JP5782536B1 - Piezoelectric vibrating piece and piezoelectric vibrator - Google Patents

Abstract

Provided is a piezoelectric vibrating piece 10 that realizes both reduction in size and reduction in CI value, and that spurious vibration hardly influences main vibration. A piezoelectric vibrating piece 10 that is formed in a rectangular plate shape and has a mesa portion 12 formed on both a first main surface A and a second main surface B and that vibrates in a thickness-slip mode is separated in the Z direction. The pair of mount electrodes 26 and 28 are formed so that they can be supported, and the height MY of the step of the mesa portion 12 is 3 μm or more and 15 μm or less. [Selection] Figure 3

Description

  The present invention relates to a piezoelectric vibrating piece and a piezoelectric vibrator.

  2. Description of the Related Art Conventionally, a piezoelectric vibrating piece that outputs a predetermined frequency with respect to an external voltage by using a piezoelectric effect, and a piezoelectric vibrator that accommodates it in a package are known. Such a piezoelectric vibrator is used as a time source, a timing source of a control signal, a reference signal source, and the like on a driving circuit such as a mobile phone, a portable information terminal device, and a radio clock.

  Various types of piezoelectric vibrating pieces are known when classified by vibration mode. As one of them, an AT vibrating piece having a thickness-shear vibration mode is known. The AT vibrating reed is formed in a rectangular plate shape in plan view, and a voltage is applied to the excitation electrodes formed on the main surfaces of the front and back surfaces of the rectangular plate, so that each main surface is in the surface direction. They move in opposite phases.

  Further, a “mesa shape” is known as the main surface shape of the AT vibrating piece. The mesa shape is a shape in which the vibration region (region where the excitation electrode is formed) of the main surface of the AT vibrating piece is formed thicker than the thickness of the peripheral portion. It becomes possible to suitably reduce vibration energy leakage to the outside of the confinement and AT vibrating piece. Since the vibration energy leakage can be reduced in this way, the CI value (Crystal Impedance) of the piezoelectric vibrating piece is lowered, and it is possible to realize a reduction in power consumption. Patent Documents 1 and 2 disclose a piezoelectric vibrating piece having a mesa shape.

JP 2013-34217 A JP 2002-118440 A

However, the above prior art has the following problems.
In recent years, the demand for downsizing of the piezoelectric vibrating piece and the piezoelectric vibrator is further increased. However, when the piezoelectric vibrating piece is downsized, the CI value is likely to increase. That is, both the downsizing and the reduction of the CI value are achieved. Is difficult.
Further, in the piezoelectric vibrating piece having a mesa shape, unnecessary vibration (hereinafter referred to as spurious) occurs in the step portion of the mesa shape, and the spurious influences the main vibration, so that the temperature characteristics and the like of the piezoelectric vibrating piece can be improved. May decrease.

  Accordingly, the present invention has been made to solve the above-described problem, and achieves both miniaturization and reduction of the CI value, and a piezoelectric vibrating piece and a piezoelectric vibrator in which spurious vibration hardly affects the main vibration. The purpose is to provide.

  In order to solve the above problems, the piezoelectric vibrating piece of the present invention is formed in a rectangular plate shape, a mesa shape is formed on at least one of the first main surface and the second main surface, and vibrates in a thickness-shear mode. The resonator element is formed so as to be supported at two points spaced apart in the long side direction, and the height of the mesa-shaped step is 3 μm or more.

As a result of the simulation performed by the inventors of the present application, when the piezoelectric vibrating piece is supported at two points separated in the long side direction, the piezoelectric vibrating piece is supported at one side only in the long side direction. In comparison, it has been found that the CI value can be reduced.
On the other hand, when the mesa-shaped step is low, it is difficult to confine vibration energy in the mesa-shaped portion, and spurious vibration is likely to occur in a region other than the mesa-shaped region. On the other hand, when the height of the mesa-shaped step is 3 μm or more, spurious vibrations are less likely to occur, and spurious vibrations existing in the proximity range of the main vibration frequency are reduced. Therefore, even if the outer dimensions of the piezoelectric vibrating piece vary due to manufacturing errors, the influence of spurious vibration on the main vibration can be suppressed.
Therefore, it is formed so that it can be supported at two points separated in the long side direction, and the height of the mesa-shaped step is set to 3 μm or more, thereby realizing both miniaturization and CI value reduction, and spurious. It is possible to provide a piezoelectric vibrating piece in which vibration hardly affects the main vibration.

The height of the mesa-shaped step is preferably 15 μm or less.
If the mesa shape has a high level difference, the mesa shape itself is greatly deformed, and spurious vibrations due to the deformation of the boundary portion of the mesa shape are likely to occur. On the other hand, when the height of the mesa-shaped step is 15 μm or less, spurious vibrations are less likely to occur, and spurious vibrations existing in the proximity range of the main vibration frequency are reduced. Therefore, even if the outer dimensions of the piezoelectric vibrating piece vary due to manufacturing errors, the influence of spurious vibration on the main vibration can be suppressed. Therefore, by setting the height of the mesa-shaped step to 15 μm or less, it is possible to provide a piezoelectric vibrating piece in which spurious vibration hardly affects the main vibration.

Moreover, it is desirable to be able to support the peripheral portion of the piezoelectric vibrating piece.
By supporting the piezoelectric vibrating piece at the peripheral portion away from the mesa shape, it becomes easy to confine the vibration energy in the mesa shape portion, and spurious vibration is less likely to occur. Therefore, it is possible to provide a piezoelectric vibrating piece in which spurious vibration hardly affects the main vibration.

On the other hand, in the piezoelectric vibrator of the present invention, the above-described piezoelectric vibrating piece is accommodated in a cavity formed by a base substrate and a lid substrate.
According to this configuration, since the piezoelectric vibrating piece described above is provided, it is possible to provide both a reduction in size and a reduction in the CI value, and a piezoelectric vibrator in which spurious vibrations are less likely to affect the main vibration.

  Since the piezoelectric vibrating piece of the present invention is formed so as to be supported at two points separated in the long side direction, it is possible to achieve both reduction in size and reduction in CI value. In addition, since the height of the mesa-shaped step is formed to be 3 μm or more, it is possible to provide a piezoelectric vibrating piece in which spurious vibration hardly affects the main vibration.

It is the perspective view which expanded the piezoelectric vibrator concerning an embodiment. It is side surface sectional drawing in the AA of FIG. It is explanatory drawing of the piezoelectric vibrating piece which concerns on embodiment, (a) is a top view, (b) is sectional drawing in the BB line of (a). It is a graph which shows the vibration characteristic of the piezoelectric vibrating piece with a level | step difference of 2 micrometers, (a) is a case where the external dimension of a X direction is changed, (b) is a case where the external dimension of a Z direction is changed. It is a graph which shows the vibration characteristic of the piezoelectric vibrating piece of 3 micrometers of steps, (a) is a case where the external dimension of a X direction is changed, (b) is a case where the external dimension of a Z direction is changed. It is a graph which shows the vibration characteristic of a 7-micrometer-thick piezoelectric vibrating piece, (a) is a case where the external dimension of a X direction is changed, (b) is a case where the external dimension of a Z direction is changed. It is a graph which shows the vibration characteristic of the piezoelectric vibration piece of level | step difference 9 micrometers, (a) is a case where the external dimension of a X direction is changed, (b) is a case where the external dimension of a Z direction is changed. It is a graph which shows the vibration characteristic of a 13-micrometer-thick piezoelectric vibrating piece, (a) is a case where the external dimension of a X direction is changed, (b) is a case where the external dimension of a Z direction is changed. It is a graph which shows the vibration characteristic of a 14-micrometer-thick piezoelectric vibration piece, (a) is a case where the external dimension of a X direction is changed, (b) is a case where the external dimension of a Z direction is changed. It is a graph which shows the vibration characteristic of a 15-micrometer-thick piezoelectric vibrating piece, (a) is a case where the external dimension of a X direction is changed, (b) is a case where the external dimension of a Z direction is changed. It is a graph which shows the relationship between a level | step difference dimension and CI value. It is a block diagram of the oscillator provided with the piezoelectric vibrator according to the embodiment. It is a block diagram of the electronic device provided with the piezoelectric vibrator according to the embodiment. It is a block diagram of the radio timepiece provided with the piezoelectric vibrator according to the embodiment.

Embodiments of the present invention will be described with reference to the drawings. In the following description, the X-axis direction of the AT-cut quartz crystal vibrating piece is the X direction, the Y′-axis direction is the Y direction, and the Z′-axis direction is the Z direction. In addition, the direction of the tip (one side) of the arrow in the illustrated coordinate system is the + direction, and the direction of the base end (the other side) of the arrow is the − direction.
(Piezoelectric vibrator)
FIG. 1 is a developed perspective view of the piezoelectric vibrator according to the embodiment, and FIG. 2 is a side sectional view taken along line AA of FIG. The piezoelectric vibrator 1 has a piezoelectric vibrating piece 10 accommodated in a cavity C of a package 5. The package 5 is formed by overlapping the base substrate 2 and the lid substrate 3.

As shown in FIG. 1, the base substrate 2 includes a bottom wall portion 80 formed in a rectangular shape when viewed from the Y direction, and a side wall portion 90 erected in the + Y direction from the peripheral edge of the bottom wall portion 80. I have. The bottom wall portion 80 and the side wall portion 90 are formed of a ceramic material or the like.
As shown in FIG. 2, a pair of internal electrodes 82 is formed on the surface of the bottom wall portion 80 inside the cavity C. The pair of internal electrodes 82 are formed apart from each other in the Z direction. A pair of external electrodes 84 is formed on the surface of the bottom wall 80 outside the cavity C. The pair of external electrodes 84 are formed apart from both ends in the Z direction. The internal electrode 82 and the external electrode 84 are connected by a through electrode 83 that penetrates the bottom wall 80 in the thickness direction.

  The lid substrate 3 is formed of a ceramic material or the like in a rectangular shape when viewed from the Y direction. The peripheral edge portion of the lid substrate 3 is bonded to the end surface in the Y direction of the side wall portion 90 of the base substrate 2. A cavity C is formed in a region surrounded by the bottom wall 80 and the side wall 90 of the base substrate 2 and the lid substrate 3.

  Inside the cavity C, a piezoelectric vibrating piece 10 is accommodated. As will be described later, a pair of mount electrodes 26 and 28 are formed at both ends in the Z direction on the main surface of the piezoelectric vibrating piece 10. The mount electrodes 26 and 28 are mounted on the internal electrode 82 of the base substrate 2 via the conductive paste 50.

(Piezoelectric vibrating piece)
3A and 3B are explanatory views of the piezoelectric vibrating piece according to the embodiment, in which FIG. 3A is a plan view and FIG. 3B is a cross-sectional view taken along line BB in FIG. As shown in FIG. 3A, the piezoelectric vibrating piece 10 of the embodiment includes a piezoelectric plate 11, an excitation electrode 22 formed on the surface of the piezoelectric plate 11, a mount electrode 26 formed around the excitation electrode, 28.

  The piezoelectric plate 11 is formed by AT-cutting a piezoelectric material such as quartz. The piezoelectric plate 11 is formed so that the length in the Z direction is longer than that in the X direction. That is, the Z direction is the long side direction, and the X direction is the short side direction. As shown in FIG. 3B, the piezoelectric plate 11 has a thickness direction in the Y direction and main surfaces on both sides in the Y direction. The piezoelectric vibrating piece 10 of the embodiment is a so-called mesa-type piezoelectric vibrating piece, and has a mesa-shaped portion (hereinafter, referred to as a mesa portion) 12 in which the centers of both main surfaces protrude in the Y direction. . An inclined surface 14 is connected between the surface of the mesa portion 12 and the surface of the peripheral edge portion 16 of the piezoelectric plate 11.

  As shown in FIG. 3A, an excitation electrode 22 is formed on the surface of the mesa unit 12. Further, on the surface of the peripheral portion 16, a mount electrode 26 is formed in the + Z direction, and a mount electrode 28 is formed in the -Z direction. The pair of mount electrodes 26 and 28 are disposed at both ends in the Z direction with the mesa 12 interposed therebetween. A lead electrode 24 that connects the excitation electrode 22 and the mount electrode 26 is formed.

  The excitation electrode 22, the lead-out electrode 24, and the mount electrode 26 described above are formed on both main surfaces of the piezoelectric plate. As shown in FIG. 3B, the mount electrodes 26A and 26B formed on both main surfaces A and B in the + Z direction are connected to each other via a side electrode 27 formed on the + Z side surface of the piezoelectric plate 11. ing. In addition, the mount electrodes 28A and 28B formed on both main surfaces A and B in the −Z direction are connected to each other via a side electrode 29 formed on the −Z side surface of the piezoelectric plate 11. On the first main surface A, the excitation electrode 22A and the mount electrode 26A are connected via the routing electrode 24A. On the second main surface B, the excitation electrode 22B and the mount electrode 28B are connected via the routing electrode 24B.

(Simulation of spurious vibration)
In general, when the external dimensions of the piezoelectric vibrating piece 10 (piezoelectric plate 11) change due to manufacturing errors or the like, the occurrence of spurious vibrations changes. Since the outer dimensions of the piezoelectric vibrating piece 10 are expected to vary due to manufacturing errors and the like, when the outer dimensions of the piezoelectric vibrating piece 10 are within the variation range, it is required to exhibit good vibration characteristics. .
The inventor of the present application conducts a simulation in order to investigate the occurrence of spurious vibration according to the step (height) dimension of the mesa portion 12 and how the spurious vibration changes depending on the outer dimension of the piezoelectric vibrating piece 10. Went.

  The simulation conditions are as follows. In the piezoelectric vibrating piece 10 shown in FIG. 3, the length PZ of the piezoelectric vibrating piece 10 is PZ = 720 μm, the length of the piezoelectric vibrating piece 10 is PX = 540 μm, and the thickness of the piezoelectric vibrating piece 10 in the Y direction PY = The thickness was 64 μm. Although the thickness PY of the piezoelectric vibrating piece 10 is set to 64 μm, it has been confirmed that the piezoelectric vibrating piece having PY of 10 μm to 120 μm exhibits similar vibration characteristics. The dimensions of the piezoelectric vibrating piece 10 described above are standard dimensions of a piezoelectric vibrating piece enclosed in a so-called 1210 size piezoelectric vibrator (length in the Z direction is 1.2 mm, length in the X direction is 1.0 mm). . On the other hand, it is considered that a piezoelectric vibrating piece enclosed in a 1612 size piezoelectric vibrator larger than the 1210 size also exhibits similar vibration characteristics. In addition, it is considered that the piezoelectric vibration piece sealed in a piezoelectric vibrator having a size of 1008 smaller than the 1210 size or smaller than that exhibits the same vibration characteristics. Therefore, the present invention is not limited to the piezoelectric vibrating piece having the dimensions described above.

  Further, the thickness (level difference) MY in the Y direction of the mesa portion 12 was variously set, with the length MZ in the Z direction of the mesa portion 12 being 480 μm and the length MX in the X direction of the mesa portion 12 being 410 μm. And about each MY, the vibration characteristic at the time of changing the length PX of the X direction of the piezoelectric vibrating piece 10 and the length PZ of the Z direction of the piezoelectric vibrating piece 10 was investigated.

  4 to 10 are graphs showing simulation results of vibration characteristics of the piezoelectric vibrating piece. The horizontal axis of each figure is the amount of change (μm) with respect to the design dimension of the piezoelectric vibrating piece. In each figure, (a) shows a case where the length PX in the X direction of the piezoelectric vibrating piece is changed, and (b) shows a case where the length PZ in the Z direction of the piezoelectric vibrating piece is changed. Moreover, the vertical axis | shaft of each figure shows the frequency (ppm) of the frequency of a piezoelectric vibrating piece with respect to a design frequency. A white circle indicates the frequency of the main vibration, and a black circle indicates the frequency of the spurious vibration. A line connecting a plurality of black circles continuously indicates the frequency of the spurious vibration mode close to the main vibration.

  A rectangular region surrounded by a thick broken line at the center of the graph (hereinafter referred to as a central region) is a region where the dimensional change of the piezoelectric vibrating piece is ± 2 μm and the frequency change rate is ± 2000 ppm. Since the outer diameter of the piezoelectric vibrating piece is expected to vary by about ± 2 μm due to manufacturing errors, it is required to exhibit good vibration characteristics within the range of this variation. Further, if the spurious vibration mode exists in the proximity range of ± 2000 ppm with respect to the main vibration of the piezoelectric vibrating piece, the spurious vibration affects the main vibration, and it becomes difficult to exhibit good vibration characteristics. Therefore, it can be said that the better the vibration characteristics, the easier the spurious vibration mode is in the central region.

  FIG. 4 shows vibration characteristics of a piezoelectric vibrating piece having a step MY of 2 μm. In FIG. 4A, there are four spurious vibration modes in the central area, and in FIG. 4B, there are four spurious vibration modes in the central area. Therefore, it can be said that it is difficult to obtain good vibration characteristics in the piezoelectric vibrating piece having the step MY of 2 μm because the spurious vibration affects the main vibration. In addition, when the level | step difference MY of the mesa part 12 shown in FIG. As a result, it is considered that the vibration generated in the area other than the mesa portion 12 becomes spurious vibration.

  FIG. 5 shows vibration characteristics of a piezoelectric vibrating piece having a step MY of 3 μm. In FIG. 5A, there are four spurious vibration modes in the central region, but in FIG. 5B, only two spurious vibration modes exist in the central region. From this result, it can be said that when the step MY is 3 μm, good vibration characteristics can be easily obtained even if the outer dimension of the piezoelectric vibrating piece varies in the Z direction.

  FIG. 6 shows vibration characteristics of a piezoelectric vibrating piece having a step MY of 7 μm. In FIG. 6A, only two spurious vibration modes exist in the central region, and in FIG. 6B, only two spurious vibration modes exist in the central region. From this result, it is considered that when the step MY is 7 μm, good vibration characteristics can be obtained even if the outer dimensions of the piezoelectric vibrating piece vary in the X direction and the Z direction.

  FIG. 7 shows vibration characteristics of a piezoelectric vibrating piece having a step MY of 9 μm. In FIG. 7A, only two spurious vibration modes exist in the central region, and in FIG. 7B, only one spurious vibration mode exists in the central region. From this result, it is considered that when the step MY is 9 μm, extremely good vibration characteristics can be obtained even if the outer dimensions of the piezoelectric vibrating piece vary in the X direction and the Z direction.

  FIG. 8 shows vibration characteristics of a piezoelectric vibrating piece having a step MY of 13 μm. In FIG. 8A, only one spurious vibration mode exists in the central region, but in FIG. 8B, three spurious vibration modes exist in the central region. From this result, it can be said that when the step MY is 13 μm, good vibration characteristics can be easily obtained even if the outer dimension of the piezoelectric vibrating piece varies in the X direction.

  FIG. 9 shows vibration characteristics of a piezoelectric vibrating piece having a step MY of 14 μm. In FIG. 9A, only one spurious vibration mode exists in the central region, and in FIG. 9B, only one spurious vibration mode exists in the central region. From this result, it is considered that when the step MY is 14 μm, extremely good vibration characteristics can be obtained even if the outer dimensions of the piezoelectric vibrating piece vary in the X direction and the Z direction.

  FIG. 10 shows vibration characteristics of a piezoelectric vibrating piece having a step MY of 15 μm. In FIG. 10A, only two spurious vibration modes exist in the central region, and in FIG. 10B, only two spurious vibration modes exist in the central region. From this result, it is considered that when the step MY is 15 μm, good vibration characteristics can be obtained even if the outer dimensions of the piezoelectric vibrating piece vary in the X direction and the Z direction.

From the above results, if the step MY of the piezoelectric vibrating piece is set to 3 μm or more, good vibration characteristics can be easily obtained. Moreover, if the step MY of the piezoelectric vibrating piece is set to 7 μm or more, particularly good vibration characteristics can be obtained.
Note that if the level difference MY is larger than 15 μm, the strain deformation of the mesa portion 12 itself in FIG. 3 increases, so that it is considered that the spurious vibration due to the deformation of the boundary portion of the mesa portion 12 increases. Therefore, good vibration characteristics can be obtained by setting the step MY of the piezoelectric vibrating piece to 15 μm or less.

  FIG. 11 is a graph showing the relationship between the step size of the piezoelectric vibrating piece and the CI value. The horizontal axis in FIG. 11 is the level difference MY, and the vertical axis is the CI value. In addition, the case where the piezoelectric vibrating piece is supported at both ends by a pair of mount electrodes spaced apart in the Z direction as in the present embodiment is indicated by a circle, and the piezoelectric vibrating piece is separated by only one end portion in the Z direction as in the prior art The case of holding and supporting is indicated by a triangle. According to this graph, in the double-sided piezoelectric vibrating piece, the CI value becomes the minimum value when the step MY is around 8 μm. As described above, if the step MY is 3 μm or more and 15 μm or less, the CI value is relatively small, which is preferable. Further, if the step MY is 5 μm or more and 12 μm or less, the CI value is particularly small, which is more preferable.

  On the other hand, the CI value when the piezoelectric vibrating reed is supported on both ends is lower as a whole than when the cantilever is supported. Therefore, the CI value can be reduced by supporting the piezoelectric vibrating piece by both ends.

  As described in detail above, the piezoelectric vibrating piece 10 of this embodiment shown in FIG. 3 is formed in a rectangular plate shape, and the mesa portion 12 is formed on both the first main surface A and the second main surface B. In the AT-cut piezoelectric vibrating piece 10 that vibrates in the thickness-slip mode, the AT-cut piezoelectric vibrating piece 10 is formed so as to be supported by a pair of mount electrodes 26 and 28 separated in the Z direction, and the step height MY of the mesa portion 12 is 3 μm or more. It was set as the structure which is.

As a result of the simulation described above, when the piezoelectric vibrating reed 10 is supported in a cantilever manner by a pair of mount electrodes 26 and 28 separated in the Z direction, the piezoelectric vibrating reed is supported in a cantilever manner only on one side in the Z direction. Thus, the CI value can be reduced.
On the other hand, when the level difference of the mesa portion 12 is low, it becomes difficult to confine vibration energy in the mesa portion 12, and spurious vibrations are likely to occur in a region other than the mesa portion 12. On the other hand, when the height MY of the step of the mesa portion 12 is 3 μm or more, spurious vibrations are less likely to occur and spurious vibrations existing in the proximity range of the main vibration frequency are reduced. Therefore, even if the outer dimension of the piezoelectric vibrating piece 10 varies due to manufacturing errors, the influence of spurious vibration on the main vibration can be suppressed.
Therefore, it is formed so as to be supported by a pair of mount electrodes 26 and 28 separated in the Z direction, and the height MY of the step of the mesa portion 12 is set to 3 μm or more, so that both miniaturization and CI value reduction can be achieved. It is possible to provide the piezoelectric vibrating piece 10 that is realized and that the spurious vibration hardly affects the main vibration.

Further, the height MY of the step of the mesa portion 12 is desirably 15 μm or less.
When the level difference of the mesa portion 12 is high, the strain deformation of the mesa portion 12 itself becomes large, and spurious vibration due to the deformation of the boundary portion of the mesa portion 12 is likely to occur. On the other hand, when the height MY of the step of the mesa portion 12 is 15 μm or less, spurious vibrations are less likely to occur, and spurious vibrations existing in the proximity range of the main vibration frequency are reduced. Therefore, even if the outer dimensions of the piezoelectric vibrating piece vary due to manufacturing errors, the influence of spurious vibration on the main vibration can be suppressed. Therefore, by setting the height MY of the step of the mesa portion 12 to 15 μm or less, it is possible to provide the piezoelectric vibrating piece 10 in which the spurious vibration hardly affects the main vibration.

It is desirable that the pair of mount electrodes 26 and 28 be configured to be supported at the peripheral portion of the piezoelectric vibrating piece 10.
By supporting the piezoelectric vibrating piece 10 at the peripheral portion away from the mesa portion 12, it becomes easy to confine vibration energy in the mesa portion 12, and spurious vibrations are less likely to occur. Therefore, it is possible to provide the piezoelectric vibrating piece 10 in which the spurious vibration hardly affects the main vibration.

On the other hand, in the piezoelectric vibrator 1 of the present invention shown in FIG. 2, the above-described piezoelectric vibrating piece 10 is accommodated in the cavity C formed by the base substrate 2 and the lid substrate 3.
According to this configuration, since the piezoelectric vibrating reed 10 described above is provided, it is possible to provide both the size reduction and the CI value reduction, and it is possible to provide the piezoelectric vibrator 1 in which the spurious vibration hardly affects the main vibration. .

(Oscillator)
Next, an embodiment of an oscillator according to the present invention will be described with reference to FIG.
As shown in FIG. 12, 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. On the substrate 103, the above-described integrated circuit 101 for the oscillator is mounted, and 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 10 in the piezoelectric vibrator 1 vibrates. This vibration is converted into an electric signal by the piezoelectric characteristics of the piezoelectric vibrating piece 10 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 that achieves both miniaturization and reduction of the CI value and has a spurious vibration hardly affecting the main vibration is provided. An oscillator 100 that can obtain a highly accurate frequency signal with low power consumption can be provided.

(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 of the present embodiment is represented by, for example, a mobile phone, and is a development and improvement of a wrist watch in the prior 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.

  Next, the configuration of the portable information device 110 of this embodiment will be described. As shown in FIG. 13, 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 piece 10 vibrates, and this vibration is converted into an electric signal by the piezoelectric characteristics of quartz or the like, 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, the piezoelectric vibrator 1 that achieves both miniaturization and reduction of the CI value and is less susceptible to spurious vibrations on the main vibration is provided. Therefore, the portable information device 110 that can display highly accurate clock information with low power consumption can be provided.

(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. 14, the radio timepiece 130 of this 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 and 60 kHz have both the property of propagating the ground surface 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 transmitters 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 radio wave of 40 kHz or 60 kHz. The long standard radio wave is obtained by subjecting time information called a time code to AM modulation on a carrier of 40 kHz or 60 kHz. 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 according to this embodiment includes piezoelectric vibrator portions 138 and 139 having resonance frequencies of 40 kHz and 60 kHz that 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.

  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, a standard radio wave of 77.5 KHZ is used in Germany. 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-controlled timepiece 130 of the present embodiment, the piezoelectric vibrator 1 that achieves both miniaturization and reduction of the CI value and is less susceptible to spurious vibrations on the main vibration is provided. Therefore, it is possible to provide a radio timepiece 130 that can count time with high power consumption and high accuracy.

The technical scope of the present invention is not limited to the above-described embodiment, and appropriate modifications can be made without departing from the spirit of the present invention.
For example, the package of the piezoelectric vibrator is not limited to the material and structure of the embodiment, and may be a package of various materials and structures.
In the piezoelectric vibrating piece according to the embodiment, the length in the Z direction is longer than that in the X direction, but the length in the X direction may be longer than that in the Z direction.

  A ... 1st main surface B ... 2nd main surface C ... Cavity MY ... Height of level | step difference 1 ... Piezoelectric vibrator 2 ... Base board 3 ... Lid board | substrate 10 ... Piezoelectric vibrating piece 12 ... Mesa part (mesa shape) 26,28 ... Mount electrode

Claims (3)

In a piezoelectric vibrating piece that is formed in a rectangular plate shape with the Z′-axis direction as a longitudinal direction, and has a mesa shape on at least one of the first main surface and the second main surface, and vibrates in a thickness-slip mode,
It is a peripheral part adjacent to the mesa shape on which the excitation electrode is formed, and is formed to be supportable at a part on the short side at two points separated in a direction parallel to the long side direction, and A piezoelectric vibrating piece having a mesa-shaped step height of 3 μm or more.   The piezoelectric vibrating piece according to claim 1, wherein the height of the mesa-shaped step is 15 μm or less.   A piezoelectric vibrator in which the piezoelectric vibrating piece according to claim 1 or 2 is accommodated in a cavity formed by a base substrate and a lid substrate.

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