Patent Application
20110148249
The present invention relates to a Surface Mount Device (SMD) type piezoelectric vibrator in which a piezoelectric vibrating reed is sealed in a cavity formed between two bonded substrates, a piezoelectric vibrator manufacturing method to manufacture the same, an oscillator, electronic equipment and a radio-controlled timepiece having the piezoelectric vibrator.
In recent years, piezoelectric vibrators using crystals or the like have been used in mobile phones or personal digital assistants, as a time source or a timing source such as a control signal, or a reference signal source and the like. Various types of piezoelectric vibrators are known. As one of them, a Surface Mount Device (SMD) type piezoelectric vibrator is known.
It is generally desirable with piezoelectric vibrators that the equivalent resistance values (effective resistance value, Re) of the piezoelectric vibrator is suppressed to a lower level. Since piezoelectric vibrators with low equivalent resistance values can vibrate the piezoelectric vibrating reed using less electric power, they are more energy efficient piezoelectric vibrators.
As one of the common methods of suppressing the equivalent resistance value, there is known a method of making an inner portion of the sealed cavity C with the piezoelectric vibrating reed 203 sealed therein closer to a vacuum as shown in
The getter material 220 is formed along a longitudinal direction of the vibration am portions 210 at both of the outsides of the pair of vibration arm portions 210 in a width direction of the piezoelectric vibrating reed 203. When gettering the getter material 220, there is a problem in that products become attached to the vibration arm portions 210 and the frequency of the piezoelectric vibrating reed 203 is changed.
In addition, after the gettering process, generally, metallic weight materials 211 provided at front ends of the vibration arm portions 210 are irradiated with a laser and the metallic weight materials 211 is trimmed, thereby performing a minute regulation (minute regulation process) of the frequencies of the piezoelectric vibrating reeds 203. However, when the frequency after the gettering process greatly gets out of a permissible range, it is difficult or impossible to limit the frequency of the piezoelectric vibrating reed 203 in the minute regulation process within the permissible range.
Thus, the invention is made in view of the above circumstances, and an object thereof is to provide a piezoelectric vibrator that can regulate the frequency after the gettering, a method of manufacturing the same, an oscillator, electronic equipment and a radio-controlled timepiece.
The Inventors of the invention obtained the following technology by testing. When the gettering is performed in an area adjoining a front end portion of the vibration arm portion of the piezoelectric vibrating reed, products due to the gettering is mainly attached to the front end portion of the vibration arm portion. In this case, since a weight (corresponding to a mass of a spring-mass system) of the front end portion increases, the frequency of the piezoelectric vibrating reed declines. On the other hand, when the gettering is performed in an area adjoining the proximal end portion of the vibration arm portion, the products are mainly attached to the proximal end portion of the vibration arm portion. In this case, an increase in rigidity (corresponding to a spring factor of a spring-mass system) of the proximal end portion is dominant, and the frequency of the piezoelectric vibrating reed increases.
Thus, the invention provides the following means:
According to the invention, there is provided a method of manufacturing a piezoelectric vibrator, the piezoelectric vibrator including a tuning fork type piezoelectric vibrating reed that includes a pair of vibration arm portions, a package that accommodates the piezoelectric vibrating reed, and a pair of regulation films that is formed along a longitudinal direction of the vibration arm portions corresponding to the pair of vibration arm portions, the piezoelectric vibrator being capable of improving a degree of vacuum in the package by irradiating the regulation films with a laser to evaporate a part of the regulation films, the method including a frequency measurement process of measuring the frequency of the piezoelectric vibrating reed, and a gettering process of evaporating a part of a regulation film of a position corresponding to a front end side of the vibration arm portion when the measured frequency is higher than a permissible range and evaporating a part of the regulation film of a position of a proximal portion side of the vibration arm portion when the measured frequency is lower than the permissible range.
With the method of manufacturing the piezoelectric vibrator according to the invention, by evaporating a part of the regulation film, a degree of vacuum in the package is regulated more to than a certain level, and the frequency can be regulated within the permissible range using the regulation film. Herein, the certain level refers to a state in which a series resonance resistance value is not greatly changed even when the degree of vacuum is improved more than that level. As a result, a suitable series resonance resistance value can be secured. Furthermore, the permissible range of the frequency is a nominal frequency of the piezoelectric vibrator for securing the quality.
A method of removing a part of the regulation film to regulating the frequency will be described. Firstly, the regulation film is formed in a state of adjoining near the vibration arm portion when seen from the plane. Thus, when the regulation film is irradiated with a laser and is evaporated, the regulation film is locally deposited to the side surface of the vibration arm portion situated near the irradiation position. At this time, if the deposition position of the regulation film is the proximal end side of the vibration arm portion, the frequency tends to increase, and if the deposition position is the front end side, the frequency tends to decline. Thus, by changing the laser irradiation position of the regulation film, the frequency of the piezoelectric vibrating reed can increase or decrease. Accordingly, the actually measured frequency is compared to the permissible range, the laser irradiation position of the regulation film is determined, and by locally depositing the evaporated regulation film to the side surface of the vibration arm portion, the vibration property of the vibrating arm portion can be changed. Accordingly, it is possible to regulate the frequency of the piezoelectric vibrating reed within the permissible range simultaneously with the gettering.
Furthermore, a pair of regulation films, which are formed along a longitudinal direction of the vibration arm portions corresponding to each of the pair of vibration arm portions, is included, when evaporating a part of the regulation film, the laser is irradiated to symmetrical positions via a center axis of the pair of vibration arm portions in the pair of regulation films to evaporate a part of the regulation film.
With this configuration, the pair of regulation films is formed in a state of adjoining near (outside) the pair of vibration arm portions when seen from plane. Thus, when the regulation film is irradiated with a laser and is evaporated, the regulation film is locally deposited on the side surface of the vibration arm portion situated near the irradiation position. Furthermore, by irradiating the laser to symmetrical positions via the center axis of the pair of vibration arm portions in the pair of regulation film, the regulation film deposited on the side surface of the pair of vibration arm portions can be made approximately uniform. Thus, a stable vibration property can be obtained even after the gettering process, and the vibration leakage can be reduced. As a consequence, the throughput can be improved.
Furthermore, the piezoelectric vibrator according to the invention is manufactured by the above-mentioned manufacturing method.
By this configuration, at the time of the gettering process, the degree of vacuum in the package can be regulated to more than a certain level, and it is possible to obtain a piezoelectric vibration in which the frequency is regulated within a permissible range using the regulation film. That is, it is possible to provide high quality piezoelectric vibrator in which the frequency is reliably regulated within the permissible range. Furthermore, the throughput can be improved.
Moreover, an oscillator according to the invention is configured so that the piezoelectric vibrator is electrically connected to an integrated circuit as an oscillator.
Furthermore, an electronic equipment according to the invention is configured so that the piezoelectric vibrator is electrically connected to a measurement portion.
Furthermore, a radio-controlled timepiece according to the invention is configured so that the piezoelectric vibrator is electrically connected to a filter portion.
In the oscillator, electronic equipment, and the radio-controlled timepiece according to the invention, since they include the piezoelectric vibrator capable of regulating the frequency after the gettering, the throughputs of the oscillator, the electronic equipment, and the radio-controlled timepiece can be improved to reduce costs, thus it is possible to obtain a high quality oscillator, electronic equipment and radio-controlled timepiece.
With the method of producing the piezoelectric vibrator according to the invention, the actually measured frequency is compared to the permissible range, the laser irradiation position of the regulation film is determined, and by locally depositing the evaporated regulation film to the side surface of the vibration arm portion, the vibration property of the vibration arm portion can be changed. Accordingly, it is possible to regulate the frequency of the piezoelectric vibrating reed within the permissible range simultaneously with the gettering.
Hereinafter, an embodiment of a piezoelectric vibrator according to the invention will be explained with reference to
As shown in
As shown in
The excitation electrode 15 including the first excitation electrode 13 and the second excitation electrode 14 are electrodes that vibrate the pair of vibration arm portions 10 and 11 in a direction approaching and retracting from each other by a predetermined resonant frequency, and are patterned and formed on the outer surfaces of the pair of vibration arm portions 10 and 11 in a state of being electrically separated, respectively. Specifically, as shown in
Furthermore, as shown in
Furthermore, on the front ends of the pair of vibration arm portions 10 and 11, a weight metal film 21 for adjusting (frequency adjustment) its own vibration state so as to be vibrated within a range of a predetermined frequency is coated. In addition, the weight metal film 21 is divided into a rough regulation film 21a used when roughly regulating the frequency and a minute regulation film 21b used when minutely regulating the frequency. By performing the frequency regulation using the rough regulation film 21a and the minute regulation film 21b, it is possible to limit the frequencies of the pair of vibration arm portions 10 and 11 within the range of a nominal frequency of a device.
As shown in
The lid substrate 3 is a transparent insulation substrate formed of a glass material, for example, soda lime glass, and, as shown in
The base substrate 2 is a transparent insulation substrate formed of the same glass material as the lid substrate 3, for example, soda lime glass, and, as shown in
On the upper surface side (a bonding surface side to which the lid substrate 3 is bonded) of the base substrate 2, as shown in
The getter material 34 is formed of aluminum or the like so as to extend from the proximal end side to the front end side along the longitudinal direction of the vibration arm portions 10 and 11 in the state of adjoining near the pair of vibration arm portions 10 and 11 when seen from the plane. Specifically, as shown in
Furthermore, the bonding film 35 is formed along the periphery of the base substrate 2 so as to surround the periphery of the concave portion 3a formed in the lid substrate 3.
Furthermore, the pair of drag electrodes 36 and 37 is patterned so as to electrically connect the one through electrode 32 of the pair of through electrodes 32 and 33 with one mount electrode 16 of the piezoelectric vibrating reed 4, and so as to electrically connect the other through electrode 33 with the other mount electrode 17 of the piezoelectric vibrating reed 4. To explain in more detail, one drag electrode 36 is formed immediately over one through electrode 32 so as to be situated immediately under the base portion 12 of the piezoelectric vibrating reed 4. In addition, the other drag electrode 37 is formed so as to be dragged from a position adjacent to one drag electrode 36 to the front end side along the vibration arm portions 10 and 11, and then be situated immediately over the other through electrode 33.
Moreover, the bumps B are formed on the pair of drag electrodes 36 and 37, respectively, and the piezoelectric vibrating reed 4 is mounted using the bump B. As a result, one mount electrode 16 of the piezoelectric vibrating reed 4 is electrically connected to one through electrode 32 via one drag electrode 36, and the other mount electrode 17 is electrically connected to the other through electrode 33 via the other drag electrode 37.
Moreover, as shown in
In the case of operating the piezoelectric vibrator 1 configured as above, a predetermined driving voltage is applied to the external electrodes 38 and 39 formed on the base substrate 2. As a result, it is possible to make the electric current flow to the excitation electrode 15 including the first excitation electrode 13 and the second excitation electrode 14 of the piezoelectric vibrating reed 4, which makes it possible to vibrate the pair of vibration arm portions 10 and 11 in the approaching and separating direction by a predetermined frequency. Moreover, it is possible to use the vibration of the pair of vibration arm portions 10 and 11 as a time source, a timing source of the control signal, a reference signal source or the like.
Next, a method of manufacturing a plurality of above-mentioned piezoelectric vibrators 1 using a base substrate wafer (base substrate) 40 and a lid substrate wafer (lid substrate) 50 at a time will be explained with reference to the flow chart shown in
Firstly, a piezoelectric vibrating reed production process is performed to produce the piezoelectric vibrating reed 4 shown in
Furthermore, after producing the piezoelectric vibrating reed 4, the rough regulation of the resonance frequency is performed. This is performed by irradiating the rough regulation film 21a of the weight metal film 21 with laser beam to evaporate a part thereof and changing the weight thereof. In addition, the minute regulation which further accurately regulates the resonance frequency is performed after the mount. This will be described later.
Next, a first wafer producing process, in which the lid substrate wafer 50 becoming the lid substrate 3 later is produced up to a state immediately before performing an anode-bonding, is performed (S20). Firstly, after the soda lime glass is polished up to a predetermined thickness and is cleaned, a circular plate shaped lid substrate mount 50, in which the deformed layer of the uppermost surface is removed by the etching or the like, is formed (S21). Next, as shown in
Next, at the timing simultaneously with or immediately before and after the process, a second wafer producing process, in which the base substrate wafer 40 becoming the base substrate 2 later is produced until the state immediately before performing an anode-bonding, is performed (S30). Firstly, after the soda lime glass is polished up to a predetermined thickness and is cleaned, a circular plate-shaped base substrate wafer 40, in which a deformed layer of the uppermost surface is removed by etching or the like, is formed (S31).
Next, a through electrode forming process, in which a plurality of pairs of through electrodes 32 and 33 is formed on the base substrate wafer 40, is performed (S32). Specifically, firstly, a plurality of pair of through holes 30 and 31 is formed by sand blasting or press working. Moreover, the pair of through electrodes 32 and 33 is formed in the plurality of pair of through holes 30 and 31. By the pair of through electrodes 32 and 33, the pair of through holes 30 and 31 is sealed and the electric conductivity between the upper surface side and the lower surface side of the base substrate wafer 40 is secured.
Next, a regulation film forming process, in which aluminum or the like is patterned on the upper surface of the base substrate wafer 40 to form the getter material 34 in the base substrate wafer 40, is performed (S33). At this time, the getter material 34 extends from the proximal end side to the front end side along the longitudinal direction of the vibration arm portions 10 and 11 in the state of adjoining near the pair of vibration arm portions 10 and 11 when seen from the plane, and is formed in the outer surface sides of the pair of vibration arm portions 10 and 11 and in positions symmetrical via the center axis L (see
Moreover, as shown in
In addition, in
Next, a bonding process, in which the base substrate wafer 40 and the lid substrate wafer 50 are bonded to each other, is performed (S40). To explain the bonding process in detail, firstly, a mount process, in which the plurality of produced piezoelectric vibrating reeds 4 is bonded to the upper surface of the base substrate wafer 40 via the drag electrodes 36 and 37, respectively, is performed (S41). Firstly, the bump B such as gold is formed on the pair of drag electrodes 36 and 37, respectively. Moreover, after the base portion 12 of the piezoelectric vibrating reed 4 is mounted on the bump B, the piezoelectric vibrating reed 4 is pressed to the bump B while heating the bump B at a predetermined temperature. As a result, the piezoelectric vibrating reed 4 is mechanically supported on the bump B, and the mount electrodes 16 and 17 and the drag electrodes 36 and 37 are electrically connected to each other. Thus, at this point in time, the pair of excitation electrodes 15 of the piezoelectric vibrating reed 4 is electrically connected to the pair of through electrodes 32 and 33, respectively. In addition, since the piezoelectric vibrating reed 4 is bump-bonded, it is supported in the state of floating from the upper surface of base substrate wafer 40.
After the mount of the piezoelectric vibrating reed 4 is finished, an overlapping process, in which the lid substrate wafer 50 is overlapped with the base substrate wafer 40, is performed (S42). Specifically, both wafer 40 and 50 are aligned in the correct position while setting a standard mark (not shown) as an index. As a result, mounted the piezoelectric vibrating reed 4 is accommodated within the cavity C which is surrounded by the concave portion 3a formed on the base substrate wafer 40 and both wafers 40 and 50.
After the overlapping process, two overlapped wafers 40 and 50 are put in an anode-bonding device (not shown) and a predetermined voltage is applied at a predetermined temperature environment to perform the anode-bonding (S43). Specifically, a predetermined voltage is applied between the bonding film 35 and the lid substrate wafer 50. Then, an electrochemical reaction occurs in an interface between the bonding film 35 and the lid substrate wafer 50, and both of them are strongly bonded to each other and are subjected to the anode-bonding. As a result, the piezoelectric vibrating reed 4 can be sealed within the cavity C, and it is possible to obtain a wafer body 60 shown in
Moreover, after the above-mentioned anode-bonding process is finished, an external electrode forming process, in which a conductive material is patterned on the lower surface of the base substrate wafer 40, and a plurality of pairs of external electrodes 38 and 39 electrically connected to the pair of through electrodes 32 and 33, respectively is formed, is performed (S50). By this process, it is possible to operate the piezoelectric vibrating reed 4 sealed in the cavity C using the external electrodes 38 and 39.
Next, a gettering process, in which the getter material 34 is irradiated with a laser light and is evaporated while vibrating the piezoelectric vibrating reed 4 sealed in the cavity C to measure the series resonance resistance value, thereby regulating the degree of vacuum in the cavity C over a fixed level, is performed (S60).
As shown in
Next, the frequency (a first frequency) of the piezoelectric vibrating reed 4 after removing a part of the getter material 34 is measured, and it is decided whether or not the first frequency is in a predetermined permissible range (S62). In a case where the first frequency is in the permissible range, the gettering process (S60) is finished. On the other hand, in a case where the first frequency is not in the permissible range, the process progresses to S63.
In a case where the first frequency is not in the permissible range, it is decided whether the first frequency is higher or lower than the permissible range (S63). When the first frequency is higher than the permissible range, the process progresses to S64, and when the first frequency is lower than the permissible range, the process progresses to S65.
In S64, in order to reduce the frequency of the piezoelectric vibrating reed 4, laser beam is irradiated to a position corresponding to the front end portions (F portion of
In S65, in order to raise the frequency of the piezoelectric vibrating reed 4, laser beam is irradiated to a position corresponding to the proximal end sides (G portion of
That is, as shown in
Next, the frequency (a second frequency) of the piezoelectric vibrating reed 4 after removing a part of the getter material 34 in S64 or S65 is measured, and it is determined whether or not the second frequency is within a predetermined permissible range (S66). When the second frequency is in the permissible range, the gettering process (S60) is finished. On the other hand, when the second frequency is not in the permissible range, the process returns to S63. Moreover, S63 to S66 are repeated until the frequency of the piezoelectric vibrating reed 4 is in the permissible range, after the frequency is in the permissible range, the gettering (S60) is finished.
In this manner, by performing the gettering process, the degree of vacuum in the cavity C can be secured more than a certain level, and the frequency can be put so as to be in the permissible range in advance. In addition, the degree of vacuum in the cavity C does not depend on the heating position of the getter material 34.
Moreover, in the present embodiment, when irradiating the getter material 34 with laser beam, in the pair of getter materials 34 and 34 formed so as to correspond to each of the pair of vibration arm portions 10 and 11, respectively, the positions symmetrical via the center axis L of the pair of vibration arm portions 10 and 11 are irradiated with laser beam. Specifically, when the getter material 34 is irradiated with laser beam, as shown in
Next, a minute regulation process, in which the minute regulation film 21b of the weight metal film 21 is heated by a laser or the like while continuously measuring the frequency and the regulated frequency of the piezoelectric vibrating reed 4 in the permission range is minutely regulated and is made closer to the object value, is performed (S70). As a result, the frequency of the piezoelectric vibrating reed 4 can be minutely regulated to enter a predetermined range of the nominal frequency. That is, in the gettering process, since the frequency of the piezoelectric vibrating reed 4 is regulated up to the approximation range (the permissible range) of the nominal frequency in advance, the minute regulation can easily be performed in a short time.
After the minute regulation of the frequency is finished, a cutting process, in which the bonded wafer body 60 is cut along the cutting lines M shown in
In addition, after the cutting process (S80) is performed to form the small pieces to the respective piezoelectric vibrators 1, the gettering process (S60) and the minute regulation process (S70) may be sequentially performed. However, as described above, by performing the gettering process (S60) and the minute regulation process (S70) in advance, the minute regulation can be performed in the state of the wafer body 60, which makes it possible to more effectively and minutely regulate the plurality of piezoelectric vibrators 1. Accordingly, it is desirable in that an improvement in throughput can be promoted.
After that, an internal electrical property inspection is performed (S90). That is, the resonant frequency, the resonant resistance value, the drive level property (an excitation electric power dependence of the resonant frequency and the resonant resistance value) or the like of the piezoelectric vibrating reed 4 are measured and checked. Furthermore, the insulation resistance property or the like is jointly checked. Moreover, the exterior inspection of the piezoelectric vibrator 1 is performed last, and the size, the quality or the like are finally checked. As a result, the manufacturing of the piezoelectric vibrator 1 is finished.
According to the present embodiment, by evaporating a part of the getter material 34, the degree of vacuum in the cavity C can be regulated to more than a certain level. Furthermore, after evaporating a part of the getter material 34, the frequency is measured, when the frequency is not in the permissible range, by heating a suitable place of the getter material 34 again depending on the value of the frequency, the frequency of the piezoelectric vibrating reed 4 can be regulated. That is, in the gettering process, the actually measured frequency is compared to the permissible range, the laser irradiation position of the getter material 34 is determined, and, by locally depositing the evaporated getter material 34 on the side surfaces 10a and 11a of the vibration arm portions 10 and 11, the frequency of the piezoelectric vibrating reed 4 can be within the permissible range. Thus, it is possible to regulate the frequency of the piezoelectric vibrating reed 4 within the permissible range simultaneously with the gettering.
Furthermore, when evaporating a part of the getter material 34, by irradiating a laser to symmetrical positions via the center line L of the pair of vibration arm portions 10 and 11 to evaporate a part of the getter material 34, it is possible to make the getter material 34 deposited on the side surfaces 10a and 11a of the pair of vibration arm portions 10 and 11 largely uniform. Thus, the stable vibration property is obtained even after the gettering process, and the vibration leakage can be reduced. As a consequence, the throughput can be improved.
Next, an embodiment of the oscillator according to the invention will be explained with reference to
As shown in
In the oscillator 100 configured as above, when the voltage is applied to the piezoelectric vibrator 1, the piezoelectric vibrating reed 4 in the piezoelectric vibrator 1 is vibrated. The vibration is converted to the electric signal by the piezoelectric property of the piezoelectric vibrating reed 4 and input in the integrated circuit 101 as the electric signal. The input electric signal is subjected to the respective processing by the integrated circuit 101 and is output as the frequency signal. As a result, the piezoelectric vibrator 1 functions as the oscillator.
Furthermore, in the configuration of the integrated circuit 101, by selectively setting an RTC (Real Time Clock) module or the like, for example, depending on the demand, the function of controlling the operating date or time of the equipment or external equipment, in addition to the timepiece single function oscillator or the like, or providing the time or the calendar or the like can be added.
As mentioned above, according to the oscillator 100 of the present embodiment, since it includes the piezoelectric vibrator 1 whose quality is improved by the minute regulation of the frequency with a high accuracy while reducing the accumulation of stress by heat, and which has a stable vibration characteristic due to the efficient gettering and minute regulation, the oscillator 100 itself also can promote high quality.
Next, an embodiment of the electronic equipment according to the invention will be explained with reference to
Next, the configuration of the portable information equipment 110 of the present embodiment will be explained. As shown in
The control portion 112 controls the respective functional portions to perform the motion control of the whole system such as the transmission and the reception of the sound data, or the measurement or the display of the current time. Furthermore, the control portion 112 includes a ROM with a program written thereon in advance, a CPU that reads and executes the program written on the ROM, and a RAM or the like used as a work area of the CPU.
The measurement portion 113 includes an integrated circuit, which is equipped with an oscillation circuit, a register circuit, a counter circuit, interface circuit or the like, and the piezoelectric vibrator 1. When the voltage is applied to the piezoelectric vibrator 1, the piezoelectric vibrating reed 4 is vibrated and the vibration is converted to the electric signal by the piezoelectric property of crystal, and is input to the oscillation circuit as the electric signal. The output of the oscillation circuit is binarized and is counted by the register circuit and the counter circuit. Moreover, the signal is transmitted to and received from the control portion 112 via the interface circuit, and the current time, the current date, the calendar information or the like is displayed on the display portion 115.
The communication portion 114 has the same function as the mobile phone of the related art, and includes a wireless portion 117, a sound processing portion 118, a switch-over portion 119, an amplification portion 120, a sound input and output portion 121, a phone number input portion 122, a receiving sound generation portion 123, and a call control memory portion 124.
The wireless portion 117 performs the exchange of the transmission and the reception of various data such as sound data with a base station via an antenna 125. The sound processing portion 118 encodes and decodes the sound signal input from the wireless portion 117 or the amplification portion 120. The amplification portion 120 amplifies the signal, which is input from the sound processing portion 118 or the input and output portion 121, to a predetermined level. The sound input and output portion 121 includes a speaker, a microphone or the like, amplifies the receiving sound or the receipt sound, or collect the sound.
Furthermore, the receiving sound generation portion 123 creates the receiving sound according to calls from the base station. The switch-over portion 119 switches the amplification portion 120 connected to the sound processing portion 118 to the receiving sound generation portion 123 only when receiving, whereby the receiving sound created in the receiving sound generation portion 123 is output to the sound input and output portion 121 via the amplification portion 120. In addition, the call control memory portion 124 stores the program relating to the departure and the arrival of the communication. Furthermore, the phone number input portion 122 includes, for example, number keys from 0 to 9 and other keys, and by pushing the number keys or the like, the phone number of the call destination or the like is input.
The voltage detection portion 116 detects the voltage drop and notifies it to the control portion 112 when the voltage added to the respective function portions such as the control portion 112 by the power source portion 111 is lower than a predetermined value. The predetermined voltage value of this time is a value which is preset as a minimum voltage necessary for stably operating the communication portion 114, and, for example, is about 3V. The control portion 112 receiving notification of a voltage drop from the voltage detection portion 116 prohibits the operation of the wireless portion 117, the sound processing portion 118, the switch-over portion 119 and the receiving sound generation portion 123. Particularly, stopping the operation of the wireless portion 117 having a high rate of electric power consumption is essential. Furthermore, the intent that the communication portion 114 becomes unusable due to the lack of the battery residual quantity is displayed on the display portion 115.
That is, the operation of the communication portion 114 can be prohibited by the voltage detection portion 116 and the control portion 112 and the intent can be displayed on the display portion 115. The display may be a text message, but as a more intuitive display, an X (cross) display may be made on a phone icon displayed on the upper portion of the display surface of the display portion 115. In addition, the power source shut-off portion 126 which can selectively shut off the power source of the portion relating to the function of the communication portion 114 is included, whereby the function of the communication portion 114 can further reliably be stopped.
As mentioned above, according to the portable information equipment 110 of the present embodiment, it is possible to obtain high quality electronic equipment 110 in which the throughput is improved and the cost can be reduced.
Next, an embodiment of a radio-controlled timepiece according to the invention will be explained with reference to
In Japan, transmitting stations for transmitting standard radio waves exist in Fukushima prefecture (40 KHz) and Saga prefecture (60 KHz), and each transmits the standard radio waves, respectively. Since long waves such as 40 KHz or 60 KHz have a property of spreading across the surface of the earth and a property of spreading while reflecting between the ionization layer and the ground of the earth, the spreading range is wide, and the above-mentioned two transmitting stations cover the whole of Japan.
Hereinafter, a functional configuration of the radio-controlled timepiece 130 will be explained in detail.
An antenna 132 receives the standard radio waves of the long waves at 40 KHz or 60 KHz. The standard radio waves of the long waves apply an AM modulation to the transport waves of 40 KHz or 60 KHz in a time information called a time code. The standard radio waves of the received long waves are amplified by an amp 133 and are filtered and tuned by a filter portion 131 having a plurality of piezoelectric vibrators 1. The piezoelectric vibrator 1 of the present embodiment includes crystal vibrator portions 138 and 139 having the same resonant frequencies of 40 KHz and 60 KHz as the transport frequency, respectively.
In addition, the signal of the filtered predetermined frequency is detected and demodulated by a detection and rectifier circuit 134. Next, the time code is taken out via a wave shaping circuit 135 and is counted by a CPU 136. In the CPU 136, information such as current year, accumulated date, day of the week, and time is read. The read information is reflected in an RTC 137 and the correct time information is displayed. Since the transport waves are 40 KHz or 60 KHz, a vibrator having the above-mentioned tuning fork type structure is suitable for the crystal vibrator portions 138 and 139.
In addition, the aforementioned explanation is shown by an example in Japan, but the frequencies of the standard radio waves of the long waves differ in foreign countries. For example, standard radio waves of 77.5 KHz are used in Germany. Thus, in a case where the radio-controlled timepiece 130 capable of coping in foreign countries is built in a mobile phone, there is a need for the piezoelectric vibrator 1 having a different frequency from the case in Japan.
As mentioned above, according to the radio-controlled timepiece 130 of the present embodiment, it is possible to obtain high quality radio-controlled timepiece 130 in which the throughput is improved and the cost can be reduced.
In addition, the technical scope of the invention is not limited to the above embodiments but various modifications can be added within a scope without departing from the gist of the invention.
For example, in the above-mentioned embodiment, the piezoelectric vibrator 1 is an SMD type piezoelectric vibrator 1 of a two layer structure type but it may be a piezoelectric vibrator of a three layer structure type. That is, a piezoelectric vibrator plate is mounted on the upper surface of the base substrate 2 using the piezoelectric vibrator plate having a frame shape portion surrounding the periphery of the piezoelectric vibrating reed 4, the base substrate 2 and the lid substrate 3 are bonded to each other via the piezoelectric vibrator plate, and the piezoelectric vibrating reed 4 is sealed in the cavity, thereby forming the piezoelectric vibrator.
Moreover, in the above-mentioned embodiment, the minute regulation film 21b is formed as the weight metal film 21 and the minute regulation film 21b is heated, thereby performing the minute regulation process, but it is not limited thereto. For example, the excitation electrode 15 may be formed on the front end sides of the pair of vibration arm portions 10 and 11 so as to extend up to near the minute regulation film 21a, and a part of the excitation electrode 15 is heated, thereby performing the minute regulation process. That is, in this case, a part of the excitation electrode 15 functions as the weight metal film 21.
Furthermore, in the above-mentioned embodiment, the case of forming the getter material 34 in the base substrate 2 is explained as an example, but the getter material 34 may be formed on any one substrate of the base substrate 2 and the lid substrate 3. That is, the getter material 34 may be formed on the lid substrate 3 and may be formed on both substrates 2 and 3.
Furthermore, in the above-mentioned embodiments, as an example of the piezoelectric vibrating reed 4, the piezoelectric vibrating reed 4 with the grooves in which the groove portions 18 are formed on both surfaces of the vibration arm portions 10 and 11 is described but it may be a type of piezoelectric vibrating reed without the groove portions 18. However, by forming the groove portions 18, when a predetermined voltage is applied to the pair of excitation electrodes 15, the electric field efficiency between the pair of excitation electrodes 15 can be improved, which can further suppress the vibration loss and further improve the vibration property. That is, the CI value (Crystal Impedance) can be further reduced and the high performance of the piezoelectric vibrating reed 4 can be further promoted. Given this point, it is desirable to form the groove portions 18.
Furthermore, in the above-mentioned embodiments, the pair of through electrodes 33 and 34 is formed, the invention is not limited thereto. However, in the case of manufacturing the piezoelectric vibrator 1 using the wafer, since the respective piezoelectric vibrating reeds 4 can be vibrated by the wafer shape by forming the through holes 33 and 34, the gettering process and the minute regulation process can be performed before forming the small pieces. Accordingly, it is desirable to form the through electrodes 33 and 34.
Moreover, in the above-mentioned embodiment, the piezoelectric vibrating reed 4 is bump-bonded, the invention is not limited to bump-bonding. For example, the piezoelectric vibrating reed 4 may be bonded by a conductive adhesive. However, the piezoelectric vibrating reed 4 can float from the upper surface of the base substrate 2 by the bump-bonding, whereby it is possible to naturally secure the minimum vibration gap that is necessary for the vibration. Thus, it is desirable to perform the bump-bonding.
Furthermore, in the above-mentioned embodiment, the description has been given of a case where, the base substrate wafer 40 is moved in the state of fixing the laser beam source device, thereby irradiating a desired position of the getter material 34 with laser beam. However, on the other hand, the base substrate wafer 40 may be fixed and the getter material 34 may be irradiated with laser beam while moving the laser beam source device.
In addition, in the present embodiment, the getter material is provided outside the pair of vibration arm portions when seen from the plane, but the getter material may be provided between the pair of vibration arm portions.
The method of manufacturing the piezoelectric vibrator according to the invention can be applied to a Surface Mount Device (SMD) type of piezoelectric vibrator in which the piezoelectric vibrating reed is sealed in the cavity formed between the two bonded substrates.
This application is a continuation of PCT/JP2008/065248 filed on Aug. 27, 2008. The entire contents of these applications are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2008/065248 | Aug 2008 | US |
| Child | 13035426 | US |
