JPS5818806B2 - Tuning fork piezoelectric vibrator - Google Patents

Description

[Detailed description of the invention] The present invention refers to the main surface (meaning the widest surface).

) is formed into a U-shape (hereinafter referred to as a tuning fork piezoelectric vibrator).

) is related to the cage. Ever since tuning fork piezoelectric vibrators, especially tuning fork crystal vibrators, have been used as vibration sources in wristwatches.

In addition to the strong demand for smaller size, copper loss, and shock resistance, it is necessary to minimize the influence of the cage and improve the temperature characteristics of the series resonant resistance and resonant frequency. Although a good leveling φ is required, these requirements are not easily satisfied because they conflict with each other.

For example, in the case of a holding structure for a tuning fork crystal resonator as shown in FIG. It is fixed and held by gluing or soldering.

Although such tuning fork crystal resonators are superior in terms of miniaturization, vibration damping, and impact resistance, they do not meet the original electrical characteristics of crystal resonators, especially the series resonant resistance value and resonant frequency. The temperature characteristics of each are forcibly constrained and deteriorated by the mechanical influence of the holding table 2.

In other words, a tuning fork crystal resonator has a series resonant resistance that is originally small, such as several ohms to several tens of ohms, whereas a high frequency resonator (several MHz to several tens of MHz) that utilizes a thickness-based vibration mode has a series resonance resistance of several ohms to several tens of ohms. Since it is a low frequency oscillator (several Hz to several hundred KHz) that utilizes a bending vibration mode, its series resonance resistance is more than 50Ω even in a vacuum sealed container environment, and furthermore, this value is , is not constant with respect to the ambient temperature, and sometimes even increases rapidly to the extent that oscillation stops at a certain temperature.

Along with this deterioration phenomenon of the series resonant resistance value, the resonant frequency temperature characteristic also changes. Normally, if the shape and cutting azimuth of the crystal vibrating piece 1 are constant, the resonant frequency temperature %Fl is included in the variation within the measurement error range. Even though it should, the distribution may have large variations without reproducibility, and the frequency change rate may become larger than the original characteristic.

The present invention has been made to solve these problems, and is suitable for miniaturization without deteriorating the electrical characteristics of a tuning fork-shaped piezoelectric vibrator, and capable of withstanding external vibrations and shocks. An object of the present invention is to provide a tuning fork-shaped piezoelectric vibrator equipped with a functional holder.

In order to achieve such an object, the tuning fork piezoelectric vibrator of the present invention has a holder for a tuning fork piezoelectric vibrator that holds the base of a tuning fork piezoelectric vibrating piece whose main surface is formed into a U-shape. The - portions of the opposing surfaces of both main surfaces of are used as clamping points, and from the clamping points, each extends in the longitudinal direction of the tuning fork-shaped piezoelectric vibrating piece without contacting the bidirectional surfaces, and the end face of the base is It consists of a tuning fork-shaped piezoelectric vibrator characterized by being surrounded and integrated.

Here, the term "tuning fork piezoelectric vibrator" refers to a tuning fork expansion piezoelectric material such as crystal, lithium tantalate, lithium niobate, or piezoelectric ceramic, in which an excitation electrode for flexural vibration is arranged, and the shape and material constants of the piezoelectric material are It vibrates by applying an alternating voltage that matches the resonance frequency based on the excitation electrode to the excitation electrode, and the "base" refers to the tuning fork-shaped piezoelectric vibrating piece other than the leg that bends and vibrates.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to examples.

First, in order to facilitate understanding of the present invention, the configuration and operating principle of a tuning fork type piezoelectric vibrator will be explained with reference to FIGS. 2 and 3.

FIG. 2 is a perspective view showing the basic configuration of a tuning-fork piezoelectric vibrator, and the shaded portions in a and b of the figure are excitation electrodes for causing the tuning-fork piezoelectric vibrator to bendingly vibrate. A split electrode 31° and a main surface (B2
Four-sided electrodes 32 are arranged on opposing surfaces of the C2 plane) and the side surface (A2C2 plane), respectively.

Note that 1'' is the base of the tuning fork-shaped piezoelectric vibrating piece.

The shape of the tuning fork piezoelectric vibrating piece is U-shaped in a and b, respectively, with the BlC plane and the B2C2 plane as the main surfaces, and the crystal axes (AsBscs) and (A2 B2C2)
are orthogonal cubic coordinate axes, and if expressed using commonly used crystal coordinate axes (X'YZ), for example, if the piezoelectric material is crystal, A1 is X, Bl is z', and c is Y' , A2 is Z'', B2 is x, and C2 is Y'.

In addition, when the piezoelectric body is lithium tantalate, A1 is Z',
B1 is X', C1 is Y'', A2 is X', B2 is Z
', C2 is Y''.

Here, the crystal coordinate axis (xy'z') is defined as (xy'z") to indicate the rotation of the coordinate axis around the X axis of the initial crystal coordinate axis (xyz), and the crystal coordinate axis (X/
y//z/) is Z of the initial crystal coordinate axis (xyz)
The crystal coordinate axis (x'
y'z) further rotated around the X' axis as (X/Y//Z/).

Rotating the crystal coordinate axes in this way means rotating the cutting azimuth angle of the piezoelectric material within a desired range of angles in order to obtain a frequency % characteristic suitable for the temperature used. This is the usual means of

The electrode connection diagrams shown in a and b in FIG. 3 correspond to the same symbols in a and b in FIG. 2, respectively, and are detailed views of the parts related to the respective electrodes. ′ is shown from the beginning.

Then, by applying an alternating voltage that matches the resonant frequency of the tuning fork piezoelectric vibrator between terminals D2 and B2, the tuning fork piezoelectric vibrator shown in a and b in FIG. Bending vibration is performed using the B, C, and B2C2 planes as bending vibration surfaces.

Next, embodiments of the present invention will be described. However, since the crystal coordinate axes and the arrangement diagram of the excitation electrodes will complicate the drawings, these will not be shown, and the explanation will be explained using diagrams focusing on the tuning fork-shaped piezoelectric vibrating piece and the cage. do.

FIG. 4 is a structural diagram of a tuning fork-shaped crystal resonator which is an embodiment of the present invention, and FIG. 4A is an overall view thereof, and FIG.

A tuning fork-shaped crystal vibrating piece 1 consisting of a leg portion 1' and a base portion 1'' is clamped by clamping surfaces 81 and 82 of the holder 4 on opposing bidirectional surfaces of the base portion 1.

The retainer 4 is fixed by soldering to a lead-out terminal 51 implanted in an insertion hole 6 made of an insulating material such as glass fixed to the bottom plate 7 of the sealed container.

Here, 2
By arranging one of the terminal electrodes facing each other on both sides of the base 1'', one terminal of the two terminal electrodes can be electrically connected to the retainer 4 by soldering or conductive adhesive, and the tuning fork The shaped crystal vibrating piece 1 is held by a holder 4.

Further, the remaining terminal electrodes are electrically connected by connecting lead wires to the lead terminals 5□ implanted in the insertion holes 62.

The tuning fork crystal resonator constructed in this way is then assembled by cold welding the cover of the sealed container to the bottom plate 7 (the inside of the container is evacuated).

As described above, the noteworthy structure of the embodiment of the present invention is the structure of the base 1'' of the tuning fork-shaped crystal vibrating piece 1 and the retainer 4.

That is, the pinching portions of the tuning fork-shaped crystal vibrating piece 1 are on the opposing surfaces of the amphiphilic surfaces of the base 1, and the pinching points 81, 8 of the retainer 4 are
The structure of the retainer is that it extends in the longitudinal direction of the tuning fork-shaped crystal vibrating piece 1 from only a portion of □ without contacting both main surfaces from its clamping point, and is combined around the end face of the base 1''. Get noticed.

By the way, the cage 9 of the tuning fork-shaped crystal vibrating piece 1 shown in FIG.
At first glance, this seems to be similar to the cage 4 shown in the embodiment of the present invention.

However, as shown in the detailed view of the retainer 9, the clamping surfaces 10I and 10□ and the bottom surface 11 are the area from the center to the longitudinal end on the main surface of the base 1'' and the bottom surface 1. ″
It must be noted that the structure is made up of contact over the entire area.

Therefore, if we compare the electrical characteristics of the tuning fork crystal resonator shown in FIG. 4, which is an embodiment of the present invention, and the tuning fork crystal resonator shown in FIG. I will explain that there is a remarkable difference that cannot be predicted due to the difference in the structure of the two.

In other words, in the fundamental wave vibration, which is the symmetrical first mode, there is not much difference between the two because the series resonance resistance and the temperature characteristics of the resonant frequency are good. However, in the eye movement in the symmetrical second mode, the following As you can see, a significant difference appears.

FIGS. 11 and 12 show cases in which the resonant frequencies of the symmetrical secondary 4 modes are 200,000H and Z, respectively, and cages 4 and 9 shown in FIGS. 4 and 5 are used as cages. The series resonance resistance temperature % characteristics and resonance frequency temperature characteristics of a tuning fork crystal resonator are shown.

In addition, in Fig. 11, the horizontal axis is temperature T ('C) and the vertical axis is series resonant resistance C1, (KΩ), and in Fig. 12, the horizontal axis is temperature T (°C), and the vertical axis is resonant frequency F. (Hz).

12 and 14 of each percent characteristic curve are shown in FIG. 4, and cages 4, 13, and 15 are the series resonance resistance temperature characteristics and resonance of a tuning fork crystal resonator when cage 5 shown in FIG. 5 is used. It is a frequency temperature characteristic curve diagram.

Curves 12 and 14 are characteristic curves that are close to the inherent characteristics of a tuning fork crystal resonator, which are determined by the shape and dimensions of the dragon fork crystal resonator and the cutting azimuth of the crystal vibrating piece.On the other hand, curves 13 and 15 are Compared to the aforementioned curves 12 and 14, respectively, not only are the fluctuations significantly large at each temperature, but the series resonance resistance values at 0°C and 30°C are so large that they cannot be measured in the Ω digit. Therefore, the resonant frequency at that time also causes a significant fluctuation, and even ends up stopping oscillation.

In addition, in terms of reproducibility of each % characteristic curve, the tuning fork crystal resonator using cage 4 shown in Fig. 4 is good, but on the other hand,
'The tuning-fork crystal resonator using the retainer 9 shown in FIG. 5 has a very large dispersion, which proves that the present invention is excellent in this respect as well.

As explained above, the tuning fork crystal resonator according to the present invention has
Good characteristics can be maintained not only in the symmetrical primary mode (fundamental wave vibration) but also in the symmetrical secondary mode without deteriorating the electrical characteristics of the tuning fork crystal resonator.

Furthermore, according to one rigid impact test, even if a wristwatch incorporating a tuning fork-shaped crystal oscillator using the present invention was dropped onto a wooden board from an altitude of 1.5 m, the frequency deviation was less than 0.3 seconds per day. It has been confirmed that only a small amount occurs, and the retention function is also fully satisfied.

With regard to miniaturization, it can be said that the embodiment is optimal, as shown in the drawings, needing no further explanation.

Although crystal has been taken up as an example as the piezoelectric material, the effects of the present invention can also be applied to tuning fork-shaped piezoelectric vibrators made of other piezoelectric materials, such as lithium tantalate, lithium niobate, and piezoelectric ceramics. What you get is
This will be easily understood by those skilled in the art.

Further, as other embodiments of the present invention, structural diagrams of a tuning fork type piezoelectric vibrator shown in FIGS. 6, 7, and 8 can be cited.

The tuning fork-shaped piezoelectric vibrators shown in FIGS. 6 and 8 can be used when the former is held perpendicular to the main surface of the vibrating piece 1, and when the latter is held parallel to the main surface of the vibrating piece 1. There are two retainers 4. and 42 are used to electrically connect to the two-terminal electrodes arranged on both main surfaces of the base 1'', and at the same time, the vibrating piece 1 is held by the holders 41 and 4□.

The tuning fork-shaped piezoelectric vibrator shown in FIG. 7 is held perpendicular to the main surface of the vibrating piece 1, and one retainer 4 is used as in the structural diagram shown in FIG. 4'. ing.

In each of these embodiments as well, the cage 4 shown in FIG. 4A is used as the basic structure, so the same effects as the tuning fork-shaped piezoelectric vibrator shown in FIG. 4A can be obtained. That is clear.

Further, modifications of the cage include those shown in FIGS. 9 and 10.

Thus, the tuning fork type piezoelectric vibrator according to the present invention is compact and has excellent vibration resistance and impact resistance, and the electric characteristics inherent to the tuning fork type piezoelectric vibrator are not degraded not only in the symmetrical first mode but also in the symmetrical second mode of vibration. Therefore, it has extremely high industrial value in this field.

[Brief explanation of the drawing]

Fig. 1 is a structural diagram of a conventional tuning fork type crystal resonator, Fig. 2 is a perspective view showing the basic configuration of a tuning fork type piezoelectric resonator, and Fig. 3 is a structural diagram of a conventional tuning fork type piezoelectric resonator.
4 is a structural diagram of a tuning fork type piezoelectric vibrator which is an embodiment of the present invention; FIG. 5 is a structural diagram of a tuning fork type piezoelectric vibrator to be compared with the present invention; 6, 7, and 8 are structural diagrams of a tuning fork-shaped piezoelectric vibrator that are other embodiments of the present invention, and Figures 9 and 10 are structural diagrams that are other embodiments of a cage used in the present invention, and FIG. 1L12 is a series resonant resistance temperature characteristic curve diagram and a resonant frequency temperature characteristic curve diagram in symmetrical second-order mode vibration of a tuning fork-shaped piezoelectric vibrator based on the embodiment of the present invention and the structural diagram shown in FIG. 5, respectively. 1...Tuning fork-shaped piezoelectric vibrating piece, 1"...Base of tuning fork-shaped piezoelectric vibrating piece, 4, 41.4□...
retainer.

Claims (1)

[Claims] 1. A holder of a tuning fork piezoelectric vibrator that holds the base of a tuning fork piezoelectric vibrating piece whose main surface is formed into a U-shape has a portion of opposing surfaces of both main surfaces of the base as a clamping point, and the clamping A tuning fork type piezoelectric vibrator, characterized in that the tuning fork type piezoelectric vibrating piece extends in the longitudinal direction from each point without contacting both of the main surfaces, and is integrated around the end face of the base.