JP2010246020A - Tuning fork type crystal unit - Google Patents

Abstract

An object of the present invention is to provide a tuning fork vibrator that improves the impact resistance by maintaining the CI small particularly by the surface longitudinal grooves, and further suppresses the occurrence of vertical vibration.
[Solution]
A pair of tuning fork arms 2 (ab) includes a tuning fork crystal piece 3 extending in one direction from the tuning fork base 1, and a tuning fork type crystal vibration in which longitudinal longitudinal grooves 5 are provided on both main surfaces of the tuning fork arm. In the child, the surface longitudinal groove 5 has a triangular shape with the width direction of the tuning fork arm 2 (ab) as a base, and the surface longitudinal groove is a single shape, and the triangular shape is the starting end of the extension of the tuning fork arm. The base of the tuning fork base, which is a part, is the base, and the tip side of the tuning fork arm is the remaining two vertices.
[Selection] Figure 1

Description

  The present invention has a technical field of a tuning fork type crystal resonator (hereinafter referred to as a tuning fork type resonator) in which a surface longitudinal groove is provided in a tuning fork arm to reduce a crystal impedance (CI), and in particular, a mechanical structure with a small CI. The present invention relates to a tuning fork type vibrator with increased strength.

(Background of the Invention)
Tuning fork vibrators are built into various electronic devices having a clock function, including wristwatches. One of these is a tuning fork vibrator in which surface longitudinal grooves are provided on both main surfaces of a tuning fork arm to improve electric field efficiency and promote miniaturization. In recent years, it has been required to prevent a decrease in mechanical strength due to surface longitudinal grooves on both main surfaces.

(Example of conventional technology)
FIG. 5 is a view of a tuning fork type vibrator for explaining a conventional example. FIG. 5 (a) is a front view of the tuning fork type vibrator, and FIG. 5 (b) is an enlarged plan view showing the electric field direction.

  The tuning fork vibrator includes a tuning fork crystal piece 3 including a tuning fork base 1 and a pair of tuning fork arms 2 (ab). The tuning fork crystal piece 3 has a crystal axis (XYZ) whose X axis (electric axis) is a width, Y axis (mechanical axis) is a length, Z axis (optical axis) is a thickness direction, and a pair of tuning fork arms from the tuning fork base 1. 2 (ab) extends parallel to the Y-axis direction. Excitation electrodes 4 for inducing tuning fork vibration are formed on both main surfaces and both side surfaces of the pair of tuning fork arms 2 (ab). In these, the outer shape and each electrode are formed by photolithography and wet etching on a crystal wafer (not shown) which is Z-cut.

  The excitation electrode 4 has both main surfaces of one tuning fork arm 2 (ab) and both side surfaces of the other tuning fork arm 2 (ab) at the same potential, and both side surfaces of one tuning fork arm 2 (ab) and both main surfaces of the other tuning fork arm 2 (ab). Are the same potential, and the two have different signs. Each excitation electrode 4 is connected in common by a wiring path (not shown) and extends to the tuning fork base 1 as a lead-out terminal. Normally, a metal film cut by a laser or the like (not shown) for frequency adjustment is formed on the tip side of each tuning fork arm 2 (ab), but is omitted here for convenience. The tuning fork base 1 is fixed to an inner bottom surface of a container (not shown) and hermetically sealed.

  Here, surface longitudinal grooves 5 along the Y-axis direction (length direction) are provided on both main surfaces of each tuning fork arm 2 (ab). The surface longitudinal groove 5 has a base portion of the tuning fork arm 2 (ab) with respect to the tuning fork base 1 as an extension start end, and the excitation electrode 4 including the inner peripheral side surface is formed in the surface longitudinal groove 5. Thus, an electric field indicated by an arrow in the X-axis direction (width direction) is generated by the excitation electrodes 4 on both main surfaces and both side surfaces of each tuning fork arm 2 (ab).

  In this case, the surface vertical groove 5 makes the electric field in the X-axis direction linearly generated by the excitation electrodes 4 on the inner and outer surfaces of the tuning fork arm 2 (ab) and the inner peripheral side surface of the surface vertical groove 5 in particular. Therefore, the electric field efficiency in the X-axis direction of each tuning fork arm 2 (ab) is increased, and the CI of tuning fork vibration can be reduced. Since the electric field strength increases as the distance d between the inner and outer surfaces of the tuning fork arm 2 (ab) and the surface longitudinal groove 5 is shorter, the CI is basically further reduced.

  The tuning fork vibration is caused by the electric field in the X-axis direction that is opposite to each other from the center of each tuning fork arm 2 (ab), for example, the outer side surface of each tuning fork arm 2 (ab) expands and the inner side surface expands and contracts (so-called bending). vibration). As a result, the tuning fork arms 2 (ab) are displaced in the opposite horizontal directions, and the tuning fork arms 2 (ab) physically resonate. Therefore, it becomes easier to vibrate than the case of a single tuning fork bar, and the height dimension can be reduced.

JP 2003-133895 A JP 2007-6091 A

(Problems of conventional technology)
However, in the tuning fork vibrator having the above-described configuration, the surface longitudinal grooves 5 are provided from both main surfaces to each tuning fork arm 2 (ab), so that the mechanical strength is also reduced. There was a problem lacking. Further, the surface longitudinal grooves 5 also reduce the rigidity in the thickness direction, generate vertical vibration perpendicular to the plate surface (main surface) of the tuning fork arm, and increase the CI by impairing the vibration energy of the tuning fork vibration. There was also a problem that let me.

(Object of invention)
It is an object of the present invention to provide a tuning fork vibrator that maintains a small CI by means of a surface longitudinal groove to improve impact resistance and further suppress the occurrence of vertical vibration.

  The present invention includes a tuning fork crystal piece in which a pair of tuning fork arms extends in one direction from a tuning fork base, as shown in the claims (Claim 1), and has a length on both main surfaces of the tuning fork arm. In the tuning fork type crystal resonator provided with the surface longitudinal groove in the direction, the surface longitudinal groove has a triangular shape with the width direction of the tuning fork arm as a base.

  With such a configuration, since a linear electric field acts by the surface longitudinal grooves, the electric field efficiency can be improved and the tuning fork vibration CI can be reduced as compared with the case where no surface longitudinal grooves are provided. Since the surface longitudinal groove of the tuning fork arm is triangular, the mechanical strength can be increased as compared with the case where the tuning fork arm is rectangular along the tuning fork arm. Therefore, it is possible to improve the impact resistance while reducing the CI. Furthermore, since the surface longitudinal grooves are triangular, and the area of the real part of the tuning fork arm is made larger than that of the rectangular shape, the rigidity in the direction perpendicular to the plate surface is increased, and the occurrence of vertical vibration on the plate surface is suppressed.

(Embodiment section)
According to a second aspect of the present invention, in the first aspect, the surface longitudinal groove is single, and the triangular shape has a base portion of the tuning fork base that becomes an extension start end of the tuning fork arm as a base, and a tip of the tuning fork arm. Let the side be the vertices of the remaining two sides. According to this, since the triangular base is the extended start end of the tuning fork base (the root of the pair of tuning fork arms), the distance between the inner circumference on the bottom side of the surface longitudinal groove and both sides of the tuning fork arm is reduced. To do. Therefore, the electric field at the base part of the pair of tuning fork arms is the largest.

  In this case, the root portion of the tuning fork arm having the largest electric field is a node (vibration fulcrum) of the tuning fork vibration, so that vibration from the root portion is facilitated to increase vibration efficiency. Further, each tuning fork arm has a larger mass on the tip side than on the tuning fork base side, so that tuning fork vibration due to inertia is urged. From these, it is possible to maintain the CI of the tuning fork vibration smaller than when the triangular apex is used as the extending start end of the tuning fork base.

  In the third aspect of the invention, in the first aspect, the surface longitudinal groove is single, and the triangular shape has a base on the tip side of the tuning fork arm, and a base portion of the tuning fork base that becomes an extension start end of the tuning fork arm. The remaining two vertices are assumed. According to this, each tuning fork arm has a smaller mass on the tip side than on the tuning fork base side, so that the swing due to inertia at the time of impact is reduced. Therefore, damage due to impact can be further prevented. However, since CI increases more than in the case of claim 2, these are selected according to the specifications.

  In the fourth aspect of the present invention, in the first, second, or third aspect, in the first aspect, the remaining two sides with respect to the bottom of the triangular surface longitudinal groove are curved outwardly. As a result, the distance between the inner and outer surfaces of each tuning fork arm and the inner peripheral side surface of the surface longitudinal groove is reduced and the electric field strength is increased, so that CI can be further reduced.

  In the fifth aspect of the present invention, in the first aspect, a plurality of the triangular surface longitudinal grooves are arranged in the length direction of the tuning fork arm. Even in this case, similarly to the first aspect, the mechanical strength can be increased to reduce the CI. The total area of the surface longitudinal grooves is smaller than that of a single surface longitudinal groove, and the real area of each tuning fork arm is increased, so that the rigidity in the direction perpendicular to the plate surface of each tuning fork arm is increased. Increase.

It is a front view of a tuning fork type vibrator explaining a 1st embodiment of the present invention. It is a front view of a tuning fork vibrator explaining a second embodiment of the present invention. It is a front view of a tuning fork type vibrator explaining a third embodiment of the present invention. It is a front view of a tuning fork type vibrator explaining other embodiments of the present invention. FIG. 2 is a diagram of a tuning fork vibrator for explaining a conventional example, in which FIG. 1A is a front view of the tuning fork vibrator and FIG. 2B is an enlarged plan view showing an electric field direction.

(Equivalent to the first embodiment, claims 1, 2, and 4)
Hereinafter, an embodiment of the present invention will be described with reference to FIG. 1 (a front view of a tuning fork vibrator). In addition, the same number is attached | subjected to the same part as a prior art example, and the description is simplified or abbreviate | omitted.

  As described above, the tuning fork vibrator has the X axis as the width, the Y axis as the length, the Z axis as the thickness direction, and a tuning fork arm 2 (ab) extending from the tuning fork base 1 in the Y axis direction. A crystal piece 3 is provided. Then, surface longitudinal grooves 5 are provided on both principal surfaces of each tuning fork arm 2 (ab), and excitation electrodes 4 are formed on both principal surfaces and both side surfaces including the inner peripheral side surface of the surface longitudinal groove 5. These are integrally formed by photolithography and wet etching.

  Here, the surface longitudinal groove 5 of each tuning fork arm 2 (ab) is single, for example, isosceles triangle. The root of the tuning fork base 1 serving as the starting extension of the tuning fork arm 2 (ab) is defined as a triangular base, and the apex is defined as the tip side (head side) of the tuning fork arm 2 (ab). The triangular base coincides with the width direction (X-axis direction) of the tuning fork arm 2 (ab). The triangular shape is a curved shape in which the remaining two sides excluding the bottom are curved outward.

  With such a configuration, as described in the column of the effect of the invention, a linear electric field acts on the surface longitudinal grooves 5, so that the electric field efficiency is improved compared with the case where the surface longitudinal grooves 5 are not provided, and the tuning fork vibration is increased. CI can be reduced. And since the surface longitudinal groove 5 of the tuning fork arm 2 (ab) has a triangular shape, the mechanical strength can be increased as compared with the case where the tuning fork arm 2 (ab) has a rectangular shape along the tuning fork arm 2 (ab). Therefore, it is possible to improve the impact resistance while reducing the CI. Further, since the area of the real part of the tuning fork arm 2 (ab) is made larger than the rectangular shape of the surface longitudinal groove 5 as in the conventional example, the rigidity in the direction perpendicular to the plate surface is increased, and the vertical vibration with respect to the plate surface is increased. Suppresses the occurrence.

  In this embodiment, the surface longitudinal groove 5 is single, and the triangular shape is the base of the tuning fork base 1 that is the extending start end of the tuning fork arm 2 (ab), and the tip side of the tuning fork arm 2 (ab). Are the vertices of the remaining two sides. Therefore, since the distance between the inner circumference on the bottom side of the surface longitudinal groove 5 and both side surfaces of the tuning fork arm 2 (ab) is reduced, the electric field at the root portion of the pair of tuning fork arms 2 (ab) is maximized.

  In this case, the root portion of the tuning fork arm 2 (ab) where the electric field is the largest is a node (vibration fulcrum) of the tuning fork vibration. Further, each tuning fork arm 2 (ab) has a larger mass on the tip side than on the tuning fork base 1 side, so that tuning fork vibration due to inertia is urged. Therefore, the CI of the tuning fork vibration can be kept smaller than the triangular vertex as the starting extension of the tuning fork base 1.

  The remaining two sides with respect to the bottom side of the surface longitudinal groove 5 having a triangular shape are curved outwardly. Accordingly, since the distance between the inner and outer surfaces of each tuning fork arm 2 (ab) and the inner peripheral side surface of the surface longitudinal groove 5 is reduced and the electric field strength is increased, CI can be further reduced.

(Second embodiment, claims 1, 3, 4)
Hereinafter, a second embodiment of the present invention will be described with reference to FIG. 2 (a front view of a tuning fork vibrator). In addition, description of the same part as previous embodiment is abbreviate | omitted.

  In the second embodiment, the top and bottom of the surface longitudinal groove 5 having a single triangular shape is turned upside down, the tip side of the tuning fork arm 2 (ab) is the bottom side, and the tuning fork that becomes the extended starting end of the tuning fork arm 2 (ab) is used. Let the base part of the base 1 be the remaining two vertices. In this way, each tuning fork arm 2 (ab) has a smaller mass on the tip side than on the tuning fork base 1 side, so that the swing due to inertia at the time of impact is reduced. Therefore, damage due to impact can be further prevented.

(Third embodiment, claims 1, 4, 5)
Hereinafter, a third embodiment of the present invention will be described with reference to FIG. 3 (a front view of a tuning fork vibrator). In addition, description of the same part as previous embodiment is abbreviate | omitted.

  In the third embodiment, a plurality of triangular surface longitudinal grooves 5 are arranged in the length direction of each tuning fork arm 2 (ab). Even in this case, similarly to the previous embodiment, the CI is reduced by the plurality of surface longitudinal grooves 5, and the mechanical strength is increased by making each surface longitudinal groove 5 triangular. Further, the total area of the surface longitudinal grooves 5 is smaller than that of the single surface longitudinal groove 5, and the area that is the real part of each tuning fork arm 2 (ab) is increased. Therefore, each tuning fork arm 2 (ab) The rigidity in the direction perpendicular to the plate surface is further increased.

  In the above embodiment, the two sides with respect to the bottom side of the surface longitudinal groove 5 have a curved shape that curves outward. However, even when the shape is linear, the same effect is basically obtained. Further, the same effect can be obtained by making the vertices of two sides other than the bottom of the surface longitudinal groove 5 in a triangular shape face each other as shown in FIG. Furthermore, the triangular shape is applicable not only to an isosceles triangle but also to a right triangle, for example.

  1 tuning fork base, 2 tuning fork arm, 3 tuning fork crystal piece, 4 excitation electrode, 5 surface longitudinal groove.

Claims (5)

  A tuning fork-type crystal resonator in which a pair of tuning fork arms includes a tuning fork crystal piece extending in one direction from a tuning fork base, and a longitudinal longitudinal groove is provided on both main surfaces of the tuning fork arm. A tuning fork type crystal resonator having a triangular shape with the width direction of the tuning fork arm as a base.   In Claim 1, the said surface longitudinal groove is single, and the said triangular shape makes the base part of the said tuning fork base part used as the extension start end part of the said tuning fork arm a base, and the vertex of two sides which remain | survives the front end side of the said tuning fork arm. Tuning fork type crystal resonator.   In Claim 1, the said surface longitudinal groove is single, and the said triangular shape makes the front end side of the said tuning fork arm a base, and the vertex of two sides which leaves the fundamental part of the said tuning fork base used as the extension start end part of the said tuning fork arm, Tuning fork type crystal resonator.   4. The tuning fork type crystal resonator according to claim 1, wherein the remaining two sides with respect to the bottom side of the triangular surface longitudinal groove according to claim 1 have a curved shape curved outward.   2. The tuning fork type crystal resonator according to claim 1, wherein a plurality of triangular surface longitudinal grooves are arranged in a length direction of the tuning fork arm.

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