JP2013187853A - Piezoelectric vibration piece, piezoelectric vibrator, oscillator, electronic apparatus, and atomic clock - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric vibration piece which inhibits the increase of the number of components and the deterioration of the production efficiency and effectively absorbs an impact thereby inhibiting the damage etc. of vibration arm parts, and to provide a piezoelectric vibrator, an oscillator, an electronic apparatus, and an atomic clock.SOLUTION: A piezoelectric vibration piece 5 includes: a pair of vibration arm parts 24, 25 which are arranged side by side in a width direction; and a base part 26 to which the base end sides of the pair of vibration arm parts, when viewed in an extension direction, are connected. A buffer part 30, which has lower rigidity compared to other portions of the base part 26 and may absorb an impact applied to the vibration arm parts 24, 25 in a thickness direction, is integrally formed with the base part 26 in a space, which is located between a mount part 26a mounted on a package 10 and a connection part 26b to which the base end sides of the vibration arm parts 24, 25 are connected, from among the base part.

Description

  The present invention relates to a piezoelectric vibrating piece, a piezoelectric vibrator, an oscillator, an electronic device, and a radio timepiece.

  For example, a cellular phone or a portable information terminal often uses a piezoelectric vibrator using quartz or the like as a time source, a timing source such as a control signal, or a reference signal source. As this type of piezoelectric vibrator, there is one in which a tuning fork type piezoelectric vibrating piece is hermetically sealed in a package in which a cavity is formed.

  The package has a structure in which one of a pair of glass substrates in which a recess is formed is overlapped with each other and directly joined together, thereby functioning the recess as a cavity. In addition, the piezoelectric vibrating piece includes a pair of vibrating arm portions arranged side by side in the width direction and a base portion that connects the proximal end sides of both vibrating arm portions. It is configured to vibrate (oscillate) at a predetermined resonance frequency in the approaching / separating direction starting from the end side.

  By the way, with the miniaturization of mobile phones and portable information terminal devices, the above-described piezoelectric vibrators are further miniaturized and thinned, and for this reason, the clearance in the thickness direction between the piezoelectric vibrating piece and the inner surface of the package is reduced. Is becoming very narrow (for example, about 20 μm to 100 μm). As a result, when an impact due to dropping or the like is applied to the piezoelectric vibrator, the vibrating arm is displaced in the thickness direction, so that the tip of the vibrating arm comes into contact with the inner surface of the package and vibrates due to the impact. There is a risk that the arm portion may be damaged.

As a countermeasure, for example, in Patent Document 1, a cushioning member made of a silicon-based adhesive or the like is disposed in a portion corresponding to the tip portion of the vibrating arm portion of the inner surface of the package, and the tip portion of the vibrating arm portion is the package. Even if it contacts, the thing which made the shock relieve with a buffer member is described (1st prior art).
Another measure is to form a stepped portion that is one step higher on the bottom of the package and mount the base of the piezoelectric vibrating piece on the stepped portion to ensure a gap between the vibrating arm and the bottom of the package. The structure to perform is examined (2nd prior art).
As another countermeasure, a configuration in which a recess for avoiding interference with the tip of the vibrating arm is formed in a portion corresponding to the tip of the vibrating arm of the inner surface of the package has been studied. (Third prior art).

JP 2003-60475 A

However, each of the above-described conventional techniques has the following problems.
That is, in the first prior art, the buffer member is formed separately on the inner surface of the package, which causes an increase in the number of parts and a decrease in manufacturing efficiency.
Further, in the second prior art, there is a problem that the thickness of the package is increased by providing the step portion.
In the third prior art, by forming a recess on the inner surface of the package, the thickness of the package at the portion where the recess is formed may be reduced, and the strength may be reduced.
Further, in the second and third prior arts, the configuration is such that the contact between the tip of the vibrating arm and the inner surface of the package is avoided. There is a possibility that it cannot be completely prevented from contacting the inner surface.

  Therefore, the present invention has been made in view of the above-mentioned problems, and while suppressing an increase in the number of parts and a decrease in manufacturing efficiency, it effectively absorbs an impact caused by a drop or the like and breaks the vibrating arm portion. The present invention provides a piezoelectric vibrating piece, a piezoelectric vibrator, an oscillator, an electronic device, and a radio timepiece that can suppress the above.

In order to solve the above-described problems, the present invention provides the following means.
A piezoelectric vibrating piece according to the present invention includes a pair of vibrating arm portions arranged side by side in the width direction, and a base portion to which a base end side in the extending direction of the pair of vibrating arm portions is connected. In
Between the mount portion mounted on the package and the connection portion to which the proximal end side of the vibrating arm portion is connected, the rigidity of the vibrating arm is low compared to other portions of the base portion. A buffer portion capable of absorbing an impact in the thickness direction perpendicular to the width direction and the extending direction with respect to the portion is formed integrally with the base portion.

According to this configuration, since the buffer portion is formed to have lower rigidity than other portions, for example, in a state where the piezoelectric vibrating piece is hermetically sealed in the package, the piezoelectric vibrating piece (vibrating arm portion) is caused by an external impact or the like. When the vibrating arm portion comes into contact with the inner surface of the package, for example, when the vibration portion vibrates in the thickness direction, the buffer portion quickly elastically deforms in the thickness direction. Thereby, the impact in the thickness direction on the vibrating arm portion can be absorbed, and damage to the piezoelectric vibrating piece can be suppressed.
In particular, since the buffer portion is formed integrally with the base portion, it is not necessary to provide a buffer member separately as in the first prior art described above. Therefore, an increase in the number of parts and a decrease in manufacturing efficiency can be suppressed.
Further, unlike the second prior art described above, there is no need to provide a stepped portion in the package, so that an increase in the thickness of the package can be suppressed and the package can be made thinner.
Furthermore, unlike the third prior art described above, no recess is formed in the package, so that the strength of the package can be maintained.

Further, the buffer portion is characterized in that an area of a cross section perpendicular to the extending direction is formed smaller than other portions of the base portion.
According to this configuration, it is possible to efficiently absorb the impact when the vibrating arm portion vibrates in the thickness direction.

By the way, when the length of the base portion is shortened in order to reduce the size of the piezoelectric vibrating piece, the distance between the mount portion and the connection portion of the base portion approaches. Then, the vibration excited by the vibrating arm portion is not sufficiently attenuated at the base portion, but leaks through the mount portion, for example, to the package side, and as a result, the resonance frequency is shifted. Such a phenomenon is regarded as vibration leakage, and when this vibration leakage occurs, in addition to the problem that the resonance frequency shifts, loss at the time of conversion from an electric signal to mechanical vibration increases, so an equivalent series resistance value (Crystal Impedance: (CI value) rises and the problem that quality deteriorates also arises.
On the other hand, in the configuration of the present invention, since the area of the cross section of the buffer portion is formed smaller than other portions, the route through which the vibration excited by the vibrating arm portion is transmitted to the mount portion side can be narrowed. Therefore, it becomes possible to confine the vibration on the vibrating arm portion side, and it is possible to suppress the leakage of the vibration to the mount portion side of the base portion. By suppressing this vibration leakage, it is possible to suppress an increase in the CI value and to suppress a decrease in the quality of the output signal.

Further, the buffer portion is characterized in that recesses formed by cutting from both sides of the base portion in the thickness direction or the width direction are alternately arranged along the extending direction. .
According to this configuration, since the concave portions are formed in a spring shape formed alternately, the buffer can be efficiently absorbed when the vibrating arm portion vibrates in the thickness direction.

The piezoelectric vibrator according to the present invention is characterized in that the piezoelectric vibrating piece according to the present invention is hermetically sealed in a package.
According to this configuration, since the piezoelectric vibrating piece of the present invention is hermetically sealed in the package, it is possible to provide a piezoelectric vibrator having sufficient strength and high reliability after being thinned.

  The oscillator of the present invention is characterized in that the piezoelectric vibrator of the present invention is electrically connected to an integrated circuit as an oscillator.

  In addition, the electronic device of the present invention is characterized in that the piezoelectric vibrator of the present invention is electrically connected to a time measuring unit.

  The radio timepiece of the present invention is characterized in that the piezoelectric vibrator of the present invention is electrically connected to a filter portion.

  Since the oscillator, electronic device, and radio timepiece according to the present invention include the piezoelectric vibrator of the present invention described above, a highly reliable high-quality oscillator, electronic device, and radio timepiece can be obtained after reducing the thickness. Can be provided.

According to the piezoelectric vibrating piece of the present invention, it is possible to effectively absorb an impact and suppress breakage of the vibrating arm portion and the like while suppressing an increase in the number of parts and a decrease in manufacturing efficiency.
According to the piezoelectric vibrator of the present invention, it is possible to provide a piezoelectric vibrator having sufficient strength and high reliability while being thinned.
In the oscillator, electronic device, and radio timepiece of the present invention, a highly reliable high-quality oscillator, electronic device, and radio timepiece can be provided after thinning.

1 is an external perspective view showing a piezoelectric vibrator according to an embodiment of the present invention. FIG. 2 is an internal configuration diagram of the piezoelectric vibrator shown in FIG. 1, and is a plan view with a lid substrate removed. It is sectional drawing in the AA of FIG. FIG. 2 is an exploded perspective view of the piezoelectric vibrator shown in FIG. 1. FIG. 4 is a cross-sectional view corresponding to FIG. 3 and is an explanatory diagram for explaining the operation of the piezoelectric vibrating piece. It is a figure which shows the piezoelectric vibrating piece of a 1st modification, Comprising: (a) is a top view, (b) is sectional drawing which follows the BB line of (a). It is a figure which shows the piezoelectric vibrating piece of a 2nd modification, Comprising: (a) is a top view, (b) is sectional drawing which follows the CC line of (a). It is a figure which shows the piezoelectric vibrating piece of a 3rd modification, Comprising: (a) is a top view, (b) is sectional drawing which follows the DD line | wire of (a). It is a top view which shows the piezoelectric vibrating piece of a 4th modification. It is a top view which shows the piezoelectric vibrating piece of a 5th modification. (A) is a top view of the piezoelectric vibrating piece of the sixth modified example, (b) is a cross-sectional view taken along the line EE of (a), and (c) to (e) are the seventh to ninth modified examples, respectively. It is a figure which shows a piezoelectric vibrating piece, Comprising: It is sectional drawing equivalent to FIG.11 (b). (A)-(c) is a top view which shows the piezoelectric vibrating piece of the 10th-12th modification, respectively. (A) And (b) is a top view which shows the piezoelectric vibrating piece of a 13th modification and a 14th modification, respectively. It is a schematic block diagram of the oscillator in embodiment of this invention. It is a schematic block diagram of the portable information device in embodiment of this invention. It is a schematic block diagram of the radio timepiece in the embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Piezoelectric vibrator)
FIG. 1 is an external perspective view of the piezoelectric vibrator according to the present embodiment as viewed from the lid substrate side. FIG. 2 is an internal configuration diagram of the piezoelectric vibrator, and is a view of the piezoelectric vibrating piece viewed from above with the lid substrate removed. 3 is a cross-sectional view of the piezoelectric vibrator taken along line AA shown in FIG. 2, and FIG. 4 is an exploded perspective view of the piezoelectric vibrator.

  As shown in FIGS. 1 to 4, the piezoelectric vibrator 1 of this embodiment includes a box-shaped package 10 in which a base substrate 2 and a lid substrate 3 are anodically bonded via a bonding material (not shown), and a cavity of the package 10. A surface-mounted piezoelectric vibrator 1 including a piezoelectric vibrating piece 5 housed in C. The piezoelectric vibrating reed 5 and the external electrodes 6, 7 installed on the first surface 2 a (the lower surface in FIG. 3) of the base substrate 2 are electrically connected by a pair of through electrodes 8, 9 penetrating the base substrate 2. ing.

  The base substrate 2 is formed in a plate shape with a transparent insulating substrate made of a glass material, for example, soda-lime glass. The base substrate 2 has a pair of through holes 21 and 22 in which a pair of through electrodes 8 and 9 are formed.

  Similar to the base substrate 2, the lid substrate 3 is a transparent insulating substrate made of a glass material, for example, soda-lime glass, and is formed in a plate shape that can be superimposed on the base substrate 2. A rectangular recess 3a is formed on the first surface 3b (the lower surface in FIG. 3) side of the lid substrate 3, and the base substrate 2 and the lid substrate 3 are placed with the recess 3a facing the base substrate 2 side. Are formed to form a cavity C for accommodating the piezoelectric vibrating reed 5. In a state where the cavity C is formed, the lid substrate 3 is anodically bonded to the base substrate 2 via a bonding material. That is, on the first surface 3 b side of the lid substrate 3, a recess 3 a is provided in the center portion, and a frame region 3 c serving as a bonding surface with the base substrate 2 is provided around the recess 3 a. Note that the bonding material of this embodiment is formed of a Si film, but the bonding material may be formed of Al. In addition, the bonding material can be formed of a Si bulk material whose resistance is reduced by doping or the like.

  The piezoelectric vibrating piece 5 is a tuning fork type vibrating piece formed from a piezoelectric material such as quartz, lithium tantalate, or lithium niobate, and vibrates when a predetermined voltage is applied. The piezoelectric vibrating piece 5 includes a pair of vibrating arm portions 24 and 25 extending in parallel to each other and a base portion that integrally connects and fixes base end portions along the extending direction of the pair of vibrating arm portions 24 and 25. 26 is a tuning fork type. The pair of vibrating arm portions 24 and 25 are arranged side by side in the width direction orthogonal to the thickness direction, and the distal end portion in the extending direction is a free end that vibrates in the width direction with the base end portion as a fixed end. . In the following description, in the piezoelectric vibrating piece 5, the extending direction of the vibrating arm portions 24 and 25 is simply referred to as the extending direction, and the vibrating arm portions 24 and 25 side along the extending direction is simply the front end side and the base portion 26. The side is simply referred to as the base end side, the arrangement direction of the vibrating arm portions 24 and 25 is simply referred to as the width direction, and the thickness direction of the piezoelectric vibrating piece 5 is simply referred to as the thickness direction.

  A pair of excitation electrodes (not shown) are formed on the outer surfaces of the pair of vibrating arms 24 and 25 to vibrate the vibrating arms 24 and 25 at a predetermined resonance frequency in a direction (width direction) approaching or separating from each other. Has been. In addition, a pair of mount electrodes (not shown) are formed on the outer surface of the base portion 26 and are electrically connected to the pair of excitation electrodes via extraction electrodes (not shown).

  As shown in FIGS. 2 and 3, the piezoelectric vibrating reed 5 configured as described above uses the second surface 2 b (upper surface in FIG. 3) of the base substrate 2 by using a bump B (see FIG. 3) such as gold. The bump electrodes 27 and 28 are bump-bonded to each other. Specifically, one excitation electrode among the excitation electrodes of the piezoelectric vibrating piece 5 is bump-bonded onto one lead-out electrode 27 via one mount electrode and bump B formed on the surface of the base portion 26. The other excitation electrode is bump-bonded onto the other lead-out electrode 28 via the other mount electrode and the bump B formed on the surface of the base portion 26.

  As described above, the piezoelectric vibrating reed 5 is joined by joining a part of the base portion 26 (portions far from the vibrating arm portions 24 and 25) onto the routing electrodes 27 and 28 on the package 10 side. The portion (hereinafter referred to as the mount portion 26a) is supported in a state of being lifted from the second surface 2b of the base substrate 2 with a support fixing point. In the mount portion 26a, the mount electrodes and the routing electrodes 27 and 28 are electrically connected to each other.

  Here, in the piezoelectric vibrating piece 5 of the present embodiment, between the mount portion 26a mounted on the package 10 and the connection portion 26b to which the base end portions of the vibrating arm portions 24 and 25 are connected on the base portion 26. In addition, a buffer portion 30 that is lower in rigidity than other portions of the base portion 26 and can absorb an impact along the thickness direction of the vibrating arm portions 24 and 25 is formed integrally with the base portion 26.

  In the buffer portion 30, a plurality of concave portions 33 formed by cutting along the thickness direction are alternately arranged along the extending direction of the vibrating arm portions 24 and 25 on both main surfaces in the thickness direction of the base portion 26. Is made up of. Each of the recesses 33 is formed in a groove shape extending linearly along the width direction, and is open toward both sides of the base portion 26 in the width direction. That is, the buffer portion 30 is configured by a spring portion in which the concave portions 33 are alternately formed so that the side cross-sectional shape is substantially W-shaped, and the elasticity in the thickness direction is locally higher than the other portions of the base portion 26. It is configured to be high. As described above, since the recess 33 is cut and formed on the main surface of the base portion 26, another portion of the base portion 26 (a portion other than the buffer portion 30) is present at the position where the recess portion 33 is present in the buffer portion 30. The cross-sectional area in the cross section perpendicular to the extending direction is smaller. That is, the thickness of the base portion 26 is locally thinner than the other portions at the location where the concave portion 33 is formed, and the presence of the thinned portion makes the buffer portion 30 more rigid than the other portions. Is set too low.

  The external electrodes 6 and 7 are installed on both sides of the first surface 2 a of the base substrate 2 in the longitudinal direction, and are electrically connected to the piezoelectric vibrating reed 5 through the through electrodes 8 and 9 and the routing electrodes 27 and 28. It is connected. More specifically, one external electrode 6 is electrically connected to one mount electrode of the piezoelectric vibrating piece 5 through one through electrode 8 and one routing electrode 27. The other external electrode 7 is electrically connected to the other mount electrode of the piezoelectric vibrating piece 5 through the other through electrode 9 and the other lead-out electrode 28.

  The through electrodes 8 and 9 are conductive core materials fixed integrally to the through holes 21 and 22, both ends in the through direction are flat, and have the same thickness as the thickness of the base substrate 2. Is formed. Each of the through-electrodes 8 and 9 completely closes the through-holes 21 and 22 to maintain the airtightness in the cavity C, and plays a role of conducting the external electrodes 6 and 7 with the lead-out electrodes 27 and 28. Yes. Specifically, one through electrode 8 is positioned below the lead-out electrode 27 between the external electrode 6 and the base portion 26 of the piezoelectric vibrating piece 5, and the other through electrode 9 is connected to the external electrode 7. And the vibrating arm portion 25 of the piezoelectric vibrating piece 5 are positioned below the routing electrode 28.

  When the piezoelectric vibrator 1 configured as described above is operated, a predetermined drive voltage is applied to the external electrodes 6 and 7 formed on the base substrate 2. Thereby, a current can be passed through each excitation electrode of the piezoelectric vibrating piece 5, and the pair of vibrating arm portions 24 and 25 can be vibrated at a predetermined frequency in a direction (width direction) in which the pair of vibrating arm portions 24 and 25 approach and separate from each other. The vibration of the pair of vibrating arm portions 24 and 25 can be used as a time source, a control signal timing source, a reference signal source, or the like.

In order to manufacture the above-described piezoelectric vibrating reed 5, first, an external pattern of the piezoelectric vibrating reed 5 having the vibrating arm portions 24 and 25 and the base portion 26 is formed on both surfaces of a wafer (not shown) by photolithography. At this time, a plurality of external patterns are formed on the wafer.
Next, both sides of the wafer are etched using the external pattern as a mask. As a result, the region not masked by the outer pattern can be selectively removed to form the outer shape of the piezoelectric vibrating piece 5. In this state, each piezoelectric vibrating piece 5 is connected to the wafer via a connecting portion (not shown).

  Here, the buffer portion 30 is formed on the base portion 26. Specifically, a region corresponding to the concave portion 33 of the buffer portion 30 is opened with respect to the outer shape pattern described above by photolithography. That is, the openings of the outer shape pattern are formed alternately at different positions in the extending direction on both main surfaces of the base portion 26. Then, etching processing (half etching) is performed on both surfaces of the wafer, using the external pattern formed in this way as a mask. Thereby, on the base part 26, the buffer part 30 in which the some recessed part 33 cut | disconnected and formed along the thickness direction is alternately arranged along the extending direction is formed.

Thereafter, the electrode film is patterned on the outer surface of the piezoelectric vibrating piece 5 by a known method to form the excitation electrode, the extraction electrode, and the mount electrode.
Then, a connecting step that finally connects the wafer and the piezoelectric vibrating piece 5 is cut, and a cutting process is performed in which the plurality of piezoelectric vibrating pieces 5 are separated from the wafer into individual pieces. As a result, a plurality of tuning-fork type piezoelectric vibrating reeds 5 can be manufactured at one time from one wafer.

Here, FIG. 5 is a cross-sectional view corresponding to FIG. 3, and is an explanatory diagram for explaining the operation of the piezoelectric vibrating piece 5.
As shown in FIG. 5, when the piezoelectric vibrator 1 receives an external impact or the like and the vibrating arm portions 24 and 25 of the piezoelectric vibrating piece 5 vibrate along the thickness direction, the distal ends of the vibrating arm portions 24 and 25 are packaged. 10 may come into contact with the inner surface (the second surface 2b of the base substrate 2 or the inner surface of the recess 3a of the lid substrate 3).

  In this case, the base portion 26 of the piezoelectric vibrating piece 5 in the present embodiment is formed with a buffer portion 30 having a lower rigidity than other portions of the base portion 26. Therefore, even if the tip ends of the vibrating arm portions 24 and 25 come into contact with the inner surface of the package 10, the impact due to the contact is transmitted to the buffer portion 30 of the base portion 26 through the vibrating arm portions 24 and 25. Absorbed by quickly elastically deforming along the direction. Then, the shock is absorbed by the buffer 30 so that the vibrations of the vibrating arms 24 and 25 are gradually attenuated, and the buffer 30 is restored, so that the piezoelectric vibrating reed 5 is located between the inner surface of the package 10. Thus, it is restored with a desired clearance.

  As described above, according to the present embodiment, since the buffer portion 30 is disposed on the base portion 26 of the piezoelectric vibrating piece 5, it is assumed that the tip ends of the vibrating arm portions 24 and 25 are in contact with the inner surface of the package 10 due to an external impact or the like. In addition, the shock can be absorbed by the buffer portion 30, thereby preventing the piezoelectric vibrating piece 5 from being damaged.

  By the way, when the length of the base portion 26 is shortened in order to reduce the size of the piezoelectric vibrating piece 5, the connection portion 26b of the base portion 26 with the vibrating arm portions 24 and 25 and the mount portion 26a with the bump B are provided. The distance approaches. Then, the vibration excited by the vibrating arm portions 24 and 25 is not sufficiently attenuated at the base portion 26 but leaks to the package 10 through the mount portion 26a, for example, and the resonance frequency is shifted as a result. Such a phenomenon is regarded as vibration leakage, and when this vibration leakage occurs, the loss during conversion from the electrical signal to mechanical vibration increases in addition to the problem of shifting the resonance frequency, so that the CI value increases and the quality is improved. There is also a problem of lowering.

  On the other hand, in the piezoelectric vibrating piece 5 of the present embodiment, the buffer portion 30 having a smaller cross-sectional area than the mount portion 26a and the connection portion 26b is formed between the mount portion 26a and the connection portion 26b of the base portion 26. Therefore, the route through which the vibration excited by the vibrating arm portions 24 and 25 is transmitted to the mount portion 26a can be narrowed. Therefore, the vibration can be confined on the vibrating arm portions 24 and 25 side, and the leakage of the vibration to the mount portion 26a side of the base portion 26 can be suppressed. Thereby, it is possible to suppress an increase in the CI value and to suppress a decrease in the quality of the output signal.

In the present embodiment, since the buffer portion 30 is formed integrally with the base portion 26 of the piezoelectric vibrating piece 5, it is not necessary to provide the buffer portion separately as in the first prior art described above. Therefore, an increase in the number of parts and a decrease in manufacturing efficiency can be suppressed.
In addition, unlike the second prior art described above, there is no need to provide a stepped portion in the package, so that an increase in the thickness of the package 10 can be suppressed and the package 10 can be made thinner.
Furthermore, unlike the third prior art described above, no recess is formed in the package, so that the strength of the package 10 can be maintained.

  In addition, since the buffer portion 30 of the present embodiment is formed in a spring shape in which the concave portions 33 are alternately formed, the shock absorbers 30 efficiently absorb the shock when the vibrating arm portions 24 and 25 vibrate in the thickness direction. be able to. Therefore, it is possible to provide the piezoelectric vibrating piece 5 that can effectively absorb the impact and suppress the breakage of the vibrating arm portions 24 and 25 and the like while suppressing an increase in the number of parts and a decrease in manufacturing efficiency. In addition, since the piezoelectric vibrator 1 according to the present embodiment includes the piezoelectric vibrating piece 5 described above, the piezoelectric vibrator 1 having sufficient strength and high reliability can be provided after being thinned. .

Next, modified examples of the piezoelectric vibrating piece 5 will be described with reference to FIGS.
(First modification)
6A and 6B are diagrams illustrating a piezoelectric vibrating piece according to a first modification, in which FIG. 6A is a plan view and FIG. 6B is a cross-sectional view taken along line BB in FIG. In addition, in each modification demonstrated below, about the structure similar to embodiment mentioned above, the same code | symbol is attached | subjected and description is abbreviate | omitted.
As shown in FIG. 6, in the piezoelectric vibrating piece 5 of this modification, grooves 41 and 42 that are recessed along the thickness direction are formed on both main surfaces of the vibrating arm portions 24 and 25, respectively. These groove portions 41 and 42 are formed in a rectangular shape with the extending direction of the vibrating arm portions 24 and 25 as a longitudinal direction in a plan view, and are formed from the base end portions of the vibrating arm portions 24 and 25 to approximately the middle. Yes.

  According to this configuration, by forming the groove portions 41 and 42, the excitation electrodes that make a pair in the vibrating arm portions 24 and 25 face each other on both sides of the groove portions 41 and 42. Can act. Thereby, even if the width of the vibrating arm portions 24 and 25 is narrowed, the electric field efficiency can be increased, and the size can be reduced while improving the quality.

  By forming the groove portions 41 and 42, the portions where the groove portions 41 and 42 are formed in the vibrating arm portions 24 and 25 are thinner than the other portions. Therefore, when the vibrating arm portions 24 and 25 are brought into contact with the inner surface of the package 10 due to external impact or the like, the piezoelectric vibrating reed 5 is easily damaged starting from the portions where the groove portions 41 and 42 are formed. On the other hand, as described above, the piezoelectric vibrating reed 5 of the present embodiment includes the buffer portion 30 in the base portion 26, so that the impact when the vibrating arm portions 24 and 25 vibrate in the thickness direction is efficiently treated. Therefore, the vibration arm portions 24 and 25 can be prevented from being damaged starting from the groove portions 41 and 42.

(Second modification)
7A and 7B are diagrams showing a piezoelectric vibrating piece according to a second modified example, in which FIG. 7A is a plan view and FIG. 7B is a cross-sectional view taken along line CC in FIG.
As shown in FIG. 7, in the piezoelectric vibrating piece 5 of this modification, hammer portions 44 and 45 having a width larger than that of the base end portion are formed at the distal end portions of the vibrating arm portions 24 and 25 (so-called “so-called”). , Hammerhead type).
According to this configuration, by forming the hammer portions 44 and 45, the tip ends of the vibrating arm portions 24 and 25 can be made heavier, and the moment of inertia during vibration can be increased. Therefore, the vibrating arm portions 24 and 25 can be easily vibrated, and the lengths of the vibrating arm portions 24 and 25 can be shortened accordingly, and further miniaturization can be easily achieved.

(Third Modification)
8A and 8B are diagrams showing a piezoelectric vibrating piece according to a third modification, in which FIG. 8A is a plan view, and FIG. 8B is a cross-sectional view taken along line DD in FIG.
As shown in FIG. 8, in the piezoelectric vibrating piece 5 of this modification, a pair of side arms 53 extending along the extending direction of the vibrating arm portions 24 and 25 are formed on the base portion 26 on both sides in the width direction of the base portion 26. It is integrally formed (so-called side arm type). Specifically, each side arm 53 extends from the base end portion of the base portion 26 toward both sides in the width direction, and from the outer end portion thereof toward the vibrating arm portions 24 and 25 side along the extending direction. It is extended. That is, each side arm 53 is positioned on both sides in the width direction of the base portion 26 and the base end portions of the vibrating arm portions 24 and 25, and the distal end portion is positioned at an intermediate portion of the vibrating arm portions 24 and 25 in the extending direction. doing.

  In this case, the front end portion of the side arm 53 can function as the mount portion 53a, and can be mounted on the package 10 via the mount portion 53a. That is, since the side arm 53 can be regarded as an extended portion of the base portion 26, it is possible to ensure a long distance between the connecting portion 26b to the vibrating arm portions 24 and 25 and the mount portion 53a. In this case, since the total length of the piezoelectric vibrating reed 5 is not increased, the size of the piezoelectric vibrating reed 5 is reduced, and vibration leakage is suppressed to prevent the CI value from increasing, thereby suppressing the quality of the output signal from decreasing. It becomes possible.

  In the present modification, the tip portion of the side arm 53 serves as a mount portion 53a that is joined to the package 10, and therefore, between the mount portion 53a and the connection portion 26b of the base portion 26 with the vibrating arm portions 24 and 25. The buffer part 30 should just be arrange | positioned in any arbitrary place of these. However, as in the illustrated example, the shock absorber 30 is provided on the upstream side of the vibration transmission path when the shock absorber 30 is provided on the side of the vibrating arms 24 and 25 rather than on the side arm 53 far from the vibrating arms 24 and 25. Can be said to be more effective.

(Fourth modification)
In addition, it is also possible to combine each modification mentioned above suitably. For example, like the 4th modification shown in FIG. 9, it is good also as a structure which combines all the characteristic parts of the 1st-3rd modification mentioned above, and it is good also as a structure which combines multiple if not all.

(5th modification)
FIG. 10 is a plan view showing a piezoelectric vibrating piece according to a fifth modification.
The piezoelectric vibrating piece 5 according to the fifth modification includes a base portion 26 disposed at the center in the width direction and a pair of vibrating arm portions 24 and 25 disposed on both sides of the base portion 26 in the width direction. 26 and a base support type in which the base end portions along the extending direction of the vibrating arm portions 24 and 25 are connected and fixed to each other.

In addition, a mount portion 26a to be joined to an electrode (leading electrode) on the package 10 side is formed at the distal end portion in the extending direction of the base portion 26, and the vibrating arm portions 24 and 25 are formed at the proximal end portions. A connecting portion 26b is formed to which the base end portion is connected. The connecting portion 26b extends from the base end portion of the base portion 26 along both sides along the width direction, and the base end portions of the vibrating arm portions 24 and 25 are fixed to the outer end portions thereof.
In the base portion 26, the buffer portion 30 described above is disposed between the mount portion 26a and the connection portion 26b.

  According to this configuration, in the base portion 26, a long distance can be secured between the connection portion 26b with the vibrating arm portions 24 and 25 and the mount portion 26a. As a result, since the total length of the piezoelectric vibrating piece 5 is not increased, the size of the piezoelectric vibrating piece 5 is reduced, and vibration leakage is suppressed to prevent the CI value from increasing, and the output signal quality is prevented from decreasing. It becomes possible.

  In each of the first to fifth modifications described above, the case where the buffer portion 30 is formed as a spring portion having a W-shaped side section has been described. However, other configurations of the buffer portion 30 may be employed. it can. Hereinafter, other modifications will be described.

(Sixth to ninth modifications)
11A and 11B are diagrams showing the piezoelectric vibrating pieces of the sixth to ninth modified examples, in which FIG. 11A is a plan view of the piezoelectric vibrating piece of the sixth modified example, and FIG. 11B is an EE of FIG. Sectional views along the lines, (c) to (e) are sectional views corresponding to FIG. 11 (b) of the piezoelectric vibrating reeds of the seventh to ninth modifications, respectively.
In the piezoelectric vibrating piece 5 in the sixth modified example shown in FIGS. 11A and 11B, the buffer portion 30 is formed by forming a pair of concave portions 33 opposed in the thickness direction on both main surfaces of the base portion 26. It is composed. Note that a plurality of pairs of the concave portions 33 opposed in the thickness direction may be formed along the extending direction.
Further, in the piezoelectric vibrating reed 5 of the seventh and eighth modified examples shown in FIGS. 11C and 11D, the buffer portion 30 is configured by forming the concave portion 33 on one main surface of the base portion 26. Yes.
Further, in the piezoelectric vibrating piece 5 of the ninth modification shown in FIG. 11E, the buffer portion is provided by providing concave portions 34 having substantially arc-shaped cross sections on both main surfaces of the base portion 26 at positions facing each other in the thickness direction. 30. Also in this case, the buffer portion 30 may be configured by providing the concave portion 34 only on one main surface.

(Tenth Modification to Twelfth Modification)
12A to 12C are plan views showing the piezoelectric vibrating reeds of the tenth to twelfth modified examples, respectively.
In the first to ninth modifications, the case in which the buffer portion 30 is formed by thinning by forming the concave portions 33 and 34 along the thickness direction of the piezoelectric vibrating piece 5 is shown, but the width direction of the base portion 26 is shown. The buffer portion 30 may be configured by cutting a recess along

  The buffer portion 30 of the tenth and eleventh modified examples shown in FIGS. 12A and 12B has a plurality of recesses 35 formed by cutting from both sides in the width direction of the base portion 26 toward the inside in the width direction. It is configured by being alternately arranged along the current direction. The buffer portion 30 of this modification can be formed simultaneously with the outer shape pattern when the outer shape pattern of the piezoelectric vibrating piece 5 is formed on the wafer.

  In particular, in the buffer portion 30 shown in FIG. 12A, the depths of the recesses 35 are increased, and the tips of the recesses 35 cut from one side edge along the width direction and the recesses 35 cut from the other side edge. The two are wrapped in the width direction of the base portion 26 by a dimension R1. Moreover, in the buffer part 30 shown in FIG.12 (b), the notch depth of the recessed part 35 is made small compared with the recessed part 35 shown in FIG.12 (a), and the recessed part 35 cut | disconnected from the one side edge along the width direction and The space | interval of the dimension R2 is ensured between the front-end | tips of the recessed part 35 cut | disconnected from the other side edge. In this case, the spring of FIG. 12 (a) having a large depth of cut can be more springy than that of FIG. 12 (b).

  In the piezoelectric vibrating piece 5 of the twelfth modified example shown in FIG. 12C, a plurality of concave portions 35 that are cut from both sides in the width direction of the base portion 26 toward the inside in the width direction are along the extending direction. The buffer part 30 is comprised by arranging in the same position. In this case, since the position of the recess 35 is symmetric on both sides of the base portion 26 in the width direction, the base portion 26 can be configured with good balance. In addition, the recessed part 35 in the tenth to twelfth modifications may or may not penetrate in the thickness direction of the base part 26. In the example of FIG. 12C, a plurality of the recesses 35 are formed along the extending direction, but a single recess may be used.

(13th modification and 14th modification)
FIGS. 13A and 13B are plan views showing the piezoelectric vibrating reeds of the thirteenth modification and the fourteenth modification, respectively.
In the piezoelectric vibrating piece 5 of the thirteenth modified example shown in FIG. 13A, the concave portions 35 are provided from both sides in the width direction of the base portion 26 toward the inside in the width direction, and the base portion 26 is along the extending direction. The buffer part 30 is comprised by providing the recessed part 33 similar to embodiment mentioned above, a 1st-5th modification, etc. on both main surfaces of the formation area of the recessed part 35. As shown in FIG.

  In the above-described embodiment and each modified example, by forming the recesses 33, 34, and 35 in the base portion 26 that reduce the cross-sectional area on the outer shape in the cross section orthogonal to the extending direction, it is more than other parts. Although the low-rigidity buffer portion 30 is configured, the apparent cross-sectional area defined by the dimensions on the outer shape is the same, but the substantial cross-sectional area occupied by the material portion can be reduced as compared with other parts. The buffer portion 30 with low rigidity can be configured.

  Specifically, in the piezoelectric vibrating piece 5 of the fourteenth modified example shown in FIG. 13B, the buffer portion 30 is configured by providing the base portion 26 with a concave portion or a through hole 36 serving as a void. That is, the buffer portion 30 is configured by locally forming a portion where the material density is reduced in the cross section perpendicular to the extending direction as compared with other portions of the base portion 26, and by reducing the material density. .

Here, the material density is the total cross-sectional area of the part where the material actually exists excluding voids such as holes formed inside the external shape with respect to the apparent cross-sectional area defined by the dimensions on the external shape. Refers to the ratio.
For example, when the outer cross section of the buffer portion 30 is rectangular, the apparent cross sectional area is a rectangular cross sectional area, but there are holes (such as through holes 36 as shown in FIG. 13B) inside the buffer portion 30. In this case, since that portion becomes a void where no material exists, the actual cross-sectional area (substantial cross-sectional area) is a value obtained by subtracting the sum of the cross-sectional areas of the void from the apparent cross-sectional area. Assuming that the material density of a portion where all the voids are filled with material is 1, the material density is lower than 1 in the portion where the voids are present, and the effective cross-sectional area becomes small due to the voids. As a result, the rigidity of the portion is lowered, and the function as the buffer portion 30 can be exhibited.

 In this case, the recesses and through-holes 36 may be provided so as to be scattered in a large number, or a single recess may be provided to reduce the substantial material density. For example, a concave portion or a through hole may be provided in the middle of the width direction of the base portion 26, and the region portion where the concave portion or the through hole is formed may be used as the buffer portion 30 with reduced rigidity, or a very small concave portion or the through hole 36 may be formed. By providing a large number of points, a portion having a small material density may be locally formed, and the portion may be used as the buffer portion 30.

(Oscillator)
Next, an embodiment of an oscillator according to the present invention will be described with reference to FIG.
As shown in FIG. 14, the oscillator 100 according to the present embodiment is configured such that the piezoelectric vibrator 1 is an oscillator electrically connected to the integrated circuit 101. The oscillator 100 includes a substrate 103 on which an electronic component 102 such as a capacitor is mounted. The above-described integrated circuit 101 for the oscillator is mounted on the substrate 103, and the piezoelectric vibrating piece 5 of the piezoelectric vibrator 1 is mounted in the vicinity of the integrated circuit 101. The electronic component 102, the integrated circuit 101, and the piezoelectric vibrator 1 are electrically connected by a wiring pattern (not shown). Each component is molded with a resin (not shown).

In the oscillator 100 configured as described above, when a voltage is applied to the piezoelectric vibrator 1, the piezoelectric vibrating piece 5 in the piezoelectric vibrator 1 vibrates. This vibration is converted into an electric signal by the piezoelectric characteristics of the piezoelectric vibrating piece 5 and input to the integrated circuit 101 as an electric signal. The input electrical signal is subjected to various processes by the integrated circuit 101 and is output as a frequency signal. Thereby, the piezoelectric vibrator 1 functions as an oscillator.
Further, by selectively setting the configuration of the integrated circuit 101, for example, an RTC (real-time clock) module or the like according to a request, the operation date and time of the device and the external device in addition to a single-function oscillator for a clock, etc. A function for controlling the time, providing a time, a calendar, and the like can be added.

  As described above, according to the oscillator 100 of the present embodiment, the piezoelectric vibrator 1 having sufficient strength and high reliability is provided after being thinned. Thus, a highly reliable high quality oscillator 100 can be provided. In addition to this, it is possible to obtain a highly accurate frequency signal that is stable over a long period of time.

(Electronics)
Next, an embodiment of an electronic apparatus according to the present invention will be described with reference to FIG. Note that the portable information device 110 having the above-described piezoelectric vibrator 1 will be described as an example of the electronic device. First, the portable information device 110 according to the present embodiment is represented by, for example, a mobile phone, and is a development and improvement of a wrist watch in the related art. The appearance is similar to that of a wristwatch, and a liquid crystal display is arranged in a portion corresponding to a dial so that the current time and the like can be displayed on this screen. Further, when used as a communication device, it is possible to perform communication similar to that of a conventional mobile phone by using a speaker and a microphone that are removed from the wrist and incorporated in the inner portion of the band. However, it is much smaller and lighter than conventional mobile phones.

(Portable information equipment)
Next, the configuration of the portable information device 110 of this embodiment will be described. As shown in FIG. 15, the portable information device 110 includes the piezoelectric vibrator 1 and a power supply unit 111 for supplying power. The power supply unit 111 is made of, for example, a lithium secondary battery. The power supply unit 111 includes a control unit 112 that performs various controls, a clock unit 113 that counts time, a communication unit 114 that communicates with the outside, a display unit 115 that displays various types of information, A voltage detection unit 116 that detects the voltage of the functional unit is connected in parallel. The power unit 111 supplies power to each functional unit.

  The control unit 112 controls each function unit to control operation of the entire system such as transmission and reception of audio data, measurement and display of the current time, and the like. The control unit 112 includes a ROM in which a program is written in advance, a CPU that reads and executes the program written in the ROM, and a RAM that is used as a work area of the CPU.

  The timer unit 113 includes an integrated circuit including an oscillation circuit, a register circuit, a counter circuit, an interface circuit, and the like, and the piezoelectric vibrator 1. When a voltage is applied to the piezoelectric vibrator 1, the piezoelectric vibrating reed 5 vibrates, and this vibration is converted into an electric signal by the piezoelectric characteristics of the crystal and is input to the oscillation circuit as an electric signal. The output of the oscillation circuit is binarized and counted by a register circuit and a counter circuit. Then, signals are transmitted to and received from the control unit 112 via the interface circuit, and the current time, current date, calendar information, or the like is displayed on the display unit 115.

The communication unit 114 has functions similar to those of a conventional mobile phone, and includes a radio unit 117, a voice processing unit 118, a switching unit 119, an amplification unit 120, a voice input / output unit 121, a telephone number input unit 122, and a ring tone generation unit. 123 and a call control memory unit 124.
The wireless unit 117 exchanges various data such as audio data with the base station via the antenna 125. The audio processing unit 118 encodes and decodes the audio signal input from the radio unit 117 or the amplification unit 120. The amplifying unit 120 amplifies the signal input from the audio processing unit 118 or the audio input / output unit 121 to a predetermined level. The voice input / output unit 121 includes a speaker, a microphone, and the like, and amplifies a ringtone and a received voice or collects a voice.

In addition, the ring tone generator 123 generates a ring tone in response to a call from the base station. The switching unit 119 switches the amplifying unit 120 connected to the voice processing unit 118 to the ringing tone generating unit 123 only when an incoming call is received, so that the ringing tone generated in the ringing tone generating unit 123 is transmitted via the amplifying unit 120. To the audio input / output unit 121.
The call control memory unit 124 stores a program related to incoming / outgoing call control of communication. The telephone number input unit 122 includes, for example, a number key from 0 to 9 and other keys. By pressing these number keys and the like, a telephone number of a call destination is input.

  When the voltage applied to each functional unit such as the control unit 112 by the power supply unit 111 falls below a predetermined value, the voltage detection unit 116 detects the voltage drop and notifies the control unit 112 of the voltage drop. . The predetermined voltage value at this time is a value set in advance as a minimum voltage necessary for stably operating the communication unit 114, and is, for example, about 3V. Upon receiving the voltage drop notification from the voltage detection unit 116, the control unit 112 prohibits the operations of the radio unit 117, the voice processing unit 118, the switching unit 119, and the ring tone generation unit 123. In particular, it is essential to stop the operation of the wireless unit 117 with high power consumption. Further, the display unit 115 displays that the communication unit 114 has become unusable due to insufficient battery power.

That is, the operation of the communication unit 114 can be prohibited by the voltage detection unit 116 and the control unit 112, and that effect can be displayed on the display unit 115. This display may be a text message, but as a more intuitive display, a x (X) mark may be attached to the telephone icon displayed at the top of the display surface of the display unit 115.
In addition, the function of the communication part 114 can be stopped more reliably by providing the power supply cutoff part 126 that can selectively cut off the power of the part related to the function of the communication part 114.

  As described above, according to the portable information device 110 of the present embodiment, since the piezoelectric vibrator 1 described above is provided, the highly reliable portable information device 110 with high reliability is provided after the thickness is reduced. it can. In addition to this, it is possible to display highly accurate clock information that is stable over a long period of time.

(Radio watch)
Next, an embodiment of a radio timepiece according to the present invention will be described with reference to FIG.
As shown in FIG. 16, the radio timepiece 130 of the present embodiment includes the piezoelectric vibrator 1 electrically connected to the filter unit 131, and receives a standard radio wave including timepiece information to accurately It is a clock with a function of automatically correcting and displaying the correct time.
In Japan, there are transmitting stations (transmitting stations) that transmit standard radio waves in Fukushima Prefecture (40 kHz) and Saga Prefecture (60 kHz), each transmitting standard radio waves. Long waves such as 40 kHz or 60 kHz have the property of propagating the surface of the earth and the property of propagating while reflecting the ionosphere and the surface of the earth, so the propagation range is wide, and the above two transmitting stations cover all of Japan. doing.

Hereinafter, the functional configuration of the radio timepiece 130 will be described in detail.
The antenna 132 receives a long standard wave of 40 kHz or 60 kHz. The long-wave standard radio wave is obtained by subjecting time information called a time code to AM modulation on a 40 kHz or 60 kHz carrier wave. The received long standard wave is amplified by the amplifier 133 and filtered and tuned by the filter unit 131 having the plurality of piezoelectric vibrators 1. The piezoelectric vibrator 1 in this embodiment includes crystal vibrator portions 138 and 139 having resonance frequencies of 40 kHz and 60 kHz, which are the same as the carrier frequency described above.

Further, the filtered signal having a predetermined frequency is detected and demodulated by the detection and rectification circuit 134. Subsequently, the time code is taken out via the waveform shaping circuit 135 and counted by the CPU 136. The CPU 136 reads information such as the current year, accumulated date, day of the week, and time. The read information is reflected in the RTC 137, and accurate time information is displayed.
Since the carrier wave is 40 kHz or 60 kHz, the crystal vibrator units 138 and 139 are preferably vibrators having the tuning fork type structure described above.

  In addition, although the above-mentioned description was shown in the example in Japan, the frequency of the long standard wave is different overseas. For example, in Germany, a standard radio wave of 77.5 KHz is used. Accordingly, when the radio timepiece 130 that can be used overseas is incorporated in a portable device, the piezoelectric vibrator 1 having a frequency different from that in Japan is required.

  As described above, according to the radio timepiece 130 of the present embodiment, since the piezoelectric vibrator 1 described above is provided, it is possible to provide a reliable and high-quality radio timepiece 130 while reducing the thickness. In addition to this, it is possible to count time stably and with high accuracy over a long period of time.

The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above-described embodiment, the piezoelectric vibrating piece 5 of the present invention is used for the surface mount type piezoelectric vibrator 1, but the present invention is not limited to this, and the piezoelectric vibrating piece of the present invention is applied to a cylinder package type piezoelectric vibrator. 5 may be adopted.

DESCRIPTION OF SYMBOLS 1 ... Piezoelectric vibrator 5 ... Piezoelectric vibrating piece 10 ... Package 24, 25 ... Vibrating arm part 26 ... Base part 26a, 53a ... Mount part 26b ... Connection part 30 ... Buffer part 33, 34, 35 ... Recessed part 36 ... Recessed part or through-hole DESCRIPTION OF SYMBOLS 100 ... Oscillator 101 ... Integrated circuit 110 ... Portable information device (electronic device) 113 ... Time measuring part 130 ... Radio wave clock 131 ... Filter part

Claims (7)

A pair of vibrating arms arranged side by side in the width direction;
In the piezoelectric vibrating piece comprising: a base portion to which a base end side in the extending direction of the pair of vibrating arm portions is connected;
Between the mount portion mounted on the package and the connection portion to which the proximal end side of the vibrating arm portion is connected, the rigidity of the vibrating arm is low compared to other portions of the base portion. A piezoelectric vibrating piece, wherein a buffer portion capable of absorbing an impact in a thickness direction perpendicular to the width direction and the extending direction with respect to a portion is formed integrally with the base portion.   2. The piezoelectric vibrating piece according to claim 1, wherein the buffer portion is formed to have a smaller cross-sectional area perpendicular to the extending direction than other portions of the base portion.   The buffer portion is configured by alternately forming recesses formed by cutting from both sides of the base portion in the thickness direction or the width direction along the extending direction. 2. The piezoelectric vibrating piece according to 2.   A piezoelectric vibrator comprising the piezoelectric vibrating piece according to claim 1 hermetically sealed in a package.   An oscillator, wherein the piezoelectric vibrator according to claim 4 is electrically connected to an integrated circuit as an oscillator.   5. An electronic apparatus, wherein the piezoelectric vibrator according to claim 4 is electrically connected to a time measuring unit.   A radio-controlled timepiece wherein the piezoelectric vibrator according to claim 4 is electrically connected to a filter portion.

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