KR830000246B1 - AT cut crystal oscillator - Google Patents

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Description

AT cut crystal oscillator

1 is a diagram showing the axial orientation of a spherical AT cut crystal oscillator according to the present invention.

2 is a perspective view of a spherical AT cut quartz crystal oscillator embodying the present invention.

3 is a diagram showing one embodiment of the temperature characteristic curve when the ratio w / t of the width width is 2.94.

4 is a diagram showing one embodiment of a frequency temperature characteristic curve when the ratio w / t of the width thickness is 3 or less.

5 is a correlation diagram between the inflection point temperature of the spherical AC cut oscillator and the ratio w / t of the width thickness according to the present invention.

FIG. 6 shows an embodiment of a frequency-temperature characteristic curve of a spherical AC cut oscillator. FIG.

7 is a correlation between the slope of the frequency-temperature characteristic curve at room temperature and the ratio of length to thickness l / t of the spherical AT cut according to the present invention.

8 is a correlation between the equivalent resistance at room temperature and the ratio of length to thickness l / t of a spherical AT cut quartz crystal oscillator embodying the present invention.

9 and 10 show frequency-temperature characteristic curves for implementing the present invention.

11 shows the temperature characteristic curve of a spherical AT cut quartz crystal when the parasitic vibration frequency of low response is near the main vibration frequency.

12A and 12B are mode chart diagrams.

Fig. 13 is a diagram showing a dimensional area for implementing the present invention.

14 is a side view showing the Y'-Z 'plane of the crystal piece inclined laterally.

FIG. 15 shows the correlation between the slope of the frequency-temperature characteristic curve and the ratio w / t of the width of the spherical AT cut crystal oscillator at room temperature.

16 is a correlation between the optimum cutting angle Q _O and the ratio w / t of the width of the spherical AT cut quartz crystal oscillator according to the present invention.

FIG. 17A is a correlation between the slope of a frequency-temperature characteristic curve at a room temperature of a spherical AT cut quartz crystal oscillator embodying the present invention and the ratio w / t of the width thickness. FIG.

FIG. 17B is a correlation between the optimum cutting angle Q _O and the ratio w / t of the width of the spherical AT-cut quartz crystal oscillator embodying the present invention. FIG.

18 is a view showing a rotation angle when the Y 'axis is the rotation axis.

사이의 상관도.Figure 19a shows the slope and rotation angle of the frequency-temperature characteristic curve

Correlation between.

사이의 상관도.19b shows the optimal cutting angle Q and the rotation angle.

Correlation between.

20 is a diagram showing a temperature characteristic curve of a spherical AT cut quartz crystal oscillator embodying the present invention.

The present invention relates to a spherical AT cut quartz crystal oscillator, in particular, having a good Q-temperature characteristic and a high Q value of a vibration frequency in which the vibration frequency of the parasitic vibration is sufficiently separated from the frequency of the thickening shear. The present invention relates to a small spherical AT cut crystal oscillator.

Background Art Conventionally, AT cut crystal oscillators have been widely used in communication equipment because of their excellent temperature characteristics, high Q values, and low equivalent resistance.

Conventionally used AT cut quartz crystal oscillators were usually disc shaped. If the ratio of the thickness-to-diameter ratio is not large, there is a strong defect between the vibration slipping to the main thickness and the parasitic vibration, and the frequency-temperature characteristics of the crystal oscillator are deteriorated so that the AT cut crystal oscillator has been limited in size.

On the other hand, a spherical AT cut oscillator has been proposed because it is advantageous in miniaturization.

According to Japanese Laid-Open Patent Publications 100991/74 and 97394/76, the ratio l / t of the length to the thickness of the crystal piece requires 30 or more. In the case where the angle between the principal plane (X-Z 'plane) and the side (X-Y' plane) of the crystal piece becomes substantially right angle, the frequency-temperature characteristic when the ratio w / t of the width to thickness of the crystal piece is less than 3 The temperature of the inflection point of the curve is gradually higher than that of an irrelevant AT cut crystal oscillator, and the temperature of the inflection point is about 40 ° when w / t is 3, which is not suitable for use at room temperature. An AT cut quartz crystal oscillator having a temperature characteristic curve of a cubic curve whose temperature of the inflection point at room temperature preferentially is about 20 ° is not yet invented, but is suitable for use in watches and portable electronic devices.

Therefore, it is small enough to be used for a watch, high Q value, low equivalent resistance, and inflection point temperature of the frequency-temperature characteristic curve is about 20 ° C., which maintains good frequency-temperature characteristics for practical use. It is an object of the present invention to provide a new spherical AT cut quartz crystal oscillator which is separated from the oscillation frequency at which the frequency slides to the main thickness and which is capable of processing, which is advantageous for mass production.

Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings. The description of the following embodiment is for the case of the wells using the spherical coordinate axes of the even system, but in the case of the left wells, the coordinate axes are replaced by the left system coordinate axes, and the related parts are replaced by the left system AT cut correction.

The elongated shape means that the XZ 'plane of the crystal piece is elongated in the direction of the X axis, close to the spherical shape in the model, and the edges of the spherical shape according to the present invention are rounded and somewhat semi-shaped. Also includes.

FIG. 1 is a diagram showing the axial direction of an elongated AT cut quartz crystal oscillator, for example, a spherical AT cut quartz crystal oscillator. 1 is a crystal. Rotate Crystal 1 upwards with a cutting angle Q (33 ° 20'-36 ° 20 ') around the X axis direction perpendicular to the ground and with the new axes X, Y', and Z '. In this case, the full length l, width w and maximum thickness t of the crystal piece are in the X-axis, Z'-, and Y'-axis directions, respectively.

The crystal piece 1 is formed into a spherical AT cut crystal oscillator by providing a metal film on the upper and lower surfaces of the X-Z 'surface of the crystal piece 1 by vapor deposition or spattering.

2 is a perspective view of a spherical AT cut quartz crystal oscillator showing an embodiment of the invention. Reference numeral 2 is a crystal piece, and the longitudinal direction and both ends 3 of the crystal piece 2 are in a bevel shape. The symbol l represents the length of the crystal piece, the symbol w represents the width, the symbol 1oβ represents the bevel angle, the symbol 1o represents the length of the bevel, and the symbol to represents the thickness of the end of the bevel portion.

The thickness t is a representative value of the thickness of the crystal piece provided in the electrode in order to excite the crystal piece with the vibration which slides in thickness.

The reason why both ends 3 are trimmed in a bevel shape is that the energy of the vibrations sliding in thickness is concentrated in the center of the surface of the crystal piece, so that the parasitic vibration is weakened and the Q value is prevented when the crystal piece is supported. Both tip portions 2 of the crystal piece have a block shape, for example, the thickness of the tip portion of the crystal piece can be trimmed to be thinner than the thickness of the main vibration part. In addition, the front end portion of the crystal oscillator 2 may be trimmed to form a plano bevel shape of a block shape.

For example, the spherical crystal oscillator may be provided with four deposited electrodes, namely, an electrode 4, deposited on the opposite X-Z 'surfaces of the crystal piece 2, and supporting the tip of the crystal piece 2 with a lead wire; The step of holding this in the container is completed.

로 주어진다. 단지, n은 오우버토운(overtone)의 차수이고, P는 밀도이며, C'55는 XY'Z' 구형 좌표축의 탄성정수이다. 폭 미끄럼 진동의 진동주파수가 두께 미끄럼 진동의 진동주파수 f와 같을때, 세장형상의 AT커트 수정 진동자의 경우에는 w/t가 1.5n으로 계산된다. 폭 미끄럼진동은 n이 기수일 때만 나타나는 것으로 생각되지만, 본 발명에 의하면, 폭 미끄럼 진동은 n=2일때, 즉 w/t=3일때 나타나서 두께 미끄럼 진동과 결합한다. 즉, 역시 우수의 폭 미끄럼 진동이 두께 미끄럼 진동의 주파수-온도 특성에 지대한 악영향을 주고 또한 Q값을 저하시킨다.The vibrations that slide in thickness are the main vibrations of the AT cut crystal oscillator, but there are also many parasitic vibrations such as contour vibrations. In order to improve the frequency-temperature characteristics of the main vibrations sliding with Q value and thickness, the effects of harmful parasitic vibrations should be avoided. Therefore, it is necessary to find a ratio of dimensions that sufficiently separate the parasitic vibrations of high and low response from the main vibrations that slide in thickness. As a result, it is necessary to first identify a high response parasitic vibration, i.e., width sliding vibration, which greatly affects the dimensioning of the width. The vibration frequency of the width sliding vibration is

Is given by Where n is the order of overtone, P is the density, and C'55 is the elastic constant of the XY'Z 'spherical coordinate axis. When the oscillation frequency of the width sliding vibration is equal to the oscillation frequency f of the thickness sliding vibration, w / t is calculated to be 1.5n in the case of an elongated AT cut quartz crystal. The width sliding vibration is thought to appear only when n is a base, but according to the present invention, the width sliding vibration appears when n = 2, that is, when w / t = 3, and is combined with the thickness sliding vibration. In other words, the excellent width sliding vibration also adversely affects the frequency-temperature characteristics of the thickness sliding vibration and lowers the Q value.

FIG. 3 shows the temperature characteristics of the thickness sliding vibration when w / t shown in FIG. 2 is almost 2.94. E denotes a frequency-temperature characteristic, and indicates a negative temperature characteristic having a large slope which is greatly affected by the width sliding vibration.

In the case of an AT cut quartz crystal, the cutting angle Q can be varied to adjust the frequency-temperature characteristics.

However, even when the cutting angle Q is changed by the ratio w / t of the width thickness, it is difficult to realize the frequency-temperature of the cubic curve that is flat near room temperature because the thickness sliding vibration is strongly coupled with the width sliding vibration.

In FIG. 3, F represents the temperature characteristic of the equivalent resistance Ki, and a decrease in the value caused by the large resistance influenced by the width sliding vibration is shown.

Therefore, when the ratio of the width thickness varied in the range of 3.0 to 1.5, the frequency-temperature characteristic of the thickness sliding vibration was investigated. The temperature of the inflection point indicates the temperature where the second derivative of the third curve is zero when the frequency-temperature characteristic is represented by the third curve.

4 is a diagram showing a frequency-temperature characteristic curve of the thickness sliding vibration, wherein the horizontal axis represents temperature, the vertical axis represents frequency change rate, and the reference temperature is 20 ° C. Curve G is frequency-temperature by theoretical calculation of irrelevant AT-cut crystal oscillator ("Adiabatic elastic constant of crystal and its temperature characteristics" by Masanao Ariga, Tokyo University of Technology, senes A Number 2, 1956) It is a characteristic curve and the temperature of an inflection point is about 28 degreeC. Curve H is a frequency-temperature characteristic curve when the ratio w / t of the width thickness thereof is about 2.87, and the temperature of the inflection point is about 43 ° C. Curve I is a frequency-temperature characteristic curve when the ratio w / t of its width thickness is about 1.94, and the temperature of the inflection point is about -7 ° C.

The relationship between the temperature of the inflection point when the temperature coefficient is 0 and the ratio w / t of the width thickness when examining the frequency-temperature characteristic curve shown in FIG. 4 is shown in FIG.

As shown in Fig. 5, the temperature of the inflection point and the ratio w / t of the width thickness are related to each other, and the horizontal axis in this figure is the ratio w / t of the width thickness and the vertical axis is the temperature of the inflection point.

As can be seen in FIG. 5, the temperature of the inflection point changes from low to high when the ratio w / t of the width thickness is in the vicinity of 1.5 where it meets the first width sliding vibration and 3.0 where it meets the secondary width sliding. Moreover, the temperature of the inflection point which was not feasible conventionally can be obtained.

In order to realize the practical use of the spherical AT cut vibrator with the good frequency-temperature characteristic curve in a communication device or an electronic watch, the temperature of the inflection point should be in the range of 35 ° C to 5 ° C, thereby making it possible to obtain a good frequency near room temperature. Temperature characteristics can be obtained.

6 shows the temperature change of the inflection point according to the present invention, where J, K, and L represent the frequency-temperature characteristic curves when the inflection point temperature is 35 ° C, 20 ° C, and 5 °, respectively.

As can be seen from the characteristic curve, in the temperature range of 0 ° to 40 ° C, the frequency change is in the range of 3 ppm, which is a good enough frequency-temperature characteristic for practical use in highly precise wrist watches. In particular, when the temperature of an inflection point is about 20 degreeC, it is preferable practically.

The ratio w / t of the width | variety thickness which satisfy | fills the temperature of an inflection point in the range of 35 degreeC-5 degreeC is set in the range of 2.0-2.8 in FIG.

An elongated AT cut quartz crystal with good frequency-temperature as shown in FIG. 6 can be obtained when the ratio w / t of the width to thickness is in the range of 2.0-2.8. On the other hand, as can be seen in FIG. 5, the dispersion at the inflection point temperature, at least, is large enough to produce the crystal oscillator no matter how much the ratio w / t of the width thickness varies in the range of 2.0-2.8. Does not affect When referring to the ratio of dimensions other than that of the present invention, when the ratio w / t of the width thickness is 2.8 or more, the temperature of the inflection point rises sharply, and when the w / t of the width thickness is 2.0 or less, the temperature of the inflection point drops sharply. Therefore, the temperature of the inflection point is far from room temperature, and furthermore, since the temperature of the inflection point is changed by slightly changing the ratio w / t of the width thickness, the production amount is considerably reduced when mass-producing the crystal oscillator.

On the other hand, the ratio of the width thickness according to the present invention is suitable for mass production and the temperature of the inflection point can be arbitrarily selected in the range of 5 ° C -35 ° C depending on the conditions under which the vibrator is used.

Then, the ratio of length to thickness will have to be determined. According to Japanese Unexamined Patent Publication No. 100991/74, it is difficult to put the crystal oscillator into practical use if the ratio l / t of the length to thickness is 30 or less. However, the vibrator used in a limited volume such as an electronic watch should be of small size. For example, when 1 / t is 30, the AT cut crystal oscillator of 4HMz is about 12 mm in length.

On the other hand, when the oscillation frequency is increased, current consumption in the oscillation circuit and the frequency division circuit generally increases, making it unsuitable for use in portable equipment.

Therefore, it is good that l / t of the vibrator is 25 or less, and the smaller the l / t, the more suitable the vibrator is for use in a portable watch. Now, to make a vibrator that can actually be used on a watch, select the length-thickness ratio l / t in the range 25-7 when w / t is in the range 2.0-1.8 to select the vibrator's frequency-temperature characteristics. The slope of the inflection point temperature and the frequency-temperature characteristic curve was investigated at room temperature. As a result, correlations showing substantially the same curves as those shown in FIGS. 5 and 15 were obtained at a plurality of l / t values. In addition, an elongated AT cut crystal oscillator with high Q value and low equivalent resistance can be obtained. In more detail, looking at the range of l / t from 25 to 7, the vibration characteristics of the vibrator are naturally affected by parasitic vibrations. Part of this experiment will be presented in FIG.

f/f)

t이다. 이 상관도는 폭대 두께의 비율 w/t가 2.5이고 길이대 두께의 비율 l/t가 12.9-6.7일때 구형 AT커트 수정 진동자의 데이터를 나타낸다. 상관도를 조사해보면, 길이대 두께의 비율 1/t가 충분히 작은 범위에서 몇개의 1/t의 비에 의해 안정한 주파수-온도 특성곡선의 기울기가 주어진다. 제9도의 상관도에 의하면, 길이대 두께의 비율 l/t가 12.9-6.7의 범위에 있을때 공진자를 실용화할 수 있는 몇개의 l/t의 비가 발견되었다.7 is the correlation between the slope of the frequency-temperature characteristic curve at room temperature and the ratio of length to thickness l / t, the horizontal axis of which is the ratio of length to thickness at l / t, and the vertical axis being the frequency at room temperature. Slope Q of the temperature characteristic curve

f / f)

t. This correlation represents the data of a spherical AT cut quartz crystal when the ratio w / t of the width to thickness is 2.5 and the ratio l / t of the length to thickness is 12.9-6.7. Examining the correlation, the slope of the stable frequency-temperature characteristic curve is given by several 1 / t ratios in a range where the length / thickness ratio 1 / t is sufficiently small. According to the correlation of FIG. 9, some ratios of l / t that can be used for the resonator are found when the ratio of length to thickness l / t is in the range of 12.9-6.7.

8 is a correlation between the equivalent series resistance R1 and the ratio l / t of the length to thickness of the spherical AT cut crystal oscillator, similarly to FIG. This data clearly shows a plurality of length-to-thickness ratios for practical application of the vibrator.

9 and 10 are frequency-temperature characteristic curves of the embodiment according to the present invention. In FIG. 9, 2G has a frequency of 4.2 MHz, w / t of about 2.3 (width w0.9 mm, thickness t ≒ 0.4 mm), and 1 / t of about 8.5 (length 1 ≒ 3.4 mm, thickness t ≒ 0.4 Mm), the bevel angle b is a frequency-temperature characteristic curve when the bevel angle b is about 7 ° 13 'and the bevel length Io is about 1 mm, and this characteristic curve is substantially equivalent to the temperature of the inflection point at 10 ° C and 138 Ω. Obtain the value of resistor R1.

On the other hand, 2H has a frequency of 4.2 MHz, w / t of about 2.5 (width w ≒ 1.0 mm, thickness t ≒ 0.4 mm), 1 / t of about 8.5 (length 1 ≒ 3.4 mm, thickness t ≒ 0.4 mm), bevel It is a frequency-temperature characteristic curve when β is about 7 ° 13 'and the bevel length Io is about 1 mm. This characteristic curve is used to determine the actual value of the inflection point at 18 ° C and the equivalent series resistance R1 at 130Ω. Get

In FIG. 10, 21 has a frequency of 4.2 HMz, w / t of about 2.3 (width w0.9 mm, thickness t ≒ 0.4 mm), and l / t of 9.3 (length 1 = 3.7 mm, thickness t ≒ 0.4 mm). ), The bevel angle β is about 7 ° 13 'and the bevel length Io is about 1mm, and this is the frequency-temperature characteristic curve, whereby the temperature of the inflection point at 10 ° C and the equivalent series resistance R1 at 130 Get the value.

In the above-described embodiment, the vibration characteristics of the bevel shape of the spherical AT cut quartz crystal oscillator are, as shown in Fig. 2, by attaching Cr and Au to Cr or Au thereon by vacuum deposition as the electrode shown in FIG. It was investigated in the step of supporting at, and vacuum sealing the crystal. The frequency-temperature characteristic curves as shown in FIGS. 9 and 10 are obtained at a plurality of sites in the range of the ratio w / t of the width thickness according to the present invention except for the sites adversely affected by parasitic resonance. The Q value of a vibrator conventionally used for watches is about when the ratio w / t of the width to thickness is in the range of 2.0 to 2.8 and the ratio 1 / t of the length to thickness is less than 25 (e.g. 25-7). A Q value of 180,000 and about 350,000 can be obtained. On the other hand, the value of the equivalent series resistance R1 of the vibrator according to the present invention is also small.

An embodiment of a spherical AT cut quartz crystal oscillator having a vibration frequency of a thick sliding main vibration and a high Q value sufficiently separated from the parasitic vibration frequency will now be described, further restricting the values of w / t and l / t.

When length 1 is determined by falling false vibration along the length (this is a high response false vibration), the frequency of what is determined by length should be virtually different in the thickness sliding main vibration.

The vibration frequency of the refraction vibration is given by the following equation.

Where n = order of the overhaul (excellent), P = correction of the crystal

In the case of a spherical AT cut crystal oscillator, when l / t is less than 25, it can be preferentially used in an electronic watch, but if the value of l / t is too small, the Q value is lowered. It is preferred that the value is in the range of n = 18 and n = 12.

The flexural vibration frequency is equal to the main vibration frequency when n = 18 and n = 20, and the length-to-thickness ratio 1 / t when n = 18 and n = 20 is calculated as 14.5 and 16.2 and selects the median thereof. .

In other words, when l / t is the median of 14.5 and 16.2, the weak effect of parasitic vibration can be avoided. When the width-to-thickness ratio w / t of the horizontal piece is 2.5 and its length-to-thickness ratio l / t is a median of 14.5 and 16.2, the thickness sliding vibration is a high response parasitic vibration such as the width sliding vibration and the thickness sliding vibration. Not affected by medicinal effects.

However, there are many parasitic vibrations of low response other than wide sliding vibration and flexural vibration.

11 is a temperature characteristic curve of a spherical AT cut crystal oscillator when the parasitic vibration frequency is in the vicinity of the main vibration that slips in thickness.

Curves M and N respectively represent the frequency-temperature characteristic curve and the temperature characteristic curve of the equivalent series resistance R1.

Discontinuity points in the frequency-temperature characteristic curve occur when the main vibration sliding in thickness due to temperature changes crosses the parasitic vibration frequency of low response.

Spherical AT cut crystal oscillators with these characteristics are not suitable for practical use. Also, in order to improve the Q-value and frequency-temperature characteristics of the spherical AT cut crystal oscillator, the low response parasitic vibration frequency should be separated from the thickness sliding main vibration. Therefore, in order to investigate in detail the low response parasitic vibration of the spherical AT cut quartz crystal oscillator, as shown in FIG. 2, w of crystal 2 according to the present invention selected as w / t = 2.5 and 1 / t = 15.25, respectively. The values of / t and 1 / t were changed fractionally.

12 (a) and 12 (b) are the mode charts showing the change in the frequency response when the phone w and the length 1 are changed, respectively, and the straight line group connects the measured values. It means the frequency constant ft. The straight line P shown in Figs. 12 (a) and 12 (b) is the main vibration of the sliding thickness, and its frequency constant is about 1666.5 KMz.mm.

Straight lines other than the straight line P are parasitic vibrations, and their vibration modes are unclear, but the slopes of the frequency constants for w / t and 1 / t are experimentally obtained. The inclination of this straight line is represented by a nearly straight line in the range of the micro area.

The parasitic vibrations to be aware of when determining w / t and 1 / t are the straight lines Q, R, S and U. Here, the parasitic vibration frequencies represented by the straight lines Q, R, S and U are f _Q , f _R , f _S and f _U, respectively.

The frequency constants of four parasitic vibrations are expressed as a function of w / t and l / t:

In order to prevent the thickness sliding vibration P from being affected by the four parasitic vibrations, the following formula must be satisfied when the frequency constant of the main vibration is f _P ㆍ t (where f _P is the main vibration frequency).

f_Qㆍt f_Pㆍt

f_Rㆍt f_Pㆍt

f_Sㆍt f_Pㆍt

f_Uㆍtf _P

f _Q ㆍ tf _P ㆍ t

f _R ㆍ tf _P ㆍ t

f _S tf _P t

f _U t

The frequency of the thickness sliding vibration P can be adjusted by the thickness of the electrode. Since the frequency drop caused by the thickness of the electrode is larger than that of the parasitic vibration, the change of the frequency constant can be as high as ± 10 KHz.mm.

Therefore, the above conditions can be expressed by the following equation.

f_Qㆍt f_Pㆍt+10

f_Rㆍt f_Pㆍt-10

f_Sㆍt f_Pㆍt-10

f_Uㆍtf _P t + 10

f _Q ㆍ tf _P ㆍ t + 10

f _R ㆍ tf _P ㆍ t-10

f _S ㆍ tf _P ㆍ t-10

f _U t

therefore,

When w / t and l / t of the spherical AT cut crystal oscillator satisfy the above four equations, strong parasitic vibrations such as wide sliding vibration and bending vibration can be eliminated, and at the same time, the 12th (a) and the As shown in Fig. 12 (b), the main vibration frequency can be separated from the weak parasitic vibration frequency.

FIG. 13 shows the ratio w / t and 1 / t of the dimensions satisfying the above four equations by implementing the present invention, the horizontal axis of which is w / t and the vertical axis of which is wl / t. If the coordinate point on this graph is expressed as (/ t, l / t), point A is (2.41, 15.69), point B is (2.58, 15.56), point C is (2.66, 14.98), and point D is (2.41, 14.98). The area inside the quadrangle consisting of these coordinate points A, B, C, and D satisfies the spherical AT cut crystal oscillator of the present invention and is also separated from the weak parasitic vibration.

FIG. 14 shows Crystalline 5 according to the invention which is the side of Crystalline 2 and is marked with an X-Y 'plane inclined counterclockwise by α (about 5 ° C) around the X-axis perpendicular to the ground and upwards. .

According to the above-mentioned JP Patent Publication, when the ratio w / t of the width thickness is in the range of 1-8, the temperature of the inflection point of the frequency-temperature characteristic curve is the temperature of the theoretical value of the infinite plate (about 25 °). Since they are about the same, the sides of the crystal are inclined to equalize the frequency-temperature characteristics of the crystal oscillator with that of the infinite plate. However, even if the vibrator according to the present invention is inclined at an inclination angle (about 6 ° 27 '), the temperature of the inflection point of the frequency-temperature characteristic curve is the same as the curve shown in FIG. When measuring the intensity of the frequency response in each case by varying the width w and length l of the spherical AT cut quartz crystal oscillator with its side slanted in a small range, the frequency response is shown in FIGS. As shown in (b), the side of the crystal oscillator was almost the same. This time, the dimension of the width of the spherical AT cut crystal oscillator inclined side is w or the upper or lower surface of the X-Z 'plane as shown in FIG.

Thus, by selecting the length l and width w of the laterally inclined spherical AT cut crystal oscillator in the areas of rectangles A, B, C and D shown in FIG. 13, w / t and l / t are further restricted and response Regardless of the hardness, the spherical AT cut crystal oscillator which is not affected by the parasitic vibration, that is, the present invention can be realized.

에서의 주파수-온도 특성곡선의 기울기이다.FIG. 15 is the correlation between the ratio w / t of the width to thickness of the crystal oscillator and the slope of the frequency-temperature characteristic curve at room temperature when l / t = 15.25 and θ = 34 ° 43 ', and the horizontal axis represents the width to thickness Ratio w / t and the vertical axis is

The slope of the frequency-temperature characteristic curve at.

Curve 2A is when the angle formed between the main surface (X-Z 'plane) and the side surface (X-Y' plane) is almost right angle, that is, when the inclination angle α shown in Fig. 14 is almost 0 °. The width w is reduced by polishing the side of the sample with w / t of 3.3, and the values obtained by investigating the temperature change characteristic of the main vibration and calculating the slope of the frequency temperature characteristic curve near room temperature are combined.

Curves 2B, 2C, and 2D show the X-Y 'plane, which is the side of the crystal, with the forward direction of the X axis above the ground, about 6 ° 27' to the right, about 6 ° 27 'to the left, and about 10 ° 40' to the left. With respect to the inclined crystal piece, a sample of w / t = 2.6 was polished and reduced in width w, and the values obtained by investigating the frequency temperature characteristics at each time and calculating the inclination near the normal temperature of the frequency temperature characteristic curve were combined.

The slope of curve 2A in FIG. 15 is extremely large when w / t is less than 2.0 or around 3.0. If the slope of the frequency-temperature characteristic curve is large, the machining accuracy of the ratio w / t of the width to thickness becomes more difficult, and the mass production of the crystal piece becomes more difficult. That is, the slope of the frequency-temperature characteristic curve is relatively flat when w / t is in the range between 2.0 and 2.8. When w / t is in the range from 2.0 to 2.8, you can mass-produce quartz pins in terms of machining accuracy. On the other hand, when comparing the inclination of the horizontal planes 2B, 2C, and 2D in which the side of X-Y 'plane is inclined by α ° in FIG. 15 with the slope of curve 2A, the slope of curve 213 is greater than the slope of curve 2A, and the curve 2C And the slope of 2D is flatter than the slope of curve 2A. In particular, since the slope of curve 2C is very flat, the crystal piece having curve 2C is suitable for mass production in view of the degree of processing. When the side of the crystal, which is the plane X-Y ', is inclined counterclockwise by α (in the range of 0 ° to 10 ° 40') perpendicular to the ground and upward, as shown in FIG. In light of the degree of processing, mass production of crystal pieces is advantageous, and the output of mass production is increased.

A crystal oscillator with a width-to-thickness ratio w / t in the range of 2.0 to 2.8 is well suited for use in electronic clocks and electronic devices mainly used at room temperature, considering the temperature of the inflection point. However, for example, when an AT cut crystal oscillator having a temperature of an inflection point of 5 ° or less is required, if the α of FIG. 14 is about 6 ° 30 ', the ratio of the width thickness may be 2.0 or less.

FIG. 16 is a correlation chart between the optimum cutting angle and the ratio of the width thickness w / t among the cutting angles θ shown in FIG. 1 for the frequency-temperature characteristic curve shown in FIG. 4, and the horizontal axis is the ratio of the width thickness ratio w / t. The vertical axis is the optimum cutting angle θ ₀ for obtaining the frequency-temperature characteristic curve shown in FIG. 4. Curves 2J, 2K, 2L, and 2M show the ratio of the optimum cutting angle θ _{0 to the} large thickness of the same crystal piece as the crystal piece showing the frequency-temperature characteristic curves 2A, 2B, 2C, and 2D of FIG.

The optimal cutting angle θ ₀ of an elongated AT cut quartz crystal oscillator where the principal plane (XZ 'plane) and the side surface (XY' plane) meet at substantially right angles (that is, α of FIG. 14 is substantially 0 °) is the curve J of FIG. Is actually 33 ° 20 'when w / t is 2.0 and 34 ° 55' when w / t is 2.8. In the correlation chart of FIG. 16, the optimum cutting angle Q is in the range of about 33 ° 20 'to 34 ° 55' corresponding to the value of each w / t when the ratio of the width w / t is in the range of 2.0 to 2.8. Is selected.

On the other hand, if the angle α is in the range of 0 ° to 10 ° 40 'inclined counterclockwise along the upward X-axis perpendicular to the ground, the range of change of the cutting angle for the ratio w / t of the width is narrowed and corrected. The vibrator is suitable for mass production. In particular, when α is 6 ° 27 ', the optimum cutting angle θ ₀ is almost fixed even when the width w / t of the width is slightly disturbed when the crystal oscillator is processed. If α is in the range of 0 ° to 10 ° 10 'perpendicular to the ground and inclined counterclockwise along the upward X axis, a range of about 33 ° 20' to 36 ° 20 'corresponding to the value of each w / t Select the range of change of the optimal cutting angle θ ₀ at.

17 (a) shows the ratio w / t of the width of the spherical AT cut quartz crystal oscillator further restricting w / t and l / t according to the embodiment of the present invention. The slope of the frequency-temperature characteristic curve at room temperature when the angle α, which is the angle between and the side (X-Y ') plane, is nearly right, l / t is 15.25, and θ is 34 ° 53', in the range 2.41 to 2.66 Indicates.

Fig. 17 (b) shows the correlation between the optimum cutting angle θo showing the flat frequency-temperature characteristics at room temperature and the ratio w / t of the width of the spherical AT cut crystal oscillator shown in Fig. 17 (a).

As shown in FIG. 17 (b), the spherical AT-cut quartz crystal oscillator showing a flat frequency-temperature characteristic curve at room temperature according to the present invention is an easy treatment method when θo is in the range of 34 ° 53 'according to w / t. Can be mass-produced. If the side of the crystal, which is the X-Y 'plane, is inclined at α ° in the range of 0 ° to 10 ° 40' along the upward X axis as shown in Figure 14, then the mass of the crystal can be mass-produced. Yields can be improved. Selecting the optimum cutting angle θo in the range of 34 ° 35'-35 ° 25 'when rotating the crystal counterclockwise α ° in the range 0 ° to 10 ° 40' along the upward X axis to the ground The preferred frequency-temperature characteristic curve showing a smooth curve at room temperature is realized over the ratio w / t of the width of the spherical AT cut crystal oscillator implementing the present invention in the range of 2.41-2.66.

In particular, in the case of α = 6 ° 27 ', the optimum cutting angle θo does not change even when w / t is dispersed when the crystal oscillator is processed.

FIG. 18 is a spherical AT cut crystal oscillator of the present invention, and is a plan view showing the rotation angle ψ between the longitudinal direction 1 and the X axis of the quartz crystal 6 when the Y 'axis is the rotation axis. Here, 7 denotes an excitation electrode, and 8 denotes a bevel portion.

에서의 주파수-온도 특성곡선의 기울기이다. 제19(a)도에서 절단각은 34°48'이다.19 (a) shows the frequency at room temperature of the spherical AT cut quartz crystal oscillator of FIG. 2 in which the rotation angle was changed when the ratio w / t of the width to thickness was 2.5 and the ratio 1 / t of the length to the thickness was 12.25. The correlation chart between the slope of the slope of the temperature characteristic curve and the rotation angle ψ, the horizontal axis of which is the rotation angle ψ shown in FIG.

The slope of the frequency-temperature characteristic curve at. In Fig. 19 (a), the cutting angle is 34 ° 48 '.

19 (b) is a correlation chart showing the optimum cutting angle θo and the rotation angle ψ in order to obtain a flat frequency-temperature characteristic curve at room temperature. As shown in Figs. 19 (a) and 19 (b), when the rotation angle is 18 ° or more, the slope of the frequency-temperature characteristic curve becomes severe.

In the case of the AT cut quartz crystal oscillator according to the present invention, the machining tolerance is not severe if it is in the direction of the X axis almost in the longitudinal direction of the crystal, that is, in the range of ± 18 ° from the X axis when the Y axis is the rotary axis. The optimal cutting angle θ ° is chosen as the rotation angle ψ. The parasitic vibration frequency varies somewhat with the rotation angle ψ, but the dimensional area according to the present invention shown in FIG. 13 does not change if ψ = 0 ° ± 18 °. The AT cut oscillator with the tip in the longitudinal direction of the bevel-shaped crystal piece has been exemplified so far, and the ratio of length to thickness l / t and width of the vibrator in the squares A, B, C, D and the region shown in FIG. The bevel length lo and the tip thickness of the spherical AT cut oscillator implementing the present invention, including the ratio w / t, are not adversely affected by parasitic vibration as long as lo / l and to / t satisfy the following equation: It shows the third-order curve of the flat frequency-temperature characteristics near the room temperature, which is specific to the AT-cut crystal oscillator.

lo/l

0.320.08

lo / l

0.32

to/t

0.850.15

to / t

0.85

An important factor of this equation is the ratio w / t of the width thickness to the ratio l / t of the length large thickness, so that each part of the crystal oscillator processed to have a plano block shape or plano bevel shape is also referred to as the square A mentioned above. , B, C, and D are satisfied. The tip of the crystal oscillator in the axial direction processed to have a bevel shape in the form of a block is effective in maintaining a high Q value because the Q value decreases little when the vibrator is supported by the longitudinal end.

20 is a temperature characteristic curve of a spherical AT cut crystal oscillator embodying the present invention. Curves 2E and 2F are the frequency-temperature characteristic curve and the temperature characteristic curve of equivalent station R1, respectively. The temperature characteristic curve shown in FIG. 20 is for a sample with θ = 34 ° 48 ', l / t = 15.3, w / t = 2.52, α = 0 °. In the dimensional domain of the present invention where the high response wide sliding frequency and flexural vibration frequency and the low response parasitic vibration frequency are sufficiently separated from the main vibration frequency, a good frequency-temperature characteristic curve as shown in FIG. The frequency characteristic of the equivalent resistance can be obtained. In FIG. 15, the temperature of the inflection point of the temperature characteristic curve is about 20 ° C. When the thickness and the main vibration frequency are about 0.4 mm and 4 HMz, respectively, an extremely small spherical AT cut crystal oscillator having a thickness of about 1 mm and a length of about 6.1 mm can be obtained.

According to the present invention thus far exemplified, by selecting the ratio w / t of the width of the crystal piece in the range of 2.0-2.8, the high Q value, the low equivalent resistance and the inflection point of the frequency-temperature characteristic curve in the range of 5 ° C-35 ° C A small, elongated AT-cut crystal oscillator with a temperature of can be obtained. Furthermore, by limiting the dimensional ratios w / t and l / t within the range of the squares defined by the four points A, B, C, and D, the inflection point temperature of the frequency-temperature characteristic curve is around 20 ° C without being affected by parasitic vibrations. It is possible to provide a small spherical AT cut crystal oscillator which can be mass-produced in view of the processing accuracy. As a result, the primary object of the present invention has been sufficiently achieved.

Claims (1)

In the AT cut quartz crystal oscillator obtained by rotating the quartz plate by the cut angle of about 33 ° 20 'to about 36 ° 20' counterclockwise around the X axis, the length l of the quartz plate in the X-axis direction and the width w in Z In the 'axial direction, the thickness t is selected in the Y' axis direction, and the width-thickness ratio w / t is selected in the range of 2.0-2.8 and the length-to-thickness dimension ratio l / t is 25 or less. AT cut crystal oscillator.

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