JP4751074B2 - Piezoelectric vibrator, oscillator, and electronic device - Google Patents

Description

  The present invention relates to a piezoelectric vibrator, an oscillator, and an electronic device. For example, the present invention relates to a tuning fork type crystal vibrator having a crystal piece having a frequency adjusting weight.

  A crystal resonator is an electronic element indispensable for manufacturing industrial products, and is widely used as a clock function or a frequency control mechanism in electronic devices such as oscillators, information communication devices and portable devices, and home appliances.

  There are various types of crystal resonators. Among them, there is a tuning fork type crystal resonator in which a crystal piece is processed into a tuning fork shape.

  A tuning fork-type crystal resonator (hereinafter simply referred to as a crystal resonator) is configured by sealing a crystal resonator element having a pair of vibrating portions (arms) in a vacuum case. Oscillates by vibrating the part symmetrically.

  In the case of the tuning fork type, the frequency of the crystal resonator is adjusted by previously attaching a weight material to the vibration portion in the manufacturing process to form the weight portion and removing it with a laser beam.

  Here, the structure of the conventional weight part is demonstrated using FIG.

  FIG. 9A shows a cross section of the vibrating part of the quartz crystal vibrating piece viewed in the arm direction of the tuning fork, and is a BB cross sectional view of FIG. 9B. On the other hand, FIG.9 (b) is AA sectional drawing in Fig.9 (a).

  The vibrating portion of the quartz crystal vibrating piece is constituted by a quartz crystal 92, a Cr layer 93 that is a Cr (chrome) thin film is formed on the surface thereof, and an Au layer 94 that is an Au (gold) thin film is further formed on the surface of the Cr layer 93. Is formed. The Cr layer 93 and the Au layer 94 constitute a base metal for forming the weight portion.

  The base metal is formed together when an excitation electrode (not shown) is formed on the surface of the crystal 92.

  Cr has good adhesion to quartz but does not form an alloy with solder, while Au forms an alloy with solder but has poor adhesion to quartz.

  For this reason, by making the base metal in this way a two-layer structure of Cr and Au, it becomes possible to ensure adhesion to the crystal and to perform good soldering.

  The quartz crystal vibrating piece includes a base portion (not shown) for fixing the vibrating piece to the airtight container and a vibrating portion formed continuously from the base portion. At the tip of the vibration part, a weight part composed of an Ag layer 95 is formed on the surface of the base metal, and the frequency of the vibration part is adjusted by the mass of the Ag layer 95.

  If the Ag layer 95 is partially deleted by a laser beam or the like, the frequency can be finely adjusted.

  Although the weight portion can be made of Au, since Au is expensive, it is generally made of Ag, which is an inexpensive substance that lacks chemical stability and oxidation resistance. Yes.

  Although not shown, the surface of the Ag layer 95 is covered with an Au thin film to prevent deterioration of the Ag layer 95 due to oxidation or gas adsorption.

There are the following documents as techniques related to the weight part of such a crystal resonator.
In this technique, a plurality of weight portions are formed in advance on the vibration portion, and the weight portions are removed to facilitate fine adjustment of the frequency.

  Here, the problem to be solved by the present invention will be described with reference to FIG. FIG. 10 schematically shows a phenomenon in which components constituting the weight portion diffuse into the underlying electrode film.

  The passage of time through the interface 85 between the element constituting the weight part (showing the Ag element of the film 95 in FIG. 10) and the underlying metal material (the surface is the Au layer 94 and the lower layer is the Cr layer 93) At the same time, intermetallic diffusion occurs. This will be briefly described.

  The Ag element constituting the weight portion is a region immediately below the frequency adjusting weight portion, that is, a region that directly faces the weight portion and forms an interface (hereinafter referred to as a direct facing interface forming region, and denoted by reference numeral 86). To spread. An arrow indicated by reference numeral 88 represents this diffusion. Diffusion is a function of the temperature of the region in question and occurs more actively at higher temperatures. The driving force for causing diffusion is based on the concentration difference of the element of interest. Therefore, the Ag element constituting the weight part continues to diffuse over a long period of time toward the direct interface formation region 86 with a low Ag concentration as time passes. As time passes, the concentration of the Ag element in the directly facing interface formation region increases, and the Ag further diffuses in the region on the base side based on the Ag concentration difference as indicated by reference numeral 89. As a result, the concentration of the Ag element in the Au layer 94 in the weight vicinity region 87 also gradually increases.

  On the other hand, although omitted in FIG. 10, the Au element in the interface forming region directly diffuses through the interface 85 in the direction of the weight based on the concentration difference of the Au element.

  As a result, the center of gravity moves and deforms in the weight part and the vicinity of the weight part, and it may be difficult to ensure long-term stability of the frequency.

  Further, when the surface of the Ag layer 95 is covered with an Au thin film (not shown), intermetallic diffusion occurs between the Ag layer 95 and the Au thin film.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a structure of a weight part for frequency adjustment and a structure of a base metal around the weight part that are not easily affected by intermetallic diffusion between Ag as a weight material and Au as a base metal. .

  In order to achieve the above object, the present invention provides a tuning-fork type piezoelectric vibrating piece having a pair of vibrating portions on which excitation electrodes are formed, and a base metal formed on the surface of the vibrating portion and made of gold. A frequency adjusting weight formed on the base metal on both sides of the vibrating portion so as to have the same film structure, a sealed container enclosing the piezoelectric vibrating piece, and the excitation electrode, The piezoelectric vibrator is provided with an external electrode formed outside the sealed container.

  In order to achieve the above object, a tuning-fork type piezoelectric vibrating piece having a pair of vibrating parts on which excitation electrodes are formed, a base metal formed on the surface of the vibrating part and having a surface made of gold, A frequency adjusting weight portion formed on a base metal on one surface of the vibrating portion; a diffusion preventing portion formed on the base metal on the base side adjacent to the frequency adjusting weight portion; and the piezoelectric vibrating piece. A piezoelectric vibrator comprising: a sealed container that encloses and an external electrode connected to the excitation electrode and formed outside the sealed container.

  Further, in order to achieve the above object, a combination of the above two inventions at the same time is also effective. That is, a tuning-fork type piezoelectric vibrating piece having a pair of vibrating parts on which excitation electrodes are formed, a base metal formed on the surface of the vibrating part and having a surface made of gold, and surfaces on both sides of the vibrating part. A frequency adjusting weight portion formed on the base metal so as to have the same film structure; a diffusion prevention portion formed on the base metal adjacent to the frequency adjusting weight portion; and the piezoelectric vibrating piece. A piezoelectric vibrator comprising: a sealed container to be sealed; and an external electrode connected to the excitation electrode and formed outside the sealed container.

  Further, the piezoelectric vibrator is characterized in that the diffusion preventing portion is formed of a metal-free film region having no metal film on the main surface. Here, the main surface is a surface on which the weight portion is formed.

  In addition, an oscillator is characterized in that the above-described piezoelectric vibrator is used as an oscillator connected to an integrated circuit.

  Furthermore, an electronic apparatus is characterized in that the above-described piezoelectric vibrator is connected to a timer unit.

  According to the present invention, the long-term stability of the frequency of the tuning fork type crystal resonator can be achieved at low cost.

  Conventionally, a weight portion for frequency adjustment has been formed only on one side of the vibrating arm portion. A diffusion between metals occurs between Ag constituting the weight part and the base metal Au, and the center of gravity position of the weight part slightly changes in a direction perpendicular to the vibrating direction of the vibrating arm part. Is causing fluctuations. Therefore, a structure that can cancel the influence of the movement of the center of gravity, which is a factor causing the frequency fluctuation, is adopted. That is, weight portions having the same structure are arranged on both sides of the vibrating arm portion. As a result, the two weight portions arranged across the vibrating arm portion of the crystal are subjected to substantially the same thermal influence, so that substantially the same diffusion occurs in the two weight portions. As a result, the movement of the center of gravity of the weight on one side is canceled by the movement of the center of gravity on the other side in the opposite direction, and it can be considered that the movement of the center of gravity is the same as the movement of the two weights as a whole. As a result, frequency fluctuations are suppressed.

  Furthermore, even if the center of gravity moves based on the diffusion generated between the weight Ag and the Au thin film covering the surface, the center of gravity can be moved by arranging the weights of the same structure on both sides of the vibrating arm. The effect can be canceled for the same reason.

  In addition, it is possible to create weight portions having the same structure on both sides of the vibrating arm portion without major process changes or introduction of new equipment.

  FIG. 1A is a perspective view showing the outer shape of the quartz crystal resonator element according to the first embodiment of the present invention.

  The quartz crystal vibrating piece 1 is a piezoelectric vibrating piece made of a flat crystal single crystal having a tuning fork shape. The quartz vibrating piece 1 extends in a pair of arms and forms a vibrating portion. It is composed of a base 30 that is continuous with one end. The other end side of the vibrating arm portion 20 is an open end.

  The outer dimensions of the vibrating arm 20 are approximately 1700 [μm] in length, 320 [μm] in width, and 130 [μm] in thickness.

  Although not shown, the vibrating arm portion 20 is formed with excitation electrodes for applying a voltage to the vibrating arm portion 20 to vibrate.

  The excitation electrode has a two-layer structure of a Cr layer deposited on the surface of quartz and an Au layer further deposited on the surface of this Cr layer.

  Weight portions 3 for adjusting the frequency are formed on both surfaces of the vibrating arm portion 20 on the open end side.

  1 (b) and 1 (c) are views showing a cross section of the vibrating arm portion 20, and FIG. 1 (b) is a cross-sectional view taken along the line AA in FIG. 1 (a). 1 (c) shows a cross section of only one side of the vibrating arm portion 20 along BB in FIG. 1 (a). Since the other vibrating arm portion 20 has the same structure, the illustration thereof is omitted.

  As shown in the figure, a base metal 4 having a two-layer structure of a Cr layer 6 and an Au layer 7 is formed on the surface of the crystal 5. The Cr layer 6 is formed on the surface of the crystal 5, and the Au layer 7 is formed on the surface of the Cr layer 6.

  The base metal 4 is formed together with the excitation electrode by forming a film by sputtering or vapor deposition.

  The weight 3 is composed of an Ag layer 9 formed on the surface of the Au layer 7 as shown in FIG. 1 (d) and 1 (e) are views showing a modification of the weight portion 3, and, like FIG. 1 (c), one side of the vibrating arm portion 20 in BB of FIG. 1 (a). Only the cross section is shown. Since the other vibrating arm portion 20 has the same structure, the illustration thereof is omitted. In the cross-sectional views shown in FIGS. 1C, 1D, and 1E, the upper and lower surfaces are referred to as main surfaces, and the left and right surfaces are referred to as side surfaces.

  FIG. 1 (d) shows a case where the surface of the Ag layer 9 is covered with a Cr thin film 10, which prevents oxidation of the Ag layer 9 and gas adsorption. The Cr thin film 10 may be formed of Au. FIG. 1E shows a structure in which an Ag layer 9 is sandwiched between a Cr thin film 8 and a Cr thin film 10. The role of the Cr thin film 8 utilizes the fact that the rate at which Ag and Au diffuse in the Cr film is extremely small as will be described later.

The length of the weight part 3 (arm direction) is about 600 μm, and the thickness of the Ag layer 9 is about 3 to 4 μm.
[Quartz crystal manufacturing process]
Next, a manufacturing process of a crystal resonator using the crystal vibrating piece 1 will be described with reference to the flowchart of FIG.

  First, the external shape of the crystal vibrating piece 1 is formed from a single crystal of crystal (step 5). The outer shape is formed by etching a wafer cut and polished from a single crystal crystal into a tuning fork shape.

  Next, an excitation electrode is formed on the crystal piece on which the outer shape is formed (step 10). This electrode formation is performed by forming Cr and Au on the surface of the crystal vibrating piece 1 by sputtering or vapor deposition to form the base metal 4 and etching it into an electrode shape.

  Next, the weight portions 3 having the same structure are formed on both sides of the tip portion of the crystal vibrating piece 1 (step 15). In this step, Ag is formed on the front and back surfaces of the vibrating arm portion 20 of the crystal vibrating piece 1 by, for example, a vapor deposition method. In the vapor deposition method, the quartz wafer set in the vapor deposition jig is formed while rotating and revolving in the film formation chamber, so the thickness of the Ag layer that forms the weight part on the front and back of the vibrating piece is reduced. It is possible to match. In addition, even when the Ag layer is sandwiched between Cr layers as shown in FIG. 1 (e), it can be easily formed by switching the respective vapor deposition ports prepared with Cr and Ag raw materials.

  Next, the frequency of the crystal vibrating piece 1 is adjusted (step 20). This frequency adjustment is performed by removing a part of the weight 3 with a laser so that the frequency falls within the range of the design value while driving the crystal vibrating piece 1 and measuring the frequency. Although the weight portions are formed on both surfaces of the resonator element, since the two weights are processed into substantially the same shape by the laser, the shape of the weight maintains symmetry.

  The quartz crystal vibrating piece 1 manufactured in this way is soldered to a member (plug) constituting the base of the quartz crystal resonator, and then sealed in a sealed container in a vacuum state and capped (step 25). The sealed container is provided with external electrodes such as lead terminals and surface mount terminals, and is connected to the excitation electrodes formed on the crystal vibrating piece 1.

  The crystal resonator that has been capped and has an outer shape undergoes screening (step 30), and then undergoes an electrical property test (step 35) to become a finished product.

  Screening (heat depletion) is a process in which the crystal resonator is heated for a certain period of time and a change that occurs in the crystal resonator is preliminarily issued.

  The crystal resonator of the present embodiment is manufactured through the above steps.

  Next, a second embodiment for reducing frequency fluctuation due to spreading will be described. In the present embodiment, a structure for preventing diffusion is set in the vicinity of the weight portion adjacent to the weight portion of the crystal vibrating piece. As described with reference to FIG. 10, the Ag element in the weight portion diffuses directly into the interface formation region 86 and further diffuses in the Au layer 94 toward the base side (indicated by reference numeral 89). The second embodiment provides a method for preventing this diffusion.

  FIG. 3 is a diagram for explaining the second embodiment. FIG. 3 shows a specific structure of the diffusion preventing unit 14 disposed in the weight vicinity region 15. FIG. 3 shows a structure in which the upper Au layer 7 is removed by a predetermined width W1 in the film structure of the Cr layer 6 and the Au layer 7 that form the base metal. With this structure, the influence of Ag diffusing in the Au layer in the direction of the weight adjacent region 15 that is continuous with the Au layer 7 of the excitation electrode in the region 12 that forms the interface directly opposite to the Ag layer in the weight portion is eliminated. Is possible.

  Here, with reference to FIG. 10, diffusion of the Cr layer 93, which is the lower layer film of the base metal 4, and the Ag element will be briefly described.

  From the direct facing interface forming region 86 to the lower Cr layer 93, Ag element diffusion occurs as indicated by reference numeral 90 based on the concentration difference. However, the phenomenon in which Ag diffuses in the Cr layer is extremely slow compared to the case where Ag element diffuses in the Au layer. Similarly, the phenomenon in which the Ag element diffuses in the Cr layer toward the base side (indicated by reference numeral 91) is very slow. Therefore, in practice, the influence of Ag diffusion in the Cr layer 93 may be ignored. This embodiment is particularly effective in such a case.

  The crystal resonator including the diffusion preventing unit 14 having the above-described structure can be manufactured according to the above-described crystal resonator manufacturing flowchart, but supplements the following two points.

  In the electrode formation in step 10 of the manufacturing flowchart, the diffusion preventing portion 14 is disposed in the weight portion vicinity region 15. The structure in which the Au layer 7 is removed with the width W1 can be easily realized by means such as lithography. The value of W1 is preferably a width of several tens of μm to 100 μm in consideration of an error in the formation position of the weight portion formed in the next process.

  In addition, the present embodiment is effective when the weight portion is disposed only on one side as in the prior art as shown in FIG. 3, and is also effective when the weight portion is on both sides.

  Moreover, as for the structure of a weight part, FIG.1 (d) shown in Example 1 and FIG.1 (e) are also applied naturally. The other steps are the same as those in the first embodiment, and thus description thereof is omitted.

  Next, a third embodiment of the present invention will be described. In the third embodiment, as a modification of the structure of the diffusion prevention unit 14 shown in the second embodiment, a metal-free film region 16 that does not have a metal film is disposed on the main surface on which the weight 3 is configured. A piezoelectric vibrator is provided.

  FIG. 4 is a schematic diagram for explaining the third embodiment. In FIG. 4, the diffusion preventing portion 14 disposed in the weight vicinity region 15 has a structure in which the Cr layer 6 and the Au layer 7 are not formed on the upper and lower main surfaces in which the weight portion 3 is formed, with a width of W2. . Here, this is defined as a metal-free film region and is represented by reference numeral 16. As a result, there is no path for diffusion on the main surface in the direction from the region 12 that forms the interface directly opposite to the Ag layer of the weight portion to the vicinity of the weight portion 15, so that no intermetallic diffusion occurs, and thus stable. The frequency can be maintained.

  The manufacture of the piezoelectric vibrator having the above-described metal-free film region as the diffusion preventing portion is basically the same as that described in the second embodiment, and the weight portion is a crystal vibrating piece as in the second embodiment. It may be arranged on both sides or on one side. Further, the configuration of the weight portion is naturally applied to FIGS. 1D and 1E shown in the first embodiment.

  The metal-free film region 16 can be formed by using a laser in addition to the lithography method. The frequency adjustment (coarse adjustment) is performed in step 20 after the weight part is formed in step 15 of the manufacturing process flowchart of FIG. 2, but in the coarse adjustment process, before the coarse adjustment operation is started, diffusion prevention is performed. The metal-free film region 16 can be formed by irradiating the part with laser and evaporating the metal film on the main surface which is the irradiated surface. After the formation of the metal-free film region, the conventional roughening operation may be performed subsequently. Since the coarse tuning operation is performed at the stage where the quartz crystal vibrating piece is connected to the wafer, it is not necessary to perform new positioning even when a metal-free film is formed, and the laser beam trajectory can be easily controlled. Therefore, it is possible to easily carry out without preparing new equipment and without greatly increasing the manufacturing cycle time.

  As an example of an embodiment of a piezoelectric vibrator manufactured by the manufacturing process described above, a configuration of a cylinder-type piezoelectric vibrator in which a tuning-fork type crystal vibrating piece is sealed with a bottomed cylindrical case will be described with reference to the drawings. explain.

  FIG. 5 is a schematic configuration diagram illustrating an example of the piezoelectric vibrator according to the present embodiment. In FIG. 5, this piezoelectric vibrator has a tuning-fork type crystal vibrating piece 1. An excitation electrode (not shown) is formed on the surface of the crystal vibrating piece 1. This excitation electrode is made of Cr and Au. Furthermore, weights having the same film structure (not shown) are provided on the front and back surfaces of the two vibrating arm portions 20 of the crystal vibrating piece 1.

  The mount portion 1a of the quartz crystal resonator element 1 is soldered and fixed to two leads 42 that pass through a substantially cylindrical airtight terminal 40 called a plug. A case 44 indicated by an imaginary line (one-dot chain line) is covered so as to cover the crystal vibrating piece 1, and this case 44 is fitted to the outer periphery of the airtight terminal 40. Since the case 44 and the outer periphery of the hermetic terminal 40 are fitted in a vacuum atmosphere, the space surrounding the crystal vibrating piece 1 in the case 44 is kept sealed in a vacuum state.

  An excitation electrode (not shown) formed on the surface of the quartz crystal vibrating piece 1 is connected to the two leads 42 through the mount portion 1a. The lead 42 is extended outside the sealed container to form an external electrode 42a.

  FIG. 6 is a schematic configuration diagram in which the piezoelectric vibrator according to the present embodiment is configured using another sealed container. FIG. 6A is a schematic plan view showing the configuration, and FIG. 6B is a diagram showing an AA cross section of FIG. The piezoelectric vibrator has a tuning-fork type crystal vibrating piece 1. An excitation electrode (not shown) is formed on the surface of the crystal vibrating piece 1. This excitation electrode is made of Cr and Au. Furthermore, a weight having the same film structure (not shown) is provided on one surface of the two vibrating arm portions 20 of the crystal vibrating piece 1.

  The quartz crystal resonator element 1 is fixed and fixed to the joint 46 of the base 45 of the box-shaped ceramic package with a conductive adhesive 47. The base 45 is hermetically sealed in a vacuum with a metal lid 48 using means such as electron beam welding or vacuum seam welding. An excitation electrode (not shown) formed on the surface of the crystal vibrating piece 1 is connected to an external electrode 49 outside the base through an internal connection (not shown) through a joint 46.

  Next, as a fourth embodiment according to the present invention, an example of an oscillator using the piezoelectric vibrator according to any of the first to third embodiments described above as an oscillator and connected to an integrated circuit will be described.

  FIG. 7 is a plan view showing an example of the configuration of a tuning fork type crystal oscillator using a tuning fork type crystal resonator as a piezoelectric vibrator, and shows a surface mount type piezoelectric oscillator using the tuning fork type crystal resonator. .

  In FIG. 7, a tuning fork type crystal resonator 51 is set at a predetermined position on a substrate 52, and an integrated circuit (IC) 53 for an oscillator is disposed adjacent to the crystal resonator. An electronic component 54 such as a capacitor is also mounted. These components are electrically connected by a wiring pattern (not shown).

  The mechanical vibration of the vibrating piece of the tuning fork type crystal resonator 51 is converted into an electric signal by the piezoelectric characteristics of the crystal and input to the integrated circuit 53. In the integrated circuit 53, signal processing is performed, and a frequency signal is output to function as an oscillator. Each of these components is molded with a resin (not shown).

  By appropriately selecting the integrated circuit 53, in addition to the single-function oscillator for a clock, there are functions for controlling the operation date and time of the device and external device, and providing the user with time and calendar information.

  Since the oscillator is configured by connecting the piezoelectric vibrator according to the present embodiment as an oscillator to the integrated circuit 53, the frequency characteristics of the piezoelectric vibrator hardly change even when the oscillator is used for a long time in a severe environment. Therefore, the oscillator can be maintained with high accuracy.

  Next, as a fifth embodiment according to the present invention, an example of an electronic device in which the piezoelectric vibrator according to any one of the first to third embodiments described above is connected to a timer unit will be described. Here, as an example of an electronic device, a preferred embodiment in a portable information device represented by a mobile phone will be described in detail.

  First, as a premise, the portable information device according to the present embodiment 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 the dial so that the current time and the like can be displayed on this screen.

  When used as a communication device, it can be removed from the wrist and communicated in the same manner as a conventional mobile phone by a speaker and a microphone built in the band. However, it is much smaller and lighter than conventional mobile phones.

  Next, a functional configuration of the portable information device according to the present embodiment will be described with reference to the drawings.

FIG. 8 is a block diagram functionally showing an example of the configuration of the portable information device according to the present embodiment.
In FIG. 8, a power supply unit 101 is a power supply unit that supplies power to each functional unit described later, and is specifically realized by a lithium ion secondary battery.

  A control unit 102, a timing unit 103, a communication unit 104, a voltage detection unit 105, and a display unit 108, which will be described later, are connected in parallel to the power supply unit 101, and power is supplied from the power supply unit 101 to each functional unit.

  The control unit 102 controls each function unit to be described later, and performs operation control of the entire system such as transmission and reception of audio data, measurement and display of the current time, and the like. Specifically, the control unit 102 is realized by a program written in advance in a ROM, a CPU that reads and executes the program, a RAM that is used as a work area of the CPU, and the like.

  The time measuring unit 103 includes an integrated circuit including an oscillation circuit, a register circuit, a counter circuit, an interface circuit, and the like, and a tuning fork type crystal resonator manufactured in the manufacturing process shown in FIG.

  The mechanical vibration of the tuning fork type crystal resonator is converted into an electric signal by the piezoelectric characteristics of the crystal and input to an oscillation circuit formed by a transistor and a capacitor. The output of the oscillation circuit is binarized and counted by a register circuit and a counter circuit. Signals are transmitted to and received from the control unit through the interface circuit, and the current time, current date, or calendar information is displayed on the display unit 107.

  The communication unit 104 has functions similar to those of a conventional mobile phone, and includes a radio unit 104a, a voice processing unit 104b, an amplification unit 104c, a voice input / output unit 104d, a ring tone generation unit 104e, a switching unit 104f, and a call control memory. Part 104g and telephone number input part 104h.

  The wireless unit 104a transmits and receives various data such as voice data to and from the base station via the antenna. The audio processing unit 104b encodes / decodes an audio signal input from the radio unit 104a or an amplification unit 104c described later. The amplifying unit 104c amplifies the signal input from the audio processing unit 104b or the audio input / output unit 104d described later to a predetermined level. The voice input / output unit 104d is specifically a speaker and a microphone, and amplifies a ringtone and a received voice or collects a speaker voice.

  In addition, the ring tone generator 104e generates a ring tone in response to a call from the base station. The switching unit 104f switches the amplifying unit 104c connected to the voice processing unit 104b to the ringing tone generating unit 104e only when an incoming call is received, so that the generated ringing tone is transmitted to the voice input / output unit 104d via the amplifying unit 104c. To be output.

  The call control memory 104g stores a program related to incoming / outgoing call control of communication. The telephone number input unit 104h is specifically composed of 0 to 9 number keys and some other keys, and inputs the telephone number of the destination.

  The voltage detection unit 105 detects the voltage drop and notifies the control unit 102 when the voltage applied to each functional unit including the control unit 102 by the power supply unit 101 falls below a predetermined value. To do.

  The predetermined voltage value is a value set in advance as a minimum voltage necessary for stably operating the communication unit 104, and is, for example, a voltage of about 3V. Upon receiving the voltage drop notification from the voltage detection unit 105, the control unit 102 prohibits the operations of the radio unit 104a, the voice processing unit 104b, the switching unit 104f, and the ring tone generation unit 104e. In particular, it is essential to stop the operation of the wireless unit 104a with high power consumption. At the same time, the display unit 107 displays that the communication unit 104 has become unusable due to insufficient battery power.

The operation of the communication unit 104 can be prohibited by the functions of the voltage detection unit 105 and the control unit 102, and a message to that effect can be displayed on the display unit 107.
As the present embodiment, the function of the communication unit can be stopped in a more complete form by providing the power cutoff unit 106 that can selectively cut off the power supply of the part related to the function of the communication unit.

  The display indicating that the communication unit 104 has become unusable may be made by a text message, but more intuitively by a method such as marking the phone icon on the display unit 107 with a cross (X). Good.

  By using the piezoelectric vibrator according to the present embodiment for electronic devices such as portable information devices as described above, the frequency characteristics of the piezoelectric vibrator can be obtained even if the electronic device is used for a long period of time in a harsh environment. Since it is difficult to change, the electronic device can be maintained with high accuracy.

It is a figure explaining 1st Embodiment. 5 is a flowchart for explaining a manufacturing process of the crystal resonator according to the embodiment. It is a figure explaining 2nd Embodiment. It is a figure explaining 3rd Embodiment. It is a schematic block diagram which shows an example of the piezoelectric vibrator which concerns on this embodiment. It is a schematic block diagram which shows another example of the piezoelectric vibrator which concerns on this embodiment. It is a top view which shows an example of a structure of the oscillator which concerns on 4th Embodiment. It is a block diagram which shows one example of a structure of the electronic device which concerns on 5th Embodiment functionally. It is a figure explaining the conventional weight part. It is a figure explaining diffusion of a weight part constituent element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Crystal resonator element 1a Mount part 3 Weight part 4 Base metal 5 Crystal 6 Cr layer 7 Au layer 8 Cr thin film 9 Ag layer 10 Cr thin film 12 Direct opposing interface formation area 14 Diffusion prevention part 15 Weight part vicinity area 16 Non-metal film area 20 Vibrating arm (vibrating part)
30 Base 40 Airtight terminal (plug)
42 Lead 42a External electrode 44 Case 45 Base 46 Joining portion 47 Conductive adhesive 48 Lid 49 External electrode 51 Tuning fork type crystal resonator 52 Substrate 53 Integrated circuit 54 Electronic component 85 Interface between the weight portion and the surface of the base metal 86 Directly facing Interface formation region 87 Weight region vicinity 88 Diffusion from the weight portion directly to the interface formation region 89 Diffusion from the interface formation region to the base side 90 Diffusion of elements constituting the weight portion from the direct interface formation region to the lower layer film of the base metal 91 Base Diffusion of constituent elements of the weight part to the base side of the metal lower layer film 92 Crystal 93 Cr layer 94 Au layer 95 Ag layer 101 Power supply part 102 Control part 103 Timing part 104 Communication part 104a Radio part 104b Sound processing part 104c Amplifying part 104d Voice Input unit 104e Ring tone generation unit 104f Switching unit 104g Call control memory unit 104 Telephone number input section 105 voltage detection unit 106 power-off unit 107 display unit

Claims (6)

A tuning-fork type piezoelectric vibrating piece having a pair of vibrating portions formed with excitation electrodes;
A base metal formed on the surface of the vibrating portion, the surface of which is composed of gold;
A frequency adjusting weight formed on the base metal on one or both sides of the vibrating portion;
Of the base metal on the base side adjacent to the frequency adjusting weight portion, a diffusion preventing portion in which only the gold is removed by a predetermined width, and
A sealed container enclosing the piezoelectric vibrating piece;
An external electrode connected to the excitation electrode and formed outside the sealed container;
A piezoelectric vibrator characterized by comprising:   2. The piezoelectric vibrator according to claim 1, wherein the base metal is made of chromium and the gold formed on the surface of the chromium, and the frequency adjusting weight is made of silver.   The piezoelectric vibrator according to claim 2, further comprising a chromium thin film or a gold thin film formed on a surface of the frequency adjusting weight portion.   The piezoelectric vibrator according to claim 3, further comprising a Cr film between the base metal and the frequency adjusting weight.   An oscillator using the piezoelectric vibrator according to any one of claims 1 to 4 as an oscillator connected to an integrated circuit.   An electronic apparatus using the piezoelectric vibrator according to any one of claims 1 to 4 connected to a timer unit.

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