JPS61260709A - Tuning fork type crystal resonator - Google Patents

Abstract

PURPOSE:To improve resonance frequency temperture characteristic by selecting the Z' axis obtained by turning a crystal by an angle of alpha (2 deg.-6 deg.) around the X axis as the thickness direction and selecting the X' axis obtained by turning the crystal by an angle of theta (6 deg.-10 deg.) around the Z' axis as the broadwise direction and using the cut crystal chip. CONSTITUTION:A crystal chip (a) is a crystal chip while being turned by an angle alpha with respect to the X axis by, e.g., alpha=2 deg.-6 deg., and a crystal chip (b) is a crystal chip cut out by turning the crystal around the Z' axis by an angle theta, e.g., theta=6 deg.-10 deg.. Then a crystal chip C forming a tuning fork is cut out while the lengthwise direction is taken as the Y'' axis, the broadwise direction is taken as the X' axis, the thickness direction is takes as the Z' axis on the plane comprising the X' axis and the Y'' axis. An exciting voltage is fed to each electrode provided to vibration arms 12, 13 of the crystal chip 1 through the leads 15, 16. The vibration of the vibration arms 12, 13 is vibrated at a prescribed frequency region by making the torsional vibrating frequency of the part (m) coincident with the bending vibration frequency of the part (n).

Description

DETAILED DESCRIPTION OF THE INVENTION (Industry - (Second Field of Application)) The present invention relates to a tuning fork crystal resonator, and particularly to a tuning fork crystal resonator that is small and has good resonance frequency temperature characteristics.

(Prior Art) Tuning fork crystal oscillators that utilize +5°×Y bending vibration are most commonly used as quartz crystal oscillators for watches. Since the tuning fork crystal resonator that utilizes this bending vibration is small and has a low resonance frequency, a C to MO5 integrated circuit with low power consumption is used as an oscillation circuit.

On the other hand, as a watch crystal oscillator, the frequency temperature characteristic is a cubic curve, and the temperature range of the characteristic portion is wide.
T-cut crystal resonators are also used.

(Problems with the prior art) The frequency-temperature characteristics of the above-mentioned tuning fork-shaped crystal resonator using bending vibration form a parabola, as shown in the curve B in Figure 4.
The following curve is

Therefore, even if the peak temperature is defined, the following frequency deviation occurs between it and the temperature actually used.

Δf/f=k (To T+)2Δf
/f: Deviation from the frequency in To: T1: For the temperature used: Quadratic coefficient To: Peak temperature 1. From the formula, the wider the temperature difference, the more the frequency change becomes a problem, and the frequency temperature characteristic Since the temperature range that can be used is narrow, for example, when used in a table clock, etc., it is directly affected by changes in the temperature of the environment and generally causes an error in the rate, making it impossible to obtain a highly accurate clock. arise.

Furthermore, an AT-cut crystal oscillator that utilizes shear vibration is also used as a watch crystal oscillator, and the frequency-temperature characteristic of this AT-cut quartz crystal oscillator has a cubic curve. Since the temperature range of its characteristic i + ztu is wide, it is possible to obtain a highly accurate clock with a difference of a few seconds per year, for example, but because the resonance frequency is as high as several MH1, it is difficult to use the C-MO3 integrated circuit, which has a slow operating speed. Not available. Therefore, in order to use the C-MO3 integrated circuit, it is necessary to increase the number of frequency division stages or increase the thickness of the AT can l wood crystal vibration r- to lower its resonant frequency. In the latter case, the circuit becomes complicated and the power consumption increases, and in the latter case, there are disadvantages such as the size of the crystal lift itself becomes large.

(Object of the Invention) An object of the present invention is to eliminate the conventional drawbacks as described in L, and to provide a tuning fork-shaped crystal vibrating f- that is small, consumes little power, and has good resonance frequency temperature characteristics.

(Summary of the Invention) In the present invention, in a tuning fork-shaped crystal resonator, the crystal resonator has a Z' axis obtained by rotating an angle of α (2° to 6°) around the X axis of the crystal. is the thickness direction, and is made from a crystal piece cut with the X' axis obtained by rotating the Z' axis at an angle of θ (6° to lO°) as the central axis, and the width direction is f.
A tuning fork-shaped crystal resonator is provided in which electrodes are provided on the front and back surfaces and both side surfaces of a vibrating arm forming a g-fork to generate torsional vibration in a predetermined portion of the vibrating arm and bending vibration in another predetermined portion. Ru.

(Example) Next, an example of the present invention will be described in detail using the drawings.

FIG. 1 is a perspective view showing an embodiment of a tuning fork-shaped crystal resonator according to the present invention, and FIG. 2 is an explanatory diagram of the cutting angle from the coordinate axis of the crystal body of the crystal.

In Fig. 2, x, y, and z indicate the electrical, mechanical, and optical axes of the crystal, and a indicates the rotation angle α, e.g., α=2° to 6°, about the X axis. This is a cut out piece of crystal. The Y-axis and the X-axis before the rotation are defined as the Y'-axis and the Z'-axis after the rotation, respectively. Next, b is a crystal piece cut out by rotating it at an angle of 0, for example θ-6° to 10', with the Z' axis as the central axis, and before the rotation, the X axis, Y'
Let the axes be the X' axis and Y'' axis after rotation, respectively. Then, on the plane consisting of the X' axis and Y'' axis, the longitudinal direction is Y'
A crystal piece C forming a tuning fork shape with the axis and width direction as the X' axis and the thickness direction as the Z' axis is cut out.

Therefore, the X' axis in the width direction and the Z' axis in the thickness direction of the crystal piece C have an angle θ from the X axis of the crystal and an angle α from the X axis, respectively.

In FIG. 1, reference numeral 1 designates a tuning fork-shaped crystal piece having a notch 11 cut from the longitudinal end of the crystal piece C and a pair of vibrating arms 12 and 13 connected at a base 14. FIG. 1(b) shows the crystal piece 1 shown in FIG. 1(a) as indicated by the arrow A.
It is a perspective view shown from the opposite direction.

A pair of electrodes 12 are provided on the front and back surfaces of a portion of the crystal piece 1 at a predetermined length m from the L side of the length of one vibrating arm 12.
1.122 and electrodes 123 and 124 are arranged, and the vibrating arm 1
Electrodes 121 and 123 and electrodes 122 and 124, which face each other via 2, are connected by connection electrodes 125 and 126, respectively, and constitute polarity electrodes, respectively.

In addition, a pair of electrodes 131 are respectively provided on the front and back surfaces of a portion of the length 2 of the other vibrating arm 13 that is a predetermined length m from the −F direction.
．． 132 and electrodes 133 and 134 are arranged, and the vibrating arm 13
Electrodes 131 and 133, electrodes 132 and 1 facing each other via
34 are connected to connection electrodes 135 and 136, respectively, and constitute polarity electrodes.

FIG. 3(a) is a cross-sectional view taken along the cutting line I--■ shown in FIG. 1(a), and shows the cross section of the vibrating arm 12.

Next, on the front and back surfaces and both sides of the n portion (n=1-m) below the m portion of one vibrating arm 12 of the crystal piece 1,
electrodes 127a, 127b and electrode 128a, respectively;
128b is provided. Then, the electrodes 127a and 1
27b is connected to the connecting electrode 125, and the electrodes 128a and 128b are connected to the connecting electrode 129b so that they have the same polarity.

Furthermore, electrodes 137a and 1 are provided below the m portion of the other vibrating arm 13, and on the front and back surfaces and both side surfaces of the n portion, respectively.
37b and electrodes 138a, 138b are provided. The electrodes 137a and 137b are the connection electrode 1.
35, the electrodes 138a and 138b are connected to the connecting electrode 13.
The electrodes 9a are connected to each other so that the electrodes have the same polarity.

FIG. 3(b) is a sectional view taken along the cutting line U-1 shown in FIG. 1(a), and shows a cross section of a portion n of the vibrating arm 12.13.

Next, in FIG. 1, 129a provided on the base 14 of the crystal piece l is a connecting electrode that connects the electrode 127a and the electrode 138b, and 139b is a connecting electrode that connects the electrode 137b and the electrode 128a.
It is a connection electrode that connects the Therefore, the above-mentioned vibrating arm 1
The electrodes arranged in 2.13 are all connected to have a pair of electrodes. For example, the connection electrode 129a,
When lead wires 15 and 16 are connected to 139b and excited by a C-MO3 integrated circuit or the like, the crystal piece 1 vibrates as a tuning fork crystal resonator.

Next, the operation of this embodiment having such a configuration will be explained. A lead wire 15 is connected to each electrode arranged on the vibrating arm 12 and 13 of the crystal piece l from an oscillation circuit such as a C-MO3 integrated circuit.
．． When an excitation voltage is applied through 16, the vibrating arm 12.13
The electrodes 121, 123, 131 and 1 of the m portion of
33 is given one voltage of the same polarity, and the electrode 122
, 124, 132 and 134 are applied with the other voltage of the same polarity. Therefore, as shown in Figure 3 (0),
The vibrating arms 12,13 alternately twist and vibrate at a predetermined frequency. And since the main vibration of torsion is sliding vibration,
Its frequency-temperature characteristic becomes a curve as shown in FIG. 4A.

Further, by applying an excitation voltage to the lead wire 15.16, the electrode 127 is placed on the n portion of the vibrating arm 12.13.
a, 127b, 138a and 138b are of the same polarity, and electrode 128a.

The other voltage of the same polarity is applied to 128b, 137a and 137b. For this reason, as shown in FIG. 3(d), the vibrating arms 12 and 13 alternately bend and extend as if opening and closing in an inverted V shape, and vibrate at a predetermined frequency. The frequency-temperature characteristic of the vibration becomes a quadratic curve as shown in B of FIG.

Therefore, as a vibrator, the vibration of the vibrating arm 12.13 is m
By matching the torsional vibration frequency of the portion n with the bending vibration frequency of the n portion, a vibrator that vibrates in a predetermined frequency range is obtained.

The frequency-temperature characteristic is a combination of the frequency-temperature characteristics of A and B in FIG. 4, as shown in C in FIG. 4, and is a flat frequency-temperature characteristic over a wide temperature range. This is because the circular vibration mode is an entrainment phenomenon that occurs only when coupling occurs in a certain frequency range, and the characteristics of both modes are combined. In addition, vibrating arm 1
It is possible to change the frequency temperature characteristics by changing the ratio of the m part and the L part of 2 and 13, and in this example, m/n=1/3 to 2/3 (m+n=f) As, m
and n are selected to obtain a tuning fork crystal resonator with flat frequency-temperature characteristics over a wide temperature range.

Although the present invention has been described by way of one embodiment, various modifications can be made within the scope of the gist of the present invention, and these are not excluded from the scope of the present invention.

(Effects of the Invention) As explained in detail above, the present invention provides a cutting angle of the crystal piece with the X axis of the crystal tilted in the range of 0:=6° to
The Z axis of the crystal is cut as the Z' axis tilted within the range of α-2° to 6°, and each of the above-mentioned 'il poles is provided to form a tuning fork-shaped crystal vibrating r as a pongee vibration electrode [7 So 13. 1. The single-pronged crystal vibration r vibrates at a desired frequency in a vibration mode that is a combination of torsional vibration and bending vibration i, and its frequency temperature characteristics also vary over a wide range of temperature I parts. It is possible to increase +'I at a wide frequency temperature of 44).

Further, according to the present invention, the 1゛1 is small and has low power consumption.
- Since the advantages of the forked crystal vibration f can be maintained, it is possible to use long B when used on the arm and 11! False over fl'l
When ・is small, it is possible to provide ;1.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an embodiment of the B'f forked crystal resonator according to the present invention, Fig. 2 is an explanatory view of the cutting angle from the coordinate axis of the crystal, and Fig. 3 is a cross-sectional view of the vibrating arm. and an explanatory diagram of the vibration state, and FIG. 4 is a curve diagram showing the relationship between the frequency change rate of the crystal resonator and the temperature. l... Crystal piece, 12.13... Vibrating arm, 121.1
22,123,124,131,132.133,13
4... Electrode. 1 2 7 a, l 2 7 b,
1 2 8 a, l 2 8 b,
137a, 137b, 138a, 138b...
・Electrode, C...Crystal J1゜

Claims (1)

[Claims] In a tuning fork-shaped crystal resonator, the thickness direction of the crystal resonator is the Z' axis obtained by rotating the crystal by an angle of α (2° to 6°) about the x-axis of the crystal. It is made from a crystal piece cut out with the width direction of the X' axis obtained by rotating the angle of θ (6° to 10°) around the central axis, and is attached to the front and back surfaces and both sides of the vibrating arm that forms the tuning fork. A tuning fork crystal resonator, characterized in that electrodes are provided for producing torsional vibration in a predetermined part of the vibrating arm and bending vibration in another predetermined part.