JP2006279870A - Lame-mode quartz crystal oscillator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a support method of a vibration part for particularly satisfying requirements of downsizing and high accuracy with respect to the vibrator shape of a lame-mode quartz crystal oscillator. <P>SOLUTION: In the lame-mode quartz crystal oscillator for causing a vibration form of contour vibration by using four corner node points of the piezoelectric plate in the case that electric charges are applied to the rectangular shaped piezoelectric plate wherein a piezoelectric plate of a rectangular shape is extended/contracted in a width direction when the piezoelectric plate is extended in a longitudinal direction of the rectangular shape and the piezoelectric plate of a rectangular shape is extended/contracted in the longitudinal direction when the piezoelectric plate is extended in the width direction of the rectangular shape. The vibrator is supported at a center position of the principal side of the piezoelectric plate when the length of sides of the rectangular piezoelectric plate is same. Concretely, the vibrator is supported at a non-vibrating part as the center position of the principal face of the vibrating parts wherein the length of one side of the rectangular piezoelectric plate is defined as L, then the length of the other longer side is a multiple of L. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a resonator shape of a lame mode crystal resonator, and more particularly to a support method for improving the impact resistance of a vibration part that satisfies the demands for miniaturization and high accuracy.

  The lame mode vibrator is small and can obtain an optimum vibration mode for realizing a low frequency. Therefore, the realization of miniaturization while being a low-frequency vibrator has a large market widely used in mobile phones, portable small game devices and the like that have made remarkable progress in recent years.

  The lame mode vibrator is formed of a piezoelectric substrate having a thickness of several tens of μm. In order to hold the lame mode vibrator, it is common to hold a vibration node so as not to hinder vibration. The vibration node is supported at four points in the secondary mode. As shown in FIG. 8, it is supported and held through the connecting portions at the four corners. From this node, the arm is pulled out and connected to the holding part and assembled into a package to obtain a vibrator. At this time, by making the arm portion as thin as possible, the inhibition of vibration can be reduced and the equivalent series resistance can be reduced. Therefore, a strong structure is required at the time of drop impact.

As described above, when the lame mode quartz crystal resonator is a square plate, the conventional lame mode crystal resonator has a high Q value because it is a vibration mode in which the four corners are nodes and vibrates in an equal volume in the plane. The most effective support method is to pull out the support part from the four corners that are the nodes of vibration to obtain the vibrator. For the actual support method, ceramic etc. are connected to the support part of the vibrator via the connection part. At present, the substrate is fixed to the substrate using a conductive adhesive.
JP 2003-101378 A Kawashima, Hirama, Saito, Koyama, "Crystal oscillator and its applied devices", IEICE Transactions, VOL. J82-CI, No. 12, December 1999, p. In addition, the applicant has not found any prior art documents related to the present invention by the time of filing of the present application other than the prior art documents specified by the above-mentioned prior art document information.

  Since the conventional lame mode quartz crystal resonator described above is a rectangular plate with an integer ratio of the vibration part, for example, when supporting the four corners of the vibration part, the vibration nodes are the four corners and the vibration displacement is small. The vibration of the lame mode due to the holding of the vibration part is not hindered.

  However, since the vibration part, the support part, and the connection part are integrally formed, when the lame mode crystal resonator is mounted and stored in the container, the part that connects the vibration part and the support part has a lame mode vibration. Since the moment force generated from the node is generated, bending vibration is generated at the connecting portion under the influence of the moment force.

  Therefore, if the shape of the support part and connection part is not set to appropriate design values, vibration of the vibration part will occur, and unnecessary vibration will be transmitted to the support part and connection part that hold the vibration part. There is a risk that the vibrations of the

  In addition, in order to mount the vibrating part on the container by some means, a support part and a connection part are required. Therefore, when considered in the form of a vibrator, a structure in which a support portion and a connection portion are integrated in addition to the vibration portion is required, so that it is difficult to reduce the overall size. On the other hand, it is possible to maintain a high Q value by reducing the weight of the supporting part other than the vibrating part and making it fragile in propulsion, but by reducing the supporting part, impact resistance and I am also worried that it will be vulnerable to impacts such as the drop-resistant strength.

  Therefore, in the present invention, when a charge is applied to the rectangular piezoelectric element plate, the four corners of the piezoelectric element plate are nodes, and when extending in the longitudinal direction of the rectangular shape, the piezoelectric element plate expands and contracts in the short direction, and In the lame mode quartz crystal resonator that generates a vibration form of contour vibration that expands and contracts in the longitudinal direction when extending in the short direction of the rectangular shape, a node portion and / or a node portion that is a non-vibrating portion of the rectangular piezoelectric element plate The lame mode quartz crystal resonator is characterized in that it is supported by a side surface. The above-mentioned node side surface is a substrate in which the piezoelectric element plate is a substrate, the dimension of one side of the vibration portion of the substrate is 1, and the other side surface The rectangular piezoelectric element plate satisfying an integer ratio (1 to n) of the side dimension and when one side of the rectangular piezoelectric element plate is L, the other side is a multiple of L. It is a lamé mode crystal resonator in a dimensional relationship.

  In short, the lame mode crystal resonator is formed of a piezoelectric substrate having a thickness of several tens of μm, and in order to hold the lame mode resonator, the vibration node is held so as not to inhibit the vibration. However, since the strength to the support part is insufficient, the multi-order Lame mode vibrator has conventionally supported the vibrator with two or four arms. On the other hand, by supporting the part that becomes the apex of the lame mode vibrator that vibrates at the lowest order near the central part that becomes the node of vibration, the support form with rigidity that increased the number of support points and improved impact resistance A Lame mode vibrator can be obtained.

  As described above, in the case of the higher-order mode resonator, the support portion of the lame mode crystal resonator of the present invention increases the number of portions to be supported by the nodal portion and / or the nodal side surface of the piezoelectric element plate, Even in the low frequency vibration mode, the strength of the connecting portion can be ensured even if the entire vibrator is downsized. In this case, the portion to be supported by the side surface is the rectangular piezoelectric element in which the dimension of one side of the vibrating portion of the substrate is 1, and the ratio of the side to the dimension of the other side satisfies an integer multiple (1 to n). In the base plate, when one side of the rectangular piezoelectric base plate is L, the other side has a dimensional relationship that is a multiple of L.

Embodiments of the present invention will be described below with reference to the drawings. In each figure, the same numerals indicate the same objects.
When the piezoelectric element plate 1 is a substrate, and one dimension of the side ratio of the substrate is 1, the lame mode vibrator has an infinite number of vibration modes existing on a plate in which the other dimension satisfies the integer ratio (1 to n). It is called. In the case of a square plate as shown in FIG. 1, when the two sides A facing each other with the corners at the four corners are displaced toward the center of the square, the other two sides B are displaced outwardly of the square, and the two sides facing each other When A is displaced in the outward direction of the square, the other two sides B are in a vibration form that is displaced in the center direction of the square. Therefore, it vibrates in such a manner that the operations of FIG. 1A and FIG. 1B are repeated. This FIG. 1 is called the lowest order vibration mode of a square plate. FIG. 1 (c) shows a dimensional concept of the diaphragm. FIG. 2 shows a schematic diagram of the vibration mode.

  On the other hand, FIGS. 3A to 3B are schematic diagrams for realizing higher-order vibration modes. FIG. 3A shows an example of analysis of a lame mode vibrator having an edge ratio of 1: 2, and FIG. 3B an edge ratio of 1: 3. As described above, the lame mode vibration is a vibration mode infinitely existing on a plate having a rectangular side ratio of an integer. A schematic diagram of the vibration mode is shown in FIGS. 4 and 5, respectively.

  In the present invention, when the above-described higher-order vibration mode is supported, what is conventionally supported only for the corner portion of the vibrator is characterized by retaining all the vibration-free portions of the vibrator. is there. As an example of the supporting form, as shown in FIG. 6, the nodal portion of the vibrator (the portion that becomes the apex of the lame mode vibrator that vibrates at the lowest order) is formed by using the piezoelectric element plate 1 as a substrate. A rectangular piezoelectric element plate 1 in which the dimension of one side of the side surface of the vibration part of the substrate is 1, and the ratio of the other side to the dimension of the other side is an integral multiple (1 to n), When one side of the piezoelectric element plate 1 is L, the other side has a dimensional relationship that is a multiple of L.

  7A and 7B can be considered for other support modes of the present invention, and each support portion 2 is considered based on FIG. 7 (a) lacks a part of the connecting portions 3 in the high-order arrangement direction which is the vertical direction of the drawing, and FIG. 7 (b) shows one of the connecting portions 3 in the horizontal direction of the drawing. It lacks a part. In addition, it is needless to say that the combined configuration of the connecting portions 3 in the range illustrated in FIG.

  FIG. 8 shows an example of a conventional support form. Conventionally, when a vibrator is manufactured, support portions 2 are provided at four corners of a square that is a node of vibration in order to avoid a decrease in Q value. In this relation, the vibration part, the support part 2 and the connection part 3 are formed integrally, so that moment force is generated at the four corners serving as vibration nodes.

  As a result, when the design of the support portion 2 is not appropriate, vibration energy leaks to the support portion 2 and the equivalent resistance value R1 increases. Furthermore, if the equivalent resistance value R1 is reduced and the width and thickness of the support part 2 from the four corners are reduced for the purpose of reducing the decrease in the Q value, the amplitude increases due to an impact such as a drop or excessive excitation current. There is a risk of damage.

It is a top view which shows the primary form of a lamé mode crystal oscillator. This is a mode for analyzing the vibration form shown in FIG. It is a top view explaining the higher order mode of a lamé mode crystal oscillator. FIG. 4 is a schematic diagram showing a secondary mode in the higher-order mode shown in FIG. 3. It is a schematic diagram which shows a tertiary mode in the high-order mode shown in FIG. It is a top view which shows an example of the support form of this invention. It is a top view which shows the other support form of this invention. It is a top view which shows the conceptual diagram of the support form of the lame mode crystal resonator made into the prior art example.

Explanation of symbols

1 Piezoelectric substrate
2 Support part 3 Connection part

Claims (1)

When a charge is applied to the rectangular piezoelectric element plate, the four corners of the piezoelectric element plate serve as nodes, and when extending in the longitudinal direction of the rectangular shape, it expands and contracts in the short direction, and the rectangular short shape In a lame mode crystal resonator that produces a vibration form of contour vibration that expands and contracts in the longitudinal direction when stretched in the hand direction,
A lame mode quartz crystal resonator supported by a nodal portion and / or a side surface of the nodal portion of the rectangular piezoelectric element plate.

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