JP2005039768A - Quartz crystal resonator, quartz crystal unit, and quartz crystal oscillator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a miniature tuning fork quartz crystal resonator capable of vibrating in a flexural mode and having high stability at a frequency for a fundamental mode of vibration, a small equivalent series resistance R<SB>1</SB>and a high quality factor Q, and to provide a quartz crystal unit configured to include the quartz crystal resonator, and a quartz crystal oscillator for providing an output signal with a highly stable oscillation frequency. <P>SOLUTION: The tuning fork bent quartz crystal resonator having three electrode terminals comprises tuning fork arms; and a tuning fork base, each tuning fork arm having a groove at least on one of its upper and lower faces, electrodes being deposited to the side of the grooves and the side of each tuning fork arm, at least one of them acting like an earth electrode. Moreover, the quartz crystal oscillator is realized wherein the bent quartz crystal resonator configures the quartz crystal unit, the figure of merit in a fundamental mode of vibration is greater than the figure of merit in a second overtone mode of vibration, and the output signal from the quartz crystal oscillator has the oscillation frequency in the fundamental mode of vibration on the basis of a relation between an amplification factor of an amplifier circuit and a feedback factor of a feedback circuit. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a crystal resonator including a vibrating arm and a base that vibrate in a bending mode, a crystal unit including the resonator, a case, and a lid, an amplifier circuit, and a feedback circuit. In particular, crystal units, crystal units, and crystal oscillators that are ideal as reference signal sources for information and communication equipment that are highly demanded for miniaturization, high accuracy, impact resistance, and low cost. New shapes, new electrode configurations, and optimal dimensions. The present invention relates to a crystal unit composed of an ultra-compact bent crystal resonator having a crystal oscillator and a crystal oscillator whose oscillation frequency of fundamental mode vibration is an output signal.

As an example, a conventional bent quartz crystal resonator includes a tuning fork arm and a tuning fork base, and electrodes are disposed on the upper and lower surfaces and side surfaces of the tuning fork arm. That is, the electrodes are arranged so as to constitute a two-electrode terminal. In addition, the conventional crystal unit is composed of a tuning fork-type bending crystal unit composed of a tuning fork arm and a tuning fork base formed integrally with a case and a lid. Further, the crystal oscillator includes an amplifier, a capacitor, a resistor, and upper and lower surfaces of the tuning fork arm. A crystal oscillator composed of a conventional tuning-fork type bent crystal resonator having electrodes arranged on the side surfaces is well known. A conventional tuning fork-type bending crystal resonator that is frequently used is composed of two tuning fork arms and a tuning fork base, and the resonance frequency of the transducer is proportional to the arm width W of the tuning fork and is the square of the length of the tuning fork arm. Inversely proportional. Therefore, it is necessary to reduce the arm width W in order to reduce the size. However, reducing the arm width W, a problem that the equivalent series resistance R ₁ becomes larger it had been left. Further, downsizing of the crystal unit and the crystal oscillator of the conventional example including the tuning-fork type bent crystal resonator has been left as a problem at the same time.

The reason why R ₁ increases is that the equivalent series resistance R ₁ decreases as the electric field component Ex of the electrode disposed on the tuning fork arm in the direction of the electric axis (x-axis) of the crystal increases, and the quality factor Q value increases. . However, in the tuning fork-type bent quartz crystal resonator that has been conventionally used, electrodes are arranged on the upper and lower surfaces and side surfaces of each tuning fork arm. For this reason, the electric field does not work linearly, and when the tuning fork type quartz crystal resonator is miniaturized, the electric field component Ex is reduced, the equivalent series resistance R ₁ is increased, and the quality factor Q value is decreased. At the same time, there remains a problem of obtaining a bent crystal resonator that is highly accurate as a time reference, that is, has high frequency stability and suppresses second harmonic mode vibration. As a method for solving the above-mentioned problem, for example, JP-A-56-65517 discloses a groove on a tuning fork arm, and discloses a groove structure and an electrode structure. However, the electrode structure of three-electrode terminal made of ground electrodes, the configuration of the groove, the relationship between the equivalent series resistance R ₂ of the equivalent series resistance R ₁ of the second harmonic mode vibration in the vibration mode and fundamental mode vibration and dimension In addition, there is no disclosure of the finger of merit M related to frequency stability. At the same time, when the vibrator having the groove is connected to a conventional circuit to form a crystal oscillation circuit, the output signal of the fundamental mode vibration is affected by the impact or vibration, and the output signal is the second harmonic mode vibration. Problems such as frequency change and detection have occurred. Furthermore, in order to reduce the current consumption of the crystal oscillator, reducing the load capacitance C _L, liable to vibration second harmonic mode, problems such as not to obtain the output frequency of the fundamental mode oscillation is left It was. Furthermore, when the electrodes arranged on the adjacent vibrating arms are configured with two electrode terminals, there remains a problem that it is difficult to form the electrodes. At the same time, there remains a problem that the overall length of the tuning fork cannot be shortened.
JP-A-56-65517 International Publication No. 00/44092 JP-A-10-153432 JP2003-163568

For this reason, it is easy to configure and connect the electrodes placed on the crystal unit, and to suppress the second harmonic mode vibration that is not affected by the impact or vibration of the crystal unit. There has been a demand for a bent crystal resonator that vibrates in a wave mode, a crystal unit including the same, and a crystal oscillator. Furthermore, short length of the crystal resonator to vibrate in the fundamental mode, i.e., a short ultra-small overall length, a small equivalent series resistance R _1, the new shape, such as the quality factor Q value increases, the electric machine Ultra-compact bent crystal unit with groove structure and electrode configuration with good conversion efficiency, crystal unit equipped with it, and output signal with oscillation frequency of fundamental mode vibration with the crystal unit and high frequency stability An ultra-small crystal oscillator having high performance (high time accuracy) has been desired. At the same time, a crystal oscillator with low current consumption and short rise time has been desired.

  An object of the present invention is to provide a bent crystal resonator that vibrates in a bending mode that advantageously solves the conventional problems by the following method, a crystal unit including the same, and a crystal oscillator.

That is, the first aspect of the crystal resonator according to the present invention is a bending crystal resonator including a vibrating arm that vibrates in a bending mode and a base, and the vibrating arm has an upper surface, a lower surface, and a side surface. In the quartz resonator, a groove is provided on at least one of the upper and lower surfaces, and a ground electrode is disposed on at least one of the side surfaces of the groove or the vibrating arm.
A first aspect of the crystal unit of the present invention is a crystal unit including a crystal resonator, a case, and a lid, and the crystal resonator is a bent crystal resonator including a vibrating arm and a base that vibrate in a bending mode. The vibrating arm has an upper surface, a lower surface, and a side surface, a groove is provided on at least one surface of the upper and lower surfaces of the vibrating arm, and a ground electrode is disposed on at least one surface of the groove or the side surface of the vibrating arm. It is a crystal unit.
According to a second aspect of the crystal unit of the present invention, the crystal unit includes a crystal resonator, a case, and a lid. The crystal resonator includes a vibrating arm and a base that vibrate in a bending mode. in the vibrating arm having an upper surface and a lower surface and side surfaces, have a frame is provided so as to protrude from the base, absolute value 0.095C / m ² of the piezoelectric constant e ₁₂ of the bent crystal oscillator A crystal unit in the range of ˜0.19 C / m ² .
According to a first aspect of the crystal oscillator of the present invention, the amplifier circuit includes an amplifier circuit and a feedback circuit. The amplifier circuit includes an amplifier and a feedback resistor element. The feedback circuit includes a crystal resonator, a capacitor, and a resistor element. A crystal oscillator comprising a crystal oscillation circuit, wherein the crystal resonator is a bending crystal resonator including a vibrating arm and a base that vibrate in a bending mode, and the vibrating arm has an upper surface, a lower surface, and a side surface. In addition, the crystal oscillation circuit is configured by including a bending crystal resonator in which the fundamental wave mode vibration of the bending crystal resonator has a greater Fibber of merit M ₁ than the second harmonic mode vibration of the Fibre of Merit M _2. together, an amplifier circuit absolute value of the negative resistance of the fundamental mode oscillation of the amplifier circuit of the crystal oscillation circuit configured by a feedback circuit | -RL 1 _| and the equivalent series resistance R ₁ of the fundamental mode oscillation Second harmonic mode absolute value of the negative resistance of the oscillation of the ratio amplifier | -RL 2 _| and the crystal oscillator circuit to be greater than the ratio of the equivalent series resistance R ₂ of the second harmonic mode vibration arrangement And a crystal oscillator in which an output signal of the crystal oscillation circuit configured to include the bent crystal resonator has an oscillation frequency of fundamental mode vibration.
According to a second aspect of the crystal oscillator of the present invention, a frame is provided so as to protrude from a base portion of a bent crystal resonator including a vibrating arm and a base portion, and the piezoelectric constant e ₁₂ of the bent crystal resonator is The crystal oscillator according to the first aspect, in which an absolute value is in a range of 0.095 C / m ^{2 to} 0.19 C / m ² .
According to a second aspect of the crystal resonator of the present invention and a third aspect of the crystal unit and the crystal oscillator, the vibrating arm includes a first vibrating arm and a second vibrating arm, and the first vibrating arm and the second vibrating arm 1. The crystal resonator according to the first aspect, wherein one groove is provided on each of the upper and lower surfaces, electrodes are disposed on side surfaces of the groove and the vibrating arm, and the electrodes disposed on the side surfaces are ground electrodes. Or the crystal unit according to the first aspect or the second aspect, or the crystal oscillator according to the first aspect or the second aspect.
According to a third aspect of the crystal resonator of the present invention and a fourth aspect of the crystal unit and the crystal oscillator, the vibrating arm includes a first vibrating arm and a second vibrating arm, and the first vibrating arm and the second vibrating arm The crystal resonator according to the first aspect, wherein one groove is provided on each of upper and lower surfaces, electrodes are disposed on side surfaces of the groove and the vibrating arm, and the electrode disposed in the groove is a ground electrode. Or the crystal unit according to the first aspect or the second aspect, or the crystal oscillator according to the first aspect or the second aspect.

As described above, the present invention provides a bending crystal resonator that vibrates in a bending mode, a crystal unit and a crystal oscillator including the same, and improves the arrangement of the electrodes of the vibrating arms of the bending crystal resonator, thereby reducing the equivalent series resistance. An oscillation frequency in which a bent quartz crystal resonator having a small R ₁ and a high Q value is obtained, and the second harmonic mode vibration is suppressed by showing the relationship between the amplifier circuit and the feedback circuit, and the fundamental mode vibration is vibrated. Can be obtained.

In addition, the grooves provided in the resonating arms, and an electrode made of a three electrode terminals disposed on the vibrating arm, by optimizing the dimensions of the grooves, ultra-small, low equivalent series resistance R _1, Q values A low-priced tuning fork-shaped bent quartz crystal having a high electromechanical conversion efficiency is obtained. At the same time, the load capacity of the feedback circuit can be reduced. As a result, a crystal oscillator with low current consumption can be realized.

  Embodiments of the present invention will be specifically described below with reference to the drawings.

Example 1 bent crystal resonator

  FIGS. 1A and 1B are a top view and a bottom view of a tuning-fork-shaped bent quartz crystal resonator 10 that vibrates in a bending mode according to the first embodiment of the present invention. Also, x, y, and z are the crystal electrical axis, mechanical axis, and optical axis, respectively. The bent crystal resonator 10 according to the present embodiment includes a vibrating arm (tuning fork arm) 11, a vibrating arm (tuning fork arm) 12, and a base 25. One end of the vibrating arm 11 and the vibrating arm 12 is a base (tuning fork base). ) 25. The vibrating arm 11 and the vibrating arm 12 each have an upper surface, a lower surface, and a side surface. A groove 13 is provided on the upper surface of the vibrating arm 11, and a groove 15 is provided on the lower surface. Also, like the vibrating arm 11, grooves 14 and 16 are provided. The angle θ is a rotation angle around the x axis, and is usually selected in the range of 0 to 15 °. In the present embodiment, grooves 13 and 15 are provided so as to sandwich the neutral line of the vibrating arm 11. The other vibrating arm 12 is also provided with grooves 14 and 16 so as to sandwich the neutral line.

  Furthermore, electrodes 17 and 19 are disposed in the grooves 13 and 15 of the vibrating arm 11, and the respective electrodes are connected to the electrodes 17 a and 19 a at the end of the base portion 25. Further, the electrode 17 a and the electrode 19 a are connected via an electrode 17 b on the side surface of the base portion 25. Similarly, electrodes 18 and 20 are disposed in the grooves 14 and 16 of the vibrating arm 12, and the respective electrodes are connected to the electrodes 18 a and 20 a at the end of the base 25. Furthermore, the electrode 18 a and the electrode 20 a are connected via an electrode 18 b on the side surface of the base portion 25. Furthermore, electrodes 21 and 22 are arranged and connected to the side surface of the vibrating arm 11, and electrodes 23 and 24 are arranged and connected to the side surface of the vibrating arm 12, so that the electrodes 22 and 23 have the same polarity. Connected near the tuning fork fork. That is, the electrodes 21, 22, 23, and 24 are connected to have the same polarity.

Ｗ_３となるように形成される。又、溝幅Ｗ_２はＷ_２≧Ｗ_１，Ｗ_３を満足する条件で形成される。更に具体的に述べると、本実施例では、溝幅Ｗ_２と腕幅Ｗとの比（Ｗ_２／Ｗ）が０．３５より大きく、１より小さくなるように、好ましくは、０．３５〜０．９５の範囲内にある。また、図２で示すように、溝の厚みｔ_１と振動腕の厚みｔとの比（ｔ_１／ｔ）が０．７９より小さくなるように（ｔ_１＝０（貫通孔）を含む）、好ましくは、０．０１〜０．７９となるように溝が振動（音叉）腕に形成されている。本実施例では、ｔ_１＜ｔの関係を有するが、本発明はこれに限定されるものでなく、本発明はｔ_１＝ｔの関係をも包含する。即ち、振動腕に溝のない平面である。電極は平面である上下面に配置され、電極の配置、接続は溝を有するときと同じである。このように形成することにより、振動腕の中立線を基点とするモーメントが大きくなる。即ち、電気機械変換効率が良くなるので、等価直列抵抗Ｒ_１の小さい、Ｑ値の高い、しかも、容量比の小さい音叉形状の屈曲水晶振動子を得ることができる。Furthermore, assuming that the partial widths W ₁ and W _{3 of} the vibrating arms and the groove width W ₂ , the arm width W of the vibrating arms 11 and 12 is W =

W ₃ is formed. Further, the groove width W ₂ is formed under the conditions satisfying W ₂ ≧ W ₁ and W ₃ . More specifically, in this embodiment, the ratio (W ₂ / W) of the groove width W ₂ to the arm width W is larger than 0.35 and smaller than 1, preferably 0.35 to It is in the range of 0.95. Further, as shown in FIG. 2, the ratio (t ₁ / t) between the thickness t _{1 of} the groove and the thickness t of the vibrating arm is smaller than 0.79 (including t ₁ = 0 (through hole)). Preferably, the groove is formed on the vibrating (tuning fork) arm so as to be 0.01 to 0.79. In the present embodiment, there is a relationship of t ₁ <t, but the present invention is not limited to this, and the present invention also includes a relationship of t ₁ = t. That is, the vibration arm is a flat surface without a groove. The electrodes are arranged on the upper and lower surfaces, which are flat, and the arrangement and connection of the electrodes are the same as when the grooves are provided. By forming in this way, the moment with the neutral line of the vibrating arm as a base point is increased. That is, since the electro-mechanical conversion efficiency is improved, a small equivalent series resistance R _1, a high Q value, moreover, it is possible to obtain a bending crystal oscillator of a small tuning fork capacity ratio.

〜０．５３ｍｍの範囲内にある。更に、基本波モードで振動する良好な音叉形状の屈曲水晶振動子を得るためには、溝の長さＬ_０と全長Ｌ_ｔとの間には密接な関係が存在する。On the other hand, although not shown, the grooves 13 and 15 and the grooves 14 and 16 have a groove length L ₀ , and the vibrating arm has an arm length L. Therefore, in order to obtain a vibrator having a small R ₁ , L ₀ / L has a value of 0.4 to 0.8. Here, when the electrode disposed in the groove is disposed in a part of the groove, L ₀ is the length L _d of the electrode in the groove. Furthermore, the total length L _t of the bent quartz resonator 10 is determined from such as the size of the frequency or container required. In this embodiment, in order to reduce the size of the tuning fork, L _t has a dimension of 2.8 mm or less, and preferably has a dimension of 2.1 mm or less. In order to further reduce the size, L _t is in the range of 1.02 mm to 1.95 mm. The overall width _{W 5 (= 2W + W 4} ) of the vibrating arm is below 0.43 mm, preferably in the range of 0.15Mm～0.36Mm. In this embodiment, the width dimension of the (tuning fork) base is given by _WH , and W

Within the range of ~ 0.53 mm. Further, in order to obtain a good tuning-fork-shaped bent quartz crystal resonator that vibrates in the fundamental wave mode, a close relationship exists between the groove length L ₀ and the total length L _t .

That is, the ratio (L ₀ / L _t ) between the length L _{0 of the} groove provided in the vibrating arms 11 and 12 and the total length L _t of the tuning fork-shaped bent quartz crystal resonator is 0.23 to 0.88. The length of the groove is provided. In particular, L ₀ is 1.45 mm or less, preferably L ₀ is in the range of 0.48 mm to 1.29 mm. Further, L ₀ may extend to the base (the length L _K of the groove on the base). The reason for forming in this way is that, in particular, it is possible to suppress the second harmonic vibration, which is an unnecessary vibration, and to improve the frequency stability of the fundamental mode vibration. Therefore, it is possible to realize a good bent crystal resonator that easily vibrates in the fundamental wave mode. If described in detail, the equivalent series resistance R ₁ of the bending quartz oscillator tuning fork vibrating at the fundamental mode is smaller than the equivalent series resistance R ₂ at the second harmonic mode vibration. That is, R ₁ <R ₂ , and in the crystal oscillator including the amplifier (CMOS inverter), the capacitor, the resistance element, the tuning-fork-shaped bent crystal resonator of this embodiment, etc., the resonator is easily oscillated in the fundamental mode. Crystal oscillator can be realized. That is, the oscillation frequency of the fundamental mode vibration is obtained as an output signal. Further, the groove length L ₀ may be divided in the length direction of the vibrating arm, and at least one of them may satisfy the side ratio (L ₀ / L _t ) or may be divided. The length of the added groove in the length direction of the formed groove should satisfy the side ratio (L ₀ / L _t ).

Further, in this embodiment, the base portion 25 in FIG. 1 (a) (b), is a whole portion of the lower side and the width W _H of the U-shape of the vibrator 10, and the vibration arms and the vibrating arms 11 Reference numeral 12 denotes the entire U-shaped upper portion of the vibrator 10 in FIGS. In the present embodiment, the tuning fork fork has a U-shape, but the present invention is not limited to the above shape, and the tuning fork fork may have a rectangular shape. In this case as well, as in the U-shaped shape, the dimensional relationship between the vibrating arm and the base is the same as the above relationship. The groove length L _{0 referred} to in the present invention means that the ratio (W ₂ / W) of the groove width W ₂ to the vibrating arm width W is larger than 0.35, smaller than 1, and the groove thickness t. ₁ is a length of a groove formed so that a ratio (t ₁ / t) of ₁ and the thickness t of the vibrating arm is smaller than 0.79.

In other words, at least one groove is provided in the longitudinal direction on the upper and lower surfaces of the vibrating arm including the neutral line, electrodes are disposed on both side surfaces of the groove, and the electrodes on the side surfaces of the groove and the electrodes are opposed to the electrodes. vibrating arms and the side electrodes are configured such that different poles each other, at least one of groove width W ₂ and the vibration arm width of said each at least one groove as the moment of inertia generated in the vibration arm is increased to The ratio (W ₂ / W) to W is larger than 0.35 and smaller than ₁ , and the ratio (t ₁ / t) between the thickness t _{1 of the} groove and the thickness t of the vibrating arm is smaller than 0.79. A groove is formed so as to be.

As an example, the vibrating arm includes at least a first vibrating arm and a second vibrating arm, and the first vibrating arm, the second vibrating arm, and the base are integrally formed by an etching method, Grooves are provided on the upper and lower surfaces of the vibrating arm and the second vibrating arm, respectively, in the thickness direction, and the groove is located above the central portion in the width direction across the neutral line of the first vibrating arm and the second vibrating arm. each one of the grooves is provided on the lower surface, are formed so as to at least one of the groove width W ₂ equal or partial width W _1, W _3, or greater than the partial width W _1, W _3, and each In the groove, electrodes having different polarities between the electrode of the groove of the first vibrating arm and the electrode of the groove of the second vibrating arm are disposed, and the electrode on the side surface of the vibrating arm disposed opposite to the electrode of the groove 3 electrode terminals having different polarities from each other, and one of the three electrode terminals is above the first vibrating arm. The electrode is arranged and connected to the groove on the lower surface, and one electrode terminal is composed of the electrodes arranged and connected to the upper and lower surfaces of the second vibrating arm, and the remaining one electrode terminal is connected to the first vibrating arm and the first vibrating arm. 2 It is comprised from the electrode arrange | positioned and connected to the both sides | surfaces of a vibrating arm.

More specifically, the Figer of Merit M _i representing the inductivity, electromechanical conversion efficiency, and quality factor of the bent quartz resonator is the ratio of the quality factor Q _i value to the capacity ratio r _i (Q _i / r _i ). defined by (i = 1 when the fundamental wave vibration, the second harmonic oscillation when i = 2), the series resonance that depends on the parallel capacitance and mechanical series resonance frequency f _s that is independent of the parallel capacitance of the flexural crystal oscillator the frequency difference Δf of frequency f _r is inversely proportional to the full Iga of merit M _i, Δf becomes smaller as the value M _i is large. Therefore, as M _i is large, the resonance frequency of the bending crystal oscillator does not influenced by the parallel capacitance, the frequency stability of a flexural quartz crystal resonator is improved. That is, a bent crystal resonator with high time accuracy can be obtained.

More specifically, the configuration of the tuning fork shape, the groove, and its dimensions makes the fibre-of-merit M ₁ of the fundamental mode vibration larger than the fibre-of-merit M ₂ of the second harmonic mode vibration. That is, M ₁ > M ₂ is satisfied. As an example, when the reference frequency of the fundamental wave mode vibration of the tuning fork shape is 32.768 kHz, W ₂ /W=0.5, _{t 1} /t=0.34, L ₀ / L _t = 0.48 However, M ₁ and M ₂ of the tuning fork-shaped bent quartz crystal resonator satisfy M ₁ > 60 and M ₂ <30, respectively. That is, (a small equivalent series resistance R ₁₎ Good high inductive electromechanical conversion efficiency, can be obtained flexural quartz oscillator that vibrates at a large fundamental mode of the quality factor. As a result, the frequency stability of the fundamental wave mode vibration becomes better than the frequency stability of the second harmonic mode vibration, and the second harmonic mode vibration can be suppressed.

  FIG. 2 is a cross-sectional view taken along the line AA ′ of the vibrating arms 11 and 12 of the bent crystal resonator 10 of FIG. The vibrating arm 11 is provided with grooves 13 and 15. Similarly, the vibrating arm 12 is provided with grooves 14 and 16. Further, electrodes 17 and 19 having the same polarity are arranged and connected to the groove 13 and the groove 15, and electrodes 18 and 20 having the same polarity are arranged and connected to the groove 14 and the groove 16. In addition, electrodes 21, 22, 23, and 24 having the same polarity are disposed and connected to the side surfaces of the vibrating arms 11 and 12, and these electrodes are grounded. That is, the ground electrode is represented by the symbol B ″. More specifically, the electrode of the groove of the vibrating arm 11 and the electrode of the groove of the vibrating arm 12 are arranged with different polarities. In the embodiment, a three-electrode terminal BB′-B ″ is configured. That is, one electrode terminal (symbol B) is configured and connected from electrodes 17 and 19. The other one electrode terminal (symbol B ′) is constructed and connected from electrodes 18 and 20. Further, the remaining one electrode terminal (symbol B ″) is a ground electrode (zero polarity) and is composed of and connected to the electrodes 21, 22, 23, 24. That is, to the three electrode terminals B, B ′, B ″. The electrodes to be connected have different polarities. Further, the electrodes will be described in detail. In this embodiment, the electrodes are arranged to oppose the electrodes 21, 22, 23 and 24 arranged on both side surfaces of the first vibrating arm 11 and both side surfaces of the second vibrating arm 12. The counter electrode is arranged to partially face each of the electrodes on both side surfaces of the first vibrating arm and the second vibrating arm.

That is, the groove electrode that opposes the z-axis (thickness) direction of the vibrating arm is configured and arranged so as to have the same polarity and the electrode that opposes the x-axis direction generally has a different polarity. Specifically, the electric field generated perpendicularly to the groove electrode does not exist in the thickness method between the groove electrode opposed to the electrode disposed in the groove provided in the thickness direction. An electrode is disposed on the surface. Now, when a DC voltage is applied between the two electrode terminals B-B '(a positive electrode at the B terminal and a negative electrode at the B' terminal), the electric field Ex works as shown by the arrows in FIG. The electric field Ex is drawn perpendicularly to the electrode by the electrodes arranged opposite to the side surface of the vibrating arm and the side surface in the groove, that is, linearly drawn, so that the electric field Ex is increased, resulting in vibration (tuning fork). At the same time, distortion occurs in the length direction of the arm, and the direction of distortion occurs oppositely on the inside and outside of the vibrating (tuning fork) arm with respect to the neutral line, and the first vibrating (tuning fork) arm and the second vibration The direction of the distortion generated inside the tuning fork is the same as that of the (tuning fork) arm neutral line, and is generated outside the tuning fork with respect to the neutral line of the first and second vibrating (tuning fork) arms. The direction of strain to be generated is the same, and the inner strain and the outer strain are generated in opposite directions. Therefore, by applying an alternating voltage between the two electrode terminals B-B ', the vibrating (tuning fork) arm vibrates in the fundamental wave mode and in the bending mode of the opposite phase, improving the resonance characteristics and generating. The amount of distortion that occurs is also increased. Therefore, even when the tuning fork-shaped bent quartz crystal is reduced in size, a tuning fork-shaped bent quartz crystal that vibrates in a bending mode having a small equivalent series resistance R ₁ and a high quality factor Q value can be obtained.

The vibration (tuning fork) arm of the bent quartz resonator 10 has a thickness t, groove has a thickness t _1. The thickness t ₁ here refers to the thickness of the deepest part of the groove. In this embodiment, the cross-sectional shape of the groove is a rectangular shape, but in actuality, the groove has a substantially U shape, or a substantially V shape, or a shape in which a substantially U shape and a substantially V shape are combined. ing. More specifically, as the groove becomes deeper, the groove width tends to become narrower. This is also true for the bent quartz resonators of other embodiments.

Bent crystal resonator of Example 2

  FIGS. 3A and 3B are a top view and a bottom view of a tuning-fork-shaped bent crystal resonator 30 that vibrates in the bending mode according to the second embodiment of the present invention. The bent crystal resonator 30 of the present embodiment includes a vibrating arm (tuning fork arm) 31, a vibrating arm (tuning fork arm) 32, and a base 45. One end of the vibrating arm 31 and the vibrating arm 32 is a base (tuning fork base). ) 45. The vibrating arm 31 and the vibrating arm 32 each have an upper surface, a lower surface, and a side surface. A groove 33 is provided on the upper surface of the vibrating arm 31, and a groove 35 is provided on the lower surface. Similarly to the vibrating arm 31, grooves 34 and 36 are provided. Furthermore, electrodes 41 and 42 are disposed and connected to the side surface of the vibrating arm 31, and the electrode 41 is connected to the electrodes 41 a and 41 c at the upper and lower ends of the base 45. Furthermore, the electrode 41 a and the electrode 41 c are connected via the electrode 41 b on the side surface of the base 45. Similarly, electrodes 43 and 44 are arranged and connected to the side surface of the vibrating arm 32, and the electrode 44 is connected to the electrodes 44 a and 44 c at the upper and lower ends of the base 45. Furthermore, the electrode 44 a and the electrode 44 c are connected via an electrode 44 b on the side surface of the base 45.

  Furthermore, electrodes 37 and 39 are disposed in the grooves 33 and 35 of the vibrating arm 31, and electrodes 38 and 40 are disposed in the grooves 34 and 36 of the vibrating arm 32. The electrodes 37 and 38 have the same polarity. The electrodes 39 and 40 are also connected to have the same polarity. One connected electrode 37, 38 is connected to the electrode 46 at the end of the base 45, and the other connected electrode 39, 40 is connected to the electrode 47 at the end of the base 45. Further, the electrode 46 and the electrode 47 are connected via an electrode 46 a on the side surface of the base 45. That is, the electrodes 37, 38, 39, and 40 are connected so as to have the same polarity. Although not shown in FIG. 3, the relationship between the dimensions of the vibrator is formed in the same manner as in the first embodiment.

FIG. 4 is a cross-sectional view taken along the line CC ′ of the vibrating arms 31 and 32 of the bent crystal resonator 30 of FIG. The vibrating arm 31 is provided with grooves 33 and 35. Similarly, the vibrating arm 32 is provided with grooves 34 and 36. Further, electrodes 37, 38, 39.40 having the same polarity are arranged and connected to the grooves 33, 34, 35, 36, and these electrodes are grounded. That is, the ground electrode. Also, electrodes 41 and 42 having the same polarity are arranged and connected to the side surface of the vibrating arm 31, and electrodes 43 and 44 having the same polarity are arranged and connected to the side surface of the vibrating arm 32. More specifically, the electrodes on the side surfaces of the vibrating arm 31 and the electrodes on the side surface of the vibrating arm 32 have different polarities. Therefore, in this embodiment, a three-electrode terminal DD′-D ″ is configured. That is, one electrode terminal (symbol D) is configured and connected from electrodes 41 and 42. Other one-electrode terminal (Symbol D ′) is composed and connected from electrodes 43 and 44. Further, the remaining one electrode terminal (symbol D ″) is a ground electrode (zero polarity), composed of electrodes 37, 38, 39 and 40. It is connected. That is, the electrodes connected to the three-electrode terminals D, D ′, and D ″ have different polarities. Further, if the electrodes are described in detail, the both side surfaces of the first vibrating arm 31 and the both side surfaces of the second vibrating arm 32 are used. The counter electrodes arranged to oppose the arranged electrodes 41, 42, 43, 44 are arranged to partially face each of the electrodes on both side surfaces of the first vibrating arm and the second vibrating arm. Now, when a DC voltage is applied between the two electrode terminals D-D '(positive to D terminal and negative to D' terminal), the electric field Ex works as shown by the arrow in FIG. By applying an alternating voltage between D and D ', the vibrating (tuning fork) arm vibrates in the fundamental wave mode and in the bending mode of the opposite phase, improving the resonance characteristics and increasing the amount of distortion generated. Therefore, even when the tuning fork-shaped bent quartz crystal is downsized, the equivalent series Small anti R _1, flexural quartz crystal tuning fork vibrating at a high bending mode Q value is obtained.

Bent crystal resonator of Example 3

  FIGS. 5A and 5B are sectional views of a tuning fork arm (vibrating arm) of a tuning fork-shaped bent quartz crystal resonator according to a third embodiment of the present invention. In FIG. 5A, a groove 53 is provided on the upper surface of the vibrating arm 51 of the bent crystal resonator 50, and a groove 54 is provided on the upper surface of the vibrating arm 52. Furthermore, electrodes 56 and 61 having the same polarity are arranged and connected to the lower surface of the groove 53 and the vibrating arm 51, and electrodes 59 and 62 having the same polarity are arranged and connected to the lower surface of the groove 54 and the vibrating arm 52. Yes. In addition, electrodes 55, 57, 58, and 60 having the same polarity are disposed and connected to the side surfaces of the vibrating arms 51 and 52, and these electrodes are grounded. That is, the electrode is represented by the symbol E ″. In more detail, the electrode of the groove of the vibrating arm 51 and the electrode of the groove of the vibrating arm 52 are arranged with different polarities. In the embodiment, a three-electrode terminal EE′-E ″ is configured. That is, one electrode terminal (symbol E) is configured and connected from the electrodes 56 and 61. The other one electrode terminal (symbol E ′) is constructed and connected from electrodes 59 and 62. Further, the remaining one electrode terminal (symbol E ″) is a ground electrode (zero polarity) and is configured and connected from electrodes 55, 57, 58 and 60. That is, to the three electrode terminals E, E ′ and E ″. The electrodes to be connected have different polarities.

Further, in FIG. 5B, a groove 73 is provided on the upper surface of the vibrating arm 71 of the bent crystal resonator 70, and a groove 74 is provided on the vibrating arm 72. Furthermore, electrodes 76, 79, 81, 82 having the same polarity are disposed and connected to the lower surfaces of the grooves 73, 74 and the vibrating arms 71, 72, and these electrodes are grounded. That is, the ground electrode. Further, electrodes 75 and 77 having the same polarity are arranged and connected to the side surface of the vibrating arm 71, and electrodes 78 and 80 having the same polarity are arranged and connected to the side surface of the vibrating arm 72. More specifically, the electrodes on the side surfaces of the vibrating arm 71 and the electrodes on the side surface of the vibrating arm 72 have different polarities. Therefore, in this embodiment, a three-electrode terminal FF′-F ″ is constituted. That is, one electrode terminal (symbol F) is constituted and connected by electrodes 75 and 77. Other one-electrode terminal (Symbol F ′) is constructed and connected from electrodes 78 and 80. Further, the remaining one electrode terminal (symbol F ″) is a ground electrode (zero polarity) and is composed of electrodes 76, 79, 81 and 82. It is connected. That is, the electrodes connected to the three electrode terminals F, F ′, F ″ have different polarities. Therefore, a DC voltage is applied between the two electrode terminals EE ′ or between the two electrode terminals FF ′ ( When the E terminal and the F terminal are positive, and the E ′ terminal and the F ′ terminal are negative), the electric field Ex works as indicated by the arrows shown in FIGS. By applying an alternating voltage between E 'or between the two electrode terminals FF', the vibrating (tuning fork) arm vibrates in the fundamental wave mode and in the bending mode of the opposite phase, and the resonance characteristics are improved. Therefore, even when the tuning fork-shaped bent quartz resonator is downsized, the tuning-fork-shaped bent quartz crystal that vibrates in a bending mode with a small equivalent series resistance R ₁ and a high Q value is obtained. In this embodiment, the groove is provided on the upper surface of the vibrating arm. The light is not limited to this, and the groove may be provided on at least one of the upper and lower surfaces of the vibrating arm.

Bent crystal resonator of Example 4

FIGS. 6A and 6B are a top view and a GG ′ cross-sectional view of a bent crystal resonator that vibrates in a bending mode according to the fourth embodiment of the present invention. The shape of the vibrator of the present embodiment is a tuning fork shape, and the bent quartz crystal vibrator 90 includes at least a vibrating arm 91, a vibrating arm 92, and a base portion 95. One end portion of the vibrating arm 91 and the vibrating arm 92 is a base portion 95. It is connected to the. Further, a frame 96 projects from the base portion 95, and the base portion 95 and the frame 96 are integrally formed. The vibrating arm 91 and the vibrating arm 92 each have an upper surface, a lower surface, and a side surface. A groove 93 is provided on the upper surface of the vibrating arm 91, and a groove is formed on the upper surface of the vibrating arm 92 in the same manner as the vibrating arm 91. 94 is provided. Also, grooves are provided on the lower surfaces of the vibrating arms 91 and 92 in the same manner as the upper surface (see FIG. 6B). In the bent quartz crystal resonator according to the present embodiment, the frame 96 is fixed to a fixing portion of a container in which the frame 96 is stored with a conductive adhesive or solder. Further, the base 95 has a length dimension _{L 1} and width _{W H, L 1} is to reduce the size, with dimensions of less than 0.5 mm. Preferably, it exists in the range of 0.015 mm-0.45 mm. Furthermore, in order to reduce the leakage of vibration energy of the vibration part by the fixing of the bending quartz oscillator, _{respectively,} the width _{W 11} of the interval _{W 10} and the frame of the vibrating arms and the frame _{W 10} is the 0.032mm~0.21mm Within the range, W ₁₁ is in the range of 0.25 mm to 0.88 mm. Furthermore, in order to improve impact resistance, a relationship of W ₁₁ = (1.2 to 7.6) × W is established. Where W is the width of the vibrating arm. Further, _{W 2} in the groove width, _{W 1} and _{W 3} being a partial width. In order to reduce the size, in this embodiment, the total arm width W ′ ₅ (= 2W + 2W ₁₀ + W ₁₁ ) is 1.2 mm or less, and preferably in the range of 0.63 mm to 1.1 mm. Furthermore, in order to prevent chipping due to impact, the corners of the base may be rounded or notched.

  Further, in FIG. 6B, the cross-sectional shapes and electrode arrangements of the vibrating arms 91 and 92 and the frame 96 will be described in detail. The vibrating arm 91 is provided with grooves 93 and 97, and the vibrating arm 92 is provided with grooves 94 and 98. Furthermore, electrodes 100 and 101 having the same polarity are disposed in the grooves 93 and 97, and electrodes 106 and 107 having the same polarity are disposed in the grooves 94 and 98. Further, electrodes 99 and 102 having the same polarity are disposed on the side surface of the vibrating arm 91, and electrodes 105 and 108 having the same polarity are disposed on the side surface of the vibrating arm 92. Specifically, an electrode is disposed on the side surface of the groove, and a two-electrode terminal H-H ′ is configured in which electrodes having different polarities are disposed on the side surface of the vibrating arm in opposition to the electrode. That is, one one-electrode terminal is configured and connected from the electrodes 99, 102, 106, and 107. The other one electrode terminal is configured and connected to electrodes 100, 101, 105, and 108. Further, the one electrode terminal is connected to the electrode 103 arranged on the frame 96, and the other one electrode terminal is connected to the electrode 104 arranged on the frame 96. Further, the frame 96 is fixed to the fixing portion of the container, and the electrodes 103 and 104 are electrically connected to the electrodes of the container (for example, the case). Further, in order to reduce the stray capacitance between the electrodes, a slit may be provided along the electrodes in the frame.

Now, when a DC voltage is applied between the two electrode terminals H-H '(positive at the H terminal and negative at the H' terminal), the electric field Ex works as indicated by the arrow shown in FIG. Therefore, when an alternating voltage is applied between the two electrode terminals H-H ', the vibrating (tuning fork) arm vibrates in the anti-phase bending mode, the resonance characteristics are improved, and the amount of distortion generated is increased. . Therefore, even when the tuning fork-shaped bent quartz crystal is reduced in size, a tuning fork-shaped bent quartz crystal that vibrates in a bending mode having a small equivalent series resistance R ₁ and a high quality factor Q value can be obtained. In this embodiment, the vibrating arm is provided with a groove, but the groove may not be provided. In this case, the electrode of the groove is disposed on a plane that is the upper and lower surfaces of the vibrating arm. Furthermore, in the present embodiment, the electrode configuration of the two-electrode terminal has been described. However, the electrode configuration of the three-electrode terminal of the first to third embodiments may be used. In this case, the ground electrode is also extended to the frame. As an example, it is disposed between the electrode 103 and the electrode 104 in FIG.

Furthermore, the bending crystal resonators of the first to fourth embodiments are excited by the piezoelectric constant e ₁₂ (= e ′ ₁₂ ), and the larger the absolute value, the better the electromechanical conversion efficiency. The absolute value of piezoelectric constant _{e 12} of the flexural crystal oscillator of the present invention have a 0.095C / ^{m 2} greater than. Usually, the absolute value of the piezoelectric constant e ₁₂ is in the range of 0.095 C / m ^{2 to} 0.19 C / m ² . In particular, the fundamental mode vibration, in order to obtain a smaller equivalent series resistance _{R 1, preferably,} the absolute value of _{e 12} is in the range of ^{0.12C / m 2 ~0.19C / m 2} . However, the piezoelectric constant e ₁₁ = 0.171 C / m ² and the piezoelectric constant e ₁₄ = −0.0406 C / m ² of quartz were used for the calculation of e ₁₂ .

Crystal unit of Example 1

  FIG. 7 is a top view of the crystal unit according to the first embodiment of the present invention. The crystal unit 130 includes a tuning fork-shaped bent crystal resonator 10 (the bent crystal resonator of the first embodiment), a case 131 and a lid (not shown). The surface mount type case 131 is provided with a fixing portion 138, and electrodes 132, 133, and 134 are arranged thereon, and are extended to the back surface of the case, although not shown. That is, a three-electrode terminal is configured. More specifically, the base portion 25 of the vibrator 10 is fixed to a fixing portion 138 provided on the case 131 with a conductive adhesive or solder. Specifically, the electrodes 17a, 26, and 18a of the base portion 25 are electrically connected to the electrodes 132, 133, and 134 of the fixing portion 138, respectively, and are fixed using fixing members 135, 136, and 137 so as to be fixed. Is done. As the fixing member, an electrically conductive material such as an adhesive or solder is used. In addition, the case 131 and the lid are joined via a joining member. Further, instead of the vibrator 10, the bent quartz crystal vibrator of the second embodiment to the fourth embodiment may be mounted. In the case of the said Example 4, two electrodes are arrange | positioned at a case so that an electrode terminal may comprise 2 electrode terminals.

  Further, the crystal unit of the embodiment is connected to a circuit element (CMOS inverter, resistor element, capacitor), and is electrically connected to a two-electrode terminal or a three-electrode terminal provided outside the crystal unit. That is, only a tuning fork-shaped bent quartz crystal is housed in the unit. At this time, the bent crystal resonator is housed in a vacuum unit. Further, the case member is made of ceramic or glass, the lid member is made of metal or glass, and the joining member is made of metal or low-melting glass. Unlike the above-described configuration, the tuning fork-shaped bent quartz crystal resonators of the first to fourth embodiments may be housed in a container (unit) together with the circuit elements.

FIGS. 8A and 8B are electrical equivalent circuit diagrams of the bent crystal resonator of the present invention. (A) is a case of 3 electrode terminals, (b) is a case of 2 electrode terminals. L ₁ , C ₁ , and R ₁ represent equivalent inductance, equivalent capacitance, and equivalent series resistance, respectively. In (a), it is composed of three electrode terminals J-J'-J ", and the electrode terminal J" is grounded. _{Also, C 2, C 3, C} 4 in capacitance between the electrodes, _{C 2} is a capacitance between the second electrode terminal J-J ', _{C 3} in the capacitance between the second electrode terminal J-J ", _{C 4} Is the capacitance between the two electrode terminals J′-J ″. Therefore, the sum of these capacitances can be electrically replaced with the parallel capacitance C ₀ of the two-electrode terminals KK ′. That is, C ₀ = C ₂ + C ₃ + C ₄ , and the three-electrode terminal can be practically handled by the two-electrode terminal.

Example 1 Crystal Oscillator

  FIG. 9 is an example of a crystal oscillation circuit diagram constituting the crystal oscillator of Example 1 of the present invention. In this embodiment, the crystal oscillation circuit 151 includes an amplifier (CMOS inverter) 152, a feedback resistor 154, a drain resistor 157, capacitors 155 and 156, and a tuning fork-shaped bent crystal resonator 153 having two electrodes. That is, the crystal oscillation circuit 151 includes an amplifier circuit 158 including an amplifier 152 and a feedback resistor 154, a drain resistor 157, capacitors 155 and 156, and a feedback circuit 159 including a bent crystal resonator 153. More specifically, the crystal oscillation circuit of the present invention is composed of an amplifier circuit and a feedback circuit, the amplifier circuit is composed of at least an amplifier, and the feedback circuit is composed of at least a tuning-fork-shaped bent crystal resonator and a capacitor. . Further, the tuning-fork-shaped bent crystal resonator used in the crystal oscillator of the present embodiment uses the two-electrode terminal bent crystal resonator described in the fourth embodiment, and the resonator is housed in a container (unit). ing. A so-called crystal unit is used.

Example 2 Crystal Oscillator

  FIG. 10 is an example of a crystal oscillation circuit diagram constituting the crystal oscillator of Example 2 of the present invention. The configuration of the crystal oscillation circuit 161 of the present embodiment is basically the same as that of the crystal oscillation circuit of the first embodiment, but the difference is the electrode configuration of the bent crystal resonator. A tuning fork-shaped bent quartz crystal 163 is used. That is, one electrode terminal is grounded. Further, the tuning-fork-shaped bent quartz crystal used in the quartz oscillator of the present embodiment is the three-electrode terminal bent quartz crystal described in the above-mentioned bent quartz crystal according to the first to third embodiments. The child is stored in a container (unit). A so-called crystal unit is used.

FIG. 11 shows the feedback circuit diagram of FIG. Now, the angular frequency of the tuning-fork-shaped quartz crystal vibrating in the bending mode is ω _i , the resistance of the drain resistor 157 is R _d , the capacitance of the capacitors 155 and 156 is C _g , C _d , and the crystal impedance of the crystal is R _ei , When the input voltage is V ₁ and the output voltage is V ₂ , the feedback rate β _i is defined by β _i = | V ₂ | _i / | V ₁ | _i . However, i represents the vibration order of the bending vibration mode. For example, when i = 1, it is fundamental wave mode vibration, and when i = 2, it is second harmonic mode vibration. Further, the load capacity C _L is given by C _L = C _g C _d / (C _g + C _d ). When C _g = C _d = C _gd and R _d >> R _ei , the feedback rate β _i is β _i = 1 / (1 + kC _L ² ). However, k is expressed by a function of ω _i , R _d , and R _ei . R _ei is approximately equal to the equivalent series resistance R _i .

Thus, from the relationship between the feedback rate β _i and the load capacitance C _L , it is well understood that the feedback rates of the fundamental mode vibration and the harmonic mode vibration increase as C _L decreases. Thus, the C _L decreases, towards the second harmonic mode vibration tends to oscillate than the fundamental mode vibration. The reason is that since the maximum vibration amplitude of the harmonic mode vibration is smaller than the maximum vibration amplitude of the fundamental mode vibration, the amplitude condition and the phase condition which are oscillation continuation conditions are satisfied simultaneously.

The crystal oscillator using the bent crystal resonator according to the present invention provides a crystal oscillator having a fundamental mode oscillation frequency with low current consumption and high frequency stability (high time accuracy). The purpose is that. Therefore, in order to reduce current consumption, the load capacitance _{C L} is used below 18 pF. In order to further reduce the current consumption, since the current consumption is proportional to the load capacity, C _L = 14 pF or less is preferable. Further, in order to suppress the vibration of the second harmonic mode and the output signal of the oscillator obtains the oscillation frequency of the fundamental mode vibration, α ₁ / α ₂ > β ₂ / β ₁ and α ₁ β ₁ > 1 are satisfied. Thus, the oscillation circuit of this embodiment is configured. However, α ₁ and α ₂ are amplification factors of the fundamental wave mode vibration and the second harmonic mode vibration, and β ₁ and β ₂ are feedback of the fundamental mode vibration and the second harmonic mode vibration feedback circuit. Rate.

In other words, the ratio between the amplification factor α ₁ of the fundamental mode vibration of the amplifier circuit and the amplification factor α ₂ of the second harmonic mode vibration is equal to the feedback factor β ₂ of the second harmonic mode oscillation of the feedback circuit and the fundamental wave. greater than the ratio of the feedback factor beta ₁ mode vibration, and the product of the feedback factor beta ₁ amplification factor alpha ₁ and the fundamental mode vibration of the fundamental wave mode vibration is configured to be greater than 1. With such a configuration, it is possible to realize a crystal oscillator that consumes less current and whose output signal has an oscillation frequency of fundamental mode vibration. The output signal of the crystal oscillation circuit is output through a buffer circuit. Furthermore, in order to obtain an optimum feedback factor of the fundamental mode oscillation, but the drain resistance _{R d} is usually 200kΩ within the 1 M.OMEGA, preferably, 600Keiomega is used from 300Keiomega.

Further, the amplifying part of the amplifying circuit constituting the crystal oscillation circuit of the present embodiment can exhibit the characteristic by a negative resistance -RL _i . When i = 1, it is a negative resistance of fundamental mode vibration, and when i = 2, it is a negative resistance of second harmonic mode vibration. In the crystal oscillator of the present embodiment, the ratio of the absolute value | −RL ₁ | of the negative resistance of the fundamental mode vibration of the amplifier circuit to the equivalent series resistance R ₁ of the fundamental mode vibration is the second harmonic mode of the amplifier circuit. The oscillation circuit is configured to be larger than the ratio between the absolute value | −RL ₂ | of the negative resistance of vibration and the equivalent series resistance R ₂ of the _second harmonic mode vibration. That is, it is configured to satisfy | −RL ₁ | / R ₁ > | −RL ₂ | / R ₂ . Preferably, it has a relationship of | -RL ₁ | / R ₁ >1> | -RL ₂ | / R ₂ . With such a configuration of the crystal oscillation circuit, the oscillation activation of the second harmonic mode vibration can be suppressed, so that the oscillation frequency of the fundamental mode vibration can be obtained as an output signal. In particular, in order to achieve the above-described object with an ultra-miniaturized tuning-fork-shaped bent quartz crystal, as an example, when the reference frequency of the fundamental mode vibration is 32.768 kHz (oscillation frequency is approximately 32.768 kHz), the basic The absolute value | -RL ₁ | of the negative resistance in the amplification section in the wave mode vibration is larger than 80 kΩ, and the absolute value | -RL ₂ | of the negative resistance in the amplification section of the second harmonic mode vibration is It is necessary to be smaller than 75 kΩ. In addition, the electrode configuration of the bent crystal unit constituting the crystal oscillation circuit of the present embodiment is a two-electrode terminal. However, as described in FIG. 8, the electric equivalent circuit is the same for both the two-electrode terminal and the three-electrode terminal. Therefore, it goes without saying that a crystal oscillation circuit having the same result as that of the two-electrode terminal can be obtained even when the three-terminal bent crystal resonator is used.

Further, the capacity ratio r ₁ in the fundamental mode vibration of the tuning fork-shaped bent quartz crystal of the first to fourth embodiments is configured to be smaller than the capacity ratio r ₂ of the second harmonic mode vibration. . With such a configuration, with respect to the same change in the load capacitance C _L, greater than the frequency change of the bending quartz oscillator frequency change of the bending quartz oscillator which oscillates at the fundamental mode oscillates at the second harmonic mode. For example, in the vicinity of C L ₌ 18 pF, when the C _L value changes 1 pF, the frequency change in the fundamental mode oscillation is greater than the frequency variation of the second harmonic mode vibration. Therefore, the fundamental mode vibration has significant effect even with a small variable amounts of C _L, it can widen the variable range of frequency. In addition, the capacitance ratio r ₁ in the fundamental mode vibration of the bent quartz crystal of each of the above embodiments is in the range of 230 to 490, and the capacitance ratio r ₂ has a value greater than 1500.

内にあるときには、Ｑ_１＜Ｑ_２の関係が得られる場合がある。The capacitance ratios r ₁ and r ₂ of the tuning fork-shaped bent quartz crystal resonator are given by r ₁ = C ₀ / C ₁ and r ₂ = C ₀ / C ₂ , respectively. However, C ₀ is a shunt capacitance electrical equivalent circuit, C ₁ and C ₂ is the equivalent capacitance of the fundamental mode vibration and second harmonic mode vibration of an equivalent circuit. That is, C ₀ is the total capacitance between the terminals, between the two electrode terminals or between the three electrode terminals of the bent crystal resonator. In other words, it is the capacitance between electrodes where an electric field is generated. Further, the quality factor of the fundamental mode vibration and the second harmonic mode vibration of the tuning fork-shaped bent quartz crystal resonator is given by Q ₁ value and Q ₂ value. In each of the tuning fork-shaped bent quartz resonators of the above-described embodiments, the dependency of the resonance frequency oscillating in the fundamental wave mode due to the parallel capacitance is smaller than the dependency of the resonance frequency oscillating in the second harmonic mode due to the parallel capacitance. Configured as follows. That is, it is configured to satisfy r ₁ / 2Q ₁ ² <r ₂ / 2Q ₂ ² . With this configuration, the influence of the parallel capacitance of the resonance frequency oscillating in the fundamental wave mode is so small that it can be ignored, so that a tuning-fork-shaped bent quartz crystal oscillating in the fundamental wave mode having high frequency stability can be obtained. Further, in the present invention, r ₁ / 2Q ₁ ² and r ₂ / 2Q ₂ ² are respectively set as S ₁ and S ₂ , and S ₁ and S ₂ are respectively frequency-stable for fundamental mode vibration and second harmonic mode vibration. Called coefficient. That is, S ₁ = r ₁ / 2Q ₁ ² and S ₂ = r ₂ / 2Q ₂ ² are given. Furthermore, usually Q ₁ > Q ₂

If it is within the range, a relationship of Q ₁ <Q ₂ may be obtained.

In addition, the electromechanical coupling coefficient of the fundamental mode vibration of the vibrator described in the above embodiments is larger than the electromechanical coupling coefficient of the second harmonic mode vibration, and the equivalent series resistance R ₁ of the fundamental mode vibration is It is in the range of 35 kΩ to 105 kΩ. R ₂ has a relationship of R ₂ / R ₁ > 1. That is, the groove and the electrode are configured to satisfy at least the relationship of R ₂ > 35 kΩ. Although the reference frequency of 32.768 kHz is used as the reference frequency in the fundamental mode vibration of the tuning-fork-shaped bent quartz crystal of each of the above embodiments, the present invention is not limited to this frequency, and the reference frequency of 10 kHz to 200 kHz is used. Applied. Further, in the above embodiment, using quartz as the piezoelectric material, the present invention is not limited thereto, the present invention is another piezoelectric materials, for example, lithium tantalate _{(L i T a O 3)} , It includes all piezoelectric materials including lithium niobate (L _i N _b O ₃ ), langasite, and is applied to the vibrator, unit and oscillator of the present invention. Furthermore, in the above embodiment, the ratio (t ₁ / t) between the groove thickness t ₁ of the vibrating arm and the thickness t of the vibrating arm is 0.79 or less.

Further, as an example of the method for manufacturing the crystal oscillator of the present invention, the oscillation frequency of the tuning fork-shaped bent crystal resonator is 32.768 kHz and the output signal of the crystal oscillation circuit is within 32.768 kHz ± 100 ppm (parts per million). In order to obtain the frequency as the output frequency, first, an electrode is disposed in a crystal wafer by a photolithographic method and an etching method (for example, a chemical etching method or an ion etching method) with a grooved or non-grooved vibrator, In addition, the vibrator is formed to have a frequency higher than 32.768 kHz. At this time, the vibrator has the vibrator shape and electrode arrangement described in the first to fourth embodiments. Next, after fixing to the fixing part of the container for housing the vibrator, a weight is added to the tuning fork arm so that an oscillation frequency within 32.768 kHz ± 100 ppm is obtained as an output frequency of the output signal of the crystal oscillation circuit. After adjusting the frequency or attaching a weight to the tuning fork arm so that the frequency is lower than 32.768 kHz, and fixing the tuning fork arm to the fixing portion of the container for housing the vibrator, the output signal of the crystal oscillation circuit is 32.768 kHz. The frequency is adjusted by removing the weight of the tuning fork arm so that an oscillation frequency within ± 100 ppm is obtained as the output frequency. In this case, the step of attaching the weight to the tuning fork arm so that the frequency is lower than 32.768 kHz is performed in the wafer state, and further, the laser beam or the like is applied so that it is in the range of −9500 ppm to +100 ppm in the wafer state. A step of adjusting the oscillation frequency may be included. Thereafter, the vibrator is fixed to the container, and the oscillation frequency is adjusted as described above. Further, the crystal oscillator amplifier, a capacitor is configured to include a resistor element and a flexural quartz crystal resonator, the load capacitance C _L value of the crystal oscillator circuit is used below 18 pF. Furthermore, for the frequency adjustment, at least one of a so-called ion etching method or sputtering method using a laser beam, vapor deposition, electron beam, and ionized atoms and molecules is used. Further, in this embodiment, a vibrator is formed in a crystal wafer so that the electrodes are arranged with a grooved or non-grooved vibrator and the frequency is higher than 32.768 kHz, and then the crystal wafer is formed. A step of inspecting whether the resonator is a good resonator or a defective resonator may be included. That is, when a defective vibrator is present, the defective vibrator is removed from the quartz wafer, or some marking is made on the vibrator, or the vibrator is stored in the computer.

  Since the crystal resonator, crystal unit, and crystal oscillator of the present invention are ultra-compact and have high frequency stability, they are particularly applicable to portable devices and consumer devices that are ultra-compact and require high frequency stability.

(A) And (b) shows the top view and bottom view of the bending crystal oscillator of Example 1 of this invention. FIG. 2 is a cross-sectional view taken along the line AA ′ of FIG. 1. (A) And (b) shows the top view and bottom view of the bending crystal oscillator of Example 2 of this invention. FIG. 4 is a cross-sectional view taken along the line CC ′ of FIG. 3. (A) And (b) shows sectional drawing of the vibrating arm (tuning fork arm) of the bending crystal oscillator of Example 3 of this invention. (A) And (b) shows the top view and GG 'sectional drawing of the bending crystal oscillator of Example 4 of this invention. It is a top view of the crystal unit of Example 1 of this invention. (A) And (b) is an electrical equivalent circuit schematic of the bending crystal oscillator of this invention. 1 shows one embodiment of a crystal oscillation circuit diagram constituting the crystal oscillator of Embodiment 1 of the present invention. One Example of the oscillation circuit diagram which comprises the crystal oscillator of Example 2 of this invention is shown. FIG. 10 is a feedback circuit diagram of FIG. 9.

Explanation of symbols

_WH tuning fork base width W ₄ , W ₁₁ tuning fork arm spacing, frame width L ₀ , L ₁ groove length, tuning fork base length L _t total length of tuning fork

Claims (7)

  A bending crystal resonator comprising a vibrating arm and a base that vibrates in a bending mode, wherein the vibrating arm has an upper surface, a lower surface, and a side surface, and a groove is provided on at least one surface of the upper and lower surfaces of the vibrating arm. A crystal resonator, wherein a ground electrode is disposed on at least one side surface of the vibrating arm. A crystal unit composed of a crystal unit, case, and lid,
The crystal unit is a flexural crystal unit composed of a vibrating arm that vibrates in a bending mode and a base, and the vibrating arm has an upper surface, a lower surface, and a side surface, and a groove is provided on at least one surface of the upper and lower surfaces of the vibrating arm. A grounding electrode is disposed on at least one side of the groove or the side surface of the vibrating arm. A crystal unit composed of a crystal unit, case, and lid,
The crystal unit is a bending crystal unit composed of a vibrating arm and a base that vibrate in a bending mode, the vibrating arm has an upper surface, a lower surface, and a side surface, and a frame is provided so as to protrude from the base unit. crystal unit absolute value of piezoelectric constant _{e 12} of the bent crystal oscillator is characterized in that in the range of ^{0.095C / m 2 ~0.19C / m 2} . The amplifier circuit is composed of an amplifier circuit and a feedback circuit. The amplifier circuit is composed of an amplifier and a feedback resistor element, and the feedback circuit is composed of a crystal oscillation circuit composed of a crystal resonator, a capacitor and a resistor element. Crystal oscillator,
The crystal unit is a flex crystal unit composed of a vibrating arm and a base that vibrate in a bending mode, and the vibrating arm has an upper surface, a lower surface, and a side surface,
With said crystal oscillating circuit off Iga of merit M ₁ of the fundamental wave mode vibrations comprises a Figa of merit M ₂ greater flexural crystal oscillator of the second harmonic mode oscillation in the flexural crystal oscillator is configured,
Ratio of absolute value | −RL ₁ | of negative resistance of fundamental wave mode vibration and equivalent series resistance R ₁ of fundamental wave mode vibration of the amplification circuit of the crystal oscillation circuit configured to include an amplification circuit and a feedback circuit The crystal oscillation circuit is configured so that is larger than the ratio of the absolute value | −RL ₂ | of the negative resistance of the second harmonic mode vibration of the amplifier circuit to the equivalent series resistance R ₂ of the _second harmonic mode vibration. And
A crystal oscillator characterized in that an output signal of the crystal oscillation circuit configured to include the bent crystal resonator is an oscillation frequency of fundamental mode vibration. Vibrating arms and the frame is provided so as to protrude from the base of the formed bending quartz oscillator and a base, absolute value 0.095C / m 2 ^~0 piezoelectric constant e ₁₂ of the bent crystal oscillator. The crystal oscillator according to claim 4, wherein the crystal oscillator is in a range of 19 C / m ² .   The vibrating arm includes a first vibrating arm and a second vibrating arm. One groove is provided on each of the upper and lower surfaces of the first vibrating arm and the second vibrating arm, and electrodes are disposed on the side surfaces of the groove and the vibrating arm. The electrode disposed on the side surface is a ground electrode, or the crystal unit according to claim 1, or the crystal unit according to claim 2 or 3, or claim 4 or claim. Item 6. The crystal oscillator according to Item 5.   The vibrating arm includes a first vibrating arm and a second vibrating arm. One groove is provided on each of the upper and lower surfaces of the first vibrating arm and the second vibrating arm, and electrodes are disposed on the side surfaces of the groove and the vibrating arm. The electrode disposed in the groove is a ground electrode, or the crystal unit according to claim 1, or the crystal unit according to claim 2 or claim 3, or claim 4 or claim. Item 6. The crystal oscillator according to Item 5.

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