JPH04102318U - Rectangular AT cut crystal oscillator - Google Patents

Abstract

(57) [Summary] [Purpose] An unprecedented small rectangular A with good frequency-temperature characteristics without coupling of thickness shear vibration and high-order contour vibration.
Obtain a T-cut crystal resonator. [Configuration] The approximate length L of the crystal resonator in the X-axis direction is 3 to 6
[mm], the width Wz [mm] in the approximate Z-axis direction when the vibration frequency f is in the range of 28 to 29 [MHz], and the vibration frequency is in the range of 28≦f<28.52 [MHz]. is (f-27.89)/0.21≦Wz≦3.0, and for the vibration frequency range of 28.11≦f≦29 [MHz], 1.0≦Wz≦(f- 27.70)/0.41. Within this range of conditions, coupling between thickness shear vibration and high-order contour vibration does not occur.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This invention aims to specifically reduce the size of an AT-cut crystal resonator with a rectangular shape. related to improvements.

0002

[Problems to be solved by conventional technology and ideas]

A rectangular AT-cut crystal resonator has a shape as shown in FIG. 3, for example. Obtained by rotating the +X axis towards you and to the left by a cutting angle θ (approximately 35°). crystal oscillator 10 The length is represented by L, the width is represented by Wz, and the thickness is represented by t. By the way, recently, electronic devices have become smaller and lighter, and crystal oscillation There is also a strong demand for smaller and lighter electronic components such as electronic components. However, the crystal oscillator In this case, the smaller the size, the more it is possible to avoid coupling between thickness shear vibration and high-order contour vibration. The problem is that it becomes difficult to

FIG. 4 shows an example of frequency-temperature characteristics of a rectangular AT-cut crystal resonator. In the figure, the horizontal axis is temperature, and the vertical axis is frequency deviation (ratio of vibration frequency variation Δf to specified vibration frequency f ₀ ). Moreover, the solid line shows the case where there is a combination of high-order contour vibrations, and the curve changes discontinuously. On the other hand, the dashed line is the case without such a connection and is a smooth cubic curve. As shown in this figure, depending on the combination of the side ratio of the length L and width Wz of the rectangular AT-cut crystal resonator, coupling with higher-order contour vibration occurs, resulting in discontinuous changes in the vibration frequency.

0004 As mentioned above, this kind of coupling between thickness-shear vibration and higher-order contour vibration is The smaller the vibrator is, the more likely it is to occur. For this reason, conventionally, crystal oscillators It has a relatively large shape. For example, the length is about 8mm and the width is about 3mm. It becomes. However, this size is sufficient for miniaturizing electronic devices. It's not something you get. In addition, in the past, the width Wz was changed by trial and error, and the above-mentioned vibration coupling was eliminated. I was looking for Hebi. For this reason, determining the shape takes time and is inefficient. This invention focuses on this point, and combines thickness shear vibration and high-order contour vibration. It has excellent frequency-temperature characteristics and the ability to achieve unprecedented miniaturization. The objective is to provide an efficient rectangular AT-cut crystal resonator.

[0005]

[Means and actions to solve the problem]

In this invention, the length L of the crystal resonator in the approximately X-axis direction is 4 to 5 [mm], and the vibration frequency is When f is in the range of 28 to 29 [MHz], approximately the width Wz [mm] in the Z-axis direction is , for the vibration frequency range of 28≦f<28.52 [MHz], (f-27.89)/0.21≦Wz≦3.0 And for the vibration frequency range of 28.11≦f≦29 [MHz], 1.0≦Wz≦(f-27.70)/0.41 It is characterized by the following. Within this range of conditions, thickness-shear vibrations and higher-order contour vibrations No combination with motion occurs.

[0006]

【Example】

Below, an example of the rectangular AT-cut crystal resonator according to the present invention is shown in the accompanying drawings. This will be explained with reference to. Note that the components similar to or equivalent to the conventional example described above are In this case, the same reference numerals will be used. In this example, first, we will discuss the frequency temperature characteristics and width Wz (see Fig. 3) of high-order contour vibration. The relationship between can be investigated. Figure 2 shows a rectangular AT-cut crystal with a frequency of 28 to 29 [MHz]. The measurement results of the vibration frequency and width Wz of the high-order contour vibration generated in the mover are shown. . In the figure, the horizontal axis is the vibration frequency f, and the vertical axis is the width Wz. Also, “−△−” is the temperature If the temperature is 80 [℃], "-×-" means the temperature is 25 [℃], "-○-" means the temperature. This is the case when the temperature is -20 [°C]. In addition, the length L is 4.5 [mm], and the thickness t is 0.0 It is 576 to 0.0596 [mm].

[0007] In addition, the relationship between the thickness t [mm] of the crystal resonator 10 and the vibration frequency f [MHz] is generally, f=n・1.67/t becomes. However, n is a vibration mode, and n=1, 2, . . . . As a result, f= The thickness t in the case of 28 to 29 [MHz] is 0.0576 to 0.0 as described above. It becomes 596 [mm].

[0008] As shown in this figure, at any temperature, as the width Wz increases, the The vibration frequency f of the next contour vibration also tends to increase. Also, keep the width Wz constant and When the temperature is changed from -20 [°C] to 80 [°C], the vibration frequency f becomes lower. Therefore, at the normal operating temperature of -20 to 80 [℃], the figures are shown with diagonal lines. In this range, coupling of higher-order contour vibrations occurs. However, in other ranges, higher order There is no coupling between contour vibration and thickness shear vibration, and cubic curve smoothness without frequency discontinuity. It has a smooth frequency temperature characteristic.

[0009] Next, from the above results, we can determine the width Wz without coupling of thickness shear vibration and higher-order contour vibration. Calculating the range looks like this: In the graph of Figure 2, the temperature is -20 [℃], Let the straight lines at 25 [°C] and 80 [°C] be graphs GA, GB, and GC. And this Approximating GA and GC in these graphs using mathematical formulas, first, the -20[℃] group Rough GA is Wz=(f-27.89)/0.21...(1) So, the graph GC at 80[℃] is Wz=(f-27.70)/0.41...(2) becomes. These equations indicate the boundaries of the range in which coupling of higher-order contour vibrations occurs. That means that.

0010 Next, consider the length L, thickness t, and other characteristics of the crystal resonator 10. As a result of measurements, it was found that coupling with higher-order contour vibration does not occur within the following range. found. Note that the length L of the crystal resonator 10 is 4 to 5 [mm], and the thickness t is 0.05 76 to 0.0596 [mm]. The vibration frequency f is in the range of 28 to 29 [MHz]. Ru. First, if the vibration frequency is 28≦f≦28.52 [MHz], (f-27.89)/0.21≦Wz≦3.0…(3) The range is . Next, when the vibration frequency is 28.11≦f≦29 [MHz], 1.0≦Wz≦(f-27.70)/0.41...(4) The range is .

[0011] For example, the width W of the crystal resonator 10 with a vibration frequency of f=28.636 [MHz] From the above formula (4), z is 1.0≦Wz≦(28.636-27.70)/0.41 This calculation results in a range of 1.0≦Wz≦2.28 [mm]. Ta For example, the frequency temperature characteristics when the width Wz is 1.8 [mm] are shown in the graph in Figure 1. As shown in GD, no coupling of higher-order contour vibrations is observed.

0012 Further, for example, a crystal resonator 10 with a vibration frequency of f=28.375 [MHz] From the formula (3) above, the width Wz of (28.375-27.89)/0.21≦Wz≦3.0 This calculation results in a range of 2.3≦Wz≦3.0 [mm]. and For example, the frequency temperature characteristic when the width Wz is 2.5 [mm] is shown in graph G in Figure 1. As shown in E, similarly, no coupling of higher-order contour vibrations is observed. In addition, in this case The width Wz may be calculated from equation (4), 1.0≦Wz≦(28.375-27.70)/0.41 becomes. When calculated, the range is 1.0≦Wz≦1.65 [mm].

[0013] As described above, according to this embodiment, the frequency of 28 to 29 [MHz] with excellent frequency temperature characteristics is ], the width Wz of the rectangular AT-cut crystal resonator in the frequency band is expressed as It becomes possible to make decisions efficiently without causing problems. In addition, the crystal oscillator itself The body can also be made much smaller.

[0014]

[Effect of the idea]

As explained above, according to the rectangular AT-cut crystal resonator according to the present invention, the constant The width Wz is determined under the formula of can be obtained efficiently with good frequency-temperature characteristics without coupling of contour vibration and high-order contour vibration. There is an effect that it can be done.

[Brief explanation of drawings]

FIG. 1 is a graph showing frequency-temperature characteristics of an embodiment of a rectangular AT-cut crystal resonator according to the present invention.

[Figure 2] Width Wz of the crystal oscillator determined in the above example
It is a graph which shows the relationship between and the vibration frequency f of high-order contour vibration.

FIG. 3 is an external view showing an example of a rectangular AT-cut crystal resonator.

FIG. 4 is a graph showing the difference in frequency temperature characteristics depending on the presence or absence of high-order contour coupling.

[Explanation of symbols]

10...Crystal resonator, L...length, Wz...width, t...thickness.

──────────────────────────────────────────────── ─── Continuation of front page (72) Creator Ken Suzuki 3-12 Moriyacho, Yokohama, Kanagawa Japan Within Victor Co., Ltd. (72) Creator Takashi Shimada 4107 Miyota, Miyota-machi, Kitasaku-gun, Nagano Prefecture Ground 5 Simeo Precision Co., Ltd.

Claims (1)

[Scope of utility model registration request] Claim 1: The length L of the crystal resonator in the approximately X-axis direction is 4
~5 [mm], and when the vibration frequency f is in the range of 28 to 29 [MHz], the width Wz [mm] in the approximately Z-axis direction is set to a range where the vibration frequency is 28≦f<28.52 [MHz]. For (f-27.89)/0.21≦Wz≦3.0
For the vibration frequency range of 28.11≦f≦29 [MHz], 1.0≦Wz≦(f-27.70)/
A rectangular AT-cut crystal resonator characterized by having a diameter of 0.41.