JP2010213102A - Piezoelectric oscillator and ambient temperature measuring method for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric oscillator and an ambient temperature measuring method for the same in which a change in temperature around the piezoelectric oscillator can be measured without using a tub-outside temperature sensor. <P>SOLUTION: A piezoelectric oscillator includes: an oscillation part 18 including a piezoelectric vibrator 1 and an oscillation circuit 18a; a heater 2 for heating the piezoelectric vibrator 1; and a temperature control part 5 for temperature-controlling the heater 2. A temperature of the piezoelectric vibrator 1 is measured by a temperature sensor 3 and on the basis of the measured temperature of the piezoelectric vibrator 1, a calorific value of the heater 2 is controlled by the temperature control part 5. If a temperature around a piezoelectric oscillator 10 is changed, on the basis of a change in the power consumption of the heater 2 (preferably on the basis of a change in a voltage of the heater 2 or a change in a current of the heater 2), a change in temperature around the piezoelectric oscillator 10 is measured. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a temperature-compensated piezoelectric oscillator and a method for measuring the ambient temperature of the piezoelectric oscillator.

  In general, when a piezoelectric oscillator is used in an environment where the temperature changes drastically, it is very difficult to oscillate the piezoelectric oscillator at a stable frequency by compensating for temperature characteristics.

  Thus, there is a piezoelectric oscillator that oscillates at a stable frequency by disposing a piezoelectric vibrator constituting a part of the piezoelectric oscillator in a thermostatic chamber. As a conventional example of such a piezoelectric oscillator, there is a thermostatic chamber type piezoelectric oscillator disclosed in Japanese Patent No. 3272633 which is Patent Document 1 described later.

  FIG. 11 is a block diagram showing an example of a conventional piezoelectric oscillator.

  The piezoelectric oscillator shown in the figure is a so-called thermostatic chamber type piezoelectric oscillator in which a piezoelectric vibrator 101, a heating element 102, and a temperature sensor 103 in a chamber are arranged in a thermostatic chamber 104.

  This piezoelectric oscillator is configured to measure the temperature of the piezoelectric vibrator 101 with the temperature sensor 103 in the tank. The signal indicating the temperature measured by the in-tank temperature sensor 103 is replaced with a current signal for controlling the heating element 102 by the temperature control unit 105 connected between the heating element 102 and the in-tank temperature sensor 103. The drive current of the heating element 102 is adjusted by the current signal. As a result, the amount of heat generated by the heating element 102 changes, the temperature of the piezoelectric vibrator 101 is adjusted to a preset value, and the piezoelectric oscillator oscillates at a stable frequency.

  Another example of the conventional piezoelectric oscillator is a piezoelectric oscillator shown in FIG.

  FIG. 12 is a block diagram showing another example of a conventional piezoelectric oscillator.

  In the piezoelectric oscillator shown in the figure, the piezoelectric vibrator 201 is arranged in the thermostatic chamber 204 together with the heating element 202 and the temperature sensor 203 in the tank, like the piezoelectric oscillator shown in FIG. The temperature is configured to be measured by the in-tank temperature sensor 203, and is called a so-called thermostat type piezoelectric oscillator.

  Furthermore, the piezoelectric oscillator 201 includes a temperature control unit 205 that controls the driving current of the heating element 202, a temperature sensor 206 outside the bath that measures the temperature outside the bath 204, and a temperature sensor 206 outside the bath 204. And a control voltage generation circuit 207 that controls a voltage applied to the piezoelectric vibrator 201 in accordance with the measured temperature.

  In the temperature control unit 205, a signal indicating a difference between the temperature measured by the outside temperature sensor 206 and the temperature measured by the inside temperature sensor 203 is replaced with a current signal for controlling the heating element 202. And the drive current of the heat generating body 202 is adjusted with this current signal. As a result, the amount of heat generated by the heating element 202 changes, the temperature of the piezoelectric oscillator is adjusted to a preset value, and the piezoelectric oscillator oscillates at a stable frequency.

Japanese Patent No. 3272633

  However, in the piezoelectric oscillator shown in FIG. 11, since the temperature of the piezoelectric vibrator 101 is managed by the temperature sensor 103 in the tank, the temperature outside the thermostat 104 is adjusted so as not to be affected by the temperature change outside the thermostat 104. On the other hand, the temperature inside the thermostat 104 was set to be high. As a result, a very large current is required to keep the temperature inside the thermostatic chamber 104 constant, and the piezoelectric oscillator shown in FIG. 11 has a problem that it is difficult to reduce the power consumed by the piezoelectric oscillator itself. there were.

  On the other hand, in the piezoelectric oscillator shown in FIG. 12, for example, when the piezoelectric oscillator is used adjacent to an element (not shown) that emits heat, the outside temperature sensor 206 is disposed near the element that emits heat. If this is the case, the outside temperature sensor 206 will not be able to measure the temperature correctly due to the influence of the heat released by the element. As a result, in the piezoelectric oscillator shown in FIG. 12, the voltage applied to the piezoelectric vibrator 201 cannot be controlled to an appropriate value by the control voltage generation circuit 207, and the piezoelectric oscillator cannot oscillate at a stable frequency. was there.

  The present invention was devised to solve such problems, and an object of the present invention is to provide a piezoelectric oscillator capable of measuring a change in the temperature around the piezoelectric oscillator without using a temperature sensor outside the tank, and the piezoelectric oscillator. It is to provide an ambient temperature measurement method.

  In order to solve the above-described problems, a piezoelectric oscillator according to the present invention includes an oscillation unit including a piezoelectric vibrator and an oscillation circuit, a heater unit that warms the piezoelectric vibrator, and a temperature control unit that controls the temperature of the heater unit. And measuring a change in temperature around the piezoelectric oscillator based on a change in power consumption of the heater part (preferably, a change in voltage of the heater part or a change in current of the heater part). To do.

  Thereby, the change of the temperature around the piezoelectric oscillator can be measured without using the outside temperature sensor.

  In the above configuration, for example, it is preferable that a crystal resonator is provided as the piezoelectric vibrator, and a film resistor or a chip resistor is provided as the heater unit because the piezoelectric oscillator can be reduced in size. .

  Moreover, the said structure WHEREIN: You may further provide the frequency control circuit which controls the frequency of the said piezoelectric vibrator based on the change of the temperature around the said piezoelectric oscillator.

  In this case, since the output of the piezoelectric vibrator is not affected by a change in temperature around the piezoelectric oscillator, the piezoelectric oscillator oscillates at a more stable frequency. Further, when a varicap diode is used for frequency control, the voltage can be used as an input signal, so that the power consumption of the heater can be detected by the terminal voltage, and the circuit configuration can be further simplified.

  Moreover, the said structure WHEREIN: The thermostat may be further provided and the said piezoelectric vibrator and the said heater part may be arrange | positioned inside the said thermostat.

  In this case, since the temperature of the piezoelectric vibrator can be kept more constant, the piezoelectric oscillator oscillates at a more stable frequency.

  In the above configuration, the apparatus further includes a temperature sensor for measuring the temperature of the piezoelectric vibrator, and the temperature sensor is disposed inside the thermostat, and the heater unit is based on the measurement result of the temperature sensor. It is also possible to control the operation.

  In this case, since the temperature of the piezoelectric vibrator can be kept more constant, the piezoelectric oscillator oscillates at a more stable frequency.

  The method for measuring the ambient temperature of a piezoelectric oscillator according to the present invention includes: an oscillation unit that includes a piezoelectric vibrator and an oscillation circuit; a heater unit that warms the piezoelectric vibrator; and a temperature control unit that controls the temperature of the heater unit. A procedure for measuring the temperature of the piezoelectric vibrator with the temperature sensor, a procedure for controlling the operation of the heater unit based on a measurement result of the temperature sensor, and power consumption of the heater unit And a procedure for measuring a change in the temperature around the piezoelectric oscillator based on the change in.

  Thereby, the change of the temperature around the piezoelectric oscillator can be measured without using the outside temperature sensor.

  Further, in the above configuration, the piezoelectric oscillator further includes a frequency control circuit that controls a frequency of the piezoelectric vibrator based on a change in temperature around the piezoelectric oscillator, and a change in temperature around the piezoelectric oscillator. Further, a procedure for controlling the frequency of the piezoelectric vibrator by the frequency control circuit may be included.

  In this case, since the output of the piezoelectric vibrator is not affected by a change in temperature around the piezoelectric oscillator, the piezoelectric oscillator oscillates at a more stable frequency.

  Since this invention was comprised as mentioned above, the change of the temperature around a piezoelectric oscillator can be measured, without using a temperature sensor outside a tank.

It is a block diagram which shows one Embodiment of the piezoelectric oscillator of this invention. It is a graph which shows the relationship between the power consumption of a heater part, and ambient temperature. It is sectional drawing which shows an example of a structure of the piezoelectric oscillator shown in FIG. FIG. 2 is a circuit diagram showing an electrical configuration example 1 of the piezoelectric oscillator shown in FIG. 1. It is a graph which shows the relationship between the voltage of a heater part, and ambient temperature. It is a graph which shows an example of the frequency temperature characteristic of the piezoelectric oscillator shown in FIG. FIG. 3 is a circuit diagram showing an electrical configuration example 2 of the piezoelectric oscillator shown in FIG. 1. FIG. 4 is a circuit diagram showing an electrical configuration example 3 of the piezoelectric oscillator shown in FIG. 1. FIG. 6 is a circuit diagram showing an electrical configuration example 4 of the piezoelectric oscillator shown in FIG. 1. It is a graph which shows the relationship between the electric current of a heater part, and ambient temperature. It is a block diagram which shows an example of the conventional piezoelectric oscillator. It is a block diagram which shows the other example of the conventional piezoelectric oscillator.

  Hereinafter, embodiments of a piezoelectric oscillator and a method for measuring the ambient temperature of the piezoelectric oscillator according to the present invention will be described.

  First, an embodiment of a piezoelectric oscillator of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing an embodiment of the piezoelectric oscillator of the present invention.

  The piezoelectric oscillator 10 is a so-called thermostatic chamber type piezoelectric oscillator including the thermostatic chamber 4. In the piezoelectric oscillator 10 shown in FIG. 1, the piezoelectric vibrator 1, the heater part 2, the temperature sensor 3, and the oscillation circuit 18a are arrange | positioned inside the thermostat 4. As shown in FIG. The oscillation circuit 18a may be arranged inside the thermostat 4 (see FIG. 1) or arranged outside the thermostat 4 (not shown), but the temperature difference with the piezoelectric vibrator 1 is small. More preferably, it is arranged inside the thermostatic chamber 4.

  As the piezoelectric vibrator 1, for example, a crystal vibrator is used. The piezoelectric vibrator 1 is vibrated by the voltage applied by the oscillation circuit 18a. The temperature sensor 3 is arranged near the piezoelectric vibrator 1 and measures the temperature of the piezoelectric vibrator 1 by measuring the temperature near the piezoelectric vibrator 1. The heater unit 2 releases heat to warm the piezoelectric vibrator 1 according to the temperature measurement result by the temperature sensor 3. The thermostat 4 is provided to keep the piezoelectric vibrator 1 at a more constant temperature.

  Furthermore, the piezoelectric oscillator 10 of the present embodiment includes a temperature control unit 5 connected between the temperature sensor 3 and the heater unit 2, and a frequency control circuit 6 disposed outside the thermostat 4.

  The temperature control unit 5 controls the operation of the heater unit 2 based on the measurement result of the temperature sensor 3. In addition, the frequency control circuit 6 measures a change in ambient temperature, which will be described later, based on a change in power consumption of the heater unit 2, and controls a voltage applied to the piezoelectric vibrator 1 based on the measurement result. 1 frequency is controlled.

  In the present embodiment, the piezoelectric vibrator 1, the oscillation circuit 18a, and the frequency control circuit 6 serve as the oscillation unit 18, and the periphery of the piezoelectric oscillator 10 schematically shown by a two-dot chain line in FIG. The temperature around the product body is the “ambient temperature”. For example, when the piezoelectric oscillator 10 is used in a state adjacent to an element that emits heat (or an element for cooling such as a Peltier element), the ambient temperature is affected by a temperature change of the element.

  Here, the relationship between the power consumption of the heater part 2 and ambient temperature is demonstrated, referring FIG. FIG. 2 is a graph showing the relationship between the power consumption of the heater unit 2 and the ambient temperature, where the vertical axis represents power consumption (W) and the horizontal axis represents ambient temperature (° C.). However, the temperature of the piezoelectric vibrator 1 measured by the temperature sensor 3 is controlled to be substantially constant.

  As indicated by L1 in FIG. 2, when the ambient temperature rises in a range of about −40 degrees to about 80 degrees, the power consumption of the heater unit 2 decreases, and the power consumption of the heater unit 2 is less than the ambient temperature. It is a linear function. In other words, the power consumption of the heater unit 2 changes according to the sum of the influences of changes in the ambient temperature received by all the members thermally connected to the heater unit 2.

  Next, an embodiment of a method for measuring the ambient temperature of a piezoelectric oscillator according to the present invention will be described with reference to FIG.

  In a state where the ambient temperature has not changed, first, the temperature near the piezoelectric vibrator 1 is measured by the temperature sensor 3. Subsequently, the temperature control unit 5 obtains a difference between the temperature measured by the temperature sensor 3 and a preset temperature, and controls the amount of heat generated by the heater unit 2 according to the obtained magnitude of the difference. By such control, the temperature of the piezoelectric vibrator 1 becomes a constant temperature, and the piezoelectric vibrator 1 oscillates at a stable frequency according to the voltage applied by the oscillation circuit 18a.

  Further, when the ambient temperature changes, the power consumption of the heater unit 2 changes as shown in FIG. 2 even though the control by the temperature control unit 5 is performed. For example, when the ambient temperature increases, the power consumption of the heater unit 2 decreases and the heat generation amount decreases, and when the ambient temperature decreases, the power consumption of the heater unit 2 increases and the heat generation amount increases.

  In the present embodiment, the change in the ambient temperature is measured by the frequency control circuit 6 based on such a change in the power consumption of the heater unit 2. Further, the frequency control circuit 6 controls the frequency of the piezoelectric vibrator 1 based on the result of measuring the change in ambient temperature. For example, in the frequency control circuit 6, when the frequency of the piezoelectric vibrator 1 is low due to a change in power consumption of the heater unit 2, adjustment is performed so that the frequency becomes high. In addition, when the frequency of the piezoelectric vibrator 1 is high due to the change in the power consumption of the heater unit 2, the frequency is adjusted to be low. A specific example of the means for performing the adjustment will be described in detail later with reference to FIGS. 4 and 7 to 9.

  In the piezoelectric oscillator 10 of this embodiment, the change in the ambient temperature is measured based on the change in the power consumption of the heater unit 2. Therefore, the outside tank temperature sensor 206 used in the conventional piezoelectric oscillator shown in FIG. 12 can be omitted. As a result, the piezoelectric oscillator 10 can be downsized and manufactured at low cost.

  Further, as described above, the conventional piezoelectric oscillator shown in FIG. 12 may not be able to measure the temperature correctly depending on the location of the outside temperature sensor 206. However, in the piezoelectric oscillator 10 of the present embodiment, based on the change in the power consumption of the heater unit 2, which is the sum of the effects of changes in the ambient temperature received by all the members thermally connected to the heater unit 2. Measuring changes in ambient temperature. Therefore, the change in ambient temperature can be measured correctly.

  Further, in the piezoelectric oscillator 10 of the present embodiment, the frequency of the piezoelectric vibrator 1 is controlled by the frequency control circuit 6 based on the measured change in ambient temperature. As a result, the piezoelectric oscillator 10 can be oscillated at a stable frequency even when the ambient temperature changes.

[Configuration example of piezoelectric oscillator]
Next, an example of the configuration of the piezoelectric oscillator shown in FIG. 1 will be described with reference to FIG. FIG. 3 is a cross-sectional view showing an example of the configuration shown in FIG. In FIG. 3, a crystal oscillator using a crystal resonator as a piezoelectric resonator is taken as an example, and a configuration example when the present invention is applied to this crystal oscillator is shown. 1 and 3 indicate the same parts, and the description of the same parts is omitted.

  As shown in FIG. 3, the crystal oscillator includes two substrates (for example, a main substrate 12) disposed in a body housing 11 composed of a metal base 11a and a body lid 11b so as to face each other. In addition, an oscillation circuit (OSC (oscillator)) substrate 13) is arranged. In the present specification, of the surfaces of the main substrate 12 and the oscillation circuit substrate 13, the surfaces facing each other are defined as one main surface 12a, 13a, and the surfaces that are paired with the one main surface 12a, 13a are the other main surfaces. 12b and 13b. In this specification, a region sandwiched between the main substrate 12 and the oscillation circuit substrate 13 is defined as the inside of the thermostatic chamber 4.

  The crystal oscillator shown in FIG. 3 includes a crystal resonator 14 as a piezoelectric resonator. The crystal unit 14 is loaded in an aluminum block 15 disposed in the thermostatic chamber 4. The aluminum block 15 covers the surface of the crystal unit 14, conducts heat released from the heater unit 2 to the entire crystal unit 14, and sets the temperature of the crystal unit 14 to a constant temperature (for example, about 80 Degree). The aluminum block 15 is joined to the one principal surface 12 a of the main substrate 12 and the one principal surface 13 a of the oscillation circuit substrate 13 by the joint portion 16. In other words, the crystal oscillator has a structure in which the joint portion 16, the aluminum block 15, the joint portion 16, and the main substrate 12 are sequentially laminated on the oscillation circuit substrate 13. Although not shown, the arrangement of the main board 12 and the oscillation circuit board 13 may be interchanged. The joint 16 is formed, for example, by filling and curing a heat conductive resin between the main board 12 and the oscillation circuit board 13, and the heat conductive resin has a high heat conductivity. Silicone resin or epoxy resin having high thermal conductivity can be used.

  Further, although not shown in detail, the crystal resonator 14 includes a crystal resonator element disposed on the resonator base, and the crystal resonator element is hermetically sealed by the resonator base and the resonator lid. It has become. In addition, an excitation electrode and an extraction electrode extracted from the excitation electrode are formed on the crystal vibrating piece, and the extraction electrode is connected to at least a pair of lead terminals 17 shown in FIG. Note that the crystal unit 14 may include only one pair of lead terminals 17 or a plurality of pairs. Although not shown, the crystal resonator 14 configured in this way is provided, for example, on an oscillation circuit 18a (see FIG. 1) provided on one main surface 13a of the oscillation circuit board 13 and on the other main surface 13b of the oscillation circuit board 13. The frequency control circuit 6 is electrically connected by a lead terminal 17.

  As shown in FIG. 3, the heater portion 2 is disposed on one main surface 12 a of the main substrate 12. A temperature control unit 5 that controls the temperature of the aluminum block 15 is disposed on the other main surface 12 b of the main substrate 12.

  Note that the transistor 2b constituting a part of the temperature control unit 5 is also used as the heater unit 2 to release heat in the same manner as the resistor 2a, and also constitutes a part of the heater unit 2.

  Further, a through hole 15a is formed in the aluminum block 15, and the temperature sensor 3 is disposed inside the through hole 15a. A joint 16 is disposed in the gap between the temperature sensor 3 and the through hole 15a. The temperature sensor 3 is formed of, for example, a thermistor, is disposed near the crystal unit 14, and is connected to the heater unit 2 via the temperature control unit 5.

  The heater unit 2 includes a resistor 2a and a transistor 2b. For example, the resistor 2a may be a film resistor such as a pressure film printing resistor or a chip resistor. In this case, the crystal oscillator can be further downsized. The transistor 2b is preferably a transistor having a sufficiently high rated value in consideration of safety, for example, a power transistor.

  In addition, a wiring pattern (not shown) is printed on one main surface 12a of the main substrate 12, and the heater portion 2 is connected to the wiring of the main substrate 12 via a lead terminal (not shown) of the transistor 2b. It is electrically connected to the pattern.

[Electrical configuration example 1 of piezoelectric oscillator]
Next, an electrical configuration example 1 of the piezoelectric oscillator shown in FIG. 1 will be described with reference to FIG. 4 is a circuit diagram showing an electrical configuration example 1 of the piezoelectric oscillator 10 shown in FIG. 1, 3, and 4, the same reference numerals indicate the same parts, and the description of the same parts is omitted.

  In the piezoelectric oscillator shown in FIG. 4, the frequency control circuit 6a measures the change in the ambient temperature based on the change in the voltage of the heater unit 2 composed of the resistor 2a and the transistor 2b. The frequency of the vibrator 42 is controlled.

  As shown in FIG. 4, the frequency control circuit 6a constitutes the oscillation unit 18 together with the oscillation circuit 18a and the piezoelectric vibrator 42. Further, the frequency control circuit 6a includes resistors 41, 44, and 45 and a varicap diode 43, and the temperature controller 5 includes an operational amplifier 47 that includes integrated circuit elements, and resistors 48, 49, 50, 51 and a transistor 2b constituting a part of the heater section 2.

  The electrical configuration of the piezoelectric oscillator shown in FIG. 4 will be described in more detail. A connection point a between one terminal of the resistor 2a connected in series and the collector terminal of the transistor 2b is connected in series via the resistor 41. The piezoelectric vibrator 42 is connected to a connection point b between the one terminal of the piezoelectric vibrator 42 and the cathode terminal of the varicap diode 43.

  The other terminal of the resistor 2a is connected to the power supply voltage (Vcc), and the emitter terminal of the transistor 2b is grounded (GND). One terminal of the resistor 45 is connected to the connection point d between the resistor 41 and the connection point b, and the other terminal of the resistor 45 is grounded. Furthermore, one terminal of the resistor 44 is connected to the anode terminal of the varicap diode 43, and the other terminal of the resistor 44 is grounded.

  The other terminal of the piezoelectric vibrator 42 is connected to one terminal of the oscillation circuit 18a, and the other terminal of the oscillation circuit 18a is connected to the anode terminal of the varicap diode 43 and the resistor 44 via the capacitor 46. Is connected to the other terminal of the oscillation circuit 18a through a regulator 52.

  One terminal of the temperature sensor 3 is connected to the non-inverting input terminal of the operational amplifier 47. Further, one terminal of a resistor 48 is connected to a connection point e between the temperature sensor 3 and the operational amplifier 47, and the other terminal of the resistor 48 is connected to a power supply voltage via a regulator 52.

  The connection point f between the resistors 49 and 50 connected in series is connected to the inverting input terminal of the operational amplifier 47. The other terminal of the resistor 49 is connected to the power supply voltage via the regulator 52, and the other terminal of the resistor 50 is grounded. Furthermore, the output terminal of the operational amplifier 47 is connected to the base of the transistor 2 b via the resistor 51.

  Furthermore, the temperature sensor 3 is a temperature sensing element (for example, a thermistor) whose resistance value varies with temperature. In FIG. 4, the resistance value increases as the temperature decreases, and the resistance value decreases as the temperature increases. A temperature element is used.

  Here, the relationship between the voltage of the heater unit 2 and the ambient temperature will be described with reference to FIG. FIG. 5 is a graph showing the relationship between the voltage of the heater unit 2 and the ambient temperature. The vertical axis represents the heater terminal voltage Vc (V), which is the voltage of the heater unit 2, and the horizontal axis represents the ambient temperature (° C.). However, the temperature of the piezoelectric vibrator 42 measured by the temperature sensor 3 is controlled to be substantially constant.

  As indicated by L2 in FIG. 5, when the ambient temperature rises in the range of about −40 degrees to about 80 degrees, the heater terminal voltage increases, and the heater terminal voltage is a linear function with respect to the ambient temperature. . That is, the voltage of the heater unit 2 changes according to the sum of the influences of changes in the ambient temperature received by all the members thermally connected to the heater unit 2. Thereby, according to the piezoelectric oscillator shown in FIG. 4, it is possible to measure the change in the ambient temperature based on the change in the voltage of the heater unit 2.

  Next, an example of a method for measuring the ambient temperature of the piezoelectric oscillator using the piezoelectric oscillator shown in FIG. 4 will be described with reference to FIG.

  When the method for measuring the ambient temperature of the piezoelectric oscillator using the piezoelectric oscillator shown in FIG. 4 is performed, the resistance value of the temperature sensor 3 varies according to the temperature in the vicinity of the piezoelectric vibrator 42 in a state where the ambient temperature has not changed.

  For example, when the temperature in the vicinity of the piezoelectric vibrator 42 decreases, the resistance value of the temperature sensor 3 increases, the voltage between the terminals of the temperature sensor 3 increases, and the output voltage of the operational amplifier 47 increases. As a result, the output current of the operational amplifier 47 increases, the collector current of the transistor 2b increases, the current flowing through the resistor 2a increases, and the amount of heat generated by the resistor 2a increases. Therefore, when the temperature in the vicinity of the piezoelectric vibrator 42 decreases, the amount of heat generated by the resistor 2a increases and the piezoelectric vibrator 42 can be warmed more rapidly.

  For example, when the temperature near the piezoelectric vibrator 42 increases, the resistance value of the temperature sensor 3 decreases, the voltage between the terminals of the temperature sensor 3 decreases, and the output voltage of the operational amplifier 47 decreases. As a result, the output current of the operational amplifier 47 decreases, the collector current of the transistor 2b decreases, the current flowing through the resistor 2a decreases, and the amount of heat generated by the resistor 2a decreases. Thereby, when the temperature in the vicinity of the piezoelectric vibrator 42 increases, the amount of heat generated by the resistor 2a decreases, and the piezoelectric vibrator 42 can be warmed more gently.

  By performing such operations in the temperature sensor 3, the temperature control unit 5, and the heater unit 2, the temperature of the piezoelectric vibrator 42 becomes constant, and the piezoelectric vibrator 42 is applied by the oscillation circuit 18a. Oscillates at a stable frequency according to the voltage.

  Furthermore, in the piezoelectric oscillator shown in FIG. 4, the temperature of the piezoelectric vibrator 42 is controlled by the temperature sensor 3, the temperature control unit 5 and the heater unit 2, and when the ambient temperature changes, the frequency control circuit 6 a A change in the ambient temperature is measured based on a change in the voltage of the heater unit 2, and the frequency of the piezoelectric vibrator 42 is controlled based on the measurement result.

  Here, before explaining in detail the control of the frequency of the piezoelectric vibrator 42 by the frequency control circuit 6a, an example of the temperature characteristic of the piezoelectric oscillator shown in FIG. 4 will be described with reference to FIG. FIG. 6 is a graph showing an example of frequency temperature characteristics of the piezoelectric oscillator shown in FIG. 4, where the vertical axis represents frequency deviation (ppb) and the horizontal axis represents ambient temperature (° C.). FIG. 6 shows the temperature characteristic L3 of the piezoelectric oscillator shown in FIG. 4 and the temperature when the resistor 41 in FIG. A characteristic L100 is also shown.

  FIG. 6 shows frequency temperature characteristics when the reference temperature is 25 ° C. For this reason, in the piezoelectric oscillator shown in FIG. 4, the values of the resistors 41 and 45 are selected so that the variation of the frequency temperature characteristic is minimized within a predetermined temperature range set with respect to the reference temperature.

  When the resistor 41 is in the open state and control by the frequency control circuit 6a is not performed, the piezoelectric oscillator shown in FIG. 4 has an ambient temperature in a range of about −20 degrees to about 65 degrees as indicated by L100 in FIG. As the frequency becomes higher, the frequency deviation becomes smaller. When the ambient temperature is about 25 ° C., the frequency deviation becomes “0”.

  In the piezoelectric oscillator shown in FIG. 4, as shown in FIG. 5, for example, the voltage of the heater unit 2 increases when the ambient temperature increases, and the voltage of the heater unit 2 decreases when the ambient temperature decreases. The frequency control circuit 6a measures changes in the ambient temperature using such changes in the voltage of the heater unit 2 (connection point a). Further, the frequency control circuit 6a adjusts the capacitance of the varicap diode 43 by controlling the voltage of the heater unit 2 (connection point a) in order to control the frequency of the piezoelectric vibrator 42 in accordance with the measured change in ambient temperature. ing.

  For example, when the ambient temperature increases, the voltage of the heater unit 2 increases as shown in FIG. As a result, the voltage at the connection point b increases, the potential difference between the cathode terminal and the anode terminal of the varicap diode 43 increases, and the capacitance of the varicap diode 43 decreases, so the frequency of the piezoelectric vibrator 42 increases. . Further, for example, when the ambient temperature decreases, the voltage of the heater unit 2 decreases as shown in FIG. As a result, the voltage at the connection point b decreases, the potential difference between the cathode terminal and the anode terminal of the varicap diode 43 decreases, and the capacitance of the varicap diode 43 increases, so the frequency of the piezoelectric vibrator 42 decreases. .

  In the piezoelectric oscillator shown in FIG. 4, by performing such an operation in the frequency control circuit 6a, the capacitance of the varicap diode 43 is adjusted according to the change in the ambient temperature, and the frequency of the piezoelectric vibrator 42 is controlled, The frequency temperature characteristics of the piezoelectric oscillator are adjusted. Therefore, as indicated by L3 in FIG. 6, the frequency deviation can be made substantially constant as compared with the case where the resistor 41 is in the open state. That is, in the piezoelectric oscillator shown in FIG. 4, the output of the piezoelectric vibrator 42 can be adjusted in the direction in which the frequency increases as the temperature increases, that is, in the direction in which the curve of the frequency temperature characteristic rotates counterclockwise.

  Therefore, according to the piezoelectric oscillator shown in FIG. 4 and the ambient temperature measuring method of the piezoelectric oscillator using the piezoelectric oscillator, the outside temperature sensor 206 (see FIG. 12) can be omitted. As a result, the piezoelectric oscillator can be downsized and manufactured at low cost.

  Further, according to the piezoelectric oscillator shown in FIG. 4 and the ambient temperature measuring method of the piezoelectric oscillator using the piezoelectric oscillator, the sum of the influences of changes in the ambient temperature received by all the members thermally connected to the heater unit 2. Since the change in the ambient temperature is measured based on the change in the voltage of the heater unit 2, the change in the ambient temperature can be correctly measured.

  Further, according to the piezoelectric oscillator shown in FIG. 4 and the ambient temperature measuring method of the piezoelectric oscillator using the piezoelectric oscillator, the frequency of the piezoelectric vibrator 42 is controlled by the frequency control circuit 6a based on the measured change in the ambient temperature. Therefore, even when the ambient temperature changes, the piezoelectric oscillator can be oscillated at a stable frequency.

[Electrical configuration example 2 of piezoelectric oscillator]
Next, Example 2 of the electrical configuration of the piezoelectric oscillator 10 shown in FIG. 1 will be described with reference to FIG. FIG. 7 is a circuit diagram showing an electrical configuration example 2 of the piezoelectric oscillator 10 shown in FIG. 1, 3, 4, and 7, the same reference numerals indicate the same parts, and the description of the same parts is omitted.

  Although the temperature characteristics of the piezoelectric oscillator shown in FIG. 7 are not shown, it is assumed that the slope is reversed from that shown in FIG. 6 (that is, the frequency deviation increases as the ambient temperature increases).

  In the piezoelectric oscillator shown in FIG. 7, the frequency control circuit 6b measures the change in the ambient temperature based on the change in the voltage of the heater unit 2, and further controls the frequency of the piezoelectric vibrator 42 according to the measurement result.

  The piezoelectric oscillator shown in FIG. 7 differs from the piezoelectric oscillator shown in FIG. 4 in the configuration of the frequency control circuit 6b, and the other configurations are the same.

  As shown in FIG. 7, the frequency control circuit 6 b includes resistors 71, 72, 44 and a varicap diode 43. More specifically, in the piezoelectric oscillator shown in FIG. 7, the resistor 41 and the resistor 45 shown in FIG. 4 are omitted, and the resistor 71 is provided between the connection point a and the connection point c (the anode terminal of the varicap diode 43). One terminal of the resistor 72 is connected to the connection point b. Further, the other terminal of the resistor 72 is connected to the power supply voltage via the regulator 52.

  In the piezoelectric oscillator shown in FIG. 7, the values of the resistors 71 and 44 are selected so that the variation of the frequency temperature characteristic is minimized within a predetermined temperature range set with respect to the reference temperature.

  Next, an example of a method for measuring the ambient temperature of the piezoelectric oscillator using the piezoelectric oscillator shown in FIG. 7 will be described with reference to FIG.

  In the state where the ambient temperature has not changed, the temperature of the piezoelectric vibrator 42 is controlled by the temperature sensor 3, the temperature control unit 5 and the heater unit 2 in the same procedure as the piezoelectric oscillator shown in FIG. Description is omitted.

  In the piezoelectric oscillator shown in FIG. 7, the temperature of the piezoelectric vibrator 42 is controlled by the temperature sensor 3, the temperature control unit 5 and the heater unit 2, and when the ambient temperature changes, the frequency control circuit 6b causes the heater unit. The change in the ambient temperature is measured based on the change in voltage 2 and the frequency of the piezoelectric vibrator 42 is controlled according to the measurement result.

  For example, when the ambient temperature increases, the voltage of the heater unit 2 increases (see FIG. 5), so that the voltage at the connection point c increases and the potential difference between the cathode terminal and the anode terminal of the varicap diode 43 decreases. . Therefore, the capacity of the varicap diode 43 increases as the ambient temperature increases. Further, for example, when the ambient temperature is lowered, the voltage of the heater unit 2 is lowered (see FIG. 5), so that the voltage at the connection point c is lowered, and the potential difference between the cathode terminal and the anode terminal of the varicap diode 43 is reduced. The capacitance of the varicap diode 43 becomes smaller.

  In the piezoelectric oscillator shown in FIG. 7, by performing such an operation in the frequency control circuit 6b, the capacitance of the varicap diode 43 is adjusted according to the change in the ambient temperature, and the frequency of the piezoelectric vibrator 42 is controlled. The frequency temperature characteristics of the piezoelectric oscillator are adjusted. Therefore, the frequency deviation can be made substantially constant. That is, in the piezoelectric oscillator shown in FIG. 7, the output of the piezoelectric vibrator 42 can be adjusted in the direction in which the frequency decreases as the temperature increases, that is, in the direction in which the frequency-temperature characteristic curve rotates clockwise.

  Therefore, according to the piezoelectric oscillator shown in FIG. 7 and the ambient temperature measuring method of the piezoelectric oscillator using the piezoelectric oscillator, the outside temperature sensor 206 (see FIG. 12) can be omitted. As a result, the piezoelectric oscillator can be downsized and manufactured at low cost.

  Further, according to the piezoelectric oscillator shown in FIG. 7 and the ambient temperature measuring method of the piezoelectric oscillator using the piezoelectric oscillator, the sum of the influences of changes in the ambient temperature received by all the members thermally connected to the heater unit 2 is achieved. Since the change in the ambient temperature is measured based on the change in the voltage of the heater unit 2, the change in the ambient temperature can be correctly measured.

  Further, according to the piezoelectric oscillator shown in FIG. 7 and the ambient temperature measuring method of the piezoelectric oscillator using the piezoelectric oscillator, the frequency of the piezoelectric vibrator 42 is controlled by the frequency control circuit 6b based on the measured change in the ambient temperature. Therefore, even when the ambient temperature changes, the piezoelectric oscillator can be oscillated at a stable frequency.

[Electric Configuration Example 3 of Piezoelectric Oscillator]
Next, Example 3 of the electrical configuration of the piezoelectric oscillator 10 shown in FIG. 1 will be described with reference to FIG. FIG. 8 is a circuit diagram showing an electrical configuration example 3 of the piezoelectric oscillator 10 shown in FIG. 1, 3, 4, 7, and 8, the same reference numerals indicate the same parts, and the description of the same parts is omitted.

  In the piezoelectric oscillator shown in FIG. 8, the frequency control circuit 6c measures the change in the ambient temperature based on the change in the voltage of the heater unit 2, and further controls the frequency of the piezoelectric vibrator 42 according to the measurement result.

  The piezoelectric oscillator shown in FIG. 8 differs from the piezoelectric oscillator shown in FIGS. 4 and 7 in the configuration of the frequency control circuit 6c, and the other configurations are the same.

  In the piezoelectric oscillator shown in FIG. 8, the frequency control circuit 6a and the frequency control circuit 6b described above are provided in the frequency control circuit 6c at the time of manufacture. In use, one of the frequency control circuit 6a and the frequency control circuit 6b is set in an open state in accordance with the temperature characteristics (temperature characteristic slope) of the piezoelectric oscillator. The circuit of one part of is adopted.

  In the frequency control circuit 6c, as shown in FIG. 8, one terminal of the resistor 41 and one terminal of the resistor 71 are connected in parallel to the connection point a. The other terminal of the resistor 41 is connected to the connection point b similarly to the piezoelectric oscillator shown in FIG. 4, and the other terminal of the resistor 71 is connected to the connection point c like the piezoelectric oscillator shown in FIG. ing. Further, one terminal of the resistor 45 and one terminal of the resistor 72 are connected to a connection point d between the other terminal of the resistor 41 and the connection point b. The other terminal of the resistor 45 is grounded, and the other terminal of the resistor 72 is connected to the power supply voltage via the regulator 52.

  Since the piezoelectric oscillator shown in FIG. 8 has such a configuration, for example, the piezoelectric oscillator shown in FIG. 4 can be obtained by setting the resistor 71 and the resistor 72 to the open state. The piezoelectric oscillator shown in FIG. The method for measuring the ambient temperature of the piezoelectric oscillator can be carried out in the same procedure as in the case of using. Further, for example, the piezoelectric oscillator shown in FIG. 7 can be obtained by setting the resistor 41 and the resistor 45 to the open state, and the ambient temperature of the piezoelectric oscillator is measured in the same procedure as in the case of using the piezoelectric oscillator shown in FIG. The method can be carried out. That is, in the piezoelectric oscillator shown in FIG. 8, the output of the piezoelectric vibrator 42 can be adjusted in the direction in which the frequency increases as the temperature increases, that is, in the direction in which the frequency-temperature characteristic curve rotates counterclockwise. It is also possible to adjust the output of the piezoelectric vibrator 42 in the direction in which the frequency decreases, that is, in the direction in which the frequency temperature characteristic curve rotates clockwise.

  Therefore, according to the piezoelectric oscillator shown in FIG. 8 and the ambient temperature measuring method of the piezoelectric oscillator using the piezoelectric oscillator, the same effect as the ambient temperature measuring method of the piezoelectric oscillator shown in FIGS. 4 and 7 and the piezoelectric oscillator using the piezoelectric oscillator is obtained. In addition, the configuration of the frequency control circuit 6c can be selected at the time of use. As a result, it can be widely used in various piezoelectric oscillators having different frequency temperature characteristics.

[Electric Configuration Example 4 of Piezoelectric Oscillator]
Next, Example 4 of the electrical configuration of the piezoelectric oscillator 10 shown in FIG. 1 will be described with reference to FIG. FIG. 9 is a circuit diagram showing an electrical configuration example 4 of the piezoelectric oscillator 10 shown in FIG. 1, 3, 4, 7, 8, and 9, the same reference numerals indicate the same parts, and the description of the same parts is omitted.

  In the piezoelectric oscillator shown in FIG. 9, when a change in ambient temperature is measured, a change in current of the heater unit 2 is used as a change in power consumption of the heater unit 2.

  The frequency temperature characteristics of the piezoelectric oscillator shown in FIG. 9 are the same as the frequency temperature characteristics of the piezoelectric oscillator shown in FIG. 4 (see FIG. 6).

  In the piezoelectric oscillator shown in FIG. 9, the frequency control circuit 6d measures the change in the ambient temperature based on the change in the current of the heater unit 2, and further controls the frequency of the piezoelectric vibrator 42 according to the measurement result.

  The piezoelectric oscillator shown in FIG. 9 differs from the piezoelectric oscillator shown in FIG. 4 in the configuration of the frequency control circuit 6d, and the other configurations are the same.

  The frequency control circuit 6 d is composed of resistors 91, 92, 93, 44 and a varicap diode 43. More specifically, in the piezoelectric oscillator shown in FIG. 9, the resistor 41 and the resistor 45 shown in FIG. 4 are eliminated, and one terminal of the resistor 91 is connected to the emitter terminal of the transistor 2b. Is connected to a connection point b between one terminal of the piezoelectric vibrators 42 connected in series and a cathode terminal of the varicap diode 43 via a resistor 92. Note that one terminal of the resistor 93 is connected to a connection point h between the resistor 92 and the connection point b. The other terminals of the resistors 91 and 93 are grounded. That is, the frequency control circuit 6d converts the current of the heater unit 2 into a voltage, and measures the change in the ambient temperature based on the change in the voltage after the conversion.

  In the piezoelectric oscillator shown in FIG. 9, the values of the resistors 44, 91, 92, and 93 are selected so that the variation of the frequency temperature characteristic is minimized within a predetermined temperature range set with respect to the reference temperature. .

  In the piezoelectric oscillator shown in FIG. 9, the entire frequency control circuit 6d is arranged outside the thermostat 4. However, only the resistor 91 in the frequency control circuit 6d is inside the thermostat 4 together with the transistor 2b (for example, FIG. 3). May be disposed on one main surface 12a) of the main substrate 12 shown in FIG.

  Next, an example of a method for measuring the ambient temperature of the piezoelectric oscillator using the piezoelectric oscillator shown in FIG. 9 will be described with reference to FIG.

  When the method for measuring the ambient temperature of the piezoelectric oscillator using the piezoelectric oscillator shown in FIG. 9 is performed, in the state where the ambient temperature has not changed, the temperature sensor is operated in the same procedure as the case where the piezoelectric oscillator shown in FIG. 4 is used. 3. The temperature control unit 5 and the heater unit 2 control the temperature of the piezoelectric vibrator 42, and detailed description thereof is omitted.

  Here, the relationship between the current of the heater unit 2 and the ambient temperature will be described with reference to FIG. FIG. 10 is a graph showing the relationship between the current of the heater unit 2 and the ambient temperature. The vertical axis represents the heater current (A), which is the current of the heater unit, and the horizontal axis represents the ambient temperature (° C.). However, the temperature of the piezoelectric vibrator 42 measured by the temperature sensor 3 is controlled to be substantially constant.

  As indicated by L4 in FIG. 10, when the ambient temperature rises in the range of about −40 degrees to about 80 degrees, the heater current decreases, and the heater current is a linear function with respect to the ambient temperature. That is, the current of the heater unit 2 changes in accordance with the sum of the influences of changes in the ambient temperature received by all the members thermally connected to the heater unit 2. Thereby, according to the piezoelectric oscillator shown in FIG. 9, it is possible to measure the change in the ambient temperature based on the change in the current of the heater unit 2.

  For example, when the ambient temperature increases, the current of the heater unit 2 decreases as shown in FIG. As a result, the voltage at the connection point b increases, the potential difference between the cathode terminal and the anode terminal of the varicap diode 43 increases, and the capacitance of the varicap diode 43 decreases. Further, for example, when the ambient temperature is lowered, the current of the heater unit 2 is increased as shown in FIG. As a result, the voltage at the connection point b decreases, the potential difference between the cathode terminal and the anode terminal of the varicap diode 43 decreases, and the capacitance of the varicap diode 43 increases.

  In the piezoelectric oscillator shown in FIG. 9, by performing such an operation in the frequency control circuit 6d, the capacitance of the varicap diode 43 is adjusted according to the change in the ambient temperature, the frequency of the piezoelectric vibrator 42 is controlled, The frequency temperature characteristics of the piezoelectric oscillator are adjusted. Therefore, the frequency deviation can be made substantially constant. That is, in the piezoelectric oscillator shown in FIG. 9, the output of the piezoelectric vibrator 42 can be adjusted in the direction in which the frequency increases as the temperature increases, that is, in the direction in which the frequency-temperature characteristic curve rotates counterclockwise.

  Therefore, according to the piezoelectric oscillator shown in FIG. 9 and the method for measuring the ambient temperature of the piezoelectric oscillator using the piezoelectric oscillator, the outside temperature sensor 206 (see FIG. 12) can be omitted. As a result, the piezoelectric oscillator can be downsized and manufactured at low cost.

  Further, according to the piezoelectric oscillator shown in FIG. 9 and the method for measuring the ambient temperature of the piezoelectric oscillator using the piezoelectric oscillator, the sum of the influences of changes in the ambient temperature received by all the members thermally connected to the heater unit 2. Since the change in the ambient temperature is measured based on the change in the current of the heater unit 2, the change in the ambient temperature can be correctly measured.

  Further, according to the piezoelectric oscillator shown in FIG. 9 and the ambient temperature measuring method of the piezoelectric oscillator using the piezoelectric oscillator, the frequency of the piezoelectric vibrator 42 is controlled by the frequency control circuit 6d based on the measured change in the ambient temperature. Therefore, even when the ambient temperature changes, the piezoelectric oscillator can be oscillated at a stable frequency.

  In the present embodiment, the heater section 2 is arranged outside the aluminum block 15 as shown in FIGS. 4, 7, 8 and 9, but the resistor 2a and the transistor constituting the heater section 2 are arranged. Of 2b, the resistor 2a may be disposed inside the aluminum block 15. In the present embodiment, the transistor 2b is disposed inside the thermostat 4 as shown in FIGS. 4, 7, 8, and 9, but the outside of the thermostat 4 (for example, the main shown in FIG. 3). It may be arranged on the other main surface 12b) of the substrate 12.

  Further, in the present specification, a constant temperature bath type piezoelectric oscillator is described as an example of the piezoelectric oscillator, but the present invention is not limited to this embodiment. For example, the temperature may be adjusted using a temperature sensor or a heater unit, but the present invention may be implemented in a piezoelectric oscillator that does not include an aluminum block in a thermostatic chamber. In this case, the same effect as the piezoelectric oscillator 10 shown in FIG. 1 can be obtained, and the piezoelectric oscillator can be further downsized.

  Further, for example, the present invention may be implemented in a piezoelectric oscillator in which the thermostatic chamber has a double structure and can perform more precise temperature adjustment. In this case, the same effect as the piezoelectric oscillator 10 shown in FIG. 1 can be obtained, and the frequency temperature characteristic of the piezoelectric oscillator can be stabilized with higher accuracy.

  As the crystal resonator element of the piezoelectric vibrator, an AT cut crystal diaphragm or an SC cut crystal diaphragm can be used.

  Further, the oscillation circuit has a steep frequency selection function in order to suppress overtone oscillation and / or to suppress B-MODE (B mode) oscillation when an SC cut crystal diaphragm is used. For example, a tank circuit or B.I. P. It is preferable to provide F (Band Pass filter).

  Furthermore, when designing a part related to oscillation consisting of an oscillation circuit, a frequency selection circuit constituting this oscillation circuit, and a piezoelectric vibrator, in order to suppress the generation of phase noise in the piezoelectric oscillator and short-term stability (short time period) In order to improve the irregular output frequency), it is necessary to improve the Q value of the part.

  The piezoelectric oscillator and the method for measuring the ambient temperature of the piezoelectric oscillator of the present invention can be utilized when stabilizing the frequency of the piezoelectric oscillator.

DESCRIPTION OF SYMBOLS 1 Piezoelectric vibrator 2 Heater part 3 Temperature sensor 4 Thermostatic bath 5 Temperature control part 6 Frequency control circuit 10 Piezoelectric oscillator 18 Oscillation part

Claims (7)

In the piezoelectric oscillator,
An oscillation part including a piezoelectric vibrator and an oscillation circuit, a heater part for heating the piezoelectric vibrator, and a temperature control part for controlling the temperature of the heater part,
A change in temperature around the piezoelectric oscillator is measured based on a change in power consumption of the heater unit. The piezoelectric oscillator according to claim 1, wherein
A piezoelectric oscillator that uses a change in voltage of the heater unit or a change in current of the heater unit as a change in power consumption of the heater unit. The piezoelectric oscillator according to claim 1 or 2,
A piezoelectric oscillator further comprising a frequency control circuit for controlling a frequency of the piezoelectric vibrator based on a change in temperature around the piezoelectric oscillator. The piezoelectric oscillator according to any one of claims 1 to 3,
A piezoelectric oscillator, further comprising a thermostatic chamber, wherein the piezoelectric vibrator and the heater section are arranged inside the thermostatic chamber. The piezoelectric oscillator according to claim 4, wherein
A temperature sensor for measuring the temperature of the piezoelectric vibrator;
The temperature sensor is arranged inside the thermostat,
A piezoelectric oscillator that controls the operation of the heater unit based on the measurement result of the temperature sensor. In the method for measuring the ambient temperature of a piezoelectric oscillator,
The piezoelectric oscillator includes an oscillation unit including a piezoelectric vibrator and an oscillation circuit, a heater unit that warms the piezoelectric vibrator, and a temperature control unit that controls the temperature of the heater unit.
A procedure for measuring the temperature of the piezoelectric vibrator with the temperature sensor;
A procedure for controlling the operation of the heater unit based on the measurement result of the temperature sensor;
A method of measuring an ambient temperature of the piezoelectric oscillator, comprising: measuring a change in temperature around the piezoelectric oscillator based on a change in power consumption of the heater unit. The ambient temperature measurement method for a piezoelectric oscillator according to claim 6,
The piezoelectric oscillator further includes a frequency control circuit that controls the frequency of the piezoelectric vibrator based on a change in temperature around the piezoelectric oscillator,
A method for measuring an ambient temperature of a piezoelectric oscillator, further comprising a step of controlling a frequency of the piezoelectric vibrator by the frequency control circuit based on a change in an ambient temperature of the piezoelectric oscillator.

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