JP3260402B2 - Torsional crystal oscillator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cut angle and a side ratio Ryx (thickness / width) of a torsional quartz oscillator. In particular, the present invention relates to a new-cut torsional crystal resonator that is optimal as a temperature sensor for a temperature measuring device.

[0002]

2. Description of the Related Art Thickness-sliding quartz oscillators, contour-sliding quartz oscillators, bent quartz oscillators, and torsional quartz oscillators have been used as oscillators for temperature sensors according to specifications.

[0003]

[SUMMARY OF THE INVENTION However, a thickness shear quartz crystal oscillator and face shear crystal has conventionally been used the transducer has a high frequency of several MH _Z above, many current consumption of the equipment, moreover, miniaturization Issues such as difficulties remained. On the other hand, the conventional bent crystal resonator and torsional crystal resonator can be operated at a low frequency, so that the power consumption can be reduced and the size can be reduced. However, the secondary temperature coefficient of the bent crystal resonator does not become zero. In addition, the linearity of the frequency with respect to the temperature is poor. Therefore, in order to obtain sufficient measurement accuracy, correction by an IC or the like is necessary, and there remains a problem that a circuit becomes complicated. Although the torsional quartz oscillator can overcome the above-mentioned problem, the conventional torsional quartz oscillator has the length direction coincident with the x-axis direction as compared with the quartz plate rotated with the Y-plate as the x-axis (electric axis) as the rotation axis. In addition, the vibrating arm cannot be formed with good alignment due to the anisotropy of the crystal of quartz,
Increases the energy loss of the support portion due to vibration, a problem that yield better not obtained a small torsional crystal oscillator equivalent series resistance R ₁ had been left. Because of this, 2
There has been a demand for a small-sized and low-frequency crystal resonator having a zero temperature coefficient of zero, a vibrating arm that can be formed with good alignment even by chemical etching, and a low frequency.

[0004]

The present invention solves the conventional problem by the following method. That is, a quartz crystal vibrating in a torsional vibration mode, a Y-plate crystal perpendicular to the y-axis (mechanical axis) and an x-axis (electric axis) as a rotation axis, and an angle φ
= 48 ° to 120 ° rotation, further, to form a y-axis the vibrator from around the angle θ = 0 ° ~80 ° rotated quartz plate of the new axis y 'axis, further, the thickness of the vibrator y ₀ And the ratio R of the width x ₀
solves the problem by forming yx a (y ₀ / x ₀₎ in 1.1 0.1.

[0005]

As described above, the present invention relates to a torsional quartz crystal resonator, and the cut angle (φ, θ) is set such that the Y plate rotates around the x axis by φ = 48.
Rotate about 120 °, and θ = 0 ° about the y 'axis.
By rotating by 80 ° and forming a vibrator having a side ratio Ryx (thickness y ₀ / width x ₀ ) of 0.1 to 1.1 from this plate by an etching method, the secondary temperature coefficient becomes zero. ,
A small, low-frequency torsional crystal resonator can be obtained.

[0006]

Next, the present invention will be specifically described based on examples. FIG. 1 shows a torsional crystal resonator 1 of the present invention and its coordinate system. The coordinate system includes an origin 0, an electric axis x, a mechanical axis y, and an optical axis z, and forms 0-xyz. First, the thickness y ₀ ,
The torsional quartz resonator 1 having a width x ₀ and a length z ₀ and having a torsional moment about the z-axis is placed so as to coincide with a Y-plate quartz which is perpendicular to the y-axis. Next, a new axis y ′ of the x-axis and the y-axis
Assuming that the rotation in the counterclockwise direction is positive with the axis as the rotation axis, the rotation is performed by the angles φ = 48 ° to 120 ° and θ = 0 ° to 80 °.

Next, the relationship between the cut angle (φ, θ) at which the secondary temperature coefficient β becomes zero and the side ratio Ryx (thickness y ₀ / width x ₀ ) will be described. 2 to 4 show the cut angle (φ, θ) and the side ratio Ry when the secondary temperature coefficient β of the torsional quartz crystal resonator of the present invention becomes zero.
x (FIG. 2) and the first- and third-order temperature coefficients α,
γ (FIG. 3) and (FIG. 4). Cut angle φ = 48 °
It can be clearly seen that β = 0 infinitely depending on the combination with the side ratio Ryx at up to 120 ° and θ = 0 ° to 80 °.
That is, in the range of φ = 48 ° to 120 ° and θ = 0 ° to 80 °, β = 0 can be obtained by selecting from the side ratios Ryx = 0.1 to 1.1. The values of α and γ at that time are shown in FIGS. 3 and 4, and the value of α is about 12 to
It has a value of 30 ppm / ° C. On the other hand, the smaller the absolute value of γ, the better the linearity over a wide temperature range. As shown in FIG. 4, when θ = 0 ° to 30 °, φ
Can be reduced relatively near 55 °, 110 ° and 120 °. Note that, as shown in FIG.
There are φ and Ryx at which β = 0 even if it exceeds 0 °, but in consideration of the easiness of etching, it is limited to about φ = 120 °.

FIG. 3 shows a cut angle φ = 90 °, θ =
An example of the frequency-temperature characteristic at 30 ° is shown. Frequency-temperature characteristics excellent in linearity were obtained.

[0009]

As described above, the torsional quartz resonator according to the present invention has the following remarkable effects. (1) Cut angle φ = 48 ° to 120 °, θ = 0 ° to 80
° and the side ratio Ryx = 0.1 to 1.1,
Since the secondary temperature coefficient β becomes zero, a frequency temperature characteristic having excellent linearity is exhibited.

(2) Since the cut angle of the present invention can be easily formed by an etching method, the size and thickness can be reduced. At the same time, a large number of transducers can be batch-processed on one wafer at a time, so that the cost can be reduced. (3) Since the frequency constant is between the tuning-fork type bent crystal resonator of the fundamental wave and the vertical crystal resonator, the frequency is relatively low.
kH _Z to especially take effect before and after.

[Brief description of the drawings]

FIG. 1 shows a torsional crystal resonator of the present invention and its coordinate system.

FIG. 2 shows the relationship between the cut angle (φ, θ) and the side ratio Ryx when the secondary temperature coefficient β of the torsional crystal resonator of the present invention becomes zero.

FIG. 3 shows the value of the primary temperature coefficient α when the secondary temperature coefficient of the present invention becomes zero.

FIG. 4 shows the value of a tertiary temperature coefficient γ when the secondary temperature coefficient of the present invention becomes zero.

FIG. 5 is an example of a frequency-temperature characteristic of the torsional crystal resonator of the present invention.

[Explanation of symbols]

1 Torsional crystal oscillator x ₀ width z ₀ length y ₀ thickness φ, θ cut angle x electric axis y mechanical axis z optical axis

Claims (1)

(57) [Claims] 1. A Y-plate crystal perpendicular to a y-axis serving as a mechanical axis,
Angle φ = 48 ° -12 with x-axis as electric axis as rotation axis
When the direction after the rotation of the y axis is a new y ′ axis, the crystal plate is rotated around the y ′ axis by an angle θ = 0 ° to 80 °, and has a thickness y _0. And the ratio R _yx (y ₀ / x ₀ ) of the width x ₀ to the width x ₀ is 0.1 to 1.1 , and the secondary temperature coefficient β is 0,
A torsional crystal resonator characterized in that: