. With the value maintained, the P / V value of the fundamental wave vibration can be further reduced.

The distance between the vibrating electrode and the short side of the main surface of the piezoelectric substrate opposite to the direction in which the extraction electrode is pulled out is represented by x.
In this case, by forming the fundamental-wave vibration suppressor around a portion at a distance of x / 3 from the vibrating electrode, the fundamental-wave vibration in the non-vibrating portion can be effectively suppressed.

Further, the fundamental wave vibration suppressor is prepared by adding Ag having a density of 5 g / cm ³ or more to
By configuring so as to contain 60% by weight, the fundamental vibration in the non-vibrating portion can be more effectively suppressed.

The organic polymer material has a Young's modulus of 7 × 1
By setting the pressure to 0 ¹⁰ Pa or less, the damping effect of the fundamental wave vibration is enhanced, the P / V value of the fundamental wave vibration is greatly reduced, and the difference is caused by the difference in linear expansion coefficient between the piezoelectric substrate and the organic polymer material. The stress can be relieved by the deformation of the organic polymer material, and the fundamental wave vibration suppressor does not peel off even after a heat cycle in a wide temperature range from −40 ° C. to + 150 ° C., so that reliability can be secured.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A tertiary overtone type piezoelectric oscillator according to the present invention has a piezoelectric substrate 1 having rectangular main surfaces as shown in FIG. The vibrating electrode includes a pair of opposing vibrating electrodes 2 and 3 and extraction electrodes 4 and 5 electrically connected to the vibrating electrodes 2 and 3, respectively.

The extraction electrodes 4 and 5 are extracted in the side direction (toward the short side of the piezoelectric substrate 1) facing the longitudinal direction of the piezoelectric substrate 1, respectively. A pair of opposed vibrating electrodes 2,
The portion sandwiched by 3 is the vibrating portion 7 of the third harmonic vibration,
The other part is the non-vibration part 8 of the third harmonic vibration,
The energy of the third harmonic vibration is confined in the vibration section 7.

In the piezoelectric oscillator of the present invention, when the length of the short side of the main surface of the piezoelectric substrate 1 is W and the length of the vibrating electrodes 2 and 3 in the short side direction of the piezoelectric substrate 1 is B, 0 .5 ≦ B /
W ≦ 0.9 is satisfied. That is, the width dimension of the piezoelectric substrate 1 is smaller than that of the related art. It is desirable that the length W of the short side of the piezoelectric substrate 1 is 1.5 mm or less. This is because miniaturization cannot be achieved if the length W of the short side is larger than 1.5 mm. When B / W is smaller than 0.5, spurious is generated between the resonance frequency Fr of the third harmonic vibration and the anti-resonance frequency Fa, and the P / V value of the third harmonic vibration is small. This is because if B / W is larger than 0.9, spurious is generated between the resonance frequency Fr of the third harmonic oscillation and the anti-resonance frequency Fa. B / W is 0.7 ≦ B / W ≦
It is desirable to satisfy 0.9.

A fundamental-wave vibration suppressor 9 is provided between the vibration electrodes 2 and 3 and the short side A of the rectangular main surface of the piezoelectric substrate 1 opposite to the direction in which the extraction electrodes 4 and 5 are extracted. ing. That is, the fundamental wave vibration suppressor 9 is adhered to a region on one main surface of the piezoelectric substrate 1 which becomes the non-vibration portion 8 of the third harmonic vibration.
And has the same length as the width of the rectangle.

Further, a plurality of fundamental waves are provided at predetermined intervals between the vibrating electrodes 2 and 3 and a short side A of the rectangular main surface of the piezoelectric substrate 1 opposite to the direction in which the extraction electrodes 4 and 5 are extracted. The fundamental wave vibration suppressor 9 is provided at least in a portion where the abdomen of the fundamental wave exists.
In other words, the fundamental wave vibration suppressor 9 is formed so as to cover the vibration distribution of the fundamental wave vibration in the region that becomes the non-vibrating portion 8 of the third harmonic vibration.

In this example, the vibrating electrodes 2 and 3
Assuming that the distance between the drawing electrode 4 and the drawing side of the rectangular main surface of the piezoelectric substrate 1 and the short side A on the side opposite to the drawing direction is x, the fundamental wave vibration suppressor 9 moves x / 3 from the vibration electrodes 2 and 3. Are formed around the portion at a distance of.

That is, the fundamental wave vibration of the third harmonic vibration vibration energy trapping type oscillator operating at the oscillation frequency of 33.86 MHz is shown in FIG. 2 (the vibration distribution forming the largest P / V of the fundamental wave vibration). As shown in the FEM analysis diagram: 1/4 upper cross section, the non-vibration part 8 of the third harmonic vibration
It can be seen that a standing wave is formed in the region of. FIG.
In the figure, the portion of the vibrating electrode 2 is shown by hatching.

When the distance between the vibrating electrodes 2 and 3 and the short side A of the piezoelectric substrate 1 is x, the standing wave has an antinode of the fundamental wave at the boundary between the vibrating electrodes 2 and 3 and the non-vibrating part 8 ( x = 0), formed at a portion at a distance of x / 3 from the vibrating electrodes 2, 3 and at a portion at a distance of 2x / 3 from the vibrating electrodes 2, 3; It occurs only in the portion at a distance of x / 3 from 3.

By forming the fundamental wave vibration suppressor 9 on the upper part, the fundamental wave vibration in the non-vibrating portion 8 is suppressed, and the P / V of the fundamental wave vibration between the vibrating electrodes 2 and 3 is thereby reduced.
The value can be greatly reduced. Note that the fundamental wave vibration suppressor 9 does not need to be formed on the entire surface of the piezoelectric substrate 1 in the width direction. Even if it is formed on the portion of the non-vibrating portion 8 where the fundamental wave vibration occurs most, the effect is large.

Such a fundamental wave vibration suppressor 9 comprises two or more powder particles having a density of 5 g / cm ³ or more in an organic polymer material.
It is comprised containing 0-60 weight%. The Young's modulus of the organic polymer material in a state not containing powder particles is 1 × 10
^{It is set to 11} Pa or less.

20 powder particles having a density of 5 g / cm ³ or more
The weight percent or more contained in the organic polymer material is such that the larger the mass of the fundamental wave vibration suppressor 9 formed in the abdomen of the fundamental wave, the greater the damping effect of the fundamental wave vibration, This is because the P / V value of the wave vibration can be reduced.

When the density is 5 g / cm ³ or more, 20
The reason that the content is not less than 5% by weight is that when the density is less than 5 g / cm ³ and the powder particles are less than 20% by weight, the fundamental wave P /
This is because the effect of suppressing the V value cannot be obtained, and the shape becomes larger in the thickness direction.

Preferably, when 40 to 60% by weight of powder particles having a density of 10 g / cm ³ or more is contained, about 20 to 30%
Since the P / V value of the fundamental wave vibration can be remarkably reduced by the fundamental wave vibration suppressor 9 made of a thick film of μm, it is possible to cope with a single screen printing, and it is excellent in productivity and small in the thickness direction. Can be achieved.

Silver is used as the powder particles having a density of 5 g / cm ³ or more .

The Young's modulus of the organic polymer material is 7 × 1
The reason for setting it to 0 ¹⁰ Pa or less is that the Young's modulus is 7 × 10 ¹⁰ Pa
This is because, when the value exceeds 3, the damping effect of the fundamental vibration becomes small, and the P / V of the third harmonic vibration is also reduced. Further, the effect of relaxing the stress generated by the difference in linear expansion coefficient between the piezoelectric substrate and the organic polymer material by the deformation of the organic polymer material is reduced, and
This is because, in a heat cycle in which the temperature is repeatedly changed from a low temperature of 150 ° C. to a high temperature of 150 ° C., cracks occur in the resin or the resin peels off from the piezoelectric substrate, and the effect of reducing the P / V value of the fundamental wave vibration is lost.

As the organic polymer material, an epoxy resin, a silicon resin, an acrylic resin, a urethane resin or the like is used.

The piezoelectric substrate 1 is, for example, a piezoelectric ceramic substrate. Specifically, the substrate is mainly composed of lead titanate (PT), and at least a part of Pb of lead titanate PbTiO ₃ is replaced by La. In addition, the main component is an ABO ₃ -type perovskite-type composite oxide in which at least a part of Ti is replaced by Mn, and the number of moles of Pb per mole of the B-site constituent element is a, and the A-site constituent elements other than Pb When the total number of moles of the element is b, a / (1-
The value (p) represented by b) is 0.92 to 0.99,
In addition, a part of Pb is replaced by at least one of Sr, Ba and Ca, and a part of Ti is replaced by (Fe _1/3 S).
b _2/3 ), (Co _1/3 Sb _2/3 ), (Y _1/2 S
b _1/2 ), (Yb _1/2 Sb _1/2 ), (In _1/2 S
b _1/2 ) and (Mg _1/3 Sb _2/3 ).

The vibrating electrodes 2 and 3 and the extraction electrodes 4 and 5 are formed by depositing metals such as Cr, Ag, Cu, Pt, Ni, and Au alone, or by combining them and depositing them sequentially by vapor deposition or sputtering. ing.

In the tertiary overtone type piezoelectric oscillator configured as described above, since the fundamental wave vibration suppressor 9 is provided between the vibration electrodes 2 and 3 and the short side A, the short side A and the vibration electrode Vibration of the fundamental wave between the second and third vibrations can be suppressed, thereby suppressing the vibration of the fundamental wave in the vibrating section, and maintaining the P / V value of the third harmonic vibration at a high value. In this state, the P / V value of the fundamental wave vibration can be significantly reduced.

In particular, by forming the fundamental-wave vibration suppressor 9 around a portion at a distance of x / 3 from the vibrating electrodes 2 and 3, the above effect is enhanced. The fundamental wave vibration suppressor 9 has a density of 5 g / c in the organic polymer material.
By configuring m ³ or more powder particles contain 20 to 60 wt%, further, the Young's modulus of the organic polymer material 1
By setting the pressure to 10 ¹¹ Pa or less, the above effect is further enhanced.

The short side A of the rectangular main surface of the piezoelectric substrate 1
When the length of the piezoelectric substrate 1 is W and the length of the vibrating electrodes 2 and 3 in the short side direction of the piezoelectric substrate 1 is B, 0.5 ≦ B / W ≦ 0.9 is satisfied. To reduce the size and to effectively confine the third harmonic vibration between the vibrating electrodes, preventing spurious between and near the resonance of the third harmonic vibration and the anti-resonance frequency and the third harmonic The P / V value of the wave can be increased.

In the above example, the fundamental wave vibration suppressor 9 has a rectangular shape. However, in the present invention, the shape of the fundamental wave vibration suppressor 9 is not particularly limited. Although the fundamental wave vibration suppressor 9 containing the powder particles is formed on one of the surfaces, it may be formed on both main surfaces. Further, although the fundamental wave vibration suppressor 9 is constituted by containing powder particles having a density of 5 g / cm ³ or more, a certain effect can be obtained without containing the powder particles.

[0050]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the dimensions are (long side 2.8 mm, short side W0.
5 to 1.1 mm, thickness 0.22 mm), and (Pb
_0.85 ) _0.97 La _0.1 Sr _0.05 (Co _1/3 Sb _2/3 ) _0.01
A piezoelectric substrate 1 made of (Yb _1/2 Sb _1/2 ) _0.01 Mn _0.02 Ti _0.96 O ₃ was produced.

Cr and Ag were sequentially deposited on both main surfaces of the piezoelectric substrate 1 and polarized at a temperature of 80 ° C. and 2 kV DC for 15 minutes. Then, the dimensions of the electrodes for simultaneously forming the extraction electrodes 4 and 5 electrically connected to the vibration electrodes 2 and 3 are changed, and a resist is printed on a rectangular portion corresponding to the electrodes, and the vibration electrodes and 33. After removing by etching so as to leave a portion serving as an extraction electrode, the resist is removed.
An energy-trap ceramic oscillator using a third harmonic vibration of a thickness longitudinal vibration corresponding to an oscillation frequency of 86 MHz was obtained.

Further, on the main surface of the piezoelectric substrate 1, an organic polymer material composed of an epoxy resin having a Young's modulus as shown in Table 1 and containing a predetermined amount of powder particles as shown in Table 1 is used. X / 3 from the vibrating electrode at the thickness shown in Table 1.
To the distant portions, the same length W as the short side and the width of 1.2 mm were applied, and ten piezoelectric oscillators each having the fundamental wave vibration suppressor 9 as shown in FIG. 1 were produced. The Young's modulus of the epoxy resin was changed by compounding a resin having a low Young's modulus.

Regarding the characteristics of the piezoelectric oscillator, the presence / absence of spurious was confirmed based on the impedance characteristics at the third harmonic oscillation, and the oscillation characteristics were evaluated.

Further, after a heat cycle test in which the temperature was repeated 500 times from −40 ° C. to + 150 ° C., 3
The difference between the P / V value of the third harmonic vibration and the P / V value of the fundamental vibration was calculated by examining the P / V value of the third harmonic vibration and the P / V value of the fundamental vibration. All samples are 3
0 dB or more.

As for the impedance characteristics, impedance waveforms (resonance impedance Ra, anti-resonance impedance Ro) and phase shift of fundamental vibration and third harmonic vibration were measured by an impedance analyzer.

The oscillation characteristics were measured using the inverter oscillation circuit shown in FIG. P / V value is P / V = 20lo
g (Ra / Ro). These results are shown in Table 2. In addition, sample No. 8 and 9 show reference samples
You.

[0057]

[Table 1]

[0058]

[Table 2]

From Tables 1 and 2, the piezoelectric oscillator of the present invention increases the P / V value of the third harmonic vibration to 55 dB or more, and the resonance frequency fr and the antiresonance frequency fa of the third harmonic vibration. There is no spurious between and near it, and the difference between the P / V value of the third harmonic oscillation and the P / V value of the fundamental oscillation can be 30 dB or more.

Sample No. FIG. 3 shows the impedance characteristics of the third harmonic oscillation of the twelve energy trap type oscillators.
FIG. 4 shows the impedance characteristic of the fundamental wave vibration. In FIG. 4 showing the impedance characteristics of the fundamental wave vibration, it can be seen that even the fundamental wave vibration of P which forms the largest P / V value is sufficiently small at 26 dB. Furthermore, a difference of 39 dB between the P / V value of the fundamental vibration and the P / V value of the third harmonic vibration was secured, and no oscillation was caused by the fundamental wave.

Further, the sample No. 14 shows a case where the fundamental wave vibration suppressor was not formed, and the impedance of the fundamental wave vibration is shown in FIG. 5. The P / V value of the fundamental wave vibration L was large, and the fundamental wave oscillated.

[0062]

According to the third overtone type piezoelectric oscillator of the present invention, the vibration of the fundamental wave between the vibrating electrode and the short side of the rectangular main surface of the piezoelectric substrate opposite to the extraction direction of the extraction electrode is suppressed. Accordingly, the fundamental vibration in the non-vibrating portion can be suppressed, and the third harmonic vibration P
/ V value is maintained at a high value, and the P / V
When the length of the short side of the rectangular main surface of the piezoelectric substrate is W and the length of the vibrating electrode in the short side direction of the piezoelectric substrate is B, 0.5 ≦ B / W
In order to satisfy ≦ 0.9, it is possible to reduce the width of the piezoelectric substrate to reduce its size, and to prevent spurious between and near the resonance and anti-resonance frequency of the third harmonic vibration,
The P / V value of the third harmonic can be increased.

[Brief description of the drawings]

FIGS. 1A and 1B show a tertiary overtone type piezoelectric oscillator of the present invention, wherein FIG. 1A is a perspective view and FIG. 1B is a side view.

FIG. 2 is a diagram showing a vibration displacement distribution diagram by FEM simulation of fundamental wave vibration, which is viewed from an upper surface of a piezoelectric substrate;
It is a / 4 cut model figure.

FIG. 12 shows the impedance characteristic of the twelfth harmonic vibration.

FIG. 12 shows impedance characteristics of twelve fundamental vibrations.

FIG. 14 shows the impedance characteristic of the fundamental wave vibration of No. 14.

FIG. 6 is a schematic diagram showing a Colpitts type oscillation circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Piezoelectric substrate 2, 3 ... Vibration electrode 4, 5 ... Extraction electrode 9 ... Fundamental wave vibration suppressor

Claims (3)

(57) [Claims] 1. A piezoelectric substrate having both rectangular main surfaces, a pair of opposing vibration electrodes formed at the center of both main surfaces of the piezoelectric substrate, and electrically connected to the vibration electrodes; A tertiary overtone type piezoelectric oscillator comprising: a lead electrode which is drawn out toward a short side on both main surfaces of the piezoelectric substrate, wherein the length of the short side of the main surface of the piezoelectric substrate is W; When the length of the vibrating electrode in the short side direction of the substrate is B, 0.5 ≦ B / W ≦ 0.9 is satisfied, and the vibrating electrode and the extraction electrode on the main surface of the piezoelectric substrate are drawn out. The Young's modulus is 7 between the direction and the opposite short side.
In an organic polymer material of × 10 ¹⁰ Pa or less, a density of 5 g /
A tertiary overtone type piezoelectric vibrator comprising a fundamental wave vibration suppressor containing 20 to 60% by weight of Ag of at least ³ cm ³ . 2. A plurality of antinodes of a fundamental wave are present at a predetermined interval between the vibrating electrode and a short side of the main surface of the piezoelectric substrate opposite to a direction in which the extraction electrode is pulled out. 3. The tertiary overtone type piezoelectric oscillator according to claim 1, wherein a vibration suppressor is provided at least on an antinode of the fundamental wave. 3. When the distance between the vibrating electrode and a short side of the main surface of the piezoelectric substrate opposite to the drawing direction of the drawing electrode is x, the fundamental wave vibration suppressor is at a distance of x / 3 from the vibrating electrode. 3. The tertiary overtone type piezoelectric oscillator according to claim 1, wherein the tertiary overtone type piezoelectric oscillator is formed around a portion at a distance.