JPS6010111Y2 - crystal twisted resonator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a twisted crystal resonator suitable for use in twisted mode converters.

As shown in Fig. 1, a conventional torsional mode converter consists of a vibrator 1 made of piezoelectric ceramic and resonators 2 and 3 made of a constant elastic alloy.The vibrator 1 is polarized in the direction of the arrow. Nichrome gold was vapor-deposited on the surfaces of semicircular porcelain 1□ and 12,
They are bonded together with the resonators 2 and 3 so that their polarization directions are opposite to each other.

Since such a transducer uses a constant modulus alloy, it is not possible to obtain good Q value and frequency-temperature characteristics without heat treatment, and even after heat treatment, the characteristics vary widely. Therefore, it is difficult to obtain a product of constant quality, and furthermore, since the main length dimension of the resonator is large, there are many drawbacks such as making it impossible to downsize the transducer.

The present invention has been made with the aim of alleviating the above-mentioned drawbacks at once, and provides a new torsional resonator that can replace constant elastic alloys.

FIG. 2 shows the cutting direction of the crystal resonator 4 of the twisted resonator according to the present invention, and the crystal coordinate axis X of the crystal.

Y, Z (where the X axis is the electrical axis, the Y axis is the mechanical axis, and the Z axis is the optical axis.

) is cut from the crystal coordinate axes (X, Y', Z') after rotating the Y-axis and two axes counterclockwise around the X-axis.

Here, the rotation angle θ is selected from within the range of 40 to 6 degrees, as described later.

The resonance frequency f of the torsional vibration mode is given by the following equation.

Here, the main length dimension of the crystalline lens in the Y'-axis direction, μ is the shear elastic modulus, and ρ is the density of the crystalline lens.

The inventor of the present invention focused on the relationship with the rotation angle described above based on this basic equation of the resonance frequency, and obtained useful results.

When observing the relationship, this frequency constant characteristic appears as curve 5 shown in FIG.

This curve 5 shows that when the same resonance frequency f is obtained and the rotation angle θ is within the range of 40 to 7 degrees, the frequency constant kr is 1 v 700k''wtt or less.

More specifically, in the twisted crystal resonator of f=128 kHz, the relationship between the main length dimension 1 and the rotation angle θ appears as a curve 6 shown in FIG.

According to this curve 6, it is shown that the rotation angle θ is within the range of 40 to 73 degrees and the main length dimension 1 is about 13 degrees or less.

Therefore, if it is desired to reduce the main length dimension 1 of the resonator in order to obtain a predetermined resonance frequency f, the rotation angle θ of the crystalline lens may be selected from the range of 40 to 73 degrees.

Next, when observing the relationship between the first-order frequency temperature coefficient Tt'' and the rotation angle θ, this first-order temperature coefficient characteristic appears as a curve 7 shown in FIG.

This curve 7 is 1 when the rotation angle θ is 36 degrees and 50 degrees.
This indicates that the next temperature coefficient T, 1) is set to zero.

However, when the rotation angle θ is 136 degrees, a quadratic temperature coefficient T! 2)
is -60 (X 10-9/deg2), which is a fairly large value, so the frequency temperature characteristics are
Although it is inappropriate because it is influenced by the following temperature coefficient, when the rotation angle θ is 50 degrees, the quadratic temperature coefficient T, /2
) is also a small value, so it exhibits good frequency-temperature characteristics.

Since the practical range that exhibits a good first-order temperature coefficient Tf1) is ±20 (X10=/deg) or less, the rotation angle θ is limited to a range of 40 degrees to 60 degrees.

For the second-order frequency coefficient 'r''), curve 8 in Figure 6
In this case, the value of T, 2) is ±40 (X 10-9/deg
”) can be as follows.

In addition, curve 8 shows T when the rotation angle θ is 147 degrees, 2)
The value of is set to zero, but the value of the first-order temperature coefficient becomes the fifth
50 (10-'/deg
), which is quite large and does not exhibit good temperature characteristics.

The crystal resonator obtained according to the present invention is used in place of a conventional constant modulus alloy, and FIG. 7 shows the configuration of an example.

In FIG. 7a, the resonator 10, 10' made of piezoelectric ceramic has a disk shape divided into parts, and electrodes 11, 11' of metal such as nickel chrome gold are provided on each amphibatic surface.

The directions of polarization are opposite to each other as shown in the figure.

A part of the electrode extends to the side surface of the vibrator 10.10', is drawn out as an extraction electrode 12.12', and is connected to the outside.

As shown in FIG. 7, the transducer 14 is constructed by bonding the vibrator 10.10' with the crystal resonator 13.13' according to the present invention.

In this way, the portion of the transducer 14 that becomes a vibration node is fixed and supported by the coupler 15.

In this case, the coupler 15 is usually used with a plurality of resonators connected thereto.

If we take the above explanation into consideration, it can be seen that the rotation angle θ which can provide good frequency temperature characteristics and reduce the main length dimension of the resonator is 40 to 60 degrees.

To give an example of the characteristics of this invention, the main length l is 13Trr!
As a result of a prototype experiment of a torsion mode converter using IL as resonators 2 and 3 shown in Fig. 1, using a crystal torsion resonator with a rotation angle θ of 50 degrees, we found that the frequency The rate of change was in the range of ±15 to 20 ppm, and uniform characteristics were obtained.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing a conventional torsion mode converter, Fig. 2 is a crystal coordinate axis showing the cutting direction of the crystalline lens according to the present invention, Fig. 3 is a characteristic diagram of the frequency constant kr with respect to the rotation angle θ,
Figure 4 is a characteristic diagram of the main length dimension 1 versus rotation angle θ, and Figure 5
The figure is a characteristic diagram of the first-order frequency temperature coefficient T, 1) with respect to the rotation angle θ, and FIG. 6 is the characteristic diagram of the second-order frequency temperature coefficient T (2) with respect to the rotation angle θ. FIGS. 7a and 7b are perspective views showing an example in which the resonator of the present invention is configured as a transducer, and FIG. 8 is a perspective view showing the resonator connected to a connector. 1.10.10'... Vibrator, 4,13.13
′...Crystal resonator, θ...Rotation angle, 1
... Length main dimension, 14 ... Conversion element.

Claims (1)

[Scope of utility model registration request] After the crystal resonator of the transducer, which is constructed by bonding a vibrator and a crystal resonator together, rotates around the X axis of the crystal coordinate axes x, y, and z, counterclockwise around the Y axis and two axes. The crystal resonator is cut by crystal coordinate axes A crystal torsional resonator characterized by resonating in a torsional vibration mode.