JPH0590880A - Tortional quartz oscillator - Google Patents

Abstract

PURPOSE:To obtain a compact tortional quartz oscillator whose secondary higher harmonic oscillation is suppressed by making the length of the exciting electrode to be attached to tuning fork arms to be longer than the half of the length of the tuning fork arm. CONSTITUTION:If a quartz oscillator 3 has a tuning fork shape, letting the length of its tuning fork arms be y0 providing that the boundary condition be fixed for one arm and be free for the other arm, the displacement u of the basic wave oscillation 1 ascends as in the direction toward the tip of the arms. On the other hand, the displacement u of the secondary higher harmonic wave oscillation 2 ascends once in the direction toward the tip, while the displacement u, when the position of the oscillation passes a certain point, descends. Further, displacement u becomes zero at the position where the length y1 is 0.67y0. As the oscillation moves farther in the direction toward the tip, the displacement u ascends, and at the position with an arm length of y0 the absolute value of the displacement becomes the maximum. Accordingly, by installing exciting electrodes 5 and 6 considering the displacement pattern of the basic wave oscillation 1 and that of the secondary higher harmonic oscillation 2, the tortional quartz oscillator that suppresses the secondary higher harmonic wave oscillation 2 can be obtained.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明は、捩り水晶振動子の励振
電極に関する。特に、小型化、高精度化、耐衝撃性、低
廉化の要求の強い腕時計、ポケットベル、ＩＣカードや
移動体無線等の基準信号源として最適な捩り水晶振動子
に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exciting electrode of a twisted quartz crystal unit. In particular, the present invention relates to a twisted crystal oscillator most suitable as a reference signal source for wristwatches, pagers, IC cards, mobile radios, etc., which are strongly required to be compact, highly accurate, shock resistant, and inexpensive.

【０００２】[0002]

【従来の技術】周波数が２００ｋＨｚ〜６００ｋＨｚの
水晶振動子は、音叉形状した屈曲水晶振動子と縦水晶振
動子が用いられてきた。2. Description of the Related Art As a crystal unit having a frequency of 200 kHz to 600 kHz, a bending crystal unit having a tuning fork shape and a vertical crystal unit have been used.

【０００３】[0003]

【発明が解決しようとする課題】しかしながら、従来か
ら使用されている音叉型屈曲水晶振動子は高調波モード
を使用するため、電極形成が複雑で、リード線等の支持
による振動エネルギー損失が多く、その結果、等価直列
抵抗Ｒ₁ が上昇するなどの課題が残されていた。一方、
縦水晶振動子は、周波数が振動腕の長さに反比例するた
めに、６００ｋＨｚ以下の振動子を実現しようとする
と、おのずから、サイズが大きくなり、小型化できない
という課題が残されていた。このようなことから、周波
数が２００ｋＨｚ〜６００ｋＨｚで、しかも高調波振動
を抑圧した、超小型で、零温度係数を有し、等価直列抵
抗Ｒ₁ の小さい、化学的エッチング加工が容易な水晶振
動子が所望されていた。However, since the tuning fork type bent crystal resonator used in the related art uses the harmonic mode, the electrode formation is complicated and the vibration energy loss due to the support of the lead wire is large. As a result, there remain problems such as an increase in equivalent series resistance R ₁ . on the other hand,
Since the frequency of the vertical crystal oscillator is inversely proportional to the length of the vibrating arm, when the oscillator having a frequency of 600 kHz or less is realized, the size of the crystal oscillator naturally becomes large, and the problem that the size cannot be reduced remains. For this reason, the quartz oscillator having a frequency of 200 kHz to 600 kHz, suppressing harmonic vibration, having a small size, having a zero temperature coefficient, having a small equivalent series resistance R ₁ and being easily chemically etched is provided. Was desired.

【０００４】[0004]

【課題を解決するための手段】本発明は、以下の方法で
従来の課題を解決するものである。すなわち、捩り振動
モードで振動する音叉形状水晶振動子で、捩り振動を励
振する励振電極は音叉基部から音叉腕先端に対して、１
／２より長く設けることにより課題を解決している。The present invention is to solve the conventional problems by the following methods. That is, in the tuning fork crystal oscillator vibrating in the torsional vibration mode, the excitation electrode for exciting the torsional vibration is 1 from the tuning fork base to the tuning fork arm tip.
The problem is solved by providing it longer than / 2.

【０００５】[0005]

【作用】このように、本発明は捩り水晶振動子で、しか
も、音叉腕に配置される励振電極長を音叉腕の長さの１
／２より大きくすることにより、第２次高調波振動を抑
圧した、Ｒ₁ の小さい小型の捩り水晶振動子がエッチン
グ法によって得られる。As described above, according to the present invention, the length of the excitation electrode disposed on the tuning fork arm is set to 1 of the length of the tuning fork arm.
By making it larger than / 2, a small torsional quartz crystal resonator having a small R ₁ and suppressing the second harmonic vibration can be obtained by the etching method.

【０００６】[0006]

【実施例】次に、本発明を実施例に基づいて具体的に述
べる。図１は、本発明の捩り水晶振動子の振動モードを
示す。本発明の音叉形状の場合、境界条件は一端固定、
他端自由と考えることができる。今、座標軸ｙ、変位を
ｕとすると、基本波振動１と第２次高調波振動２の捩り
水晶振動子の変位ｕは図１のごとく与えられる。今、振
動腕の長さｙ₀ とすると、基本波振動１は先端に行くに
つれて変位ｕは大きくなる。一方、第２次高調波振動２
は一端変位ｕは大きくなるが、更に先端に行くにつれ
て、変位ｕは小さくなり、ｙ₁ ＝０．６７ｙ₀ でｕ＝０
となる。更に、先端部に行くにつれて大きくなり、ｙ＝
ｙ₀ で変位の絶対値は最大を示す。それ故、基本波振動
１と第２次高調波振動２の変位形を考慮して励振電極を
配置することにより、第２次高調波振動２を抑圧した捩
り水晶振動子が得られる。EXAMPLES Next, the present invention will be specifically described based on Examples. FIG. 1 shows the vibration modes of the twisted crystal oscillator of the present invention. In the case of the tuning fork shape of the present invention, the boundary condition is fixed once,
The other end can be considered free. Now, assuming that the coordinate axis is y and the displacement is u, the displacement u of the torsional quartz oscillator of the fundamental wave vibration 1 and the second harmonic vibration 2 is given as shown in FIG. Now, assuming that the length of the vibrating arm is y ₀ , the displacement u of the fundamental wave vibration 1 increases toward the tip. On the other hand, the second harmonic vibration 2
The displacement u increases once, but the displacement u decreases toward the tip, and y ₁ = 0.67 y ₀ and u = 0.
Becomes Furthermore, it becomes larger toward the tip, and y =
The absolute value of the displacement shows the maximum at y ₀ . Therefore, by disposing the excitation electrodes in consideration of the displacement types of the fundamental wave vibration 1 and the second-order harmonic vibration 2, a twisted quartz resonator in which the second-order harmonic vibration 2 is suppressed can be obtained.

【０００７】次に、その抑圧できる理由と励振電極につ
いて述べる。振動を抑圧するには、振動子に流れる電流
Ｉをできるだけ小さくすればよい。今、振動子を励振す
る圧電定数をｅ₁₆、基本波振動及び第２次高調波振動時
に振動子に流れる電流をＩ_0,Ｉ₂ とすると、 Ｉ₀ ∝ｅ₁₆ｓｉｎ（π／２ｙ₀ ）ｙ_e …（１） Ｉ₂ ∝ｅ₁₆ｓｉｎ（３π／２ｙ₀ ）ｙ_e …（２） の関係が得られる。但し、ｙ_e は基部からの電極長であ
る。Ｉ₀はｙ_e が増加すると徐々に大きくなる。しか
し、Ｉ₂ はｙ_e が０．３３ｙ₀ までは増加するが、更に
ｙ_e が増加すると、ｙ_e ＝０．６７ｙ₀ で、Ｉ₂ ＝０と
なる。それ故、励振電極の長さｙ_e を０．６７ｙ₀ まで
配置することにより、第２次高調波振動を完全に抑圧す
ることができる。しかし、実際には、ｙ_e を０．５ｙ₀
まで設けても第２次高調波振動２の電流Ｉ₂ は基本波振
動１の電流より著しく小さくなり、十分に第２次高調波
振動を抑圧することができる。更には、ｙ_e を０．６７
ｙ₀ より長くしても、Ｉ₂ はＩ₁ より相当に小さくでき
るので（ｙ_e ＝０．６７ｙ₀ ではＩ₂ ＝０）、同様に第
２次高調波振動を抑圧することができる。Next, the reason why it can be suppressed and the excitation electrode will be described. In order to suppress the vibration, the current I flowing through the vibrator may be made as small as possible. Now, assuming that the piezoelectric constant for exciting the vibrator is e ₁₆ , and the currents flowing through the vibrator at the time of fundamental vibration and second harmonic vibration are I _{0 and} I ₂ , I ₀ ∝e ₁₆ sin (π / 2y ₀ ) y _e (1) I ₂ ∝e ₁₆ sin (3π / 2y ₀ ) y _e (2) However, y _e is the electrode length from the base. I ₀ gradually increases as y _e increases. However, although I ₂ has y _e increases to 0.33Y _0, further y _e is increased, with y _e = 0.67y _0, the I ₂ = 0. Therefore, by arranging the length y _e of the excitation electrode up to 0.67 y ₀ , the second harmonic vibration can be completely suppressed. However, in reality, y _e is 0.5y ₀
Even if it is provided, the current I ₂ of the second harmonic vibration 2 is significantly smaller than the current of the fundamental vibration 1, and the second harmonic vibration can be sufficiently suppressed. Furthermore, y _e is 0.67
be longer than y _0, I ₂ is because it considerably less than I ₁ (I ₂ = 0 at y _e = 0.67y _0), it is possible to suppress the second harmonic vibration as well.

【０００８】図２は、本発明の音叉形状捩り水晶振動子
の励振電極配置の一実施例である。音叉形状捩り水晶振
動子３は音叉腕４とマウント部７から構成されている。
音叉腕４には励振電極５、６が配置され、マウント部７
まで延びている。又、励振電極５、６の電極長ｙ_e は
０．５ｙ₀ （ｙ₀：音叉腕の長さ）より大きく（ｙ_e ≧
０．５ｙ₀ ）なるように配置されている。本実施例では
音叉腕４の表面のみに励振電極を配置したが、表裏面に
配置しても同様の効果が得られる。Ｒ₁ を更に小さくし
たいときには、表裏面に励振電極を配置すれば良い。次
に、零温度係数が得られるカット角（φ、θ）と辺比Ｒ
_zx（厚みｚ₀ ／幅ｘ₀ ）との関係について述べる。FIG. 2 shows an embodiment of the arrangement of the excitation electrodes of the tuning fork-shaped twisted crystal oscillator of the present invention. The tuning fork-shaped twisted crystal unit 3 includes a tuning fork arm 4 and a mount portion 7.
Excitation electrodes 5 and 6 are arranged on the tuning fork arm 4, and a mounting portion 7 is provided.
Has been extended to. The electrode length y _e excitation electrodes 5 and 6 0.5y ₀ (y _0: fork arm length) greater than (y _e ≧
0.5y ₀ ). Although the excitation electrodes are arranged only on the surface of the tuning fork arm 4 in this embodiment, the same effect can be obtained by disposing the excitation electrodes on the front and back surfaces. When it is desired to further reduce R ₁ , it is sufficient to dispose excitation electrodes on the front and back surfaces. Next, the cut angle (φ, θ) and the side ratio R at which the zero temperature coefficient is obtained
The relationship with _zx (thickness z ₀ / width x ₀ ) will be described.

【０００９】図３は、本発明の音叉形状捩り水晶振動子
８とその座標系を示す。座標系は原点０、電気軸ｘ、機
械軸ｙ、光軸ｚから成り、０−ｘｙｚを構成している。
まず、厚みｚ₀ ，幅ｘ₀ ，長さｙ₀ から成り、ｙ軸回り
に捩りモーメントを有する捩り水晶振動子８はｚ軸と垂
直となるＺ板水晶に一致するように置く。次に、ｘ軸
（φ度）とｚ軸の新軸ｚ’軸（θ度）を回転軸として、
反時計方向の回転を正とすると、角度φ＝２５゜〜３３
゜、θ＝±（５゜〜３０゜）及びφ＝−３０゜〜−６０
゜、θ＝±（２０゜〜５０゜）で辺比Ｒ_zx（ｚ₀ ／
ｘ₀ ）＝０．１〜０．８の組み合わせにより、１次温度
係数α＝０が得られる。FIG. 3 shows a tuning fork-shaped twisted crystal oscillator 8 of the present invention and its coordinate system. The coordinate system is composed of an origin 0, an electric axis x, a mechanical axis y, and an optical axis z, and constitutes 0-xyz.
First, the twisted crystal oscillator 8 having a thickness z ₀ , a width x ₀ and a length y ₀ and having a twisting moment around the y-axis is placed so as to coincide with a Z-plate crystal perpendicular to the z-axis. Next, the x-axis (φ degree) and the new z-axis z ′ axis (θ degree) are used as rotation axes,
If the counterclockwise rotation is positive, the angle φ = 25 ° ~ 33
°, θ = ± (5 ° to 30 °) and φ = -30 ° to -60
The edge ratio R _zx (z ₀ / at the _{angle of} θ = ± (20 ° -50 °)
The combination of x ₀ ) = 0.1 to 0.8 gives the primary temperature coefficient α = 0.

【００１０】図４は、本発明の音叉形状捩り水晶振動子
の周波数温度特性の一実施例を示す。カット角φ＝２９
゜、θ＝１０゜の場合である。常温でα＝０となり、こ
のときの２次温度係数βは−１．３６×１０^-8／℃²と
優れた周波数温度特性を示す。図５は、本発明の音叉形
状捩り水晶振動子の周波数温度特性の他の実施例を示
す。カット角φ＝−４３゜、θ＝４０゜の場合である。
図４と同様、優れた周波数温度特性を示す。FIG. 4 shows an embodiment of the frequency-temperature characteristic of the tuning fork-shaped twisted crystal oscillator of the present invention. Cut angle φ = 29
This is the case where the angle θ and θ = 10 °. At room temperature, α = 0, and the secondary temperature coefficient β at this time is −1.36 × 10 ⁻⁸ / ° C. ^{2, which} is an excellent frequency-temperature characteristic. FIG. 5 shows another embodiment of the frequency-temperature characteristic of the tuning fork-shaped twisted quartz crystal resonator of the present invention. This is the case where the cut angle φ = −43 ° and θ = 40 °.
Similar to FIG. 4, it exhibits excellent frequency-temperature characteristics.

【００１１】[0011]

【発明の効果】以上述べたように、本発明の音叉形状捩
り水晶振動子は次の著しい効果を有する。 （１）音叉腕に配置される励振電極長を限定することに
より、第２次高調波振動を抑圧することができる。 （２）エッチング法によって容易に形成できるので、小
型化、薄型化ができる。同時に、１枚のウエハ上に多数
個の振動子を一度にバッチ処理できるので、低廉化が可
能である。 （３）常温で零温度係数が得られるので、高精度の捩り
水晶振動子となる。 （４）音叉形状に加工されるので、リード線等の支持に
よる振動エネルギー損失が小さくなり、耐衝撃性に優れ
た捩り水晶振動子が得られる。 （５）振動子の表裏面に励振電極を配置することによ
り、等価直列抵抗Ｒ₁の小さい、Ｑ値の高い音叉形状捩
り水晶振動子が得られる。As described above, the tuning fork-shaped twisted crystal oscillator of the present invention has the following remarkable effects. (1) The second harmonic vibration can be suppressed by limiting the length of the excitation electrode arranged on the tuning fork arm. (2) Since it can be easily formed by an etching method, it can be made smaller and thinner. At the same time, a large number of vibrators can be batch-processed on one wafer at a time, so that the cost can be reduced. (3) Since the zero temperature coefficient can be obtained at room temperature, the twisted quartz crystal resonator has high accuracy. (4) Since it is processed into a tuning fork shape, the loss of vibration energy due to the support of lead wires and the like is reduced, and a twisted quartz crystal resonator having excellent impact resistance can be obtained. (5) By disposing the excitation electrodes on the front and back surfaces of the oscillator, a tuning fork-shaped twisted quartz oscillator having a small equivalent series resistance R ₁ and a high Q value can be obtained.

【図面の簡単な説明】[Brief description of drawings]

【図１】本発明の捩り水晶振動子の振動モードを示す。FIG. 1 shows vibration modes of a twisted crystal oscillator according to the present invention.

【図２】本発明の音叉形状捩り水晶振動子の励振電極配
置の一実施例を示す。FIG. 2 shows an embodiment of the arrangement of excitation electrodes of the tuning fork-shaped twisted crystal oscillator of the present invention.

【図３】本発明の音叉形状捩り水晶振動子とその座標系
を示す。FIG. 3 shows a tuning fork-shaped twisted crystal oscillator of the present invention and its coordinate system.

【図４】本発明の音叉形状捩り水晶振動子の周波数温度
特性の一実施例である。FIG. 4 is an example of frequency-temperature characteristics of the tuning fork-shaped twisted quartz crystal resonator of the present invention.

【図５】本発明の音叉形状捩り水晶振動子の周波数温度
特性の他の実施例である。FIG. 5 is another embodiment of the frequency-temperature characteristic of the tuning fork-shaped twisted crystal resonator of the present invention.

【符号の説明】[Explanation of symbols]

１ 基本波 ２ 第２次高調波 ３、８ 音叉形状捩り水晶振動子 ４、９ 音叉腕 ５、６ 励振電極 ７ マウント部 φ、θ カット角 ｙ_e 励振電極長 ｘ₀ 音叉腕の幅 ｚ₀ 音叉腕の厚み ｙ₀ 音叉腕の長さ ｘ 電気軸 ｙ 機械軸 ｚ 光軸 ｕ 変位1 fundamental wave 2 2nd harmonic 3 and 8 tuning fork shape twisted crystal unit 4 and 9 tuning fork arm 5 and 6 excitation electrode 7 mounting part φ, θ cut angle y _e excitation electrode length x ₀ tuning fork arm width z ₀ tuning fork Arm thickness y ₀ Tuning fork arm length x Electric axis y Mechanical axis z Optical axis u Displacement

Claims (1)

【特許請求の範囲】[Claims] 【請求項１】 捩り振動モードで振動する音叉形状水晶
振動子で、励振電極の長さをｙ_e 、音叉基部から腕先端
までの長さをｙ₀ としたとき、ｙ_e ≧０．５ｙ₀ となる
よう、捩り振動を励振する励振電極を設けたことを特徴
とする捩り水晶振動子。In 1. A tuning fork crystal oscillator that oscillates at a torsional vibration mode, when the length y _e excitation electrodes, the length from the fork base to the arm tip was y _0, y _e ≧ 0.5Y ₀ A twisted quartz crystal resonator is provided with an excitation electrode for exciting torsional vibration.