JP5218372B2 - Piezoelectric oscillator and frequency control method of piezoelectric oscillator - Google Patents

Description

  The present invention relates to a piezoelectric oscillator including a piezoelectric vibrator, and a heater unit and a temperature control unit for maintaining the temperature of the piezoelectric vibrator at a predetermined temperature.

  As an example of a conventional piezoelectric oscillator, there is one configured to keep the temperature of a piezoelectric vibrator constituting a part of the piezoelectric oscillator constant (see, for example, Patent Document 1).

  This piezoelectric oscillator includes a piezoelectric vibrator, a heating element, and a temperature sensor, and measures the temperature of the piezoelectric vibrator with the temperature sensor. Then, the signal indicating the temperature measured by the temperature sensor is replaced with a current signal for controlling the heating element by a temperature control unit connected between the heating element and the temperature sensor, and the driving current of the heating element is determined by the current signal. Adjust. As a result, the amount of heat generated by the heating element changes, and the temperature of the piezoelectric vibrator is adjusted to a preset value.

  By the way, the frequency of the piezoelectric oscillator varies due to the frequency-temperature characteristics of the piezoelectric vibrator. Accordingly, the frequency-temperature characteristics of the piezoelectric vibrator will be described with reference to FIG. FIGS. 17A and 17B show a frequency temperature characteristic L11 of a piezoelectric vibrator having an AT-cut crystal vibrating piece and a frequency temperature characteristic L12 of a piezoelectric vibrator having an SC-cut crystal vibrating piece. It is a graph, a vertical axis | shaft shows a frequency deviation (ppm) and a horizontal axis shows the temperature (degreeC) of a piezoelectric vibrator. FIG. 17A shows frequency temperature characteristics L11 and L12 of each piezoelectric vibrator in a temperature range of −40 ° C. to 140 ° C., and FIG. 17B shows a temperature range of 70 to 90 ° C. The more detailed frequency temperature characteristics L11 and L12 of each piezoelectric vibrator are shown.

  As shown in FIG. 17A, the temperature of the piezoelectric vibrator is a variable in both the piezoelectric vibrator having the AT-cut crystal vibrating piece and the piezoelectric vibrator having the SC-cut crystal vibrating piece. In this case, the frequency deviation is expressed as a cubic function.

  In the conventional piezoelectric oscillator described above, temperature control is performed so that the temperature of the piezoelectric vibrator is maintained at a temperature within a range of 75 ° C. to 85 ° C., for example, as shown in FIG. Furthermore, the frequency deviation of the piezoelectric vibrator is suppressed within a range of 0 to 0.4 ppm. For this reason, in the conventional piezoelectric oscillator, the piezoelectric vibrator oscillates at a relatively stable frequency as compared with the case where the temperature of the piezoelectric vibrator is not controlled at all.

Japanese Patent No. 3272633

  However, even if the temperature of the piezoelectric vibrator is kept substantially constant, for example, at a temperature in the range of 75 ° C. to 85 ° C., as shown in FIG. 17B, the frequency deviation of the piezoelectric vibrator is 2 Fluctuates slightly in the order of function.

  For this reason, even in the above-described conventional piezoelectric oscillator, the oscillation frequency slightly changed due to the above-described frequency temperature characteristics of the piezoelectric vibrator.

  The present invention has been made in view of such a situation, and is a piezoelectric oscillator provided with a piezoelectric vibrator, a heater unit for maintaining the temperature of the piezoelectric vibrator at a predetermined temperature, and a temperature control unit. Another object of the present invention is to provide a piezoelectric oscillator in which frequency fluctuations due to changes in ambient temperature are reduced.

  Alternatively, the present invention reduces frequency fluctuations due to changes in ambient temperature with respect to a piezoelectric oscillator provided with a piezoelectric vibrator and a heater unit and a temperature control unit for maintaining the temperature of the piezoelectric vibrator at a predetermined temperature. Another object of the present invention is to provide a method for controlling the frequency of a piezoelectric oscillator.

  A piezoelectric oscillator according to the present invention includes an oscillation unit including a piezoelectric vibrator and an oscillation circuit, a heater unit for heating the piezoelectric vibrator composed of a plurality of elements, and the heater unit to the piezoelectric vibrator. A temperature control unit that controls the amount of heat released, and at least one of the plurality of elements constituting the heater unit, the power consumption of which varies in a quadratic function with respect to a temperature change around the piezoelectric oscillator. And a frequency control circuit that controls the frequency of the piezoelectric vibrator based on a temperature change.

  According to this configuration, based on the temperature change of one element whose power consumption fluctuates in a quadratic function with respect to the temperature change around the piezoelectric oscillator among the plurality of elements constituting the heater unit, the piezoelectric vibrator Because the frequency of the piezoelectric vibrator is controlled, the piezoelectric vibrator and the heater section and the temperature control section for maintaining the temperature of the piezoelectric vibrator at a predetermined temperature are compared with changes in ambient temperature. Frequency fluctuation can be reduced. In particular, compensation for frequency fluctuations due to frequency temperature characteristics that change in a quadratic function of the piezoelectric vibrator can be realized with a simple circuit configuration.

  In the piezoelectric oscillator according to the aspect of the invention, the heater unit may include a transistor and a heater resistor as the element, and the frequency control circuit may be configured based on a temperature change of the transistor. The frequency may be controlled.

  With this configuration, frequency fluctuations due to changes in ambient temperature can be reliably reduced. In particular, in a heater unit in which a heater resistor and a transistor are combined, the power consumption of the transistor changes in a quadratic function with respect to the temperature change around the piezoelectric oscillator, as shown in FIG. For this reason, by using the temperature change of the transistor corresponding to this change in power consumption, compensation for frequency fluctuations due to the frequency temperature characteristic that changes in a quadratic function of the piezoelectric vibrator can be made with a simpler circuit configuration. Can be realized.

  In the piezoelectric oscillator according to the aspect of the invention, the frequency control circuit may further control the frequency of the piezoelectric vibrator based on a temperature change around the piezoelectric oscillator.

  In this configuration, since the frequency of the piezoelectric vibrator is controlled based on the temperature change around the piezoelectric oscillator, the frequency fluctuation due to the change in the ambient temperature can be further reduced. That is, compensation for frequency fluctuations due to the frequency temperature characteristics of the piezoelectric vibrator can be performed more accurately.

  In the piezoelectric oscillator according to the aspect of the invention, the frequency control circuit may further include the piezoelectric vibrator based on a change in current of the heater unit that varies in a linear function with respect to a temperature change around the piezoelectric oscillator. The frequency may be controlled.

  In this configuration, the frequency of the piezoelectric vibrator is further controlled based on a change in the current of the heater unit that varies in a linear function with respect to a change in the ambient temperature of the piezoelectric oscillator. Frequency fluctuations can be further reduced. That is, it is possible to more accurately compensate for frequency fluctuations due to the frequency temperature characteristics of the piezoelectric vibrator.

  The piezoelectric oscillator according to the present invention may further include a thermostatic chamber that keeps the piezoelectric vibrator at a predetermined temperature, and the piezoelectric vibrator may be disposed inside the thermostatic bath.

  In this configuration, the temperature of the piezoelectric oscillator can be kept more constant, and the piezoelectric vibrator can be oscillated at a more stable frequency.

  In the piezoelectric oscillator according to the present invention, when the thermostatic chamber is provided, the heater unit may be arranged outside the thermostatic chamber.

  In this configuration, compared to the case where the heater unit is disposed inside the thermostat, the influence of the temperature and thermal gradient inside the thermostat can be reduced, and the piezoelectric vibrator can be oscillated at a more stable frequency.

  In the piezoelectric oscillator of the present invention, in the case where the thermostatic chamber is provided, the oscillation unit is disposed on one main surface of the substrate, and a thermostatic unit that maintains the piezoelectric vibrator at a predetermined temperature is provided inside the substrate. It is preferable that a constant temperature case for sealing the oscillating portion is provided on one main surface, and the constant temperature bath is constituted by the constant temperature portion and the constant temperature case.

  In this configuration, since the thermostat is composed of the thermostat case and the thermostat, it is possible to minimize an increase in size and an increase in manufacturing cost due to the provision of the thermostat. In addition, a constant temperature case for sealing the oscillation part is provided on one main surface of the substrate, and the oscillation part is sealed by the constant temperature part and the constant temperature case. It can be reduced in height and size.

  According to the frequency control method of the piezoelectric oscillator of the present invention, the piezoelectric oscillator includes an oscillation unit including a piezoelectric vibrator and an oscillation circuit, a heater unit for heating the piezoelectric vibrator configured by a plurality of elements, and the heater A temperature control unit that controls the amount of heat released from the unit to the piezoelectric vibrator, and among the plurality of elements constituting the heater unit, power consumption with respect to a temperature change around the piezoelectric oscillator An element temperature measuring step for measuring a temperature change of one element that varies in a quadratic function, and a frequency control step for controlling the frequency of the piezoelectric vibrator based on a measurement result in the element temperature measuring step. It is characterized by having.

  According to this method, a piezoelectric oscillator including a piezoelectric vibrator and a heater unit and a temperature control unit for maintaining the temperature of the piezoelectric vibrator at a predetermined temperature consumes less power with respect to changes in ambient temperature. Since the frequency of the piezoelectric vibrator is controlled based on the temperature change of one element constituting the heater unit that varies in a quadratic function, the frequency fluctuation due to the change in the ambient temperature can be reduced. In particular, compensation for frequency fluctuations due to frequency temperature characteristics that change in a quadratic function of the piezoelectric vibrator can be realized with a simple circuit configuration.

  The frequency control method for a piezoelectric oscillator according to the present invention further includes an ambient temperature measurement step for measuring a temperature change around the piezoelectric oscillator, and the frequency control step further includes a measurement result in the ambient temperature measurement step. Based on the above, the frequency of the piezoelectric vibrator may be controlled.

  In this method, since the frequency of the piezoelectric vibrator is controlled based on the temperature change around the piezoelectric oscillator, the frequency fluctuation due to the change in the ambient temperature can be further reduced. That is, compensation for frequency fluctuations due to the frequency temperature characteristics of the piezoelectric vibrator can be performed more accurately.

  Further, in the frequency control method for a piezoelectric oscillator according to the present invention, the frequency control step is further based on a change in current of the heater unit that varies in a linear function with respect to a change in temperature around the piezoelectric oscillator. The frequency of the piezoelectric vibrator may be controlled.

  In this method, the frequency of the piezoelectric vibrator is further controlled based on a change in the current of the heater unit that varies in a linear function with respect to a change in temperature around the piezoelectric oscillator. Can be further reduced. That is, it is possible to more accurately compensate for frequency fluctuations due to the frequency temperature characteristics of the piezoelectric vibrator.

  According to the present invention, in a piezoelectric oscillator provided with a piezoelectric vibrator and a heater section and a temperature control section for maintaining the temperature of the piezoelectric vibrator at a predetermined temperature, frequency fluctuation due to a change in ambient temperature is reduced. be able to.

1 is a block diagram showing a piezoelectric oscillator according to Embodiment 1 of the present invention. It is a graph which shows the relationship between the power consumption of a heater part, and ambient temperature. It is a graph which shows the relationship between the temperature measured by each of the primary compensation sensor and the secondary compensation sensor, and the ambient temperature. It is a perspective view which shows an example of the structure of the piezoelectric oscillator which concerns on Embodiment 1 of this invention. FIG. 5 is a schematic exploded view of a main body casing, a substrate, and a metal case constituting the piezoelectric oscillator shown in FIG. 4. FIG. 5 is a schematic plan view showing a positional relationship among a substrate constituting the piezoelectric oscillator shown in FIG. 4 and a heater section, a temperature control sensor, a primary compensation sensor, and a secondary compensation sensor on the substrate. It is a schematic perspective view which shows the metal case which comprises the piezoelectric oscillator shown in FIG. It is a circuit diagram which shows an example of the electrical constitution of the piezoelectric oscillator which concerns on Embodiment 1 of this invention. It is a graph which shows an example of the frequency temperature characteristic of the piezoelectric oscillator shown in FIG. It is a graph which shows the relationship between the voltage in the connection point a of the frequency control circuit of the piezoelectric oscillator shown in FIG. 8, and ambient temperature. It is a graph which shows the relationship between the voltage which generate | occur | produces with the circuit for secondary compensation of the frequency control circuit of the piezoelectric oscillator shown in FIG. 8, and ambient temperature. It is a graph which shows the relationship between the voltage which generate | occur | produces with the circuit for primary compensation of the frequency control circuit of the piezoelectric oscillator shown in FIG. 8, and ambient temperature. It is a block diagram which shows the piezoelectric oscillator which concerns on Embodiment 2 of this invention. It is a perspective view which shows an example of the structure of the piezoelectric oscillator which concerns on Embodiment 2 of this invention. It is a schematic plan view which shows the positional relationship of the board | substrate which comprises the piezoelectric oscillator shown in FIG. 14, and the heater part on the board | substrate, the sensor for temperature control, and the sensor for secondary compensation. It is a circuit diagram which shows an example of the electrical constitution of the piezoelectric oscillator which concerns on Embodiment 2 of this invention. It is a graph which shows the frequency temperature characteristic of a piezoelectric vibrator, (a) is a graph which shows the frequency temperature characteristic of a piezoelectric vibrator in the range of -40 degreeC-140 degreeC, (b) is the range of 70 degreeC-90 degreeC. 5 is a graph showing the frequency temperature characteristics of the piezoelectric vibrator in more detail.

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

<Embodiment 1>
FIG. 1 is a block diagram showing a piezoelectric oscillator 1 according to Embodiment 1 of the present invention.

  The piezoelectric oscillator 1 is a so-called thermostatic bath-equipped piezoelectric oscillator including a thermostatic chamber 7. A piezoelectric oscillator 1 shown in FIG. 1 includes a piezoelectric vibrator 2, an oscillation circuit 6a, a secondary compensation sensor 51, a temperature control sensor 41, and a frequency control circuit 5 inside a thermostatic chamber 7. Outside the thermostatic chamber 7, a heater unit 3 of the piezoelectric vibrator 2, a temperature control unit 4, and a primary compensation sensor 52 are provided. In the present embodiment, the oscillating unit 6 includes the piezoelectric vibrator 2, the oscillation circuit 6 a, and the frequency control circuit 5.

  As the piezoelectric vibrator 2, for example, a crystal vibrating piece such as an SC cut and an AT cut is used. The piezoelectric vibrator 2 is vibrated by the voltage applied by the oscillation circuit 6a.

  A temperature control sensor 41 is disposed in the vicinity of the piezoelectric vibrator 2, and the temperature change of the piezoelectric vibrator 2 is measured by measuring the temperature in the vicinity of the piezoelectric vibrator 2 by the temperature control sensor 41.

  The heater unit 3 is composed of a plurality of elements, specifically, a transistor 32 and a heater resistor 31 (see FIG. 4 to be described later). By these elements, the inside of the thermostatic chamber 7 is heated and indirectly. The piezoelectric vibrator 2 is heated. That is, the piezoelectric vibrator 2 is heated by releasing heat to the piezoelectric vibrator 2.

  In addition, the heater unit 3 is arranged outside the thermostatic chamber 7, and compared with the case where the heater unit 3 is arranged inside the thermostatic chamber 7, the influence of the temperature and heat gradient in the thermostatic chamber 7 is reduced, and the piezoelectric element is piezoelectric. The vibrator 2 oscillates at a more stable frequency.

  The operation of the heater unit 3 is controlled by the temperature control unit 4. Specifically, the temperature control unit 4 obtains a difference between the temperature in the vicinity of the piezoelectric vibrator 2 measured by the temperature control sensor 41 and a preset temperature, and according to the magnitude of the obtained difference, The amount of heat released from the heater unit 3 to the piezoelectric vibrator 2 is controlled to control the temperature of the piezoelectric vibrator 2.

  Under such an environment, the temperature around the piezoelectric oscillator 1 schematically shown by a two-dot chain line in FIG. 1 (that is, around the product main body) (hereinafter referred to as ambient temperature) is maintained at a constant temperature. In this case, the temperature of the piezoelectric vibrator 2 is maintained at a constant temperature.

  However, even if the temperature control unit 4 maintains the temperature of the piezoelectric vibrator 2 at, for example, a temperature around 80 ° C., as shown in FIG. 17B, the frequency deviation of the piezoelectric vibrator 2 is It fluctuates in a quadratic function with respect to a slight temperature change of the piezoelectric vibrator 2. When the control by the frequency control circuit 5 is not performed due to the frequency temperature characteristic of the piezoelectric vibrator 2, the frequency of the piezoelectric oscillator 1 is about −40 ° C. to about −40 ° C. as indicated by L 7 in FIG. It slightly fluctuates in a quadratic function with respect to changes in ambient temperature within a range of about 75 ° C.

  Therefore, in the present embodiment, in order to reduce the fluctuation in the frequency of the piezoelectric oscillator 1 due to such a change in the ambient temperature, the voltage applied to the piezoelectric vibrator 2 is controlled to control the frequency of the piezoelectric vibrator 2. A frequency control circuit 5 is provided.

  Here, the relationship between the power consumption of the heater unit 3 and the ambient temperature will be described with reference to FIG. FIG. 2 is a graph showing the relationship between the power consumption of the heater unit 3 and the ambient temperature, where the vertical axis represents power consumption (W) and the horizontal axis represents ambient temperature (° C.). However, it is assumed that the temperature of the piezoelectric vibrator 2 measured by the temperature control sensor 41 is controlled to be substantially constant.

  The power consumption of the entire heater unit 3 (that is, the total power consumption of the transistor 32 and the heater resistor 31) is in the range of about −40 ° C. to about 75 ° C., as shown by L1 in FIG. , And fluctuates linearly with changes in ambient temperature.

  As shown by L3 in FIG. 2, the power consumption of the transistor 32 constituting the heater unit 3 is a frequency control indicated by L7 in FIG. 9 with respect to a change in ambient temperature in a range of about −40 ° C. to about 75 ° C. It fluctuates in a quadratic function whose polarity is opposite to that of the frequency temperature characteristic when the control by the circuit is not performed.

  Further, the power consumption of the heater resistor 31 constituting the heater section is a quadratic function that decreases as the ambient temperature rises in the range of about −40 ° C. to about 75 ° C. as indicated by L2 in FIG. fluctuate.

  That is, in the range of about −40 ° C. to about 75 ° C., the power consumption of the transistor 32 and the heater resistor 31 fluctuates in a quadratic function with respect to the change in the ambient temperature, and the total of the power consumption (that is, The power consumption of the heater unit 3) varies in a linear function.

  Therefore, in the piezoelectric oscillator 1 according to the present embodiment, paying attention to the change in power consumption with respect to the ambient temperature of the heater unit 3 as described above, among the elements (heater resistor 31 and transistor 32) constituting the heater unit 3, An element whose power consumption fluctuates in a quadratic function with respect to a change in ambient temperature, that is, a secondary compensation sensor 51 for measuring a temperature change of the transistor 32 is provided. Furthermore, the piezoelectric oscillator 1 according to the present embodiment is provided with a primary compensation sensor 52 for measuring a temperature change around the piezoelectric oscillator 1.

  FIG. 3 is a graph showing the relationship between the temperature measured by each of the secondary compensation sensor 51 and the primary compensation sensor 52 and the ambient temperature. In FIG. 3, the vertical axis indicates the temperature (° C.) measured by the secondary compensation sensor 51 or the primary compensation sensor 52, and the horizontal axis indicates the ambient temperature (° C.).

  Similar to the power consumption of the transistor 32, the temperature measured by the secondary compensation sensor 51 is within a range of about −40 ° C. to about 75 ° C. with respect to changes in ambient temperature, as indicated by L4 in FIG. Fluctuates in a quadratic function.

  Further, as shown by L5 in FIG. 3, the temperature measured by the primary compensation sensor 52 rises in proportion to the increase in ambient temperature within the range of about −40 ° C. to about 75 ° C., Fluctuates linearly with changes in ambient temperature.

  Based on such temperature characteristics, the following frequency control method is implemented in the piezoelectric oscillator 1 of the present embodiment.

  That is, the piezoelectric oscillator 1 according to the present embodiment is adapted to the temperature change around the piezoelectric oscillator 1 among the plurality of elements (the heater resistor 31 and the transistor 32) constituting the heater unit 3 by the secondary compensation sensor 51. The temperature change of one element (transistor 32) whose power consumption fluctuates in a quadratic function is measured (element temperature measurement step), and the temperature change around the piezoelectric oscillator 1 is measured by the primary compensation sensor 52. (Ambient temperature measurement step). The frequency control circuit 5 controls the frequency of the piezoelectric vibrator 2 based on the measurement result in the element temperature measurement step and the measurement result in the ambient temperature measurement step (frequency control step).

  More specifically, the frequency control circuit 5 compensates for the secondary component of the frequency temperature characteristic of the piezoelectric oscillator 1 by using the temperature change of the transistor 32 that varies in a quadratic function with respect to the change in the ambient temperature. Simultaneously with the generation of the control voltage, the frequency of the piezoelectric vibrator 2 is controlled by generating a control voltage that compensates for the primary component of the frequency temperature characteristic of the piezoelectric oscillator 1 using the change in the ambient temperature.

  By controlling the frequency of the piezoelectric vibrator 2 in this way, in the piezoelectric oscillator 1 according to the first embodiment, as indicated by L6 in FIG. There are few. Further, by using the temperature change of the transistor 32 of the heater unit 3 whose power consumption changes in a quadratic function with respect to the ambient temperature, it depends on the frequency temperature characteristic of the piezoelectric vibrator 2 that changes in a quadratic function. Compensation for frequency fluctuation can be realized with a simple circuit configuration.

—Structural Example 1 of Piezoelectric Oscillator—
Next, an example of the structure of the piezoelectric oscillator 1 according to the first embodiment of the present invention will be described with reference to FIGS.

  FIG. 4 is a perspective view showing an example of the structure of the piezoelectric oscillator 1 according to Embodiment 1 of the present invention. FIG. 5 shows a main body housing 9 and a substrate 8 that constitute the piezoelectric oscillator 1 shown in FIG. FIG. 4 is a schematic exploded view of a metal case 72.

  In this structural example, the piezoelectric oscillator 1 includes an oscillation unit including a substrate 8, a piezoelectric vibrator 2 disposed on one main surface 80 of the substrate 8, and an oscillation circuit (not shown), as shown in FIGS. 4 and 5. And a metal case 72 (constant temperature case according to the present invention) for sealing the oscillating portion.

  As shown in FIGS. 4 and 5, the main body housing 9 of the piezoelectric oscillator 1 is composed of a protective case 91 having an opening 90 formed on one surface, and a constituent member of the piezoelectric oscillator 1 joined to the protective case 91. It consists of a base 92 for sealing. An external lead terminal 93 that is electrically connected to an external electronic device is formed on the base 92 so as to protrude from the inside (inside) of the main body housing 9 to the outside (outside). The protective case 91 and the base 92 are formed using metal, and an insulating member made of glass or the like is interposed between the base 92 and the external lead terminal 93. With this configuration, it is possible to deal with EMS (Electro Magnetic Susceptibility).

  Next, each configuration of the piezoelectric oscillator 1 shown in FIG. 4 will be described in detail with reference to FIGS. 6 shows the positional relationship among the substrate 8 constituting the piezoelectric oscillator 1 shown in FIG. 4 and the heater unit 3, the temperature control sensor 41, the primary compensation sensor 52, and the secondary compensation sensor 51 on the substrate 8. It is a schematic plan view which shows. Further, FIG. 7 is a schematic perspective view showing a metal case 72 constituting the piezoelectric oscillator 1 shown in FIG.

  As shown in FIGS. 4 and 5, the piezoelectric vibrator 2 is supported by a crystal vibrating piece (not shown) such as an SC cut or an AT cut, a support base 23 that supports the crystal vibrating piece, and a support base 23. And a cap 24 for hermetically sealing the quartz crystal vibrating piece. The crystal vibrating piece is formed with a pair of excitation electrodes (not shown) and an extraction electrode (not shown) drawn from the pair of excitation electrodes. Two lead terminals 21 are bonded to the support base 23 using an insulating bonding material. Each of the two lead terminals 21 includes an outer lead portion extending outward from the support base 23 and an inner lead portion disposed inside the piezoelectric vibrator 2 and joined to the extraction electrode of the crystal vibrating piece. It is configured. As shown in FIG. 4, the two lead terminals 21 are arranged at the same position in the side view of the piezoelectric vibrator 2. Further, the two lead terminals 21 extend outward from the support base 23 in the same direction.

  As shown in FIGS. 4 and 7, the metal case 72 is a box-like body having an opening 73 formed on one end surface. When the metal case 72 is disposed on the substrate 8, the opening 73 is formed on the substrate 8. It faces the main surface 80. The metal case 72 includes a top plate 76 and four side plates 70, and the side plate 70 is suspended from the outer peripheral end of the top plate 76. Of these four side plates 70, any two opposing side plates 70 are formed with protruding pieces 74 protruding from their tips. The metal case 72 is preferably formed of a material having high thermal conductivity, and brass is used in this structural example.

  The substrate 8 is composed of a multilayer substrate in which a plurality of layers are laminated, and is, for example, a resin substrate having a thermal conductivity of 0.2 W / (m · K) to 0.5 W / (m · K). As a specific example, a paper phenol substrate, a paper epoxy substrate, a glass composite substrate, a glass epoxy substrate, or a fluororesin substrate can be used as the substrate 8.

  As shown in FIG. 4, a constant temperature portion 71 that keeps the piezoelectric vibrator 2 at a predetermined temperature is provided inside the substrate 8. The constant temperature part 71 is formed in an intermediate layer of the substrate 8 and is a heat conductive material having high heat conductivity, and is formed into a flat plate-like pattern having a rectangular shape in plan view. In this structural example, a solid pattern is used as the constant temperature portion 71.

  As shown in FIGS. 4 to 6, an oscillation circuit 6 a using the piezoelectric vibrator 2 as an oscillator is patterned (not shown) on one main surface 80 of the substrate 8 and integrated as a constituent member of the oscillation circuit 6 a. Circuit chip and other electronic components (not shown), frequency control circuit 5 (not shown), temperature control sensor 41 for measuring the temperature of the piezoelectric vibrator 2, and secondary for measuring the temperature change of the transistor 32 of the heater unit 3. A compensation sensor 51 and a primary compensation sensor 52 for measuring a change in ambient temperature are provided. In this structural example, a thermistor is used as each of the temperature control sensor 41, the secondary compensation sensor 51, and the primary compensation sensor 52.

  Further, as shown in FIG. 6, a rectangular region in plan view of the principal surface 80 of the substrate 8 of the constant temperature portion 71 (a region overlapping the constant temperature portion 71 in plan view) is defined as an overlapping region A, and a piezoelectric vibrator is provided in the overlapping region A. A mounting portion 83 for electrically connecting the two lead terminals 21 is formed. The mounting portion 83 is formed in a cylindrical concave shape having a depth that does not reach the constant temperature portion 71. A joining portion 82 that joins the metal case 72 is provided along the outer periphery of the overlapping region A. The joint portion 82 is formed in a rectangular parallelepiped concave shape along each side of the outer peripheral edge of the overlapping region A of the main surface 80 of the substrate 8. The bonding portion 82 is provided with a heat conductive film (not shown) having a high thermal conductivity extending from the concave inner surface to one main surface 80 of the substrate 8 outside the bonding portion 82. The heat conductive film is connected to the constant temperature part 71. In this structural example, copper is used as the heat conductive film.

  On the other main surface 81 of the substrate 8, as shown in FIGS. 4 and 6, a heater unit 3 that indirectly warms the piezoelectric vibrator 2 by heating the inside of the thermostatic chamber 7, and a piezoelectric element from the heater unit 3. A temperature control unit 4 that controls the amount of heat released to the vibrator 2 and controls the temperature of the piezoelectric vibrator 2 is provided. As described above, the heater unit 3 includes the transistor 32 and the heater resistor 31. In the present embodiment, a chip resistor or the like (not limited to the chip resistor may be a film resistor) is used as the heater resistor 31.

  The substrate 8 is formed with a plurality of via holes (not shown) penetrating from the main surface 80 of the substrate 8 on the constant temperature portion 71 to the constant temperature portion 71. In the via hole, the heater part 3 is connected to the constant temperature part 71 through the via hole, and heat from the heater part 3 is transmitted to the constant temperature part 71. Further, a hole 85 penetrating from one main surface 80 to the other main surface 81 is formed on the outer periphery in plan view of the substrate 8, and an external lead terminal 93 is inserted into the hole 85 as shown in FIG. 4.

  In the piezoelectric oscillator 1, the thermostatic chamber 7 is configured by the thermostatic portion 71 and the metal case 72. In the thermostatic chamber 7, the piezoelectric vibrator 2 and the oscillation circuit 6a disposed on one main surface of the substrate 8 are sealed, and the piezoelectric vibrator 2 is maintained at a predetermined temperature.

  Further, as shown in FIG. 4, the heater unit 3 (the transistor 32 and the heater resistor 31) and the primary compensation sensor 52 are arranged outside the thermostat 7, and the temperature control sensor 41 is arranged inside the thermostat 7. And a secondary compensation sensor 51 are arranged. In this structure example, as shown in FIGS. 4 and 6, the temperature control sensor 41 is provided at a position facing the cap 24 of the piezoelectric vibrator 2, and the secondary compensation sensor 51 is interposed via the substrate 8. And provided at a position facing the transistor 32. The primary compensation sensor 52 is provided at a position that is not easily affected by the heat released from the heater unit 3 and is away from the heater unit 3 outside the thermostat 7.

  According to the structure example 1 as described above, the thermostat 7 is composed of the metal case (constant thermostat) 72 and the thermostat 71, so that the increase in size and the increase in manufacturing cost due to the provision of the thermostat 7 are minimized. To the limit. In addition, a metal case 72 that seals the oscillating portion (the piezoelectric vibrator 2 and the oscillating circuit 6 a) is provided on one main surface 80 of the substrate 8, and the oscillating portion is sealed by the constant temperature portion 71 and the metal case 72. Compared with the case where the thermostat 7 is provided separately, the main body housing 9 can be reduced in height and size.

-Electrical configuration example of piezoelectric oscillator 1
Next, an example of the electrical configuration of the piezoelectric oscillator 1 according to the first embodiment of the present invention will be described with reference to FIG.

  FIG. 8 is a circuit diagram showing an example of the electrical configuration of the piezoelectric oscillator 1 according to the first embodiment of the present invention.

  In the piezoelectric oscillator 1 shown in FIG. 8, the frequency control circuit 5 measures the temperature change of the transistor 32 with the secondary compensation sensor 51, and measures the ambient temperature change with the primary compensation sensor 52. According to the result, the frequency of the piezoelectric vibrator 2 is controlled.

  As shown in FIG. 8, the frequency control circuit 5 constitutes the oscillation unit 6 together with the oscillation circuit 6 a and the piezoelectric vibrator 2. Further, the frequency control circuit 5 includes a secondary compensation sensor 51, a primary compensation sensor 52, resistors 53, 54, 55 and 56, and a varicap diode 57. In FIG. 1, for convenience, the secondary compensation sensor 51 and the primary compensation sensor 52 are illustrated separately from the frequency control circuit 5.

  The temperature control unit 4 includes an operational amplifier 46 formed of integrated circuit elements and resistors 42, 43, 44, and 45.

  The electrical configuration of the piezoelectric oscillator 1 shown in FIG. 8 will be described in more detail. One terminal of the heater resistor 31 and the collector terminal of the transistor 32 are connected in series. Here, the other terminal of the heater resistor 31 is connected to the power supply voltage (Vcc), and the emitter terminal of the transistor 32 is grounded.

  One terminal of the resistor 53 is connected to one terminal of the secondary compensation sensor 51 that measures the temperature change of the transistor 32. Further, the other terminal of the secondary compensation sensor 51 is connected to a power supply voltage via a power supply circuit. The secondary compensation sensor 51 is a temperature-sensitive element (for example, a thermistor) whose resistance value varies with temperature. In FIG. 8, the resistance value increases as the temperature decreases, and the resistance value decreases as the temperature increases. A temperature sensitive element is used.

  In addition, one terminal of the resistor 54 is connected to one terminal of the primary compensation sensor 52 that measures a change in ambient temperature. Further, the other terminal of the primary compensation sensor 52 is connected to the power supply circuit via the power supply circuit. The primary compensation sensor 52 is a temperature-sensitive element (for example, a thermistor) whose resistance value varies with temperature. In FIG. 8, the resistance value increases as the temperature decreases, and the resistance value decreases as the temperature increases. A temperature sensitive element is used.

  The other terminal of the resistor 53 and the other terminal of the resistor 54 are connected, and the connection point a is a connection point b between one terminal of the piezoelectric vibrator 2 connected in series and the cathode terminal of the varicap diode 57. It is connected to the. Further, one terminal of the resistor 55 is connected to the connection point b, and the other terminal of the resistor 55 is grounded. Further, one terminal of the resistor 56 is connected to the anode terminal of the varicap diode 57, and the other terminal of the resistor 56 is grounded.

  The other terminal of the piezoelectric vibrator 2 is connected to one terminal of the oscillation circuit 6a, and the connection point c between the anode terminal of the varicap diode 57 and the resistor 56 is connected to the other terminal of the oscillation circuit 6a. Has been.

  One terminal of the temperature control sensor 41 is connected to the non-inverting input terminal of the operational amplifier 46. Furthermore, one terminal of a resistor 44 is connected to a connection point d between the temperature control sensor 41 and the operational amplifier 46, and the other terminal of the resistor 44 is connected to a power supply voltage via a power supply circuit. Further, the other terminal of the temperature control sensor 41 is grounded. The temperature control sensor 41 is a temperature-sensitive element (for example, a thermistor) whose resistance value varies with temperature. In FIG. 8, the resistance value increases as the temperature decreases, and the resistance value decreases as the temperature increases. A temperature sensitive element is used.

  The connection point e between the resistors 42 and 43 connected in series is connected to the inverting input terminal of the operational amplifier 46. Furthermore, the other terminal of the resistor 42 is connected to the power supply voltage via the power supply circuit, and the other terminal of the resistor 43 is grounded.

  One terminal of the resistor 45 is connected to the connection point f between the inverting input terminal of the operational amplifier 46 and the connection point e, and the other terminal of the resistor 45 is connected to the output terminal of the operational amplifier 46. . Further, a connection point g between the output terminal of the operational amplifier 46 and the resistor 45 is connected to the base of the transistor 32 via the resistor 47.

  According to the electrical configuration as described above, for example, when the temperature in the vicinity of the piezoelectric vibrator 2 decreases, the resistance value of the temperature control sensor 41 increases and the voltage between the terminals of the temperature control sensor 41 increases. Output voltage increases. As a result, the output current of the operational amplifier 46 increases, the collector current of the transistor 32 increases, the current flowing through the heater resistor 31 increases, and the amount of heat generated by the heater resistor 31 increases. Therefore, when the temperature in the vicinity of the piezoelectric vibrator 2 decreases, the amount of heat generated by the heater resistor 31 increases and the piezoelectric vibrator 2 can be warmed more rapidly.

  For example, when the temperature in the vicinity of the piezoelectric vibrator 2 increases, the resistance value of the temperature control sensor 41 decreases, the voltage between the terminals of the temperature control sensor 41 decreases, and the output voltage of the operational amplifier 46 decreases. As a result, the output current of the operational amplifier 46 decreases, the collector current of the transistor 32 decreases, the current flowing through the heater resistor 31 decreases, and the amount of heat generated by the heater resistor 31 decreases. Therefore, when the temperature in the vicinity of the piezoelectric vibrator 2 increases, the amount of heat generated by the heater resistor 31 decreases and the piezoelectric vibrator 2 can be warmed gently.

  By performing such operations in the temperature control sensor 41, the temperature control unit 4, and the heater unit 3, the temperature of the piezoelectric vibrator 2 becomes a constant temperature, and the piezoelectric vibrator 2 is moved by the oscillation circuit 6a. Oscillates at a stable frequency according to the applied voltage.

  Further, in the piezoelectric oscillator 1 shown in FIG. 8, not only the temperature of the piezoelectric vibrator 2 is controlled by the temperature control sensor 41, the temperature control unit 4 and the heater unit 3, but also the temperature of the transistor 32 is controlled by the secondary compensation sensor 51. The change is measured, and the change in ambient temperature is measured by the primary compensation sensor 52. The frequency control circuit 5 controls the frequency of the piezoelectric vibrator 2 based on the measurement results obtained by the secondary compensation sensor 51 and the primary compensation sensor 52.

  FIG. 9 is a graph showing an example of frequency temperature characteristics of the piezoelectric oscillator 1 shown in FIG. 8, where the vertical axis represents frequency deviation (ppb) and the horizontal axis represents ambient temperature (° C.). FIG. 9 shows the case where the secondary temperature compensation sensor 51, the primary compensation sensor 52, and the resistors 53 and 54 in FIG. 8 are not included (ie, the frequency temperature characteristic L6 of the piezoelectric oscillator 1 shown in FIG. 8). The frequency temperature characteristic L7 is also shown when the control by the frequency control circuit 5 is not performed.

  FIG. 10 is a graph showing a relationship L8 between the voltage and the ambient temperature at the connection point a of the frequency control circuit 5 of the piezoelectric oscillator 1 shown in FIG. 11 shows the voltage generated by the secondary compensation circuit 5a of the frequency control circuit 5 of the piezoelectric oscillator 1 shown in FIG. 8 (that is, at the connection point a when the primary compensation sensor 52 and the resistor 54 are not provided). It is a graph which shows the relationship L9 of voltage) and ambient temperature. Further, FIG. 12 shows the voltage generated by the primary compensation circuit 5b of the frequency control circuit 5 of the piezoelectric oscillator 1 shown in FIG. 8 (that is, at the connection point a when there is no secondary compensation sensor 51 and resistor 53). The relationship L10 between the voltage and the ambient temperature is shown. 10 to 12, the vertical axis represents voltage (V), and the horizontal axis represents ambient temperature (° C.).

  When there is no secondary compensation sensor 51, primary compensation sensor 52, and resistors 53 and 54 (when control by the frequency control circuit 5 is not performed) as shown by L7 in FIG. 9, the piezoelectric oscillator shown in FIG. 1 has a frequency deviation that is quadratic with a change in ambient temperature in a range of about −25 ° C. to about 75 ° C., and the frequency deviation is minimum when the ambient temperature is about 35 ° C. .

  In the piezoelectric oscillator 1 shown in FIG. 8, as shown by L8 in FIG. 10, the frequency control circuit 5 has characteristics almost opposite to the frequency temperature characteristics shown in L7 in FIG. (Ie, in a range of about −25 ° C. to about 75 ° C., so that it changes in a quadratic function with respect to a change in ambient temperature and becomes a maximum around 35 ° C.) By controlling, the capacitance of the varicap diode 57 is changed.

  Specifically, when the ambient temperature changes, the secondary compensation circuit unit 5a including the secondary compensation sensor 51 and the resistor 53 of the frequency control circuit 5 performs secondary compensation based on the temperature change of the transistor 32. The resistance value of the sensor 51 changes in a quadratic function, and a voltage that changes in a quadratic function with respect to the change in ambient temperature as shown by L9 in FIG. 11 is generated. That is, based on the measurement result of the secondary compensation sensor 51, a voltage for compensating the secondary component of the frequency temperature characteristic indicated by L7 in FIG. 9 is generated.

  At the same time, in the primary compensation circuit unit 5b configured by the primary compensation sensor 52 and the resistor 54 of the frequency control circuit 5, the resistance value of the primary compensation sensor 52 is primary based on the change in ambient temperature. A voltage that varies functionally and varies linearly with a change in ambient temperature as indicated by L10 in FIG. 12 is generated. That is, based on the measurement result of the primary compensation sensor 52, a voltage for compensating the primary component of the frequency temperature characteristic indicated by L7 in FIG. 9 is generated.

  Then, the voltage generated in the secondary compensation circuit unit 5a and the voltage generated in the primary compensation circuit unit 5b are added together, and at the connection point a, the ambient temperature as indicated by L8 in FIG. A control voltage having a temperature characteristic almost opposite to the frequency temperature characteristic L7 is generated to change the capacitance of the varicap diode 57.

  The piezoelectric oscillator 1 shown in FIG. 8 includes a temperature control unit 4 and a constant temperature bath 7 and is configured not to be affected by the ambient temperature, and performs the operation as described above in the frequency control circuit 5. Thus, the capacitance of the varicap diode 57 is changed in accordance with the change in the ambient temperature, the frequency of the piezoelectric vibrator 2 is controlled, and the frequency temperature characteristic of the piezoelectric oscillator 1 is adjusted. Therefore, as indicated by L6 in FIG. 9, the frequency deviation can be made substantially constant as compared with the case where the secondary compensation sensor 52, the primary compensation sensor 51, and the resistors 53 and 54 are not provided. That is, it is possible to reduce frequency fluctuations with respect to changes in ambient temperature.

  Further, the frequency control circuit 5 of the piezoelectric oscillator 1 shown in FIG. 8 uses the temperature change of the transistor 32 of the heater unit 3 that changes in a quadratic function with respect to the change in the ambient temperature and the change in the ambient temperature. The frequency of the piezoelectric vibrator 2 is controlled, and the primary component and the secondary component of the frequency temperature characteristic of the piezoelectric oscillator 1 can be compensated with a relatively simple circuit configuration.

<Embodiment 2>
FIG. 13 is a block diagram showing the piezoelectric oscillator 1 according to Embodiment 2 of the present invention.

  The basic configuration of the piezoelectric oscillator 1 according to the present embodiment is substantially the same as that of the piezoelectric oscillator 1 according to the first embodiment, and only differences from the piezoelectric oscillator 1 according to the first embodiment will be described below. To do.

  In the piezoelectric oscillator 1 according to the present embodiment, the heater unit 3 includes a pair of transistors 33 and 34 that are Darlington-connected and a heater resistor 31 (see FIG. 15 described later).

  The relationship between the power consumption of the heater unit 3 and the ambient temperature is substantially the same as the relationship between the power consumption of the heater unit 3 and the ambient temperature in the piezoelectric oscillator 1 according to Embodiment 1 shown in FIG.

  That is, when the temperature of the piezoelectric vibrator 2 measured by the temperature control sensor 41 is controlled to be substantially constant, the pair of transistors 33 and 34 connected in Darlington range from about −40 ° C. to about 75 ° C., respectively. The power consumption fluctuates in a quadratic function with respect to changes in ambient temperature. The power consumption of the entire heater unit 3 (that is, the total power consumption of the transistors 33 and 34 and the heater resistor 31) decreases in proportion to the increase in ambient temperature in the range of about −40 ° C. to about 75 ° C. Fluctuates linearly with changes in ambient temperature.

  For this reason, in the piezoelectric oscillator 1 according to the present embodiment, the secondary compensation sensor 51 is disposed in the vicinity of one of the pair of transistors 33 and 34, and the temperature measured by the secondary compensation sensor 51. Similarly to the secondary compensation sensor 51 according to the first embodiment, it also fluctuates in a quadratic function with respect to a change in ambient temperature.

  Further, the current of the heater unit 3 varies in a linear function with respect to the change in the ambient temperature, similarly to the change in the power consumption indicated by L1 in FIG.

  Therefore, in the piezoelectric oscillator 1 of the present embodiment, the frequency control circuit 5 implements the following frequency control method.

  That is, the piezoelectric oscillator 1 according to the present embodiment is configured to change the temperature around the piezoelectric oscillator 1 among the plurality of elements (the heater resistor 31 and the transistors 33 and 34) constituting the heater unit 3 by the secondary compensation sensor 51. On the other hand, the temperature change of one element (transistor 33) whose power consumption fluctuates in a quadratic function is measured (element temperature measurement step). The frequency control circuit 5 performs piezoelectric vibration based on the measurement result in the element temperature measurement step and the change in the current of the heater unit 3 that varies in a linear function with respect to the temperature change around the piezoelectric oscillator 1. The frequency of the child 2 is controlled (frequency control step).

  More specifically, the frequency control circuit 5 compensates for the secondary component of the frequency temperature characteristic of the piezoelectric oscillator 1 by using the temperature change of the transistor 33 that varies in a quadratic function with respect to the change in ambient temperature. At the same time as generating the control voltage, the control voltage for compensating the primary component of the frequency temperature characteristic of the piezoelectric vibrator by utilizing the change in the current of the heater unit 3 that fluctuates in a linear function with the change in the ambient temperature. The frequency of the piezoelectric vibrator 2 is controlled by being generated.

  By controlling the frequency of the piezoelectric vibrator 2 in this way, the piezoelectric oscillator 1 according to the second embodiment can suppress the frequency fluctuation due to the change in the ambient temperature as in the first embodiment. Yes. Further, since it is not necessary to provide the primary compensation sensor 52 as compared with the first embodiment, the number of components is small, and the piezoelectric oscillator 1 can be further downsized.

-Structural example of piezoelectric oscillator 2-
Next, an example of the structure of the piezoelectric oscillator 1 according to the second embodiment of the present invention will be described with reference to FIGS.

  FIG. 14 is a perspective view showing an example of the structure of the piezoelectric oscillator 1 according to Embodiment 2 of the present invention. FIG. 15 shows the substrate 8 constituting the piezoelectric oscillator 1 shown in FIG. 3 is a schematic plan view showing a positional relationship among a heater unit 3, a temperature control sensor 41, and a secondary compensation sensor 51. FIG.

  The structural example 2 of the piezoelectric oscillator 1 according to the present embodiment is substantially the same as the structural example 1 of the piezoelectric oscillator 1 according to the above-described first embodiment, and only differences from the structural example 1 will be described below.

  In the present structural example, the heater section 3 includes a pair of transistors 33 and 34 that are Darlington-connected and a heater resistor 31, as shown in FIG.

  The secondary compensation sensor 51 is disposed in the vicinity of one transistor 33 of the heater unit 3. Specifically, the secondary compensation sensor 51 is provided inside the thermostatic chamber 7, and is provided at a position facing the transistor 33 and the substrate 8 on one main surface 80 of the substrate 8. In the second structural example, the secondary compensation sensor 51 is provided in the vicinity of the transistor 33, but may be provided in the vicinity of the transistor 34.

  In the second structural example, the primary compensation sensor 52 provided in the piezoelectric oscillator 1 shown in FIG. 4 is omitted.

-Electrical configuration example of piezoelectric oscillator 2-
Next, an example of the electrical configuration of the piezoelectric oscillator 1 according to the second embodiment of the present invention will be described with reference to FIG.

  FIG. 16 is a circuit diagram showing an example of the electrical configuration of the piezoelectric oscillator 1 according to the second embodiment of the present invention.

  The electrical configuration example 2 of the piezoelectric oscillator 1 according to the present embodiment has substantially the same configuration as the electrical configuration example 1 of the piezoelectric oscillator 1 according to the first embodiment. Only the differences will be described.

  The electrical configuration of the piezoelectric oscillator 1 shown in FIG. 16 is different from the electrical configuration (electrical configuration example 1) of the piezoelectric oscillator 1 shown in FIG. 8 in the configurations of the heater unit 3 and the frequency control circuit 5.

  That is, in the piezoelectric oscillator 1 shown in FIG. 16, the connection point g between the output terminal of the operational amplifier 46 and the resistor 45 is connected to the base of the transistor 34 via the resistor 47. The transistor 34 has an emitter terminal connected to the base of the transistor 33 and a collector terminal connected to the collector terminal of the transistor 33. That is, the transistors 33 and 34 are Darlington connected. A connection point h between the collector terminal of the transistor 34 and the collector terminal of the transistor 33 is connected to one terminal of the heater resistor 31. The other terminal of the heater resistor 31 is connected to the power supply voltage (Vcc), and the emitter terminal of the transistor 33 is grounded.

  According to the electrical configuration as described above, compared to the electrical configuration example 1 described above, the degree of increase / decrease in the current flowing through the heater resistor 31 accompanying the increase / decrease in the output voltage of the operational amplifier 46 is determined by a pair of transistors connected in Darlington Since it can be amplified by 33 and 34, it becomes possible to control the temperature of the piezoelectric vibrator 2 with higher accuracy.

  In the frequency control circuit 5 of the piezoelectric oscillator 1 shown in FIG. 16, the frequency control circuit 5 includes a secondary compensation sensor 51, resistors 53, 55, 56, 58, and a varicap diode 57.

  That is, one terminal of the resistor 53 is connected to one terminal of the secondary compensation sensor 51 that measures the temperature change of the transistor 33, and the other terminal of the resistor 53 is connected to one terminal of the resistor 58. The other terminal of the resistor 58 is connected to a connection point i between the pair of transistors 33 and 34 and the heater resistor 31 that are Darlington-connected.

  The connection point j of the resistors 53 and 58 is connected to one terminal of the resistor 55. Further, the connection point k is connected to one terminal of the piezoelectric vibrator 2 connected in series and the cathode terminal of the varicap diode 57. Are connected to the connection point b. The other terminal of the resistor 55 is grounded. Further, one terminal of the resistor 56 is connected to the anode terminal of the varicap diode 57, and the other terminal of the resistor 56 is grounded.

  In the piezoelectric oscillator 1 shown in FIG. 16, as with the piezoelectric oscillator 1 shown in FIG. 8, the frequency control circuit 5 causes the frequency characteristic indicated by L <b> 7 in FIG. The junction point j has a characteristic (ie, changes in a quadratic function with respect to a change in ambient temperature in the range of about −25 ° C. to about 75 ° C., and becomes maximum at about 35 ° C.). Is controlled to change the capacitance of the varicap diode 57.

  Specifically, when the ambient temperature changes, in the secondary compensation circuit unit 5 a configured by the secondary compensation sensor 51 of the frequency control circuit 5 and the resistor 53, the secondary compensation sensor is based on the temperature of the transistor 33. The resistance value 51 changes, and a voltage that varies in a quadratic function with respect to the change in ambient temperature as shown by L9 in FIG. 11 is generated. That is, based on the measurement result of the secondary compensation sensor 51, a voltage for compensating the secondary component of the frequency temperature characteristic indicated by L7 in FIG. 9 is generated.

  At the same time, in the primary compensation circuit unit 5b constituted by the resistor 58 of the frequency control circuit 5, the heater current whose current value fluctuates in a linear function with respect to the change in the ambient temperature is changed to L10 in FIG. As shown, a voltage that varies in a linear function is generated with respect to a change in ambient temperature. That is, based on the change in the heater current, a voltage is generated that compensates for the primary component of the frequency temperature characteristic indicated by L7 in FIG.

  Then, the voltage generated in the secondary compensation circuit unit 5a and the voltage generated in the primary compensation circuit unit 5b are added together, and at the connection point j, the ambient temperature as indicated by L8 in FIG. A control voltage having a temperature characteristic almost opposite to the temperature characteristic of the frequency is generated to change the capacitance of the varicap diode 57.

  The piezoelectric oscillator 1 shown in FIG. 16 includes a temperature control unit 4 and a constant temperature bath 7 and is configured not to be affected by the ambient temperature, and performs the operation as described above in the frequency control circuit 5. Thus, the frequency temperature characteristic of the piezoelectric oscillator 1 is adjusted by changing the capacitance of the varicap diode 57 according to the change in the ambient temperature and controlling the frequency of the piezoelectric vibrator 2. Therefore, as indicated by L6 in FIG. 9, the frequency deviation can be made substantially constant as compared with the case where the control by the frequency control circuit 5 is not performed. That is, it is possible to reduce frequency fluctuations with respect to changes in ambient temperature.

  Further, in the frequency control circuit 5 of the piezoelectric oscillator 1 shown in FIG. 16, the temperature change of the transistor 33 of the heater unit 3 that changes in a quadratic function with respect to the change of the ambient temperature, and the change of the current of the heater unit 3. The frequency of the piezoelectric vibrator 2 is controlled by using it, and the primary and secondary components of the frequency temperature characteristic of the piezoelectric oscillator 1 can be compensated with relatively few parts.

  Further, in the frequency control circuit 5 of the piezoelectric oscillator 1 shown in FIG. 16, the frequency temperature characteristic 1 of the piezoelectric oscillator 1 is changed based on the change in the current of the heater unit 3 that changes in a linear function with respect to the change in the ambient temperature. Since the compensation of the secondary component is performed, it is not necessary to provide a primary compensation sensor, and the primary component of the frequency temperature characteristic of the piezoelectric oscillator 1 is compensated with fewer parts than the piezoelectric oscillator 1 shown in FIG. be able to.

  Although the embodiments of the present invention have been described above, in the piezoelectric oscillator according to the present invention, the heater unit is capable of heating the piezoelectric vibrator by adjusting the amount of heat released by the temperature control unit. For example, any element may be used, and the present invention is not limited to the element including the heater resistor and the transistor described above. Further, the number of elements constituting the heater section may be two or more, and is not particularly limited.

  In the piezoelectric oscillator according to the present invention, the element whose temperature change is used for frequency control in the frequency control circuit is at least one of a plurality of elements constituting the heater section, and the ambient temperature change. However, any element may be used as long as the power consumption varies in a quadratic function, and the element is not limited to the above-described transistor. For example, a heater resistor may be used.

  In the first and second embodiments described above, the frequency control circuit 5 constitutes the heater unit 3 in which the power consumption of the frequency of the piezoelectric vibrator 2 fluctuates in a quadratic function with respect to a change in ambient temperature. Although it is configured to control based on a change in ambient temperature or a change in current in the heater unit 3 along with a temperature change of one element, for example, a configuration that is not easily affected by a change in ambient temperature by including a thermostatic bath The frequency control circuit 5 sets the frequency based only on the temperature change of one element constituting the heater unit 3 whose power consumption fluctuates in a quadratic function with respect to the change of the ambient temperature. You may control.

  In the first and second embodiments described above, the frequency control circuit 5 compensates the primary component of the frequency temperature characteristic of the piezoelectric oscillator 1 by the temperature measured by the primary compensation sensor 52 or the current of the heater unit 3. Is compensated for the primary component of the frequency temperature characteristic of the piezoelectric oscillator 1 based on both the temperature measured by the primary compensation sensor 52 and the change in the current of the heater unit 3. May be.

  Further, in the first and second structural examples 1 and 2, the secondary compensation sensor 51 is provided at a position facing the transistors 32 and 33 with the substrate 8 interposed therebetween. The compensation sensor 51 may be disposed in the vicinity of the transistors 32 and 33. For example, the secondary compensation sensor 52 may be provided adjacent to the transistors 32 and 33 without using the substrate 8. .

  In the first and second embodiments described above, the thermostatic chamber 7 is provided, and by heating the inside of the thermostatic chamber 7 by the heater unit 3, the piezoelectric vibrator 2 is indirectly heated by the heater unit 3. However, for example, when used in an environment where the change in the ambient temperature is small, the thermostatic chamber 7 may not be provided. In this case, the piezoelectric vibrator 2 may be directly heated by the heater unit 3. . That is, the piezoelectric oscillator according to the present invention may not include a thermostatic chamber, and the heater unit may warm the piezoelectric vibrator directly or indirectly.

  Further, in Structure Example 1 and Structure Example 2 of Embodiments 1 and 2 described above, the thermostatic chamber 7 in which the piezoelectric vibrator 2 is housed is configured by a metal case 72 (a constant temperature case) and a constant temperature portion 71. The thermostatic chamber may be made of a heat conductive material that seals the piezoelectric vibrator, for example, an aluminum block.

  Further, in the piezoelectric oscillator according to the present invention, the structure and the electrical configuration thereof include an oscillating unit including a piezoelectric vibrator and an oscillating circuit, and a heater unit for heating the piezoelectric vibrator constituted by a plurality of elements. A temperature control unit for controlling the amount of heat released from the heater unit to the piezoelectric vibrator, and power consumption with respect to a temperature change around the piezoelectric oscillator among the plurality of elements constituting the heater unit. Any one may be used as long as it has a frequency control circuit that controls the frequency of the piezoelectric vibrator based on a temperature change of one element that varies in a quadratic function. However, the present invention is not limited to the structural example 2, the electrical configuration example 1, and the electrical configuration example 2.

  That is, the present invention can be implemented in various other forms without departing from the spirit or main features thereof. For this reason, the above-described embodiment is merely an example in all respects and should not be interpreted in a limited manner. The scope of the present invention is indicated by the claims, and is not restricted by the text of the specification. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Piezoelectric oscillator 2 Piezoelectric vibrator 3 Heater part 31 Heater resistance 32, 33, 34 Transistor 4 Temperature control part 41 Temperature control sensor (thermistor)
5 Frequency control circuit 51 Secondary compensation sensor (thermistor)
52 Primary compensation sensor (Thermistor)
6 Oscillating unit 6a Oscillating circuit 7 Constant temperature bath 71 Constant temperature unit 72 Metal case 8 Substrate 80 One main surface 81 Other main surface 82 Joint 9 Main body housing 91 Protective case 92 Base 93 External lead terminal

Claims (10)

A piezoelectric oscillator,
An oscillation unit including a piezoelectric vibrator and an oscillation circuit;
A heater for heating the piezoelectric vibrator composed of a plurality of elements;
A temperature control unit for controlling the amount of heat released from the heater unit to the piezoelectric vibrator;
The frequency of the piezoelectric vibrator is based on the temperature change of at least one element whose power consumption varies in a quadratic function with respect to the temperature change around the piezoelectric oscillator among the plurality of elements constituting the heater unit. And a frequency control circuit for controlling the piezoelectric oscillator. The piezoelectric oscillator according to claim 1,
The heater unit includes a transistor and a heater resistor as the element,
The frequency control circuit controls the frequency of the piezoelectric vibrator based on a temperature change of the transistor. The piezoelectric oscillator according to claim 1 or 2,
The frequency control circuit further controls the frequency of the piezoelectric vibrator based on a temperature change around the piezoelectric oscillator. The piezoelectric oscillator according to any one of claims 1 to 3,
The frequency control circuit further controls the frequency of the piezoelectric vibrator based on a change in current of the heater unit that varies in a linear function with respect to a change in temperature around the piezoelectric oscillator. Piezoelectric oscillator. The piezoelectric oscillator according to any one of claims 1 to 4,
A piezoelectric oscillator, further comprising a thermostatic chamber for maintaining the piezoelectric vibrator at a predetermined temperature, wherein the piezoelectric vibrator is arranged inside the thermostatic bath. The piezoelectric oscillator according to claim 5, wherein
A piezoelectric oscillator characterized in that the heater section is arranged outside the thermostat. The piezoelectric oscillator according to claim 5 or 6, wherein
The oscillator is disposed on one principal surface of the substrate;
Inside the substrate is provided a constant temperature portion for maintaining the piezoelectric vibrator at a predetermined temperature,
A constant temperature case for sealing the oscillation unit is provided on one main surface of the substrate,
The thermostatic chamber is constituted by the thermostatic part and the thermostatic case. In the frequency control method of the piezoelectric oscillator,
The piezoelectric oscillator includes an oscillation unit including a piezoelectric vibrator and an oscillation circuit, a heater unit for heating the piezoelectric vibrator composed of a plurality of elements, and a discharge from the heater unit to the piezoelectric vibrator. A temperature control unit that controls the amount of heat generated,
An element temperature measuring step for measuring a temperature change of one element whose power consumption fluctuates in a quadratic function with respect to a temperature change around the piezoelectric oscillator among the plurality of elements constituting the heater unit;
A frequency control step of controlling a frequency of the piezoelectric vibrator based on a measurement result in the element temperature measurement step. The frequency control method according to claim 8, wherein
An ambient temperature measuring step for measuring a temperature change around the piezoelectric oscillator;
In the frequency control method, the frequency control step further controls the frequency of the piezoelectric vibrator based on a measurement result in the ambient temperature measurement step. In the frequency control method according to claim 8 or 9,
The frequency control step further controls the frequency of the piezoelectric vibrator based on a change in current of the heater unit that varies in a linear function with respect to a temperature change around the piezoelectric oscillator. Frequency control method.

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