JPH04128421U - SC cut crystal oscillator - Google Patents

Abstract

(57) [Summary] [Purpose] To provide an SC-cut crystal resonator that suppresses A-mode and B-mode vibrations and reliably resonates in C-mode, which is the main vibration. [Construction] In an SC-cut twice-rotated crystal resonator cut from a surface perpendicular to the Y-axis of the crystal, rotated approximately 34 degrees around the X-axis and then rotated approximately 22 degrees around the Z-axis. , a pair of excitation electrodes are formed facing each other on the front and back plate surfaces of the crystal piece, and from the Z' axis direction passing through the center of the plate surface with a gap of 0.05 mm to 0.15 mm to the excitation electrodes. A sub-electrode connected to the excitation electrode on the other side plate is provided in a direction rotated by 30° to 50°.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This invention relates to SC-cut crystal resonators, and in particular to suppression of sub-vibration modes. Ru.

0002

[Conventional technology]

In general, quartz crystal units exhibit unique vibration characteristics depending on the cutting angle with respect to the crystal axis. Ru. AT cut, which is most commonly used at frequencies of several MHz to over 10 MHz. A crystal resonator exhibits a cubic temperature characteristic having an inflection point near 25°C. By the way, reference oscillators that require highly stable frequencies for measurement equipment, wireless equipment, etc. For example, a constant temperature oven type oscillator is used. This temperature-controlled oscillator has 80 Crystal vibration is achieved by storing the crystal resonator in a constant temperature bath heated to a constant temperature of about ℃. This aims to stabilize the frequency by eliminating changes in frequency due to the temperature characteristics of the sensor. An SC cut crystal oscillator is suitable for such an oscillator. It has been known. This SC cut crystal resonator 1 is made of quartz crystal as shown in Figure 4. Rotate the plane perpendicular to the Y axis by about 34 degrees around the X axis, and then rotate it around the Z axis. It was cut out from a surface rotated approximately 22 degrees. However, this SC cut crystal resonator has a higher temperature than an AT cut crystal resonator. It has good impact properties, exhibits zero temperature coefficient at relatively high temperatures around 80℃, and has high impact properties. A high Q value can be obtained. Such characteristics can be obtained by heating to a constant temperature of about 80℃, for example. This is an extremely desirable feature for a highly stable crystal oscillator that is housed in a thermostatic chamber. It is gender. Therefore, for example, the 34th FCS (FREQ.CONTR) held in May 1980 SC cut in fundamental mode on pages 187 to 193 of the proceedings of OL SYMPOSIUM Species as disclosed as resonators (FUNDAMENTAL MODE SC-CUT RESONATORS) Various reports have been made.

0003 By the way, such an SC cut crystal resonator has a resonance characteristic as shown in FIG. 5, for example. B at the high-frequency side near the C-mode resonance (C in the diagram), which is the main vibration, as shown in the figure. Mode (B in the diagram) and A mode (A in the diagram) are generated. Here, the crystal impedance (hereinafter abbreviated as CI) of A-mode vibration is Since the value is larger than that of the C mode, there is no particular problem. On the contrary The CI of B mode is equal to or in some cases smaller than that of C mode. For this When an oscillator is actually manufactured, there is a problem in that it oscillates in the B mode of secondary vibration. Therefore, when using an SC cut crystal resonator, the main vibration of the C mode must be confirmed. In order to actually excite, the vibration of B mode is suppressed and its CI is made higher than that of C mode. also needs to be made larger. For this purpose, for example, a conveyor machine that processes only one main surface of a crystal piece into a convex lens shape is used. However, such devices are not suitable for the main purpose of C mode. The value of the secondary vibration of B mode is about twice the value of the CI of vibration, so the secondary vibration is ensured. There were problems that could not be suppressed.

0004

[Problem that the idea aims to solve]

This invention was made in view of the above circumstances, and it is possible to use not only A mode but also B mode. C-mode resonance can be suppressed, thereby ensuring that C-mode resonance can be excited. The object of the present invention is to provide an SC-cut crystal resonator that can perform the following steps.

[0005]

[Means to solve the problem]

This invention rotates the plane perpendicular to the Y-axis of the quartz crystal by approximately 34 degrees around the X-axis. Furthermore, the SC cut is rotated twice from a surface rotated about 22 degrees around the Z axis. In a crystal resonator, a pair of excitation electrodes are formed facing oppositely to the front and back plate surfaces of a crystal piece, In the plate surface with a distance of 0.05 mm to 0.15 mm to this excitation electrode. The excitation electrode on the other side plate surface is rotated by 30° to 50° from the Z’ axis direction passing through the heart. The device is characterized in that it is provided with a sub-electrode connected to.

[0006]

【Example】

An embodiment of the present invention is shown below as a front view of a crystal resonator with the cover removed, as shown in Figure 1. This will be explained in detail with reference to . In the figure, 11 is an SC cut crystal piece. This crystal piece 11 is placed on the Y axis of the crystal. Rotate the orthogonal plane approximately 33 degrees around the X axis, for example 33 degrees 18' counterclockwise, and then Cut out from a plane rotated approximately 22 degrees around the Z axis, for example 22 degrees 30' counterclockwise. It is a twice-rotated crystal piece. Then, the crystal piece 11 is shaped into a round plate or a short piece with a thickness depending on the desired resonance frequency. After forming into a book shape, excitation electrodes 12 are formed facing each other by vapor deposition or the like in the central part of both side plate surfaces. form. The excitation electrodes 12 are arranged in opposite directions along the Z'-axis direction of the plate surface. It is designed to lead out to the edge of the plate surface. And inside the plate surface of this crystal piece 11 The sub-electrode 13 is formed in a direction rotated by 30° to 50° with respect to the Z' axis passing through the heart. ing. Further, this sub-electrode 3 has a distance of 0.05 mm to 0.15 mm with respect to the excitation electrode 12. They are provided at intervals W of mm and are connected to the excitation electrode 12 on the other side plate surface. Note that in the crystal resonator shown in FIG. Sub-electrodes 13 are provided at symmetrical positions, and the sub-electrodes on the extraction end side of the excitation electrode 12 13 is connected to the excitation electrode 12, and the sub-electrode 13 on the opposite side faces the excitation electrode 12. It is connected to an excitation electrode 12 formed on the opposite side of the plate. Also against Excitation electrode 12 and sub-electrode with the same positional relationship and shape as in Fig. 1 are placed on the side plate surface. A pole 13 is formed. Note that the crystal piece 11 connects the drawn end of the excitation electrode 12 to the tip of the holding member 14. A conductive adhesive is applied thereto, and the proximal end of the holding member 14 is attached to the base. It is wound around the terminal 16 implanted in the terminal 15 and fixed thereto. Then, a frequency adjustment electrode is placed on the basic electrode of the crystal piece 11 held by the holding member 14. After vapor deposition and precisely matching the desired resonance frequency, cover with a cover (not shown). It is sealed airtight.

[0007] The graph shown in Figure 2 shows the excitation electrode on the plate surface and the sub-electrode on the outside as shown in Figure 1. Hold the end of the SC-cut crystal piece that formed the pole in the Z'-axis direction and adjust the position of this sub-electrode. The change in CI of C mode (curve c) and B mode (curve b) when changing the position is shown below. This is a graph showing. This crystal piece has a diameter of 12 mm and a 3rd order crystal with a frequency of 5 MHz. I used a baton one. As is clear from this result, the CI of C mode, which is the main vibration of interest, is approximately 80. Ω is a constant value, but the B-mode CI to be suppressed is at ±40° with respect to the Z' axis. It is the largest when the sub-electrode is placed in the direction, and the CI ratio with C mode is also the largest. . Practically speaking, however, the auxiliary electrode is placed at an angle of 30° with respect to the Z' axis passing through the center of the crystal piece. By arranging it at a position rotated by 50 degrees, the CI of B mode is about 330Ω. C mode, which is definitely the main vibration, has a ratio of more than 4 times that of C mode. It can be excited by With such a configuration, relatively large displacement will occur due to B-mode resonance. Since the sub-electrode is provided at a position rotated by 30° to 50° with respect to the Z' axis, B-mode resonance can be suppressed by the mass addition effect. Furthermore, this sub-telephone Since the poles are placed between the excitation electrodes on the plate surface with a small gap, the resonance of B mode will not occur. The electrical energy generated can be released to the excitation electrode and efficiently suppressed. can. Also, even if a sub-electrode is provided on the plate surface of the crystal piece, the SC cut crystal Since the essential characteristics of the resonator are not lost, it is especially suitable for highly stable oscillators using a constant temperature bath. A crystal oscillator suitable for this can be obtained. Note that the present invention is not limited to the above-mentioned embodiment, and for example, the present invention is not limited to the embodiment shown in FIG. Of course, it can also be applied to those using round crystal pieces as shown in the cross-sectional view. . In this case as well, it is possible to obtain the same effect as using the rectangular crystal piece shown in Figure 1. can.

[0008]

[Effect of the idea]

As detailed above, according to the present invention, the resonance of A mode and B mode can be suppressed. SC-cut crystal that can reliably excite C-mode resonance, which is the main vibration. A vibrator can be provided.

[0009]

[Brief explanation of drawings]

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

FIG. 2 is a graph showing the relationship between the formation position of a sub-electrode and CI in an embodiment of the present invention.

FIG. 3 is a front view of another embodiment of the present invention.

FIG. 4 is a perspective view illustrating an SC cut crystal resonator.

FIG. 5 is a diagram showing resonance characteristics of an SC-cut crystal resonator.

[Explanation of symbols]

11 Crystal piece 12 Excitation electrode 13 Sub-electrode 14 Holding member 15 base 16 terminal

Claims (1)

[Scope of utility model registration request] Claim 1: SC-cut twice-rotated crystal cut from a surface perpendicular to the Y-axis of a quartz crystal, rotated approximately 34 degrees around the X-axis and further rotated approximately 22 degrees around the Z-axis. In the vibrator, a pair of excitation electrodes are formed facing each other on the front and back surfaces of the crystal blank and led out to the ends along the Z'-axis direction in opposite directions, and a pair of excitation electrodes are formed at a distance of 0.05 mm to 0.0 mm with respect to the excitation electrodes. An SC cut plate characterized by having a sub-electrode connected to the excitation electrode on the other side plate surface in a direction rotated by 30° to 50° from the Z' axis direction passing through the center of the plate surface with an interval of 15 mm. Crystal oscillator.