JPH05102779A - HT cut crystal unit - Google Patents

Abstract

(57) [Summary] [Object] An object of the present invention is to improve the characteristics by preventing vibration leakage of an HT-cut quartz resonator, and by processing by a photolithography method, to improve the dimensional accuracy in miniaturization. An object of the present invention is to provide an HT-cut crystal unit that is excellent and has achieved cost reduction. [Structure] Cutting direction (yxl) is + 34 ° from 30 '+
In an HT-cut quartz crystal unit at 39 ° 30 'and a support frame part is integrally molded from the oscillator part, when the inclination angle θ between the parallel part of the longitudinal direction of the diaphragm part and the damping part is 30 °, the oscillator part The HT-cut crystal resonator has a ratio L / W of the length L and the width W within the range of 3.1 to 3.7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an HT-cut crystal oscillator which prevents vibration leakage and improves various characteristics to achieve miniaturization.

[0002]

2. Description of the Related Art A crystal oscillator is most widely used as a piezoelectric oscillator. 0.8 using this crystal oscillator
When obtaining a low frequency band of up to several MHz, it has been difficult to manufacture since it hits the boundary between the contour vibration system and the thickness shear vibration system. In other words, in the contour vibration system, the shape is too small and it is difficult to process, and because the influence of the support occupies a large weight on the performance of the crystal unit, it was not satisfactory. On the other hand, in the case of a thickness-sliding vibration system, the influence of support is small, but since the frequency is inversely proportional to the thickness, the thickness inevitably becomes thick when this low frequency band is obtained, and the shape also becomes too large with it. There was a problem in miniaturization. In addition, in order to achieve miniaturization and higher precision, it is assumed that a large number of quartz resonators are simultaneously molded by photolithography, and it is important to mold this low frequency band with a thickness-sliding vibration system. However, in the case of a contour vibration system, it is possible to reduce the thickness of the crystal unit because the frequency hardly contributes to the thickness. It is convenient to process the method, and the present invention deals with the contour vibration system. Square-shaped CT cuts and DT cuts have been conventionally known as this contour vibration system, but in order to further reduce the size, the X-axis direction is made longer than the Z-axis direction, so-called strip-shaped HT cuts and SL cuts. There is. In the present invention, the HT-cut crystal oscillator among them is taken up. This HT-cut crystal unit has conventionally been supported and electrically led to the central portion of the main surface of the crystal unit by a wire line, but as the size of the HT-cut crystal unit becomes smaller, there are problems in manufacturing and structure. Instead of this, processing is performed by a photolithography method and formation is performed by energy trapping. Conventionally, as shown in FIG. 4, an attenuating portion 44 having a width that narrows as it extends in the length direction from the short side of the vibrating plate portion 43 is formed and fixed at the end of the attenuating portion. However, there is a risk of receiving stress from the retainer when supporting the retainer. Therefore, as shown in FIG. 5, the end of the damping portion 54 is connected to the support frame portion 52 surrounding the vibrator portion, and the through hole 55 is provided so as not to propagate the vibration to the support frame portion. Has the drawback of becoming large.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in order to improve the above-mentioned drawbacks, and improves characteristics by preventing vibration leakage of an HT-cut crystal unit, and a photolithography method. The present invention intends to obtain an HT-cut crystal resonator that is formed with good dimensional accuracy and achieves cost reduction when it is downsized.

[0004]

The present invention is directed to a cutting orientation (y
xl) is in the range of + 34 ° 30 ′ to + 39 ° 30 ′, and in the HT-cut quartz crystal unit in which the vibrator part and the support frame part are integrally molded, the inclination angle θ between the parallel part of the diaphragm plate length and the damping part is The length L and the width W of the vibrator part around 30 °
Is a HT-cut quartz crystal resonator having a ratio L / W within the range of 3.1 to 3.7.

[0005]

EXAMPLE FIG. 1 is a plan view showing this example. HT
Since the cut crystal unit 10 is formed by the photolithography method, it has a thickness of several tens of microns. The cut angle is the cutting direction (y
xl) is from + 34 ° 30 'to + 39 ° 30'. The vibrator portion 11 and the support frame portion 12 are formed, and the vibrator portion 11 includes a rectangular diaphragm portion 13 in the center and an attenuating portion 14 whose width dimension decreases in the longitudinal direction.
From the attenuating portion 14, a bridge portion 15 that is a part of the support frame portion 12
To the support frame portion 12, and the vibrator portion 11 is attached to the support frame portion.
It surrounds the whole. In the figure, the length L and the width W of the vibrator portion 11, the length l of the diaphragm portion 13, the inclination angle between the longitudinal direction of the diaphragm portion 13 and the damping portion 14 are represented by θ. The diagonal lines are
An excitation electrode for exciting the diaphragm 13 and an extraction electrode for electrically leading to the outside are shown.

FIG. 2 shows the HT-cut crystal unit 10 of FIG.
, And the inclination angle θ between the parallel part of the vibrator and the damping part
Around 30 °, CI (Crystal Imp
is a correlation diagram showing the optimum value of the
The ratio L of the length L and the width W of the vibrator part around 30 °
FIG. 3 shows a correlation diagram with the CI value of the SL cut crystal resonator 10 with respect to / W. Figure 3 is a graph of the quadratic function,
The CI value is 2 KΩ or less when the side ratio L / W is 3.1 to 3.7. The smaller the CI value, the better, but 2k
When it is Ω or less, the current consumption of the circuit is small and it is good. As the best range, the side ratio L / W is 3.4 to 3.5.
It is good to do.

[0007]

According to the present invention, the optimum value of the side ratio of the HT-cut crystal unit is found, and the tilt angle is increased,
The attenuator is shorter, which is advantageous for downsizing. As a result, the CI value, which is one of the characteristics of the crystal unit, can be lowered, and the characteristics of the crystal unit can be sufficiently brought out. Further, in the present invention, the support frame portion that combines protection and support from the outside of the vibrator portion is formed integrally with the vibrator portion, whereby vibration of the support plate portion is trapped by energy, and vibration leakage is further caused. It goes through a damping part and a bridging part so that it does not occur, and it is devised so that the loss of vibration is not transmitted to the support frame part, and the characteristics of the vibrator part can be fully drawn out. Contrary to the case of conventional through holes only, the measures against vibration leakage are prevented by the bridging part, so it is possible to prevent deterioration of the characteristics and thereby to electrically draw out to the support frame terminal side. Even if it is fixed to a retainer such as a base, the measure against vibration leakage is taken, so that it is possible to mass-produce a uniform product without producing a characteristic difference and reduce the cost.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of the present invention.

FIG. 2 is a correlation diagram between a tilt angle and a CI value.

FIG. 3 is a correlation diagram of a ratio L / W of a vibrator portion length L and a width W and a CI value.

FIG. 4 is a perspective view of a conventional HT-cut crystal diaphragm part.

FIG. 5 is a plan view of a conventional HT-cut crystal unit.

[Explanation of symbols]

 10 HT-cut crystal oscillator 11 Oscillator part 12 Support frame part 14 Attenuation part 15 Bridging part L Length of oscillator part W Width of oscillator part θ Inclination angle

Claims (1)

[Claims] 1. An HT-cut quartz crystal resonator having a cutting direction (yxl) in the range of + 34 ° 30 ′ to + 39 ° 30 ′ and a vibrator part and a support frame part integrally formed with a parallel part of the length of the diaphragm part. The ratio L / W between the length L and the width W of the vibrator portion is 3.1 to 3.
An HT-cut crystal unit characterized by being in the range of 7.